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1

Gamma radiolytic stability of CyMe4BTBP and the effect of nitric acid

Schmidt H., Wilden A., Modolo G., Švehla J., Grüner B., Ekberg C.

Nukleonika

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2015

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Vol. 60, No. 4, part 2

879--884

EN

The highly selective nitrogen donor ligand CyMe4BTBP for An(III) separation by solvent extraction was irradiated in a 60Co γ-source under varying conditions. Organic solutions of 10 mmol/L ligand in 1-octanol were contacted with different concentrations of nitric acid to observe the influence of an aqueous phase during irradiation. In subsequent liquid-liquid extraction experiments, distribution ratios of 241Am and 152Eu were determined. Distribution ratios decreased with increasing absorbed dose when irradiation was performed in the absence of nitric acid. With addition of nitric acid, initial distribution ratios remained constant over the whole examined dose range up to 300 kGy. For qualitative determination of radiolysis products, HPLC-MS measurements were performed. The protective effect of nitric acid was confi rmed, since in samples irradiated with acid contact, no degradation products were observed, but only addition products of the 1-octanol molecule to the CyMe4BTBP molecule.

2

Influence of alpha and gamma radiolysis on Pu retention in the solvent TBP/kerosene

Gao Y, Zheng W., Cao X., Chen S.

Nukleonika

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2014

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Vol. 59, No. 4

123--128

EN

In light of the issue of radiolysis of the solvent system in PUREX process, alpha and gamma radiation stability of tributyl phosphate (TBP)/kerosene (OK) have been studied in this paper, in which 238Pu dissolved in the organic phase and 60Co are selected as alpha and gamma irradiation sources, respectively. The amount of the degradation products not easily removed after the washing process has been measured by the plutonium retention. The effects of the absorbed dose, the TBP volume fraction, the cumulative absorbed dose and the presence of UO2 2+ and Zr4+ on the radiolysis of the solvents have been investigated. The results have indicated that the Pu retention increases with the increase of the absorbed dose after alpha or gamma irradiation, and is larger for the solvent containing less TBP. There is competition between UO2 2+ and Pu4+ to complex with the degradation products, and Zr4+ accelerates the radiolysis of the system.

3

Chromatographic determination of the products of gamma radiolysis of aqueous solutions of chlorophenoxy acid herbicides

Biesaga M., Stafiej A., Pyrzyńska K., Drzewicz P., Trojanowicz M.

Chemia Analityczna

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2005

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Vol. 50, No. 5

863-873

EN

In this study a reversed-phase HPLC procedure for the simultaneous determination of chlorophenoxy acid herbicides and their radiolytic degradation products has been elaborated. Satisfactory separation has been achieved with a mobile phase consisting of 60% 26 mmol L-1 acetic acid (pH 2.5} and 40% (v/v) acetonitrile. LOD values for herbicides andphenol derivatives were in the ranges of 19-41 μ L-1 and 10-60 μ L-1 respectively, applying spectrophotometric detection at 280 nm. The developed method has been applied for the monitoring of the efficiency of gamma radiolysis of commonly used herbicides:MCPA and dicamba.

PL

Wysokosprawna chromatografia cieczowa w odwróconym układzie faz została wykorzystana do oznaczania wybranych herbicydów chlorofenoksykwasowych oraz do analizy produktów ich radiolitycznego rozpadu - fenoli i chlorofenoli. Optymalne warunki rozdzielenia otrzymano przy zastosowaniu 60% kwasu octowego (26 mmol -1, ph 2,5) i 40% acetonitrylu jako fazy ruchomej z detekcjąspektrofotometrycznąprzy γ= 280 nm. Granice wykrywalności dla herbicydów i chlorofenoli wynosiły odpowiednio 19-41 μ L-1 i 10-60 μg L-1.Opracowana metoda została wykorzystana do monitorowania wpływu wielkości dawkipromieniowania na proces rozkładu powszechnie stosowanych herbicydów MCPA i dikamby.

4

Influence of protonation on the stability of disulfide radicals

Berges J., Fuster F., Silvi B., Jacquot J., Houee-Levin Ch.

Nukleonika

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2000

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Vol. 45, nr 1

23-29

EN

The ease of disulfide bond cleavage in peptides and proteins is evaluated by an experimental method (one-electron reduction by COOź- radicals and measurement of the chain length) and two theoretical approaches based on quantum chemistry and topology. All results agree to show acidcatalysis of this bond opening. The disulfide bond in the radical state is weakened by protonation.