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  • Author or Editor: L. Bakos x
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Abstract  

An activation analytical method has been developed for determining Cd, Ag, Sb, Se, Br by 14 MeV neutron-induced X-ray emission spectroscopy using Pr as an internal standard. A good correlation was obtained between the activity ratio, RA o and the weight ratio, RW. Results are given after correction for self-absorption and without correction. The results are comparable in both cases when dilution with H3BO3 (90%) is applied. The elements listed can be determined at minor concentrations (0.01%) with a relative error not more than ±5%.

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Abstract  

The empirical coefficient method represents the absorption and enhancement effect of each element on each other by parameters independent of mass concentrations. This method is used together with the internal standard method for the determination of cadmium, bromine and selenium by 14 MeV neutron activation followed by X-ray spectrometry. The results of analysis show a relative error not more than ±5%.

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Abstract  

The problem of converting measured intensities into mass concentrations arises from the fact that the measured intensity of a characteristic X-ray line of an element or compound depends not only on the mass concentration of that element or compound but also on the nature and abundance of the other constituents of the specimen. In this work the empirical coefficient method which comprises both absorption and enhancement effects of each element on each other element by parameters independent of mass concentrations was used for correction of enhancement effects from antimony and praseodymium on bromine in two groups of samples. The results of analysis of bromine shows a relative error of not more than ±4%.

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Abstract  

A method is described for the simultaneous determination of cadmium, antimony and praseodymium by 14-MeV neutron activation analysis based on characteristic X-ray spectrometry. The results of analysis show a relative error not higher than ±5%, when diluted with H3BO3 /90%/ and utilizing the internal standard method to minimize the interelement effects.

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Abstract  

14 MeV neutron activation followed by X-ray spectrometry was applied to the simultaneous nondestructive determination of cadmium, antimony and bromine, utilizing praseodymium as an internal standard. The results of analysis show a relative error not higher than ±5%, when the samples were diluted with H3BO3 -5% to minimize the interelement effects.

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Abstract  

The intensity of characteristic X-rays emitted from one element may be reduced by partial absorption by other elements in the matrix, or alternatively it is enhanced by their presence. In this work the enhancement effect of antimony on bromine, cadmium and selenium are given. The dependence of the specific activity of each element /Cd, Br and Se/ on the ratio of the weight of Sb to that of the element is given, when the concentration of Sb is not very low /-5%/.

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Abstract  

14 MeV neutron activation of ternary copper silver selenide gives rise to a predominant activity from the 0.511 MeV annihilation peak from the three elements when -ray spectrometry is used. To overcome the interference problems, X-ray spectrometry was applied to the simultaneous nondestructive determination of silver and selenium, after which copper can be determined by -ray spectrometry. The results of analysis show a relative error not higher than ±5%, when the samples were diluted with H3BO3 /90%/ to minimize the interelement effects.

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Ethanol recovery from aqueous fermentation broth by extraction using oleic acid with simultaneous esterification by lipase enzyme was studied. To determine the optimal conditions for the complex process, the ternary system was characterised; binodal curves and tie lines of (ethanol+oleic acid+water) system were determined. Enzymatic esterification of ethanol and oleic acid was carried out and resulted in higher than 50% conversion with simultaneous reduction of ethanol content in the broth. Finally, the effect of the ester product (ethyl oleate) on the distribution of ethanol was determined.

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Abstract  

Preliminary phantom measurements were carried out for regional determination of calcium in the human forearm. Two paraffine phantoms /large and small/ were activated, either in the free space or surrounded by paraffine plates, by a252Cf neutron source. Differences between neutron flux densities in positions of the ulna and radius are discussed.

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Abstract  

The possibility of applications of characteristic X-rays from radioactive products of reactor neutron activation was investigated with particular emphasis on (n, ), n, n), (n, 2n), (n, p) and (n, ) products with long half-lives. The sensitivity and detection limits of silver, cerium, gadolinium, selenium, cadmium and europium have been investigated. The elements were studied both in a pure and in a matrix form, in both cases the samples were diluted with graphite (90%) to minimize matrix effects (absorption and enhancement).

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