unique "atomic age" c. 1953 oversized stainless steel wall plaque salvaged from the lobby of the max straus tumor clinic building (chicago, il). some of the primary functions of this radioisotope facility involved educational research on the safe handling of radioactive isotopes. while there are many methods of research on ri, the facility primarily uses two methods: namely the use of radiation as a marker (radioassay, or tracer, method), and the use of the radioactive isotope fixed-radioactive half-life method (radiometric age measurement method). a radioisotope is a version of a chemical element that has an unstable nucleus and emits radiation during its decay to a stable form. radioisotopes have important uses in medical diagnosis, treatment, and research. the stylized lettering used to highlight the "chicago no. 16 radioisotope project" are deeply embossed with original baked black enameled finish. the wall-mount plaque was formerly dedicated in 1953. sign fabricator unknown. measures 60 x 21 1/4 inches.