Funding for this research was provided by:
Social Development Program of Ningbo, China (2013C50044)
Social Development and Science & Technology Program of Zhenhai, Ningbo, China (2016S009)
Received: 10 August 2018
Accepted: 6 December 2018
First Online: 21 January 2019
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Hospital of Zhenhai Refine-Chemical Company, Ningbo, China. Informed written consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare no conflict of interest.
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