Increasing the resistance of a NiCrBSi coating to heat wear by means of combined laser heat treatment

Testing of NiCrBSi coatings formed by gas-powder laser cladding and combined laser heat treatment, including laser cladding and high-temperature annealing, were conducted under conditions of sliding friction on the Kh12M steel according to the pin-on-disk scheme. The combined processing resulting in the formation of large carbides and chromium borides in the coatings is shown to increase their wear resistance by a factor of 1.8 at sliding velocities of 6.1 and 9.3 m/s, when there is significant frictional heating of the friction surfaces. © 2018 Author(s)

BETULIN-3, 28-DIPHOSPHATE SALT COMPLEXES WITH AMINES AND THEIR ANTIOXIDANT ACTIVITY

Objective: Studies of composition, stability and antioxidant properties of the betulin-3, 28-diphosphate complexes with dopamine and trisamine.Methods: The betulin-3, 28-diphosphate (BDP) interaction with amines in a water-alcohol medium was studied by using spectral methods and potentiometric titration. Biochemical indexes such as catalase, superoxide dismutase (SOD), lactate dehydrogenase (LDH) activities and malondialdehyde (MDA) level were estimated in experiments on rats.Results: BDP was synthesized using betulin by POCl3 treatment in the presence of pyridine in dioxane. The complexation of BDP with amines was confirmed by the 31P-NMR and FTIR-spectral data. The stoichiometry of BDP-dopamine complexes was equal to 2:1 and 4:1 and its complexes with trisamine were produced in the ratio 1:1 in a water-alcohol medium. The conditional stability constant К′st of the BDP-trisamine complex is 1130±55 mol∙l-1. BDP-Tris complex improved SOD activity up to 30% and up to 105% in the presence of cytostatic-hydrazine sulfate. The MDA level in erythrocytes decreased up to 57% and in combination with cytostatics (5-fluorouracil and hydrazine sulfate)-up to 11-14%. The catalase activity increased by 44-94% and MDA level in erythrocytes decreased by 22-53% under the action BDP-DA complexes that depends on the dose.Conclusion: The BDP forms stable complexes with trisamine and dopamine that make it possible to use this compound as a component of drug delivery system for high toxicity cytostatics and for readily oxidized catecholamines. It has been shown that both its complexes with amines and the combination with cytostatics enhanced antioxidant activity in an experiment in vitro

Eddy-current testing of fatigue degradation in additionally heat-treated gas powder laser clad NiCrBSi coating under contact fatigue loading

The paper studies the applicability of eddy-current technique to testing fatigue degradation in Ni-18.2Cr-3.3B-4.2Si coating, produced by gas powder laser cladding and subjected to additional high-temperature annealing at 1025 °C, under contact loading. It is demonstrated that eddy-current testing of fatigue degradation in Ni-18.2Cr-3.3B-4.2Si coating under contact loading after high-temperature annealing has certain limitations caused by the high brittleness of this coating. In this case, it is possible to test only a sharp increase in the sizes of contact damages, which occurs at 8×10 5 cycles under these loading conditions and results from the formation of a great number of peripheral ring cracks in the fracture zone; the eddy-current readings α decrease due to the increasing electrical resistivity of the coating. Testing can be performed by eddy-current measurements at high excitation frequencies of an eddy-current transducer (f=72-120 kHz), when the effect of the ferromagnetic steel base on the eddy-current readings α is minimum. © 2018 Author(s)

Eddy-current testing of fatigue degradation upon contact fatigue loading of gas powder laser clad NiCrBSi-Cr 3 C 2 composite coating

The possibilities of the eddy-current method for testing the fatigue degradation under contact loading of gas powder laser clad NiCrBSi-Cr 3 C 2 composite coating with 15 wt.% of Cr 3 C 2 additive have been investigated. It is shown that the eddy-current testing of the fatigue degradation under contact loading of the NiCrBSi-15%Cr 3 C 2 composite coating can be performed at high excitation frequencies 72-120 kHz of the eddy-current transducer. At that, the dependences of the eddy-current instrument readings on the number of loading cycles have both downward and upward branches, with the boundary between the branches being 3×10 5 cycles in the given loading conditions. This is caused, on the one hand, by cracking, and, on the other hand, by cohesive spalling and compaction of the composite coating, which affect oppositely the material resistivity and, correspondingly, the eddy-current instrument readings. The downward branch can be used to monitor the processes of crack formation and growth, the upward branch - to monitor the degree of cohesive spalling, while taking into account in the testing methodology an ambiguous character of the dependences of the eddy-current instrument readings on the number of loading cycles. © 2017 Author(s)

An educational software product work out as needed training resource to ensure the integration of the english language and study disciplines

