1. a Department of Biological and Chemical Engineering, Faculty of Engineering , Gunma University , Tenjin-cho 1-5-1, Kiryu, Gunma , 376 , Japan
2. b Japan Atomic Energy Research Institute Takasaki Radiation Chemistry Research Establishment , Watanuki-machi 1233, Takasaki-shi, Gunma , 370-12 , Japan
3. c Department of Biological Sciences, Faculty of Science Kanagawa , University Hiratsuka , Kanagawa , 259-12 , Japan