R. M. Mahfouz

Isothermal decomposition of γ-irradiated samarium acetate

Abstract Isothermal decomposition of un-irradiated and pre-γ-irradiated samarium acetate has been investigated at different temperatures between 613 and 633 K. Irradiation was observed to enhance the rate of decomposition without modifying the mechanism of thermal decomposition. Thermal decomposition of samarium acetate has been shown to proceed by two-dimensional phase-boundary reaction both for un-irradiated and pre-γ-irradiated samples. The enhancement of the decomposition was found to increase with an increase in the γ-ray dose applied to the sample and may be attributed to an increase in point defects and formation of additional nucleation centers generated in the host lattice. Thermodynamic values of the main decomposition process were calculated and evaluated.

COMPLEXATION REACTIONS OF Dy(III), Er(III), Gd(III), Ho(III), AND Sm(III) IONS WITH THENOYLTRIFLUOROACETONE

The reactions of thenoyltrifluoroacetone (HTTF) and LnCl3 (Ln = Dy(III), Er(III), Gd(III), Ho(III) and Sm(III)) in 3:1 ligand:metal molar ratio have been investigated. The isolated solid products have been characterized by spectroscopy (UV-Vis, IR and 1H NMR), thermogravimetry and elemental analyses. The microanalytical data of the investigated compounds are consistent with the chemical formulas Ln(TTF)3(H2O)2 (Ln = Dy, Gd and Ho), Er(TTF)3, and Sm(TTF)2Cl(H2O). The charge densities on the ligand atoms were calculated by CNDO-SCF calculations. The antibacterial activities of the investigated complexes were tested and evaluated.

Effects of precursor on the morphology and size of ZrO2 nanoparticles, synthesized by sol-gel method in non-aqueous medium

Pure zirconium oxide (ZrO2) nanoparticles with diameters 10-25 nm were synthesized from ZrOCl2.8H2O and Zr(SO4)2.H2O with benzyl alcohol as non-aqueous solvent medium using sol-gel method. Sodium lauryl sulfate was added as surfactants to control the particle size. The synthesized ZrO2 nanoparticles have a mixture of tetragonal and monoclinic structure. The XRD showed the purity of obtained ZrO2 nanoparticles with tetragonal and monoclinic phase and the crystallite size for ZrOCl2.8H2O precursor was estimated to be 18.1 nm and that from Zr(SO4)2.H2O was 9.7 nm. The transmission electron microscopy and scanning electron microscopic studies also shows different sizes of nanoparticles and different morphology depending on the precursor used for the synthesis of ZrO2 nanoparticles

PREPARATION AND CHARACTERIZATION OF NEW In(III), Re(III), AND Re(V) COMPLEXES WITH THENOYLTRIFLUOROACETONE AND SOME BIDENTATE HETEROCYCLIC LIGANDS

ABSTRACT New In(III), Re(III) and Re(V) complexes with the thenoyltrifluoroacetone ligand (HTTA) of the general formulae [In-(TTA)(H2O)4]SO4, [Re(TTA)n(H2O)x]Cl3-n and [ReO(TTA)n-(H2O)x]Cl3-n (where n and x refer to the number of [TTA]− moieties and H2O molecules, respectively) have been prepared and characterized by spectroscopy, thermogravimetry, elemental analyses and X-ray diffraction. The charge densities on the ligand atoms were calculated via CNDO-SCF calculations. The newly prepared complexes. [In(TTA)(H2O)4]SO2 and [ReO(TTA)(H2O)2]CL2 were employed as precursors for the synthesis of the mixed-ligand complexes [In(TTA)(HOCTA)2], [In(TTA)(TZT)2] and [ReO(TTA)(HOTCA)]Cl using R(-)-2-oxothiazolidine 4-carboxylicacid (H2OTCA) and 1H-1,2,4-triazole-3-thiol (H2TZT) as ligands. The synthesized mixed-ligand complexes were characterized by the conventional physical and chemical methods of analysis applied earlier for the characterization of the precursors. The investigated complexes are soluble in water, ethanol and acetonitrile, insoluble in non-polar solvents and could be of potential use for clinical studies. The antibacterial activity of the investigated complexes has been tested and evaluated.

