Features of the magnetic properties of Co/Si/Co thin-film systems

The magnetic properties of Co/Si/Co thin-film structures grown by magnetron sputtering have been studied using magnetooptical techniques. It is established that the saturation field (H S) of trilayers exhibits oscillations as a function of the thickness of the semiconductor (silicon) interlayer. This behavior is explained by structural features of the Co/Si/Co system and the presence of antiferromagnetic exchange coupling between magnetic layers via the silicon interlayer. © 2013 Pleiades Publishing, Ltd

On integration of the Kowalevski gyrostat and the Clebsch problems

For the Kowalevski gyrostat change of variables similar to that of the Kowalevski top is done. We establish one to one correspondence between the Kowalevski gyrostat and the Clebsch system and demonstrate that Kowalevski variables for the gyrostat practically coincide with elliptic coordinates on sphere for the Clebsch case. Equivalence of considered integrable systems allows to construct two Lax matrices for the gyrostat using known rational and elliptic Lax matrices for the Clebsch model. Associated with these matrices solutions of the Clebsch system and, therefore, of the Kowalevski gyrostat problem are discussed. The Kotter solution of the Clebsch system in modern notation is presented in detail.Comment: LaTeX, 24 page

Pt-CeO2-based composites in environmental catalysis: A review

The Pt–CeO2-based composites have brought about a vivid research interest due to their use in advanced combustion engines, proton-exchange membrane fuel cells, etc. Complementing features of Pt and ceria particles cause numerous applications of such composites in environmental catalysis science and technology. The present review summarizes recent advances in Pt–CeO2 chemistry and discusses the following key aspects: (1) catalyst preparation, including Pt and Ce-MOF-derived precursors, and treatment methods, (2) Pt-related factors: size, including single-atom formulations, and state, (3) CeO2-related factors: morphology, surface defects, and derived features, (4) modification of catalyst composition, including the formation of bimetallic particles, (5) nature and structure of active sites, (6) features of metal–support interaction. The range of covered environmental catalytic applications includes oxidation processes (CO oxidation, VOCs abatement, soot oxidation, combustion of vehicle exhausts, etc.), reduction of nitroaromatics, CO2 utilization (dry reforming of alkanes, CO2 reduction, etc.), and photocatalytic reactions

Development of layered anode structures supported over Apatite-type Solid Electrolytes

Apatite-type lanthanum silicates (ATLS) materials have attracted interest in recent literature as solid electrolytes for SOFCs. The fabrication of an ATLS based fuel cell with the state-of-art electrodes (NiO/YSZ as anode and LSCF or LSM as cathode) can show degradation after long operation hours due to Si diffusion mainly towards the anode. In this work, we report a “layer-by-layer anodic electrodes” fabrication by means of spin coating and physical spraying. The overall aim of this work is the successful fabrication of such a layered structure including suitable blocking layers towards the inhibition of Si interdiffusion from the apatite electrolyte to the anode. The results showed that the deposition of 3 layers of LFSO/GDC (3μm), NiO/GDC (4μm) and the final NiO/YSZ anode layer provided a stable half-cell, with no solid state reaction occurring among the electrodes and no Si diffusion observed towards the anode after thermal treatment at 800°C for 120h

Exercícios de equações diferenciais ordinárias

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Problems of Teaching Foreign Students under Conditions of the Pandemic

The article analyzes a process of teaching foreign students at regional universities under conditions of restrictions associated with the COVID-19 pandemic, using digital technologies. Currently, universities, and especially technical universities, play a leading role in the development and distribution of digital technologies. The authors believe that achieving these goals involves changing the content of academic disciplines and courses, including those aimed at improving digital literacy. The concept of combining a lecture system and e-learning technologies, which are provided by the electronic platform Microsoft Teams at the VSTU, is a modern format of the educational process. With a mixed format of educational process, the modular principle of organizing a curriculum of disciplines seems to be more appropriate. The authors analyze the results of the first stage of educational digitalization (the second semester of the 2019/20 academic year). This analysis is based on the academic performance of students (Russian and foreign) and the results of teachers’ and students’ survey on the effectiveness of distance learning. According to the results of educational analytics, the authors state, firstly, a decrease in the absolute academic performance of students while teaching with a help of the distance education technologies and e-learning, due to the low level of students’ self-organization and the lack of educational material in the digital format; secondly, a decrease in the quality of teaching, which demonstrates the unwillingness of teachers to use the potential of e-learning and, thirdly, the impossibility of a complete transfer of teaching to a digital environment. In addition, the authors describe the problems faced by regional universities in the process of educational digitalization and the implementation of the program of Russian education export

Laser-based synthesis of TiO2-Pt photocatalysts for hydrogen generation

The development of visible-light active titanium dioxide is one of the key challenges in photocatalysis that stimulates the development of TiO2-based composite materials and methods for their synthesis. Here, we report the use of pristine and Pt-modified dark titanium dioxide prepared via pulsed laser ablation in liquid (Nd:YAG laser, 1064 nm, 7 ns) for photocatalytic hydrogen evolution from alcohol aqueous solutions. The structure, textural, optical, photoelectrochemical, and electrochemical properties of the materials are studied by a complex of methods including X-ray diffraction, low-temperature nitrogen adsorption, electrophoretic light scattering, diffuse reflection spectroscopy, photoelectrochemical testing, and electrochemical impedance spectroscopy. Both the thermal treatment effect and the effect of modification with platinum on photocatalytic properties of dark titania materials are studied. Optimal compositions and experimental conditions are selected, and high photocatalytic efficiency of the samples in the hydrogen evolution reaction (apparent quantum yield of H2 up to 0.38) is demonstrated when irradiated with soft UV and blue LED, i.e., 375 and 410 nm. The positive effect of low platinum concentrations on the increase in the catalytic activity of dark titania is explained