Hu, J
Chu, Z
Han, J
Zhang, Q
Zhang, D
Dang, Y
Ren, J
Chan, H C
Zhang, J
Huang, Y
Article History
Received: 20 April 2014
Revised: 9 July 2014
Accepted: 23 July 2014
First Online: 18 September 2014
Competing interests
: The authors declare no conflict of interest.