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The mechanical and elastic properties of new silicon nitride fabricated by cold isostatic pressing and free sintering are considered. Young's modulus, Poisson's ratio and shear modulus of investigated ceramic were determined. An indentation technique for measuring the indentation modulus was developed. The flexural strength, the compressive strength and the fracture toughness were investigated. Young's modulus of the obtained material was 240GPa by resonance and 214GPa by mechanical tests. The microhardness was 1380 HV0.5 and 970 HK2.5. Obtained silicon nitride ceramic is one of a candidate material for a wide range of structural applications due to its high density (2.94g/cm3) and low open porosity (0.1%). © 2015 Elsevier Ltd and Techna Group S.r.l. Source

Kravchuk T.N.,Novotek LLC | Sergeev S.V.,Belgorod national research University
Gornyi Zhurnal

There is offered the method of protection of capital support of ventilation-auxiliary shaft from agressive impact of underground waters of Middle-Cambrian water-bearing complex in complicate hydrogeological conditions of open-cast and underground mining of Udachnaya kimbelite pipe in the range zone of permafrost (in the northern part of Yakutia). Such protection is carried out by the decreasing of the level of underground waters in the area of shaft by drainage complex of back holes. Underground waters of Middle-Cambrian water-bearing complex are high-pressure. These waters are characterized by high mineralization and gas saturation. Method of numerical modeling with application of the MODFLOW program of GMS system was used for the purpose of substantiation of this method of shaft protection from aggressive impact of underground waters. There was made a calculation hydrogeological scheme of the area of filtration of underground waters of the researched region. There were specified the filtration parameters of waterbearing rocks of Middle-Cambrian water-bearing complex on the stage of solving of opposite problem. The distribution of the level of underground waters of Middle-Cambrian water-bearing complex on the model of regional and local scales was obtained, according to the results of forecast task. There was defined the necessary amount of rising drainage holes with stated production capacity, required for the reaching of efficient decreasing of the level of underground waters in the area of vertical shaft of Udachny underground mine. Source

In this study we examined evolutionary processes in the populations of small mobile animal species, the terrestrial mollusks Chondrula tridens Müll. (Ch. tridens) in the urbanized landscape. We applied PCR methodology, using the RAPD and ISSR DNA markers, to define the genetic structure in the Ch. tridens populations, inhabiting the Mid-Russian Upland. Analysis of the obtained DNA patterns uncovered the presence of both polymorphic and monomorphic alleles. Based on this data, we defined the levels of genetic variability in the studied Ch. tridens populations, and determined the factors affecting formation of the population’s gene pool in this species. We present our conclusions on the genome structure and gene pool distribution in the populations of the Ch. tridens in the urbanized landscape. © 2014, Pleiades Publishing, Ltd. Source

Studies on the gene pool structure in ten populations of the bush snail Bradybaena fruticum Müll. inhabiting the southern Central Russian Upland were performed with a time interval of 14 years, in 1996 and 2010. Significant changes were revealed in allele frequencies and the level of genetic diversity. Using the temporal method (Krimbas and Tsakas, 1971; Nei and Tajima, 1981), the effective population size was calculated for the studied groups of mollusks. Specific features of the metapopulation structure of Br. fruticum in an urbanized landscape are discussed. © 2015, Pleiades Publishing, Ltd. Source

Shul'ga N.F.,National Science Center Kharkov Institute of Physics and Technology | Syshchenko V.V.,Belgorod national research University
Journal of Surface Investigation

The scattering of a plane electromagnetic wave at a filamentary target is considered. The obtained expression for the scattering cross-section is used to derive a kinetic equation describing wave propagation in a parallel-fiber bundle. The intensity evolution of radiation propagating in a bundle of straight and bent fibers is considered. It is shown that there are conditions under which the radiation-intensity maximum shifts following the bending of a fiber bundle. © 2015, Pleiades Publishing, Ltd. Source

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