Coexistence of Superconductivity and Charge Density Waves in Tantalum Disulfide: Experiment and Theory.

The coexistence of charge density wave (CDW) and superconductivity in tantalum disulfide (2H-TaS_{2}) at low temperature is boosted by applying hydrostatic pressures to study both vibrational and magnetic transport properties. Around P_{c}, we observe a superconducting dome with a maximum superconducting transition temperature T_{c}=9.1 K. First-principles calculations of the electronic structure predict that, under ambient conditions, the undistorted structure is characterized by a phonon instability at finite momentum close to the experimental CDW wave vector. Upon compression, this instability is found to disappear, indicating the suppression of CDW order. The calculations reveal an electronic topological transition (ETT), which occurs before the suppression of the phonon instability, suggesting that the ETT alone is not directly causing the structural change in the system. The temperature dependence of the first vortex penetration field has been experimentally obtained by two independent methods. While a d wave and single-gap BCS prediction cannot describe the lower critical field H_{c1} data, the temperature dependence of the H_{c1} can be well described by a single-gap anisotropic s-wave order parameter.

Complex study of air pollution in electroplating workshop.

A comprehensive analysis of the state of air inside an industrial workshop with electroplating production was carried out. The data of quantitative distribution of suspended particles by size fractions (PM0.3, PM0.5, PM1, PM3, PM5, PM10) are presented for 15 main processes of electroplating. Morphometric and chemical composition of the surface of particles were studied. We observed particles of rounded shape, various agglomerates with complex geometric shapes, acute-angular particles, which when inhaled pose a maximum threat to human health. Chemical analysis of these particles showed an absolute predominance of oxides of non-ferrous metals, the percentage of which varied depending on the type of electroplating bath. The content of highly hazardous substances of the 1st (Zn, Pb, and Cd) and the 2nd (Cu, Cr, Ni, Co, and Mo) hazard classes in each sample was recorded.

Pressure-induced metallization in layered ReSe2.

The evolution of the crystal structure and electrical transport properties of distorted layered transition metal dichalcogenide ReSe2 was studied under high pressure up to ~90 GPa by Raman spectroscopy and electrical resistivity measurements accompanied by ab initio electronic band structure calculations. Raman spectroscopy studies indicate an isostructural phase transition due to layer sliding at ~7 GPa, to the distorted 1T-phase which remains stable up to the highest pressures employed in these experiments. From a direct band gap semiconductor at ambient pressure, ReSe2 undergoes pressure-induced metallization at pressures ~35 GPa, in agreement with the ab initio calculations. Resistivity measurements performed with different loading conditions reveal the possible emergence of superconductivity, which is most likely not an intrinsic property of ReSe2, but is rather conditioned by internal stresses upon compression.

Atomic and electronic structures evolution of the narrow band gap semiconductor Ag2Se under high pressure.

Non-trivial electronic properties of silver telluride and other chalcogenides, such as the presence of a topological insulator state, electronic topological transitions, metallization, and the possible emergence of superconductivity under pressure have attracted attention in recent years. In this work, we studied the electronic properties of silver selenide (Ag2Se). We performed direct current electrical resistivity measurements, in situ Raman spectroscopy, and synchrotron x-ray diffraction accompanied by ab initio calculations to explore pressure-induced changes to the atomic and electronic structure of Ag2Se. The temperature dependence of the electrical resistivity was measured up to 30 GPa in the 4-300 K temperature interval. Resistivity data showed an unusual increase in the thermal energy gap of phase I, which is a semiconductor under ambient conditions. Recently, a similar effect was reported for the 3D topological insulator Bi2Se3. Raman spectroscopy studies revealed lattice instability in phase I indicated by the softening of observed vibrational modes with pressure. Our hybrid functional band structure calculations predicted that phase I of Ag2Se would be a narrow band gap semiconductor, in accordance with experimental results. At a pressure of ~7.5 GPa, Ag2Se underwent a structural transition to phase II with an orthorhombic Pnma structure. The temperature dependence of the resistivity of Ag2Se phase II demonstrated its metallic character. Ag2Se phase III, which is stable above 16.5 GPa, is also metallic according to the resistivity data. No indication of the superconducting transition is found above 4 K in the studied pressure range.

Structure and electrical resistivity of mixed-valent EuNi2P2 at high pressure.

The structural properties and electrical resistivity of homogeneous mixed-valent EuNi2P2 are studied at pressures up to 45 GPa. No structural phase transition is observed in the whole pressure range and the overall pressure behavior of the structural parameters is similar to that of related compounds in the collapsed tetragonal ThCr2Si2-type structure. Electrical resistivity measured up to 31 GPa at temperatures between 4 and 300 K exhibits continuous changes from the behavior typical for a mixed-valent Eu system to that of a normal metallic system at pressures above 20 GPa, indicating a transition of the strongly mixed-valent Eu atoms with a valence ~2.5 towards a pure trivalent state. No superconductivity was observed in the whole studied pressure-temperature range.

[Ejaculatory disorders in some regions of the Russian Federation].

