Nothing to see here. Zero*.
Briefly looking at the abstracts available here, they are nothing like a scientific abstract only a teaser for the article. The whole point of a free app is to give some free content, to entice the reader and make it worthwhile. Not here! This is not found in Natures app the "articles" and "editorial" reviewed. Even the editorial is not posted online. All else requires in app purchase to read any of the content. Avoid this app.
Insomnia. about
NatureJournals