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Sample records for solution simulating low-level

  1. Pore solution chemistry of simulated low-level liquid waste incorporated in cement grouts

    SciTech Connect

    Kruger, A.A.

    1995-12-01

    Expressed pore solutions from simulated low level liquid waste cement grouts cured at room temperature, 50{degree}C and 90{degree}C for various duration were analyzed by standard chemical methods and ion chromatography. The solid portions of the grouts were formulated with portland cement, fly ash, slag, and attapulgite clay in the ratios of 3:3:3:1. Two different solutions simulating off-gas condensates expected from vitrification of Hanford low level tank wastes were made. One is highly alkaline and contains the species Na{sup {plus}}, P0{sub 4}{sup 3-}, N0{sub 2}{sup -}, NO{sub 3}{sup -} and OH{sup -}. The other is carbonated and contains the species, Na{sup {plus}}, PO{sub 4}{sup 3-}, NO{sub 2}{sup -}, NO{sub 3}{sup -}, and CO{sub 3}{sup 2-}. In both cases phosphate rapidly disappeared from the pore solution, leaving behind sodium in the form of hydroxide. The carbonates were also removed from the pore solution to form calcium carbonate and possibly calcium monocarboaluminate. These reactions resulted in the increase of hydroxide ion concentration in the early period. Subsequently there was a significant reduction OH{sup -} and Na{sup {plus}} ion concentrations. In contrast high concentration of N0{sub 2}{sup -} and N0{sub 3}{sup -} were retained in the pore solution indefinitely.

  2. Early containment of high-alkaline solution simulating low-level radioactive waste stream in clay-bearing blended cement

    SciTech Connect

    Kruger, A.A.; Olson, R.A.; Tennis, P.D.

    1995-04-01

    Portland cement blended with fly ash and attapulgite clay was mixed with high-alkaline solution simulating low-level radioactive waste stream at a one-to-one weight ratio. Mixtures were adiabatically and isothermally cured at various temperatures and analyzed for phase composition, total alkalinity, pore solution chemistry, and transport properties as measured by impedance spectroscopy. Total alkalinity is characterized by two main drops. The early one corresponds to a rapid removal of phosphorous, aluminum, sodium, and to a lesser extent potassium solution. The second drop from about 10 h to 3 days is mainly associated with the removal of aluminum, silicon, and sodium. Thereafter, the total alkalinity continues descending, but at a lower rate. All pastes display a rapid flow loss that is attributed to an early precipitation of hydrated products. Hemicarbonate appears as early as one hour after mixing and is probably followed by apatite precipitation. However, the former is unstable and decomposes at a rate that is inversely related to the curing temperature. At high temperatures, zeolite appears at about 10 h after mixing. At 30 days, the stabilized crystalline composition Includes zeolite, apatite and other minor amounts of CaCO{sub 3}, quartz, and monosulfate Impedance spectra conform with the chemical and mineralogical data. The normalized conductivity of the pastes shows an early drop, which is followed by a main decrease from about 12 h to three days. At three days, the permeability of the cement-based waste as calculated by Katz-Thompson equation is over three orders of magnitude lower than that of ordinary portland cement paste. However, a further decrease in the calculated permeability is questionable. Chemical stabilization is favorable through incorporation of waste species into apatite and zeolite.

  3. Simulation of the great plains low-level jet and associated clouds by general circulation models

    SciTech Connect

    Ghan, S.J.; Bian, X.; Corsetti, L.

    1996-07-01

    The low-level jet frequently observed in the Great Plains of the United States forms preferentially at night and apparently influences the timing of the thunderstorms in the region. The authors have found that both the European Centre for Medium-Range Weather Forecasts general circulation model and the National Center for Atmospheric Research Community Climate Model simulate the low-level jet rather well, although the spatial distribution of the jet frequency simulated by the two GCM`s differ considerably. Sensitivity experiments have demonstrated that the simulated low-level jet is surprisingly robust, with similar simulations at much coarser horizontal and vertical resolutions. However, both GCM`s fail to simulate the observed relationship between clouds and the low-level jet. The pronounced nocturnal maximum in thunderstorm frequency associated with the low-level jet is not simulated well by either GCM, with only weak evidence of a nocturnal maximum in the Great Plains. 36 refs., 20 figs.

  4. Potential of Chromolaena odorata for phytoremediation of (137)Cs from solution and low level nuclear waste.

    PubMed

    Singh, Shraddha; Thorat, Vidya; Kaushik, C P; Raj, Kanwar; Eapen, Susan; D'Souza, S F

    2009-03-15

    Potential of Chromolaena odorata plants for remediation of (137)Cs from solutions and low level nuclear waste was evaluated. When plants were exposed to solutions spiked with three different levels of (137)Cs, namely 1 x 10(3) kBqL(-1), 5 x 10(3) kBqL(-1) and 10 x 10(3) kBqL(-1), 89%, 81% and 51% of (137)Cs was found to be remediated in 15 d, respectively. At the lowest Cs activity (1 x 10(3) kBqL(-1)), accumulation of Cs was found to be higher in roots compared to shoots, while at higher Cs activities (5 x 10(3) kBqL(-1) and 10 x 10(3) kBqL(-1)), Cs accumulation was more in shoots than roots. When plants were incubated in low level nuclear waste, 79% of the activity was removed by plants at the end of 15 d. The present study suggests that C. odorata could be used as a potential candidate plant for phytoremediation of (137)Cs. PMID:18599208

  5. The removal of benzene in a simulated low-level mixed waste

    SciTech Connect

    Cooper, W.J.; Nickelsen, M.G.; Lin, K.; Kurucz, C.N.; Waite, T.D.; Bibler, J.; Dougal, R.

    1994-12-31

    The treatment of mixed wastes presents numerous problems for the generator as well as for anyone interested in site remediation largely due to its classification as both a radiological and hazardous waste. The goal of this project was to develop a treatment process that could be used to destroy the hazardous organic compounds in a continuous stream of low-level mixed waste. Once the toxic organic compound(s) is destroyed, the waste would be classified only as a radiological waste and could be treated using known technology. Electron beam irradiation has proven to be an effective technology for removing hazardous organic compounds in aqueous streams. The removal results from the action of highly reactive chemical species (OH{center_dot}, e{sup {minus}}{sub aq}, H{center_dot}) generated when high energy electrons penetrate water. Since e{sup {minus}}{sub aq} and H{center_dot} are reducing radicals and OH{center_dot} is an oxidizing radical, the process is effective against a wide range of individual organic compounds as well as mixtures of compounds commonly found in low-level mixed waste. Pilot scale (100 gpm) studies, on simulated low-level mixed waste, were conducted at the Electron Beam Research Facility (EBRF) located in the Central District Wastewater Treatment Plant in Miami, Florida. The electron beam system used for these studies utilizes a 1.5 MeV, 50 mA continuous beam accelerator. This paper will present a brief overview of the technology, and selected results from the simulated low-level mixed waste experiments.

  6. Pilot-scale grout production test with a simulated low-level waste

    SciTech Connect

    Fow, C.L.; Mitchell, D.H.; Treat, R.L.; Hymas, C.R.

    1987-05-01

    Plans are underway at the Hanford Site near Richland, Washington, to convert the low-level fraction of radioactive liquid wastes to a grout form for permanent disposal. Grout is a mixture of liquid waste and grout formers, including portland cement, fly ash, and clays. In the plan, the grout slurry is pumped to subsurface concrete vaults on the Hanford Site, where the grout will solidify into large monoliths, thereby immobilizing the waste. A similar disposal concept is being planned at the Savannah River Laboratory site. The underground disposal of grout was conducted at Oak Ridge National Laboratory between 1966 and 1984. Design and construction of grout processing and disposal facilities are underway. The Transportable Grout Facility (TGF), operated by Rockwell Hanford Operations (Rockwell) for the Department of Energy (DOE), is scheduled to grout Phosphate/Sulfate N Reactor Operations Waste (PSW) in FY 1988. Phosphate/Sulfate Waste is a blend of two low-level waste streams generated at Hanford's N Reactor. Other wastes are scheduled to be grouted in subsequent years. Pacific Northwest Laboratory (PNL) is verifying that Hanford grouts can be safely and efficiently processed. To meet this objective, pilot-scale grout process equipment was installed. On July 29 and 30, 1986, PNL conducted a pilot-scale grout production test for Rockwell. During the test, 16,000 gallons of simulated nonradioactive PSW were mixed with grout formers to produce 22,000 gallons of PSW grout. The grout was pumped at a nominal rate of 15 gpm (about 25% of the nominal production rate planned for the TGF) to a lined and covered trench with a capacity of 30,000 gallons. Emplacement of grout in the trench will permit subsequent evaluation of homogeneity of grout in a large monolith. 12 refs., 34 figs., 5 tabs.

  7. Growth of Plants in Solution Culture Containing Low Levels of Chromium 1

    PubMed Central

    Huffman, E. W. D.; Allaway, W. H.

    1973-01-01

    Chromium was not required for normal growth of romaine lettuce (Lactuca sativa L. subsp. longifolia), tomato (Lycopersicon esculentum Mill.), wheat (Triticum aestivum L.), or bean (Phaseolus vulgaris L.) in solution culture containing 3.8 × 10−4 μM Cr. Plants grown on this purified nutrient solution contained an average of 22 ng Cr/g dry weight. Duckweed (Lemna sp.) grew and reproduced normally on a dilute nutrient solution containing 3.8 × 10−5 μM Cr. PMID:16658503

  8. Biochemical process of low level radioactive liquid simulation waste containing detergent

    SciTech Connect

    Kundari, Noor Anis Putra, Sugili; Mukaromah, Umi

    2015-12-29

    Research of biochemical process of low level radioactive liquid waste containing detergent has been done. Thse organic liquid wastes are generated in nuclear facilities such as from laundry. The wastes that are cotegorized as hazard and poison materials are also radioactive. It must be treated properly by detoxification of the hazard and decontamination of the radionuclides to ensure that the disposal of the waste meets the requirement of standard quality of water. This research was intended to determine decontamination factor and separation efficiensies, its kinetics law, and to produce a supernatant that ensured the environmental quality standard. The radioactive element in the waste was thorium with activity of 5.10{sup −5} Ci/m{sup 3}. The radioactive liquid waste which were generated in simulation plant contains detergents that was further processed by aerobic biochemical process using SGB 103 bacteria in a batch reactor equipped with aerators. Two different concentration of samples were processed and analyzed for 212 hours and 183 hours respectively at a room temperature. The product of this process is a liquid phase called as supernatant and solid phase material called sludge. The chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solid (SS), and its alpha activity were analyzed. The results show that the decontamination factor and the separation efficiency of the lower concentration samples are higher compared to the samples with high concentration. Regarding the decontamination factor, the result for 212 hours processing of waste with detergent concentration of 1.496 g/L was 3.496 times, whereas at the detergent concentration of 0.748 g/L was 15.305 times for 183 hours processing. In case of the separation efficiency, the results for both samples were 71.396% and 93.465% respectively. The Bacterial growth kinetics equation follow Monod’s model and the decreasing of COD and BOD were first order with the rate constant of 0

  9. Biochemical process of low level radioactive liquid simulation waste containing detergent

    NASA Astrophysics Data System (ADS)

    Kundari, Noor Anis; Putra, Sugili; Mukaromah, Umi

    2015-12-01

    Research of biochemical process of low level radioactive liquid waste containing detergent has been done. Thse organic liquid wastes are generated in nuclear facilities such as from laundry. The wastes that are cotegorized as hazard and poison materials are also radioactive. It must be treated properly by detoxification of the hazard and decontamination of the radionuclides to ensure that the disposal of the waste meets the requirement of standard quality of water. This research was intended to determine decontamination factor and separation efficiensies, its kinetics law, and to produce a supernatant that ensured the environmental quality standard. The radioactive element in the waste was thorium with activity of 5.10-5 Ci/m3. The radioactive liquid waste which were generated in simulation plant contains detergents that was further processed by aerobic biochemical process using SGB 103 bacteria in a batch reactor equipped with aerators. Two different concentration of samples were processed and analyzed for 212 hours and 183 hours respectively at a room temperature. The product of this process is a liquid phase called as supernatant and solid phase material called sludge. The chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solid (SS), and its alpha activity were analyzed. The results show that the decontamination factor and the separation efficiency of the lower concentration samples are higher compared to the samples with high concentration. Regarding the decontamination factor, the result for 212 hours processing of waste with detergent concentration of 1.496 g/L was 3.496 times, whereas at the detergent concentration of 0.748 g/L was 15.305 times for 183 hours processing. In case of the separation efficiency, the results for both samples were 71.396% and 93.465% respectively. The Bacterial growth kinetics equation follow Monod's model and the decreasing of COD and BOD were first order with the rate constant of 0.01 hour-1.

  10. Simulation of the Low-Level-Jet by general circulation models

    SciTech Connect

    Ghan, S.J.

    1996-04-01

    To what degree is the low-level jet climatology and it`s impact on clouds and precipitation being captured by current general circulation models? It is hypothesised that a need for a pramaterization exists. This paper describes this parameterization need.

  11. Characterization of simulated low-level waste grout produced in a pilot-scale test

    SciTech Connect

    Lokken, R.O.; Reimus, M.A.; Martin, P.F.C.; Geldart, S.E.

    1988-02-01

    The objectives of a pilot-scale grout test were to determine the homogeneity of the grout produced under conditions similar to those planned for the TGF, to evaluate performance of candidate grout processing equipment for the TGF, and to evaluate properties of grout that was produced during continuous operation over an extended time period and cured in a large monolith. This report addresses the first and third objectives. Tests were conducted on pilot-scale grout slurry, simulated waste solution, dry solids blend samples, and cured grout samples. Grout slurry collected at two points during the pilot-scale test and slurry produced in the laboratory were characterized by measuring rheology, drainable liquid, and penetration resistance. Cured grout samples included samples collected during the pilot-scale test and cured in the laboratory, samples produced in the laboratory, samples obtained from tubes inserted into the monolith, and samples from cored sections of the monolith. Tests conducted on the cured samples included compressive strength, density, ultrasonic pulse velocity, leachability, and microstructural characterization. 10 refs., 12 figs., 16 tabs.

  12. Removal of technetium-99 from simulated Oak Ridge National Laboratory Newly-Generated Liquid Low-Level Waste

    SciTech Connect

    Beck, D.E.; Osborne, P.E.; Bunch, D.H.; Fellows, R.L.; Sellers, G.F.; Shoemaker, J.L.; Bowser, K.T.; Bostick, D.T.

    1995-06-01

    We report laboratory investigations on treatment options for the removal of the radionuclide {sup 99}{Tc} (as the pertechnetate anion, {Tc}O{sub 4}{sup {minus}}) from simulated Oak Ridge National Laboratory Newly Generated Liquid Low-Level Waste. The waste stimulant is alkaline (pH 12-13), containing sodium carbonate ({approximately}0.10 mot/L) and sodium hydroxide ({approximately} 0.125 mol/L), plus a modest concentration of sodium nitrate ({approximately}0.06 mol/L). Several organic resin anion exchange media were tested; Dowex{trademark} 1-X-8 and Reillex{trademark} HPQ resins were notably effective (with equilibrium distribution coefficients {approximately}2,000 mL/g, as-received basis). We also tested steel wool as a reagent to chemically reduce and sorb {sup 99}Tc. At pH values above {approximately}10, the iron surface was passivated and became ineffective as a reagent for technetium; however, as the test solution pH value was adjusted to near-neutrality (e.g., pH 8-9), the steel was noted to be more effective than the organic resins tested. In dynamic flow conditions, steel wool packed in a column was noted to continuously leak {approximately}1--3% of the amount of {sup 99}{Tc} activity in the feed solution, although no additional increase in eluent activity was noted for the duration of the testing ({approximately}1200 bed volumes of {approximately}0.11 mg/L {sup 99}{Tc} flowed at a rate equivalent to {approximately}0.5 gal/min/ft{sup 2} of column cross sectional area). Although no breakthrough was noted (other than the 1--3 % continuous ``bleed`` noted previously) during the column operation ({approximately} 2 weeks), the steel in the column was deteriorated, causing plugging and erratic flow toward the end of the testing interval.

  13. Phytoremediation of 137cesium and 90strontium from solutions and low-level nuclear waste by Vetiveria zizanoides.

    PubMed

    Singh, Shraddha; Eapen, Susan; Thorat, Vidya; Kaushik, C P; Raj, Kanwar; D'Souza, S F

    2008-02-01

    Vetiver grass (Vetiveria zizanoides) L. Nash plantlets when tested for their potential to remove (90)Sr and (137)Cs (5 x 10(3) k Bq l(-1)) from solutions spiked with individual radionuclide showed that 94% of (90)Sr and 61% of (137)Cs could be removed from solutions after 168 h. When both (90)Sr and (137)Cs were supplemented together to the solution, 91% of (90)Sr and 59% of (137)Cs were removed at the end of 168 h. In case of (137)Cs, accumulation occurred more in roots than shoots, while (90)Sr accumulated more in shoots than roots. When experiments were performed to study the effect of analogous elements, K(+) ions reduced the uptake of (137)Cs, while (90)Sr accumulation was found to decrease in the presence of Ca(2+) ions. Plants of V. zizanoides could also effectively remove radioactive elements from low-level nuclear waste and the level of radioactivity was reduced below detection limit at the end of 15 days of exposure. The results of the present study indicate that V. zizanoides may be a potential candidate plant for phytoremediation of (90)Sr and (137)Cs. PMID:17257679

  14. Simulation of background from low-level tritium and radon emanation in the KATRIN spectrometers

    SciTech Connect

    Leiber, B.; Collaboration: KATRIN Collaboration

    2013-08-08

    The KArlsruhe TRItium Neutrino (KATRIN) experiment is a large-scale experiment for the model independent determination of the mass of electron anti-neutrinos with a sensitivity of 200 meV/c{sup 2}. It investigates the kinematics of electrons from tritium beta decay close to the endpoint of the energy spectrum at 18.6 keV. To achieve a good signal to background ratio at the endpoint, a low background rate below 10{sup −2} counts per second is required. The KATRIN setup thus consists of a high luminosity windowless gaseous tritium source (WGTS), a magnetic electron transport system with differential and cryogenic pumping for tritium retention, and electro-static retarding spectrometers (pre-spectrometer and main spectrometer) for energy analysis, followed by a segmented detector system for counting transmitted beta-electrons. A major source of background comes from magnetically trapped electrons in the main spectrometer (vacuum vessel: 1240 m{sup 3}, 10{sup −11} mbar) produced by nuclear decays in the magnetic flux tube of the spectrometer. Major contributions are expected from short-lived radon isotopes and tritium. Primary electrons, originating from these decays, can be trapped for hours, until having lost almost all their energy through inelastic scattering on residual gas particles. Depending on the initial energy of the primary electron, up to hundreds of low energetic secondary electrons can be produced. Leaving the spectrometer, these electrons will contribute to the background rate. This contribution describes results from simulations for the various background sources. Decays of {sup 219}Rn, emanating from the main vacuum pump, and tritium from the WGTS that reaches the spectrometers are expected to account for most of the background. As a result of the radon alpha decay, electrons are emitted through various processes, such as shake-off, internal conversion and the Auger deexcitations. The corresponding simulations were done using the KASSIOPEIA

  15. Performance Assessment of Low-Level Waste Disposal Facilities Using Coupled Unsaturated Flow and Reactive Transport Simulators

    SciTech Connect

    Bacon, Diana H.; McGrail, Pete P.; Freedman, Vicky L.; Ventura, Giancarlo; Risoluti, Piero N.; Krupka, Kenneth M.; McGrail, B. P.; Cragnolino, G. A.

    2002-01-01

    Recent advances in development of reactive chemical transport simulators have made it possible to use these tools in performance assessments (PAs) for nuclear waste disposal. Reactive transport codes were used to evaluate the impacts of design modifications on the performance of two shallow subsurface disposal systems for low-level radioactive waste. The first disposal system, located at the Hanford site in Richland, Washington, is for disposal of low-level waste glass. Glass waste blocks will be disposed in subsurface trenches, surrounded by backfill material. The effect of different waste package sizes and layering on technetium release to the vadose zone had a small impact on release rates. The second disposal system involves a hypothetical repository for low-activity waste in Italy. A model of uranium release from a grout waste form was developed using the STORM reactive transport code. Uranium is predicted to be relatively insoluble for several hundred years under the high-pH environment of the cement pore water. The effect of using different filler materials between the waste packages on uranium flux to the vadose zone proved to have a negligible impact on release rates.

  16. The impact of climate change on the global coastal low-level wind jets: EC-EARTH simulations

    NASA Astrophysics Data System (ADS)

    Semedo, Alvaro; Soares, Pedro M. M.; Lima, Daniela C. A.; Cardoso, Rita M.; Bernardino, Mariana; Miranda, Pedro M. A.

    2016-02-01

    Coastal low-level jets (CLLJ) are low tropospheric coast-parallel wind features, confined to the marine atmospheric boundary layer, which lay on the east flank of the semi-permanent sub-tropical high-pressure systems, in the mid-latitudes, along equator-ward eastern boundary currents. Coastal jets are of utmost relevance to the regional climate, through their impact on the along coast sea surface temperature, driving the upwelling of cold deep nutrient-rich waters, and by having a decisive impact on the aridity of the mid-latitude western coastal areas. Here the impact of a warmer climate in the CLLJ climate is investigated, through a 2-member ensemble of EC-Earth CMIP5 simulations of future climate, following the RCP8.5 greenhouse gases emissions scenario. Besides the projected changes of the CLLJ, towards the end of the 21st century, the future characteristics of the coastal jets are also presented. No common feature of projected changes in the seven identified CLLJ areas was identified. The Iberian Peninsula and the Oman coastal jets are the ones that presented the highest differences, compared to present climate: highest projected increases in frequency of occurrence, as well as highest projected increases in jet strength (wind speed at the jet height) and jet height. This study presents a step forward towards a larger ensemble of CLLJ projections, required to better assess robustness and uncertainty of potential future climate change.

  17. Impact of Enhanced Low-level Stratus on Simulated SSTs, Precipitation and the Circulation in the Tropical Atlantic Sector

    NASA Astrophysics Data System (ADS)

    Bader, J.; Eichhorn, A.

    2015-12-01

    Most coupled atmosphere-ocean general circulation models (AOGCMs) show a substantial warm bias in sea-surface temperatures (SSTs) in the eastern tropical Atlantic. The impact of enhanced low-level clouds on SST, precipitation and the circulation in the tropical Atlantic sector is tested. Therefore, we have conducted sensitivity experiments with the atmospheric model ECHAM6 and the coupled version of it (MPI-ESM1) in which we enhance the formation of low-level stratus at the inversion layer in the low troposphere. The impact of enhanced low-level clouds is compared to the standard version of the models. There is a direct cloud impact by reducing the incoming solar radiation at the surface. The reduced incoming solar radiation leads to a cooling of SSTs in the eastern tropical Atlantic in the coupled atmosphere-ocean model. This in turn causes not only locally rainfall reductions in oceanic precipitation but also a remote precipitation enhancement over north east Brazil. These precipitation changes are associated with changes in the equatorial wind-stress forcing. The impact of the wind stress changes on the equatorial zonal SST-gradient and the seasonal cycle is also analysed.

  18. Modeling of nuclide release from low-level radioactive paraffin waste: a comparison of simulated and real waste.

    PubMed

    Kim, Ju Youl; Kim, Chang Lak; Chung, Chang Hyun

    2002-10-01

    Nuclide leaching models based on mass transfer theory are reviewed and evaluated to analyze the leaching test results of simulated and real paraffin waste from Korean nuclear power plants (NPPs). An empirical model (EM), bulk diffusion model (BDM), coupled diffusion/dissolution model (CDDM), shrinking core model (SCM), modified SCM (MSCM), and uniform reaction model (URM) are selected for comparison. In case of simulated paraffin waste form, the experimental results are satisfactorily explained by the SCM which is based on a diffusion-controlled dissolution reaction. Leaching behavior of real paraffin waste form is well predicted by URM that considers inter-aggregated porous medium and intra-aggregated porous medium separately. If real paraffin waste forms are manufactured with relatively uniform composition, their leaching behaviors are expected to be similar to those of simulated paraffin waste forms. PMID:12169419

  19. Quantifying the intrinsic surface charge density and charge-transfer resistance of the graphene-solution interface through bias-free low-level charge measurement

    NASA Astrophysics Data System (ADS)

    Ping, Jinglei; Johnson, A. T. Charlie

    2016-07-01

    Liquid-based bio-applications of graphene require a quantitative understanding of the graphene-liquid interface, with the surface charge density of adsorbed ions, the interfacial charge transfer resistance, and the interfacial charge noise being of particular importance. We quantified these properties through measurements of the zero-bias Faradaic charge-transfer between graphene electrodes and aqueous solutions of varying ionic strength using a reproducible, low-noise, minimally perturbative charge measurement technique. The measurements indicated that the adsorbed ions had a negative surface charge density of approximately -32.8 mC m-2 and that the specific charge transfer resistance was 6.5 ± 0.3 MΩ cm2. The normalized current noise power spectral density for all ionic concentrations tested collapsed onto a 1/fα characteristic with α = 1.1 ± 0.2. All the results are in excellent agreement with predictions of the theory for the graphene-solution interface. This minimally perturbative method for monitoring charge-transfer at the sub-pC scale exhibits low noise and ultra-low power consumption (˜fW), making it suitable for use in low-level bioelectronics in liquid environments.

  20. A piloted simulation investigation of yaw dynamics requirements for turreted gun use in low-level helicopter air combat

    NASA Technical Reports Server (NTRS)

    Decker, William A.; Morris, Patrick M.; Williams, Jeffrey N.

    1988-01-01

    A piloted, fixed-base simulation study was conducted to investigate the handling qualities requirements for helicopter air-to-air combat using turreted guns in the near-terrain environment. The study used a version of the helicopter air combat system developed at NASA Ames Research Center for one-on-one air combat. The study focused on the potential trade-off between gun angular movement capability and required yaw axis response. Experimental variables included yaw axis response frequency and damping and the size of the gun-movement envelope. A helmet position and sighting system was used for pilot control of gun aim. Approximately 340 simulated air combat engagements were evaluated by pilots from the Army and industry. Results from the experiment indicate that a highly-damped, high frequency yaw response was desired for Level I handling qualities. Pilot preference for those characteristics became more pronounced as gun turret movement was restricted; however, a stable, slow-reacting platform could be used with a large turret envelope. Most pilots preferred to engage with the opponent near the own-ship centerline. Turret elevation restriction affected the engagement more than azimuth restrictions.

  1. Aerosol First Indirect Effects on Non-Precipitating Low-Level Liquid Cloud Properties as Simulated by CAM5 at ARM Sites

    SciTech Connect

    Zhao, Chuanfeng; Klein, Stephen A.; Xie, Shaocheng; Liu, Xiaohong; Boyle, James; Zhang, Yuying

    2012-04-28

    We quantitatively examine the aerosol first indirect effects (FIE) for non-precipitating low-level single-layer liquid phase clouds simulated by the Community Atmospheric Model version 5 (CAM5) running in the weather forecast mode at three DOE Atmospheric Radiation Measurement (ARM) sites. The FIE is quantified in terms of a relative change in cloud droplet effective radius for a relative change in aerosol accumulation mode number concentration under conditions of fixed liquid water content (LWC). CAM5 simulates aerosol-cloud interactions reasonably well for this specific cloud type, and the simulated FIE is consistent with the long-term observations at the examined locations. The FIE in CAM5 generally decreases with LWC at coastal ARM sites, and is larger by using cloud condensation nuclei rather than aerosol accumulation mode number concentration as the choice of aerosol amount. However, it has no significant variations with location and has no systematic strong seasonal variations at examined ARM sites.

  2. Structure of a Microbial Community in Soil after Prolonged Addition of Low Levels of Simulated Acid Rain

    PubMed Central

    Pennanen, Taina; Fritze, Hannu; Vanhala, Pekka; Kiikkilä, Oili; Neuvonen, Seppo; Bååth, Erland

    1998-01-01

    Humus samples were collected 12 growing seasons after the start of a simulated acid rain experiment situated in the subarctic environment. The acid rain was simulated with H2SO4, a combination of H2SO4 and HNO3, and HNO3 at two levels of moderate acidic loads close to the natural anthropogenic pollution levels of southern Scandinavia. The higher levels of acid applications resulted in acidification, as defined by humus chemistry. The concentrations of base cations decreased, while the concentrations of exchangeable H+, Al, and Fe increased. Humus pH decreased from 3.83 to 3.65. Basal respiration decreased with decreasing humus pH, and total microbial biomass, measured by substrate-induced respiration and total amount of phospholipid fatty acids (PLFA), decreased slightly. An altered PLFA pattern indicated a change in the microbial community structure at the higher levels of acid applications. In general, branched fatty acids, typical of gram-positive bacteria, increased in the acid plots. PLFA analysis performed on the bacterial community growing on agar plates also showed that the relative amount of PLFA specific for gram-positive bacteria increased due to the acidification. The changed bacterial community was adapted to the more acidic environment in the acid-treated plots, even though bacterial growth rates, estimated by thymidine and leucine incorporation, decreased with pH. Fungal activity (measured as acetate incorporation into ergosterol) was not affected. This result indicates that bacteria were more affected than fungi by the acidification. The capacity of the bacterial community to utilize 95 different carbon sources was variable and only showed weak correlations to pH. Differences in the toxicities of H2SO4 and HNO3 for the microbial community were not found. PMID:9603831

  3. Numerical simulations of a transverse indirect circulation and low-level jet in the exit region of an upper-level jet

    NASA Technical Reports Server (NTRS)

    Brill, K. F.; Uccellini, L. W.; Burkhart, R. P.; Warner, T. T.; Anthes, R. A.

    1985-01-01

    A numerical study was performed of a severe weather event (tornado) which occurred on May 10, 1973 in the Ohio region. The situation was modeled with a primitive equation mesoscale dynamic formulation. Account was taken of precipitation, the planetary boundary layer parameters as bulk quantities, the vertical pressure gradient, and lateral boundary conditions based on radiosonde data. Two 12-hr simulations, adiabatic and nondivergent, respectively, were analyzed for relationships between upper and lower level jets. In the adiabatic formulation, a transverse circulation with a low level jet formed at the exit region of the upper level jet. The nondivergent situation led to similar, but weaker, phenomena. Both forms suggest that indirect circulation in the exit zone of an upper level jet is strongly influenced by the initial structure of the jet.

  4. The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection-permitting simulations

    PubMed Central

    Heinold, B; Knippertz, P; Marsham, JH; Fiedler, S; Dixon, NS; Schepanski, K; Laurent, B; Tegen, I

    2013-01-01

    [1] Convective cold pools and the breakdown of nocturnal low-level jets (NLLJs) are key meteorological drivers of dust emission over summertime West Africa, the world’s largest dust source. This study is the first to quantify their relative contributions and physical interrelations using objective detection algorithms and an off-line dust emission model applied to convection-permitting simulations from the Met Office Unified Model. The study period covers 25 July to 02 September 2006. All estimates may therefore vary on an interannual basis. The main conclusions are as follows: (a) approximately 40% of the dust emissions are from NLLJs, 40% from cold pools, and 20% from unidentified processes (dry convection, land-sea and mountain circulations); (b) more than half of the cold-pool emissions are linked to a newly identified mechanism where aged cold pools form a jet above the nocturnal stable layer; (c) 50% of the dust emissions occur from 1500 to 0200 LT with a minimum around sunrise and after midday, and 60% of the morning-to-noon emissions occur under clear skies, but only 10% of the afternoon-to-nighttime emissions, suggesting large biases in satellite retrievals; (d) considering precipitation and soil moisture effects, cold-pool emissions are reduced by 15%; and (e) models with parameterized convection show substantially less cold-pool emissions but have larger NLLJ contributions. The results are much more sensitive to whether convection is parameterized or explicit than to the choice of the land-surface characterization, which generally is a large source of uncertainty. This study demonstrates the need of realistically representing moist convection and stable nighttime conditions for dust modeling. Citation: Heinold, B., P. Knippertz, J. H. Marsham, S. Fiedler, N. S. Dixon, K. Schepanski, B. Laurent, and I. Tegen (2013), The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection

  5. Vaporization Rate of Cesium from Molten Slag in a Plasma Melting Furnace for the Treatment of Simulated Low-Level Radioactive Wastes

    SciTech Connect

    Yasui, Shinji; Amakawa, Tadashi

    2003-02-15

    The vaporization phenomena of cesium (Cs) from molten slag have been investigated in a plasma melting process for simulated radioactive waste materials. A direct current transfer-type plasma with a maximum output of 50 kW was used to melt carbon steel and granular oxide mixtures (Fe{sub 2}O{sub 3}, Al{sub 2}O{sub 3}, SiO{sub 2}, CaO, and MgO) containing nonradioactive cesium nitrate, to measure Cs vaporization. These materials are the main components of low-level miscellaneous solid wastes. The vaporization rate of Cs from the molten slag during the plasma melting was observed and was compared with the vaporization rate obtained in an electric resistance furnace. The apparent vaporization rate of Cs was found to follow the first-order rate equation with respect to the molten slag's Cs content, and its rate constant values varied (3.5 to 21.0) x 10{sup -6} m/s varying with the chemical composition of the miscellaneous solid wastes. These rate constants were about one order larger than those obtained in the electric resistant furnace and also the diffusion coefficients of basic elements in the molten slag. These results suggest that the vaporization rate of Cs is controlled by the vaporization step from the free molten slag furnace to the gas phase and depends predominantly on the thermodynamic properties of the molten slag.

  6. Low-Level Detection of a Bacillus Anthracis Simulant using Love-Wave Biosensors on 36 Degree YX LiTaO3

    SciTech Connect

    BRANCH,DARREN W.; BROZIK,SUSAN M.

    2003-03-01

    Crucial to low-level detection of biowarfare agents in aqueous environments is the mass sensitivity optimization of Love-wave acoustic sensors. The present work is an experimental study of 36{sup o} YX cut LiTaO{sub 3} based Love-wave devices for detection of pathogenic spores in aqueous conditions. Given that the detection limit (DL) of Love-wave based sensors is a strong function of the overlying waveguide, two waveguide materials have been investigated, which are polyimide and polystyrene. To determine the mass sensitivity of Love-wave sensor, bovine serum albumin (BSA) protein was injected into the Love-wave test cell while recording magnitude and phase shift across each sensor. Polyimide had the lowest mass detection limit with an estimated value of 1-2 ng/cm{sup 2}, as compared to polystyrene where DL = 2.0 ng/cm{sup 2}. Suitable chemistries were used to orient antibodies on the Love-wave sensor using adsorbed protein G. The thickness of each biofilm was measured using ellipsometry from which the surface concentrations were calculated. The monoclonal antibody BD8 with a high degree of selectivity for anthrax spores was used to capture the non-pathogenic simulant B. thuringiensis B8 spores. Bacillus Subtilis spores were used as a negative control to determine whether significant non-specific binding would occur. Spore aliquots were prepared using an optical counting method, which permitted removal of background particles for consistent sample preparation. This work demonstrates that Love-wave devices can be used to detect B. anthracis simulant below reported infectious levels.

  7. The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection-permitting simulations

    NASA Astrophysics Data System (ADS)

    Heinold, B.; Knippertz, P.; Marsham, J. H.; Fiedler, S.; Dixon, N. S.; Schepanski, K.; Laurent, B.; Tegen, I.

    2013-05-01

    Convective cold pools and the breakdown of nocturnal low-level jets (NLLJs) are key meteorological drivers of dust emission over summertime West Africa, the world's largest dust source. This study is the first to quantify their relative contributions and physical interrelations using objective detection algorithms and an off-line dust emission model applied to convection-permitting simulations from the Met Office Unified Model. The study period covers 25 July to 02 September 2006. All estimates may therefore vary on an interannual basis. The main conclusions are as follows: (a) approximately 40% of the dust emissions are from NLLJs, 40% from cold pools, and 20% from unidentified processes (dry convection, land-sea and mountain circulations); (b) more than half of the cold-pool emissions are linked to a newly identified mechanism where aged cold pools form a jet above the nocturnal stable layer; (c) 50% of the dust emissions occur from 1500 to 0200 LT with a minimum around sunrise and after midday, and 60% of the morning-to-noon emissions occur under clear skies, but only 10% of the afternoon-to-nighttime emissions, suggesting large biases in satellite retrievals; (d) considering precipitation and soil moisture effects, cold-pool emissions are reduced by 15%; and (e) models with parameterized convection show substantially less cold-pool emissions but have larger NLLJ contributions. The results are much more sensitive to whether convection is parameterized or explicit than to the choice of the land-surface characterization, which generally is a large source of uncertainty. This study demonstrates the need of realistically representing moist convection and stable nighttime conditions for dust modeling.

  8. The removal of low levels of organics from aqueous solutions using Fe(II) and hydrogen peroxide formed in situ at gas diffusion electrodes

    SciTech Connect

    Harrington, T.; Pletcher, D.

    1999-08-01

    The removal of several organics (phenol, aniline, acetic acid, formaldehyde, and three azo dyes) from aqueous solutions (pH 2) containing Fe(II) and using hydrogen peroxide produced by the reduction of oxygen at a gas-diffusion electrode is demonstrated. It is shown that chemical oxygen demand of solutions containing such organics may be reduced by >90% with a current efficiency >50%, leading to acceptable energy consumptions. The approach also clearly has considerable generality. The voltammetry of the gas diffusion electrodes, fabricated by screen printing an XC72-R carbon powder/polytetrafluorene active layer on a carbon fiber paper support is also reported and discussed.

  9. Pyrene Excimer-Based Peptidyl Chemosensors for the Sensitive Detection of Low Levels of Heparin in 100% Aqueous Solutions and Serum Samples.

    PubMed

    Thirupathi, Ponnaboina; Park, Joo-Young; Neupane, Lok Nath; Kishore, Mallela Y L N; Lee, Keun-Hyeung

    2015-07-01

    Fluorescent chemosensors (1 and 2, Py-(Arg)nGlyGlyGly(Arg)nLys(Py)-NH2, n = 2 and 3) bearing two pyrene (Py) labeled heparin-binding peptides were synthesized for the sensitive ratiometric detection of heparin. The peptidyl chemosensors (1 and 2) sensitively detected nanomolar concentrations of heparin in aqueous solutions and in serum samples via a ratiometric response. In 100% aqueous solutions at pH 7.4, both chemosensors exhibited significant excimer emission at 486 nm as well as weak monomer emission in the absence of heparin. Upon the addition of heparin into the solution, excimer emission increased with a blue shift (10 nm) and monomer emission at 376 nm decreased. The chemosensors showed a similar sensitive ratiometric response to heparin independent of the concentration of the chemosensors. The peptidyl chemosensors were applied to the ratiometric detection of heparin over a wide range of pH (1.5-11.5) using the excimer/momomer emission changes. In the presence of serum, 1 and 2 displayed significant monomer emission at 376 nm with relatively weak excimer emission and the addition of heparin induced a significant increase in excimer emission at 480 nm and a concomitant decrease in monomer emission. The enhanced ratiometric response to heparin in the serum sample was due to the interactions between the peptidyl chemosensors and serum albumin in the serum sample. The detection limits of 2 for heparin were less than 1 nM in 100% aqueous solutions and serum samples. The peptidyl chemosensors bearing two heparin-binding sites are a suitable tool for the sensitive ratiometric detection of nanomolar concentrations of heparin in 100% aqueous solutions and serum samples. PMID:26068096

  10. Application of Molecular Techniques To Elucidate the Influence of Cellulosic Waste on the Bacterial Community Structure at a Simulated Low-Level-Radioactive-Waste Site▿ †

    PubMed Central

    Field, Erin K.; D'Imperio, Seth; Miller, Amber R.; VanEngelen, Michael R.; Gerlach, Robin; Lee, Brady D.; Apel, William A.; Peyton, Brent M.

    2010-01-01

    Low-level-radioactive-waste (low-level-waste) sites, including those at various U.S. Department of Energy sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a nonradioactive model low-level-waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rRNA gene clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both methods revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more operational taxonomic units, and therefore relative diversity, than the clone libraries. Diversity indices suggest that diversity is lowest in the fill and fill-waste interface (FW) layers and greater in the wood waste and waste-clay interface layers. Principal-coordinate analysis and lineage-specific analysis determined that the Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose-degrading microorganisms suggest that the FW layer is an enrichment environment for these organisms. These results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system. PMID:20305022

  11. Application of molecular techniques to elucidate the influence of cellulosic waste on the bacterial community structure at a simulated low-level-radioactive-waste site.

    PubMed

    Field, Erin K; D'Imperio, Seth; Miller, Amber R; VanEngelen, Michael R; Gerlach, Robin; Lee, Brady D; Apel, William A; Peyton, Brent M

    2010-05-01

    Low-level-radioactive-waste (low-level-waste) sites, including those at various U.S. Department of Energy sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a nonradioactive model low-level-waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rRNA gene clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both methods revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more operational taxonomic units, and therefore relative diversity, than the clone libraries. Diversity indices suggest that diversity is lowest in the fill and fill-waste interface (FW) layers and greater in the wood waste and waste-clay interface layers. Principal-coordinate analysis and lineage-specific analysis determined that the Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose-degrading microorganisms suggest that the FW layer is an enrichment environment for these organisms. These results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system. PMID:20305022

  12. Teaching the Low Level Achiever.

    ERIC Educational Resources Information Center

    Salomone, Ronald E., Ed.

    1986-01-01

    Intended for teachers of the English language arts, the articles in this issue offer suggestions and techniques for teaching the low level achiever. Titles and authors of the articles are as follows: (1) "A Point to Ponder" (Rachel Martin); (2) "Tracking: A Self-Fulfilling Prophecy of Failure for the Low Level Achiever" (James Christopher Davis);…

  13. Toward Realistic Simulation of low-Level Clouds Using a Multiscale Modeling Framework With a Third-Order Turbulence Closure in its Cloud-Resolving Model Component

    NASA Technical Reports Server (NTRS)

    Xu, Kuan-Man; Cheng, Anning

    2010-01-01

    This study presents preliminary results from a multiscale modeling framework (MMF) with an advanced third-order turbulence closure in its cloud-resolving model (CRM) component. In the original MMF, the Community Atmosphere Model (CAM3.5) is used as the host general circulation model (GCM), and the System for Atmospheric Modeling with a first-order turbulence closure is used as the CRM for representing cloud processes in each grid box of the GCM. The results of annual and seasonal means and diurnal variability are compared between the modified and original MMFs and the CAM3.5. The global distributions of low-level cloud amounts and precipitation and the amounts of low-level clouds in the subtropics and middle-level clouds in mid-latitude storm track regions in the modified MMF show substantial improvement relative to the original MMF when both are compared to observations. Some improvements can also be seen in the diurnal variability of precipitation.

  14. Application of Molecular Techniques to Elucidate the Influence of Cellulosic Waste on the Bacterial Community Structure at a Simulated Low-Level-Radioactive-Waste Site

    SciTech Connect

    Erin K. Field; Seth D'Imperio; Amber R. Miller; Michael R. VanEngelen; Robin Gerlach; Brady D. Lee; William A. Apel; Brent M. Peyton

    2010-05-01

    Low-level radioactive waste sites, including those at various U.S. Department of Energy (DOE) sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a non-radioactive model low-level waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rDNA clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both the clone library and PhyloChip results revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more unique Operational Taxonomic Units (OTUs), and therefore more relative diversity, than the clone libraries. Calculated diversity indices suggest that diversity is lowest in the Fill (F) and Fill Waste (FW) layers and greater in the Wood Waste (WW) and Waste Clay (WC) layers. Principal coordinates analysis and lineage specific analysis determined that Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose degrading microorganisms suggests the FW layer is an enrichment environment for cellulose degradation. Overall, these results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system.

  15. Arctic low-level boundary layer clouds: in-situ measurements and simulations of mono- and bimodal supercooled droplet size distributions at the cloud top layer

    NASA Astrophysics Data System (ADS)

    Klingebiel, M.; de Lozar, A.; Molleker, S.; Weigel, R.; Roth, A.; Schmidt, L.; Meyer, J.; Ehrlich, A.; Neuber, R.; Wendisch, M.; Borrmann, S.

    2014-06-01

    Aircraft borne optical in-situ size distribution measurements were performed within Arctic boundary layer clouds, with a special emphasis on the cloud top layer, during the VERtical Distribution of Ice in Arctic Clouds (VERDI) campaign. The observations were carried out within a joint research activity of seven German institutes to investigate Arctic boundary layer-, mixed-phase clouds in April and May 2012. An instrumented Basler BT-67 research aircraft operated out of Inuvik over the Mackenzie River delta and the Beaufort Sea in the Northwest Territories of Canada. Besides the cloud particle and hydrometeor size spectrometers the aircraft was equipped with instrumentation for aerosol, radiation and other parameters. Inside the cloud, droplet size distributions with monomodal shapes were observed for predominantly liquid-phase Arctic stratocumulus. With increasing altitude inside the cloud the droplet mean diameters grew from 10 μm to 20 μm. In the upper transition zone (i.e. adjacent to the cloud-free air aloft) changes from monomodal to bimodal droplet size distributions were observed. It is shown that droplets of both modes co-exist in the same (small) air volume and the bimodal shape of the measured size distributions cannot be explained as an observational artifact caused by accumulating two droplet populations from different air volumes. The formation of a second size mode can be explained by (a) entrainment and activation/condensation of fresh aerosol particles, or (b) by differential evaporation processes occurring with cloud droplets engulfed in different eddies. Activation of entrained particles seemed a viable possibility as a layer of dry Arctic enhanced background aerosol was detected directly above the stratus cloud might form a second mode of small cloud droplets. However, theoretical considerations and a model simulation revealed that, instead, turbulent mixing and evaporation of larger droplets most likely are the main reasons for the formation

  16. Arctic low-level boundary layer clouds: in situ measurements and simulations of mono- and bimodal supercooled droplet size distributions at the top layer of liquid phase clouds

    NASA Astrophysics Data System (ADS)

    Klingebiel, M.; de Lozar, A.; Molleker, S.; Weigel, R.; Roth, A.; Schmidt, L.; Meyer, J.; Ehrlich, A.; Neuber, R.; Wendisch, M.; Borrmann, S.

    2015-01-01

    Aircraft borne optical in situ size distribution measurements were performed within Arctic boundary layer clouds with a special emphasis on the cloud top layer during the VERtical Distribution of Ice in Arctic clouds (VERDI) campaign in April and May 2012. An instrumented Basler BT-67 research aircraft operated out of Inuvik over the Mackenzie River delta and the Beaufort Sea in the Northwest Territories of Canada. Besides the cloud particle and hydrometeor size spectrometers the aircraft was equipped with instrumentation for aerosol, radiation and other parameters. Inside the cloud, droplet size distributions with monomodal shapes were observed for predominantly liquid-phase Arctic stratocumulus. With increasing altitude inside the cloud the droplet mean diameters grew from 10 to 20 μm. In the upper transition zone (i.e., adjacent to the cloud-free air aloft) changes from monomodal to bimodal droplet size distributions (Mode 1 with 20 μm and Mode 2 with 10 μm diameter) were observed. It is shown that droplets of both modes co-exist in the same (small) air volume and the bimodal shape of the measured size distributions cannot be explained as an observational artifact caused by accumulating data point populations from different air volumes. The formation of the second size mode can be explained by (a) entrainment and activation/condensation of fresh aerosol particles, or (b) by differential evaporation processes occurring with cloud droplets engulfed in different eddies. Activation of entrained particles seemed a viable possibility as a layer of dry Arctic enhanced background aerosol (which was detected directly above the stratus cloud) might form a second mode of small cloud droplets. However, theoretical considerations and model calculations (adopting direct numerical simulation, DNS) revealed that, instead, turbulent mixing and evaporation of larger droplets are the most likely reasons for the formation of the second droplet size mode in the uppermost region

  17. CORROSION TESTING IN SIMULATED TANK SOLUTIONS

    SciTech Connect

    Hoffman, E.

    2010-12-09

    Three simulated waste solutions representing wastes from tanks SY-102 (high nitrate, modified to exceed guidance limits), AN-107, and AY-102 were supplied by PNNL. Out of the three solutions tested, both optical and electrochemical results show that carbon steel samples corroded much faster in SY-102 (high nitrate) than in the other two solutions with lower ratios of nitrate to nitrite. The effect of the surface preparation was not as strong as the effect of solution chemistry. In areas with pristine mill-scale surface, no corrosion occurred even in the SY-102 (high nitrate) solution, however, corrosion occurred in the areas where the mill-scale was damaged or flaked off due to machining. Localized corrosion in the form of pitting in the vapor space of tank walls is an ongoing challenge to overcome in maintaining the structural integrity of the liquid waste tanks at the Savannah River and Hanford Sites. It has been shown that the liquid waste condensate chemistry influences the amount of corrosion that occurs along the walls of the storage tanks. To minimize pitting corrosion, an effort is underway to gain an understanding of the pitting response in various simulated waste solutions. Electrochemical testing has been used as an accelerated tool in the investigation of pitting corrosion. While significant effort has been undertaken to evaluate the pitting susceptibility of carbon steel in various simulated waste solutions, additional effort is needed to evaluate the effect of liquid waste supernates from six Hanford Site tanks (AY-101, AY-102, AN-102, AN-107, SY-102 (high Cl{sup -}), and SY-102 (high nitrate)) on carbon steel. Solutions were formulated at PNNL to replicate tank conditions, and in the case of SY-102, exceed Cl{sup -} and NO{sub 3}{sup -} conditions, respectively, to provide a contrast between in and out of specification limits. The majority of previous testing has been performed on pristine polished samples. To evaluate the actual tank carbon steel

  18. Low level vapor verification of monomethyl hydrazine

    NASA Technical Reports Server (NTRS)

    Mehta, Narinder

    1990-01-01

    The vapor scrubbing system and the coulometric test procedure for the low level vapor verification of monomethyl hydrazine (MMH) are evaluated. Experimental data on precision, efficiency of the scrubbing liquid, instrument response, detection and reliable quantitation limits, stability of the vapor scrubbed solution, and interference were obtained to assess the applicability of the method for the low ppb level detection of the analyte vapor in air. The results indicated that the analyte vapor scrubbing system and the coulometric test procedure can be utilized for the quantitative detection of low ppb level vapor of MMH in air.

  19. Simulation of unsaturated flow and nonreactive solute transport in a heterogeneous soil at the field scale

    SciTech Connect

    Rockhold, M L

    1993-02-01

    A field-scale, unsaturated flow and solute transport experiment at the Las Cruces trench site in New Mexico was simulated as part of a blind'' modeling exercise to demonstrate the ability or inability of uncalibrated models to predict unsaturated flow and solute transport in spatially variable porous media. Simulations were conducted using a recently developed multiphase flow and transport simulator. Uniform and heterogeneous soil models were tested, and data from a previous experiment at the site were used with an inverse procedure to estimate water retention parameters. A spatial moment analysis was used to provide a quantitative basis for comparing the mean observed and simulated flow and transport behavior. The results of this study suggest that defensible predictions of waste migration and fate at low-level waste sites will ultimately require site-specific data for model calibration.

  20. Staggered solution procedures for multibody dynamics simulation

    NASA Technical Reports Server (NTRS)

    Park, K. C.; Chiou, J. C.; Downer, J. D.

    1990-01-01

    The numerical solution procedure for multibody dynamics (MBD) systems is termed a staggered MBD solution procedure that solves the generalized coordinates in a separate module from that for the constraint force. This requires a reformulation of the constraint conditions so that the constraint forces can also be integrated in time. A major advantage of such a partitioned solution procedure is that additional analysis capabilities such as active controller and design optimization modules can be easily interfaced without embedding them into a monolithic program. After introducing the basic equations of motion for MBD system in the second section, Section 3 briefly reviews some constraint handling techniques and introduces the staggered stabilized technique for the solution of the constraint forces as independent variables. The numerical direct time integration of the equations of motion is described in Section 4. As accurate damping treatment is important for the dynamics of space structures, we have employed the central difference method and the mid-point form of the trapezoidal rule since they engender no numerical damping. This is in contrast to the current practice in dynamic simulations of ground vehicles by employing a set of backward difference formulas. First, the equations of motion are partitioned according to the translational and the rotational coordinates. This sets the stage for an efficient treatment of the rotational motions via the singularity-free Euler parameters. The resulting partitioned equations of motion are then integrated via a two-stage explicit stabilized algorithm for updating both the translational coordinates and angular velocities. Once the angular velocities are obtained, the angular orientations are updated via the mid-point implicit formula employing the Euler parameters. When the two algorithms, namely, the two-stage explicit algorithm for the generalized coordinates and the implicit staggered procedure for the constraint Lagrange

  1. Packaged low-level waste verification system

    SciTech Connect

    Tuite, K.; Winberg, M.R.; McIsaac, C.V.

    1995-12-31

    The Department of Energy through the National Low-Level Waste Management Program and WMG Inc. have entered into a joint development effort to design, build, and demonstrate the Packaged Low-Level Waste Verification System. Currently, states and low-level radioactive waste disposal site operators have no method to independently verify the radionuclide content of packaged low-level waste that arrives at disposal sites for disposition. At this time, the disposal site relies on the low-level waste generator shipping manifests and accompanying records to ensure that low-level waste received meets the site`s waste acceptance criteria. The subject invention provides the equipment, software, and methods to enable the independent verification of low-level waste shipping records to ensure that the site`s waste acceptance criteria are being met. The objective of the prototype system is to demonstrate a mobile system capable of independently verifying the content of packaged low-level waste.

  2. Low level image segmentation: an expert system.

    PubMed

    Nazif, A M; Levine, M D

    1984-05-01

    A major problem in robotic vision is the segmentation of images of natural scenes in order to understand their content. This paper presents a new solution to the image segmentation problem that is based on the design of a rule-based expert system. General knowledge about low level properties of processes employ the rules to segment the image into uniform regions and connected lines. In addition to the knowledge rules, a set of control rules are also employed. These include metarules that embody inferences about the order in which the knowledge rules are matched. They also incorporate focus of attention rules that determine the path of processing within the image. Furthermore, an additional set of higher level rules dynamically alters the processing strategy. This paper discusses the structure and content of the knowledge and control rules for image segmentation. PMID:21869225

  3. A method to foresee the 22nd century-state of the Low-Level Caribbean Jet and the SST difference between the Eastern Pacific and Western Atlantic Tropical Oceans from 21st century RegCM4 simulations

    NASA Astrophysics Data System (ADS)

    Pavia, Edgar; Graef, Federico; Fuentes-Franco, Ramón; Villanueva, Ismael

    2015-04-01

    A regional climate model (RegCM4) has recently verified the strengthening of the Low-Level Caribbean Jet (LLCJ) as a response to the increasing sea surface temperature (SST) difference (θ) between the Eastern Tropical Pacific (ETP) and the Western Tropical Atlantic (WTA) towards the end of the 21st century. This LLCJ strengthening, in turn, has been identified as the main cause for a future significant decrease in summer precipitation over the South of Mexico and Central America (SMCA) region, as the strong LLCJ transports humidity to the Pacific Ocean away from the continent. Since this dramatic scenario is a robust signal in different studies, here we propose a method to examine the relationship between θ and the zonal wind (U) associated to the LLCJ. The scheme consists of a pair of coupled equations which yield periodic solutions (found by means of a numerical-analytical hybrid method) which suggest that the system has a tendency to return to its present state during the 22nd century. Finally our results are compared to the available 22nd century outputs from different numerical models.

