Funding for this research was provided by:
the Natural Science Foundation of Guangdong Province (No. 2017A030310245)
the Science and Technology Program of Guangzhou City (NO. 201804010195)
Text and Data Mining valid from 2018-09-12
Received: 2 July 2018
Accepted: 28 August 2018
First Online: 12 September 2018
: The authors declare that they have no competing interests.
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