Funding for this research was provided by:
the scientific research cultivation fund of Xi'an University of Science and Technology in China (201635)
the PhD research startup foundation of Xi'an University of Science and Technology in China (2015QDJ072)
the natural science foundation of Shaanxi province in China (2017JQ6053)
the national natural science foundation of China (61702408)
Article History
Received: 27 September 2017
Revised: 4 February 2018
Accepted: 15 May 2018
First Online: 22 May 2018