Showing papers by "Pacific Northwest National Laboratory published in 1986"
TL;DR: In this paper, the effects of self-radiation damage from alpha decay were determined as a function of cumulative dose, and the macroscopic swelling of the specimens increased exponentially with dose to limiting (saturation) values of 5.1 and 6.0% for Gd2Ti2O7 and CaZrTi 2O7, respectively.
217 citations
TL;DR: The rapid recovery of the melatonin rhythm after cessation of field exposure was determined to be less than 3 days, suggesting that the overall metabolic competence of the pineal is not permanently compromised by electric-field exposure, and that the circadian rhythm effect may be neuronally mediated.
Abstract: Rats exposed for 3 weeks to uniform 60-Hz electric fields of 39 kV/m (effective field strength) failed to show normal pineal gland circadian rhythms in serotonin N-acetyl transferase activity and melatonin concentrations. The time required for recovery of the melatonin rhythm after cessation of field exposure was determined to be less than 3 days. The rapid recovery suggests that the overall metabolic competence of the pineal is not permanently compromised by electric-field exposure, and that the circadian rhythm effect may be neuronally mediated.
137 citations
TL;DR: In this article, a review of the development of the synthetic aperture focusing technique (SAFT) for use in ultrasonic testing is presented. And the equations for processing the data using the SAFT algorithm in several modes are described.
Abstract: This paper is a review of the development of the synthetic aperture focusing technique (SAFT) for use in ultrasonic testing. The equations for processing the data using the SAFT algorithm in several modes are described. This paper also compares the results obtained using full 3D processing against line SAFT processing. It then briefly discusses ways to reduce the processing time for the SAFT algorithm.
134 citations
TL;DR: In this article, the authors measured wind and temperature profiles from towers that extended through the depth of the katabatic flow and found that the turbulent kinetic energy profiles in slope flow are dependent on the speed and direction of the ambient wind and can differ substantially from those found over flat terrain.
Abstract: Observations of nocturnal slope flow have been made at two sites with quite different topography and vegetation. In both cases, continuous measurements of wind and temperature profiles were made from towers that extended through the depth of the katabatic flow. At the simpler site, which approximates a tilted plane, three towers were located at different distances down the slope to measure the development of slope flow with downslope distance. Slope flow depth, downslope wind speed, and temperature deficit are found to change with downslope distance at rates that are consistent with the predictions of Manins and Sawford's (1979) layer-averaged model of slope flow, while measured entrainment rates are found to be comparable to those predicted by Ellison and Turner's (1959) laboratory experiments. The depth of slope flow is found to be roughly 0.05 times the vertical drop from the top of the slope, a relationship that also follows from combining Manins and Sawford's model and Ellison and Turner's laboratory data. Analysis of the wind spectra and a simple numerical model suggest that the turbulent kinetic energy profiles in slope flow are dependent on the speed and direction of the ambient wind and can differ substantially from those found over flat terrain. At the more complex of the two measurement sites, the occurrence of slope flow was found to correlate well with a dimensionless number 5 that is a function of the ridge-top wind speed and of the strength and depth of the inversion and that is an estimate of the ratio of the buoyancy deficit to the external horizontal pressure gradient.
124 citations
TL;DR: It is suggested that in subsurface materials of low carbon content, quinoline sorption is controlled by pH the nature and capacity of the exchange complex, and groundwater ion composition.
Abstract: The sorption of quinoline (pK/sub a/ = 4.94) was investigated on low-organic-carbon subsurface materials that varied in pH. Sorption isotherms were measured from 10/sup -7/ to 10/sup -4/ M quinoline and were found to be nonlinear. The resulting Freundlich constant (K/sub F/), based on total aqueous quinoline concentration, were poorly correlated with subsoil properties, including organic carbon. Higher sorption in the acidic subsoils and favorable coefficients for regression of K/sub F/, normalized to cation-exchange capacity vs. the ionization fraction (Q), point to the importance of ion exchange of the protonated compound. When the subsoil pH is adjusted, it is shown that sorption parallels the ionization fraction and retention of the organic cation far exceeds that of the neutral species. Calculations of surface speciation and thermodynamic parameters of sorption (..delta..H/sup 0/, ..delta..S/sup 0/) point to ion exchange and/or surface protonation at pH, levels exceeding pK/sub a/ by greater than 2 log units. It is suggested that in subsurface materials of low carbon content, quinoline sorption is controlled by pH the nature and capacity of the exchange complex, and groundwater ion composition. 46 references, 5 figures, 4 tables.
