Funding for this research was provided by:
National Science Foundation (1449860, 1218156 and 1350521)
National Natural Science Foundation of China (61402081)
National Natural Science Foundation of China (61572333)
863 Program of China (2015AA016405)
Fundamental Research Funds for the Central Universities of China (ZYGX2014J059)
China Scholarship Council ([2015]3012)
the Oversea Academic Training Funds, UESTC
Article History
First Online: 5 May 2016