Funding for this research was provided by:
the National Natural Science Foundation of China (51678075)
Hunan Provincial Natural Science Foundation of China (2017JJ2015)
Article History
Received: 30 December 2017
Accepted: 3 March 2018
First Online: 9 March 2018
Compliance with ethical standards
:
: The authors declare that there is no conflict of interests regarding the publication of this paper (such as financial gain).