Funding for this research was provided by:
National Natural Science Foundation of China (61370102)
Guangdong Natural Science Funds for Distinguished Young Scholar (2014A030306050)
Guangdong High-level personnel of special support program (2014TQ01X664)
the Ministry of Education - China Mobile Research Funds (MCM20160206)
Article History
First Online: 6 March 2018
Compliance with ethical standards
:
: All authors of this paper declare that we have no conflict of interest.
: This paper does not contain any studies with human participants or animals. This paper has not been submitted to more than one journal and it has not been published previously.