Isothermal decomposition of γ-irradiated uranyl acetate

Isothermal decomposition of un-irradiated and pre-γ-irradiated dehydrated uranyl acetate has been investigated at different temperatures between 573 and 593 K. Irradiation enhances the rate of decomposition without modification of the mechanism of thermal decomposition which has been shown to proceed by a nucleation and growth mechanism, both for un-irradiated and pre-γ-irradiated samples of uranyl acetate. The enhancement of the decomposition was found to increase with an increase in the γ-ray dose applied to the sample and may be attributed to an increase in the number of point defects and formation of additional nucleation centers generated in the host lattice.

Chemical effects of cobalt neutron capture recoils in K3Co/CN/6-K3Fe/CN/6 and K3Co/CN/6-K3Cr/CN/6 mixed crystals

The chemical effects of cobalt neutron capture recoils produced in mixed crystals of the types K3Co/CN/6-K3Fe/CN/6 and K3Co/CN/6-K3Cr/CN/6 have been investigated. Analysis of the neutron irradiated samples was performed using solvent extraction and making use of a 512-channel analyzer for radioactivity measurements. It was found that the initial cobalt parent retentions vary linearly with parent mol fraction in the mixed crystals. The results are discussed in terms of retention and non-retention reactions in view of a mechanistic model involving metal-and ligand-vacancy exchanges, substitution and transfer reactions.

Synthesis, spectral, thermal, X-ray single crystal of new RuCl2(dppb)diamine complexes and their application in hydrogenation of Cinnamic aldehyde

The preparation of new three trans-[RuCl(2)(dppb)(N-N)] with mixed diamine (N-N) and 1,4-bis-(diphenylphosphino)butane (dppb) ligands, starting from RuCl(2)(PPh(3))(3) as precursor is presented. The complexes are characterized on the basis of elemental analysis, IR, (1)H, (13)C and (31)P{(1)H}NMR, FAB-MS, TG/DTA and single crystal X-ray diffraction studies. Complex (2L(1)) crystallizes in the monoclinic unit cells with the space group P2(1). The catalysts are evaluated for their Cinnamic aldehyde hydrogenation. The catalysts show excellent activity and selectivity for the unsaturated carbonyl compound under mild conditions.

A new technetium(V)-2-thiohydantoin complex

SummaryA new 2-thiohydantoin 99Tcv complex was prepared by the direct reduction of TcO4−with alkaline Na2S2O4 in the presence of an excess of the ligand, and characterized by spectroscopy. Reversed phase HPLC on lichrosorb-Rp-18 showed the complex to be pure; electrophoresis measurements showed it to be neutral. The complex was H2O soluble.

Spectroscopic studies and electrical conductivity behavior of γ-irradiated Li2SO4—Na2SO4 mixed system

Abstract The Li2SO4—Na2SO4 mixed system was prepared by the precipitation technique. Electron paramagnetic resonance (EPR) spectra of the γ-irradiated Li2SO4—Na2SO4 mixed system were measured at room temperature. Two types of centers, A and B, identified as SO− 3 and SO− 4, respectively were studied. The SO− 3 center is characterized by an intense isotropic signal with a g-value ≈ 2.0029, while the SO− 4 center appears as a weak and broad signal with a g-value of 2.02. Infrared spectra were recorded for unirradiated and γ-irradiated samples. A decrease in the intensity of the IR spectra was observed after irradiation. The electrical conductivity, σ, was measured for the Li2SO4—Na2SO4 system before and after γ-irradiation in the temperature range from 30 up to 430°C. A considerable decrease in the conductivity value accompanied by an increase in the activation energy was observed after gamma irradiation. The energy of formation of Frenkel defects was estimated to be 3.2eV. The current-voltage characteristics were measured at different temperatures in order to estimate the type of conduction in the samples. Isothermal annealing kinetics were investigated at different temperatures before and after γ-irradiation.

Model free approach for non-isothermal decomposition of un-irradiated and γ-irradiated silver acetate: new route for synthesis of Ag(2)O nanoparticles.

Kinetic studies for the non-isothermal decomposition of unirradiated and γ-irradiated silver acetate with 10(3) kGy total γ-ray doses were carried out in air. The results showed that the decomposition proceeds in one major step in the temperature range of (180-270 °C) with the formation of Ag(2)O as solid residue. The non-isothermal data for un-irradiated and γ-irradiated silver acetate were analyzed using Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ) iso-conversional methods. These free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes in the thermal decomposition behavior of silver acetate were recorded as a result of γ-irradiation. Calcinations of γ-irradiated silver acetate (CH(3)COOAg) at 200 °C for 2 hours only led to the formation of pure Ag(2)O mono-dispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesized nanoparticles.