  4. Durability of cement stabilized low-level wastes

    SciTech Connect

    Kkruger, A.A.

    1995-12-01

    Cementitious materials containing high proportions of slag and fly ash have been tested for suitability to immobilize simulated alkaline and carbonated off-gas waste solutions after vitrification of low- level tank wastes stored at Hanford. To assess their performance, long-term durability was assessed by measuring stability of compressive strength and weight during leaching and exposure to sulfate and carbonate solutions. The important parameter controlling the durability is pore structure, because it affects both compressive strength and susceptibility to different kinds of chemical attack. Impedance spectroscopy was utilized to assess the connectivity of the pore system at early ages. Mercury intrusion porosimetry (MIP) and SEM were utilized to assess development of porosity at later ages. Phase alterations in the matrix exposed to aging and leaching in different media were followed using XRD. Mixtures were resistant to deterioration during immersion in solutions containing high concentrations of sulfate or carbonate ions. Mixtures were also resistant to leaching. These results are consistent with microstructural observations, which showed development of a finer pore structure and reduction in diffusivity over days or months of hydration.

  5. Low-level waste program technical strategy

    SciTech Connect

    Bledsoe, K.W.

    1994-10-01

    The Low-Level Waste Technical Strategy document describes the mechanisms which the Low-Level Waste Program Office plans to implement to achieve its mission. The mission is to manage the receipt, immobilization, packaging, storage/disposal and RCRA closure (of the site) of the low-level Hanford waste (pretreated tank wastes) in an environmentally sound, safe and cost-effective manner. The primary objective of the TWRS Low-level waste Program office is to vitrify the LLW fraction of the tank waste and dispose of it onsite.

  6. Flight in low-level wind shear

    NASA Technical Reports Server (NTRS)

    Frost, W.

    1983-01-01

    Results of studies of wind shear hazard to aircraft operation are summarized. Existing wind shear profiles currently used in computer and flight simulator studies are reviewed. The governing equations of motion for an aircraft are derived incorporating the variable wind effects. Quantitative discussions of the effects of wind shear on aircraft performance are presented. These are followed by a review of mathematical solutions to both the linear and nonlinear forms of the governing equations. Solutions with and without control laws are presented. The application of detailed analysis to develop warning and detection systems based on Doppler radar measuring wind speed along the flight path is given. A number of flight path deterioration parameters are defined and evaluated. Comparison of computer-predicted flight paths with those measured in a manned flight simulator is made. Some proposed airborne and ground-based wind shear hazard warning and detection systems are reviewed. The advantages and disadvantages of both types of systems are discussed.

  7. Low-level waste forum meeting reports

    SciTech Connect

    Sternwheeler, W.D.E.

    1992-12-31

    This paper provides highlights from the 1992 winter meeting of the Low Level Radioactive Wastes Forum. Topics of discussion included: legal information; state and compact reports; freedom of information requests; and storage.

  8. Low-level waste forum meeting reports

    SciTech Connect

    1992-12-31

    This report provides highlights from the 1992 fall meeting of the Low LEvel Radioactive Waste Forum. Topics included: disposal options after 1992; interregional agreements; management alternatives; policy; and storage.

  9. Characteristics of low-level smokers.

    PubMed

    Hyland, Andrew; Rezaishiraz, Hamed; Bauer, Joseph; Giovino, Gary A; Cummings, K Michael

    2005-06-01

    Average daily cigarette consumption has decreased, and some evidence suggests that the rate of "some day" smoking has increased; however, relatively little is known about low-level smokers. The present analysis describes and compares low-level versus heavier smokers, using cross-sectional and longitudinal data. Data from the Community Intervention Trial for Smoking Cessation (COMMIT) were used in this analysis. Population-based cross-sectional tobacco use telephone surveys were performed in 22 North American communities in 1988 and 1993, and the prevalence and characteristics of low-level smoking and reasons for quitting are reported from the 1993 prevalence survey. In addition, a cohort of 6,603 smokers was identified in 1988 and interviewed again in 1993 and 2001 to assess patterns of low-level smoking over time and its association with smoking cessation. In 1988, 7.6% were low-level smokers; in 1993, 10.7% were low-level smokers. Compared with heavier smokers, low-level smokers were more likely to be female, older, not married, Black or Hispanic; to have a 4-year college degree; to have no other adult smokers in the household; and to wait longer in the day to have their first cigarette. Low-level smokers also were less likely to report trying to quit because of the expense of smoking or physician advice to quit. They were more likely to try to quit because of trying to set a good example; concern for second-hand smoke; and factors such as bad breath, smell, or the taste of smoking. Those who smoked full-priced premium brands and who worked in a completely smoke-free worksite were more likely to be low-level smokers. Compared with heavier smokers, low-level smokers had similar rates of making a future quit attempt, lower use rates of nicotine replacement therapy, and higher cessation rates. Low-level smokers may be a growing segment of the smoker population and have different characteristics, health risks, and intervention needs compared with their heavier

  10. Low-level-waste-form criteria

    SciTech Connect

    Barletta, R.E.; Davis, R.E.

    1982-01-01

    Efforts in five areas are reported: technical considerations for a high-integrity container for resin wastes; permissible radionuclide loadings for organic ion exchange resin wastes; technical factors affecting low-level waste form acceptance requirements of the proposed 10 CFR 61 and draft BTP; modeling of groundwater transport; and analysis of soils from low-level waste disposal sites (Barnwell, Hanford, and Sheffield). (DLC)

  11. Engineered sorbent barriers for low-level waste disposal.

    SciTech Connect

    Freeman, H.D.; Mitchell, S.J.; Buelt, J.L.

    1986-12-01

    The Engineered Sorbent Barriers Program at Pacific Northwest Laboratory is investigating sorbent materials to prevent the migration of soluble radio nuclides from low-level waste sites. These materials would allow water to pass, preventing the bathtub effect at humid sites. Laboratory studies identifield promising sorbent materials for three key radionuclides: for cesium, greensand; for cobalt, activated charcoal; and for strontium, synthetic zeolite or clinoptilolite. Mixtures of these sorbent materials were tested in 0.6-m-diameter columns using radioactive leachates. To simulate expected worst-case conditions, the leachate solution contained the radionuclides, competing cations, and a chelating agent and was adjusted to a pH of 5. A sorbent barrier comprised of greensand (1 wt%), activated charcoal (6 wt%), synthetic zeolite (20 wt%), and local soil (73 wt%) achieved the decontamination factors necessary to meet the regulatory performance requirements established for this study. Sorbent barriers can be applied to shallow-land burial, as backfill around the waste or engineered structures, or as backup to other liner systems. 7 refs., 14 figs., 12 tabs.

  12. Preparation of Simulated Waste Solutions for Solvent Extraction Testing

    SciTech Connect

    Peterson, R.A.

    2000-06-27

    Personnel will need to routinely prepare 0.5 to 10 L batches of salt solutions simulating Savannah River Site (SRS) soluble waste for solvent extraction testing. This report describes the compositions and preparation methods.

  13. Polymer solution phase separation: Microgravity simulation

    NASA Technical Reports Server (NTRS)

    Cerny, Lawrence C.; Sutter, James K.

    1989-01-01

    In many multicomponent systems, a transition from a single phase of uniform composition to a multiphase state with separated regions of different composition can be induced by changes in temperature and shear. The density difference between the phase and thermal and/or shear gradients within the system results in buoyancy driven convection. These differences affect kinetics of the phase separation if the system has a sufficiently low viscosity. This investigation presents more preliminary developments of a theoretical model in order to describe effects of the buoyancy driven convection in phase separation kinetics. Polymer solutions were employed as model systems because of the ease with which density differences can be systematically varied and because of the importance of phase separation in the processing and properties of polymeric materials. The results indicate that the kinetics of the phase separation can be performed viscometrically using laser light scattering as a principle means of following the process quantitatively. Isopycnic polymer solutions were used to determine the viscosity and density difference limits for polymer phase separation.

  14. Nonisothermal Analysis of Solution Kinetics by Spreadsheet Simulation

    ERIC Educational Resources Information Center

    de Levie, Robert

    2012-01-01

    A fast and generally applicable alternative solution to the problem of determining the useful shelf life of medicinal solutions is described. It illustrates the power and convenience of the combination of numerical simulation and nonlinear least squares with a practical pharmaceutical application of chemical kinetics and thermodynamics, validated…

  15. Packaged low-level waste verification system

    SciTech Connect

    Tuite, K.T.; Winberg, M.; Flores, A.Y.; Killian, E.W.; McIsaac, C.V.

    1996-08-01

    Currently, states and low-level radioactive waste (LLW) disposal site operators have no method of independently verifying the radionuclide content of packaged LLW that arrive at disposal sites for disposal. At this time, disposal sites rely on LLW generator shipping manifests and accompanying records to insure that LLW received meets the waste acceptance criteria. An independent verification system would provide a method of checking generator LLW characterization methods and help ensure that LLW disposed of at disposal facilities meets requirements. The Mobile Low-Level Waste Verification System (MLLWVS) provides the equipment, software, and methods to enable the independent verification of LLW shipping records to insure that disposal site waste acceptance criteria are being met. The MLLWVS system was developed under a cost share subcontract between WMG, Inc., and Lockheed Martin Idaho Technologies through the Department of Energy`s National Low-Level Waste Management Program at the Idaho National Engineering Laboratory (INEL).

  16. The Great Plains low-level jet (LLJ) during the atmospheric radiation measurement (ARM) intensive observation period (IOP)-4 and simulations of land use pattern effect on the LLJ

    SciTech Connect

    Wu, Y.; Raman, S.

    1996-04-01

    The Great Plains low-level jet (LLJ) is an important element of the low-level atmospheric circulation. It transports water vapor from the Gulf of Mexico, which in turn affects the development of weather over the Great Plains of the central United States. The LLJ is generally recognized as a complex response of the atmospheric boundary layer to the diurnal cycle of thermal forcing. Early studies have attributed the Great Plains LLJ to the diurnal oscillations of frictional effect, buoyancy over sloping terrain, and the blocking effects of the Rocky Mountains. Recent investigations show that the speed of the LLJ is also affected by the soil type and soil moisture. Some studies also suggest that synoptic patterns may play an important role in the development of the LLJ. Land surface heterogeneties significantly affect mesoscale circulations by generating strong contrasts in surface thermal fluxes. Thus one would expect that the land use pattern should have effects on the LLJ`s development and structure. In this study, we try to determine the relative roles of the synoptic forcing, planetary boundary layers (PBL) processes, and the land use pattern in the formation of the LLJ using the observations from the Atmospheric Radiation Measurement (ARM) Intensive Operation Period (IOP)-4 and numerical sensitivity tests.

  17. Low-level waste forum meeting reports

    SciTech Connect

    1991-12-31

    This report contains highlights from the 1991 fall meeting of the Low Level Radioactive Waste Forum. Topics included legal updates; US NRC updates; US EPA updates; mixed waste issues; financial assistance for waste disposal facilities; and a legislative and policy report.

  18. Vital parameters related low level laser radiation

    NASA Astrophysics Data System (ADS)

    Palmieri, Beniamino; Capone, Stefania

    2011-08-01

    The first work hypotesis is that biosensors on the patient detecting heart, breath rate and skin parameters, modulate laser radiation to enhance the therapeutic outcome; in the second work hypotesis: biofeedback could be effective, when integrated in the low level laser energy release.

  19. Infrared low-level wind shear work

    NASA Technical Reports Server (NTRS)

    Adamson, Pat

    1988-01-01

    Results of field experiments for the detection of clear air disturbance and low level wind shear utilizing an infrared airborne system are given in vugraph form. The hits, misses and nuisance alarms scores are given. Information is given on the infrared spatial resolution technique. The popular index of aircraft hazard (F= WX over g - VN over AS) is developed for a remote temperature sensor.

  20. Low-level waste forum meeting reports

    SciTech Connect

    1995-12-31

    This paper provides highlights from the 1995 summer meeting of the Low Level radioactive Waste Forum. Topics included: new developments in state and compacts; federal waste management; DOE plans for Greater-Than-Class C waste management; mixed wastes; commercial mixed waste management; international export of rad wastes for disposal; scintillation cocktails; license termination; pending legislation; federal radiation protection standards.

  1. Low-level waste forum meeting reports

    SciTech Connect

    1993-12-31

    This paper provides the results of the winter meeting of the Low Level Radioactive Waste Forum. Discussions were held on the following topics: new developments in states and compacts; adjudicatory hearings; information exchange on siting processes, storage surcharge rebates; disposal after 1992; interregional access agreements; and future tracking and management issues.

  2. Low-level waste forum meeting reports

    SciTech Connect

    1990-12-31

    This paper provides highlights from the October 1990 meeting of the Low Level Radioactive Waste Forum. Topics of discussion included: a special session on liability and financial assurance needs; proposal to dispose of mixed waste at federal facilities; state plans for interim storage; and hazardous materials legislation.

  3. Modeling of pilot's visual behavior for low-level flight

    NASA Astrophysics Data System (ADS)

    Schulte, Axel; Onken, Reiner

    1995-06-01

    Developers of synthetic vision systems for low-level flight simulators deal with the problem to decide which features to incorporate in order to achieve most realistic training conditions. This paper supports an approach to this problem on the basis of modeling the pilot's visual behavior. This approach is founded upon the basic requirement that the pilot's mechanisms of visual perception should be identical in simulated and real low-level flight. Flight simulator experiments with pilots were conducted for knowledge acquisition. During the experiments video material of a real low-level flight mission containing different situations was displayed to the pilot who was acting under a realistic mission assignment in a laboratory environment. Pilot's eye movements could be measured during the replay. The visual mechanisms were divided into rule based strategies for visual navigation, based on the preflight planning process, as opposed to skill based processes. The paper results in a model of the pilot's planning strategy of a visual fixing routine as part of the navigation task. The model is a knowledge based system based upon the fuzzy evaluation of terrain features in order to determine the landmarks used by pilots. It can be shown that a computer implementation of the model selects those features, which were preferred by trained pilots, too.

  4. Simulation of osmotic pressure in concentrated aqueous salt solutions.

    SciTech Connect

    Luo, Y.; Roux, B.; Univ. of Chicago

    2010-01-01

    Accurate force fields are critical for meaningful simulation studies of highly concentrated electrolytes. The ion models that are widely used in biomolecular simulations do not necessarily reproduce the correct behavior at finite concentrations. In principle, the osmotic pressure is a key thermodynamic property that could be used to test and refine force field parameters for concentrated solutions. Here we describe a novel, simple, and practical method to compute the osmotic pressure directly from molecular dynamics (MD) simulation of concentrated aqueous solutions by introducing an idealized semipermeable membrane. Simple models for Na+, K+, and Cl- are tested and calibrated to accurately reproduce the experimental osmotic pressure at high salt concentration, up to the solubility limit of 4-5 M. The methodology is general and can be extended to any type of solute as well as nonadditive polarizable force fields.

  5. Simulation models for conservative and nonconservative solute transport in streams

    USGS Publications Warehouse

    Runkel, R.L.

    1995-01-01

    Solute transport in streams is governed by a suite of hydrologic and chemical processes. Interactions between hydrologic processes and chemical reactions may be quantified through a combination of field-scale experimentation and simulation modeling. Two mathematical models that simulate conservative and nonconservative solute transport in streams are presented. A model for conservative solutes that considers One Dimensional Transport with Inflow and Storage (OTIS) may be used in conjunction with tracer-dilution methods to quantify hydrologic transport processes (advection, dispersion, lateral inflow and transient storage). For nonconservative solutes, a model known as OTEQ may be used to quantify chemical processes within the context of hydrologic transport. OTEQ combines the transport mechanisms in OTIS with a chemical equilibrium sub-model that considers complexation, precipitation/dissolution and sorption. OTEQ has been used to quantify processes affecting trace metals in two streams in the Rocky Mountains of Colorado, USA.

  6. Computer Simulation of Grain Growth Kinetics with Solute Drag

    SciTech Connect

    Chen, L.; Chen, S.P.; Fan, D.

    1998-12-23

    The effects of solute dragon grain growth kinetics were studied in two dimensional (2-D) computer simulations by using a diffuse-interface field model. It is shown that, in the low velocity / low driving force regime, the velocity of a grain boundary motion departs from a linear relation with driving force (curvature) with solute drag. The nonlinear relation of migration velocity and driving force comes from the dependence of grain boundary energy and width on the curvature. The growth exponent m of power growth law for a polycrystalline system is affected by the segregation of solutes to grain boundaries. With the solute drag, the growth exponent m can take any value between 2 and 3 depending on the ratio of lattice diffusion to grain boundary mobility. The grain size and topological distributions are unaffected by solute drag, which are the same as those in a pure system.

  7. Melittin Aggregation in Aqueous Solutions: Insight from Molecular Dynamics Simulations.

    PubMed

    Liao, Chenyi; Esai Selvan, Myvizhi; Zhao, Jun; Slimovitch, Jonathan L; Schneebeli, Severin T; Shelley, Mee; Shelley, John C; Li, Jianing

    2015-08-20

    Melittin is a natural peptide that aggregates in aqueous solutions with paradigmatic monomer-to-tetramer and coil-to-helix transitions. Since little is known about the molecular mechanisms of melittin aggregation in solution, we simulated its self-aggregation process under various conditions. After confirming the stability of a melittin tetramer in solution, we observed—for the first time in atomistic detail—that four separated melittin monomers aggregate into a tetramer. Our simulated dependence of melittin aggregation on peptide concentration, temperature, and ionic strength is in good agreement with prior experiments. We propose that melittin mainly self-aggregates via a mechanism involving the sequential addition of monomers, which is supported by both qualitative and quantitative evidence obtained from unbiased and metadynamics simulations. Moreover, by combining computer simulations and a theory of the electrical double layer, we provide evidence to suggest why melittin aggregation in solution likely stops at the tetramer, rather than forming higher-order oligomers. Overall, our study not only explains prior experimental results at the molecular level but also provides quantitative mechanistic information that may guide the engineering of melittin for higher efficacy and safety. PMID:26208115

  8. Diffusion of Particle in Hyaluronan Solution, a Brownian Dynamics Simulation

    NASA Astrophysics Data System (ADS)

    Takasu, Masako; Tomita, Jungo

    2004-04-01

    Diffusion of a particle in hyaluronan solution is investigated using Brownian dynamics simulation. The slowing down of diffusion is observed, in accordance with the experimental results. The temperature dependence of the diffusion is calculated, and a turnover is obtained when the temperature is increased.

  9. A flow simulation study of protein solution under magnetic forces

    NASA Astrophysics Data System (ADS)

    Okada, Hidehiko; Hirota, Noriyuki; Matsumoto, Shinji; Wada, Hitoshi

    2013-02-01

    We have developed a superconducting magnet system generating magnetic forces able to compensate gravity and suppress convection of diamagnetic protein solution from which protein crystals precipitate. A simulation model has been proposed to elucidate the motion of protein solutions and search for the optimal conditions of the crystal formation process. This model incorporates general, non-uniform magnetic forces as external forces, while the previous models involve only simple, uniform magnetic forces. The simulation results indicate that the vertical component can suppress the convection of protein solution, while the horizontal component induces minimal convection. We, therefore, need to take into account the both components when considering the formation of protein crystals under magnetic forces.

  10. Lid design for low level waste container

    DOEpatents

    Holbrook, Richard H.; Keener, Wendell E.

    1995-01-01

    A container for low level waste includes a shell and a lid. The lid has a frame to which a planar member is welded. The lid frame includes a rectangular outer portion made of square metal tubing, a longitudinal beam extending between axial ends of the rectangular outer portion, and a transverse beam extending between opposite lateral sides of the rectangular outer portion. Two pairs of diagonal braces extend between the longitudinal beam and the four corners of the rectangular outer portion of the frame.

  11. Liquid low level waste management expert system

    SciTech Connect

    Ferrada, J.J.; Abraham, T.J. ); Jackson, J.R. )

    1991-01-01

    An expert system has been developed as part of a new initiative for the Oak Ridge National Laboratory (ORNL) systems analysis program. This expert system will aid in prioritizing radioactive waste streams for treatment and disposal by evaluating the severity and treatability of the problem, as well as the final waste form. The objectives of the expert system development included: (1) collecting information on process treatment technologies for liquid low-level waste (LLLW) that can be incorporated in the knowledge base of the expert system, and (2) producing a prototype that suggests processes and disposal technologies for the ORNL LLLW system. 4 refs., 9 figs.

  12. Lid design for low level waste container

    DOEpatents

    Holbrook, R.H.; Keener, W.E.

    1995-02-28

    A container for low level waste includes a shell and a lid. The lid has a frame to which a planar member is welded. The lid frame includes a rectangular outer portion made of square metal tubing, a longitudinal beam extending between axial ends of the rectangular outer portion, and a transverse beam extending between opposite lateral sides of the rectangular outer portion. Two pairs of diagonal braces extend between the longitudinal beam and the four corners of the rectangular outer portion of the frame. 6 figs.

  13. Low-level structural recognition of documents

    SciTech Connect

    Chenevoy, Y.; Belaied, A.

    1994-12-31

    This paper focuses on the qualitative approach of the low-level structured document analysis. The system identifies the different logical fields within the document and produces as output a structured flow with confidence scores. The strategy is driven by a generic model and by an OCR flow. Logical labels are attached to research areas after hypothesizing and testing typographical, lexical and contextual properties. A qualitative recognition is performed, which allows to amphasize ambiguities and unrecognized fields. Library references are treated to illustrate this method.

  14. Russian low-level waste disposal program

    SciTech Connect

    Lehman, L.

    1993-03-01

    The strategy for disposal of low-level radioactive waste in Russia differs from that employed in the US. In Russia, there are separate authorities and facilities for wastes generated by nuclear power plants, defense wastes, and hospital/small generator/research wastes. The reactor wastes and the defense wastes are generally processed onsite and disposed of either onsite, or nearby. Treating these waste streams utilizes such volume reduction techniques as compaction and incineration. The Russians also employ methods such as bitumenization, cementation, and vitrification for waste treatment before burial. Shallow land trench burial is the most commonly used technique. Hospital and research waste is centrally regulated by the Moscow Council of Deputies. Plans are made in cooperation with the Ministry of Atomic Energy. Currently the former Soviet Union has a network of low-level disposal sites located near large cities. Fifteen disposal sites are located in the Federal Republic of Russia, six are in the Ukraine, and one is located in each of the remaining 13 republics. Like the US, each republic is in charge of management of the facilities within their borders. The sites are all similarly designed, being modeled after the RADON site near Moscow.

  15. Low level tank waste disposal study

    SciTech Connect

    Mullally, J.A.

    1994-09-29

    Westinghouse Hanford Company (WHC) contracted a team consisting of Los Alamos Technical Associates (LATA), British Nuclear Fuel Laboratories (BNFL), Southwest Research Institute (SwRI), and TRW through the Tank Waste Remediation System (TWRS) Technical Support Contract to conduct a study on several areas concerning vitrification and disposal of low-level-waste (LLW). The purpose of the study was to investigate how several parameters could be specified to achieve full compliance with regulations. The most restrictive regulation governing this disposal activity is the National Primary Drinking Water Act which sets the limits of exposure to 4 mrem per year for a person drinking two liters of ground water daily. To fully comply, this constraint would be met independently of the passage of time. In addition, another key factor in the investigation was the capability to retrieve the disposed waste during the first 50 years as specified in Department of Energy (DOE) Order 5820.2A. The objective of the project was to develop a strategy for effective long-term disposal of the low-level waste at the Hanford site.

  16. BLT-MS (Breach, Leach, and Transport -- Multiple Species) data input guide. A computer model for simulating release of contaminants from a subsurface low-level waste disposal facility

    SciTech Connect

    Sullivan, T.M.; Kinsey, R.R.; Aronson, A.; Divadeenam, M.; MacKinnon, R.J. |

    1996-11-01

    The BLT-MS computer code has been developed, implemented, and tested. BLT-MS is a two-dimensional finite element computer code capable of simulating the time evolution of concentration resulting from the time-dependent release and transport of aqueous phase species in a subsurface soil system. BLT-MS contains models to simulate the processes (water flow, container degradation, waste form performance, transport, and radioactive production and decay) most relevant to estimating the release and transport of contaminants from a subsurface disposal system. Water flow is simulated through tabular input or auxiliary files. Container degradation considers localized failure due to pitting corrosion and general failure due to uniform surface degradation processes. Waste form performance considers release to be limited by one of four mechanisms: rinse with partitioning, diffusion, uniform surface degradation, or solubility. Radioactive production and decay in the waste form are simulated. Transport considers the processes of advection, dispersion, diffusion, radioactive production and decay, reversible linear sorption, and sources (waste forms releases). To improve the usefulness of BLT-MS a preprocessor, BLTMSIN, which assists in the creation of input files, and a post-processor, BLTPLOT, which provides a visual display of the data have been developed. This document reviews the models implemented in BLT-MS and serves as a guide to creating input files for BLT-MS.

  17. Enhancing physiologic simulations using supervised learning on coarse mesh solutions.

    PubMed

    Kolandaivelu, Kumaran; O'Brien, Caroline C; Shazly, Tarek; Edelman, Elazer R; Kolachalama, Vijaya B

    2015-03-01

    Computational modelling of physical and biochemical processes has emerged as a means of evaluating medical devices, offering new insights that explain current performance, inform future designs and even enable personalized use. Yet resource limitations force one to compromise with reduced order computational models and idealized assumptions that yield either qualitative descriptions or approximate, quantitative solutions to problems of interest. Considering endovascular drug delivery as an exemplary scenario, we used a supervised machine learning framework to process data generated from low fidelity coarse meshes and predict high fidelity solutions on refined mesh configurations. We considered two models simulating drug delivery to the arterial wall: (i) two-dimensional drug-coated balloons and (ii) three-dimensional drug-eluting stents. Simulations were performed on computational mesh configurations of increasing density. Supervised learners based on Gaussian process modelling were constructed from combinations of coarse mesh setting solutions of drug concentrations and nearest neighbourhood distance information as inputs, and higher fidelity mesh solutions as outputs. These learners were then used as computationally inexpensive surrogates to extend predictions using low fidelity information to higher levels of mesh refinement. The cross-validated, supervised learner-based predictions improved fidelity as compared with computational simulations performed at coarse level meshes--a result consistent across all outputs and computational models considered. Supervised learning on coarse mesh solutions can augment traditional physics-based modelling of complex physiologic phenomena. By obtaining efficient solutions at a fraction of the computational cost, this framework has the potential to transform how modelling approaches can be applied in the evaluation of medical technologies and their real-time administration in an increasingly personalized fashion. PMID:25652458

  18. Enhancing physiologic simulations using supervised learning on coarse mesh solutions

    PubMed Central

    Kolandaivelu, Kumaran; O'Brien, Caroline C.; Shazly, Tarek; Edelman, Elazer R.; Kolachalama, Vijaya B.

    2015-01-01

    Computational modelling of physical and biochemical processes has emerged as a means of evaluating medical devices, offering new insights that explain current performance, inform future designs and even enable personalized use. Yet resource limitations force one to compromise with reduced order computational models and idealized assumptions that yield either qualitative descriptions or approximate, quantitative solutions to problems of interest. Considering endovascular drug delivery as an exemplary scenario, we used a supervised machine learning framework to process data generated from low fidelity coarse meshes and predict high fidelity solutions on refined mesh configurations. We considered two models simulating drug delivery to the arterial wall: (i) two-dimensional drug-coated balloons and (ii) three-dimensional drug-eluting stents. Simulations were performed on computational mesh configurations of increasing density. Supervised learners based on Gaussian process modelling were constructed from combinations of coarse mesh setting solutions of drug concentrations and nearest neighbourhood distance information as inputs, and higher fidelity mesh solutions as outputs. These learners were then used as computationally inexpensive surrogates to extend predictions using low fidelity information to higher levels of mesh refinement. The cross-validated, supervised learner-based predictions improved fidelity as compared with computational simulations performed at coarse level meshes—a result consistent across all outputs and computational models considered. Supervised learning on coarse mesh solutions can augment traditional physics-based modelling of complex physiologic phenomena. By obtaining efficient solutions at a fraction of the computational cost, this framework has the potential to transform how modelling approaches can be applied in the evaluation of medical technologies and their real-time administration in an increasingly personalized fashion. PMID:25652458

  19. Efficient field-theoretic simulation of polymer solutions

    NASA Astrophysics Data System (ADS)

    Villet, Michael C.; Fredrickson, Glenn H.

    2014-12-01

    We present several developments that facilitate the efficient field-theoretic simulation of polymers by complex Langevin sampling. A regularization scheme using finite Gaussian excluded volume interactions is used to derive a polymer solution model that appears free of ultraviolet divergences and hence is well-suited for lattice-discretized field theoretic simulation. We show that such models can exhibit ultraviolet sensitivity, a numerical pathology that dramatically increases sampling error in the continuum lattice limit, and further show that this pathology can be eliminated by appropriate model reformulation by variable transformation. We present an exponential time differencing algorithm for integrating complex Langevin equations for field theoretic simulation, and show that the algorithm exhibits excellent accuracy and stability properties for our regularized polymer model. These developments collectively enable substantially more efficient field-theoretic simulation of polymers, and illustrate the importance of simultaneously addressing analytical and numerical pathologies when implementing such computations.

  20. Efficient field-theoretic simulation of polymer solutions

    SciTech Connect

    Villet, Michael C.; Fredrickson, Glenn H.

    2014-12-14

    We present several developments that facilitate the efficient field-theoretic simulation of polymers by complex Langevin sampling. A regularization scheme using finite Gaussian excluded volume interactions is used to derive a polymer solution model that appears free of ultraviolet divergences and hence is well-suited for lattice-discretized field theoretic simulation. We show that such models can exhibit ultraviolet sensitivity, a numerical pathology that dramatically increases sampling error in the continuum lattice limit, and further show that this pathology can be eliminated by appropriate model reformulation by variable transformation. We present an exponential time differencing algorithm for integrating complex Langevin equations for field theoretic simulation, and show that the algorithm exhibits excellent accuracy and stability properties for our regularized polymer model. These developments collectively enable substantially more efficient field-theoretic simulation of polymers, and illustrate the importance of simultaneously addressing analytical and numerical pathologies when implementing such computations.

  1. Airborne infrared low level wind shear predictor

    NASA Technical Reports Server (NTRS)

    Kuhn, P. M.; Kurkowski, R. L.

    1984-01-01

    The operating principles and test performance of an airborne IR (13-16 micron) temperature-sensing detection and warning system for low-level wind shear (LLWS) are presented. The physics of LLWS phenomena and of the IR radiometer are introduced. The cold density-current outflow or gust front related to LLWS is observed in the IR spectrum of CO2 by a radiometer with + or - 0.5-C accuracy at 0.5-Hz sampling rate; LLWS alerts are given on the basis of specific criteria. Test results from the JAWS experiments conducted at Denver in July 1982, are presented graphically and discussed. The feasibility of the passive IR system is demonstrated, with an average warning time of 51 sec, corresponding to a distance from touchdown of about 2 miles.

  2. R&D ERL: Low level RF

    SciTech Connect

    Smith, K.

    2010-01-15

    A superconducting RF (SRF) Energy Recovery Linac (ERL) is currently under development at the Collider-Accelerator Department (C-AD) at Brookhaven National Laboratory (BNL). The major components from an RF perspective are (a) a 5-cell SRF ERL cavity, (b) an SRF photocathode electron gun, and (c) a drive laser for the photocathode gun. Each of these RF subsystems has its own set of RF performance requirements, as well as common requirements for ensuring correct synchronism between them. A low level RF (LLRF) control system is currently under development, which seeks to leverage both technology and experience gained from the recently commissioned RHIC LLRF system upgrade. This note will review the LLRF system requirements and describe the system to be installed at the ERL.

  3. Measurements for low level RF control systems

    NASA Astrophysics Data System (ADS)

    Simrock, S. N.

    2007-08-01

    The low level RF control system for the European x-ray free electron laser, which is based on TESLA technology, requires information on a large number of signals and parameters which are either directly measurable as physical signals or must be derived from the physical signals. In most cases, calibrations are required to obtain the desired quantities. The measured signals are used in the real time feedback loops for field and resonance control, and for diagnostic purposes to support automation and exception handling. Good system models and powerful signal processors (including field programmable gate arrays and digital signal processors) combined with fast communication links allow for processing a large number of complex algorithms in real time. Several of these algorithms have been implemented at the free electron laser at Hamburg (FLASH) for evaluation and have increased the availability of the facility for user operation.

  4. Detecting low levels of radionuclides in fluids

    DOEpatents

    Patch, Keith D.; Morgan, Dean T.

    2000-01-01

    An apparatus and method for detecting low levels of one or more radionuclides in a fluid sample uses a substrate that includes an ion exchange resin or other sorbent material to collect the radionuclides. A collecting apparatus includes a collecting chamber that exposes the substrate to a measured amount of the fluid sample such that radionuclides in the fluid sample are collected by the ion exchange resin. A drying apparatus, which can include a drying chamber, then dries the substrate. A measuring apparatus measures emissions from radionuclides collected on the substrate. The substrate is positioned in a measuring chamber proximate to a detector, which provides a signal in response to emissions from the radionuclides. Other analysis methods can be used to detect non-radioactive analytes, which can be collected with other types of sorbent materials.

  5. Statistical analysis of low level atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Tieleman, H. W.; Chen, W. W. L.

    1974-01-01

    The statistical properties of low-level wind-turbulence data were obtained with the model 1080 total vector anemometer and the model 1296 dual split-film anemometer, both manufactured by Thermo Systems Incorporated. The data obtained from the above fast-response probes were compared with the results obtained from a pair of Gill propeller anemometers. The digitized time series representing the three velocity components and the temperature were each divided into a number of blocks, the length of which depended on the lowest frequency of interest and also on the storage capacity of the available computer. A moving-average and differencing high-pass filter was used to remove the trend and the low frequency components in the time series. The calculated results for each of the anemometers used are represented in graphical or tabulated form.

  6. Mechanisms of low level light therapy

    NASA Astrophysics Data System (ADS)

    Hamblin, Michael R.; Demidova, Tatiana N.

    2006-02-01

    The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers. Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. This likely is due to two main reasons; firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. In particular a biphasic dose response has been frequently observed where low levels of light have a much better effect than higher levels. This introductory review will cover some of the proposed cellular chromophores responsible for the effect of visible light on mammalian cells, including cytochrome c oxidase (with absorption peaks in the near infrared) and photoactive porphyrins. Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species and induction of transcription factors. These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation. The results of these biochemical and cellular changes in animals and patients include such benefits as increased healing in chronic wounds, improvements in sports injuries and

  7. Transport code for radiocolloid migration: with an assessment of an actual low-level waste site

    SciTech Connect

    Travis, B.J.; Nuttall, H.E.

    1984-12-31

    Recently, there is increased concern that radiocolloids may act as a rapid transport mechanism for the release of radionuclides from high-level waste repositories. The role of colloids is, however, controversial because the necessary data and assessment methodology have been limited. Evidence is accumulating to indicate that colloids are an important consideration in the geological disposal of nuclear waste. To quantitatively assess the role of colloids, the TRACR3D transport code has been enhanced by the addition of the population balance equations. This new version of the code can simulate the migration of colloids through combinations of porous/fractured, unsaturated, geologic media. The code was tested against the experimental laboratory column data of Avogadro et al. in order to compare the code results to both experimental data and an analytical solution. Next, a low-level radioactive waste site was investigated to explore whether colloid migration could account for the unusually rapid and long transport of plutonium and americium observed at a low-level waste site. Both plutonium and americium migrated 30 meters through unsaturated volcanic tuff. The nature and modeling of radiocolloids are discussed along with site simulation results from the TRACR3D code. 20 references.

  8. Disposal of low-level and low-level mixed waste: audit report

    SciTech Connect

    1998-09-03

    The Department of Energy (Department) is faced with the legacy of thousands of contaminated areas and buildings and large volumes of `backlog` waste requiring disposal. Waste management and environmental restoration activities have become central to the Department`s mission. One of the Department`s priorities is to clean up former nuclear weapons sites and find more effective and timely methods for disposing of nuclear waste. This audit focused on determining if the Department was disposing of low-level and low-level mixed waste in the most cost-effective manner.

  9. Advanced biologically plausible algorithms for low-level image processing

    NASA Astrophysics Data System (ADS)

    Gusakova, Valentina I.; Podladchikova, Lubov N.; Shaposhnikov, Dmitry G.; Markin, Sergey N.; Golovan, Alexander V.; Lee, Seong-Whan

    1999-08-01

    At present, in computer vision, the approach based on modeling the biological vision mechanisms is extensively developed. However, up to now, real world image processing has no effective solution in frameworks of both biologically inspired and conventional approaches. Evidently, new algorithms and system architectures based on advanced biological motivation should be developed for solution of computational problems related to this visual task. Basic problems that should be solved for creation of effective artificial visual system to process real world imags are a search for new algorithms of low-level image processing that, in a great extent, determine system performance. In the present paper, the result of psychophysical experiments and several advanced biologically motivated algorithms for low-level processing are presented. These algorithms are based on local space-variant filter, context encoding visual information presented in the center of input window, and automatic detection of perceptually important image fragments. The core of latter algorithm are using local feature conjunctions such as noncolinear oriented segment and composite feature map formation. Developed algorithms were integrated into foveal active vision model, the MARR. It is supposed that proposed algorithms may significantly improve model performance while real world image processing during memorizing, search, and recognition.

  10. Experimental incineration of low level radioactive samples.

    PubMed

    Yumoto, Y; Hanafusa, T; Nagamatsu, T; Okada, S

    2000-08-01

    To determine the volume reduction potential for incineration of radioactivity in low-level radioactive waste, an incineration experiment was performed at the Okayama University Radioisotope Center (OURIC). Solid low-level radioactive samples (LLRS) were prepared for 15 routinely used radionuclides (45Ca, 1251, 32p, 33p, 35S, 59Fe, 123I, 131I, 67Ga, 99mTc, 111In, 3H, 14C, 51Cr, and 201Tl). For each radionuclide, incinerated one at a time, the smoke duct radioisotope concentration was less than 1/10 of the regulatory concentration limit (The Japanese law concerning prevention of radiation hazard due to radioisotopes, etc.). The radionuclide-containing combustible and semi-combustible LLRS were incinerated at the AP-1 50R furnace erected at OURIC, and the distribution of radioactivity inside and outside the furnace was measured. In the experimental incineration of LLRS containing these 15 radionuclides, the fractions released (RF) in the gas phase of the final smoke duct ranged from 0.165 to 0.99. The radioactivities remaining in the incineration residue were 99mTc, 87%; 59Fe, 83.1%; 45Ca, 75%; 51Cr, 62.1%; 33P, 62.0%; 32P, 61.1%; 67Ga, 57.7%; 35S, 26.0%; 111In, 21.1%; 201Tl, 16.6%; 123I, 11.9%; 131I, 8.2%; 125I, 2.4%; 14C, 0.39%; 3H, 0.04%. In the incineration of LLR S containing 35S, the rate of adhesion to the furnace wall was lower at high-temperature (809 degrees C) incineration than at low-temperature (376 degrees C) incineration. For LLRS containing one of the three radioiodines, 123I, 125I, or 131I, no such difference was observed between low (372 degrees C) and high (827 degrees C) temperature incineration (RF varied from 0.82 to 0.94). PMID:10910400

  11. Density of simulated americium/curium melter feed solution

    SciTech Connect

    Rudisill, T.S.

    1997-09-22

    Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to Oak Ridge National Laboratory and use in heavy isotope production programs. Prior to vitrification, a series of in-tank oxalate precipitation and nitric/oxalic acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Following nitric acid dissolution and oxalate destruction, the solution will be denitrated and evaporated to a dissolved solids concentration of approximately 100 g/l (on an oxide basis). During the Am/Cm vitrification, an airlift will be used to supply the concentrated feed solution to a constant head tank which drains through a filter and an in-line orifice to the melter. Since the delivery system is sensitive to the physical properties of the feed, a simulated solution was prepared and used to measure the density as a function of temperature between 20 to 70{degrees} C. The measured density decreased linearly at a rate of 0.0007 g/cm3/{degree} C from an average value of 1.2326 g/cm{sup 3} at 20{degrees} C to an average value of 1.1973g/cm{sup 3} at 70{degrees} C.

  12. MESERAN Calibration for Low Level Organic Residues

    SciTech Connect

    Benkovich, M.G.

    2004-04-08

    Precision cleaning studies done at Honeywell Federal Manufacturing & Technologies (FM&T), the Kansas City Plant (KCP), and at other locations within the Department of Energy (DOE) Weapons complex over the last 30 years have depended upon results from MESERAN Evaporative Rate Analysis for detecting low levels of organic contamination. The characterization of the surface being analyzed is carried out by depositing a Carbon-14 tagged radiochemical onto the test surface and monitoring the rate at which the radiochemical disappears from the surface with a Geiger-Mueller counter. In the past, the total number of counts over a 2-minute span have been used to judge whether a surface is contaminated or not and semi-quantitatively to what extent. This technique is very sensitive but has not enjoyed the broad acceptance of a purely quantitative analysis. The work on this project developed calibrations of various organic contaminants typically encountered in KCP operations. In addition, a new analysis method was developed to enhance the ability of MESERAN Analyzers to detect organic contamination and yield quantitative data in the microgram and nanogram levels.

  13. Polyethylene solidification of low-level wastes

    SciTech Connect

    Kalb, P.D.; Colombo, P.

    1985-02-01

    This topical report describes the results of an investigation on the solidification of low-level radioactive waste in polyethylene. Waste streams selected for this study included those which result from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those which remain problematic for solidification using contemporary agents (ion exchange resins). Four types of commercially available low-density polyethylenes were employed which encompass a range of processing and property characteristics. Process development studies were conducted to ascertain optimal process control parameters for successful solidification. Maximum waste loadings were determined for each waste and polyethylene type. Property evaluation testing was performed on laboratory-scale specimens to assess the potential behavior of actual waste forms in a disposal environment. Waste form property tests included water immersion, deformation under compressive load, thermal cycling and radionuclide leaching. Recommended waste loadings of 70 wt % sodium sulfate, 50 wt % boric acid, 40 wt % incinerator ash, and 30 wt % ion exchange resins, which are based on process control and waste form performance considerations are reported. 37 refs., 33 figs., 22 tabs.

  14. Language abstractions for low level optimization techniques

    NASA Astrophysics Data System (ADS)

    Dévai, Gergely; Gera, Zoltán; Kelemen, Zoltán

    2012-09-01

    In case of performance critical applications programmers are often forced to write code at a low abstraction level. This leads to programs that are hard to develop and maintain because the program text is mixed up by low level optimization tricks and is far from the algorithm it implements. Even if compilers are smart nowadays and provide the user with many automatically applied optimizations, practice shows that in some cases it is hopeless to optimize the program automatically without the programmer's knowledge. A complementary approach is to allow the programmer to fine tune the program but provide him with language features that make the optimization easier. These are language abstractions that make optimization techniques explicit without adding too much syntactic noise to the program text. This paper presents such language abstractions for two well-known optimizations: bitvectors and SIMD (Single Instruction Multiple Data). The language features are implemented in the embedded domain specific language Feldspar which is specifically tailored for digital signal processing applications. While we present these language elements as part of Feldspar, the ideas behind them are general enough to be applied in other language definition projects as well.

  15. Molecular dynamics simulations of solutions at constant chemical potential

    NASA Astrophysics Data System (ADS)

    Perego, C.; Salvalaglio, M.; Parrinello, M.

    2015-04-01

    Molecular dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, which range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, which influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a grand-canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work, we propose the Constant Chemical Potential Molecular Dynamics (CμMD) method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the CμMD method to the paradigmatic case of urea crystallization in aqueous solution. As a result, we have been able to study crystal growth dynamics under constant supersaturation conditions and to extract growth rates and free-energy barriers.

  16. Efficient solution techniques for simulation nutrient uptake by plant roots

    NASA Astrophysics Data System (ADS)

    Abesha, Betiglu; Vanderborght, Jan; Javaux, Mathieu; Schnepf, Andrea; Vereecken, Harry

    2015-04-01

    Water and nutrient transfer to plant roots is determined by processes occurring from the single root to the entire root system. A mechanistic spatially distributed description of these processes would require a sub mm discretization which is computationally not feasible. In this contribution, we present efficient solution techniques to represent accurate nutrient uptake by plant roots. The first solution technique describes nutrient transport towards a single root segment using a 1-D radially axisymmetric model (Barber and Cushman 1981). Transport to the entire root system is represented by a network of connected cylindrical models around the roots. This network of cylinders was coupled to a 3-D regular grid that was used to solve the flow and transport equations in the soil at the root system scale (Javaux et al. 2008). The second technique was a modified time compression approximation (TCA), which can be a simple and reasonably accurate semi-analytical method for predicting cumulative nutrient uptake when the convection flux and diffusion coefficient change over time due to for instance soil drying. The analytical approach presented by Roose et al. (2001) to calculate solute cumulative uptake provides means to analyze cumulative nutrient uptake at a changing diffusive-convective flux over time but with constant convection and diffusion coefficient. This analytical solution was used in TCA framework to predict uptake when convection and diffusion coefficient change over time. We compared cumulative nutrient uptake by the 1D / 3D coupled model with results obtained by spatially highly resolved 3-D model and the approximate analytical solution of Roose et al. (2001). The good agreement between both model approaches allows the use of the 1D/3D coupling approach to simulate water and nutrient transport at the a root system scale with minimal computational cost and good accuracy. This approach also accounts for the effect of transpiration and soil drying on nutrient

  17. Numerical error in groundwater flow and solute transport simulation

    NASA Astrophysics Data System (ADS)

    Woods, Juliette A.; Teubner, Michael D.; Simmons, Craig T.; Narayan, Kumar A.

    2003-06-01

    Models of groundwater flow and solute transport may be affected by numerical error, leading to quantitative and qualitative changes in behavior. In this paper we compare and combine three methods of assessing the extent of numerical error: grid refinement, mathematical analysis, and benchmark test problems. In particular, we assess the popular solute transport code SUTRA [Voss, 1984] as being a typical finite element code. Our numerical analysis suggests that SUTRA incorporates a numerical dispersion error and that its mass-lumped numerical scheme increases the numerical error. This is confirmed using a Gaussian test problem. A modified SUTRA code, in which the numerical dispersion is calculated and subtracted, produces better results. The much more challenging Elder problem [Elder, 1967; Voss and Souza, 1987] is then considered. Calculation of its numerical dispersion coefficients and numerical stability show that the Elder problem is prone to error. We confirm that Elder problem results are extremely sensitive to the simulation method used.

  18. An efficient solution for hazardous geophysical flows simulation using GPUs

    NASA Astrophysics Data System (ADS)

    Lacasta, A.; Juez, C.; Murillo, J.; García-Navarro, P.

    2015-05-01

    The movement of poorly sorted material over steep areas constitutes a hazardous environmental problem. Computational tools help in the understanding and predictions of such landslides. The main drawback is the high computational effort required for obtaining accurate numerical solutions due to the high number of cells involved in the calculus. In order to overcome this problem, this work proposes the use of GPUs for decreasing significantly the CPU simulation time. The numerical scheme implemented in GPU is based on a finite volume scheme and it was validated in previous work with exact solutions and experimental data. The computational cost time obtained with the Graphical Hardware technology, GPU, is compared against Single-Core (sequential) and Multi-Core (parallel) CPU implementations. The GPU implementation allows to reduce the computational cost time in two orders of magnitude.

  19. Simulation of transportation of low enriched uranium solutions

    SciTech Connect

    Hope, E.P.; Ades, M.J.

    1996-08-01

    A simulation of the transportation by truck of low enriched uranium solutions has been completed for NEPA purposes at the Savannah River Site. The analysis involves three distinct source terms, and establishes the radiological risks of shipment to three possible destinations. Additionally, loading accidents were analyzed to determine the radiological consequences of mishaps during handling and delivery. Source terms were developed from laboratory measurements of chemical samples from low enriched uranium feed materials being stored at SRS facilities, and from manufacturer data on transport containers. The transportation simulations were accomplished over the INTERNET using the DOE TRANSNET system at Sandia National Laboratory. The HIGHWAY 3.3 code was used to analyze routing scenarios, and the RADTRAN 4 code was used to analyze incident free and accident risks of transporting radiological materials. Loading accidents were assessed using the Savannah River Site AXAIR89Q and RELEASE 2 codes.

  20. Dielectric response of triplex DNA in ionic solution from simulations.

    PubMed Central

    Yang, L; Weerasinghe, S; Smith, P E; Pettitt, B M

    1995-01-01

    We have analyzed a 1.2-ns molecular dynamics simulation of 51 mM d(CG.G)7 with 21 Na+ counter-ions and 1 M NaCl in water. Via the dipole fluctuations, the dielectric constant for the DNA is found to be around 16, whereas that for the bases and sugars combined is only 3. The dielectric constant for water in this system is 41, which is much smaller than 71 for pure SPC/E water, because of the strong restriction imposed on the motion of water molecules by the DNA and the ions. Also addressed in the present work are several technical issues related to the calculation of the dipole moment of an ionic solution from molecular dynamics simulations using periodic boundary conditions. PMID:8534822

  1. An overview of the geochemical code MINTEQ: Applications to performance assessment for low-level wastes

    SciTech Connect

    Peterson, S.R.; Opitz, B.E.; Graham, M.J.; Eary, L.E.

    1987-03-01

    The MINTEQ geochemical computer code, developed at the Pacific Northwest Laboratory (PNL), integrates many of the capabilities of its two immediate predecessors, MINEQL and WATEQ3. The MINTEQ code will be used in the Special Waste Form Lysimeters-Arid program to perform the calculations necessary to simulate (model) the contact of low-level waste solutions with heterogeneous sediments of the interaction of ground water with solidified low-level wastes. The code can calculate ion speciation/solubilitya, adsorption, oxidation-reduction, gas phase equilibria, and precipitation/dissolution of solid phases. Under the Special Waste Form Lysimeters-Arid program, the composition of effluents (leachates) from column and batch experiments, using laboratory-scale waste forms, will be used to develop a geochemical model of the interaction of ground water with commercial, solidified low-level wastes. The wastes being evaluated include power-reactor waste streams that have been solidified in cement, vinyl ester-styrene, and bitumen. The thermodynamic database for the code was upgraded preparatory to performing the geochemical modeling. Thermodynamic data for solid phases and aqueous species containing Sb, Ce, Cs, or Co were added to the MINTEQ database. The need to add these data was identified from the characterization of the waste streams. The geochemical model developed from the laboratory data will then be applied to predict the release from a field-lysimeter facility that contains full-scale waste samples. The contaminant concentrations migrating from the waste forms predicted using MINTEQ will be compared to the long-term lysimeter data. This comparison will constitute a partial field validation of the geochemical model.

  2. Properties of slag concrete for low-level waste containment

    SciTech Connect

    Langton, C.A.; Wong, P.B.

    1991-12-31

    Ground granulated blast furnace slag was incorporated in the concrete mix used for construction of low-level radioactive waste disposal vaults. The vaults were constructed as six 100 {times} 100 {times} 25 ft cells with each cell sharing internal walls with the two adjacent cells. The vaults were designed to contain a low-level radioactive wasteform called saltstone and to isolate the saltstone from the environment until the landfill is closed. Closure involves backfilling with native soil, installation of clay cap, and run-off control. The design criteria for the slag-substituted concrete included compressive strength, 4000 psi after 28 days; slump, 6 inch; permeability, less than 10{sup {minus}7} cm/sec; and effective nitrate, chromium and technetium diffusivities of 10{sup {minus}8}, 10{sup {minus}12} and 10{sup {minus}12} cm{sup 2}/sec, respectively. The reducing capacity of the slag resulted in chemically reducing Cr{sup +6} to Cr{sup +3} and Tc{sup +7} to Tc{sup +4} and subsequent precipitation of the respective hydroxides in the alkaline pore solution. Consequently, the concrete vault enhances containment of otherwise mobile waste ions and contributes to the overall protection of the groundwater at the disposal site.

  3. Properties of slag concrete for low-level waste containment

    SciTech Connect

    Langton, C.A. ); Wong, P.B. )

    1991-01-01

    Ground granulated blast furnace slag was incorporated in the concrete mix used for construction of low-level radioactive waste disposal vaults. The vaults were constructed as six 100 {times} 100 {times} 25 ft cells with each cell sharing internal walls with the two adjacent cells. The vaults were designed to contain a low-level radioactive wasteform called saltstone and to isolate the saltstone from the environment until the landfill is closed. Closure involves backfilling with native soil, installation of clay cap, and run-off control. The design criteria for the slag-substituted concrete included compressive strength, 4000 psi after 28 days; slump, 6 inch; permeability, less than 10{sup {minus}7} cm/sec; and effective nitrate, chromium and technetium diffusivities of 10{sup {minus}8}, 10{sup {minus}12} and 10{sup {minus}12} cm{sup 2}/sec, respectively. The reducing capacity of the slag resulted in chemically reducing Cr{sup +6} to Cr{sup +3} and Tc{sup +7} to Tc{sup +4} and subsequent precipitation of the respective hydroxides in the alkaline pore solution. Consequently, the concrete vault enhances containment of otherwise mobile waste ions and contributes to the overall protection of the groundwater at the disposal site.

  4. Methods for simulating solute breakthrough curves in pumping groundwater wells

    USGS Publications Warehouse

    Starn, J. Jeffrey; Bagtzoglou, Amvrossios C.; Robbins, Gary A.

