Funding for this research was provided by:
National Natural Science Foundation of China (61502158)
National Natural Science Foundation of China (61572354)
Fundamental Research Funds for the Central Universities (531107040842)
City University of Hong Kong (CityU 11259516)
Article History
Received: 27 September 2016
Revised: 31 May 2017
Accepted: 25 June 2017
First Online: 4 July 2017