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Chemical modification of HA with PAA and PVP solutions prior to PMMA/HA composite synthesis gave rise to a significant improvement of the bending and impact strength as well as a hardness and emollescence temperature of the final product. Polymer-polymer complexes, formed as a result of chemical interaction of non-reacted (with HA calcium ions) carboxyl group of PAA with PVP at the interface of HA with PMMA, play a key role in this improvement. Using IR spectroscopy and X-ray photoelectron spectroscopy, it was shown that all components of PMMA/HA composite can be linked together either by ionic bonds or by hydrogen bonding. This significantly enhances the mechanical properties of such bioactive polymer systems, and their functionality as an implant material. [ABSTRACT FROM AUTHOR]

Geochemical studies of volcanic glasses (obsidians and perlites) from geological outcrops (N = 80) and archaeological collections (N = 110) were performed in order to determine source provenance in Primorye (Russian Far East), using neutron activation analysis and X–ray fluorescence spectrometry. Three major sources of archaeological volcanic glass were identified, two relatively local and one more remote. Several minor sources detected in the archaeological assemblage have not been located. This study suggests that long–distance obsidian exchange between Primorye and adjacent North–East Asia has existed since c. 10 000 BP. [ABSTRACT FROM AUTHOR]

Polyarylate has been used as a model polymer to study its tribological property alteration during impregnation of copper(II) hexafluoroacetylacetonate in a supercritical carbon dioxide environment followed by thermal decomposition of the copper compound in air. The initial, impregnated and thermally treated polymer samples were tested by various tribological techniques to compare their wear resistance, friction coefficient fk and surface microhardness H. SEM, EDX and ESCA have been applied to determine surface and internal domain morphology, profiles of copper complex concentration, its types and influence on the tribological properties of the samples. Dramatic surface layer modification and significant enhancement of its wear resistance (more than 400%) due to this process have been observed and discussed. [ABSTRACT FROM AUTHOR]

A series of studies was carried out at the Kaplanov kudurs in the upper reaches of the Kolumbe river (the territory of Sikhote-Alin biosphere reserve, Russia) in order to confirm the “rare earth” hypothesis as one of the possible causes of geophagy and consumption of mineralized spring water on kudurs. The mineral and chemical content of spring water and mineral soils of lithogenic substances, consumed by animals at the Kaplanov kudurs in the upper reaches of the Kolumbe river (the territory of Sikhote-Alin biosphere reserve, Russia). Previously unknown data on microelement composition of the minerals consumed by animals was received. It was found that the composition of water of various kudurs differs immensely and forms mainly in restored gley environments (sometimes in restored environments with high concentrations of sulfates). It was also found out that the microelement composition in spring waters can significantly vary over time. When this happens, the most variable are Al, Fe, Co, Ni, Cu, Zn, Ba, Sr, and some rare metals from the rare earth elements (REE) group and lanthanides. It was confirmed that one of the elements which attracts the animals in spring water and in “edible” subsoils is Na. However, Na is not the only element, which is searched by the animals at the kudurs, as consumed water and soil on some kudur contain an insignificant amount of it with simultaneously increased concentrations of a number of trace elements, including from the group REE. [ABSTRACT FROM AUTHOR]