100 citations
TL;DR: Preliminary evidence suggests that bioassays might be a useful tool in broadly identifying classes of toxic components of contaminated soil and that chemical analysis alone may fail to correctly rate the severity of possible environmental toxicity.
Abstract: Bioassays were used in a three-phase research project to (a) assess the comparative sensitivity of test organisms to known classes of chemicals, (b) determine if the chemical components in field soil and water samples of unknown chemical composition could be inferred from laboratory studies using pure chemicals and (c) investigate kriging (a relatively new statistical “mapping” technique) and bioassays as methods to define the areal extent of chemical contamination.
The algal assay generally was most sensitive to samples of pure chemicals, soil elutriates and water from eight sites with known chemical contamination. Bioassays of nine samples of unknown chemical composition from the Rocky Mountain Arsenal site showed that a lettuce seed soil contact phytoassay was most sensitive. Preliminary evidence suggests that bioassays might be a useful tool in broadly identifying classes of toxic components of contaminated soil. Nearly pure formulations of insecticides and herbicides were less toxic than were their counterpart commercial formulations. This finding indicates that chemical analysis alone may fail to correctly rate the severity of possible environmental toxicity. Finally, we demonstrate that the lettuce seed phytoassay and kriging techniques can be used to map contamination in a portion of the Rocky Mountain Arsenal site and aid in cleanup decisions.
96 citations
01 Jan 1986
87 citations
TL;DR: It is found that the H+O3→HO+O2 reaction proceeds along a nonplanar pathway in which the H atom descends vertically to the plane containing the ozone molecule to form an HO3 intermediate which then undergoes fragmentation.
Abstract: The key features of the H+O3 potential energy surface have been determined using ab initio quantum mechanical methods. The electronic wave function used is a multiconfiguration Hartree–Fock wave function which provides a qualitatively correct description of various reactive channels. It is found that the H+O3→HO+O2 reaction proceeds along a nonplanar pathway in which the H atom descends vertically to the plane containing the ozone molecule to form an HO3 intermediate which then undergoes fragmentation. No planar transition state for a direct O‐atom abstraction could be located. The radical–radical O+HO2 reaction was found to have no energy barrier to formation of HO3 which was determined to subsequently decompose to HO+O2. The H‐atom abstraction reaction O+HO2→OH+O2 was found to have a small activation energy. The dynamical implications of these findings are discussed. The results are consistent with the observed vibrational excitation of the OH product in the H+O3 reaction. The key features of the H+O3 p...
86 citations
69 citations
58 citations
TL;DR: A set of equations and a FORTRAN program have been developed to calculate extraterrestrial solar radiation on a plane surface of arbitrary inclination and azimuth at any point on the Earth as discussed by the authors.
TL;DR: In this article, the authors examined the exchange of material by convective cloud processes between the mixed layer and the overlying free troposphere and found that mixed layer pollutants are vented above the entrainment zone of its boundary layer into the over-lying cloud layer by fields of active cumulus and that such active clouds may force cloud layer air downward into the mixed layers.
Abstract: This paper examines the exchange of material by convective cloud processes between the mixed layer and the overlying free troposphere. It describes results of a field experiment that was conducted in Lexington, Kentucky, during the period from 20 July to 24 August 1983 to study the processes associated with the vertical transport of acidic pollutants by nonprecipitating cumulus convection. An aircraft released SF6 tracer either within or above the mixed layer, and it was sampled by another aircraft at various levels within or above the mixed layer in the active cumulus convective cloud zone, as well as on the ground. The results show that mixed layer pollutants are vented above the entrainment zone of its boundary layer into the overlying cloud layer by fields of active cumulus and that such active clouds may force cloud layer air downward into the mixed layer.
TL;DR: In this article, the role of methanol, acetonitrile, and 2-propanol solvent modifiers on retention with supercritical carbon dioxide was investigated for selected solutes.
TL;DR: In this article, three crystalline ceramic materials, which occur as host phases for the long-lived actinides in many nuclear waste formulations, were doped with Cm-244, and the effects of self-radiation damage from alpha decay on microstructure and physical properties were investigated.