    2012-01-01

    In modeling there is always a trade-off between execution time and accuracy. For gradient-based parameter estimation methods, where a simulation model is run repeatedly to populate a Jacobian (sensitivity) matrix, there exists a need for rapid simulation methods of known accuracy that can decrease execution time, and thus make the model more useful without sacrificing accuracy. Convolution-based methods can be executed rapidly for any desired input function once the residence-time distribution is known. The residence-time distribution can be calculated efficiently using particle tracking, but particle tracking can be ambiguous near a pumping well if the grid is too coarse. We present several embedded analytical expressions for improving particle tracking near a pumping well and compare them with a finely gridded finite-difference solution in terms of accuracy and CPU usage. Even though the embedded analytical approach can improve particle tracking near a well, particle methods reduce, but do not eliminate, reliance on a grid because velocity fields typically are calculated on a grid, and additional error is incurred using linear interpolation of velocity. A dilution rate can be calculated for a given grid and pumping well to determine if the grid is sufficiently refined. Embedded analytical expressions increase accuracy but add significantly to CPU usage. Structural error introduced by the numerical solution method may affect parameter estimates.

  5. Multiphase fluid simulation tools for winning remediation solutions

    SciTech Connect

    Deschaine, L.M.

    1997-07-01

    Releases of petroleum product such as gasoline and diesel fuels from normal operating practices to aquifers are common. The costs to remediate these releases can run in the billions of dollars. Solutions to remediate these releases usually consist of some form of multiphase (air, water, oil) fluid movement, whether it be a multiphase high vacuum extraction system, bioslurping, groundwater pump and treat system, an air sparging system, a soil vapor extraction system, a free product recovery system, bioremediation or the like. The software being tested in Test Drive, Multiphase Organic Vacuum Enhanced Recovery Simulator (MOVER) is a computer simulation tool that will give the practitioner the ability to design high vacuum enhanced multiple phase recovery systems and bioslurping systems, which are often the low cost effective remediation approach. It will also allow for the comparison of various proposed remediation approaches and technologies so the best solution can be chosen for a site. This is a key competitive advantage to translate conceptual ideas into winning bids.

  6. Methods for simulating solute breakthrough curves in pumping groundwater wells

    NASA Astrophysics Data System (ADS)

    Jeffrey Starn, J.; Bagtzoglou, Amvrossios C.; Robbins, Gary A.

    2012-11-01

    In modeling there is always a trade-off between execution time and accuracy. For gradient-based parameter estimation methods, where a simulation model is run repeatedly to populate a Jacobian (sensitivity) matrix, there exists a need for rapid simulation methods of known accuracy that can decrease execution time, and thus make the model more useful without sacrificing accuracy. Convolution-based methods can be executed rapidly for any desired input function once the residence-time distribution is known. The residence-time distribution can be calculated efficiently using particle tracking, but particle tracking can be ambiguous near a pumping well if the grid is too coarse. We present several embedded analytical expressions for improving particle tracking near a pumping well and compare them with a finely gridded finite-difference solution in terms of accuracy and CPU usage. Even though the embedded analytical approach can improve particle tracking near a well, particle methods reduce, but do not eliminate, reliance on a grid because velocity fields typically are calculated on a grid, and additional error is incurred using linear interpolation of velocity. A dilution rate can be calculated for a given grid and pumping well to determine if the grid is sufficiently refined. Embedded analytical expressions increase accuracy but add significantly to CPU usage. Structural error introduced by the numerical solution method may affect parameter estimates.

  7. PLUTONIUM SOLUBILITY IN SIMULATED SAVANNAH RIVER SITE WASTE SOLUTIONS

    SciTech Connect

    Rudisill, T.; Hobbs, D.; Edwards, T.

    2010-09-27

    To address the accelerated disposition of the supernate and salt portions of Savannah River Site (SRS) high level waste (HLW), solubility experiments were performed to develop a predictive capability for plutonium (Pu) solubility. A statistically designed experiment was used to measure the solubility of Pu in simulated solutions with salt concentrations and temperatures which bounded those observed in SRS HLW solutions. Constituents of the simulated waste solutions included: hydroxide (OH{sup -}), aluminate (Al(OH){sub 4}{sup -}), sulfate (SO{sub 4}{sup 2-}), carbonate (CO{sub 3}{sup 2-}), nitrate (NO{sub 3}{sup -}), and nitrite (NO{sub 2}{sup -}) anions. Each anion was added to the waste solution in the sodium form. The solubilities were measured at 25 and 80 C. Five sets of samples were analyzed over a six month period and a partial sample set was analyzed after nominally fifteen months of equilibration. No discernable time dependence of the measured Pu concentrations was observed except for two salt solutions equilibrated at 80 C which contained OH{sup -} concentrations >5 mol/L. In these solutions, the Pu solubility increased with time. This observation was attributed to the air oxidation of a portion of the Pu from Pu(IV) to the more soluble Pu(V) or Pu(VI) valence states. A data driven approach was subsequently used to develop a modified response surface model for Pu solubility. Solubility data from this study and historical data from the literature were used to fit the model. The model predicted the Pu solubility of the solutions from this study within the 95% confidence interval for individual predictions and the analysis of variance indicated no statistically significant lack of fit. The Savannah River National Laboratory (SRNL) model was compared with predicted values from the Aqueous Electrolyte (AQ) model developed by OLI Systems, Inc. and a solubility prediction equation developed by Delegard and Gallagher for Hanford tank waste. The agreement between

  8. Steam Reforming of Low-Level Mixed Waste

    SciTech Connect

    1998-01-01

    Under DOE Contract No. DE-AR21-95MC32091, Steam Reforming of Low-Level Mixed Waste, ThermoChem has successfully designed, fabricated and operated a nominal 90 pound per hour Process Development Unit (PDU) on various low-level mixed waste surrogates. The design construction, and testing of the PDU as well as performance and economic projections for a 500- lb/hr demonstration and commercial system are described. The overall system offers an environmentally safe, non-incinerating, cost-effective, and publicly acceptable method of processing LLMW. The steam-reforming technology was ranked the No. 1 non-incineration technology for destruction of hazardous organic wastes in a study commissioned by the Mixed Waste Focus Area published April 1997.1 The ThermoChem steam-reforming system has been developed over the last 13 years culminating in this successful test campaign on LLMW surrogates. Six surrogates were successfidly tested including a 750-hour test on material simulating a PCB- and Uranium- contaminated solid waste found at the Portsmouth Gaseous Diffusion Plant. The test results indicated essentially total (>99.9999oA) destruction of RCRA and TSCA hazardous halogenated organics, significant levels of volume reduction (> 400 to 1), and retention of radlonuclides in the volume-reduced solids. Cost studies have shown the steam-reforming system to be very cost competitive with more conventional and other emerging technologies.

  9. Issue briefs on low-level radioactive wastes

    SciTech Connect

    Not Available

    1981-01-01

    This report contains 4 Issue Briefs on low-level radioactive wastes. They are entitled: Handling, Packaging, and Transportation, Economics of LLW Management, Public Participation and Siting, and Low Level Waste Management.

  10. An Implicit Solution Framework for Reactor Fuel Performance Simulation

    SciTech Connect

    Glen Hansen; Chris Newman; Derek Gaston; Cody Permann

    2009-08-01

    The simulation of nuclear reactor fuel performance involves complex thermomechanical processes between fuel pellets, made of fissile material, and the protective cladding that surrounds the pellets. An important design goal for a fuel is to maximize the life of the cladding thereby allowing the fuel to remain in the reactor for a longer period of time to achieve higher degrees of burnup. This presentation presents an initial approach for modeling the thermomechanical response of reactor fuel, and details of the solution method employed within INL's fuel performance code, BISON. The code employs advanced methods for solving coupled partial differential equation systems that describe multidimensional fuel thermomechanics, heat generation, and oxygen transport within the fuel. This discussion explores the effectiveness of a JFNK-based solution of a problem involving three dimensional fully coupled, nonlinear transient heat conduction and that includes pellet displacement and oxygen diffusion effects. These equations are closed using empirical data that is a function of temperature, density, and oxygen hyperstoichiometry. The method appears quite effective for the fuel pellet / cladding configurations examined, with excellent nonlinear convergence properties exhibited on the combined system. In closing, fully coupled solutions of three dimensional thermomechanics coupled with oxygen diffusion appear quite attractive using the JFNK approach described here, at least for configurations similar to those examined in this report.

  11. Low level liquid waste conditioning at the ENEA Trisaia Centre

    SciTech Connect

    Di Pace, L.; Risoluti, P.; Lippolis, G.

    1993-12-31

    At the ENEA Trisaia Centre (Southern Italy) 56 m{sup 3} of radioactive low-level liquid wastes, generated during past operations of the ITREC reprocessing pilot plant and presently stored in a 60,000 liter carbon steel tank, have to be solidified in order to fulfill the specific requirements established by the Safety Authority, taking into account a Technical Guide issued on the matter of Radioactive Waste Management. For this purpose, the design of a facility, for conditioning this liquid LLW by cementation, was completed and submitted to the Safety Authority. The facility, named SIRTE, is composed of a transfer system and a cementation section based on the MOWA technique. Furthermore a qualification program for the treatment and conditioning process has been completed, in order to define the best cement matrix formulation, at the ENEA Casaccia Research Centre. The main characteristics of the cement matrix, coming from tests on simulated conditioned waste, are given.

  12. Summertime Low-Level Jets over the Great Plains

    SciTech Connect

    Stensrud, D.J.

    1996-04-01

    The sky over the southern Great Plains Cloud and Atmospheric Radiation Testbed (CART) site of the Atmospheric Radiation Measurement (ARM) Program during the predawn and early morning hours often is partially obstructed by stratocumulus, stratus fractus, or cumulus fractus that are moving rapidly to the north, even through the surface winds are weak. This cloud movement is evidence of the low-level jet (LLJ), a wind speed maximum that occurs in the lowest few kilometers of the atmosphere. Owing to the wide spacing between upper-air sounding sites and the relatively infrequent sounding launches, LLJ evolution has been difficult to observe adequately, even though the effects of LLJs on moisture flux into North America are large. Model simulation of the LLJ is described.

  13. Application of solvlent change techniques to blended cements used to immobilize low-level radioactive liquid waste

    SciTech Connect

    Kruger, A.A.

    1996-07-01

    The microstructures of hardened portland and blended cement pastes, including those being considered for use in immobilizing hazardous wastes, have a complex pore structure that changes with time. In solvent exchange, the pore structure is examined by immersing a saturated sample in a large volume of solvent that is miscible with the pore fluid. This paper reports the results of solvent replacement measurements on several blended cements mixed at a solution:solids ratio of 1.0 with alkaline solutions from the simulation of the off- gas treatment system in a vitrification facility treating low-level radioactive liquid wastes. The results show that these samples have a lower permeability than ordinary portland cement samples mixed at a water:solids ratio of 0.70, despite having a higher volume of porosity. The microstructure is changed by these alkaline solutions, and these changes have important consequences with regard to durability.

  14. Hierarchical simulation of aquifer heterogeneity: implications of different simulation settings on solute-transport modeling

    NASA Astrophysics Data System (ADS)

    Comunian, Alessandro; De Micheli, Leonardo; Lazzati, Claudio; Felletti, Fabrizio; Giacobbo, Francesca; Giudici, Mauro; Bersezio, Riccardo

    2016-03-01

    The fine-scale heterogeneity of porous media affects the large-scale transport of solutes and contaminants in groundwater and it can be reproduced by means of several geostatistical simulation tools. However, including the available geological information in these tools is often cumbersome. A hierarchical simulation procedure based on a binary tree is proposed and tested on two real-world blocks of alluvial sediments, of a few cubic meters volume, that represent small-scale aquifer analogs. The procedure is implemented using the sequential indicator simulation, but it is so general that it can be adapted to various geostatistical simulation tools, improving their capability to incorporate geological information, i.e., the sedimentological and architectural characterization of heterogeneity. When compared with a standard sequential indicator approach on bi-dimensional simulations, in terms of proportions and connectivity indicators, the proposed procedure yields reliable results, closer to the reference observations. Different ensembles of three-dimensional simulations based on different hierarchical sequences are used to perform numerical experiments of conservative solute transport and to obtain ensembles of equivalent pore velocity and dispersion coefficient at the scale length of the blocks (meter). Their statistics are used to estimate the impact of the variability of the transport properties of the simulated blocks on contaminant transport modeled on bigger domains (hectometer). This is investigated with a one-dimensional transport modeling based on the Kolmogorov-Dmitriev theory of branching stochastic processes. Applying the proposed approach with diverse binary trees and different simulation settings provides a great flexibility, which is revealed by the differences in the breakthrough curves.

  15. Conformable, Low Level Light Therapy platform

    NASA Astrophysics Data System (ADS)

    Jablonski, Michal; Bossuyt, Frederick; Vanfleteren, Jan; Vervust, Thomas; De Smet, Herbert

    2014-05-01

    Well-being applications demand unobtrusive treatment methods in order to reach user acceptance. In the field of light therapy this needs to be carefully addressed because, in most cases, light treatment system size has to be significant with respect to human body scale. At the same time we observe the push to make wearable devices that deliver the treatment on the go. Once scaled up, standard flexible electronics (FPC) fail to conform to body curvatures leading to decrease in comfort. A solution to this problem demands new or modified methods for fabrication of the electronic circuits that fulfill the conformability demand (flexing, but also stretching). Application of Stretchable Molded Interconnect (SMI) technology, that attempts to address these demands, will be discussed. The unique property of SMI is that its manufacturing draws mainly from standard PCB and FCB technologies to inherit the reliability and conductivity. At the same time, however, it allows soft, flexible and stretchable circuits with biomimetic haptics and high optical efficiency. In this work a demonstrator device for blue light therapy of RSI is presented that illustrates the strengths as well as challenges ahead of conformable light circuits. We report system electro-optical efficiency, possible irradiance levels within skin thermal comfort and efficiency under cyclic, tensile stretching deformation.

  16. Aqueous Solutions on Silica Surfaces: Structure and Dynamics from Simulations

    NASA Astrophysics Data System (ADS)

    Striolo, Alberto; Argyris, Dimitrios; Tummala, Naga Rajesh

    2009-03-01

    Our group is interested in understanding the properties of aqueous electrolyte solutions at interfaces. The fundamental questions we seek to answer include: (A) how does a solid structure perturb interfacial water? (B) How far from the solid does this perturbation persist? (C) What is the rate of water reorientation and exchange in the perturbed layer? (D) What happens in the presence of simple electrolytes? To address such topics we implemented atomistic molecular dynamics simulations. Recent results for water and simple electrolytes near silicon dioxide surfaces of various degrees of hydroxylation will be presented. The data suggest the formation of a layered aqueous structure near the interface. The density profile of interfacial water seems to dictate the density profiles of aqueous solutions containing NaCl, CaCl2, CsCl, and SrCl2 near the solid surfaces. These results suggest that ion-ion and ion-water correlations are extremely important factors that should be considered when it is desired to predict the distribution of electrolytes near a charged surface. Our results will benefit a number of practical applications including water desalination, exploitation of the oil shale in the Green River Basin, nuclear waste sites remediation, and design of nanofluidic devices.

  17. Direct simulation of plastocyanin and cytochrome f interactions in solution.

    PubMed

    Kovalenko, I B; Abaturova, A M; Gromov, P A; Ustinin, D M; Grachev, E A; Riznichenko, G Yu; Rubin, A B

    2006-06-01

    Most biological functions, including photosynthetic activity, are mediated by protein interactions. The proteins plastocyanin and cytochrome f are reaction partners in a photosynthetic electron transport chain. We designed a 3D computer simulation model of diffusion and interaction of spinach plastocyanin and turnip cytochrome f in solution. It is the first step in simulating the electron transfer from cytochrome f to photosystem 1 in the lumen of thylakoid. The model is multiparticle and it can describe the interaction of several hundreds of proteins. In our model the interacting proteins are represented as rigid bodies with spatial fixed charges. Translational and rotational motion of proteins is the result of the effect of stochastic Brownian force and electrostatic force. The Poisson-Boltzmann formalism is used to determine the electrostatic potential field generated around the proteins. Using this model we studied the kinetic characteristics of plastocyanin-cytochrome f complex formation for plastocyanin mutants at pH 7 and a variety of ionic strength values. PMID:16829698

  18. Midlatitude Tropopause and Low-Level Moisture

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Pauluis, O. M.; Shaw, T. A.

    2014-12-01

    A new relationship between the surface distribution of equivalent potential temperature and the potential temperature at the tropopause is proposed. Using a Gaussian approximation for the distribution of equivalent potential temperature, we argue that the tropopause potential temperature is approximately given by the mean equivalent potential temperature at the surface plus twice its standard derivation. This relationship is motivated by the comparison of the meridional circulation on dry and moist isentropes. It is further tested using four reanalysis datasets: the Interim ECMWF Re-Analysis (ERA-Interim); the NCEP-Department of Energy (DOE) Reanalysis II; the NCEP Climate Forecast System Reanalysis; and the Twentieth-Century Reanalysis (20CR), version 2. The proposed relationship successfully captures the annual cycle of the tropopause for both hemispheres. The results are robust among different reanalysis datasets, albeit the 20CR tends to overestimate the tropopause potential temperature. Furthermore, the proposed mechanism also works well in obtaining the inter-annual variability (with climatological annual cycle removed) for Northern Hemisphere summer with an above 0.6 correlation across different reanalyses. On the contrary, this mechanism is rather weak in explaining the interannual variability in the Southern Hemisphere and no longer works for Northern Hemisphere wintertime. This work suggests the important role of the moist dynamics in determining the midlatitude tropopause. In order to better understand the dynamical mechanisms, we make use of an idealized aquaplanet model simulation with a prescribed subtropical planetary-scale wave sea surface temperature perturbation, which mimics the land-ocean heating asymmetry. A similar dynamical connection is also found in this idealized model experiment, which reveals possible mechanisms related to the Asian monsoon and subtropical anticyclones. Finally, the representation of the dynamical relationship in CMIP5

  19. Decontamination processes for low level radioactive waste metal objects

    SciTech Connect

    Longnecker, E.F.; Ichikawa, Sekigo; Kanamori, Osamu

    1996-12-31

    Disposal and safe storage of contaminated nuclear waste is a problem of international scope. Although the greatest volume of such waste is concentrated in the USA and former Soviet Union, Western Europe and Japan have contaminated nuclear waste requiring attention. Japan`s radioactive nuclear waste is principally generated at nuclear power plants since it has no nuclear weapons production. However, their waste reduction, storage and disposal problems may be comparable to that of the USA on an inhabited area basis when consideration is given to population density where Japan`s population, half that of the USA, lives in an area slightly smaller than that of California`s. If everyone`s backyard was in California, the USA might have insoluble radioactive waste reduction, storage and disposal problems. Viewing Japan`s contaminated nuclear waste as a national problem requiring solutions, as well as an economic opportunity, Morikawa began research and development for decontaminating low level radioactive nuclear waste seven years ago. As engineers and manufacturers of special machinery for many years Morikawa brings special electro/mechanical/pneumatic Skills and knowledge to solving these unique problems. Genden Engineering Services and Construction Company (GESC), an affiliate of Japan Atomic Power Company, recently joined with Morikawa in this R&D effort to decontaminate low level radioactive nuclear waste (LLW) and to substantially reduce the volume of such nuclear waste requiring long term storage. This paper will present equipment with both mechanical and chemical processes developed over these several years by Morikawa and most recently in cooperation with GESC.

  20. Impact of Low-level Jet on Regional Ozone

    NASA Astrophysics Data System (ADS)

    Liu, F.

    2011-12-01

    During spring and summer seasons, the frequent occurrences of nocturnal low-level jet (LLJ) over Great Plains region of the United States are widely recognized. As an important element of the low-level atmospheric circulation this LLJ effectively transports water vapor from the Gulf of Mexico, which in turn affects the development of server weather over the central United States. The LLJ has long been known to be conducive to summer rainfall and widespread flooding over the Great Plains of North America. The LLJ transports more than just moisture. Ozone episodes occur mainly during summer and are influenced by regional transport. Little is known, however,about the interrelation between the Great Plains LLJ and regional ozone transport. In this study, analysis of observational data during 1993-2006 has shown strong influence of the Great Plains LLJ on local and regional ozone distributions. Hourly ozone measurements from Air Quality System (AQS) are compared with wind fields at 850 hPa from the NCEP North American Regional Reanalysis (NARR). It is demonstrated that the low ozone concentrations over Texas in late spring and summer are identified with large LLJ transport of clean marine air mass from the Gulf of Mexico. Significant negative correlations exist between daily ozone concentration and LLJ index (Figure 1), suggesting that lower ozone over Texas is associated with stronger LLJ. On the other hand, positive correlations occur in the Midwest and Northeast, indicating the important role of regional transport of ozone and precursors along the pathway by the wind circulation accompanying the LLJ. In addition, the LLJ is significantly correlated with northerly flows in the eastern Pacific Ocean and the adjacent coast. This relationship explains the coexistence of low ozone concentrations in Texas and southwestern U.S during summer, both attributed to the inland transport of clean marine air. These observed ozone-LLJ patterns are well simulated by the regional CMM5

  1. Leaching studies of low-level radioactive waste forms

    SciTech Connect

    Dayal, R.; Arora, H.; Milian, L.; Clinton, J.

    1985-01-01

    A research program has been underway at the Brookhaven National Laboratory to investigate the release of radionuclides from low-level waste forms under laboratory conditions. This paper describes the leaching behavior of Cs-137 from two major low-level waste streams, that is, ion exchange bead resin and boric acid concentrate, solidified in Portland cement. The resultant leach data are employed to evaluate and predict the release behavior of Cs-137 from low-level waste forms under field burial conditions.

  2. Twelfth annual US DOE low-level waste management conference

    SciTech Connect

    Not Available

    1990-01-01

    The papers in this document comprise the proceedings of the Department of Energy's Twelfth Annual Low-Level Radioactive Waste Management Conference, which was held in Chicago, Illinois, on August 28 and 29, 1990. General subjects addressed during the conference included: mixed waste, low-level radioactive waste tracking and transportation, public involvement, performance assessment, waste stabilization, financial assurance, waste minimization, licensing and environmental documentation, below-regulatory-concern waste, low-level radioactive waste temporary storage, current challenges, and challenges beyond 1990.

  3. Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado

    USGS Publications Warehouse

    Robson, S.G.; Saulnier, G.J., Jr.

    1981-01-01

    Oil-shale mining activities in Piceance basin in northwestern Colorado could adversely affect the ground- and surface-water quality in the basin. This study of the hydrology and geochemistry of the area used ground-water solute-transport-modeling techniques to investigate the possible impact of the mines on water quality. Maps of the extent and structure of the aquifer were prepared and show that a saturated thickness of 2,000 feet occurs in the northeast part of the basin. Ground-water recharge in the upland areas in the east, south, and west parts of the basin moves down into deeper zones in the aquifer and laterally to the discharge areas along Piceance and Yellow Creeks. The saline zone and the unsaturated zone provide the majority of the dissolved solids found in the ground water. Precipitation, ion-exchange, and oxidation-reduction reactions are also occuring in the aquifer. Model simulations of ground-water pumpage in tracts C-a and C-b indicate that the altered direction of ground-water movement near the pumped mines will cause an improvement in ground-water quality near the mines and a degradation of water quality downgradient from the tracts. Model simulations of mine leaching in tract C-a and C-b indicate that equal rates of mine leaching in the tracts will produce much different effects on the water quality in the basin. Tract C-a, by virtue of its remote location from perennial streams, will primarily degrade the ground-water quality over a large area to the northeast of the tract. Tract C-b, by contrast, will primarily degrade the surface-water quality in Piceance Creek, with only localized effects on the ground-water quality. (USGS)

  4. Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado

    USGS Publications Warehouse

    Robson, Stanley G.; Saulnier, George J.

    1980-01-01

    Oil-shale mining activities in Piceance basin in northwestern Colorado could adversely affect the ground- and surface-water quality in the basin. This study of the hydrology and geochemistry of the area used groundwater solute-transport-modeling techniques to investigate the possible impact of the mines on water quality. Maps of the extent and structure of the aquifer were prepared and show that a saturated thickness of 2,000 feet occurs in the northeast part of the basin. Ground-water recharge in the upland areas in the east, south, and west parts of the basin moves down into deeper zones in the aquifer and laterally to the discharge areas along Piceance and Yellow Creeks. The saline zone and the unsaturated zone provide the majority of the dissolved solids found in the ground water. Precipitation, ion-exchange, and oxidation-reduction reactions are also occurring in the aquifer. Model simulations of groundwater pumpage in tracts C-a and C-b indicate that the altered direction of groundwater movement near the pumped mines will cause an improvement in groundwater quality near the mines and a degradation of water quality downgradient from the tracts. Model simulations of mine leaching in tract C-a and C-b indicate that equal rates of mine leaching in the tracts will produce much different effects on the water quality in the basin. Tract C-a, by virtue of its remote location from perennial streams, will primarily degrade the groundwater quality over a large area to the northeast of the tract. Tract C-b, by contrast, will primarily degrade the surface-water quality in Piceance Creek, with only localized effects on the groundwater quality. (USGS)

  5. Hydrogen absorption in iron exposed to simulated concrete pore solutions

    SciTech Connect

    Lillard, R.S.; Scully, J.R.

    1996-02-01

    Safe cathodic protection (CP) limits are required for prestressed steel in concrete to avoid the risk of hydrogen embrittlement (HE). This preliminary study addressed some effects of concrete pore solution chemistry and metal surface condition on hydrogen absorption in iron. To accomplish this, the Devanathan-Stachurski permeation technique was used to investigate hydrogen absorption in 99.5% iron foils exposed to NaOH, saturated Ca(OH){sub 2}, and saturated Ca(OH){sub 2} + 0.6 M NaCl, all at pH 12.5. The foils used in this investigation were tested after various surface preparations: (a) polished, (b) with a thermal oxide formed by a heat treatment designed to simulate the stress relief oxide, and (c) with corrosion films to simulate an inservice tendon that was exposed to a marine environment for some time prior to CP. Hydrogen uptake in iron was most efficient for foils covered with Portland cement-based mortar, at least 2.5 times greater than that in NaOH of the same pH and hydrogen production rate. Absorption in saturated Ca(OH){sub 2} was somewhat less than that from the mortar cover. While chloride had no direct effect on the hydrogen absorption rate, the corrosion product and the thermal oxide were found to decrease hydrogen absorption compared to polished iron. The thermal oxide acted as a complete barrier at all charging current densities investigated. The effectiveness of this thermal oxide barrier to hydrogen, however, was compromised by corrosion resulting from alternate immersion exposure to a chloride environment.

  6. Low-Level Waste (LLW) forum meeting report

    SciTech Connect

    1995-12-31

    The Low-Level Radioactive Waste Forum (LLW Forum) is an association of state and compact representatives, appointed by governors and compact commissions, established to facilitate state and compact implementation of the Low-Level Radioactive Waste Policy Act of 1980 and the Low-Level Radioactive Waste Policy Amendments Act of 1985 and to promote the objectives of low-level radioactive waste regional compacts. The LLW Forum provides an opportunity for state and compact officials to share information with one another and to exchange views with officials of federal agencies and other interested parties.

  7. Simulator for an Accelerator-Driven Subcritical Fissile Solution System

    SciTech Connect

    Klein, Steven Karl; Day, Christy M.; Determan, John C.

    2015-09-14

    LANL has developed a process to generate a progressive family of system models for a fissile solution system. This family includes a dynamic system simulation comprised of coupled nonlinear differential equations describing the time evolution of the system. Neutron kinetics, radiolytic gas generation and transport, and core thermal hydraulics are included in the DSS. Extensions to explicit operation of cooling loops and radiolytic gas handling are embedded in these systems as is a stability model. The DSS may then be converted to an implementation in Visual Studio to provide a design team the ability to rapidly estimate system performance impacts from a variety of design decisions. This provides a method to assist in optimization of the system design. Once design has been generated in some detail the C++ version of the system model may then be implemented in a LabVIEW user interface to evaluate operator controls and instrumentation and operator recognition and response to off-normal events. Taken as a set of system models the DSS, Visual Studio, and LabVIEW progression provides a comprehensive set of design support tools.

  8. Solution Structures of Rat Amylin Peptide: Simulation, Theory, and Experiment

    PubMed Central

    Reddy, Allam S.; Wang, Lu; Lin, Yu-Shan; Ling, Yun; Chopra, Manan; Zanni, Martin T.; Skinner, James L.; De Pablo, Juan J.

    2010-01-01

    Abstract Amyloid deposits of amylin in the pancreas are an important characteristic feature found in patients with Type-2 diabetes. The aggregate has been considered important in the disease pathology and has been studied extensively. However, the secondary structures of the individual peptide have not been clearly identified. In this work, we present detailed solution structures of rat amylin using a combination of Monte Carlo and molecular dynamics simulations. A new Monte Carlo method is presented to determine the free energy of distinct biomolecular conformations. Both folded and random-coil conformations of rat amylin are observed in water and their relative stability is examined in detail. The former contains an α-helical segment comprised of residues 7–17. We find that at room temperature the folded structure is more stable, whereas at higher temperatures the random-coil structure predominates. From the configurations and weights we calculate the α-carbon NMR chemical shifts, with results that are in reasonable agreement with experiments of others. We also calculate the infrared spectrum in the amide I stretch regime, and the results are in fair agreement with the experimental line shape presented herein. PMID:20141758

  9. Extensions to Dynamic System Simulation of Fissile Solution Systems

    SciTech Connect

    Klein, Steven Karl; Bernardin, John David; Kimpland, Robert Herbert; Spernjak, Dusan

    2015-08-24

    Previous reports have documented the results of applying dynamic system simulation (DSS) techniques to model a variety of fissile solution systems. The SUPO (Super Power) aqueous homogeneous reactor (AHR) was chosen as the benchmark for comparison of model results to experimental data for steadystate operation.1 Subsequently, DSS was applied to additional AHR to verify results obtained for SUPO and extend modeling to prompt critical excursions, ramp reactivity insertions of various magnitudes and rate, and boiling operations in SILENE and KEWB (Kinetic Experiment Water Boiler).2 Additional models for pressurized cores (HRE: Homogeneous Reactor Experiment), annular core geometries, and accelerator-driven subcritical systems (ADAHR) were developed and results reported.3 The focus of each of these models is core dynamics; neutron kinetics, thermal hydraulics, radiolytic gas generation and transport are coupled to examine the time-based evolution of these systems from start-up through transition to steady-state. A common characteristic of these models is the assumption that (a) core cooling system inlet temperature and flow and (b) plenum gas inlet pressure and flow are held constant; no external (to core) component operations that may result in dynamic change to these parameters are considered. This report discusses extension of models to include explicit reference to cooling structures and radiolytic gas handling. The accelerator-driven subcritical generic system model described in References 3 and 4 is used as a basis for this extension.

  10. First participation by the NMISA in a low-level comparison: CCRI(II)-S9 exercise.

    PubMed

    van Wyngaardt, W M; van Staden, M J; Lubbe, J

    2013-11-01

    The NMISA Radioactivity Standards Laboratory participated in the CCRI(II)-S9 inter-comparison of the measurement of the activity concentration of (137)Cs and (40)K in rice material, piloted by the KRISS. The paper describes the equipment used, the measurement set-up and data analysis. The efficiency of the detector for (137)Cs and (40)K was determined by comparison against a spiked standard solution, and Monte Carlo simulations performed to estimate the difference in γ-ray escape probability between the solution standard and starch (as an approximation for milled rice) due to attenuation disparities. The uncertainty budget was estimated rather conservatively, since these were the first low-level measurements performed by the NMISA using an HPGe detector. PMID:23562433

  11. Dielectric Properties of Low-Level Liquid Waste

    SciTech Connect

    L. E. Lagos; M. A. Ebadian

    1998-10-20

    The purpose of this study was to develop a data collection containing values for the dielectric properties of various low-level liquid waste (LLLW) simulants measured as a function of frequency, temperature, and composition. The investigation was motivated by current interest in the use of microwave processing for the treatment of radioactive waste. A large volume of transuranic liquid and sludge produced by the U.S. Department of Defense (DOD) during the production of nuclear fiel bars is stored at several U.S. Department of Energy (DOE) sites around the United States. Waste storage and disposal space is scarce, expensive, and must be minimized. Thus, several DOE sites are pursuing the use of microwave heating as a means of achieving volume reduction and solidification of low-level liquid wastes. It is important to know which microwave frequencies should be employed tc achieve the most efficient processing at a range of different temperatures. The dielectric properties of the LLLW simulants can be utilized to determine the optimum frequencies for use with a particular LLLW or with other LLLWS of similar composition. Furthermore, nonlinear thermal processes, such as thermal runaway, which occur in the material being treated cannot be modeled without a knowledge of the temperature dependence of the dielectric properties. Often, this data does not exist; however, when it does, only very limited data near room temperature are available. The data collection generated in this study can be used to predict the behavior of a variety of microwave thermal treatment technologies, which have the potential of substantially reducing the volume of the LLLWS that are currently stored at many DOE sites. This information should help the users of the microwave reduction and solidification technology to optimize microwave processes used in the treatment of LLLW. The microwave reduction and solidification technology has clear advantages over other methods of reducing LLLWS. These

  12. Directions in low-level radioactive waste management: A brief history of commercial low-level radioactive waste disposal

    SciTech Connect

    Not Available

    1994-08-01

    This report presents a history of commercial low-level radioactive waste disposal in the United States, with emphasis on the history of six commercially operated low-level radioactive waste disposal facilities. The report includes a brief description of important steps that have been taken during the last decade to ensure the safe disposal of low-level radioactive waste in the 1990s and beyond. These steps include the issuance of comprehensive State and Federal regulations governing the disposal of low-level radioactive waste, and the enactment of Federal laws making States responsible for the disposal of such waste generated within their borders.

  13. Development studies for the treatment of ORNL low-level liquid waste

    SciTech Connect

    Campbell, D.O.; Lee, D.D.; Dillow, T.A.

    1991-11-01

    An experimental program is under way to investigate potential separation methods for application to specific problems relating to the management of low-level liquid wastes (LLLWs) at ORNL. This report summarizes experimental results that were acquired during fiscal year 1990 and have not been previously reported elsewhere. Measurements are presented for cesium and strontium removal from simulated high-salt waste compositions, using both inorganic ion- exchange sorbents and organic ion-exchange resins, and for one experiment with actual LLLW supernate solution from Melton Valley Storage Tank W-26, using inorganic sorbents. The purpose of the study was to acquire an extensive data base to support the development of flowsheets for decontamination of the LLLW currently stored at ORNL. Experimental measurements with inorganic ion exchangers focused on batch separations of cesium using several transition-metal hexacyanoferrate(2) compositions (ferrocyanides) and of strontium using titanium oxide-based sorbents. Cesium distribution coefficients in the range of 1 {times} 10{sup 6} were generally observed with nickel and cobalt ferrocyanides at pH values {le}11, yielding DFs of about 100 with 100 ppm sorbent in a single-stage batch separation. Most organic ion-exchange resins are not very effective for cesium removal from such high salt concentrations, but a new resorcinol-based resin developed at the Savannah River Site was found to be considerably superior to any other such material tested. Several chelating resins were effective for removing strontium from the waste simulants. An ion-exchange column test successfully demonstrated the simultaneous removal of both cesium and strontium from a waste simulant solution.

  14. Responses to the low-level-radiation controversy

    SciTech Connect

    Bond, V.P.

    1981-10-07

    Some data sets dealing with the hazards of low-level radiation are discussed. It is concluded that none of these reports, individually or collectively, changes appreciably or even significantly the evaluations of possible low-level radiation effects that have been made by several authoritative national and international groups. (ACR)

  15. Molten salt oxidation for treating low-level mixed wastes

    SciTech Connect

    Adamson, M G; Ford, T D; Foster, K G; Hipple, D L; Hopper, R W; Hsu, P C

    1998-12-10

    MS0 is a promising alternative to incineration for the treatment of a variety of organic wastes. Lawrence Livermore National Laboratory (LLNL) has prepared a facility (please see the photo attached) in which an integrated pilot-scale MS0 treatment system is being tested and demonstrated. The system consists of a MS0 vessel with a dedicated off-gas treatment system, a salt recycle system, feed preparation equipment, and a ceramic final waste forms immobilization system. The MSO/off-gas system has been operational since December 1997. The salt recycle system and the ceramic final forms immobilization became operational in May and August 1998, respectively. We have tested the MS0 facility with various organic feeds, including chlorinated solvents; tributyl phosphate/kerosene, PCB-contaminated waste oils & solvents, booties, plastic pellets, ion exchange resins, activated carbon, radioactive-spiked organics, and well-characterized low- level liquid mixed wastes. MS0 is a versatile technology for hazardous waste treatment and may be a solution to many waste disposal problems. In this paper we will present our operational experience with MS0 and also discuss its process capabilities as well as performance data with different feeds.

  16. Application of Low level Lasers in Dentistry (Endodontic)

    PubMed Central

    Asnaashari, Mohammad; Safavi, Nassimeh

    2013-01-01

    Low level lasers, cold or soft lasers: These lasers do not produce thermal effects on tissues and induce photoreactions in cells through light stimulation which is called photobiostimulation. Power of these lasers is usually under 250mW. The main point differentiating low level lasers and high power ones is the activation of photochemical reactions without heat formation. The most important factor to achieve this light characteristic in lasers is not their power, but their power density for each surfa ceunit (i.e cm2). Density lower than 670mW/cm2, can induce the stimulatory effects of low level lasers without thermal effects. Low level lasers (therapeutic) used today as treatment adjunctive devices in medicine and dentistry. Numerous studies have been performed on the applications of low level lasers in patient pain reduction. Mechanisms of pain reduction with therapeutic lasers and their application are expressed, and the studies realized in this field are presented. PMID:25606308

  17. The Role of Low-Level Laser in Periodontal Surgeries

    PubMed Central

    Sobouti, Farhad; Khatami, Maziar; Heydari, Mohaddase; Barati, Maryam

    2015-01-01

    Treatment protocols with low-level Laser (also called ‘soft laser therapy) have been used in health care systems for more than three decades. Bearing in mind the suitable sub-cellular absorption and the cellular-vascular impacts, low-level laser may be a treatment of choice for soft tissues. Low-level lasers have played crucial and colorful roles in performing periodontal surgeries. Their anti-inflammatory and painless effects have been variously reported in in-vitro studies. In this present review article, searches have been made in Pub Med, Google Scholar, and Science Direct, focusing on the studies which included low-level lasers, flap-periodontal surgeries, gingivectomy, and periodontal graft. The present study has sought to review the cellular impacts of low-level lasers and its role on reducing pain and inflammation following soft tissue surgical treatments. PMID:25987968

  18. The role of low-level laser in periodontal surgeries.

    PubMed

    Sobouti, Farhad; Khatami, Maziar; Heydari, Mohaddase; Barati, Maryam

    2015-01-01

    Treatment protocols with low-level Laser (also called 'soft laser therapy) have been used in health care systems for more than three decades. Bearing in mind the suitable sub-cellular absorption and the cellular-vascular impacts, low-level laser may be a treatment of choice for soft tissues. Low-level lasers have played crucial and colorful roles in performing periodontal surgeries. Their anti-inflammatory and painless effects have been variously reported in in-vitro studies. In this present review article, searches have been made in Pub Med, Google Scholar, and Science Direct, focusing on the studies which included low-level lasers, flap-periodontal surgeries, gingivectomy, and periodontal graft. The present study has sought to review the cellular impacts of low-level lasers and its role on reducing pain and inflammation following soft tissue surgical treatments. PMID:25987968

  19. Computational model for simulation small testing launcher, technical solution

    NASA Astrophysics Data System (ADS)

    Chelaru, Teodor-Viorel; Cristian, Barbu; Chelaru, Adrian

    2014-12-01

    The purpose of this paper is to present some aspects regarding the computational model and technical solutions for multistage suborbital launcher for testing (SLT) used to test spatial equipment and scientific measurements. The computational model consists in numerical simulation of SLT evolution for different start conditions. The launcher model presented will be with six degrees of freedom (6DOF) and variable mass. The results analysed will be the flight parameters and ballistic performances. The discussions area will focus around the technical possibility to realize a small multi-stage launcher, by recycling military rocket motors. From technical point of view, the paper is focused on national project "Suborbital Launcher for Testing" (SLT), which is based on hybrid propulsion and control systems, obtained through an original design. Therefore, while classical suborbital sounding rockets are unguided and they use as propulsion solid fuel motor having an uncontrolled ballistic flight, SLT project is introducing a different approach, by proposing the creation of a guided suborbital launcher, which is basically a satellite launcher at a smaller scale, containing its main subsystems. This is why the project itself can be considered an intermediary step in the development of a wider range of launching systems based on hybrid propulsion technology, which may have a major impact in the future European launchers programs. SLT project, as it is shown in the title, has two major objectives: first, a short term objective, which consists in obtaining a suborbital launching system which will be able to go into service in a predictable period of time, and a long term objective that consists in the development and testing of some unconventional sub-systems which will be integrated later in the satellite launcher as a part of the European space program. This is why the technical content of the project must be carried out beyond the range of the existing suborbital vehicle

  20. Computational model for simulation small testing launcher, technical solution

    SciTech Connect

    Chelaru, Teodor-Viorel; Cristian, Barbu; Chelaru, Adrian

    2014-12-10

    The purpose of this paper is to present some aspects regarding the computational model and technical solutions for multistage suborbital launcher for testing (SLT) used to test spatial equipment and scientific measurements. The computational model consists in numerical simulation of SLT evolution for different start conditions. The launcher model presented will be with six degrees of freedom (6DOF) and variable mass. The results analysed will be the flight parameters and ballistic performances. The discussions area will focus around the technical possibility to realize a small multi-stage launcher, by recycling military rocket motors. From technical point of view, the paper is focused on national project 'Suborbital Launcher for Testing' (SLT), which is based on hybrid propulsion and control systems, obtained through an original design. Therefore, while classical suborbital sounding rockets are unguided and they use as propulsion solid fuel motor having an uncontrolled ballistic flight, SLT project is introducing a different approach, by proposing the creation of a guided suborbital launcher, which is basically a satellite launcher at a smaller scale, containing its main subsystems. This is why the project itself can be considered an intermediary step in the development of a wider range of launching systems based on hybrid propulsion technology, which may have a major impact in the future European launchers programs. SLT project, as it is shown in the title, has two major objectives: first, a short term objective, which consists in obtaining a suborbital launching system which will be able to go into service in a predictable period of time, and a long term objective that consists in the development and testing of some unconventional sub-systems which will be integrated later in the satellite launcher as a part of the European space program. This is why the technical content of the project must be carried out beyond the range of the existing suborbital vehicle

  1. Conditions necessary for low-level measurements of reactive oxidants

    SciTech Connect

    Nakareseisoon, S.

    1988-01-01

    Chlorine dioxide and ozone are considered to be the alternatives to chlorine for the disinfection of drinking water supplies and also for the treatment of wastewaters prior to discharge. Chlorine dioxide, under normal circumstances, is reduced to chlorite ion which is toxic. The recommended seven-day suggested no-adverse-response levels (SNARL's) of chlorite ion is 0.007 mg/l (7 ppb). Chlorite ion at these low levels cannot be satisfactorily determined by existing methods, and so, it became necessary to develop an analytical method for determining ppb levels of chlorite ion. Such a method can be developed using differential pulse polarography (DPP). The electrochemical reduction of chlorite ion has been studied between pH 3.7-14 and in an ionic strength range of 0.05-3.0 M. The optimum conditions are pH 4.1-4.4 and an ionic strength of 0.45 M. The current under these conditions is a linear function of chlorite ion concentration ranging from 2.77 {times} 10{sup {minus}7} to 2.80 {times} 10{sup {minus}4} M (19 ppb to 19 ppm). The imprecision is better than {plus minus} 1.0% and {plus minus} 3.4% at concentrations of 2.87 {times} 10{sup {minus}5} M and 1.74 {times} 10{sup {minus}6} M, respectively, with a detection limit of 1 {times} 10{sup {minus}7} M (7 ppb). The rate of ozone decomposition has been studied in highly basic solutions (8-15 NaOH), where ozone becomes stable. The mechanism of ozone regeneration was proposed to explain the observed kinetic and to clarify the contradiction concerning the very slow observed rate of ozone decomposition in basic solution.

  2. Observational and model evidence for positive low-level cloud feedback.

    PubMed

    Clement, Amy C; Burgman, Robert; Norris, Joel R

    2009-07-24

    Feedbacks involving low-level clouds remain a primary cause of uncertainty in global climate model projections. This issue was addressed by examining changes in low-level clouds over the Northeast Pacific in observations and climate models. Decadal fluctuations were identified in multiple, independent cloud data sets, and changes in cloud cover appeared to be linked to changes in both local temperature structure and large-scale circulation. This observational analysis further indicated that clouds act as a positive feedback in this region on decadal time scales. The observed relationships between cloud cover and regional meteorological conditions provide a more complete way of testing the realism of the cloud simulation in current-generation climate models. The only model that passed this test simulated a reduction in cloud cover over much of the Pacific when greenhouse gases were increased, providing modeling evidence for a positive low-level cloud feedback. PMID:19628865

  3. Steam reforming of low-level mixed waste. Final report

    SciTech Connect

    1998-06-01

    ThermoChem has successfully designed, fabricated and operated a nominal 90 pound per hour Process Development Unit (PDU) on various low-level mixed waste surrogates. The design, construction, and testing of the PDU as well as performance and economic projections for a 300-lb/hr demonstration and commercial system are described. The overall system offers an environmentally safe, non-incinerating, cost-effective, and publicly acceptable method of processing LLMW. The steam-reforming technology was ranked the No. 1 non-incineration technology for destruction of hazardous organic wastes in a study commissioned by the Mixed Waste Focus Area and published in April 1997. The ThermoChem steam-reforming system has been developed over the last 13 years culminating in this successful test campaign on LLMW surrogates. Six surrogates were successfully tested including a 750-hour test on material simulating a PCB- and Uranium-contaminated solid waste found at the Portsmouth Gaseous Diffusion Plant. The test results indicated essentially total (> 99.9999%) destruction of RCRA and TSCA hazardous halogenated organics, significant levels of volume reduction (> 400 to 1), and retention of radionuclides in the volume-reduced solids. Economic evaluations have shown the steam-reforming system to be very cost competitive with more conventional and other emerging technologies.

  4. Hanford low-level waste process chemistry testing data package

    SciTech Connect

    Smith, H.D.; Tracey, E.M.; Darab, J.G.; Smith, P.A.

    1996-03-01

    Recently, the Tri-Party Agreement (TPA) among the State of Washington Department of Ecology, U.S. Department of Energy (DOE) and the US Environmental Protection Agency (EPA) for the cleanup of the Hanford Site was renegotiated. The revised agreement specifies vitrification as the encapsulation technology for low level waste (LLW). A demonstration, testing, and evaluation program underway at Westinghouse Hanford Company to identify the best overall melter-system technology available for vitrification of Hanford Site LLW to meet the TPA milestones. Phase I is a {open_quotes}proof of principle{close_quotes} test to demonstrate that a melter system can process a simulated highly alkaline, high nitrate/nitrite content aqueous LLW feed into a glass product of consistent quality. Seven melter vendors were selected for the Phase I evaluation: joule-heated melters from GTS Duratek, Incorporated (GDI); Envitco, Incorporated (EVI); Penberthy Electomelt, Incorporated (PEI); and Vectra Technologies, Incorporated (VTI); a gas-fired cyclone burner from Babcock & Wilcox (BCW); a plasma torch-fired, cupola furnace from Westinghouse Science and Technology Center (WSTC); and an electric arc furnace with top-entering vertical carbon electrodes from the U.S. Bureau of Mines (USBM).

  5. An update of a national database of low-level radioactive waste in Canada

    SciTech Connect

    De, P.L.; Barker, R.C.

    1993-03-01

    This paper gives an overview and update of a national database of low-level radioactive waste in Canada. To provide a relevant perspective, Canadian data are compared with US data on annual waste arisings and with disposal initiatives of the US compacts and states. Presented also is an assessment of the data and its implications for disposal solutions in Canada.

  6. Directions in low-level radioactive waste management: A brief history of commercial low-level radioactive waste disposal

    SciTech Connect

    Not Available

    1990-10-01

    This report presents a history of commercial low-level radioactive waste management in the United States, with emphasis on the history of six commercially operated low-level radioactive waste disposal facilities. The report includes a brief description of important steps that have been taken during the 1980s to ensure the safe disposal of low-level waste in the 1990s and beyond. These steps include the issuance of Title 10 Code of Federal Regulations Part 61, Licensing Requirements for the Land Disposal of Radioactive Waste, the Low-Level Radioactive Waste Policy Act of 1980, the Low-Level Radioactive Waste Policy Amendments Act of 1985, and steps taken by states and regional compacts to establish additional disposal sites. 42 refs., 13 figs., 1 tab.

  7. Mixed and Low-Level Treatment Facility Project

    SciTech Connect

    Not Available

    1992-04-01

    This appendix contains the mixed and low-level waste engineering design files (EDFS) documenting each low-level and mixed waste stream investigated during preengineering studies for Mixed and Low-Level Waste Treatment Facility Project. The EDFs provide background information on mixed and low-level waste generated at the Idaho National Engineering Laboratory. They identify, characterize, and provide treatment strategies for the waste streams. Mixed waste is waste containing both radioactive and hazardous components as defined by the Atomic Energy Act and the Resource Conservation and Recovery Act, respectively. Low-level waste is waste that contains radioactivity and is not classified as high-level waste, transuranic waste, spent nuclear fuel, or 11e(2) byproduct material as defined by DOE 5820.2A. Test specimens of fissionable material irradiated for research and development only, and not for the production of power or plutonium, may be classified as low-level waste, provided the concentration of transuranic is less than 100 nCi/g. This appendix is a tool that clarifies presentation format for the EDFS. The EDFs contain waste stream characterization data and potential treatment strategies that will facilitate system tradeoff studies and conceptual design development. A total of 43 mixed waste and 55 low-level waste EDFs are provided.

  8. In vitro transdentinal effect of low-level laser therapy

    NASA Astrophysics Data System (ADS)

    Oliveira, C. F.; Basso, F. G.; dos Reis, R. I.; Parreiras-e-Silva, L. T.; Lins, E. C.; Kurachi, C.; Hebling, J.; Bagnato, V. S.; de Souza Costa, C. A.

    2013-05-01

    Low-level laser therapy (LLLT) has been used for the treatment of dentinal hypersensitivity. However, the specific LLL dose and the response mechanisms of these cells to transdentinal irradiation have not yet been demonstrated. Therefore, this study evaluated the transdentinal effects of different LLL doses on stressed odontoblast-like pulp cells MDPC-23 seeded onto the pulpal side of dentin discs obtained from human third molars. The discs were placed in devices simulating in vitro pulp chambers and the whole set was placed in 24-well plates containing plain culture medium (DMEM). After 24 h incubation, the culture medium was replaced by fresh DMEM supplemented with either 5% (simulating a nutritional stress condition) or 10% fetal bovine serum (FBS). The cells were irradiated with doses of 15 and 25 J cm-2 every 24 h, totaling three applications over three consecutive days. The cells in the control groups were removed from the incubator for the same times as used in their respective experimental groups for irradiation, though without activating the laser source (sham irradiation). After 72 h of the last active or sham irradiation, the cells were evaluated with respect to succinic dehydrogenase (SDH) enzyme production (MTT assay), total protein (TP) expression, alkaline phosphatase (ALP) synthesis, reverse transcriptase polymerase chain reaction (RT-PCR) for collagen type 1 (Col-I) and ALP, and morphology (SEM). For both tests, significantly higher values were obtained for the 25 J cm-2 dose. Regarding SDH production, supplementation of the culture medium with 5% FBS provided better results. For TP and ALP expression, the 25 J cm-2 presented higher values, especially for the 5% FBS concentration (Mann-Whitney p < 0.05). Under the tested conditions, near infrared laser irradiation at 25 J cm-2 caused transdentinal biostimulation of odontoblast-like MDPC-23 cells.

  9. Hanford low-level tank waste interim performance assessment

    SciTech Connect

    Mann, F.M.

    1996-09-16

    The Hanford Low-Level Tank Waste Interim Performance Assessment examines the long-term environmental and human health effects associated with the disposal of the low-level fraction of the Hanford single- and double-shell tank waste in the Hanford Site 200 East Area. This report was prepared as a good management practice to provide needed information about the relationship between the disposal system design and its performance as early as possible in the project cycle. The calculations in this performance assessment show that the disposal of the low-level fraction can meet environmental and health performance objectives.

  10. Hanford low-level tank waste interim performance assessment

    SciTech Connect

    Mann, F.M.

    1997-09-12

    The Hanford Low-Level Tank Waste Interim Performance Assessment examines the long-term environmental and human health effects associated with the disposal of the low-level fraction of the Hanford single and double-shell tank waste in the Hanford Site 200 East Area. This report was prepared as a good management practice to provide needed information about the relationship between the disposal system design and performance early in the disposal system project cycle. The calculations in this performance assessment show that the disposal of the low-level fraction can meet environmental and health performance objectives.

  11. Slag cement-low level radioactive waste forms at Savannah River Plant

    SciTech Connect

    Malek, R.I.A.; Roy, D.M.; Langton, C.A.

    1986-12-01

    A hydrated ceramic waste form, ''salt-stone,'' was designed for solidification and stabilization of Savannah River Plant (SRP) low level radioactive defense waste. This waste is a concentrated salt solution containing mainly sodium nitrate, nitrite, aluminate, sulfate, and hydroxide and has radioactivity. Ground, granulated blast furnace slag (a byproduct from the steel industry) was identified as a potential hydraulic ingredient for saltstone since its reactivity was found to be enhanced by the high alkalinity of the waste solution.

  12. Policy analysis of the low-level radioactive waste-disposal problem in the United States

    SciTech Connect

    Maloney, S.; Sterman, J.D.

    1982-05-01

    Federal policy governing the control of low-level radioactive waste resulting from commercial nuclear reactor operations is currently undergoing development. A simulation model examines the effects of various options, including volume reduction, local waste-disposal limits, the use of the U. S. Department of Energy sites, and expedited licensing of disposal sites.

