Before revision: Cryogenic engineering is a sub stream of mechanical engineering dealing with cryogenics, and related very low temperature processes such as air liquefaction, cryogenic engines (for rocket propulsion), cryogenic surgery .
After revision: Cryogenic engineering is a sub stream of mechanical engineering dealing with cryogenics, and related very low temperature processes such as air liquefaction, cryogenic engines (for rocket propulsion), cryosurgery .