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Article History

Received: 6 March 2018

Accepted: 14 June 2018

First Online: 29 June 2018

Compliance with ethical standards

:

: No funding was received for this study.

: The authors declare that they have no conflict of interest.

: All procedures performed in the studies involving human participants were in accordance with the ethical standards of the the medical ethics committee of the First Affiliated Hospital of Zhengzhou University, China, and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

: Informed consent was obtained from all individual participants included in the study.