  13. An Ultrascalable Solution to Large-scale Neural Tissue Simulation

    PubMed Central

    Kozloski, James; Wagner, John

    2011-01-01

    Neural tissue simulation extends requirements and constraints of previous neuronal and neural circuit simulation methods, creating a tissue coordinate system. We have developed a novel tissue volume decomposition, and a hybrid branched cable equation solver. The decomposition divides the simulation into regular tissue blocks and distributes them on a parallel multithreaded machine. The solver computes neurons that have been divided arbitrarily across blocks. We demonstrate thread, strong, and weak scaling of our approach on a machine with more than 4000 nodes and up to four threads per node. Scaling synapses to physiological numbers had little effect on performance, since our decomposition approach generates synapses that are almost always computed locally. The largest simulation included in our scaling results comprised 1 million neurons, 1 billion compartments, and 10 billion conductance-based synapses and gap junctions. We discuss the implications of our ultrascalable Neural Tissue Simulator, and with our results estimate requirements for a simulation at the scale of a human brain. PMID:21954383

  14. An Ultrascalable Solution to Large-scale Neural Tissue Simulation.

    PubMed

    Kozloski, James; Wagner, John

    2011-01-01

    Neural tissue simulation extends requirements and constraints of previous neuronal and neural circuit simulation methods, creating a tissue coordinate system. We have developed a novel tissue volume decomposition, and a hybrid branched cable equation solver. The decomposition divides the simulation into regular tissue blocks and distributes them on a parallel multithreaded machine. The solver computes neurons that have been divided arbitrarily across blocks. We demonstrate thread, strong, and weak scaling of our approach on a machine with more than 4000 nodes and up to four threads per node. Scaling synapses to physiological numbers had little effect on performance, since our decomposition approach generates synapses that are almost always computed locally. The largest simulation included in our scaling results comprised 1 million neurons, 1 billion compartments, and 10 billion conductance-based synapses and gap junctions. We discuss the implications of our ultrascalable Neural Tissue Simulator, and with our results estimate requirements for a simulation at the scale of a human brain. PMID:21954383

  15. Bibliographic Data on Low-Level Radioactive Waste Documents

    Energy Science and Technology Software Center (ESTSC)

    1995-11-10

    The purpose of the system is to allow users (researchers, policy makers, etc) to identify existing documents on a range of subjects related to low-level radioactive waste management. The software is menu driven.

  16. Mixed Low-Level Radioactive Waste (MLLW) Primer

    SciTech Connect

    W. E. Schwinkendorf

    1999-04-01

    This document presents a general overview of mixed low-level waste, including the regulatory definitions and drivers, the manner in which the various kinds of mixed waste are regulated, and a discussion of the waste treatment options.

  17. Radiation-induced response of operational amplifiers in low-level transient radiation environments

    SciTech Connect

    Paulos, J.J.; Bishop, R.J.; Turflinger, T.L.

    1987-12-01

    Extensive computer simulations have been performed on CMOS and bipolar operational amplifiers in an attempt to obtain a better understanding of low-level transient radiation response mechanisms. The simulation methodology has been confirmed using flash X-ray data for the amplifiers studied. Variations in circuit response to loading and feedback configuration have been explored, and several generalizations can be made which may provide a useful basis for a specification methodology.

  18. Sulfur polymer cement as a low-level waste glass matrix encapsulant

    SciTech Connect

    Sliva, P.; Peng, Y.B.; Peeler, D.K.

    1996-01-01

    Sulfur polymer cement (SPC) is being considered as a matrix encapsulant for the Hanford low-level (activity) waste glass. SPC is an elemental sulfur polymer-stabilized thermoplastic that is fluid at 120 {degrees}C to 140{degrees}C. The candidate process would encapsulate the waste glass by mixing the glass cullet with the SPC and casting it into the container. As the primary barrier to groundwater and a key factor in controlling the local environment of the disposal system after it has been compromised, SPC plays a key role in the waste form`s long-term performance assessment. Work in fiscal year 1995 targeted several technical areas of matrix encapsulation involving SPC. A literature review was performed to evaluate potential matrix-encapsulant materials. The dissolution and corrosion behavior of SPC under static conditions was determined as a function of temperature, pH, and sample surface area/solution volume. Preliminary dynamic flow-through testing was performed. SPC formulation and properties were investigated, including controlled crystallization, phase formation, modifying polymer effects on crystallization, and SPC processibility. The interface between SPC and simulated LLW glass was examined. Interfacial chemistry and stability, the effect of water on the glass/SPC interface, and the effect of molten sulfur on the glass surface chemistry were established. Preliminary scoping experiments, involving SPC`s Tc gettering capabilities were performed. Compressive strengths of SPC and SPC/glass composites, both before and after lifetime radiation dose exposure, were determined.

  19. An adaptive nonlinear solution scheme for reservoir simulation

    SciTech Connect

    Lett, G.S.

    1996-12-31

    Numerical reservoir simulation involves solving large, nonlinear systems of PDE with strongly discontinuous coefficients. Because of the large demands on computer memory and CPU, most users must perform simulations on very coarse grids. The average properties of the fluids and rocks must be estimated on these grids. These coarse grid {open_quotes}effective{close_quotes} properties are costly to determine, and risky to use, since their optimal values depend on the fluid flow being simulated. Thus, they must be found by trial-and-error techniques, and the more coarse the grid, the poorer the results. This paper describes a numerical reservoir simulator which accepts fine scale properties and automatically generates multiple levels of coarse grid rock and fluid properties. The fine grid properties and the coarse grid simulation results are used to estimate discretization errors with multilevel error expansions. These expansions are local, and identify areas requiring local grid refinement. These refinements are added adoptively by the simulator, and the resulting composite grid equations are solved by a nonlinear Fast Adaptive Composite (FAC) Grid method, with a damped Newton algorithm being used on each local grid. The nonsymmetric linear system of equations resulting from Newton`s method are in turn solved by a preconditioned Conjugate Gradients-like algorithm. The scheme is demonstrated by performing fine and coarse grid simulations of several multiphase reservoirs from around the world.

  20. ISOPAR L Release Rates from Saltstone Using Simulated Salt Solutions

    SciTech Connect

    Bronikowski, M

    2006-02-06

    The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) and the Salt Waste Processing Facility (SWPF) will produce a Deactivated Salt Solution (DSS) that will go to the Saltstone Production Facility (SPF). Recent information indicates that solvent entrainment in the DSS is larger than expected. The main concern is with Isopar{reg_sign} L, the diluent in the solvent mixture, and its flammability in the saltstone vault. If it is assumed that all the Isopar{reg_sign} L is released instantaneously into the vault from the curing grout before each subsequent pour; the Isopar{reg_sign} L in the vault headspace is well mixed; and each pour displaces an equivalent volume of headspace, the allowable concentration of Isopar{reg_sign} L in the DSS sent to SPF has been calculated at approximately 4 ppm. The amount allowed would be higher, if the release from grout were significantly less. The Savannah River National Laboratory was tasked with determining the release of Isopar{reg_sign} L from saltstone prepared with a simulated DSS with Isopar{reg_sign} L concentrations ranging from 50 mg/L to 200 mg/L in the salt fraction and with test temperatures ranging from ambient to 95 C. The results from the curing of the saltstone showed that the Isopar{reg_sign} L release data can be treated as a percentage of initial concentration in the concentration range studied. The majority of the Isopar{reg_sign} L that was released over the test duration was released in the first few days. The release of Isopar{reg_sign} L begins immediately and the rate of release decreases over time. At higher temperatures the immediate release is larger than at lower temperatures. In one test at 95 C essentially all of the Isopar{reg_sign} L was released in three months. Initial curing temperature was found to be very important as slight variations during the first few days affected the final Isopar{reg_sign} L amount released. Short scoping tests at 95 C with solvent containing all components (Isopar

  1. ISOPAR L RELEASE RATES FROM SALTSTONE USING SIMULATED SALT SOLUTIONS

    SciTech Connect

    Zamecnik, J; Michael Bronikowski, M; Alex Cozzi, A; Russell Eibling, R; Charles Nash, C

    2008-07-31

    The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) and the Salt Waste Processing Facility (SWPF) will produce a Decontaminated Salt Solution (DSS) that will go to the Saltstone Production Facility (SPF). Recent information indicates that solvent entrainment in the DSS is larger than expected. The main concern is with Isopar{reg_sign} L, the diluent in the solvent mixture, and its flammability in the saltstone vault. If it is assumed that all the Isopar{reg_sign} L is released instantaneously into the vault from the curing grout before each subsequent pour, the Isopar{reg_sign} L in the vault headspace is well mixed, and each pour displaces an equivalent volume of headspace, the maximum concentration of Isopar{reg_sign} L in the DSS to assure 25% of the lower flammable limit is not exceeded has been determined to be about 4 ppm. The amount allowed would be higher if the release from grout were significantly less. The Savannah River National Laboratory was tasked with determining the release of Isopar{reg_sign} L from saltstone prepared with a simulated DSS with Isopar{reg_sign} L concentrations ranging from 50 to 200 mg/L in the salt fraction and with test temperatures ranging from ambient to 95 C. The results from the curing of the saltstone showed that the amount of Isopar{reg_sign} L released versus time can be treated as a percentage of initial amount present; there was no statistically significant dependence of the release rate on the initial concentration. The majority of the Isopar{reg_sign} L that was released over the test duration was released in the first few days. The release of Isopar{reg_sign} L begins immediately and the rate of release decreases over time. At higher temperatures the immediate release rate is larger than at lower temperatures. Initial curing temperature was found to be very important as slight variations during the first few hours or days had a significant effect on the amount of Isopar{reg_sign} L released. Short scoping

  2. Low-level radioactive waste regulation: Science, politics and fear

    SciTech Connect

    Burns, M.E.

    1988-01-01

    An inevitable consequence of the use of radioactive materials is the generation of radioactive wastes and the public policy debate over how they will be managed. In 1980, Congress shifted responsibility for the disposal of low-level radioactive wastes from the federal government to the states. This act represented a sharp departure from more than 30 years of virtually absolute federal control over radioactive materials. Though this plan had the enthusiastic support of the states in 1980, it now appears to have been at best a chimera. Radioactive waste management has become an increasingly complicated and controversial issue for society in recent years. This book discusses only low-level wastes, however, because Congress decided for political reasons to treat them differently than high-level wastes. The book is based in part on three symposia sponsored by the division of Chemistry and the Law of the American Chemical Society. Each chapter is derived in full or in part from presentations made at these meetings, and includes: (1) Low-level radioactive wastes in the nuclear power industry; (2) Low-level radiation cancer risk assessment and government regulation to protect public health; and (3) Low-level radioactive waste: can new disposal sites be found.

  3. Classroom Simulation of Small-Scale Solutional Landforms.

    ERIC Educational Resources Information Center

    Brook, George A.; Luft, Edward R.

    1988-01-01

    Describes a model for generating solution features, or karren, on gypsum blocks within 24-48 hours in order to illustrate terrain-forming processes. This method for replicating landforms provides hands-on experience for students, and can be varied to demonstrate a number of principles. (LS)

  4. Commission operation. National Low-Level Radioactive Waste Management Program

    NASA Astrophysics Data System (ADS)

    1984-09-01

    Since Congress enacted the Low-Level Radioactive Waste Policy Act, the states have prepared to meet their responsibilities for management of low-level radioactive waste by entering into regional compacts. This option document is intended to provide a framework for the operation of a compact commission formed as the governing body of a low-level radioactive waste compact. The document is designed to be easily modified to meet the needs of various regional compacts. The ideas and format presented were taken in general from the Federal Administrative procedures Act, various state administrative procedures, and the state regulatory agencies' rules of procedure. Requirements of filing, time frames, and standard language are written from a legal perspective.

  5. Low Level Laser Therapy: A Panacea for oral maladies

    PubMed Central

    Kathuria, Vartika; Kalra, Gauri

    2015-01-01

    Aim: To review the applications of low level laser therapy on various soft and hard oral tissues. A variety of therapeutic effects of Low Level Laser Therapy have been reported on a broad range of disorders. It has been found amenably practical in dental applications including soft as well as hard tissues of the oral cavity. LLLT has been found to be efficient in acceleration of wound healing, enhanced remodelling and bone repair, regeneration of neural cells following injury, pain attenuation, endorphin release stimulation and modulation of immune system. The aforementioned biological processes induced by Low level lasers have been effectively applied in treating various pathological conditions in the oral cavity. With is article, we attempt to review the possible application of Low Laser Therapy in the field of dentistry. PMID:26557737

  6. Remote-Handled Low Level Waste Disposal Project Alternatives Analysis

    SciTech Connect

    David Duncan

    2010-10-01

    This report identifies, evaluates, and compares alternatives for meeting the U.S. Department of Energy’s mission need for management of remote-handled low-level waste generated by the Idaho National Laboratory and its tenants. Each alternative identified in the Mission Need Statement for the Remote-Handled Low-Level Waste Treatment Project is described and evaluated for capability to fulfill the mission need. Alternatives that could meet the mission need are further evaluated and compared using criteria of cost, risk, complexity, stakeholder values, and regulatory compliance. The alternative for disposal of remote-handled low-level waste that has the highest confidence of meeting the mission need and represents best value to the government is to build a new disposal facility at the Idaho National Laboratory Site.

  7. The APOSTLE simulations: solutions to the Local Group's cosmic puzzles

    NASA Astrophysics Data System (ADS)

    Sawala, Till; Frenk, Carlos S.; Fattahi, Azadeh; Navarro, Julio F.; Bower, Richard G.; Crain, Robert A.; Dalla Vecchia, Claudio; Furlong, Michelle; Helly, John. C.; Jenkins, Adrian; Oman, Kyle A.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom; Trayford, James; White, Simon D. M.

    2016-04-01

    The Local Group galaxies offer some of the most discriminating tests of models of cosmic structure formation. For example, observations of the Milky Way (MW) and Andromeda satellite populations appear to be in disagreement with N-body simulations of the `lambda cold dark matter' (ΛCDM) model: there are far fewer satellite galaxies than substructures in CDM haloes (the `missing satellites' problem); dwarf galaxies seem to avoid the most massive substructures (the `too-big-to-fail' problem); and the brightest satellites appear to orbit their host galaxies on a thin plane (the `planes of satellites' problem). Here we present results from APOSTLE (A Project Of Simulating The Local Environment), a suite of cosmological hydrodynamic simulations of 12 volumes selected to match the kinematics of the Local Group (LG) members. Applying the EAGLE code to the LG environment, we find that our simulations match the observed abundance of LG galaxies, including the satellite galaxies of the MW and Andromeda. Due to changes to the structure of haloes and the evolution in the LG environment, the simulations reproduce the observed relation between stellar mass and velocity dispersion of individual dwarf spheroidal galaxies without necessitating the formation of cores in their dark matter profiles. Satellite systems form with a range of spatial anisotropies, including one similar to the MWs, confirming that such a configuration is not unexpected in ΛCDM. Finally, based on the observed velocity dispersion, size, and stellar mass, we provide estimates of the maximum circular velocity for the haloes of nine MW dwarf spheroidals.

  8. A robotic inspector for low-level radioactive waste

    SciTech Connect

    Byrd, J.S.; Pettus, R.O.

    1996-06-01

    The Department of Energy has low-level radioactive waste stored in warehouses at several facilities. Weekly visual inspections are required. A mobile robot inspection system, ARIES (Autonomous Robotic Inspection Experimental System), has been developed to survey and inspect the stored drums. The robot will travel through the three- foot wide aisles of drums stacked four high and perform a visual inspection, normally performed by a human operator, making decisions about the condition of the drums and maintaining a database of pertinent information about each drum. This mobile robot system will improve the quality of inspection, generate required reports, and relieve human operators from low-level radioactive exposure.

  9. Modeling and low-level waste management: an interagency workshop

    SciTech Connect

    Little, C.A.; Stratton, L.E.

    1980-01-01

    The interagency workshop on Modeling and Low-Level Waste Management was held on December 1-4, 1980 in Denver, Colorado. Twenty papers were presented at this meeting which consisted of three sessions. First, each agency presented its point of view concerning modeling and the need for models in low-level radioactive waste applications. Second, a larger group of more technical papers was presented by persons actively involved in model development or applications. Last of all, four workshops were held to attempt to reach a consensus among participants regarding numerous waste modeling topics. Abstracts are provided for the papers presented at this workshop.

  10. Immobilized low-level waste disposal options configuration study

    SciTech Connect

    Mitchell, D.E.

    1995-02-01

    This report compiles information that supports the eventual conceptual and definitive design of a disposal facility for immobilized low-level waste. The report includes the results of a joint Westinghouse/Fluor Daniel Inc. evaluation of trade-offs for glass manufacturing and product (waste form) disposal. Though recommendations for the preferred manufacturing and disposal option for low-level waste are outside the scope of this document, relative ranking as applied to facility complexity, safety, remote operation concepts and ease of retrieval are addressed.

  11. GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

    SciTech Connect

    Winn, W.G.

    1999-07-28

    The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.

  12. Verification of particle-in-cell simulations against exact solutions of kinetic equations

    NASA Astrophysics Data System (ADS)

    Turner, Miles

    2015-09-01

    Demonstrating correctness of computer simulations (or verification) has become a matter of increasing concern in recent years. The strongest type of verification is a demonstration that the simulation converges to an exact solution of the mathematical model that is supposed to be solved. Of course, this is possible only if such an exact solution is available. In this paper, we are interested in kinetic simulation using the particle-in-cell method, and consequently a relevant exact solution must be a solution of a kinetic equation. While we know of no such solutions that exercise all the features of a typical particle-in-cell simulation, in this paper we show that the mathematical literature contains several such solutions that involve a large fraction of the functionality of such a code, and which collectively exercise essentially all of the code functionality. These solutions include the plane diode, the neutron criticality problem, and the calculation of ion energy distribution functions in oscillating fields. In each of theses cases, we can show the the particle-in-cell simulation converges to the exact solution in the expected way. These demonstrations are strong evidence of correct implementation. Work supported by Science Foundation Ireland under grant 08/SRC/I1411.

  13. A preliminary evaluation of alternatives for disposal of INEL low-level waste and low-level mixed waste

    SciTech Connect

    Smith, T.H.; Roesener, W.S.; Jorgenson-Waters, M.J.

    1993-07-01

    The Mixed and Low-Level Waste Disposal Facility (MLLWDF) project was established in 1992 by the US Department of Energy Idaho Operations Office to provide enhanced disposal capabilities for Idaho National Engineering Laboratory (INEL) low-level mixed waste and low-level waste. This Preliminary Evaluation of Alternatives for Disposal of INEL Low-Level Waste and Low-Level Mixed Waste identifies and evaluates-on a preliminary, overview basis-the alternatives for disposal of that waste. Five disposal alternatives, ranging from of no-action`` to constructing and operating the MLLWDF, are identified and evaluated. Several subalternatives are formulated within the MLLWDF alternative. The subalternatives involve various disposal technologies as well as various scenarios related to the waste volumes and waste forms to be received for disposal. The evaluations include qualitative comparisons of the projected isolation performance for each alternative, and facility, health and safety, environmental, institutional, schedule, and rough order-of-magnitude life-cycle cost comparisons. The performance of each alternative is evaluated against lists of ``musts`` and ``wants.`` Also included is a discussion of other key considerations for decisionmaking. The analysis of results indicated further study is necessary to obtain the best estimate of long-term future waste volume and characteristics from the INEL Environmental Restoration activities and the expanded INEL Decontamination and Decommissioning Program.

  14. Transportation and disposal configuration for DOE-managed low-level and mixed low-level waste

    SciTech Connect

    Johnsen, T.

    1993-06-01

    This report briefly examines the current U.S. Department of Energy complex-wide configuration for transportation and disposal of low-level and mixed low-level waste, and also retraces the historical sequence of events and rationale that has guided its development. The study determined that Nevada Test Site and the Hanford Site are the only two sites that currently provide substantial disposal services for offsite low-level waste generators. It was also determined that mixed low-level waste shipments are infrequent and are generally limited to shipments to offsite commercial treatment facilities or other Department of Energy sites for storage. The current alignment of generator to disposal site for low-level waste shipments is generally consistent with the programmatic mission of the generator; that is, defense-generated waste is shipped to the Nevada Test Site and research-generated waste is transported to the Hanford Site. The historical development of the current configuration was resurrected by retrieving Department of Energy documentation and interviewing both current and former department and contractor personnel. According to several accounts, the basic framework of the system was developed during the late 1970s, and was reportedly based on the ability of the disposal site to manage a given waste form. Documented evidence to support this reasoning, however, could not be uncovered.

  15. Numerical solutions of atmospheric flow over semielliptical simulated hills

    NASA Technical Reports Server (NTRS)

    Shieh, C. F.; Frost, W.

    1981-01-01

    Atmospheric motion over obstacles on plane surfaces to compute simulated wind fields over terrain features was studied. Semielliptical, two dimensional geometry and numerical simulation of flow over rectangular geometries is also discussed. The partial differential equations for the vorticity, stream function, turbulence kinetic energy, and turbulence length scale were solved by a finite difference technique. The mechanism of flow separation induced by a semiellipse is the same as flow over a gradually sloping surface for which the flow separation is caused by the interaction between the viscous force, the pressure force, and the turbulence level. For flow over bluff bodies, a downstream recirculation bubble is created which increases the aspect ratio and/or the turbulence level results in flow reattachment close behind the obstacle.

  16. Computer Simulation of Ligated Nanoparticle Assembly from Solution

    NASA Astrophysics Data System (ADS)

    Pierce, Flint; Chakrabarti, Amit; Sorensen, Chris

    2007-03-01

    Nanoparticles are becoming increasingly important for the design of novel materials in a wide range of new applications. Ligation of these particles by chemical species provides a means to stabilize them into useful assemblies. It is essential to have a clear physical picture of the way these particles interact. To this end, we are investigating systems of metal nanoparticles ligated with alkyl chains. Our approach is three-fold. First, we are simulating (Monte Carlo) systems of ligated nanoparticles, including all chain/particle interactions in order to develop a model potential. Second, we are simulating (molecular dynamics) systems of these particles interacting via this model potential, varying the alkyl chain length, solvent, core material, and particle volume fraction. Finally, for comparison we are simulating these systems using theoretically derived potentials found in the literature. Initial results indicate a range of morphologies, from fractal aggregates to crystallites, depending on the temperature and potentials involved. Our goal is to provide a guide to researchers in choosing materials and assembly conditions that will lead to desired assembly properties.

  17. Dynamics of the Iberian Peninsula Coastal Low-Level Jet

    NASA Astrophysics Data System (ADS)

    Semedo, Alvaro; Rijo, Nádia; Miranda, Pedro; Lima, Daniela C. A.; Cardoso, Rita; Soares, Pedro

    2016-04-01

    Coastal low-level jets (CLLJ) are important mesoscale phenomena of some regional coastal climates. They are characterized by a coast-parallel flow which has a wind speed maxima within the first few hundred meters above sea level (usually below 1000 m, and most of the times around 500 m), encapsulated within the marine atmospheric boundary layer (MABL). Coastal jets have a larger scale synoptic forcing behind them: a high pressure system over the ocean and a thermal low inland. The regions where CLLJ occur coincide with cold equator-ward eastern boundary currents in the mid-latitudes (with an exception of the coast of Oman in the Arabian Sea), where the contrast between the cold ocean and the warm land in the summer is highest. As a response of CLLJ occurrences a positive feedback mechanism is triggered: the coast-parallel wind induces upwelling currents at the coast, reducing the sea surface temperature, which in turn increase the thermal (pressure) gradient at the coast, leading to higher wind speeds. The Iberian Peninsula Coastal Jet (IPCJ) is an example of a CLLJ, developed mostly during the summer season due to the effect of the semi-present Azores high-pressure system in the North Atlantic and of a thermal low pressure system inland. This synoptic pattern drives a seasonal (western) coast parallel wind, often called the Nortada (northerly wind), where the IPCJ develops. A detailed analysis of the IPCJ structure and dynamics will be presented, trough the analysis of two case studies off the west coast of Portugal. The case studies are simulated using the WRF mesoscale model, at 9 and 3 km horizontal resolution, forced by the ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-Interim reanalysis. The MABL structure off the west coast of Iberia, the interaction of the flow with the two main west Iberia capes (Finisterre and Roca), and the consequences on the cloud cover and wind speed up- and down-wind of the capes will be analysed.

  18. Low-level radioactive waste disposal facility closure

    SciTech Connect

    White, G.J.; Ferns, T.W.; Otis, M.D.; Marts, S.T.; DeHaan, M.S.; Schwaller, R.G.; White, G.J. )

    1990-11-01

    Part I of this report describes and evaluates potential impacts associated with changes in environmental conditions on a low-level radioactive waste disposal site over a long period of time. Ecological processes are discussed and baselines are established consistent with their potential for causing a significant impact to low-level radioactive waste facility. A variety of factors that might disrupt or act on long-term predictions are evaluated including biological, chemical, and physical phenomena of both natural and anthropogenic origin. These factors are then applied to six existing, yet very different, low-level radioactive waste sites. A summary and recommendations for future site characterization and monitoring activities is given for application to potential and existing sites. Part II of this report contains guidance on the design and implementation of a performance monitoring program for low-level radioactive waste disposal facilities. A monitoring programs is described that will assess whether engineered barriers surrounding the waste are effectively isolating the waste and will continue to isolate the waste by remaining structurally stable. Monitoring techniques and instruments are discussed relative to their ability to measure (a) parameters directly related to water movement though engineered barriers, (b) parameters directly related to the structural stability of engineered barriers, and (c) parameters that characterize external or internal conditions that may cause physical changes leading to enhanced water movement or compromises in stability. Data interpretation leading to decisions concerning facility closure is discussed. 120 refs., 12 figs., 17 tabs.

  19. 77 FR 26991 - Low-Level Radioactive Waste Management Issues

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-08

    ... Volume Reduction and Low-Level Radioactive Waste Management'' (76 FR 50500; August 15, 2011); and the... regulations were published in the Federal Register on December 27, 1982 (47 FR 57446). The rule applies to any... (74 FR 30175; Docket ID NRC-2009-0257), the NRC staff subsequently developed a technical...

  20. Mixed and Low-Level Waste Treatment Facility project

    SciTech Connect

    Not Available

    1992-04-01

    Mixed and low-level wastes generated at the Idaho National Engineering Laboratory (INEL) are required to be managed according to applicable State and Federal regulations, and Department of Energy Orders that provide for the protection of human health and the environment. The Mixed and Low-Level Waste Treatment Facility Project was chartered in 1991, by the Department of Energy to provide treatment capability for these mixed and low-level waste streams. The first project task consisted of conducting engineering studies to identify the waste streams, their potential treatment strategies, and the requirements that would be imposed on the waste streams and the facilities used to process them. The engineering studies, initiated in July 1991, identified 37 mixed waste streams, and 55 low-level waste streams. This report documents the waste stream information and potential treatment strategies, as well as the regulatory requirements for the Department of Energy-owned treatment facility option. The total report comprises three volumes and two appendices. This report consists of Volume 1, which explains the overall program mission, the guiding assumptions for the engineering studies, and summarizes the waste stream and regulatory information, and Volume 2, the Waste Stream Technical Summary which, encompasses the studies conducted to identify the INEL's waste streams and their potential treatment strategies.

  1. Low-Level Waste Disposal Alternatives Analysis Report

    SciTech Connect

    Timothy Carlson; Kay Adler-Flitton; Roy Grant; Joan Connolly; Peggy Hinman; Charles Marcinkiewicz

    2006-09-01

    This report identifies and compares on-site and off-site disposal options for the disposal of contract-handled and remote-handled low-level waste generated by the Idaho National Laboratory and its tenants. Potential disposal options are screened for viability by waste type resulting in a short list of options for further consideration. The most crediable option are selected after systematic consideration of cost, schedule constraints, and risk. In order to holistically address the approach for low-level waste disposal, options are compiled into comprehensive disposal schemes, that is, alternative scenarios. Each alternative scenario addresses the disposal path for all low-level waste types over the period of interest. The alternative scenarios are compared and ranked using cost, risk and complexity to arrive at the recommended approach. Schedule alignment with disposal needs is addressed to ensure that all waste types are managed appropriately. The recommended alternative scenario for the disposal of low-level waste based on this analysis is to build a disposal facility at the Idaho National Laboratory Site.

  2. Teaching Low-Level Adult ESL Learners. ERIC Digest.

    ERIC Educational Resources Information Center

    Holt, Grace Massey

    In recent years, the English-as-a-Second-Language (ESL) teaching profession has made discoveries about teaching beginning or low-level adult learners (those with little or no schooling in their native languages, learners who may not be familiar with the Roman alphabet, those with learning disabilities, and those literate in their native languages…

  3. Effects of low levels of radiation on humans

    SciTech Connect

    Auxier, J.A.

    1981-01-01

    The state of knowledge on effects of low-level ionizing radiations on humans is reviewed. Several problems relating to dose thresholds or lack of thresholds for several types of cancer and high LET radiations and the effects of fractionation and dose protection are discussed. (ACR)

  4. Credit WCT. Photographic copy of photograph, low level aerial view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Photographic copy of photograph, low level aerial view of Test Stand "D," looking due west, after completion of Dd station installation in 1961. Note Test Stand "D" "neutralization pond" to immediate southeast of tower. (JPL negative no. 384-2997-B, 12 December 1961) - Jet Propulsion Laboratory Edwards Facility, Test Stand D, Edwards Air Force Base, Boron, Kern County, CA

  5. Environmentalism and low-level waste-the aftermath

    SciTech Connect

    Pastorelle, P.J.

    1995-05-01

    Radical Environmentalists, anxious to shut down nuclear power, are directing efforts against the disposal of low-level radioactive wastes (contaminated coveralls, tools, paper, plastic, glass, etc.). The rationals is that if nuclear power facilities cannot dispose of their waste streams, eventually they may have to stop operating. This article discusses the political and practical issues surrounding this approach.

  6. A Plane-Parallel Wind Solution for Testing Numerical Simulations of Photoevaporation

    NASA Astrophysics Data System (ADS)

    Hutchison, Mark A.; Laibe, Guillaume

    2016-04-01

    Here, we derive a Parker-wind-like solution for a stratified, plane-parallel atmosphere undergoing photoionisation. The difference compared to the standard Parker solar wind is that the sonic point is crossed only at infinity. The simplicity of the analytic solution makes it a convenient test problem for numerical simulations of photoevaporation in protoplanetary discs.

  7. Proteus aircraft low-level flyby at Las Cruces Airport.

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The unique Proteus aircraft served as a test bed for NASA-sponsored flight tests designed to validate collision-avoidance technologies proposed for uninhabited aircraft. The tests, flown over southern New Mexico in March, 2002, used the Proteus as a surrogate uninhabited aerial vehicle (UAV) while three other aircraft flew toward the Proteus from various angles on simulated collision courses. Radio-based 'detect, see and avoid' equipment on the Proteus successfully detected the other aircraft and relayed that information to a remote pilot on the ground at Las Cruces Airport. The pilot then transmitted commands to the Proteus to maneuver it away from the potential collisions. The flight demonstration, sponsored by NASA Dryden Flight Research Center, New Mexico State University, Scaled Composites, the U.S. Navy and Modern Technology Solutions, Inc., were intended to demonstrate that UAVs can be flown safely and compatibly in the same skies as piloted aircraft.

  8. Micellar crystals in solution from molecular dynamics simulations

    SciTech Connect

    Anderson, J.; Lorenz, C.; Travesset, A.

    2008-05-14

    Polymers with both soluble and insoluble blocks typically self-assemble into micelles, which are aggregates of a finite number of polymers where the soluble blocks shield the insoluble ones from contact with the solvent. Upon increasing concentration, these micelles often form gels that exhibit crystalline order in many systems. In this paper, we present a study of both the dynamics and the equilibrium properties of micellar crystals of triblock polymers using molecular dynamics simulations. Our results show that equilibration of single micelle degrees of freedom and crystal formation occur by polymer transfer between micelles, a process that is described by transition state theory. Near the disordered (or melting) transition, bcc lattices are favored for all triblocks studied. Lattices with fcc ordering are also found but only at lower kinetic temperatures and for triblocks with short hydrophilic blocks. Our results lead to a number of theoretical considerations and suggest a range of implications to experimental systems with a particular emphasis on Pluronic polymers.

  9. The capture of oxidized mercury from simulated desulphurization aqueous solutions.

    PubMed

    Ochoa-González, Raquel; Díaz-Somoano, Mercedes; Martínez-Tarazona, M Rosa

    2013-05-15

    Elemental mercury in flue gases from coal combustion is difficult to control. However, oxidized mercury species are soluble in water and can be removed with a high degree of efficiency in wet flue gas desulphurization (WFGD) systems operating in coal combustion plants, provided that no re-emissions occur. In this article the mechanisms affecting the re-emission of oxidized mercury species in WFGD conditions via sulphite ions are discussed. The parameters studied include the operating temperature, the pH, the redox potential, the concentrations of mercury and oxygen in the flue gas and the concentration of reductive ions in the solution. The results show that temperature, pH and the concentration of mercury at the inlet of the WFGD systems are the most important factors affecting oxidized mercury removal. The results indicate that sulphite ions, not only contribute to the reduction of Hg(2+), but that they may also stabilize the mercury in the liquid fraction of the WFGD limestone slurry. Consequently, factors that increase the sulphite content in the slurry such as a low oxygen concentration promote the co-capture of mercury with sulphur. PMID:23500649

  10. Simulating water, solute, and heat transport in the subsurface with the VS2DI software package

    USGS Publications Warehouse

    Healy, R.W.

    2008-01-01

    The software package VS2DI was developed by the U.S. Geological Survey for simulating water, solute, and heat transport in variably saturated porous media. The package consists of a graphical preprocessor to facilitate construction of a simulation, a postprocessor for visualizing simulation results, and two numerical models that solve for flow and solute transport (VS2DT) and flow and heat transport (VS2DH). The finite-difference method is used to solve the Richards equation for flow and the advection-dispersion equation for solute or heat transport. This study presents a brief description of the VS2DI package, an overview of the various types of problems that have been addressed with the package, and an analysis of the advantages and limitations of the package. A review of other models and modeling approaches for studying water, solute, and heat transport also is provided. ?? Soil Science Society of America. All rights reserved.

  11. Criticality safety considerations for low-level-waste facilities

    SciTech Connect

    Hopper, C.M.

    1995-04-01

    The nuclear criticality safety for handling and burial of certain special nuclear materials (SNM) at low-level-waste (LLW) facilities is licensed by the US Nuclear Regulatory Commission (NRC). Recently, Oak Ridge National Laboratory (ORNL) staff assisted the NRC Office of Nuclear Material Safety and Safeguards, Low-Level-Waste and Decommissioning Projects Branch, in developing technical specifications for the nuclear criticality safety of {sup 235}U and {sup 235}Pu in LLW facilities. This assistance resulted in a set of nuclear criticality safety criteria that can be uniformly applied to the review of LLW package burial facility license applications. These criteria were developed through the coupling of the historic surface-density criterion with current computational technique to establish safety criteria considering SNM material form and reflector influences. This paper presents a summary of the approach used to establish and to apply the criteria to the licensing review process.

  12. Low-level RF control for the AFEL

    SciTech Connect

    Ziomek, C.; Kinross-Wright, J.; Plato, J.

    1994-09-01

    A limiting factor in the performance of the Los Alamos Advanced Free Electron Laser (AFEL) is the stability of the RF accelerating field. A high-performance low-level RF control system has been implemented that uses analog feedback and digital feed forward to regulate the RF field. This low-level RF control system has achieved long-term amplitude and phase stabilities better than {+-}0.25% and {+-}0.33{degree} respectively. In order to improve the RF field stability further, a detailed system analysis and design is proceeding. Subsystem measurements are being used to model the system performance, predict the performance-limiting components, and determine possible improvements. Results to-date, modeling analyses, and suggested future improvements are presented.

  13. Automatic Measurement of Low Level Contamination on Concrete Surfaces

    SciTech Connect

    Tachibana, M.; Itoh, H.; Shimada, T.; Yanagihara, S.

    2002-02-28

    Automatic measurement of radioactivity is necessary for considering cost effectiveness in final radiological survey of building structures in decommissioning nuclear facilities. The RAPID (radiation measuring pilot device for surface contamination) was developed to be applied to automatic measurement of low level contamination on concrete surfaces. The RAPID has a capability to measure contamination with detection limit of 0.14 Bq/cm2 for 60Co in 30 seconds of measurement time and its efficiency is evaluated to be 5 m2/h in a normal measurement option. It was confirmed that low level contamination on concrete surfaces could be surveyed by the RAPID efficiently compared with direct measurement by workers through its actual application.

  14. National Low-Level Waste Management Program Radionuclide Report Series

    SciTech Connect

    J.P. Adams; M.L. Carboneau; W.E. Allred

    1999-02-01

    The National Low Level Waste Management Program at the Idaho National Engineering and Environmental Laboratory has published a report containing key information about selected radionuclides that are most likely to contribute significantly to the radiation exposures estimated from a performance assessment of a low-level radioactive waste (LLW) disposal facility. The information includes physical and chemical characteristics, production means, waste forms, behavior of the radionuclide in soils, plants, groundwater, and air, and biological effects in animals and humans. The radionuclides included in this study comprise all of the nuclides specifically listed in 10CFR61.55, Tables 1 and 2, 3 H, 14 C, 59 Ni, 60 Co, 63 Ni, 90 Sr, 94 Nb, 99 Tc, 129 I, 137 Cs, 241 Pu, and 242 Cm. Other key radionuclides addressed in the report include 237 Np, 238 U, 239 Pu, and 241 Am. This paper summarizes key information contained within this report.

  15. National Low-Level Waste Management Program Radionuclide Report Series

    SciTech Connect

    Adams, James Paul; Carboneau, Michael Leonard; Allred, William Edgar

    1999-03-01

    The National Low Level Waste Management Program at the Idaho National Engineering and Environmental Laboratory has published a report containing key information about selected radionuclides that are most likely to contribute significantly to the radiation exposures estimated from a performance assessment of a low-level radioactive waste (LLW) disposal facility. The information includes physical and chemical characteristics, production means, waste forms, behavior of the radionuclide in soils, plants, groundwater, and air, and biological effects in animals and humans. The radionuclides included in this study comprise all of the nuclides specifically listed in 10CFR61.55, Tables 1 and 2, 3 H, 14 C, 59 Ni, 60 Co, 63 Ni, 90 Sr, 94 Nb, 99 Tc, 129 I, 137 Cs, 241 Pu, and 242 Cm. Other key radionuclides addressed in the report include 237 Np, 238 U, 239 Pu, and 241 Am. This paper summarizes key information contained within this report.

  16. Low-level waste disposal in highly populated areas

    SciTech Connect

    Kowalski, E.; McCombie, C.; Issler, H.

    1989-11-01

    Nuclear-generated electricity supplies almost 40% of the demand in Switzerland (the rest being hydro-power). Allowing for a certain reserve and assuming an operational life-time of 40 years for each reactor, and taking into account wastes from decommissioning and from medicine, industry and research, the total amount of low-level radioactive waste to be disposed of is about 175,000 m{sup 3}. Since there are no unpopulated areas in Switzerland, and since Swiss Federal Law specifies that the safety of disposal may not depend upon supervision of the repository, no shallow-land burial has been foreseen, even for short-lived low-level waste. Instead, geological disposal in a mined cavern system with access through a horizontal tunnel was selected as the best way of meeting the requirements and ensuring the necessary public acceptance.

  17. Mixed and low-level waste treatment facility project

    SciTech Connect

    Not Available

    1992-04-01

    The technology information provided in this report is only the first step toward the identification and selection of process systems that may be recommended for a proposed mixed and low-level waste treatment facility. More specific information on each technology will be required to conduct the system and equipment tradeoff studies that will follow these preengineering studies. For example, capacity, maintainability, reliability, cost, applicability to specific waste streams, and technology availability must be further defined. This report does not currently contain all needed information; however, all major technologies considered to be potentially applicable to the treatment of mixed and low-level waste are identified and described herein. Future reports will seek to improve the depth of information on technologies.

  18. A model for a national low level waste program

    SciTech Connect

    Blankenhorn, James A

    2009-01-01

    A national program for the management of low level waste is essential to the success of environmental clean-up, decontamination and decommissioning, current operations and future missions. The value of a national program is recognized through procedural consistency and a shared set of resources. A national program requires a clear waste definition and an understanding of waste characteristics matched against available and proposed disposal options. A national program requires the development and implementation of standards and procedures for implementing the waste hierarchy, with a specitic emphasis on waste avoidance, minimization and recycling. It requires a common set of objectives for waste characterization based on the disposal facility's waste acceptance criteria, regulatory and license requirements and performance assessments. Finally, a national waste certification program is required to ensure compliance. To facilitate and enhance the national program, a centralized generator services organization, tasked with providing technical services to the generators on behalf of the national program, is necessary. These subject matter experts are the interface between the generating sites and the disposal facility(s). They provide an invaluable service to the generating organizations through their involvement in waste planning prior to waste generation and through championing implementation of the waste hierarchy. Through their interface, national treatment and transportation services are optimized and new business opportunities are identified. This national model is based on extensive experience in the development and on-going management of a national transuranic waste program and management of the national repository, the Waste Isolation Pilot Plant. The Low Level Program at the Savannah River Site also successfully developed and implemented the waste hierarchy, waste certification and waste generator services concepts presented below. The Savannah River Site

  19. Waste Management Facilities cost information for low-level waste

    SciTech Connect

    Shropshire, D.; Sherick, M.; Biadgi, C.

    1995-06-01

    This report contains preconceptual designs and planning level life-cycle cost estimates for managing low-level waste. The report`s information on treatment, storage, and disposal modules can be integrated to develop total life-cycle costs for various waste management options. A procedure to guide the US Department of Energy and its contractor personnel in the use of cost estimation data is also summarized in this report.

  20. Commercial low-level radioactive waste disposal in the US

    SciTech Connect

    Smith, P.

    1995-10-01

    Why are 11 states attempting to develop new low-level radioactive waste disposal facilities? Why is only on disposal facility accepting waste nationally? What is the future of waste disposal? These questions are representative of those being asked throughout the country. This paper attempts to answer these questions in terms of where we are, how we got there, and where we might be going.

  1. Forearm muscle oxygenation decreases with low levels of voluntary contraction

    NASA Technical Reports Server (NTRS)

    Murthy, G.; Kahan, N. J.; Hargens, A. R.; Rempel, D. M.

    1997-01-01

    The purpose of our investigation was to determine if the near infrared spectroscopy technique was sensitive to changes in tissue oxygenation at low levels of isometric contraction in the extensor carpi radialis brevis muscle. Nine subjects were seated with the right arm abducted to 45 degrees, elbow flexed to 85 degrees, forearm pronated 45 degrees, and wrist and forearm supported on an armrest throughout the protocol. Altered tissue oxygenation was measured noninvasively with near infrared spectroscopy. The near infrared spectroscopy probe was placed over the extensor carpi radialis brevis of the subject's right forearm and secured with an elastic wrap. After 1 minute of baseline measurements taken with the muscle relaxed, four different loads were applied just proximal to the metacarpophalangeal joint such that the subjects isometrically contracted the extensor carpi radialis brevis at 5, 10, 15, and 50% of the maximum voluntary contraction for 1 minute each. A 3-minute recovery period followed each level of contraction. At the end of the protocol, with the probe still in place, a value for ischemic tissue oxygenation was obtained for each subject. This value was considered the physiological zero and hence 0% tissue oxygenation. Mean tissue oxygenation (+/-SE) decreased from resting baseline (100% tissue oxygenation) to 89 +/- 4, 81 +/- 8, 78 +/- 8, and 47 +/- 8% at 5, 10, 15, and 50% of the maximum voluntary contraction, respectively. Tissue oxygenation levels at 10, 15, and 50% of the maximum voluntary contraction were significantly lower (p < 0.05) than the baseline value. Our results indicate that tissue oxygenation significantly decreases during brief, low levels of static muscle contraction and that near infrared spectroscopy is a sensitive technique for detecting deoxygenation noninvasively at low levels of forearm muscle contraction. Our findings have important implications in occupational medicine because oxygen depletion induced by low levels of muscle

  2. The Argonne low level /sup 14/C counting system

    SciTech Connect

    Gray, J.; Rymas, S.J.; Studebaker, L.D.; Yule, H.P.

    1987-01-01

    A low level /sup 14/CO/sub 2/ counting system is described. This system was used to process several thousand CO/sub 2/ samples derived from atmospheric collections at various altitudes. Special features include counter construction utilizing electrolytic copper and shielding with neutron moderating and absorbing paraffin containing sodium metaborate. The effect of steel shielding thickness is shown, and the anticoincidence counters are described. Purification of the CO/sub 2/ for proportional counting is discussed. 5 refs., 3 figs.

  3. Chemical digestion of low level nuclear solid waste material

    DOEpatents

    Cooley, Carl R.; Lerch, Ronald E.

    1976-01-01

    A chemical digestion for treatment of low level combustible nuclear solid waste material is provided and comprises reacting the solid waste material with concentrated sulfuric acid at a temperature within the range of 230.degree.-300.degree.C and simultaneously and/or thereafter contacting the reacting mixture with concentrated nitric acid or nitrogen dioxide. In a special embodiment spent ion exchange resins are converted by this chemical digestion to noncombustible gases and a low volume noncombustible residue.

  4. Management of low-level radioactive wastes around the world

    SciTech Connect

    Lakey, L.T.; Harmon, K.M.; Colombo, P.

    1985-04-01

    This paper reviews the status of various practices used throughout the world for managing low-level radioactive wastes. Most of the information in this review was obtained through the DOE-sponsored International Program Support Office (IPSO) activities at Pacific Northwest Laboratory (PNL) at Richland, Washington. The objective of IPSO is to collect, evaluate, and disseminate information on international waste management and nuclear fuel cycle activities. The center's sources of information vary widely and include the proceedings of international symposia, papers presented at technical society meetings, published topical reports, foreign trip reports, and the news media. Periodically, the information is published in topical reports. Much of the information contained in this report was presented at the Fifth Annual Participants' Information Meeting sponsored by DOE's Low-Level Waste Management Program Office at Denver, Colorado, in September of 1983. Subsequent to that presentation, the information has been updated, particularly with information provided by Dr. P. Colombo of Brookhaven National Laboratory who corresponded with low-level waste management specialists in many countries. The practices reviewed in this paper generally represent actual operations. However, major R and D activities, along with future plans, are also discussed. 98 refs., 6 tabls.

  5. Greater-confinement disposal of low-level radioactive wastes

    SciTech Connect

    Trevorrow, L.E.; Gilbert, T.L.; Luner, C.; Merry-Libby, P.A.; Meshkov, N.K.; Yu, C.

    1985-01-01

    Low-level radioactive wastes include a broad spectrum of wastes that have different radionuclide concentrations, half-lives, and physical and chemical properties. Standard shallow-land burial practice can provide adequate protection of public health and safety for most low-level wastes, but a small volume fraction (about 1%) containing most of the activity inventory (approx.90%) requires specific measures known as ''greater-confinement disposal'' (GCD). Different site characteristics and different waste characteristics - such as high radionuclide concentrations, long radionuclide half-lives, high radionuclide mobility, and physical or chemical characteristics that present exceptional hazards - lead to different GCD facility design requirements. Facility design alternatives considered for GCD include the augered shaft, deep trench, engineered structure, hydrofracture, improved waste form, and high-integrity container. Selection of an appropriate design must also consider the interplay between basic risk limits for protection of public health and safety, performance characteristics and objectives, costs, waste-acceptance criteria, waste characteristics, and site characteristics. This paper presents an overview of the factors that must be considered in planning the application of methods proposed for providing greater confinement of low-level wastes. 27 refs.

  6. Steam reforming of low-level mixed waste

    SciTech Connect

    Voelker, G.E.; Steedman, W.G.; Chandran, R.R.

    1996-12-31

    The U.S. department of Energy (DOE) is responsible for the treatment and disposal of an inventory of approximately 160,000 tons of Low-Level Mixed Waste (LLMW). Most of this LLMW is stored in drums, barrels and steel boxes at 20 different sites throughout the DOE complex. The basic objective of low-level mixed waste treatment systems is to completely destroy the hazardous constituents and to simultaneously isolate and capture the radionuclides in a superior final waste form such as glass. The DOE is sponsoring the development of advanced technologies that meet this objective while achieving maximum volume reduction, low-life cycle costs and maximum operational safety. ThermoChem, Inc. is in the final stages of development of a steam-reforming system capable of treating a wide variety of DOE low-level mixed waste that meets these objectives. The design, construction, and testing of a nominal 1 ton/day Process Development Unit is described.

  7. The effects of radiative transfer on low-level cyclogenesis

    SciTech Connect

    Leach, M.J.; Raman, S.

    1995-04-01

    Many investigators have documented the role that thermodynamic forcing due to radiative flux divergence plays in the enhancement or generation of circulation. Most of these studies involve large-scale systems, small-scale systems such as thunderstorms, and squall lines. The generation of circulation on large scales results from the creation of divergence in the upper troposphere and the maintenance of low-level potentially unstable air, and the maintenance of baroclinicity throughout the atmosphere. On smaller scales, radiative flux divergence acts similarly. In the thunderstorms and squall lines, the radiative forcing acts as a pump, increasing the divergence at the top of the storm systems and increasing the updraft velocity and the intensity of inflow at mid-levels in the storm systems. Other researchers have examined the role of surface processes and low-level baroclinicity in east coast cyclogenesis. In this paper, we examine the interactive role that radiative flux divergence, clouds, and surface processes play in low-level cyclogenesis and the creation or maintenance of the boundary layer baroclinicity.

  8. Recent progress in low-level gamma imaging

    SciTech Connect

    Mahe, C.; Girones, Ph.; Lamadie, F.; Le Goaller, C.

    2007-07-01

    The CEA's Aladin gamma imaging system has been operated successfully for several years in nuclear plants and during decommissioning projects with additional tools such as gamma spectrometry detectors and dose rate probes. The radiological information supplied by these devices is becoming increasingly useful for establishing robust and optimized decommissioning scenarios. Recent technical improvements allow this gamma imaging system to be operated in low-level applications and with shorter acquisition times suitable for decommissioning projects. The compact portable system can be used in places inaccessible to operators. It is quick and easy to implement, notably for onsite component characterization. Feasibility trials and in situ measurements were recently carried out under low-level conditions, mainly on waste packages and glove boxes for decommissioning projects. This paper describes recent low-level in situ applications. These characterization campaigns mainly concerned gamma emitters with {gamma} energy < 700 keV. In many cases, the localization of hot spots by gamma camera was confirmed by additional measurements such as dose rate mapping and gamma spectrometry measurements. These complementary techniques associated with advanced calculation codes (MCNP, Mercure 6.2, Visiplan and Siren) offer a mobile and compact tool for specific assessment of waste packages and glove boxes. (authors)

  9. Lidar Measurements of Summer Low Level Jet Events over Baltimore

    NASA Astrophysics Data System (ADS)

    Delgado, R.; Weldegaber, M.; Woodman, M.; Seybold, M.; Demoz, B.; McCann, K. J.; Whiteman, D. N.; Hoff, R. M.

    2008-05-01

    Remote sensing of atmospheric aerosols and water vapor, in the lower troposphere, have been carried out at the University of Maryland, Baltimore County (UMBC) by the Atmospheric Lidar Group during summer low level jet events over Maryland for two years and especially during the Water Vapor Variability - Satellite/Sondes (WAVES) campaigns of 2006 and 2007. For lofted layers encountered the aerosol lidar ratio (Sa) was computed to determine the aerosol extinction and subsequently the optical depth. Aerosol stratification and disturbance of nocturnal boundary layer, observed by lidar at UMBC, was confirmed by Maryland Department of the Environment (MDE) wind profiler measurements. The vertical and horizontal distribution of the low level jet was identified with the Weather Research and Forecasting (WRF) model to characterize the nature and possible effects of the incoming low level jet air mass on surface ozone within the boundary layer. Ground measurements from MDE monitoring stations and lidar optical depth are compared to evaluate aerosol loading due to long range transport in the boundary layer.

  10. Low-level radioactive waste technology: a selected, annotated bibliography

    SciTech Connect

    Fore, C.S.; Vaughan, N.D.; Hyder, L.K.

    1980-10-01

    This annotated bibliography of 447 references contains scientific, technical, economic, and regulatory information relevant to low-level radioactive waste technology. The bibliography focuses on environmental transport, disposal site, and waste treatment studies. The publication covers both domestic and foreign literature for the period 1952 to 1979. Major chapters selected are Chemical and Physical Aspects; Container Design and Performance; Disposal Site; Environmental Transport; General Studies and Reviews; Geology, Hydrology and Site Resources; Regulatory and Economic Aspects; Transportation Technology; Waste Production; and Waste Treatment. Specialized data fields have been incorporated into the data file to improve the ease and accuracy of locating pertinent references. Specific radionuclides for which data are presented are listed in the Measured Radionuclides field, and specific parameters which affect the migration of these radionuclides are presented in the Measured Parameters field. In addition, each document referenced in this bibliography has been assigned a relevance number to facilitate sorting the documents according to their pertinence to low-level radioactive waste technology. The documents are rated 1, 2, 3, or 4, with 1 indicating direct applicability to low-level radioactive waste technology and 4 indicating that a considerable amount of interpretation is required for the information presented to be applied. The references within each chapter are arranged alphabetically by leading author, corporate affiliation, or title of the document. Indexes are provide for (1) author(s), (2) keywords, (3) subject category, (4) title, (5) geographic location, (6) measured parameters, (7) measured radionuclides, and (8) publication description.

  11. Mixed and Low-Level Waste Treatment Facility Project

    SciTech Connect

    Not Available

    1992-04-01

    Mixed and low-level wastes generated at the Idaho National Engineering Laboratory (INEL) are required to be managed according to applicable State and Federal regulations, and Department of Energy Orders that provide for the protection of human health and the environment. The Mixed and Low-Level Waste Treatment Facility Project was chartered in 1991, by the Department of Energy to provide treatment capability for these mixed and low-level waste streams. The first project task consisted of conducting engineering studies to identify the waste streams, their potential treatment strategies, and the requirements that would be imposed on the waste streams and the facilities used to process them. This report documents those studies so the project can continue with an evaluation of programmatic options, system tradeoff studies, and the conceptual design phase of the project. This report, appendix B, comprises the engineering design files for this project study. The engineering design files document each waste steam, its characteristics, and identified treatment strategies.

