Funding for this research was provided by:
National Natural Science Foundation of China (11502073)
Scientific Research Fund of Henan Provincial Education Department (14A110004)
Doctoral Foundation of Henan Polytechnic University (B2012-107)
Article History
Received: 12 January 2018
Accepted: 2 April 2018
First Online: 11 May 2018
Compliance with ethical standards
:
: The authors declared that they have no conflict of interest.