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  • Author or Editor: A. El-Sayed x
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Abstract  

Comparison of Compton scattering and Compton scattering cross section with self-attenuation coefficient were explained based on the kinematic equation and Klein-Nishina formula. Naturally occurring elements, 238U (226Ra), 40K, 232Th (228Ra) and 137Cs were determined in sediments and water from Ismailia canal in Egypt which were found in the range of permissible level. Self-attenuation coefficients, K, the ratio between photopeak detection efficiency using solid and liquid standards were determined. They fit well comparing to Compton scattering, Compton scattering cross section while inversely fit to energy-absorption Compton scattering cross section based on the Klein-Nishina formula.

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Abstract  

Thermodynamic investigation of the extraction of both uranium(VI) and uranium(IV) from nitric acid solutions using tri-n-butyl phosphate (TBP) loaded on polyacrylic acid polymer (SM-7) as an inert supporting material has been done using batch technique. The effect of temperature on the equilibrium extraction values has been utilized to evaluate the change in standard thermodynamic quantities (viz. DH, DS, and DG). The Freundlich isotherm was successfully applied to the extraction data of both metal ions. The Dubinin-Radushkevich (D-R) isotherm was found to be valid only in case of U(IV) extraction. Based on the D-R expression, the maximum extraction capacity of loaded TBP and the mean free energy of U(IV) extraction have been determined.

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Abstract  

Pure Na2S2O3·5H2O, was investigated carefully for its X-ray diffraction, IR-absorption spectra, UV/Vis-absorption spectra, thermogravimetric analysis, differential thermal analysis before and after various gamma ray absorbed doses. Results obtained were explained, compared and discussed in detail, leading to a mechanism for radiation damage in this system.

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Two types of actinophages, φS and φL, were isolated from soil samples by using Streptomyces scabies MR13, a potato scab pathogen, as an indicator strain. The phages were partially characterized according to their physicochemical properties, plaques and particles morphology and their host-range. The host-range of these phages was narrow for φS and wide for φL. The adsorption rate constants of the φS and φL were 3.44 × 10−9 and 3.18 × 10−9 ml/min, and their burst sizes were 1.61 and 3.75 virions, respectively. One-step growth indicated that φS and φL have a latent period of 30 min followed by a rise period of 30 min. The temperate character of these phages was tested in other isolates of Streptomyces. Four of the phages (φSS3, φSS12, φSS13 and φSS17) were identified as temperate phages, since they were able to lysogenize SS3, SS12, SS13 and SS17. φSS3, φSS12 and φSS13 were homoimmune, and they were heteroimmune with respect to φSS17. The restriction barriers of lysogenic isolates (SS12, SS13 and SS17) interfered with the blockage of plaques formation by phages (φSS12, φSS13 or φSS17) propagated on them, about 75% of lysogenic isolates had restriction systems. The exposure of the lysogenic isolates (SS12, SS13 and SS17) to UV-irradiation prevented the possible restriction barriers of these isolates, and these barriers could be overcome.

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Summary  

The extractive first order derivative spectrophotometry is a selective method for the separation and determination of U(VI) using tri-n-butyl phosphate (TBP), which combines the roles of solvent and complexing agent. The complex is formed by extracting U(VI) from an aqueous 6M sodium nitrate solution at initial pH 3.0 into a 25% solution of TBP in kerosene. This extraction also separates U(VI) from many diverse ions that interfere. After extraction, the determination of uranium shows good accuracy and precision with relative standard deviation of 1.5% (n = 5) at 20 ppm using zero-order spectrum at lmax = 250 nm. Calibration curve was also found to obey Beer's law in the range of 10-100 ppm with 3.33 ppm detection limit. However, these accuracy and precision have been improved to give relative standard deviation of 0.7% (n = 5) at 20 ppm with a lower detection limit of 2.24 ppm using the first-derivative spectrum at l = 263 nm comparing to the normal one.

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Abstract  

The thermal stability of solidified NaNO3 salts in bitumen and cement has been investigated for safety considerations in the field of solidification of radioactive waste. The thermal decomposition of bitumen and cement in presence of NaNO3 in a temperature range 22–650C has been studied. The fraction decomposed of the pure samples and mixtures showed slow linear reactions followed by acceleratory and decay stages. Data are analyzed according to both Freeman-Carroll and Coats-Redfern kinetics to evaluate the activation energy and the order of reactions of all mixtures. It is found that the activation energies of bitumen and cement were 594 and 203 kJ mol-1, respectively. The order of reactions of bitumen and cement was 2 and 4, respectively. The addition of NaNO3 shortens the duration of the induction period in all mixtures. It was concluded that solidification of radioactive waste containing NaNO3 in bitumen and cement should be applied in the temperature range 22–300C. At temperature higher than300C solidification should be in cement.

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Abstract  

Gamma-irradiation can be used for the sterilization of some99mTc-labelled freeze dried kits. In connection with this the effect of -radiation on Sn(II) content, radiochemical purity,in-vitro stability and biological distribution of some currently used99mTc-labelled kits has been investigated. For irradiation the certain radiation sterilization doses (25 and 50 kGy) were used. A variable decrease of Sn(II) content was observed in all -irradiated kits. The losses are in the order of 10–25% compared with the Sn(II) content of original ones. The colour of the irradiated kits did not changed except DTPA which developed yellow colour after irradiation. For the irradiated and original kits nearly the same pH were found. The irradiated kits seemed to undergo partial decomposition or chemical alteration which led to some deviation of the biological distribution of them.

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The thermal behaviour of the entitled nickel(II) and copper(II) complexes of ¯4-acetylamino-2-hydroxy-5-methyl azobenzene has been studied by means of differential thermal analysis (DTA), thermogravimetry (TG), X-ray powder diffraction, IR and electrical conductivity. A light has been thrown on the nature of interaction of the solvents of crystallization with the host complex. Some of the kinetic parameters are calculated and discussed.

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