  12. Low-level measurements of tritium in water.

    PubMed

    Villa, M; Manjón, G

    2004-01-01

    Using a liquid scintillation counter, an experimental procedure for measuring low-level activity concentrations of tritium in environmental water has been developed by our laboratory, using the electrolytic tritium enrichment. Additionally, some quality tests were applied in order to assure the goodness of the method. Well-known water samples collected in the Tagus River (West of Spain) and the Danube River (Bulgaria), both affected by nuclear plant releases, were analysed and results were compared to previous data. The analytical procedure was applied to drinking water samples from the public water supply of Seville and mineral waters from different springs in Spain in order to characterize its origin. Due to the very low levels of tritium in the analysed samples, some results were reported as lower than the minimum detectable activity concentration (MDA). However, the count rate of these measurements was over the background count rate of LS counter in all the cases. For that reason, an exhaustive discussion about the meaning of the MDA, using an experimental essay, was made in order to establish a rigorous criterion that leads to a reliable value in the case of low-level measurements. PMID:15177365

  13. Mixed and Low-Level Waste Treatment Facility project

    SciTech Connect

    Not Available

    1992-04-01

    Mixed and low-level wastes generated at the Idaho National Engineering Laboratory (INEL) are required to be managed according to applicable State and Federal regulations, and Department of Energy Orders that provide for the protection of human health and the environment. The Mixed and Low-Level Waste Treatment Facility Project was chartered in 1991, by the Department of Energy to provide treatment capability for these mixed and low-level waste streams. The first project task consisted of conducting engineering studies to identify the waste streams, their potential treatment strategies, and the requirements that would be imposed on the waste streams and the facilities used to process them. This report, Appendix A, Environmental Regulatory Planning Documentation, identifies the regulatory requirements that would be imposed on the operation or construction of a facility designed to process the INEL's waste streams. These requirements are contained in five reports that discuss the following topics: (1) an environmental compliance plan and schedule, (2) National Environmental Policy Act requirements, (3) preliminary siting requirements, (4) regulatory justification for the project, and (5) health and safety criteria.

  14. Effect of additives on Hg2+ reduction and precipitation inhibited by sodium dithiocarbamate in simulated flue gas desulfurization solutions.

    PubMed

    Lu, Rongjie; Hou, Jiaai; Xu, Jiang; Tang, Tingmei; Xu, Xinhua

    2011-11-30

    Mercury (II) (Hg(2+)) ion can be reduced by aqueous S(IV) (sulfite and/or bisulfite) species, which leads to elemental mercury (Hg(0)) emissions in wet flue gas desulfurization (FGD) systems. Numerous reports have demonstrated the high trapping efficiency of sodium dithiocarbamate over heavy metals. In this paper, a novel sodium dithiocarbamate, DTCR, was utilized as a precipitator to control Hg(2+) reduction and Hg(0) emission against S(IV) in FGD solutions. Results indicated that Hg(2+) reduction efficiency decreased dramatically while precipitation rate peaked at around 91.0% in consistence with the increment of DTCR dosage. Initial pH and temperature had great inhibitory effects on Hg(2+) reduction: the Hg(2+) removal rate gradually increased and reached a plateau along with the increment of temperature and initial pH value. Chloride played a key role in Hg(2+) reduction and precipitation reactions. When Cl(-) concentration increased from 0 to 150 mM, Hg(2+) removal rate dropped from 93.84% to 86.05%, and the Hg(2+) reduction rate remained at a low level (<7.8%). SO(4)(2-), NO(3)(-) and other common metal ions would affect the efficiency of Hg(2+) reduction and precipitation reactions in the simulated desulfurization solutions: Hg(2+) removal rate could always be above 90%, while Hg(2+) reduction rate was maintained at below 10%. The predominance of DTCR over aqueous S(IV), indicated by the results above, has wide industrial applications in FGD systems. PMID:21955657

  15. Raptor responses to low-level jet aircraft and sonic booms.

    PubMed

    Ellis, D H; Ellis, C H; Mindell, D P

    1991-01-01

    We estimated effects of low-level military jet aircraft and mid- to high-altitude sonic booms (actual and simulated) on nesting peregrine falcons (Falco peregrinus) and seven other raptors by observing their responses to test stimuli, determining nesting success for the test year, and evaluating site reoccupancy rates for the year following the tests. Frequent and nearby jet aircraft passes: (1) sometimes noticeably alarmed birds, (2) occasionally caused birds to fly from perches or eyries, (3) most often evoked only minimal responses, and (4) were never associated with reproductive failure. Similarly, responses to real and simulated mid- to high-altitude sonic booms were often minimal and never appeared productivity limiting. Eighteen (95%) of 19 nest sites subjected to low-level jet flights and/or simulated sonic booms in 1980 fledged young during that year. Eighteen (95%) of 19 sites disturbed in 1980 were reoccupied by pairs or lone birds of the same species in 1981. We subjected four pairs of prairie falcons (Falco mexicanus) to low-level aircraft at ad libitum levels during the courtship and incubation phases when adults were most likely to abandon: all four eyries fledged young. From heart rate (HR) data taken via a telemetering egg at another prairie falcon eyrie, we determined that stimulus-induced HR alterations were comparable to rate changes for birds settling to incubate following flight. While encouraging, our findings cannot be taken as conclusive evidence that jet flights and/or sonic booms will have no long-term negative effects for other raptor species or for other areas. In addition, we did not experiment with totally naive wild adults, rotary-winged aircraft, or low-level sonic booms. PMID:15092075

  16. Raptor responses to low-level jet aircraft and sonic booms

    USGS Publications Warehouse

    Ellis, D.H.; Ellis, C.H.; Mindell, D.P.

    1991-01-01

    We estimated effects of low-level military jet aircraft and mid- to high-altitude sonic booms (actual and simulated) on nesting peregrine falcons (Falco peregrinus) and seven other raptors by observing their responses to test stimuli, determining nesting success for the test year, and evaluating site reoccupancy rates for the year following the tests. Frequent and nearby jet aircraft passes: (1) sometimes noticeably alarmed birds, (2) occasionally caused birds toffy from perches or eyries, (3) most often evoked only minimal responses, and (4) were never associated with reproductive failure. Similarly, responses to real and simulated mid- to high-altitude sonic booms were often minimal and never appeared productivity limiting. Eighteen (95%) of 19 nest sites subjected to low-level jet flights and/or simulated sonic booms in 1980 fledged young during that year. Eighteen (95%) of l9 sites disturbed in 1980 were reoccupied by pairs or lone birds of the same species in 1981. We subjected four pairs of prairie falcons (Falco mexicanus) to low-level aircraft at ad libitum levels during the courtship and incubation phases when adults were most likely to abandon: all four eyries fledged young. From heart rate (HR) data taken via a telemetering egg at another prairie falcon eyrie, we determined that stimulus-induced HR alterations were comparable to rate changes for birds settling to incubate following flight. While encouraging, our findings cannot be taken as conclusive evidence that jet flights and/or sonic booms will have no long-term negative effects for other raptor species or for other areas. In addition, we did not experiment with totally naive wild adults, rotary-winged aircraft, or low-level sonic booms.

  17. STABLE SR VS 85SR SORPTION FROM SIMULATED WASTE SOLUTIONS BY MST AND MMST

    SciTech Connect

    Taylor-Pashow, K.; Hobbs, D.

    2012-04-02

    A series of tests were performed to examine the sorption of stable Sr versus the sorption of {sup 85}Sr by monosodium titanate (MST) and modified monosodium titanate (mMST) from simulated waste solutions. Earlier testing indicated a discrepancy between the decontamination factors (DFs) obtained by measuring the stable Sr concentrations by inductively coupled plasma - mass spectroscopy (ICP-MS) and the {sup 85}Sr activities by gamma spectroscopy. One hypothesis to explain this discrepancy was that the stable Sr and {sup 85}Sr were in different chemical forms in the simulated solutions. Several simulants were prepared using different methods for adding the Sr and performance tests were carried out using MST and mMST to determine the Sr and {sup 85}Sr DFs with the various simulants. Testing indicated no discrepancy between the Sr and {sup 85}Sr DFs in tests with these simulants.

  18. US and Russian innovative technologies to process low-level liquid radioactive wastes: The Murmansk initiative

    SciTech Connect

    Dyer, R.S.; Penzin, R.; Duffey, R.B.; Sorlie, A.

    1996-12-31

    This paper documents the status of the technical design for the upgrade and expansion to the existing Low-level Liquid Radioactive Waste (LLLRW) treatment facility in Murmansk, the Russian Federation. This facility, owned by the Ministry of Transportation and operated by the Russian company RTP Atomflot in Murmansk, Russia, has been used by the Murmansk Shipping Company (MSCo) to process low-level liquid radioactive waste generated by the operation of its civilian icebreaker fleet. The purpose of the new design is to enable Russia to permanently cease the disposal at sea of LLLRW in the Arctic, and to treat liquid waste and high saline solutions from both the Civil and North Navy Fleet operations and decommissioning activities. Innovative treatments are to be used in the plant which are discussed in this paper.

  19. Unit cell modeling in support of interim performance assessment for low level tank waste disposal

    SciTech Connect

    Kline, N.W., Westinghouse Hanford

    1996-08-01

    A unit cell model is used to simulate the base analysis case and related sensitivity cases for the interim performance assessment of low level tank waste disposal. Simulation case results are summarized in terms of fractional contaminant release rates to the vadose zone and to the water table at the unconfined aquifer. Results suggest that the crushed glass water conditioning layer at the top of the facility and the chemical retardation pad at the bottom of the facility can be important components of the facility. Results also suggest that the release rates to the water table are dominated by the release rate from the waste form.

  20. A dual-porosity model for simulating solute transport in oil shale

    USGS Publications Warehouse

    Glover, K.C.

    1987-01-01

    A model is described for simulating three-dimensional groundwater flow and solute transport in oil shale and associated geohydrologic units. The model treats oil shale as a dual-porosity medium by simulating flow and transport within fractures using the finite-element method. Diffusion of solute between fractures and the essentially static water of the shale matrix is simulated by including an analytical solution that acts as a source-sink term to the differential equation of solute transport. While knowledge of fracture orientation and spacing is needed to effectively use the model, it is not necessary to map the locations of individual fractures. The computer program listed in the report incorporates many of the features of previous dual-porosity models while retaining a practical approach to solving field problems. As a result the theory of solute transport is not extended in any appreciable way. The emphasis is on bringing together various aspects of solute transport theory in a manner that is particularly suited to the unusual groundwater flow and solute transport characteristics of oil shale systems. (Author 's abstract)

  1. South America Low-Level Jet and its effects on the precipitation over La Plata Basin

    NASA Astrophysics Data System (ADS)

    Llopart, Marta; Coppola, Erika; Giorgi, Filippo

    2015-04-01

    Studies with climate models have shown a dry bias in precipitation over La Plata Basin region for both regional and global models, which suggests a common deficiency in simulating the precipitation of the region. These deficiencies could be tied with the models parameterizations, which are not able to capture the dynamical systems as for example the low level jet, resulting in a weak latitudinal and meridional moisture transport. The goal of this work was to analyze the simulated South America low level jet and its impacts on the precipitation over La Plata Basin using different model parameterizations. In this work we used the Regional Climate Model (RegCM4) over CORDEX South America Domain. The model results were compared against Era-Interim analysis and CRU data. The results show that the low level jet representation is tied to both the precipitation convection scheme and the land-surface scheme. Several combinations of both convection and land-surface scheme have been tested and this can result in a weaker or stronger representation of the jet. The optimal configuration has been obtained and the physical explanation is presented. The jet position and strength is clearly influencing the precipitation spatial distribution and intensity over La Plata basin and by modeling the correct position and intensity the jet the dry bias over this basin is reduced.

  2. Seventh annual DOE LLWMP participants' information meeting. DOE Low-Level Waste Management Program. Abstracts

    SciTech Connect

    Not Available

    1985-08-01

    The following sessions were held: International Low-Level Waste Management Activities; Low-Level Waste Disposal; Characteristics and Treatment of Low-Level Waste; Environmental Monitoring and Performance; Greater Confinement and Alternative Disposal Methods; Low-Level Waste Management; Corrective Measures; Performance Prediction and Assessment; and Siting New Defense and Commercial Low-Level Waste Disposal Facilities.

  3. A preliminary evaluation of alternatives for treatment of INEL Low-Level Waste and low-level mixed waste

    SciTech Connect

    Smith, T.H.; Roesener, W.S.; Jorgensen-Waters, M.J.; Edinborough, C.R.

    1992-06-01

    The Mixed and Low-Level Waste Treatment Facility (MLLWTF) project was established in 1991 by the US Department of Energy Idaho Field Office to provide treatment capabilities for Idaho National Engineering Laboratory (INEL) low-level mixed waste and low-level waste. This report identifies and evaluates the alternatives for treating that waste. Twelve treatment alternatives, ranging from ``no-action`` to constructing and operating the MLLWTF, are identified and evaluated. Evaluations include facility performance, environmental, safety, institutional, schedule, and rough order-of-magnitude cost comparisons. The performance of each alternative is evaluated against lists of ``musts`` and ``wants.`` Also included is a discussion of other key considerations for decision making. Analysis of results indicated further study is necessary to obtain the best estimate of future waste volumes and characteristics from the expanded INEL Decontamination and Decommissioning Program. It is also recommended that conceptual design begin as scheduled on the MLLWTF, maximum treatment alternative while re-evaluating the waste volume projections.

  4. GTS Duratek, Phase I Hanford low-level waste melter tests: 100-kg melter offgas report

    SciTech Connect

    Eaton, W.C.

    1995-11-01

    A multiphase program was initiated in 1994 to test commercially available melter technologies for the vitrification of the low-level waste (LLW) stream from defense wastes stored in underground tanks at the Hanford Site in southeastern Washington State. Phase 1 of the melter demonstration tests using simulated LLW was completed during fiscal year 1995. This document is the 100-kg melter offgas report on testing performed by GTS Duratek, Inc., in Columbia, Maryland. GTS Duratek (one of the seven vendors selected) was chosen to demonstrate Joule heated melter technology under WHC subcontract number MMI-SVV-384215. The document contains the complete offgas report on the 100-kg melter as prepared by Parsons Engineering Science, Inc. A summary of this report is also contained in the GTS Duratek, Phase I Hanford Low-Level Waste Melter Tests: Final Report (WHC-SD-WM-VI-027).

  5. Iron-phosphate ceramics for solidification of mixed low-level waste

    DOEpatents

    Aloy, Albert S.; Kovarskaya, Elena N.; Koltsova, Tatiana I.; Macheret, Yevgeny; Medvedev, Pavel G.; Todd, Terry

    2000-01-01

    A method of immobilizing mixed low-level waste is provided which uses low cost materials and has a relatively long hardening period. The method includes: forming a mixture of iron oxide powders having ratios, in mass %, of FeO:Fe.sub.2 O.sub.3 :Fe.sub.3 O.sub.4 equal to 25-40:40-10:35-50, or weighing a definite amount of magnetite powder. Metallurgical cinder can also be used as the source of iron oxides. A solution of the orthophosphoric acid, or a solution of the orthophosphoric acid and ferric oxide, is formed and a powder phase of low-level waste and the mixture of iron oxide powders or cinder (or magnetite powder) is also formed. The acid solution is mixed with the powder phase to form a slurry with the ratio of components (mass %) of waste:iron oxide powders or magnetite:acid solution=30-60:15-10:55-30. The slurry is blended to form a homogeneous mixture which is cured at room temperature to form the final product.

  6. A computer simulation study of the separation of aqueous solutions using thin zeolite membranes

    NASA Astrophysics Data System (ADS)

    Lin, J.; Murad, S.

    2001-07-01

    A recently developed molecular simulation scheme for studying solutions undergoing osmosis and reverse osmosis was used to study the separation of aqueous solutions using thin zeolite membranes. This method allows for the preservation of the atomic roughness of the membranes, while the molecules that constitute the membranes are also allowed to vibrate. In the simulations, two thin membranes cut from a cubic cell of ZK-4 zeolite were used as the semi-permeable membranes to separate water from aqueous NaCl solutions. Both osmosis and reverse-osmosis phenomena were observed. The study showed that ZK-4 zeolite membranes show promise for use in membrane-based separation of aqueous electrolyte solutions, as well as other similar systems.

  7. Status of low-level radioactive waste management in Korea

    SciTech Connect

    Lee, K.J.

    1993-03-01

    The Republic of Korea has accomplished dramatic economic growth over the past three decades; demand for electricity has rapidly grown more than 15% per year. Since the first nuclear power plant, Kori-1 [587 MWe, pressurized water reactor (PWR)], went into commercial operation in 1978, the nuclear power program has continuously expanded and played a key role in meeting the national electricity demand. Nowadays, Korea has nine nuclear power plants [eight PWRs and one Canadian natural uranium reactor (CANDU)] in operation with total generating capacity of 7,616 MWe. The nuclear share of total electrical capacity is about 36%; however, about 50% of actual electricity production is provided by these nine nuclear power plants. In addition, two PWRs are under construction, five units (three CANDUs and two PWRs) are under design, and three more CANDUs and eight more PWRs are planned to be completed by 2006. With this ambitious nuclear program, the total nuclear generating capacity will reach about 23,000 MWe and the nuclear share will be about 40% of the total generating capacity in the year 2006. In order to expand the nuclear power program this ambitiously, enormous amounts of work still have to be done. One major area is radioactive waste management. This paper reviews the status of low-level radioactive waste management in Korea. First, the current and future generation of low-level radioactive wastes are estimated. Also included are the status and plan for the construction of a repository for low-level radioactive wastes, which is one of the hot issues in Korea. Then, the nuclear regulatory system is briefly mentioned. Finally, the research and development activities for LLW management are briefly discussed.

  8. Steady and Unsteady Nozzle Simulations Using the Conservation Element and Solution Element Method

    NASA Technical Reports Server (NTRS)

    Friedlander, David Joshua; Wang, Xiao-Yen J.

    2014-01-01

    This paper presents results from computational fluid dynamic (CFD) simulations of a three-stream plug nozzle. Time-accurate, Euler, quasi-1D and 2D-axisymmetric simulations were performed as part of an effort to provide a CFD-based approach to modeling nozzle dynamics. The CFD code used for the simulations is based on the space-time Conservation Element and Solution Element (CESE) method. Steady-state results were validated using the Wind-US code and a code utilizing the MacCormack method while the unsteady results were partially validated via an aeroacoustic benchmark problem. The CESE steady-state flow field solutions showed excellent agreement with solutions derived from the other methods and codes while preliminary unsteady results for the three-stream plug nozzle are also shown. Additionally, a study was performed to explore the sensitivity of gross thrust computations to the control surface definition. The results showed that most of the sensitivity while computing the gross thrust is attributed to the control surface stencil resolution and choice of stencil end points and not to the control surface definition itself.Finally, comparisons between the quasi-1D and 2D-axisymetric solutions were performed in order to gain insight on whether a quasi-1D solution can capture the steady and unsteady nozzle phenomena without the cost of a 2D-axisymmetric simulation. Initial results show that while the quasi-1D solutions are similar to the 2D-axisymmetric solutions, the inability of the quasi-1D simulations to predict two dimensional phenomena limits its accuracy.

  9. The Dependence of the Low-Level Equatorial Easterly Jet on Hadley and Walker Circulations.

    NASA Astrophysics Data System (ADS)

    Battisti, David S.; Ovens, David D.

    1995-11-01

    in that region.The eddy vertical-flux convergence of moisture in the Kuo convective scheme produces a dry tongue in the Walker circulation simulation below the low-level equatorial easterly jet. The CCM1 climatologies show that the dynamics of the jet do not depend on this feature. Betts, Albrecht, and Kloesel have observed a similar feature just above the boundary layer in the central to eastern Pacific and, without referring to the low-level jet, they have hypothesized a mechanism in which convection forms this dry layer. Analysis of the simulations performed here suggests that the model's parameterized convective physics utilize the same mechanism to form the dry tongue in the vicinity of the low-level equatorial easterly jet; however, since the mechanism of Betts, Albrecht, and Kloesel has not yet been confirmed through observational studies, the relationship between the observed and modeled dry tongue remains speculative.

  10. Geologic setting of the low-level burial grounds

    SciTech Connect

    Lindsey, K.A.; Jaeger, G.K.; Slate, J.L.; Swett, K.J.; Mercer, R.B.

    1994-10-13

    This report describes the regional and site specific geology of the Hanford Sites low-level burial grounds in the 200 East and West Areas. The report incorporates data from boreholes across the entire 200 Areas, integrating the geology of this area into a single framework. Geologic cross-sections, isopach maps, and structure contour maps of all major geological units from the top of the Columbia River Basalt Group to the surface are included. The physical properties and characteristics of the major suprabasalt sedimentary units also are discussed.

  11. Mobile plant for low-level radioactive waste reprocessing

    SciTech Connect

    Sobolev, I.A.; Panteleyev, V.I.; Demkin, V.I.

    1993-12-31

    Along with nuclear power plants, many scientific and industrial enterprises generate radioactive wastes, especially low-level liquid wastes. Some of these facilities generate only small amounts on the order of several dozen cubic meters per year. The Moscow scientific industrial association, Radon, developed a mobile pilot system, EKO, for the processing of LLW with a low salt content. The plant consists of three modules: ultrafiltration module; electrodialysis module; and filtration module. The paper describes the technical parameters and test results from the plant on real LLW.

  12. Low level atmospheric sulfur dioxide pollution and childhood asthma

    SciTech Connect

    Tseng, R.Y.; Li, C.K. )

    1990-11-01

    Quarterly analysis (1983-1987) of childhood asthma in Hong Kong from 13,620 hospitalization episodes in relation to levels of pollutants (SO{sub 2}, NO{sub 2}, NO, O{sub 3}, TSP, and RSP) revealed a seasonal pattern of attack rates that correlates inversely with exposure to sulfur dioxide (r = -.52, P less than .05). The same cannot be found with other pollutants. Many factors may contribute to the seasonal variation of asthma attacks. We speculate that prolonged exposure (in terms of months) to low level SO{sub 2} is one factor that might induce airway inflammation and bronchial hyperreactivity and predispose to episodes of asthma.

  13. System for chemically digesting low level radioactive, solid waste material

    DOEpatents

    Cowan, Richard G.; Blasewitz, Albert G.

    1982-01-01

    An improved method and system for chemically digesting low level radioactive, solid waste material having a high through-put. The solid waste material is added to an annular vessel (10) substantially filled with concentrated sulfuric acid. Concentrated nitric acid or nitrogen dioxide is added to the sulfuric acid within the annular vessel while the sulfuric acid is reacting with the solid waste. The solid waste is mixed within the sulfuric acid so that the solid waste is substantilly fully immersed during the reaction. The off gas from the reaction and the products slurry residue is removed from the vessel during the reaction.

  14. Nuclear reactor with low-level core coolant intake

    DOEpatents

    Challberg, Roy C.; Townsend, Harold E.

    1993-01-01

    A natural-circulation boiling-water reactor has skirts extending downward from control rod guide tubes to about 10 centimeters from the reactor vessel bottom. The skirts define annular channels about control rod drive housings that extend through the reactor vessel bottom. Recirculating water is forced in through the low-level entrances to these channels, sweeping bottom water into the channels in the process. The sweeping action prevents cooler water from accumulating at the bottom. This in turn minimizes thermal shock to bottom-dwelling components as would occur when accumulated cool water is swept away and suddenly replaced by warmer water.

  15. Alpha low-level stored waste systems design study

    SciTech Connect

    Feizollahi, F.; Teheranian, B.; Quapp, W.J.

    1992-08-01

    The Stored Waste System Design Study (SWSDS), commissioned by the Waste Technology Development Department at the Idaho National Engineering Laboratory (INEL), examines relative life-cycle costs associated with three system concepts for processing the alpha low-level waste (alpha-LLW) stored at the Radioactive Waste Management Complex`s Transuranic Storage Area at the INEL. The three system concepts are incineration/melting; thermal treatment/solidification; and sort, treat, and repackage. The SWSDS identifies system functional and operational requirements and assesses implementability; effectiveness; cost; and demonstration, testing, and evaluation (DT&E) requirements for each of the three concepts.

  16. Alpha low-level stored waste systems design study

    SciTech Connect

    Feizollahi, F.; Teheranian, B. . Environmental Services Div.); Quapp, W.J. )

    1992-08-01

    The Stored Waste System Design Study (SWSDS), commissioned by the Waste Technology Development Department at the Idaho National Engineering Laboratory (INEL), examines relative life-cycle costs associated with three system concepts for processing the alpha low-level waste (alpha-LLW) stored at the Radioactive Waste Management Complex's Transuranic Storage Area at the INEL. The three system concepts are incineration/melting; thermal treatment/solidification; and sort, treat, and repackage. The SWSDS identifies system functional and operational requirements and assesses implementability; effectiveness; cost; and demonstration, testing, and evaluation (DT E) requirements for each of the three concepts.

  17. Low level communication management for e-health systems

    NASA Astrophysics Data System (ADS)

    Riva, Guillermo; Zerbini, Carlos; Voos, Javier; Centeno, Carlos; González, Eduardo

    2011-12-01

    The heterogeneity of e-health systems encourages the use of standards such as Health Level 7 (HL7v3) to ensure interoperability. Many actual implementations address this problem by unoptimized high level programming of top-range portable computing platforms. However, this approach could pose excessive demands on battery-powered mid-range terminals. In this work, we propose low-level support for portable HL7v3-compatible embedded systems in order to better exploit their limited processing and communications capabilities. In particular, we present our experience in mobile communication management through two different approaches, which proves the feasibility of this proposal.

  18. Effectiveness of low-level laser on carpal tunnel syndrome

    PubMed Central

    Li, Zhi-Jun; Wang, Yao; Zhang, Hua-Feng; Ma, Xin-Long; Tian, Peng; Huang, Yuting

    2016-01-01

    Abstract Background: Low-level laser therapy (LLLT) has been applied in the treatment of carpal tunnel syndrome (CTS) for an extended period of time without definitive consensus on its effectiveness. This meta-analysis was conducted to evaluate the effectiveness of low-level laser in the treatment of mild to moderate CTS using a Cochrane systematic review. Methods: We conducted electronic searches of PubMed (1966–2015.10), Medline (1966–2015.10), Embase (1980–2015.10), and ScienceDirect (1985–2015.10), using the terms “carpal tunnel syndrome” and “laser” according to the Cochrane Collaboration guidelines. Relevant journals or conference proceedings were searched manually to identify studies that might have been missed in the database search. Only randomized clinical trials were included, and the quality assessments were performed according to the Cochrane systematic review method. The data extraction and analyses from the included studies were conducted independently by 2 reviewers. The results were expressed as the mean difference (MD) with 95% confidence intervals (CI) for the continuous outcomes. Results: Seven randomized clinical trials met the inclusion criteria; there were 270 wrists in the laser group and 261 wrists in the control group. High heterogeneity existed when the analysis was conducted. Hand grip (at 12 weeks) was stronger in the LLLT group than in the control group (MD = 2.04; 95% CI: 0.08–3.99; P = 0.04; I2 = 62%), and there was better improvement in the visual analog scale (VAS) (at 12 weeks) in the LLLT group (MD = 0.97; 95% CI: 0.84–1.11; P < 0.01; I2 = 0%). The sensory nerve action potential (SNAP) (at 12 weeks) was better in the LLLT group (MD = 1.08; 95% CI: 0.44–1.73; P = 0.001; I2 = 0%). However, 1 included study was weighted at >95% in the calculation of these 3 parameters. There were no statistically significant differences in the other parameters between the 2 groups. Conclusion

  19. Ankle-foot orthosis function in low-level myelomeningocele.

    PubMed

    Hullin, M G; Robb, J E; Loudon, I R

    1992-01-01

    Six children with low-level myelomeningocele underwent gait analysis. All showed excessive ankle dorsiflexion and knee flexion when walking barefoot. A rigid thermoplastic ankle-foot orthosis (AFO) improved gait by preventing ankle dorsiflexion and reducing knee flexion. Biomechanically, the AFO caused a reduction in external knee moment by aligning the knee with the ground reaction force. Small changes in the foot-shank angle of the orthosis had profound effects on knee mechanics. Knee hyperextension could be controlled by a rocker sole. Kinetic gait analysis permits understanding of the biomechanical effects of orthoses. PMID:1613099

  20. Parametric study of radionuclide characterization -- Low-level waste. Draft

    SciTech Connect

    Amir, S.J.

    1993-04-01

    The criteria and guidance given in this addendum specifically address the classification of low-level waste at the Hanford Reservation into Category 1, Category 3, and Greater Than Category 3 (GTC3). These categories are developed based on the performance assessment (PA) being conducted for the Hanford Site. The radionuclides and their concentration for each category are listed in the revised Table 1-1 (Attachment 1). The information to classify the waste for US Department of Transportation (DOT) and to classify Transuranic (TRU)/ Non-TRU, Contact Handled (CH)/Remote Handled (RH) waste is given in WHC-EP-0063-3 (WHC 1991).

  1. Treatment of Lymphedema Praecox through Low Level Laser Therapy (LLLT)

    PubMed Central

    Mahram, Manoochehr; Rajabi, Majid

    2011-01-01

    A 15-year-old girl with right lower extremity lymphedema praecox was treated through Low Level Laser Therapy (LLLT), by means of a GaAs and GaAlAs diodes laser-therapy device. Treatment sessions were totally 24, each cycle containing 12 every other day 15-minute sessions, and one month free between the cycles. The treatment was achieved to decrease the edema and no significant increase in circumference of involved leg was found following three months after the course of treatment. Although LLLT can be considered a beneficial treatment for Lymphedema Praecox, any definite statement around its effectiveness needs more studies on more cases. PMID:22091317

  2. Solvent activity in electrolyte solutions from molecular simulation of the osmotic pressure

    NASA Astrophysics Data System (ADS)

    Kohns, Maximilian; Reiser, Steffen; Horsch, Martin; Hasse, Hans

    2016-02-01

    A method for determining the activity of the solvent in electrolyte solutions by molecular dynamics simulations is presented. The electrolyte solution is simulated in contact with the pure solvent. Between the two phases, there is a virtual membrane, which is permeable only for the solvent. In the simulation, this is realized by an external field which acts only on the solutes and confines them to a part of the simulation volume. The osmotic pressure, i.e., the pressure difference between both phases, is obtained with high accuracy from the force on the membrane, so that reliable data on the solvent activity can be determined. The acronym of the new method is therefore OPAS (osmotic pressure for activity of solvents). The OPAS method is verified using tests of varying complexity. This includes a comparison of results from the OPAS method for aqueous NaCl solutions to results from the literature which were obtained with other molecular simulation methods. Favorable agreement is observed not only for the solvent activity but also for the activity coefficient of NaCl, which is obtained by application of the Gibbs-Duhem equation.

  3. Solvent activity in electrolyte solutions from molecular simulation of the osmotic pressure.

    PubMed

    Kohns, Maximilian; Reiser, Steffen; Horsch, Martin; Hasse, Hans

    2016-02-28

    A method for determining the activity of the solvent in electrolyte solutions by molecular dynamics simulations is presented. The electrolyte solution is simulated in contact with the pure solvent. Between the two phases, there is a virtual membrane, which is permeable only for the solvent. In the simulation, this is realized by an external field which acts only on the solutes and confines them to a part of the simulation volume. The osmotic pressure, i.e., the pressure difference between both phases, is obtained with high accuracy from the force on the membrane, so that reliable data on the solvent activity can be determined. The acronym of the new method is therefore OPAS (osmotic pressure for activity of solvents). The OPAS method is verified using tests of varying complexity. This includes a comparison of results from the OPAS method for aqueous NaCl solutions to results from the literature which were obtained with other molecular simulation methods. Favorable agreement is observed not only for the solvent activity but also for the activity coefficient of NaCl, which is obtained by application of the Gibbs-Duhem equation. PMID:26931686

  4. PERSiST: the precipitation, evapotranspiration and runoff simulator for solute transport

    NASA Astrophysics Data System (ADS)

    Futter, M. N.; Erlandsson, M. A.; Butterfield, D.; Whitehead, P. G.; Oni, S. K.; Wade, A. J.

    2013-07-01

    While runoff is often a first-order control on water quality, runoff generation processes and pathways can vary widely between catchments. Credible simulations of solute and pollutant transport in surface waters are dependent on models which facilitate appropriate representations of perceptual models of the runoff generation process. With a few exceptions, models used in solute transport simulations enforce a single, potentially inappropriate representation of the runoff generation process. Here, we present a flexible, semi-distributed landscape scale rainfall-runoff model suitable for simulating a broad range of user-specified perceptual models of runoff generation and stream flow occurring in different climatic regions and landscape types. PERSiST, the Precipitation, Evapotranspiration and Runoff Simulator for Solute Transport; is designed for simulating present day conditions and projecting possible future effects of climate or land use change on runoff, catchment water storage and solute transport. PERSiST has limited data requirements and is calibrated using observed time series of precipitation, air temperature and runoff at one or more points in a river network. Here, we present a first application of the model to the Thames River in the UK and describe a Monte Carlo tool for parameter optimization and sensitivity analysis.

  5. Generalized image charge solvation model for electrostatic interactions in molecular dynamics simulations of aqueous solutions

    NASA Astrophysics Data System (ADS)

    Deng, Shaozhong; Xue, Changfeng; Baumketner, Andriy; Jacobs, Donald; Cai, Wei

    2013-07-01

    This paper extends the image charge solvation model (ICSM) [Y. Lin, A. Baumketner, S. Deng, Z. Xu, D. Jacobs, W. Cai, An image-based reaction field method for electrostatic interactions in molecular dynamics simulations of aqueous solutions, J. Chem. Phys. 131 (2009) 154103], a hybrid explicit/implicit method to treat electrostatic interactions in computer simulations of biomolecules formulated for spherical cavities, to prolate spheroidal and triaxial ellipsoidal cavities, designed to better accommodate non-spherical solutes in molecular dynamics (MD) simulations. In addition to the utilization of a general truncated octahedron as the MD simulation box, central to the proposed extension is an image approximation method to compute the reaction field for a point charge placed inside such a non-spherical cavity by using a single image charge located outside the cavity. The resulting generalized image charge solvation model (GICSM) is tested in simulations of liquid water, and the results are analyzed in comparison with those obtained from the ICSM simulations as a reference. We find that, for improved computational efficiency due to smaller simulation cells and consequently a less number of explicit solvent molecules, the generalized model can still faithfully reproduce known static and dynamic properties of liquid water at least for systems considered in the present paper, indicating its great potential to become an accurate but more efficient alternative to the ICSM when bio-macromolecules of irregular shapes are to be simulated.

  6. Greater-than-Class C low-level waste characterization

    SciTech Connect

    Piscitella, R.R.

    1991-12-31

    In 1985, Public Law 99-240 (Low-Level Radioactive Waste Policy Amendments Act of 1985) made the Department of Energy (DOE) responsible for the disposal of greater-than-Class C low-level radioactive waste (GTCC LLW). DOE strategies for storage and disposal of GTCC LLW required characterization of volumes, radionuclide activities, and waste forms. Data from existing literature, disposal records, and original research were used to estimate characteristics, project volumes, and determine radionuclide activities to the years 2035 and 2055. Twenty-year life extensions for 70% of the operating nuclear reactors were assumed to calculate the GTCC LLW available in 2055. The following categories of GTCC LLW were addressed: Nuclear Utilities Waste; Potential Sealed Sources GTCC LLW; DOE-Held Potential GTCC LLW; and Other Generator Waste. It was determined that the largest volume of these wastes, approximately 57%, is generated by nuclear utilities. The Other Generator Waste category contributes approximately 10% of the total GTCC LLW volume projected to the year 2035. DOE-Held Potential GTCC LLW accounts for nearly 33% of all waste projected to the year 2035. Potential Sealed Sources GTCC LLW is less than 0.2% of the total projected volume. The base case total projected volume of GTCC LLW for all categories was 3,250 cubic meters. This was substantially less than previous estimates.

  7. IGRIS for characterizing low-level radioactive waste

    SciTech Connect

    Peters, C.W.; Swanson, P.J.

    1993-03-01

    A recently developed neutron diagnostic probe system has the potential to noninvasively characterize low-level radioactive waste in bulk soil samples, containers such as 55-gallon barrels, and in pipes, valves, etc. The probe interrogates the target with a low-intensity beam of 14-MeV neutrons produced from the deuterium-tritium reaction in a specially designed sealed-tube neutron-generator (STNG) that incorporates an alpha detector to detect the alpha particle associated with each neutron. These neutrons interact with the nuclei in the target to produce inelastic-, capture-, and decay-gamma rays that are detected by gamma-ray detectors. Time-of-flight methods are used to separate the inelastic-gamma rays from other gamma rays and to determine the origin of each inelastic-gamma ray in three dimensions through Inelastic-Gamma Ray Imaging and Spectroscopy (IGRIS). The capture-gamma ray spectrum is measured simultaneously with the IGRIS measurements. The decay-gamma ray spectrum is measured with the STNG turned off. Laboratory proof-of-concept measurements were used to design prototype systems for Bulk Soil Assay, Barrel Inspection, and Decontamination and Decommissioning and to predict their minimum detectable levels for heavy toxic metals (As, Hg, Cr, Zn, Pb, Ni, and Cd), uranium and transuranics, gamma-ray emitters, and elements such as chlorine, which is found in PCBs and other pollutants. These systems are expected to be complementary and synergistic with other technologies used to characterize low-level radioactive waste.

  8. Secondary Low-Level Waste Treatment Strategy Analysis

    SciTech Connect

    D.M. LaRue

    1999-05-25

    The objective of this analysis is to identify and review potential options for processing and disposing of the secondary low-level waste (LLW) that will be generated through operation of the Monitored Geologic Repository (MGR). An estimate of annual secondary LLW is generated utilizing the mechanism established in ''Secondary Waste Treatment Analysis'' (Reference 8.1) and ''Secondary Low-Level Waste Generation Rate Analysis'' (Reference 8.5). The secondary LLW quantities are based on the spent fuel and high-level waste (HLW) arrival schedule as defined in the ''Controlled Design Assumptions Document'' (CDA) (Reference 8.6). This analysis presents estimates of the quantities of LLW in its various forms. A review of applicable laws, codes, and standards is discussed, and a synopsis of those applicable laws, codes, and standards and their impacts on potential processing and disposal options is presented. The analysis identifies viable processing/disposal options in light of the existing laws, codes, and standards, and then evaluates these options in regard to: (1) Process and equipment requirements; (2) LLW disposal volumes; and (3) Facility requirements.

  9. Biological intrusion of low-level-waste trench covers

    SciTech Connect

    Hakonson, T.E.; Gladney, E.S.

    1981-01-01

    The long-term integrity of low-level waste shallow land burial sites is dependent on the interaction of physical, chemical, and biological factors that modify the waste containment system. Past research on low-level waste shallow land burial methods has emphasized physical (i.e., water infiltration, soil erosion) and chemical (radionuclide leaching) processes that can cause waste site failure and subsequent radionuclide transport. The purpose of this paper is to demonstrate the need to consider biological processes as being potentially important in reducing the integrity of waste burial site cover treatments. Plants and animals not only can transport radionuclides to the ground surface via root systems and soil excavated from the cover profile by animal burrowing activities, but they modify physical and chemical processes within the cover profile by changing the water infiltration rates, soil erosion rates and chemical composition of the soil. One approach to limiting biological intrusion through the waste cover is to apply a barrier within the profile to limit root and animal penetration with depth. Experiments in the Los Alamos Experimental Engineered Test Facility were initiated to develop and evaluate biological barriers that are effective in minimizing intrusion into waste trenches. The experiments that are described employ four different candidate barrier materials of geologic origin. Experimental variables that will be evaluated, in addition to barrier type, are barrier depth and soil overburden depth. The rate of biological intrusion through the various barrier materials is being evaluated through the use of activatable stable tracers.

  10. Treatment options for low-level radiologically contaminated ORNL filtercake

    SciTech Connect

    Lee, Hom-Ti; Bostick, W.D.

    1996-04-01

    Water softening sludge (>4000 stored low level contaminated drums; 600 drums per year) generated by the ORNL Process Waste Treatment Plant must be treated, stabilized, and placed in safe storage/disposal. The sludge is primarily CaCO{sub 3} and is contaminated by low levels of {sup 90}Sr and {sup 137}Cs. In this study, microwave sintering and calcination were evaluated for treating the sludge. The microwave melting experiments showed promise: volume reductions were significant (3-5X), and the waste form was durable with glass additives (LiOH, fly ash). A commercial vendor using surrogate has demonstrated a melt mineralization process that yields a dense monolithic waste form with a volume reduction factor (VR) of 7.7. Calcination of the sludge at 850-900 C yielded a VR of 2.5. Compaction at 4500 psi increased the VR to 4.2, but the compressed form is not dimensionally stable. Addition of paraffin helped consolidate fines and yielded a VR of 3.5. In conclusion, microwave melting or another form of vitrification is likely to be the best method; however for immediate implementation, the calculation/compaction/waxing process is viable.

  11. Biphasic Dose Response in Low Level Light Therapy

    PubMed Central

    Huang, Ying-Ying; Chen, Aaron C.-H.; Carroll, James D.; Hamblin, Michael R.

    2009-01-01

    The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing cell death and tissue damage has been known for over forty years since the invention of lasers. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial in mainstream medicine. The biochemical mechanisms underlying the positive effects are incompletely understood, and the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. A biphasic dose response has been frequently observed where low levels of light have a much better effect on stimulating and repairing tissues than higher levels of light. The so-called Arndt-Schulz curve is frequently used to describe this biphasic dose response. This review will cover the molecular and cellular mechanisms in LLLT, and describe some of our recent results in vitro and in vivo that provide scientific explanations for this biphasic dose response. PMID:20011653

  12. Modified sulfur cement solidification of low-level wastes

    SciTech Connect

    Not Available

    1985-10-01

    This topical report describes the results of an investigation on the solidification of low-level radioactive wastes in modified sulfur cement. The work was performed as part of the Waste Form Evaluation Program, sponsored by the US Department of Energy's Low-Level Waste Management Program. Modified sulfur cement is a thermoplastic material developed by the US Bureau of Mines. Processing of waste and binder was accomplished by means of both a single-screw extruder and a dual-action mixing vessel. Waste types selected for this study included those resulting from advanced volume reduction technologies (dry evaporator concentrate salts and incinerator ash) and those which remain problematic for solidification using contemporary agents (ion exchange resins). Process development studies were conducted to ascertain optimal process control parameters for successful solidification. Maximum waste loadings were determined for each waste type and method of processing. Property evaluation testing was carried out on laboratory scale specimens in order to compare with waste form performance for other potential matrix materials. Waste form property testing included compressive strength, water immersion, thermal cycling and radionuclide leachability. Recommended waste loadings of 40 wt. % sodium sulfate and boric acid salts and 43 wt. % incinerator ash, which are based on processing and performance considerations, are reported. Solidification efficiencies for these waste types represent significant improvements over those of hydraulic cements. Due to poor waste form performance, incorporation of ion exchange resin waste in modified sulfur cement is not recommended.

  13. A computer simulation study of the formation of liquid crystal nanodroplets from a homogeneous solution.

    PubMed

    Berardi, Roberto; Costantini, Alberto; Muccioli, Luca; Orlandi, Silvia; Zannoni, Claudio

    2007-01-28

    The aggregation of liquid crystal nanodroplets from a homogeneous solution is an important but not well understood step in the preparation of various advanced photonic materials. Here, the authors performed molecular dynamics computer simulations of the formation of liquid crystalline nanodroplets, starting from an isotropic and uniform binary solution of spherical Lennard-Jones (solvent) and elongated ellipsoidal Gay-Berne (solute) rigid particles in low (<10%) concentration. They studied the dynamics of demixing and the mesogen ordering process and characterized the resulting nanodroplets assessing the effect of temperature, composition, and specific solute-solvent interaction on the morphology, structure, and anisotropy. They find that the specific solute-solvent interaction, composition, and temperature can be adjusted to tune the nanodroplet growth and size. PMID:17286507

  14. A computer simulation study of the formation of liquid crystal nanodroplets from a homogeneous solution

    NASA Astrophysics Data System (ADS)

    Berardi, Roberto; Costantini, Alberto; Muccioli, Luca; Orlandi, Silvia; Zannoni, Claudio

    2007-01-01

    The aggregation of liquid crystal nanodroplets from a homogeneous solution is an important but not well understood step in the preparation of various advanced photonic materials. Here, the authors performed molecular dynamics computer simulations of the formation of liquid crystalline nanodroplets, starting from an isotropic and uniform binary solution of spherical Lennard-Jones (solvent) and elongated ellipsoidal Gay-Berne (solute) rigid particles in low (<10%) concentration. They studied the dynamics of demixing and the mesogen ordering process and characterized the resulting nanodroplets assessing the effect of temperature, composition, and specific solute-solvent interaction on the morphology, structure, and anisotropy. They find that the specific solute-solvent interaction, composition, and temperature can be adjusted to tune the nanodroplet growth and size.

  15. Development of Three-Layer Simulation Model for Freezing Process of Food Solution Systems

    NASA Astrophysics Data System (ADS)

    Kaminishi, Koji; Araki, Tetsuya; Shirakashi, Ryo; Ueno, Shigeaki; Sagara, Yasuyuki

    A numerical model has been developed for simulating freezing phenomena of food solution systems. The cell model was simplified to apply to food solution systems, incorporating with the existence of 3 parts such as unfrozen, frozen and moving boundary layers. Moreover, the moving rate of freezing front model was also introduced and calculated by using the variable space network method proposed by Murray and Landis (1957). To demonstrate the validity of the model, it was applied to the freezing processes of coffee solutions. Since the model required the phase diagram of the material to be frozen, the initial freezing temperatures of 1-55 % coffee solutions were measured by the DSC method. The effective thermal conductivity for coffee solutions was determined as a function of temperature and solute concentration by using the Maxwell - Eucken model. One-dimensional freezing process of 10 % coffee solution was simulated based on its phase diagram and thermo-physical properties. The results were good agreement with the experimental data and then showed that the model could accurately describe the change in the location of the freezing front and the distributions of temperature as well as ice fraction during a freezing process.

  16. The plasma torch for the vitrification of low-level radioactive waste

    SciTech Connect

    Peratt, A.L.

    1995-12-31

    Plasma torch technology provides a possible solution for radioactive material storage. During the past decade, plasma torches have been developed that produce temperatures as high as 25,000 F. Currently, the plasma torch finds application in solid waste vitrification and pyrolysis plants. Low-level radioactive waste is a topic of considerable interest for baseline technologies development, generally by means of low-temperature arc heating to characterize surrogate or low-level waste streams. High temperature plasma torches, the hottest members belonging to the family of plasma arc heaters, are efficient devices for reducing matter to its constituent elements but also the most complex in theory and operation. Characterization of the high energy density plasma instability that produces the intense heat, ranges from MHD computer modeling to stimulated Raman scattering by laser diagnostics. This paper describes the history of the plasma torch and the possible use of a 1-megawatt reverse polarity torch in a low-level radioactive waste testbed. Issues such as torch diagnostics, control, and the monitoring of radioactive gaseous, aqueous, solid, and plasma effluent streams are discussed.

  17. Climatology Study of Low-level Cloud and Fog in Mountain Terrain Using Satellite Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Duan, Yajuan; Barros, Ana P.

    2015-04-01

    The presence of orographic clouds and fog has major environmental and economic implications that the potential shift in the space-time distribution can effectively redistribute freshwater resources and threaten the sustainability of the ecology, geomorphology and hydrology of mountainous regions and adjacent basins. This includes the Southern Appalachian Mountains, which rely closely on the moisture input from fog, cap clouds and light rainfall, as well as cloud forests in the Andes with frequent occurrence of dense fog. However, the applicability of fog forecasting models becomes limited in regions of complex terrain. The motivation of this project is to develop a satellite-based hydroclimatology and physical parameterization of orographic low-level clouds and fog regimes in the Southern Appalachians using a general methodology that can be applied to mountainous regions elsewhere. An algorithm for the detection and extraction of stratus clouds and fog was developed using cloud base height product from 8-years of CALIPSO and CloudSat observations, and evaluated against ground-based measurements from ceilometers. This population of low-level clouds and fog will be analyzed with GOES infrared and visible imagery, MODIS products, and with airport cloud height and visibility records to expand the spatial coverage beyond narrow satellite sensor swaths. The climatology will be further developed through integration with results from WRF high-solution simulations for selected periods since the bulk of the PMM network has been in place (2008-present) to aid in defining meteorological and time-of-day constraints in the interpretation of simulated satellite profiles through a satellite-sensor simulator. A 4-day WRF simulation is performed at Pegion Basin in the Southern Appalachian Mountains with increasing horizontal (0.25 km grid spacing) and vertical (up to 80 sigma levels) resolution and evaluated against observations collected during the Integrated Precipitation and

  18. Intercomparison of 3D pore-scale flow and solute transport simulation methods

    DOE PAGESBeta

    Mehmani, Yashar; Schoenherr, Martin; Pasquali, Andrea; Perkins, William A.; Kim, Kyungjoo; Perego, Mauro; Parks, Michael L.; Balhoff, Matthew T.; Richmond, Marshall C.; Geier, Martin; et al

    2015-09-28

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing a standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that validation to include additional models of the first type based onmore » the lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). The PNM approach used in the current study was recently improved and demonstrated to accurately simulate solute transport in a two-dimensional experiment. While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries on solute transport in the manner of PNMs has not been fully determined. We apply all four approaches (FVM-based CFD, LBM, SPH and PNM) to simulate pore-scale velocity distributions and (for capable codes) nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The intercomparison work was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This paper provides support for

  19. Intercomparison of 3D pore-scale flow and solute transport simulation methods

    SciTech Connect

    Mehmani, Yashar; Schoenherr, Martin; Pasquali, Andrea; Perkins, William A.; Kim, Kyungjoo; Perego, Mauro; Parks, Michael L.; Balhoff, Matthew T.; Richmond, Marshall C.; Geier, Martin; Krafczyk, Manfred; Luo, Li -Shi; Tartakovsky, Alexandre M.; Yang, Xiaofan; Scheibe, Timothy D.; Trask, Nathaniel

    2015-09-28

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing a standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that validation to include additional models of the first type based on the lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). The PNM approach used in the current study was recently improved and demonstrated to accurately simulate solute transport in a two-dimensional experiment. While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries on solute transport in the manner of PNMs has not been fully determined. We apply all four approaches (FVM-based CFD, LBM, SPH and PNM) to simulate pore-scale velocity distributions and (for capable codes) nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The intercomparison work was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This paper provides support for confidence

  20. Effects of low-level chronic irradiation on radiosensitivity of mammals: modeling and experimental studies

    NASA Astrophysics Data System (ADS)

    Smirnova, O. A.; Yonezawa, M.

    Effects of low dose rate chronic irradiation on radiosensitivity of mammals mice are studied by experimental and modeling methods Own and reference experiments show that priming chronic low-level short-term and long-term exposures to radiation induce respectively elevated radiosensitivity and lowered radiosensitivity radioresistance in mice The manifestation of these radiosensitization and radioprotection effects are respectively increased and decreased mortality of preirradiated specimens after challenge acute irradiation in comparison with those for previously unexposed ones Taking into account that the reason of the animal death in the experiments was the hematopoietic syndrome the biophysical models of the critical body system hematopoiesis are used to simulate the dynamics of the major hematopoietic lines in mice exposed to challenge acute irradiation following the chronic one Juxtaposition of the modeling results obtained and the relevant experimental data shows that the radiosensitization effect of chronic low-level short-term less than 1 month preirradiation on mice is due to increased radiosensitivity of lymphopoietic granulocytopoietic and erythropoietic systems accompanied by increased or close to the normal level radiosensitivity of thrombocytopoietic system which are induced by the above-indicated exposure In turn the radioprotection effect of chronic low-level long-term more than 1 month preirradiation on mice is caused by decreased radiosensitivity radioresistance of the granulocytopoietic system which

  1. DRINK: a biogeochemical source term model for low level radioactive waste disposal sites.

    PubMed

    Humphreys, P; McGarry, R; Hoffmann, A; Binks, P

    1997-07-01

    Interactions between element chemistry and the ambient geochemistry play a significant role in the control of radionuclide migration in the geosphere. These same interactions influence radionuclide release from near surface, low level radioactive waste, disposal sites once physical containment has degraded. In situations where LLW contains significant amounts of metal and organic materials such as cellulose, microbial degradation in conjunction with corrosion can significantly perturb the ambient geochemistry. These processes typically produce a transition from oxidising to reducing conditions and can influence radionuclide migration through changes in both the dominant radionuclide species and mineral phases. The DRINK (DRIgg Near field Kinetic) code is a biogeochemical transport code designed to simulate the long term evolution of the UK low level radioactive waste disposal site at Drigg. Drigg is the UK's principal solid low level radioactive waste disposal site and has been receiving waste since 1959. The interaction between microbial activity, the ambient geochemistry and radionuclide chemistry is central to the DRINK approach with the development of the ambient pH, redox potential and bulk geochemistry being directly influenced by microbial activity. This paper describes the microbial aspects of the code, site data underpinning the microbial model, the microbiology/chemistry interface and provides an example of the code in action. PMID:9340003

  2. Coupling MD Simulations and X-ray Absorption Spectroscopy to Study Ions in Solution

    SciTech Connect

    Marcos, E. Sanchez; Beret, E. C.; Martinez, J. M.; Pappalardo, R. R.; Ayala, R.; Munoz-Paez, A.

    2007-11-29

    The structure of ionic solutions is a key-point in understanding physicochemical properties of electrolyte solutions. Among the reduced number of experimental techniques which can supply direct information on the ion environment, X-ray Absorption techniques (XAS) have gained importance during the last decades although they are not free of difficulties associated to the data analysis leading to provide reliable structures. Computer simulations of ions in solution is a theoretical alternative to provide information on the solvation structure. Thus, the use of computational chemistry can increase the understanding of these systems although an accurate description of ionic solvation phenomena represents nowadays a significant challenge to theoretical chemistry. We present: (a) the assignment of features in the XANES spectrum to well defined structural motif in the ion environment, (b) MD-based evaluation of EXAFS parameters used in the fitting procedure to make easier the structural resolution, and (c) the use of the agreement between experimental and simulated XANES spectra to help in the choice of a given intermolecular potential for Computer Simulations. Chemical problems examined are: (a) the identification of the second hydration shell in dilute aqueous solutions of highly-charged cations, such as Cr{sup 3+}, Rh{sup 3+}, Ir{sup 3+}, (b) the invisibility by XAS of certain structures characterized by Computer Simulations but exhibiting high dynamical behavior and (c) the solvation of Br{sup -} in acetonitrile.

  3. Prediction of Solution Properties of Flexible-Chain Polymers: A Computer Simulation Undergraduate Experiment

    ERIC Educational Resources Information Center

    de la Torre, Jose Garcia; Cifre, Jose G. Hernandez; Martinez, M. Carmen Lopez

    2008-01-01

    This paper describes a computational exercise at undergraduate level that demonstrates the employment of Monte Carlo simulation to study the conformational statistics of flexible polymer chains, and to predict solution properties. Three simple chain models, including excluded volume interactions, have been implemented in a public-domain computer…

  4. Computer simulation of cascade damage in -iron with carbon in solution

    SciTech Connect

    Calder, Andrew F; Bacon, David J; Barashev, Aleksandr; Osetsky, Nickolai

    2008-01-01

    Computer simulation of cascade damage in -iron with carbon in solution Original Research Article Journal of Nuclear Materials, Volume 382, Issues 2 3, 1 December 2008, Pages 91-95 Andrew F. Calder, David J. Bacon, Alexander V. Barashev, Yuri N. Osetsky

  5. Solute transport with equilibrium aqueous complexation and either sorption or ion exchange: Simulation methodology and applications

    USGS Publications Warehouse

    Lewis, F.M.; Voss, C.I.; Rubin, J.

