A sensitive and highly selective spectrophotometric method has been developed for the determination of titanium (IV) using 5-(2',4'-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (I), 5-(2'-methyl-4'-hydroxyphenylazo)-6-hydroxypyrimidine-2,4-dione (II) and 5-(4'-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (II) as chromogenic reagents Titanium(IV) forms insoluble red complexes in aqueous acidic medium, which can be made soluble by the action of anionic surfactant. The deep red coloured complexes, having an absorption maximum at 546, 566 and 595 nm, respectively. Beer's law is obeyed over the concentration range 0.02-1.80 mug mL(-1) of Ti (IV). For more accurate results, Ringbom optimum concentration ranges were found to be 0.05-1.70 mug mL(-1). The molar absorptivity, Sandell sensitivity and relative standard deviations were also calculated. Most of the foreign metal ions and anions do not produce any coloration with reagents (I-III) at the optimum conditions. Based on these results, a simple and direct Specrophotometric method with high selectivity and sensitivity was proposed. The method has been successfully applied for the determination of titanium in soil, geo-chemical and silicate rock samples.

Three fossil woods, collected from Late Jurassic-Early Cretaceous of Gebel Kamil in southwestern Egypt, were studied anatomically, and identified as Xenoxylon saadawii sp. nov. of the family Protopinaceae.

3-(1,1-Dioxadibenzothien-4-oyl)acrylic acid (1) was condensed with compounds containing active methylene groups under Michael reaction conditions to furnish the Michael adducts (lactones 2a-c, lactams 3a-c, ketones 4a,b). The behavior of these adducts toward the action of hydrazine hydrate were investigated. The compounds were tested for their biological properties.

Proton-ligand dissociation constant of 4-(4-nitrophenylazo)-3-methyl-1-(2-hydroxy-3-morpholinopropan-1-yl)-2-pyrazolin-5-one (NAMP) and metal-ligand stability constants of its complexes with some transition metal ions were measured potentiometrically in 0.1 M-KCl and 40 vol.% ethanol-water. The order of stability constants was found to be K(UO22+) > K(Ce3+) > K(La3+) > K(Mn2+) < K(Co2+) K(Zn2+) The dissociation constant pK(1)(H) of NAMP and the stepwise stability constants log K of its complexes were determined at different temperatures (298 K, 308 K, and 318 K). The corresponding thermodynamic parameters (DeltaG, DeltaH, and DeltaS) were derived and discussed. The dissociation process is nonspontaneous, endothermic, and entropically unfavourable. The formation of the complexes was found to be spontaneous, exothermic or endothermic (depending on the metal) and entropically favourable. The stoichiometries of the complexes were determined spectrophotometrically and conductometrically and indicate the formation of n(metal): n(ligand) = 1: 1 and 1: 2 complexes.

The aim of this paper is to get new critertia for spectral classification of some early type stars which depend on the flux in the UV region lambdalambda 1500-2500 by carrying out spectrophotometric analysis of observational ultraviolet data of stars obtained by the S2/68 Ultraviolet Sky Survey Telescope (UVSST) aboard the European Space Research Organization (ESRO) Satellite TD1. We have developed these new criteria based on the Intrinsic Ultraviolet Colour Index (IUI), and the Intrinsic Flux Ratio (IFR). Using these quantities we are going to represent the results of spectral classification of 323 early type stars mainly from spectral type B and A. The results of calculations of the Intrinsic Flux Ratios for the stars under investigation together with their Colour Temperatures (Tc) are given. Comparison between our suggested two new criteria with the MK classification system and Cucchairo (1980) classification system was carried out.

Three simple, accurate, sensitive and selective spectrophotometric methods (A, B and C) for the determination of famotidine (Fam) in bulk sample, in dosage forms and in the presence of its oxidative. metabolites are described. The first method A is based on oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measuring the decrease in absorbance of Amaranth dye (AM) at a suitable lambda(max) (521 nm). The methods B and C involve addition of excess cerric sulphate and determination of the unreacted Ce(IV) by decrease the red colour of chromotrope 2R (C2R) at lambda(max) 528 nm for method B or decrease the orange pink colour of rhodamine 6G (Rh6G) at lambda(max) 526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.1-2.4 mug mL(-1) for method A and 0.1-2.2 mug mL(-1) for methods B and C. The apparent molar absorptivity, Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.2-2.2 mug mL(-1) for method A and 0.2-2.0 mug mL(-1) for methods B and C. The stoichiometric ratio between the drug (Fam) and the oxidant (NBS or Ce4+) was estimated. The validity of the proposed methods were tested by analysing pure and dosage forms containing famotidine and in the presence of its oxidative degradates. Statistical treatment of the results reflects that the proposed procedures are precise, accurate and easily applicable for the determination of famotidine in pure form, in pharmaceutical preparations and in the presence of its oxidative degradates.

A new spectrophotometric method for the microdetermination of zinc is proposed. The method is based on complexation reaction of zinc(II) with the chromogenic agent 2,3-dichloro-6-(2-hydroxynaphthylazo)quinoxaline in the presence of cetyltrimethylammonium bromide (CTAB) and nonyl phenoxy polyetho-xyethanol (OP) in slightly basic medium containing 20% (v/v) ethanol. Under certain experimental conditions, Beer's law is obeyed over the range 0.02-0.80 mug ml(-1) of Zn2+ with molar absorptivity of 1.06 x 10(5) l Mol(-1) cm(-1) and Sandell sensitivity of 0.62 ng cm(-2). The limits of detection and quantification as well as the regression equation are also calculated. The relative standard deviation for ten determinations for sample containing 0.5 mug ml(-1) was found to be 1.15%. As compared with other methods, our method is highly sensitive and selective because of the complex has high, and sharp absorption band at 616 nm. In addition, the present method is simple and rapid, no heating, no extraction or standing is needed. The proposed method has been applied successfully to the spectrophotometric determination of trace amounts of zinc in some alloys and ore samples.

A theoretical analysis of the migration of nuclides leaching out of a repository is presented. The analysis is applicable to a situation where the diffusion and convection process can be described by (1+ 2) dimension elliptic partial differential equation (PDE). Explicit mathematical formulas have been derived, using symmetry method, for the pore-water concentration of nuclides. By means of a parametric study the effect of cracking on the transport of radionuclides, groundwater velocity and diffusion coefficients on nuclide migration are elucidated. The results indicate that the migration rate in the surrounding geomedium is manageable through the cracks with factor depends on the various parameters of the disposal-vault conditions. (C) 2002 Elsevier Science Inc. All rights reserved.

Four glasses of (V2O5)(0.3)-(P2O5)(0.6)-(MO)(0.1) where MO=(TeO2, GeO2, Bi2O3 or P2O5) were prepared by melting the appropriate amounts of V2O5, MO and (NH4)(2)HPO4 in an open crucible. The structures of the virgin and annealed glasses (at 673 K for 24 h) were studied using density. FT-IR, X-ray diffraction (XRD). electron spin resonance (ESR) and scanning electron microscope (SEM). The electrical conductivity (sigma), dielectric constant (epsilon') and dielectric loss (epsilon") for the virgin and annealed lasses are investigated over a temperature range between 78 and 450 K and at a frequency from dc to 10(6) Hz. At low temperatures the conductivity data are explained on the basis of variable range hopping mechanism, while at high temperatures the Mott's models of phonon assisted polaronic conductivity is consistent with the conductivity data. The ac-conductivity increased with frequency according to sigma(ac)(omega) = Aomega(s), where s has a value depending on the temperature and the composition of the sample and ties in the range 0.45-0.85. One peak for each one of epsilon"-T plots has been observed at temperatures depending on the composition of the samples. Each of epsilon' and epsilon" was found to be dependent on the composition and the crystalline phases formed in the matrix. The effect of the framework composition of the glass on the physical proper-ties has been discussed.

The two-fold potential of F-2(+) center at the low coordinated surfaces of AgBr thin films in providing tunable laser activity and photographic sensitization is investigated using ab initio methods of molecular electronic structure calculations. The explicitly considered clusters were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. The neighbor ions nearest to the F-2(+) defect sites were allowed to relax to equilibrium in each case. As far as the tunable laser is concerned, F-2(+) laser activity increases significantly as the bromine coordination decreases from 5 (flat) to 4 (edge) to 3 (Br- corner). The smallest calculated Stokes-shift at the flat surface suggests that emission has the same oscillator strength as absorption. All relaxed excited states (RESs) are deep below the conduction bands of the perfect ground state surfaces. More than one band are expected for edge and corner surfaces. The Br- corner of AgBr is the least probable site for RES orientational destruction of F-2(+). The excited state at the corner has higher energy than that at the flat or at the edge surfaces. F-2(+) can be readily formed at the bromine corner relative to the flat and edge surfaces. The Glasner-Tompkins relation is generalized to include the reduced bromine coordination at the surfaces of the AgBr host. As far as photographic sensitization is concerned, while the alternating pattern of s(1) silver atoms in the vapor phase was retained, it was destroyed in the crystal environment. The F-2(+) defect containing surface of AgBr is developable with a minor activation energy barrier to electron transfer from the developer. Defect mobility makes electron transfer from the developer more facile in the process of visible image formation. About 58% of the reduction of silver ions at the flat surface of AgBr are attributed to the host anions and F-2(+) defect formation, leaving ca. 42% for the reduction of photoelectrons and developer molecules. The rotational diffusion of the central Ag-2 by 90degrees increases the last percentage to ca. 60%, but is hindered by an energy barrier of ca. 1.66eV. (C) 2002 Elsevier Science B.V. All rights reserved.

This paper treats a set of equations of the form X + A*F(X)A = Q, where F maps positive definite matrices either into positive definite matrices or into negative definite matrices, and satisfies some monotonicity property. Here A is arbitrary and Q is a positive definite matrix. It is shown that under some conditions an iteration method converges to a positive definite solution. An estimate for the rate of convergence is given under additional conditions, and some numerical results are given. Special cases are considered, which cover also particular cases of the discrete algebraic Riccati equation.

An attempt has been made to examine F-A(Ga+. In+. Tl+) tunable laser activity and adsorptivity of halogen atoms (F, Cl, Br, I, At) at the (001) surface of KCl crystal using an embedded cluster model, CIS and density functional theory calculations with effective core potentials. The ion clusters were embedded in a simulated Coulomb field that closely approximates the Madelung field at the host surface. The nearest neighbor ions to the defect site were then allowed to relax to equilibrium. Based on the calculated strength of electron-phonon coupling and Stokes-shifted optical transition bands, The F-A(Tl+) center was found to be the most laser active in agreement with the experimental observation that the optical emissions of F-A(In+) and F-A(Ga+) centers were strongly quenched. The disappearance of the anisotropy and np splitting observed in the absorption of F-A(Ga+, In+, Tl+) centers were monotonically increasing functions of the size of the impurity cation. The F-A(Ga+, In+, Tl+) defect formation energies followed the order F-A(Ga+) > F-A(In) > F-A(Tl+). The Glasner-Tompkins empirical relationship between the principal optical absorption of F centers in solids and the fundamental absorption of the host crystal was generalized to include the positive ion species. As far as the adsorptivity of the halogen atoms is concerned, the F and F-A(In+, Tl+) centers were found to change the nature of adsorption from physical adsorption to chemical adsorption. The adsorption energies were monotonically increasing functions of the electronegativity of the halogen and the amount of charge transferred from the defect-free surface. The calculated adsorption energies were explainable in terms of the electron affinity, the effective nuclear charge and the electrostatic potentials at the surface. The spin pairing mechanism played the dominant role in the course of adsorbate-substrate interactions and the KCl defect-free surface can be made semiconducting by For F-A(In+, Tl+) surface imperfections. (C) 2001 Elsevier Science B.V. All rights reserved.

The effect of rhodanine azosulpha drugs on the corrosion behaviour of 304 stainless steel in 1.0 M hydrochloric acid solution as corrosive medium has been investigated using weight loss and potentiostatic polarization techniques. Some corrosion parameters such as anodic and cathodic Tafel slope, corrosion potential, corrosion current, exchange current densities, surface coverage and inhibition efficiency were calculated. The polarization measurements indicated that the inhibitors are of mixed type and inhibit corrosion by parallel adsorption on the surface of steel due to the presence of more than one active centre in the inhibitor molecule. The adsorption is obeyed Langmuir adsorption isotherm. The activation energy and thermodynamic parameters were calculated at different temperature. (C) 2002 Elsevier Science Ltd. All rights reserved.

In this paper, we construct a restrictive type of Chebyshev rational approximation. It yields more accurate results and exact values at some selected points. We use this method to approximate the exponential function. We apply this approach to define a new implicit finite difference scheme to parabolic partial differential equations. This approach will exhibit several advantages features: highly accurate, fast, and the absolute error still very small whatever the exact solution is too large. Stability conditions are obtained and utilized in numerical computations. Finally, some numerical results to describe the performance of this approach are given. (C) 2002 Elsevier Science Inc. All rights reserved.

A fluorescent solar collector (FSC) based on Perylene-dye doped in poly (methyl methacrylate) (PMMA) has been suggested. A qualitative study shows that the Perylene dye with high fluorescence quantum yield and large Stokes shift can be used as a good activator for a FSC. After the FSC has been exposed to daylight illumination for one season (Summer 2000), the fluorescence quantum yield decreased and a new fluorescent band appeared. This new band is due to the dimers that exist only in the excited state (excimers). Also, the absorption spectra of Perylene dye was shifted to a longer waveleugth by exposure to sunlight, this leads to more overlapping between absorption and emission spectra and decreased the optical efficiency of the FSC. The optical efficiency of the FSC was measured and calculated hourly for one season. The average values of the optical efficiency for three positions were higher than those obtained in previous work. The photodegradation of the Perylene dye after 32 weeks exposure to daylight shows two decomposition rates. (C) 2002 Elsevier Science Ltd. All rights reserved.

The optical absorption of poly(methyl methacrylate) (PMMA), doped with perylene dye, prepared by both thermal polymerization and casting methods, has been measured before and after exposure to filtered or unfiltered light using xenon arc lamp or day light. The optical band gap of thermally polymerized PMMA was reduced by doping with perylene dye or exposure to UV radiation. Study of DSC and FTIR measurements confirmed that the samples prepared by thermal polymerization are more stable than solvent-cast samples. (C) 2002 Society of Chemical Industry.

4-(5,5-Dioxodibenzothiophen-2-yl)-4-oxo-2-butenoic acid (1) was condensed with compounds containing active methylene groups under Michael reaction conditions to form the Michael adducts 2a-c, 3a-c, and 4a-b. The behavior of Michael adduct towards the action of hydrazine hydrate was investigated. The compounds were tested for biological properties.

The reaction of quinazoline-4(3H)-thiones 2a-d with amino acid ester hydrochlorides in boiling solvents, under the basic catalysis, afforded the corresponding substitution products (3-6)a-e in low yield. The reaction could be improved by carrying it without a solvent yielding imidazo[1,2-c[- and pyrimido[1,2-c]quinazolines (7-10)a-e. The antibacterial and antifungal activities of the prepared compounds were tested.

Type I F-A (Rb+, Cs+) and II F-A (Li+, Na+) tunable laser activities, adsorptivity and donor-acceptor properties of O and O- adsorbates at the flat surface of KCl crystal were investigated using an embedded cluster model and ab initio, methods of molecular electronic structure calculations. Ion clusters were embedded in a simulated Coulomb field that closely approximates the Madelung field of the host surface, and the nearest neighbor ions to the defect site were allowed to relax to equilibrium. Based on the calculated Stokes shifted optical transition bands, F-A tunable laser activities were found to be inversely proportional to the size of the dopant cation (Li+, Na+, Rb+, Cs+) relative to the host cation (K+). This relation was explained in terms of the axial perturbation of the impurity cation. The probability of orientational bleaching attributed to the RES saddle point ion configuration along the (110) axis was found to be inversely proportional to the size of the dopant cation, with activation energy barriers of ca. 0.44-3.34 eV. Surface relaxation energies of type II F-A centers were more important than those of type I F-A centers. In terms of defect formation energies, the products of type II F-A center imperfection were more stable than those of type I F-A. The difference between F or F-A band energies and exciton bands depended almost exclusively on the size of the positive ion species. As far as the adsorptivity of O and O- is concerned, the results confirm that surface imperfection enhances the adsorption energies by ca. 4.38-16.37 eV. O and O- penetrate through the defect-containing surface. The energy gap between the adsorbate and the defect containing surface and the donor-acceptor property of adsorbate play the dominant role in the course of adsorbate substrate interactions and the results were explained in terms of electrostatic potential curves and Mulliken population analysis. (C) 2002 Elsevier Science Ltd. All rights reserved.

A series of dealuminated mordenites treated under various conditions of acid leaching was impregnated in an aqueous solution of ammonium heptamolybdate to achieve a loading of 12 wt% Mo. These samples were characterized by XRD, UV-DRS, N-2 adsorption, TGA, and FTIR techniques. Special attention was given to the far-IR measurements and IR study of surface hydroxyl groups before and after dealumination. A polymolybdate species was recognized by the appearance of bands at 344, 319, and 236 (229) cm(-1) due to the vibrational modes of delta(Mo-O) and delta(Mo-O-Mo), respectively. The disappearance of the 236 cm(-1) band as well as that at 344 cm(-1) in favor of the 319 cm(-1) band, with the dealumination, was related to the high dispersion of Mo species in the produced mesopore surface assessed by the N-2 adsorption at 77 K. No bands due to bulk MoO3 were detected from the IR and XRD results. A strong interaction between Mo species and dealuminated mordenite surfaces (OH groups) was recognized by a decrease in intensity and a marked shift of the band at 3745 to 3727 cm(-1) as well as the appearance of a new band at 3668 cm(-1). The latter band was produced by the interaction of the framework At-OH with Mo species. The BET surface areas of Mo-dealuminated mordenite samples were higher than the corresponding Mo-free ones. The diffuse reflectance measurements suggested that Mo cations are predominantly present as an octahedrally coordinated Mo6+, along with some tetrahedral Mo6+. New spectral features as a consequence of dealumination events in the far-IR range were evaluated and discussed. (C) 2002 Elsevier Science (USA).

We explore a notion of fuzzy T-neighbourhood spaces, for any continuous triangular norm T, and we present on this notion a unified treatment. Our theory, on one hand, generalizes the theory of Lowen (Fuzzy Sets and Systems 7 (1982) 65) from T = Min to arbitrary T, which has been the progenitor of this work, and on the other hand it is strongly related to the theory of L-neighbourhoods of Hohle (Mathematics of Fuzzy Sets: Logic, Topology and Measure Theory, Kluwer Academic Publishers, Dordrecht, 1999) (when L is restricted to the lattice [0, 1]). We study the T-neighbourhood bases and systems of our spaces, their level topologies, as well as their relationship to the Lowen-Hohle fuzzy T-uniformities (J. Math. Anal. Appl. 82 (1981) 370; Manuscripta Math. 38 (1982) 289) and to our fuzzy T-proximities (introduced in Part I). We show that the nearness concept underlying a fuzzy T-neighbourhood space is a fuzzy relation of closeness between its ordinary subsets and ordinary points. In particular, our spaces are in canonical one-to-one correspondence with the (T-)probabilistic topological spaces of Frank (J. Math. Anal. Appl. 34 (1971) 67). We demonstrate that each full subcategory T-FNS, of FTS, of fuzzy T-neighbourhood spaces is a topological category. To do that, we characterize T-FNS within FTS, and we characterize continuity of functions within T-FNS in terms of T-neighbourhood bases. (C) 2002 Elsevier Science B.V. All rights reserved.

This is the first one of three articles that are intended to be published consecutively in this journal. Together they constitute a three-part work on the unified subject of fuzzy T-neighbourhood spaces and their fuzzy T-proximities, where T stands for any continuous triangular norm. These new notions generalize. to arbitrary T, corresponding ones due to Artico, Hohle, Lowen and Moresco. In this part, we define and study notions of fuzzy T-proximity, one for each T. Their definition subsumes that of fuzzy proximity due to Artico and Moresco (Fuzzy Sets and Systems 21 (1987) 85), as our Min-proximity. In particular, we study proximity maps, the fuzzy topological space associated with a T-proximity (which, in the second part, will be proved a fuzzy T-neighbourhood space), T-proximities as fuzzy relations in (ordinary) power sets, T-proximal neighbourhood systems, and relationships to the Hohle-Lowen fuzzy T-uniformities (J. Math. Anal. Appl. 82 (1981) 370; Manuscripta Math. 38 (1982) 289). The second part of this three-part work will be concerned with the categories of fuzzy T-neighbourhood spaces, one for each T. Whereas we devote the third part to our T-separation axioms in those categories. (C) 2002 Elsevier Science B.V. All rights reserved.

In this paper, we consider the problem of when the equation X + A*X-2m A = I has a positive definite solution. An effective iterative procedure is presented for computing of a positive definite solution of this equation. Some properties of necessary and sufficient conditions for existence of a positive definite solutions are derived. Numerical results for a number of special cases are given. (C) 2002 Elsevier Science Inc. All rights reserved.

alpha-Benzylamino-beta-(5,5-dioxodibenzothiophen-2-carbonyl)propionic acid (1) has been synthesized by treating the corresponding beta-aroylacrylic acid with benzylamine in dry benzene. On treatment with hydrazine hydrate the keto acid I furnishes the corresponding pyridazinone derivative 2. The behaviour of 2 towards carbon electrophiles, namely, ethyl chloroacetate, acrylonitrile, formaldehyde and secondary amines (under Mannich reaction conditions), aromatic aldehydes and carbon nucleophiles, namely, POCl3/PCl3 and P2S5 has been investigated. The 3-chloropyridazine derivative 13 reacts with hydrazine hydrate to give the 3-hydrazino derivative 14. On treatment with ethyl acetoacetate and/or acetylacetone the hydrazine 14 undergoes cyclization to afford pyrazolone derivative 16 and 3-(3,5-dimethyl-pyrazol-1-yl)pyridazine derivative 17, respectively. On reaction with acetylhydrazine in boiling butanol and/or sodium azide in DMF the 3-chloropyridazine derivative 13 affords the triazolo[4,3-b]pyridazine 18 and the tetrazolo[1,5-b]pyridazine 19, respectively. The anti-microbial activity of the synthesized derivatives has been investigated.

This paper presents the use of symmetry reduction method resulting in new exact solutions for the groundwater flow and transport equation. It is assumed that the radionuclides are transported by advection-diffusion in a single fracture and diffusion in the surrounding rock-matrix. The application of one-parameter group reduces the number of independent variables, and consequently the governing PDE of (1 + 2)-dimension reduces to set of ODEs which are solved analytically. This enables us to present some new exact time-dependent solutions of the advection-diffusion equation.

The twofold potential of F-2(+) color center at the low coordinated surfaces of LiH in providing tunable laser activity and adsorption properties for atomic halogens is examined using ab initio calculations. Based on Stokes shifts of the examined clusters, the F-2(+) laser activity was very weak, but increases significantly as the coordination number decreases from 5 (flat) to 4 (edge) to 3 (H(-)corner). The corner site is the least probable for relaxed excited state orientational destruction of F-2(+). The exciton (energy) transfer takes place from the corner to the flat or edge sites. The Glasner-Tompkins relation is generalized to include the low coordinated surfaces of LiH. The F-2(+) color center change the nature of halogen-surface interaction from physical adsorption to chemical adsorption. The halogen-surface interactions were monotonically increasing functions of the electronegativity of the halogen and the amount of charge transferred between the halogen and the surface. The "covalent spin pairing" mechanism play the dominant role in the course of adsorbate-substrate interactions. (C) 2002 Elsevier Science B.V. All rights reserved.

A simple selective and highly sensitive extraction method has been developed for the determination of ruthenium spectrophotometrically after extraction of its 2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (I), 2,3-dichloro-6-(2-hydroxy-3,5-dinitrophenylazo)quinoxaline (II) and 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline (III) complexes into microcrystalline p-dichlorobenzene. The optimization of experimental conditions for the procedure is studied. The solid p-dichlorobenzene containing the ruthenium-reagent (I-III) complexes is separated by filtration and dissolved in N,N-dimethylformamide. The absorbance is measured at lambda(max) 622, 518 and 542 nm against reagents I, II and III, respectively, as blank. Beer's law is obeyed upto 2.5 mug ml(-1) of ruthenium. The molar absorptivity, Sandell sensitivity, detection and quantification limits are calculated, when compared with those parameters without using solid phase extraction method. The interference of various ions has been studied in detail and the statistical evaluation of the experimental results is reported. The proposed methods have been successfully applied for the determination of trace amount of ruthenium in seawater, ore and metallurgy products. (C) 2002 Published by Elsevier Science B.V.

The charge transfer complexes formed between some anilides and pi-electron acceptors [picric acid, 2,4-dinitrophenol, 3,5-dinitrobenzoic aicd, 3,5-dinitrosalicylic acid and m-dinitrobenzene] are synthesized and characterized. Spectral characteristics and stability of the complexes are investigated and discussed in terms of donor molecular structure, pi- acceptor electron affinity, and solvent polarity. It is deduced that the complexes are mainly of the n-pi* and pi-pi* type where the ground state wave function can be described primarily by the non-bonding structure. The optimum conditions favouring the formation of the coloured complexes are extensively studied for the micro determina-tion of anilides derivatives in pharmaceutical drugs using nitrobenzene as acceptor; the moleculor structure was found to be 1: 1 (D : A). Beer's law is obeyed up to 23.0, 18.60 and 16.0 mug ml(-1) for p(OH), p-(OCH3)(2) and p-N(CH3)(2), respectively.

The molecular complexes of some lanthanides scandium (Sc3+), yttrium (Y3+), lanthanum (La3+), gadolinium (Gd3+), cerium (Ce3+) and ytterbium. (Yb-3) have been studies in dimethyl formamide (DMF) spectrophtometrically equilibrium constants (K), molar extintion coefficient (epsilon), energy of transition (E) and free energy (DeltaG*) were calculated. The polymerization of acrylonitrile has been studied and investigated in the presence of Sc3+, Y3+, La3+, Gd3+, Ce3+, and Yb3+ ions. The IR spectra of the formed AN-M (III) Br-3 polymer complexes show the absence of the C=N band and the presence of two new bands corresponding to NH2 and OH groups. Magnetic moment values and the thermal stabilities of homopolymer and the polymer complexes were studied by means of thermogravimetric analysis and the activation energies for degradation were calculated.

The complex of tin(IV) with 5-(4'-nitro-2',6'-dichlorophenylazo) (I) and 5-(4'- chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (II) in the presence of nonyl phenoxy polyethoxyethanol (NPE) and cetyltrimethylammonium bromide (CTAB) has a sensitive absorption band with lambda(max) 517 and 488 nm, respectively, Under the optimal conditions, Beer-Lambert law is obeyed over the range 0.05-1.50 and 0.05-1.30 mug ml(-1) Sn(IV) with molar absorptivity being 9.50 x 10(4) and 1.05 x 10(5) L mol(-1) cm(-1) using ligand I and II, respectively. As compared with the visible methods which uses bromopyrogallol red (BPR) as the chromogenic reagent (lambda(max) = 550 nm) and that using phenylfluorone = 360 nm), our method is highly sensitive and selective because the complexes have a high and sharp absorption band. In addition, the present method is simple and rapid, no heating or standing time is needed. By means of the mixed surfactants, the precipitation caused by the ion association of cetyltrimethylammoniurn cation and I-3(-) anion is avoided if iodide is used for separating micro amounts of tin(IV) from a sample matrix. An application of the proposed method to the determination of tin(IV) in a variety of alloys and in a canned food was made with satisfactory results.

New spectrophotometric procedures have been established for the quantitation of piroxicam and tenoxicam. The procedures are based on the reaction between the examined drug and alizarin (I), alizarin red S (II), alizarin yellow G (III) or quinalizarin (IV) producing ion-pair complexes which can be measured at the optimum wavelength. The optimization of the reaction conditions is investigated. Beer's law is obeyed in the concentration ranges 0.05-2.40 mug ml(-1), whereas optimum concentration as adopted from Ringbom plots was 0.12-2.25 mug ml(-1). The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficient was greater than or equal to 0.9990 (n = 10) with a relative standard deviation (R.S.D.) of less than or equal to 1.2, for ten determinations of 1.0 mug ml(-1). The methods are successfully applied to the determination of piroxicam and tenoxicam in their pharmaceutical formulations. (C) 2002 Elsevier Science B.V. All rights reserved.

The notions of phi(0)-stability of systems of ordinary differential equations (ODEs) were introduced. In this paper, we will extend the phi(0)-stability notion to a new type of stability called total phi(0)-stability, and give some criteria and results. Our technique depends on Liapunov's direct method. (C) 2002 Elsevier Science Inc. All rights reserved.

The preparation of titania doped (0.63 - 3.2 mmol g(-1)) silica (TiO2/SiO2) was described together with a mixed oxide sample (TiO2-SiO2) at a nominal molar ratio near to 1. These materials were thoroughly characterized by XRD, N-2 adsorption at 76 K and ammonia adsorption measurements as well as FTIR spectroscopy. The activity of the materials towards 1-butene isomerization was also tested. FTIR results showed a band at 612 cm(-1) attributed to bulk TiO2 phase, in the doped 3.2 mmol g(-1) TiO2/SiO2 Sample, that was paralleled to an exhibited perturbation for the SiO2 bands in the low frequency region, specifically those at 470 and 808 cm(-1). The former band was similarly obtained in the TiO2-SiO2 sample, with a lower decrease in intensity, together with the appearance of a new band at 948 cm(-1) attributed to Ti-O-Si linkages. This deed indicated the decrease in population of Ti-O-Ti bridges in the mixed oxide sample. FTIR spectra of adsorbed D2O established the presence of different types of titania hydroxyl groups (3615 and 3520 cm(-1)) that were composed during desorption of water from the titania surface. The activity towards 1-butene isomeriztion was found to increase gradually, in the doped samples, to achieve its maximum at the titania loading 3.2 mmol g(-1), however, a tremendous decrease was obtained for the mixed oxide sample. This behavior was correlated with the acidity of the samples. The dependence of the reaction on either Ti-O-Ti or Ti-O-Si sites was evaluated and discussed. (C) 2002 Published by Elsevier Science B.V.

The twofold potentials of F-A(I):Au+ and F-A(II)Cu+ color centers at the low coordinated surfaces of AgBr thin films in providing tunable laser activity and photographic sensitization were investigated using ab initio methods of molecular electronic structure calculations. Clusters of variable size were embedded in simulated Coulomb fields that closely approximated the Madelung fields of the host surfaces, and the nearest neighbor ions to the F-A defect site were allowed to relax to equilibrium in each case. Based on the calculated Stokes shifted optical transition bands and horizontal shifts along the configuration coordinate diagrams, both F-A(I):Au+ and F-A(II):Cu+ color centers were found to be laser active. The laser activity faded quickly as the bromide ion coordination decreased from 5 (flat) to 4 (edge) to 3 (corner) and as the size of the impurity cation increased from Cu+ to Au+. The latter relation was explainable in terms of the axial perturbation of the impurity cation. The smallest calculated Stokes-shift at the corner surface strength as absorption. All relaxed excited states RESs of the defect containing surfaces were deep below the lower edges of the conduction bands of the defect free ground state surfaces, indicating that F-A(I):Au+ and F-A(II):Cu+ are suitable laser defects. The probability of orientational destruction of the two centers attributed to the assumed RES saddle point ion configurations along the axis was found to be directly proportional to the size of the impurity cation, with activation energy barriers of about 0.655-3.294 eV for Cu+. and about 1.887-3.404 eV for Au+. The possibility of exciton (energy) transfer front the sites of higher coordination to those of lower coordination is demonstrated. The more laser active F-A(II):Cu+ center was more easily formed than the less laser active F-A(I):Au+ center. The Glasner-Tompkins empirical relation was generalized to include F-A centers at the low coordinated surfaces of silver bromide thin film. As far as color photographic sensitization is concerned, the lowest unoccupied molecular orbitals of the selected dye molecules in the excited states were high enough for electron injection. F-A defect formation and rotational diffusion of silver clusters reduced the energy gaps between the excited dye molecules and the lower edges of the conduction bands and allowed for hole injection. About 54-60% of the reduction of silver ions at the flat surface of AgBr was attributed to the host anions and F-A defect formation, leaving about 40-46% for the reduction of photoelectrons as well as the electrons of the developer or dye molecules. The unrelaxed rotational diffusions of the central Ag-4 by 90degrees decreased the latter percentage, but were severely hindered by activation energy barriers. (C) 2002 Wiley Periodicals, Inc.

In this paper, we establish three iteration methods to compute solutions for a class of (weakly) singular two-point boundary value problems (x(alpha)y')' = f (x, y), where x is an element of (0, 1) and alpha < 2. We obtain the sufficient conditions for existence of a unique solution on R. Finally, we given some numerical examples. (C) 2002 Elsevier Science Inc. All rights reserved.

The interaction of 400 GeV/c protons and 340 GeV/c pi(-) with nucleons in nuclear emulsion has been investigated. The interaction mean free paths (m.f.p.) and the corresponding reaction cross-sections (sigma(in)) have been found, the multiplicity distributions for the events with N-h = 0 (clean events) are measured and studied as well as the angular and pseudorapidity distributions. Finally the coherent multiparticle production cross-sections (sigma(coh)) were estimated and compared with other data, where it was found to be increasing slowly with increasing incident momentum for protons while it increases rapidly with increasing pi(-)-momentum.

The UV, IR and H-1-NMR spectra of some 4-(R-phenyl azo) 1-hydroxy 2-naphthoic acid derivatives are studied. The effects of substituent groups and the solvent polarity on electronic spectral, IR bands and H-1-NMR proton chemical shifts are considered, the molecular orbital calculations obtained are rationalized quantitatively with that obtained practically using the PPP-model with configuration interaction (CI). (C) 2002 Elsevier Science B.V. All rights reserved.

A facile, rapid and sensitive methods for the determination of tetramisole hydrochloride in pure and in dosage forms are described. The procedures are based on the formation of coloured products with the chromogenic reagents alizarin blue BB (I), alizarin red S (II), alizarin violet 3R (III) and alizarin yellow G (IV). The coloured products showed absorption maxima at 605, 468, 631 and 388 nm for I-IV, respectively. The colours obtained were stable for 24 h. The colour system obeyed Beer's law in the concentration range 1.0-36, 0.8-32, 1.2-42 and 0.8-30 mug ml(-1), respectively. The results obtained showed good recoveries with relative standard deviations of 1.27, 0.96, 1.13 and 1.35%, respectively. The detection and determination limits were found to be 1.0 and 3.8, 1.2 and 4.2, 1.0 and 3.9 and finally 1.4 and 4.8 ng ml(-1) for I-IV complexes, respectively. Applications of the method to representative pharmaceutical formulations are represented and the validity assessed by applying the standard addition technique, which is comparable with that obtained using the official method. (C) 2002 Elsevier Science B.V. All rights reserved.

Five glasses of (Bi2O3)(x)-(B2O3)(I-x), x=0.06-0.26, have been prepared by melting in an open crucible. The density, thermal analysis and FT-IR spectra were measured. The softening temperature decreased with the bismuth oxide content in the sample. The x-ray diffraction confirmed the amorphous nature for the prepared samples. The molar volume was found to increase with Bi2O3 content in the glass matrix. The temperature dependence for the electrical conductivity sigma, dielectric constant epsilon' and dielectric loss epsilon" for these glasses were studied over a, temperature range from room temperature to 750 K and frequency from dc to 10(6) Hz. The mechanism of conduction was found to change with the temperature range of measurements. The electrical conductivity values increased with increasing mol % Bi2O3. The ac conductivity increased with frequency according to sigma(ac)(omega)=Aomega(s), where sigma has a value in the range 0.1-0.4 depending on the temperature and composition of the sample. The temperature dependence of the dielectric constant epsilon' showed that at relatively lower temperatures the electric dipoles formed in the glasses are frozen and starting to rotate at the softening temperature of the glass. Each of epsilon' and epsilon' was found to be dependent on the glass composition. The dielectric behaviour could be described according to the Debye-model for all results have been discussed and correlated together.

Gamma- irradiation effect on the kinetic parameters of the cation exchange reactions of Fe2+, Co2+ and Ni2+ ions on H- Mordenite has been studied. Kinetic analysis of the results according to the various theoretical models showed that the best fir of data is obtained of both non- irradiated and irradiated H- Mordenite with low doses from 2.2(.)10(6) to 4.6(.)10(6) Gy with three- dimensional diffusion controlled reaction (D-3), while the best fit is obtained for the 2- dimensional diffusion controlled reactions (D-2) by increasing the radiation dose to 5.5 (.)10(6) Gy. These investigations have shown that the possible reason for such behavior have been analyzed on the basis of gamma- irradiation may be caused desorption of the adsorbed ionic species.

The twofold potential of F+ color centers at the low coordinated surfaces of SrO for providing tunable laser activity and adsorption properties for atomic halogens (F, Cl and Br) has been investigated using ab initio electronic structure calculations. SrO clusters of variable sizes were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces and the nearest neighbor ions to F+ were allowed to relax to equilibrium. Based on Stokes shifted optical transition bands and horizontal shifts along the configuration coordinate diagrams, the F+ laser activity was found to decrease as the coordination number of the surface ions decreases from 5 (flat) to 4 (edge) to 3 (corner). An attempt has been made to explain this result in terms of Madelung potentials and optical-optical conversion efficiencies. All relaxed excited states are deep below the conduction bands of the perfect ground states, implying that F+ is a laser-suitable defect. The most laser active flat surface is the least probable for relaxed excited state orientational destruction of F+. The excited state at the edge has the highest energy, implying exciton (energy) transfer to the flat and edge sites. F+ relaxation and defect-formation energies increase with increasing surface coordination number. The Glasner-Tompkins relation between the fundamental optical absorption of F+ in solids and the fundamental absorption of the host crystals can be generalized to include the low coordinated surfaces of SrO. The F+ color center changes the nature of halogen-surface interaction (adsorption energies) from physical adsorption to chemical adsorption. The halogen-surface interactions increase with increasing electronegativity of the halogen. The calculated adsorption energies can be explained in terms of surface electrostatic potentials, and the covalent spin pairing mechanism plays a dominant role in determining adsorbate-substrate interactions.

The symmetry reduction of the master equation of a one-dimensional lattice-gas model with order preservation where the occupation probabilities of sites corresponding to Bose statistics as a consequence of the prescribed dynamics is studied. Some exact solutions are found. (C) 2002 Elsevier Science Inc. All rights reserved.

AC conductivity and dielectric studies on vanadium phosphate glasses doped with lithium have been carried out in the frequency range 0.2-100 kHz and temperature range 290-493 K. The frequency dependence of the conductivity at higher frequencies in glasses obeys a power relationship, sigma(ac) = Aomega(s). The obtained values of the power s lie in the range 0.5 less than or equal to s less than or equal to 1 for both undoped and doped with low lithium content which confirms the electron hopping between V4+ and V5+ ions. For doped glasses with high lithium content, the values of s less than or equal to 0.5 which confirm the domination of ionic conductivity. The study of frequency dependence of both dielectric constant and dielectric loss showed a decrease with increasing frequency while they increase with increasing temperature. The results have been explained on the basis of frequency assistance of electron hopping besides the ionic polarization of the glasses. The bulk conductivity increases with increasing temperature whereas decreases with increasing lithium content which means a reduction of the V5+. (C) 2002 Published by Elsevier Science Ltd.

In this paper the radial deformation and the corresponding stresses in a non-homogeneous hollow elastic cylinder rotating about its axis with a constant angular velocity is investigated. The material of the cylinder is assumed to the non-homogeneous and cylindrically orthotropic. The system of fundamental equations is solved by means of a finite difference method and the numerical calculations are carried out for the temperature, the components of displacement and the components of stress with the time t and through the thickness of the cylinder. The results indicate that the effect of inhomogeneity is very pronounced.

A simple and rapid spectrophotometric methods have been estimated for the microdetermination of phenylephrine HCl (I) and orphenadrine citrate (II). The proposed methods are based on the formation of ion-pair complexes between the examined drugs with alizarine (Aliz), alizarine red S (ARS), alizarine yellow G (AYG) or quinalizarine (Qaliz), which can be measured at the Optimum lambda(max). The optimization of the reaction conditions is investigated. Beer's law is obeyed in the concentration ranges 2-36 mug ml(-1), whereas optimum concentration as adopted from Ringbom plots was 3.5-33 mug ml(-1). The molar absorptivity, Sandell sensitivity, and detection limit are also calculated. The correlation coefficient was greater than or equal to0.9988 (n = 6) with a relative standard deviation of less than or equal to1.7, for six determinations of 20 mug ml(-1). The proposed methods are successfully applied to the determination of drugs I and II in their dosage forms using the standard addition technique. (C) 2002 Elsevier Science B.V. All rights reserved.

A simple, accurate, precise and sensitive colorimetric method for the determination of some beta-blockers as atenolol (Ateno), metoprolol (Metop), sotalol (Sot) and nadolol (Nad) is described. This method is based on the formation of charge transfer complex with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in methanolic-aqueous (for Ateno and Metop) or acetone-aqueous (for Sot and Nad) medium [30% (v/v)]. The orange color products are measured at 485, 470, 465 and 462 nm for Ateno, Metop, Sot and Nad, respectively. The optimization of various experimental conditions is described. Beer's law is obeyed in the range 0.4-60 mug ml(-1) while that obtained applying Ringbom is 0.8-56 mug ml-1. The molar absorptivity, Sandell sensitivity, detection and quantification limits are calculated. The results obtained showed good recoveries of 99.5+/-1.1, 100.3+/-1.2, 100.5+/-1.0 and 99.3+/-1.1% with relative standard deviations of 0.74, 0.98, 1.15 and 0.87% for Ateno, Metop, Sot and Nad, respectively. Applications of the proposed method to representative pharmaceutical formulations are successfully presented. (C) 2002 Elsevier Science B.V. All rights reserved.

Subharmonic resonance of two-degree-of-freedom systems with cubic non-linearities to multifrequency parametric excitations in the presence of three-to-one internal resonance is investigated. Two approximate methods (the multiple scales and the generalized synchronization) are used to construct first-order non-linear ordinary differential equations governing the modulation of the amplitudes and phases. Steady-state solutions and their stability are computed for selected values of the system parameters. The results obtained by the two methods are in excellent agreement. Numerical solutions are carried out and graphical representations of the results are presented and discussed. (C) 2002 Elsevier Science Inc. All rights reserved.

The notion of Lipschitz stability of impulsive systems of differential equations (DEs) was introduced. In this paper, we will extend the notion of eventual stability to impulsive systems of DEs and extend the notion of Lipschitz stability of impulsive systems of DEs to a new type of stability called eventual Lipschitz stability. Some criteria and results are given. Our technique depends on Liapunov's direct method and comparison principle. (C) 2002 Elsevier Science Inc. All rights reserved.

We present a simple method to estimate the distribution of mass, charge and excitation energy of the Au residual nuclei in Au (10.6 A GeV) + Em, in the framework of Glauber plus quantum molecular dynamics model. We apply it to the analysis of fragment correlations of Au as a function of bound charge. This method gives an opportunity to accurately estimate such correlations without any adjustments.

In this paper; the second-order symmetric Sturm-liouville differential expressions tau(1), tau(2),..., tau(n) with real coefficients are considered on the interval I = (a, b), - infinity less than or equal to a less than or equal to b greater than or equal to infinity. It is shown that the characterization of singular self-adjoint boundary conditions involves the sesquilinear form associated with the product of Sturm-Liouville differential expressions and elements of the maximal domain of the product operators, and it is an exact parallel of the regular case. This characterization is an extension of those obtained in [6], [8], [11], [12], [14] and [15].

In this paper we will extend the perturbing Liapunov function method to systems of functional differential equations and discuss phi(0)-equiboundedness and phi(0)-equistability properties via the concept of perturbing Liapunov functional.

Perturbing Liapunov function method was introduced for systems of ordinary differential equations. In this paper, we will extend this method to systems of functional differential equations and discuss stability and boundedness properties via the concept of perturbing Liapunov function. (C) 2002 Elsevier Science Inc. All rights reserved.

The kinetics of exchange of thorium and uranyl ions on Al-13-phosphatoantimonic acid (Al-13-PAA) was studied in nitrate solution at pH 1. The investigations were carried out under particle diffusion mechanism and the limited batch technique. The effects of particle size, concentration, and temperature have been studied. The effective diffusion coefficient, activation energy, and entropy of activation have been evaluated. The exchange capacity was evaluated and found to be 0.9 and 0.7 meq g(-1) for uranyl and thorium ions respectively.

A selective, reproducible, and sensitive spectrophotometric method for uranyl determination was developed. The method is based on the selective complexation reaction of UO22+ ions with 2-(2-benzothiazolylazo)phenol(l), -4-methoxyphenol (II), and -3-hydroxyphenol(III) in the presence of sodium lauryl sulphate. The potentiality of the prepared reagents as new chromogenic ones for the determination of UO22+ ions are studied by extensive investigations of the optimum conditions favoring the formation of the colored complexes. The of UO22+ method allows the determination, in the range of 0.05-1.60, 0.05-1.40, and 0.05-1.70 mug mL(-1) at lambda(max) 585, 608, and 599 nm using reagents I, II, and III, respectively. For more accurate results, Ringbom optimum concentration ranges were found to be 0.10-1.60 mug mL(-1). The molar absorptivity, Sandell sensitivity, detection, and quantification limits are also evaluated. The interfering ions and their tolerance limits have been studied. The method was successfully applied to the determination of uranium from standard ores, geological samples, and synthetic matrices.

Charge Transfer molecular complexes of Norfloxacin-[1-eihyl-6-fluoro-1,4-dihydro-4-oxo-7-(I-piperazinyl) 3-quinolone carboxylic acid] with m-dinitrobenzene, picric acid, 3,5-dinitrobenzoic acid and 3,5 dinitrosalicylic acid have been synthesized and characterized by elemental analysis as well as different spectroscopic techniques. Spectral characteristics. and stability of the-complexes are investigated and discussed in terms of donor molecular structure, pi-acceptor electron affinity, and solvent polarity. It is deduced that the complexes are mainly of-the,n-pi* and pi-pi* types. Ionization potential of the donor was estimated from the CT transition energies of their complexes. The potentiality of the electron acceptors as new chromophoric reagents for the spectrophotometric determination of Norfloxacin was studied by extensive investigation of optimum conditions favouring the formation,of the colored complexes.

The reaction of triazino benzo isothiazole sulphur dioxide with carbon electrophiles namely, alpha-cyanocinnamonitrile, alpha-ethoxycarbonyl cinnamonitrile, alpha-cyanocinnamamide, formaldehyde piperidine, and ethyl chloroacetate has been investigated. Also it reacted with chlorine nucleophile and gave the chloro derivative. Its behavior towards nitrogen nucleophiles namely, acylhydrazine, aminoacids, aminophenols, hydrazine hydrate, ammonium acetate and sodium azide has been discussed.

The 3-amino-4(3H)-quinazolinethiones 2a-c react with phenyl isothiocyanate in DMF, giving N,N-disubstituted thioureas 3a-c. When 2a-c are treated with phenyl isothiocyanate in dry acetonitrile in the presence of triethylamine, the mesoionic compounds 4a-c are isolated. The methiodide 5a reacts with carbon nucleophiles such as malononitrile and/or ethyl cyanoacetate in the presence of triethylamine to give the corresponding 1,2,4-triazoles 6a,b. On the other hand, compounds 2a-c react with CS2-K2CO3 combination to furnish 1,3,4-thiadiazolo[3,2-c]-4-quinazolinium-2-mercaptides 7a-c. Treatment of the methiodide 8a with malononitrile in the presence of potassium t-butoxide provides a mixture of 2-[2-(2-nitrophenyl)-3H-quinazolin-4-ylidene]malononitrile 9 (24%) and 2-amino-5-(2-nirophenyl)pyrazolo[1,5-c]quinazoline-1-carbonitrile 10 (40%). The reaction between Schiff bases 11 derived from 2a and phenacyl bromide yields 2-benzoyl-1,3,4-thiadiazino[3,2-c]quinazolin-5-ium bromide derivatives 12a,b. (C) 2003 Wiley Periodicals, Inc.

4-Allylthio-2-arylquinazolines 4a-c undergo cyclization by action of bromine to furnish 5-aryl-3-bromomethyl-2,3-dihydrothiazolo[3,2-c]qui-nazolin-4-ium bromides 5a-c. Compounds 5a-c undergo ring opening by action of water under acid catalysis to afford the corresponding dibromide derivatives 6a-c. Bromination of 3-allyl-2-aryl-4(3H)quinazolinethiones 7a-c leads to 5-aryl-2-bromomethyl-2,3-dihydrothiazolo[3,2-c]quinazolin-4-ium bromides 8a-c. However, anhydro-3-hydroxy-5-aryl-1,3-thiazolo[3,2-c]quinazolin-4-ium hydroxide 10a-c were prepared by the cyclodehydration of the corresponding thioglycolic acids 9a-c with Ac2O. (C) 2003 Wiley Periodicals, Inc.

Bacteriological and physicochemical parameters were determined in water samples collected from fifty-one producing wells used for human consumption in Taiz City (Yemen Republic) and its surroundings. Most water samples, especially from private wells, contained a high concentration of total coliforms which greatly exceeded the permissible limits recommended by the World Health Organization in 1996. Fecal coliforms were found in the majority of polluted sampled waters (65 % of the total of wells examined).

Given the significant low yield (19-43 %) in reported results on the cyclocondensation of sulfaguanidine acetate with chalcones, a careful reinvestigation was carried out. A new series of chalcones, bearing electron-attracting groups in the aromatic moiety, have been used as precursors in the synthesis of diphenylsulfapyrimidine acetates with good yield. All synthesized compounds were active against G(+)- and G(-)-bacteria, and fungi. Combination of substituents (Cl, OMe, NO2, etc.) enhanced antimicrobial activity. Derivative with two NO2 groups exhibit; an activity comparable with sulfadiazine.

Since a very low yield (19-43 %) in the reported results on the cyclocondensation of sulfaguanidine acetate with chalcones was given, a careful reinvestigation was carried out. New series of chalcones, bearing electron-attracting groups in the aromatic moiety, have been used as precursors in the synthesis of diphenylsulfapyrimidine acetates with good yield. The compounds were tested for their biological properties.

Dissociation constants of azosulfonamide derivatives of rhodanine have been determined potentiometrically in 0.1 M-KCl and 30 vol. % ethanol-water mixture. The data are discussed in terms of the electron nature of the substituents and of the change in temperature. The pK(1)(H) Values have been found to increase with increasing electron-donating nature of the substituents. The evaluated thermodynamic parameters (DeltaG, DeltaH, and DeltaS) indicated that the dissociation processes are not spontaneous, they are endothermic and entropically unfavourable.

The notion of eventual stability has been recently discussed. We extend this notion to impulsive systems of differential equations. Our technique depends on Liapunov's direct method. (C) 2002 Elsevier Science Inc. All rights reserved.

An analysis is presented for simultaneous primary resonances of two-degree-of-freedom system with quadratic and cubic nonlinearities to external excitations having the frequencies Omega(1) and Omega(2). The relations between the external frequencies of the system are such that they are excited into external resonances in two cases: the first case without internal resonances and the second case in the presence of different possibilities of internal resonances (one-to-one, two-to-one, three-to-one, one-to-two, and one-to-three). The method of multiple scales (MMS) is used to determine four first-order ordinary differential equations, which describe the modulation of the amplitudes and phases of both modes. In order to use the MMS properly, we introduce new detuning parameters of both modes. It is found analytically that two-mode responses can occur at each primary resonance. In all cases the steady-state solutions and their stability are determined. Numerical results depicting the resonances are presented. (C) 2002 Elsevier Science Inc. All rights reserved.

The CeO2-modified ZrO2 support was impregnated in an aqueous solution of ammonium heptamolybdate to achieve a loading of 8 wt.% Mo. This material (Mo/Zr(Ce)) was characterized, in comparison with Mo/Zr, by X-ray diffraction, FT-IR and UV-VIS diffuse reflectance spectroscopy as well as low temperature N, adsorption and electrical conductivity measurements. The X-ray results showed that the particles size of MoO3 on Zr(Ce) (24.7 nm) was lower than those on ceria free Zr (36.7 nm). The IR results indicated that a strong interaction between Mo species and zirconia was recognized in the Mo/Zr(Ce) sample by the appearance of a new band at 858 cm(-1) attributed to a Mo-O-Zr linkage, which was not detected in the Mo/Zr sample. The UV-VIS spectra showed that both octahedral (291 nm) and tetrahedral (249 nm) Mo6+ were detected in the Mo/Zr sample where tetrahedral arrangement (246 nm) was only adopted for Mo6+ in the Mo/Zr(Ce) sample. The addition of either Cc or Mo to zirconia causes a marked increase in the specific surface area of the samples. The conductivity measurements showed that all samples exhibit a semiconducting behavior. (C) 2002 Elsevier Science B.V. All rights reserved.

