Funding for this research was provided by:
the Key Program of National Natural Science Foundation of China (61133005, 61432005)
the National Natural Science Foundation of China (61370095, 61472124)
the National Natural Science Foundation of China (61572175)
International Science & Technology Cooperation Program of China (ID0E33AE3480)
Research Project of the Education Department of Hunan Province (ID0EI5AE3481)
Article History
Received: 22 October 2017
Revised: 3 December 2017
Accepted: 22 December 2017
First Online: 13 January 2018