Spectroscopic study of impurities and associated defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) meteorites

The results of spectroscopic and structural studies of phase composition and of defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) chondrites indicate that nitrogen atomic environment in meteoritic nanodiamonds (MND) is similar to that observed in synthetic counterparts produced by detonation and by the Chemical Vapour Deposition (CVD)-process. Most of the nitrogen in MND appears to be confined to lattice imperfections, such as crystallite/twin boundaries and other extended defects, while the concentration of nitrogen in the MND lattice is low. It is suggested that the N-rich sub-population of MND grains may have been formed with high growth rates in environments rich in accessible N (i.e., N in atomic form or as weakly bonded compounds). For the first time the silicon-vacancy complex (the "silicon" defect) is observed in MND by photoluminescence spectroscopy.Comment: 33 pages, 5 figures, submitted to Geochimica et Cosmochimica Act

Insight into effect of water additive on carbon remaining in metal alloys after high-pressure high-temperature diamond synthesis

In this study, we attempted to unravel the physicochemical grounds of the effect of water additive on diamond crystallization from a conventional metal-carbon system at high-pressure and high-temperature conditions. The microstructure and chemical state of carbon inclusions remained in a Ni-Fe alloy after the synthesis experiments at 6 GPa and 1370 degrees C with H2O additive of 0.18 and 0.53 wt% were examined by methods of scanning electron microscopy, X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy. It was found, that at the larger H2O concentration, the residual Ni-Fe-C system is enriched by sp(2)-hybridized carbon and oxygenated carbon, mainly in the carboxyl form. Our results suggest that formation of double bonds between carbon and oxygen atoms terminates tetrahedral hybridization of carbon, which is a necessary condition for nucleation and growth of diamond crystal, and promotes the formation of graphite-like phase. Thus, this study gives insight into the mechanism of diamond nucleation and growth in the presence of water in the metal carbon melt. (C) 2016 Elsevier B.V. All rights reserved

Analysis of Some Immunological Blood Indices of Experimental Animals when Administering Them Intact Lyposomes in Different Ways

State of immunity (cellular and humoral, natural resistance factors) was evaluated, functional and enzymatic activity of blood neutrophils was studied in experimental animals under administration of intact lyposomes in different ways (per os and intra peritoneum). The lyposomes were formed out of the lipids isolated from porcine brains. The lyposomes were shown to produce prolonged stimulating effect upon immunocompetent cells at any way of administration, this effect being more pronounced when preparations were injected intra peritoneum