Funding for this research was provided by:
National Science Foundation of China ((31870206))
Innovation of Science and Technology Commission of Shenzhen (JSGG20140515164852417)
Scientific Research Project of Shenzhen Urban Administration (201519)
Scientific Research Program of Sino- Africa Joint Research Center (SAJL201607)
Article History
Received: 31 March 2020
Accepted: 8 June 2020
First Online: 27 June 2020
Compliance with ethical standards
:
: All authors declare no conflict of interest.