Magnetic States in Ensemble of Ferromagnetic Nanoparticles in Cu-Mn-Al Alloy.

Two Cu-Mn-Al samples of different compositions were studied: one exhibiting martensitic transformation, another without structural transition. X-ray diffraction and magnetic measurements demonstrate that different magnetic behaviors of alloys originate from different concentrations and sizes of ferromagnetic nanoparticles, which appear after solid solution decomposition.Estimation of magnetic moments of ferromagnetic nanoparticles from magnetization curves was performed using Langevin function and compared to those obtained from X-ray examination. Granular systems are known to show giant magnetoresistance. Therefore, magnetoresistance of Cu-Mn-Al melt-spun ribbons after different aging times was measured. The study has shown that increase in the concentration of Mn atoms and time of aging in Cu-Mn-Al alloy leads to an increase in the amount of precipitated phase appearing as ferromagnetic nanoparticles.

[The adaptive reaction of the blood lymphocytes in persons subjected to chronic radiation exposure at low doses]. / Adaptivnaia reaktsiia limfotsitov krovi liudei, podvergshikhsia khronicheskomu vozdeistviiu radiatsii v malykh dozakh.

The changes in the PHA-stimulated human blood lymphocytes of the peoples from Moscow and from polluted after Chernobyl disaster Bryansk region were studied. The decrease in lymphocyte mitotic index in residents from polluted regions was revealed. Moscow population was not distinguished from Bryansk region population by the frequency of cells with micronuclei. There was also no difference in frequency of micronuclei after 1 Gy irradiation of the these populations. The adaptive response (irradiation with a dose of 0.05 Gy followed by 1.0 Gy irradiation 5 hours later) was studied. The decrease in the number of individuals with adaptive response and appearance of the individuals with increased radiosensitivity in the population of polluted regions were observed. There was no such subpopulation among the Moscow residents. So, firstly, low dose chronic irradiation is not an adaptive factor; secondly, the determination of adaptive response can be methodological procedure for the revealing the changes which were induced by low dose chronic irradiation (accompanied by other environment agents).

[Results of experimental radiobiological studies made within the 10-kilometer zone of the Chernobyl AES accident]. / Itogi éksperimental'nykh radiobiologicheskikh issledovanii v 10-kilometrovoi zone avarii na ChAES.

A study was made of the effect of high radioactive contamination on the animal organism (C57BL/6 mice) and HeLa cell culture within the ten-kilometer zone of the Chernobyl A.P.S. accident. The total radiation dose, as calculated by a gamma-component, was 0.09 to 2 Gy. A long-term exposure of mice within the zone (cumulative dose of 1.8 to 2 Gy) caused a significant decrease in bone marrow stem potencies and changes in the brain vascular system; subsequent acute exposure of animals increased interferon titres in the serum to a much greater extent than a single acute exposure did. As to HeLa cells, irradiation there of with doses of 0.09 to 0.4 Gy during 15-20 postirradiation generations caused a decrease in the proliferative activity, an emergence of cells with micronuclei and of giant cells, and remote cell death.