read directly. More significant is the fact that information theory predicts that cross-correlation enhances the signalto-noise ratio (11, 12). This allows greater resolution than could be obtained via Lissajous figures.The instrument described above has been demonstrated to be well suited to its primary task of measuring high impedance systems at low frequencies using minimal excitation. However, the potential of the correlation method for use in systems where conductivity is a dynamic parameter (11) G. M. Heiftje, Anal. Chem., 44(6), 81A (1972). ( 12) G. M. Heiftje, Anal. Chem., 44(7), 69A (1972).should not be underestimated, particularly since the necessary equipment is available commercially or may be constructed in the laboratory at low cost. The instrument may be easily modified to function in either the impedance or the admittance mode. In addition, the nature of the instrumental response makes it applicable to a wide variety of problems.

Generator nuclides constitute a convenient tool for applications in nuclear medicine. In this paper, some radiochemical aspects of generator nuclide parents regularly processed at Los Alamos are introduced. The bulk production of the parent nuclides

No abstract

In December of 1989, the United States Food and Drug Administration approved

Plutonium oxide pellets (80% ^'*Pu, 40 g each) were exposed to fresh water and sea water at two temperatures for 3 yr in enclosed glass chambers. The concentrations of plutonium observed in the waters increased linearly with time throughout the experiment. However, the observed release rates were inversely dependent on temperature and salinity, ranging from 160)iCi/day for cold fresh water to 1.4 nCi/day for warm sea water. The total releases, including the chamber residues, showed similar dependencies. A major portion (typically greater than 50%) of the released plutonium passed through a 0.1-|im filter, with even larger fractions (greater than 80%) for the fresh water systems.