1. Research Center for Functional Materials, National Institute for Materials Science (NIMS), Tsukuba, Japan
2. Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan
3. Department of Radiation Oncology, University of Tsukuba Hospital, Tsukuba, Japan
4. Graduate School of Advanced Engineering, Department of Materials Science and Technology, Tokyo University of Science, Katsushika-ku, Japan