Funding for this research was provided by:
National Natural Science Foundation of China (NSFC) (51505095)
Natural Science Foundation of Guangxi Province (2016GXNSFBA380114)
Innovation Project of Guet Graduate Education (2018YJCX04.)
Article History
Received: 26 April 2018
Accepted: 24 August 2018
First Online: 3 September 2018
Competing interests
: The authors declare that they have no competing interests.
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