1. Laboratory of Advanced Polymers and Optimized Materials (LAPOM), Department of Materials Science, University of North Texas, Denton, TX 76203-5310, USATel.: , Fax:
2. Department of Mechanical and Biomechanical Engineering, Cracow University of Technology, Warszawska 24, 31-155 Cracow, Poland
3. Southwestern Medical Center, University of Texas at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75235; now at Lally School of Management and Technology, Rensselaer Polytechnic Institute, 110 8th St., Troy, NY 12180-3590, USA
4. Currently at Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET)—Universidad Nacional de Mar del Plata, J.B. Justo 4302, 7600 Mar del Plata, Argentina