Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
Ibaraki University, 162-1, Shirakata, Tokai, Naka, Ibaraki, 319-1106, Japan