Wang, Xinjiang
Huang, Baoling
Article History
Received: 3 April 2014
Accepted: 28 August 2014
First Online: 17 September 2014
Change Date: 20 January 2015
Change Type: Update
Change Details: A correction has been published and is appended to both the HTML and PDF versions of this paper. The error has not been fixed in the paper.
Competing interests
: The authors declare no competing financial interests.