1. Department of Materials Science & Metallurgy; University of Cambridge; 27 Charles Babbage Road Cambridge CB3 0FS United Kingdom
2. Division of Trauma & Orthopaedic Surgery; Box 180, Addenbrooke's Hospital; Hills Road Cambridge CB2 0QQ United Kingdom
3. Faculty of Chemistry; Materials & Bioengineering; Department of Chemistry & Materials Engineering; Kansai University; 3-3-35 Yamate-Cho Suita, Osaka 564-8680 Japan