1. Department of Materials Chemistry, Graduate School of Engineering, Tohoku University, Aoba-yama 07, Sendai 980-8579, Japan, Department of Mathematics, Faculty of Engineering, Hiroshima Kokusai Gakuin University, Hiroshima, 6-20-1 Nakano, Aki-ku, Hiroshima 739-0312, Japan, and New Industry Creation Hatchery Center, Tohoku University, Aoba-yama 04, Sendai 980-8579, Japan