    1987-01-01

    Methodologies that account for specific types of chemical reactions in the simulation of solute transport can be developed so they are compatible with solution algorithms employed in existing transport codes. This enables the simulation of reactive transport in complex multidimensional flow regimes, and provides a means for existing codes to account for some of the fundamental chemical processes that occur among transported solutes. Two equilibrium-controlled reaction systems demonstrate a methodology for accommodating chemical interaction into models of solute transport. One system involves the sorption of a given chemical species, as well as two aqueous complexations in which the sorbing species is a participant. The other reaction set involves binary ion exchange coupled with aqueous complexation involving one of the exchanging species. The methodology accommodates these reaction systems through the addition of nonlinear terms to the transport equations for the sorbing species. Example simulation results show (1) the effect equilibrium chemical parameters have on the spatial distributions of concentration for complexing solutes; (2) that an interrelationship exists between mechanical dispersion and the various reaction processes; (3) that dispersive parameters of the porous media cannot be determined from reactive concentration distributions unless the reaction is accounted for or the influence of the reaction is negligible; (4) how the concentration of a chemical species may be significantly affected by its participation in an aqueous complex with a second species which also sorbs; and (5) that these coupled chemical processes influencing reactive transport can be demonstrated in two-dimensional flow regimes. ?? 1987.

  6. Multicomponent leach tests in Standard Canadian Shield Saline Solution on glasses containing simulated nuclear waste

    SciTech Connect

    Heimann, R.B.; Wood, D.D.; Hamon, R.F.

    1984-01-01

    Leaching experiments on borosilicate glass frit and simulated nuclear waste glasses were performed as a preliminary to leaching experiments on glasses incorporating radioactive waste. The experimental design included (1) simulated waste glass, (2) ASTM Grade-2 titanium container material, (3) clay buffer material, (4) Standard Canadian Shield Saline Solution, and (5) granitic rock. Cumulative fractions of release for boron were determined, as well as the solution concentrations of silicon, iron, strontium and cesium. The leach rates for boron after 28 d were approximately 5 x 10/sup -6/ kg x m/sup -2/ x s/sup -1/ in Hastelloy vessels. There is an apparently strong relationship between the clay/groundwater ratio, the concentration of iron in the solution, and the concentrations of silicon, strontium, and cesium.

  7. Molecular dynamics simulations of the surface tension and structure of salt solutions and clusters.

    PubMed

    Sun, Lu; Li, Xin; Hede, Thomas; Tu, Yaoquan; Leck, Caroline; Ågren, Hans

    2012-03-15

    Sodium halides, which are abundant in sea salt aerosols, affect the optical properties of aerosols and are active in heterogeneous reactions that cause ozone depletion and acid rain problems. Interfacial properties, including surface tension and halide anion distributions, are crucial issues in the study of the aerosols. We present results from molecular dynamics simulations of water solutions and clusters containing sodium halides with the interatomic interactions described by a conventional force field. The simulations reproduce experimental observations that sodium halides increase the surface tension with respect to pure water and that iodide anions reach the outermost layer of water clusters or solutions. It is found that the van der Waals interactions have an impact on the distribution of the halide anions and that a conventional force field with optimized parameters can model the surface tension of the salt solutions with reasonable accuracy. PMID:22352372

  8. Low-level radioactive waste: An introductory overview

    NASA Astrophysics Data System (ADS)

    Godbee, H. W.; Kibbey, A. H.

    In 1980, the accumulated volume of buried low-level waste (LLW) in the United States amounted to over 92,000 cu m. Of this, 49,700 cu m was attributed to the US commercial fuel cycle, 36,400 cu m to institutional and industrial, and 76,300 cu m to government activities. In addition, there was another 6500 cu m of LLW sent to commercial burial grounds from government agencies or other licensed activities (e.g., fabrication of fuel for foreign reactors). If no more land is licensed for commercial burial, Barnwell with its limited waste acceptance will be the only site still operating in the year 2000. Of the DOE sites, only NTS and Hanford will have ample land. All the other principal DOE sites except LASL will be exhausted and this site will have about 7 of usable land left.

  9. Overview of resuspension model: application to low level waste management

    SciTech Connect

    Healy, J.W.

    1980-01-01

    Resuspension is one of the potential pathways to man for radioactive or chemical contaminants that are in the biosphere. In waste management, spills or other surface contamination can serve as a source for resuspension during the operational phase. After the low-level waste disposal area is closed, radioactive materials can be brought to the surface by animals or insects or, in the long term, the surface can be removed by erosion. Any of these methods expose the material to resuspension in the atmosphere. Intrusion into the waste mass can produce resuspension of potential hazard to the intruder. Removal of items from the waste mass by scavengers or archeologists can result in potential resuspension exposure to others handling or working with the object. The ways in which resuspension can occur are wind resuspension, mechanical resuspension and local resuspension. While methods of predicting exposure are not accurate, they include the use of the resuspension factor, the resuspension rate and mass loading of the air.

  10. WRAP low level waste (LLW) glovebox acceptance test report

    SciTech Connect

    Leist, K.J.

    1998-02-17

    In June 28, 1997, the Low Level Waste (LLW) glovebox was tested using glovebox acceptance test procedure 13031A-85. The primary focus of the glovebox acceptance test was to examine control system interlocks, display menus, alarms, and operator messages. Limited mechanical testing involving the drum ports, hoists, drum lifter, compacted drum lifter, drum tipper, transfer car, conveyors, lidder/delidder device and the supercompactor were also conducted. As of November 24, 1997, 2 of the 131 test exceptions that affect the LLW glovebox remain open. These items will be tracked and closed via the WRAP Master Test Exception Database. As part of Test Exception resolution/closure the responsible individual closing the Test Exception performs a retest of the affected item(s) to ensure the identified deficiency is corrected, and, or to test items not previously available to support testing. Test Exceptions are provided as appendices to this report.

  11. Luminous fabric devices for wearable low-level light therapy

    PubMed Central

    Shen, Jing; Chui, Chunghin; Tao, Xiaoming

    2013-01-01

    In this paper, a flexible luminous fabric device was developed and investigated for wearable three-dimensionally fitted low-level light therapy. The fabric device exhibited excellent optical and thermal properties. Its optical power density and operating temperature were stable during usage for 10 hours. In vitro experiments demonstrated a significant increase in collagen production in human fibroblast irradiated by the fabric device, compared with the fibroblast without light irradiation. A series of tests were conducted for the safety of the fabric for human skin contact according to ISO standard ISO 10993-1:2003. The results showed that there was no potential hazard when the luminous fabrics were in direct contact with human skin. PMID:24409391

  12. Low-level stored waste inspection using mobile robots

    SciTech Connect

    Byrd, J.S.; Pettus, R.O.

    1996-06-01

    A mobile robot inspection system, ARIES (Autonomous Robotic Inspection Experimental System), has been developed for the U.S. Department of Energy to replace human inspectors in the routine, regulated inspection of radioactive waste stored in drums. The robot will roam the three-foot aisles of drums, stacked four high, making decisions about the surface condition of the drums and maintaining a database of information about each drum. A distributed system of onboard and offboard computers will provide versatile, friendly control of the inspection process. This mobile robot system, based on a commercial mobile platform, will improve the quality of inspection, generate required reports, and relieve human operators from low-level radioactive exposure. This paper describes and discusses primarily the computer and control processes for the system.

  13. Role of reactive oxygen species in low level light therapy

    NASA Astrophysics Data System (ADS)

    Chen, Aaron Chi-Hao; Huang, Ying-Ying; Arany, Praveen R.; Hamblin, Michael R.

    2009-02-01

    This review will focus on the role of reactive oxygen species in the cellular and tissue effects of low level light therapy (LLLT). Coincidentally with the increase in electron transport and in ATP, there has also been observed by intracellular fluorescent probes and electron spin resonance an increase in intracellular reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, singlet oxygen and hydroxyl radical. ROS scavengers, antioxidants and ROS quenchers block many LLLT processes. It has been proposed that light between 400-500- nm may produce ROS by a photosensitization process involving flavins, while longer wavelengths may directly produce ROS from the mitochondria. Several redox-sensitive transcription factors are known such as NF-kB and AP1, that are able to initiate transcription of genes involved in protective responses to oxidative stress. It may be the case that LLLT can be pro-oxidant in the short-term, but anti-oxidant in the long-term.

  14. Biochemical effects of low level exposure to soman vapour.

    PubMed

    Bajgar, J; Sevelová, L; Krejcová, G; Fusek, J; Vachek, J; Kassa, J; Herink, J; de Jong, L P A; Benschop, H

    2004-03-01

    The aim of this study was to demonstrate changes in acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities, tyrosine aminotransferase activity (TAT) and plasma corticosterone level, neuroexcitability and behavior following 24 hours and 4 weeks of soman sublethal inhalation exposure at low level. AChE activity in erythrocytes and BuChE activity in plasma was decreased (dependent on the concentration of soman) 24 h and 4 weeks after the exposure. Similar decrease in AChE activity in different brain parts was observed. One of stressogenic parameters (TAT) was changed after 24 h exposure only. 4 weeks after the exposure, these parameters (corticosterone and TAT) were in the range of normal values. Behaviour of experimental animals was changed 24 h after the exposure persisting 4 weeks after the exposure as well as neuroexcitability. PMID:15141961

  15. Characteristics of low-level radioactive decontamination waste

    SciTech Connect

    Akers, D.W.; McConnell, J.W. Jr.; Morcos, N. )

    1993-02-01

    This document addresses the work performed during fiscal year 1992 at the Idaho National Engineering Laboratory by the Low-Level Radioactive Waste -- Decontamination Waste Program (FIN A6359), which is funded by the US Nuclear Regulatory Commission. The program evaluates the physical stability and leachability of solidified waste streams generated in the decontamination process of primary coolant systems in operating nuclear power stations. The data in this document include the chemical composition and characterization of waste streams from Peach Bottom Atomic Power Station Unit 3 and from Nine Mile Point Nuclear Plant Unit 1. The results of compressive strength testing on immersed and unimmersed solidified waste-form specimens from peach Bottom, and the results of leachate analysis are addressed. Cumulative fractional release rates and leachability indexes of those specimens were calculated and are included in this report.

  16. On low-level tritium measurements with LSC Quantulus

    PubMed

    Schafer; Hebert; Zeiske

    2000-07-01

    Low-level measurements of 3H have been made with the "Quantulus" liquid scintillation counter (LSC) using different scintillation cocktails together with selected types of counting vials. Comparisons were made between counters at the underground laboratory "Felsenkeller" (110 m water equivalent) and in an above ground laboratory (0 m water equivalent) of the TU Freiberg. In the underground laboratory, the background is strongly influenced by the beta-decay of the 220Rn-daughter 212Pb (T(1/2) = 10.6 h) from the laboratory air, stimulating luminescence irradiation in the vial. The effective background count rate in the 3H-window (having subtracted the "luminescence effect") in the underground laboratory is two times lower than that in the above ground laboratory due to the better shielding of cosmic rays. PMID:10879878

  17. The use of low-level jets by migrating birds.

    PubMed

    Liechti, F; Schaller, E

    1999-11-01

    Birds flying at high altitudes have occasionally been observed above mountain areas and the open sea. For the first time the regular occurrence of migrating birds flying within a low-level jet at heights of 5000 to almost 9000 m asl. have now been verified by radar above the Negev desert in southern Israel. Tracks of rather large birds with wing-beat frequencies of 5-6 Hz were measured to have horizontal flight speeds up to 50 m/s. Visual observations, seasonal occurrence, and wing-beat frequencies allowed to associate them with small species of the order Ciconiiformes (mainly Ardeidae) and possibly with members of the Laro-Limicolae group. These wading birds seem prone to continuing nocturnal migration into daytime under favorable conditions and to make use of high wind speeds at sometimes extreme altitudes. PMID:10551952

  18. Low-level light therapy (LLLT) for cosmetics and dermatology

    NASA Astrophysics Data System (ADS)

    Sawhney, Mossum K.; Hamblin, Michael R.

    2014-02-01

    Over the last few years, low-level laser (light) therapy (LLLT) has been demonstrated to be beneficial to the field of aesthetic medicine, specifically aesthetic dermatology. LLLT encompasses a broad spectrum of procedures, primarily cosmetic, which provide treatment options for a myriad of dermatological conditions. Dermatological disorders involving inflammation, acne, scars, aging and pigmentation have been investigated with the assistance of animal models and clinical trials. The most commercially successful use of LLLT is for managing alopecia (hair loss) in both men and women. LLLT also seems to play an influential role in procedures such as lipoplasty and liposuction, allowing for noninvasive and nonthermal methods of subcutaneous fat reduction. LLLT offers a means to address such conditions with improved efficacy versatility and no known side-effects; however comprehensive literature reports covering the utility of LLLT are scarce and thus the need for coverage arises.

  19. Observation of Low Level Heating in an Erupting Prominence

    NASA Technical Reports Server (NTRS)

    Kucera, Therese A.

    2007-01-01

    We present multi-wavelength observations of low level heating in an erupting prominence observed in the UV and EUV over a wide range of temperatures and wavelengths by SOHO's SUMER instrument, TRACE and also in H-alpha by the Yunnan Astronomical Observatory. The eruption occurred on 2004 April 30. The heating is relatively mild, leading only to the ionization of neutral hydrogen and probably helium. It is also localized, occurring along the bottom edge of the erupting prominence and in a kink-like feature in the prominence. The heating is revealed as a decrease in the Lyman absorption. This decrease results in an apparent increase in emission in all the lines observed by SUMER, especially those formed at temperatures -1 0A5. However, this is due to the disappearance of cooler absorbing material in the prominence rather than an increase in these higher temperature species.

  20. Observation of Low Level Heating in an Erupting Prominence

    NASA Technical Reports Server (NTRS)

    Kucera, Theresa; Landi, E.

    2007-01-01

    We present multi-wavelength observations of low level heating in an erupting prominence observed in the UV and EUV over a wide range of temperatures and wavelengths by SOHO's SUMER instrument, TRACE and also in H-alpha by the Yunnan Astronomical Observatory. The eruption occurred on 2004 April 30. The heating is relatively mild, leading only to the ionization of neutral hydrogen and probably helium. It is also localized, occurring along the bottom edge of the erupting prominence and in a kink-like feature in the prominence. The heating is revealed as a decrease in the Lyman absorption. This decrease results in an apparent increase in emission in all the lines observed by SUMER, especially those formed at temperatures approx. 10(exp 5). However, this is due to the disappearance of cooler absorbing material in the prominence rather than an increase in these higher temperature species.

  1. Low-level radioactive waste form qualification testing

    SciTech Connect

    Sohal, M.S.; Akers, D.W.

    1998-06-01

    This report summarizes activities that have already been completed as well as yet to be performed by the Idaho National Engineering and Environmental Laboratory (INEEL) to develop a plan to quantify the behavior of radioactive low-level waste forms. It briefly describes the status of various tasks, including DOE approval of the proposed work, several regulatory and environmental related documents, tests to qualify the waste form, preliminary schedule, and approximate cost. It is anticipated that INEEL and Brookhaven National Laboratory will perform the majority of the tests. For some tests, services of other testing organizations may be used. It should take approximately nine months to provide the final report on the results of tests on a waste form prepared for qualification. It is anticipated that the overall cost of the waste quantifying service is approximately $150,000. The following tests are planned: compression, thermal cycling, irradiation, biodegradation, leaching, immersion, free-standing liquid tests, and full-scale testing.

  2. Effect of interstitial low level laser stimulation in skin density

    NASA Astrophysics Data System (ADS)

    Jang, Seulki; Ha, Myungjin; Lee, Sangyeob; Yu, Sungkon; Park, Jihoon; Radfar, Edalat; Hwang, Dong Hyun; Lee, Han A.; Kim, Hansung; Jung, Byungjo

    2016-03-01

    As the interest in skin was increased, number of studies on skin care also have been increased. The reduction of skin density is one of the symptoms of skin aging. It reduces elasticity of skin and becomes the reason of wrinkle formation. Low level laser therapy (LLLT) has been suggested as one of the effective therapeutic methods for skin aging as in hasten to change skin density. This study presents the effect of a minimally invasive laser needle system (MILNS) (wavelength: 660nm, power: 20mW) in skin density. Rabbits were divided into three groups. Group 1 didn't receive any laser stimulation as a control group. Group 2 and 3 as test groups were exposed to MILNS with energy of 8J and 6J on rabbits' dorsal side once a week, respectively. Skin density of rabbits was measured every 12 hours by using an ultrasound skin scanner.

  3. Screening Experiments for Removal of Low-Level Tritiated Water

    SciTech Connect

    Kim, Yun Mi; Baney, Ronald; Powers, Kevin; Koopman, Ben; Tulenko, James

    2005-03-15

    Screening experiments for low levels of tritiated water (HTO) remediation based upon selective adsorption/desorption mechanisms utilizing equilibrium isotope effects have been carried out. Several organic and inorganic high surface area materials were investigated to assess their ability to selectively adsorb low concentrations of HTO. Ion-exchange resins with cation functionalities, chitosan, sodium alginate, and several inorganic media modified with metal cations exhibited promising results. Biomaterials, for example, chitosan and modified alginate, demonstrated positive results. Based on the literature and our preliminary testing, we postulate four possible mechanisms for selected tritium adsorption: hydrogen ion exchange, HTO coordination with surface cation sites, hydrogen bonding to surface basic sites, and secondary hydrogen bonding (structural water) in fine pores.

  4. Effects of high vs low-level radiation exposure

    SciTech Connect

    Bond, V.P.

    1983-01-01

    In order to appreciate adequately the various possible effects of radiation, particularly from high-level vs low-level radiation exposure (HLRE, vs LLRE), it is necessary to understand the substantial differences between (a) exposure as used in exposure-incidence curves, which are always initially linear and without threshold, and (b) dose as used in dose-response curves, which always have a threshold, above which the function is curvilinear with increasing slope. The differences are discussed first in terms of generally familiar nonradiation situations involving dose vs exposure, and then specifically in terms of exposure to radiation, vs a dose of radiation. Examples are given of relevant biomedical findings illustrating that, while dose can be used with HLRE, it is inappropriate and misleading the LLRE where exposure is the conceptually correct measure of the amount of radiation involved.

  5. Low Level Laser Therapy: laser radiation absorption in biological tissues

    NASA Astrophysics Data System (ADS)

    Di Giacomo, Paola; Orlando, Stefano; Dell'Ariccia, Marco; Brandimarte, Bruno

    2013-07-01

    In this paper we report the results of an experimental study in which we have measured the transmitted laser radiation through dead biological tissues of various animals (chicken, adult and young bovine, pig) in order to evaluate the maximum thickness through which the power density could still produce a reparative cellular effect. In our experiments we have utilized a pulsed laser IRL1 ISO model (based on an infrared diode GaAs, λ=904 nm) produced by BIOMEDICA s.r.l. commonly used in Low Level Laser Therapy. Some of the laser characteristics have been accurately studied and reported in this paper. The transmission results suggest that even with tissue thicknesses of several centimeters the power density is still sufficient to produce a cell reparative effect.

  6. Low level laser therapy on injured rat muscle

    NASA Astrophysics Data System (ADS)

    Mantineo, M.; Pinheiro, J. P.; Morgado, A. M.

    2013-06-01

    Although studies show the clinical effectiveness of low level laser therapy (LLLT) in facilitating the muscle healing process, scientific evidence is still required to prove the effectiveness of LLLT and to clarify the cellular and molecular mechanisms triggered by irradiation. Here we evaluate the effect of different LLLT doses, using continuous illumination (830 nm), in the treatment of inflammation induced in the gastrocnemius muscle of Wistar rats, through the quantification of cytokines in systemic blood and histological analysis of muscle tissue. We verified that all applied doses produce an effect on reducing the number of inflammatory cells and the concentration of pro-inflammatory TNF-α and IL-1β cytokines. The best results were obtained for 40 mW. The results may suggest a biphasic dose response curve.

  7. Pyrochemical Processing for Low-Level Waste Production in PEACER

    SciTech Connect

    Byung Gi Park; Il Soon Hwang

    2002-07-01

    A pyrochemical partitioning process has been conceptually designed so that the transmutation of spent LWR fuels in PEACER can produce mainly low-level waste (Class C waste) for near-surface burial. Chloride salt technology developed for IFR has been employed as the baseline. Electrorefining, reductive extraction and salt recycling steps are used to construct overall flowsheet in order to support PEACER operation. The decontamination factor for transuranic elements was estimated based on both thermodynamic models and reported experimental data. It is expected that overall decontamination factor can be as high as 10{sup 5} for transuranic elements. Final wastes from pyrochemical processing for PEACER are noble metals, alkaline earth metal, and lanthanides. The final wastes are stabilized by mixing with zeolite and glass-frits such that concentration limit for class C waste can be met. The volume of Class C waste is estimated to be small enough to make PEACER concept valuable for densely populated countries. (authors)

  8. Optimising the Performance of the Low Level Waste Repository - 12144

    SciTech Connect

    Huntington, Amy; Baker, Andrew; Cummings, Richard; Shevelan, John; Sumerling, Trevor

    2012-07-01

    The Low Level Waste Repository (LLWR) is the United Kingdom's principal facility for the disposal of low-level waste (LLW). The LLWR made a major submission to its environmental regulator (the Environment Agency) on 1 May 2011, the LLWR's 2011 Environmental Safety Case (ESC). One of the key regulatory requirements is that all aspects of the construction, operation and closure of the disposal facility should be optimised. An optimised Site Development Plan for the repository was developed and produced as part of the ESC. The Site Development Plan covers all aspects of the construction, operation and closure of the disposal facility. This includes the management of past and future disposals, emplacement strategies, design of the disposal vaults, and the closure engineering for the site. The Site Development Plan also covers the period of active institutional control, when disposals at the site have ceased, but it is still under active management, and plans for the long-term sustainable use of the site. We have a practical approach to optimisation based on recorded judgements and realistic assessments of practicable options framed within the demands of UK policy for LLW management and the characteristics the LLWR site and existing elements of the facility. The final performance assessments undertaken for the ESC were based on the Site Development Plan. The ESC will be used as a tool to inform future decision-making concerning the repository design, operation and the acceptance of wastes, as set out in the evolving Site Development Plan. Maintaining the ESC is thus essential to ensure that the Site Development Plan takes account of an up-to-date understanding and analysis of environmental performance, and that the Plan continues to be optimised. (authors)

  9. Low-Level Cues and Ultra-Fast Face Detection

    PubMed Central

    Crouzet, Sébastien M.; Thorpe, Simon J.

    2011-01-01

    Recent experimental work has demonstrated the existence of extremely rapid saccades toward faces in natural scenes that can be initiated only 100 ms after image onset (Crouzet et al., 2010). These ultra-rapid saccades constitute a major challenge to current models of processing in the visual system because they do not seem to leave enough time for even a single feed-forward pass through the ventral stream. Here we explore the possibility that the information required to trigger these very fast saccades could be extracted very early on in visual processing using relatively low-level amplitude spectrum (AS) information in the Fourier domain. Experiment 1 showed that AS normalization can significantly alter face-detection performance. However, a decrease of performance following AS normalization does not alone prove that AS-based information is used (Gaspar and Rousselet, 2009). In Experiment 2, following the Gaspar and Rousselet paper, we used a swapping procedure to clarify the role of AS information in fast object detection. Our experiment is composed of three conditions: (i) original images, (ii) category swapped, in which the face image has the AS of a vehicle, and the vehicle has the AS of a face, and (iii) identity swapped, where the face has the AS of another face image, and the vehicle has the AS of another vehicle image. The results showed very similar levels of performance in the original and identity swapped conditions, and a clear drop in the category swapped condition. This result demonstrates that, in the early temporal window offered by the saccadic choice task, the visual saccadic system does indeed rely on low-level AS information in order to rapidly detect faces. This sort of crude diagnostic information could potentially be derived very early on in the visual system, possibly as early as V1 and V2. PMID:22125544

  10. Incineration of Low Level Radioactive Vegetation for Waste Volume Reduction

    SciTech Connect

    Malik, N.P.S.; Rucker, G.G.; Looper, M.G.

    1995-03-01

    The DOE changing mission at Savannah River Site (SRS) are to increase activities for Waste Management and Environmental Restoration. There are a number of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) locations that are contaminated with radioactivity and support dense vegetation, and are targeted for remediation. Two such locations have been studied for non-time critical removal actions under the National Contingency Plan (NCP). Both of these sites support about 23 plant species. Surveys of the vegetation show that radiation emanates mainly from vines, shrubs, and trees and range from 20,000 to 200,000 d/m beta gamma. Planning for removal and disposal of low-level radioactive vegetation was done with two principal goals: to process contaminated vegetation for optimum volume reduction and waste minimization, and for the protection of human health and environment. Four alternatives were identified as candidates for vegetation removal and disposal: chipping the vegetation and packing in carbon steel boxes (lined with synthetic commercial liners) and disposal at the Solid Waste Disposal Facility at SRS; composting the vegetation; burning the vegetation in the field; and incinerating the vegetation. One alternative `incineration` was considered viable choice for waste minimization, safe handling, and the protection of the environment and human health. Advantages and disadvantages of all four alternatives considered have been evaluated. For waste minimization and ultimate disposal of radioactive vegetation incineration is the preferred option. Advantages of incineration are that volume reduction is achieved and low-level radioactive waste are stabilized. For incineration and final disposal vegetation will be chipped and packed in card board boxes and discharged to the rotary kiln of the incinerator. The slow rotation and longer resident time in the kiln will ensure complete combustion of the vegetative material.

  11. Quantitative interpretation of molecular dynamics simulations for X-ray photoelectron spectroscopy of aqueous solutions.

    PubMed

    Olivieri, Giorgia; Parry, Krista M; Powell, Cedric J; Tobias, Douglas J; Brown, Matthew A

    2016-04-21

    Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy(XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyteinterface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquidinterface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer description of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (<300 eV) where the ad hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquidinterfaces are discussed. PMID:27389231

  12. Quantitative interpretation of molecular dynamics simulations for X-ray photoelectron spectroscopy of aqueous solutions

    NASA Astrophysics Data System (ADS)

    Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.; Brown, Matthew A.

    2016-04-01

    Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy (XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyte interface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquid interface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer description of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (<300 eV) where the ad hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquid interfaces are discussed.

  13. MEASUREMENTS TAKEN IN SUPPORT OF QUALIFICATION OF PROCESSING SAVANNAH RIVER SITE LOW-LEVEL LIQUID WASTE INTO SALTSTONE

    SciTech Connect

    Reigel, M.; Bibler, N.; Diprete, C.; Cozzi, A.; Staub, A.; Ray, J.

    2010-01-27

    The Saltstone Facility at the Savannah River Site (SRS) immobilizes low-level liquid waste into Saltstone to be disposed of in the Z-Area Saltstone Disposal Facility, Class Three Landfill. In order to meet the permit conditions and regulatory limits set by the South Carolina Department of Health and Environmental Control (SCDHEC), the Resource Conservation and Recovery Act (RCRA) and the Environmental Protection Agency (EPA), both the low-level salt solution and Saltstone samples are analyzed quarterly. Waste acceptance criteria (WAC) are designed to confirm the salt solution sample from the Tank Farm meets specific radioactive and chemical limits. The toxic characteristic leaching procedure (TCLP) is used to confirm that the treatment has immobilized the hazardous constituents of the salt solution. This paper discusses the methods used to characterize the salt solution and final Saltstone samples from 2007-2009.

  14. Vectra GSI, Inc. low-level waste melter testing Phase 1 test report

    SciTech Connect

    Stegen, G.E.; Wilson, C.N.

    1996-02-21

    A multiphase program was initiated in 1994 to test commercially available melter technologies for the vitrification of the low-level waste (LLW) stream from defense wastes stored in underground tanks at the Hanford Site in southeastern Washington State. Vectra GSI, Inc. was one of seven vendors selected for Phase 1 of the melter demonstration tests using simulated LLW that were completed during fiscal year 1995. The attached report prepared by Vectra GSI, Inc. describes results of melter testing using slurry feed and dried feeds. Results of feed drying and prereaction tests using a fluid bed calciner and rotary dryer also are described.

  15. Numerical Simulations of STOVL Hot Gas Ingestion in Ground Proximity Using a Multigrid Solution Procedure

    NASA Technical Reports Server (NTRS)

    Wang, Gang

    2003-01-01

    A multi grid solution procedure for the numerical simulation of turbulent flows in complex geometries has been developed. A Full Multigrid-Full Approximation Scheme (FMG-FAS) is incorporated into the continuity and momentum equations, while the scalars are decoupled from the multi grid V-cycle. A standard kappa-Epsilon turbulence model with wall functions has been used to close the governing equations. The numerical solution is accomplished by solving for the Cartesian velocity components either with a traditional grid staggering arrangement or with a multiple velocity grid staggering arrangement. The two solution methodologies are evaluated for relative computational efficiency. The solution procedure with traditional staggering arrangement is subsequently applied to calculate the flow and temperature fields around a model Short Take-off and Vertical Landing (STOVL) aircraft hovering in ground proximity.

  16. Local structure of the halite-sylvine solid solution according to the computer simulation data

    SciTech Connect

    Urusov, V. S. Leonenko, E. V.

    2008-09-15

    The structural, elastic, and thermodynamic properties of halite NaCl and sylvine KCl and the miscibility properties of the NaCl-KCl solid solution found by computer simulation are in good agreement with the experimental data. Analysis of the relaxation of the solid solution structure suggests that both anion and cation sublattices are distorted; however, the anion sublattice is distorted much more strongly. Calculations of the local bond valence at all types of ions in the solid solution show opposite deviations from the balance at cations, whereas the general balance is retained. The values of the electrostatic potential in the ion positions reflect weakening of bonding in the solid solution with respect to its pure components. In addition, with an increase in the average interatomic distance in the first coordination sphere around cations, the modulus of the electrostatic potential at cations decreases.

  17. Alternatives generation and analysis report for immobilized low-level waste interim storage architecture

    SciTech Connect

    Burbank, D.A., Westinghouse Hanford

    1996-09-01

    The Immobilized Low-Level Waste Interim Storage subproject will provide storage capacity for immobilized low-level waste product sold to the U.S. Department of Energy by the privatization contractor. This report describes alternative Immobilized Low-Level Waste storage system architectures, evaluation criteria, and evaluation results to support the Immobilized Low-Level Waste storage system architecture selection decision process.

  18. Use of boundary fluxes when simulating solute transport with the MODFLOW ground-water transport process

    USGS Publications Warehouse

    Konikow, L.F.; Hornberger, G.Z.

    2003-01-01

    This report describes modifications to a U.S. Geological Survey (USGS) threedimensional solute-transport model (MODFLOWGWT), which is incorporated into the USGS MODFLOW ground-water model as the Ground- Water Transport (GWT) Process. The modifications improve the capability of MODFLOW-GWT to accurately simulate solute transport in simulations that represent a nonzero flux across an aquifer boundary. In such situations, the new Boundary Flux Package (BFLX) will allow the user flexibility to assign the flux to specific cell faces, although that flexibility is limited for certain types of fluxes (such as recharge and evapotranspiration, which can only be assigned to the top face if either is to be represented as a boundary flux). The approach is consistent with that used in the MODPATH model. The application of the BFLX Package was illustrated using a test case in which the Lake Package was active. The results using the BFLX Package showed noticeably higher magnitudes of velocity in the cells adjacent to the lake than previous results without the BFLX Package. Consequently, solute was transported slightly faster through the lake-aquifer system when the BFLX Package is active. However, the overall solute distributions did not differ greatly from simulations made without using the BFLX Package.

  19. On-Site Decontamination System for Liquid Low Level Radioactive Waste - 13010

    SciTech Connect

    OSMANLIOGLU, Ahmet Erdal

    2013-07-01

    This study is based on an evaluation of purification methods for liquid low-level radioactive waste (LLLW) by using natural zeolite. Generally the volume of liquid low-level waste is relatively large and the specific activity is rather low when compared to other radioactive waste types. In this study, a pilot scale column was used with natural zeolite as an ion exchanger media. Decontamination and minimization of LLLW especially at the generation site decrease operational cost in waste management operations. Portable pilot scale column was constructed for decontamination of LLW on site. Effect of temperature on the radionuclide adsorption of the zeolite was determined to optimize the waste solution temperature for the plant scale operations. In addition, effect of pH on the radionuclide uptake of the zeolite column was determined to optimize the waste solution pH for the plant scale operations. The advantages of this method used for the processing of LLLW are discussed in this paper. (authors)

  20. Simulation of macromolecule self-assembly in solution: A multiscale approach

    NASA Astrophysics Data System (ADS)

    Lavino, Alessio D.; di Pasquale, Nicodemo; Carbone, Paola; Barresi, Antonello A.; Marchisio, Daniele L.

    2015-12-01

    One of the most common processes to produce polymer nanoparticles is to induce self-assembly by using the solvent-displacement method, in which the polymer is dissolved in a "good" solvent and the solution is then mixed with an "anti-solvent". The polymer ability to self-assemble in solution is therefore determined by its structural and transport properties in solutions of the pure solvents and at the intermediate compositions. In this work, we focus on poly-ɛ-caprolactone (PCL) which is a biocompatible polymer that finds widespread application in the pharmaceutical and biomedical fields, performing simulation at three different scales using three different computational tools: full atomistic molecular dynamics (MD), population balance modeling (PBM) and computational fluid dynamics (CFD). Simulations consider PCL chains of different molecular weight in solution of pure acetone (good solvent), of pure water (anti-solvent) and their mixtures, and mixing at different rates and initial concentrations in a confined impinging jets mixer (CIJM). Our MD simulations reveal that the nano-structuring of one of the solvents in the mixture leads to an unexpected identical polymer structure irrespectively of the concentration of the two solvents. In particular, although in pure solvents the behavior of the polymer is, as expected, very different, at intermediate compositions, the PCL chain shows properties very similar to those found in pure acetone as a result of the clustering of the acetone molecules in the vicinity of the polymer chain. We derive an analytical expression to predict the polymer structural properties in solution at different solvent compositions and use it to formulate an aggregation kernel to describe the self-assembly in the CIJM via PBM and CFD. Simulations are eventually validated against experiments.

  1. Simulation of macromolecule self-assembly in solution: A multiscale approach

    SciTech Connect

    Lavino, Alessio D. Barresi, Antonello A. Marchisio, Daniele L.; Pasquale, Nicodemo di; Carbone, Paola

    2015-12-17

    One of the most common processes to produce polymer nanoparticles is to induce self-assembly by using the solvent-displacement method, in which the polymer is dissolved in a “good” solvent and the solution is then mixed with an “anti-solvent”. The polymer ability to self-assemble in solution is therefore determined by its structural and transport properties in solutions of the pure solvents and at the intermediate compositions. In this work, we focus on poly-ε-caprolactone (PCL) which is a biocompatible polymer that finds widespread application in the pharmaceutical and biomedical fields, performing simulation at three different scales using three different computational tools: full atomistic molecular dynamics (MD), population balance modeling (PBM) and computational fluid dynamics (CFD). Simulations consider PCL chains of different molecular weight in solution of pure acetone (good solvent), of pure water (anti-solvent) and their mixtures, and mixing at different rates and initial concentrations in a confined impinging jets mixer (CIJM). Our MD simulations reveal that the nano-structuring of one of the solvents in the mixture leads to an unexpected identical polymer structure irrespectively of the concentration of the two solvents. In particular, although in pure solvents the behavior of the polymer is, as expected, very different, at intermediate compositions, the PCL chain shows properties very similar to those found in pure acetone as a result of the clustering of the acetone molecules in the vicinity of the polymer chain. We derive an analytical expression to predict the polymer structural properties in solution at different solvent compositions and use it to formulate an aggregation kernel to describe the self-assembly in the CIJM via PBM and CFD. Simulations are eventually validated against experiments.

  2. Investigation of the liquid low-level waste evaporator steam coil failure and supporting laboratory studies

    SciTech Connect

    Pawel, S.J.; Keiser, J.R.; Longmire, H.F.

    1995-05-01

    Using a remote video camera, the internals of a low-level waste evaporator tank (termed 2A2, type 304L stainless steel construction, known to have failed steam coils) were inspected. This inspection revealed at least three rather substantial holes as opposed to crack- or pit-like leak sites near the nominal solution level position on one particular steam coil. This section was removed from the evaporator vessel, and subsequent hot cell examination revealed extensive general corrosion on the process side of the coil with little or no attack on the steam side. Hot cell metallography confirmed intense general corrosion on the process side and, in addition, revealed shallow intergranular attack at the leading edge of corrosion. No pits or cracks were detected in this section of the steam coil. Laboratory corrosion tests with coupons of 304L (and other high-alloy materials) isothermally exposed in a range of solutions similar to those expected in the evaporator reveal only very low corrosion rates below 40% sodium hydroxide and the solution boiling point. However, {open_quotes}dried film{close_quotes} experiments revealed that much more dilute solutions became aggressive to stainless steel due to concentrating effects (evaporation and periodic wetting) at the air/solution interface. The high general corrosion rates observed on the failed coil section occurred at or near the air/solution interface and were attributed to such {open_quotes}splash zone{close_quotes} activity.

  3. Laboratory development of methods for centralized treatment of liquid low-level waste at Oak Ridge National Laboratory

    SciTech Connect

    Arnold, W.D.; Bostick, D.T.; Burgess, M.W.; Taylor, P.A.; Perona, J.J.; Kent, T.E.

    1994-10-01

    Improved centralized treatment methods are needed in the management of liquid low-level waste (LLLW) at Oak Ridge National Laboratory (ORNL). LLLW, which usually contains radioactive contaminants at concentrations up to millicurie-per-liter levels, has accumulated in underground storage tanks for over 10 years and has reached a volume of over 350,000 gal. These wastes have been collected since 1984 and are a complex mixture of wastes from past nuclear energy research activities. The waste is a highly alkaline 4-5 M NaNO{sub 3} solution with smaller amounts of other salts. This type of waste will continue to be generated as a consequence of future ORNL research programs. Future LLLW (referred to as newly generated LLLW or NGLLLW) is expected to a highly alkaline solution of sodium carbonate and sodium hydroxide with a smaller concentration of sodium nitrate. New treatment facilities are needed to improve the manner in which these wastes are managed. These facilities must be capable of separating and reducing the volume of radioactive contaminants to small stable waste forms. Treated liquids must meet criteria for either discharge to the environment or solidification for onsite disposal. Laboratory testing was performed using simulated waste solutions prepared using the available characterization information as a basis. Testing was conducted to evaluate various methods for selective removal of the major contaminants. The major contaminants requiring removal from Melton Valley Storage Tank liquids are {sup 90}Sr and {sup 137}Cs. Principal contaminants in NGLLLW are {sup 9O}Sr, {sup 137}Cs, and {sup 106}Ru. Strontium removal testing began with literature studies and scoping tests with several ion-exchange materials and sorbents.

  4. An Investigation of Topography Modulated Low Level Moisture Convergence Patterns in the Southern Appalachians Using WRF

    NASA Astrophysics Data System (ADS)

    Wilson, A. M.; Duan, Y.; Barros, A.

    2015-12-01

    The Southern Appalachian Mountains (SAM) region is a biodiversity hot-spot that is vulnerable to land use/land cover changes due to its proximity to the rapidly growing population in the Southeast U.S. Persistent near surface moisture and associated microclimates observed in this region have been documented since the colonization of the area. The landform in this area, in particular in the inner mountain region, is highly complex with nested valleys and ridges. The geometry of the terrain causes distinct diurnal and seasonal local flow patterns that result in highly complex interactions of this low level moisture with meso- and synoptic-scale cyclones passing through the region. The Weather Research and Forecasting model (WRF) was used to conduct high resolution simulations of several case studies of warm season precipitation in the SAM with different synoptic-scale conditions to investigate this interaction between local and larger-scale flow patterns. The aim is to elucidate the microphysical interactions among these shallow orographic clouds and preexisting precipitating cloud systems and identify uncertainties in the model microphysics using in situ measurements. Findings show that ridge-valley precipitation gradients, in particular the "reverse" to the classical orographic effect observed in inner mountain valleys, is linked to horizontal heterogeneity in the vertical structure of low level cloud and precipitation promoted through landform controls on local flow. Moisture convergence patterns follow the peaks and valleys as represented by WRF terrain, and the topography effectively controls their timing and spatial structure. The simulations support the hypothesis that ridge-valley precipitation gradients, and in particular the reverse orographic enhancement effect in inner mountain valleys, is linked to horizontal heterogeneity in the vertical structure of low level clouds and precipitation promoted through landform controls on moisture convergence.

  5. Analytical estimates of radial segregation in Bridgman growth from low-level steady and periodic accelerations

    NASA Technical Reports Server (NTRS)

    Naumann, Robert J.; Baugher, Charles

    1992-01-01

    Approximate analytical solutions are developed that are mathematically tractable but provide the elements of CFD models for estimating convective flows subjected to low-level accelerations. The estimates are applicable to dilute systems that have horizontal temperature gradients in the vertical Bridgman configuration. The Navier-Stokes momentum equation is solved in 1D and subsequently in 2D by the first-order perturbation method. The analysis used is the case of plane-front solidification of a dilute system in the vertical thermally stable configuration. The model is found to predict the degree of radial segregation within a factor of two for a range of material and processing parameters. The method provides detailed information on the effects of processing on solute distribution in the grown crystal which are of interest in the orbital experiments emphasizing the control of radial segregation.

  6. Ab initio molecular dynamics simulation of aqueous solution of nitric oxide in different formal oxidation states

    NASA Astrophysics Data System (ADS)

    Venâncio, Mateus F.; Rocha, Willian R.

    2015-10-01

    Ab initio molecular dynamics simulations were used to investigate the early chemical events involved in the dynamics of nitric oxide (NOrad), nitrosonium cation (NO+) and nitroxide anion (NO-) in aqueous solution. The NO+ ion is very reactive in aqueous solution having a lifetime of ∼4 × 10-13 s, which is shorter than the value of 3 × 10-10 s predicted experimentally. The NO+ reacts generating the nitrous acid as an intermediate and the NO2- ion as the final product. The dynamics of NOrad revealed the reversibly formation of a transient anion radical species HONOrad -.

  7. Technical issues in licensing low-level radioactive waste facilities

    SciTech Connect

    Junkert, R.

    1993-03-01

    The California Department of Health Service spent two years in the review of an application for a low-level radioactive waste disposal facility in California. During this review period a variety of technical issues had to be evaluated and resolved. One of the first issues was the applicability and use of NRC guidance documents for the development of LLW disposal facilities. Other technical issues that required intensive evaluations included surface water hydrology, seismic investigation, field and numerical analysis of the unsaturated zone, including a water infiltration test. Source term verification became an issue because of one specific isotope that comprised more than 90% of the curies projected for disposal during the operational period. The use of trench liners and the proposed monitoring of the unsaturated zone were reviewed by a highly select panel of experts to provide guidance on the need for liners and to ensure that the monitoring system was capable of monitoring sufficient representative areas for radionuclides in the soil, soil gas, and soil moisture. Finally, concerns about the quality of the preoperational environmental monitoring program, including data, sample collection procedures, laboratory analysis, data review and interpretation and duration of monitoring caused a significant delay in completing the licensing review.

  8. Low-level waste minimization at the Y-12 Plant

    SciTech Connect

    Koger, J.

    1993-03-01

    The Y-12 Development Waste Minimization Program is used as a basis for defining new technologies and processes that produce minimum low-level wastes (hazardous, mixed, radioactive, and industrial) for the Y-12 Plant in the future and for Complex-21 and that aid in decontamination and decommissioning (D and D) efforts throughout the complex. In the past, the strategy at the Y-12 Plant was to treat the residues from the production processes using chemical treatment, incineration, compaction, and other technologies, which often generated copious quantities of additional wastes and, with the exception of highly valuable materials such as enriched uranium, incorporated very little recycle in the process. Recycle, in this context, is defined as material that is put back into the process before it enters a waste stream. Additionally, there are several new technology drivers that have recently emerged with the changing climate in the Nuclear Weapons Complex such as Complex 21 and D and D technologies and an increasing number of disassemblies. The hierarchies of concern in the waste minimization effort are source reduction, recycle capability, treatment simplicity, and final disposal difficulty with regard to Complex 21, disassembly efforts, D and D, and, to a lesser extent, weapons production. Source reduction can be achieved through substitution of hazardous substances for nonhazardous materials, and process changes that result in less generated waste.

  9. Evaluation of Low-Level Laser Therapy in TMD Patients

    PubMed Central

    Ayyildiz, Simel; Emir, Faruk; Sahin, Cem

    2015-01-01

    Light amplification by stimulated emission of radiation (laser) is one of the most recent treatment modalities in dentistry. Low-level laser therapy (LLLT) is suggested to have biostimulating and analgesic effects through direct irradiation without causing thermal response. There are few studies that have investigated the efficacy of laser therapy in temporomandibular disorders (TMD), especially in reduced mouth opening. The case report here evaluates performance of LLLT with a diode laser for temporomandibular clicking and postoperative findings were evaluated in two cases of TMD patients. First patient had a history of limited mouth opening and pain in temporomandibular joint (TMJ) region since nine months. Second patient's main complaint was his restricted mouth opening, which was progressed in one year. LLLT was performed with a 685 nm red probed diode laser that has an energy density of 6.2 J/cm2, three times a week for one month, and application time was 30 seconds (685 nm, 25 mW, 30 s, 0.02 Hz, and 6.2 J/cm2) (BTL-2000, Portative Laser Therapy Device). The treatment protocol was decided according to the literature. One year later patients were evaluated and there were no changes. This application suggested that LLLT is an appropriate treatment for TMD related pain and limited mouth opening and should be considered as an alternative to other methods. PMID:26587294

  10. Recent international developments in low-level waste disposal

    SciTech Connect

    Mitchell, S.J.; Lakey, L.T.; Harmon, K.M.

    1986-11-01

    Recent international developments in low-level waste (LLW) disposal have included a move away from ocean dumping and a trend towards engineered and deeper dispoosal. Siting efforts have accelerated as interim storage facilities and existing sites reach capacity. The suspension of ocean dumping by the London Dumping Conventions of 1983 and 1985 has affected the LLW disposal practices of several countries, including the United Kingdom, Belgium, the Netherlands, Switzerland, and Japan. Their plans now include disposal in trenches, shallow concrete pits, deep mines, sub-seabed caverns, horizontal mountain tunnels, and long-term storage facilities. Other recent developments include selection of the semi-desert Vaalputs site in South Africa, licensing activities for the Konrad mine site in the Federal Republic of Germany, design of at-reactor sites in Finland, and construction of a Baltic Sea site in Sweden. Also, the French have recently selected the Aube site for engineered disposal in monoliths and tumuli, now used at the La Manche site.

  11. Honeybees as monitors of low levels of radioactivity

    SciTech Connect

    Simmons, M.A. ); Bromenshenk, J.J.; Gudatis, J.L. . Dept. of Zoology)

    1990-07-01

    Large-scale environmental monitoring programs rely on sampling many media -- air, water, food, et cetera -- from a large network of sampling stations. For describing the total region possibly impacted by contaminants, the most efficient sampler would be one that covered a large region and simultaneously sampled many different media, such as water, air, soil, and vegetation. Honeybees have been shown to be useful monitors of the environment in this context for detecting both radionuclides and heavy metals. This study sought to determine the effectiveness of honeybees as monitors of low levels of radioactivity in the form of tritium and gamma-emitting radionuclides. For the study, approximately 50 honeybee colonies were placed on the Hanford Site and along the Columbia River in areas downwind of the site. The mini-hive colonies were sampled after 1 month and tested for tritium and for gamma-emitting radionuclides. From this and other studies, it is known that honeybees can be used to detect radionuclides present in the environment. Their mobility and their ability to integrate all exposure pathways could expand and add another level of confidence to the present monitoring program. 6 refs., 1 fig., 2 tabs.

  12. Factors associated with low levels of aerobic fitness among adolescents

    PubMed Central

    Gonçalves, Eliane Cristina de Andrade; Silva, Diego Augusto Santos

    2016-01-01

    Abstract Objective: To evaluate the prevalence of low aerobic fitness levels and to analyze the association with sociodemographic factors, lifestyle and excess body fatness among adolescents of southern Brazil. Methods: The study included 879 adolescents aged 14-19 years the city of São José/SC, Brazil. The aerobic fitness was assessed by Canadian modified test of aerobic fitness. Sociodemographic variables (skin color, age, sex, study turn, economic level), sexual maturation and lifestyle (eating habits, screen time, physical activity, consumption of alcohol and tobacco) were assessed by a self-administered questionnaire. Excess body fatness was evaluated by sum of skinfolds triceps and subscapular. We used logistic regression to estimate odds ratios and 95% confidence intervals. Results: Prevalence of low aerobic fitness level was 87.5%. The girls who spent two hours or more in front screen, consumed less than one glass of milk by day, did not smoke and had an excess of body fatness had a higher chance of having lower levels of aerobic fitness. White boys with low physical activity had had a higher chance of having lower levels of aerobic fitness. Conclusions: Eight out of ten adolescents were with low fitness levels aerobic. Modifiable lifestyle factors were associated with low levels of aerobic fitness. Interventions that emphasize behavior change are needed. PMID:26743851

  13. Selected radionuclides important to low-level radioactive waste management

    SciTech Connect

    1996-11-01

    The purpose of this document is to provide information to state representatives and developers of low level radioactive waste (LLW) management facilities about the radiological, chemical, and physical characteristics of selected radionuclides and their behavior in the environment. Extensive surveys of available literature provided information for this report. Certain radionuclides may contribute significantly to the dose estimated during a radiological performance assessment analysis of an LLW disposal facility. Among these are the radionuclides listed in Title 10 of the Code of Federal Regulations Part 61.55, Tables 1 and 2 (including alpha emitting transuranics with half-lives greater than 5 years). This report discusses these radionuclides and other radionuclides that may be significant during a radiological performance assessment analysis of an LLW disposal facility. This report not only includes essential information on each radionuclide, but also incorporates waste and disposal information on the radionuclide, and behavior of the radionuclide in the environment and in the human body. Radionuclides addressed in this document include technetium-99, carbon-14, iodine-129, tritium, cesium-137, strontium-90, nickel-59, plutonium-241, nickel-63, niobium-94, cobalt-60, curium -42, americium-241, uranium-238, and neptunium-237.

  14. Investigation of the low-level modulated light action

    NASA Astrophysics Data System (ADS)

    Antonov, Sergei N.; Sotnikov, V. N.; Koreneva, L. G.

    1994-07-01

    Now there exists no clear complete knowledge about mechanisms and pathways by which low level laser bioactivation works. Modulated laser light action has been investigated two new ways: dynamical infrared thermography and computing image of living brain. These ways permit observation in real time laser action on peripheral blood flow, reflex reactions to functional probes, thermoregulation mechanisms as well as brain electrical activity changes of humans. We have designed a universal apparatus which produced all regimes of the output laser light. It has a built-in He-Ne laser with an acousto-optic modulator and an infrared GaAs laser. The device provided spatial combination of both the light beams and permitted us to irradiate an object both separately and simultaneously. This research shows that the most effective frequencies range from several to dozens of hertz. The duty factor and frequency scanning are also important. On the basis of these results in Russian clinics new treatment methods using modulated light are applied in practical neurology, gynecology, etc.

  15. Low-Level Jets: The Data Assimilation Office and Reanalysis

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Data assimilation brings together atmospheric observations and atmospheric models-what we can measure of the atmosphere with how we expect it to behave. NASA's Data Assimilation Office (DAO) sponsors research projects in data reanalysis, which take several years of observational data and analyze them with a fixed assimilation system, to create an improved data set for use in atmospheric studies. Using NCCS computers, one group of NASA researchers employs reanalysis to examine the role of summertime low-level jet (LLJ) winds in regional seasonal climate. Prevailing winds that blow strongly in a fixed direction within a vertically and horizontally confined region of the atmosphere are known as jets. Jets can dominate circulation and have an enormous impact on the weather in a region. Some jets are as famous as they are influential. The jet stream over North America, for instance, is the wind that blows eastward across the continent, bringing weather from the west coast and increasing the speed of airplanes flying to the east coast. The jet stream, while varying in intensity and location, is present in all seasons at the very high altitude of 200-300 millibars - more than 6 miles above Earth's surface.

  16. Low-level laser therapy for Peyronie's disease

    NASA Astrophysics Data System (ADS)

    Johnson, Douglas E.; Bertini, John E. J.; Harris, James M.; Hawkins, Janet H.

    1995-05-01

    We are reporting the preliminary results of a nonrandomized trial using a low-level gallium- aluminum-arsenide (GaAlAs) laser at a wavelength of 830 nm (Microlight 830, Lasermedics, Inc., Stafford, TX) to treat patients with symptomatic Peyronie's disease. All patients entered into the study had disease consisting of a well-defined fibrous plaque causing pain and/or curvature of the penile shaft on erection that interfered with satisfactory sexual intercourse. Treatment has consisted of 30 mW administered over a duty cycle of 100 seconds (3 J) beginning at the base of the penis and extending to the coronal sulcus over the dorsum of the penis at 0.5 cm intervals. An additional duty cycle of 100 seconds was delivered to each 0.5 cm of palpable plaque. The ability of the therapy to reduce the size of the fibrous plaque, the severity of the penile curvature, and the severity of pain associated with penile erection and the treatment's effect on the patient's quality of life were assessed for each patient at completion of therapy and 6 weeks later.

  17. Assessing the Impacts of Low Level Jets over Wind Turbines

    NASA Astrophysics Data System (ADS)

    Gutierrez Rodriguez, Walter; Araya, Guillermo; Ruiz-Columbie, Arquimedes; Tutkun, Murat; Castillo, Luciano

    2015-11-01

    Low Level Jets (LLJs) are defined as regions of relatively strong winds in the lower part of the atmosphere. They are a common feature over the Great Plains in the United States. This paper is focused on the determination of the static/dynamic impacts that real LLJs in West Texas have over wind turbines and wind farms. High-frequency (50Hz) observational data from the 200-m meteorological tower (Reese, Texas) have been input as inflow conditions into the NREL FAST code in order to evaluate the LLJ's structural impacts on a typical wind turbine. Then, the effect of the LLJ on the wind turbine's wake is considered to evaluate the overall impact on the wind farm. It has been observed that during a LLJ event the levels of turbulence intensity and turbulence kinetic energy are significantly much lower than those during unstable conditions. Also, low-frequency oscillations prevail during stable conditions when LLJs are present, as opposed to high-frequency oscillations which are more prevalent during unstable conditions. Additionally, in LLJs the energy concentrates in particular frequencies that stress the turbine whereas turbine signals show frequencies that are also present in the incoming wind. Grants: NSF-CBET #1157246, NSF-CMMI #1100948, NSF-PIRE # NSF-OISE-1243482.

