Funding for this research was provided by:
National Natural Science Foundation of China (71503137)
Received: 17 September 2017
Accepted: 24 January 2018
First Online: 2 February 2018
Ethics approval and consent to participate
: This study was approved by the Academic Research Ethics Committee of Nanjing Medical University; reference number: 2,017,602. All procedures were in accordance with the ethical standards of the Helsinki Declaration. Participants provided informed consent prior to data collection.
: Not applicable.
: The authors declare that they have no competing interests.
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