Funding for this research was provided by:
National Natural Science Foundation of China (11501438, 11501076)
Natural Science Basic Research Plan in Shaanxi Province of China (2018JM1035)
the Young Talent fund of University Association for Science and Technology in Shaanxi (20170607)
Article History
Received: 23 May 2019
Accepted: 14 October 2019
First Online: 21 October 2019
Competing interests
: The authors declare that they have no competing interests.