Don State Technical University

This review focuses on the effect of metal-containing nanomaterials on tribological performance in oil lubrication. The basic data on nanolubricants based on nanoparticles of metals, metal oxides, metal sulfides, nanocomposities, and rare-earth compounds are generalized. The influence of nanoparticle size, morphology, surface functionalization, and concentration on friction and wear is analyzed. The lubrication mechanisms of nanolubricants are discussed. The problems and prospects for the development of metal-containing nanomaterials as lubricant additives are considered. The bibliography includes articles published during the last five years.

The rising medical costs associated with cancer have led to considerable financial hardship for patients and their families in the United States. Using data from the LIVESTRONG 2012 survey of 4,719 cancer survivors ages 18-64, we examined the proportions of survivors who reported going into debt or filing for bankruptcy as a result of cancer, as well as the amount of debt incurred. Approximately one-third of the survivors had gone into debt, and 3 percent had filed for bankruptcy. Of those who had gone into debt, 55 percent incurred obligations of $10,000 or more. Cancer survivors who were younger, had lower incomes, and had public health insurance were more likely to go into debt or file for bankruptcy, compared to those who were older, had higher incomes, and had private insurance, respectively. Future longitudinal population-based studies are needed to improve understanding of financial hardship among US working-age cancer survivors throughout the cancer care trajectory and, ultimately, to help stakeholders develop evidence-based interventions and policies to reduce the financial hardship of cancer.

In this investigation, it was shown that a probability of thermal runaway in commercial lithium-ion cells of the type 18650 grows with number increase of charge/discharge cycles and increase of cells state of charge (SOC). Notably, experiments in an accelerating rate calorimeter (ARC) showed that with the number growth of cells charge/discharge cycles, it is observed a considerable decline of an initiation temperature of exothermic reactions of thermal runaway and increase of released energy. Additional ARC-experiments with the following analysis of the gas released showed that in a course of cells cycling in anode graphite, hydrogen is accumulated. It was proven in experiments that a recombination of released-from-graphite-anode atomic hydrogen is exactly that powerful exothermic reaction, which increases the released energy in the beginning of the thermal runaway and decreases the temperature of its initiation. Thus, the reason for the initiation of thermal runaway in lithium-ion cells is a powerful exothermic reaction of recombination of atomic hydrogen accumulated in anode graphite in a during of cells cycling. The possible mechanism of initiation thermal runaway has been proposed corresponding to all the experimental results obtained.

Abstract Forty years ago, Garvie and his Australian co‐workers reported that the stress‐induced transformation of metastable tetragonal zirconia grains to the monoclinic symmetry could give rise to a powerful toughening mechanism. Their results even led them to consider zirconia systems as analogues of certain steels. This seminal paper generated extraordinary excitement in the ceramic community and it is still the subject of extensive research. Transformation toughening is widely used in zirconia materials and results in an increase in strength and toughness when compared to nontransformable ceramics, but the implementation into strong, tough, and sufficiently stable materials has not been fully reached. Zirconia ceramics generally fail at low strains with a much larger scatter in the strength values than metals and require statistical approaches to failure. Here we describe in detail the mechanical behavior laws of ceria‐doped zirconia composites exhibiting a high degree of stress‐induced transformation. They present, to some extent, mechanical behavior analogous to a metal, displaying, (a) significant amount of transformation‐induced plasticity without damage, (b) very high flaw tolerance and (c) almost no dispersion in strength data. They potentially open new application avenues in situations where the advantages of ceramics were dampened by their brittle failure behavior. In particular, the consequences of such behavior for dental implants and additive‐manufactured structures are highlighted.

This paper studied the gases release of a graphite//NMC111(LiNi1/3Mn1/3Co1/3O2) cell during cycle in the voltage ranges of 2.6-4.2V and 2.6-4.8V and the temperatures of at 25°C and 60°C. It was proved that the CO2, CO, and H2 gases are released as a result of electrolyte decomposition. And it shows that the CO and H2 gases evolution is a direct consequence of the electrochemical reaction of electrolyte decomposition, while the CO2 generation is a consequence of the additional chemical reaction of interaction between the O2 released from the cathode atomic lattice oxygen and CO released from the same place on the cathode (appearing because of the electrolyte decomposition). That is why at the same electrochemical reaction of electrolyte decomposition, the ratio CO2/CO varies in the wide range from 0.82 to 2.42 depending on cycling conditions (temperature and cutoff voltage). It was proved that a potential-independent H2 evolution is a consequence of its adsorption in pores of powdered graphite on anode. There was proposed the mechanism of the electrolyte decomposition and the gases evolution in lithium-ion cells at their cycling, which corresponds quantitatively to all obtained experimental results.

