125 research outputs found

    Bulk rock elastic moduli at high pressures, derived from the mineral textures and from extrapolated laboratory data

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    The elastic anisotropy of bulk rock depends on the mineral textures, the crack fabric and external parameters like, e.g., confining pressure. The texture-related contribution to elastic anisotropy can be predicted from the mineral textures, the largely sample-dependent contribution of the other parameters must be determined experimentally. Laboratory measurements of the elastic wave velocities are mostly limited to pressures of the intermediate crust. We describe a method, how the elastic wave velocity trends and, by this means, the elastic constants can be extrapolated to the pressure conditions of the lower crust. The extrapolated elastic constants are compared to the texture-derived ones. Pronounced elastic anisotropy is evident for phyllosilicate minerals, hence, the approach is demonstrated for two phyllosilicate-rich gneisses with approximately identical volume fractions of the phyllosilicates but different texture types

    Critical behavior of the fluctuation heat capacity near the glass transition of metallic glasses

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    The high-frequency shear modulus of five Zr-, Pd-, Cu-based conventional and two high-entropy bulk metallic glasses was measured in a wide temperature range up to the beginning of crystallization. Using these data and general thermodynamic relations, the "fluctuation" heat capacity ΔCf\Delta C_f determined by local structural fluctuations in the defect regions is introduced and calculated. It is found that ΔCf\Delta C_f temperature dependence for all metallic glasses has a large peak located slightly below or above the glass transition temperature but clearly lower than the crystallization onset temperature. The form of this peak resembles the characteristic λ\lambda-peak typical for order-disorder phase transitions. It is suggested that this ΔCf\Delta C_f-peak reflects certain underlying critical phenomenon. The critical temperature T0T_0 (peak temperature) and corresponding critical index α\alpha are determined. Averaged over all seven metallic glasses under investigation in the initial and relaxed states, the critical index α=0.26\alpha=0.26. The results obtained indicate that the fluctuations of thermal energy near the glass transition bear the marks of a continuous phase transition. However, the derived critical index is between those corresponding to a second-order phase transition (α0.1\alpha\approx 0.1) and a critical transition characterized by a tricritical point (α0.5\alpha \approx 0.5).Comment: 18 pages, 4 figure

    Description of Fischer Clusters Formation in Supercooled Liquids Within Framework of Continual Theory of Defects

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    Liquid is represented as complicated system of disclinations according to defect description of liquids and glasses. The expressions for the linear disclination field of an arbitrary form and energy of inter-disclination interaction are derived in the framework of gauge theory of defects. It allows us to describe liquid as a disordered system of topological moments and reduce this model to the Edwards--Anderson model with large-range interaction. Within the framework of this approach vitrifying is represented as a "hierarchical" phase transition. The suggested model allows us to explain the process of the Fischer clusters formation and the slow dynamics in supercooled liquids close to the liquid--glass transition point

    Laser Ablation Synthesis and Characteristics of Tm-Doped Gd2O3 Nanoparticles

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    Synthesis of nano-sized particles of thulium-doped gadolinium sesquioxide is reported. The nanopowder was obtained by laser ablation of solid target composed of a mixture of Tm2O3 and Gd2O3 powders using radiation of pulse-periodical CO2 laser. Morphological features, structural characteristics of nanoparticles and their densification behavior were investigated. It was shown that the as-synthesized nanopowder consists of loosely agglomerated particles with spherical shape and a diameter from 10 to 40 nm. It was revealed that the obtained sample is in the form of solid solution of Tm2O3 in Gd2O3 with monoclinic crystalline phase exhibiting the following lattice parameters: a = 14.095 Å; b = 3.571 Å c = 8.758 Å β = 100.182 °. Using X-ray diffraction analysis it was determined that, as opposed to other rare-earth sesquioxides (for instance, Y2O3 and Lu2O3), the phase transformation of monoclinic modification into cubic modification was not observed under thermal treatment at a temperature up to 1200 °C. This was also confirmed by an absence of stepwise variation in density of Tm:Gd2O3 compact which was evident for Gd2O3 sample prepared from powder with cubic phase and micro-sized particles. © Published under licence by IOP Publishing Ltd.The reported study was funded by RFBR and Sverdlovsk region, project number 20-48-660039

    Synthesis and Study of Nanopowders Based on Nd:(YXGd1-X)2O3 Solid Solution for Obtaining Active Laser Media

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    The paper reports on the possibility of obtaining nanopowders based on gadolinium oxide Gd2O3 stabilized with yttrium oxide Y2O3. The dependence of the stability of the cubic phase of gadolinium oxide Gd2O3 on the amount of the stabilizing additive was shown.Исследование выполнено при финансовой поддержке РФФИ и Свердловской области в рамках научного проекта № 20-48-660039

    Non-Waste Alternative Technologies in the Production of Heterologous Anti-Rabies Immunoglobulin

