Comparing VVR-M reactor fuel assembly heat technological capabilities

Translated from Atomnaya Énergiya, Vol. 67, No. 2, pp. 97–100, August, 1989.     

Cardioinotropic Effects in Subchronic Intoxication of Rats with Lead and/or Cadmium Oxide Nanoparticles

Subchronic intoxication was induced in outbred male rats by repeated intraperitoneal injections with lead oxide (PbO) and/or cadmium oxide (CdO) nanoparticles (NPs) 3 times a week during 6 weeks for the purpose of examining its effects on the contractile characteristics of isolated right ventricle trabeculae and papillary muscles in isometric and afterload contractions. Isolated and combined intoxication with these NPs was observed to reduce the mechanical work produced by both types of myocardial preparation. Using the in vitro motility assay, we showed that the sliding velocity of regulated thin filaments drops under both isolated and combined intoxication with CdO–NP and PbO–NP. These results correlate with a shift in the expression of myosin heavy chain (MHC) isoforms towards slowly cycling β–MHC. The type of CdO–NP + PbO–NP combined cardiotoxicity depends on the effect of the toxic impact, the extent of this effect, the ratio of toxicant doses, and the degree of stretching of cardiomyocytes and muscle type studied. Some indices of combined Pb–NP and CdO–NP cardiotoxicity and general toxicity (genotoxicity included) became fully or partly normalized if intoxication developed against background administration of a bioprotective complex.     

Influence of the composition and structure of the glass-crystalline shell of cenospheres on helium permeability

We studied the interrelation between the composition, morphology, and helium permeability of the shell of narrow fractions of nonmagnetic nonperforated cenospheres extracted from cenosphere concentrates of fly ash of the sialic type with the use of technological stages of hydrodynamic, magnetic separation, sizing, and aerodynamic classification. For the interval of variation of Al₂O₃ content from 20 to 38 wt %, the regression equation [SiO₂]/[Al₂O₃] = 5.06 − 0.1[Al₂O₃] is established, with the correlation coefficient equal to −0.98. It is found that, together with the growth in the concentration of Al₂O₃ in the indicated interval, the content of the originally mullite phase increases from 1.3 to 42.4 wt %, and this is accompanied by the growth of the helium permeability of the glass-crystalline shell of the cenospheres.     

Some Characteristics of Free Cell Population in the Airways of Rats after Intratracheal Instillation of Copper-Containing Nano-Scale Particles

We used stable water suspensions of copper oxide particles with mean diameter 20 nm and of particles containing copper oxide and element copper with mean diameter 340 nm to assess the pulmonary phagocytosis response of rats to a single intratracheal instillation of these suspensions using optical, transmission electron, and semi-contact atomic force microscopy and biochemical indices measured in the bronchoalveolar lavage fluid. Although both nano and submicron ultrafine particles were adversely bioactive, the former were found to be more toxic for lungs as compared with the latter while evoking more pronounced defense recruitment of alveolar macrophages and especially of neutrophil leukocytes and more active phagocytosis. Based on our results and literature data, we consider both copper solubilization and direct contact with cellular organelles (mainly, mitochondria) of persistent particles internalized by phagocytes as probable mechanisms of their cytotoxicity.     

Preparation of <Superscript>48</Superscript>Ca and its use in experiments on synthesis of new superheavy elements

A procedure was developed for preparing metallic ⁴⁸Ca in a high yield. The starting ⁴⁸CaCO₃ was first calcined to ⁴⁸CaO and then mixed with Al powder. The charge was fired at 1200–1300°C in a specially designed reactor. The vapor of the released ⁴⁸Ca was condensed in the reactor zone cooled to room temperature. The process was monitored with ⁴⁷Ca tracer. Much attention was given to recovery of expensive ⁴⁸Ca from products of the aluminothermic process. The metallic ⁴⁸Ca obtained was used for generating a beam of ⁴⁸Ca⁵⁺ ions on an accelerator complex of FLNR JINR in experiments on synthesis of new superheavy elements.     

Effect of chromium compounds on the properties of ion-exchange membranes

The transport properties of ion-exchange membranes MK-40 and MF-4SK, MA-40, and MA-41 in solutions of sodium chloride, chromium(III) chloride, and chromium(VI) oxide have been studied. It has been found that the MA-40 and MA-41 membranes retain their transport properties in chromium chloride(III) solutions, whereas the anion-exchange membranes in chromium(VI) oxide solutions undergo partial or complete degradation. The oxidative impact of chromate ions on both the hydrocarbon matrix of the MK-40 membranes and the chemically resistant perfluorocarbon matrix of the MF-4SK membrane has been revealed.