Funding for this research was provided by:
National Natural Science Foundation of China (11374096)
National Natural Science Foundation of China (11374096)
Natural Science Foundation of Hunan Province (14jj6035)
Science Research Foundation of Education Department of Hunan Province (14B147)
Article History
Received: 28 December 2016
Accepted: 11 January 2018
First Online: 1 February 2018