1. Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Rokko, Nada, Kobe 657-8501, Japan
2. Technical Support Center for Leather Industries, Hyogo Prefectural Institute of Technology, 3 Nozato, Himeji 670-0811, Japan
3. Materials and Analysis Department, Hyogo Prefectural Institute of Technology, 3-1-12 Yukihiracho, Kobe 654-0037, Japan