Du, William W
Fang, Ling
Yang, Weining
Wu, Nan
Awan, Faryal Mehwish
Yang, Zhenguo
Yang, Burton B
Article History
Received: 28 June 2016
Revised: 11 October 2016
Accepted: 14 October 2016
First Online: 25 November 2016
Competing interests
: The authors declare no conflict of interest.