1. State
Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China
2. Department
of Materials Science and Engineering, University of Sheffield, Mappin
Street, Sheffield S1 3JD, U.K.
3. Institute
of Chemistry, Organic Chemistry, Martin-Luther-University Halle-Wittenberg, D-06120 Halle, Germany
4. Department
of Physics, Zhejiang Sci-Tech University, Xiasha College Park, Hangzhou 310018, P. R. China