1. Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
2. ZEON Corporation, 1-6-2 Marunouchi, Chiyoda-ku, Tokyo 100-8246, Japan
3. Japan Science and Technology Agency (JST), Kawaguchi, 332-0012, Japan