1. Department of Materials Science, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa 259-1293, Japan, Department of Applied Chemistry, Faculty of Engineering, Kanagawa University, Rokkakubashi, Yokohama, Kanagawa 221-8686, Japan, and Meiji Cell Technology Center, Meiji Milk Products Co., 540 Naruda, Odawara, Kanagawa 250-0862, Japan