Abstract: Three crystalline ceramic materials, which occur as host phases for the long-lived actinides in many nuclear waste formulations, were doped with Cm-244, and the effects of self-radiation damage from alpha decay on microstructure and physical properties were investigated. The irradiation-induced micro- structure consists of individual amorphous tracks from both the alpha-recoil particles and the spontaneous fission fragments. The overlap of the tracks at higher doses leads to a completely amorphous state at a cumulative dose of 1.3–2.3 × 1025 alpha decays/m3. This radiation-induced amorphization process results in a stored energy of ∼ 128 J/g, 5–10% swelling, factor of 10–50 increase in leachability, and an increase in fracture toughness.
TL;DR: In this paper, soda lime silicate galss was leached in D 18 2 O at 25, 50, and 90°C up to 500 h and was examined using non-resonant nuclear reaction and Rutherford backscattering analysis.
Abstract: Soda lime silicate galss was leached in D 18 2 O at 25, 50, and 90°C up to 500 h and was examined using non-resonant nuclear reaction and Rutherford Backscattering analysis. Replacement of sodium by deuterium ( D / Na = 2.3 ±0.5) was consistent with earlier results, which have been cited as support for an ion-interdiffusion leaching mechanism. However, uptake of 18 O was in excess of D ( 18 O/D = 1.6±0.3 ), with 18 O penetrating to depths as great as those from which Na was extracted. Results indicate extensive hydrolysis and condensation reactions of the silicate matrix within the surface reaction layer while alkali is being extracted, an example of a “transformed” surface structure through which water has relatively easy access.
TL;DR: In this paper, half-lives and Pn values for 38 precursors among the low yield fission products are presented for 38 low-power fission devices. Pn value is based on a beta-neutron coincidence technique.
Abstract: Half-lives and Pn values are presented for 38 precursors among the low yield fission products. Pn values are based on a beta-neutron coincidence technique.
TL;DR: In this article, the reaction of Fe, Co, and Ni with polyphosphine ligand was shown to lead to the formation of (Fe(PP/sub 3/), (BF/sub 4/)/sub 2), and (Ni(I/0) couples.
Abstract: The reaction of (M(CH/sub 3/CN)/sub 6/) (BF/sub 4/)/sub 2/ (where M = Fe, Co, and Ni) with P(CH/sub 2/CH/sub 2/PPh/sub 2/)/sub 3/ (PP/sub 3/), PhP(CH/sub 2/CH/sub 2/PPh/sub 2/)/sub 2/ (PP/sub 2/), and Ph/sub 2/PCH/sub 2/CH/sub 2/PPh/sub 2/ (dppe) results in the formation of (Fe(PP/sub 3/)(CH/sub 3/CN)/sub 2/) (BF/sub 4/)/sub 2/, (Fe(PP/sub 2/)(CH/sub 3/CN)/sub 3/) (BF/sub 4/)/sub 2/, (Fe(dppe)/sub 2/(CH/sub 3/CN)/sub 2/) (BF/sub 4/)/sub 2/, (Co(PP/sub 3/)(CH/sub 3/CN)) (BF/sub 4/)/sub 2/, (Co(dppe)/sub 2/(CH/sub 3/CN)) (BF/sub 4/)/sub 2/, (Ni(PP/sub 3/)(CH/sub 3/CN)) (BF/sub 4/)/sub 2/, (Ni(PP/sub 2/)(CH/sub 3/CN))(BF/sub 4/)/sub 2/, and (Ni(dppe)/sub 2/)(BF/sub 3/)/sub 2/, respectively. Electrochemical studies have been carried out on these complexes to examine the influence of the nature of the polyphosphine ligand on the redox properties of each metal. For (Fe(PP)(CH/sub 3/CN)/sub 2/)(BF/sub 4/)/sub 2/ the reversibility of both the Fe(II/III) and Fe(I/0) couples are enhanced relative to those of (Fe(dppe)/sub 2/(CH/sub 3/CN)/sub 2/)(BF/sub 4/)/sub 2/. For (Co(PP/sub 3/)(CH/sub 3/CN))(BF/sub 4/)/sub 2/ the lowest oxidation state accessible in CH/sub 3/CN is +1, while for (Co(dppe)/sub 2/(CH/sub 3/CN))(BF/sub 4/)/sub 2/ the -1 oxidation state can be observed. The Ni(I/0) couple is reversible for (Ni(dppe)/sub 2/)(BF/sub 4/)/sub 2/ and irreversible for (Ni(PP/sub 2/)(CH/sub 3/CN))(BF/sub 4/)/sub 2/ and (Ni(PP/sub 3/)(CH/sub 3/CN))(BF/sub 4/)/submore » 2/. The electrochemical studies of the latter complex have led to the synthesis of a Ni(0) dimer, (Ni(PP/sub 3/))/sub 2/.« less
TL;DR: In this article, the effects of self-radiation damage on microstructure and fracture properties in Cm-doped Ca 2 Nd 8 (SiO 4 ) 6 O 2 were investigated.