Технология предполагает создание учебного продукта, который означает развитие и трансформацию профессионального образования, формирование нового образовательного поля по англоязычной траектории и распространение активных форм обучения, применение в обучении современных технологий и технических средств совершенствования образовательного процесса. Особое внимание должно быть уделено «отстающим» студентам и их специальной подготовке.Our educational software product focused strongly on education concerning some acknowledge the importance of language learning and acquiring professional and intercultural competences advancing at all grades of education, by encouraging quality linguistic and cultural preparation for mobility in both general professional and vocational education. A program particularly emphasizes on disadvantaged learners and their specific needs

The influence of a combined strain-heat treatment on the features of electromagnetic testing of fatigue degradation of quenched constructional steel

The possibilities of the magnetic and eddy-current methods for testing fatigue degradation during low-cycle loading of quenched steel 50 (0.51% C) that was subjected to a combined strain-heat treatment according to an optimal regime that included friction treatment with subsequent tempering at T = 350 C, were investigated. It is shown that for steel that was subjected to a combined nanostructuring treatment, the accumulation of a plastic strain under "hard" cyclic loading can be tested using the coercimetric method and values of the residual magnetic induction on the major and minor magnetic-hysteresis loops, values of the maximum and initial magnetic permeabilities, and readings of an eddy-current instrument at a low excitation frequency of the eddy-current transducer. The appearance of surface fatigue cracks can be tested via eddy-current measurements at high frequencies, when the contribution of the crack formation in the hardened layer to the eddy-current characteristics is considerable. © 2013 Pleiades Publishing, Ltd

Wear-resistant nickel-based laser clad coatings for high-temperature applications

The effect of high-temperature processing on laser clad Ni-based coatings is studied. Annealing at 1025°C forms thermally stable framework structures with large chromium carbides and borides. As a result, improved hardness and wear resistance of the coating are maintained when heated to 1000°C. Stabilizing annealing also increases the frictional thermal resistance of the NiCrBSi coating. Under high-speed (3.1– 9.3 m/s) sliding friction, when the surface layer temperature reaches about 500 –1000°С and higher, the wear resistance of the coating increases by 1.7 – 3.0 times. The proposed approach to the formation of heat-resistant coatings is promising, in particular, for a hot deformation tool and other components of metallurgical equipment operating under high thermal and mechanical loads. Such products include crystallizer walls of continuous casting machines. For the walls, the development of laser cladding technology for wear-resistant composite coatings on copper alloys is relevant as an alternative to thermal spraying. The cladding of composite NiBSi-WC coatings of 0.6 and 1.6 mm thickness on a Cu-Cr-Zr bronze substrate heated to 200 – 250°C with a diode laser is considered. The presence of boron causes the formation of the W(C, B) carboboride phase, whose hardness is higher than that of WC in the initial powder. Depending on the thickness of coatings and, accordingly, on the duration of heating and the subsequent cooling, the process of secondary carboborides precipitation from the solid solution can be suppressed (in the “thin” coating) or activated (in the “thick” coating). This leads to a higher wear resistance under friction sliding 1.6 mm thickness coating. © 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved.Institute of Education Sciences, IES: АААА-А18-118020790147-4Russian Science Foundation, RSF: 19-79-00031АААА-А18-118020190116-6The work was supported by the state orders of IMP UB RAS on the subjects “Laser” and “Structure” №АААА-А18-118020190116-6 and IES №АААА-А18-118020790147-4. The study of the evolution of the structure of NiCrBSi coatings during heating was carried out with financial support from the Russian Science Foundation, grant № 19-79-00031. The structural studies were done on the equipment installed at the Plastometriya Collective Use Center of IES UB RAS

The US Expert Community’s Role in the Formation of Nuclear Risk Reduction Policy During the Cold War

Рукопись поступила в редакцию: 30.03.2021. Принята к публикации: 23.07.2021.Received: 30.03.2021. Accepted: 23.07.2021.Данная работа посвящена изучению роли экспертного сооб- щества США в формировании политики снижения угрозы ядерной войны в период Холодной войны. Авторы рассматривают два способа взаимодей- ствия экспертов с властью: прямое (посредством участия экспертов в различ- ных профильных комитетах и комиссиях, подготовки аналитических отчетов) и через взаимодействие с гражданским обществом (публикация исследова- ний, формирование общественного мнения касательно ядерного оружия). Особое внимание уделяется роли советско-американского экспертного диа- лога в уменьшении угрозы ядерной войны. Авторы также рассматривают деятельность общественных организаций («Врачи мира за предотвращения ядерной войны», «Группа доверия», «Physicians for Social Responsibility»). В результате исследования авторы приходят к выводу, что американские экс- перты формировали дискуссию о необходимости предотвращения ядерной войны как среди правительственных структур, так и внутри гражданского общества, а также поддерживали диалог с советскими экспертами, что повли- яло на общее восприятие факторов, способных привести к началу ядерной войны (nuclear risks perception). Кроме того, эксперты выступали источни- ками новых идей, которые впоследствии были реализованы политическими деятелями на практике.This paper addresses the role of the US expert community in shaping the nuclear risk reduction policy during the Cold War. The authors examines two ways of interaction between experts and the authorities: direct (through the participation of experts in various specialized committees and commissions, preparing analytical reports, and so on) and through communication with the civil society (publication of studies, forming public opinion on nuclear weapons. The authors pay special attention to the role of the Soviet-American expert dialogue in reducing the nuclear risks. The authors also examines the activities of public organizations (International Physicians for the Prevention of Nuclear War, Physicians for Social Responsibility). As a result, the authors conclude that American experts shaped a discussion on the need to prevent nuclear war both within the government structures and civil society and maintained a dialogue with Soviet experts, which impacted nuclear risks perception. In addition, experts were sources of new ideas, which were subsequently put into practice by politicians

