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Superconducting materials with high current carrying capacity operating in magnetic fields up to 18 T at 4.2 K are required for promising applications in magnetic systems of high-energy physics devices, NMR-spectroscopes and others. The paper presents the study results of the Nb3Sn strands manufactured by the bronze route differed in the filament composition. The filaments were made from the alloys Nb-3.5 wt. %Ta and Nb-7.0wt.%Ta and the matrix was produced from the Cu-15.5wt.%Sn-0.25wt.%Ti alloy. To form the superconducting Nb3Sn phase a series of reaction heat treatments of conductor samples were carried out by two-stage regimes with the temperature of the second stage varying from 650 to 720 °C. The microstructure of the Nb3Sn layer was studied by scanning electron microscopy and their electro-physical characteristics were also measured. It was shown that after reaction at 575 °C, 100 h + 650 °C, 200 h samples with different Ta content had almost the same current -carrying capacity in the field range 12-18 T at 4.2 K. The critical temperature of superconductors decreased from 17.5 to 16.5 K with an increase of the second stage of reaction temperature from 650 to 720 °C.

Modernity raises the most important questions for researchers: what will happen to patients who have undergone COVID-19? What complications threaten them? What happens to the immune system after this disease? To what extent do the changes caused by the virus disrupt the formation of protective immunity in the future? The study found a causal relationship between SARS-CoV-2 infection, immune dysfunction, and the manifestation of chronic inflammatory diseases. Proven multitarget action of the new drug Mercurid, aimed at modulating the activity of several critical target proteins, such as CD3, CD4, CD8, CD25, CD38, CD54, CD95. On the one hand, this has reduced the severity of postpartum complications, and on the other - to increase the ability of the immune system to eliminate the virus from the body. The therapeutic efficacy of Mercurid was 75.1%. The second research finding is that patients with a history of chronic inflammatory disease with a history of SARS-CoV-2 are more likely to develop impaired specific protective antibodies. This conclusion follows from the pathologically low level of CD4, CD8, CD25 and overexpression of CD38, ICAM-1, CD95, which indicates apoptosis of immune cells, lymphopenia and the formation of the phenotype of depleted T cells with activation of inhibitory receptor expression. Thus, for this cohort of patients, vaccination may be ineffective due to the presence of a compromised immune system. Accordingly, corrective multi-target immunotherapy targeting multiple target proteins critical to the development of long-term effective post-viral immunity to SARS-CoV-2 is an extremely important therapeutic task. Immunoprophylaxis can be performed both before and after vaccination, in order to achieve the maximum protective effect against the vaccine.