1. National Institute of Materials Physics; P.O. Box MG 07 Magurele Romania
2. Collagen Department; National Research & Development Institute for Textiles and Leather (INCDTP)-Division, Leather and Footwear Research Institute; Ion Minulescu Str.93 Bucharest 031215 Romania
3. Department of Strength of Materials; University Politehnica of Bucharest, Faculty of Engineering and Management of Technological Systems; 313 Splaiul Independentei Bucharest Romania