1. Biomaterials Field, Research Center for Functional MaterialsNational Institute for Materials Science 1‐1 Namiki Tsukuba Ibaraki 305‐0044 Japan
2. Digestive and Lifestyle DiseasesDepartment of Human and Environmental SciencesKagoshima University Graduate School of Medical and Dental Sciences 8‐35‐1 Sakuragaoka Kagoshima 890‐8544 Japan