[en] Long-term potentiation of the hippocampal slice preparation results in an increase in the incorporation of labeled valine into the proteins destined for secretion into the extracellular medium. Double-labeling methods established that the increased secretion of the labeled proteins was limited to the potentiated region of a slice; incorporation of labeled valine was increased in the hippocampus if potentiation was through the Schaffer collaterals and in the dentate if potentiation was through the perforant path. Controls for nonspecific stimulation showed no changes. There appears to be a link between long-term potentiation and the metabolic processes that lead to protein synthesis in the hippocampal slice system

[en] Distribution ratios for a number of nuclides (Sr, Ba, Cs, Co, Y, Eu(III), Ce(III), Sb, U(VI), I, Mo, Nb, Ru) were measured between ground water and bentonite and Nevada alluvium. Results are tabulated and discussed for each individual nuclide. 5 tables

[en] This project developed from the Oklo natural fission reactor studies. It had been determined in the Oklo studies that many fission products and actinides remained in the reactor site during the periods of their radioactive decay following formation in the reactor zone two billion years ago. An explanation for this retention of fission products and actinides uses the extreme insolubility of uraninite (UO₂) in very reducing water environments. One can estimate from available thermodynamic data that the concentration of uranium in equilibrium with uraninite in pH 7 water that is free of dissolved oxygen is approx. 7 x 10^-6 ppM. This low value suggested that the reducing conditions that can occur in deep geologic burial would result in a very slow leaching of spent fuel elements in contact with water since spent fuel elements are largely sintered UO₂. Studies on the leaching of spent fuel elements were conducted to verify this phenomenon. Results of the studies show that the solubilities of some radionuclides, especially rare earths and actinides, may be an important and controlling factor in leaching of waste forms. These solubilities should be measured accurately as a function of pH and not as a part of a multicomponent system. Although the amount of data is small it is interesting to postulate that a negative temperature coefficient of solubility is being exhibited by the actinides and rare earths. Individual solubilities should be measured as a function of temperature to determine if a kinetic effect is being observed in the data. A negative temperature coefficient of solubility for actinides and rare earths in water would have important consequences for nuclear reactor safety and for the management of nuclear wastes

[en] The solubilities of some radionuclides, especially rare earths and actinides, may be an important and controlling factor in leaching of waste forms. These solubilities should be measured accurately as a function of pH and not as a part of a multicomponent system. Individual solubilities should be measured as a function of temperature to determine if a kinetic effect is being observed in the data. A negative temperature coefficient of solubility for actinides and rare earths in water would have important consequences for nuclear reactor safety and for the management of nuclear wastes

[en] As a follow up to the initial 1998 intercomparison study, a second study was initiated in 2001 as part of the ongoing evaluation of the capabilities of various ultra-sensitive methods to analyze ²³⁹Pu in urine samples. The initial study was sponsored by the Department of Energy, Office of International Health Programs to evaluate and validate new technologies that may supersede the existing fission tract analysis (FTA) method for the analysis of ²³⁹Pu in urine at the (micro)Bq/l level. The ultra-sensitive techniques evaluated in the second study included accelerator mass spectrometry (AMS) by LLNL, thermal ionization mass spectrometry (TIMS) by LANL and FTA by the University of Utah. Only the results for the mass spectrometric methods will be presented. For the second study, the testing levels were approximately 4, 9, 29 and 56 (micro)Bq of ²³⁹Pu per liter of synthetic urine. Each test sample also contained ²⁴⁰Pu at a ²⁴⁰Pu/²³⁹Pu atom ratio of ∼0.15 and natural uranium at a concentration of 50 (micro)Bq/ml. From the results of the two studies, it can be inferred that the best performance at the (micro)Bq level is more laboratory specific than method specific. The second study demonstrated that LANL-TIMS and LLNL-AMS had essentially the same quantification level for both isotopes. Study results for bias and precision and acceptable performance compared to ANSI N13.30 and ANSI N42.22 have been compiled

[en] We have used scanning Kelvin probe microscopy (SKPM) as a local probe to study charge trapping in zone-cast pentacene field effect transistors on both SiO₂ and benzocyclobutene (BCB) substrates. Annealing at 130 deg. C was found to reduce the threshold voltage, susceptibility to negative gate bias stress and trapping of positive charges within single pentacene grains. We conclude that oxygen is able to penetrate and disassociatively incorporate into crystalline pentacene, chemically creating electrically active defect states. Screening of a positive gate bias caused by electron injection from Au into pentacene was directly observed with SKPM. The rate of screening was found to change significantly after annealing of the film and depended on the choice of gate dielectric.

[en] As a follow up to the initial 1998 intercomparison study, a second study was initiated in 2001 as part of the ongoing evaluation of the capabilities of various ultra-sensitive methods to analyze ²³⁹Pu in urine samples. The initial study was sponsored by the Department of Energy, Office of International Health Programs to evaluate and validate new technologies that may supersede the existing fission tract analysis (FTA) method for the analysis of ²³⁹Pu in urine at the μBq/l level. The ultra-sensitive techniques evaluated in the second study included accelerator mass spectrometry (AMS) by LLNL, thermal ionization mass spectrometry (TIMS) by LANL and FTA by the University of Utah. Only the results for the mass spectrometric methods will be presented. For the second study, the testing levels were approximately 4, 9, 29 and 56 μBq of ²³⁹Pu per liter of synthetic urine. Each test sample also contained ²⁴⁰Pu at a ²⁴⁰Pu/²³⁹Pu atom ratio of ∼0.15 and natural uranium at a concentration of 50 μBq/ml. From the results of the two studies, it can be inferred that the best performance at the μBq level is more laboratory specific than method specific. The second study demonstrated that LANL-TIMS and LLNL-AMS had essentially the same quantification level for both isotopes. Study results for bias and precision and acceptable performance compared to ANSI N13.30 and ANSI N42.22 have been compiled. (author)