Funding for this research was provided by:
Received: 1 June 2018
Accepted: 3 September 2018
First Online: 1 October 2018
Ethics approval and consent to participate
: The study protocol was approved by local ethics committee. All phases of the study were carried out in conformity with the principles expressed in the Declaration of Helsinki. Written informed consent was obtained according to Chinese law.
: The study was approved by ethic committee of Zhengzhou University. The informed consents were obtained from all subjects or their guardians.
: The authors declare that there are no competing interests.
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