Funding for this research was provided by:
TianYuan Special Fund of the National Natural Science Foundation of China (11426068)
Project for Young Creative Talents of Ordinary University of Guangdong Province (2014KQNCX228)
PhD Start-up Fund of Natural Science Foundation of Guangdong Province (2014A030310330)
Fund for Science and Technology of Guangzhou (201607010352)
Article History
Received: 24 July 2018
Accepted: 7 September 2018
First Online: 20 September 2018
Competing interests
: The authors declare that there are no competing interests.