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[en] Within the framework of the BEST experiment project, a calorimetric system was developed to measure the activity of high-intensity (several MCi) neutrino sources based on 51Cr. In the range of thermal capacities of 250–520 W, the uncertainty of the heat release measurement is less than 0.25%. Taking into account the uncertainty of the energy release value for the 51Cr decay (0.23%), the activity of the neutrino source can be determined with an accuracy of ∼0.5%.
[en] The 51Cr method for measurement of red cell survival is applicable only in the steady state of equation between red cell production and destruction and stable red cell mass. When there is a change in red cell mass due to blood loss, hemolysis, suppression of red cell production or ineffective erythropoiesis, the result is often misled. In this paper effect of blood loss on 51Cr red cell survival during the study is presented.
[en] The relative amount of chromium excreted in rat bile after injection of Cr-III is much less than after injection of Cr-VI, about 0.1% and from 6-8% during 5 hours respectively, for corresponding dose levels. The liver to bile ratio was 50-100 for Cr-III injection for Cr-VI the ratio was 2-3. With doses up to 18 μmol Cr/kg, only Cr-III was found in bile even after injection of CR-VI.Glutathione depletion of the liver with cyclohexene oxide decreased chromium excretion in bile. Such treatment also decresed the reduction of Cr-VI to Cr-III in the liver cell as only Cr-VI was found in bile. A different distribution of Cr-III in the liver dependent on whether derived from Cr-VI or taken up by the liver as such must be assumed. Taking into account the usual low penetration of biological membranes by Cr-III, a possible active transport mechanism or a specific diffusable Cr-III compound must be postulated. (author)
[en] The Kinetics of exchange of radiochromium atoms between the two aqueoustable ions of chromium was studied as a function of reaction temperature, reaction time, pH and chromium species concentration. Reaction mistures with only Cr(III) and 51Cr(III) show no 51Cr(VI) while mixtures of Cr(VI) and 51Cr(VI) give 51Cr(III) via acid reduction. Mixtures of Cr(III) and Cr(VI) with either 51Cr(VI) or 51Cr(III) show exchange. The contributions of reduction and exchange to the final product mixture were determined. (author)
[pt]A cinetica da troca de cromio-51 entre os estados de oxidacao estaveis do cromio em solucao aquosa foi estudada em funcao da concentracao destas especies, do pH e da temperatura e tempo de reacao. Nao foi observada formacao de 51Cr(VI) em solucoes contendo somente Cr(III) e 51Cr(III), enquanto misturas com Cr(VI) e 51Cr(VI) formam 51(III) por reducao acida. Mistura-se de Cr(III) e Cr(VI) com Cr(VI) ou 51Cr(III) mostram, respectivamente, 51Cr(III) ou 51Cr(VI), por reacoes de trocas e reducao. As contribuicoes de troca e de reducao para a formacao dos produtos finais foram determinadas. (autor)