Duan, Zheng
Smith, Andrew
Yang, Liu
Youngblood, Brian
Lindner, Jürgen
Demidov, Vladislav E.
Demokritov, Sergej O.
Krivorotov, Ilya N.
Article History
Received: 13 June 2014
Accepted: 21 October 2014
First Online: 5 December 2014
Competing interests
: The authors declare no competing financial interests.