  18. Advances in low-level jet research and future prospects

    NASA Astrophysics Data System (ADS)

    Liu, Hongbo; He, Mingyang; Wang, Bin; Zhang, Qinghong

    2014-02-01

    The low-level jet (LLJ) is closely related to severe rainfall events, air pollution, wind energy utilization, aviation safety, sandstorms, forest fire, and other weather and climate phenomena. Therefore, it has attracted considerable attention since its discovery. Scientists have carried out many studies on LLJs and made significant achievements during the past five or six decades. This article summarizes and assesses the current knowledge on this subject, and focuses in particular on three aspects: 1) LLJ classification, definition, distribution, and structure; 2) LLJ formation and evolutionary mechanisms; and 3) relationships between LLJ and rainfall, as well as other interdisciplinary fields. After comparing the status of LLJ research at home (China) and abroad, we then discuss the shortcomings of LLJ research in China. We suggest that this includes: coarse definitions of the LLJ, lack of observations and inadequate quality control, few thorough explorations of LLJ characteristics and formation mechanisms, and limited studies in interdisciplinary fields. The future prospects for several LLJ research avenues are also speculated.

  19. Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

    PubMed Central

    Takaya, Naoki; Catalan-Sakairi, Maria Antonina B.; Sakaguchi, Yasushi; Kato, Isao; Zhou, Zhemin; Shoun, Hirofumi

    2003-01-01

    Most denitrifiers produce nitrous oxide (N2O) instead of dinitrogen (N2) under aerobic conditions. We isolated and characterized novel aerobic denitrifiers that produce low levels of N2O under aerobic conditions. We monitored the denitrification activities of two of the isolates, strains TR2 and K50, in batch and continuous cultures. Both strains reduced nitrate (NO3−) to N2 at rates of 0.9 and 0.03 μmol min−1 unit of optical density at 540 nm−1 at dissolved oxygen (O2) (DO) concentrations of 39 and 38 μmol liter−1, respectively. At the same DO level, the typical denitrifier Pseudomonas stutzeri and the previously described aerobic denitrifier Paracoccus denitrificans did not produce N2 but evolved more than 10-fold more N2O than strains TR2 and K50 evolved. The isolates denitrified NO3− with concomitant consumption of O2. These results indicated that strains TR2 and K50 are aerobic denitrifiers. These two isolates were taxonomically placed in the β subclass of the class Proteobacteria and were identified as P. stutzeri TR2 and Pseudomonas sp. strain K50. These strains should be useful for future investigations of the mechanisms of denitrifying bacteria that regulate N2O emission, the single-stage process for nitrogen removal, and microbial N2O emission into the ecosystem. PMID:12788710

  20. Soil characterization methods for unsaturated low-level waste sites

    SciTech Connect

    Wierenga, P.J.; Young, M.H. . Dept. of Soil and Water Science); Gee, G.W.; Kincaid, C.T. ); Hills, R.G. . Dept. of Mechanical Engineering); Nicholson, T.J.; Cady, R.E. )

    1993-01-01

    To support a license application for the disposal of low-level radioactive waste (LLW), applicants must characterize the unsaturated zone and demonstrate that waste will not migrate from the facility boundary. This document provides a strategy for developing this characterization plan. It describes principles of contaminant flow and transport, site characterization and monitoring strategies, and data management. It also discusses methods and practices that are currently used to monitor properties and conditions in the soil profile, how these properties influence water and waste migration, and why they are important to the license application. The methods part of the document is divided into sections on laboratory and field-based properties, then further subdivided into the description of methods for determining 18 physical, flow, and transport properties. Because of the availability of detailed procedures in many texts and journal articles, the reader is often directed for details to the available literature. References are made to experiments performed at the Las Cruces Trench site, New Mexico, that support LLW site characterization activities. A major contribution from the Las Cruces study is the experience gained in handling data sets for site characterization and the subsequent use of these data sets in modeling studies.

  1. Risk evaluation - conventional and low level effects of radiation

    SciTech Connect

    Bond, V.P.; Varma, M.N.

    1984-04-01

    Any discussion of the risk of exposure to potentially-hazardous agents in the environment inevitably involves the question of whether the dose effect curve is of the threshold or linear, non-threshold type. A principal objective of this presentation is to show that the function is actually two separate relationships, each representing distinctly different functions with differing variables on the axes, and each characteristic of quite different functions with differing variables on the axes, and each characteristic of quite different disciplines (i.e., the threshold function, of Pharmacology, Toxicology and Medicine (PTM); the linear, non-threshold function, of Public Health including safety and accident statistics (PHS)). It is shown that low-level exposure (LLE) to radiation falls clearly in the PHS category. A function for cell dose vs. the fraction of single cell quantal responses is characterized, which reflects the absolute and relative sensitivities of cells. Acceptance of this function would obviate any requirement for the use in Radiation Protection of the concepts of a standard radiation, Q, dose equivalent and rem. 9 references, 4 figures.

  2. Effect of Pulsing in Low-Level Light Therapy

    PubMed Central

    Hashmi, Javad T.; Huang, Ying-Ying; Sharma, Sulbha K.; Kurup, Divya Balachandran; De Taboada, Luis; Carroll, James D.; Hamblin, Michael R.

    2010-01-01

    Background and Objective Low level light (or laser) therapy (LLLT) is a rapidly growing modality used in physical therapy, chiropractic, sports medicine and increasingly in mainstream medicine. LLLT is used to increase wound healing and tissue regeneration, to relieve pain and inflammation, to prevent tissue death, to mitigate degeneration in many neurological indications. While some agreement has emerged on the best wavelengths of light and a range of acceptable dosages to be used (irradiance and fluence), there is no agreement on whether continuous wave or pulsed light is best and on what factors govern the pulse parameters to be chosen. Study Design/Materials and Methods The published peer-reviewed literature was reviewed between 1970 and 2010. Results The basic molecular and cellular mechanisms of LLLT are discussed. The type of pulsed light sources available and the parameters that govern their pulse structure are outlined. Studies that have compared continuous wave and pulsed light in both animals and patients are reviewed. Frequencies used in other pulsed modalities used in physical therapy and biomedicine are compared to those used in LLLT. Conclusion There is some evidence that pulsed light does have effects that are different from those of continuous wave light. However further work is needed to define these effects for different disease conditions and pulse structures. PMID:20662021

  3. Low-level microwave irradiation and central cholinergic systems

    SciTech Connect

    Lai, H.; Carino, M.A.; Horita, A.; Guy, A.W. )

    1989-05-01

    Our previous research showed that 45 min of exposure to low-level, pulsed microwaves (2450-MHz, 2-microseconds pulses, 500 pps, whole-body average specific absorption rate 0.6 W/kg) decreased sodium-dependent high-affinity choline uptake in the frontal cortex and hippocampus of the rat. The effects of microwaves on central cholinergic systems were further investigated in this study. Increases in choline uptake activity in the frontal cortex, hippocampus, and hypothalamus were observed after 20 min of acute microwave exposure, and tolerance to the effect of microwaves developed in the hypothalamus, but not in the frontal cortex and hippocampus, of rats subjected to ten daily 20-min exposure sessions. Furthermore, the effects of acute microwave irradiation on central choline uptake could be blocked by pretreating the animals before exposure with the narcotic antagonist naltrexone. In another series of experiments, rats were exposed to microwaves in ten daily sessions of either 20 or 45 min, and muscarinic cholinergic receptors in different regions of the brain were studied by 3H-QNB binding assay. Decreases in concentration of receptors occurred in the frontal cortex and hippocampus of rats subjected to ten 20-min microwave exposure sessions, whereas increase in receptor concentration occurred in the hippocampus of animals exposed to ten 45-min sessions. This study also investigated the effects of microwave exposure on learning in the radial-arm maze. Rats were trained in the maze to obtain food reinforcements immediately after 20 or 45 min of microwave exposure.

  4. Health effects of low-level exposure to polychlorinated biphenyls

    SciTech Connect

    Stark, A.D.; Costas, K.; Chang, H.G.; Vallet, H.L.

    1986-10-01

    A polychlorinated biphenyl (PCB) spill resulting from a transformer explosion in Syracuse, New York, with no subsequent fire, provided an opportunity for the examination of the effects of low-level PCB exposure without the confounding presence of furans and dioxins. The incident provided 52 individuals exposed to PCB among building personnel, police, firemen, and public utility employees. Sixty-eight nonexposed were matched to the exposed group by sex, age, employer, and job description. Data were collected on the exposed relative to their activities at the spill site, their location, possible routes of exposure duration of exposure, and subsequent health effects. Exposed and nonexposed were interviewed for past medical history and relevant symptoms. Blood chemistries were studied inclusive of SGOT, SGPT, total protein, CBC, cholesterol, and triglyceride levels, as well as a fasting blood PCB level measurement. Six weeks after the spill, exposed and nonexposed were re-interviewed and had their blood work repeated except for the CBC and PCB levels. Exposed and nonexposed laboratory results were unremarkable. Some transient skin irritation believed to be associated with PCBs was noted. There were significant PCBs in blood level trends for occupation, age, duration of exposure, and level of alcohol consumption. Triglyceride level was highly correlated with PCB level. This relationship held when age and alcohol consumption were controlled for.

  5. Effect of interstitial low level laser therapy on tibial defect

    NASA Astrophysics Data System (ADS)

    Lee, Sangyeob; Ha, Myungjin; Hwang, Donghyun; Yu, Sungkon; Jang, Seulki; Park, Jihoon; Radfar, Edalat; Kim, Hansung; Jung, Byungjo

    2016-03-01

    Tibial defect is very common musculoskeletal disorder which makes patient painful and uncomfortable. Many studies about bone regeneration tried to figure out fast bone healing on early phase. It is already known that low level laser therapy (LLLT) is very convenient and good for beginning of bone disorder. However, light scattering and absorption obstruct musculoskeletal therapy which need optimal photon energy delivery. This study has used an interstitial laser probe (ILP) to overcome the limitations of light penetration depth and scattering. Animals (mouse, C57BL/6) were divided into three groups: laser treated test group 1 (660 nm; power 10 mW; total energy 5 J) and test group 2 (660 nm; power 20 mW; total energy 10 J); and untreated control group. All animals were taken surgical operation to make tibial defect on right crest of tibia. The test groups were treated every 48 hours with ILP. Bone volume and X-ray attenuation coefficient were measured on 0, 14th and 28th day with u-CT after treatment and were used to evaluate effect of LLLT. Results show that bone volume of test groups has been improved more than control group. X-ray attenuation coefficients of each groups have slightly different. The results suggest that LLLT combined with ILP may affect on early phase of bone regeneration and may be used in various musculoskeletal disease in deep tissue layer.

  6. Remediation alternatives for low-level herbicide contaminated groundwater

    SciTech Connect

    Conger, R.M.

    1995-10-01

    In early 1995, an evaluation of alternatives for remediation of a shallow groundwater plume containing low-levels of an organic herbicide was conducted at BASF Corporation, a petrochemical facility located in Ascension Parish, Louisiana. The contaminated site is located on an undeveloped portion of property within 1/4 mile of the east bank of the Mississippi River near the community of Geismar. Environmental assessment data indicated that about two acres of the thirty acre site had been contaminated from past waste management practices with the herbicide bentazon. Shallow soils and groundwater between 5 to 15 feet in depth were affected. Maximum concentrations of bentazon in groundwater were less than seven parts per million. To identify potentially feasible remediation alternatives, the environmental assessment data, available research, and cost effectiveness were reviewed. After consideration of a preliminary list of alternatives, only two potentially feasible alternatives could be identified. Groundwater pumping, the most commonly used remediation alternative, followed by carbon adsorption treatment was identified as was a new innovative alternative known as vegetative transpiration. This alternative relies on the natural transpiration processes of vegetation to bioremediate organic contaminants. Advantages identified during screening suggest that the transpiration method could be the best remediation alternative to address both economic and environmental factors. An experiment to test critical factors of the vegetatived transpiration alternative with bentazon was recommended before a final decision on feasibility can be made.

  7. Versatile Low Level RF System For Linear Accelerators

    SciTech Connect

    Potter, James M.

    2011-06-01

    The Low Level RF (LLRF) system is the source of all of the rf signals required for an rf linear accelerator. These signals are amplified to drive accelerator and buncher cavities. It can even provide the synchronizing signal for the rf power for a synchrotron. The use of Direct Digital Synthesis (DDS) techniques results in a versatile system that can provide multiple coherent signals at the same or different frequencies with adjustable amplitudes and phase relations. Pulsing the DDS allows rf switching with an essentially infinite on/off ratio. The LLRF system includes a versatile phase detector that allows phase-locking the rf frequency to a cavity at any phase angle over the full 360 deg. range. With the use of stepper motor driven slug tuners multiple cavity resonant frequencies can be phase locked to the rf source frequency. No external phase shifters are required and there is no feedback loop phase setup required. All that is needed is to turn the frequency feedback on. The use of Digital Signal Processing (DSP) allows amplitude and phase control over the entire rf pulse. This paper describes the basic principles of a LLRF system that has been used for both proton accelerators and electron accelerators, including multiple tank accelerators, sub-harmonic and fundamental bunchers, and synchrotrons.

  8. Ultra-low level radon assays in gases

    SciTech Connect

    Liu, Xin Ran

    2015-08-17

    The SuperNEMO experiment aims to search for the neutrinoless double beta decay (0νβ β) to T{sub 1{sub /{sub 2}}}(0ν) > 10{sup 26} years, this corresponds to an effective neutrino mass of 50-100 meV. The extremely rare event rate means the minimisation of background is of critical concern. The stringent strategy instigated to ensure detector radiopurity is outlined here for all construction materials. In particular the large R&D programme undertaken to reach the challengingly low level of radon, < 0.15 mBq/m{sup 3}, required inside the SuperNEMO gaseous tracker will be detailed. This includes an experiment designed to measure radon diffusion through various materials. A “Radon Concentration Line” (RnCL) was developed to be used in conjunction with a state-of-the-art radon detector in order to achieve world leading sensitivity to {sup 222}Rn content in large gas volumes at the level of a few µBq/m{sup 3}. A radon purification system was developed and installed which has demonstrated radon suppression by several orders of magnitude depending on the carrier gas. This apparatus has now been commissioned and measurements of cylindered gas have been made to confirm radon suppression by a factor 20 when using nitrogen as the carrier gas. The results from measurements of radon content in various gases, used inside SuperNEMO, using the RnCL will be presented.

  9. Low-level laser/light therapy for androgenetic alopecia.

    PubMed

    Gupta, Aditya K; Lyons, Danika C A; Abramovits, William

    2014-01-01

    Androgenetic alopecia (AGA) is a persistent and pervasive condition that affects men worldwide. Some common treatment options for AGA include hair prosthetics, oral and topical medications, and surgical hair restoration (SHR). Pharmaceutical and SHR treatments are associated with limitations including adverse side effects and significant financial burden. Low-level laser or light (LLL) devices offer alternative treatment options that are not typically associated with adverse side effects or significant costs. There are clinic- and home-based LLL devices. One home-based laser comb device has set a standard for others; however, this device requires time devoted to carefully moving the comb through the hair to allow laser penetration to the scalp. A novel helmet-like LLL device for hair growth has proven effective in preliminary trials and allows for hands-free use. Regardless, there are few clinical trials that have been conducted regarding LLL devices for AGA and results are mixed. Further research is required to establish the true efficacy of these devices for hair growth in comparison to existing alternative therapies. PMID:25134310

  10. Credit WCT. Photographic copy of photograph, low level aerial view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit WCT. Photographic copy of photograph, low level aerial view of Test Stand "D," looking due south, after completion of Dd station installation in 1961. Note Test Stand "D" "neutralization pond" to immediate southeast of tower. A steel barrier north of and parallel to the Dd station separates fuel run tanks (on south side obscured from view) from oxidizer run tanks (on north side). Small Dj injector test stand is visible to the immediate left of oxidizer run tanks; it is oriented on a northeast/southwest diagonal to the Dd test station. The large tank to the north of the oxidizer run tanks (near center bottom of view) is an oxidizer storage tank for nitrogen tetroxide. Slender tanks to the northwest of the tower (lower right of view) contain high pressure nitrogen gas. A large vertical tank at the base of the tower contains distilled water for flushing propellant lines. (JPL negative no. 384-2997-B, 12 December 1961) - Jet Propulsion Laboratory Edwards Facility, Test Stand D, Edwards Air Force Base, Boron, Kern County, CA

  11. WRAP low level waste (LLW) glovebox operational test report

    SciTech Connect

    Kersten, J.K.

    1998-02-19

    The Low Level Waste (LLW) Process Gloveboxes are designed to: receive a 55 gallon drum in an 85 gallon overpack in the Entry glovebox (GBIOI); and open and sort the waste from the 55 gallon drum, place the waste back into drum and relid in the Sorting glovebox (GB 102). In addition, waste which requires further examination is transferred to the LLW RWM Glovebox via the Drath and Schraeder Bagiess Transfer Port (DO-07-201) or sent to the Sample Transfer Port (STC); crush the drum in the Supercompactor glovebox (GB 104); place the resulting puck (along with other pucks) into another 85 gallon overpack in the Exit glovebox (GB 105). The status of the waste items is tracked by the Data Management System (DMS) via the Plant Control System (PCS) barcode interface. As an item is moved from the entry glovebox to the exit glovebox, the Operator will track an items location using a barcode reader and enter any required data on the DMS console. The Operational Test Procedure (OTP) will perform evolution`s (described below) using the Plant Operating Procedures (POP) in order to verify that they are sufficient and accurate for controlled glovebox operation.

  12. Integrated software system for low level waste management

    SciTech Connect

    Worku, G.

    1995-12-31

    In the continually changing and uncertain world of low level waste management, many generators in the US are faced with the prospect of having to store their waste on site for the indefinite future. This consequently increases the set of tasks performed by the generators in the areas of packaging, characterizing, classifying, screening (if a set of acceptance criteria applies), and managing the inventory for the duration of onsite storage. When disposal sites become available, it is expected that the work will require re-evaluating the waste packages, including possible re-processing, re-packaging, or re-classifying in preparation for shipment for disposal under the regulatory requirements of the time. In this day and age, when there is wide use of computers and computer literacy is at high levels, an important waste management tool would be an integrated software system that aids waste management personnel in conducting these tasks quickly and accurately. It has become evident that such an integrated radwaste management software system offers great benefits to radwaste generators both in the US and other countries. This paper discusses one such approach to integrated radwaste management utilizing some globally accepted radiological assessment software applications.

  13. Certification Plan, low-level waste Hazardous Waste Handling Facility

    SciTech Connect

    Albert, R.

    1992-06-30

    The purpose of this plan is to describe the organization and methodology for the certification of low-level radioactive waste (LLW) handled in the Hazardous Waste Handling Facility (HWHF) at Lawrence Berkeley Laboratory (LBL). This plan also incorporates the applicable elements of waste reduction, which include both up-front minimization and end-product treatment to reduce the volume and toxicity of the waste; segregation of the waste as it applies to certification; an executive summary of the Waste Management Quality Assurance Implementing Management Plan (QAIMP) for the HWHF and a list of the current and planned implementing procedures used in waste certification. This plan provides guidance from the HWHF to waste generators, waste handlers, and the Waste Certification Specialist to enable them to conduct their activities and carry out their responsibilities in a manner that complies with the requirements of WHC-WAC. Waste generators have the primary responsibility for the proper characterization of LLW. The Waste Certification Specialist verifies and certifies that LBL LLW is characterized, handled, and shipped in accordance with the requirements of WHC-WAC. Certification is the governing process in which LBL personnel conduct their waste generating and waste handling activities in such a manner that the Waste Certification Specialist can verify that the requirements of WHC-WAC are met.

  14. Noninvasive low-level laser therapy for thrombocytopenia.

    PubMed

    Zhang, Qi; Dong, Tingting; Li, Peiyu; Wu, Mei X

    2016-07-27

    Thrombocytopenia is a common hematologic disorder that is managed primarily by platelet transfusions. We report here that noninvasive whole-body illumination with a special near-infrared laser cures acute thrombocytopenia triggered by γ-irradiation within 2 weeks in mice, as opposed to a 5-week recovery time required in controls. The low-level laser (LLL) also greatly accelerated platelet regeneration in the presence of anti-CD41 antibody that binds and depletes platelets, and prevented a severe drop in platelet count caused by a common chemotherapeutic drug. Mechanistically, LLL stimulated mitochondrial biogenesis specifically in megakaryocytes owing to polyploidy of the cells. LLL also protected megakaryocytes from mitochondrial injury and apoptosis under stress. The multifaceted effects of LLL on mitochondria bolstered megakaryocyte maturation; facilitated elongation, branching, and formation of proplatelets; and doubled the number of platelets generated from individual megakaryocytes in mice. LLL-mediated platelet biogenesis depended on megakaryopoiesis and was inversely correlated with platelet counts, which kept platelet biogenesis in check and effectively averted thrombosis even after repeated uses, in sharp contrast to all current agents that stimulate the differentiation of megakaryocyte progenitors from hematopoietic stem cells independently of platelet counts. This safe, drug-free, donor-independent modality represents a paradigm shift in the prophylaxis and treatment of thrombocytopenia. PMID:27464749

  15. Low level CO2 effects on pulmonary function in humans

    NASA Technical Reports Server (NTRS)

    Sexton, J.; Mueller, K.; Elliott, A.; Gerzer, D.; Strohl, K. P.; West, J. B. (Principal Investigator)

    1998-01-01

    The purpose of the study was to determine whether chamber exposure to low levels of CO2 results in functional alterations in gas mixing and closing volume in humans. Four healthy volunteer subjects were exposed to 0.7% CO2 and to 1.2% CO2. Spirometry, lung volumes, single breath nitrogen washout, diffusing capacity for carbon monoxide (DLCO) by two methods, and cardiac output were measured in triplicate. Values were obtained over two non-consecutive days during the training period (control) and on days 2 or 3, 4, 6, 10, 13, and 23 of exposure to each CO2 level. Measurements were made during the same time of day. There was one day of testing after exposure, while still in the chamber but off carbon dioxide. The order of testing, up until measurements of DLCO and cardiac output, were randomized to avoid presentation effects. The consistent findings were a reduction in diffusing capacity for carbon monoxide and a fall in cardiac output, occurring to a similar degree with both exposures. For the group as a whole, there was no indication of major effects on spirometry, lung volumes, gas mixing or dead space. We conclude that small changes may occur in the function of distal gas exchanging units; however, these effects were not associated with any adverse health effects. The likelihood of pathophysiologic changes in lung function or structure with 0.7 or 1.2% CO2 exposure for this period of time, is therefore, low.

  16. Feedback Configuration Tools for LHC Low Level RF

    SciTech Connect

    Van Winkle, D.; Fox, J.; Mastorides, T.; Rivetta, C.; Baudrenghien, P.; Butterworth, A.; Molendijk, J.; /CERN

    2009-12-16

    The LHC Low Level RF System (LLRF) is a complex multi-VME crate system which is used to regulate the superconductive cavity gap voltage as well as to lower the impedance as seen by the beam through low latency feedback. This system contains multiple loops with several parameters to be set before the loops can be closed. In this paper, we present a suite of MATLAB based tools developed to perform the preliminary alignment of the RF stations and the beginnings of a closed loop model based alignment routine. We briefly introduce the RF system and in particular the base band (time domain noise based) network analyzer system built into the LHC LLRF. The main focus of this paper is the methodology of the algorithms used by the routines within the context of the overall system. Measured results are presented that validate the technique. Because the RF systems are located in a cavern 120 m underground in a location which is relatively un-accessible without beam and completely un-accessible with beam present or magnets are energized, these remotely operated tools are a necessity for the CERN LLRF team to maintain and tune their LLRF systems in a similar fashion as to what was done very successfully in PEP-II at SLAC.

  17. Reproductive toxicity of low-level lead exposure in men

    SciTech Connect

    Telisman, Spomenka Colak, Bozo; Pizent, Alica; Jurasovic, Jasna; Cvitkovic, Petar

    2007-10-15

    Parameters of semen quality, seminal plasma indicators of secretory function of the prostate and seminal vesicles, sex hormones in serum, and biomarkers of lead, cadmium, copper, zinc, and selenium body burden were measured in 240 Croatian men 19-52 years of age. The subjects had no occupational exposure to metals and no known other reasons suspected of influencing male reproductive function or metal metabolism. After adjusting for age, smoking, alcohol, blood cadmium, and serum copper, zinc, and selenium by multiple regression, significant (P<0.05) associations of blood lead (BPb), {delta}-aminolevulinic acid dehydratase (ALAD), and/or erythrocyte protoporphyrin (EP) with reproductive parameters indicated a lead-related increase in immature sperm concentration, in percentages of pathologic sperm, wide sperm, round sperm, and short sperm, in serum levels of testosterone and estradiol, and a decrease in seminal plasma zinc and in serum prolactin. These reproductive effects were observed at low-level lead exposure (BPb median 49 {mu}g/L, range 11-149 {mu}g/L in the 240 subjects) common for general populations worldwide. The observed significant synergistic effect of BPb and blood cadmium on increasing serum testosterone, and additive effect of a decrease in serum selenium on increasing serum testosterone, may have implications on the initiation and development of prostate cancer because testosterone augments the progress of prostate cancer in its early stages.

  18. Low level laser therapy for traumatic brain injury

    NASA Astrophysics Data System (ADS)

    Wu, Qiuhe; Huang, Ying-Ying; Dhital, Saphala; Sharma, Sulbha K.; Chen, Aaron C.-H.; Whalen, Michael J.; Hamblin, Michael R.

    2010-02-01

    Low level laser (or light) therapy (LLLT) has been clinically applied for many indications in medicine that require the following processes: protection from cell and tissue death, stimulation of healing and repair of injuries, and reduction of pain, swelling and inflammation. One area that is attracting growing interest is the use of transcranial LLLT to treat stroke and traumatic brain injury (TBI). The fact that near-infrared light can penetrate into the brain would allow non-invasive treatment to be carried out with a low likelihood of treatment-related adverse events. LLLT may have beneficial effects in the acute treatment of brain damage injury by increasing respiration in the mitochondria, causing activation of transcription factors, reducing key inflammatory mediators, and inhibiting apoptosis. We tested LLLT in a mouse model of TBI produced by a controlled weight drop onto the skull. Mice received a single treatment with 660-nm, 810-nm or 980-nm laser (36 J/cm2) four hours post-injury and were followed up by neurological performance testing for 4 weeks. Mice with moderate to severe TBI treated with 660- nm and 810-nm laser had a significant improvement in neurological score over the course of the follow-up and histological examination of the brains at sacrifice revealed less lesion area compared to untreated controls. Further studies are underway.

  19. The Mechanism of Field-Scale Solute Transport: An insight from Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Russo, David

    2014-05-01

    Field-scale transport of conservative (chloride) and reactive (nitrate) solutes was analyzed by means of two different model processes for the local description of the transport. The first is the classical, one-region advection dispersion equation (ADE) model, while the second is the two-region, mobile-immobile (MIM) model. The analyses were performed by means of detailed three-dimensional (3-D), numerical simulations of the flow and the transport considering realistic features of the soil-water-plant-atmosphere system, pertinent to a turf field located in the Glil Yam site, Israel, irrigated with treated waste water (TWW). Simulated water content and concentration profiles were compared with available measurements of their counterparts. Results of the analyses suggest that the behavior of both the conservative and the reactive solutes in the Glil Yam site is quantified better when the transport on the local scale is modeled as a two-region, MIM model, than when a single-region, ADE model is used. Reconstruction of the shape of the measured solute concentration profiles using the MIM transport model, required relatively large immobile water content fraction and relatively small mass transfer coefficient. These results suggest that in the case of initially non-zero solute concentration profile (e.g., chloride and nitrate), the 3-D ADE transport model may significantly overestimate the groundwater contamination hazard posed by the solutes moving through the vadose zone, as compared with the 3-D MIM transport model, while the opposite is true in the case of initially zero solute concentration profile (e.g., carbamazepine). These findings stem from the combination of relatively large immobile water content fraction and relatively small mass transfer coefficient taken into account in the MIM transport model. In the first case, this combination forces a considerable portion of the solute mass to remain in the immobile region of the water-filled pores, while the opposite

  20. Hydrolysis of plutonium: Corrosion kinetics in DMSO solutions containing simulated high explosive and water

    SciTech Connect

    Haschke, J.M.; Pruner, R.E. II

    1995-01-01

    A sequence of experiments is described that address the compatibility of plutonium metal with dimethyl sulfoxide solvent and with solutions containing simulated HMX explosive and simulated explosive plus water. In the absence of water, reaction is slow and forms a thin adherent product layer on clean metal surfaces. Corrosion of oxide-coated plutonium is observed after 15 to 20 days in a solution containing 0.18 mass % (0.11 M) water. After corrosion initiates, the rate accelerates rapidly and attains a value of 0.13 mg Pu/cm{sup 2} h with a surface that is approximately one percent active. Dependence of the Pu + H{sub 2}O reaction on water concentration is evaluated using the data from literature sources. Hazards associated with the use of wet dimethyl sulfoxide as a solvent for removing explosives during weapon dismantlement are identified and a simple method for their mitigation is outlined.

  1. Mean ionic activity coefficients in aqueous NaCl solutions from molecular dynamics simulations.

    PubMed

    Mester, Zoltan; Panagiotopoulos, Athanassios Z

    2015-01-28

    The mean ionic activity coefficients of aqueous NaCl solutions of varying concentrations at 298.15 K and 1 bar have been obtained from molecular dynamics simulations by gradually turning on the interactions of an ion pair inserted into the solution. Several common non-polarizable water and ion models have been used in the simulations. Gibbs-Duhem equation calculations of the thermodynamic activity of water are used to confirm the thermodynamic consistency of the mean ionic activity coefficients. While the majority of model combinations predict the correct trends in mean ionic activity coefficients, they overestimate their values at high salt concentrations. The solubility predictions also suffer from inaccuracies, with all models underpredicting the experimental values, some by large factors. These results point to the need for further ion and water model development. PMID:25637995

  2. Mean ionic activity coefficients in aqueous NaCl solutions from molecular dynamics simulations

    SciTech Connect

    Mester, Zoltan; Panagiotopoulos, Athanassios Z.

    2015-01-28

    The mean ionic activity coefficients of aqueous NaCl solutions of varying concentrations at 298.15 K and 1 bar have been obtained from molecular dynamics simulations by gradually turning on the interactions of an ion pair inserted into the solution. Several common non-polarizable water and ion models have been used in the simulations. Gibbs-Duhem equation calculations of the thermodynamic activity of water are used to confirm the thermodynamic consistency of the mean ionic activity coefficients. While the majority of model combinations predict the correct trends in mean ionic activity coefficients, they overestimate their values at high salt concentrations. The solubility predictions also suffer from inaccuracies, with all models underpredicting the experimental values, some by large factors. These results point to the need for further ion and water model development.

  3. Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes

    NASA Astrophysics Data System (ADS)

    Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.

    2016-08-01

    The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.

  4. Stability of 3D Textile Composite Reinforcement Simulations: Solutions to Spurious Transverse Modes

    NASA Astrophysics Data System (ADS)

    Mathieu, S.; Hamila, N.; Dupé, F.; Descamps, C.; Boisse, P.

    2016-03-01

    The simulation of thick 3D composite reinforcement forming brings to light new modeling challenges. The specific anisotropic material behavior due to the possible slippage between fibers induces, among other phenomena, the development of spurious transverse modes in bending-dominated 3D simulations. To obtain coherent finite element responses, two solutions are proposed. The first one uses a simple assumed strain formulation usually prescribed to prevent volumetric locking. This solution avoids spurious transverse modes by stiffening of the hourglass modes. Nevertheless the deformation obtained by this approach still suffers from the inability of the standard continuum mechanics of Cauchy to describe fibrous material deformation. The second proposed approach is based on the introduction of a bending stiffness which both avoids the spurious transverse modes and also improves the global behavior of the element formulation by enriching the underlying continuum. To emphasize the differences between different formulations, element stiffnesses are explicitly calculated and compared.

  5. Aggregation work at polydisperse micellization: ideal solution and "dressed micelle" models comparing to molecular dynamics simulations.

    PubMed

    Burov, S V; Shchekin, A K

    2010-12-28

    General thermodynamic relations for the work of polydisperse micelle formation in the model of ideal solution of molecular aggregates in nonionic surfactant solution and the model of "dressed micelles" in ionic solution have been considered. In particular, the dependence of the aggregation work on the total concentration of nonionic surfactant has been analyzed. The analogous dependence for the work of formation of ionic aggregates has been examined with regard to existence of two variables of a state of an ionic aggregate, the aggregation numbers of surface active ions and counterions. To verify the thermodynamic models, the molecular dynamics simulations of micellization in nonionic and ionic surfactant solutions at two total surfactant concentrations have been performed. It was shown that for nonionic surfactants, even at relatively high total surfactant concentrations, the shape and behavior of the work of polydisperse micelle formation found within the model of the ideal solution at different total surfactant concentrations agrees fairly well with the numerical experiment. For ionic surfactant solutions, the numerical results indicate a strong screening of ionic aggregates by the bound counterions. This fact as well as independence of the coefficient in the law of mass action for ionic aggregates on total surfactant concentration and predictable behavior of the "waterfall" lines of surfaces of the aggregation work upholds the model of "dressed" ionic aggregates. PMID:21197978

  6. Multiscale Molecular Simulation of Solution Processing of SMDPPEH: PCBM Small-Molecule Organic Solar Cells.

    PubMed

    Lee, Cheng-Kuang; Pao, Chun-Wei

    2016-08-17

    Solution-processed small-molecule organic solar cells are a promising renewable energy source because of their low production cost, mechanical flexibility, and light weight relative to their pure inorganic counterparts. In this work, we developed a coarse-grained (CG) Gay-Berne ellipsoid molecular simulation model based on atomistic trajectories from all-atom molecular dynamics simulations of smaller system sizes to systematically study the nanomorphology of the SMDPPEH/PCBM/solvent ternary blend during solution processing, including the blade-coating process by applying external shear to the solution. With the significantly reduced overall system degrees of freedom and computational acceleration from GPU, we were able to go well beyond the limitation of conventional all-atom molecular simulations with a system size on the order of hundreds of nanometers with mesoscale molecular detail. Our simulations indicate that, similar to polymer solar cells, the optimal blending ratio in small-molecule organic solar cells must provide the highest specific interfacial area for efficient exciton dissociation, while retaining balanced hole/electron transport pathway percolation. We also reveal that blade-coating processes have a significant impact on nanomorphology. For given donor/acceptor blending ratios, applying an external shear force can effectively promote donor/acceptor phase segregation and stacking in the SMDPPEH domains. The present study demonstrated the capability of an ellipsoid-based coarse-grained model for studying the nanomorphology evolution of small-molecule organic solar cells during solution processing/blade-coating and provided links between fabrication protocols and device nanomorphologies. PMID:27435212

  7. Simulation and analysis of solute transport in 2D fracture/pipe networks: The SOLFRAC program

    NASA Astrophysics Data System (ADS)

    Bodin, Jacques; Porel, Gilles; Delay, Fred; Ubertosi, Fabrice; Bernard, Stéphane; de Dreuzy, Jean-Raynald

    2007-01-01

    The Time Domain Random Walk (TDRW) method has been recently developed by Delay and Bodin [Delay, F. and Bodin, J., 2001. Time domain random walk method to simulate transport by advection-dispersion and matrix diffusion in fracture networks. Geophys. Res. Lett., 28(21): 4051-4054.] and Bodin et al. [Bodin, J., Porel, G. and Delay, F., 2003c. Simulation of solute transport in discrete fracture networks using the time domain random walk method. Earth Planet. Sci. Lett., 6566: 1-8.] for simulating solute transport in discrete fracture networks. It is assumed that the fracture network can reasonably be represented by a network of interconnected one-dimensional pipes (i.e. flow channels). Processes accounted for are: (1) advection and hydrodynamic dispersion in the channels, (2) matrix diffusion, (3) diffusion into stagnant zones within the fracture planes, (4) sorption reactions onto the fracture walls and in the matrix, (5) linear decay, and (6) mass sharing at fracture intersections. The TDRW method is handy and very efficient in terms of computation costs since it allows for the one-step calculation of the particle residence time in each bond of the network. This method has been programmed in C++, and efforts have been made to develop an efficient and user-friendly software, called SOLFRAC. This program is freely downloadable at the URL http://labo.univ-poitiers.fr/hydrasa/intranet/telechargement.htm. It calculates solute transport into 2D pipe networks, while considering different types of injections and different concepts of local dispersion within each flow channel. Post-simulation analyses are also available, such as the mean velocity or the macroscopic dispersion at the scale of the entire network. The program may be used to evaluate how a given transport mechanism influences the macroscopic transport behaviour of fracture networks. It may also be used, as is the case, e.g., with analytical solutions, to interpret laboratory or field tracer test experiments

  8. Computer Simulation of Cascade Damage in α-Iron with Carbon in Solution

    SciTech Connect

    Andrew, Calder F; Bacon, David J; Barashev, Aleksandr; Osetskiy, Yury N

    2008-01-01

    Molecular dynamics simulation method is used to investigate defect production by displacement cascades in iron with carbon (C) in solution. This is the first study of cascade damage in a metal containing interstitial solute. Iron is of particular interest because of the use of ferritic steels in plant for nuclear power generation. Cascades are simulated with energy in the range 5 to 20keV in iron at either 100 or 600K containing carbon with concentration in the range 0 to 1at%. C in solution has no discernible effect on the number of defects produced in cascades under any of the conditions simulated, nor on the clustered fraction of either self-interstitial atoms (SIAs) or vacancies. However, significant fractions of single SIAs and vacancies are trapped by C in the cascade process, irrespective of cascade energy. The fraction is independent of temperature for vacancies, but increases strongly with temperature for SIAs: this is a consequence of the higher mobility of the SIA.

  9. Molecular dynamics computer simulation of the hydration of two simple organic solutes

    NASA Astrophysics Data System (ADS)

    Remerie, Klaas; van Gunsteren, Wilfred F.; Postma, Johan P. M.; Berendsen, Herman J. C.; Engberts, Jan B. F. N.

    The hydration of two simple organic solutes has been studied using the molecular dynamics (MD) computer simulation method. Results of the simulations of a single 1,4-dioxane or 1,3-dioxane molecule dissolved in 122 water molecules are compared with those of a MD simulation of an empty cavity of corresponding size in 216 water molecules. This yields the opportunity to trace the specific effects of the polar and dispersion solute-solvent interactions on the properties of the water molecules in the hydration shell of the solute. The hydration shell properties of 1,4-dioxane (μ) = 0·14 D) are very similar to those of the corresponding cavity, whereas those of 1,3-dioxane (μ) = 1·91 D) show significant deviations. Earlier conclusions that water structure-making and water structure-breaking properties of 1,4-dioxane are about equally balanced, while 1,3-dioxane is definitely structure-breaking, are confirmed. Moreover, it is shown that a slower self-diffusion and reorientation of water molecules upon addition of a cosolvent does not necessarily point at structure-making properties, additional to those that are already induced by the cavity formation. The introduction of an empty cavity also slows down self-diffusion and molecular reorientation in the hydration shell.

  10. Molecular dynamics simulations of the dielectric properties of fructose aqueous solutions.

    PubMed

    Sonoda, Milton T; Dolores Elola, M; Skaf, Munir S

    2016-10-19

    The static dielectric permittivity and dielectric relaxation properties of fructose aqueous solutions of different concentrations ranging from 1.0 to 4.0 mol l(-1) are investigated by means of molecular dynamics simulations. The contributions from intra- and interspecies molecular correlations were computed individually for both the static and frequency-dependent dielectric properties, and the results were compared with the available experimental data. Simulation results in the time- and frequency-domains were analyzed and indicate that the presence of fructose has little effect on the position of the fast, high-frequency (>500 cm(-1)) components of the dielectric response spectrum. The low-frequency (<0.1 cm(-1)) components, however, are markedly influenced by sugar concentration. Our analysis indicates that fructose-fructose and fructose-water interactions strongly affect the rotational-diffusion regime of molecular motions in the solutions. Increasing fructose concentration not only enhances sugar-sugar and sugar-water low frequency contributions to the dielectric loss spectrum but also slows down the reorientational dynamics of water molecules. These results are consistent with previous computer simulations carried out for other disaccharide aqueous solutions. PMID:27546528

  11. Mixed micellization of gemini and conventional surfactant in aqueous solution: a lattice Monte Carlo simulation.

    PubMed

    Gharibi, Hussein; Khodadadi, Zahra; Mousavi-Khoshdel, S Morteza; Hashemianzadeh, S Majid; Javadian, Soheila

    2014-09-01

    In the current study, we have investigated the micellization of pure gemini surfactants and a mixture of gemini and conventional surfactants using a 3D lattice Monte Carlo simulation method. For the pure gemini surfactant system, the effects of tail length on CMC and aggregation number were studied, and the simulation results were found to be in excellent agreement with the experimental results. For a mixture of gemini and conventional surfactants, variations in the mixed CMC, interaction parameter β, and excess Gibbs free energy G(E) with composition revealed synergism in micelle formation. Simulation results were compared to estimations made using regular solution theory to determine the applicability of this theory for non-ideal mixed surfactant systems. A large discrepancy was observed between the behavior of parameters such as the activity coefficients fi and the excess Gibbs free energy G(E) and the expected behavior of these parameters as predicted by regular solution theory. Therefore, we have used the modified version of regular solution theory. This three parameter model contains two parameters in addition to the interaction parameters: the size parameter, ρ, which reflects differences in the size of components, and the packing parameter, P*, which reflects nonrandom mixing in mixed micelles. The proposed model provides a good description of the behavior of gemini and conventional surfactant mixtures. The results indicated that as the chain length of gemini surfactants in mixture is increased, the size parameter remains constant while the interaction and packing parameters increase. PMID:25218241

  12. Temperature and solute-transport simulation in streamflow using a Lagrangian reference frame

    USGS Publications Warehouse

    Jobson, Harvey E.

    1980-01-01

    A computer program for simulating one-dimensional, unsteady temperature and solute transport in a river has been developed and documented for general use. The solution approach to the convective-diffusion equation uses a moving reference frame (Lagrangian) which greatly simplifies the mathematics of the solution procedure and dramatically reduces errors caused by numerical dispersion. The model documentation is presented as a series of four programs of increasing complexity. The conservative transport model can be used to route a single conservative substance. The simplified temperature model is used to predict water temperature in rivers when only temperature and windspeed data are available. The complete temperature model is highly accurate but requires rather complete meteorological data. Finally, the 10-parameter model can be used to route as many as 10 interacting constituents through a river reach. (USGS)

  13. Two-dimensional Green`s function Poisson solution appropriate for feature-scale microelectronics simulations

    SciTech Connect

    Riley, M.E.

    1998-03-01

    This report describes the numerical procedure used to implement the Green`s function method for solving the Poisson equation in two-dimensional Cartesian coordinates. The procedure can determine the solution to a problem with any or all of applied voltage boundary conditions, dielectric media, floating (insulated) conducting media, dielectric surface charging, periodic (reflective) boundary conditions, and volumetric space charge. The numerical solution is reasonably fast, and the dimension of the linear problem to be solved is that of the number of elements needed to represent the surfaces, not the whole computational volume. The method of solution is useful in the simulation of plasma particle motion in the vicinity of complex surface structures as found in microelectronics plasma processing applications. A FORTRAN implementation of this procedure is available from the author.

  14. Two-dimensional Green`s function Poisson solution appropriate for cylindrical-symmetry simulations

    SciTech Connect

    Riley, M.E.

    1998-04-01

    This report describes the numerical procedure used to implement the Green`s function method for solving the Poisson equation in two-dimensional (r,z) cylindrical coordinates. The procedure can determine the solution to a problem with any or all of the applied voltage boundary conditions, dielectric media, floating (insulated) conducting media, dielectric surface charging, and volumetric space charge. The numerical solution is reasonably fast, and the dimension of the linear problem to be solved is that of the number of elements needed to represent the surfaces, not the whole computational volume. The method of solution is useful in the simulation of plasma particle motion in the vicinity of complex surface structures as found in microelectronics plasma processing applications. This report is a stand-alone supplement to the previous Sandia Technical Report SAND98-0537 presenting the two-dimensional Cartesian Poisson solver.

  15. Counting people with low-level features and Bayesian regression.

    PubMed

    Chan, Antoni B; Vasconcelos, Nuno

    2012-04-01

    An approach to the problem of estimating the size of inhomogeneous crowds, which are composed of pedestrians that travel in different directions, without using explicit object segmentation or tracking is proposed. Instead, the crowd is segmented into components of homogeneous motion, using the mixture of dynamic-texture motion model. A set of holistic low-level features is extracted from each segmented region, and a function that maps features into estimates of the number of people per segment is learned with Bayesian regression. Two Bayesian regression models are examined. The first is a combination of Gaussian process regression with a compound kernel, which accounts for both the global and local trends of the count mapping but is limited by the real-valued outputs that do not match the discrete counts. We address this limitation with a second model, which is based on a Bayesian treatment of Poisson regression that introduces a prior distribution on the linear weights of the model. Since exact inference is analytically intractable, a closed-form approximation is derived that is computationally efficient and kernelizable, enabling the representation of nonlinear functions. An approximate marginal likelihood is also derived for kernel hyperparameter learning. The two regression-based crowd counting methods are evaluated on a large pedestrian data set, containing very distinct camera views, pedestrian traffic, and outliers, such as bikes or skateboarders. Experimental results show that regression-based counts are accurate regardless of the crowd size, outperforming the count estimates produced by state-of-the-art pedestrian detectors. Results on 2 h of video demonstrate the efficiency and robustness of the regression-based crowd size estimation over long periods of time. PMID:22020684

  16. The Dose That Works: Low Level Laser Treatment of Tendinopathy

    SciTech Connect

    Tumilty, Steve; Munn, Joanne; David Baxter, G.; McDonough, Suzanne; Hurley, Deirdre A.; Basford, Jeffrey R.

    2010-05-31

    Background: Low Level Laser Therapy (LLLT) is used in the treatment of tendon injuries. However, the clinical effectiveness of this modality remains controversial with limited agreement on the most efficacious dosage and parameter choices. Purpose: To assess the clinical effectiveness of LLLT in the treatment of tendinopathy and the validity of current dosage recommendations for treatment. Method: Medical databases were searched from inception to 1st August 2008. Controlled clinical trials evaluating LLLT as a primary intervention for any tendinopathy were included in the review. Methodological quality was classified using the PEDro scale. Appropriateness of treatment parameters were assessed using established guidelines. Results: Twenty five trials met the inclusion criteria. There was conflicting findings from multiple trials: 12 showed positive effects and 13 were inconclusive or showed no effect. Dosages used in the 12 positive studies support the existence of an effective dosage window that closely resembled current guidelines. Where pooling of data was possible, LLLT showed a positive effect size; in high quality studies of lateral epicondylitis, participants' grip strength was 9.59 Kg higher than the control group; for participants with Achilles tendinopathy, the effect was 13.6 mm less pain on a 100 mm visual analogue scale. Conclusion: This study found conflicting evidence as to the effectiveness of LLLT in the treatment of tendinopathy. However, an effective dosage window emerged showing benefit in the treatment of tendinopathy. Strong evidence exists from the 12 positive studies that positive outcomes are associated with the use of current dosage recommendations for the treatment of tendinopathy.

  17. Low Level Waste Conceptual Design Adaption to Poor Geological Conditions

    SciTech Connect

    Bell, J.; Drimmer, D.; Giovannini, A.; Manfroy, P.; Maquet, F.; Schittekat, J.; Van Cotthem, A.; Van Echelpoel, E.

    2002-02-26

    Since the early eighties, several studies have been carried out in Belgium with respect to a repository for the final disposal of low-level radioactive waste (LLW). In 1998, the Belgian Government decided to restrict future investigations to the four existing nuclear sites in Belgium or sites that might show interest. So far, only two existing nuclear sites have been thoroughly investigated from a geological and hydrogeological point of view. These sites are located in the North-East (Mol-Dessel) and in the mid part (Fleurus-Farciennes) of the country. Both sites have the disadvantage of presenting poor geological and hydrogeological conditions, which are rather unfavorable to accommodate a surface disposal facility for LLW. The underground of the Mol-Dessel site consists of neogene sand layers of about 180 m thick which cover a 100 meters thick clay layer. These neogene sands contain, at 20 m depth, a thin clayey layer. The groundwater level is quite close to the surface (0-2m) and finally, the topography is almost totally flat. The upper layer of the Fleurus-Farciennes site consists of 10 m silt with poor geomechanical characteristics, overlying sands (only a few meters thick) and Westphalian shales between 15 and 20 m depth. The Westphalian shales are tectonized and strongly weathered. In the past, coal seams were mined out. This activity induced locally important surface subsidence. For both nuclear sites that were investigated, a conceptual design was made that could allow any unfavorable geological or hydrogeological conditions of the site to be overcome. In Fleurus-Farciennes, for instance, the proposed conceptual design of the repository is quite original. It is composed of a shallow, buried concrete cylinder, surrounded by an accessible concrete ring, which allows permanent inspection and control during the whole lifetime of the repository. Stability and drainage systems should be independent of potential differential settlements an d subsidences

  18. Environmental monitoring of low-level radioactive waste disposal facility

    SciTech Connect

    Shum, E.Y.; Starmer, R.J.; Young, M.H.

    1989-12-01

    This branch technical position (BTP) paper on the environmental monitoring program for a low-level radioactive waste disposal facility provides general guidance on what is required by Section 61.53 of Title 10 of the Code of Federal Regulations (10 CFR) of applicants submitting a license application for such a facility. In general, the environmental monitoring program consists of three phases: preoperational, operational, and postoperational. Each phase of the monitoring program should be designed to fulfill the specific objectives defined in the BTP paper. During the preoperational phase, the objectives of the program are to provide site characterization information, to demonstrate site suitability and acceptability, to obtain background or baseline information, and to provide a record for public information. During the operational phase, the emphasis on measurement shifts. Monitoring data are obtained to provide early warning of releases and to document compliance with regulations, the dose limits of 10 CFR Part 61, or applicable standards of the US Environmental Protection Agency. Data are also used to update important pathway parameters to improve predictions of site performance and to provide a record of performance for public information. The postoperational environmental monitoring program emphasizes measurements to demonstrate compliance with the site-closure requirements and continued compliance with the performance objective in regard to the release of radionuclides to the environment. The data are used to support evaluation of long-term effects on the general public and for public information. Guidance is also provided in the BTP paper on the choice of which constituents to measure, setting action levels, relating measurements to appropriate actions in a corrective action plan, and quality assurance.

  19. Melatonin protection from chronic, low-level ionizing radiation.

    PubMed

    Reiter, Russel J; Korkmaz, Ahmet; Ma, Shuran; Rosales-Corral, Sergio; Tan, Dun-Xian

    2011-12-15

    In the current survey, we summarize the published literature which supports the use of melatonin, an endogenously produced molecule, as a protective agent against chronic, low-level ionizing radiation. Under in vitro conditions, melatonin uniformly was found to protect cellular DNA and plasmid super coiled DNA from ionizing radiation damage due to Cs(137) or X-radiation exposure. Likewise, in an in vivo/in vitro study in which humans were given melatonin orally and then their blood lymphocytes were collected and exposed to Cs(137) ionizing radiation, nuclear DNA from the cells of those individuals who consumed melatonin (and had elevated blood levels) was less damaged than that from control individuals. In in vivo studies as well, melatonin given to animals prevented DNA and lipid damage (including limiting membrane rigidity) and reduced the percentage of animals that died when they had been exposed to Cs(137) or Co(60) radiation. Melatonin's ability to protect macromolecules from the damage inflicted by ionizing radiation likely stems from its high efficacy as a direct free radical scavenger and possibly also due to its ability to stimulate antioxidative enzymes. Melatonin is readily absorbed when taken orally or via any other route. Melatonin's ease of self administration and its virtual absence of toxicity or side effects, even when consumed over very long periods of time, are essential when large populations are exposed to lingering radioactive contamination such as occurs as a result of an inadvertent nuclear accident, an intentional nuclear explosion or the detonation of a radiological dispersion device, i.e., a "dirty" bomb. PMID:22185900

  20. The role of nitric oxide in low level light therapy

    NASA Astrophysics Data System (ADS)

    Hamblin, Michael R.

    2008-02-01

    The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage by reducing cellular apoptosis has been known for almost forty years since the invention of lasers. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. Firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of choosing amongst a large number of illumination parameters has led to the publication of a number of negative studies as well as many positive ones. This review will focus on the role of nitric oxide in the cellular and tissue effects of LLLT. Red and near-IR light is primarily absorbed by cytochrome c oxidase (unit four in the mitochondrial respiratory chain). Nitric oxide produced in the mitochondria can inhibit respiration by binding to cytochrome c oxidase and competitively displacing oxygen, especially in stressed or hypoxic cells. If light absorption displaced the nitric oxide and thus allowed the cytochrome c oxidase to recover and cellular respiration to resume, this would explain many of the observations made in LLLT. Why the effect is only seen in hypoxic, stressed or damaged cells or tissues? How the effects can keep working for some time (hours or days) postillumination? Why increased NO concentrations are sometimes measured in cell culture or in animals? How blood flow can be increased? Why angiogenesis is sometimes increased after LLLT in vivo?

