Feng, Xiaozhou
Sun, Suping
Zhang, Tongqian
An, Xiaomin
Funding for this research was provided by:
the National Natural Science Youth Fund of China (61102144)
The Shaanxi Province Department of Education Fund (14JK1353)
The Shandong Provincial Natural Science Foundation of China (ZR2015AQ001)
The president of Xi'an Technological University Foundation (XAGDXJJ1423)
Article History
Received: 2 November 2017
Accepted: 3 April 2018
First Online: 16 May 2018
Competing interests
: The authors declare that they have no competing interests.