A comparison is made between a typical intranuclear cascade (INC) model and the experimental inclusive slow (T0.4 GeV) proton spectra in the p-C, C-C, and C-Ta in interactions at 3.3A GeV over a broad angular interval from 0degrees to 180degrees. It is found that the INC model reproduces rather well the inclusive slow and fast proton spectra, provided that the mean number of interacting protons (participants) in the corresponding angular interval does not exceed 2. The systematic discrepancies are identified and shown to correspond mainly to the noncovariant nature of the INC calculations.

A new kind of interference fringes, fringes of equal tangential inclination by curvature-induced birefringence, is presented. These are two-beam interference fringes produced by bending a thin sheet of birefringent material into a part of an exact cylinder such that the curvature is constant. Due to this curvature there is a uniform birefringence being induced. The change in birefringence induced by applying different radii of curvatures to a Fortepan sheet is measured. The stored (fixed) or natural birefringence of this sheet is deduced. (C) 2002 Elsevier Science Ltd. All rights reserved.

The do and ac conductivities as well as the dielectric constant (epsilon') were measured for different zeolites encapsulated gold (AuCl3) samples at different temperatures (300-500 K) and various frequencies (5 kHz-1 MHz). The conductivity was found to change in the order Au/FSM-27 > Au/NaY > Au/FSM-47. Sorbed water contained inside zeolites assists greatly the proton mobility (zeolite protons) and the ion mobility (Na+ and Au+) and hence enhance the electric conduction in the temperature range 300-373 K. Raising the temperature over 373 K induces dehydration effect that assists the metallic gold formation and thus a dramatic loss in conductivity was revealed. The conduction mechanism was expected to be partially ionic and partially electronic. The IR study showed that the exposure of Au zeolites to CO gas produced a characteristic band of Au+-CO at 2180 cm(-1) that tends to decrease with temperatures and even vanishes at 376 K in favor of Au-0-CO at 2128 cm(-1). Similarly, a phase transition at 338 K, that occurs in the range 300-376 K, was confirmed by DTA to further emphasize the temperature regions of either Au+ cations (338 K) or Au-0 (376 K) formation. (C) 2002 Elsevier Science Ltd. All rights reserved.

We address the problem of identifying a useful set of mutually compatible separation axioms for each category T-FNS of T-neighbourhood spaces. It should contain one of T-complete regularity that characterizes T-uniformizability, as indeed we achieve here. This seems to necessitate the parameterization of most separation axioms by the triangular norm T, with the exception of the two axioms T-0 and R-0, which have categorical definitions valid in any topological category. We introduce T-separation axioms in terms of T and fuzzy closure operators only; making them meaningful for the whole of FTS. We then characterize them within T-FNS in terms of T, fuzzy closures of crisp fuzzy subsets and T-neighbourhoods. We study our T-axioms and establish some entailments between, them. Our T-complete regularity commits us to investigate a "T-real line", which is a T-neighbourhood space induced by a certain probabilistic T-metric due to Hohle (Fuzzy Sets and Systems 1 (1978) 311). (C) 2002 Elsevier Science B.V. All rights reserved.

This paper is devoted to study the initial and final fuzzy uniform structures of the fuzzy uniform structure defined by the author and others in 1998. In this paper, we show that all initial and final lifts in the category FUN of these fuzzy uniform spaces and hence the initial and final fuzzy uniform structures exist. We introduce a characterization for the initial fuzzy uniform structures and as a special initial fuzzy uniform spaces the subspaces and product spaces of these fuzzy uniform spaces can be also characterized. We also show that the fuzzy topology (global homogeneous fuzzy neighborhood structure) associated to the initial fuzzy uniform structure of a family of fuzzy uniform structures coincides with the initial fuzzy topology (initial global homogeneous fuzzy neighborhood structure) of the family of fuzzy topologies (global homogeneous fuzzy neighborhood structures) associated to these fuzzy uniform structures. (C) 2002 Elsevier Science B.V. All rights reserved.

Thermal and electrical properties for pure and doped amorphous Al2O3 (by 1% Fe3+, Ni2+, CO2+) have been investigated. All samples changed to gamma-Al2O3 after annealing at 1200 K for 3 h. Electrical conductivity a, dielectric constant epsilon' and dielectric loss epsilon" were studied between 78 and 400 K and over a frequency range of 0-10(6) Hz. An anomalous behavior in In sigma-T-1 relation is observed for all samples. or-value increases in the order: sigma(Co-doped) > sigma(Ni-doped) > sigma(Fe-doped) > sigma(pure). At lower temperatures, semimetallic behavior was observed; while at moderate temperatures semiconducting behavior predominates with an activation energy decreases with the addition of the doping ions. The ac-conductivity was found to obey the power relation sigma(omega) = Aomega(s). epsilon'-value increased in the order: epsilon'(Co-doped) > epsilon'(Ni-doped) > epsilon'(Fe-droped) > epsilon'(pure). Both epsilon' and epsilon" showed maximum values at temperatures which are not changed by measuring frequencies. These maxima Fe-doped pure are slightly shifted to lower temperatures by adding the doping ions. The results have been discussed on the basis of the formation of Al-O dangling bonds in each of the pure and the doped Al2O3. (C) 2002 Elsevier Science B.V. All rights reserved.

New Ce(III), Th(IV) and U(VI) complexes with the aryl Schiff bases 2-hydroxybenzylamine-2'-hydroxybenzylidene (HL1), -2'-hydroxynaphthylidene (HL2), -2'-hydroxy-5'-bromobenzylidene (HL1), -2'-hydroxy-5'-chlorobenzylidene (HL4), 2'-hydroxy-3',5'-dichlorobenzylidene (HL5) and 2'-hydroxy-3-methoxybenzylidene (HL6) have been synthesized and characterized by elemental and thermal analyses, molar conductance, magnetic susceptibility, IR, H-1 NMR and electronic spectra. Elemental analyses along with conductometric titrations showed the formation of 1:1 and 1:2 (M:L) complexes while IR, molar conductance and H-1 NMR data proved that these ligands act as monobasic, tridentates for the 1: 1 and monobasic, bidentates for the 1:2 complexes with a coordination number of eight in both.

Three simple, accurate and sensitive colorimetric methods (A, B and C) for the determination of ranitidine HCl (RHCl) in bulk sample, in dosage forms and in the presence of its oxidative degradates are described. The first method A is based on the oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measurement of the decrease in absorbance of amaranth dye (AM) at a suitable lambda(max) = 520 nm. The methods B and C involve the addition of excess Ce4+ and determination of the unreacted oxidant by decrease the red color of chromotrope 2R (C2R) at a suitable lambda(max) = 528 nm for method B or decrease the orange pink color of rhodamine 6G (Rh6G) at a suitable lambda(max) = 526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.2-3.6, 0.1-2.8 and 0.1-2.6 mug ml(-1) for methods A, B and C, respectively. The apparent molar absorptivity. Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.3-3.4, 0.2-2.6 and 0.2-2.4 mug ml(-1) for methods A, B and C, respectively. Analyzing pure and dosage forms containing RHCl tested the validity of the proposed methods. The relative standard deviations were less than or equal to1.38 with recoveries 98.9-101.0%. (C) 2002 Elsevier Science B.V. All rights reserved.

A simple, fairly rapid, sensitive and accurate method is described for the colorimetric determination of neomycin sulphate (NMS), based on the measurement of the absorbance of the extracted organic soluble ion-association complex formed between neomycin dictation and a bulky counter anion. Different chromotropic acid azo dyes were examined as counter ions. The effect of pH, the counter ion concentration, sequence of addition and solvents for extraction were also illustrated. The most suitable system is based on reagent VIII (pH 7.5) with chloroform as the extraction solvent. The use of other counter ions, in conjunction with their respective solvents, was found to be less sensitive. The neomycin-reagent VIII system exhibits negligible or no interference when used for the determination of up to 5 8 mug ml(-1) of NMS in the presence of several drug excipiences. The method has been used for the determination of up to 58 mug ml(-1) with a good recovery (99.8 +/- 1.5%), and the precision is supported by the low relative standard deviation less than or equal to1.35%. The sensitivity is discussed and the results are compared with the official method. The proposed method was applied successfully to the determination of NMS in pure and dosage forms, with a good precision and accuracy compared to the official one. (C) 2002 Elsevier Science B.V. All rights reserved.

Quinazoline isothiocyanate 1 reacts with various nucleophiles (nitrogen nucleophiles, oxygen nucleophiles and sulphur nucleophiles) to afford heterocyclic systems 2-13. Also, the [ 4 + 2] cycloaddition reaction of 1 with phenyl isocyanate, benzylidene aryl amine and cinnamic acid derivatives gave novel heterocyclic compounds 14-16. Moreover, the reaction of 1 with active methylene compounds under Michael reaction conditions also was investigated. to yield 17 and 18 and it was found that all these reactions proceeded via isothiocyanate heterocyclization to furnish non-condensed heterocyclic compounds. Some of the newly synthesized compounds were tested for their antimicrobial activities.

A facile, rapid and sensitive spectrophotometric method for the determination of zinc is performed, based on complexation reaction between the metal ion and 1,5-diphenyl-3-acetylformazan (I) 1-(o-carboxyphenyl)-3-acetyl-5-acetylformazan (II), 1-(o-carboxyphenyl)-3-acetyl-5-phenylformazan (III), and 1-(o-carboxyphenyl)-3-acetyl-5-mtolylformazan (IV) in the presence of cationic surfactant cetylpyridinium chloride (CPC). The important analytical parameters and their effects on the reported system are investigated. Zinc reacts with the reagents (I-IV) and CPC in the ratio 1:1:2 (metal: reagent: CPC) in the pH range 8.5, 7.5, 5.5 and 6.5 to form a ternary complex with an absorption maximum 616, 656, 672 and 599 nm, respectively. The reaction was extremely rapid at room temperature, and the absorbance value remains unchanged for at least 1 week. The apparent stability constant of the complex were found to be 13.1 9.2, 11.4 and 12.3, and adheres to Beer's law for 0.05-3.50 mug per 10 ml of zinc. For more accurate analysis, Ringbom optimum concentration range was found from 0.08 to 3.20 mug per 10 ml of zinc. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. Taking a constant concentration of metal ion and determining its concentration in the presence of large number of foreign ions tested the effect of foreign ions. The method was applied for determination of zinc in serum, human hair and pharmaceutical formulations, where excellent agreements between reported and obtained results were achieved. The relative standard deviation was better than 1.67%. (C) 2003 Elsevier Science B.V. All rights reserved.

Solid-phase spectrophotometry (SPS) has been applied to analysis for trace amounts of vanadium in several environmental water (potable and polluted), biological samples (human blood and urine), and soil samples. Vanadium was sorbed in a styrene-divinylbenzene-type anion-exchanger Dowex 1-X8 as a vanadium-2,3-dichloro-6(3-carboxy-2-hydroxynaphthylazo)quinoxaline. Resin phase absorbances at 606 and 800 nm were measured directly which allowed the determination of vanadium in the range 0.03-2.2 ng ml(-1) with a relative standard deviation (R.S.D.) of 1.4%. The comparison of the SPS method and the gallic acid persulphate method shows that the linearity, analytical sensitivity, and precision were better for the SPS method, and that the latter method has lower detection and quantification limits compared with the gallic acid persulphate method. (C) 2002 Elsevier Science B.V. All rights reserved.

Fe was introduced in mordenite zeolite by means of ion exchange either in solid or in liquid state. The iron loading (50-200 wt%), iron precursor (FeSO4.7H(2)O and FeCl3), and mordenite starting material (NH4M, HM, and NaM) were varied during the exchange processes. The Fe species were characterized by N-2 adsorption measurements as well as by XRD and Mossbauer spectroscopies. The Fe-mordenite samples prepared by liquid-state ion exchange attained remarkable Fe dispersion and surface areas higher than those of the parent. It was found that Fe3+ ions, which substituted the framework Al and accordingly occupied tetrahedral sites, were decreased with Fe loadings with concomitant increase in Fe3+-occupied octahedral sites. The latter sites disappeared at 20 K to provoke the superparamagnetic alpha-Fe2O3 in different particles size. The acid leaching (0.1 M HCl, 333 K, 3 h) of the samples showed the disappearance of the most highly distorted extra-framework Fe3+ species, providing an indication of their presence on the external surface. On the other hand, a hematite phase was detected in the solid-state ion exchange of FeCl3 with either HM or NH4M at the loading of 100% Fe. More correlations between Mossbauer data on one hand and XRD and texturing properties on the other hand were evaluated and discussed. (C) 2003 Elsevier Science (USA). All rights reserved.

This paper aims to introduce a comparison of Adomian decomposition method and wavelet-Galerkin method for the solution of integro-differential equations. From the computational viewpoint, the comparison shows that the Adomian decomposition method is efficient and easy to use. (C) 2002 Published by Elsevier Science Inc.

Two methods are described for the determination of amodiaquine hydrochloride, chloroquine phosphate and primaquine phosphate, based on the formation of their ion-associates with [Cd2+, Co2+, Mn2+ and Zn2+] thiocyanate, ammonium reineckate and/or sodium cobaltinitrite. The molar combining ratio reveal that (1:1) (drug:reagent) ion associates are formed for all reagents except for ammonium reineckate which form (1:2) ion associates with all studied drugs. The optimum conditions for the ion-association have been studied. Conductometric method was applied for the direct determination of the suggested drugs in bulk powders, whereas indirect atomic absorption spectrometric method, depending on the measurement of the excess metal ion present in supernatant solutions after precipitation of the ion associates is used to calculate the drug concentration. Optimum concentration ranges for the determination of aminoquinoline antimalarial drugs under consideration were 0.46-12.90 and 0.155-3.87 mg using conductometric and indirect atomic absorption spectral methods, respectively. The proposed procedures have been applied successfully to the analysis of these drugs in certain formulations and the results are favourably comparable to the official methods. (C) 2002 Elsevier Science B.V. All rights reserved.

In this Letter, we dealt with finding the solutions of a generalized fifth order KdV equation (for short, gfKdV) by using the Adomian decomposition method (for short, ADM). We prove the convergence of ADM applied to the gfKdV equation. Then we obtain the exact solitary-wave solutions and numerical solutions of the gfKdV equation for the initial conditions. The numerical solutions are compared with the known analytical solutions. Their remarkable accuracy are finally demonstrated for the gfKdV equation. (C) 2003 Elsevier Science B.V All rights reserved.

A system of two degrees of freedom with quadratic and cubic nonlinearities and subjected to parametric and external excitations is studied and solved. The method of multiple scale perturbation technique (MSPT) is used to analyze the response of this system. Four ordinary differential equations are derived to describe the modulation of the amplitudes and phases of the two modes of vibrations for the principal parametric resonances. The steady-state solutions and their stability are determined and representative numerical results are included. The theoretical resonance cases of this system have been obtained from the first approximation differential equations and some of them are confirmed by applying well-known numerical technique. The stability of the obtained numerical solution is studied using phase-plane method. The effects of different parameters on the vibration of this system are investigated. (C) 2003 Published by Elsevier Science B.V. on behalf of IMACS.

Poly(methyl methacrylate) doped with fluorescent perylene dye was prepared by both radical polymerization of methyl methacrylate and solvent casting from polymer solutions. The samples were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, electrical conductivity, and dielectric properties. Both conductivity and dielectric properties were measured in the temperature range 303-433 K and the frequency range 10(3) to 5 x 10(6) Hz. The results show that the direct-current electrical conductivity increased by increasing dye content in solvent-cast samples, whereas it decreased radically polymerized samples. The results of alternating-current conductivity suggest electron hopping between filled and empty localized states. The study of dielectric properties showed two relaxation peaks corresponding to the dipole segmental and dipole group losses. Explanations based on the polymer free.,volume and acid-base interactions were proposed to examine the influence of the sample preparation and perylene dye concentration on the glass-transition temperature and dielectric relaxation of the samples. The obtained results recommend the thermal and molecular stability of luminescent solar concentrator (LSC) matrices prepared by radical polymerization over those prepared by solvent casting. (C) 2003 Wiley Periodicals, Inc.

Four rapid, simple, reproducible and sensitive methods (A - D) for assaying domperidone (1) and metoclopramide (11) in a bulk sample and in dosage forms were investigated. The first and second methods, A and B, are based on the oxidation of I and/or II by Fe3+ in the presence of o-phenanthroline (o-phen) or bipyridyl (bipy). The formation of tris-complex upon reactions with Fe3+-o-phen and/or Fe3+-bipy mixture in an acetate buffer solution of the optimum pH-values was demonstrated. Methods C and D involve the addition of excess Ce4+ and the determination of unreacted oxidant by a decrease of the red color of chromotrope 2R (C2R) at a suitable lambda(max) of 528 nm for method C, or a decrease in the orange pink color of Rhodamine 6G (Rh6G) at a suitable lambda(max) value of 525 nm for method D. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.2 - 5.8 mug ml(-1). The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. For a more accurate analysis, the Ringbom optimum concentration ranges are 0.35 - 5.6 mug ml(-1). The developed methods were successfully applied to the determination of domperidone and metoclopramide in bulk and pharmaceutical preparations without any interference from common excipients.

The ultrarelativistic quantum molecular dynamics (UrQMD) model is incorporated with a statistical decay model aiming to describe the neutron double global-differential cross sections of p+Al, Fe, and Zr at 1.2 GeV. Good agreement is generally obtained with the default UrQMD parameters. In particular, the UrQMD calculation with a momentum dependent Pauli potential improves the intensity of the quasielastic peak in neutron double-differential cross sections. The lower and higher energy parts of the neutron spectra at backward angles are found to be sensitive to meson-meson and meson-baryon interactions. The influence of sequential evaporation and simultaneous multifragmentation disintegration mechanisms on the neutron spectra is also investigated. It is shown that the statistical multifragmentation model is more suited for the description of the lower part of the neutron energy spectra.

Pitting corrosion of nickel and its alloys (Inconel 600 and Incoloy 800) in 0.1 M H2SO4 solution containing of NaCl was studied using cyclic voltammetry and potentiodynamic anodic polarization techniques. The integrated charge amounts Deltaq(a) in presence of Cl- ions was taken as a measure of pitting corrosion. The pitting potential was varied with Cl- ion concentrations according to an S-shaped curves. Addition of dihydrazide derivatives of malonic, succinic and adipic acid caused a shift of pitting potential in the noble direction accounting for increased resistance to pitting attack.

The thermodynamic metal-ligand stability constants of Be2+, Mg2+, Ca2+, Sr2+ and Ba2+ with P-methoxy salicyldehydineazo methin (I), 2,4-dihydroxy salicyldin isomethin indazole (H) and 3,5-dichlorosalicyldine azomethin indazole (III) Schiff bases in 50% dioxane-water media at 293 K, 308 K and 383 K have been determined. The effect of the ligands, central metal ions, ratio of the charge and radius, atomic number of the atoms and the order of the stability constants is discussed The stability constants of the alkali earth metal follow the order Be2+ > Mg2+ > Ca2+ > Sr2+ > Ba2+ with all the substituted Indazol Schiff bases.

The transformation of ethanol on Fe ion-exchanged mordenite was compared in the temperature range of 200-400degreesC for samples prepared in the solution and solid states. Ethane and methane were found as rather major products, compared to acetaldehyde and acetone. Diethyl ether was also detected as a dehydration product. The conversion was found to increase monotonically (to 96%) with increasing the Fe content (to 100%) and reaction temperature to 400degreesC. The selectivity towards acetaldehyde and acetone was found maximum at the temperature 300degreesC. Decrease in the catalyst Bronsted acidity due to ion-exchange in solution caused a marked increase in the selectivity toward acetaldehyde at 300degreesC. At variance, Fe ion-exchanged in the solid state resulted in a higher Bronsted acidity catalyst of higher selectivity to acetone. The solid state exchanged catalyst formed more coke at 400degreesC. The higher zeolite acidity catalyzes the ethane propagation into the coke precursors. The extraordinary formation of ethane as a dominant transformation product (in the absence of H-2 gas supply) is explained mainly to the O-abstracting affinity of the Fe3+ ion. Methane may be formed as a result of decomposition reaction at high temperatures. Mossbauer and XRD were applied for characterizing different Fe species involved as active sites in the reaction. Coke deposited on the catalysts was measured by TGA. Other helpful information was obtained from BET of N-2-adsorption and FT-IR of NH3-adsorption. Fair correlation between the active sites responsible for formation of the various products and the zeolite acidity is discussed along with a possible role for the surface area and pore structure in the reaction activity and selectivity. (C) 2003 Elsevier Science B.V. All rights reserved.

The thermal decomposition processes taking place in the solid state oxalate mixture of CuC2O4-ZnC2O4-2H(2)O (1:1 mole ratios) have been studied in air using DTA-TG, XRD and SEM techniques. DTA-TG curves showed that, the decomposition proceeds through three well-defined steps with DTA peaks closely correspond to the weight loss obtained. The decomposition behaviour of the oxalate mixture is in good agreement with that of the individual oxalates. XRD showed an increase in the intensity of the diffraction lines on rising the calcinations temperature from 400 to 800degreesC attributed to the grain growth of the decomposition products. SEM experiments confirmed this result as the very small crystallites obtained at 400 degreesC are re-textured and coalesced into aggregates of large crystals with sharp edges and angles when calcined at 800degreesC. Kinetic analysis of the oxalate decomposition steps was performed under non-isothermal conditions using different integral methods of analysis. The dynamic TG curves obeyed the Avrami-Erofeev equation characteristic of solid-state nucleation-growth mechanism and consistent with the textural changes accompanying the decomposition revealed by SEM experiments. The activation parameters were calculated and discussed in view of the electronegativity of the metal ions. (C) 2003 Elsevier Science B.V. All rights reserved.

In this paper, symmetry reductions for a cubic nonlinear Schrodinger (NLS) equation to complex ordinary differential equations are presented. These are obtained by means of Lie's method of infinitesimal transformation groups. It is shown that ten types of-subgroups of the symmetry group lead, via symmetry reduction, to ordinary differential equations. These equations are solved and the similarity solutions are obtained.

In this Letter, we consider a coupled Schrodinger-Korteweg-de Vries equation (or Sch-KdV) equation with appropriate initial values using the Adomian's decomposition method (or ADM). In this method, the solution is calculated in the form of a convergent power series with easily computable components. The method does not need linearization, weak nonlinearity assumptions or perturbation theory. The convergence of the method as applied to Sch-KdV is illustrated numerically. (C) 2003 Elsevier Science B.V. All rights reserved.

Various pottery materials were evaluated for possible use in manufacturing containers for radioactive waste. Their potential was examined from the viewpoints of the effectiveness of disposal and the changes induced in them by gamma rays. Samples of these materials were irradiated with high-energy neutrons and gamma rays in a reactor near its core. the physical and mechanical properties of the materials before and after gamma irradiation (in a Co-60 gamma cell) were compared. The study showed that pottery materials are resistant to radiation. Therefore, they were proposed for manufacturing drums for disposal of radioactive waste of high gamma activity. (C) 2003 Elsevier Science Ltd. All rights reserved.

In several recent papers, a one-sided iterative process for computing positive definite solutions of the nonlinear matrix equation X + A * X-1 A = Q, where Q is positive definite, has been studied. In this paper, a two-sided iterative process for the same equation is investigated. The novel idea here is that the two sequences obtained by starting at two different values provide (a) an interval in which the solution is located, that is, X-k less than or equal to X less than or equal to Y-k for all k and (b) a better stopping criterion. Some properties of solutions are discussed. Sufficient solvability conditions on a matrix A are derived. Moreover, when the matrix A is normal and satisfies an additional condition, the matrix equation has smallest and largest positive definite solutions. Finally, some numerical examples are given to illustrate the effectiveness of the algorithm.

In this paper the parallel plate and cylindrical geometry are considered to model contaminant transport in a main fracture surrounded by a two-dimensional rock matrix. The transformation group theoretical approach is applied to present some new analytical solutions for the advection-dispersion equation governing these models. The application of this approach reduces the number of independent variables, and consequently the governing equation is reduced to ordinary differential equations. The general analysis developed in this study corresponds to the case of parabolic manner of the velocity within the main fracture. (C) 2002 Elsevier Science Inc. All rights reserved.

Effect of calcination temperature on the physico-morphological properties of CoC2O4.2H(2)O-FeC2O4-2H(2)O (1:2 mole ratio) mixture has been investigated using DTA-TG, XRD, Mossbauer effect (ME) spectroscopy, FT-IR and SEM measurements. DTA-TG results showed that the decomposition proceeds via four well-defined steps. The first is attributed to dehydration and formation of anhydrous mixture which decomposed in the second step to give CoC2O4-Fe2O3 mixture. In the third step, CoC2O4 decomposed and Co3O4-Fe2O3 mixture is formed. This mixture is thermally stable up to 920degreesC, then CO3O4 reduced to CoO, which reacts directly with alpha-Fe2O3 to form CoFe2O4, in the fourth step. ME spectra demonstrated that part of alpha-Fe2O3 is formed in a superparamagnetic doublet state in the early stages of decomposition. As the temperature increased to 800 degreesC, the crystallites are grown and the superparamagnetism disappeared. At 1000degreesC, a ferrimagnetic ordering ME spectrum fitted into two Zeeman sextets due to Fe3+ at the two distinct sites of CoFe2O4 inverse spinel has been obtained. XRD patterns of samples calcined at 250 and 280degreesC revealed none of XRD lines characteristic of alpha-Fe2O3, while the pattern of that fired at 1000degreesC confirmed the presence of single-phase cubic spinel structure with no evidence of impurities. FT-IR and SEM studies are consistent with the previous results. Kinetic analysis of the dehydration and the oxalate decomposition reactions was performed under non-isothermal conditions using different integral methods of analysis. The dynamic TG curves showed a sigmoid shape and obeyed the Avrami-Erofeev equation characteristic of the solid state nucleation-growth mechanism. The activation parameters were calculated and discussed. (C) 2003 Elsevier Science B.V. All rights reserved.

The non-isothermal decomposition of NiC2O4.2H(2)O.FeC2O4.2H(2)O (1:2 mole ratio) mixture was studied on heating to the formation of NiO-Fe2O3 mixture at 350 T in air atmosphere using thermogravimetry. Kinetic analysis of data according to the integral composite method showed that the oxidative decomposition of FeC2O4 and NiC2O4 are best described by the three-dimensional phase boundary model. The activation parameters were calculated and discussed. The solid products at different decomposition stages were identified using XRD, Mossbauer and FT-IR spectroscopic techniques. Some characteristic XRD lines of NiFe2O4 start to appear at 800 T beside the characteristic lines of NiO and Fe2O3, whereas at 1000 degreesC, only the characteristic lines of single phase cubic NiFe2O4 appeared. The Mossbauer spectrum at 1000 T fitted into two Zeeman sextets characteristic of Fe3+ on the tetrahedral (A) and octahedral (B) sites of NiFe2O4 inverse spinel. Consistent results were obtained using FT-IR where the absorption bands appeared at 602 and 407 cm(-1) for the mixture calcined at 1000 degreesC. These can be assigned to the intrinsic vibrations of tetrahedral and octahedral sites of NiFe2O4, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.

Substituted 6-(1H-benzimidazol-2-yl)-[1,2,4]triazolo[3,4-a]phthalazine derivatives containing alkyl, aryl, hydroxyl, mercapto, methylthio and formyl substituents at position 3 have been synthesised. Di-[6-(1H-benzimidazol-2-yl)3-[1,2,4]triazolo[3,4-a]phthalazin-3-yl]alkanes have been obtained by the use of dicarboxylic acids or their esters in the above condensations. Methylation reactions of the triazolo-phthalazine system are reported.

We consider solitary-wave solutions of the generalized regularized long-wave (RLW) and Korteweg-de Vries (KdV) equations. We prove the convergence of Adomian decomposition method applied to the generalized RLW and KdV equations. Then we obtain the exact solitary-wave solutions and numerical solutions of the generalized RLW and KdV equations for the initial conditions. The numerical solutions are compared with the known analytical solutions. Their remarkable accuracy are finally demonstrated for the generalized RLW and KdV equations. (C) 2003 Elsevier Science Ltd. All rights reserved.

Yttrium reacts with 5-(4-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (I), 5-(2'-bromophenylazo)-6-hydroxypyrimidine-2,4-dione (II), 5 -(2',4-dimethylphenylazo)-6- hydroxypyrimidine-2,4-dione (III), 5-(4'-nitro-2',6'-dichlorophenylazo)-6-hydroxypyrimidine-2,4-di one (IV), 5 - (2'-methyl-4-hydroxyphenylazo)- 6-hydroxypyrimidine-2,4-dione (V) to form a dark pink complexes, having an absorption maximum at 610, 577, 596, 567 and 585 nm, respectively. The complex formation was completed spontaneously in theil buffer solution and the resulting complex was stable for at least 3 h after dilution. Under the optimum conditions employed, the molar absorptivities were found to be 1.60 x 10(4), 1.29 x 10(4), 1.96 x 10(4), 1.45 x 10(4) and 1.21 x 10(4) l mol(-1) cm(-1) and the molar ratios were (1: 1) and (1:2) (M:L). The linear ranges were found within 95 mug of yttrium in 25 ml solution. One of the characteristics of the complex was its high tolerance for calcium and hence a method of separation and enrichment of microamounts of yttrium by using calcium oxalate precipitate was developed and applied to measure yttrium in nickel-base alloys. Interfering species and their elimination have been studied. The precision and recovery are both satisfactory. (C) 2003 Published by Elsevier B.V.

The 3(2H)-oxo-, 3(2H)-thioxo- or 3-amino-pyridazine derivatives 4, 6 and 7 were coupled with N-phthalyl- or N-tosyl-amino acids in one-step using N,N'-dicyclohexyl-carbodiimide as the condensing agent to furnish the corresponding 3-(N-phthalyl- or N-tosyl-aminoacyl)pyridazine derivatives 8-10 respectively. Hydrazinolysis of the N-phthalyl derivatives in methanol yielded the corresponding unprotected derivatives 11-13. The antibacterial activities of the prepared compounds were tested.

4-Allylthio-2-arylquinazolines 4a-c undergo cyclization by action of bromine to furnish 5-aryl-3-bromomethyl-2,3-dihydrothiazolo[3,2c]quinazolin-4-ium bromide 5a-c. Compounds 5a-c undergo ring opening by action of water under acid catalysis to afford the corresponding dibromide derivatives 6a-c. Bromination of 3-allyl-2-aryl-4(3H)quinazolinethiones 76-c leads to 5-aryl-2-bromomethyl-2,3dihydrothiazolo[3,2-cjquinazolin-4-ium bromides 8a-c. However, 5-aryl-1,3-thiazolo[3,2-c]quinazolinium-3-olate 10a-c were prepared by the cyclodehydration of the corresponding thioglycolic acids 9a-c with Ac2O.

The dielectric permittivity (epsilon') of the organic complexes of the general formula (CH2)(n)(NH3)(2)Mn1-xLaxCl4, n = 5, 6, 7 and 0.1 less than or equal to x less than or equal to 0.9 was studied at different temperatures as a function of the applied frequency. The obtained results contain more than one phase transition depending on the La3+ ion concentration as well as the applied frequency. The appeared transitions were of thermochromic type (change in crystal symmetry) because it gives a reversible color change with temperature. Varying the layer spacing by varying the number of carbon atom (n) will change drastically the permittivity of the sample, due to varying the superexchange interaction through the intervening of the organic group. The AC conductivity for the investigated samples was measured in the same range of temperature and frequency as that of permittivity measurements. The calculated values of the activation energy indicate the semiconducting behavior of these complexes. More than one conduction mechanisms were obtained as indicated from the existence of more than one straight line. Hopping mechanism was the most predominant one that interprets the conductivity in the low temperature region. In the moderate region of temperature the holes play a role. In the high temperature region we expect some ionic conduction which was clear from the high values of activation energy. (C) 2003 Kluwer Academic Publishers.

Two series of dealuminated Na-mordenite zeolites (DML and DMH) were impregnated, in comparison with the parent nondealuminated NaMSP, in aqueous nitrate solutions of Cu and Ni to achieve varying loadings for both of the cations. These samples were characterized by N-2 adsorption, XRD, DSC of ammonia desorption, ammonia volumetric sorption, IR of ammonia adsorption, and FTIR-photoacoustic (FTIR-PAS) techniques. The FTIR-PAS spectrum of CuNi-loaded NaMSP shows a band at 935 cm(-1) ascribed to O3Si-O-SiO3 linkages produced as a result of dealumination caused by the synergistic effect of Cu and Ni cations under the preparation conditions. As a confirmation, this band was intensified upon acid dealumination (DML) where, at the extent of dealumination (DMH), collapsing of the zeolite structure was obtained subsequent to cation modification. In addition, the dealumination effect was markedly enhanced upon increasing the load of Cu in proportion to Ni. A total erosion of OH group characteristics of Si-(OH)-AL at 3610 cm(-1) was depicted when the Ni content exceed that of Cu where it did not show any change when the Cu content surpasses that of Ni. The amount of adsorbed ammonia measured volumetrically was enlarged after dealumination as well as after increasing the contents of the modificating cations. The IR study of ammonia adsorption revealed a band at 1428 cm(-1), in either nondealuminated or dealuminated-modified samples, assigned to stronger Bronsted acid sites than those at 1455 cm(-1). The band at 1428 cm(-1) was markedly enhanced in the latter samples than in the former. This was due in part to the replacement of the protons by cations, producing sufficiently mobile protons. In conformity, DeltaH values obtained for DSC effects via ammonia desorption were enhanced after dealumination. Other correlations with XRD and surface texturing on one hand and the structural variations following cations incorporation on the other hand are evaluated and discussed. (C) 2003 Elsevier Inc. All rights reserved.

This paper presents the results of the study of interaction of the relativistic O-16 nucleus with the momentum 4.5 A GeV/c with the photo emulsion. The average multiplicities of the different emitted hadrons (shower and grey) in the forward (FHS) and backward (BHS) hemisphere, compared with other data from the interaction of P-1, He-4, Li-6, C-12, Ne-22 and Si-28 at nearly the same momentum, have been studied as a function of projectile mass number, the number of interacting projectile nucleons, impact parameter and number of shower particles emitted in the backward hemisphere. The multiplicity distribution of the shower particles emitted in the forward and backward hemisphere directions using the KNO representation are represented and described by an exponential form for BHS shower particles. Another objective of this paper is to examine whether the mechanism of particle production in the BHS is significantly different from the operating in the production of particles in the FHS which can help to solve some questions connected with the role of collective phenomena in the backward emission of particles from the nuclear targets. (C) 2003 Elsevier Science Ltd. All rights reserved.

A compocasting process including two steps, liquid and semisolid stirring. This process has been used to produce SiC particle reinforced aluminium matrix composites (A7475). In the presnt study, this process has been used to produce aluminium matrix composites reinforced with 15 and 25 vol.% SiC particles of 15, 30, 50 and 100 mum size. This process leads to complete wetting of SiC particles, good distribution in molten aluminium and it can be readily achieved at relatively low stirring rate. After casting, the composites were hot extruded, solution treatment at 753 K for 1.5 hours and ageing at 393 K for 6 hours (M). Then the interaction between SiCp and aluminium matrix has been studied. Al4C3 is not detected at the A7475/SiC interface due to lower processing temperature. The corrosion behaviour of extruded SiCp/(A7475) alloy and (A7475) were investigated under the condition of the peak aged (T6) in 3.5% NaCl using weight loss and a polarisation measurements. Some corrosion kinetic and mechanistic parameters have been studied such as anodic and cathodic Tafel slopes, corrosion potential and corrosion current density. The addition of SiC particle by 15 or 25 vol.% in aluminium alloy (A 74 75) decreases the resistance of these alloys to corrosion. The increase of particle size accelerates the corrosion process. Addition of Na2CrO4 as inhibitor to 3.5% NaCl decreases the corrosion rate of composites alloy. The inhibition efficiency was found to be increased with chromate concentration.

We consider the problem of determining analytically the exact solutions of the heat conduction equation in an inhomogeneous medium, described by the diffusion equation partial derivative(t)T(x, t) = r(1-s)partial derivative(r)(k(r)r(s-1)partial derivative(r)T(r, t)) with a position-dependent thermal diffusivity K(r). The unsteady one-dimensional heat conduction equation is transformed into an ordinary differential equation called Kummer's equation unifiedly in the linear, cylindrical and spherical coordinate systems. Kummer's equation is solved in terms of the confluent hypergeometric functions. These solutions exist on the conditions that boundaries move with their positions proportional to some functions of time. Progress has been made in this direction by introducing similarity variables and transformations. (C) 2002 Elsevier Science Inc. All rights reserved.

The notion of Lipschitz stability for systems of ordinary differential equations (ODE) was introduced. In this paper, we will extend the total stability notion to a new type of stability called total Lipschitz stability. Some criteria and results are given. Our technique depends on Liapunov's direct method. MSC-34D20. (C) 2003 Elsevier Ltd. All rights reserved.

A simple, accurate and sensitive method for the microdetermination of benzocaine, lignocaine and procaine hydrochlorides in pure forms and in pharmaceutical formulations is described. The procedure is based on the reaction of those drugs in an aqueous acidic medium with p-benzoquinone to form charge-transfer complexes. The method has been used for the determination of 5.0 - 70, 5.0 - 60 and 5.0 - 90 mug ml(-1) of benzocaine, lignocaine HCl and procaine HCl, respectively. The complexes have apparent molar absorptivities of 1.70 x 10(3), 2.79 x 10(3) and 2.42 x 10(3) L mol(-1) cm(-1) and Sandell sensitivities of 9.72, 10.34 and 11.25 ng cm(-2), respectively. The proposed procedure of analysis is as accurate as the British Pharmacopoeial method (2003). The method was successfully used for the determination of those drugs in the presence of their degradation products, additives and excipients, which were normally encountered in pharmaceutical formulations.

Reaction of readily available alpha-(benzotriazolyl)alkyl urea derivatives (derived from aromatic, heteroaromatic, and aliphatic aldehydes) with beta-keto esters resulted in 3,4-dihydropyrimidin-2(1H)-ones in good to excellent yields.

3-(4-Thioxo-3,4-dihydroquinazolin-2-yl)acrylic acid 1 proved to be a convenient precursor for the synthesis of novel polyfunctional quinazoline derivatives of pharmaceutical interest via its treatment with some, pi-deficient compounds such as phenyl isocyanate and phenyl isothiocyanate. Also, S- and N-glucosidation of quinazoline has been achieved by treatment of 1 with glucopyranosyl bromide in alkaline medium. The behavior of 1 toward acrylonitrile (under Michael reaction condition), paraformaldehyde in the presence of secondary amines (under Mannich reaction condition) and sodium azide were investigated. Moreover, the peptidyl derivatives of quinazoline have been synthesized by condensation of 1 with alpha-amino acids via different routes. Some of the newly synthesized products were tested for their antimicrobial activities. The structure assignments are based on the analytical and spectroscopic results.

The inhibitive action of the mucilage extracted from the modified stems of prickly pears, toward acid corrosion of aluminum, is tested using weight loss, thermometry, hydrogen evolution and polarization techniques. It was found that the extract acts as a good corrosion inhibitor for aluminum corrosion in 2.0 M HCl solution. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm. It was found that the adsorption of the extract on aluminum surface is a spontaneous process. The inhibition efficiency (IE) increases as the extract concentration is increased. The effect of temperature on the IE was studied. It was found that the presence of extract increases the activation energy of the corrosion reaction. Moreover, the thermodynamic parameters of the adsorption process were calculated. It was found also that the Opuntia extract provides a good protection to aluminum against pitting corrosion in chloride ion containing solutions. (C) 2003 Elsevier Ltd. All rights reserved.

This Letter presents a numerical method, based on the Adomian's decomposition method (ADM), is presented of the Jaulent-Miodek (JM) equation. We obtain the numerical and exact travelling wave solutions of the JM equation for the initial conditions. The ADM method provides a better approximation to the exact solution than the classical methods. In order to show the efficiency of this method, exhaustive numerical examples are presented. (C) 2003 Elsevier B.V. All rights reserved.

Reaction of N-{3-cyano-6-[4(5-oxo-2-phenylhydrazono-4,5-dihydroimidazol-1-yl)phenyl]-4-phenylpyridin-2-yl}formimidic ethyl ester (3) and 3-[4-(3-amino-4-imino-5-phenyl-3,4-dihydropyrido[2,3-d]pyrimidin-7-yl)phenyl]-2-phenyl-5-phenylhydrazono-3,5-dihydroimidazol-4-one (4) with different reagents has been investigated and discussed. Some of the obtained compounds were tested for their antimicrobial activity.

Oxazolone forms (1:1) complexes with Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ chlorides, as well as forms (1:1) complexes with Co2+ and Cu2+ acetates. All the complexes are found to be non-electrolytes in DMF; tetrahedral, square-planar and octahedral structures are assigned to them based on electronic and magnetic data. IR studies reveal that the complexes are formed by donating the lone-pair electron from O and N atoms to the metal ion. The thermal decomposition of the [ML(.)mX(.)nH(2)O](y)(H2O)-H-. chelates was studied by TG-DTA techniques. The mechanism of the decomposition has been established from TG-DTA data. The kinetic parameters, activation energy (E-a) and pre-exponential factor (A), were calculated from TG curves using Coats and Redfern method. Relative thermal stabilities of the chelates have been evaluated on the basis of these parameters. (C) 2003 Published by Elsevier Science B.V.

In this paper, an algorithm for obtaining the Hermitian positive definite solutions of the nonlinear matrix equation X + A * X -1 A = I is considered and discussed. The convergence of the algorithm is proved. Numerical experiments to illustrate the behavior of the algorithm are executed.

N-(2-Styryl-, 2-p-chlorostyryl- or 2-p-nitrostyryl-4-oxo-3H-quinazolin-3-yl)-2-aminobenzamides 6a-c react with triethyl orthoesters to furnish some new 2-styryl-, 2-p-chlorostyryl- or 2-p-nitrostyryl-2-substituted-3,3-biqui-nazolin-4(3H)ones (7a-c- 9a-c). An alternative synthesis of (7-9)b has been accomplished by reaction of acetylanthranil with 2-amino-2-styryl-, 2-p-chlorostyryl- or 2-p-nitrostyryl-quinazolin-4(3H)-ones 4a-c. The synthesised products are tested for antimicrobial activities using methaqualone as reference standard.

The effect of some ethoxylated fatty alcohols, with different numbers of ethylene oxide units, on the corrosion of zinc in 0.5 M HCl has been studied using weight loss and polarization measurements. The inhibition efficiency was found to increase with increasing concentration, number of ethylene oxide units per molecule and with decreasing the temperature. Inhibition was explained on the basis of adsorption of ethoxylated fatty alcohols molecules on the metal surface through their ethoxy groups. The degree of surface coverage varied linearly with logarithm of inhibitor concentration fitting Temkin isotherm. The thermodynamic parameters were calculated for the tested system from the data obtained at different temperatures. (C) 2003 Elsevier Ltd. All rights reserved.

In this paper we use Adomian's decomposition method for solving linear and nonlinear Klein-Gordon and sine-Gordon equations. Analytic and numerical studies are presented. The obtained results show improvements over existing techniques. (C) 2003 Published by Elsevier Science Ltd.

Iron-modified mesoporous and microporous zeolite materials, namely FSM-16 and NaY as well as dealuminated NaY (del-NaY), were prepared using cyclopentadienyl iron dicarbonyl diamer [(C5H5)Fe(CO)(2)](2) via a chemical vapor deposition (CVD) technique. XRD, FTIR, TG/DSC, N-2 adsorption and Mossbauer measurements were used to characterize the various materials. An isomorphous substitution of Fe3+ into the framework of NaY zeolite was accomplished as determined from the Mossbauer results (IS less than or equal to 0.3) as well as from the increase in the unit cell volume. As a further confirmation, some framework IR bands (780 and 574 cm(-1)) showed a shift towards lower frequencies upon iron incorporation along with the existence of a band at 686 cm(-1) ascribed to Si-O-Fe linkages. The latter band was emphasized on the basis of comparison of NaY before and after the CVD treatment with the precursor of the Fe complex. Two types of octahedral Fe3+ components were revealed in FSM-16 and del-NaY samples specified as intrazeolitic iron oxide clusters and alpha-Fe2O3 species, which were localized on the external surfaces of zeolites and occupied small percentages (18-22%) compared with the former species. The surface area of the support NaY was preserved after the CVD treatment rather than FSM-16 that showed a reduction (24%). The catalytic activities of various samples for the liquid phase hydroxylation of phenol using H2O2 were found to be in the order: Fe/NaY > Fe/FSM-16 > Fe/del-NaY The higher activity of the Fe/NaY sample was attributed to the high dispersity of Fe ions that are located in framework positions and to the high crystallinity. (C) 2003 Published by Elsevier Ltd.

Polymer complexes with uranium, cobalt, and iron chlorides were synthesized and investigated by elemental analysis, electronic (uv-visible), IR vibration, and magnetic moment measurements. The thermal stabilities of N-acryloyl,N'-cyanoacetohydrazide (ACAH) homopolymers and polymer complexes of poly(ACAH) (PACAH) with metal chlorides were studied thermogravimetrically. The rates of polymerization of PACAH in the absence and presence of metal chlorides were studied. The activation energies of the degradation of the homopolymer and polymer complexes were calculated using the Arrhenius equation. (C) 2003 Wiley Periodicals, Inc.

The corrosion behaviour of 304 stainless steel (SS) in 0.5 M H2SO4 solution was studied using potentiodynamic and galvanostatic polarization techniques. Three anodic peaks were observed in the potentiodynamic anodic polarization curves before oxygen evolution. The effects of acid concentrations and voltage scan rate were studied. The inhibitive effect of 4-substituted pyrazole-5-ones toward the corrosion of 304 SS in 0.5 M H2SO4 were studied. The inhibition action of these compounds was assumed to occur via adsorption on the steel surface through the active centres contained in their structure. The mechanism of inhibition was interpreted on the basis of the inductive and mesomeric effects of the substituents. There is a good agreement between the percentage inhibition efficiencies calculated from both techniques. The inhibition efficiencies increase with increasing the inhibitor concentrations. (C) 2003 Elsevier B.V. All rights reserved.

In this paper the existence theorem for an almost everywhere solution of a mixed problem for more complicated nonlinear hyperbolic-parabolic (nonlinear thermoelasticity) system was proved using Galerkin's method and suitable a priori estimates were obtained. (C) 2002 Elsevier Inc. All rights reserved.

In this Letter we present an Adomian's decomposition method (shortly ADM) for obtaining the numerical soliton-like solutions of the potential Kadomtsev-Petviashvili (shortly PKP) equation. We will prove the convergence of the ADM. We obtain the exact and numerical solitary-wave solutions of the PKP equation for certain initial conditions. Then ADM yields the analytic approximate solution with fast convergence rate and high accuracy through previous works. The numerical solutions are compared with the known analytical solutions. (C) 2003 Elsevier B.V. All rights reserved.

Fission-produced I-131 and Ru-103 radionuclides have been separated sequentially by distillation from H2SO4 of controlled chemical composition. The thermal-neutron irradiated uranium trioxide targets were digested in 2M NaOH solution and then, the supernatant solution was acidified to 20% H2SO4 with addition of a few drops of H2O2 Solution. On boiling for 3.5 hours, greater than or equal to99.99% I-131 was volatilized, passed through 3M H2SO4 traps, and then collected in 0.1M NaOH + 0.01% Na2S2O3 solution with a recovery yield of 73.6%. The product radionuclide had high radiochemical and radionuclidic purities. After separation of I-131, the fission-product solution was acidified to 40% H2SO4 acid containing KMnO4 as an oxidant and boiled for 40 minutes. Ruthenium nuclides were volatilized and collected in 0.1M NaOH solution. Gamma-ray spectrometry showed that the separation and the recovery yields of 103Ru were greater than or equal to99.99 and 65%, respectively, with similar to92% radionuclidic purity, measured immediately after separation. The radionuclides of I-132 and Rh-106 were the main contaminants detected in the obtained Ru-103 product solution.

In this paper, Adomian's decomposition method is applied to solving high-order linear Volterra-Fredholm integro-differential equations. Comparison with the results obtained in terms of Taylor's polynomials reveals that the Adomian's decomposition method is more accurate and is more efficient than the Taylor's expansion technique. The decomposition method also minimizes the computational difficulties of Taylor's expansion approach in that the components of the decomposition series are determined elegantly by using simple integrals.

Molecular complexes of charge transfer of some 4-(2-hydroxy-4' -substituted benzyldene amino)-2-methyl quinoline with fluoranil and 2,4-dinitrofluorobenzene have been investigated by R H-1-NMR, electronic absorption and ESR spectroscopy. [GRAPHICS] The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional methods, the role of the molecular structure of the complexes as well as the equilibrium constants (K), Oscillator strength (1), dipole moment (mu,) and free energy (DeltaG*) are elucidated.

N-[4-(Dicyanomethylazo)phenyl]-2-saccharin-2-ylacetamide (2) proved to be a convenient precursor for the synthesis of a variety of pyridazine and pyrimidine derivatives 4a,b,6, and 7. Also a series of substituted pyrimidines 10-16 were prepared from the reaction of N-[4-(2-amino-1-cyano-2-substitutedvinylazo)phenyl]-2-(saccharin-2-yl)acetamide 9a,b with different reagents via initial addition to either the cyano or amino group, followed by cyclization. Some of the synthesized heterocycles were screened for their biological activity. (C) 2003 Wiley Periodicals, Inc.

In this paper, the general ordinary quasi-differential expression M-p of n-th order with complex coefficients and its formal adjoint M-p(+) on any finite number of intervals I-p = (a(p), b(p)), p = 1, ..., N, are considered in the setting of the direct sums of L-wp(2) (a(p), b(p))-spaces of functions defined on each of the separate intervals, and a number of results concerning the location of the point spectra and the regularity fields of general differential operators generated by such expressions are obtained. Some of these are extensions or generalizations of those in a symmetric case in [1], [14], [15], [16], [17] and of. a general case with one interval in [2], [11], [12], whilst others are new.

The behaviour of 5,6,7,8-tetrabromo-4-(3,4-dimethylphenyl)-1H-2,3-benzoxazin-1-one towards phosphorus pentasulfide, active methylene compounds, 3,5-dimethylpyrazole under Friedel-Craft's conditions, Grignard reagents, o-phenylenediamine, and hydrazine hydrate has been investigated. Also, reactions of 2-amino-5,6,7,8-tetrabromo-4-(3,4-dimethylphenyl)-2H-phthalazin-1-one with aromatic aldehyde, acetic anhydride, and ethyl acetate are described.

3(2H)-Oxo-, 3(2H)-thioxo- or 3-aminopyridazine derivatives were coupled with N-phthalyl- or N-tosylamino acids in one-step room-temperature reaction using N,N'-dicyclohexylcarbodiimide as the condensing agent to furnish the corresponding 3-N-(phthalyl- or tosylamino acids) pyridazine derivatives. Hydrazinolysis of the N-phthalyl derivatives in methanol yielded the corresponding unprotected derivatives. The antibacterial activities of the prepared compounds were tested.

The nature, sequence, crystallinity and microstructure of hydrated phases were analyzed using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the formation of different hydrated phases was temperature dependence. The physico-mechanical and microstructural characteristics were investigated after curing at 20, 40 and 60degreesC. The results indicated that for the substitution of calcium aluminate cement (CAC) by air-cooled slag (AS) or water-cooled slag (WS) at 20 C, the compressive strength increases with slag content up to 10 wt.%, then followed by a decrease with further slag substitution up to 25 wt.%; but the values are still higher than those of the neat CA C pastes at different curing ages up to 60 days. After 28 days of hydration at 40-60 C, the compressive strength increases with the slag content. This is attributed to the prevention of the conversion reaction, which was confirmed by XRD, DSC and SEM techniques, and the preferential formation of stratlingite (gehleinte-like) phase. The SEM micrographs showed a close texture of hydrated CAC/slag blends made with AS or WS at 40degreesC due to the formation of C(2)ASH(s) and C-S-Hphases.

The materials used in this investigation were ordinary Portland cement (OPC), granulated blast-furnace slag cement (GBFSC) and limestone (LS). The slag cement containing limestone shows small thermal expansion and shrinkage coefficient in comparison to neat OPC pastes. This is mainly due to the pozzolanic activity of the granulated slag as well as the filling effect of limestone. It was found that the partial substitution of slag by 5 wt.% LS improves the compressive strength. As the curing temperature increases, the C-S-H phases are deposited within the pore system, which can accommodate larger amounts of hydration products. Thisfact leads to relatively high compressive strength values of GBFSC when compared with OPC pastes. As the amount of limestone increases (15 wt. % LS), the compressive strength diminishes. The presence of 15 wt. % limestone changes the morphological shape of C-S-H crystalsfrom fibers to crumbledfoils with smallfibers embedded of Ca(OH), phase.

