Smart Lists are a great way to keep your library organized; you tell them to organize things in a certain way, and every time you add something to your library, the smart list will look to see if that item meets the rule you set for the collection and if so, bring it in automatically.
Your Smart List query can be anything you can search for in your library and be as complex as you need to narrow down results. See some popular examples below.
(To add these to your personal library, simply click on the one you would like to add and you'll be taken to that Smart List's new location in your library)
Unread within papers added in last 7 days
Unread within papers added in last 14 days
Unread within papers added in last 30 days
To make your own Smart List, click on the Settings icon of your personal library and select "Create Smart List":
With the Smart List above set up, everytime an article is added to "My Papers", the app will check to see if the word "lexapro" appears in the article and, if it does, it will automatically add it to the Smart List "OCD Research".