Funding for this research was provided by:
National Natural Science Foundation of China (71603136)
Nantong Municipal Science and Technology Bureau (MSI2017016-4)
National Natural Science Foundation (71702131)
Article History
Received: 11 October 2018
Accepted: 22 December 2019
First Online: 2 January 2020
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of Nantong University (NO 2017120). All respondents were informed about the aim of the survey, the selection criterion of the sample, and the assurance that the information was only for research. Respondents gave written informed consent before inclusion in the study.
: Not applicable.
: The authors declare that they have no competing interests.