Funding for this research was provided by:
National Natural Science Foundation of China (61671464, 61471389, 61701523, 61801508)
Natural Science Foundation of Shanxi Province (2018JM6040)
Article History
Received: 29 November 2018
Accepted: 15 March 2019
First Online: 29 March 2019
Competing Interests
: The authors declare that they have no competing interests.
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