Funding for this research was provided by:
the Fundamental Research Funds for the China University of Mining and Technology (2017XKQY063)
Article History
Received: 10 June 2019
Accepted: 9 July 2019
First Online: 15 July 2019
Compliance with ethical standards
:
: On behalf of all authors, the corresponding author states that there is no conflict of interest.
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