National Fundamental Research Program [2007CB925204]; National Natural Science FoundationNational Natural Science Foundation of China (NSFC) [10775048, 11075050]; Program for Changjiang Scholars and Innovative Research Team in UniversityProgram for Changjiang Scholars & Innovative Research Team in University (PCSIRT) [IRT0964]; Hunan Provincial Education DepartmentHunan Provincial Education Department [08W012]