Ma, J-x
Yan, B-x
Zhang, J
Jiang, B-H
Guo, Y
Riedel, H
Mueller, M D
Remick, S C
Yu, J J
Article History
Received: 11 June 2014
Revised: 24 July 2014
Accepted: 28 July 2014
First Online: 4 September 2014
Competing interests
: The authors declare no conflict of interest.