Funding for this research was provided by:
The National Natural Science Foundation of China (61102062,61301122)
The Key Project of Chinese Ministry of Education (212145)
The Research Project of Chongqing Education Commission (KJ120530, KJ1400405)
NSF of Chongqing (cstc2014jcyjA40052)
NSF of CQUPT (A2013-30)
The Doctor Science Research Starting Foundation of CQUPT (A2013-23)