Effect of thermal annealing and deposition conditions on the structure and mechanical properties of a mulitlayer nitride coating based on Ta

An analysis of the structure and mechanical properties of multilayer nitride coatings based on Ta depending on the deposition conditions and thermal vacuum-free annealing was conducted. Ta/TaN is a multylayer structure with alternate deposition of a polycrystalline layer of Ta of high ductility and a layer of TaN of high strength. TaN is a coating deposited by magnetron sputtering with the ratio N2/Ar = 0.4, exhibiting a high degree of crystallinity that leads to a high adhesive strength and hardness of Ta/TaN multilayer coatings. For nitride coatings based on refractory elements of the V–VI period, the general patterns consisting in the formation of the NaCl structure, and the predominant orientation of the planes (111) were identified. The application of heat treatment decreases the microhardness of the Ta/TaN multilayer coatings from 2600 to 1200 kgf/mm2, and leads to deterioration of the adhesive strength between the layers. In the process of mechanical testing, the tribological coefficient for the considered protective coatings was 0.1–0.25, the volume of surface wear was 14.3 mm

Effect of thermal annealing and deposition conditions on the structure and mechanical properties of a mulitlayer nitride coating based on Ta

An analysis of the structure and mechanical properties of multilayer nitride coatings based on Ta depending on the deposition conditions and thermal vacuum-free annealing was conducted. Ta/TaN is a multylayer structure with alternate deposition of a polycrystalline layer of Ta of high ductility and a layer of TaN of high strength. TaN is a coating deposited by magnetron sputtering with the ratio N2/Ar = 0.4, exhibiting a high degree of crystallinity that leads to a high adhesive strength and hardness of Ta/TaN multilayer coatings. For nitride coatings based on refractory elements of the V–VI period, the general patterns consisting in the formation of the NaCl structure, and the predominant orientation of the planes (111) were identified. The application of heat treatment decreases the microhardness of the Ta/TaN multilayer coatings from 2600 to 1200 kgf/mm2, and leads to deterioration of the adhesive strength between the layers. In the process of mechanical testing, the tribological coefficient for the considered protective coatings was 0.1–0.25, the volume of surface wear was 14.3 mm

Possible Metal/Insulator Transition at B=0 in Two Dimensions

We have studied the zero magnetic field resistivity of unique high- mobility two-dimensional electron system in silicon. At very low electron density (but higher than some sample-dependent critical value, $n_{cr}\sim 10^{11}$ cm$^{-2}$), CONVENTIONAL WEAK LOCALIZATION IS OVERPOWERED BY A SHARP DROP OF RESISTIVITY BY AN ORDER OF MAGNITUDE with decreasing temperature below 1--2 K. No further evidence for electron localization is seen down to at least 20 mK. For $n_s<N_{cr}$, the sample is insulating. The resistivity is empirically found to SCALE WITH TEMPERATURE BOTH BELOW AND ABOVE $n_{cr}$ WITH A SINGLE PARAMETER which approaches zero at $n_s=n_{cr}$ suggesting a metal/ insulator phase transition.Comment: 10 pages; REVTeX v3.0; 3 POSTSCRIPT figures available upon request; to be published in PRB, Rapid Commu

Relationships between the allozyme and phenotypic diversities of Picea ajanensis populations

The structures of Picea ajanensis populations were compared based on allozyme analysis of vegetative buds and morphometric analysis of generative organs. Six cenopopulations of P. ajanensis were investigated in areas with various levels of volcanic impact in the Kamchatka Peninsula. The genetic structures of spruce populations and phenotypes were determined by analysis of ten enzyme systems (PGM, GOT, HK, LAP, MDH, SKDH, IDH, GDH, PGI and SOD). Phenotypic variability of spruce populations was estimated based on the composition of morphotypes that were identified by using geometric morphometrics of cone-scale shapes. Pairwise comparison of samples of cones from 170 trees from six populations revealed 12 morphotypes differing in the shape of cone scales. Comparative assessment of variability and similarity of populations was carried out based on the frequency of occurrence of phenotypes and frequency of alleles of polymorphic loci. Correlations of the genetic and phenotypic distance matrices between different phenotypes were revealed. This observation was consistent with the genetic determination of the shape of cone scales in spruce. Genetic differences between the morphotypes with regard to nine polymorphic loci (Got-2, Skdh-1, Idh-2, Pgm-2, Mdh-1, Mdh-3, Pgm- 1, Pgi-2, and Hk) were not significant. Statistically significant differences between the morphotypes were revealed for two loci: Pgm-2 and Mdh-1. Differences in the genetic diversity of spruce populations generally corresponded to differences in their phenotypic diversity. The high levels of genetic and phenotypic diversity characterized a stable population structure of spruce in the area of weak volcanic influence. Changes in the genetic structure and low levels of the phenotypic diversity of spruce were observed under catastrophic volcanic impact

Level and correlations of soluble suppression of tumorigenicity 2 protein in heart failure and its relationship with clinical and paraclinical characteristics of patients

