1. Daicel Corporation, 1239, Shinzaike, Aboshi-ku, Himeji, Hyogo 671-1283, Japan
2. Electron Microscope Unit, Mark Wainwright Analytical Centre and School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052, Australia
3. Graduate School of Engineering Science, Osaka University, 1-3, Machikaneyama, Toyonaka, Osaka 560-8531, Japan