Chemists are architects on a tiny scale. They design and build molecules, structures composed of atoms. By precisely combining chemicals and sometimes using catalysts, molecules that help a chemical reaction happen more quickly, chemists create materials suited to all sorts of different uses, from gasoline to carbon fiber to lifesaving medicines. They also investigate the molecular structure of different types of already-existing matter. Biochemist and Cancer Researcher Eugene DeSombre discovered how different breast cancers react to estrogen and developed a test for that, helping doctors figure out how to treat different cancer patients. Physical Chemist Barbara Hopf Offenhartz studied the molecular structure of vitamin B12 and of hemoglobin, the chemical that makes blood red. Peter O’Donnell Offenhartz (married to Barbara) used his expertise in physical chemistry to investigate ways of improving different forms of alternative energy including solar and geothermal power. He worked with various kinds of batteries, used computers to explore the structure of complicated molecules, and helps solve his neighbors’ communication and technology problems.