A simple, sensitive, and convenient spectrophotometric method for the determination of diclofenac sodium and piroxicam in pure form and in pharmaceutical formulations was developed. The method is based on the oxidation of diclofenac sodium or piroxicam by iron(HI) in the presence of o-phenanthroline. The formation of tris(o-phenanthroline) iron(II) complex (ferroin) upon the reaction of diclofenac sodium or piroxicam with an iron(III)-o-phenanthroline mixture in acetate buffer solution of pH 4.4 and 4.8, respectively, was investigated. The ferroin complex is measured at 510 nm against a reagent blank prepared in the same manner. The optimum experimental parameters for the color production are selected. Beer's law is valid within a concentration range of 1.0-32 mug mL(-1) for diclofenac sodium and 1.0-28 mug mL-1 for piroxicam. For more accurate results, Ringbom optimum concentration ranges are 2.0-30 and 2.0-26 mug mL(-1) for diclofenac sodium and piroxicam, respectively. The molar absorptivities are 1.15 x 10(4) and 1.63 x 10(4) L mol(-1) cm(-1), whereas Sandell sensitivities are 2.78 and 2.03 ng cm(-2) for diclofenac sodium and piroxicam, respectively. The method gave a mean percentage recoveries 99.8 +/- 1.2% for diclofenac sodium and 100.3 +/- 0.8% for piroxicam. The developed method is applied for the determination of diclofenac sodium and piroxicam in bulk powder and in their pharmaceutical formulations without any interference from tablet fillers.

Acrylonitrile was copolymerized with pentachlorophenyl methacrylate (PCPMA)in dimethyl formamide using azobisisobutyronitrile as initiator. The composition of the copolymers was determined by nitrogen analysis and the monomer reactivity ratios (r(1) and r(2)) were calculated. Both the homopolymer and the copolymers were characterized by a variety of spectral and thermal methods. Thermogravimetry and differential thermal analysis data showed that the comonomer (PCPMA) initiates the nitrile oligomerization reaction in the copolymer upon heating. A mechanism for the initiation of (PCPMA) units in the nitrile copolymers was also proposed. (C) 2003 Wiley Periodicals, Inc.

The general analysis of transformation group method has been developed to study the linear thermoelastic system. The application of one-parameter group reduces the number of independent variables. Consequently, the governing system of second-order partial differential equations reduced into systems of ordinary differential equations. In this paper some of these systems are solved analytically. (C) 2003 Published by Elsevier Inc.

A comparative study of results obtained from the interactions of 14.6A GeV Si-28 in nuclear emulsion is presented. In this work the experimental data serve as one of the decisive signature of quark-gluon plasma formation. The data for 200 and 400 proton-emulsion interactions are used to investigate the assumption which consider interaction of Si-28-Em at 14.6A GeV is such that for a proton with total energy corresponding to that for effective number of interacting nucleons (12.6 x 14.6 = 175) or as a proton having the total energy of Si-28 (i.e., 28 x 14.6 = 409 GeV). It is also shown that the relativistic quantum molecular dynamics model nicely predicts the multiplicities and correlations of shower and grey particles in the interactions of Si-28 with emulsion nuclei at 14.6A GeV. (C) 2003 Published by Elsevier B.V.

A linear form of density-dependent total nucleon-nucleon (NN) cross-section that depends on the coordinates of the projectile and target is applied in the Glauber phase shift formula. The only free parameter in these calculations is the density-dependent parameter "beta", which is adjusted to obtain an agreement between the calculated angular distribution of the elastic-scattering cross-section and the corresponding experimental one. The elastic scattering of the C-12 ion on the C-12 ion target has been studied at incident energies of 300, 360, 1016, 1441 and 2400 MeV. The total reaction cross-section "sigma(r)" is also calculated with the obtained value of "beta" for the same reactions. The obtained values of "sigma(r)" are compared with those obtained from the optical-model analysis as well as those of the experimental value. Nuclear transparency effects are also discussed. Generally, the density-dependent NN cross-section improves the calculated results.

The electrochemical and passivation behaviour of lead electrode in 0.10 mol dm(-3) Na2HPO4 solution was studied using cyclic voltammetric technique and complemented by X-ray surface analysis. The anodic half-cycle of the voltammogram exhibits active, pre-passive, passive and transpassive regions before the oxygen evolution. Passivity is due to the formation of thick porous PbO film by three-dimensional nucleation and growth on the electrode surface. The transpassive region is attributed to the electroformation of PbO2. The cathodic half-cycle shows two cathodic peaks as well as a small shoulder at the extreme negative potential just before the hydrogen evolution. The mechanism of formation of the passive film is discussed. (C) 2003 Elsevier B.V. All rights reserved.

Three accurate, rapid and simple atomic absorption spectrometric, conductometric and colorimetric methods were developed for the determination of norfloxacin (NRF), ciprofloxacin (CIP), ofloxacin (OFL) and enrofloxacin (ENF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink Coloured complexes were determined either by AAS or colorimetrically at lambda(max) 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone in the range 5.0-65, 4.0-48, 5.0-56 and 6.0-72 mug ml(-1) of NRF, CPF, OFL and ENF, respectively. The optimizations Of various experimental conditions were described. The results obtained showed good recoveries of 99.15 +/- 1.15, 99.30 +/- 1.40, 99.60 +/- 1.50, and 99.00 +/- 1.25% with relative standard deviations of 0.81, 1.06, 0.97, and 0.69% for NRF, CPF, OFL, and ENF, respectively. Applications of the proposed methods to representative pharmaceutical formulations are successfully presented. (C) 2003 Elsevier B.V. All rights reserved.

The two-dimensional Laplace integral transform technique has been applied to get the temperature distributions in the molten layer of a thin-film coated on a substrate, the solid part of the film and the substrate during the irradiation with a pulsed laser. The derivation has taken into account the cooling and the temperature-dependent absorption coefficient of the irradiated surface. As an illustrative example computations were carried out on an aluminum thin-film coated on a glass substrate. (C) 2003 Elsevier Ltd. All rights reserved.

3(2H)-Oxo-, 3-mercapto- or 3-amino-pyridazine derivatives 3,5 and 6 have been coupled with N-phthalyl- or N-tosylamino acids in one-step at room temperature by using N,N'-dicyclohcxylcarbodiimide as the condensing agent to furnish the corresponding 3-N-(phthalyl- or tosyl-amino acids) pyridazine derivatives (7-9)a-h, respectively. Hydrazinolysis of the N-phthalyl derivatives (7-9)a-d in methanol yields the corresponding unprotected derivatives (7-9)i-l. The anti-bacterial activity of the prepared compounds has been tested.

The inhibition of aluminium corrosion in oxalic acid solution by three cationic surfacants was studied using potentiostatic and potentiodynamic polarization. It was found that the addition of any of the three used surfacants resulted in a decrease of the corrosion current, demonstrating the inhibition nature of these surfactants. The inhibition efficiency increases with increasing surface concentration as well as the number of ethylamine units. The results obtained are discussed in view of the adsorption of surfacant molecules on the aluminium surface. It was found the adsorption of surfacant molecules on the aluminium surface follows the Languir adsorption isotherm. The effect of temperature on the inhibition efficiency was also studied. The results indicate that the inhibition efficiency decreases with increasing temperature. The activation energy of the system increases with the addition of surfacant; on the other hand, it was found that the addition of surfacant shifts the pitting potential of aluminium toward the active direction, indicating the accelerating effect on pitting corrosion. This finding is discussed in view of the effect of surfacant addition on the interfacial tension at the passive film/solution interface.

The H-mordenite zeolite catalyzes the polymerization of N,N-diethanol acrylamide (DEAA) with phthalic anhydride (PA) yielding polyesteramide (PEA) resin. The Fe modified mordenites showed lower activity than that of H-mordenite that presented high stability on multiple recycling. The formation of DEAA; the principal step in forming PEA, was occurred through the condensation reaction of diethanol amine (DEA) and acrylic acid (AA) with 91% selectivity in addition to 9% devoted for the corresponding ester (diethanol amine monoacrylate; DEMA). The IR spectroscopic study of DEAA formation in the presence of mordenite zeolite reveals the greater affinity of the reactants specifically AA to protons that are likely to be the initiators of the DEAA formation. The formation of ester was confirmed through the appearance of a band at 1735 cm(-1) attributed to the stretching vibration of C=O of ester groups. A possible reaction mechanism is proposed based on data reported in the literature and the results of the present investigation. The activation energy of the DEAA formation was found to be 35.5 kJ mol(-1), for non-catalyzed and 11.46 kJ mol(-1), for the H-mordenite catalyzed one. The acidic and textural properties of the catalytic samples have been measured using NH3 adsorption (at 150degreesC) and N-2 adsorption (at -196degreesC), respectively. The results obtained indicate the importance of the zeolite acid selectivity towards amide and ester formation. (C) 2003 Elsevier B.V. All rights reserved.

In this article, we implement a relatively new numerical technique, Adomian's decomposition method for solving the linear Helmholtz partial differential equations. The method in applied mathematics can be an effective procedure to obtain for the analytic and approximate solutions. A new approach to a linear or nonlinear problems is particularly valuable as a tool for Scientists and Applied Mathematicians, because it provides immediate and visible symbolic terms of analytic solution as well as its numerical approximate solution to both linear and nonlinear problems without linearization [Solving Frontier Problems of Physics: The Decomposition Method, Kluwer Academic Publishers, Boston, 1994; J. Math. Anal. Appl. 35 (1988) 501]. It does also not require discretization and consequently massive computation. In this scheme the solution is performed in the form of a convergent power series with easily computable components. This paper will present a numerical comparison with the Adomian decomposition and a conventional finite-difference method. The numerical results demonstrate that the new method is quite accurate and readily implemented. (C) 2003 Elsevier Inc. All rights reserved.

The thermal decomposition of cadmium-zinc oxalate (1: 1 mol ratios) mixture in air was investigated by non-isothermal thermogravimetric analysis. Intermediates and the final products were characterized by X-ray diffraction and scanning electron microscopy techniques. TG showed that the mixture dehydrated in two steps and decomposed exothermically to CdO-ZnO mixture at 390degreesC in a further two steps. The observed increase in the intensity of the X-ray diffraction lines by raising the calcination temperature from 400 to 800degreesC is attributed to the grain growth of CdO-ZnO mixture as revealed from SEM experiments. The kinetics of the oxalate decomposition steps was performed using the various reaction interface models and differential techniques of computational analysis of non-isothermal data. The activation parameters, calculated using the integral composite method, showed that the reactions were best described by the random nucleation model characteristic of solid state nucleation growth mechanism. The results of activation parameters for the different decomposition steps are compared and discussed. (C) 2003 Elsevier B.V. All rights reserved.

The molecular charge-transfer complexes of phenylephrine with picric acid and in-dinitrobenzene have been studied and investigated by IR, H-1 NMR electronic spectra in organic solvents and buffer solutions, respectively. Simple and selective methods are proposed for the determination of phenylephrine hydrochloride in bulk form and in tablets. The two methods are based on the formation of charge-transfer complexes between drug base as a n-donor (D) and picric acid, in-dinitrobenzene as pi-acceptor (A). The products exhibit absorption maxima at 497 and 560 nm in acetonitrile for picric acid and in-dinitrobenzene, respectively. The coloured product exhibits an absorption maximum at 650 nm in dioxane. The sensitive kinetic methods for the determination phynylephrine hydrochloride are described. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time at 20 min. (C) 2003 Elsevier B.V. All rights reserved.

Cetyltrimethylammonium bromide (CTAB)-modified mesoporous molecular sieve FSM-16, prepared by a hydrothermal process (373 K, 3 days), was tested as an adsorbent for acid dye (acid yellow, AY, and acid blue, AB) removal in comparison with as-prepared FSM-16 and activated carbon (AC) derived from rice husk (50 vol% H3PO4, 773 K, 2.5 h). The adsorption isotherms, sorption kinetics, and pH effects upon acid dyes sorption on the adsorbents were thoroughly investigated. The structures of different adsorbents were characterized by XRD, FTIR spectroscopy, N-2 adsorption measurements, and thermogravimetric (TG) analysis. It was found that the ultimate capacity of the adsorbents varied in the order FSM-16 > modified FSM-16 > AC and followed first-order rate kinetics. The adsorption isotherm of acid dyes on FSM-16 is of type IV, according to the IUPAC classification, drastically different from that of CTAB/FSM-16, which showed a type I isotherm. The latter sample had better adsorption performance at low concentration of acid dyes than the former. As compared to activated carbon of microporous character, the CTAB/FSM-16 sample achieved higher performance at low concentrations. This was due to the successful narrowing of the pore opening of FSM-16 using CTAB with maintenance of a considerable portion of the pore volume. Powder XRD and N-2 adsorption studies of the CTAB/FSM-16 material indicated that the textural properties of the support were preserved during the hydrothermal synthesis and that the channels remained accessible, despite a significant reduction in surface area (ca. 26%). TG studies, on the other hand, confirmed that the modified material presented a higher hydrophobicity than that of the CTAB-free FSM-16 sample. (C) 2003 Elsevier Inc. All rights reserved.

In this paper, some properties of a positive definite solution of the nonlinear matrix equation X + A(star) X-n = 1 are discussed. Effective iterative methods to obtain the smallest positive definite solution are established. Moreover, the necessary and sufficient conditions for existence the smallest positive definite solution are obtained. Finally, some numerical results are given. (C) 2003 Elsevier Inc. All rights reserved.

The pitting corrosion behavior of lead in 0.10 M Na2HPO4 solutions containing various concentrations from NaNO3 has been studied using potentiodynamic anodic polarization and SEM techniques and complemented by both X-ray and FT-IR surface analysis. Above certain critical NaNO3 concentration, the aggressive anions prevented the oxygen evolution and induce pitting on the Pb electrode surface. Pitting-initiation and pitting-growth were found to depend on the concentration of the aggressive NO3- anions. Also, some changes in the (I - E) curves within the active, pre-passive and passive regions were recorded. These changes imply mainly the appearance of new stages and peaks. This behavior gives an indication for definite changes in the pit-characteristics, which interpreted in terms of solution composition and kinetics of its associated processes within pits. (C) 2004 Kluwer Academic Publishers.

A single phase manganese ferrite powder have been synthesized through the thermal decomposition reaction of MnC2O4.2H(2)O-FeC2O4.2H(2)O (1:2 mole ratio) mixture in air. DTA-TG, XRD, Mossbauer spectroscopy, FT-IR and SEM techniques were used to investigate the effect of calcination temperature on the mixture. Firing of the mixture in the range 300-500 degreesC produce ultra-fine particles of alpha-Fe2O3 having paramagnetic properties. XRD, Mossbauer spectroscopy as well as SEM experiments showed the progressive increase in the particle size of alpha-Fe2O3 up to 500 degreesC. DTA study reveals an exothermic phase transition at 550 degreesC attributed to the formation of a Fe2O3-Mn2O3 solid solution which persists to appear up to 1000 degreesC. At 1100 degreesC, the single phase MnFe2O4 with a cubic structure predominated. The Mossbauer effect spectrum of the produced ferrite exhibits normal Zeeman split sextets due to Fe(3+)ions at tetrahedral (A) and octahedral (B) sites. The obtained cation distribution from Mossbauer spectroscopy is (Fe0.92Mn0.08)[Fe1.08Mn0.92]O-4. (C) 2003 Elsevier Ltd. All rights reserved.

The homogeneous degradation of benzene (B), toluene (T), ethylbenzene (E) and p-xylene (X) (BTEX) was studied in aqueous solutions, at pH 3.0, of hydrogen peroxide (5.8 mM) under UV irradiation in a photoreactor equipped with a 300 nm lamp of light intensity 3.5 x 10(-5) Ein L(-1)min(-1). BTEX was substantially degraded by the H2O2/UV system, with >90% disappearing in 10 min of irradiation. The decomposition of BTEX was studied either as single or as multi-component systems. The effects of irradiation time, amounts of H2O2 in molar ratios, rate of degradation and competition between components were thoroughly examined. It can be stated that the rate of BTEX degradation in mixture was higher than those for the individual components due to external effects of the absorption of UV fight by the mixture, and their effects on enhancing the formation of OH. radicals. The appropriate figure of merit, the electrical energy per mass (EE/M), was estimated at various molar ratios and it was confirmed that the best value was the one depicted for p-xylene (0.065 kWh kg(-1)). A theoretical model for the degradation pathway was proposed. (C) 2004 Society of Chemical Industry.

We consider solitary-wave solutions of the generalized Burgers-Fisher (BF) equation u(l) + pu(r)u(x) - u(xx) - qu(1 - u(r)) = 0. In this paper by considering the decomposition scheme, we first obtain the exact solutions of the generalized BF equation for the initial condition without using any classical transformations and then its numerical solutions are constructed without using any discretization technique. The numerical solutions are compared with the known analytical solutions. Its remarkable accuracy is finally demonstrated in the study of some values r greater than or equal to 2 of the generalized BF equation. (C) 2003 Elsevier Inc. All rights reserved.

Polycrystalline samples with the general formula Col-xCdxFe2O4 (0 less than or equal to X less than or equal to 1) were synthesized by calcining the respective oxalates mixtures at 1000 degreesC for 5 h. Their structural, electrical and magnetic properties are studied using X-ray diffraction, Fourier transform infrared and Mossbauer spectroscopy, and electrical conductivity and magnetic susceptibility techniques. With cadmium ion substitution, the lattice parameter, X-ray density, oxygen parameter, inversion factor and radii of tetrahedral and octahedral sites are calculated. The Fourier transform infrared spectra showed two dominant bands in the high- and low-frequency range which are assigned to the tetrahedral and octahedral complexes, respectively. The relationship between bands position and cadmium content was also investigated. The Mossbauer spectroscopy was carried out to study the cation distribution in this system. It was found that ions at octahedral site moved to the tetrahedral site, and that this system varied from an inverse to a normal spinel structure. The temperature variation of the conductivity showed a definite kink, except for the CdFe2O4 sample, which corresponds to the ferrimagnetic to paramagnetic transitions. The effective magnetic moment of the samples and their Curie temperature were observed to decrease by the substitution effect. (C) 2004 Elsevier B.V. All rights reserved.

In this paper, we shall use the averaged clearance method to solve the equation of stationary pressure distribution in the flow between the conic bodied and realized in a PC (IBM computer system). This method take into accounts of quantity, location and dimensions of the feeders, in case of the flow in thin films between the immobile conic surfaces. Numerical results were presented in the form of non-dimensional charts for radial, axial loads capacity and mass flow rate. (C) 2003 Elsevier Inc. All rights reserved.

Descriptions, comparisons and affinities are given for the following Late Eocene-Early Miocene new, to Egypt, records: Palmoxylon compactum Sahni, Palmoxylon geometricum Sahni, Palmoxylon indicum Sahni, Palmoxylon pondicherriense Sahni, Palmoxylon pyriforme Sahni, Palmoxylon rewahense Sahni and Palmoxylon wadiai Sahni. Comments on the geologic ages of the compared Palmoxylon species, Indian Plate migration, palaeogeography and palaeoclimates are given. (C) 2004 Elsevier B.V. All rights reserved.

In this paper, we study the relation between the fuzzy separation axioms, which had been introduced by the authors in 2001, and the fuzzy proximity defined by Katsaras in 1980. We study also the relation between our fuzzy separation axioms and the G-compactness defined by Gahler in 1995. Moreover, we show here the relation between these fuzzy separation axioms and the fuzzy uniform structures introduced and studied by Gahler and the first author in 1998. (C) 2003 Elsevier Ltd. All rights reserved.

The effect of two polyamide compounds on the corrosion behavior of aluminum metal in oxalic acid solution was investigated using potentiostatic and. potentiodynamic anodic polarisation techniques. The inhibition efficiency increases with increasing polyamide concentration until a critical value and. then starts to decrease in high polymer concentrations, indicating a low inhibition efficiency. The inhibitive behavior of these compounds is discussed in terms of adsorption of the polyamide compounds on the metal surface and formation of insoluble complexes. The adsorption process is found to obey Temkin adsorption isotherm. The pitting potential varies with concentration of chloride ions according to a linear relationship. The addition of polyamide compounds shift the pitting potential of aluminum electrode to more positive potentials, indicating an increased resistance to pitting attack.

dSimple and rapid spectrophotometric procedures have been established for quantitation of nefopam hydrochloride (NF) mebevrine hydrochloride (MB) and phenylpropanolamine hydrochloride (PP). The procedures are based on the reaction between the examined drugs (NF, MB and PP) and alizarin (I), alizarin red S (II), alizarin yellow G (III) and quinalizarin (IV) producing ion-pair complexes which can be measured at the optimum wavelength. The optimization of the reaction conditions is investigated. Beer's law is obeyed in the concentration ranges 0.5-30.0 mug ml(-1). The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficient was greater than or equal to0.9988 (n = 6) with a relative standard deviation (R.S.D.) of less than or equal to 1.3, for six determinations of 20 mug ml(-1). The methods are successfully applied to the determination of NF, MB and PP in their pharmaceutical formulations. (C) 2003 Elsevier B.V. All rights reserved.

Ternary copolymerization of tri-n-butyltin acrylate (BTA) with methyl acrylate (MA), methyl methacrylate (MMA), styrene (ST), acrylonitrile (AN) and N-methacryloyloxytetrabromophthalimide (NMTP) was carried out in solution at 65degreesC in the presence of azobisisobutyronitrile (AIBN) as a free radical initiator. Experimental terpolymerization data agree well with calculations based on the Alfrey-Goldfinger equation. The determination of unitary, binary and ternary azeotropes of the systems studied was easily handled by a computer program. Ternary azeotropic compositions for BTA-NMTP-ST and BTA-NMTP-AN were 71:8:21 and 25:25:50 mol%, respectively. Selective unitary and binary azeotropic compositions were polymerized and the 26:20:54 results obtained show good agreement between the theoretical and experimental terpolymer compositions for each case. Also, pseudo-azeotropic regions were identified where the deviation between feed and polymer composition is very small. The azeotropic points of the four systems were confirmed using Turasov et al's equations and were found to have satisfactory results. (C) 2004 Society of Chemical Industry.

An analysis of the quasielastic and inelastic peaks of neutrons induced by 1.2 GeV protons on targets with 27less than or equal toAless than or equal to232 is presented using the ultrarelativistic quantum molecular dynamics (UrQMD) model. Two distinct contributions of the nuclear medium are studied in the UrQMD framework, referred to as "in-medium" and "mean field" effects. The former only includes modifications to the NN-elastic and NN-->NDelta angular distributions as well as changes to the Delta-mass distribution. The latter incorporates the (QMD) interaction potential between nucleons. It is shown that in-medium effect produces an important role for enhancing the quasi-inelastic peak, while the mean field effect enhances the intensity of both peaks and becomes important in the quasielastic region. The introduction of both effects in the UrQMD calculations improves the intensity and location of the quasielastic and inelastic peaks. A rather smooth dependence of the integrated cross sections of the quasielastic and inelastic peaks on the mass number at both angles is also found and shown to be in qualitative agreement with the UrQMD incorporating these two effects.

A preparatively simple synthesis of N-linked glycopeptoids starting from iminodiacetic acid and glvcosylamines, using hexafluoroacetone as protecting and activating reagent is described.

N-Glycosides of Asn and homologues have been synthesized starting from hexafluoroacetone-protected omega-activated Asp, Glu, and Aad derivatives and glycosylamines. The synthetic value of the new building blocks was demonstrated by the concise incorporation of N-glycosylated Asn, Gln, and Aad omega-amides into glycopeptides.

Five glasses of the AgI-Ag2O-V2O5-P2O5 system exhibiting mixed electronic-ionic conduction were prepared and irradiated by gamma-rays. The structures of the irradiated and unirradiated glasses were studied using density, FT-IR, X-ray diffraction (XRD), electron spin resonance (ESR) and scanning electron microscope (SEM). The electrical conductivity (sigma), dielectric constant (epsilon') and dielectric loss (epsilon") for the irradiated and unirradiated glasses are also investigated over a temperature range between 300-380 K and at a frequency from dc to 10(6) Hz. Both components of ionic sigma(i) and electronic sigma(e) conductivities were separated from the total conductivity sigma(tot) = sigma(i) + sigma(e) using impedance spectroscopy method. The temperature dependencies of electronic and ionic conductivities as well as corresponding transference numbers were studied. The activation energy values E-e and E-i for both conduction processes were determined. The temperature dependence of epsilon' showed an increase in epsilon' with T. Each of epsilon' and epsilon" was found to be dependent on the composition of the glass matrix. The effect of both gamma-radiation and the framework composition of the glass on the electrical properties have been discussed.

The proton-ligand dissociation constant and metal-ligand stability constants of 7-sulfamerazine-azo-5-chloro-8-hydroxyquinoline (H2L) with some transition metal ions were calculated. The stability constants of the complexes with divalent transition metal ions such as Mn2+, Co2+, Ni2+ and Cu2+ are determined potentiometrically in 0.1 M KCl containing 40% (v/v) ethanol-water mixture. The order of the stability constants of the complexes was found to be Mn2+ < Co2+ < Ni2+ < Cu2+. The effect of temperature was studied and the corresponding thermodynamic parameters such as free energy change (DeltaG), enthalpy change (DeltaH) and entropy change (DeltaS) were determined and discussed. The dissociation process of the ligand was found to be non-spontaneous, endothermic and entropically unfavourable. The formation of the metal-ligand complexes has been found to be spontaneous, endothermic and entropically favourable at higher temperatures.

Inhibition of the corrosion of carbon steel in hydrochloric acid solution by some mono- and bis-azo dyes based on 1,5-dihydroxynaphthalene was studied in relation to the concentration of inhibitors using weight loss and potentiostatic polarization techniques. The percentage inhibition efficiency calculated from two methods is in a good agreement with each other. The inhibition mechanism of the additives was ascribed to the formation of complex compound adsorbed on the metal surface. The adsorption process follows Freundlich adsorption isotherm. The formation of the complex compound was studied by conductometric and potentiometric titrations. The stability constants of the Fe-complexes were determined using the latter technique and related to the inhibition efficiency.

In this paper an algorithm based on Adomian's decomposition method is developed to approximate the solution of systems of nonlinear algebraic equations F(X) = 0. Special cases of the system of nonlinear equations are solved using the algorithm of the decomposition method. It turns out that the convergence of this algorithm is rapid. The decomposition method has the advantage of being more concise for numerical purposes. (C) 2003 Elsevier Inc. All rights reserved.

Oligomeric polyester, namely poly(tetramethylene asparate) (PTMA), was synthesized From D,L-aspartic acid and 1,4-butanediol by a melt codensation technique. Polyester-metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Fe(III), Pd(IV), and UO2(II) in DMSO. The polyester-metal complexes were characterized by elemental analysis, UV-Vis, IR spectral studies, magnetic susceptibility measurements and H-1-NMR. Mossbauer spectra of mixed samples of Pd-PTMA and Fe(II)-PTMA with a ratio of 1 : 2 mol showed the iron(III) oxide formed in early stages of the decomposition at 250degreesC is mainly fine-grained and as the temperature is increased, well-crystalline hematic is formed. Above 250degreesC, the Mossbauer spectrum showed the typical six-line pattern of magnetically oriented Fe(III) oxide, but at 800degreesC, the spectrum showed quadrupole interaction characteristic of PdFe2O4, spinel. The metal ions were found to be six-coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (DTA-TG) showed that co-ordination polymers are thermally more stable than polyester; the activation parameters for both decomposition steps were calculated and discussed. (C) 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 942-947, 2004.

To explore the influence of CeO2 doped TiO2 Support on the dispersion, structure and acidic properties of molybdenum oxide species, an investigation was undertaken by using XRD, N-2 adsorption, FTIR and UV-Vis diffuse reflectance techniques in addition to in situ FTIR-pyridine study. In this work, the MoO3/TiO2 and MoO3/TiO2(CeO2) samples were prepared, at the 8 wt.% Mo loading, by incipient wetness impregnation method. The characterization results suggest that the Mo state in the calcined (773 K) MoO3/TiO2 sample is in X-ray amorphous character and exhibit reasonably higher specific surface area (319 m(2) g(-1)) than that of MoO3/TiO2 (CeO2) (273 m(2) g(-1)). The former support also accommodates a sub-monolayer equivalent of MoO3 (8 wt.%) in a highly dispersed state. The UV-Vis spectra indicated that the dispersed Mo in the MoO3/TiO2 sample is in tetrahedral coordination where it is in octahedral coordination on the MoO3/TiO2(CeO2) sample that showed discrete amounts of bulk MoO3 species. It was revealed also that the presence of Ce retarded the strong association rendered between molybdena, and titania and thus, an over-layer of MoO3 was detected; as indicated by IR spectroscopy (1067 cm(-1)), paralleled with an appearance of high intense and sharp XRD lines of TiO2 proposing sintering of the support. The latter result brings up activation of the TiO2 anatase as discrete phase in MoO3/TiO2 (CeO2) as detected from UV-Vis; 380-400 nm. In situ FTIR spectra of pyridine adsorbed on the samples have revealed the following results (i) all the samples exhibit Lewis and Bronsted acid sites (ii) the TiMo and TiCeMo samples exhibit higher Bronsted acidity (1645-1636 and 1543 cm(-1)) than that of TiCe and rather presented basic sites similar to those offered by TiCe but of lower concentration. (C) 2004 Elsevier B.V. All rights reserved.

The corrosion behavior of aluminium in 2 M HCl solution in the absence and presence of four compounds of antibacterial drug was investigated using hydrogen evolution, weight loss, and potentiostatic polarization techniques. It was found that, the inhibition efficiency of these compounds depends on their concentration and chemical structure. The inhibitive action of these compounds was discussed in terms of blocking the electrode surface by adsorption of the molecules through the active centers contained in their structure. The adsorption process follows Langmuir adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds was also, studied. Some activated thermodynamic parameters were computed. (C) 2003 Elsevier Ltd. All rights reserved.

In this paper, we will discuss the notion of Lipschitz and Lipschitz phi(0)-stability for systems of functional differential equations employing the method of perturbed Liapunov functionals. (C) 2004 Elsevier Ltd. All rights reserved.

The construction and general performance of thirteen new polymeric membrane sensors for the determination of fexofenadine hydrochloride based on its ion exchange with reineckate, tetraphenylborate and tetraiodomercurate have been studied. The effects of membrane composition, type of plasticizer, pH value of sample solution and concentration of the analyte in the sensor internal solution have been thoroughly investigated. The novel sensor based on reineckate exchanger shows a stable, potentiometric response for fexofenadine in the concentration range of 1 x 10(-2) - 2.5 x 10(-6) M at 25degreesC that is independent of pH in the range of 2.0 - 4.5. The sensor possesses a Nernstian cationic slope of 62.3 +/- 0.7 mV/concentration decade and a lower detection limit of 1.3 x 10(-6) M with a fast response time of 20 - 40 s. Selectivity coefficients for a number of interfering ions and excipients relative to fexofenadine were investigated. There is negligible interference from almost all studied cations, anions, and pharmaceutical excipients, however, citrizine that has a structure homologous to that of fexofenadine was found to interfere. The determination of fexofenadine in aqueous solution shows an average recovery of 99.83% with a mean relative standard deviation (RSD) of 0.5%. Direct potentiometric determination of fexofenadine in tablets gave results that compare favorably with those obtained by standard spectrophotometric methods. Potentiometric titration of fexofenadine with phosphomolybdic acid as a titrant has been monitored with the proposed sensor as an end point indicator electrode.

The voltammetric response of per-cathodic activated carbon steel electrode in deaerated 0.50 M NaHCO3 solution at pH 8.72 and 25degreesC at a scan rate of 25 mV s(-1) was investigated. The influence of cycling, potential excursion and scanning rate on the anodic behavior was studied. The results revealed a specific effect of HCO3- ions on the overall anodic process. The complex reaction pathways involving possible competitive anodic consecutive steps and related intermediates were discussed and summarized.

The decomposition method for solving the Klein-Gordon equation has been implemented. The explicit and numerical solutions of the equation are calculated in the form of convergent power series with easily computable components. The present method performs extremely well in terms of accuracy, efficiency, simplicity, stability and reliability. We also proved the convergence of Adomian's decomposition method for the nonlinear Klein-Gordon equation. (C) 2003 Elsevier Inc. All rights reserved.

The notion of phi(0)-stability recently was introduced. In this paper, we will extend this notion to the so-called eventual phi(0)-stability for impulsive systems of differential equations under more relax conditions. Our technique depends on Lyapunov's direct method. (C) 2003 Published by Elsevier Inc.

We implemented the Adomian decomposition method (for short, ADM) for approximating the solution of the seventh-order Sawada-Kotera (for short, sSK) and a Lax's seventh-order KdV (for short, LsKdV) equations. By using this scheme, explicit exact solution is calculated. We obtain the exact solitary-wave solutions and numerical solutions of the LsKdV and sSK equations for the initial conditions. The numerical solutions are compared with the known analytical solutions. Their remarkable accuracy are finally demonstrated for the both seven-order equations. (C) 2003 Elsevier Inc. All rights reserved.

A simple and reproducible spectrophotometeric method for the assay of cefotaxime sodium, cefuroxime sodium, and ceftriaxone disodium with metol-chromium(VI) reagent has been developed. The procedure is based on direct oxidation of metol by potassium dichromate in presence of drug in acidic medium and subsequent formation of ternary complex. Beer's law is obeyed in the range 0.2-28 mug ml(-1) at lambda(max) 520 nm. For more accurate analysis, Ringbom optimum concentration range is found to be 0.8-26.5 mug ml(-1). The molar absorptivity and Sandell sensitivity were calculated. Six replicate analysis of solutions containing seven different concentrations of the examined drugs were carried out and gave a mean correlation coefficient less than or equal to0.9996; the factors of the regression line equation for the three cephalosporins were calculated. The proposed method was applied to the determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official methods. (C) 2004 Elsevier B.V. All rights reserved.

Fatty acids isothiocyanate (1) was used as a starting material to synthesize some important heterocycles such as triazoles, oxazoles, thiazoles, benzoxazoles and quinazolines by treating with different types of nucleophiles such as nitrogen nucleophiles, oxygen nucleophiles, and sulfur nucleophiles. The produced compounds were subjected to propylene oxide in different moles (n = 3, 5 and 7) to produce novel groups of nonionic compounds having the double function as antimicrobial and surface active agents which can be used in the manufacturing of drugs, cosmetics, pesticides or can be used as antibacterial and/or antifungal. The physical properties as surface and interfacial tension, cloud point, foaming height, wetting time, emulsification power and the critical micelle concentration (CMC) were determined, antimicrobial and biodegradability were also determined.

We study the solitary-wave solutions of the (2 + 1)-dimensional Boussinesq equation u(tt)-u(xx)-u(yy)-(u(2))(xx)-u(xxxx)= 0 and (3 + 1)-dimensional KP equation u(xt)-6u(x)(2) + 6uu(xx)-u(xxxx)-u(yy)-u(zz)=0. In this paper by considering the decomposition scheme, we first obtain the exact solitary-wave solutions of the (2 + I)-dimensional Boussinesq equation and (3 +1)-dimensional KP equation for the initial conditions without using any classical transformations and then its numerical solutions are constructed without using any discretization technique. The numerical solutions are compared with the known analytical solutions. Its remarkable accuracy is finally demonstrated in the study of (2 + 1)-dimensional Boussinesq equation and (3 + 1)-dimensional KP equation. (C) 2003 Elsevier Inc. All rights reserved.

Adomian's decomposition method (ADM) is proposed to approximate the numerical and analytical solutions of system two-dimensional Burgers' equations (STDBE) with initial conditions. The advantages of this work are the decomposition method reduces the computational work and improvement with regard to its accuracy and rapid convergence. Some examples are given to illustrate the performance of the method described. (C) 2003 Elsevier Inc. All rights reserved.

This paper concerns the analytical study of the non-isothermal flow of a non-Newtonian power law lubricant through the gap of a conical bearing when an external magnetic field is applied. At first, the more general basic equations of motion, continuity and energy in curvilinear form in the width direction are derived. Then, as a special case, a conical bearing gap is considered. By integrating a modified form of Reynolds equation the bearing characteristics for a non-Newtonian power law lubricant when an external magnetic field is applied are obtained. Numerical results were presented in each of these forms: pressure, temperature and capacity of the conical bearing. The effects of the parameters of the non-Newtonian power law and magnetic field are shown and discussed. (C) 2004 Elsevier Inc. All rights reserved.

Simple and convenient synthesis for a series of 2,3-diglycosylpyrimidine 4, pyrazolo [3,4]-pyrimidine 8, ditetrazolo [1,5-a; 1',5'-c] pyrimidine 9,2,9a,10-triazaanthracene 12, thieno[2,3-d]pyrimidine 14,1,3,5,7-tetraazafluorene-8-one 15, 1,3,5-triazafluorene-8-one 16,1,3-diazafluorene 21a,b derivatives have been synthesized via a sequence of heterocyclization reactions of suitably functionalized 6-[5-(4-bromophenyl)oxazol-4-yl]-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile (2) with different electrophiles and nucleophiles. The new compounds were prepared with the objective to study their pharmacological properties.

The synthesis of Ce3+, Th4+, and UO22+ complexes with six azo compounds based on 4-methyl-6,7-dihydroxy-8-arylazo coumarin is reported. The azo compounds were expected to coordinate through O and N either in the azo or in the hydrazone form, but different physicochemical studies (elemental and thermal analysis, molar conductance, IR, magnetic susceptibility, H-1-NMR, and electronic absorption spectra) show that they coordinate via O, O with the coumarins acting as mono (or sometimes di-) basic and bidentate ligands. Biological activity of some complexes has been evaluated against some filamentous microscopic fungi, yeast, and bacteria. The results are compared to those of the free ligands.

p-Acryloyloxybenzoic acid (PAB) was prepared by the reaction of p-hydroxybenzoic acid and acryloyl chloride in the presence of triethylamine. Triphenyltin acrylate (TPTA), triphenyltin methacrylate (TPTMA), p-acryloyloxytriphenyltin benzoate (TPTB) and triphenyltin itaconate (TPTI) monomers were prepared by the reactions of acrylic, methacrylic, p-acryloyloxybenzoic and itaconic acids, respectively, with triphenyltin hydroxide in the presence of dicyclohexylcarbodiimide (DCCI) as a dehydrating agent. Binary copolymerizations of PAB with TPTA, TPTMA, TPTB and TPTI were performed in dimethylformamide (DMF) using 1 mol% azobisisobutyronitrile (AIBN) as initiator at 65 degreesC. The structures of the monomers and copolymers were investigated by IR and H-1 NMR spectrometry. The composition of the copolymers was determined by tin analysis. Copolymerization parameters for each system were calculated by both the Fineman-Ross and Kelen-Tudos methods. The monomer reactivity ratios for the four systems studied, PAB-TPTA, PAB-TPTMA, PAB-TPTB and PAB-TPTI, were found to be r(1) = 0.468, r(2) = 2.096; r(1) = 0.43S, r(2) = 2.292; r(1) = 0.449, r(2) = 2.22S and r(1) = 0.416, r(2) = 4.526, respectively. The average Q and e values for the prepared organotin monomers were calculated. (C) 2004 Society of Chemical Industry.

Purpose - To prepare and characterise organotin polymers via a new synthetic route by exchange reactions of poly-N-acryloyloxy- and poly-N-methacryloyloxy-tetrabromophthalimide with hydroxy- and aminotri-n-butyltin benzoates. Design/methodology/approach - Preparation of N-acryloyloxytetrabromophthalimide (NATP) and N-methacryloyloxytetrabromophthalimide (NMTP) by the reaction of N-hydroxytetrabromo-phthalimide with acryloyl or methacryloyl chloride. The exchange reactions of the resulting polymers with amino and hydroxytri-n-butyltin benzoate were carried out. The structure of the resulting compounds was characterised. Findings - NATP and NMTP were prepared by the reaction of N-hydroxy-tetrabromophthalimide with acryloyl or methacryloyl chloride in the presence of TEA. The monomers prepared were easily polymerised. The exchange reactions of poly-NATP and poly-NMTP with amino and hydroxytri-n-butyltin benzoate were studied. The structure of the polymers and copolymers prepared was confirmed by tin analysis, IR and (HNR)-H-1 spectroscopy. Research limitations/implications - The new monomer described in the present investigation may be useful for the preparation of organotin polymers by a new synthetic route. Also, the organotin polymers prepared had good film properties and were suitable for film formation. Practical implications - The method for the preparation of monomer is simple and the exchange reactions provide a simple and practical solution for preparation of some classes of organotin polymers and copolymers. Originality/value - The method of preparation of organotin polymers was novel and may be useful for preparation of other organotin polymers and copolymers.

Purpose - To determine the optimal general condition for the synthesis and polymerisation of 2-(N-phthalimido)ethyl acrylate (NPEA), as well as the exchange reactions of poly-NPEA with aminated and hydroxylated compounds as a model compound. Design/methodology/approach - Preparation of 2-(N-phthalimido)ethyl acrylate by the reaction of N-(2-hydroxyethyl) phthalimide with acrylic acid and polymerisation of the resulting monomer. The exchange reactions of the resulting polymer with amines and hydroxy compounds were carried out. The structure of the resulting compounds were characterised. Findings - NPEA was prepared by the reaction of N-(hydroxyethyl)phthalimide with acrylic acid. The monomer prepared was easily polymerised. The reactions of the resulting polymer with amines and hydroxy compounds were studied. In all cases, the exchange reactions were almost practically quantitative, which was confirmed by elemental analysis, IR and (HNMR)-H-1 spectroscopy. Also, it was clear that poly-NPEA showed a good behaviour as a model compound for a long active polymeric-drug. Research limitations/implications - The new monomer described in the present investigation may be useful for the preparation of polymeric-drug adducts. Also, similar monomeric phthalimides may be synthesised starting from a number of other hydroxy or amino acids, thus providing wider possibilities for the synthesis of pharmacologically active polymers. Practical implications - The method for preparation of monomer is simple and the exchange reactions provide a simple and practical solution to prepare some classes of macromolecular drugs. Originality/value - The method of preparation of polymers was novel and may be useful for preparation of polymeric-drug adducts.

Purpose - Preparation of new organotin polymers via a new synthetic route based on the exchange reactions of pentachlorophenyl acrylate or methacrylate with amino-tri-phenyltin benzoates or hydroxyl-tri-phenyltin benzoates. Design/methodology/approach - The pentachlorophenyl acrylate or methacrylate was prepared by polymerisation in solution with azobisisobutyrontrile as a free radical initiator. The polymers obtained were allowed to undergo exchange reactions with amino-tri-phenyltin benzoates or hydroxyl-tri-phenyltin benzoates. The structure of the polymers prepared was confirmed by IR spectroscopy. Films were prepared from purified organotin polymers solution on glass, PVC and tin plates. The release of tin compound from the films, when immersed in aqueous media, was assessed. The concentration of the released tin (ppm) was measured by atomic adsorption spectrophotometer. Findings - The new synthetic route was effective, the organotin polymers prepared had good film properties and the release of tin compounds increased with the content of tin in the organotin polymers. Research limitations/implications - The alkaline resistance of the polymeric films prepared needs improvement. Practical implications - The polymers prepared provide a family of effective polymeric fungicide useful for a number of applications including water sterilisation. Originality/value - The polymers prepared contained pendent triphenyltin moieties which slowly hydrolysed to give fungicidal and antifouling effects.

A new series of anionic surfactants with dual type of activity antimicrobial and surface activity have been synthesized by reaction of 4H-3,1-benzoxazinone 3 and quinazolinethione 10 with nitrogen nucleophiles and activated olefinic compounds. The compounds were evaluated for their surface activity as well as their antimicrobial and biodegradability properties.

Spectrophotometric investigation of palladium(II) or of tartaric acid in presence of niobium(V) were conducted using their colour reactions with 5-(benzothiazolyl-azo)2,5-naphthalenediol (I), 1-(2-benzothiazolylazo)2-hydroxy-3-naphthoic acid (II) and 5-(2-benzothiazolylazo)8-hydroxyquinoline (III) in acidic medium, or weak acidic medium. The stoichiometric ratios and stability constants of the formed complexes were determined. The calibration graphs were linear in the range of 0.02-1.35, 0.02-1.20, and 0.02-1.10 mugmL(-1) of Pd2+ with apparent molar absorptivities of 6.15 x 10(4), 7.27 x 10(4) and 5.80 x 10(4), L mol(-1) cm(-1) using I, II, and III, respectively, at lambda(max) 638, 677, and 656 nm. On the other hand, calibration graphs for tartaric acid in the presence of Nb5+ were linear in the 0.01-1.60, 0.01-1.7, and 0.01-1.45 mug mL(-1) range with s of 1.27 x 10(5), 1.13 x 10(5), and 1.45 x 10(5) L mol(-1) cm(-1) at 692, 649, and 661 nm, respectively. Sandell sensitivity, detection, and quantification limits were also calculated. The proposed methods were selective and sensitive in comparison with other methods and the effect of foreign ions Cu2+, Ni2+, and Fe2+ was negligible for the assay of Pd2+.

Deep electronic states associated with iron silicide precipitates have been studied by means of deep-level transient spectroscopy. The observed spectra show the characteristic features of bandlike states at extended defects, From the stability of the states on annealing at moderate temperature they are tentatively attributed to precipitate-matrix interfaces.

Epoxide derivative II was used to synthesize a number of new condensed and noncondensed heterocyclic systems. Thus, reaction of II with amines, hydrazines, active methylene compounds and Friedel-Crafts reactions have been studied. On the other hand, II reacted with Grignard reagents and afforded products with an open epoxide ring. However, II condensed with thiourea and glycine gave oxazolinethione and 2-morpholinone derivatives. Also, II reacted with acetic acid and gave hydroxypropanoyl derivative. Action of different nitriles with II gave the hydroxy amide derivatives, which underwent cyclization and afforded 2-oxazoline derivatives.

The electrical properties measurements were carried out for the complex (CH2)(2)Mn1-xCdxCl4, 0.0 less than or equal to x less than or equal to 1.0 at different temperatures as a function of frequency (100-1000 kHz). Four transition points were obtained for x = 0.5, which were assigned as thermochroism, interlayer exchange interaction, order-disorder and chain melting transition. The presence of more than one straight line in the conductivity data clarifies the presence of more than one conduction mechanism, and the calculated values of the activation energy indicate the semiconducting characteristics of the investigated complexes. The values of the relaxation time depend on Cd-content as well as the heating temperature. The expected critical concentration at x = 0.5 agrees well with the percolation theory of Mont-Carlo group. The IR spectra indicate that, the force constant of the bonds and the atomic mass vibration are affected by Cd-content. (C) 2005 Springer Science + Business Media, Inc.

Seven samples of the system Cu1-xCdxFe2O4 were prepared by thermal decomposition of mixed metal oxalates with x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0. The formation of the ferrispinel was studied by XRD, FT-IR, Mossbauer spectroscopy, electrical conductivity and magnetic susceptibility measurements. XRD showed single cubic spinel phase for all the samples except for CuFe2O4 sample which shows a tetragonal structure. An increase in the lattice parameter of the ferrispinel was observed with increasing the cadmium content. The temperature variation of ac conductivity showed four definite regions with three transitions which attribute to the change in the conduction mechanism with increasing temperature. Magnetic properties of the sample with x < 0.5 showed a decrease in the effective magnetic moment with the increase in the cadmium content which means that the ferromagnetics are widely separated and enclosed by non-magnetic cadmium ions. A well defined hyperfine Zeeman spectrum is observed for samples with x greater than or equal to 0.3 at room temperature and resolved into two sextets corresponding to the octahedral and tetrahedral sites. The propable ionic configuration of the system proposed is (CdxCuyFe1-x-y)[Cu1-x-yFe1+x+y]O-4. (C) 2005 Springer Science + Business Media, Inc.

Cerium containing mordenites catalysts were prepared by impregnation (CeMimp), solid-state ion exchange (CeMss) and in situ incorporation during synthesis (CeMin). The structure of the samples has been investigated by X-ray diffraction. FT-IR, N-2 adsorption, thermal analyses (TG and DTA) and pyridine-FT-IR. Water-gas shift reaction (WGSR) was carried out over various catalysts and the catalytic reaction was monitored using in situ FT-IR. The results obtained showed the presence of cerium silicate phase, in case of CeMin sample as evidenced by XRD and FT-IR spectroscopy. In case of CeMimp and CeMss, a separate CeO2, phase was observed in a highly dispersed state in the former than in the latter, which measured the highest specific surface area. FT-IR results of pyridine adsorption indicate the presence of acid-base site pairs on the surface of CeMimp and CeMss samples where only Lewis acidity was found on CeMin, reflecting the presence of Ce3+ with Si4+ cations at tetrahedral lattice sites in mordenite. CeMimp showed the highest catalytic activity followed by CeMss. It has been shown that reduction by H-2 carried out at 500degreesC was responsible for activating different carbonyls attached to Ce3+; such as Ce3+-CO and Ce3+-(CO)2 which decomposed into CO2 (ads). The role of basicity, Ce dispersion and surface texture of reduced Ce-mordenites on their catalytic activity in CO oxidation by H2O was evaluated and discussed. (C) 2004 Elsevier B.V. All rights reserved.

Quenching the beta-lithiated benzotriazolylvinyl ethyl ether 2 with aldehydes, acid chlorides and chalcones provided the corresponding beta-hydroxyalkyl derivatives 4a-f, beta-keto vinyl ethers 7a,b, and Michael adducts 8a,b, respectively. The alkylated product 4 was converted into alpha, beta-unsaturated ketones 5a-f upon treatment with bromine. beta-Keto vinyl ethers 7a,b cyclocondensed with hydrazines to afford pyrazoles 9a-d, and with hydroxylamine hydrochloride to give isoxazoles 10a,b. Treatment of 8 with phosphorus pentachloride resulted in the formation of 2,4,6-triarylpyrylium chlorophosphates 12.

A new series of anionic surfactants having double function as antimicrobial and surface active agents have been synthesized by reaction of 4(H)-3,L-benzoxazinone 3 and quinazolinethione 10 with nitrogen nucleophiles and-activated olefinic compounds. The compounds were evaluated for their surface activity as well as the antimicrobial and biodegradability properties.

2-thiozyl methacrylamide (TMA) was synthesized by the reaction of 2-aminothiazole with either methacryloyl chloride or methacrylic acid in the presence of triethylamine and N, N '-dicyclohexylcarbodiimide, respectively. Binary copolymerization reactions of the prepared monomer with methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (BA) and tert-butylacrylate (t.BA) were performed in dimethylformamide at 65 degrees C using 1 mol% azobisisobutyronitrile (AIBN) as initiator. The structure of the 2-thiozyl methacrylamide monomer and the prepared copolymers was investigated by IR and H-1 NMR spectroscopy. The copolymer compositions were determined from sulphur analysis. Copolymerization parameters for each system were calculated by the Finemen-Ross and Kelen-Tudos methods. The monomer reactivity ratios for the systems TMA-MA, TMA-EA, TMA-BA, and TMA-tBA were found to be r(1) = 0.128, r(2) = 0.740; r(1) = 0.235, r(2) = 0.420; r(1) = 0.420, r(2) = 0.330 and r(1) = 1.690, r(2) = 0.027, respectively. The reactivities of acrylic esters decrease as the alkyl group become bulkier. The average Q and e values for TMA were calculated from the monomer reactivity ratios determined in the present and previous studies.

The aqueous extract of the leaves of henna (lawsonia) is tested as corrosion inhibitor of G steel, nickel and zinc in acidic, neutral and alkaline solutions, using the polarization technique. It was found that the extract acts as a good corrosion inhibitor for the three tested electrodes in all tested media. The inhibition efficiency increases as the added concentration of extract is increased. The degree of inhibition depends on the nature of metal and the type of the medium. For C-steel and nickel, the inhibition efficiency increases in the order: alkaline < neutral < acid, while in the case of zinc it increases in the order: acid < alkaline < neutral. The extract acts as a mixed inhibitor. The inhibitive action of the extract is discussed in view of adsorption of lawsonia molecules on the metal surface. It was found that this adsorption follows Langmuir adsorption isotherm in all tested systems. The formation of complex between metal cations and lawsone is also proposed as additional inhibition mechanism of C-steel and nickel corrosion. (C) 2004 Elsevier Ltd. All rights reserved.

Complexes of derivatives of 2,5-dichlorosalicylanilide with transition metal ions, Cu2+ Co2+, Ni2+, Zn2+ and Fe3+, were been prepared and studied using microanalysis, electronic, IR, H-1-NMR spectra and TGA. Thermal stability and activation energies were determined. The pK-H values of these anilides have been investigated by spectrophotometry and potentiometric methods, and the optimum conditions favouring the formation of the coloured complexes have been studied. Anilide is found to behave as an inhibitor for the corrosion of iron in acidic solutions.

The effect of quadratic and cubic non-linearities in elastomeric material dampers used to quiet torsional oscillations of internal-combustion engines sharts is investigated. In the present work, a non-linear elastomeric damper or absorber is used to control the torsional vibrations of the crankshaft in internal combustion engines, When Subject to external excitation torque. The method of multiple scales is used to derive four first-order differential equations governing the modulation of the amplitudes and phases of the two modes of the crankshaft and the absorber for the fundamental resonance. These equations are used to determine the steady state amplitudes and system stability. A relationship that relates the elastomer properties and other system parameters is found. The effects of damping, detuning, non-linear terms, and magnitude of excitation are analyzed. A stability analysis is performed on the steady state Solutions. (C) 2004 Published by Elsevier Inc.

