Funding for this research was provided by:
Fundamental Research Funds for the Central Universities (2019WP04)
Received: 24 April 2019
Accepted: 4 July 2019
First Online: 18 July 2019
Ethics approval and consent to participate
: The study received approval from the Ethical Committee of China University of Mining and Technology. Participants provided written informed consent.
: Consent for publication was obtained from each participant during the informed consent process.
: The authors declare that they have no competing interests.