Funding for this research was provided by:
the Major Program of National Natural Science Foundation of China (51490662)
the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (51621004)
the National Science Fund for Distinguished Young Scholars (51725502)
the Natural Science Foundation of Hunan Province of China (2017JJ2012)
the Educational Commission of Hunan Province of China (17A036)
Article History
Received: 10 October 2018
Revised: 18 December 2018
Accepted: 5 February 2019
First Online: 13 March 2019