Funding for this research was provided by:
National Natural Science Foundation of China (61773282, 61873186)
the Application Base and Frontier Technology Research Project of Tianjin of China (13JCQNJC03600)
South African National Research Foundation (112142, 112108)
South African National Research Foundation Incentive Grant (114911)
Tertiary Education Support Programme (TESP) of South African ESKOM
Article History
Received: 2 January 2019
Accepted: 5 November 2019
First Online: 21 November 2019
Compliance with ethical standards
:
: The authors declare that they have no conflicts of interest.