Aim. To establish the correlations of the soluble suppression of tumorigenicity 2 protein (sST2) and N-terminal pro-brain natriuretic peptide (NT-proBNP) with some clinical and paraclinical characteristics of patients with heart failure (HF).Material and methods. The study included 130 patients with HF (men — 54, women — 76, mean age, 64,3±8,3 years) from the regional registry of HF patients in the Voronezh Oblast. All patients underwent echocardiography and general clinical investigations. In addition, the serum levels of sST2 and NT-proBNP were determined and their correlations with other parameters were studied.Results. The blood level of sST2 in HF patients was 339,8 [266;405] pg/ml. In the study sample of patients with HF, sST2 levels correlated with right atrial (r=0,49) and right ventricular (r=0,32) sizes, left ventricular end-diastolic dimension (r=0,34) and volume (r=0,33), left ventricular early diastolic filling rate (r=-0,35), blood calcium level (r=-0,55) and functional class of exertional angina (r=-0,37).Conclusion. The data obtained may indicate a pathogenetic relationship between sST2 and systolic and diastolic dysfunction of the left ventricle and right heart

Biomarkers ST2 and interleukin 33 for assessing the severity of cardiac inflammation and fibrosis in patients with chronic heart failure

Chronic heart failure (CHF) is a pathology that affects more than 37 million people worldwide. Despite the introduction of new drugs into practice, that have proven their effectiveness in the treatment of patients with CHF, the life expectancy of these patients is growing at a slow pace. At the same time, the insufficient effect of neurohormonal blockers for the treatment of patients with CHF with preserved ejection fraction (CHFpEF), which prevails in the general structure of CHF, indicates a significant role of unidentified pathological processes in the development of this form of the disease. In recent years, the role of cardiac fibrosis has been actively studied within the framework of the investigation of the pathogenesis of CHFpEF, the probable biomarkers of which are interleukin (IL) 33 and suppression of tumorigenicity 2 (ST2). This literature review examines the influence of the IL-33/ ST2 interaction as a biomarker of cardiac fibrosis on the course of CHF and the possibilities of its practical application

Bilirubin and cardiovascular risk

This literature review demonstrates the results of experimental and clinical studies, as well as data from meta-analyzes on the effect of bilirubin levels on cardiovascular system. Recent studies provided a new look at the role of bilirubin in cardiovascular disease. Modern concepts consider bilirubin as a powerful endogenous antioxidant with anti-inflammatory effects, capable of influencing the course of atherosclerotic cardiovascular diseases and reducing ischemic damage. The change in bilirubin levels affects the coronary blood flow, the development of collateral circulation and the morphology of coronary plaques. A low bilirubin level is associated with an increase in left ventricular mass and a decrease in its contractility, which, in turn, leads to heart failure and increases the risk of rehospitalizations. Taking into account the above effects of bilirubin, there was interest in assessing the effect of its blood level on the risk of atherosclerotic cardiovascular diseases. Recent studies have attempted to create risk stratification models for adverse cardiovascular events based on bilirubin levels

Acute Coronary Syndrome during the Pandemic New Coronavirus Infection

The experience of managing patients with COVID-19 around the world has shown that, although  respiratory symptoms predominate  during the manifestation of infection, then many patients can develop serious damage  to the cardiovascular system. However, coronary artery disease (CHD) remains the leading cause of death worldwide. The purpose of the review is to clarify the possible pathogenetic links between COVID-19 and acute coronary syndrome (ACS), taking into account which will help to optimize the management of patients with comorbid  pathology. Among the body's responses to SARS-CoV-2 infection, which increase the likelihood of developing  ACS,  the role of systemic inflammation, the quintessence  of which is a "cytokine storm" that can destabilize  an atherosclerotic  plaque is discussed.  Coagulopathy, typical for patients with Covid-19, is based on immunothrombosis, caused by a complex  interaction between neutrophilic  extracellular  traps and von Willebrandt  factor in conditions  of systemic inflammation. The implementation  of a modern strategy  for managing patients with ACS,  focused on the priority of percutaneous interventions (PCI), during  a pandemic is experiencing great  difficulties  due to the formation  of time delays  before  the start of invasive  procedures  due to the epidemiological situation. Despite this, the current European,  American and Russian recommendations for the management of infected patients with ACS confirm the inviolability of the position of PCI as the first choice for treating patients with ACS and the undesirability  of replacing  invasive treatment with thrombolysis

Two interacting quasiparticles above the Fermi sea

We study numerically the interaction and disorder effects for two quasiparticles in two and three dimensions. The dependence of the interaction-induced Breit-Wigner width on the excitation energy above the Fermi level, the disorder strength and the system size is determined. A regime is found where the width is practically independent of the excitation energy. The results allow to estimate the two quasiparticle mobility edge.Comment: revtex, 4 pages, 4 figure

Quasiparticles of strongly correlated Fermi liquids at high temperatures and in high magnetic fields

Strongly correlated Fermi systems are among the most intriguing, best experimentally studied and fundamental systems in physics. There is, however, lack of theoretical understanding in this field of physics. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature. It turns out that the hidden fundamental law is well forgotten old one directly related to the Landau---Migdal quasiparticles, while the basic properties and the scaling behavior of the strongly correlated systems can be described within the framework of the fermion condensation quantum phase transition (FCQPT). The phase transition comprises the extended quasiparticle paradigm that allows us to explain the non-Fermi liquid (NFL) behavior observed in these systems. In contrast to the Landau paradigm stating that the quasiparticle effective mass is a constant, the effective mass of new quasiparticles strongly depends on temperature, magnetic field, pressure, and other parameters. Our observations are in good agreement with experimental facts and show that FCQPT is responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.Comment: 17 pages, 17 figures. Dedicated to 100th anniversary of A.B.Migdal birthda