Funding for this research was provided by:
National Natural Science Foundation of China (81401132, 81401132)
Department of Science and Technology of Sichuan Province (18ZDYF3200)
Chengdu University of Technology (KYTZ201637)
the Youth Foundation for Humanities and Social Sciences of Ministry of Education of China under Grant 17YJCZH202
Article History
Received: 15 January 2018
Accepted: 19 October 2018
First Online: 2 November 2018
Competing Interests
: The authors declare no competing interests.