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Article History

Received: 17 July 2018

Revised: 10 December 2018

Accepted: 5 April 2019

First Online: 30 April 2019

Compliance with ethical guidelines

:

: J. Nie, Q. Shi, Z. Kong, C.K. Lao, H. Zhang and T.K. Tong declare that they have no competing interests.

: All procedures performed in studies involving human participants or on human tissue were in accordance with the ethical standards of the institutional and/or national research committee and with the 1975 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.