Article History
Received: 2 December 2019
Revised: 2 December 2019
Accepted: 21 January 2020
First Online: 3 February 2020
Compliance with ethical standards
:
: Author Liu Zi-xian, Zhang De-gan, Luo Gu-zhao, Lian Ming and Liu Bing 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.
: Informed consent was obtained from all individual participants included in the study.