Mao, Renfang
Yang, Riyun
Chen, Xia
Harhaj, Edward W
Wang, Xiaoying
Fan, Yihui
Article History
Received: 3 September 2016
Revised: 17 November 2016
Accepted: 17 November 2016
First Online: 13 February 2017
Competing interests
: The authors declare no conflict of interest.