1. Fundamental Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501, Japan, Department of Biological Resource Chemistry, Kyoto Prefectural University, Shimogamo, Kyoto 606-8522, Japan, Faculty of Engineering and Design, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan