1. Laboratory of Controllable Preparation and Application of Nanomaterials Technical Institute of Physics and Chemistry Chinese Academy of Sciences CAS Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Beijing 100190 P. R. China
2. School of Optoelectronic Science and Engineering University of Electronic Science and Technology of China Chengdu Sichuan 610054 P. R. China
3. Department of Radiology First Hospital of China Medical University Shenyang 110001 P. R. China
4. University of Chinese Academy of Sciences Beijing 100049 P. R. China