Funding for this research was provided by:
China Scholarship Council (201608140214)
National Natural Science Foundation of China (11371313, 61573016)
Foundation of Yuncheng University (YQ-2017003, YQ-2014011)
Received: 24 August 2018
Accepted: 2 October 2018
First Online: 11 October 2018
: The authors declare that they have no competing interests.