In 1.3: Atlas Rises, some old blueprints from the Scientist NPC, and their corresponding products have been deprecated and re-introduced for balancing reasons. For example, if you had learned the Voltaic Cells recipe pre-update, then this blueprint will no longer be accessible. Similarly, any old Voltaic Cells you had created pre-update will be marked 'Obsolete' (Note: these can still be sold for the same amount at the Galactic Marketplace).
To re-learn these recipes, simply re-hire your Scientist and run through their missions again. Note: if you find your Scientist isn't offering you missions, try completing missions for your Overseer (construction) NPC instead.