1. Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
2. Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto 602-8566, Japan
3. Department Polytechnic of Engineering and Architecture, University of Udine, 33100 Udine, Italy
4. Biomedical Research Center, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan