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Article History

Received: 14 April 2018

Accepted: 4 June 2018

First Online: 9 June 2018

Compliance with ethical standards

: All our studies are in compliance with ethical regulations of Yidu Central Hospital of Weifang.

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

: This article does not contain any studies with human participants or animals performed by any of the authors.

: Not applicable.