Ma, Jie
Xie, Guoqiang
Lv, Peng
Gao, Wenlan
Yuan, Peng
Qian, Liejia
Griebner, Uwe
Petrov, Valentin
Yu, Haohai
Zhang, Huaijin
Wang, Jiyang
Article History
Received: 26 September 2013
Accepted: 2 May 2014
First Online: 23 May 2014
Competing interests
: The authors declare no competing financial interests.