The coronavirus disease outbreak in 2019 (COVID-19) has now achieved the level of a global pandemic and affected more than 100 million people on all five continents and caused over 2 million deaths. Russia is, needless to say, among the countries affected by SARS-CoV-2, and its health authorities have mobilized significant efforts and resources to fight the disease. The paper presents the result of a functional analysis of 155 patients in the Moscow Region who were examined at the Central Clinical Hospital of the Russian Academy of Sciences during the first wave of the pandemic (FebruaryJuly, 2020). The inclusion criteria were a positive PCR test and typical, computed tomographic findings of viral pneumonia in the form of ground-glass opacities. A clinical correlation analysis was performed in four groups of patients: (1) those who were not on mechanical ventilation, (2) those who were on mechanical ventilation, and (3) those who subsequently recovered or (4) died. The correlation analysis also considered confounding comorbidities (diabetes, metabolic syndrome, hypertension, etc.). The immunological status of the patients was examined (levels of immunoglobulins of the M, A, G classes and their subclasses, as well as the total immunoglobulin level) using an original SARS-CoV-2 antibody ELISA kit. The ELISA kit was developed using linear S-protein RBD-SD1 and NTD fragments, as well as the N-protein, as antigens. These antigens were produced in the prokaryotic E. coli system. Recombinant RBD produced in the eukaryotic CHO system (RBD CHO) was used as an antigen representing conformational RBD epitopes. The immunoglobulin A level was found to be the earliest serological criterion for the development of a SARS-CoV-2 infection and it yielded the best sensitivity and diagnostic significance of ELISA compared to that of class M immunoglobulin. We demonstrated that the seroconversion rate of early N-protein-specific IgM and IgA antibodies is comparable to that of antibodies specific to RBD conformational epitopes. At the same time, seroconversion of SARS-CoV-2 N-protein-specific class G immunoglobulins was significantly faster compared to that of other specific antibodies. Our findings suggest that the strong immunogenicity of the RBD fragment is for the most part associated with its conformational epitopes, while the linear RBD and NTD epitopes have the least immunogenicity. An analysis of the occurrence rate of SARS-CoV-2-specific immunoglobulins of different classes revealed that RBD- and N-specific antibodies should be evaluated in parallel to improve the sensitivity of ELISA. An analysis of the immunoglobulin subclass distribution in sera of seropositive patients revealed uniform induction of N-protein-specific IgG subclasses G1G4 and IgA subclasses A1A2 in groups of patients with varying severity of COVID-19. In the case of the S-protein, G1, G3, and A1 were the main subclasses of antibodies involved in the immune response.

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The article presents an approach to assessing the fracture toughness of structural alloys based on thermally activated crack growth and recording acoustic emission signals. The kinetic and structural features of the stable growth of the initiated crack are estimated using a multilevel acoustic emission model based on the time dependence of the logarithm of the cumulative acoustic emission count. The article provides an evaluation of the stable kinetic constants included in the equation of the thermal fluctuation steps of a crack according to literature sources and using the acoustic emission method. It is shown that parameters such as activation energy, activation area before the crack tip, and the rate of non-activation crack growth are stable and show a satisfactory correspondence between the reference literature and real experiments. The approach does not require a set of laboratory experiments to determine the empirical constants of traditional crack growth rate equations, and it also differs in that it takes into account the unique features of the destruction of a particular specimen or technological equipment and allows for a non-destructive assessment of fracture toughness. The values obtained are conservative. The concentration criterion of destruction requires further investigation.

Background: According to experimental studies, mesh implants may reduce in size up to 50.8% during their integration into soft tissues. This results in impaired mobility of the anterior abdominal wall and hernia recurrences, as well as affects patients' quality of life. Due to unsatisfactory radiographic contrast of polymeric mesh implants, changes in their size can be rarely confirmed using imaging methods. Medical devices made of metal alloys have the best radiographic contrast. Objective: The purpose of this study was to evaluate the radiographic contrast of mesh implants made of titanium filaments and to determine the sizes and locations of the implants after the anterior abdominal wall hernia repair. Materials & Methods: The study included 40 patients with inguinal, umbilical, and postoperative ventral hernias. Surgical hernia repair was performed using a mash implant made of titanium filaments, "titanium silk". Multislice spiral computed tomography (MSCT) was performed on Days 3 and 90 after surgery, followed by an assessment of the size and location of the mesh implant.Results: 90 days after the anterior abdominal wall hernia repair, the locations of the titanium silk mesh implants in the tissues corresponded to their intraoperative setting. There were no statistically significant changes in the sizes of mesh implants on Day 90, compared with Day 3. Conclusion:The titanium silk mesh implants have satisfactory radiographic contrast, which allows imaging of their location and size in the tissues using MSCT and comprehensive evaluation of hernia repair outcomes using instrumental methods of examination. K E Y W O R D S3D reconstruction, multislice spiral computed tomography, polymeric mesh implants, radiographic contrast, soft tissues, titanium mesh