Physical aspects of the lithium ion interaction with the imperfect silicene located on a silver substrate

Epitaxy of Si on a silver substrate is the main method to obtain silicene. The latter does not separate from the substrate. In the present paper, the possibility of using silicene on a silver substrate as an anode for lithium-ion batteries is studied by the method of molecular dynamics. Structural and mechanical effects arising from the motion of a Li + ion through a planar channel formed by a perfect and defective two-layer silicene are studied. Generally, the defect stability and silicene sheet integrity are independent of the Ag(001) or Ag(111) substrate type. The transverse vibrations of Si atoms in the channel have a significant effect on the motion of lithium ions. This effect is taken into account by using the interference factor that describes the slowing down of the motion of the Li + ion in the channel. The dependence of this coefficient on the size of vacancy defects in silicene is determined. The presence of the substrate makes this dependence less relevant. The stress distribution in the defective silicene while driving a lithium ion along the planar silicene channel is calculated. The strongest stresses in the silicene are created by forces directed perpendicular to the strength of the external electric field. These forces dominate in the silicene channel placed on the substrates of both types. © 2018, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved.Acknowledgements. This study is supported by the Russian Science Foundation (project no. 16‑13‑00061)

Molecular dynamics study of the stability of aluminium coatings on iron

Among the available protection systems for steel, the use of coatings is the most popular and economical method. One can protect the steel electrode from aggressive media with an aluminum coating. A thin Al film on an Fe substrate has been studied by the molecular dynamics method at a heating temperature from 300 K to 1500 K. A significant horizontal displacement of individual Al atoms on the edges of the film is observed during the simulation. The film begins to “spread” slightly near the edges. This “spreading” creates the conditions for the beginning of diffusion of iron atoms into aluminum. Some Al atoms were found to penetrate the Fe matrix at a temperature of 873 K. The total energy curve of the system shows both the melting transition in aluminum and phase transition from the body-centered cubic lattice to the face-centered cubic one at 1173 K. The binding energy for the Al atom in the lattice of the Fe crystal is smaller than that for Fe atoms. The calculated diffusion coefficients for Al and Fe have a significantly slower growth with a temperature in the range of 673 K ≤ T ≤1500 K. To describe the diffusion in a crystal using the molecular dynamics model, a temperature-dependent correction to the activation energy is calculated. The temperature dependence of the diffusion coefficient of aluminum atoms in an iron crystal can be represented as an Arrhenius expression with a temperature-dependent energy barrier for diffusion. © 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved

Kinetic test of a doped silicene-graphite anode element in a computer experiment

The stability of the system "bi-layer silicene on the graphite substrate" is studied in the molecular dynamics simulation. Silicene sheets are doped with phosphorus, and graphite sheets are doped with nitrogen. Lithium ion moves along a silicene channel with a gap in the range of 0.6-0.8 nm. The time for the ion to pass the channel and leave it decreases with an increase in the channel gap. There is a tendency of the silicene sheets roughness growth with an increase in the gap between silicene sheets (except, 0.75 nm). Doping phosphorus and nitrogen atoms stabilize the silicene and graphite structure. © 2020 Published under licence by IOP Publishing Ltd.Russian Science Foundation, RSF: 16-13-00061The study is supported by the Russian Science Foundation (project no. 16-13-00061)

Ab Initio Study of the Mechanism of Proton Migration in Perovskite LaScO3

The mechanism of proton motion in a LaScO3 perovskite crystal was studied by ab initio molecular dynamics. The calculations were performed at different temperatures, locations, and initial velocity of the proton. Different magnitudes and directions of the external electric field were also considered. It is shown that initial location and interaction between proton and its nearest environment are of great importance to the character of the proton movement, while the magnitude and direction of the initial velocity and electric field strength are secondary factors characterizing its movement through the LaScO3 crystal. Four types of proton-jumping between oxygen atoms are determined and the probability of each of them is established. Energy barriers and characteristic times of these jumps are determined. The probable distances from a proton to other types of atoms present in perovskite are calculated. It is shown that the temperature determines, to a greater extent, the nature of the motion of a proton in a perovskite crystal than the magnitude of the external electric field. The distortion of the crystal lattice and its polarization provoke the formation of a potential well, which determines the path for the proton to move and its mobility in the perovskite crystal. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.122020100205-5, FUME-2022-0005; Government Council on Grants, Russian Federation: 075-03-2022-011, FEUZ-2020-0037Funding: This work is partly supported by Government of Russian Federation, the State Assignment number FEUZ-2020-0037, registration number 075-03-2022-011; and is partly executed in the frame of the scientific theme of Institute of high-temperature electrochemistry UB RAS, number FUME-2022-0005, registration number 122020100205-5

Smoking as a medical and social problem among students of Kursk State Medical University

A study was conducted among smoking students of FGBOU VO KSMU. It was revealed that half of the respondents have smoking parents; some of the respondents have chronic or smoking-related diseases, the number and severity of which is directly dependent on the length of smoking; most of the respondents would like to get rid of nicotine dependence.Проведено исследование среди курящих студентов ФГБОУ ВО КГМУ. Выявлено, что половина респондентов имеет курящих родителей; часть опрошенных имеет хронические или ассоциированные с курением заболевания, количество и тяжесть которых находится в прямой зависимости от стажа курения; большинство респондентов хотели бы избавиться от никотиновой зависимости

Pedagogical Bases of Formation of Key Information Technology Competencies Polytechnic Institute Graduates

The article based on the analysis of the literature and experience in the field of economic education is considered a system of key concepts on the topic, as well as features of the introduction of competence approach in teaching practice Polytechnic Institute, the problem of realization competence approach in higher education, the formation of key information technology competencies, ensuring high availability Polytechnic Institute graduates to solve problems in the practice of the specialty, modern requirements to the society and the state system of vocational education at all levels, the task of creating these pedagogical conditions, which would help improve the quality of training of future specialists. This article lists didactic, psycho-pedagogical, organizational and pedagogical conditions that are necessary to improve the level of information technology training of future specialists. Their implementation will create the necessary information technology economist competence. Keywords: economic reforms, economic education, polytechnic education, competence, professionalism JEL Classifications: A10, A29, Q1

Discommensurational and Inhomogeneous States Induced by a Strong Magnetic Field in Low-Dimensional Antiferromagnets

Anisotropic antiferromagnetic systems of dimensionality greater than one in an external field are shown to exhibit a complicated array of ground states depending on the spin structure of the surface. The simplest structure that exhibits these effects is the spin ladder with the surface being the ladder end, which can be either compensated or non-compensated spins. The structure with the compensated end has a surface spin flop phase, the non-compensated end has a discommensurational phase, and the transition to these phases can be either first or second order with a tricritical point.Comment: 10 page