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    Presented is a comprehensive approach to utilization of the wastes that appear in the process of heterologous anti-rabies immunoglobulin production (packed red cells, fibrin, and alcohol-containing products). Specific immunoglobulin is extracted from the surface of red blood cells using desorption technique. Additional yields of immunoglobulin after exposure of erythrocytes to non-ionic detergent amount to 10-19 % of the output. Rich protein supplement feeding for horses-producers is obtained from spray-dried packed red cells. Solid nutritious substrate for microbiological media production is obtained from fibrin using enzymic hydrolysis method. The efficiency of the fibrin hydrolysate-based media is 1.5-2 times higher in comparison with that of the media based on the digest of meat and casein, as demonstrated by the results of Vibrio cholerae scaled cultivation. Furthermore, worked out is the technology of ethanol regeneration after the rivanol-ethanolic precipitation of gamma globulin, alcohol content by volume being (93±1) % after the regeneration. It is demonstrated that the regenerated alcohol can be used as a precipitator in the process of anti-rabies serum fractioning. All in all, the developed techniques make it possible to utilize the wastes of anti-rabies immunoglobulin production and provide for further use of derivatives while producing medical immunobiological preparations

    INFLUENCE OF Sc2O3 ADDITIVES ON STRUCTURAL AND SPECTROSCOPIC CHARACTERISTICS OF TRANSPARENT TM:(Y,Sc)2O3 CERAMICS

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    Synthesis, microstructure features and spectroscopic characterization of mixed sesquiox-ide Tm:(Y,Sc)2O3 transparent ceramics are reported. The absorption and emission cross sec-tion spectra were studied and the impact of different Sc content on structural and spectro-scopic properties was assessed.Работа выполнена при финансовой поддержке РФФИ в рамках научного проекта №18-53-7815 Итал_т и проекта CNR SAC.AD002.020.016

    Coping Responses During the COVID-19 Pandemic: A Cross-Cultural Comparison of Russia, Kyrgyzstan, and Peru

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    Background. The COVID-19 pandemic has subjected people around the world to severe stress, evoking a variety of coping responses. Coping responses can be broadly classified into four strategies: 1) problem-focused coping; 2) emotion-focused coping; 3) socially supported coping; and 4) avoidance. While there is a wide variability of individual coping responses, to some extent they are also culturally specific. Objective. This study aimed to compare the differences in the prevalence and factor structure of coping responses during COVID-19 pandemic in three countries: Russia, Kyrgyzstan, and Peru. Design. The sample included 501 participants from Russia, 456 participants from Kyrgyzstan, and 354 participants from Peru. The mean age of participants was 28 years in Russia (SD = 13.5); 24 years in Kyrgyzstan (SD = 10.0); and 30 years in Peru (SD = 12.3). In Russia and Kyrgyzstan, coping strategies were assessed with an abbreviated Russian adaptation of the COPE (Coping Orientations to Problems Experienced) questionnaire. In Peru, coping responses were assessed using the Spanish version of the Brief COPE questionnaire. The average scores from fifteen COPE scales were used as the input data for linear modelling and factor analysis. Results. The coping scores varied substantially within each country. Differences between countries accounted for 17.7% of the total variability in religious coping; 15.8% in acceptance; 13.9% in mental disengagement; and less than 7% in the other coping strategies. No difference in the prevalence of coping responses was found between Russian and Kyrgyz participants after accounting for age and gender. In all three countries the coping responses were associated with the same four coping domains: problem-focused coping, socially supported coping, avoidance, and emotion-focused coping. Four factors explained up to 44% of the total variation in the COPE scores. Religious coping and mental disengagement were classified into different coping domains in the three countries. Conclusion. The results suggest that during the COVID-19 pandemic, people from different countries apply the full range of coping responses within the four universal coping strategies. Religious coping and mental disengagement differed the most across the countries, suggesting that some coping behaviors can take on different roles within the system of coping responses to stressful events. We attribute these differences to differing cultural and socioeconomic characteristics, and the different measures taken by governments in response to COVID-19. © 2020. Lomonosov Moscow State University. All Rights Reserved.is study was supported by Russian Foundation for Basic Research (Project No. 20-04-60394)

    Brown bear attacks on humans : a worldwide perspective

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    The increasing trend of large carnivore attacks on humans not only raises human safety concerns but may also undermine large carnivore conservation efforts. Although rare, attacks by brown bears Ursus arctos are also on the rise and, although several studies have addressed this issue at local scales, information is lacking on a worldwide scale. Here, we investigated brown bear attacks (n = 664) on humans between 2000 and 2015 across most of the range inhabited by the species: North America (n = 183), Europe (n = 291), and East (n = 190). When the attacks occurred, half of the people were engaged in leisure activities and the main scenario was an encounter with a female with cubs. Attacks have increased significantly over time and were more frequent at high bear and low human population densities. There was no significant difference in the number of attacks between continents or between countries with different hunting practices. Understanding global patterns of bear attacks can help reduce dangerous encounters and, consequently, is crucial for informing wildlife managers and the public about appropriate measures to reduce this kind of conflicts in bear country.Peer reviewe
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