We studied the effect of the semiclassical molecular initial ground state configuration of the nucleus on the neutron spectra for p+Al, Fe, and Zr at 1.2 GeV by using an improved ultrarelativistic quantum molecular dynamics (ImUrQMD) model. Compared to the standard UrQMD version, it incorporates: (i) Pauli potential, (ii) a medium modified NN -> N Delta angular distribution, and (iii) a statistical multifragmentation decay model as an afterburner. It is shown that the slow evaporated, cascade, and quasielastic (inelastic) peaks of neutrons are all sensitive to different initialization procedures. Therefore, the implementation of a proper semiclassical ground state initialization in the ImUrQMD model is of importance for the description of all the neutron spectra in proton-induced reactions at intermediate energies (approximate to 1GeV).

Silica sources can influence different aspects of ZSM-5 crystallization and it leads to change in the properties of the final product. The crystallinity of nanosized ZSM-5 zeolite from precursors mixtures containing different silica sources, e.g. tetraethylorthosilicate (TEOS), colloidal silica (Ludox LS 30), sodium metasilicate and fumed silica have been studied. The produced samples are investigated using XRD, SEM, and carbon % in the samples after calcination in air and BET surface area. The product obtained by TEOS, fumed silica and colloidal silica is ZSM-5 phase, but the product obtained by sodium metasilicate is the quartz phase. The crystallinity, and % of the nanosized ZSM-5 zeolite increased in the following order: sodium metasilicate < colloidal silica < TEOS < fumed silica. The average crystal size increased in the following order: fumed silica < TEOS < colloidal silica < sodium metasilicate. The surface area increased in the following order: sodium metasilicate < colloidal silica < TEOS < fumed silica. The template was almost completely removed from the ZSM-5 by calcination at 550 degrees C for 8 h in air. (c) 2004 Elsevier Inc. All rights reserved.

In this investigation, two mixes were used: ordinary Portland cement (OPC) and a blended cement prepared with the partial substitution of OPC by 10 mass% silica fume (SF). The setting and hardening characteristics were monitored by the aid of electrical conductivity as a function of curing time. The shear stress and electrical conductivity were studied at different temperatures, namely, 20, 35, 45 and 55 degrees C. As the temperature increases, the shear stresses decrease with the increase of shear rate. The height of electrical conductivity peaks of superplasticized cement pastes increases due to the increase of the paste fluidity. In the presence of 1.0% polycarboxylate (PC), the electrical conductivity of cement pastes decreases from 1 to 28 days. PC retards the hydration of cement pastes. The presence of PC extended the setting times of cement pastes at 35 degrees C than at 20 degrees C due to the increase in the adsorption capacity at this temperature. PC extends the dormant stage of the hydration process and delays the onset of the accelerating stage, without affecting its rate. (c) 2004 Elsevier Ltd. All rights reserved.

The concept of phi(0)-stability and phi(0)-boundedness recently were introduced for systems of ordinary differential equations (ODEs). Perturbing Liapunov function method was discussed for systems of ODEs and extend to systems of functional differential equations (FDEs). In this paper, we extend these notions to impulsive systems of differential equations via cone perturbing Liapunov function method. (c) 2004 Elsevier Inc. All rights reserved.

Lipschitz phi(0)-stability notion was introduced. In this paper, we will discuss the notion of Lipschitz phi(0)-stability of comparison systems of differential equations. Our technique depends on limiting equation method. (c) 2004 Published by Elsevier Inc.

The notions of practical stability of systems of ordinary differential equations (ODE) was introduced. In this paper, we will extend practical stability notion to a new type of stability called practical phi(0)-stability of perturbed systems of ordinary differential equations, and given Some criteria and results. Our technique depends on cone-vector Liapunov function method. (c) 2004 Elsevier Inc. All rights reserved.

The principal parametric resonance of a single-degree-of-freedom system with non-linear two-frequency parametric and self-excitations is investigated. In particular, the case in which the parametric excitation terms with close frequencies is examined. The method of multiple scales is used to determine the equations that describe to first-order the modulation of the amplitude and phase. Qualitative analysis and asymptotic expansion techniques are employed to predict the existence of steady state responses. Stability is investigated. The effect of damping, magnitudes of non-linear excitation and self-excitation are analyzed. (c) 2004 Elsevier Ltd. All rights reserved.

The in situ interaction of nitric oxide (NO) gas on the cerium framework-substituted ZSM-5 and mordenite zeolites was studied by FT-IR spectroscopy. Samples of ZSM-5 and mordnite-containing cerium (7.5 wt.% expressed as CeO2) have been hydrothermally synthesized from starting gel upon which the introduction of cerium is being made during synthesis of zeolites. The morphological and textural characteristics of cerium-free and cerium-containing zeolites were studied using XRD, FT-IR in the T-O range, and N-2 adsorption at -196 degrees C. The results revealed that the insertion of cerium in both zeolites led to a decrease in their degree of crystallinity. Such a decrease was 36% for Ce-ZSM-5 while it was 18% for Ce-mordenite. The results indicated a significant decrease in nitrogen sorption capacity (BET) by 31% from 624 to 431 m(2)/g and also a decrease of the micropore volume by 27.8% from 0.579 to 0.418 cm(3)/g for Ce-ZSM-5. These results were found on the other extreme in case of Ce-mordenite. The presence of Cc did not affect the cell volume of ZSM-5 much, while it increased that of mordenite. Most of Ce-IV ions were embedded in the framework of mordenite, where they exposed as extra-framework CeO2 and cerium silicate in ZSM-5. The in situ interaction of NO on Ce-zeolites was studied using an FT-IR quartz cell. The adsorption of NO gas led to the formation of a series of nitrosyl species: N2O (2245 cm(-1)), NO+ (2160 cm(-1)), NO (1910 cm(-1)), N2O3 (1880, 1580 cm(-1)), (NO)(2s,as) (1844, 1734-1720 cm(-1)), NO2 (1630 cm(-1)) and ionic compounds were stable upon evacuation, i.e. nitrato and nitrito NOx- (x = 2-3) (1300-1500 cm(-1)). Such nitrosyl complexes were favorably formed on Ce-ZSM-5 than on Ce-mordenite due to facilitated intervention of the cerium couple (Ce-III/Ce-IV) on the former than on the latter. (c) 2005 Elsevier B.V. All rights reserved.

The dynamic stability and complicated motions of a vessel in regular sea are investigated when the frequency in the pitch is nearly twice the Frequency in the roll. We use the Method of Multiple Scales to determine four first-order nonlinear ordinary differential equations that govern the modulation of the amplitudes and phases when the forcing frequency is near either the pitch or the roll natural frequency. These equations are used to determine the steady-state solutions and their stability. Force-response and frequency-response curves are generated. Coexistence of multiple solutions is found in the presence of quadratic nonlinearities. The linear solution is symmetric. The pitch mode has multi-valued solutions and the roll mode has a single-valued solution for the case of primary resonance of the pitch mode. Both pitch and roll modes have multivalued solutions in small intervals for the case of primary resonance of the roll mode.

An SIRS epidemic model with general periodic vaccination strategy is analyzed. This periodic vaccination strategy is discussed first for an SIRS model with seasonal variation in the contact rate of period T = 1 year. We start with the case where the vaccination strategy and the contact rate have the same period and then discuss the case where the period of the vaccination strategy is LT, where L is an integer. We investigate whether a periodic vaccination strategy may force the epidemic dynamics to have periodic behavior. We prove that our SIRS model has a unique periodic disease free solution (DFS) whose period is the same as that of the vaccination strategy, which is globally asymptotically stable when the basic reproductive number Ro is less than or equal to one in value. When R-0 > 1, we prove that there exists a non-trivial periodic solution of period the same as that of the vaccination strategy. Some persistence results are also discussed. Threshold conditions for these periodic vaccination strategies to ensure that R-0

T HE CORROSION behaviour of a cadmium electrode in Na2CO3 and HCl solutions was studied in the absence and presence of five compounds of cationic surfactants of olyelamido derivatives using potentiostatic polarization technique. The inhibition efficiency was found to increase with increasing the inhibitor concentration and the number of polyethylene diamine units, and decrease with rising temperature. These compounds are more effective in HCl than in Na2CO3 solutions. This can be attributed to the synergistic effect of Cl- ions with the cationic surfactant compounds. The inhibitors are adsorbed on the surface of Cd in both HCl and Na2CO3 solutions according to Langmuir adsorption isotherm. The effect of temperatures was studied to evaluate some activated thermodynamic parameters.

In the present work the spectra of even-even Hf isotopes are studied through the selecting of core-cluster decomposition of the parent nucleus. The considered partition should give internal stability of the core-cluster combination. The modified Woods-Saxon and Coulomb potentials are used to reproduce the spectra of even-even Hf isotopes where the core-radius is taken as a free parameter. The theoretical calculations of the excitation energies and the transition probabilities B(E2) of the ground state band are compared to the experimental data of the considered Hf isotopes. The obtained results reflect the ability of describing the pure rotational ground state band of even-even Hf isotopes through the core-cluster decomposition model.

This paper presents a modification of Rojo's algorithm [Comput. Math. Appl. 20 (1990) 61] to solve block circulant tridiagonal systems of linear equations which are Toeplitz and Hermitian. This new approach gives us a general direct algorithm for solving the problem. We will show how to choose a block matrix as a parameter to describe the method. We employ the factorization of block Toeplitz tridiagonal matrices as the product of two block Toeplitz subdiagonal and superdiagonal matrices. The algorithm is based on obtaining the solution of the nonlinear matrix equation A = Gamma + B*Gamma(-1) B. Finally, some numerical results will be given. (c) 2004 Elsevier Inc. All rights reserved.

The 8 wt.% MoO3-modified CeO2 materials were prepared by three different methods namely, impregnation, wet mechanical mixing and co-precipitation and characterized by thermal analyses (TG and DTA), X-ray diffractometry, infrared spectroscopy, UV-vis diffuse reflectance spectroscopy as well as nitrogen sorptometry. Their catalytic activities in the oxidation of CO to CO2 were also examined. The results showed that the material prepared by co-precipitation provided the highest activity, comparatively. This was due to the concomitant strong metal oxide-support interaction revealed for this material that validated by XRD and FTIR results those showed diminishing in particles size of the two ions and formation of Mo-O-Ce linkages (760 cm(-1)), respectively. The UV-vis spectrum of this material showed the predominant presence of tetrahedral Mo6+ reflecting the highest dispersion among all samples. This material exhibited as well the highest specific surface area (96 m(2)/g) and rather presented mesopores of regular distribution. Important correlations between the latter material and those prepared by impregnation and wet mechanical mixing in view of proposed interaction between ions, morphology, surface texturing and their effects on the activity of CO oxidation were evaluated and discussed. It is inferred that surface molybdate that permit the formation of Mo6+ in highly dispersed state beside the Ce3+/Ce4+ redox couples were responsible for the revealed catalytic activity. (c) 2005 Published by Elsevier B.V.

The present paper treats iterative methods for a class of nonlinear matrix equations X + A star X(-alpha)A = I, with two cases: alpha >= 1 and 0 < alpha < 1. Here, the matrix A is nonsingular. We will derive the necessary and sufficient conditions for the existence of positive definite solutions. (c) 2005 Elsevier Inc. All rights reserved.

The ultra-relativistic quantum molecular dynamics (UrQMD) model is developed for neutron spallation production from approximate to 1 GeV proton-induced reactions. Improvements in the dynamical content of the standard UrQMD model include: (i) an initial ground state which reproduces the experimental root mean square radii; (ii) a momentum-dependent Pauli potential and (iii) medium-modified angular distributions for quasi-inelastic NN scattering and the reverse N Delta -> NN reaction. It is shown that, in conjunction with the generalized evaporation model, the improved UrQMD model is able to reproduce the whole energy-angle neutron double differential cross sections in the interactions of proton on Al, Fe and Zr at 1.2 GeV.

The electrical properties of the solid electrolytes Ag7I4VO4-Al2O3 (0-40 mol% Al2O3) are investigated. The electrical conductivity, dielectric constant and dielectric loss are increased by increasing the concentration of Al2O3; showing a maximum at 30 mol% Al2O3. The conductivity is found to be increased by decreasing the particle size of Al2O3. The results are explained using the random resistor network model (RRN). This is due to the formation of a highly conducting interface layer along the matrix-particle interface. This layer is destroyed at concentrations higher than 30 mol% Al2O3. (c) 2005 Published by Elsevier Ltd.

Calcium aluminate cement (CAC) pastes containing Egyptian air-cooled slag (AS) or water-cooled slag (WS) were prepared using different amounts of slag, namely, 5, 10, 15, 20 and 25 mass%. The pastes were prepared with deionized water using the required water of standard consistency to produce normal workability. The variations of electrical conductivity with the hydration time were measured at 20, 40 and 60 degrees C. The results demonstrate that electrical conductivity is a useful technique to study the change in the phase composition at different temperatures during the setting and hardening of calcium aluminate cement as well as reflecting the role of AS and WS, preventing the conversion occurring during the CAC hydration. (c) 2004 Elsevier Ltd. All rights reserved.

A simple phenomenological potential model is suggested to describe the interaction between the constituent quarks of meson systems. Taking the spin-dependence terms in consideration modifies some previous potential models. The resonance masses and the leptonic decay widths of c (c) over bar, b (b) over bar, c (s) over bar, b (u) over bar, and c (b) over bar mesons are calculated using the nonrelativistic wave equation. A comparison between the present calculations and the available experimental results are given.

An approach for implementing an active nonlinear vibration absorber is presented. The strategy uses the saturation phenomenon that is exhibited by multi-degree-of-freedom systems with cubic nonlinearities possessing one-to-one internal resonance. The proposed technique consists of introducing a second-order controller and coupling it to the plant through a sensor and an actuator, where both the feedback and control simals are cubic. Once the structure is forced near its resonances, the oscillatory response is suppressed through the saturation phenomenon. We present theoretical results of the application of the proposed vibration absorber. The structure consists of a cantilever beam. the feedback signal is generated by a strain gage, and the actuation is achieved through piezoceramic patches. The equations of motion are developed and analyzed through perturbation techniques and numerical simulation. We use the method of multiple scales to obtain an approximate solution of these equations and investigate the vibration stability. There are two cases of fixed points. In the first case, the response amplitude is symmetric about the origin and divided into two branches with increasing magnitudes for decreasing and increasing the natural frequency omega and the coefficient of external excitation f respectively. In the second case, the response amplitudes are symmetric about the origin for variation of all parameters but the symmetry disappeared for increasing detuning parameter sigma.

In this paper, a general periodic vaccination has been applied to control the spread and transmission of an infectious disease with latency. A SEIRS-1 epidemic model with general periodic vaccination strategy is analyzed. We suppose that the contact rate has period T, and the vaccination function has period LT, where L is an integer. Also we apply this strategy in a model with seasonal variation in the contact rate. Both the vaccination strategy and the contact rate are general time-dependent periodic functions. The same SEIRS models have been examined for a mixed vaccination strategy composed of both the time-dependent periodic vaccination strategy and the convention alone. A key parameter of the paper is a conjectured value R-0(c) for the basic reproduction number. We prove that the disease-free solution(DFS) is globally asymptotically stable (GAS) when R-0(sup) < 1. If R-0(inf) > 1,then the DFS is unstable,and we prove that there exists a nontrivial periodic solution whose period is the same as that of the vaccination strategy. Some persistence results are also discussed. Necessary and sufficient conditions for the eradication or control of the disease are derived. Threshold conditions for these vaccination strategies to ensure that R-0(sup) < 1 and R-0(inf) > 1 are also investigated.

Fatty acids isothiocyanates 1 have been used as starting materials to synthesise some important heterocycles, such as triazoles, oxazoles, thiazoles, benzoxazoles and quinazolines by treating with different types of nucleophiles, namely, nitrogen nucleophiles, oxygen nucleophiles and sulphur nucleophiles. The produced compounds react with-propylene oxide in different moles (n = 3, 5 and 7) to yield novel groups of nonionic compounds having a double function like antimicrobial and surface active agents which can be used in the manufacture of drugs, cosmetics, pesticides or can be used as antibacterial and/or antifungal. The physical properties as surface and interfacial tension, cloud point, foaming height, wetting time, emulsification power and the critical micelle concentration (CMC) have been determined. Antimicrobial and biodegradability are also determined.

The problem of aggressive attack of sulphate and chloride ions has been of considerable scientific and technological interest because this attack is one of the factors responsible for damage to concrete. The corrosive action of chlorides is due to the formation of chloroaluminate hydrates, which causes softening of concrete. Sulphate ions can enter into chemical reactions with certain constituents of concrete, producing sulphoaluminate hydrates and gypsum, which cause the expansion of concrete. The aim of the present work is to study the hydration and the durability of mixed cement (sulphate-resisting and slag cement blends) pastes and mortars in Caron's Lake water. Different mixes of sulphate-resisting cement (SRC) with various proportions of slag cement were prepared and immersed in tap water for 3, 7, 28 and 90 days. The durability of the cement mortars was followed by curing the samples in tap water for 28 days (zero time) then immersed in Caron's Lake water for 1, 3, 6, 9 and 12 months. The hydration behavior was measured by the determination of the compressive strength, free lime, evaporable and nonevaporable water, total chloride and total sulphate contents at each curing time. The increase of substitution of SRC with blast-furnace slag cement (BFSC) up to 30 % increases slightly the total pore volume. The free lime contents decrease sharply in the first months of immersion then slightly up to 1 year. The blended cement pastes made of SRC with BFSC up to 30 mass% have lower values of total chloride and total sulphate, while the mortars containing only SRC have lower values of compressive strength than those of all blended cement mortars at all curing ages of immersion under Caron's Lake water. Useful conclusions and recommendations concerning the use of 70 mass% of SRC with 30 mass% slag cement produces a highly durable mixed cement. (c) 2004 Elsevier Ltd. All rights reserved.

In this paper, we find the explicit and numerical traveling wave solutions of Whitham-Broer-Kaup (for short WBK) equations, which contain blow-up solutions and periodic solutions, by using the decomposition method. By using this method, the solutions were calculated in the form of a convergent power series with easily computable components. The convergence of the method as applied to the Whitham-Broer-Kaup equations is illustrated numerically. (c) 2004 Elsevier Inc. All rights reserved.

Successful choice of the suitable catalyst composition for hydrogen/deuterium exchange reaction between hydrogen and water requires understanding of chemical kinetics as well as surface properties and activity in both liquid- and vapour phases. The present study deals with the thermodynamic and kinetic behaviour of a simple liquid phase reaction on the surface of nickel catalyst promoted with zirconium oxide used for the H/D exchange. This study helps understand the condensation of water on the catalyst surface during operation which leads to its poisoning. In this specific case water molecules are responsible for selective poisoning of this type of catalysts. The reaction rate constant, the increase in Gibb's free energy, the enthalpy, the entropy of activation and the energy of activation were calculated.

Epoxy fatty derivatives of both cis 9-octadecenoic and trans 2-octadecenoic acids produced from Crude Mangifera Oil have been prepared by in-situ technique utilizing hydrogen peroxide and acetic acid in the presence of strong acid catalyst. Excellent conversions to epoxide have been achieved with a series of prepared unsaturated fatty esters (70%), alcohols (44%), and hydrocarbons (58%). Epoxy fatty compounds are excellent plasticizers and stabilizers for polyvinyl chloride resins.

Consider X1,X2,...,X(n) be a sequence of independent identically distributed (i.i.d.) random variables having an unknown absolutely continuous distribution function F with problability density function f. The purpose of this paper is to obtain an asymptotic mean integrated square error (MISE) of the estimator [GRAPHICS] of an unknown d.f.F(x) when its p.d.f. f(x) be continuous everywhere or continuous excpt at a finite number of discontinuity points, and the asymptotically optimum value of h(j) which minimizes the suggested MISE of F(x).

Inhibition efficiency of some N-heterocyclic compounds on the HCl corrosion of Zn in 0.05 and 0.1 mol L-1 HCl solutions have been studied. Quinoline and some of its derivatives were tested at different concentrations and temperatures. The influence of various functional groups on corrosion inhibition was determined in accordance with their type and position in the N-heterocycles. The inhibitive efficiency was found to increase on increasing the inhibitor concentration and/or decreasing the temperature. The mechanism of inhibition action was discussed and correlated with the chemical structure of the inhibitors molecules.

The electrochemical behaviour of some azo compounds of 4-aminoantipyrine derivatives (I-V) have been studied in ethanolic buffered solutions using tast polarography (DC sampled mode), linear sweep and cyclic voltammograms. Generally, the reduction polarograms of these compounds show a single, 4-electrons diffusion controlled irreversible wave within the entire pH range (2-12), which represents the reduction process. The kinetic parameters of the electrode reaction are given.

Alkylation of beta-aroylacrylic acid (I) with 3, 5-dimethylpyrazole affords beta-aroyl-alpha-(3, 5-dimethylpyrazol-4-yl)-propionic acid (II). Reaction of (II) with hydrazine hydriate gives dihydropyridazinones (III). The reaction of (III) with ethyl bromoacetate and dimethylsulphate in different solvents has been studied. Chloropyridazine (VI) is obtained from the reaction of (III) with POCl3/PCl5. The behaviour of (VI) towards some nucleophiles has also been investigated. The reaction of (III) with bromine/acetic acid mixture, Grignard reagents are described. The acid (II) reacts with hydroxylamine to give dihydro-1, 2-oxazin-6(2H)-one (XII). The antimicrobial activity of some synthesized products has been investigated.

New Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Hg(II), Pd(II) and UO2(II) complexes of the Schiff base ligand (FBz) formed by condensation of fluorenone with S-benzyldithiocarbazate have been prepared and characterized by elemental analysis, magnetic and spectroscopic measurements. The Cu(FBz)2(Cl)2 complex is paramagnetic. The Ni(FBz-H)2 complex is diamagnetic, four-coordinate and square planar. The Co(II) ion is oxidized in the presence of the Schiff base with the concomitant formation of a Co(III) complex of empirical formulae Co(FBz)Cl3OH2. The ligand was tested as a corrosion inhibitor for copper. Inhibition efficiency was calculated and the limiting concentration of FBz to give maximum efficiency was 10(-3) mol dm-3 at 25-degrees-C. The polarographic reduction of FBz was investigated in Britton-Robinson buffer solutions of pH 3-10. The polarograms at dme indicated that the depolarizer is reduced through two two-electron irreversible diffusion-controlled waves. The mechanistic pathway of the electrode reaction is commensurate with this result.

The electrical conductivity of pure and Mn-doped MgAl2O4 spinel has been studied in nitrogen atmosphere as a function of temperature. The conduction process is explained by the motion of cation vacancies in each of gamma-irradiated and unirradiated samples. The effect of gamma-irradiation on the conductivity and activation energy has been discussed.

The kinetics of the neutral hydrolysis of ethylchloroformate have been studied in water-acetonitrile and in water- tetrahydrofuran mixtures in the temperature range of 30-50-degrees-C. The hydrolysis reaction follows a first-order rate law. The rates of the hydrolysis showed maxima at 0.9 and at 0.92 water mole fraction in water-acetonitrile and in water- tetrahydrofuran mixtures, respectively. The activation parameters DELTA-H# and DELTA-S# showed minima at nearly the same solvent composition range. The significance of these results from the viewpoint of the changing of solvent structure in such mixture is discussed.

The electrical properties (resistance, dielectric constant and pyroelectric current) as a function of temperature in the range 30-degrees-C < T < 120-degrees-C of anthranilic acid single crystals (o-aminobenzoic acid, C6H4NH2COOH), were accurately measured and correlated to the structural phase change that has been observed at 81-degrees-C. The activation energies of the two phases were determined. The recorded DTA thermogram supports this phase change. In addition, the mean molar susceptibility chi-M of the powdered sample was accurately determined in the same temperature range; the result indicates that the structural phase change takes place at 81-degrees-C.

An attempt is made to investigate the properties of nodal configurations and analyse many-body energies in Li3(3+), F3(3-), Li2(2+)F- and Li+F2(2-) ions at the lithium fluoride crystal geometries both in the short- and long-range regions of interactions. Cluster geometries in the short-range regions were also investigated and the effect of introducing diffuse and polarization functions to the 6-311G basis set was considered. For three ions of the same type, nodal configurations were detected at the apex angles 126.5-degrees and 135.0-degrees using the 6-311G basis and at the apex angles 127.0-degrees and 129.35-degrees using the 6-311 + + G** basis. For three ions of different types, the occurrence of nodal configurations depends on the basis set size used in the calculations. While at the 6-311G level no nodal configurations were detected for Li2(2+)F- and Li+F2(2-) ions, at the 6-311 + + G** level a nodal configuration was detected for Li2(2+)F- at 83.0-degrees. The conjecture of a symmetric compensation between the SCF regimes is discussed and correlated with reported results on rare-gas trimers.

1-(Dibenzothien-2-oyl)-1, 2-dihydrobenzo[f]coumarin (1) has been prepared by Pechmann condensation of beta-naphthol with beta-(dibenzothien-2-oyl)acrylic acid. The behaviour of the latter towards nitrogen nucleophiles, aldehydes under Knowevinagel condition, carbon electrophiles under Michael condition, bromination in different solvents and carbon nucleophiles under Grignard condition have been investigated. The Claisen reaction of 1 with diethyl oxalate and ethyl acetate, and Mannich reaction with different bases have also been studied.

Multibody expansion with zero point vibrational energy correction is combined with group theoretical analysis to examine the stability, structure and energetics of the title ions. The stability order based on the total interaction energy V(3) and the two-body contributions V(2,3) is Li2F+ > [Na2F+,Li2Cl+ > Na2Cl+ in agreement with previous experimental and theoretical predictions. The multibody terms have been analysed and zero point vibrational energy correction introduced for accurate description of these terms. Normal coordinate analysis has been carried out at the minimum energy configurations using the 6-311 + + G** basis set to calculate harmonic force constants, harmonic frequencies, IR intensities and Raman activities as well as frequency assignments.

A kinetic-theory treatment of the cylindrical Couette flow is considered. A generalization of the case of a surface with an arbitrary reflection coefficient that depends on the nature of the surface. In this paper we consider that the reflection coefficients of the inner and outer walls are different. A model kinetic equation of the BGK (Bhatnger-Gross-Krook) type is solved using the method of moments with a two-sided distribution function. The dependence of the velocity and shear stress on the reflection coefficient is obtained.

The composition and stability constants of La (III), Nd (III), Gd (III), UO2 (II) and Th (IV) complexes with hydroxamic acid derivatives have been determined by conductometric and potentiometric measurments. The proton reagent stability constants and stepwise formation constants were measured and the free energy changes were calculated for the ligands and their chelates. The chemical structure of the chelates were determined on the basis of conductometric measurments, elemental and thermal analyses.

Uranium is sorbed on tin(IV) antimonate ("SnSb") from aqueous nitrate solutions by a cation exchange mechanism. Kinetic and thermodynamic parameters have been evaluated under the conditions favouring a particle diffusion controlled mechanism. Sorption of uranium by SnSb has been also studied as a function of uranium concentration, pH, and temperature. The sorption of urnaium is found to be an endothermic process and increases markedly with temperature between 30 and 60-degrees-C. The results have been analysed by the Langmuir adsorption isotherm over the entire range of uranium concentrations. Results indicate that, in terms of heat of adsorption. SnSb seems to be a better sorbent for uranium than the hydrous oxides.

Ternary copolymerization reactions of N-acryloyloxyphthalimide (NAP) or N-methacryloyloxyphthalimide (NMP) and acrylonitrile with methyl acrylate or methyl methacrylate were carried out in solution at 60-degrees-C in the presence of a free radical initiator. Experimental terpolymerization data agree well with calculations based on the Alfrey-Goldfinger equation. The determination of unitary, binary, and ternary azeotropies of the various systems studied was easily handled by a computer program. The results show that there is no ternary azeotropic composition for any terpolymer system studied. Selective unitary and binary azeotropic compositions were polymerized and the results show good agreement between the theoretical and experimental terpolymer composition in each case. The estimation of terpolymer compositions was carried out by H-1 NMR spectroscopy.

Ternary copolymerizations of tri-n-butyltin 4-acryloyloxybenzoate (ABTB) with acrylonitrile (AN) and alkyl acrylates [methyl (MA), ethyl (EA) or butyl acrylate (BA)], methyl methacrylate (MMA) or styrene (ST) were carried out in solution at 70-degrees-C in the presence of free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey-Goldfinger equation. The determination of unitary, binary and ternary azeotropies of various systems studied was easily handled by a computer program. The results obtained show that there is no ternary azeotropic composition for any terpolymer system studied. Selective unitary and binary azeotropic compositions were polymerized and the results obtained show good agreement between the theoretical and experimental terpolymer composition for each case.

THREE REDUCING sugars-glucose, fructose, and maltose-were tested as inhibitors of carbon-steel corrosion in alkaline solution. Their inhibition efficiencies were measured using weight-loss and potentiostatic polarization, and it was found that the. addition of any of the three reduced the corrosion rate of the steel. The inhibition efficiency decreased according in the order glucose > fructose > maltose. The adsorption of glucose molecules on the steel surface followed the Langmuir adsorption isotherm, whereas the adsorption of fructose and maltose do not. It was also found that the three sugars acted as anodic inhibitors, where their oxidation reactions interfered with the anodic corrosion reaction of the steel The inhibitive effects of the tested sugars are discussed in view of their relative reducing-power. UV-visible spectra were recorded for the test solutions after the completion of the weight-loss experiments, and the spectra suggested a formation of metal-sugar complexes.

In this paper, we introduce a new inversion free variant of the basic fixed point iteration method for obtaining a maximal positive definite solution of the nonlinear matrix equation X + A*X-1 A = Q. It is more accurate than Zhan's algorithm (J. Sci. Comput. 17 (1996) 1167) and has less number of operations than the algorithm of Guo and Lancaster (Math. Comput. 68 (1999) 1589). We derive convergence conditions of the iteration and existence conditions of a solution to the problem. Finally, we give some numerical results to illustrate the behavior of the considered algorithm. (c) 2004 Elsevier B.V. All rights reserved.

The oxidation states of mercury in FA: Hg+ and FA: Hg++ color centers at the low coordination (100) and (110) surfaces of AgBr play important roles in laser light generation and color image formation. Two simultaneous potentials at these surfaces were investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the F-A(-) defect site were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the oxidation state of mercury, the coordination number of the surface ion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity and optical-optical conversion efficiency. All relaxed excited states of the defect-containing surfaces were deep below the lower edges of the conduction bands of the ground state defect-free surfaces, suggesting that the FA: Hg+ and FA: Hg++ centers are suitable laser defects. The dependence of the orientational destruction, recording sensitivity and exciton (energy) transfer on the oxidation state of mercury and the coordination number of the surface ion on is clarified. The Glasner-Tompkins empirical rule is generalized to include the oxidation state of the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The Hg++ surfaces of AgBr are significantly more sensitive than the corresponding surfaces. On the basis of quasi Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states is determined.

The applicability and synthetic potency of the novel reagent 1-hydrazinophthalazine 1 to develop an expeditious convenient synthetic route via the annelation reactions with appropriate reagents for polyfunctionally substituted triazoles, Pyrazoles, tetrazoles, and polycyclic condensed systems are reported. Chemical and spectroscopic study for the structures of the newly synthesized compounds are investigated. The prepared compounds were tested in vitro for their antimicrobial activity.

This paper presents the influence of some superplasticizers namely, naphthalene sulphonate formaldehyde (NSF), melamine sulphonate formaldehyde (MSF) and polycarboxylate (PC) on the physical and microstructural characteristics of ordinary Portland cement (OPC) containing 10 and 30 mass% silica fume (SF). It was found that the addition of superplasticizers improves the plastic and hardening properties of the silica fume-blended cement pastes leading to higher values of compressive strength. Also, the results indicate that the higher compressive strength values of the superplasticized blended cement pastes are mainly due to the relatively higher values of gel/space ratio than those of the neat OPC cement pastes. With the increase of SF content in the pastes, the Ca(OH)(2) content diminished or is fully consumed and transformed into C-S-H. The occurrence of C-S-H in large quantity is responsible for bridging cement particles and producing a rigid system with a more dense and impermeable matrix, leading to a decrease of the specific surface area of cement pastes cured up to 360 days; this could be attributed to the continuous filling up of a part of the available pore volume by the hydration products.

Rice hulls were treated using several sodium hydroxide concentrations and temperatures. The black liquor contents of silica, lignin and hemicelluloses increased with increase in temperature or sodium hydroxide concentration. Hexoses constituted the major part and pentoses the minor part of the black liquor hemicelluloses. The ratio of pentoses to hexoses increased slightly with the increase of treatment variables. The pentose content of the black liquor consisted of arabinose and xylose, while the hexose composition was mannose, galactose, rhamnose and glucose. On increasing the alkali concentration, the xylose and mannose concentrations increased greatly, while galactose and glucose increased only slightly. Using 10 soil samples several isolates of fungi and actinomycetes were obtained. These were identified as five species of the genus Aspergillus, three species of Paecilomyces, two species of Penicillium, one species each of Alternaria, Trichoderma, Chaetomium and Actinopolyspora. These fungi were cultivated on black liquor basal salts medium. The highest bioconversion rate of black liquor hemicelluloses into biomass and single-cell proteins was achieved by Aspergillus terreus, followed by Paecilomyces simplicissima then Actinopolyspora sp.

A spectrophotometric method for the determination of some alkaloids (namely ephedrine HCl, cinchonine HCl. chlorpheniramine maleate. atropine sulphate and diphenhydramine HCl) as separate compounds as well as in pharmaceutical preparations through the formation of their ion-pair (reineckate complexes) is described. These complexes were prepared and the final products were extracted with nitrobenzene in situ. The optimum conditions for complete extraction were evaluated by investigating the nature of solvent, pH, time of shaking, temperature and reineckate concentrations. The absorption spectra of the extracted organic layer were measured at 520 nm. The extraction constants were calculated and found to have a mean of log K(E) congruent-to 2. The application of the present method was compared with the accepted pharmacopoeia method and the effects of some interfering ions were also studied.

9-(p-Anisyl)-6a, 7, 8, 9-tetrahydro-6-oxo-6H-benzo[d]naphtho[1,2-b]pyran-7, 8-dicarboxylic acid (3) has been prepared by cycloaddition of 4-(p-methoxystyryl)-2H-naphthol[1, 2-b]pyran-2-one (2) with maleic anhydride. The reactions of 3 with amines, phosphorous pentachloride, Grignard reagents and aromatic hydrocarbons have been investigated.

Alkyl N-(aminoethylene)-beta-aspartamates of the general formula, H2NCH2CH2NHCH(COOH) CH2CONHR, were prepared by nucleophilic addition of ethylene diamine to the double bond of N-alkylmaleamic acid with triethyl amine as catalyst. The structure of the addition products was verified by IR and NMR spectroscopy. The products showed good surface active properties and proved to be good corrosion inhibitors for steel in acidic solution.

2-Hydroxy myristic, palmitic and stearic acids were prepared. These acids were converted to methyl esters and then reduced with LiAlH4 to the corresponding alkane-1,2-diols. The hydroxy acids were reacted with monoethanolamine and diethanolamine to the corresponding fatty alkanolamides. A series of sulphation products at the hydroxyl groups of 2-hydroxy acids (RCH(OSO3Na)COONa), esters (RCH(OSO3Na)COOCH3), and alkanolamides (RCH(OSO3Na)CONHCH2CH2OSO3Na), (RCH(OSO3Na)CON(CH2CH2OSO3Na)2, (R = 12,14,16 carbon atoms) were prepared. Also the alkane 1,2-diols were sulphated, (RCH(OSO3Na)CH2OSO3Na). The surface active properties of these compounds were evaluated.

The effects of the basis-set size on many-body energy expansion in Li(n)n+F- clusters are investigated and correlated with previously reported values on Li(n)n+Cl- analogs. Coulomb and non-Coulomb energies in Li(n)n+F- at different configurations are also examined. Although at the minimal STO-3G basis V(na)(3, 4) and V(na)(4, 4) nonadditivity terms were the smallest in the D3h configuration, they were the largest at the extended 6-311 + +G basis. V(m, n) terms where m = n greater-than-or-equal-to 3 were found to be playing a small role in the chemistry and physics of Li(n)n+F- clusters compared with V(3, n) terms in Li(n)n+Cl- clusters.

A new series of symmetric bis-Schiff bases derived from 1,2-diaminoethane with bis-salicylaldehyde (H2L1) and/or bis-o-hydroxyacetophenone (H2L2) have been prepared. The metal(II) complexes of these ligands were isolated and characterized by elemental analyses, magnetic moments and spectral (visible, i.r.) measurements. I.r. spectra show that the ligands behave as dianionic or neutral tetradentate. Replacing the imine C-H with a bulky methyl group leads to a steric interaction with the methylene protons of the chelate ring. The (NiL2) is diamagnetic four coordinate square planer. The electronic spectrum shows that [Cu2(H2L1)Cl4(OH2)4] complex is tetragonally distorted octahedral. The polarographic reduction of Schiff bases was investigated in Britton-Robinson buffer solutions at pH 3-12. The polarograms at dme indicated that depolarizers, (H2L1 & H2L2) are reduced through 8-electron irreversible diffusion-controlled wave. The mechanistic pathway of the electrode reaction is discussed.

Based on some electrical properties (resistivity, dielectric constant and pyroelectric current) measured between 40 and 300-degrees-C, combined with the DTA thermogram in the same temperature range, we observed two structural phase transitions in ammonium purpurate (APP) "murexide" C8H4O6H5.NH4 at temperatures of about 100 and 257-degrees-C. The data are correlated to the reorientation and distortion of the NH4 ions, which are closely related to the different possibilities of the N-H...X hydrogen bonding scheme.

The electrical conductivity of gamma-irradiated and unirradiated complexes of (CH2)8(NH3)2Co1-xZnxCl4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) was measured in the temperature range from 300 K to a temperature near the melting points of the samples. The results showed an increase in the conductivity values with increasing concentration of zinc ions in the samples. Both differential scanning calorimeter (DSC) and conductivity measurements showed the presence of many phase transitions in each of the complexes investigated. The results of irradiated compounds with a composition of 0 less-than-or-equal-to x less-than-or-equal-to 0.8 showed an increase in the conductivity values, at lower temperatures, compared with the values of unirradiated ones. For composition x = 1 no change in the conductivity data has been observed after irradiation. The effect of change in the chemical composition and irradiation on the conductivity data are discussed.

The object of the present paper is to investigate the influence of initial stress on the waves propagation in a generalized thermoelastic granular medium subjected to the boundary conditions that the outer surface is traction free. In addition, it is subjected to temperature boundary conditions. The wave velocity equation for the generalized thermoelastic granular medium Rayleigh wave under the influence of initial stress has been obtained. The classical result has been derived as a limiting case similar to one which was obtained by Ewing et al. (1957).

Ternary copolymerization of tri-n-butyltin acrylate (TBTA) or methylacrylate (TBTMA) with itaconic acid (IA) or dimethyl itaconate (DMI) and acrylonitrile (AN) were carried out in solution at 70-degrees-C in the presence of a free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey-Goldfinger equation. Ternary azeotropic compositions for TBTA-IA-AN, TBTMA-IA-AN, and TBTMA-DMI-AN systems were 39.0:26.1:34.9, 51.7:10.5:37.8, and 00.3:66.3:33.4 mol %, respectively. Also, "pseudo-azeotropic" regions were identified where the deviation between feed and polymer compositions is very small.

Ground and excited state properties of many body energies in Li(n)n+ F- ions were examined at two levels of ab initio theory. The effect of basis set size at configurations specified by two angular variables was tested. The ions in the excited state lattice were found to be more bound than those in the ground state. Discrepancies were observed between the minimal and extended basis set for describing the multibody expansions. Although the ground state V(m, n) terms at m = n greater-than-or-equal-to 3 were negligible, the excited state V(m, n) terms at m = n greater-than-or-equal-to 3 were not negligible.

p-Acryloyloxybenzoic acid (ABA) and N-methacryloyloxytetrabromophthalimide (NMTP) were prepared. The monomer reactivity ratios for the copolymerization of tri-n-butyltin acrylate (monomer-1) with ABA and NMTP have been found to be r1 = 1.01, r2 = 0.40 and r1 = 0.69, r2= 0.90 respectively; those for tri-n-butyltin methacrylate (monomer- 1) with ABA and NMTP were r1 = 2.21, r2 = 0.87 and r1 = 0.85, r2 = 1.35 respectively. Copolymerizations were carried out in solution at 70-degrees using 1 mol% azobisisobutyronitrile as initiator. The structures of the monomers were investigated by i.r. and H-1-NMR.

The kinetics of the thermal decomposition of manganese(II) acetate tetrahydrate were studied using isothermal and dynamic thermogravimetric techniques. The dehydration of the tetrahydrate proceeds via a two-stage reaction, each stage involving loss of two water molecules, while the thermal decomposition of the anhydrous salt proceeds in one step to MnO. Kinetic analysis of isothermal data of the three decomposition reactions, when compared with the various solid state reaction models, showed that the reactions are best described by the phase boundary and random nucleation models. Kinetic analysis of the dynamic TG curves were discussed with reference to a composite integral method, in comparison with the integral methods due to Coats and Redfern and to Ozawa. The activation parameters were calculated and the results of the isothermal and dynamic integral methods were compared and discussed.

The thermal decomposition of gamma-irradiated and unirradiated complexes of mandel-hydroxamic acid (HMA), Co(HMA)2 . 1/2H2O, Mn(HMA)2 . 2H2O, Ba(HMA)2 . 2H2O and Cd(HMA)2 . 2H2O have been studied thermogravimetrically (under isothermal conditions). The thermal dehydration of each complex occurred in one step, while the decomposition of dehydrated complexes occurred in two steps. The kinetic parameters for dehydration were computed by different models. The thermal dehydration is regulated by random nucleation A3 for Co-, Mn-, and Cd-complexes and by phase-boundary (R3) for Ba-complex. The effect of gamma-irradiation on the kinetic parameters of thermal decomposition is discussed. Radiation did not modify the mechanism of the reaction but accelarated the dehydration steps in the case of Mn- and Co-complexes.

A series of trivalent lanthanide chelates of the type [Ln(PHNSA) (H2O)n] (2 Cl) (where Ln3+ = Pr, Nd, Sm, Eu, Gd, Dy, Er, Yb or Lu; PHNSA = 2-(X)-phenylazo-2-hydroxynaphthalene-6-sulphonic acid; X = H, Cl, OCH3, CH3 and SO3H) have been synthesized and characterized by elemental and thermal analysis, molar conductance, IR, H-1 NMR (for diamagnetic complexes), electronic spectra and magnetic susceptibility measurements. IR data along with those of the H-1 NMR unequivocally proved that the coordination of the ligands to the metal ions took place in a bidentate fashion through the oxygen of the hydroxyl group and the nitrogen of the azo group. The mapetic moment values showed little deviation from Van Vleck values.

High silica mordenite samples (Si/Al molar ratios 38 and 60) were synthesized hydrothermally at 433 K with the template route method using o-phenylenediamine and characterized with several techniques including XRD, FT-IR, TG/DTA, pyridine-FTIR and N-2 adsorption. The effects of Na2O/SiO2 ratio, Si/Al ratio, temperature, crystallization time and various templates on mordenite crystallization as well as crystallite size that was smaller than 50 nm, irrespective of varying the parameters were thoroughly investigated. The effect of alkali cations such as Na+ and K+ on mordenite crystallization and on thermal stability of the produced mordenite was also investigated. Pyridine adsorption suggests an increase in Lewis acid sites particularly following hydrothermal treatment at 120 degrees C where at 160 degrees C both Lewis and Bronsted acid sites in addition to oxidation products, which are indicative of the existence of dual acid-base sites, were exposed. Surface texturing of the produced samples were correlated with their thermal analyses data. (c) 2005 Published by Elsevier Inc.

Stoichiometric SnS films were prepared, using the thermal evaporation technique, on clean glass substrates. According to x-ray investigations, the as-deposited films were in a partially crystalline state. The dielectric properties of the samples have been studied in the temperature range of 300-573 K and at different fixed frequencies (1, 10; and 100 kHz). The temperature dependence of epsilon', epsilon", tan delta, sigma(ac) and sigma(dc) has been found, and a dielectric dispersion and Debye relaxation phenomena were noted. The activation energies, due to do conductivity, ac conductivity and relaxation processes at different thicknesses, have been deduced. Thermodynamic parameters such as the free energy of activation Delta F, the enthalpy Delta H, and the change in entropy Delta S have been calculated. The results are discussed in terms of Debye relaxation, dispersion processes, and the defect states.

Ruthenium-106 and Cs-137 have been separated from thermal-neutron irradiated UO3 targets aged for similar to 2.5 years by distillation and surface interactions in nitrate media of controlled chemical composition. After digestion of the aged targets with their aluminum wrapper in 2M NaOH solution, nitric acid was added to complete dissolution of the formed residue. The prepared fission product solution was separated from 1291 and 91.8% Ru-106 by sequential distillation from 20% and 40% HNO3 solutions containing H2O2 and KMnO4, as oxidants, and by boiling for 4 and 2.5 hours, respectively. The recovery yield of Ru-106 collected in 0.1 M NaOH solution was similar to 68.2% with a radionuclidic purity of >= 99.99%. Thereafter, the fission product solution was brought to pH 9.5 by addition of NaOH solution to precipitate AI(OH)(3), MnO2, and Na2U2O7 which selectively retained the remaining fission products leaving, mainly, Cs-137 in the supernatant solution. The recovery yield of Cs-137 was >= 97.3% with similar to 99.75% radionuclidic purity. The gamma-ray emitter contaminants which could be detected and identified in the recovered Cs-137 solution, were similar to 0.25% Cs-134 and similar to 1.4- 10(-3)% (152,155) Eu.

In this paper a notion of L-topological group, introduced by Ahsanullah in 1984, is studied. Some basic properties related to these L-topological groups are proved. In 1992 Kubiak had generalized the functors omega and (1), defined by Lowen in 1976, for any complete lattice L to the functors omega L and L-1. We show here that for this notion of L-topological group omega L and L-1 are functors. Moreover, to justify this notion of L-topological group, we show in this paper that all initial and final lifts exist uniquely in the concrete category L-TopGrp of L-topological groups and hence all initial and final L-topological groups exist and can be characterized. As consequences the L-topological subgroups, L-topological product groups, and L-topological quotient groups are exist. Some examples of L-topological groups are given. (c) 2005 Elsevier B.V. All rights reserved.

The F-A1:Cs+ and F-A2:Li+ color centers at the flat, edge and corner surfaces of AgBr play important roles in laser light generation and color image formation. These two applications are investigated simultaneously by using quantum mechanical ab initio methods. As far as laser light generation is concerned, the calculated Stokes shifts suggest that laser activity is sensitive to the simultaneous effects of the vibrational coupling mode, the impurity cation, the coordination number of the surface ion, and the choice of the basis set centered on the anion vacancy. The FA(1):Cs+ and F-A2:Li+ color centers are suitable laser defects. The dependence of orientational destruction, recording sensitivity and exciton (energy) transfer on the impurity cation and the coordination number of the surface ion is clarified. The Glasner-Tompkins empirical rule is generalized to include the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states. Color image formation was found to be sensitive to the coordination number of the surface ion and the type of the impurity cation. On the basis of quasi Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states was determined. (c) 2005 Elsevier B.V.

We determine the response of bowed structural elements to a two-frequency, transverse load. The effects of both initial curvature (i.e., quadratic nonlinearities) and mid-surface stretching (i.e.. cubic nonlinearities) are included. We investigate possible large-amplitude-low-frequency responses to excitations of such structural elements (drumming) and determine the conditions under which the one-half subharmonics of the transverse load can be excited individually in the presence of three-to-one intemal resonance. The method of multiple time scales is used to determine four first-order nonlinear ordinary differential equations that govem the time variation of the amplitudes and phases of the interacting modes. The fixed points of these equations are obtained and their stability is determined. Numerical solutions are. carried out and graphical representations of the results are presented. The region of multivalued disappear for increasing the parameters mu(22), d(6), Gamma(2) and decreasing the parameters d(2), d(4), d(5) and omega(1). The nontrivial solution has unstable solution for increasing the damping factors. The trivial solution has unstable and stable solutions for decreasing the parameters Gamma(1) and Gamma(2) respectively.

beta-(4-Chlorobenzoyl)acrylic acid (1) proved to be a convenient precursor for the synthesis of a variety of heterocyclic systems through the reaction with compounds containing active methylene groups under Michael reaction conditions. Also, the reactivity of Michael adduct towards nitrogen nucleophiles was investigated to afford diazepine, indazole, isoxazole and quinazoline derivatives. Some of the synthesized compounds were screened for their biological activity.

Barium-137m radioisotope generator of the chromatographic column elution mode based on loading 1.5 g 6-tungstocerate(IV) gel matrix with similar to 54 kBq of fission-produced Cs-137 is described. The elution performance of the generated Ba-137m radionuclide was investigated as a function of chemical composition of the eluent, flow rate, elution frequency, and age of the generator system. At comparable conditions, Ba-137m eluates with 0.9% NaCl-0.1M HCl eluent had higher elution yields and radionuclidic purity than with 0.1M NH4Cl-0.1M HCl eluent. The generator has been repeatedly eluted for 311 days by passing 4810 ml of the saline eluent (10 ml x 481 elution operations) at a flow rate of 3.0 ml/min. Barium-137m eluates of high and reproducible elution yields, chemical and radionuclidic purities of (>= 99.99%) were obtained.

A new explicit expression of the higher order pseudospectral differentiation matrices is presented by using an explicit formula for higher derivatives of Chebyshev polynomials. The roundoff errors incurred during computing differentiation matrices are investigated. The advantages of the suggested differentiation matrices emerged through comparisons with other ones. (c) 2004 IMACS. Published by Elsevier B.V.

In this study, a kind of explicit exact and numerical solutions to the Lienard equation is obtained, and the applications of the results to this equation has been compared with their known theoretical solution. This paper is particularly concerned with the Adomian decomposition method and the numerical results demonstrate that the new method is relatively accurate and easily implemented. (c) 2005 Elsevier Inc.

Fe/ZSM-5 samples (5 wt.% Fe) prepared by in situ incorporation using TPABr template under hydrothermal conditions (Fe-ZSM-5(in)), chemical liquid deposition (Fe-ZSM-5(imp)) and solid-solid (Fe-ZSM-5(ss)) interaction were characterized by N-2 physisorption, TG/DSC, X-ray diffraction, FTIR spectroscopy, UV-Vis diffuse reflectance spectroscopy and Fe-57 Mossbauer spectroscopy techniques. Calcination at 550 degrees C leads to almost complete removal of template that was associated with dislodgment of significant fraction of Fe to external positions as recognized for the in situ prepared sample (Fe-ZSM-5in). This sample showed an increase in lattice volume suggesting the presence of the majority of Fe ions in tetrahedral positions inside zeolite channels and offered as well the lowest crystallites size (75 nm) and maximum S-BET (453 m(2)/g) between all samples. On the other hand, Fe-ZSM-5(ssbef), resulting from solid-solid interaction and subjected to heat treatment in vacuum at 200 degrees C, measured the lowest mean pore radius (r(-); 23 angstrom), and pore volume (V-p; 0.3887 cm(3)/g), giving a hint about the probability of finding neutral iron oxide nanoparticles (alpha-Fe2O3) as a separate phase that has been validated by Mossbauer (IS = 0.3 mm/s, QS = -0.2 mm/s, H-eff = 520 kOe) and UV-Vis (400 nm) investigations. This sample also demonstrated that the majority of Fe occupied framework positions beside a fraction identified as small oligonuclear oxo-iron ions (Fe-x(3+)-O; 290 nm). Interestingly, Fe-ZSM-5(ssaft), resulting from solid-solid interaction and subjected to air calcination at 550 degrees C, measured maximum V-p (0.6380 cm(3)/g) and r(-)(39 angstrom) values, reflecting the enforced location of Fe in this sample leading to an effective pore widening and thus a pronounced mesoporosity is attained. IR bands due to v(as)T-O in ZSM-5 (1105 cm(-1)) showed a shift to lower wave numbers (1059 cm(-1)) following Fe incorporation reflecting the extent of exchanging Fe in this sample (Fe-ZSM-5s,aft), unlike the rest of the samples which showed splitting, which accounted for the presence of residual Al3+ beside Fe3+ ions in the same site. Mossbauer data of this sample confirmed the latter result and indicated the maximum lattice imperfection and showed as well the lowest degree of crystallinity. The Fe-ZSM-5(impaft) sample, subjected to heat treatment at 550 'C, showed alpha-Fe2O3 species where that heated at 110 degrees C presented the lowest SBET (361 m(2)/g). More correlations were evaluated and discussed on the effect of thermal treatment on the existence of various Fe species (either framework or non-framework), their electronic states and local structures. (c) 2005 Published by Elsevier Inc.

