1. a School of Materials Science, Japan Advanced Institute of Science and Technology , 1-1 Asahidai, Nomi , 923-1292 , Japan
2. b Systems and Structural Biology Center, RIKEN , 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama , 230-0045 , Japan
3. c Center for Fiber and Textile Science, Kyoto Institute of Technology , Matsugasaki, Kyoto , 606-8585 , Japan