1. Division of Physicochemical Research, Faculty of Natural Sciences and Technology, Opole University, ul. kard. B. Kominka 6, 45-032 Opole, Poland, phone +48 77 401 60 42, fax +48 77 401 60 51
2. Institute of Industrial Electrical Engineering, Faculty of Electrical Engineering, Czestochowa University of Technology, al. Armii Krajowej 17, 42-200 Częstochowa, Poland