Total stability for systems of ordinary differential equations, functional differential equations, and difference equations was introuced. In this paper, we will extend this notion to the so-called total phi(0)-stability for systems of difference equations. given some new criteria and results. Our technique depends on cone-valued Liapunov's function method.

The response to multifrequency excitation of a three-degree-of-freedom self-excited system is analyzed by using multiple scales. Five cases of resonance are considered: Harmonic, subharmonic, superhamonic, simultaneous sub/superharmonic, and combination resonances. The steady-state amplitudes for each case are plotted, showing the influences of the several parameters. Approximate solutions are found and stability analyses are carried out for each case.

Saturated copolyester were prepared by copolyesterification of bis-1,4-(dicarboxymethoxy) benzene and phthalic anhydride with diethylene glycol, triethylene glycol, tetraethylene glycol 1,4-butane diol, 1,2-propane diol, and 1,6-hexamethylene glycol. Also, unsaturated copolyesters were prepared by copolyesterification of bis-1,4-(dicarboxymethoxy) benzene and maleic anhydride with the same glycols. All the copolyester resins obtained have been characterized and unsaturated copolyesters in the form of films were determined. IR and H-1-NMR spectroscopy were used for both qualitative and quantitative analysis of the copolyesters resins and their hydrolyzate products, after curing with styrene.

Binary and ternary copolymerizations of di-(tri-n-butyltin) itaconate (TBTI) with methyl acrylate, methyl methacrylate (MMA), styrene (ST) and N-vinyl-2-pyrrolidinone (NVP) were carried out in solution at 60-degrees in the presence of a free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey-Goldfinger equation. Determination of unitary, binary and ternary azeotropies of the various systems studied was easily handled by a computer. Ternary azeotropic compositions for TBTI-MMA-NVP and TBTI-ST-NVP systems were 13:69:18 and 26:60:14 mol% respectively.

Moller-Plesset fourth order perturbations and group theoretical formalism for C2v and D3h forms of ozone are considered. It is concluded that the C2v and D3h forms are isomers corresponding to two different local minima at the potential energy surface with an energy gap of 11.4 kJ mol-1 at the level of the Hartree-Fock 6-311 + + G(3df,3pd) basis set employed in this study. The need for the perturbation level of theory and the drawbacks of the minimal STO-3G basis set in describing the C2v and Dh intermolecular interactions are also considered.

A kinetic study of the dehydration and decomposition of gamma-irradiated and unirradiated Na2[Co(C4H4O4)2].7H2O has been studied using isothermal and dynamic thermogravimetric methods. The thermal dehydration occurs in one step regulated by a random nucleation model (A3), while the decomposition of anhydrous salt is controlled by a phase boundary controlled model (R3). The kinetic parameters obtained at three heating rates are in good agreement; however, the values of the kinetic parameters estimated isothermally are slightly different from those estimated dynamically. Irradiation enhanced both the dehydration and the decomposition reactions but did not modify their mechanisms. The activation energy decreases as the irradiation dose increases.

Samples of CuO-Fe2O3, CuO-Cr2O3 and CuS-Cr2S3 were characterised by chemical, ir and X-ray diffraction analysis. Electrical conductivity measurements were carried out in the temperature range, room temperature to 350-degrees. CuO-Fe3O3 system was found to be n-type semiconductor, CuO-Cr2O3 system p-type semiconductor while CuS-Cr2S3 system is a metallic conductor. The Insigma vs 1/T plots were single straight lines whereas CuO-Fe2O3 system gave a break at about 200-degrees (T(b)) that could be due to a change in the semiconducting nature of the solid. The activation energies for electrical conductivity were calculated according to the linear regression analysis. On increasing the calcination temperature for the oxide systems, the rate constant for catalytic decomposition of H2O3 decreased while for the sulphide system it increased. The activation energies were calculated.

The electronic absorption spectra of 3-(($) over bar 3 N-arylidenehydrazino-($) over bar 1,($) over bar 2,($) over bar 4-triazol-5-yl) coumarin III are investigated in organic solvents of varying polarities and buffer solutions of different PH. The behaviour of the latter is utilized in calculating pka values of these compounds. The important bands in the IR spectra and the main H-1 NMR signals are assigned and discussed in relation to molecular structure. The antimicrobial activity of these compound has been investigated.

Ternary copolymerisations of tri-n-butyltin acrylate (TBTA) or tri-n-butyltin methacrylate (TBTMA) with itaconic acid (IA) or dimethylitaconate (DMI) and N-vinyl-2-pyrrolidone (NVP) were carried out in solution at 70-degrees-C in the presence of a free radical initiator. Experimental terpolymerisation data agreed with calculations based on the Alfrey-Goldfinger equation. Ternary azeotropic compositions for TBTA-IA-NVP and TBTA-DMI-NVP systems were 52.60:14.80:32.60 and 56.60:26.60:16.80 mol%, respectively. Also 'pseudo-azeotropic' regions were identified where the deviation between feed and polymer compositions is very small.

A spectrophotometric procedure for the determination of ampicillin (Amp.) in pure solutions and in its pharmaceutical preparations has been developed. This new method offers advantages of simplicity, rapidity and stability in comparison with the official BP (1980) method. The proposed method is based on the formation of a colour condensation product through the reaction of ampicillin and nitrobenzene derivatives in an alkaline aqueous-acetone medium 40% (v/v). Beer's law is obeyed in the range 0.5-28 mug ml-1. The colours were produced within 20 min. after heating at 60+/-5-degrees-C and stable for at least 6 h. The method is relatively accurate (recovery 100+/-2%) and precise (RSD 1.9%) and can be used successfully for the preparation of capsules, syrup and ampoules.

A spectrophotometric method for the determination of amoxycillin trihydrate and flucloxacillin monohydrate alone or in mixtures and pharmaceutical preparations is described using 3,5-dinitrobenzoic acid. The procedure does not require any separation step. The calibration curves are linear up to 1-24 mug/ml of amoxycillin trihydrate at room temperature and up to 1-30 mug/ml of flucloxacillin monohydrate at 60 +/- 2-degrees-C after heating time 30 min. The method is relatively accurate (with error less-than-or-equal-to 2%), precise (R.S.D. less-than-or-equal-to 1.6%) and is applied successfully for synthetic mixture and pharmaceutical preparations (vails, capsules and syrup) containing each or both of them.

Thermal decomposition of pure and mixed copper and manganese carbonate 1.0:0.25, 1.0;0.50 and 1.0:1.0 with respect to CuO:MnO2 was studied. The products at different temperatures were character by X-ray diffraction analysis. The catalytic activity of the thermal products of pure and Mixed oxides was tested in H2O2 decomposition. Thermal treatment of copper carbonate produced CuO at temperature as low as 200-degrees-C, the increase of temperature of treatment increased the degree of crystallinity of CuO. Manganese carbonate starts to decompose at temperature higher than 300-degrees-C yielding MnO2 whereas at 500-degrees-C a mixture of cubic and tetragonal Mn2O3 was detected. At temperature higher than 500-degrees-C, the major crystalline form of Mn2O3 was cubic. On the other hand, Cu-Mn-mixed carbonates produced only MnCO3 crystalline form at low temperatures. At 500-degrees-C CuO and other compounds such as Mn2O3 or CuMn2O4 were detected depending on the composition of mixtures. The increase of temperature of treatment was found to be accompanied by an increase in the degree of crystallinity of CuMn2O4. The catalytic activity of these solids in hydrogen peroxide decomposition was found to increase as the activation temperature was increased passing through a maximum when the catalysts preheated at 500-degrees-C. The increase of calcination temperature higher than 500-degrees-C was accompanied by a marked decrease in the activity in H2O2 decomposition. This may be attributed to sintering and/or formation of inactive form of CuMn2O4.

Carmoisine (chromotrope FB, C.I. 14720, acid red 14) has been used for the determination of diphenhydramine.

Calculations on clusters of Li and F ions at LiF crystal geometries were carried out in relation to the solids. Schottky-Wagner defects in bulk and surface fragments, both in the ground and excited states, were considered. Counterpoise correction of BSSE was also investigated. It is found that bulk and surface defects minimize cation-anion attraction and maximize cation-cation and anion-anion repulsions. Based on the total interaction energies, the excited state fragments were found to be more bound than the ground state fragments. Unexpectedly, neglect of BSSE correction underestimated the total interaction energies. On the surface, cationic vacancies enhance the adsorption of anions and anionic vacancies enhance the adsorption of cations.

A search for nodal structures in the C2v and D3h isomers of ozone was carried out at the Hartree-Fock 6-311++G(d,p) and electron correlation MP4SDTQ 6-311++G(d,P) levels of ab initio theory. For the D3h configuration the equilateral side was scaled and for the C2v configuration the equal sides of the isosceles triangle were fixed and the apex angle was varied. The search was facilitated by means of a computer program that can allow the assignment of the nodal structures up to a reasonable accuracy. At the Hartree-Fock level, nodal structures were detected at the nodal parameters R = 1.541 angstrom and phi = 104.219-degrees for the D3h and C2v configurations respectively. At the electron correlation level no nodal structures were detected. At each point on the potential energy surfaces, the multibody expansion was analyzed and its convergence was tested.

Treatment of clay loam soil with carbaryl (sevin), thiodicarb (larvin) and methomyl (lannate) at field and 10 folds the recommended doses showed a variable effect on population of total bacteria, azotobacters and nitrifying bacteria, in addition to the soil content of total soluble salts; the effect differed according to the herbicide and the dose level. The bacterial population was significantly increased in the first five days of treatment, then a decrease was recorded. The increase in the microbial population and total soluble salts were proportion to the levels of the insecticides. Moreover, supplementation of glucose to the soil caused substantial increase over that in the insecticide and/or glucose free soils.

The electronic absorption spectra of some hydroxamic acid oxime derivatives and Schiff's base derivatives in polar (ethanol) and nonpolar (CCl4) solvents, as well as in some other organic solvents of different polarities, were investigated; the variation of absorbance with pH was utilized for the determination of pK(a) and DELTAG* values. The important bands in the IR spectra as well as the main signals of the NMR spectra are also discussed in relation to the molecular structure.

An attempt is made to test the transferability of specific physical meanings from Fourier analysis of rotational potential function to the multibody expansion of Li2F2 ions at certain crystal and cluster geometries generated by rotation about a common axis.

Two notions of fuzzy syntopogeny have been introduced for the framework FNS of fuzzy neighbourhood spaces: one by Katsaras and the other by Mashhour, Morsi and El-Tantawy. We identify a property that holds in all the special types of interest from Katsaras' fuzzy topogenous orders, and we call it structure A. We show that the Katsaras' fuzzy topogenous orders of structure A are completely determined by their behaviour on ordinary subsets. We then establish natural bijections between them and the saturated N. topogenous orders of Mashhour et al. Those bijections are related to Flushoh's ideas on fuzzy filters.

The results of the multiplicity distributions of shower, grey, black, and heavily ionizing charged particles from O-16-induced reactions at 200A GeV are presented. The results are compared with the predictions of the Lund Monte Carlo code FRITIOF, the multichain model by Ranft, and the Monte Carlo code VENUS.

Radical copolymerizations of p-acryloyloxy-tri-n-butyltin benzoate (ABTB) with allyl methacrylate, N-vinyl pyrrolidone and vinyl acetate were carried out in solution at 70-degrees using 1 mol% azobisisobutyronitrile as initiator. The copolymer compositions were determined from tin analyses. The monomer reactivity ratios for copolymerizations of ABTB (monomer-1) with allyl methacrylate, N-vinyl pyrrolidone and vinyl acetate have been found to be r1 = 0.28, r2 = 0.89; r1 = 0.07; r2 = 0.40 and r1 = 0.92, r2 = 0.99, respectively. The Q and e values for the organotin monomer were calculated.

Beta-Aroyl-alpha-(indol-3-yl)propionic acids II were prepared by the reaction of beta-aroyl-acrylic acid I with indole in dry benzene. Reaction of II with hydrazine hydrate afforded dihydropyridazinones III. The reaction of III with ethyl bromoacetate and dimethyl sulphate in different solvents was studied. Compounds III reacted with POCl3/PCl5 to give chloropyridazine VI. The behaviour of VI towards some nucleophiles was investigated. Reaction of III with bromine/acetic acid mixture and Grignard reagents was described. Dehydration of II yielded the butenolids XII which underwent ring opening reaction with amine to give XIII. Also compounds II reacted with hydroxylamine lo give dihydro-1,2-oxazin-6(211)-one XIV. The antimicrobial activity of some synthesized products was investigated.

The chelates of some arsenazo compounds: 1-(1-phenylazo-2-arsonic acid)-2-naph-thol,4-(1-phenylazo-2-arsonic acid)-1-naphthol,4-(1-phenylazo-2-arsonic acid)-1-hydroxy-2-naphthoic and 2-hydroxy-1-(1-phenylazo-2-arsonic acid)-3-naphthoic acid with Sc(III), Y(III), La(III), Th(IV) and UO2(II) ions have been investigated in solution using spectrophotometric and conductometric titration methods. The studies revealed the formation of complexes of stoichiometric (metal : ligand) ratios 1 : 1 and 1 : 2. The chelates have been produced in solid state and their structures are characterised by chemical analysis, thermal methods (DTA and TGA) and electronic, IR absorption spectra.

Butyl rubber (IIR) loaded with 20 parts per hundred parts rubber (phr) BaTiO3 was mixed with different concentrations of the various carbon blacks HAF, GPF, SRF and lampblack. Electrical conduction measurements of vulcanisates were carried out at various applied electric powers. The temperature change (Delta T) of the rubber samples as a result of Joule heating against time (t) was recorded. The Delta T-t characteristics were found to be markedly dependent on the carbon black type and concentration as well as the ambient temperature. No appreciable change in the above characteristics with thermal aging was observed over long times (up to 6 months). Theoretical calculations of the specific heat (C-p) carried out and correlated with those obtained experimentally by the flash method.

The problem of characterizing all regularly solvable operators and their adjoints generated by a general ordinary quasi-differential expressions Mp on any finite number of intervals Ip=(a(p), b(p)), P=1, 2, ..., N are studied in the setting of the direct sum of L(wp)(2)(a(p), b(p))-spaces of functions defined on each of the separate intervals. The domains of these operators are described in terms of boundary conditions involving the L(wp)(2)(a(p), b(p)) solutions of M(p)[u]=lambda w(p)u and the adjoint equation M(p)(+)[v]+lambda w(p)v(lambda epsilon not subset of). These boundary conditions involve M(p) expression on any finite number of intervals I-p,p=1, ..., N.

Structural and energetic properties of metal-non-metal interactions were estimated at the Hartree-Fock level of ab initio theory. The convergence of the many-body expansion and group theoretical parameterization were found to uniquely characterize these interactions.

Several routes for building up the LiF unit cell from cluster and crystal fragments are examined. Two routes were detected and compared with each other in connection with their capabilities to reproduce binding energies within the unit cell environment. An extrapolation method is suggested to reproduce binding energies beyond the unit cell environment. Several nucleation mechanisms are also examined and correlated with the corresponding binding energies.

The effects of gamma radiations on the kinetic parameters of the dynamic thermal decomposition-gasification reactions of ammonium oxalate monohydrate have been investigated using differential thermal analysis and thermogravimetry techniques. Kinetic analysis of the dynamic TG results are discussed in view of a composite integral method in comparison with the integral methods due to Coats and Redfern and to Ozawa. The activation parameters for the non-irradiated and irradiated samples are calculated and the results of the different methods of data analysis are compared and discussed.

Extensive study of composition, stability constants and optimum conditions of Fe(III), Ni (II) and Cu(II) complexes with lour aro compounds based on 4 - amlnoantipyrene are done. The coloured complexes formed, at the optimum conditions mentioned, can be successifully used In the microdetermination of metal ions In synthetic solutions as well as In Incoloy 800 alloy. The method described Is rapid, sensitive, highly accurate and reproducable.

A characterisation is obtained of all the regularly solvable operators and their adjoints generated by general ordinary quasidifferential expressions in L(w)2(a, b). The domains of these operators are described in terms of boundary conditions involving the L(w)2(a, b) solutions of M[u] = lambdawu and the adjoint equation M+ [upsilon] = lambdaBARwupsilon(lambda is-an-element-of C) at both singular end-points a and b. These results are an extension of those proved in [3], by Evans and Ibrahim, to the case of two singular end-points of the interval (a, b), and a generalisation of those in [10] and [13] concerning selfadjoint and J-selfadjoint differential operators, where J denotes complex conjugation.

N-Antipyryl acrylamide monomer [2,3-dimethyl-1-phenyl-5-oxo-3-pyrazolin-4-ylacryloylamine) was synthesized by the reaction of 4-aminoantipyrine with either acryloyl chloride or acrylic acid in the presence of N,N'-dicyclohexyl carbodiimide as the dehydrating agent. Binary copolymerizations of this new monomer with methyl acrylate, ethyl acrylate, butyl acrylate and styrene were performed in dimethylformamide at 65-degrees-C using 1 mol% azobisisobutyronitrile as the initiator. The copolymer compositions were determined from the nitrogen analyses. Copolymerization parameters for each system were calculated by the Fineman-Ross and Kelen-Tudos methods.

beta-(4-phenylbenzoyl)acrylic acid I reacted with 6-(2'-methoxynaphthalenyl)-4-phenylpyrimidine-2(1H)thione to furnish alpha-[6-(2'-methoxynaphthalenyl)-4-phenylpyrimidinylthio]- beta-(4-phenylbenzoyl)propionic acid II. Dehydration of acid II aforded furanone derivative III. The behaviour of III towards hydrazine hydrate, hydroxylamine hydrochloride, primary amines, aromatic hydrocarbons (under Friedel-Crafts conditions) and carbon nucleophiles (under Grignard conditions) has been investigated.

The coherent multiparticle production in pi- (340 GeV/c) and in K+/-(70 GeV/c) interactions with nuclei is studied using the nuclear-emulsion technique. The mean free path and cross-sections of the three-prong events are estimated and compared with other data. A SIGMA(i) sintheta(i) analysis, pseudorapidity and azimuthal angular distributions are discussed.

The field of the learning sciences is represented by a growing community internationally. Many experts now recognize that conventional ways of conceiving knowledge, educational systems and technology-mediated learning are facing increasing challenges in this time of rapid technological and social changes. Herein, a suggested innovative, challenging trend at the field of the learning sciences is adopted. This trend deals with complex issues associated to deferent educational/learning phenomena. This paper presents a novel realistic simulation of some observed educational phenomena using ANNs modeling. Results obtained after practical application of a computer assisted instructional program are mainly motivating our realistic ANNs computer models. In some details, suggested ANNs models simulate realistically students' learning behavioral phenomena for two different cognitive styles. These styles are field dependent (FD) style and field independent (FI) one. Both were simulated via two types of ANNs models obeying two learning paradigms. That is supervised and unsupervised learning paradigms simulating FD and FI cognitive styles respectively. Moreover, both models simulate adaptive performance of learner control as learning process proceeds. That is fulfilled after following of suggested deferent lea mer control indices to simulate deferent levels of learner control. Interestingly, obtained results shown to be agree well with results obtained by practical educational experimental work. Additionally, our results give a valuable interpretation to some other results obtained after some educational studies. Conclusively, this paper, in few words, classified as an interdisciplinary research work dealing with some complex challenging educational issues. In practice, these issues arise recently due to excessive progress in computer and information technologies. That applied in educational practical field aiming to reach non traditional (non classical) solutions for confronted issues.

Time delays occur in many physical systems. In particular, when automatic control is used with structural or mechanical systems, there exists a delay between measurement of the system state and corrective action. The concept of an equivalent damping related to the delay feedback is proposed and the appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. We investigate the fundamental resonance and subharmonic resonance of order one- half of a harmonically oscillation under state feedback control with a time delay. By using the multiple scale perturbation technique, the first order approximation of the resonances are derived and the effect of time delay on the resonances is investigated. The fixed points correspond to a periodic motion for the starting system and we show the external excitation- response and frequency- response curves. We analyze the effect of time delay and the other different parameters on these oscillations.

The effect of frying of potato chips (batch processing during 12 h) on the chemical characteristics and fatty acid composition of the used oil were determined. Samples of the fried oil and potato chips were taken at various time periods. The volatile carbonyl compounds of the aroma concentrate of each sample were isolated and their oxime derevatives were prepared and subsequently estimated by UV absorption for the total oximes and conjugated diene carbonyl oximes. The development of the volatile carbonyl compounds in both frying oil and fried potato chips was increased on continued frying. Concerning the frying oil this increase was found to be in coincident with the decrease in the linoleic and linolenic acid percent.

The electrochemical behavior of citrazinic acid azo dye derivatives (I-V) was recorded in aqueous buffer solutions containing 10% (v/v) DMF using DC-polarography and cyclic voltammetry. The DC-polarograms displayed one or two reduction waves depending on the nature of substituent and the pH of the electrolyte solution. The reduction process takes place irreversibly and diffusion controlled at the electrode surface through the uptake of four electron/molecules for compound I and eight electron/molecules for each of compounds II-V. The recorded cyclic voltammograms displayed two irreversible cathodic peaks at different pH values. The kinetic parameters of the electrode process such as, an, heterogeneous rate constant (k s) and activation energy (ΔG#) were evaluated and discussed from cyclic voltammetry. Also, the electrode reaction mechanism is proposed and discussed. The effect of introducing substituents on the half-wave potential of the reduction process is illustrated. The different thermodynamic parameters such as activation energy (ΔG#), enthalpy change (ΔH#) and entropy change (ΔS#) revealed the endergonic nature of the electrode reaction.

The kinetics of the thermal decomposition of Cu- and Co-itaconato complexes were studied using dynamic thermogravimetric techniques. The dehydration process was found to proceed in a one-stage reaction, while the thermal decomposition of the anhydrous salts was followed a two-stage reaction. The first stage is the decomposition of the complex to metal carbonate, whereas the second stage is the decomposition of the formed carbonate to the oxide. Kinetic analysis of the dynamic TG curves were discussed with reference to a composite integral method on comparison with the integral methods of Coats and Redfern and Ozawa. The activation parameters were calculated and discussed for each decomposition step.

We have studied the effects of radiation on the boundary layer flow and heat transfer of an electrically conducting micropolar fluid over a continuously moving stretching surface embedded in a non-Darcian porous medium with a uniform magnetic field. The transformed coupled nonlinear ordinary differential equations are solved numerically. The velocity, the angular velocity, and the temperature are shown graphically. The numerical values of the skin friction coefficient, the wall couple stress, and the wall heat transfer rate are computed and discussed for various values of parameters.

Ternary copolymerization reactions of p-acryloyloxy-tri-n-butyltin benzoate (ABTB) with N-vinyl-2-pyrrolidone (NVP) and alkyl acrylates [ethyl (EA) and butyl acrylate (BA)] or vinyl acetate (VA) were carried out in solution at 65 degrees in the presence of a free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey-Goldfinger equation. The unitary, binary and ternary azeotropes of various systems studied was easily determined by a computer program. The results obtained showed that there is no ternary azeotropic compositions for any terpolymer system studied. Selective unitary and binary azeotropic compositions were polymerized and the results obtained showed good agreement between the theoretical and experimental terpolymer composition for each case.

This paper considers a kind of nonlinear matrix equations. Two effective iterative algorithms for obtaining the maximal positive definite solution are proposed. They improve and accelerate the convergence to the solution. An estimate for the convergence rate is given under additional conditions. Numerical results are given to illustrate the performance of the algorithms.

The dissolution of carbon steel was studied in HCl solution as a function of acid and inhibitor concentrations as well as of temperature. The inhibition efficiency of some ethoxylated fatty amines having the general formula R-NH-(CH2CH2O)(n) - H, as determined from polarization measurements and weight loss experiments, was found to increase, with increasing the inhibitor concentrations and/or decreasing the temperature. Inhibition was explained by adsorption on the metal surface through their ethoxy groups while the hydrocarbon parts protrude brush like into the solution. These compounds inhibit both cathodic and anodic reactions acting as mixed inhibitors.

The polarographic behaviour of the degradation product of ampicillin formed by alkaline bydrolysis is studied at different pH values. In strong alkaline solution (pH = 12) it gives two reduction waves with half-wave potentials -0.62 and -1.35 V vs. SCE. The first wave (at -0.62 V) is used for analytical purposes. A new and sensitive method is described for analytical determination of ampicillin in its pharmaceutical formulation and human urine.

A spectrophotometric method has been developed for the microdetermination of sulfamethoxazole rind trimethoprim drugs. The proposed method is based on the charge transfer (CT) complex formation of the drug with alizarin or quinalizarin in alkaline medium and measuring the developed absorbance at its maximum. The optimum conditions for maximum absorbance results are studied and Beer's law is obeyed in the ranges 10-130 and 10-190 mu g/ml for sulfamethoxazole and trimethoprim respectively. For more accurate results, Ringbom optimum concentration ranges are 20-120 and 10-170 mu g/ml respectively. The molar absorptivity and Sandell sensitivity are also calculated. The proposed spectrophotometric method of analysis is as accurate as the USP method (USP XX. The National Formulary, NF XV, 1980 P. 925. Mack Easton, Pa., 1980) and is simpler than their official method. Applications of the suggested method to representative pharmaceutical sulfa drugs are presented and the validity of the method was assessed by applying the standard addition technique.

Spatio temporal dynamics of the positive column of a do neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio-temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg-Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio-temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space-time data and theoretical simulation space-time results was obtained.

The aminothiadiazole (II) on treatment with aromatic aldehydes yielded Schiff bases, which cyclized to thiazohdinone derivatives by reaction with thioglycolic acid. Reaction of II with phenyl isocyanate and phenyl isothiocyanate afforded the carbamide and caxbothiamide derivatives, respectively, which on reaction with malonic acid in acetyl chloride gave barbituric and thiobarbituric acid derivatives. However, reaction of carbon disulfide and methyl iodide with II gave dithiocarbamidate derivative which on treatment with ethylenediamine or o-phenylenediamine gave the condensed N-imidazolylthiadiazolylamine derivatives.

A sensitive spectrophotometric method for zinc has been established by reacting zinc with three salicylic acid azo dyes 2-hydroxy (la), 2-carboxy (Ib) and 4-(2-arsonophenylazo) salicylic acid(lc)in universal buffer solution of pH 8.4, 7.1 and 6.0 respectively. The molar absorptivities are 1.16, 1.39 and 1.36 X 10(4) l/mol.cm at 515, 450 and 525 nm using reagents Ia, Ib and Ic respectively. The formed complexes have the molar ratios of zinc to ligands 1 : 1 and 2 : 1. Beer's law is obeyed upto 7.19 ppm of zinc whereas the optimum concentration range as evaluated by Ringbom's method is 0.5-7.00 ppm. Sandell sensitivities of the method are evaluated. The method has been used to determine zinc in various pharmaceutical products.

This study aimed to investigate the effect of heat treatment on microstructure and phase composition of pastes containing fly ash (FA) and limestone (LS). Two groups of cement pastes were prepared. In the first group, Portland cement (OPC) has been partially replaced by 10, 20 and 30 wt.% FA (M.0, M.10, M.20, M.30). The second group of specimens is constituted by samples derived from M.20, in which, FA has been replaced by 5, 10, 15 and 20 wt.% LS (L.5, L.10, L.15 and L.20). After 28 and 366 days of water curing, the hardened cement pastes were dried at 105 degrees C for 24 hours, subjected to thermal treatment for 3 hours at 250, 450, 650 and 800 degrees C, then cooled to room temperature in the furnace switched off. The compressive strength and weight loss were determined. Scanning electron microscopy, differential scanning calorimetry and X-ray diffraction were used for identification of the changes occurring in the microstructure of the formed or decomposed phases. The results show that additional hydration of unhydrated cement grains, recrystallization, deformation and transformation of CSH phases were occurred. The changes in physical state of cement pastes were studied by measuring deterioration in the compressive strength with temperature.

A linear rate equation describing fragmentation processes, which includes both continuous and discrete loss of mass, is reduced to a partial differential equation. Different types of similarity solutions are obtained by applying Lie's similarity method.

Thermal decomposition of mixed copper and manganese carbonates in molar ratios 1:1 and 1:0.5 with respect to CuO: MnO2 doped with 1, 2.5 and 5 wt.% Mg2+ has been studied. The thermal products obtained at different temperatures have. been characterized by X-ray diffraction analysis. The catalytic activity of the thermal products has been tested in H2O2 decomposition. Calcination of mixtures at 200 degrees C produces three crystalline phases CuO, Cu-2(NO3)(OH)(3) and unaffected MnCO3. The increase in temperature of treatment leads to the formation of manganese oxide which in turn reacts with CuO forming spinel CuMn2O4. The incorporated magnesium in the spinel structure occupies the octahedral coordinated sites [Cu0.752+Mn0.252+(Cu0.252+Mg0.5(2+)Mn(1.5)(2+))O-4]. Catalytic activity of the undoped samples increases creases with increase in the calcination temperature up to 500 degrees C and at 800 degrees C it decreases. The doping with magnesium ions shows slight change in activity for catalysts calcined at 200 degrees and 500 degrees C, while considerable increase in activity is detected for catalysts calcined at 800 degrees C. This may be attributed to lattice inversion defects and distortions of the formed spinel besides CuO present with other oxides.

This work aims to study the effect of the polycarboxylate superplalsticizer (PCS) on the rheology. electrical conductivity. physico-chemical and mechanical properties of ordinary Portland cement (OPC) pastes containing silica fume (SF). The blended cement pastes were prepared from OPC-SF (90 wt.% OPC + 10 wt.% SF). The results show that addition of PCS to the cement blends decreases their electrical conductivity during the early and later ages up to 28 days. In addition, PCS admixture considerably affects the amount of chemically combined water Compressive strength of OPC pastes is higher than that of pastes containing SF However, the addition of 0.75-1.5 wt.% PCS brings higher compressive strength values of OPC-SF pastes than those of OPC cement pastes.

Accurate measurements of some electrical properties combined with the differential thermal analysis (DTA) were made from room temperature up to 200-degrees-C for single crystals of KHSO4 (KHS). The data reveal the existence of two (non-ferroelectric) phase transitions around 100-degrees-C and 175-degrees-C. The first structural phase transition may involve only minor change in atomic positions and therefore it is not easy to detect. The existence of this phase is confirmed by the X-ray diffraction pattern. The data are correlated with the arrangement of the molecules in the unit cell including the hydrogen bonding system due to the two distinct HSO4 ions as well as the onset of the reorientational motion of the sulphate group.

We study some relationships between a fuzzy uniformity and its alpha-level uniformities. We prove that a fuzzy neighbourhood space is fuzzy uniformizable iff its alpha-level spaces, for all 0 < alpha < 1, are uniformizable. We supply an explicit formula for a fuzzy uniformity inducing such a space. Similar criteria are established for the axioms of N-normality NT2, NT1, WNT1, NT0, WNT0 and NR0. We show that the two notions of the alpha level uniformity of a fuzzy uniformity induced by a fuzzy metric, and the uniformity generated by the a-level metric of that fuzzy metric, are compatible. We also supply an explicit formula for a fuzzy pseudo-metric which induces a fuzzy neighbourhood space whose alpha-level topologies are pseudo-metrizable for all 0 < alpha < 1.

The copolymerization of p-acryloyloxy-tri-n-butyltin benzoate (ABTB) with acrylonitrile (AN) has been investigated in dimethylformamide (DMF), using azobisisobutyronitrile (AIBN) as an initiator. The prepared homopolymer of (ABTB), as well as the copolymers, were characterized by a variety of analytical, spectral, and thermal methods. Thermogravimetry (TG) and differential thermal analysis (DTA) data showed a little improvement in the thermal behavior of the investigated copolymer. A mechanism for the initiation of ABTB units in the nitrile oligomerization in the copolymer was also proposed. (C) 1994 John Wiley & Sons, Inc.

Alpha-Amino phenyl acetyl-N-phenylhydroxamic acid has been prepared, identified by microanalysis, IR and NMR. The prepared compound was used in gravimetric determination of Cu(II), Ni(II), Zn(II), Mn(II), Al(III) after precipitation of metal complex. The reagent was used for separation of a mixture of binary catinos by either adjustment of acidity or using a masking agent. The precipitate is weighed as M(C14H13N2O2)2 in the case of divalent cations and as M(C14H13N2O2)3 for trivalent cation after drying at 110-120-degrees-C. The gravimetrically determination of iron(III) and vanadium was failed. The interfering ions were determined. The accuracy is generally more than 0.3%.

Ternary copolymerization of N-antipyryl acrylamide (NAA) with different alkyl acrylates [methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BuA)] or styrene (ST) and acrylonitrile (AN) were carried out in solution at 65-degrees-C in the presence of AIBN as a free radical initiator. Experimental terpolymerization data agree well with calculations based on the Alfrey-Goldfinger equation. The determination of unitary, binary, and ternary azeotropes of various systems studied was easily handled by a computer program. Ternary azeotropic compositions for NAA-MA-AN, NAA-EA-AN, NAA-BuA-AN, and NAA-ST-AN systems were 31.0: 10.0: 59.0, 37.0: 09.0: 54.0, 23.0: 10.0: 67.0, and 66.5: 30.50: 03.0 mol %, respectively. Selective unitary and binary azeotropic compositions were polymerized and the obtained results show good agreement between the theoretical and experimental terpolymer composition for each case. Also, pseudo-azeotropic regions were identified where the deviation between feed and polymer composition is very small. The azeotropic points of the four systems were confirmed using Tarasov et al.'s equations and were found to have satisfactory results. (C) 1994 John Wiley & Sons, Inc.

Mashhour and Morsi introduced an axiom of N-complete regularity to characterize the Lowen fuzzy uniformizable fuzzy neighbourhood spaces (fns's). Guided by that axiom we supply a Sierpinski object for the Artico-Moresco category FP of fuzzy proximity spaces, which Katsaras has shown to be a topological category. We define the degree of functional fuzzy separatedness of a pair of subsets of a fns. We use that notion to define the Cech fuzzy proximity of an N-completely regular fns (X, rho). We establish that it is the finest fuzzy proximity that induces the fns (X, rho). We study in some detail the Czech fuzzy proximities obtained from N-normal fns's.

A simple and selective method for the determination of amoxycillin in pure form and in pharmaceutical preparations is described. The procedure is based on the reaction of amoxycillin with 4-nitrophenol (1), 2,4-dinitrophenol (11), 3,5-dinitrobenzoic acid (III) or 3,5-dinitrosalicylic acid (IV) in alkaline medium. The method has been used for the determination of 1-24 mug/ml of amoxycillin trihydrate in solution. The method is selective for the determination of amoxycillin in the presence of its degradation products, other antibiotics and different amines that are normally encountered in dosage forms.

The synthesis, spectral characteristics, and analytical application of 2,3-Dichloro-6-(3-car xy-2-hydroxy-1-naphthylazo)quinoxaline (DCHNAQ) are described. A simple, rapid, selective, and sensitive spectrophotometric method for the determination of microgram amounts of gold, alone, or in the presence of associated metals, is developed, based on the color reaction between the metal ion and the reagent. The yellowish brown complex (lambda(max) = 575 nm) has stoichiometric ratio (1:1) [metal:ligand] over the pH range 3.4 to 7.0. Beer's law is obeyed over the concentration range 0.1-6.9 mug cm-3 of gold. The molar absorptivity and Sandell's sensitivity of the method are 1.52x10(4) dm3 mol-1 cm-1 and 0.016 mug Au cm-1 respectively. The relative standard deviation for six replicate determination of 2.95 mug CM-3 of gold(III) is 1.37%. The interference of various ions has been studied and conditions were developed for the determination of gold in alloys and some synthetic samples without the need for extraction or heating.

2-Pyrimidyl acrylamide monomer (2PA) has been prepared by the reaction of 2-amino pyrimidine with acrylolyl chloride in the presence of triethylamine as catalyst. Its structure was confirmed by IR and H-1 NMR spectroscopy. Ternary copolymerizations of 2-pyrimidyl acrylamide monomer (2PA) with methyl acrylate (MA), methyl methacrylate (MMA), ethyl acrylate (EA), butyl acrylate (BuA) and acrylonitrile (AN) were carried out in THF at 65-degrees-C in the presence of a free radical initiator. Experimental terpolymerization data agree well with calculations based on the Alfrey-Goldfinger equation. The determination of unitary, binary and ternary azeotropies of the various systems studied were easily handled by a computer. The ternary azeotropic compositions for 2PA-MA-AN and 2PA-MMA-AN were 32.20:17.5:50.30 and 13.54: 52.64: 33.82 mol%, respectively. Pseudo-azeotropic regions were identified where the deviation between feed and polymer composition is very small.

The vibrational and rotational characteristics of the ground bands of even-even nuclei with 150 less-than-or-equal-to A less-than-or-equal-to 166 (2 < R4 < 3) are studied. The spectra of these nuclei (with band crossing angular momentum I(c) greater-than-or-equal-to 12) are analyzed with a cubic polynomial in I. The considered nuclei (Sm-150, Gd-152, Dy-154-156, 156Er, Yb-158,Yb-160,Yb-162 and Hf-162,Hf-164,Hf-166 lie in the central region between the Z = 50 and Z = 82 major shell closures and span the spherical to the well deformed region. The gradual shape transition from a soft spherical vibrator to a deformed rotor from Sm-150 to 166Hf is thus made explicitly apparent from the g-band spectrum analysis in terms of the vibrational, rotational and softness coefficients. The transition at N = 88-90 for the vibrational-rotational ratios and for the kinematic moments of inertia are reproduced.

2-Pyrimidyl acrylamide (2PA) monomer was prepared by the reaction of 2-aminopyrimidine with acryloyl chloride. Its structure was confirmed by IR, H-1 NMR, and MS spectroscopy. Binary copolymerizations of this new monomer with methyl acrylate (MA), ethyl acrylate (EA), butyl acrylate (BuA), methyl methacrylate (MMA), vinyl acetate (VA), and acrylonitrile (AN) were performed in tetrahydrofuran, using 1 mol% azobisisobutyronitrile as initiator at 65-degrees-C. N analysis and H-1 NMR spectroscopy were used to determine the composition of the copolymers. Copolymerization parameters for each system were calculated by both the Fineman & Ross and Kelen & Tudos methods. The monomer reactivity ratios for the systems 2PA-MA, 2PA-EA, 2PA-BuA, 2PA-MMA, 2PA-VA, and 2PA-AN were found by the Kelen & Tudos method to be r1 = 0.58 +/- 0.042, r2 = 1.26 +/- 0.086; r1 = 0.63 +/- 0.041, r2 = 1.04 +/- 0.072; r1 = 0.88 +/- 0.051, r2 = 0.99 +/- 0.069; r1 = 0.43 +/- 0.021, r2 = 1.60 +/- 0.094, r1 = 0.69 +/- 0.051, r2 = 0.084 +/- 0.088; and r1 = 0.065 +/- 0.008, r2 = 2.54 +/- 0.220, respectively. The average Q and e values for 2PA were found to be 0.51 and 0.66, respectively.

We introduce a new R1 separation axiom for fuzzy topological spaces. We identify, from the literature, which lower fuzzy separation axioms are compatible with our R1 axiom. We provide alternative descriptions for this R1 axiom in the special setting of fuzzy neighborhood spaces. This special case has standard higher fuzzy separation axioms. In it, we establish aspects of compatibility of our R1 axiom with those higher separation axioms, as well as with fuzzy compactness.

The Lie similarity method has been used to extend the similarity solutions of the one-dimensional inhomogeneous nonlinear diffusion equations. We determine the Lie point symmetry vector fields and calculate the similarity ansatz. Then we discuss the resulting nonlinear ordinary differential equations. Exact solutions are found, and their relations to some real physical are discussed.

N-antipyryl-acrylamide monomer (NAA) (2,3-dimethyl-1-phenyl-5-oxo-3-pyrazolin acryloylamine) was copolymerized with acrylonitrile in dimethyl formamide using azobis-isobutyronitrile (AIBN) as initiator. The homopolymer and also the copolymers were characterized by a variety of spectral and thermal methods. Thermogravimetry (TG) and differential thermal analysis (DTA) data showed a remarkable improvement in the thermal behaviour of the investigated copolymers. A mechanism for the participation of the acryl-oyloxy units in the nitrile oligomerization is proposed and confirmed by interpretation of the fragmentation patterns of the mass spectrum of the N-antipyryl-acrylamide (NAA) monomer and also the IR spectra of the copolymers after heating.

Ampicillin trihydrate (12.5-575 mug) and amoxycillin trihydrate (10-400 mug), in 25-ml total volume, are determined spectrophotometrically using picric and picramic acids as pi-acceptors at pH 9. The method is relatively accurate (with a recovery of 100 +/- 1.67%) and precise (RSD = 1.7%) and was applied successfully to capsules, ampoules, and syrup formulations. (C) 1994 Academic Press, Inc.

Locally produced non-edible oil, namely, rice bran oil (R.B.O.) was utilized as starting materials for preparing new nonionic surfactant. Oxypropylated diet monoesters of linoleic and rice bran oil fatty acids were prepared. Also amide oxime derivatives were obtained. Surface active properties of these compounds were measured. Under neutral condition amide oximes served as nonionic surfactants and their properties were similar to other oxypropylated monoesters.

Four hundred forty seven isolates belonging to 12 genera and 29 species were identified in poultry fodder stored from August 1988 to July 1989. Aspergillus and Penicillium were the genera most commonly isolated from the fodder. Aflatoxins were first detected at the 4th month of storage, gradually increased until the 6th month, when the highest counts of fungi were recorded, then greadually decreased to undetectable levels at the 9th month of storage. Aflatoxins B1, B2, G1 and G2 were produced by 112 of 447 isolates belonging to 11 genera and 25 species. Aspergillus flavus (134 isolates) and Penicillium notatum (72 isolates) were the most common aflatoxin-producing species. Aspergillus flavus (435) produced the largest amount of aflatoxin B1 (800 mug/l), and Penicillium notatum (33) produced the largest amount of aflatoxin G1 (240 mug/l) when compared with all other isolates. Penicillium notatum (33) also produced aflatoxin B1 (20 mug/l). Propionic and oxalic acids completely inhibited growth and aflatoxin production of A. flavus (435) and P. notatum (33) between pH 2.5 and 5.0. Citric acid and tartaric acid completely inhibited the growth and aflatoxin production of the same isolates at pH values between 2.5 and 4.0.

3-Hydrazinopyridazine (5) has been synthesized by a four-step route. The hydrazine (5) on treatment with ethyl acetoacetate and/or acetylacetone undergo cyclization to afford pyrazolone derivative (6) and 3-(pyrazol-1-yl)pyridazine derivatives (7) respectively. Condensation of 5 with ethyl chloroacetate and/or diethyloxalate furnish 1,2,5-triazino-fused ketones (8 and 9) of the tide pyridazine respectively. Also, condensation of 5 with aromatic aldehydes and/or acetic anhydride afford 3-aryl- and 3-methyl substituted 1,2,5-triazolo-fused pyridazines (11 and 13) respectively. Diazotization of 5 with nitrous acid give 3-azidopyridazine (14) which undergo thermal cyclization to furnish the tetrazolopyridazine (15).

Three fatty acid ethoxylates obtained form soya bean oil with different numbers of ethylene oxide units were used as inhibitors for C-steel corrosion in 2 M H2SO4 solution. Their inhibition efficiencies have been evaluated using three different techniques; weight loss, hydrogen evolution and polarization techniques. It has been found that, the inhibitive effect increases as the number of ethylene oxide units is increased. Moreover, the compound studied follow the Langmuir adsorption isotherm in their adsorption on the metal surface. It was concluded that, they adsorbed on the metal surface on both anodic and cathodic sites (mixed inhibitors).

Different partitionings of the Li2F2 model cluster into interacting subunits were investigated in order to select the best partitioning for building a model potential. Two criteria were used for selecting the best partitioning: the total interaction energy; and the covergence of many-body effects. A certain partitioning was detected and may be recommended as an alternative to the partitioning which is commonly used in supermolecular calculations.

The kinetics of the non-isothermal decomposition of potassium nickel(II) oxalate in air were studied for non-irradiated and irradiated crystals using thermogravimetric techniques. Analysis of kinetic data were performed using the direct differential method, the integral methods due to Coats-Redfern, Ozawa and a composite integral method. The results of the kinetic analysis of dynamic data and the effects of radiation were discussed and compared with those obtained under isothermal conditions.

The physicochemical properties (crystal structure, surface acidity, surface area, catalytic activity and electrical conductivity) of TiO2-silica gel mixed oxides have been investigated. A series of mixed oxides of various compositions in the range of 0-100% for each component were prepared by calcining the mixed oxides in air at temperatures of 115, 300, 600 and 1000-degrees-C. The results obtained have been discussed and correlated.

3-Amino-2-methyl-4(3H)-quinazolinone (2) has been synthesized by treating 2-methylbenzoxazinone (1) with hydrazine hydrate. Reaction of quinazolinone (2) with phenyl isothiocyanate and phenyl isocyanate furnish the corresponding aminocarbothiamide and aminocarbamide derivatives (3 and 5), respectively, which on reaction with malonic acid in acetyl chloride afford thiobarbituric and barbituric acid derivatives (4 and 6), respectively. Behaviour of compound 5 towards different aldehydes, ketones and imides have been investigated.

Mn(II), Co(II), Ni(II), CU(II) and Zn(II) complexes with some derivatives of o-hydroxyphenylazo-1-methyl-3 -phenyl-2-thiohydantoin have been prepared. Their stoichiometry and stability constants were investigated in solution using conductometric and potentiometric measurements. The ionization constants of the ligands and the formation constant of the chelates were determined. The structure of the solid complexes (IM : 1L) and (1M : 2L) has been confirmed by elemental analyses, thermal (TGA and DTA) methods, IR and H-1 NMR spectra.

In this paper, the general ordinary quasidifferential expression M of nth order, with complex coefficients, and its formal adjoint M(+) are considered. It is shown in the case of two singular endpoints and when all solutions of the equation and the adjoint equation are in L(w)(2)(I) (the limit-circle case) that all well-posed extensions of the minimal operator T-0(M) have resolvents which are Hilbert-Schmidt integral operators and consequently have a wholly discrete spectrum. This implies that all the regularly solvable operators have all of the standard essential spectra to be empty. These results extend those for the formally symmetric expression M studied in [1] and [14], and also extend those proved in [8] for one singular endpoint.

The thermal properties (thermal conductivity lambda, thermal diffusivity a, and specific heat capacity C-p) of butyl rubber with 100 phr of different carbon blacks (HAF, GPF, SRF and LAMP black) were measured in the temperature range 300-450 K. The thermal properties were slightly affected by the addition of the different carbon blacks, and there was a sharp increase in both lambda and C-p with temperature on addition of 20 phr of powdered BaTiO3 ceramic only for samples containing SRF and HAF carbon blacks. The electrical conductivity, sigma, was also measured for these composites. It increased appreciably with the surface area of the added carbon black. On addition of 20 phr of powdered BaTiO3 ceramic, the electrical conductivity was observed to increase for all the butyl rubber composites.

Two simple, selective and sensitive spectrophotometric methods are described for the determination of 6-aminopenicillanic acid (6-APA). The methods are based on the reaction of 6-APA with either bromophenol blue (BPB) or bromothymol blue (BTB), to give orange-red and green species, respectively. The coloured products are quantified spectrophotometrically at 625 and 616 nm for BPB and BTB, respectively. The optimization of the different experimental conditions is described. No interferences from different beta-lactams and common degradation products were observed in the determination of 6-APA using BTB, while flucloxacillin, dicloxacillin, adrenaline, vitamin C, urea and common degradation products in any percentage interfere on using BPB only. The BTB method was better than the BPB method, because of its wider range of determination (0.4-20 mugml-1 vs. 0.4-7.2 mug ml-1 on using BPB), higher molar absorptivity and Sandell sensitivity (3.27 x 10(3)1 mol-1 cm-1) and 0.099 mug cm-2 vs. 2.82 x 10(3)l mol-1 cm-1 and 0.115 mug cm-2), greater stability (3 and 10 days on using BTB and BPB, respectively) and better selectivity. The results were compared with those given by the Official United States Pharmacopeial XXI method.

A simple and sensitive conductometric method for the determination of 2-24 mg of pindolol and propranolol hydrochlorides using ammonium reineckate and potassium tetracyanonickelate in an ethanol-water mixture is described. The effect of the solvent ratio, reagent concentration, time and temperature on the shape of the titration curve is studied. Statistical treatment of the experimental results indicates that the method is precise and accurate. The accuracy of the method is indicated by the excellent recovery (98.2-101.2%) and the precision is supported by the low standard deviation value

The validity of the point charge model applied to LiH crystal surface imperfection is tested by calculations carried out on crystal field and overlap effects. Two types of defects were considered, namely, Schottky or Schottky Wagner and self defects. An attempt was made to answer the question: How large must a crystal fragment be for its properties to be those of the bulk? The crystal fragment is LiH5 surrounded by four ion shells, and the properties are binding energy, defect energy, axial and equatorial hydride ion transfer energy and hydride ion desorption energy. The ease of constructing model potentials in the framework of the point charge model is confirmed.

Polarographic reduction of arylhydrazone derivatives of acetylacetone was studied in aqueous buffer solutions over a wide pH range (2-11). The results indicated that the reduction of all arylhydrazones occurs in a single 4-electron well defined wave. The effect of substituent groups on the half-wave potential has been correlated with Hammett substituent constant. The suggested mechanism is similar in both acidic and alkaline media. Stability constant of the metal complexes of these compounds with Cu2+, and Pb2+ ions in solution using differential pulse polarography and potentiometric measurements was calculated. The effect of substituent on the stability constant has been discussed.

We obtain a complete classification of all possible nontrivial similarity solutions of the free Kramers equation, together with a necessary and sufficient condition for each type to be reducible to the heat equation. A confluent hypergeometric solution of the free Kramers equation is derived for some classes of similarity solutions.

In this paper the general ordinary quasi-differential expressions of nth order with complex coefficients are considered, and a number of results concerning the location of the point spectra and regularity fields of the operators generated by such expressions are obtained. Some of these are extensions or generalizations of those in the symmetric case in [9, 10] and [11], while others are new.

The chelates formed between 1,4-bis(2'-hydroxyphenylazomethine) phenylene with La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, and Lu ions have been investigated in solution using conductometric, potentiometric, and spectrophotometric methods. The studies revealed the formation of M(2)L and ML complexes. The solid chelates have been characterized by elemental and thermal analysis, molar conductance, IR, H-1 NMR (for La and Lu chelates), and electronic spectra. The bonding takes place through the coordination of nitrogen in the -CH=N- group and the oxygen of the hydroxyl group by proton displacement.

Metalloid-nonmetal and Metal-nonmetal interactions of BF3, BCl3, AlF3 and AlCl3 were examined at the matrix Hartree Fock level of ab initio theory. Structural and energetic properties, many-body expansion convergence, short- and long-range components of interaction energies, and group-theoretical parameters were found to uniquely characterize these interactions.

Using Lie group methods, we analyse nonlinear diffusion equations in an inhomogeneous medium f(x)u(t)=(g(x)D(u(x))(x) with arbitrary diffusion coefficient D(u), and arbitrary thermal coefficients f(x) and g(x), which have a wide spectrum of applications in many areas of science. The Lie-group-based similarity method leads to a classification of the diffusion and thermal coefficients according to its symmetry properties. With the help of the adjoint representation, the optimal system of similarity reductions is calculated. Exact similarity solutions of the second-order ordinary differential equatiors resulting from the reductions are demonstrated by examples.

The electropolymerization of N-methylacryloyloxy phthalimide has been studied in DMF using a sacrificial nickel anode in the presence of tetrabutylammonium perchlorate as supporting electrolyte. The effect of different reaction parameters such as the type of electrolyte, concentration of monomer and electrolyte, current strength, the duration of electrolysis and the temperature of the reaction on the yield of the polymer and the rate of polymerization were studied. It was found that the nickel content in the obtained polymer depends on the concentration of the monomer. A mechanism of electropolymerization is suggested and confirmed by i.r., H-1-NMR, thermal analysis and electrical conductivity measurements.

Simple, rapid, accurate and sensitive spectrophotometric methods are described for the determination of norfloxacin. The methods are based on the reaction of this drug as a pi-electron donor with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ), p-chloranil (CL) or chloranilic acid (CLA) as pi-acceptors to give highly coloured complex species. The coloured products are measured spectrophotometrically at 460, 843, 550 and 531 nm for DDQ, TCNQ, CL and CLA, respectively. Optimization of the different experimental conditions is described. Beer's law is obeyed in the range 10-400 mu g ml(-1) and colours were produced in non-aqueous media and were stable for at least 3 h. Applications of the suggested methods to representative pharmaceutical dosage forms are presented and compared with the official method. Interferences from additives and common degradation products were investigated.

