He 'kept/maintained his cool' [=he didn't get angry or upset] even though it was clear that he was being unfairly treated.
He was struggling to 'maintain his cool/composure'. [=he was struggling not to become angry or upset]
They barely had enough food to 'maintain life'. [=to make it possible for life to exist or continue]
(..) as a gyroscope? Wow. I've never thought about that. And since it's in a quantum state, it would maintain an infinite persistence. Groundbreaking revelations, tropical drinks. Tell me this isn't like the best episode of (..)2016 TvShow: The Big Bang Theory Title: The Positive Negative Reaction Season: 9 Episode 16