O. N. Bodin1, O. E. Bezborodova2, V.M. Zhigachev3, K.D. Mishina4, D.V. Martynov5, A.A. Trofimov6

1, 3, 5 Penza State Technological University (Penza, Russia)
2, 4, 6 Penza State University (Penza, Russia)
bodin_o@inbox.ru