Funding for this research was provided by:
National Natural Science Foundation of China (61674113, 51622507, 61471255)
Natural Science Foundation of Shanxi Province (2016011040)
Scientific and Technologial Innovation Programs of Higher Education Institutions (2016138)
Article History
Received: 4 August 2018
Accepted: 31 October 2018
First Online: 8 November 2018