Li, Bing
Sheng, Minjie
Li, Jianhua
Yan, Guoquan
Lin, Anjuan
Li, Min
Wang, Weifang
Chen, Yihui
Article History
Received: 20 December 2013
Accepted: 2 June 2014
First Online: 27 August 2014
Competing interests
: The authors declare no competing financial interests.