Funding for this research was provided by:
National Natural Science Foundation of China (81703539, No. 31371070 and 81671264)
Fundamental Research Funds for the Central Universities (15ykjc08b)
Guangdong Provincial International Cooperation Project of Science & Technology (2013B051000038)
Received: 21 March 2019
Accepted: 18 June 2019
First Online: 14 August 2019
Compliance with ethical standards
: All authors declare that they have no conflicts of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: For this type of study, formal consent is not required.