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Article History

Received: 2 November 2017

Accepted: 5 April 2018

First Online: 20 April 2018

Ethics approval and consent to participate

: This article does not contain any studies with human participants or animals performed by any of the authors. The experimental protocol was established according to the ethical guidelines of the Helsinki Declaration, and ethical approval for this study was provided by Dalian University Affiliated Zhongshan Hospital. All patients or guardians, after reading, filled in and signed the consent form and agreed to participate in the study.

: The authors declare that they have no competing interests.

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