Funding for this research was provided by:
the National Natural Science Foundation of China (31670956)
Received: 15 January 2020
Accepted: 4 March 2020
First Online: 12 March 2020
Ethics approval and consent to participate
: This study was approved by the ethics committee of the Affiliated Lianyungang Hospital of Xuzhou Medical University (No. 2016008), and informed consent was signed by the volunteer and his family members.
: Not applicable.
: The authors declare that they have no competing interests.