Funding for this research was provided by:
Ministry of Education of China for an Innovative Research Team in University grant (IRT_17R88)
Received: 16 July 2020
Accepted: 9 December 2020
First Online: 6 January 2021
Ethics approval and consent to participate
: The protocol used in this study was in accordance with the Declaration of Helsinki and was approved by the Ethics Committee at Northwest Minzu University Lanzhou, China. Written consent was individually obtained from the participants.
: All authors declare they have no actual or potential competing interests.