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  • Author or Editor: A. Abdel Fattah x
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Abstract  

Solid complexes of two derivatives of Schiff bases SAT and SAZ with Pr(III), Nd(III), Gd(III), Dy(III), Ho(III), Er(III) and Yb(III) were prepared and characterized by elemental analysis , IR spectra and TG. The suggested formula of the obtained solid complexes is [MLCl2(H2O)n] for sat and [MLCl (H2O)n] for SAZ where M=trivalent lanthanide ion, L=deprotonated ligand and n=2-3. The TG gives information about the coordinated water molecules, thermal stability and the coordination number of M which was found to be 6–8. A scheme of thermal decomposition of the complexes is also proposed. Comparison of the IR spectra of the ligands with those of their complexes indicate the center of chelation in SAT and SAZ which act as tridentate ligands.

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Abstract  

The rates of extraction of Zn(II) from hydrobromic acid solutions into benzene solutions of the liquid anion exchanger Amberlite LA-2 and those into methyl isobutyl ketone (MIBK) have been investigated. The distribution equilibria of this system have been also studied. Under the used experimental conditions the extracted species of Zn(II) have been proposed. The kinetic data indicated a first order reaction with respect to Zn(II) in both systems, nearly one with respect to HBr and from 0–0.38 for LA-2. In case of extraction of Zn(II) with methyl isobutyl ketone, MIBK, the reaction order with respect to MIBK was found to be 4 and with respect to HBr inverse first order. The rate constants of these extraction processes were determined and the rate determining steps were discussed in the light of the obtained results.

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Abstract  

Several new complexes of Schiff bases ligands H4La and H4Lb with transition metal ions such as Cr(III), Fe(III), Co(II) and Zn(II) are synthesized. Elemental analysis, infrared, UV–Vis and thermal analysis, as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. A square planar geometry is suggested for Zn(II) complexes, while an octahedral geometry suggested for the Cr(III), Fe(III) and Co(II) complexes. The thermal decomposition of complexes was found to be first order reaction and the thermodynamic parameters corresponding to the different decomposition steps were reported.

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Abstract  

The effect of -radiation on the color intensity of aerated, deaerated and oxygenated aqueous solutions of a diazo dye (Helion Red 8B) has been investigated. The decoloration yields of Helion Red 8B neutral aqueous solution, G(-Dye), for the nitrogen-, oxygen- and aerated-saturated solutions were found to be 0.77, 0.46 and 0.36 in the respective early stage. The rate constant for the reaction of the OH radical with the HR8B dye, obtained from competition kinetics using ethanol, was found to be 1.3·1010 M–1·s–1. In aerated solutions (pH 3), the G(-Dye) decreased markedly upon the addition of a very small amount of ethanol. Suggestions are made for possible use of the dye as a radiation dosimeter in the dose range of 0.1 to 2 kGy.

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The effect of benomyl as a fungicide on growth rate and ultrastructure of two isolates (P623 and P1319) of Phytophthora infestants is compared. Using different concentrations (50, 100, 200 and 500 ppm) of benomyl caused an inhibition of the mycelial growth of both isolates depending on the degree of concentration. The isolate P1319 was found to be more sensitive to benomyl than the isolate P623. Ultrastructural studies confirmedthese observations. The hyphae of isolate P1319 subjected to 100 and 500 ppm benomyl showed severe changes in the cítoplasm more than isolate P623. The increase of lipid bodies and vacuoles in hyphal cytoplasm of both isolates was the characteristic phenomenon after treatment of benomylparticulary at the concentration of 500 ppm.

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Abstract  

The effect of radiation on the colour intensity of aerated, oxygen and nitrogen-saturated aqueous solution of Solophenyl Orange TGL has been investigated. Experiments show that the absorption band decreases gradually with the increase of the dose in all cases and the destruction of the skeleton of the dye molecule is promoted, by the presence of oxygen. The kinetics of degradation of solution of (SOTGL) turned out to be of the first order with respect to the low dye concentration (<0.14 g/l) and of zero order for dye concentration (>0.14 g/l). The radiochemical degradation yield (Gd) was calculated and was found to decrease experimentally with the increase of dose for low concentrations, whereas for higher concentrations such a behaviour can be presented by a straight line parallel to the dose axis. The influence of pH on the degradation of the dye was studied. The specific bimolecular rate constant of the reaction of SOTGL with the hydroxyl radical was determined by studying the effect of ethanol concentration on Gd using competition kinetics and was found to be 1.055·109 M–1 s–1. Suggestions are made for possible low radiation dosimetry (about 1.5 kGy) by means of spectrophotometric analysis of the absorption spectra.

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Abstract  

The present investigation has been carried out to study the effect of -radiation on the absorption spectra of aerated solutions of alizarin complexone dye at different concentrations and pH values. The change in optical density for dosimeter concentrations ranging from 5·10–2 to 15·10–2 mM was observed to respond linearly to the increase of absorbed gamma dose. With the proper choice of concentration and pH value, the system is suitable for the accurate measurement of absorbed doses up to 5.3 kGy. This study includes also an investigation of the effect of environmental conditions on the stability of the dye solutions at different pH values during storage. Suggestions are made for possible low radiation dosimetry by means of spectrophotometric analysis of the absorption spectra.

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Abstract  

TL-glow curves of calcium phosphate ceramic powders prepared either from natural or synthetic phosphates have been investigated. The TL-samples from synthetic phosphates, particularly those having Ca/P ratio=2.8, show higher TL-sensitivity, about 1/10 times that of LiF TLD-100 powders, with glow curves having maxima (peaks) around 110, 175 and 325 °C. The TL-response of all phosphate ceramic samples showed a dependence on -dose, well described by a power function in a range from about 1 to 104 Gy, which is useful for therapeutic and radiation processing levels. For regeneration of irradiated TL-samples, annealing around 350 °C for 20 min was found suitable. A low Ca/P ratio can be recommended for high dose measurements, while higher ratio gives greater TL-sensitivity, hence allowing measurement of lower -doses.

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Abstract  

Solvent extraction on Zr(IV) were carried out at 5, 25 and 40 °C using Amberlite LA-2, TBP and HDEHP in toluene or kerosene from solutions of HCl, HBr or KI. The equilibrium constant K ex as well as the thermodynamic functions DG°, DH° and DS° of the nine extraction systems were deduced. The overall extraction equilibria were postulated from the obtained data.

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