Han, F
Liu, W
Jiang, X
Shi, X
Yin, L
Ao, L
Cui, Z
Li, Y
Huang, C
Cao, J
Liu, J
Article History
Received: 26 February 2014
Revised: 18 September 2014
Accepted: 3 October 2014
First Online: 1 December 2014
Competing interests
: The authors declare no conflict of interest.