Funding for this research was provided by:
National Natural Science Foundation of China (Nos. 81430055)
Guangxi Science and Technology Base and Talent Special Project (No. AD17129003)
Changjiang Scholars and Innovative Research Team in University (No. IRT_15R13)
Received: 14 December 2018
Accepted: 12 June 2019
First Online: 9 July 2019
: The authors declare that they have no competing interests.
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