Funding for this research was provided by:
National Natural Science Foundation of China (11572056)
Natural Science Foundation of Hunan Province (2018JJ3533)
Education Department of Hunan Province (17B008)
China Scholarship Council (201700800002)
Article History
Received: 16 January 2019
Accepted: 2 July 2019
First Online: 26 July 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interests regarding the publication of this paper.