Funding for this research was provided by:
Natural Science Foundation of Guangdong Province (2015A030313896)
Characteristic Innovation Project (Natural Science) of Guangdong Province (2015KTSCX097)
Science and Technology Program Project of Guangzhou (201707010230)
Article History
Received: 1 April 2018
Accepted: 31 July 2018
First Online: 9 August 2018
Competing interests
: The authors declare that they have no competing interests.