The breaking of the vertical symmetry in Janus monochalcogenides gave rise to many properties that were not present in the original monochalcogenide monolayers. However, recent papers have often focused only on Janus monochalcogenides containing S, Se, and Te elements despite that O is also one of the group VI chalcogen elements. In this paper, we systematically investigate the electronic, transport, optical, and thermoelectric properties of Janus monolayers ${\mathrm{In}}_{2}X\mathrm{O}$ ($X=\mathrm{S},\mathrm{Se},\mathrm{Te}$) using first-principles calculations. Based on phonon spectrum analysis and ab initio molecular dynamics simulations at room temperature, ${\mathrm{In}}_{2}X\mathrm{O}$ monolayers were reported to be stable. Our calculations reveal that, while ${\mathrm{In}}_{2}\mathrm{SO}$ is an indirect semiconductor, ${\mathrm{In}}_{2}\mathrm{SeO}$ exhibits a direct semiconducting characteristic, and biaxial strain can lead to the semiconductor-metal phase transition in ${\mathrm{In}}_{2}\mathrm{SeO}$. Monolayer ${\mathrm{In}}_{2}\mathrm{TeO}$ is metal at equilibrium, and its metallic characteristics are prevented under biaxial strains. Calculations for transport properties show that the carrier mobilities of ${\mathrm{In}}_{2}\mathrm{SO}$ and ${\mathrm{In}}_{2}\mathrm{SeO}$ monolayers are highly anisotropic, and electron mobility of ${\mathrm{In}}_{2}\mathrm{SO}$ exceeds $3\ifmmode\times\else\texttimes\fi{}{10}^{3}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}/\mathrm{Vs}$. In this paper, the optical and thermoelectric properties of ${\mathrm{In}}_{2}\mathrm{SO}$ and ${\mathrm{In}}_{2}\mathrm{SeO}$ monolayers are also investigated and discussed in detail. Finally, the electronic properties of all four possible stacking configurations of the Janus bilayers are briefly calculated. Our findings not only contribute to a more general view of the physical properties of the Janus group III monochalcogenides but also recommend them as potential nanomaterials for applications in optoelectronic and thermal devices.

Purpose The purpose of this paper is to determine the priorities of formation of competencies during training of digital personnel for industry 4.0. Design/methodology/approach The author performs two experiments for determining the scenario according to which industry 4.0 develops and will develop: the first experiment is aimed at determining the influence of the number of robots at unemployment level in 2019 and 2022 with the help of regression and correlation analysis (regression curves are built). The second experiment is connected to evaluation of the ratio of the number of robots to the number of population in 2019 and 2022. The research objects are countries with the highest number of robots in the world – i.e. with the highest level of development of industry 4.0; the information and empirical basis is materials of the International Federation of Robotics and the International Monetary Fund for 2019 and their forecasts for 2022. Findings The results of the performed experiments showed that in 2019 and 2022 the level of robotization of socio-economic systems of the countries of the world will be very low, and robotization will not cause growth of unemployment. Based on this, it is concluded that industry 4.0 will be developing according to the scenario of moderate automatization and robotization with preservation of domination of human labor in most business processes and spheres of economy. Communications with people will constitute the basis of the activities of digital personnel, and social competencies (with obvious significance of technical competencies) will be of top priority for them. Originality/value It is substantiated that technical competencies, with their large importance, will move to the background, while the key task will be society’s adaptation to the new technological mode and making social competencies the highest priority. The social and technical competencies of digital personnel in view of the performed tasks for industry 4.0 are determined.

Ammonium is a water pollutant that harms the environment, particularly fisheries. Rice straw is also an economic waste of rice, with millions of tons produced per year around the world. In this paper, physical and chemical procedures for the modification of rice straw were studied. The kinetic and isothermal adsorption trends were investigated, including the ammonium removal efficiency, the contact time of the adsorbent, the amount of adsorbent, and the initial concentration of NH 4 + . The effect of temperature and pH on the adsorption process was discussed. The removal efficiency of NH 4 + recorded 43, 53.7, and 69.5%, with maximum adsorption values of 2.9, 3.5, and 4.5 mg/g at temperatures of 25 ± 5, 35 ± 5, and 45 ± 5°C, respectively, at pH 7.5. The biochar obtained from rice follows the pseudo-second-order equation for ammonium adsorption kinetics (R 2 = 0.98). The adsorption isotherm follows Freundlich’s model (R 2 = 0.99) and Langmuir’s model (R 2 = 0.98).

