1. Micro/Nano Science and Technology Center, Jiangsu University, Zhenjiang 212013, P. R. China
2. Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
3. State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian 116024, P. R. China
4. Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, P. R. China