TL;DR: In this article, the effect of density on the enthalpy of transfer and the entropy of transfer of the solute between the mobile and stationary phase was investigated for capillary supercritical fluid chromatography (SFC) using carbon dioxide as the mobile phase.
TL;DR: A microprocessor-controlled rotating shadowband photometer that is designed to require little or no maintenance, it should never need realignment, but will require occasional cleaning, and its accuracy in a broadband solar resource measurement is low.
01 Jan 1986
TL;DR: In this paper, the authors have suggested that subsequent soil solubility and uptake by plants will be important factors in governing Tc radiation dose to man, however, prediction of Tc behaviour in soils and availability to plants is complicated by its complex chemistry relative to soil processes.
Abstract: Technetium from a number of sources has the potential for entering soils in initially volatile or solubilised forms [1,2]. Several assessments [3] have suggested that subsequent soil solubility and uptake by plants will be important factors in governing Tc radiation dose to man. However, prediction of Tc behaviour in soils and availability to plants is complicated by its complex chemistry relative to soil processes.
TL;DR: In this article, the authors investigated the mechanism responsible for atomization of selenium in graphite furnaces and for stabilization that occurs when nickel is added to the mixture of dicarbide and oxides.
Abstract: Mechanisms responsible for atomization of selenium in graphite furnaces and for stabilization that occurs when nickel is added to selenium are investigated by mass analyzing, in real-time, the gaseous species from furnaces heated in vacuum and in atmospheric pressure environments. For the latter case, the analysis is done on a molecular beam formed from free-jet expansion of gases from the furnace. The apparatus for doing this is described. Results from the two experimental techniques, when compared, indicate that the primary loss of selenium at low temperatures is from thermal dissociation of selenium dicarbide. Secondary losses are due to vaporization of the dimer and the oxides. Nickel nitrate inhibits formation of the dicarbide, the dimer and the oxides. Mechanisms that are responsible for these findings are postulated.
01 Jun 1986-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the relative stability of crystalline and amorphous phases in metallic structures during ion irradiation is discussed in terms of the free energy changes and point defect mobility.
Abstract: The relative stability of crystalline and amorphous phases in metallic structures during ion irradiation is discussed in terms of the free energy changes and point defect mobility. The increase in free energy due to radiation induced defects is predicted to be larger for line compounds than compounds with wide solubility, which can explain the greater tendency toward amorphization for line compounds. Low defect mobility is also necessary to ensure a high total defect concentration. Nucleation of dislocation structure is an alternate way to relieve the high internal free energy and therefore may preclude subsequent amorphous transformation. Ion irradiation can also enhance the crystallization kinetics of the amorphous phase. A critical temperature region can be defined which separates the regions of crystalline stability from amorphous stability during irradiation.
TL;DR: In this article, the authors analyzed hourly tethered-balloon wind soundings from the Brush Creek Valley of Colorado to determine the nocturnal atmospheric mass (or volume) budget of the valley.
Abstract: Hourly tethered-balloon wind soundings from the 650-m deep, narrow, Brush Creek Valley of Colorado are analyzed to determine the nocturnal atmospheric mass (or volume) budget of the valley. Under the assumption that the volume flux on an entire valley cross section can be approximated from balloon soundings over the valley center, volume fluxes are calculated from tethered balloon profiles taken on 30–31 July 1982 at several points along the valley's longitudinal axis in a 7-km long segment of the valley. Down-valley volume fluxes increased in the 3 h following sunset to levels that were basically maintained through the night. Down-valley volume fluxes increased with distance down the valley axis from 0.9 million m3 s−1 at the upper end of the segment to 2.8 million m3 s−1 at the lower end, producing an average volume flux divergence of 271 m2 s−1. If we assume that the volume flux divergence is supported entirely by subsidence of air into the valley, a peak sinking rate of 0.10 m s−1 is obtained...