Изотопный состав зимних атмосферных осадков и снежного покрова в предгорьях Алтая

Over the past three decades, several general circulation models of the atmosphere and ocean (atmospheric and oceanic general circulation models  – GCMs) have been improved by modeling the hydrological cycle with the use of isotopologues (isotopes of water) HDO and H2 18O. Input parameters for the GCM models taking into account changes in the isotope composition of atmospheric precipitation were, above all, the results obtained by the network GNIP – Global Network of Isotopes in Precipitation. At different times, on the vast territory of Russia there were only about 40 simultaneously functioning stations where the sampling of atmospheric precipitation was performed. In this study we present the results of the isotope composition of samples taken on the foothills of the Altai during two winter seasons of 2014/15 and 2015/16. Values of the isotope composition of precipitation changed in a wide range and their maximum fluctuations were 25, 202 and 18‰ for δ18О, dexc and δD, respectively. The weighted-mean values of δ18О and δD of the precipitation analyzed for the above two seasons were close to each other (−21.1 and −158.1‰ for the first season and −21.1 and −161.9‰ for the second one), while dexc values differed significantly. The comparison of the results of isotope analysis of the snow cover integral samples with the corresponding in the time interval the weighted-mean values of precipitation showed high consistency. However, despite the similarity of values of δ18О and δD, calculated for precipitation and snow cover, and the results, interpolated in IsoMAP (from data of the GNIP stations for 1960–2010), the dexc values were close to mean annual values of IsoMAP for only the second winter season. According to the trajectory analysis (the HYSPLIT model), the revealed differences between both, the seasons, and the long-term average values of IsoMAP, were associated with a change of main regions where the air masses carrying precipitation were formed, namely, the North Atlantic (the winter season of 2014/15) and the inland areas with open ice-free water bodies (the season of 2015/16). Thus, with the correct interpretation of the results, the data on the snow cover isotope composition on the Altai foothills can be used as an alternative data sources instead of the GNIP data.Приводятся результаты изотопного анализа состава атмосферных осадков и снежного покрова предгорий Алтая. Показано, что средневзвешенные значения осадков двух зимних сезонов (2014/15 и 2015/16 гг.) для δ18О составили −21,1‰, а для δD −158,1 и −161,9‰ соответственно и хорошо согласуются с изотопным составом интегральных проб снежного покрова. Проявившиеся отличия в dexc, очевидно, связаны со сменой основных регионов формирования воздушных масс, приносящих атмосферные осадки: сменой открытых ото льда акваторий Северной Атлантики на внутриконтинентальные водоёмы. При корректной интерпретации результатов данные изотопного состава атмосферных осадков и снежного покрова в предгорьях Алтая могут быть использованы в ряде моделей МОЦ

FIRST REPORT ON TRUFFLE-INHABITING FUNGI AND METAGENOMIC COMMUNITIES OF TUBER AESTIVUM COLLECTED IN RUSSIA

Truffles are one of the least studied groups of fungi in terms of their biological and biotechnological aspects. This study aimed to isolate truffle-inhabiting fungi and assess the metagenomic communities of the most common Russian summer truffle, Tuber aestivum. This study is the first to characterize the biodiversity of prokaryotic and eukaryotic organisms living in the truffle T. aestivum using molecular analysis and sequencing. Plant pathogens involved in a symbiotic relationship with truffles were identified by sequencing the hypervariable fragments of the 16S rRNA and 18S rRNA genes. In addition, some strains of fungal symbionts and likely pathogens were isolated and recognized for the first time from the truffles. This study also compared and characterized the general diversity and distribution of microbial taxa of T. aestivum collected in Russia and Europe. The results revealed that the Russian and European truffle study materials demonstrated high similarity. In addition to the truffles, representatives of bacteria, fungi, and protists were found in the fruiting bodies. Many of these prokaryotic and eukaryotic species inhabiting truffles might influence them, help them form mycorrhizae with trees, and regulate biological processes. Thus, truffles are interesting and promising sources for modern biotechnological and agricultural studies