A preprint is a complete draft research paper made available in open access on a preprint web server before being certified by peer review and published by a journal. Publication of manuscripts in a peer-reviewed journal often takes weeks or months from the time of initial submission. Preprints allow authors to receive early feedback from their peers, which may help revise and prepare articles for submission. However, the revised manuscripts after or during peer-reviewed are not recommended to be post on the prepress server. The manuscript whose corresponding preprint version has been indexed (e.g. in MEDLINE or PubMed) will not be considered.