A U.S. Air Force fighter-jet machine-gun mechanic from Columbus, Ohio, introduces a high-performance problem-solver; an entrepreneur from Queens, New York, hopes the Sharks bite into a DNA test that aims to aid and optimize medical research; a Dallas, Texas, entrepreneur duo hopes to lure the Sharks with their high-tech solution for a common household chore; robots and drones are all the rage with boys, but one Bethesda, Maryland, entrepreneur is hoping to encourage more girls to get into coding and technology.