Chen, H
Shi, R
Luo, B
Yang, X
Qiu, L
Xiong, J
Jiang, M
Liu, Y
Zhang, Z
Wu, Y
Article History
Received: 30 May 2014
Revised: 18 October 2014
Accepted: 5 November 2014
First Online: 15 January 2015
Competing interests
: The authors declare no conflict of interest.