**Authors' contribution**

Vechorko V. I.-the idea of research. Writing sections "research Results", "discussion of results", "Conclusions". Doroshenko D. A.-description of research methods. Evsikov E. M.-a set of materials, statistical processing, design of the article text. Baykova O. A.-writing the section "Introduction", design of the article text. Teplova N.V. - writing the chapter "Discussion of results".
