SUBAQUEOUS STALACTOIDS IN THE DAL’NEE VERKHNEE LAKE OF THE SHULGAN-TASH CAVE (SOUTHERN URALS)

The relevance of the work is conditioned by the need for a comprehensive study of the mineralogical and microbiological parameters of the Shulgan-Tash (Kapova) cave, which is an archeological monument of universal importance. The purpose of the work: to describe findings of subaquatic stalactites in the Shulgan-Tash cave and to solve mineralogical and genetic issues. Research methodology: hydrochemical, electron microscopic and microbiological techniques of research were used in the present work. Results. This article describes subaqueous stalactoids for the first time in Russia. In the foreign literature they are called “Pool Fingers”. They are the carbonate forming with the origin, which is not yet definitely installed. They are emerging in the coastal zones of the cave waters. Subaqueous stalactoids were found in the Dal'nee Verkhnee lake on the second floor of the Shulgan-Tash cave 700 meters from the entrance. Subaqueous stalactoids are widespread along the Eastern and Western shores of the lake. They are thin and elongated aggregates of cream-colored up to a length of 30 cm, composed of calcite. They were formed in the lake of calcium bicarbonate type water with total mineralization of 390–510 mg/l, their hydrogen index is close to neutral (pH 6.8–7.3) and minor (not more than 5 mg/l) magnesium, sulfates and chlorides. Stalactitical surfaces are covered with the biofilm of the extracellular polymeric substances (EPS) and microorganisms. In their environment, the crystallization of calcite takes place. The “filaments”, whose taxonomic affiliation is not clear are found inside the units in the flattened strands of biological origin. Calcite is a block crystal subindividuals, which possess the elements of splitting. Their size is about 200–300 μm. The manifestation of skeletal crystal growth happens rather often. Researches prove the participation of microorganisms in the origin of subaqueous stalactoids. Apparently, filamentous bacterial mats play the role of the primers and a “framework", which provides a gravity-oriented growth of the aggregates. Extracellular polymeric substance (EPS) has the ability to form complex compounds with ions of Ca2+. It may indirectly lead to the precipitation of calcite. Conclusions. The microbial mediated genesis, similar to that described in the literature of the North American counterparts, was substantiated for the subaqueous stalactoids (Pool Fingers)

The relationship of gene polymorphisms of C-reactive protein with the development of myocardial infarction and formation of multifocal atherosclerosis in CHD patients

Purpose. To assess the contribution of the CRP gene polymorphisms rs3093077, rs1130864 and rs1205 in the development of myocardial infarction (MI) and multivessel disease (MVD) in CAD patients based on gender and age. Material and methods. 303 patients with stable coronary artery disease were included in the study. C-reactive protein (CRP) levels were measured by high sensitive immunoturbidimetric assay. The genotyping studies were performed in 96-well plates using the TaqMan assay. Results. Male gender and older age are proven to be among independent clinical predictors of myocardial infarction and the development of MVD in patients with coronary artery disease. The rs1205 C/C CRP homozygous carriers have a significantly higher risk of multivessel coronary lesions at age > 65, regardless of gender (OR = 4.72, 95 % CI = 1.27–17.56; p = 0.045). The C/C genotype of rs3093077, A/G of rs1130864 and P/T of rs1205 in female patients reduce the risk of myocardial infarction (OR = 0.53, 95 % CI = 0.30–0.95; p = 0.0079, OR = 0.37, 95 % CI = 0.16 – 0.82; p = 0.0027 and OR = 0.35, 95 % CI = 0.14–0.84; p = 0.0097, respectively). The groups with and without myocardial infarction were comparable by the allele frequencies and genotype distribution combinations of the CRP polymorphisms (rs3093077, rs1130864 and rs1205). Regardless of a positive history of MVD and myocardial infarction, serum levels of CRP over 3 mg/L indicates a high risk of cardiovascular events in patients with stable coronary artery disease. However, there is no relationship between protein levels and the polymorphisms of the genes encoding them (p = 0.56). Conclusion: The prediction of myocardial infarction and MVD requires not only assessing clinical and demographic data of patients, but also measuring CRP levels and studying its gene polymorphisms

Получение силуминов с использованием отходов кремниевого производства

The paper presents a review of existing methods to produce silumins. The possibility of obtaining foundry alloys using amorphous microsilica is shown. Different methods of adding SiO2 particles into molten aluminum are studied: in the form of aluminum powder — SiO2 master alloy tablets, particle mixing in the melt at the liquidus temperature and introducing SiO2 together with a stream of argon. The paper provides calculations of Gibbs energy formation and change enthalpy for silicon reduction by aluminum from its oxide. Calculations demonstrated the thermodynamic possibility of silumin production using amorphous microsilica. The effect of alloying additives and impurities on the silicon reduction behavior is determined. It is found that magnesium can be used as a surface-active additive to remove oxygen from dispersed particle surfaces and reduce silicon from its oxide. It is determined that the method of aluminum-silicon alloy production by introducing amorphous microsilica preheated to 300 °С into the aluminum melt (t = = 900 °С) together with argon stream (with subsequent intensive mixing) features higher efficiency since it ensures producing aluminum-silicon alloys containing more than 6 wt.% of silicon and microstructure of pre-eutectic foundry silumins. Industrial application of the proposed method will improve the efficiency of the existing silumin production process due to savings on purchasing commercial crystalline silicon. Moreover, this technology will minimize the environmental impact by reducing the volume and subsequent eliminating sludge fields used as landfills for storing dust from silicon gas treatment systems containing up to 95 wt.% of amorphous microsilica.Представлен обзор существующих способов производства силуминов. Показана возможность получения литейных сплавов с использованием аморфного микрокремнезема. Изучены и опробованы различные методы введения частиц диоксида кремния в алюминиевый расплав — в виде таблетированных лигатур «алюминиевый порошок— SiO2», путем замешивания частиц в расплав при температуре ликвидуса, а также введением SiO2 в расплав совместно с потоком аргона. Проведены расчеты энтальпии образования и изменения энергии Гиббса процесса восстановления алюминием кремния из его оксида, в ходе которых показана термодинамическая вероятность получения силуминов с использованием аморфного микрокремнезема. Определено влияние легирующих добавок и примесей на протекание процесса восстановления кремния. Выявлена возможность использования магния в качестве поверхностно-активной добавки, позволяющей удалить кислород с поверхности дисперсных частиц и восстановить кремний из его оксида. Определено, что способ получения литейных силуминов путем введения предварительно нагретого до 300 °С аморфного микрокремнезема в расплав алюминия (t = 900 °С) совместно с потоком аргона (с последующим интенсивным перемешиванием) обладает наибольшей эффективностью, поскольку позволяет получать алюмокремниевые сплавы с содержанием Si более 6 мас.% и микроструктурой, соответствующей доэвтектическим литейным силуминам. Промышленная реализации предложенного метода позволит повысить эффективность существующего технологического процесса получения силуминов за счет экономии ресурсов на приобретение товарного кристаллического кремния. Более того, внедрение этой технологии будет способствовать снижению экологической нагрузки на окружающую среду за счет сокращения объемов и последующей ликвидации шламовых полей, являющихся полигонами для хранения пыли систем газоочистки кремниевого производства, содержащей до 95 мас.% аморфного микрокремнезема