The modern paradigm assumes that interspecies communication of microorganisms occurs through precise regulatory mechanisms. In particular, antagonism between bacteria or bacteria and fungi can be achieved by direct destruction of the targeted cells through the regulated production of antimicrobial metabolites or by controlling their adaptive mechanisms, such as the formation of biofilms. The quorum-quenching phenomenon provides such a countermeasure strategy. This review discusses quorum-sensing suppression by Gram-positive microorganisms, the underlying mechanisms of this process, and its molecular intermediates. The main focus will be on Gram-positive bacteria that have practical applications, such as starter cultures for food fermentation, probiotics, and other microorganisms of biotechnological importance. The possible evolutionary role of quorum-quenching mechanisms during the development of interspecies interactions of bacteria is also considered. In addition, the review provides possible practical applications for these mechanisms, such as the control of pathogens, improving the efficiency of probiotics, and plant protection.

Our world is now facing a multitude of novel infectious diseases. Bacterial infections are treated with antibiotics, albeit with increasing difficulty as many of the more common causes of infection have now developed broad spectrum antimicrobial resistance. However, there is now an even greater challenge from both old and new viruses capable of causing respiratory, enteric, and urogenital infections. Reports of viruses resistant to frontline therapeutic drugs are steadily increasing and there is an urgent need to develop novel antiviral agents. Although this all makes sense, it seems rather strange that little attention has been given to the antiviral capabilities of probiotics. Over the years, beneficial strains of lactic acid bacteria (LAB) have been successfully used to treat gastrointestinal, oral, and vaginal infections, and some can also affect a reduction in serum cholesterol levels. Some probiotics prevent gastrointestinal dysbiosis and, by doing so, reduce the risk of developing secondary infections. Other probiotics exhibit anti-tumor and immunomodulating properties, and in some studies, antiviral activities have been reported for probiotic bacteria and/or their metabolites. Unfortunately, the mechanistic basis of the observed beneficial effects of probiotics in countering viral infections is sometimes unclear. Interestingly, in COVID-19 patients, a clear decrease has been observed in cell numbers of Lactobacillus and Bifidobacterium spp., both of which are common sources of intestinal probiotics. The present review, specifically motivated by the need to implement effective new counters to SARS-CoV-2, focusses attention on viruses capable of co-infecting humans and other animals and specifically explores the potential of probiotic bacteria and their metabolites to intervene with the process of virus infection. The goal is to help to provide an informed background for the planning of future probiotic-based antiviral research.

We theoretically study the magneto-optical transport properties of monolayer molybdenum disulfide (${\mathrm{MoS}}_{2}$) on polar substrates in the presence of a perpendicular magnetic field. The magneto-optical absorption coefficient (MOAC) is investigated as a function of the incident photon energy when carriers are scattered by three different types of phonons: the intrinsic ${\mathrm{MoS}}_{2}$ acoustic, optical phonons, and the surface optical (SO) phonons induced by polar substrates. Among the substrates considered, the largest magnitude of MOAC and full-width at half maximum (FWHM) are observed for a ${\mathrm{SiO}}_{2}$ substrate over the entire temperature and magnetic field range considered due to its strongest electron-SO phonon scattering, while an h-BN substrate displays the lowest one. The piezoelectric (PE) coupling to the transverse (TA) phonon is shown to dominate the MOAC and FWHM due to intrinsic acoustic phonon scattering. Meanwhile, these properties for intrinsic optical phonons are dominated by zero-order deformation potential (DP) couplings and the Fr\"ohlich interaction. The dependence of the MOAC and FWHM on temperature, magnetic field, and the effective ${\mathrm{MoS}}_{2}$-substrate distance is also examined. The present results for monolayer ${\mathrm{MoS}}_{2}$ are compared with those in conventional two-dimensional systems as well as in graphene. Our results show that SO phonons play a crucial role at high temperature depending on the substrates and have a non-negligible effect on the magneto-optical transport properties of monolayer ${\mathrm{MoS}}_{2}$, which could be further experimentally and theoretically investigated in the future.

This chapter will discuss monopsony and its problems in the labor market: does the monopsony of employees and working conditions have a negative impact; why are trade unions created and how do they affect this situation?

