Who is Mr. John Loomis from Z for Zachariah and what is their importance?

Mr. Loomis is a scientist who worked with a team who invented a material that repels radiation. The group made a suit out of this material, as well as a filter for water and containers for food. The team was waiting for the military to come inspect the invention when war breaks out and the United States is devastated by a nuclear holocaust. Mr. Loomis is locked in his lab with another scientist. This scientist wants to take the suit and find his family, but Mr. Loomis refuses. Mr. Loomis kills his co-worker when the man refuses to back down.