Five linear 1,3-dialkylbenzenes namely dibutyl-, dipentyl-, dihexyl-, diheptyl- and dioctylbenzenes were prepared in good yield via two simple catalytic routes under very mild conditions and affording insignificant side products. The starting feed, 1,4-di(1'-hydroxyalkyl) benzene was obtained from terephthalaldehyde and the appropriate n-alkylbromide through Grignard reaction. 1,4-Di (1'-hydroxyalkyl) benzenes were converted into the corresponding I,4-dialkylbenzenes either by oxidation-hgdrogenation or dehydration-hydrogenation routes. Oxidation was carried out at 50 degrees C using CrO3 and dehydration step was performed using anhydrous CuSO4 at 165-170 degrees C. Pd/C or (Pt/C) was used to catalyse the hydrogenation step at 60 degrees C and 3.4 bar H-2 pressure. Mass spectra of the obtained compounds were discussed. H-1-NMR and IR spectra were measured to add further confirmation to the structure.

The electrochemical behaviour of Fe and C-steel samples in oxalic acid solutions was studied by the use of cyclic voltammetry. Two peaks were observed; the first one was the anodic peak and the second one an unexpected reductive dissolution peak which could be observed in the cathodic branch of cyclic voltammograms of all electrodes studied. The carbon content was found to increase the active dissolution of steels and to decrease their tendency towards passivation. The inhibitive efficiency of phenyl phthalimide derivatives on the active dissolution of Fe and steel samples in 0.1 M oxalic acid were investigated.

The effect of HNO3 concentration and addition of the sodium salts of Cl-, CrO42-, WO42-, MoO42-, HPO42- and CO32- on the dissolution kinetic parameters of Ni, Inconel 600, Incoloy 800 and 316 SS were studied. Increase of acid concentration and addition of NaCl increased the corrosion rate. The remaining anion had an inhibitive effect by decreasing the rate of tire anodic reaction.

The rotation problem of an orthotropic cylinder containing. (i) an isotropic core and (ii) a rigid core is considered. The elastic constants and density are taken as a power function of the radial coordinate. Analytical expressions for the components of the stress in different cases are obtained. Finally, the results are illustrated graphically.

A very simple, highly sensitive and selective spectrophotometric method for the rapid determination of cobalt (II) in aqueous media containing 30% (v/v) ethanol is described. The method is based on the formation of green colour complex by the reaction of cobalt (II) with 1'-(2-arsenito-phenylazo) 2'-naphthol (I-a) and its 3'-carboxylic acid (I-b) in basic media. The effects of amount of reagent, pH, time and temperature have also been studied. Beer's law is obeyed over the range 0.1-4.0 mu g ml(-1) of cobalt with a minimum photometric error of 1.33%. A fair degree of selectivity for cobalt is achieved by measuring the absorbance of green colouration at 580 and 582 nm for I-a and I-b, respectively. The molar absorptivities for the green complexes are 3.65 and 4.1 x 10(4)-1 mol(-1) cm(-1) sensitivities are 8.1 and 7.2 ng cm for complexes of reagent I-a and I-b, respectively. The proposed method has been applied to determination of vitamin B-12 (cyanocohalamine phosphate) in pure form and in various pharmaceutical formulations.

The differential thermal analysis-thermogravimetry (DTA-TG) behaviour of chemically coprecipitated iron(III) oxalate-magnesium oxalate (1: 1 mole ratio) was investigated. X-ray diffractometry (XRD) of samples calcined at different temperatures showed that magnesium ferrite is formed in samples heated at higher temperatures. Integral composite analyses of dynamic TG data of the decomposition reactions in the coprecipitated mixture were carried out using various solid state reaction model equations, and the results showed that the decomposition reactions are best described by the two- and three-phase boundary, R(2) and R(3) models. Kinetic analyses of dynamic data were also carried out in accordance with the integral methods of Ozawa and Coats-Redfern and the results are discussed in comparison with the integral composite analysis of data.

A spectrophotometric procedure for the determination of six pharmaceutical sulfonamides containing a primary aromatic amino group using alizarine (I), alizarine blue (II), alizarine red (III), and quinalizarine (IV), that offers advantages of simplicity, rapidity, sensitivity, precision, and stability, has been developed. The proposed method is based on the formation of colored products with the chromogenic reagents (I-IV). A linear correlation was found between absorbance at lambda(max) and the concentration. For more accurate results, Ringbom optimum concentration ranges are evaluated. The molar absorptivities (epsilon), absorptivities (a), and Sandell sensitivities for all sulfonamides derivatives with the chromogenic reagents tested were calculated. The procedures developed are applied for bulk sulfa drugs and some of their dosage forms. (C) 1995 Academic Press, Inc.

Differential thermal analysis-thermogravimetry (DTA-TG), X ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were used to study the formation of CuCr2S4 spinel and the thermal decomposition reactions in crystalline mixtures of copper and chromium sulfides. The copper-chromium sulfide spinel was characterized by XRD and SEM and the kinetics of formation was followed in the temperature range 200-300 degrees C by a titrimetric method. Kinetic analysis in view of various solid-state reaction models showed that the reaction is best described by the diffusion models with an average activation energy 24.6 +/- 1.6 kJ/mol. (C) 1995 Academic Press, Inc.

(2-Methylquinazol-4-oxy) acetic acid hydrazide (3) reacts with appropriate aldehydes and ketone to give the corresponding hydrazone derivatives (4a-c and 6) which are subsequently cyclised to 4-thiazolidinone (5a-c) and pyrazole derivatives (7), respectively. Also, the cyclisation of the hydrazide 3 with acetonylacetone yield pyrrole derivative 8. Reaction of 3 with phenyl isothiocyanate and/or phenyl isocyanate in different solvents produced S-triazole (9), thiosemicarbazide and semicarbazide derivatives (10a,b), respectively. Compounds 10a,b are susceptible to ring-closure on treatment with phenacyl bromide leading to thiazole and oxazole derivatives (11a,b).

New electrodes for the selective determination of selenite were constructed by compressing either HgSeO3 or a mixture of HgSeO3 and Hg2Cl2. The linear concentration range was 6.0 x 10(-5)-10(-1) M with a slope of 29.5 mV/concentration decade. The usable pH range for both electrodes was wide (3-10) and their life span was up to 8 days. Selectivity coefficient values were determined for various anions and no significant interferences were observed for most of them. The solubility products of some sparingly soluble selenite salts were determined using the latter electrode.

2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C-12, C-14, C-16 and C-18 carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR) and nuclear magnetic resonance (NMR). Surface and interfacial tension, Krafft point, welting time, emulsification power, foaming height and critical micelle concentration (cmc) were determined and a comparative study was made between their chemical structure and surface active properties. Antimicrobial activity of these surfactants was also determined.

Four ate compounds based on 5-aminoindazole have been synthesized and characterized by elemental analysis as well as different spectroscopic techniques. The potentiality of the prepared compounds as new chromophoric reagents for the spectrophotometric determination of VO2+ was studied by extensive investigation of optimum conditions favouring the formation of the coloured complexes. The effect of interfering ions on the determination of VO2+ was investigated. Beer's law is obeyed in the concentration range of 1.0-12 mu g/ml. The detection limits are 0.8, 0.9, 0.7, and 1.1 mu g/ml using reagent 1a, 1b, 1c, and 1d, respectively. The standard deviations of the proposed method are 0.098, 0.111, 0.089, and 0.078. The molar absorptivities are 5.8, 6.7, 6.1, and 8.2 x 10(3) l . mol(-1). cm(-1) for 1a-d, respectively, whereas Sandell sensitivities are found to be 0.0187, 0.0163, 0.0174, and 0.0146 mu g . cm(-2) using the same reagents. The ability of using these reagents as metallochromic reagents in complex on III titrations was also studied.

UV spectra, de polarograms, cyclic voltammetry and coulometry measurements of salicylaldehyde-4-(2-pyridyl)-3-thiosemicarbazone (H2SPT) were recorded in Britton-Robinson buffer solutions of pH 2-12. The dissociation constants of H2SPT evaluated spectrophotometrically and potentiometrically in a 5% (v/v) DMF-water mixture are concordant. The dc-polarograms in solutions of pH < 8.5 exhibit a single 4-electron diffusion-controlled polarographic wave, whereas in solutions of pH > 8.5 two waves are observed. The cyclic voltammograms give a single cathodic peak in acidic and neutral solutions, whereas two cathodic peaks can be identified in alkaline ones. An electrode mechanism is proposed and discussed. The effect of temperature on the dissociation constants and the polarographic data was also investigated; the corresponding thermodynamic parameters were derived and are discussed.

The d.c. electrical conductivity (sigma) and the relative permittivity (epsilon) were accurately measured as a function of temperature in the range 300 < T < 450 K for ammonium oxalate monohydrate (AOX), (NH4)(2) C2O4H2O and potassium oxalate monohydrate (POX), K2C2O4H2O. Differential thermal analysis (DTA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) from 300 K up to 520 K were also performed for each compound. The data of the electrical parameters combined with the DTA and/or DSC thermograms suggest the existence of a possible change in the electrical conduction at 350 K for AOX and at 355 K for POX. Like most hydrogen-bonded molecules, the charge carriers may be protons and the electrical conduction is therefore protonic. At somewhat higher temperatures, dehydration and/or decomposition takes place in each compound and is reflected as a sudden loss in weight in the TGA plot.

The whole part of Agave kerchovei (Fam: Agavaceae) collected from Orman garden, Giza, Egypt affords compounds 1, 2 and 3. Their structures have been assigned as tigogenin glycosides and sarsapogenin glycoside from spectral analysis. The glycosidic nature is confirmed by acid hydrolysis and identification of the resulting sugars.

A quantum chemical study of the efficiency of some o-, m-, and p-substituted benzohydrazides, cinnamohydrazide, and Schiff bases derived from salcylaldehyde with o- substituted anilines, p-substituted benzaldehydes with 2-aminopyridine and 2-aminopyrimidine, benzaldehyde and cinnamaldehyde with p-phenylenediamine as corrosion inhibitors of steel in the presence of 1M HCl is presented. The AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods were used. A possible correlation between corrosion inhibition efficiencies and structural properties was searched to reduce the number of compounds to be selected for testing from a library of compounds. Quantum parameters, total negative charge (TNC) on the molecule, energy of highest occupied molecular orbital (E-HOMO), energy of lowest unoccupied molecular orbital (E-LUMO), dipole moment (mu), total energy (TE), and linear solvation energy terms, molecular volume (Vi) and dipolar-polarization (pi*) were correlated to corrosion inhibition efficiency of the studied compounds. The results were used to predict the corrosion inhibition of some related aromatic hydrazide derivatives with correlation coefficient r > 0.96.

Purpose - To study the effects of the sodium salts of molybdate, tungstate and monovanadate as well as some derivatives of Neville-Winter acid azo dyes on the corrosion of carbon steel in 3.5 percent NaCl solution. Design/methodology/approach - Open circuit potential measurement and potentiostatic polarization techniques have been used. Findings - It was found that all the compounds had inhibition effects on carbon steel dissolution. Inhibition efficiency (IE) increased with increase in inhibitor concentration. The process of inhibition was attributed to the formation of an adsorbed film on the metal surface, which protects the metal against the corrosive medium. The adsorption of these compounds on the steel/chloride interface was found to follow Freundlich adsorption isotherm behaviour. Originality/value - Proves the effectiveness of the sodium salts of molybdate, tungstate and monovanadate as well as some derivatives of Neville-Winter acid azo dyes on the corrosion of carbon steel in 3.5 percent NaCl solution.

The boundary-layer flow of a power-law non-Newtonian fluid over a continuously moving surface in the presence of a magnetic field B(x) applied perpendicular to the surface has been investigated. An analytical solution is obtained and compared with the numerical solution of the resulting non linear ordinary differential equation. The effects of the Stewart number (N) and the power law-index (n) on the velocity profiles and the skin-friction are studied.

The electronic absorption spectra of bisazo compound[I] derived from 4-4-oxydianiline and ethylcyanoacetate were investigated in organic solvents of varying polarities and buffer solutions of. different pH. The important bonds in the IR spectra and the main H-NMR signals were assigned and discussed. Also, the polarographic behaviour of bisazo compound[I] was investigated in Britton-Robinson buffer series of pH 2-10. The polarograms in acid solution exhibited a single 8-electron, irreversible, diffusion-controlled wave corresponding to the cleavage of the two N=N centers, whereas in alkaline solutions one 4-electron wave is obtained. The cyclic voltammograms give two cathodic peaks in acid and neutral solutions, whereas in alkaline ones a single cathodic peak is observed. The electrode reaction mechanism is suggested and discussed.

In this paper we consider the positive definite solutions of nonlinear matrix equation X + A(star)X(-delta)A = Q, where delta is an element of (0, 1], which appears for the first time in [S.M. El-Sayed, A.C.M. Ran, On an iteration methods for solving a class of nonlinear matrix equations, SIAM J. Matrix Anal. Appl. 23 (2001) 632-645]. The necessary and sufficient conditions for the existence of a solution are derived. An iterative algorithm for obtaining the positive definite solutions of the equation is discussed. The error estimations are found. (c) 2005 Elsevier Inc. All rights reserved.

Two simple and accurate methods are described for the determination of clindamycin hydrochloride. The spectrophotometric method involves the formation of ion pair complex between clindamycin hydrochloride and rose bengal in slightly basic medium (pH 7.5). The colour formed is measured at lambda(max) 555 nm. The conductometric method involves direct titration of the drug rose bengal in an ethanol-water (2:1) (v/v) mixture. The optimum concentration range, precision, accuracy, standard deviation and relative standard deviation for both methods were calculated. The proposed methods were applied to the determination of the drug in pure and capsule forms.

We consider traveling wave solutions of the nonlinear Schrodinger (NLS for short) equation. In this paper by considering the decomposition scheme, we first obtain the exact solutions of the NLS equation for the initial condition without using any classical transformations and then its numerical solutions are constructed without using any discretization technique. The numerical solutions are compared with the known analytical solutions. Its remarkable accuracy is finally demonstrated in the study of some initial values of the NLS equation. (c) 2005 Elsevier Inc. All rights reserved.

Disazo dyes derived from the disodium salt of chromotropic acid and their chelates with metal ions were applied on polyester, polyester/cotton and polyester/wool blend fibres as disperse dyes. The fastness to washing, perspiration, rubbing and light of the resultant dyeings were measured. The bonding of dye or its complexes to the fibre and the effect of substituent groups on the colour fastness of the dyes are discussed.

Hydrothermally synthesized ZSM-5 zeolite modified by manganese (Mn/ZSM-5) or lanthanum (La/ZSM-5) or mixture of both (Mn-La/ZSM-5) using impregnation technique was characterized by powder XRD, FTIR and N-2 adsorption measurements. These materials were tested for discoloration (adsorption) and mineralization (in the presence of UV irradiation) of indigo carmine (IC) dye. The results indicate that MnOx incorporated ZSM-5 that showed the highest lattice volume and pore radius between all samples presented the highest photocatalytic activity, comparatively. However, the Mn-La/ZSM-5 catalyst exhibited the lowest activity even when compared with the parent ZSM-5 sample. This was in part due to evoking of Mn3O4 species at the expense of Mn2O3 ones, which were proposed to be the active sites of the reaction. This reaction was found to be acidity dependent since Mn/ZSM-5 showed significant bands at 3650 and 3619 cm(-1) those in contrast appeared shapely in La/ZSM-5, whereas for Mn-La/ZSM-5 only a band at 3619 cm(-1) was obtained. On the other hand, the decolorization activity showed comparable high rates for Mn/ZSM-5 and Mn-La/ZSM-5 samples (100% removal) implying that the adsorption process is more referred to acid-base site pairs where the photocatalytic activity seems to be more restricted to acidic sites. The influence of pH, catalyst amount and time on the decolorization rate of IC on Mn/ZSM-5 was thoroughly investigated and correlated with ZPC of MnOx species, various exposed species of MnOx and surface properties. (c) 2005 Published by Elsevier B.V.

Charge transfer complexes of substituted-N-aryl-N-4-(-p-anisyl-5-arylazothiazolyl)thiourea with 2,3-dichloro-5,6-dicyanobenzoquinones (DDQ), chloranilic acid (CHLA), chloranil (CHL), bromanil (BRL) and iodanil (IDL) in methylene chloride were investigated spectrophotometrically to determine association constants (K), molar extinction coefficients (epsilon) and stoichiometric ratio. The effect of thermodynamic parameters (Delta G* and Delta H) on the stability of the complexes are discussed and the transition energy (E) of the CT complexes are reported. The solid CT complexes of the substituted-N-aryl-N-4-(-p-anisyl-5-arylazothiazolyl)thiourea with the above acceptors have been prepared and investigated by IR, electronic, H-1 NMR and ESR spectroscopy. Nonacidic acceptors yield complexes having pi-pi* and n-pi* bonding. Acidic acceptors yield complexes having pi-pi* and proton transfer interaction. The formation of 1:2 (D:A) complexes is also ascertained. (C) 2005 Elsevier B.V

Charge-transfer molecular complexes of some 2-aryl-4-arylidene-5(4) oxazolanes with di- and trinitrobenzene have been studied at 25 degrees C. The stoichiometry and apparent formation constants of the complexes formed were determined by applying the conventional continuous variation method. The role of the molecular structure of the electron donor and acceptor compounds as well as the nature of the solvent on the formation of such charge-transfer complexes. Furthermore, association constants, oscillator strength, dipole moment, and free energy are elucidated. (C) 1995 Academic Press, Inc.

Extraction of phenolic compounds of grape leaves after flavour extraction has been studied. Fractionation of these compounds was done using thin-layer and column chromatography and the compounds were identified by NMR analysis. A remarkable variation in the concentration of these phenolic compounds of all the varieties was observed, when subjected to flavour extraction.

A new modified spectrophotometric procedures are presented for the determination of three pharmaceutical antibiotic compounds through chage-transfere complexation reaction with chloranil. The complex shows an absorption mAxima at 550 nm, having a molar absorptivity coefficient of 5.55x10(3),7.81x10(3) and 1.38x10(4) 1. mol(-1)cm(-1) for ampicillin, amoxycillin and neomycin, respectively. Optimization of the reaction conditions has been investigated. Obediance to Beer's law (40 mu g/ml) permitted the assay of thes drugs in its dosage forms. A variety of pharmaceutical dosage forms containing ampicillin, amoxycillin and neomycin are successfully analysed by the proposed procedure.

The Al-13-phosphatoantimonic acid Al-13-Sb3P2O14.x H2O has been prepared starting from K3Sb3P2O14 Thermal behaviour has been studied using TGA and DTA. pH titration curves of Al-13-phosphatoantimonic acid with alkali hydroxide solutions (Na+, K+ and Li+) shows a very promising ion exchanger. However, the capacities of the alkali metal were 4.08, 4.32 and 7.2 meq/g for Li+, Na+ and K+ respectively.

The kinetic studies of exchange of Na+ and K+ on cerium phosphate was studied In alkaline solutions under particle diffusion controle. The effective diffusion coefficient and activation energy have been evaluated. The entropies were calculated and found to be -13.9 and -22.0 J mol(-1) K-1 for Na+ and K+, respectively.

The inhibitive effect of the natural juice of onion bulb on the corrosion of zinc in HCl solution was determined using hydrogen evolution and weight loss measurements as well as potentiodynamic polarization technique. Potentiodynamic anodic polarization was used to determine the effect of the juice on pitting corrosion of zinc in NaCl solution. It is found that the presence of onion juice reduced markedly the corrosion rate of zinc in the acid solution. The inhibition efficiency increases as the juice concentration is increased. Moreover, the presence of the juice in NaCl solution shifts the pitting potential toward more positive direction. The inhibitive effect of onion juice is discussed on the basis of adsorption of its components on the metal surface. Such adsorption is found to follow Langmuir adsorption isotherm. Negative values were obtained for the energy of adsorption indicating the spontaneity of the adsorption process. The formation of insoluble complexes as a result of interaction between zinc cations and S-(1-propenyl)-L-cysteine sulfoxide, which is present in the juice, is also discussed.

Azide 3 was prepared from the corresponding acid chloride 2. The base catalyzed decomposition with aromatic amines, aminobenzoic acids and/or hydrazines afforded the corresponding anilides 4a-f and/or hydrazides 5a-d via azido group displacement. Compounds 5c and 5d were refluxed in Ac2O to give 1,3,4-oxadiazole derivatives 6a and 6b. Lewis acid catalyzed decomposition of azide 3 with anhyh. AlCl3 in dry aromatic substrates gave the corresponding ketones 7a-c. Also, the reaction of azide 3 with glycine gave 9.

High-current discharge is studied between two electrodes where the filling medium is a mixture of methanol and air. Combustion is ignited by a 52 U discharge between two T-shaped electrodes. The combustion device consists of a 52 U capacitor bank, a discharge and combustion chamber and diagnostic systems. Current disruption has been observed at the moment of a change between the capacitive and inductive discharges. This has been referred to plasma expansion and termination when there is no voltage between the electrodes. The disruption time increases with an increase in the charging voltage. The kinetic pressure of combustion has shown three different behaviours. The first type is similar to partial fuel normal combustion. The second type is complete normal combustion. The third type is fast plasma combustion which results when an exponential pressure decay due to the heat transport process, very low heat losses and the short rise time of the kinetic pressure is obtained.

2-Aryl-1-oxaspir(2,5)octa-4-ones Ia,b were synthesized and reacted with thiourea in ethanol to give hydroxy cyclohexanone derivatives IIa,b. Compounds IIa,b were readily cyclised into the corresponding 5-hydroxy quinazolines IIIa,b and their dehydrated derivatives IVa,b. A mixture of compounds III and IV were also prepared directly from the reaction of compounds Ia,b with thiourea in alkaline medium. Compounds Va,b were produced by reduction of corresponding IV. Compounds III or and V reacted with chloroacetic acid to give resp. VI and VIII which condensed with aromatic aldehydes to form resp, VIII and IX.

We used two simple control laws based on linear velocity and quantic feedback to suppress the high-amplitude vibrations of a structural dynamic model of the twin-tail assembly of an F-15 fighter when subjected to harmonic resonance excitations. We developed the nonlinear differential equations of motion and obtained an approximate solution using the method of multiple scales. Four first-order equations governing the amplitudes and phases of the response were derived. Then, a bifurcation analysis was conducted to examine the stability of the system and investigate the performance of the control laws. The theoretical findings indicate that the control laws lead to effective vibration suppression and bifurcation control. The results show that both laws are effective at suppressing the vibrations. To compare the performance of both techniques, we calculated the power requirements for a simple system.

The two-dimensional Laplace integral transform technique has been applied to get the temperature distributions in the molten and the solid parts of a semi-infinite target irradiated with a pulsed laser. Formulas for the time dependence of the evaporated part and the molten layer thicknesses of the target were found considering the temperature dependence of the absorption coefficient of the irradiated surface as well as the chemical reaction. As the illustrative example computations were carried out on an aluminum target. (c) 2004 Elsevier Ltd. All rights reserved.

The Lie group method is applied to make a group classification of the PDE governs the dispersion of gaseous pollutants in the presence of a temperature inversion and obtained on a great varity of analytical solutions. The pollutants are assumed to be spread in the layer bounded by the ground surface and the inversion level and they are driven by wind in the horizontal direction. The general solution has been specified for two cases; (i) the ground absorbs all the gaseous pollutants and (ii) the ground does not absorb any pollutant. (c) 2005 Elsevier Ltd. All rights reserved.

A new simple and sensitive spectrophotometric procedure for the determination of sulfacetamide sodium (I), sulfadiazine (II), sulfadimidine (III) and sulfathiazole (IV) is based on the reaction of the drug with acetylacetone-formaldehyde reagent to give a yellow product having lambda(max) at 400 nm. Optimization of the reaction conditions has been investigated. A linear correlation was obtained between absorbance at lambda(max) and the concentration. The Beer's law limits of I, II, III and IV are 4-80, 4-72, 4-60 and 4-80 mu g/ml, respectively. For more accurate results, Ringbom optimum concentration ranges were evaluated to be 6-76, 8-66, 6-56 and 8-75 mu g/ml for I, II, III and IV, respectively. The molar absorptivities and Sandell sensitivities for all sulfa drugs under consideration were evaluated. Relative standard deviations of 0.98, 1.07, 0.86 and 0.79% were obtained for I, II, III and IV, respectively. The method has been compared to the official method and found to be simple, accurate (t-test) and reproducible (F-test). The developed procedures were applied for bulk sulfa drugs and some of their dosage forms without interferences from additive and common prescribed drugs.

A simple, rapid and sensitive spectrophotometric method is proposed for the determination of cephadroxil (I), cephalexin (II) and cephradine (III). The method is based on ion-pair complex formation between these derivatives and chromotrope 2B (C2B) or chromotrope 2R (C2R), to give a highly coloured radical anion. The coloured products are quantified spectrophotometrically at 542 and 564 nm for C2B and C2R, respectively. The optimization of the experimental conditions is described. The method has been used for the determination of 0.4-15, 0.4-14 and 0.4-18 mu g/ml of drugs I, II and III, respectively. The accuracy of the method is indicated by the excellent recovery (100.0 +/- 1.7%) and the precision is supported by the low relative standard deviations less than or equal to 1.5%. The sensitivity of the method is discussed and the results are compared with the official method. The interference from common degradation products and excipients was also studied. The proposed method was applied successfully to the determination of the different cephalosporins in dosage forms, with good precision and accuracy. The results were compared with those given by the official B.P. 1993 method.

Sodium 1-[4-amino-5-mercapto-4H-(1,2,4)triazol-3-yl]heptadecane-1-sulfonate 2 has been used as a new precursor to Synthesize Some important biologically active heterocycles. Reaction of 2 with carbon disulphide in pyridine and acid chlorides yields the 1,2,4-triazole derivatives 3, 4a and 4b. Condensation of 2 with appropriate aldehydes gives 5a-c which have been cyclized by treating with thioglycollic acid to yield ha-c. Reactions of ? with phthalic anhydride and 4-metlylbenzenesulfonyl chloride gives 7 and 8. In addition, the reaction of 1, 2 with chloroacetaldehyde, phenacyl bromide, urea anti chloroacetyl chloride yields 9, 10, 11 and 12, respectively. On the other hand, refluxing, 2 with phenyl isothiocyanate gives 13 and 14. All these products have antimicrobial activity and they can be used as surface active agents.

The Reynolds equation for misaligned radial face seals coning is solved numerically, and the squeeze effects on the separating forces and tilting moments are studied. Also, the variations in the seal characteristics with eccentricity, thin film thickness and radius ratio are presented. ne numerical results for the forces and moments are given in nondimensional form.

1,3-Diaryl-2-Propen-1-one reacted with thiourea in the presence of sodium ethoxide to furnish 4,6-diarylpyrimidine-2(1H) thione (2) under bar. The behaviour of (2) under bar towards nitrogen nucleophiles, and carbon electrophiles under Michael reaction conditions have been investigated. The oxidation of the thione (2) under bar gave the corresponding disulphide derivative . Acylation of (2) under bar yielded the corresponding S-acetyl- and N-benzoyl- derivatives, respectively.

The convergence of the matrix Hartree-Fock energies of Li+, H- and LiH prototype systems and electron correlation energies of LiH are studied when a systematic procedure for the construction of even-tempered basis sets of primitive Gaussian type functions of s-symmetry is employed. It is shown that an accuracy approaching the sub-mu Hartree level can be achieved for the total energies of Li+, H- and LiH within the Hartree-Fock approximation. While an accuracy approaching the sub-mu Hartree level can be achieved for the total energy of LiH within the Moller-Plesset perturbation level, an accuracy approaching the mu Hartree level can be achieved within the configuration interaction level. The Hartree-Fock energies of LiH approach the saturation faster than do the electron correlation energies. The convergence of Moller-Plesset perturbation series was basis set size dependent, but the convergence rate and the related Pople approximation were basis set size independent.

We obtain a complete classification of all possible nontrivial similarity solutions of the Free Kramer equation, together with a necessary and sufficient condition for each type to be reduced to a heat equation. A confluent hypergeometric solution of the free Kramer equation is derived by some classes of similarity solutions.

Xylenol orange is proposed as new sensitive reagent for the colorimetric determination of selenium and tellurium. The reagent forms a pink colored radical cation with selenite and tellurite instantaneously at room temperature in slightly acidic medium. The pink species exhibits an absorption maximum at 568 and 569 nm with a molar absorption coefficient of 2.69 x 10(4) and 2.82 x 10(4) 1 mol(-1) cm(-1) and Sandell sensitivity of 2.94 and 4.52 ng cm(-2) for selenite and tellurite, respectively. A 10-fold molar excess of the reagent is necessary for the development of the maximum color intensity. Beer's law is obeyed over the concentration range 0.10-5.50 and 0.13-6.38 mu g ml(-1) of selenium and tellurium, respectively with an optimum concentration range of 0.35-5.10 and 0.40-6.00 mu g ml(-1), respectively using Ringbom method. The effects of acidity, time, temperature, order of addition of reagent, reagent concentration and the tolerance limit of the method towards various cations and anions usually associated with. selenium and tellurium are reported. The proposed method is extremely sensitive, reproducible and has been satisfactorily applied to the determination of trace amount of selenium in polluted water, plant material and medicated shampoo.

A simple, rapid and sensitive method for the determination of betamethasone (I), dexamethasone (II) and hydrocortisone (III), either in the pure form or in pharmaceutical formulations is described. Tile method is based on the development of a brown product with indophenol in basic aqueous-ethanolic (50% v/v) medium. The optimum reaction conditions for the charge transfer complex formed were assessed. The absorbance measurements were made at 820, 816 and 822 nn for I, II and III respectively. The calibration graph was linear in the range 1-26, 1-32 and 1-35 mu g/ml of I, II and III with slopes of 0.028, 0.021 and 0.024, respectively. For more accurate analysis, Ringbom optimum concentration ranges were 2.5-23.0, 3.0-28.5 and 3.0-33.0 mu g/ml for I, II and III, respectively. The precision of the procedure was checked by calculating the relative standard deviation of ten replicate determinations on a sample containing 20 mu g/ml for each drug and was found to be 1.67, 1.39 and 1.85% for I, II and III, respectively. Many common excepience and common drugs present in their dosage forms do not interfere, and the tolerable levels were evaluated. Results of analysis of pure drugs and their dosage forms by the proposed method are in good agreement with those of the British Pharmacopoeia 1993 procedure.

The probability of deuteron formation resulting from the interaction of high energy protons with nucleons, light nuclei (CNO) and heavy nuclei (Ag, Br) is discussed. The proportionality of the identified deuterons and protons (produced at the same angle due to the same interaction) agrees with that of the Butler and Pearson model which owes the deuteron formation to the average nuclear interaction seen by the cascade nucleons within the nucleus and then the normal n-p interaction. The data are based on the momentum and angular distributions of the outgoing particles.

We consider the way in which a solution to a class of nonlinear partial differential equations S(u)u(t)=(K(u)u(x))(x) approaches the similarity form. The problem we solve is chosen for two main reasons: first the equation above is of widespread use in modeling physical situations and second it provides a tractable but significant example of a free boundary problem.

The isothermal, stationary and isochoric flow of a fluid of grade two between a pair of rotating eccentric spheres is investigated. The equations of motion of first and second order are formulated and solved for the first order only. However, the equation of second order indicates the presence of secondary flow. The stress distributions are computed and used to determine the resultant forces and torques acting on the stationary outer sphere. An important result For rheometry is that the resultant torques can be used to determine the coefficient of viscosity, while the resultant force in the direction of the axis of symmetry may be employed to determine the second normal stress difference.

N-Methylacryloyloxytetrabromophthalimide (NMTP) monomer was prepared and studied by elemental analysis and IR, H-1 NMR and UV-vis spectroscopy. The effect of solvent on UV-vis spectra is considered. Complexes of (NMTP) with Cu(II), Co(II), Ni(II), Zn(II) and Fe(III) chlorides have been studied. The equilibrium constants (K-c) of some metal ions, molar extinction coefficients (epsilon), ionization potential (IP), the stoichiometry and foreign ions are determined, The solid complexes have been prepared and investigated by elemental analysis, IR, UV-vis and ESR spectroscopy to elucidate the structural configuration.

An analysis of momentum characteristics of the backward emitted shower particles has been performed using interactions of 4.5 A GeV/c C-12 and Si-28 With emulsion. These data have been compared with the corresponding ones in the forward hemisphere. The average values of momentum and transverse momentum in the backward and forward hemisphere are (P-b) = 182 +/- 11, (P-b) = 68 +/- 4, (P-f) = 720 +/- 10 and (P-l(f)) = 280 +/- 20, respectively. The transverse momentum distributions have been compared with Hagedorn's distribution and the corresponding temperatures have been deduced to be T-b = 27.2 +/- 1.6 and T-f = 112.0 +/- 5.6. The momentum distribution of shower particles emitted in the backward hemisphere has an exponential form with slope parameter T-0 = 46 MeV/c.

The synthesis of N-acryloyloxytetrabromophthalimide was accomplished in fair yield by the reaction of acryloyl chloride with N-hydroxytetrabromophthalimide in the presence of triethylamine. Following polymerization of the monomer, exchange reactions of the resulting polymer with amines, amino acids, alcohols, phenols and hydroxybenzoic acids were studied.

A new simple, accurate, precise and sensitive indirect method for the determination of chloropheniramine maleate (CPRM) and chlorophenoxamine HCl (CPX HCl) using atomic absorption spectrometry has been developed. The method is based on precipitation of the ion associates formed by the reaction of CPRM or CPX HCl with ammonium reineckate and/or sodium cobaltinitrite. The solubility of the solid complexes at the optimum conditions of pH and ionic strength values have been studied. Saturated solutions of each ion-associate were prepared under the optimum conditions and the metal ion-content in the supernatant was determined. The solubility products were thus calculated at different temperatures and the thermodynamic parameters Delta H, Delta G and Delta S were determined. The method has been used for the determination of 15.6-156.4 and 13.6-136.1 mu g/mL of CPRM and CPX HCl, respectively using ammonium reineckate and 23.4-234.5 and 20.4-204.2 mu g/mL, using sodium cobaltinitrite. The method developed was applied for analysis of bulk drugs and some of their pharmaceutical preparations.

Cyclic voltammograms and potentiodynamic anodic polarization curves were obtained for Incoloy 800 and 316 stainless steels in varying concentrations of NaCl. The integrated charge amounts, q(a), in presence of Cl(-)ions was taken as a measure of the extent of pitting corrosion while the difference in values between pitting potential and protection potential (E(pit) - E(pp) was taken as a measure of pit repassivation ability. The pitting potential varies with the logarithm of Cl(-)ion concentrations according to sigmoidal - S - shaped curves which were explained on the basis of formation of passivitable, limiting active and continuously propagated pits depending on the concentration of Cl(-)ions. 316 stainless steel was found to have higher resistance to pitting corrosion than Incoloy 800. This was attributed to the presence of Mo in the former, addition of CrO42-, NO2-, VO3- and SiO42- to Cl- medium causes inhibition of pitting corrosion of bath alloys. The percentage inhibition efficiency (PIE) calculated from the change of the anodic charge (q(a)) in the absence and presence of inhibitors decreases in the order: CrO42- > NO2- > SiO42- > VO3-.

The charged-particle multiplicities produced in inelastic interactions of O-16 ions at 3.7 and 60A GeV with emulsion nuclei are investigated and compared with theoretical predictions. Results from the interaction with CNO and AgBr target nuclei are analysed in terms of negative binomial (NB) distribution. Data from other nucleus-emulsion collision experiments have been used to fit an empirically proposed relationship for the average value of total charged multiplicity as a function of the geometrically determined number of interacting nucleons.

A simple and selective method for the determination of erythromycin and its stearate and succinate esters in their pure forms and in pharmaceutical formulations is described. The procedure is based on the formation of a blue-coloured (lambda(max) = 633 nm) complex with gentiana violet in alkaline medium. Different variables affecting the colour development were studied and optimized. The method was used to determine 2.5-25 mu g ml(-1) of erythromycin in the final measured solution. The simplicity of the method permits rapid analysis and it is thus suitable for routine control. The method is highly specific for the determination of stearate and succinate esters in pharmaceutical formulations. The reliability of the method was established by parallel determinations against the official British Pharmacopoeial method.

A comparative study of the reaction of La(III), Sm(III), Eu(III) and Gd(III) with some aryl Schiff bases has been carried out using polarographic and spectraphotometric methods. The optimum conditions for the determination of 1.39-20.84, 1.50-22.56, 1.52-22.80 and 1.57-23.59 mu g/ml of La(III), Sm(III), Eu(III) and Gd(III), respectively has bees studied. The proposed methods show an average recovery of 98.20% with standard deviation not exceeding +/- 0.058 indicating their reproducibility and sensitivity.

Converged Hartree-Fock and frequency calculations of molecular hydrogen were obtained when a systematic procedure for constructing basis sets of primitive Gaussian type functions with s-, p-, d- and f-symmetry was employed.

The interaction characteristics of 400 GeV protons with emulsion nuclei were studied and discussed. The multiplicity distributions of secondary charged particles have been measured for 480 inelastic events and are compared with the results obtained in p-emulsion (P-Em) collisions at different energies. The integral distribution of the number of disintegrated particles from the target nuclei N-h is used to separate the number of the inelastic interactions of proton with light (CNO) and heavy (AgBr) nuclei in the emulsion. The interaction characteristics of protons (400 GeV) with different groups of target nuclei have been investigated. Copyright (C) 1996 Elsevier Science Ltd

The visibility of the speckle pattern resulting from the scattered radiation of transmitted beams through a diffusing surface has been studied for a Gabor hologram and speckle photography. The cases of strictly- and quasimonochromatic light ave also considered. Mathematical expressions for the dependence of the visibility on the distance from the centre of the undiffracted illuminating beam, its spectral half-width Delta f and the amplitude ratio m between the reference beam and the integrated scattered beams ave obtained. A graphical method is found for determining m and Delta f from the visibility as a function of the distance from the centre of the undiffracted illuminating beam. Copyright (C) 1996 Elsevier Science Ltd.

beta-Aroylacrylic acids react with thiophene in boiling benzene to give alpha-(2-thienyl)-beta-aroylpropionic acids (1a-c). The reactions of 1c with hydrazine hydrate, hydroxylamine hydrochloride, semicarbazide hydrochloride, aromatic aldehydes, and acetic anhydride yield pyridazinone 2, oxazinone 3, semicarbazone 4, arylidene propionic acids (5a-c) and furanones (6a-c), respectively. The reactions of compound 6c with some nitrogen nucleophiles and aromatic hydrocarbons under Friedel Crafts' conditions have also been discussed.

Proton-ligand and metal-ligand stability constants of the o- phenylinediamine Schiff base derived from o-acetoacetylphenol with some transition metal ions (Cr3+, Fe3+, Co2+, Ni2+, Cu2+ and Cd2+ were determined potentiometrically in PO % (v/v) ethanol-water medium at three different temperatures (298, 308 and 318 K). The order of stability constants of metal complexes was found to be Cr3+ > Fe3+ > Co2+ > Ni2+ > Cu2+ > Cd2+ which was in a good agreement with Irving-Williams order. The thermodynamic parameters Delta G, Delta H and Delta S were calculated and discussed. The results of stability constants were also calculated and confirmed spectrophotometrically in 30 % (v/v) ethanol-water medium using universal buffer solutions. The stoichiometric ratios of (M:L) were determined spectrophotometrically and confirmed conductometrically.

The behaviour of codeine reineckate and codeine tetraphenylborate membrane electrodes has been observed with a respective Nernstian response of 58 and 56 mV/decade for 9.3 x 10(-5)-1.3 x 10(-3) M codeine sulfate solutions. The working pH ranges were 5-8 and 4-8, respectively. The selectivity towards sugars, amines, amino acids, cations, and some pharmaceutical compounds was found to be satisfactory. The isothermal temperature coefficient was 0.0014 V/degrees C. The electrodes were applied successfully for the determination of codeine in some pharmaceutical dosage forms with a relative standard deviation range of 0.16-0.30% and an average recovery of 98.6 +/- 0.6%.

2-Amino-5-[6-(dibenzothien-4-yl)-4,5-dihydropyridazin-3-yloxymethyl]-1,3,4-thiadiazole (2) has been synthesised by treating thiosemicarbazide with the acid 1. The amine (2) on treatment with aromatic aldehydes furnishes schiff bases of thiadiazoles (3a,b) which on reaction with thioglycollic acid yield 4-thiazolidinone derivatives (4a,b). Reaction of 2 with phenyl isocyanate and phenyl isothiocyanate give the corresponding aminocarbamide and aminocarbothiamide derivatives (6 and 7), respectively, which on reaction with malonic acid in acetyl chloride afford baribituric and thiobarbituric acid derivatives (8a,b), respectively. However, reaction of carbon disulphide and methyl iodide with 2 give dithiocarbamidate derivative (9) which on treatment with o-phenylenediamine and ethylenediamine give 10 and 11, respectively.

Complexes of La3+, Ce3+, Nd3+, Th4+ and UO22+ with some derivatives of o-hydroxyphenylazo-1-methyl-3-phenyl-2-thiohydantoin have been investigated in solution by using spectrophotometric and conductometric titration methods. The composition of the complexes was determined to be 1:1 and 1:2 (M:L). The optimum conditions favouring the formation of the coloured complexes were studied extensively and their stability constants determined. Adherence to Beer's law was observed for the ppm concentration range. Spectrophotometric titration methods for La3+, Ce3+, Nd3+, Th4+ and UO22+ with EDTA in the presence of the ligand as an indicator are reported as are interferences by several metal ions. The solid complexes have been characterized by elemental analyses, thermal methods (DTA and TGA), IR and solution H-1 NMR spectra.

Saccharinyl benzoic acid azides 2a-c were used to synthesize a number of noncondensed heterocyclic systems. Thus azides 2a or 2c reacted with glycine to give 1,3-oxazolin-5-one derivatives 3a and 3b. However azide 2b reacted to give diaryl urea derivative which was easily cyclized to give imidazol -2,5- dione (6). Also azides 2a-c reacted with glycolic acid to give 1,3-oxazolin -2,5-dione derivatives (7a-c) and with aroyl hydrazines to give the corresponding hydrazides (8a-f) which were cyclized to 1,3,5-oxadiazole derivatives (9a-f).

The spectroscopic behaviour of some quinoline azo dyes has been studied. A simple, rapid, accurate, and sensitive method for the spectrophotometric microdetermination of Ag(I) ions using the title compounds is given. The conditions for the formation of the coloured complexes are obeyed up to 26 mu g . ml(-1); the optimum concentration range for application of the Ringbom method is 2.5-23 mu g . ml(-1). The molar absorptivity and the Sandell sensitivity have also been calculated. The method proved to be successful in determining Ag+ in photography fixing solutions. The results agreed satisfactorily with those obtained using standard atomic absorption spectroscopy.

A simple, rapid and accurate colorimetric method is proposed for the determination of tannins, based on the reduction of tetrazolium blue in alkaline medium by tannins at 90 +/- 2 degrees C for 15 min, leading to the formation of a highly coloured formazan derivative. Absorbance measurements were made at 527 nm and the calibration graph was linear for 0.2-9.0 mu g/ml of tannic acid. For more accurate analysis, the Ringbom optimum concentration range was found to be 0.5-8.2 mu g/ml. The relative standard deviation for the determination in a tea sample containing 7.55% tannins was 1.65%. Most of the ingredients commonly found in tea samples do not interfere with the determination. Several tea samples were analysed using the proposed method.

The dc polarographic behavior of metronidazole is studied in McIlvaine buffers. The reduction is irreversible and exhibits two waves; the first is suitable for analytical purposes. The limiting current shows a linear dependence with the drug concentration in the range 0.02-1 mM. A new polarographic method is examined for determination of metionidazole in commercial tablets and human urine. (C) 1997 Academic Press.

A simple, sensitive, accurate and rapid spectrophotometric method for the determination of some anthelmintics that are used in veterinary medication is described, based on the formation of an ion pair complex with bromocresol purple (BCP) and bromocresol green (BCG). Drugs analyzed are piperazine hexahydrate, tetramisole hydrochloride and metronidazole. The drugs were determined either in pure powdered forms or in pharmaceutical formulations using the standard addition technique. The sensitivity, precision and accuracy of the method was discussed and the results compared with the official method of British Pharmacopoeia (B.P. 1993).

A d.c. polarographic study has been carried out on the complexes of Co(II), Ni(II) and Zn(II) with procaine in NH4Cl (0.6 M)/borax (0.07 M) buffer solution of pH 8.2. The data obtained indicate that the reduction of Co(II) and Ni(II) ions occur irreversibly in the presence of the chelating agent. The kinetic parameters (alpha n and K(f,h)degrees) Of the two complexes were calculated. The study of Zn(II) complex shows a reversible reduction as indicated from the logarithmic analysis. The formed complex is (1:1) (metal:ligand), its formation constant was determined (log K=4.2 +/- 0.07).

A number of novel quinazolines and annulated quinazolines 4-11 are obtained via the nucleophilic interaction of 2-alkyl-4H-3,1-benzoxazin-4-one 3 with different nitrogen nucleophiles. Hydrazinoquinazoline 11 is used for the synthesis of other quinazoline derivatives 12-14 through the reaction of different reagents. The antimicrobial, surface active properties and the biodegradability of some of the synthesized compounds are described.

The use of sodium 1-(4-amino-5-mereapto-4H-[1,2,4] triazol-3-yl) And heptadecane-l-sulfonate (2) as new precursors to synthesize some important, biologically active heterocytes has been found to be effective. The reaction of 2 with carbon, disulphide in pyridine and acid chlorides yielded the 1,2,4-triazole, derivatives 3, 4a and 4b. The condensation, of 2 with appropriate aldehydes gave 5a-c which were cyclized by treating with thioglycollic acid to yield 6a-c. The reactions of 2 with phthalic anhydride and 4-methylbenzene-sultonylchloride gave 7 and 8. In addition., the reaction of 2 with chloroacetaidehyde, phenacyl bromide, urea and chloroacetyl chloride yielded 9, 10, 11 and 12. At the same time, refluxing 2 with phenyl lsothiocyanate gave 13 and 14. All these products have antimicrobial activity and they can be used as surface active agents.

Cationic surfactant, cetylpyridinium bromide (CPB), sensitizes the colour reaction of cerium(IV) with 1,3-o-hydroxyphenyl-5-phenylformazan(I), 1-m-hydroxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(II) and 1-m-carboxyphenyl-3-o-hydroxyphenyl-5-phenylformazan(III). The formation of a soluble ternary complex of stoichiometric ratio 1: 1: 1 (Ce(IV)-R-CPB) is responsible for the observed enhancement in the molar absorptivity and Sandell sensitivity of the formed complex, when a surfactant is present. The ternary complex exhibits absorption maxima at 596, 571 and 607 nm (epsilon = 6.05 x 10(4), 6.28 x 10(4) and 8.06 x 10(4) L mol(-1) cm(-1)) using triphenylformazan derivatives 1, 11 and 111, respectively. Beer's law is obeyed between 0.15 and 2.5 mu g ml(-1), whereas, optimum concentration range applying Ringbom method is in the range 0.30-2.25 mu g ml(-1). Conditional formation constants in the presence and absence of CPB for Ce(IV) complexes have been calculated. The proposed method has been successfully applied to the analysis of magnesium-base cerium alloys and synthetic mixtures corresponding to various cerium alloys. (c) 2005 Elsevier B.V. All rights reserved.

The new bridged diacetato-diamido-diamine-uranyl complex {2[(UO2)(H2N)(H3N)(OOCCH3)]} was prepared and characterized by elemental analysis, IR measurement as well as TG and DTA analysis. The kinetic parameters; activation energy (E-a), pre-exponential factor (A) and the order of decomposition (n) were calculated from TG curves using Coats-Redfern and Flynn-Wall-Ozawa methods. The mechanism of decomposition has been established from TG and DTA data. The data obtained agree quite well with the expected structure and show that the complex finally decomposes to form UO3. A general mechanism describing the formation of bridged complex {2[(UO2)(H2N)(H3N)(OOCCH3)]} is proposed.

The steady flow of an incompressible Oldroyd 8-constant fluid in the annular region between two spheres, or so-called spherical Couette flow, is investigated. The inner sphere rotates with anangular velocity about the z-axis, which passes through the center of the spheres, while the outer sphere is kept at rest. The viscoelasticity of the fluid is assumed to dominate the inertia such that the latter can be neglected in the momentum equation. An analytical solution is obtained through the expansion of the dynamical variables in a power series of the dimensionless retardation time. The leading velocity term denotes the Newtonian rotation about the z-axis. The first-order term results in a secondary flow represented by the stream function that divides the flow region into four symmetric parts. The second-order term is the viscoelastic contribution to the primary viscous flow. The first-order approximation depends on the viscosity and four of the material time-constants of the fluid. The second-order approximation depends on the eight viscometric parameters of the fluid. The torque acting on the outer sphere has an additional term due to viscoelasticity that depends on all the material parameters of the fluid under consideration. For an Oldroyd-B fluid this contributed term enhances the primary torque but in the case of fluids with higher elasticity the torque components may be enhanced or diminished depending on the values of the viscometric parameters.

Methotrexate (MTX) is widely used in the treatment of a number of oncological and hematological diseases. Due to its known limitations, MTX is often conjugated with different carriers to obtain amended forms of the drug. In this study, the potential influence of the substitution level (loading ratio) of the dextran T10- and T40-based MTX conjugates (D-MTX) on their properties were investigated in vitro and in vivo. The clear dependence of the in vitro antiproliferative effect on the substitution level was established only in the case of the dextran T10-based preparations (T10-MTX conjugates). Conjugates with the higher substitution level had the lower antiproliferative effect. For the dextran T40-based (T40-MTX conjugates) set no similar relationship was observed in the tested range of substitution levels, nor was any dependence observed between the biological properties of the D-MTX preparations in vivo and their substitution levels. However, the difference between the two conjugates was well pronounced in a multiple-dose schedule, when the advantage of T40-MTX over T10-MTX was cumulative during the prolonged course of administration.

The corrosion inhibition efficiencies of some triazole, oxadiazole and thiadiazole derivatives for steel in presence of acidic medium have been studied by using AM1, PM3. MINDO/3 and MNDO semi-empirical SCF molecular orbital methods. Geometric structures, total negative charge on the molecule (TNC), highest occupied molecular energy level (E-HOMO), lowest unoccupied molecular energy level (E-LUMO), core-core repulsion (CCR), dipole moment (mu) and linear solvation energy terms, molecular volume (V-i) and dipolar-polarization (pi(*)), were correlated to corrosion inhibition efficiency. Four equations were proposed to calculate corrosion inhibition efficiency. The agreement with the experimental data was found to be satisfactory: the standard deviations between the calculated and experimental results ranged between +/- 0.03 and +/- 4.18. The inhibition efficiency was closely related to orbital energies (E-HOMO and E-LUMO) and mu. The correlation between quantum parameters and experimental inhibition efficiency has been validated by single point calculations for the semi-empirical AM I structures using B3LYP/6-31G** as a higher level of theory. The proposed equations were applied to predict the corrosion inhibition efficiency of some related structures to select molecules of possible activity from a presumable library of compounds. (c) 2005 Elsevier Ltd. All rights reserved.

Different types of material powder have been placed at the breach of a coaxial discharge for impulse plasma deposition. The coaxial discharge is powered with a 46.26 mu F, 24 kV capacitor bank. When the discharge takes place at the breach, the powder is evaporated and ionized to form a sheath of its material. The plasma sheath is ejected from the discharge zone with a high velocity to be deposited on a glass substrate. It has been found from scanning electron microscopy analysis that the deposited material is almost homogeneous for ceramic and graphite powders. The grain size is estimated to be of the order of a few microns. To measure the deposited material thickness, a microdensitometer, a laser interferometer and an optical microscope are used. It has also been found that the deposited material thickness depends on the discharge number of shots and the capacitor bank energy

A series of 2,3-diglycosylpyrimidine 4, annelated pyrimidine derivatives, pyrazolo-[3,4-d]pyrimidine 8, ditetrazolo[1,5-a;1',5'-c]pyrimidine 9, 2,9a,10-triazaanthracene 12, thieno-[2,3-d]pyrimidine 14, 9-thia-1,3,5,7-tetraazafluorene-8-one-15, 7-oxa-9-thia-1,3,5-triazafluorene-8-one 16, and 5-oxa-9-thia-1,3-diazafluorene 21a,b derivatives have been synthesized via a sequence of heterocyclization reactions of suitably functionalized 6-[5-(4-bromophenyl)oxazol4-yl]-1,2,3,4-tetrahydro-2-thioxo-4-oxopyrimidine-5-carbonitrile (2) with different electrophiles and nucleophiles. The new compounds were prepared with the objective to study their pharmacological properties.

The aim of the present work is to evaluate possibility of microwave emitted by cellular phone that can elicit cortical spreading depression (CSD) in rat brain and studying the characteristics of the evoked signals. (CSD) was elicited in cerebral cortex of anesthetized rats after exposure to microwave irradiation (935.2-960.2 MHz) from Global System for Mobile communications (GSM) mobile phone. With the microwave output of about 8.5 mW at the antenna - tissue surface (4mm in diameter), CSD was elicited after 50 sec irradiation from the beginning of a received signal to the mobile and after 35 sec irradiation from the beginning of a transmitted signal from the mobile. CSD was elicited in about 90% of experiments after irradiation by both types of signal exposure. The results have shown that slow potential change (SPC) has an amplitude of 4.5 ± 0.75 mV, duration of 1.5 ± 0.5 min and propagated speed of 3 mm/min on the average. The amplitude, duration and behaviour of SPC of the evoked spreading depression were found to be affected by irradiation time and the method of exposure.