Purpose The purpose of this paper is to study the limitations, opportunities and conditions for the development of e-learning in the inclusive education system in the universities. Design/methodology/approach The paper reviews the literature dedicated to e-learning, its application and adaptation in higher inclusive education. Systemic and social approaches were applied to the perception of higher inclusive education for the purposes of this study. The principles of evolutionary economics and institutional theory were used for determining the possibility of using e-learning in higher inclusive education. The findings are confirmed by an empirical study of the integration of e-learning into the higher inclusive education system by the example of Russia. Findings It has been shown that the development of e-learning in the national higher education system and its perception by the higher inclusive education system depends on the level of development of social and information interrelation in the society. In addition, e-learning can only be used in higher inclusive education when it is interrelated with traditional learning. The efficiency of e-learning in higher inclusive education depends on the systemic institutional environment which was formed both at the level of the state and at the level of a particular university. In this case, the institutional environment should be focused not only on the development of e-learning and inclusive education, but also on their collaboration. Practical implications The results of the study, which identified special aspects, opportunities and limitations of e-learning in higher inclusive education, can be applied to improve its effectiveness both at the level of individual universities and at the level of formation of national strategies for the development of higher education. Originality/value Given the growing relevance of higher inclusive education in the contemporary world and the limited number of studies of adaptation and the use of e-learning in it, the results obtained can contribute to the implementation of strategic planning of this direction at the national and local levels.

Currently, one of the topical areas of application of machine learning methods in the construction industry is the prediction of the mechanical properties of various building materials. In the future, algorithms with elements of artificial intelligence form the basis of systems for predicting the operational properties of products, structures, buildings and facilities, depending on the characteristics of the initial components and process parameters. Concrete production can be improved using artificial intelligence methods, in particular, the development, training and application of special algorithms to determine the characteristics of the resulting concrete. The aim of the study was to develop and compare three machine learning algorithms based on CatBoost gradient boosting, k-nearest neighbors and support vector regression to predict the compressive strength of concrete using our accumulated empirical database, and ultimately to improve the production processes in construction industry. It has been established that artificial intelligence methods can be applied to determine the compressive strength of self-compacting concrete. Of the three machine learning algorithms, the smallest errors and the highest coefficient of determination were observed in the KNN algorithm: MAE was 1.97; MSE, 6.85; RMSE, 2.62; MAPE, 6.15; and the coefficient of determination R2, 0.99. The developed models showed an average absolute percentage error in the range 6.15−7.89% and can be successfully implemented in the production process and quality control of building materials, since they do not require serious computing resources.

This review's objective was to critically revisit various research approaches for studies on the application of beneficial organisms and bacteriocins as effective biopreservatives in the food industry. There are a substantial number of research papers reporting newly isolated bacterial strains from fermented food products and their application as potential probiotics, including partial characterization of bacteriocins produced by these microorganisms. Most of these studies follow scientific community-accepted standard procedures and propose various applications of the studied strains and bacteriocins as potential biopreservatives for the food industry. A few investigations go somewhat further, performing model studies, exploring the application of expressed bacteriocins in a designed food product, or trying to evaluate the effectiveness of the studied potential probiotics and bacteriocins against foodborne pathogens. Some authors propose applications of bacteriocin producers as starter cultures and are exploring in situ bacteriocin production to aid in the effective control of foodborne pathogens. However, few studies have evaluated the possible adverse effects of bacteriocins, such as toxicity. This comes from well-documented reports on bacteriocins being mostly non-immunogenic and having low cytotoxicity because most of these proteinaceous molecules are small peptides. However, some studies have reported on bacteriocins with noticeable cytotoxicity, which may become even more pronounced in genetically engineered or modified bacteriocins. Moreover, their cytotoxicity can be very specific and is dependent on the concentration of the bacteriocin and the nature of the targeted cell. This will be discussed in detail in the present review.

