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  • Author or Editor: N. Yakovlev x
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Abstract  

A semiempirical method of allowing for the effect of impurity element screening in samples of irregular geometry, absorbing thermal and resonance neutrons, is suggested. The accuracy of this method was evaluated for cobalt, silver, indium, iridium, gold and mercury and experimentally checked for silver and indium samples.

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Abstract  

A method has been developed for the activation analysis of boron and cadmium, taking into account neutron absorption of the sample. The concept of the screening coefficient, expressing the self-screening of the matrix on the contamination is introduced. A formula is proposed for calculation of the screening coefficient, based on the boron or cadmium ratios for the contaminating elements being determined. Good agreement between experimental and calculated values was obtained.

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Abstract  

Extraction of Bk(IV), Ce(IV), Pu(IV) and Zr by tributyl phosphate from 2M to 16M nitric acid solutions has been studied. Using the data on the effect of the extractant, nitric acid and nitrate ion concentrations on the distribution coefficients of Bk(IV) and Ce(IV), the mechanism of Bk(IV) extraction by tributyl phosphate from nitric acid solutions is considered.

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Abstract  

The effect of solvent extraction on the redox equilibrium of Me(IV)−Me(III)-type couples is considered using berkelium and cerium as examples. The possibilities of applying a solvent extraction technique to study redox equilibria is discussed. The solvent extraction technique is shown to be reliable for determining the degree of oxidation and the ratio of redox forms only when the solution under study does not contain oxidation agents acting under solvent extraction conditions. Otherwise the results obtained can lead to erroneous conclusions. To make a correct interpretation of the regularities of extraction behaviour of an element in an unsteady valence state, potentiometric data should be used.

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Abstract  

An approach allowing establishment of the relationship between the energies of mixing in binary homovalent melts of metals and the corresponding values for halide salts (chlorides or fluorides) of these metals is proposed. The procedure given as an example for estimation of the exchange energies in liquid-phase systems formed by lithium and other alkali metals allows a considerable reduction in the number of experimentally complicated definitions for thermodynamic characteristics of similar systems.

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Abstract  

A calculation method of self-shielding coefficients of interesting elements in samples of any forms is given for the neutron activation analysis of cadmium and its compounds. The determination of ten elements in cadmium telluride using radiochemical separation and γ spectrometry is described.

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Abstract  

A procedure for neutron-activation analysis of cerium, lanthanum, praseodymium and neodymium, tested on more than thirty samples of steels, is described. After irradiation for 20 hrs with a neutron flux of 1.2·1013 n·cm−2·sec−1 the steel samples were dissolved in aqua regia and extraction separation of iron from 6N HCl by ether was employed. The REE were separated as a group by precipitation as fluorides and hydroxydes. The individual rare-earth elements were separated from each other using a KU-2 cation exchange resin and a solution of ammonium α-hydroxyisobutirate as eluant. The separated samples were counted on a NaI(T1) γ-spectrometer.

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