The nature and types of internal molecular and thermal motions that polymer chains and polymer segments undergo have a great bearing on the physical behavior of polymeric solids. A relatively new tool is now available that permits us to observe and study internal thermally-induced motions directly at the atomic or molecular level rather than from macroscopic observations. this tool is nuclear magnetic resonance spectroscopy. This talk discusses (1) the nature of nuclear magnetic resonance, (2) NMR line shapes and the influence of temperature, (3) NMR line widths and second moments as a function of temperature, and (4) lists six general conclusions.

Summary. Cattle in Reno, Nevada, exhibit a constant very low concentration of I 131 in their thyroid glands in the absence of known releases of I 131 to the atmosphere. This concentration is about 1 picocurie per gram of fresh thyroid tissue. ; This I 131 appears to originate below the tropopause