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  • Author or Editor: N. El-Assy x
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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  

The effect of -radiation on the electronic absorption spectra of the negatively solvatochromic dyestuff1, namely, 4-(4-N,N,-dimethylaminostyryl)-pyridinium methiodide in water and dimethylsulphoxide solvents is investigated. Ionizing radiation at different absorbed doses brought about gradual bleaching of aerated dye solutions. The -radiation-induced degradation and the consequent changes in the electronic absorption spectrum of dye 1 are discussed in the light of the theoretically calculated spectrum. The linear response range of dye1 in case of DMSO solution is wider than that in H2O. The results demonstrate that the radiochromic dye solution offer dosimetry in the low dose range by means of visible spectrophotometric analysis.

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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  

Hydrogen and methane produced during the -radiolysis of 2-propanol have been measured in the absence and presence of 0.1 and 0.01 M ketone (1-(2-furanyl)-1-hexanone) at different doses. In the absence of ketone at 100 kGy, the hydrogen and methane yields were found to be G(H2)=5.1 and G(CH4)=2.02. At lower ketone concentrations the hydrogen and methane yields were G(H2)=4.35 and G(CH4)=1.83, while higher concentrations decreased the above values to G(H2)=2.95 and G(CH4)=1.33, respectively. The radiolytic mechanism is discussed in detail.

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Abstract  

Chemical and physical properties of Suez Canal bottom sediments (SCBS) and sea water at port Tawfeek area, the south entrance of Suez canal, have been studied. The SCBS was separated into its size fractions (natural sediment, sand, silt and clay). These different sediment fractions were allwed to be in equilibrium with89Sr,60Co and134Cs solutions. Desorption studies were carried out on these contaminated sediments.

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Abstract  

The aminolysis of hexachlorocyclodiphosphazane with substituted or unsubstituted arylamines, led to the preparation of some new organophosphorus compounds. It was also possible to isolate some new geometrical isomers containing substituted arylamines. It has been found that the aminolysis reactions of 1,3-diaryl-2,2,2,4,4,4-hexachlorocyclodiphosphazane take place without ring cleavage of the cyclodiphosphazane ring system, leading to 1,3-diaryl-2-oxo-2,2,4-arylcyclodiphosphazanes. The structures of these aminophosphorus compounds were substantiated on the basis of microanalytical data, infrared, ultraviolet and proton NMR spectroscopic evidence. Hexachlorocyclodiphosphazane and some aminosubstituted cyclodiphosphazane compounds were irradiated by gamma-rays and the ultraviolet measurements before and after irradiation were discussed. It was observed that all the absorption bands show the highest absorptivity values at a particular irradiation integral dose for each of the irradiated compounds. From the ultraviolet results and mass spectrometric data, it may be suggested that the possible decomposition sites of the amino-substituted cyclodiphosphazanes are at the double bond between the four-membered ring and the exocyclic phenyl ring and at the double bond between the four-membered ring and the oxygen atom.

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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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Abstract  

A preliminary liquid-liquid extraction study of ferric and ferrous ions has been undertaken using the radioactive tracer technique with59Fe as an indicator of iron. Various solvents were studied and suitable media and solvents were selected for the separation of the two oxidation states of iron. Such separation was used to study the effect of ascorbic acid and other reducing agents on the reduction of ferric ions. The oxidation of ferrous ions to the ferric state under the effect of gamma radiation from60Co has also been investigated in the absence and presence of ascorbic acid, using spectrophotometry. In addition, a calculation of the amount of iron oxidized by gamma radiation is given with a discussion of its mechanism and possible effects on the metabolism of iron in the human body.

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