TL;DR: Sequential photon-excitation, electron-impact ionization with subsequent mass analysis has been applied to a barium atomic beam, allowing the recording of individual optical spectra for all the stable isotopes, including the 0.1% abundant (130)Ba and (132)Ba in a sample with natural isotopic abundances.
Abstract: Sequential photon-excitation, electron-impact ionization with subsequent mass analysis has been applied to a barium atomic beam. High-resolution, Doppler-free laser excitation produces the 6s6p(1)P(1) excited state, which is then ionized by electron bombardment. The excited state is selectively ionized when bombardment energies are between the excited- and ground-state ionization thresholds. Mass discrimination has permitted the recording of individual optical spectra for all the stable isotopes, including the 0.1% abundant (130)Ba and (132)Ba, in a sample with natural isotopic abundances.
TL;DR: Composition-based correlations to predict the relative sensitization resistance of AISI 304 and 316 stainless steel (SS) have been evaluated by comparison to a large data base in this article.
Abstract: Composition-based correlations to predict the relative sensitization resistance of AISI 304 and 316 stainless steel (SS) have been evaluated by comparison to a large data base. The best fi...
TL;DR: A lower limit of 1.5\ifmmode\times\else\texttimes\fi{}${10}^{25}$ yr (68% C.L.) is reported for the mean life of the electron decay via the branch ${e}^{\mathrm{\ensuremath{-}}}$ while the ultimate limit on the half-life for this decay mode which would be attainable using this technique is about 3 orders of magnitude higher.
Abstract: A lower limit of 1.5\ifmmode\times\else\texttimes\fi{}${10}^{25}$ yr (68% C.L.) is reported for the mean life of the electron decay via the branch ${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}\ensuremath{\gamma}+${\ensuremath{
u}}_{e}$. This is significantly longer than the best previously reported limit. Data were collected for 8850 h with an ultralow-background 135-${\mathrm{cm}}^{3}$ Ge detector located 1438 m underground. The electrons of primary interest are in the germanium crystal and in 102 kg of copper surrounding the detector. A projection of the ultimate limit on the half-life for this decay mode which would be attainable using this technique, under the most optimistic circumstances, is about 3 orders of magnitude higher.
01 Jun 1986-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, an examination of amorphization kinetics in intermetallic alloys indicated that both a criterion based on cascade-induced point defects and a uniform production of point defects rationalized observed amorphisation kinetics, and the dose dependencies of average defect concentrations were calculated and simulated using a Monte Carlo technique.
Abstract: An examination of amorphization kinetics in intermetallic alloys indicated that both a criterion based on cascade-induced point defects and a criterion based on a uniform production of point defects rationalized observed amorphization kinetics in ion irradiated NiTi. The dose dependencies of average defect concentrations were calculated and the fluctuations in concentration were simulated using a Monte Carlo technique. Assumed low interstitial mobilities and high sink strengths promoted amorphization. Faster interstitial mobilities caused shorter lifetimes for cascades and lesser accumulation of cascade damage. Assuming uniform production of point defects, the predicted dose exponent for amorphization increased with increasing critical defect concentration and increasing critical cluster size.
TL;DR: Ferrous/ferric equilibria were determined in an alkali-iron borosilicate glass of the type that is presently being considered for nuclear waste disposal in this article, where the theoretical redox behavior is found at conditions more reducing than 1 kPa. Deviation from this behavior at more oxidizing conditions results from mutual interactions between the iron redox couple and other multivalentions in the glass.
Abstract: Ferrous/ferric equilibria were determined in an alkali-iron borosilicate glass of the type that is presently being considered for nuclear waste disposal. Theoretical redox behavior is found at conditions more reducing than 1 kPa. Deviation from this behavior at more oxidizing conditions results from mutual interactions between the iron redox couple and other multivalentions in the glass. The results suggest that the ferrous/ferric ratio can be used as a quantitative indicator of the glass oxidation state in these complex glasses. Implications regarding redox control of the vitrification process are discussed.