1. Textile Engineering Department, Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia, Vinča Institute of Nuclear Sciences, P. O. Box 522, 11001 Belgrade, Serbia, Institute of Physics, Pregrevica 118, 11080 Zemun, Serbia, and Department of Bioengineering and Biotechnology, Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia