A.D. Usanov - Ph. D. (Phys.-Math.), Associate Professor, Faculty of Nano- and Biomedical Technologies, Saratov State University named after N.G. Chernyshevsky. E-mail: aka_norton@mail.ru A.P. Rytik - Ph. D. (Phys.-Math.), Associate Professor, Faculty of Nano- and Biomedical Technologies, Saratov State University named after N.G. Chernyshevsky. E-mail: ra4csz@yandex.ru A.V. Bondarenko - Student, Faculty of Nano- and Biomedical Technologies, Saratov State University named after N.G. Chernyshevsky. E-mail: neznakomka317@yandex.ru N.S. Ilukhina - Student, Faculty of Nano- and Biomedical Technologies, Saratov State University named after N.G. Chernyshevsky. E-mail: Nabiy0621@gmail.com