National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [21372092, 21102051]; Natural Science Foundation of Hubei ProvinceNatural Science Foundation of Hubei Province [2013CFA112, 2014CFB246]; Self-determined research funds of CCNU from the colleges' basic research and operation of MOE [CCNU14Z01001, CCNU13F005]