Science Foundation for Distinguished Young Scholars of Hunan Province, ChinaNational Natural Science Foundation of China (NSFC)National Science Fund for Distinguished Young Scholars [10JJ1005]; Research Fund for the Doctoral Program of Higher Education of ChinaResearch Fund for the Doctoral Program of Higher Education of China (RFDP)Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) [200805370002]; Team Project for the Technology Innovation of Higher Education of Hunan Province, China