1. School of Science and Technology, Kobe University, Nada-ku, Rokkodai-cho 1-1, Kobe 657-8501, Japan; Department of Chemistry and Chemical Technology, University of Bradford, Bradford, W. Yorkshire BD7 1DP, United Kingdom; Fundamental Research Laboratory of Fibers and Fiber-forming Polymers, Asahi Chemical Industry Co., Ltd., 11-7 Hachonawate, Takatsuki, Osaka 569, Japan; and Department of Informatics, University of Wales, Bangor, Bangor Gwynedd LL57 2DG, Wales