Ejaculatory disorders are one of the most frequent sexual dysfunction. To study this problem in different climatic regions, we made a population-based trial with participation of 543 Russian men (149 from the south of Russia, 394 from Siberia). Correlation of ejaculatory disorders with IELT duration, a testosterone level, comorbid chronic prostatitis was estimated. We found that 59.2% of young men had normal ejaculation but only 20% of men over 50 years of age. In the latter group of patients delayed ejaculation predominated. 43.6% of the southerners and 33.5% of the Siberians had premature ejaculation, and 6.1 and 16.9%--delayed ejaculation, respectively; 26.7 and 31.2% were hypogonadal, respectively. Ejaculation was normal in 74.6% men with a normal testosterone level. Hypogonadal patients had premature ejaculation in 48.2% cases, delayed ejaculation in 28.3%. Of the total 543 men, 67.2% had chronic prostatitis. Only 46% of patients with chronic prostatitis had normal ejaculation, 43.3% had premature ejaculation and 10.7% had delayed ejaculation. Thus, in cold climate delayed ejaculation occurs more often, in the South premature ejaculation predominates. A low testosterone level as well as chronic prostatitis resulted in ejaculatory disorders. There are significant differences in ejaculation between young and old men, whose living in the South and Siberia, eugonadal and hypogonadal. Therefore, when characterizing a copulative act as "normal" it is necessary to take into account age, comorbidity, region of living and other factors.

Phase stability of lithium azide at pressures up to 60 GPa.

We studied lithium azide (LiN(3)) by x-ray diffraction and Raman spectroscopy at hydrostatic compression up to pressures above 60 GPa at room temperature. The results of x-ray diffraction analyses reveal the stability of the ambient-pressure C 2/m crystal structure up to the highest pressure. The pressure dependence of librational modes provides evidence for an order-disorder transition at low pressures (below 3 GPa), similar to the transition observed previously at low temperatures. The observed structure stability indicates that this transition is not associated with structural changes. The phase stability of LiN(3) is in contrast to that of sodium azide (which is isostructural at ambient pressure), for which a set of phase transitions has been reported at pressures below 50 GPa.

Superconductivity in hydrogen dominant materials: silane.

The metallization of hydrogen directly would require pressure in excess of 400 gigapascals (GPa), out of the reach of present experimental techniques. The dense group IVa hydrides attract considerable attention because hydrogen in these compounds is chemically precompressed and a metallic state is expected to be achievable at experimentally accessible pressures. We report the transformation of insulating molecular silane to a metal at 50 GPa, becoming superconducting at a transition temperature of Tc = 17 kelvin at 96 and 120 GPa. The metallic phase has a hexagonal close-packed structure with a high density of atomic hydrogen, creating a three-dimensional conducting network. These experimental findings support the idea of modeling metallic hydrogen with hydrogen-rich alloy.

[Toxic effect of antituberculous drugs on spermatogenesis]. / Toksicheskoe vliianie protivotuberkuleznykh preparatov na spermatogenez.

To determine the impact of multidrug therapy on male sexual function, isoniazid was tested for their effects on spermatogenesis and the liver in an experiment on laboratory animals, then on spermatogenesis and spermatozoidal function by using the clinical data. There is evidence for that isoniazid given to mice produces no toxic effect on spermatogenesis. The drug in a dose of 0.5% fails to affect the mobility of spermatozoa in vitro. Combined antituberculous therapy does not cause any significant changes in the basic indices of a spermatogram in patients with different forms of tuberculosis. Intermittent combined antituberculous therapy does not result in the derangement of major constituents of a copulative act.

[Enzyme indicator of the immunobiologic activity of antigens]. / Fermentnyi pokazatel' immunobiologicheskoi aktivnosti antigenov.

The test-system has been elaborated for the determination of the ability of different antigens in the cultures of the mouse peritoneal macrophages. Measuring an intracellular acid phosphatase activity, reflecting the extent of the cell activation, was taken as a principle of this test-system. With the help of this test-system ability of a few antigens (lipopolysaccharide, polysaccharide, glycoprotein, protein and low molecular weight substances--peptide and glycopeptide) have been studied. It is testified that above mentioned antigens possessed different effects on the acid phosphatase activity.

[Characteristics of the immune status of female cattle breeders with chlamydia infections]. / Osobennosti immunogo statusa zhenshchin-zhivotnovodov s khlamidiinoi infektsiei.

Chlamydia urogenital infections cause significant changes in the immune status which can be regarded as immunopathologic disorders. Taking into account the wide prevalence of infections of this kind, particularly among female agriculture workers, as well as their pathogenicity and health-related consequences, Chlamydia Trachomatis cases must be properly revealed in women affected with inflammatory diseases of genitalia with subsequent etiotropic treatment.

[Preparative method of isolating influenza virus glycoproteins]. / Preparativnyi metod vydeleniia glikoproteinov virusa grippa.

Two preparative methods for isolation of biologically active glycoproteins from influenza virus A - hemagglutinin and neuraminidase, were elaborated. A three-step procedure involves solubilization of glycoproteins with nonionic (Triton N-101, TN) or cationic (cetylpyridinium chloride, CPC) detergents, separation from degraded virions by centrifugation, and removal of detergents and lipids by precipitation of the glycoproteins with butanol (TN), or, alternatively, precipitation of CPC upon cooling. Using virion concentration of approximately 1 mg/ml and optimal weight ratio of detergent to virus (protein) of approximately 20:1 (for TN) and 1:1 (for CPC), the glycoproteins were obtained with the overall yield of 70-80%. The isolated glycoproteins exhibit the same immunological and enzymatic activities as intact virus A/Texas/77 and A/Leningrad/80.