The dynamics of dc neon glow discharge is examined by calculating a Lyapunov exponent spectrum (LES) and correlation dimension (D-corr) from experimental time series. The embedding theory is used to reconstruct an attractor with the delay coordinate method. The analysis refers to periodic, chaotic, and quasi-periodic attractors. The results obtained are confirmed by a comparison with other methods of time series analysis such as the Fourier power spectrum and autocorrelation function. The main object of the present work is the positive column of a dc neon glow discharge. The positive column is an excellent model for the study of a non-linearity plasma system because it is nonisothermal plasma far from equilibrium. (c) 2006 American Institute of Physics.

An analytical investigation of the nonlinear vibration of a post-buckled beam subjected to harmonic excitations is presented. The system can be modelled as a nonlinear oscillator with parametric and external excitations having frequencies Omega(1) and Omega(2). The method of multiple scales is used to determine to second order the amplitude and phase-modulation equations. Attention is focused on subharmonic resonances (Omega(1) congruent to 2 omega(0), Omega(2) congruent to 2 omega(0); Omega(1) congruent to 3 omega(0), Omega(2) congruent to 3 omega(0); Omega(1) congruent to 4 omega(0), Omega(2) congruent to 4 omega(0); Omega(1) congruent to 5 omega(0) and Omega(1) congruent to 6 omega(0)) where omega(0) is the natural frequency. Steady-state amplitude for each case is plotted as a function of a detuning parameter showing the influences of the several parameters. Stability is performed on figures by solid and broken lines. There exist multivalued solutions which increase or decrease by the variation of some parameters. The response amplitude is not affected by increasing and decreasing the parameters F-1 and alpha(3) for the cases of subharmonics of order one-half and one-third. The solution loses stability on increasing the parameters alpha(4), alpha(5) and F-1 in the case of subharmonic resonance of order one-fifth and also for decreasing the parameters mu and alpha(4) in the case of subharmonic resonance of order one-sixth.

In this paper, the method of internal resonances in a system of rods under vertical kinematic biharmonic excitation is presented. The elements of the system are connected with articulated joints. The couplings of the elements of the system through internal longitudinal forces, which are parametrical, are taken into account. The analysis of such objects under kinematic excitation may have essential significance in the study of paraseismic phenomena. The fundamental problem is to choose the appropriate model of the described object ( structures, buildings, mechanical devices and mechanisms). The model includes some important properties of the object in the particular situation. The autoparametric phenomena can play an essential role in the processes of destruction of described objects. The equations of motion are obtained from Lagrange's equations and the harmonic balance method is applied. Nonlinear terms appear in the equations of motion. These terms are nonlinear damping and nonlinear inertia and have a geometric nature. The amplitudes of the vibrations in the stationary states of internal resonance are investigated. Plots of the amplitudes against frequency are presented.

The F-A1:T1(+) and F-A2:Ga+ color centers at the low coordination (100) and (110) surfaces of AgCl and AgBr play important roles in laser light generation and color image formation. Double-well potentials at these surfaces are investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the FA-defect site were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the vibrational coupling mode, the impurity cation, the coordination number of the surface ion, the lattice anion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity and optical-optical conversion efficiency. All relaxed excited states of the defect-containing surfaces were deep below the lower edges of the conduction bands of the ground state defect-free surfaces, suggesting that the F-A1:T1(+) and F-A2:Ga+-centers are suitable laser defects. The dependence of orientational destruction, recording sensitivity and exciton (energy) transfer on the impurity cation, the coordination number of the surface ion, and the type of the lattice anion is clarified. The Glasner-Tompkins empirical rule is generalized to include the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The (110) surfaces of AgBr and AgCl were more sensitive than the corresponding (100) surfaces, and AgBr thin film was found to be more sensitive than that of AgCl. On the basis of quasi-Fermi levels, the difference in the sensitizing capabilities between the examined dyes in the excited states was determined. (c) 2005 Elsevier B.V.

A series of amphoteric surfactants; containing alpha-hydroxy ester group and an amino acid residue were prepared with the addition of epoxy derivatives (which were prepared from epoxidation of alkyl methacrylate) to different types of amino acids (glycine, alanine, valine, isoleucine, phenylalanine, tyrosine, serine, threonine, aspartic and anthranific acid). The structures of the prepared compounds were confirmed by infrared spectra, proton magnetic resonance spectra, Mass spectra and elementary analysis. Surface tension, Kraft point, foaming power, critical micelle concentration emulsion and Ca++ stabilities were determined. Antimicrobial activity and biodegradability were also screened.

The effect of some aminopyrimidine derivatives on the corrosion of 1018 carbon steel in 0.05 M HNO3 solution was studied using weight loss and polarization techniques. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor and with decreasing temperature. The addition of KI to aminopyrimidine derivatives enhanced the inhibition efficiency due to synergistic effect. The inhibitors are adsorbed on the steel surface according to Temkin isotherm. Some thermodynamic functions were computed and discussed. It was found that the aminopyrimidine derivatives provide a good protection to steel against pitting corrosion in chloride containing solutions. (c) 2005 Elsevier Ltd. All rights reserved.

The effects of Cl-, NO3- and SO42- aggressive anions on the corrosion and passivation behavior of carbon steel electrode in deaerated 0.50 M NaHCO3 solutions were studied using potentiodynamic anodic polarization and SEM techniques. It was found that the presence of Cl-, NO3- and SO42- anions stimulates the anodic dissolution rate in both the active and the pre-passive potential regions. Moreover, significantly great effects were observed in both the passive and the trans-passive potential regions. Pitting corrosion was observed only in the presence of Cl- anions, while the presence of NO3- and SO42- anions facilitate only passivation by oxygen of water without themselves participating in the cathodic process. Also, it was observed that the effect of NO3- anion, which is a strong oxidizing agent acting "primarily" as stimulator of the cathodic process and then its reaction product acts "indirectly" retarding the anodic process. On the other hand, the effect of SO42- anion, which is a non-oxidizing agent, exerts an "indirect" effect on the cathodic reaction increasing its rate and then "directly" influence on the anodic reaction, retarding it. (c) 2005 Elsevier B.V. All rights reserved.

This paper is the second part and continuation of a paper for the author published in 2003 and investigating initial fuzzy uniform structures. The final fuzzy uniform structures and the final global fuzzy neighborhood structures, for the notions of fuzzy uniform structure and of global fuzzy neighborhood structure introduced by the author and others in 1998 in two separate papers, are characterized. This paper also shows that the expected relations between the final fuzzy uniform structures and the final fuzzy topologies and the final global fuzzy neighborhood structures are indeed true. (C) 2006 Elsevier B.V. All rights reserved.

In this paper, the initial and final L-proximities, for a notion of L-proximity introduced by the author and others in 1998, are investigated. This L-proximity is called L-proximity of the internal type. This paper shows that all initial and final lifts in the category L-PRI of L-proximity spaces of the internal type and hence all initial and final L-proximities of the internal type exist. The expected relation between the initial L-proximities of the internal type and the initial L-topologies, the initial global L-neighborhood structures, the initial L-uniform structures is verified. That is, the L-topology (global L-neighborhood structure) associated with the initial of a family of L-proximities of the internal type coincides with the initial of the family of L-topologies (global L-neighborhood structures) associated with these L-proximities of the internal type. Moreover, the L-proximity of the internal type associated with the initial of a family of L-uniform structures coincides with the initial of the family of L-proximities of the internal type associated with these L-uniform structures. (C) 2006 Elsevier B.V. All rights reserved.

Aqueous solutions of cerium nitrate of increasing concentrations (2.5, 5 and 7.5 wt.% Cc) have been contacted with the components forming Mordenite zeolite; during forming the gel under hydrothermal conditions, for allowing the accessibility of Cc ions to proceed into compensating positions in Mordenite structure. These materials were characterized by the methods of FTIR, XRD, N-2 adsorption and UV-vis diffuse reflectance spectroscopy. The interaction of NO and CO adsorptions; at room temperature, on thermally pre-treated (300 degrees C, 10(-5) Torr, 3 h) as well as pre-reduced (50 Torr, 500 degrees C, 1 h) samples were studied by in situ Fourier transform infrared spectroscopy. XRD and FTIR results indicate that the Ce atoms are mostly present in internal surfaces in Mordenites for 2.5 and 5CeMOR samples whereas for 7.5CeMOR, a decrease in diffusion of Ce to be in compensating positions is perceived; as conceived from lowering the lattice volume, pointing to the presence of discrete amounts of CeO2 (582 cm(-1)) and cerium silicate (Si-O-Ce; 797 cm(-1)) species. All the samples indicate intra-crystalline mesopores as depicted from V-1-t plots particularly the 7.5CeMOR sample that showed the highest wide-pore volume (0.073 cm(3)/g), lowest pore radius (21 angstrom) and thus, revealed the highest S-BET between all samples (363 m(2)/g). UV-vis characterization of 7.5CeMOR sample shows octahedral Cc species (345, 360 and 390 nm) in small clusters inside zeolite channels and most probably originated from cerium silicates having different coordination with NaMOR along with discrete amounts of CeO2 (420 nm) species. CO readily adsorbs on the Ce3+ sites of the pre-reduced 7.5CeMOR catalyst, rather than those on Ce4+, to display minor amounts of carboxylate and dominant amounts of monodentate carbonate that were amenable to decompose to produce CO2 gas (2335 cm-1). On the other hand, the in situ interaction of nitric oxide (NO) gas on the 7.5CeMOR catalyst led to the formation of a series of nitrosyl species: N2O (2240 cm(-1)), NO (1908 cm(-1)), N2O3 (1880 cm(-1)) and (NO)(2s,as) (1844, 1734-1720 cm(-1)). Such nitrosyl complexes were favorably formed on Ce3+ in 7.5CeMOR those exchanged Na ones. (c) 2006 Published by Elsevier Inc.

Three simple, sensitive and accurate spectrophotometric methods have been developed for the determination of dextromethorphan hydrobromide (DEX) and ketamine hydrochloride (KET) in dosage forms. These methods are based on the formation of ion-pair complexes with bromocresol green (BCG), bromocresol purple (BCP), and bromophenol blue (BPB) in acidic medium. The coloured ion-pair products are measured at 419, 409 and 417 nm for DEX and at 417, 408 and 416 nm for KET using BCG, BCP and BPB, respectively. Beer's law was obeyed in the range of 2.0-22 mu g mL(-1) for DEX and 2.0-16 mu g mL(-1) for KET. The composition of the ion-pair was established by continuous variation and molar ratio methods. The proposed methods were applied successfully for the determination of DEX and KET in dosage forms applying the standard addition technique and compared statistically with the official methods. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated.

Sulfated (5 wt.%) TiO2 and non-sulfated TiO2 (rutile) modified by NH4VO3 using incipient wetness impregnation technique to achieve a loading of 2 wt.% V2O5 were thoroughly characterized by means of X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-vis absorption spectroscopy, N-2 sorptiometry, particle size analyzer and pyridine-Fr-IR that was used to investigate the acidity of the samples. Degradation of methylene blue (MB) dye was tested for the effectiveness of the samples. The results revealed that MB degradation was highly improved with V supported on TiO2-SO4 and showed a conversion comprises of 98% after UV irradiation (emitting at 400 nm) for 70 min exceeding that Of SO4 free TiO2 sample (78%) obtained at the same period of illumination. This was due to the large surface area (345 M-2 g(-1)), small crystallites size, reduced band-gap energy and presence of basic sites namely O-2(-) and OH- moieties those take part in the reaction as additional oxidizing agents. The photocatalytic degradation of MB was found to follow first order rate kinetics. More information on the activity, surface texturing, kinetics and TOC removal were well evaluated, compared and discussed for all samples. (c) 2006 Elsevier B.V

The effect of curing temperature on electrical conductivity and microstructure of some blended systems was studied. The electrical conductivity was monitoring prior the cement was mixed with water up to 7 days at temperature 20, 35 and 55 degrees C. Air-cooled slag (AS) and water-cooled slag (WS) restricted the conversion reactions by the preferential formation Of C(2)ASH(8) (stratlingite) compared to that Of C(3)AH(6). The plates Of C(2)ASH(8) are deposited as a thin flaky-plate in the pore system and cover the hexagonal crystals of CAH(10) and C(2)AH(8).

The dependence of spallation neutron production double-differential cross sections on the density of the quantum molecular dynamics potential is investigated in p+Al, Fe, Zr, and Pb reactions at 1.2 GeV. It is shown that the cascade component of the neutron spectra is largely unaffected by the parameters of the density-dependent potential. As for the evaporative part (< 20 MeV), some differences are marked only for Pb. Calculated results with a Skyrme-type equation of state of K=300 MeV reproduce the neutron spectra for the reactions under study.

2-Hydrazono-3-phenylquinazolin-4(3H)-ones 11a-i are shown by N-15 NMR to exist in DMSO solution predominantly as the imino tautomers B and not the amino tautomers A. 2-Hydrazino-benzimidazole derivative 12 and 2-hydrazino-4,6-dimethylpyrimidine derivative 13 were found to exist predominantly as the amino tautomers.

Calculations of the spatial and temporal temperature distributions in the molten layer thickness, the still solid part and in the backward surface of the finite slab were carried out during the irradiation with a pulsed laser. The two-dimensional Laplace integral transform technique has been applied to obtain the mathematical expressions for these temperature distributions and the molten layer thickness as a function of the inciting time. The derivations have taken into account the temperature-dependent absorption coefficient of the irradiated surface and the cooling. As all illustrative example, computations were carried out on a finite aluminum (Al) target. (C) 2008 Elsevier GmbH. All rights reserved.

Seismic-facies analysis and the subsurface tectonic evolution of the Western Sub-Basin (WSB) of the Gulf Of Suez, Egypt, were studied by seismic reflection data of 45 seismic lines. Eight of these lines were selected to illustrate the structural framework and depositional history of the WSB supported by the composition, velocity and vertical seismic profile (VSP) logs of ten wells. The analysis of two way time (TWT) structure-contour maps and rose diagrams revealed that the Miocene strata are dissected by NE-SW trending faults of the Morgan Accommodation Zone (MAZ). North of this zone, a general dip towards the northeast is recognized, south of this zone, the regional dip is towards the southwest. The complex structural framework was the main factor controlling facies changes of the syn-depositional Miocene units along the study area.

A simple, quick, accurate, and sensitive colorimetric method is described for the determination of sildenafil citrate (SLD). The method is based on the reaction of SLD with Congo Red, Sudan 11, and Gentian Violet in buffered aqueous solutions at pH 2.5, 6.5, and 11.0, respectively, to give highly colored soluble ion-associate complex species; the colored products are quantitated colorimetrically at 523, 554, and 569 nm, respectively. The various experimental conditions were optimized. The stoichiometric ratio was found to be 1:1 for all ion associates; the calculated logarithmic stability constants were 8.51, 7.79, and 5.58, respectively. Beer's law was obeyed over the concentration range of 0.2-7.0 mu g/mL, whereas the Ringbom optimum concentration range was 0.4-6.5 mu g/mL. Values for molar absorptivity, Sandell sensitivity, and detection and quantification limits were also calculated. The proposed method was successfully applied to the determination of SLD in Viagra tablets and in serum samples by using the technique of standard additions with mean accuracy values of 100.06 +/- 1.14, 99.87 +/- 0.70, and 99.86 +/- 0.97% for Viagra tablets and 99.88 +/- 0.60, 99.90 +/- 0.90, and 100.24 +/- 0.80% for serum samples, respectively.

The corrosion behavior of nickel, Inconel 600, and Inconel 690 in different concentrations of HCl solutions and its inhibition by clove oil was studied using potentiostatic polarization measurements. As the acid concentration increases, the rate of corrosion increases, indicating that HCl accelerates the dissolution of nickel and its alloys. The inhibition efficiency of the clove oil was found to increase with increase of its concentration. The inhibitive action of this oil was discussed in view of adsorption onto the metal surface. The adsorbed layer acts as a barrier between the metal surface and aggressive solution, leading to a decrease in corrosion rate. The adsorption process follows Langmuir adsorption isotherms. It was found that the clove oil provides good protection to nickel and its alloys against pitting corrosion in chloride-containing solution using potentiodynamic anodic polarization techniques.

The two-dimensional integral Laplace transform technique has been applied to get the temperature distributions in the molten layer, the solid part and in the backward surface of a finite target irradiated with a pulsed laser. Formulas for the time dependence of the evaporated part and the molten layer thicknesses of the target were found. This is accomplished by considering the temperature dependence of the absorption coefficient of the irradiated surface as well as the chemical reaction. As an illustrative example computations were carried out on an aluminum (Al) target. (C) 2008 Elsevier B.V. All rights reserved.

This article investigates the influence of radiation and temperature-dependent viscosity on the problem of unsteady MHD flow and heat transfer of an electrically conducting fluid past an infinite vertical porous plate taking into account the effect of viscous dissipation. The governing equations are converted into a system of nonlinear ordinary differential equations via a local similarity parameter which is taken as a function of time. The resulting system of coupled nonlinear ordinary differential equations is solved numerically using the fourth order Runge-Kutta integration scheme with the shooting method. The numerical results for the velocity and the temperature are displayed graphically showing the effects of various parameters. The results show that increasing the Eckert number and decreasing the viscosity of air leads to a rise in the velocity, while increasing in the magnetic or the radiation parameters is associated with a decrease in the velocity. Also, an increase in the Eckert number leads to an increase in the temperature, whereas an increase in radiation parameter leads to a decrease in the temperature.

Methods for Study of weakly nonlinear continuous systems are discussed. The method of multiple scales is used to analyze the nonlinear response of a relief valve under combined static and dynamic loadings. We determine a second-order approximation to the response of the system for file case of primary resonance. Second, we derive a second-order nonlinear ordinary differential equation that describes the time evolution of a single-mode, the so-called single-mode discretization. Then, We use the Multiple scales method to determine second-order approximate solutions of this equation, thereby obtaining the equations describe the modulations Of the amplitude and phase of the response. We show that the results of the second approach are erroneous. (C) 2007 Elsevier Ltd. All rights reserved.

Three simple, accurate, and sensitive colorimetric methods for the determination of cimetidine (Cim) in pure form, in dosage forms, and in the presence of its oxidative degradates were developed. These methods are indirect, involve the addition of excess oxidant [N-bromosuccinimide (NBS) for method A; cerric sulfate [Ce(SO(4))(2)] for methods B and C] of known concentration in acid medium to Cim, and the determination of the unreacted oxidant by measurement of the decrease in absorbance of amaranth dye for method A, chromotrope 2R for method B, and rhodamine 6G for method C at a suitable maximum wavelength, lambda(max): 520, 528, and 525 nm, for the 3 methods, respectively. Regression analysis of the Beer plots showed good correlation in the concentration ranges of 0.2-4.4 mu g/mL for method A, and 0.2-3.4 mu g/mL for methods B and C. The apparent molar absorptivity, Sandell sensitivity, and detection and quantitation limits were evaluated. The stoichlometric ratio between the drug (Cim) and the oxidant (NBS or Ce(4+)) was estimated. The validity of the proposed methods was tested by analyzing pure and dosage forms containing Cim with relative standard deviation

The inhibition effect of some phenylhydrazone derivatives, namely,.[ ethyl(2Z)-cyano[(4E)-5-oxo-3-phenyl-4-(phenylhydrazono)-1,3- thia-zolidin-2-ylidene] acetate (A), ethyl(2Z)-cyano[(4E)-5-oxo-3phenyl-4-(p-methylphenylhydrazono)- 1,3-thiazolidin-2-ylidene] acetate (B), ethyl(2Z)-cyano[(4E)-5oxo-3-phenyl-4-(o-methoxyphen-ylhydrazono)- 1,3-thiaz-oli-din-2-ylid-ene] acetate (C) and ethyl(2Z)-cyano[(4E)-5-oxo-3-thiazo-lid-in-2-ylidene] acetate (D) on the corrosion of 70Cu-30Zn brass in 2M HCl solution has been investigated using weight loss and galvanostatic polarization techniques. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor and with decreasing temperature. The addition of KI to phenylhydrazone derivatives enhanced the inhibition efficiency due to synergistic effect. The adsorption of these inhibitors on the brass surface obeys Temkin isotherm. Some activated thermodynamic parameters were calculated. The addition of these compounds to the potentiodynamic anodic polarization curves of square- brass electrode in chloride solutions shift the pitting potential to more positive values, indicating an increased resistance to pitting attack .

The flow and heat transfer of an electrically conducting micropolar fluid on a continuously moving porous plate embedded in a non-Darcian porous medium in the presence of a transverse magnetic field and heat generation or absorption has been considered. Ohmic heating and a new model for viscous dissipation are taken into account. The transformed coupled non-linear ordinary differential equations are solved numerically by employing a fourth-order Rung-Kutta integration scheme coupled with the shooting technique. The effects of various physical parameters on the velocity, micro-rotation velocity and temperature are shown graphically. Moreover, the numerical values of the local skin-friction, the local wall couple stress and the local Nusselt number are displayed in a tabular form and axe discussed.

The adsorption properties of Cu, Ag, Ni, and Pd atoms on O(2-), Fand F(+) sites of MgO, CaO, SrO, and BaO (001) surfaces have been studied by means of density functional calculations. The examined dusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. The adsorption properties have been analyzed with reference to the basicity and energy gap of the oxide support in addition to orbital interactions. While the free Ni d(9)s(1) triplet ground state is preserved on adsorption on the O(2-) sites of MgO, CaO, and SrO surfaces, it is no longer preserved on the O(2-) site of BaO. For all adsorbates considered, adsorption is found to be stronger on F(+) sites compared with regular O(2-) sites. While on the O(2-) site, Pd and Ni form the most stable complexes, on the F site, Pd and Cu form the most stable counterparts. On the F(+) site, die single valence electron of Cu and Ag atoms couples with the unpaired electron of the vacancy forming a covalent bond. As a result, the adsorption energies of these atoms on the F(+) site are stronger than those on the F and O(2-) sites. The adsorption properties correlate linearly with the basicity and energy gap of the oxide support in addition to orbital interactions. (C) 2008 Wiley Periodicals, Inc. Int J Quantum Chem 109: 1094-1102, 2009

The Middle Jurassic (Bathonian) rocks of the Ras El Abd area include three main shell concentrations: a molluscan shell bed, the lower rhynchonellid bed, and the upper rhynchonellid bed. Analysis of the taphonomic signatures indicates that: the molluscan shell bed represents a proximal tempestite, the lower rhynchonellid bed corresponds to a primary biogenic concentration sensu [Fursich, F.T., Oschmann, W., 1993. Shell beds as tools in basin analysis: the Jurassic of Kachchh, western India. journal of the Geological Society 150, 169-185], and the upper rhynchonellid bed a proximal storm-flow concentration. The shell concentrations formed below fair-weather wave-base in shallow, relatively high energy environments. (C) 2009 Elsevier Ltd. All rights reserved.

The energy band gap of a series of different sizes of CdSe quantum rods have been determined by STM technique at room temperature. The results confirm that the band gap of CdSe quantum rods (QRs) depends mainly on the width (the dimension of the electron confinement) and only slightly on the length as shown previously in the literatures. The experimental data is compared to that calculated using two theoretical models, the effective mass approximation (EMA) and the semi-empirical pseudopotential method (SEPM). The theoretical values for the energy band gap at varying radius are in agreement with the experimental results within 0.08 eV. (c) 2008 Published by Elsevier B.V.

The synthesis of TiZSM-5 (TiZ) catalysts using acid catalyzed sol-gel method via different molar ratios of tetra-isopropyl orthotitanate [Ti(O-i-Pr)(4)] was thoroughly characterized by inductively coupled plasma optical emission (ICP-OE), X-ray diffraction (XRD), particle size analyzer, N(2) adsorption, pyridine-FTIR and ultra-violet visible (UV-vis) spectroscopy. Liquid phase dehydration of 1-pentanol to di-n-pentyl ether (DNPE) was tested for the catalysts. Characterization of TiZSM-5 catalysts clearly shows that at low loadings (up to 5wt%) titanium atoms were on the inner surface of zeolite layers mainly in tetrahedral environment as conceived from UV-vis (248-260 nm) and IR (960 and 1123 cm(-1)) results besides surface texturing data that showed lower surface areas (524-480 m(2) g(-1)) and pore volumes (0.4955-0.4530cm(3) g(-1)) as compared to the parent (587 m(2) g(-1) and 0.5642 cm(3) g(-1)). A distortion of tetrahedral Ti species was perceived at high-titania loadings (>= 10 wt%) evidencing its existence on zeolite surfaces as a distinctive anatase phase. The catalytic dehydration of 1-pentanol over 5, 10 and 15 wt% TiZ catalysts achieved 70% conversion and 10TiZ showed the highest selectivity (60%) to DNPE. This was due to enhancing Bronsted acid sites, retaining crystallinity, decreased particles size and to the relatively large BET surface area. The effect of temperature (298-523 K), time (4-16 h), titania loadings (2.5-15 wt%) as well as solvent engagement on the selectivity to DNPE was thoroughly investigated. The nano-sized TiO(2) crystals in/on 10TiZ surfaces and zeolite pore volume seem to provide excellent possibilities for diffusion of reactants and products, which of significant importance in heterogeneous catalysis. (C) 2008 Elsevier B.V. All rights reserved.

The role of artificial polarization in two different applications of the title color center, namely optical properties of F-A2:Sr2+ center and adsorbate-substrate interactions, is investigated by using quantum mechanical CI-singles and DFT ab initio methods. Clusters of variable sizes were embedded in the simulated Coulomb field that closely approximate the Madelung field of the host surface, and ions that were the nearest neighbors to the defect site were allowed to relax to equilibrium. The sensitivity of the calculated transition energies (Stokes shifts) of F-A2:Sr2+ center as well as related optical properties, such as optical-optical conversion efficiency, relaxed excited states of the defect-containing surface, orientational destruction of the point defect, recording sensitivity, the Glasner-Tompkins empirical rule, and the artificial polarization were examined. The dependence of NO and ON adsorption energies at RbCl (001) surface on artificial polarization were also examined, and the results were explained in terms of electrostatic potential curves. The coadsorption of NO molecules, and the charge transfer reactions between the NO molecules and the paramagnetic chlorine vacancy on RbCl surface were considered.

In this work, a new theoretical and experimental approach for measuring birefringence of solid materials was described. Dispersions of birefringence Of quartz, calcite crystals and Fortypan sheet were determined in the visible region. The results were compared with other interferometric methods to verify the accuracy of this approach. (c) 2009 Elsevier Ltd All rights reserved..

The radiochemical separation of no-carrier-added cerium from proton irradiated lanthanum was studied by solvent extraction using DEE, TBP and TPPO, the latter reagent being employed for the first time for separation of radiocerium from bulk of lanthanum. Distribution coefficients of cerium and lanthanum were investigated as a function of equilibrium time and concentration of HNO3. A mixture of 0.05M K2Cr2O7 and 0.1M H2SO4 was used as an oxidizing agent to improve the separation efficiency of cerium. A comparative study of the three extractants released that DEE is the best for separation of cerium from bulk of lanthanum oxide. The target was prepared by pressing. The production of Ce-139 of high radionuclidic purity and chemical purity via irradiation of lanthanum oxide target at MGC-20 cyclotron with protons of energy 14.5 MeV is described. The experimental yield was found to be 153 kBq/mu A center dot h.

We present solutions to the problem of waves propagating at an interface between two inviscid fluids of infinite extent and differing densities. The method of multiple scale is employed to obtain a dispersion relation and nonlinear Schrodinger (NLS) equation, which describes the behavior of the system for the fluid interface. The dispersion relation of the model NLS equation is studied. The solutions of the NLS equation are derived analytically by using the complex tanh-function method and the function transformation method into a sine-Gordon equation. Also, diagrams are drawn to illustrate the elevation of the interface, the slip velocity, and the conservation of power. We observe that the elevation of the interface is in the form of traveling quasi-solitary waves that decrease as the wave number increases. We see that the slip velocities also bring a nonlinear and periodic characters. Finally, we observe that the conservation of power is in the form of traveling waves. Also, as the wave number increases, the conservation of power is more accurate in fluctuating around zero.

A novel three-component synthesis of 5-hydrazinoalkylidene rhodanine derivatives starting from aliphatic primary amines, carbon disulfide, and 1,2-diaza-1,3-dienes is described. The reaction proceeds successfully under both solution and solid-phase conditions.

Nickel zinc ferrites, Ni1-xZnxFe2O4 (0.0

The adsorption properties of CO molecules adsorbed on Ni, Pd, Cu and Ag atoms deposited on O(2) , F and F(+) sites of MgO, CaO, SrO and BaO terrace surfaces have been studied by means of density functional calculations and embedded cluster model. The examined clusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. The adsorption properties of CO have been analyzed with reference to the basicity of the oxide support, bond order conservation energy, pairwise and non-pairwise additivity, associative adsorption, electrostatic potentials, and orbital interactions. CO adsorption on an oxide support is drastically enhanced when CO is adsorbed on a metal deposited on this support. A dramatic change is found, and explained, when one compares the CO binding energy to O(2) and F sites. The formation of a strong bond at the support metal interface has a considerable consequence on the metal-CO binding energy. The binding of CO is dominated by the metal-CO pairwise additive term, and the non-additivity term increases with increasing the basicity of the support. While the classical contributions to the electrostatic interactions are quite similar for the deposited metals, they are quite dissimilar when going from defect-free to defect-containing surfaces. The adsorption properties correlate linearly with the basicity and energy gaps of the oxide support where the electrostatic potential generated by the oxide modifies the physical and chemical properties of the adsorbed metal and therefore its reactivity versus the CO adsorbate. (C) 2009 Elsevier B.V. All rights reserved.

N-Protected dipeptidoylbeiizotriazoles react with aqueous ammonia to give dipeptide primary amides (77-98%) and with N-unprotected alpha-amino amides to afford tripeptide primary amides (82-86%). (C) 2009 Published by Elsevier Ltd.

A sensitive, selective and rapid method has been developed for the determination micrograms per liter level of vanadium ion based on the rapid reaction of vanadium(V) with 2,3-dichloro-6-(2,7-dihydroxy-1-naphthylazo)quinoxaline (DCDHNAQ) and the solid phase extraction of the colored complex with C18 cartridge. The DCDHNAQ reacts with V(V) in the presence of citric acid-sodium hydroxide buffer solution (pH 3.3) and benzyldimethyl tetradecylammonium chloride (zephiramine) medium to form a violet complex of a molar ratio 1:2 [V(V) to DCDHNAQ]. This complex was enriched by solid phase extraction with C18 cartridge and the enrichment factor of 100 was obtained by elution of the complex from the cartridge with acetonitrile. The molar absorptivity and Sandell sensitivity of the complex are 2.45 x 10(5) L mol(-1) cm(-1) and 0.0208 ng cm(-2) at 573 nm in the measured solution. Beer's law is obeyed in the range of 0.01-0.45 mu g mL(-1), whereas Ringbom optimum concentration ranges found to be 0.025-0.425 mu g mL(-1). The detection and quantification limits are 3.2 and 9.9 mu g L(-1), respectively in the original samples. This method was applied to the determination of vanadium(V) in steel, soil, water and biological samples with good results. (C) 2009 Elsevier B.V. All rights reserved.

The effect of variable thermal conductivity on free-convection boundary layer of an electrically conducting non-Newtonian power law fluid over a non-isothermal vertical full cone in a saturated porous medium in the presence of a magnetic field applied normal to the cone surface has been studied. The transformed nonlinear ordinary differential equations are solved numerically using the fourth-order Runge-Kutta method coupled with the shooting method. The effects of the power law index, the magnetic parameter and the thermal conductivity parameter on the temperature profiles as well as on the local Nusselt number are presented and discussed.

A simple, rapid, accurate, precise and sensitive spectrophotometric method for the determination of amlodipine besylate (ADB) in bulk sample and in dosage forms is described. The method is based on oxidation of the drug by potassium permanganate in acidic medium and determine the unreacted oxidant by measuring the decrease in absorbance for five different dyes; methylene blue (MB), acid blue 74 (AB), acid red 73 (AR), amaranth dye (AM) and acid orange 7 (AO) at a suitable lambda(max) 663, 609, 511, 520, and 484 nm, respectively. Regression analysis of Beer's law plots showed good correlation in the concentration ranges 1.0-24, 0.9-22, 1.2-26, 0.9-12.8 and 1.0-14 mu g ml(-1), respectively. The apparent molar absorptivity, Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results. Ringbom optimum concentration ranges were 1.2-22.4, 1.1-20, 1.4-24.5, 1.0-12.3 and 1.3-13.2 mu g ml(-1), respectively. Statistical treatment of the results reflects that the proposed procedures are precise, accurate and easily applicable. for the determination of amlodipine besylate in pure form and in pharmaceutical preparations. (C) 2009 King Saud University. All rights reserved.

A total of 120 albino mice were divided into: G1 (80 infected with S. mansoni cercariae by tail immersion) and G2 (40 uninfected controls). Seven weeks after infection, G1 was subdivided into four subgroups of 20 mice each. Gla: Infected untreated control. G1b: treated with Praziquantel (PZQ) in a dose of 500 mg/kg for two consecutive days. G1c: treated with Oltipraz (Oz) in a dose of 500 mg/kg for three consecutive days. G1d: treated with combination of PZQ and Oz (1/3 therapeutic dose of both for two consecutive days. G2 was divided into 4 subgroups of ten mice each. G2a: non infected non treated. G2b: PZQ treated (PZQ control positive). G2c: Oz treated (Oz control positive). G2d: Drugs treated (PZQ and Oz control positive). The effect of drugs was done 2 weeks post-treatment, parasitologically to detect number of worms and the distribution in liver vasculature after perfusion of hepatic circulation of mice, and number of eggs per gram of liver tissue. Also, histopathological examination of liver samples with H& E and/or Masson's trichrome stains showed effect on granuloma and tissue. PZQ gave reduction of total worm burden to 0.22 + 0.01 (99%), while Oz gave 22.4 + 0.57 (3.6%). PZQ produced marked hepatic shift while Oz gave 6.14%efficacy. A decrease in egg number with PZQ was 63.69%. Oz gave 13.5%. Complete disappearance of immature ova with increase no. of dead ones was 97.89% of mature ova stage to 2.11% after PZQ. Oz gave 45% of all detected ova with slight increase of dead ones to 14.18% compared to 9.8% in infected control. Improvement of hepatic pathology in form of 51.2% reduction in granuloma size and 54.7% decrease in number with improvement of hepatocytes was after treatment with PZQ in contrary to Oz as reduction of size and number of granuloma was 13.6% and 21.6% respectively. Combination of reduced dose of both drugs produced moderate effect on all criteria less than that detected with full dose of PZQ, but much better that obtained after Oz.

A total of 410 Tilapia zillii, 70 Clarias gariepinus, 30 Bagrus bajad and 15 Chlrysichthys auratus fishes were collected from different water bodies in Qualyobia Governorate. Microscopic examination of samples showed infection in muscles and head region (gills & branchial cavity) with encysted metacercariae in 91.7% of T. zillii, 82.85% of Cl. gariepinus, 70% of B. bajad and 86.66% of Ch. auratus. The highest distribution of metacercarial infection among the T. zillii was in the muscles of posterior third and tail followed by the middle third, anterior third and head region (gills & branchial cavity) while the highest distribution of metacercarial infection among Cl. gariepinus was in the middle third muscles followed by the posterior third, anterior third and lastly in the head region. The highest metacercarial infection among B. bajad and Ch. auratus fish was in the posterior third muscles and branchial cavity respectively. The taxonomic morphology of the encysted metacercariae and the excysted ones was given

The effect of a magnetic field on a micropolar fluid flow in the vicinity of an axisymmetric stagnation point on a circular cylinder is studied numerically. The governing conservation equations of continuity, momentum and angular momentum are partial differential equations which are transformed into a system of ordinary differential equations by using the usual similarity transformations. The resulting system of coupled non-linear ordinary differential equations is solved numerically by using the shooting method. The numerical results indicate the velocity, angular velocity and pressure distributions for different parameters of the problem including Reynolds number, magnetic parameter and dimensionless material properties, etc. In addition, the effect of the pertinent parameters on the local skin friction coefficient and the couple stress are discussed numerically and illustrated graphically.

In the present work, we calculate the total reaction cross sections for the reactions of the following projectiles: P, (12)C, (14)N, (16)O, (22)Ne, (24)Mg, (28)Si, and (32)S with emulsion nuclei, at incident energy E(Lab) = 3.7 GeV/n, in the framework of the modified Glauber models I and II (Gl-I and Gl-II approaches). At the same time the number of interacted nucleons from these projectiles and the emulsion target nuclei beside the number of their binary collisions are calculated. Also the multiplicity of the shower particles produced in these reactions are calculated. A comparison between the calculated values of these total reaction cross sections and their multiplicities of the produced shower particles in these reactions, with the corresponding measured values, had been done within both: Gl-I and Gl-II approaches and in accordance to the zero-range considerations. As a result of this comparison we have not obtained an agreement between the calculated values and the corresponding experimental data in case of the total reaction cross sections, but we have got, in general, a good agreement for the comparison in the case of the particle multiplicities calculations. It should be noted, for the last comparison, that the theoretical calculations in the framework of Gl-II approach give, in general, agreement with the corresponding experimental data better than those we have obtained for the theoretical calculations in the framework of the Gl-I approach.

We present results of electronic structure and transport calculations for metallic interfaces, based on density functional theory and the non-equilibrium Green's function method. Starting from the electronic structure of smooth Al, Cu, Ag, and Au interfaces, we study the effects of different kinds of interface roughness on the transmission coefficient and the I-V characteristic. In particular, we compare prototypical interface distortions, including vacancies and metallic impurities.

A voltammetric method is described for the determination of nimesulide based on the reduction of the nitro group at glassy carbon electrode. The voltammetric behavior of the drug was investigated in Britton-Robinson buffer (pH 2.0-12.0) applying cyclic voltammetry technique. One cathodic and one anodic peaks were observed. The comparison of peak heights and potentials indicated that these peaks are quasi-reversible. The determination of nimesulide in pure form was performed using adsorptive linear sweep voltammetry. The cathodic peak current varied linearly in the range 4.0x10(-7) - 5.0x10(-5) M (0.116 - 14.65 mu g mL(-1)). The limits of detection (LOD) and quantification (LOQ) were 3.2x10(-8) and 1.06x10(-7) mol L(-1), respectively. The proposed method was applied to pharmaceutical formulations with percent recoveries in the range 98.00-101.60%, and a relative standard deviation of 0.61-1.46%. The validity of the method was performed to the determination of nimesulide in human serum with acceptable results for biological samples. No sample pre-treatments or solvent extraction procedures were needed.

An efficient and direct one-pot reaction of ethyl saccharinylcyanoacetate derivative 3 with a variety of active methylene reagents and nitrogen nucleophiles afforded novel series of polyfunctionally substituted heteroaromatic derivatives 5-13, respectively. The pyrazole derivative 13 was seemed to be the excellent precursors for the synthesis of pyrazolo[1,5-a]pyrimidine derivatives 14-24. The antimicrobial screening of some synthesized products was evaluated against some selected bacteria and fungi. The structures of the synthesized derivatives were established by elemental and spectral data.

The present paper deals with an intrinsic investigation of the notion of a concurrent pi-vector field on the pullback bundle of a Finsler manifold (M, L). The effect of the existence of a concurrent pi-vector field on some important special Finsler spaces is studied. An intrinsic investigation of a particular beta-change, namely the energy beta-change ((L) over tilde (2)(x, y) = L-2(x, y)+ B-2(x, y) with B := g((zeta) over bar,(eta) over bar); (zeta) over bar being a concurrent pi-vector field), is established. The relation between the two Barthel connections Gamma and (Gamma) over tilde, corresponding to this change, is found. This relation, together with the fact that the Cartan and the Barthel connections have the same horizontal and vertical projectors, enable us to study the energy beta-change of the fundamental linear connection in Finsler geometry: the Cartan connection, the Berwald connection, the Chern connection, and the Hashiguchi connection. Moreover, the change of their curvature tensors is concluded. It should be pointed out that the present work is formulated in a prospective modern coordinate-free form.(a)

Irradiation of gamma-ray to FSM-16 encapsulated HAuCl(4). synthesized via chemical vapor deposition, led to the formation of Au nanowires (2 10 nin diameter and 17 147 nm length), Contrarily, reductive carbonylation of impregnated HAuCl(4) with FSM-16 using CO (200 torr)/water (20 torr) for 2 h, Followed by it! radiation with a high-pressure Hg lamp at 300 K. for 36 h, resulted in the formation of Au nanoparticles (circular; 8-75 nin diameter). These catalysts have been characterized by XRD, N(2)-sorpitometry, TEM, UV-vis-PRS, CO-FTIR spectroscopy, and then tested for water-gas shift reaction (WGSR) under feeding conditions of P(CO) = 60 torr and PH(2)O = 5 torr. Evidently, Au nanowires exhibited higher activity (3 times) than Au nanoparticles. It has been shown that the activity depends on Au geometry rather than structural characteristics, such as surface area, In-situ FTIR CO adsorption and UV-vis-DRS evidenced major changes oil the surface properties of Au nanowires in exposing different oxidation states as well Lis inducing electron deficiencies exceeding those oil Au nanoparticles. Gold nanowires displayed surface plasmon resonance peak at 5 5 nm derivatized from distribution in size and dispersion and Father exceeding that at 484 rim exhibited for gold nanoparticles. It has beet) shown that Au(0) species, including nanowires and small aggregated metallic nanoparticles, contribute significantly, if not predominantly, to the WGS activity. The TEM study provided evidence that reduction pretreatment of Au nanowires prior to carrying out the reaction results in elimination of the activity due to sintering (from 35 to 53 nm)as well as to the exhibited change in geometry and thus altering the nature of active centers.

The influence of coprecipitated hexagonal barium ferrite BaFe(12)O(19) phase on the cure characteristics and dynamic properties of natural rubber-ferrite composites has been Studied as a function of ferrite loading up to 220 phr (part per hundred part of rubber). Unusual characteristics of coprecipitated ferrite particles were discovered by scanning electron microscope. The results show that scorch time t(10) and cure time t(90) decrease dramatically with increasing ferrite content LIP to critical ferrite loading. After 160 phr, t(90) increases sharply with increasing ferrite content, in contrast to saturation of t(10). Minimum torque recorded normal behaviour at low ferrite loading, whereas it decreases with increasing ferrite content at high ferrite loading because of dilution effects. The storage modulus E' and loss modulus E '' decrease with increasing temperature. The loss tangents (tan delta) of the composites are greater than those of the pure rubber. Linear viscoelastic behavior was observed as a result of the homogeneity and compatibility of the composites. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3294-3299, 2009

N-(Acyl)-1H-benzotriazoles 6a-f react with L-cysteine 5 at 20 degrees C to give exclusively (i) N-acyl-L-cysteines 8a-e in the presence of triethylamine in CH(3)CN-H(2)O (3: 1), but (ii) S-acyl-L-cysteines 7a-c in CH(3)CN-H(2)O (5:1) in the absence of base. Structures 7b, 7d and 8b, 8d are supported by 2D NMR spectroscopic methods including gDQCOSY, gHMQC, gHMBC, and (1)H-(15)N CIGA-RgH M BC experiments. The structure of compound 8d was also supported by single-crystal X-ray diffraction.

The influence of coprecipitated barium ferrite (BaF) on the magnetic and mechanical properties of natural rubber-ferrite composites (RFCs) has been studied. Unusual characteristics of the BaF particles were revealed by a scanning electron microscope. The results show that the saturation magnetisation increases with increasing the ferrite content even for the considerably high BaF loading samples, whereas the coercivity is almost unchanged. The present RFCs recorded relatively low density 1.95 g cm(-3) with high stored energy 1.26 MGOe at the maximum BaF loading of 220 phr. Both of the tensile strength and the elongation at break decrease with increasing BaF content. Evaluation of the swelling ratio was carried out to have an insight into the change in the mechanical properties of the RFCs at high BaF loading.

Nanocrystalline Mg-substituted NiCuZn ferrites were successfully synthesized, for the first time, by using metal nitrates and freshly extracted egg white. The thermal decomposition process of the nitrate-egg white precursors was investigated by thermogravimetric (TG) technique. X-ray diffraction (XRD) revealed that, single-phase cubic ferrites with average particle size of 23.9-35.1 nm were directly formed after ignition at 500 degrees C. No noticeable variation of lattice parameters with increasing magnesium content was observed, while X-ray densities were found to decrease. This can be explained on the basis of ionic radii and atomic masses of the substituted cation. Transmission electron microscope (TEM) shows that, particles are permanently magnetized and get agglomerated. The saturation magnetization (M(s)) and coercivity (H(c)) as a function of Mg content were investigated using vibrating sample magnetometer (VSM). It has been found that the M(s) increases firstly up to x = 0.2 and then decreases, while H(c) continuously decreases. Magnetic susceptibility measurements give results which agree well with those obtained by VSM. The obvious decrease in the Curie temperature (T(C)) with increasing mg indicates that the ferrimagnetic grains are widely separated and enclosed by non-magnetic magnesium ions. (C) 2009 Elsevier B.V. All rights reserved.

In this paper we apply the dynamical systems method (DSM) proposed by A. G. Ramm. and the variational regularization method (VRM), to obtain numerical solution to some singularly perturbed ill-posed problems contaminated by noise. The results obtained by these methods are compared to the exact solution for the model problems. It is found that the dynamical systems method is preferable because it is easier to apply, highly stable, robust, and it always converges to the solution even for large size models. (C) 2009 Elsevier Ltd. All rights reserved.

Nous etudions ici les effets d'une viscosite et d'une conductivite thermique variables sur l'ecoulement et le transfert de chaleur d'un fluide non Newtonien conducteur a l'interieur d'un mince film liquide sur une surface instable elastique en presence d'un champ magnetique transverse. Le systeme transforme d'equations differentielles ordinaires non lineaires est alors solutionne numeriquement. Nous presentons de facon graphique et analysons les resultats illustrant les effets des differents parametres sur les profils de vitesse et de temperature. Nous presentons sous forme de tables les valeurs du coefficient local de friction de peau et du nombre local de Nusselt pour differentes valeurs des parametres physiques.

New nano-blue ceramic pigments of CoxMg1-xAl2O4 (0

The reaction of 2-hydroxyoctadecanoyl chloride (2) and anthranilic acid gave 2-(1-hydroxyheptadecyl)-4H-3,1-benzoxazin-4-one (3) which was used as starting material to synthesize some condensed and non-condensed heterocyclic compounds by reaction with nitrogen nucleophiles (e.g., hydrazine hydrate, and formamide). Subsequent reaction of the synthetic products with different amounts of propylene oxide gave a novel group of nonionic compounds having a double function as antimicrobial and surface active agents which may be useful in the manufacture of drugs, cosmetics, pesticides or as antibacterial and/or antifungal. The surface active properties such as surface and interfacial tensions, cloud point, foaming height, wetting time, and emulsification power were determined. The antimicrobial and biodegradability were also screened.

The electrical properties measurements were carried out for the complex (CH2)(2)(NH3)(2)Mn1-xCdxCl4, 0.0

The oxidation states of Thallium in F-A1 Tl+n (n = 1, 3) color centers at the (100) surface of NaCl play important role in laser light generation and adsorbate-substrate interactions. Double-well potentials at these surfaces are investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the F-A1 Tl+n (n = 1, 3) defect site were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the oxidation states of Thallium. The relaxed excited states of the defect-containing surface were deep below the lower edge of the conduction bands of the ground state defect-free surface, suggesting that the F-A1 Tl+n (n = 1,3) centers are suitable laser defects. The dependence of the orientational destruction and recording sensitivity on the oxidation state of Thallium is clarified. The Glasner-Tompkins empirical rule is generalized to include the oxidation state of the impurity cation. The adsorption energies of CO and OC over NaCl(I 00) was found to be sensitive to the oxidation state of the impurity cation. F-A1 Tl+n (n = 1, 3) centers changed the physical adsorption of CO to chemical adsorption. While the artificial flow of charge was significant in the case of Tl+1 impurity, it was negligible in the case of Tl+3 impurity, and the results were explained in terms of the electrostatic potential curves. (c) 2006 Elsevier B.V.

In this paper we study the response of single-degree-of-freedom with cubic, quartic and quintic nonlinearities to an amplitude-modulated excitation whose carrier frequency is much higher than the natural frequency of the system. The only restriction on the amplitude modulation is that it contains frequencies much lower than the carrier frequency of the excitation. The method of multiple scales is used to derive two coupled first-order ordinary differential equations that describe the evolution of the amplitude and phase with damping, nonlinearities and resonances. The evolution equations are used to determine the steady-state motions, while representative frequency-response curves are presented for each resonance. Stability analysis of the amplitude and phase modulation equations for both cases are performed. The bending of the response curves leads to multi-valued solutions and hence to jump phenomena.

The response of a single-degree-of-freedom system with quadratic, cubic and quartic nonlinearities subjected to a sinusoidal excitation that involves multiple frequencies is considered. The method of multiple scales is used to construct a first order uniform expansion yielding two first-order nonlinear ordinary differential equations that are derived for the evolution of the amplitude and phase. These oscillations involve a subharmonic oscillation of order one-fourth and superharmonic oscillation of order two. Steady state responses and their stability are computed for selected values of the system parameters. The effects of these (quadratic, cubic, and quartic) nonlinearities on these oscillations are specifically investigated. With this study, it has been verified that the qualitative effects of these nonlinearities are different. Regions of hardening (softening) behaviour of the system exist for the case of subharmonic resonance. The response curve is not affected by decreasing the damping factor for the case of superharmonic resonance. It is shown that the response curve contracts or expands as the parameters vary. The multivalued region increases or decreases when some parameters vary.

6-aminopyrazolo[3,4-b] pyridine-5-carbonitrile (2) was used as a precursor for the synthesis of a variety of pyrazolo[3,4-b][1,8] naphthyridines (3,4) and pentaazacyclopenta[b]naphthalenes (5-10, 13, 14) via the initial addition to either the cyano or amino group followed by cyclization. Also, a series of heptaazadicyclopenta[a, g] naphthalenes (15-17) and heptaazacyclopenta[b]phenanthrenes (18, 19) were obtained via the interaction of 4-(dibenzothiophen-2-yl)-1,5-dihydro-5- imino-3-methyl-1-phenyl-1,2,6,8,9-pentaazacyclopenta[b]naphthalen-6-ylamine (14) with different reagents. The structures of the synthesized compounds were established by elemental and spectral analyses.

A series of barium titanium oxide with various Ba/Ti ratios having a hollandite structure was obtained by ceramic technique. It was shown that barium titanium hollandites may adopt both oxygen excess and oxygen deficient stoichiometries within the structure. As a limiting case the barium titanium hollandites with only tetravalent titanium ions were obtained. Results of investigation samples in the general formula BaxTi4-2xFe2xO8; 0.1

The inhibitive effect of the extract of khillah (Ammi visnaga) seeds, on the corrosion of SX 316 steel in HCl solution was determined using weight loss measurements as well as potentiostatic technique. It was found that the presence of the extract reduces markedly the corrosion rate of steel in the acid solution. The inhibition efficiency increases as the extract concentration is increased. The inhibitive effect of khillah extract was discussed on the basis of adsorption of its components on the metal surface. Negative values were calculated for the energy of adsorption indicating the spontaneity of the adsorption process. The formation of insoluble complexes as a result of interaction between iron cations and khellin, which present in the extract, was also discussed. (c) 2005 Elsevier B.V.

The electrical characteristics of DC Nitrogen-Hydrogen mixture glow discharge were investigated. The discharge current-voltage (I-V) characteristic curves of the discharge were measured at different gas pressures and gas mixture percentage. The axial distribution of both potential and electric field were studied at different H-2 percentage. The existence of the reversal electric field in the negative glow region was confirmed. Using the axial electric field distribution, the cathode fall thickness (X-c) was calculated. Second derivative of the single Langmuir probe electron current method was used to measure the electron energy distribution function (EEDF) in (N-2-H-2) gas mixture DC glow discharge at different H-2 percentage. In the positive column region, a Maxwellian EEDF was found at different conditions, while in both cathode fall and negative glow regions, a non-Maxwellian EEDF was observed. Two groups of electrons were detected in these two regions.

Fuzzy neighbourhood base spaces (FNBS), introduced by Morsi, are a special type of stratified I-topological spaces (SI-TOP), previously denoted as fuzzy topological spaces (FTS). We introduce further characterizations of FNBS in terms of level sets. Also, we construct stable subconstructs of SI-TOP, in the sense of Lowen and Wuyts [Stable subconstructs of FTS: I, J. Fuzzy Math. 1(3) (1993) 475-489], whose corresponding total stratified I-topologies are generated by elements of I-I which are greater than id(I). The maximal objects of such stable subconstructs have weaker properties than that of the ascending chain property, and then these objects give rise to fuzzy neighbourhood base spaces. Therefore, special types of fuzzy neighbourhood base spaces are constructed. (C) 2006 Elsevier B.V. All rights reserved.