The stability of RNA is a critical factor in determining its functionality and degradation in the cell. In recent years, it has been shown that the stability of RNA depends on a complex interaction of external and internal factors. External conditions, such as temperature fluctuations, the level of acidity of the environment, the presence of various substances and ions, as well as the effects of oxidative stress, can change the structure of RNA and affect its stability. Internal factors, including the specific structural features of RNA and its interactions with protein molecules, also have a significant impact on the regulation of the stability of these molecules. In this article, we review the main factors influencing RNA stability, since understanding the factors influencing this extremely complex process is important not only for understanding the regulation of expression at the RNA level but also for developing new methods for isolating and stabilizing RNA in preparation for creating biobanks of genetic material. We reviewed a modern solution to this problem and formulated basic recommendations for RNA storage aimed at minimizing degradation and damage to the molecule.

emissions into the atmosphere, do not pollute the environment, and reduce energy costs and the cost of production processes. These technologies include the production of geopolymer concretes. The purpose of the study was a detailed in-depth analytical review of studies of the processes of structure formation and properties of geopolymer concretes in retrospect and the current state of the issue. Geopolymer concrete is a suitable, environmentally friendly and sustainable alternative to concrete based on ordinary Portland cement (OPC) with higher strength and deformation properties due to its more stable and denser aluminosilicate spatial microstructure. The properties and durability of geopolymer concretes depend on the composition of the mixture and the proportions of its components. A review of the mechanisms of structure formation, the main directions for the selection of compositions and processes of polymerization of geopolymer concretes has been made. The technologies of combined selection of the composition of geopolymer concrete, production of nanomodified geopolymer concrete, 3D printing of building structures from geopolymer concrete, and monitoring the state of structures using self-sensitive geopolymer concrete are considered. Geopolymer concrete with the optimal ratio of activator and binder has the best properties. Geopolymer concretes with partial replacement of OPC with aluminosilicate binder have a denser and more compact microstructure due to the formation of a large amount of calcium silicate hydrate, which provides improved strength, durability, less shrinkage, porosity and water absorption. An assessment of the potential reduction in greenhouse gas emissions from the production of geopolymer concrete compared to the production of OPC has been made. The potential of using geopolymer concretes in construction practice is assessed in detail.

The fundamental motivation of this research is to investigate the effect of flexoelectricity on a piezoelectric nanobeam for the first time involving internal viscoelasticity. To date, the effect of flexoelectricity on the mechanical behavior of nanobeams has been investigated extensively under various physical and environmental conditions. However, this effect as an internal property of materials has not been studied when the nanobeams include an internal damping feature. To this end, a closed-circuit condition is considered taking converse piezo–flexoelectric behavior. The kinematic displacement of the classical beam using Lagrangian strains, also applying Hamilton’s principle, creates the needed frequency equation. The natural frequencies are measured in nanoscale by the available nonlocal strain gradient elasticity model. The linear Kelvin–Voigt viscoelastic model here defines the inner viscoelastic coupling. An analytical solution technique determines the values of the numerical frequencies. The best findings show that the viscoelastic coupling can directly affect the flexoelectricity property of the material.

Bulk poly-supercrystalline ceramic-organic nanocomposites were produced and characterized with a nanoindentation-based study. These nanocomposites were processed using two different routines, to compare their properties with and without crosslinking the organic ligands interfacing the ceramic nanoparticles. Together with the expected material strengthening induced by crosslinking, a distinct response emerges when using Berkovich and cube-corner indenters. The supercrystalline materials are prone to compaction, cracking and chipping phenomena that become more severe when a sharper tip is employed, implying that a Berkovich indenter is more suitable for the evaluation of elastic modulus and hardness. The cube-corner tip, on the other hand, is employed for the investigation of fracture toughness, comparing two methods and multiple models available from the literature. The fracture toughness outcomes suggest that cracks evolve with a quarter-penny shaped profile at the indent’s corners, and that extrinsic toughening mechanisms, such as plastic-like deformation and crack deflection, play a significant role.

The performance of waste marble powder as a partial replacement for cement is examined with the aim to achieve more sustainable concrete. Pursuant to this goal, a total of 15 specimens were manufactured and then tested to examine the bending behavior. The effects of longitudinal reinforcement ratio and waste marble powder ratio were selected as variables. The experimental results showed that different proportions of tension reinforcement and waste marble powder had different crack and bending impacts on reinforced concrete beams. As the waste marble powder amount in the concrete mixture is increased from 0% to 40%, it was detected that the crack type changes from a shear crack from to a flexural crack as the amount of waste marble powder increases in the mixing ratio. The experimental findings revealed that the waste marble powder can be successfully used as 10% of the partial replacement of cement. Increasing the waste marble powder ratio by more than 10% can significantly decrease the capacity of the beams, especially when longitudinal reinforcement ratio is high. The influence of waste marble as partial replacement on the capacity decreases as the longitudinal reinforcement ratio decreases. Therefore, 10%–20% marble waste can be utilized as a replacement for cement when the longitudinal reinforcement ratio is close to the balanced ratio and more than 20% waste marble ratio should be avoided for any cases.