Funding for this research was provided by:
National Natural Science Foundation of China (41271167)
Hunan Provincial Department of Education of China (17A067)
State Administration of Foreign Experts Affairs (GWD201543000243)
National Science Foundation (OCE-1637630)
Article History
Received: 26 August 2017
Revised: 11 March 2018
Accepted: 16 April 2018
First Online: 5 June 2018
Compliance with ethical standards
:
: The authors declare they have no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.