Sun, Jing
Wang, Heng
Ren, Liping
Chen, Sumei
Chen, Fadi
Jiang, Jiafu
Article History
Received: 28 November 2016
Revised: 2 January 2017
Accepted: 8 January 2017
First Online: 15 February 2017
Competing interests
: The authors declare no conflict of interest.