Chen, Yan
Chen, Bei
Yang, Ti
Xiao, Weiming
Qian, Li
Ding, Yanbing
Ji, Mingchun
Ge, Xiaoqun
Gong, Weijuan
Article History
Received: 13 November 2014
Revised: 1 August 2015
Accepted: 1 August 2015
First Online: 14 September 2015
Competing interests
: All authors have declared there are no financial conflicts of interest with regard to this work.