1. Department of Physics; Faculty of Electrical Engineering and Informatics, Technical University of Košice; Park Komenského 2 042 00 Košice Slovakia
2. Polymer Institute; Slovak Academy of Sciences; Dúbravská cesta 9 845 41 Bratislava Slovakia
3. Institute of Natural and Synthetic Polymers; Slovak University of Technology; Radlinského 9 812 37 Bratislava Slovakia
4. Department of Ceramics; Faculty of Metallurgy, Technical University of Košice; Park Komenského 19 042 00 Košice Slovakia