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The article deals with the effect of stressful factors on the mental health of students. Stressful factors of the social environment require more in-depth study due to worsening mental health. Materials for the study were obtained in Chelyabinsk. 128 students from 18 to 23 years old engaged and not involved in physical education and sports were tested. Mental health components were diagnosed using a screening test. Results. Such social stressful factors were revealed as mental disorders and diseases, nervous tension, anger, mental stress and irritability that had statistically significant correlation coefficients and negatively affected mental health. The following components have a positive effect on mental health: permanent mood, psychological climate, the ability to optimize the mental status under stress, mental well-being. Conclusion. Statistically significant relationships between the integral indicator of mental health and all mental health components are identified. The revealed correlations indicate that the higher the numerical values of stressful factors (mental disorders and diseases, nervous and mental stress, irritability), the lower the integral indicator of mental health. Also, the higher the values of positive factors such as permanent mood, psychological climate, relationships with others, the ability to optimize the mental status under stress, the mental well-being, harmonious relationships, the higher the integral indicator of the mental health of students. [ABSTRACT FROM AUTHOR]

The paper presents numerical simulation of polycrystalline titanium deformation in terms of the crystal plasticity theory. Based on the experimental data, a three-dimensional polycrystalline model is generated by a method of step-by-step packing. Constitutive relations for the deformation behavior of grains are based on the crystal plasticity theory with regard to the crystalline structure and dislocation glide in hexagonal closepacked crystal lattices. The boundary value problem of elastoplastic deformation is solved numerically using the finite element method. The proposed model is tested by elastoplastic deformation of titanium single crystals having different orientation. The proposed model is used to study the influence of the crystallographic orientation on localized plastic deformation in polycrystals. [ABSTRACT FROM AUTHOR]

The results of an experimental study of hybrid X-pinches (HXPs) as sources of vacuum ultraviolet (VUV) radiation within the wavelength range of λ < 2000 Å are presented. A KING compact low-voltage generator (45 kV, 200 kA, 190 ns) was used to feed the X-pinches. The dynamics of forming the radiating plasma of HXPs of different materials were studied using pinhole cameras with radiation receivers based on microchannel plates with a time resolution of 5 ns and a spatial resolution of 150 µm. The time structure and energy characteristics of the radiation were studied using diamond photoconducting detectors (PCDs). The spectral composition of UV radiation was investigated using a spectrograph based on the transmission grating. It has been shown that the efficiency of conversion of the capacitor-stored energy to the VUV radiation may reach 5%, whereas the fraction of soft X-rays (SXR) with quanta energies above 800 eV is no more than 3%. In this case, the source brightness reaches 2 × 109 W/(sr cm2). [ABSTRACT FROM AUTHOR]

A comparative study of the relative antioxidant activity (RAA) of fullerene С60 and its amino acid derivatives is performed via amperometry and fluorimetry. The sizes of nanoparticles in the corresponding colloidal solutions are determined via dynamic light scattering (photon correlation spectroscopy) to study the effect the steric factors of the investigated compounds have on the magnitude of the RAA. Data are subjected to statistical correlation regression analysis using results obtained for the RAA dependence of fullerene С60 and salt forms of its acid derivatives on the corresponding sizes of nanoparticles in colloidal aqueous solutions. A close negative (inverse) correlation is identified between the size of nanoparticles in a solution and their antioxidant properties, with a pronounced synergic effect related to the influence of both chemical structure of the studied compounds and their structural organization in colloid solution. It is found that the structure of a substituent in a molecule of amino acid derivative of fullerene С60 also influences the size of the forming nanoparticles. At the same time, reductive properties of amino acid derivatives of fullerene С60 are generally determined by the electron effects of substituents. [ABSTRACT FROM AUTHOR]

Simulations of characteristic mesoscale processes in a solid require a computational domain with a large number of structural elements (grains, inclusions, pores, etc.) and a sufficiently detailed mesh for their approximation. Reasoning that the computer power needed for such simulation increases nonlinearly with the number of structural elements, it is desirable to minimize the computational costs without loss of information and accuracy, for example, by solving quasi-static problems in a dynamic statement. Here we analyze the applicability of dynamic methods to quasi-static micro- and mesomechanical problems with explicit account of microstructure by the example of dynamic and static finite element computations of uniaxial tension for materials insensitive to strain rates. The analysis shows that the main parameter influencing the coincidence of dynamic and static solutions is the time in which the loading rate rises to its amplitude. If this rise time is longer than two travels of an elastic wave through a material, the dynamic and static problem solutions deviate by no more than 0.1% while the random access memory and the computation time needed for the static case is about ten times those for the dynamic one. Thus, explicit dynamic methods can be applied to advantage to quasi-static problems of micro- and mesomechanics. [ABSTRACT FROM AUTHOR]

The initial stage of the nanosecond explosion of 1–15 μm-thick flat foils in a diode with a current of 40–80 kA is studied. Projection radiography is used to take images of exploded foils at a spatial resolution of 3–4 μm using the soft X-ray radiation (E = 2.5–5 keV) of a hybrid X-pinch and at a time resolution of 0.1 ns. Foil strips 0.3–2 mm wide and 0.5–7 mm long were introduced in the return circuit of the diode in a high-current BIN generator with a current amplitude of 270 kA and a current rise time of 100 ns; the main load of the generator is an X-pinch. The experiments demonstrate that small-scale structures, the shape and the size of which depend on the foil material and the current density and distribution in a foil, are formed in a foil. Possible scenarios of the structure formation are discussed. [ABSTRACT FROM AUTHOR]

At present, the focus is on solving the urgent problem of reliable performance of power system elements and ensuring their efficient operation during mining. A methodological approach is considered that allows assessing the reliability level of low-voltage asynchronous electric motors in a coal mine with difficult geological and climatic mining conditions. The object of the study is asynchronous electric motors used at one of the enterprises of Siberian Coal Energy Company (SUEK) in Trans-Baikal territory. The main tool for implementing the research objectives was program MATLAB/Simulink. The purpose of the article is to study the influence of external operational factors on the service life of an asynchronous electric motor with a squirrel-cage rotor. A comprehensive solution to issues aimed at maintaining the reliability level of asynchronous electric motors is one of the priority areas, mainly aimed at ensuring the effective functioning of a coal mining enterprise.

The results of studying instabilities in flat aluminum 4-μm-thick foils exploded using the GVP generator with a short circuit current of 10 kA and a current rise time of 350 ns are presented. The dynamics of foil destruction during the explosion was studied using laser probing. During the experiments, it was ascertained that in the presence of the two-dimensional structure of foil, the growth rates of instabilities and their nature depend on the foil orientation relative to the direction of current flow. The conditions are cleared up, under which during the explosion of foils with two-dimensional inherent structures, the development of instabilities is slowed down. [ABSTRACT FROM AUTHOR]