[1] Nankai Univ, TEDA Appl Phys Inst, Tianjin 300457, Peoples R China
[2] Nankai Univ, Sch Phys, Tianjin 300457, Peoples R China
[3] INRS EMT, 1650 Blvd Lionel Boulet, Varennes, PQ J3X 1S2, Canada
[4] Univ Zagreb, Fac Civil Engn, A Kacica Miasica 26, Zagreb 10000, Croatia
[5] Univ Zagreb, Fac Sci, Dept Phys, Bijenicka C 32, Zagreb 10000, Croatia
[6] Univ Elect Sci & Technol China, Inst Fundamental & Frontier Sci, Chengdu 610054, Sichuan, Peoples R China
[7] San Francisco State Univ, Dept Phys & Astron, San Francisco, CA 94132 USA