N-(alpha-Aminoalkyl)benzotriazoles, prepared from a variety of aldehydes and secondary amines, react with diverse ester enolates, sulfones, a sulfoxide, alkylated pyridines, and nitriles to provide novel access to beta-amino carboxylic esters (55-80% yield), beta-aminoalkyl sulfones (42-88% yield), beta-aminoalkyl sulfoxides (20-32% yield), alpha- and gamma-(beta-aminoalkyl)pyridines (69-90% yield), and beta-aminoalkyl cyanides (10-97% yield), respectively.

A smooth and rapid one step synthesis of novel pyrido[2 ',3 ':3,4] pyrazolo[1,5-a]pyrimidines 4a,b and 7, pyrido[2',3':3,4]pyrazolo[5,1-c]triazines10-12a, b, pyrido[3 '',2 '':4,5] thieno[3',2': 4,5] pyrimido/triazino[1,6-a]benzimidazoles 15-20 in synthetically useful yields utilizing, 3-amino-4-phenyl-5-(saccharin-2-yl)-1H-pyrazolo[3,4-b]pyridine (3) were described. The structure assignment of the new compounds is based on chemical and spectroscopic evidence. Preliminary biological studies of some synthesized compounds showed promising antimicrobial activities.

The present paper deals with families of non-trivial solutions of the equation (d/d xi omega)(2) = P omega(4)(xi) + Q omega(2)(xi) + R. On the basis of these solutions, a direct and generalized algebraic algorithm is described for constructing the new solutions of some nonlinear partial differential equations (NLPDEs). Subsequently, many new and more general exact solutions in terms of the Weierstrass elliptic function p (xi; g(2), g(3)) are obtained. The method can be applied to other NLPDEs in mathematical physics. (C) 2009 Elsevier Ltd. All rights reserved.

This paper deals with the study of the effect of MHD on thin films of a micropolar fluid. These thin films are considered for three different geometries, namely: (i) flow down an inclined plane, (ii) flow on a moving belt and (iii) flow down a vertical cylinder. The transformed boundary layer governing equations of a micropolar fluid and the resulting system of coupled non-linear ordinary differential equations are solved numerically by using shooting method. Numerical results were presented for velocity and micro-rotation profiles within the boundary layer for different parameters of the problem including micropolar fluid parameters, magnetic field parameter, etc., which are also discussed numerically and illustrated graphically. (C) 2009 Elsevier B.V. All rights reserved.

Polycrystalline ferrites with general formula NiFe(2-x)Cr(x)O(4) (0

The inhibition effect of Ni2+ cation, 3-methyl pyrazolone (3-MP) and mixture of them on the corrosion of carbon steel in 0.5 M H2SO4 solution was studied using weight loss, galvanostatic and potentiodynamic anodic polarization techniques The inhibition efficiency increases with increasing concentration of Ni2+ and 3-MP. The mixtures of Ni2+ and 3-MP improved the inhibition efficiency The formation of complex Compound was discussed depending on the results derived from UV-visible spectrophotometric measurements as well as conductometric titration (c) 2009 Elsevier B.V. All rights reserved

Metal-oxide heterostructures have been attracting considerable attention in recent years due to various technological applications. We present results of electronic structure and transport calculations for the Au-MgO-Au (metal-insulator-metal) heterostructure based on density-functional theory and the nonequilibrium Green's functions method. The dependence of the conductance of the heterostructure on the thickness of the MgO interlayer and the interface spacing is studied. In addition, we address the effects of O vacancies. We observe deviations from an exponentially suppressed conductance with growing interlayer thickness caused by Au-O chemical bonds. Electronic states tracing back to O vacancies can increase the conductance. Furthermore, this effect can be enhanced by enlarging the interface spacing as the vacancy induced Mg states are shifted toward the Fermi energy.

Electrochemical frequency modulation (EFM), a nondestructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is applied here to investigate the inhibition performance of tyrosine (Tyr) toward corrosion of low chromium alloy steel in 0.50 M HCl. Measurements were conducted under various experimental conditions in the range of temperature (20-60 A degrees C). Results obtained from EFM were compared with other traditional corrosion monitoring techniques, namely Tafel extrapolation, impedance, and weight loss. Polarization measurements showed that Tyr acted as a mixed-type inhibitor with cathodic predominance. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protected the metal against corrosive agents. Energy dispersive X-ray spectroscopy and scanning electron microscopy examinations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increased with increase in Tyr concentration, while it decreased with solution temperature. The adsorptive behavior of Tyr on the electrode surface followed Temkin-type isotherm. Thermodynamic functions for the adsorption process were determined. The data obtained from the different methods were in good agreements, which indicated that the EFM technique was valid for monitoring the corrosion inhibition under the studied conditions.

A one-pot three-component synthesis of 3-oxo-3-(phenoxathiin-2-yl)-1-phenyl/(4-chlorophenyl)propyl alkyl/aryl-dithiocarbamate was achieved from the reaction of 3-phenyl/(4-chlorophenyl)-1-(phenoxathiin-2-yl)propenones, amine and carbon disulfide. The antimicrobial activities of some compounds were also screened against some selected bacteria and fungi.

The purpose of this study is to introduce a modification of the homotopy perturbation method using Laplace transform and Pade approximation to obtain closed form solutions of nonlinear coupled systems of partial differential equations. Two test examples are given; the coupled nonlinear system of Burger equations and the coupled nonlinear system in one dimensional thermoelasticity. The results obtained ensure that this modification is capable of solving a large number of nonlinear differential equations that have wide application in physics and engineering. (C) 2009 Elsevier Ltd. All rights reserved.

A spectrophotometric procedure for the determination of sertraline hydrochloride (Sert) and/or clidinium bromide (Clid) in bulk sample and in dosage forms was developed. The purpose of this work was to develop a rapid, simple, inexpensive, precise, and accurate visible spectrophotometric method. The procedure is based on formation of an ion-pair complex by their reaction with bromocresol green (BCG), bromophenol blue (BPB), and bromothymol blue (BTB) in buffered aqueous solution at pH 3. The colored products are extracted into a polar solvent and measured spectrophotometrically at the optimum lambda(max) for each complex. Optimization of different experimental conditions is described. Regression analysis of Beer-Lambert plots showed good correlation in the concentration range of 1-30 A mu g mL(-1). The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. For more accurate analysis, Ringbom optimum concentration range of 2-27 A mu g mL(-1) was used. The developed methods were successfully applied for the determination of sertraline hydrochloride and clidinium bromide in bulk in pharmaceutical formulations without any interference from common excipients. The procedure has the advantage of being highly sensitive and simple for the determination of the studied drugs, weak UV-absorbing compounds.

A simple, selective, highly sensitive and accurate procedure for the determination of trace amounts of copper has been developed based on solid-phase spectrophotometry. Copper reacts with 5-(2-benzothiazolylazo)-8-hydroxyquinoline (BTAHQ) to give a complex with high molar absorptivity (3.17 x 10(7) L mol(-1) cm(-1), 3.07 x 10(8) L mol(-1) cm(-1), 1.22 x 10(9) L mol(-1) cm(-1), and 1.80 x 10(9) L mol(-1) cm(-1)), fixed on a Dowex 1-X8 type anion-exchange resin for 10 mL, 100 mL, 500 mL, and 1000 mL, respectively. The absorbance at 667 nm and 800 nm packed in a 1.0 mm cell was measured directly. Calibration is linear over the range 0.2-3.7 A mu g L(-1) with RSD of < 1.28 % (n = 10). The detection and quantification limits of the 500 mL sample method are 79 ng L(-1) and 260 ng L(-1) when using 60 mg of Dowex 1-X8. For a 1000 mL sample, the detection and quantification limits are 67 ng L(-1) and 220 ng L(-1) using 60 mg of the exchanger. Increasing the sample volume can enhance the sensitivity. The proposed method was applied to the determination of copper in different environmental water samples (tap, pit, spring, and river), food products (rice, corn flour, and tea), and mushrooms, using the standard addition technique.

This paper describes the synthesis and characterization of a new solid acid polymer electrolyte (SAPE) based on polyvinyl alcohol, lithium bromide and sulfuric acid. Ethylene carbonate was used as plasticizer in the matrix for membranes prepared by a solution cast technique. AC impedance spectroscopy was used to determine the ionic conductivity of SAPE at different temperature and frequency values giving some insight into its potential utility as a solid acid membrane in solid state batteries. The ionic transference number of mobile ions has been estimated by a dc polarization method and the results reveal that the conducting species are predominately ions. A solid state magnesium battery is fabricated and characterized. A cell with the configuration Mg/SAPE/MnO2 gives a capacity of 270 mAh/g and has an internal resistance approximate to 175 Omega. The electrode degradation after discharge was characterized by XRD analysis. (C) 2009 Elsevier B.V. All rights reserved.

A new epiphytic moss, Zygodon catarinoi C. Garcia, F. Lara, Sergio and Sim-Sim, was recorded from Libya for the first time. The new species is characterized by ovate to elliptic gemmae, narrowly lanceolate, loosely erect leaves, the abaxial surface of the costae in the distal 1/3-1/2 of the leaf covered with forked papillae, leaf lamina bistratose, rudimentary peristome and with cucullate smooth calyptra. This study is to collected the genus Zygodon growing on trunks of some trees in Al-Jebel Al-Akhdar (Libya) throughout the winter season (January-March, 2007) and May 2008, in order to revision the genus in Libya. The taxa moss flora of Libya after this record became 108.

Biosorption of nickel by two bacterial species: Bacillus subtilis 117S and Pseudomonas cepacia 120S was studied. The maximum uptake of nickel was achieved at 234.4 mu g Ni(2+) ml(-1) by P. cepacia 120S (living and dead biomass) and at 117.2 and 351.6 mu g Ni(2+) ml(-1) by living and dead biomass of B. subtilis 117S. The increase in biomass concentration has shown an increase in the nickel uptake. The nickel removal increased significantly during contact time from 1 to 8 h then remained constant until 24 h where the equilibrium occurred. Biosorption efficiency of nickel increased with increasing pH from 2 to 7 for living and dead biomass of P. cepacia 120S and B. subtilis 117S. Temperature had an important role in nickel biosorption by both species. The nickel removal by living biomass was significantly disturbed after pretreatment of bacterial biomass with sodium azide, mercuric chloride and formaldehyde. Esterification of carboxyl groups, methylation of amino groups and extraction of lipid fraction of biomass by acetone and benzene significantly reduced the biosorption capacity of nickel. Repeated biosorption and desorption operations exhibited that the biosorption capacity of bacterial biomass regenerated with HNO(3) and NaOH as desorbing medium increased significantly in cycle 4 for P. cepacia 120S and B. subtilis 117S. In case of regeneration with HNO(3) and distilled water the biosorption capacity increased significantly in cycle 4 for B. subtilis 117S and did not differ significantly from cycle 1 to cycle 4 for P. cepacia 120S. The biosorption capacity of living and dead biomass of B. subtilis 117S and dead biomass of P cepacia 120S (155.5 as compared to 175.6 and 169.8 mg Ni(2+) g(-1)) was higher than that of sludge, tea and saw dust (148.4, 52.7 and 44.6 mg Ni(2+) g(-1)).

The primary and subharmonic resonances of a nonlinear single-degree-of-freedom (SDOF) system under feedback control with a time delay have been studied by means of an asymptotic perturbation technique. Both external (forcing) and parametric excitations have been included. By means of the averaging method and multiple scales method, two slow-flow equations for the amplitude and phase of the primary and subharmonic resonances and all other parameters are obtained, respectively. The steady state solutions (fixed points) for the original system are investigated. The stability of the fixed points is examined by using the variational method. The effect of the feedback gains, time-delay, the coefficient of cubic term, the coefficients of external and parametric excitations on the steady state responses are investigated and the results are presented as plots of the steady state response amplitude versus the detuning parameter. The results obtained by the two methods are in excellent agreement. There exist saddle node bifurcations for the case of primary resonance and the solutions lose stability for the case of resonance subharmonic.

Periodic solutions are investigated for a weakly damped nonlinear Mathieu equation. The multiple scales perturbation technique is used to determine a third-order solution for a nonlinear Mathieu equation. We derive a first reduced differential amplitude-phase system having periodic components. These equations are used to determine the fixed points. The stability of stationary solutions of this reduced system is analyzed. Numerical solutions are presented, which illustrate the behavior of the steady-state response amplitude as a function of the detuning parameter. Stability analysis is carried out for each case. The effects of these (quadratic and cubic) nonlinearities on these oscillations are specifically investigated. With this study, it has been verified that the qualitative effects of these nonlinearities are different.

A one-pot three component synthesis of alkyl/aryl-dithiocarbamic acid-3-oxo-3-(phenoxathiin-2-yl)-1-phenyl/(4-chlorophenyl)propyl esters (3a-n) was achieved from the reaction of 3-phenyl/(4-chlorophenyl)-1-(phenoxathiin-2-yl)propenones (1a,b), amine, and carbon disulfide. The antimicrobial activities of some compounds were also screened against some selected bacteria and fungi. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Two vacuum residues were delivered from two different petroleum refineries, one from Suez Petroleum Company and the second from Alexandria Petroleum Company. They were subjected to solvent extraction using n-pentane, n-heptane, and ethyl acetate. The process of solvent extraction aims to separate maltenes and asphaltenes. The maltenes were further subjected to liquid chromatography (column chromatograph) in order to separate them into saturates and aromatics (mono-, di-, and poly-) and resins. The saturates that were separated from the maltenes of the two vacuum residues with different solvents were studied by gas chromatography in order to determine how much n-paraffins and cyclo-paraffins they contained.

Two vacuum residues were delivered from two different petroleumr efineri es, one from Suez Petroleum Company and the second from Alexandria Petroleum Company. Two heavy residues were subjected to solvent extraction using n-pentane, n-heptane, and ethyl acetate. The studied residues were fractionated into their comp onents. Infrared spectroscopy was applied to study the distribution of functional groups contained in samples and their components. Some ratios calculated from the peak heights of selected infrared bands allow for a better comparison. The UV-Vis spectroscopic technique was applied to the aromatic fraction to determine how much mono-,di-,and polyaromatics are present in the aromatic fraction. The monoaromatics represent the lowest constituent among the aromatics present, whereas the poly aromatics and diaromatics are predominantly present and form the major constituent.

Conformational equilibria in novel C-nitroso derivatives of indolizines and 3- and 5-azaindolizines have been studied by NMR. (13)C chemical shifts of the carbon alpha to the nitroso group confirmed that these compounds are present in solution as monomers. The conformers arising from restricted rotation about the C-NO bond in monomers were identified by the chemical shifts of the carbon beta to the nitroso group. Barriers to rotation in these compounds were unusually high, particularly for substituents in position 3 of indolizine. Ethyl 2-(methylamino)-1-nitrosoindolizine-3-carboxylate displayed conformers arising from the restricted rotation about the C-COOR bond. Molecular modelling demonstrated that in 1-nitrosoindolizines, the position of the conformational equilibrium is due to steric effects, while for 3-nitrosoindolizines electronic effects prevail.

Reaction of o-phenylene diamine with thiosemicarbazide did not give benzotriazine-2-thione 2 as reported, although the product was found to be benzimidazole-2-thione 3. Glycosylation of 3 with acetobromo sugars 4a-4b gave the respective thioglycosides 7a-7d in addition to minor products of the nucleosides 8a and 8b, in the case of the gluco- and galacto-analogs, respectively. The regioselectivity of glycosylation reaction has been investigated.

A theoretical analysis is performed to study the flow and heat transfer characteristics of magnetohydrodynamic mixed convection flow of a micropolar fluid past a stretching surface with slip velocity at the surface and heat generation (absorption). The transformed equations solved numerically using the Chebyshev spectral method. Numerical results for the velocity, the angular velocity, and the temperature for various values of different parameters are illustrated graphically. Also, the effects of various parameters on the local skin-friction coefficient and the local Nusselt number are given in tabular form and discussed. The results show that the mixed convection parameter has the effect of enhancing both the velocity and the local Nusselt number and suppressing both the local skin-friction coefficient and the temperature. It is found that local skin-friction coefficient increases while the local Nusselt number decreases as the magnetic parameter increases. The results show also that increasing the heat generation parameter leads to a rise in both the velocity and the temperature and a fall in the local skin-friction coefficient and the local Nusselt number. Furthermore, it is shown that the local skin-friction coefficient and the local Nusselt number decrease when the slip parameter increases.

In this study glochidia as most sensitive life-stage of bivalves were used to evaluate the toxicity of copper, zinc and lead. Sensitivity of three species, Anodonta anatina, Pseudanodonta complanata and Unio tumidus were compared to copper and zinc, based on 24 and 48 h LC(50)s. The copper 24 h LC(50) showed the lowest value (26.8 mu g.L(-1)) for Unio tumidus glochidia. After 48 h exposure, close LC(50) values, 18.9 and 19.0 mu g.L(-1), were recorded for A. anatina and U. tumidus glochidia, respectively. U. tumidus glochidia exhibited the highest sensitivity to zinc (48 h LC(50) = 134.2 mu g.L(-1)) followed by P. complanata (48 h LC(50) = 201.6 mu g.L(-1)) and A. anatina (48 h LC(50) = 233.5 mu g.L(-1)). Toxicity of lead to P. complanata glochidia was estimated, 24 and 48 h LC(50)s of lead to 374.6 and 260.8 mu g.L(-1), respectively. No observed effect concentrations (NOECs) for the tested metals exhibited species differences. All NOECs exceeded environmental quality standards (EQS), therefore these species are at risk only in such European freshwaters which have extreme concentration of these metals. Synergistic effect was reported for the combinations of Cu + Zn and Cu + Pb, additive effect was reported for Zn + Pb.

A new series of 3-(phenoxathiin-2-yl)-5-aryl-2-pyrazoline derivatives were synthesized from the reaction of 1-(phenoxathiin-2-yl)-3-phenyl/(4-chlorophenyl)propenones 1a and 1b with different nitrogen nucleophiles. The titled compounds were investigated for their antibacterial and antifungal activities and were compared with the standard drugs. Most of the synthesized compounds demonstrated potent to weak antimicrobial activity.

Series of polymeric surfactants based on decylacrylate (M1) as hydrophobe and oxypropylated maleate (Mm2,4,6 and 8 with different molar ratios of propylene oxide) as hydrophiles were prepared by copolymerization in presence of 1mole% azobiisobutyronitrile (AIBN) as free radical initiator to afford [PMm2, PMm4, PMm6, and PMm8]a-i. The reaction mixtures were followed by sulfation and neutralization to attain [PMmS2, PMmS4 PMmS6, and PMmS8]a-i as anionic copolymeric surfactants, in good yield. These derivatives were purified and characterized by microanalysis, infrared, and 1H-NMR spectra studies. Also, surface activity, dispersing properties, and biodegradability were evaluated. The prepared anionic copolymeric surface active agents revealed good surface activities and high dispersing properties above 70% special for PMms8d with 8mole propylene oxide and equal molar ratio from hydrophilic and hydrophobic monomers. Also, they are more biodegradable than traditional surfactants.

The onset of micelles formations critical micelle concentration, diffusion coefficients as well as particle sizes for some new synthesized anionic copolymer surfactants PSA4a, PSA4b, and PSA4c, were determined and discussed. Three different electrochemical techniques such as cyclic voltammetry (CV), rotating disk voltammetry (RDV), and chronocoulometry (CC) were used in this investigation. The voltammetry of electroactive hydrophobic probe ferrocene solubilized surfactants was investigated in aqueous buffer carbonate solutions of pH 10. The CMC for each PSA4a, PSA4b, and PSA4c, was found to be 3.20x10-4, 4.60x10-4 and 6.30x10-4M, respectively, using both CV and RDV techniques. The amount of adsorption contribution of ferrocene solubilized surfactants at the glassy carbon electrode was determined from chronocoulometric measurements and it was found in the range from (1.4 to 2.7)x10-15M. The apparent diffusion coefficients were estimated from RDV measurements and the real micelles diffusion coefficients were obtained. Re-quilibrium considerations of ferrocene probe kinetics at the electrode surface were treated according to two different modes of slow- and fast-kinetics. The corrected diffusion coefficient values showed constancy at (5.3 +/- 0.1)x10-7, (4.8 +/- 0.1)x10-7, and (3.6 +/- 0.4)x10-7cm2/sec for PSA4a, PSA4b, and PSA4c, respectively in the concentration range from 20 to 200mM. The morphological features of anionic copolymeric surfactants PSA4a, PSA4b, and PSA4c, micelles showed globular self-assembled structure.

The corrosion behavior of carbon steel in 1MHCl solution in the absence and presence of three compounds of ethoxylated fatty amide was studied using weight loss and galvanostatic polarization techniques. The percentage inhibition efficiency was found to increase with increasing of inhibitor concentrations, number of ethylene oxide unit and with decreasing temperature. The inhibitive action of these compounds was discussed in term of adsorption on the steel surface through ethylene oxide unit while the hydrocarbon parts protrude brush-like into the solution. The adsorption process follows Langmuir adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds was also studied. Some activated thermodynamic parameters were calculated.

In this paper, the sufficient conditions that guarantee the convergence of the variational iteration method when applied to solve a coupled system of nonlinear partial differential equations are presented. Especial attention is given to the error bound of the nth term of the resultant sequence. Numerical examples to show the efficiency of the method are presented.

Alkyl (octyl, decyl and dodecyl; C(8), C(10) and C(12)) benzene sulphonyl chloride was used in the preparation of a novel series of nonionic surfactants (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c. The preparations were completed by reacting each alkyl (C(8), C(10) and C(12)) benzene sulphonyl chloride with ethanolamine to give (I-III) respectively. The resulting products were reacted separately with ethylene oxide in the presence of different (base KOH, Lewis acid SnCl(4) and k10 clay) catalysts to produce different moles of nonionic surfactants (5, 7 and 9) in sequence corresponding to (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c respectively. The chemical structures of prepared nonionic surfactants were elucidated by IR and (1)HNMR spectra. The surface activity, biodegradability and biological activities of the prepared compounds were investigated. The obtained data show that these compounds have good surface and biological activities as well as reasonable biodegradability properties.

Three rapid, simple, reproducible and sensitive spectrophotomettic methods (A, B and C) are described for the determination of two organophosphorus pesticides, (malathion and dimethoate) in formulations and vegetable samples. The methods A and B involve the addition of an excess of Ce(4+) into sulphuric acid medium and the determination of the unreacted oxidant by decreasing the red color of chromotrope 2R (C2R) at a suitable lambda(max) = 528 nm for method A, or a decrease in the orange pink color of rhodamine 6G (Rh6G) at a suitable lambda(max) = = 525 nm. The method C is based on the oxidation of malathion or dimethoate with the slight excess of N-bromosuccinimide (NBS) and the determination of unreacted oxidant by reacting it with amaranth dye (AM) in hydrochloric acid medium at a suitable lambda(max) = 520 nm. A regression analysis of Beer-Lambed plots showed a good correlation in the concentration range of 0.1-4.2 mu g mL(-1) The apparent molar absorptivity, Sandell sensitivity, the detection and quantification limits were calculated. For more accurate analysis, Ringbom optimum concentration ranges are 0.25-4.0 mu g mL(-1). The developed methods were successfully applied to the determination of malathion, and dimethoate in their formulations and environmental vegetable samples.

The inhibition effect of natural black cumin oil on the corrosion of nickel in 0.1M HCl solution was studied using galvanostatic and potentiodyanmic anodic polarization techniques. It was found that the inhibition efficiency increased with an increase in the inhibitor concentration of this oil. The inhibitive action of black cumin oil was attributed to the adsorption on metal surface. The adsorbed layer acts as a barrier between the metal surface and aggressive solution, leading to a decrease in the corrosion rate. The adsorption process follows the Langmuir adsorption isotherm. It was found also that black cumin oil provides good protection to nickel against pitting corrosion in sodium chloride solutions.

This article describes an investigation of the corrosion behavior of carbon steel in 2M HCl solution with the addition of some cyanoacetohydrazide derivatives by weight loss, galvanostatic polarization, and potentiodynamic anodic polarization techniques. The explored methods gave almost similar results. Results obtained reveal that inhibitor (I) is the best inhibitor and the inhibition efficiency (IE%) follows the sequence IIIIIIIV. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitors and decreases with increasing temperature of the medium. The addition of KI, KSCN, and KBr to cyanoacetohydrazide derivatives enhanced the inhibition efficiency due to synergistic effect. The effect of temperature on C-steel corrosion in 2M HCl and with the addition of 11x10-6M of investigated compounds in the temperature range 30 degrees-50 degrees C was studied. Some thermodynamic functions were computed and discussed. The inhibitors are adsorbed on the carbon steel surface according to Temkin's adsorption isotherm. Polarization data suggested that the additives used act as mixed-type inhibitors. It was found that the cyanoacetohydrazide derivatives provide good protection to carbon steel against pitting corrosion in chloride-containing solutions.

An analysis is performed to investigate the effects of variable viscosity and thermal conductivity on the two-dimensional steady flow of an electrically conducting, incompressible, upper-convected Maxwell fluid in the presence of a transverse magnetic field and heat generation or absorption. The governing system of partial differential equations is transformed into a system of coupled nonlinear ordinary differential equations, and is solved numerically. Velocity and temperature fields have been computed and shown graphically for various values of the physical parameters. The local skin-friction coefficient and the local Nusselt number have been tabulated. It is found that fluid velocity decreases with an increase in the viscosity parameter and the Deborah number. It is also observed that increasing the magnetic parameter leads to a fall in the velocity and a rise in the temperature. Furthermore, it is shown that the temperature increases due to increasing the values of the thermal conductivity parameter and the heat generation parameter, while it decreases with an increase of both the absolute value of the heat absorption parameter and the Prandtl number.

The present paper is a continuation of the foregoing paper [16]. The main aim is to establish an intrinsic investigation of the conformal change of the most important special Finsler spaces. Necessary and sufficient conditions for such special Finsler manifolds to be invariant under a conformal change are obtained. Moreover, the conformal change of Chern and Hashiguchi connections, as well as their curvature tensors, are given.

The complexation of samarium(III) using 5-(2'-bromophenylazo)-6-hydroxy pyrimidine-2,4-dione (Ra), 5-(4'-chlorophenylazo)-6-hydroxypyrimidine-2,4-dione (Rb), and 5-(2',4'-dimethylphenylazo)-6-hydroxypyrimidine-2,4-dione (Rc) was studied in the presence and absence of cetyltrimethyl ammonium bromide (CTMAB). Binary Sm-R2 and ion associate (Sm-R2)-(CTMAB) complexes were formed at pH 7.2, 7.7, and 8.2 and showed an absorption maxima at 577, 610, and 597nm in the absence and 595, 625, and 613nm in the presence of CTMAB, respectively. The stability constant and the stoichiometric ratio of the formed complexes were also calculated. The ion associate complex formation was completed spontaneously and the resulting complexes were stable for at least 12h. Under the optimum experimental conditions employed, the molar absorptivity, Sandell sensitivity, optimum concentration ranges, detection, and quantitation limits were calculated. Interfering species of different anions and cations have been studied. The precision and recovery for the developed procedures are both satisfactory. The proposed procedure is successfully applied to determine samarium in standard samples of rare earth mixture, synthetic, and monazite samples.

The effect of crown ethers on the corrosion behavior of stainless steel (type 430) in 2M HCl solution was studied using weight loss and galvanostatic polarization methods. The inhibition efficiency was found to increase with increasing the concentration of the inhibitors and deceases with increasing the temperature. The polarization studies showed that crown ethers act as mixed-type inhibitors. The inhibiting effect of these compounds was interpreted in view of their adsorption on the metal surface. The adsorption of these compounds was found to obey Temkin adsorption isotherm. Surface examination and morphological studies were tested using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). All the results achieved were compared and discussed. (C) 2009 Elsevier B.V. All rights reserved.

A computational study using several ab initio methods, HF, DFT and MP2 at different basis set levels (6-31G*, 6-31G**, 6-311G** and 6-311++G**) has been performed to determine the possible stable conformations attained by the cephalosporin nucleus. The calculations were carried out in three stages by studying the conformational analysis of the 3-cephem nucleus, the 3-cephem-4-carboxylic acid nucleus and the acetylamino group of the 7-acetylamino-3cephem-4-carboxylic acid. In the first two stages, the potential energy surfaces indicated two minima that correspond to the S1-up and C2-up conformations, with the S1-up being more stable. The energy required for the interconversion of the S1-up to the C2-up is around 7 kcal/mol, indicating the feasibility of interconversion between the two conformers. In the third stage, the acetylamino group attained two conformations with respect to the 3-cephem nucleus. All the geometric parameters obtained in this study were found to be in reasonably good agreement with available X-ray diffraction data, even upon using a simple basis set. Copyright 2009 Elsevier Inc. All rights reserved.

A computational study using several ab initio methods, HF, DFT and MP2 at different basis set levels (6-31G*, 6-31G**, 6-311G** and 6-311++G**) has been performed to determine the possible stable conformations attained by the cephalosporin nucleus. The calculations were carried out in three stages by studying the conformational analysis of the 3-cephem nucleus, the 3-cephem-4-carboxylic acid nucleus and the acetylamino group of the 7-acetylamino-3cephem-4-carboxylic acid. in the first two Stages, the potential energy surfaces indicated two minima that correspond to the S1-up and C2-up conformations, with the S1-up being more stable. The energy required for the interconversion of the S1-up to the C2-up is around 7 kcal/mol, indicating the feasibility of interconversion between the two conformers. In the third stage, the acetylamino group attained two conformations with respect to the 3-cephem nucleus. All the geometric parameters obtained in this study were found to be in reasonably good agreement with available X-ray diffraction data, even upon using a simple basis set. (C) 2009 Elsevier Inc. All rights reserved.

We have developed dye-sensitized nanocrystalline CdS and ZnS solar cells (DSSCs) based on crystal violet, methylene blue, and fluorescein photosensitizers. Nanocrystalline CdS and ZnS were synthesized by a green synthesis method using starch as the capping agent. Characterization of nanocrystalline CdS and ZnS was carried out by optical absorption and x-ray diffraction. The results indicate that CdS and ZnS prepared by this method may be used as photoelectodes in photo-electro-chemical energy conversion systems. DSSCs have been built and their photocurrent, open-circuit voltage, fill factor, and efficiency have been measured under direct sunlight illumination (1000 Wcm(-2)). The efficiency of the cells made from dye-CdS was much higher than that of the cells made from dye-ZnS. This can be attributed to the particle size effect. Among the prepared dye-sensitized solar cells, a DSSC based on fluorescein dye as the photosensitizer produced the highest overall light solar energy to electricity conversion efficiency.

This paper examines the effect of copper substitution on the structural and magnetic properties in nanocrystalline ferrite series of nominal composition; Ni(0.7-x)Cu(x)ZnO(3)Fe(2)O(4) (where x=0.1-0.6) synthesized by a simple method using metal nitrates and freshly extracted egg-white. X-ray diffraction measurements (XRD) confirmed the formation of single-phase cubic spinel structure. The average crystallite size was calculated using XRD pattern and confirmed by transmission electron microscope (TEM). The nearly constant lattice parameters obtained with Cu substitution was attributed to the small difference in the ionic radius between Ni(2+) and Cu(2+) ions. FT-IR spectra showed two absorption bands assigned to the tetrahedral and octahedral complexes. The effect of Cu concentration on the magnetic properties was investigated using vibrating sample magnetometer (VSM) and molar magnetic susceptibility measurements. The decrease in the saturation magnetization and the Curie temperature values with increasing Cu content was explained in terms of the magnetic moments and magnetic exchange interaction existing between the antiparallel uncompensated electron spin of A and B sublattices. The magnetic measurements also proved that the entire preparation method has a great effect on enhancing the magnetic properties of the system. (C) 2009 Elsevier B.V. All rights reserved.

A magneto-hydrodynamic simulation of a plasma focus device with hemisphere electrodes is constructed. The snowplow model is used with help of the momentum conservation equation to describe the motion of the plasma sheath between the two concentric hemispheres. The model simulates various plasma parameters like plasma temperature and plasma sheath velocity. The circuit equation is used to calculate the discharge current and electrodes voltage across the two hemisphere terminals. A comparison between the cylindrical and spherical devices is built. The results show that the current dip and the spike voltage is expected to be much pronounced in the spherical devices. It is found also that the plasma sheath velocity and temperature in the case of the cylindrical system are higher than that in the spherical one.

Premature luteinization (PL) refers to a rise in serum progesterone (P) levels on the day of hCG administration. Most studies used an absolute P level on the day of hCG administration as an indicator of PL, and the cutoff level differed from 0.8 to 2 ng/mL. Some authors defined PL as a P/E2 ratio of > 1. There is a marked variation in the incidence (13% to 71%), of PL due to discrepancies in definition, population characteristics and/or treatment protocols. The pathogenesis of PL in COH is still poorly understood. Several hypotheses may be considered to explain this phenomenon: elevation of follicular LH levels, serum accumulation of HCG from HMG, increased LH receptor sensitivity of the granulosa cells to FSH, or poor ovarian response with increased LH sensitivity. The consequences of this premature elevation of serum P on IVF outcome remain controversial. Attempts to prevent COH include: use of Low-dose hCG alone in the late COH stages, flexible antagonist protocol, use of mifepristone, aspiration of a single leading follicle, hCG administration when the levels of serum P exceeded 1.0 ng/mL.

Solid polymer electrolytes (SPE) based on poly-(vinyl alcohol) (PVA)(0.7) and sodium iodide (NaI)(0.3) complexed with sulfuric acid (SA) at different concentrations were prepared using solution casting technique. The structural properties of these electrolyte films were examined by X-ray diffraction (XRD) studies. The XRD data revealed that sulfuric acid disrupt the semi-crystalline nature of (PVA)(0.7)(NaI)(0.3) and convert it into an amorphous phase. The proton conductivity and impedance of the electrolyte were studied with changing sulfuric acid concentration from 0 to 5.1 mol/liter (M). The highest conductivity of (PVA)(0.7)(NaI)(0.3) matrix at room temperature was 10(-5) S cm(-1) and this increased to 10(-3) S cm(-1) with doping by 5.1 M sulfuric acid. The electrical conductivity (sigma) and dielectric permittivity (epsilon') of the solid polymer electrolyte in frequency range (500 Hz-1 MHz) and temperature range (300-400) K were carried out. The electrolyte with the highest electrical conductivity was used in the fabrication of a sodium battery with the configuration Na/SPE/MnO2. The fabricated cells give open circuit voltage of 3.34 V and have an internal resistance of 4.5 k Omega.

In this project, nanocrystalline SnO(2) powders were successfully prepared by (a) citrate sol-gel and (b) direct precipitation methods. Powders were characterized using thermal analysis techniques (DTA-TG-DSC), X-ray powder Diffraction (XRD), surface area (BET) and electrical conductivity measurements. XRD patterns showed the presence of the cassiterite structure. SnO(2) particles, prepared through sol-gel method exhibit crystallite sizes in the range from 3.1 to 22.3 nm when the gel is heat treated at different temperatures up to 900 degrees C. SnO(2) nanocrystallites prepared by the precipitation method are comparatively larger in size. The higher specific surface area was obtained for the powder prepared using sol-gel method and the obtained average grain size (d) is relatively large compared with that of the average crystallite size. The powders show a semiconducting behavior with increasing temperature. The higher conductivity obtained for SnO(2) prepared by sol-gel method can be attributed to their smaller average crystallite size. XRD of alumina doped powder exhibits finer particles than pure SnO(2). TEM images showed that the particles are spherical in shape and consist of a core of SnO(2) surrounded by a coating of alumina. The calculated surface area was found to decrease with temperature increases. Due to the effective role of Al(2)O(3) additive as a grain growth inhibitor for the matrix grains, the observed surface area for the coated materials are predominantly higher than for the uncoated materials.

Three rapid, simple, accurate and selective validated spectrophtometric methods (A, B and C) for the determination of piroxicam (PX) and tenoxicam (TX) in bulk sample and in dosage forms are described. The methods are based on the oxidation of the studied drugs by a known excess of potassium permanganate in sulfuric acid medium and subsequent determination of unreacted oxidant by reacting it with Methylene Blue (Basic Blue 9) dye (method A), Acid Red 27 (Amaranth) dye (method B) and Acid Orange 7 (orange II) dye (method C), in the same medium at a suitable lambda(max) = 660, 520 and 485 nm, respectively. The reacted oxidant was found to be corresponding to the drug content. Regression analysis of Beer-Lambert plots showed good correlations in the concentration ranges 1.0-8.0, 1.0-9.0 and 1.0-7.2 pig mL(-1) using methods A, B and C, respectively, for PX and 0.3-7.0, 0.3-1.6 and 0.3-2.5 mu g mL(-1) using methods A, B and C, respectively, for TX. The stoichiometric ratios for the cited drugs to oxidant were studied. The optimum reaction conditions and other analytical parameters were evaluated. The proposed methods were applied successfully to determine the examined drugs either in pure form or pharmaceutical formulations with good accuracy and precision. The relative standard deviations were

A Chebyshev pseudo-spectral method for solving numerically linear and nonlinear fractional-order integro-differential equations of Volterra type is considered. The fractional derivative is described in the Caputo sense. The suggested method reduces these types of equations to the solution of linear or nonlinear algebraic equations. Special attention is given to study the convergence of the proposed method. Finally, some numerical examples are provided to show that this method is computationally efficient, and a comparison is made with existing results.

The effect of replacing vanadium by Cu2+ ion on the dc-electrical conductivity (sigma) and I-Vcharacteristics of (V2O5)(0.7)(GeO2)(0.3) glass has been investigated at different temperatures. The conductivity value increases with increasing the concentration of Cu2+. The electrical conduction is interpreted on the basis of electrons hopping from reduced to unreduced vanadium and/or cupper ions. The I-V characteristic curves showed three regions of conduction, namely, high resistance state (OFF-state), turnover point with zero differential resistance region (partial derivative V/partial derivative I=0) and a differential negative-resistance region. The turnover point is strongly dependent on composition, sample thickness and temperature. The switching data are discussed according to electrothermal model. (C) 2009 Elsevier B.V. All rights reserved.

The effect induced by introducing electron captor substituent, namely, fluorine in the arene rings of phenoxathiin on the structure of the phenoxathiin nucleus have been studied using the ab initio method at the B3LYP/(6-31+G)+d basis set level. The study predicts and analyses the configuration of several not yet synthesized fluorinated-phenoxathiin derivatives. Thus, the magnitude of change in the puckering angle P. of phenoxathiin was found to be dependent on the position of the fluorine atom with respect to the oxygen atom of the central heterocyclic ring. Substitution at the 1-position, meta to the oxygen did induce flattening of the nucleus i.e. increased phi(c), while substitutions at the 2- and 4- positions, para and ortho to the oxygen, respectively, induced further puckering on the nucleus i.e. decreased P.. Successive substitution at these positions enhanced these effects. Thus, 1,9-difluorophenoxathiin was found to be the most flattened, while 2,3,4,6,7,8-hexafluorophenoxathiin was found to be the most puckered fluorinated phenoxathiins. The predicted inversion barrier for all the studied compounds was very small; it did not exceed 1.67 kcal/mol for the most puckered isomer. Consequently, we anticipated these compounds to enjoy an easy butterfly interconversion. (C) 2010 Elsevier B.V. All rights reserved.

Solid polymer electrolytes based on poly (vinyl alcohol) (PVA) complexed with ammonium sulfate (NH4)(2)SO4 at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by X-ray diffraction (XRD) studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with the increase of ammonium sulfate added up to 5 wt %, after which the degree of crystallinity increases. The complexation of the salt with the polymer was confirmed by Fourier transform infrared (FTIR) spectroscopy. Electrical conductivity was measured in the temperature range of 303-373 K. The conductivity was found to obey Arrhenius formula. The dielectric permittivity epsilon' was studied as function of temperature and frequency, respectively. The data showed increasing in epsilon' values with the increase in temperature while decreased with increase in frequency for polymer electrolyte system up to 10% of ammonium sulfate added. For values of addition greater than 10%, epsilon' is independent of both temperature and frequency. The ac conductivity is found to obey the power relation. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1213-1217, 2010

A simple, rapid, accurate, precise and sensitive colorimetric method for the determination of captopril (CAP) in bulk sample and in dosage forms is described. The method is based on oxidation of the drug by potassium permanganate in acidic medium and determination of the unreacted oxidant by measuring the decrease in absorbance for five different dyes; methylene blue (MB); acid blue 74 (AB), acid red 73 (AR), amaranth dye (AM) and acid orange 7 (AO) at a suitable lambda(max) (660, 610, 510, 520, and 485 nm), respectively. Regression analysis of Beer's plots showed good correlation in the concentration ranges (0.4-12.5, 0.3-10, 0.5-11, 0.4-8.3 and 0.5-9.3 mu g ml(-1)), respectively. The apparent molar absorbtivity, Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.5-12, 0.5-9.6, 0.6-10.5, 0.5-8.0 and 0.7-9.0 mu g ml(-1), respectively. The validity of the proposed method was tested by analyzing in pure and dosage forms containing CAP whether alone or in combination with hydrochlorothiazide. Statistical analysis of the results reflects that the proposed procedures are precise, accurate and easily applicable for the determination of CAP in pure form and in pharmaceutical preparations. Also, the stability constant was determined and the free energy change was calculated potentiometrically. (C) 2006 Published by Elsevier Ltd.

The primary and subharmonic resonances of a nonlinear single-degree-of-freedom system under feedback control with a time delay are studied by means of an asymptotic perturbation technique. Both external (forcing) and parametric excitations are included. By means of the averaging method and multiple scales method, two slow-flow equations for the amplitude and phase of the primary and subharmonic resonances and all other parameters are obtained. The steady state (fixed points) corresponding to a periodic motion of the starting system is investigated and frequency-response curves are shown. The stability of the fixed points is examined using the variational method. The effect of the feedback gains, the time-delay, the coefficient of cubic term, and the coefficients of external and parametric excitations on the steady-state responses are investigated and the results are presented as plots of the steady-state response amplitude versus the detuning parameter. The results obtained by two methods are in excellent agreement.

In this work, a new experimental approach was used for measuring birefringence of mixture thermotropic liquid crystal materials at different wavelengths in the visible region. Also the values of the refractive indices were measured for these mixture thermotropic liquid crystals in isotropic and liquid crystal phase at different wavelengths. (C) 2010 Elsevier Ltd. All rights reserved.

Thermal processes involved during the decomposition course of La-2(C2O4)(3)center dot 10H(2)O-FeC2O4 center dot 2H(2)O (1:2 mole ratio) mixture up to 750 degrees C, in an atmosphere of air, were monitored by thermogravimetry and differential thermal analysis. X-ray diffraction and Mossbauer spectroscopy were used to characterize the intermediates and the final product. The results showed that a microcrystalline or possibly amorphous iron(III) oxide with a paramagnetic nature was appeared in the early stages of decomposition at 250 degrees C. By increasing the temperature, a well crystalline hematite with ferromagnetic properties was obtained. XRD pattern of the mixture calcined at 1100 degrees C shows the formation of LaFeO3 single phase in consistent with the hyperfine magnetic splitting (one sextet of lines) characteristic of LaFeO3 obtained in the Mossbauer spectra of the mixture calcined at the same temperature.

A new process to prepare single-phase nano-sized ferrites, Ni(0.80-x)Cu(0.2)Zn(x)Fe(2)O(4) with x = 0.1-0.7, was developed using egg-white precursors. TG measurement showed that, the precursors must be calcined at 550 degrees C. XRD patterns indicated the formation of single-phase cubic ferrites with particle size in the range 28.7-48.4 nm. TEM image gave particle size agrees well with that estimated using XRD. FT-IR spectroscopy showed the characteristic ferrite bands. Hysteresis loops measurements exhibited an increase in the saturation magnetization value (M(s)) up to zinc content of 0.2 followed by unexpected decrease, which suggests the preference of Zn(2+) ions to occupy octahedral sites. The decrease in the coercivity (H(c)) with increasing zinc content is attributed to the lower magneto-crystalline anisotropy of Zn(2+) ions compared to Ni(2+) ions. Temperature dependence of the molar magnetic susceptibility (chi(M)) suggested a ferrimagnetic behavior of the investigated samples and showed a decrease in the value of the Curie temperature (T(C)) with increasing zinc. (C) 2010 Elsevier Ltd. All rights reserved.

The oxidation states of thallium in F-A and F-B color centers at the low coordination (100) and (110) surfaces of AgBr play important roles in laser light generation, color image formation, and adsorbate-substrate interactions. The color center potentials at these surfaces are investigated by using quantum mechanical ab initio methods. Quantum clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and ions that were the nearest neighbors to the F-A and F-B defect sites were allowed to relax to equilibrium. The calculated Stokes shifts suggest that laser light generation is sensitive to the simultaneous effects of the oxidation state of thallium, the coordination number of the surface ion, and the choice of the basis set centered on the anion vacancy. An attempt has been made to explain these effects in terms of Madelung potential, electron affinity, optical-optical conversion efficiency, and adsorbate-substrate electrostatic potentials. All relaxed excited states of the defect containing surfaces were deep below the lower edges of the conduction bands of the groundstate defect-free surfaces, suggesting that the title color centers are suitable laser defects. The dependence of the orientational destruction, recording sensitivity and exciton (energy) transfer on the oxidation state of thallium and the coordination number of the surface ion is clarified. The Glasner-Tompkins empirical rule is generalized to include the oxidation state of the impurity cation and the coordination number of the surface ion. As far as color image formation is concerned, the supersensitizer was found to increase the sensitizing capabilities of two primary dyes in the excited states by increasing the relative yield of quantum efficiency. The Tl+3 surfaces of AgBr are significantly more sensitive than the corresponding Tl+1 surfaces. On the basis of quasi Fermi levels, the difference in the sensitizing capabilites between the examined dyes in the excited states is determined. The adsorbate-substrate interactions were found to be dependent on the oxidation state of the impurity cation and on the electronegativity of the adatom. (c) 2006 Elsevier B.V. All rights reserved.

H-1, C-13, and N-15 NMR chemical shifts for pyridazines 4-22 were measured using 1D and 2D NMR spectroscopic methods including H-1-H-1 gDQCOSY, H-1-C-13 gHMQC, H-1-C-13 gHMBC, and H-1-N-15 CIGAR-HMBC experiments. Copyright (C) 2010 John Wiley & Sons, Ltd.

The primary and subharmonic resonance of order one-third of a cantilever beam under state feedback control with a time delay are investigated. Using the method of multiple scales, we obtain two slow flow equations for the amplitude and phase. The first-order approximate solution is derived and the effect of time delay on the resonance is investigated. The concept of an equivalent damping, related to the delay feedback, is proposed and an appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. The fixed points corresponding to the periodic motion of the starting system are determined, and the frequency-response and external excitation-response curves are shown. Bifurcation analysis is conducted in order to examine the stability of the system.

This paper presents an analytical study of the simultaneous principal parametric resonances of two coupled Duffing equations with time delay state feedback. The concept of an equivalent damping related to the delay feedback is proposed and the appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. The method of multiple scales is used to determine a set of ordinary differential equations governing the modulation of the amplitudes and phases of the two modes. The first order approximation of the resonances are derived and the effect of time delay on the resonances is investigated. The fixed points correspond to a periodic motion for the starting system and we show the frequency-response curves. We analyse the effect of time delay and the other different parameters on these oscillations. The stability of the fixed points is examined by using the variational method. Numerical solutions are carried out and graphical representations of the results are presented and discussed. Increasing in the time delay tau given decreasing and increasing in the regions of definition and stability respectively and the first mode has decreased magnitudes. The multivalued solutions disappear when decreasing the coefficients of cubic nonlinearities of the second mode alpha(3) and the detuning parameter sigma(2) respectively. Both modes shift to the left for increasing linear feedback gain v(1) and the coefficient of parametric excitation f(1) respectively.

In this work, we studied the substitution effect of iron by gallium on the structural, magnetic and electrical properties of the ferrite system; Ni(0.5)Cu(0.25)Zn(0.25)Fe(2-x)Ga(x)O(4) (x = 0-1.0), synthesized by using the urea combustion method. XRD patterns of the samples calcined at 700 C show only cubic spinel ferrite with an average crystallite sizes in the range of 40-54 nm. The lattice parameters were slightly changed with increasing Ga content which can be explained on the basis of the relative ionic radii of Ga(3+) and Fe(3+) ions. FT-IR measurements show two fundamental absorption bands, assigned to the vibration of tetrahedral and octahedral complexes, which were slightly changed with increasing Ga content. Mossbauer measurements enable us to predict the possible cation distribution of the system. It was found that Ga(3+) ion prefer to substitute Fe(3+) ions located in the octahedral site. Superparamagnetic state was observed in the Mossbauer spectra of the samples with Ga content >0.5. The decrease of the magnetic hyperfine field with gallium concentration was explained on the basis of supertransferred hyperfine interaction. A semiconducting behavior was inferred for all samples and the conductivity values were found to decrease with increasing the Ga content. The conduction mechanism in the spinel ferrite compounds was explained in terms of the hopping conduction process. The dielectric constant measured as a function of frequency and temperature was found to be dependent on the Ga concentration. The determined transition temperature was found to decrease with increasing Ga content. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

A non-linear control law is proposed to suppress the vibrations of the first mode of a cantilever beam when subjected to primary and principal parametric excitations. The dynamics of the beam are modeled with a second-order non-linear ordinary-differential equation. The model accounts for viscous damping air drag, and inertia and geometric non-linearities. A control law based on quantic velocity feedback is proposed. The method of multiple scales method is used to derive two-first ordinary differential equations that govern the evolution of the amplitude and phase of the response. These equations are used to determine the steady state responses and their stability. Amplitude and phase modulation equations as well as external force-response and frequency-response curves are obtained. Numerical simulations confirm this scenario and detect chaos and unbounded motions in the instability regions of the periodic solutions. (c) 2005 Elsevier Ltd.

This paper presents the concentration distribution around a growing nitrogen gas bubble in the blood and other tissues of divers who surface too quickly, when the ambient pressure through the decompression process is variable and constant. This effort is a modification of Sirinivasan et al. model (1999) [9]. The mathematical model is solved analytically to find the growth rate of a gas bubble in a tissue after decompression in the ambient pressure. Moreover, the concentration distribution around the growing bubble is introduced. The growth process is affected by ascent rate (alpha)over dot(t), tissue diffusivity D(T), initial concentration difference Delta C(0), surface tension a and void fraction phi(0). (C) 2010 Elsevier Inc. All rights reserved.

Nanostructured titanium dioxide and vanadium oxide supported over titanium dioxide was synthesized using a template synthesis route method under hydrothermal conditions (at 353 K for 5 days) via sodium dodecyl sulfate surfactant. The influence of pH (2.0-9.0) and thermal treatment (623 and 773 K) on the structural, surface acidity and textural properties of TiO(2) and V(2)O(5)/TiO(2) materials was investigated using XRD, thermal analyses, SEM, FTIR, N(2) adsorption and pyridine-FTIR measurements. The synthesized TiO(2) and V(2)O(5)/TiO(2) showed high mesoporosities with different pore sizes ranging from 24.6 to 40.6 A and exhibited nano-sized crystals varying from 7.5 to 15.1 nm. All templated samples exhibited very high surface areas; commencing from 263 to 465 m(2)/g, as well as pore volume up to 0.73 cm(3)/g. The synthesized samples exhibited a pure anatase crystalline phase for TiO(2) in the pH range 4.8-9, in which substantial amounts of mesopores were developed where that prepared at pH = 2.0 showed the formation of only rutile phase with higher affinity to micropores. Surface acid strength was greater for highly dispersed V containing TiO(2) due to a strong interaction of the VO(x) species with support centers that act as electron attractor centers creating Lewis acid sites. It was found that pH has a paramount effect influencing both the nature of pores and the type of TiO(2) formed. The photocatalytic reduction of Hg(2+) in water by UV irradiation was chosen to evaluate the activities of the synthesized materials. (c) 2006 Published by Elsevier Inc.

In this paper, the thermal-diffusion and magnetic field effects on a stagnation point flowing over a flat stretching surface have been obtained and studied numerically with the variation of the viscosity under the Soret and Dufour's effects. The governing continuity, momentum, energy and concentration equations are converted into a system of non-linear ordinary differential equations by means of similarity transformation. The resulting system of coupled non-linear ordinary differential equations is solved numerically. Numerical results were presented for velocity, temperature and concentration profiles for different parameters of the problem as radiation parameter, magnetic field parameter, porous medium parameter, endothermic chemical reaction, heat source parameter, stretching parameter, the Soret and Dufour number and other. Also the effects of the pertinent parameters on the skin friction, the rate of heat and mass transfer are obtained and discussed numerically and illustrated graphically. (C) 2010 Elsevier B.V. All rights reserved.