Funding for this research was provided by:
National Natural Science Foundation of China (51374092)
National Natural Science Foundation of China (51774111)
Joint Fund of Coal (U1261206)
Innovation and Outstanding Talent Project of Henan Province Science and Technology (184200510003)
Article History
Received: 29 August 2018
Accepted: 5 January 2019
First Online: 24 January 2019
Compliance with ethical standards
:
: The authors declare no conflict of interest.