Li, H
Zhao, X
Yan, X
Jessen, W J
Kim, M-O
Dombi, E
Liu, P P
Huang, G
Wu, J
Article History
Received: 13 November 2014
Revised: 12 February 2015
Accepted: 10 May 2015
First Online: 15 June 2015
Competing interests
: The authors declare no conflict of interest.