National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [11301172, 11226170, 11331005]; China Postdoctoral Science Foundation funded projectChina Postdoctoral Science Foundation [2012M511640]; Hunan Provincial Natural Science Foundation of ChinaNatural Science Foundation of Hunan Province [13114095]; Scientific Research Fund of Hunan Provincial Education DepartmentHunan Provincial Education Department [14B077]; Program for Changjiang Scholars and Innovative Research Team in UniversityProgram for Changjiang Scholars & Innovative Research Team in University (PCSIRT) [IRT13066]; Special Fund Basic Scientific Research of Central Colleges [CCNU12C01001]