  1. The effect of low level laser on anaplastic thyroid cancer

    NASA Astrophysics Data System (ADS)

    Rhee, Yun-Hee; Moon, Jeon-Hwan; Ahn, Jin-Chul; Chung, Phil-Sang

    2015-02-01

    Low-level laser therapy (LLLT) is a non-thermal phototherapy used in several medical applications, including wound healing, reduction of pain and amelioration of oral mucositis. Nevertheless, the effects of LLLT upon cancer or dysplastic cells have been so far poorly studied. Here we report that the effects of laser irradiation on anaplastic thyroid cancer cells leads to hyperplasia. 650nm of laser diode was performed with a different time interval (0, 15, 30, 60J/cm2 , 25mW) on anaplastic thyroid cancer cell line FRO in vivo. FRO was orthotopically injected into the thyroid gland of nude mice and the irradiation was performed with the same method described previously. After irradiation, the xenograft evaluation was followed for one month. The thyroid tissues from sacrificed mice were undergone to H&E staining and immunohistochemical staining with HIF-1α, Akt, TGF-β1. We found the aggressive proliferation of FRO on thyroid gland with dose dependent. In case of 60 J/ cm2 of energy density, the necrotic bodies were found in a center of the thyroid. The phosphorylation of HIF-1α and Akt was detected in the thyroid gland, which explained the survival signaling of anaplastic cancer cell was turned on the thyroid gland. Furthermore, TGF-β1 expression was decreased after irradiation. In this study, we demonstrated that insufficient energy density irradiation occurred the decreasing of TGF-β1 which corresponding to the phosphorylation of Akt/ HIF-1α. This aggressive proliferation resulted to the hypoxic condition of tissue for angiogenesis. We suggest that LLLT may influence to cancer aggressiveness associated with a decrease in TGF-β1 and increase in Akt/HIF-1α.

  2. Microbial degradation of low-level radioactive waste. Final report

    SciTech Connect

    Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W. Jr

    1996-06-01

    The Nuclear Regulatory Commission stipulates in 10 CFR 61 that disposed low-level radioactive waste (LLW) be stabilized. To provide guidance to disposal vendors and nuclear station waste generators for implementing those requirements, the NRC developed the Technical Position on Waste Form, Revision 1. That document details a specified set of recommended testing procedures and criteria, including several tests for determining the biodegradation properties of waste forms. Information has been presented by a number of researchers, which indicated that those tests may be inappropriate for examining microbial degradation of cement-solidified LLW. Cement has been widely used to solidify LLW; however, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. The purpose of this research program was to develop modified microbial degradation test procedures that would be more appropriate than the existing procedures for evaluation of the effects of microbiologically influenced chemical attack on cement-solidified LLW. The procedures that have been developed in this work are presented and discussed. Groups of microorganisms indigenous to LLW disposal sites were employed that can metabolically convert organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with cement and can ultimately lead to structural failure. Results on the application of mechanisms inherent in microbially influenced degradation of cement-based material are the focus of this final report. Data-validated evidence of the potential for microbially influenced deterioration of cement-solidified LLW and subsequent release of radionuclides developed during this study are presented.

  3. Health effects of low level radiation: carcinogenesis, teratogenesis, and mutagenesis

    SciTech Connect

    Ritenour, E.R.

    1986-04-01

    The carcinogenic effects of radiation have been demonstrated at high dose levels. At low dose levels, such as those encountered in medical diagnosis, the magnitude of the effect is more difficult to quantify. Three reasons for this difficulty are (1) the effects in human populations are small compared with the natural incidence of cancer in the populations; (2) it is difficult to transfer results obtained in animal studies to the human experience; and (3) the effects of latency period and plateau increase the complexity of population studies. In spite of these difficulties, epidemiologic studies of human populations exposed to low levels of radiation still play a valuable role in the determination of radiation carcinogenecity. They serve to provide upper estimates of risk and to rule out the appearance of new effects that may be masked by the effects of high doses. While there is evidence for mutagenic effects of radiation in experimental animals, no conclusive human data exist at the present. It is not possible to rule out the presence of genetic effects of radiation in humans, however, because many problems exist with regard to the epidemiologic detection of small effects when the natural incidence is relatively large. In animals, subtle effects (eg, a decrease in the probability of survival from egg to adult) may occur with greater frequency than more dramatic disorders in irradiated populations. However, these types of genetic abnormalities are difficult to quantitate. Current risk estimates are based primarily upon data pertaining to dominant mutations in rodents. Some specific locus studies also permit identification of recessive mutation rates. The embryo and fetus are considered to be at greater risk for adverse effects of radiation than is the adult.

  4. The Dose That Works: Low Level Laser Treatment of Tendinopathy

    NASA Astrophysics Data System (ADS)

    Tumilty, Steve; Munn, Joanne; McDonough, Suzanne; Hurley, Deirdre A.; Basford, Jeffrey R.; David Baxter, G.

    2010-05-01

    Background: Low Level Laser Therapy (LLLT) is used in the treatment of tendon injuries. However, the clinical effectiveness of this modality remains controversial with limited agreement on the most efficacious dosage and parameter choices. Purpose: To assess the clinical effectiveness of LLLT in the treatment of tendinopathy and the validity of current dosage recommendations for treatment. Method: Medical databases were searched from inception to 1st August 2008. Controlled clinical trials evaluating LLLT as a primary intervention for any tendinopathy were included in the review. Methodological quality was classified using the PEDro scale. Appropriateness of treatment parameters were assessed using established guidelines. Results: Twenty five trials met the inclusion criteria. There was conflicting findings from multiple trials: 12 showed positive effects and 13 were inconclusive or showed no effect. Dosages used in the 12 positive studies support the existence of an effective dosage window that closely resembled current guidelines. Where pooling of data was possible, LLLT showed a positive effect size; in high quality studies of lateral epicondylitis, participants' grip strength was 9.59 Kg higher than the control group; for participants with Achilles tendinopathy, the effect was 13.6 mm less pain on a 100 mm visual analogue scale. Conclusion: This study found conflicting evidence as to the effectiveness of LLLT in the treatment of tendinopathy. However, an effective dosage window emerged showing benefit in the treatment of tendinopathy. Strong evidence exists from the 12 positive studies that positive outcomes are associated with the use of current dosage recommendations for the treatment of tendinopathy.

  5. Wound healing stimulation in mice by low-level light

    NASA Astrophysics Data System (ADS)

    Demidova, Tatiana N.; Herman, Ira M.; Salomatina, Elena V.; Yaroslavsky, Anna N.; Hamblin, Michael R.

    2006-02-01

    It has been known for many years that low levels of laser or non-coherent light (LLLT) accelerate some phases of wound healing. LLLT can stimulate fibroblast and keratinocyte proliferation and migration. It is thought to work via light absorption by mitochondrial chromophores leading to an increase in ATP, reactive oxygen species and consequent gene transcription. However, despite many reports about the positive effects of LLLT on wound healing, its use remains controversial. Our laboratory has developed a model of a full thickness excisional wound in mice that allows quantitative and reproducible light dose healing response curves to be generated. We have found a biphasic dose response curve with a maximum positive effect at 2 J/cm2 of 635-nm light and successively lower beneficial effects from 3-25 J/cm2, the effect is diminished at doses below 2J/cm2 and gradually reaches control healing levels. At light doses above 25 J/cm2 healing is actually worse than controls. The two most effective wavelengths of light were found to be 635 and 820-nm. We found no difference between filtered 635+/-15-nm light from a lamp and 633-nm light from a HeNe laser. The strain and age of the mouse affected the magnitude of the effect. Light treated wounds start to contract after illumination while control wounds initially expand for the first 24 hours. Our hypothesis is that a single brief light exposure soon after wounding affects fibroblast cells in the margins of the wound. Cells may be induced to proliferate, migrate and assume a myofibroblast phenotype. Our future work will be focused on understanding the mechanisms underlying effects of light on wound healing processes.

  6. The Caribbean Low-Level Jet Interannual Summer Variability

    NASA Astrophysics Data System (ADS)

    Munoz, E.; Busalacchi, A.

    2006-12-01

    The Caribbean Low-Level Jet (CALLJ) is an intrinsic component of the climate of the Caribbean and Central America region albeit its controls and effects are not well known. The CALLJ is manifested as strong easterly winds in boreal summer at about 925 mb over the Caribbean Sea. Our overarching objectives are: to determine the factors that control the interannual variability of the CALLJ, and to determine the contribution of CALLJ anomalies on summer Caribbean precipitation. An index representing the CALLJ variability is defined as the 925-mb zonal winds averaged over the area: 70°-80° W, 12°-16° N. The summer months corresponding to the upper and lower quartiles of the CALLJ index are chosen from the period 1979-2001 to construct composites. Multivariate principal component analysis is performed with Caribbean 925-mb zonal winds and sea level pressure (SLP) or Caribbean precipitation. It is observed that the main anomalous climate pattern associated with an anomalously strong CALLJ is one with low SLP and warm sea surface temperature (SST) anomalies in the tropical Pacific and high SLP and cool SST anomalies in the tropical Atlantic and the Caribbean. These climate anomalies force remotely the CALLJ through changes in the Caribbean SLP gradients while local feedbacks amplify the effects. Less precipitation over large areas of the Caribbean and Central America is due to stronger vertical wind shear and moisture flux divergence related to a strengthening of the CALLJ. The findings contribute to a better understanding of the climate interactions in the Caribbean region in light of the CALLJ variability and controls.

  7. Low level laser therapy reduces inflammation in activated Achilles tendinitis

    NASA Astrophysics Data System (ADS)

    Bjordal, Jan M.; Iversen, Vegard; Lopes-Martins, Rodrigo Alvaro B.

    2006-02-01

    Objective: Low level laser therapy (LLLT) has been forwarded as therapy for osteoarthritis and tendinopathy. Results in animal and cell studies suggest that LLLT may act through a biological mechanism of inflammatory modulation. The current study was designed to investigate if LLLT has an anti-inflammatory effect on activated tendinitis of the Achilles tendon. Methods: Seven patients with bilateral Achilles tendonitis (14 tendons) who had aggravated symptoms by pain-inducing activity immediately prior to the study. LLLT (1.8 Joules for each of three points along the Achilles tendon with 904nm infrared laser) and placebo LLLT were administered to either Achilles tendons in a random order to which patients and therapist were blinded. Inflammation was examined by 1) mini-invasive microdialysis for measuring the concentration of inflammatory marker PGE II in the peritendinous tissue, 2) ultrasound with Doppler measurement of peri- and intratendinous blood flow, 3) pressure pain algometry and 4) single hop test. Results: PGE 2- levels were significantly reduced at 75, 90 and 105 minutes after active LLLT compared both to pre-treatment levels (p=0.026) and to placebo LLLT (p=0.009). Changes in pressure pain threshold (PPT) were significantly different (P=0.012) between groups. PPT increased by a mean value of 0.19 kg/cm2 [95%CI:0.04 to 0.34] after treatment in the active LLLT group, while pressure pain threshold was reduced by -0.20 kg/cm2 [95%CI:-0.45 to 0.05] after placebo LLLT. Conclusion: LLLT can be used to reduce inflammatory musculskeletal pain as it reduces inflammation and increases pressure pain threshold levels in activity-induced pain episodes of Achilles tendinopathy.

  8. Benchmark Study of 3D Pore-scale Flow and Solute Transport Simulation Methods

    NASA Astrophysics Data System (ADS)

    Scheibe, T. D.; Yang, X.; Mehmani, Y.; Perkins, W. A.; Pasquali, A.; Schoenherr, M.; Kim, K.; Perego, M.; Parks, M. L.; Trask, N.; Balhoff, M.; Richmond, M. C.; Geier, M.; Krafczyk, M.; Luo, L. S.; Tartakovsky, A. M.

    2015-12-01

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that benchmark study to include additional models of the first type based on the immersed-boundary method (IMB), lattice Boltzmann method (LBM), and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries in the manner of PNMs has not been fully determined. We apply all five approaches (FVM-based CFD, IMB, LBM, SPH and PNM) to simulate pore-scale velocity distributions and nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The benchmark study was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This study provides support for confidence in a variety of pore-scale modeling methods, and motivates further development and application of pore-scale simulation methods.

  9. Numerical simulation of fracture permeability evolution due to reactive transport and pressure solution processes

    NASA Astrophysics Data System (ADS)

    Watanabe, N.; Sun, Y.; Taron, J.; Shao, H.; Kolditz, O.

    2013-12-01

    Modeling fracture permeability evolution is of great interest in various geotechnical applications including underground waste repositories, carbon capture and storage, and engineered geothermal systems where fractures dominate transport behaviors. In this study, a numerical model is presented to simulate fracture permeability evolution due to reactive transport and pressure solution processes in single fractures. The model was developed within the international benchmarking project for radioactive waste disposals, DECOVALEX 2015 (Task C1). The model combines bulk behavior in pore spaces with intergranular process at asperity contacts. Hydraulic flow and reactive transport including mineral dissolution and precipitation in fracture pore space are simulated using the Galerkin finite element method. A pressure solution model developed by Taron and Elsworth (2010 JGR) is applied to simulating stress-enhanced dissolution, solute exchange with pore space, and volume removal at grain contacts. Fracture aperture and contact area ratio are updated as a result of the pore-space reaction and intergranular dissolution. In order to increase robustness and time step size, relevant processes are monolithically coupled with the simulations. The model is implemented in a scientific open-source project OpenGeoSys (www.opengeosys.org) for numerical simulation of thermo-hydro-mechanical/chemical processes in porous and fractured media. Numerical results are compared to previous experiment performed by Yasuhara et al. (2006) on flow through fractures in the Arkansas novaculite sample. The novaculite is approximated as pure quartz aggregates. Only with fitted quartz dissolution rate constants and solubility is the current model capable of reproducing observed hydraulic aperture reduction and aqueous silicate concentrations. Future work will examine reaction parameters and further validate the model against experimental results.

  10. Caffeine and Sugars Interact in Aqueous Solutions: A Simulation and NMR Study

    PubMed Central

    Tavagnacco, Letizia; Engström, Olof; Schnupf, Udo; Saboungi, Marie-Louise; Himmel, Michael; Widmalm, Göran; Cesàro, Attilio; Brady, John W.

    2012-01-01

    Molecular dynamics simulations were carried out on several systems of caffeine interacting with simple sugars. These included a single caffeine molecule in a 3 molal solution of α-D-glucopyranose, at a caffeine concentration of 0.083 molal; a single caffeine in a 3 molal solution of β-D-glucopyranose, and a single caffeine molecule in a 1.08 molal solution of sucrose (table sugar). Parallel Nuclear Magnetic Resonance titration experiments were carried out on the same solutions under similar conditions. Consistent with previous thermodynamic experiments, the sugars were found to have an affinity for the caffeine molecules in both the simulations and experiments, and that the binding in these complexes occurs by face-to-face stacking of the hydrophobic triad of protons of the pyranose rings against the caffeine face, rather than by hydrogen bonding. For the disaccharide, the binding occurs via stacking of the glucose ring against the caffeine, with a lesser affinity for the fructose observed. These findings are consistent with the association being driven by hydrophobic hydration, and are similar to the previously observed binding of glucose rings to various other planar molecules, including indole, serotonin, and phenol. PMID:22897449

  11. Preferential Solvation in Urea Solutions at Different Concentrations: Properties from Simulation Studies.

    SciTech Connect

    Kokubo, Hironori; Pettitt, Bernard M.

    2007-02-15

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We performed molecular dynamics simulations of urea solutions at different concentrations with two urea models (OPLS and KBFF) to examine the structures responsible for the thermodynamic solution properties. Our simulation results showed that hydrogen-bonding properties such as the average number of hydrogen bonds and their lifetime distributions were nearly constant at all concentrations between infinite dilution and the solubility limit. This implies that the characterization of urea-water solutions in the molarity concentration scale as nearly ideal is a result of facile local hydrogen bonding rather than a global property. Thus, urea concentration does not influence the local propensity for hydrogen bonds, only how they are satisfied. By comparison, the KBFF model of urea donated fewer hydrogen bonds than OPLS. We found that the KBFF urea model in TIP3P water better reproduced the experimental density and diffusion constant data. Preferential solvation analysis showed that there were weak urea-urea and water-water associations in OPLS solution at short distances, but there were no strong associations. We divided urea molecules into large, medium, and small clusters to examine fluctuation properties and found that any particular urea molecule did not stay in the same cluster for a long time. We found neither persistent nor large clusters.

  12. Preferential Solvation in Urea Solutions at Different Concentrations: Properties from Simulation Studies

    SciTech Connect

    Kokubo, Hironori; Pettitt, Bernard M.

    2007-04-21

    We performed molecular dynamics simulations of urea solutions at different concentrations with two urea models (OPLS and KBFF) to examine the structures responsible for the thermodynamic solution properties. Our simulation results showed that hydrogen-bonding properties such as the average number of hydrogen bonds and their lifetime distributions were nearly constant at all concentrations between infinite dilution and the solubility limit. This implies that the characterization of urea-water solutions in the molarity concentration scale as nearly ideal is a result of facile local hydrogen bonding rather than a global property. Thus, urea concentration does not influence the local propensity for hydrogen bonds, only how they are satisfied. By comparison, the KBFF model of urea donated fewer hydrogen bonds than OPLS. We found that the KBFF urea model in TIP3P water better reproduced the experimental density and diffusion constant data. Preferential solvation analysis showed that there were weak urea-urea and water-water associations in OPLS solution at short distances, but there were no strong associations. We divided urea molecules into large, medium, and small clusters to examine fluctuation properties and found that any particular urea molecule did not stay in the same cluster for a long time. We found neither persistent nor large clusters.

  13. Optical coherence tomography images simulated with an analytical solution of Maxwell's equations for cylinder scattering

    NASA Astrophysics Data System (ADS)

    Brenner, Thomas; Reitzle, Dominik; Kienle, Alwin

    2016-04-01

    An algorithm for the simulation of image formation in Fourier domain optical coherence tomography (OCT) for an infinitely long cylinder is presented. The analytical solution of Maxwell's equations for light scattering by a single cylinder is employed for the case of perpendicular incidence to calculate OCT images. The A-scans and the time-resolved scattered intensities are compared to geometrical optics results calculated with a ray tracing approach. The reflection peaks, including the whispering gallery modes, are identified. Additionally, the Debye series expansion is employed to identify single peaks in the OCT A-scans. Furthermore, a Gaussian beam is implemented in order to simulate lateral scanning over the cylinder for two-dimensional B-scans. The fields are integrated over a certain angular range to simulate a detection aperture. In addition, the solution for light scattering by layered cylinders is employed and the various layers are identified in the resulting OCT image. Overall, the simulations in this work show that OCT images do not always display the real surface of investigated samples.

  14. Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations.

    PubMed

    Monti, Susanna; Carravetta, Vincenzo; Ågren, Hans

    2016-07-14

    The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption. PMID:27305447

  15. PHAST Version 2-A Program for Simulating Groundwater Flow, Solute Transport, and Multicomponent Geochemical Reactions

    USGS Publications Warehouse

    Parkhurst, David L.; Kipp, Kenneth L.; Charlton, Scott R.

    2010-01-01

    The computer program PHAST (PHREEQC And HST3D) simulates multicomponent, reactive solute transport in three-dimensional saturated groundwater flow systems. PHAST is a versatile groundwater flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. Major enhancements in PHAST Version 2 allow spatial data to be defined in a combination of map and grid coordinate systems, independent of a specific model grid (without node-by-node input). At run time, aquifer properties are interpolated from the spatial data to the model grid; regridding requires only redefinition of the grid without modification of the spatial data. PHAST is applicable to the study of natural and contaminated groundwater systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock/water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, or density-dependent flow. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux (specified-flux), and leaky (head-dependent) conditions, as well as the special cases of rivers, drains, and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association or Pitzer specific interaction thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, ion exchange sites, surface complexation sites, solid solutions, and gases; and

  16. Low-Level Educational Achievements in the UAE Model Schools

    ERIC Educational Resources Information Center

    Sarsar, Nasreddine

    2007-01-01

    This research paper explores in depth the real causes behind underachievement among students at UAE Model Schools. The researcher suggests practical solutions to turn Model Schools into high-performance schools. He also sets out to discuss the issue of NESTs Vs NNESTs and the implications of such a distinction for the education profession. The aim…

  17. Use of Analytical Solutions to Optimize Simulation of Multicomponent Three-Phase Displacements

    NASA Astrophysics Data System (ADS)

    Laforce, Tara

    2010-05-01

    The conservation law for oil/water/gas flow in porous media can be highly sensitive to numerical dispersive effects, particularly in systems with substantial partitioning of components between the gas and oil phases. As a consequence, it is not typically possible to perform field-scale simulations with a sufficiently fine-grid to accurately model compositional displacements such as CO2 injection into oil fields for storage or enhanced oil recovery (EOR). The purpose of this study is to use analytical results to demonstrate the numerical errors in water and gas injection simulations in one dimension (1D) and to discuss the applicability of simplified models in obtaining an accurate simulated solution. Recently analytical solutions have become available for simultaneous water and gas (sWAG) flooding for three-phase multicomponent compositional systems (LaForce and Orr, 2009). This work showed the surprising result that excessive water injection can interfere with the development of multicontact miscibility (MCM) between the oil and gas phases. Multicontact miscibility occurs when a combination of thermodynamics and flow through porous media cause the formation of a single hydrocarbon phase. When MCM occurs hydrocarbons are displaced from the reservoir much more efficiently than in an immiscible gas or water flood. This presentation will compare and contrast the predicted displacements to a variety of models for sWAG flooding, including injection of water and a first-contact miscible (FCM) gas, three-phase compositional systems with developed miscibility and inert water (the aqueous phase contains only water, and water exists in only the aqueous phase) and compositional systems with developed miscibility in which all of the hydrocarbon components partition between all of the phases, but the water remains in the aqueous phase. Simulated solutions for each of the models are compared with the analytical solutions for various injection mixtures. This analysis can be used

  18. PHAST--a program for simulating ground-water flow, solute transport, and multicomponent geochemical reactions

    USGS Publications Warehouse

    Parkhurst, David L.; Kipp, Kenneth L.; Engesgaard, Peter; Charlton, Scott R.

    2004-01-01

    The computer program PHAST simulates multi-component, reactive solute transport in three-dimensional saturated ground-water flow systems. PHAST is a versatile ground-water flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. PHAST is applicable to the study of natural and contaminated ground-water systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock-water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, density-dependent flow, or waters with high ionic strengths. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux, and leaky conditions, as well as the special cases of rivers and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, gases, surface complexation sites, ion exchange sites, and solid solutions; and (3) kinetic reactions with rates that are a function of solution composition. The aqueous model (elements, chemical reactions, and equilibrium constants), minerals, gases, exchangers, surfaces, and rate expressions may be defined or modified by the user. A number of options are available to save results of simulations to output files. The data may be saved in three formats: a format suitable for viewing with a text editor; a

  19. From single Debye-Hückel chains to polyelectrolyte solutions: Simulation results

    NASA Astrophysics Data System (ADS)

    Kremer, Kurt

    1996-03-01

    This lecture will present results from simulations of single weakly charged flexible chains, where the electrostatic part of the interaction is modeled by a Debye-Hückel potential,( with U. Micka, IFF, Forschungszentrum Jülich, 52425 Jülich, Germany) as well as simulations of polyelectrolyte solutions, where the counterions are explicitly taken into account( with M. J. Stevens, Sandia Nat. Lab., Albuquerque, NM 87185-1111) ( M. J. Stevens, K. Kremer, JCP 103), 1669 (1995). The first set of the simulations is meant to clear a recent contoversy on the dependency of the persistence length LP on the screening length Γ. While the analytic theories give Lp ~ Γ^x with either x=1 or x=2, the simulations find for all experimentally accessible chain lengths a varying exponent, which is significantly smaller than 1. This causes serious doubts on the applicability of this model for weakly charged polyelectrolytes in general. The second part deals with strongly charged flexible polyelectrolytes in salt free solution. These simulations are performed for multichain systems. The full Coulomb interactions of the monomers and counterions are treated explicitly. Experimental measurements of the osmotic pressure and the structure factor are reproduced and extended. The simulations reveal a new picture of the chain structure based on calculations of the structure factor, persistence length, end-to-end distance, etc. Even at very low density, the chains show significant bending. Furthermore, the chains contract significantly before they start to overlap. We also show that counterion condensation dramatically alters the chain structure, even for a good solvent backbone.

  20. Decoration of gold nanoparticles with cysteine in solution: reactive molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Monti, Susanna; Carravetta, Vincenzo; Ågren, Hans

    2016-06-01

    The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption.The dynamics of gold nanoparticle functionalization by means of adsorption of cysteine molecules in water solution is simulated through classical reactive molecular dynamics simulations based on an accurately parametrized force field. The adsorption modes of the molecules are characterized in detail disclosing the nature of the cysteine-gold interactions and the stability of the final material. The simulation results agree satisfactorily with recent experimental and theoretical data and confirm previous findings for a similar system. The covalent attachments of the molecules to the gold support are all slow physisorptions followed by fast chemisorptions. However, a great variety of binding arrangements can be observed. Interactions with the adsorbate caused surface modulations in terms of adatoms and dislocations which contributed to strengthen the cysteine adsorption. Electronic supplementary information (ESI) available: Different views of the AuNP surface coverage. Distance map describing the position of each molecule in relation to the others on the AuNP (alpha carbon distances). See DOI: 10.1039/C

  1. Measurement of Low Level Explosives Reaction in the Two-Dimensional Steven Impact Test

    SciTech Connect

    Forbes, J.W.; Tarver, C.M.; Chidester, S.K.; Garcia, F.; Greenwood, D.W.; Garza, R.

    2000-10-10

    The two-dimensional Steven impact test has been developed to be reproducible and amenable to computer modeling. This test has a hemispherical projectile traveling at tens of m/s impacting a metal cased explosive target. To assist in the understanding of this safety test, two-dimensional shock wave gauge techniques were used to measure the pressures of a few kilobars and times of reactions less than a millisecond. This work is in accord with a long-term goal to develop two-dimensional shock diagnostic techniques that are more than just time of arrival indicators. Experiments were performed where explosives were impacted at levels below shock initiation levels but caused low level reactions. Carbon foil and carbon resistor pressure gauges were used to measure pressures and time of events. The carbon resistor gauges indicate a late time low level reaction at 350 {micro}s after impact of the hemispherical projectile creating 0.5-6 kb peak shocks at the center of PBX 9501 (HMX/Estane/BDNPA-F; 95/2.5/2.5 wt %) explosive discs. The Steven test calculations are based on an ignition and growth criteria and found that the low level reaction occurs at 335 {micro}s, which is in good agreement with the experimental data. Some additional experiments simulating the Steven impact test were done on a gas gun with carbon foil and constantan strain gauges in a PMMA target. Hydrodynamic calculations can be used to evaluate the gauge performance in these experiments and check the lateral strain measurements.

  2. Aggregation in dilute aqueous tert-butyl alcohol solutions: Insights from large-scale simulations

    NASA Astrophysics Data System (ADS)

    Gupta, Rini; Patey, G. N.

    2012-07-01

    Molecular dynamics simulations employing up to 64 000 particles are used to investigate aggregation and microheterogeneity in aqueous tert-butyl alcohol (TBA) solutions for TBA mole fractions Xt ⩽ 0.1. Four different force fields are considered. It is shown that the results obtained can be strongly dependent on the particular force field employed, and can be significantly influenced by system size. Two of the force fields considered show TBA aggregation in the concentration range Xt ≈ 0.03 - 0.06. For these models, systems of 64 000 particles are minimally sufficient to accommodate the TBA aggregates. The structures resulting from TBA aggregation do not have a well-defined size and shape, as one might find in micellar systems, but are better described as TBA-rich and water-rich regions. All pair correlation functions exhibit long-range oscillatory behavior with wavelengths that are much larger than molecular length scales. The oscillations are not strongly damped and the correlations can easily exceed the size of the simulation cell, even for the low TBA concentrations considered here. We note that these long-range correlations pose a serious problem if one wishes to obtain certain physical properties such as Kirkwood-Buff integrals from simulation results. In contrast, two other force fields that we consider show little sign of aggregation for Xt ≲ 0.08. In our 64 000 particle simulations all four models considered show demixing-like behavior for Xt ≳ 0.1, although such behavior is not evident in smaller systems of 2000 particles. The meaning of the demixing-like behavior is unclear. Since real TBA-water solutions do not demix, it might be an indication that all four models we consider poorly represent the real system. Alternatively, it might be an artifact of finite system size. Possibly, the apparent demixing indicates that for Xt ≳ 0.1, the stable TBA aggregates are simply too large to fit into the simulation cell. Our results provide a view of the

  3. WATSFAR: numerical simulation of soil WATer and Solute fluxes using a FAst and Robust method

    NASA Astrophysics Data System (ADS)

    Crevoisier, David; Voltz, Marc

    2013-04-01

    To simulate the evolution of hydro- and agro-systems, numerous spatialised models are based on a multi-local approach and improvement of simulation accuracy by data-assimilation techniques are now used in many application field. The latest acquisition techniques provide a large amount of experimental data, which increase the efficiency of parameters estimation and inverse modelling approaches. In turn simulations are often run on large temporal and spatial domains which requires a large number of model runs. Eventually, despite the regular increase in computing capacities, the development of fast and robust methods describing the evolution of saturated-unsaturated soil water and solute fluxes is still a challenge. Ross (2003, Agron J; 95:1352-1361) proposed a method, solving 1D Richards' and convection-diffusion equation, that fulfil these characteristics. The method is based on a non iterative approach which reduces the numerical divergence risks and allows the use of coarser spatial and temporal discretisations, while assuring a satisfying accuracy of the results. Crevoisier et al. (2009, Adv Wat Res; 32:936-947) proposed some technical improvements and validated this method on a wider range of agro- pedo- climatic situations. In this poster, we present the simulation code WATSFAR which generalises the Ross method to other mathematical representations of soil water retention curve (i.e. standard and modified van Genuchten model) and includes a dual permeability context (preferential fluxes) for both water and solute transfers. The situations tested are those known to be the less favourable when using standard numerical methods: fine textured and extremely dry soils, intense rainfall and solute fluxes, soils near saturation, ... The results of WATSFAR have been compared with the standard finite element model Hydrus. The analysis of these comparisons highlights two main advantages for WATSFAR, i) robustness: even on fine textured soil or high water and solute

  4. Low-level vibrations maintain the intervertebral disc during unloading

    NASA Astrophysics Data System (ADS)

    Holguin, Nilsson

    Changes in intervertebral disc (IVD) biochemistry, morphology and mechanics have been characterized only incompletely in the rat hindlimb unloading (HU) model. Although exposure to chronic vibrations can be damaging, low-magnitude vibrations can attenuate the geometric changes of the IVD due to altered spinal loading. Here, we tested the hypothesis that low-magnitude, high-frequency vibrations will mitigate the hypotrophy, biochemical degradation and deconditioning of the IVD during HU. When applied as whole-body vibrations through all four paws, Sprague-Dawley rats were subjected to HU and exposed to daily periods (15min/d) of either ambulatory activities (HU+AMB) or whole body vibrations superimposed upon ambulation (HU+WBV; WBV at 45Hz, 0.3g). After 4wks and, compared to age-matched control rats (AC), the lumbar IVD of HU+AMB had a 22% smaller glycosaminoglycans/collagen ratio, 12% smaller posterior IVD height, and 13% smaller cross-sectional area. Compared to HU+AMB rats, the addition of low-level vibratory loading did not significantly alter IVD biochemistry, posterior height, area, or volume, but directionally altered IVD geometry. When subjected to upright vibrations through the hindpaws, rats were HU for 4wks. A subset of HU rats stood in an upright posture on a vertically oscillating plate (0.2g) at 45- or 90-Hz (HU+45 or HU+90). After 4wks, regardless of sham (HU+SC) loading (HU+/-SC) and, compared to AC, IVD of HU+/-SC had 10% less height, 39% smaller nucleus pulposus area, less glycosaminoglycans in the nucleus pulposus (21%), anterior annulus fibrosus (16%) and posterior annulus fibrosus (19%), 76% less tension-compression neutral zone (NZ) modulus, 26% greater compressive modulus, 25% greater initial elastic damping modulus, 26% less torsional NZ stiffness, no difference in collagen content and a weaker relationship between tension-compression NZ modulus and posterior height change. Exogenously introduced oscillations maintained the morphology

  5. SECONDARY LOW-LEVEL WASTE GENERATION RATE ANALYSIS

    SciTech Connect

    D. LaRue

    1999-05-10

    The objective of this design analysis is -to update the assessment of estimated annual secondary low-level waste (LLW) generation rates resulting from the repackaging of spent nuclear fuel (SNF) and high-level waste (HLW) for disposal at the Monitored Geologic Repository (MGR). This analysis supports the preparation of documentation necessary for license application (LA) for the MGR. For the purposes of this analysis, secondary LLW is defined, in brief terms, as LLW generated as a direct result of processing SNF/HLW through the receiving and repackaging operations. The current Waste Handling Building (WHB) design is based on the predominant movement of fuel assemblies through the wet handling lines within the WHB. Dry handling lines are also included in the current WHB design to accommodate canistered waste (i.e., SNF and/or HLW packages). Major input changes to this analysis in comparison to previous analyses include: (1) changes in the SNF/HLW arrival schedules; (2) changes to the WHB and the Waste Treatment Building (WTB) dimensions; and (3) changes in operational staff sizes within the WHB and WTB. The rates generated in this analysis can be utilized to define necessary waste processes, waste flow rates, and equipment sizes for the processing of secondary LLW for proper disposal. This analysis is based on the present reference design, i.e., Viability Assessment (VA) design, and present projections on spent fuel delivery and processing. LLW generation rates, for both liquids and solids, are a direct function of square footages in radiological areas, and a direct function of spent fuel throughput. Future changes in the approved reference design or spent fuel throughput will directly impact the LLW generation rates defined in this analysis. Small amounts of wastes other than LLW may be generated on a non-routine basis. These wastes may include transuranic (TRU), hazardous, and mixed wastes. Although the objective of this analysis is to define LLW waste generation

  6. Cellular chromophores and signaling in low level light therapy

    NASA Astrophysics Data System (ADS)

    Hamblin, Michael R.; Demidova-Rice, Tatiana N.

    2007-02-01

    The use of low levels of visible or near infrared light (LLLT) for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage by reducing cellular apoptosis has been known for almost forty years since the invention of lasers. Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. This likely is due to two main reasons; firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. In recent years major advances have been made in understanding the mechanisms that operate at the cellular and tissue levels during LLLT. Mitochondria are thought to be the main site for the initial effects of light and specifically cytochrome c oxidase that has absorption peaks in the red and near infrared regions of the electromagnetic spectrum matches the action spectra of LLLT effects. The discovery that cells employ nitric oxide (NO) synthesized in the mitochondria by neuronal nitric oxide synthase, to regulate respiration by competitive binding to the oxygen binding of cytochrome c oxidase, now suggests how LLLT can affect cell metabolism. If LLLT photodissociates inhibitory NO from cytochrome c oxidase, this would explain increased ATP production, modulation of reactive oxygen species, reduction and prevention of apoptosis, stimulation of angiogenesis, increase of blood flow and induction of transcription factors. In

  7. Closure Plan for Active Low Level Burial Grounds

    SciTech Connect

    SKELLY, W.A.

    2000-11-16

    This plan has been prepared in response to direction from the U.S. Department of Energy. The purpose of the plan is to define approaches that will be implemented to ensure protection of the public and the environment when active Low-Level Burial Grounds (LLBGs) at the Hanford Site are closed. Performance assessments for active burial grounds in the 200 East and West 200 Areas provide current estimates of potential environmental contamination and doses to the ''maximum exposed individual'' from burial ground operation and closure and compare dose estimates to performance objective dose limits for the facilities. This is an Operational Closure Plan. The intent of the guidance in DOE Order 435.1 is that this plan will be a living document, like the facility performance assessments, and will be revised periodically through the operational life of the LLBGs to reflect updated information on waste inventory. management practices, facility transition planning, schedule dates, assessments of post-closure performance, and environmental consequences. Out year dates identified in this plan are tentative. A Final Closure Plan will be prepared in the future when the timing and extent of closure-related activities for LLBGs can be established with greater certainty. After current operations at the LLBGs are concluded, this plan proposes transitioning of these facilities to the Environmental Restoration Program. This action will enable the Environmental Restoration Program to design and implement consistent and coordinated final remedial actions for active and inactive LLBGs. Active and inactive burial grounds in the 200 West and 200 East Areas are commingled. This plan describes approaches that will be implemented during Interim Closure, Final Closure, and Institutional Control Periods to prepare LLBGs for surface barriers, and the construction of barriers, as well as the scope of inspection, monitoring and maintenance practices that will be performed during and after closure

  8. Peat: a natural repository for low-level radioactive waste

    SciTech Connect

    Thomas, E.D.

    1985-12-01

    A study has been initiated to evaluate the possibility of using peat as a natural repository for the disposal of low-level radioactive waste. One aspect of this study was to determine the retentive properties of the peat through measurements of the distribution coefficients (K/sub d/) for Am-241, Ru-106, Cs-137, Co-57, and Sr-85 in two layers of mountain top peat bogs from Lefgren's, NY, and Spruce Flats, PA. These K/sub d/ values were then compared to literature values of various sediment/water systems at similar environmental conditions. Am-241, Ru-106, Co-57, and Sr-85 attained distribution coefficients in the organic rich layers of the bogs two orders of magnitude greater than those obtained previously at pH 4.0. Although, the Cs-137 sorbed strongly to the inorganic rich layer of the Spruce Flats, PA, bog, the K/sub d/ values obtained for this isotope were, again, comparable or higher than those reported previously at pH 4.0, indicating the greater retentive properties of the peat. A chromatographic ''theoretical plate'' model was used to describe the field migration of Cs-137. The advection and diffusion coefficients were higher in the Lefgren's Bog, NY, than those obtained for the Spruce Flats Bog, PA. These field data were substantiated by the lower Cs-137 K/sub d/ values determined in the laboratory for the Lefgren's Bog, NY, compared to the Spruce Flats Bog. Although this model gave a good indication of the field migration, it neglected the process of sorption as defined by the sorption isotherm. Based on the time series data on distribution ratio measurements, a Cameron-Klute type of sorption isotherm was indicated, with rapid equilibrium initially superimposed onto a slower first order linear reversible equilibrium. This sorption isotherm can then be used in the final form of a model to describe the migration of radionuclides in a peat bog. 19 refs., 15 figs., 10 tabs.

  9. Molecular Dynamics Simulation of the Titration of Polyoxocations in Aqueous Solution

    SciTech Connect

    Rustad, James R.

    2005-09-01

    The aqueous complex ion Al30O8(OH)56(H2O)26 18+(Al30) has a variety of bridging and terminal amphoteric surface functional groups which deprotonate over a pH range of 4–7. Their relative degree of protonation is calculated here from a series of molecular dynamics simulations in what appear to be the first molecular dynamics simulations of an acidometric titration. In these simulations, a model M30O8(OH)56(H2O)26 18+ ion is embedded in aqueous solution and titrated with hydroxide ions in the presence of a charge-compensating background of perchlorate ions. Comparison with titration of a model M13O4(OH)24(H2O)12 7+ reveals that the M30 ion is more acidic than the M13 ion due to the presence of acidic nH2O functional groups. The higher acidities of the functional groups on the M30 ion appear to result from enhanced hydration. Metal–oxygen bond lengths are calculated for the ion in solution, an isolated ion in the gas phase, and in its crystalline hydrate sulfate salt. Gas-phase and crystalline bond lengths do not correlate well with those calculated in solution. The acidities do not relate in any simple way to the number of metals coordinating the surface functional group or the M-O bond length. Moreover, the calculated acidity in solution does not correlate with proton affinities calculated for the isolated ion in the absence of solvent. It is concluded that the search for simple indicators of structure–reactivity relationships at the level of individual reactive sites faces major limitations, unless specific information on the hydration states of the functional groups is available.

  10. Dynamic simulation of concentrated macromolecular solutions with screened long-range hydrodynamic interactions: Algorithm and limitations

    PubMed Central

    Ando, Tadashi; Chow, Edmond; Skolnick, Jeffrey

    2013-01-01

    Hydrodynamic interactions exert a critical effect on the dynamics of macromolecules. As the concentration of macromolecules increases, by analogy to the behavior of semidilute polymer solutions or the flow in porous media, one might expect hydrodynamic screening to occur. Hydrodynamic screening would have implications both for the understanding of macromolecular dynamics as well as practical implications for the simulation of concentrated macromolecular solutions, e.g., in cells. Stokesian dynamics (SD) is one of the most accurate methods for simulating the motions of N particles suspended in a viscous fluid at low Reynolds number, in that it considers both far-field and near-field hydrodynamic interactions. This algorithm traditionally involves an O(N3) operation to compute Brownian forces at each time step, although asymptotically faster but more complex SD methods are now available. Motivated by the idea of hydrodynamic screening, the far-field part of the hydrodynamic matrix in SD may be approximated by a diagonal matrix, which is equivalent to assuming that long range hydrodynamic interactions are completely screened. This approximation allows sparse matrix methods to be used, which can reduce the apparent computational scaling to O(N). Previously there were several simulation studies using this approximation for monodisperse suspensions. Here, we employ newly designed preconditioned iterative methods for both the computation of Brownian forces and the solution of linear systems, and consider the validity of this approximation in polydisperse suspensions. We evaluate the accuracy of the diagonal approximation method using an intracellular-like suspension. The diffusivities of particles obtained with this approximation are close to those with the original method. However, this approximation underestimates intermolecular correlated motions, which is a trade-off between accuracy and computing efficiency. The new method makes it possible to perform large-scale and

  11. Transport of conservative solutes in simulated fracture networks: 1. Synthetic data generation

    NASA Astrophysics Data System (ADS)

    Reeves, Donald M.; Benson, David A.; Meerschaert, Mark M.

    2008-05-01

    This paper investigates whether particle ensembles in a fractured rock domain may be adequately modeled as an operator-stable plume. If this statistical model applies to transport in fractured media, then an ensemble plume in a fractured rock domain may be modeled using the novel Fokker-Planck evolution equation of the operator-stable plume. These plumes (which include the classical multi-Gaussian as a subset) are typically characterized by power law leading-edge concentration profiles and super-Fickian growth rates. To investigate the possible correspondence of ensemble plumes to operator-stable densities, we use numerical simulations of fluid flow and solute transport through large-scale (2.5 km by 2.5 km), randomly generated fracture networks. These two-dimensional networks are generated according to fracture statistics obtained from field studies that describe fracture length, transmissivity, density, and orientation. A fracture continuum approach using MODFLOW is developed for the solution of fluid flow within the fracture network and low-permeability rock matrix, while a particle-tracking code, random walk particle method for simulating transport in heterogeneous permeable media (RWHet), is used to simulate the advective motion of conservative solutes through the model domain. By deterministically mapping individual fractures onto a highly discretized finite difference grid (1 m × 1 m × 1 m here), the MODFLOW "continuum" simulations can faithfully preserve details of the generated network and can approximate fluid flow in a discrete fracture network model. An advantage of the MODFLOW approach is that matrix permeability can be made nonzero to account for any degree of matrix flow and/or transport.

  12. Dynamic simulation of concentrated macromolecular solutions with screened long-range hydrodynamic interactions: Algorithm and limitations

    NASA Astrophysics Data System (ADS)

    Ando, Tadashi; Chow, Edmond; Skolnick, Jeffrey

    2013-09-01

    Hydrodynamic interactions exert a critical effect on the dynamics of macromolecules. As the concentration of macromolecules increases, by analogy to the behavior of semidilute polymer solutions or the flow in porous media, one might expect hydrodynamic screening to occur. Hydrodynamic screening would have implications both for the understanding of macromolecular dynamics as well as practical implications for the simulation of concentrated macromolecular solutions, e.g., in cells. Stokesian dynamics (SD) is one of the most accurate methods for simulating the motions of N particles suspended in a viscous fluid at low Reynolds number, in that it considers both far-field and near-field hydrodynamic interactions. This algorithm traditionally involves an O(N3) operation to compute Brownian forces at each time step, although asymptotically faster but more complex SD methods are now available. Motivated by the idea of hydrodynamic screening, the far-field part of the hydrodynamic matrix in SD may be approximated by a diagonal matrix, which is equivalent to assuming that long range hydrodynamic interactions are completely screened. This approximation allows sparse matrix methods to be used, which can reduce the apparent computational scaling to O(N). Previously there were several simulation studies using this approximation for monodisperse suspensions. Here, we employ newly designed preconditioned iterative methods for both the computation of Brownian forces and the solution of linear systems, and consider the validity of this approximation in polydisperse suspensions. We evaluate the accuracy of the diagonal approximation method using an intracellular-like suspension. The diffusivities of particles obtained with this approximation are close to those with the original method. However, this approximation underestimates intermolecular correlated motions, which is a trade-off between accuracy and computing efficiency. The new method makes it possible to perform large-scale and

  13. Implicit solution of the material transport in Stokes flow simulation: Toward thermal convection simulation surrounded by free surface

    NASA Astrophysics Data System (ADS)

    Furuichi, Mikito; May, Dave A.

    2015-07-01

    We present implicit time integration schemes suitable for modeling free surface Stokes flow dynamics with marker in cell (MIC) based spatial discretization. Our target is for example thermal convection surrounded by deformable surface boundaries to simulate the long term planetary formation process. The numerical system becomes stiff when the dynamical balancing time scale for the increasing/decreasing load by surface deformation is very short compared with the time scale associated with thermal convection. Any explicit time integration scheme will require very small time steps; otherwise, serious numerical oscillation (spurious solutions) will occur. The implicit time integration scheme possesses a wider stability region than the explicit method; therefore, it is suitable for stiff problems. To investigate an efficient solution method for the stiff Stokes flow system, we apply first (backward Euler (BE)) and second order (trapezoidal method (TR) and trapezoidal rule-backward difference formula (TR-BDF2)) accurate implicit methods for the MIC solution scheme. The introduction of implicit time integration schemes results in nonlinear systems of equations. We utilize a Jacobian free Newton Krylov (JFNK) based Newton framework to solve the resulting nonlinear equations. In this work we also investigate two efficient implicit solution strategies to reduce the computational cost when solving stiff nonlinear systems. The two methods differ in how the advective term in the material transport evolution equation is treated. We refer to the method that employs Lagrangian update as "fully implicit" (Imp), whilst the method that employs Eulerian update is referred to as "semi-implicit" (SImp). Using a finite difference (FD) method, we have performed a series of numerical experiments which clarify the accuracy of solutions and trade-off between the computational cost associated with the nonlinear solver and time step size. In comparison with the general explicit Euler method

  14. Multiphase flow experiments, mathematical modeling and numerical simulation of the water - gas - solute movement

    NASA Astrophysics Data System (ADS)

    Li, Y.; Ma, X.; Su, N.

    2013-12-01

    The movement of water and solute into and through the vadose zone is, in essence, an issue of immiscible displacement in pore-space network of a soil. Therefore, multiphase flow and transport in porous media, referring to three medium: air, water, and the solute, pose one of the largest unresolved challenges for porous medium fluid seepage. However, this phenomenon has always been largely neglected. It is expected that a reliable analysis model of the multi-phase flow in soil can truly reflect the process of natural movement about the infiltration, which is impossible to be observed directly. In such cases, geophysical applications of the nuclear magnetic resonance (NMR) provides the opportunity to measure the water movements into soils directly over a large scale from tiny pore to regional scale, accordingly enable it available both on the laboratory and on the field. In addition, the NMR provides useful information about the pore space properties. In this study, we proposed both laboratory and field experiments to measure the multi-phase flow parameters, together with optimize the model in computer programming based on the fractional partial differential equations (fPDE). In addition, we establish, for the first time, an infiltration model including solute flowing with water, which has huge influence on agriculture and soil environment pollution. Afterwards, with data collected from experiments, we simulate the model and analyze the spatial variability of parameters. Simulations are also conducted according to the model to evaluate the effects of airflow on water infiltration and other effects such as solute and absorption. It has significant meaning to oxygen irrigation aiming to higher crop yield, and shed more light into the dam slope stability. In summary, our framework is a first-time model added in solute to have a mathematic analysis with the fPDE and more instructive to agriculture activities.

  15. Poleward shift in Indian summer monsoon low level jetstream under global warming

    NASA Astrophysics Data System (ADS)

    Sandeep, S.; Ajayamohan, R. S.

    2015-07-01

    The low level jetstream (LLJ) transports moisture from the surrounding Oceans to Indian land mass and hence an important component of the Indian summer monsoon (ISM). Widening of tropical belt and poleward shifts in mid-latitude jetstreams have been identified as major impacts of global warming on large-scale atmospheric dynamics. A general northward shift in ISM circulation has been suggested recently, based on the Coupled Model Inter-comparison Project (CMIP5) simulations. Here, we investigate the current and projected future changes in LLJ in observations as well as the coupled model (CMIP3/CMIP5) simulations. A poleward shift in the monsoon LLJ has been detected both in the observations and coupled model simulations. The poleward shift is also reflected in the future projections in a warming scenario, with the magnitude of shift depending on the degree of warming. Consistent with the LLJ shift, a drying (wet) trend in the southern (northern) part of the western coast of India is also observed in the last three decades. Further analysis reveals that enhanced land-sea contrast resulted in a strengthening of the cross-equatorial sea level pressure gradient over Indian Ocean, which in turn resulted in the northward shift of the zero absolute vorticity contour from its climatological position. The poleward shift in zero absolute vorticity contour is consistent with that of LLJ core (location of maximum low-level zonal winds). Possible uncertainties in the results are discussed in the context of known model biases and ensemble sample sizes. These results assume significance in the context of the concerns over ecologically fragile Western Ghats region in a warming scenario.

  16. Landform controls on low level moisture convergence and the diurnal cycle of warm season orographic rainfall in the Southern Appalachians

    NASA Astrophysics Data System (ADS)

    Wilson, Anna M.; Barros, Ana P.

    2015-12-01

    The Advanced Weather Research and Forecasting (WRF) model was used to simulate two warm season events representative of reverse orographic enhancement of warm season precipitation in the Southern Appalachians under weak (9-12 July, 2012) and strong (12-16 May, 2014) synoptic forcing conditions. Reverse orographic enhancement refers to significant enhancement of rainfall intensity (up to one order of magnitude) at low elevations in the inner mountain valleys, but not in the ridges. This is manifest in significant increases of radar reflectivity observations and associated integral quantities (rain rate) at low levels (within 500 m of the surface), as well as changes in the observed microphysical properties of rainfall (raindrop size distribution). Analysis of high-resolution (1.25 km × 1.25 km) WRF simulations shows that the model captures the march of observed rainfall, though not the timing in the case of strong synoptic forcing. For each event, the results show that the space-time variability of rainfall in the inner region is strongly coupled to the development and persistence of organized within-valley low-level moisture convergence that is a necessary precursor to valley fog and low level cloud formation. Microphysical interactions among precipitation from propagating storm systems, and local low-level clouds and fog promote coalescence efficiency through the seeder-feeder mechanism leading to significant enhancement of rainfall intensity near the ground as shown by Wilson and Barros (2014). The simulations support the hypothesis that ridge-valley precipitation gradients, and in particular the reverse orographic enhancement effects in inner mountain valleys, are linked to horizontal heterogeneity in the vertical structure of low level clouds and precipitation promoted through landform controls on moisture convergence.

  17. NWChem: A comprehensive and scalable open-source solution for large scale molecular simulations

    NASA Astrophysics Data System (ADS)

    Valiev, M.; Bylaska, E. J.; Govind, N.; Kowalski, K.; Straatsma, T. P.; Van Dam, H. J. J.; Wang, D.; Nieplocha, J.; Apra, E.; Windus, T. L.; de Jong, W. A.

    2010-09-01

    The latest release of NWChem delivers an open-source computational chemistry package with extensive capabilities for large scale simulations of chemical and biological systems. Utilizing a common computational framework, diverse theoretical descriptions can be used to provide the best solution for a given scientific problem. Scalable parallel implementations and modular software design enable efficient utilization of current computational architectures. This paper provides an overview of NWChem focusing primarily on the core theoretical modules provided by the code and their parallel performance. Program summaryProgram title: NWChem Catalogue identifier: AEGI_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGI_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Open Source Educational Community License No. of lines in distributed program, including test data, etc.: 11 709 543 No. of bytes in distributed program, including test data, etc.: 680 696 106 Distribution format: tar.gz Programming language: Fortran 77, C Computer: all Linux based workstations and parallel supercomputers, Windows and Apple machines Operating system: Linux, OS X, Windows Has the code been vectorised or parallelized?: Code is parallelized Classification: 2.1, 2.2, 3, 7.3, 7.7, 16.1, 16.2, 16.3, 16.10, 16.13 Nature of problem: Large-scale atomistic simulations of chemical and biological systems require efficient and reliable methods for ground and excited solutions of many-electron Hamiltonian, analysis of the potential energy surface, and dynamics. Solution method: Ground and excited solutions of many-electron Hamiltonian are obtained utilizing density-functional theory, many-body perturbation approach, and coupled cluster expansion. These solutions or a combination thereof with classical descriptions are then used to analyze potential energy surface and perform dynamical simulations. Additional comments: Full

  18. Modeling approaches for concrete barriers used in low-level waste disposal

    SciTech Connect

    Seitz, R.R.; Walton, J.C.

    1993-11-01

    A series of three NUREGs and several papers addressing different aspects of modeling performance of concrete barriers for low-level radioactive waste disposal have been prepared previously for the Concrete Barriers Research Project. This document integrates the information from the previous documents into a general summary of models and approaches that can be used in performance assessments of concrete barriers. Models for concrete degradation, flow, and transport through cracked concrete barriers are discussed. The models for flow and transport assume that cracks have occurred and thus should only be used for later times in simulations after fully penetrating cracks are formed. Most of the models have been implemented in a computer code. CEMENT, that was developed concurrently with this document. User documentation for CEMENT is provided separate from this report. To avoid duplication, the reader is referred to the three previous NUREGs for detailed discussions of each of the mathematical models. Some additional information that was not presented in the previous documents is also included. Sections discussing lessons learned from applications to actual performance assessments of low-level waste disposal facilities are provided. Sensitive design parameters are emphasized to identify critical areas of performance for concrete barriers, and potential problems in performance assessments are also identified and discussed.

  19. Modelling coastal low-level wind-jets: does horizontal resolution matter?

    NASA Astrophysics Data System (ADS)

    Ranjha, Raza; Tjernström, Michael; Svensson, Gunilla; Semedo, Alvaro

    2016-04-01

    Atmospheric flows in coastal regions are impacted by land-sea temperature contrasts, complex terrain, shape of the coastline, among many things. Along the west coast of central North America, winds in the boundary layer are mainly from north or northwest, roughly parallel to the coastline. Frequently, the coastal low-level wind field is characterized by a sharp wind maximum along the coast in the lowest kilometre. This feature, commonly referred to as a coastal low-level jet (CLLJ), has significant impact on the climatology of the coastal region and affects many human activities in the littoral zone. Hence, a good understanding and forecasting of CLLJs are vital. This study evaluates the issue of proper mesoscale numerical model resolution to describe the physics of a CLLJ, and its impact on the upper ocean. The COAMPS® model is used for a summer event to determine the realism of the model results compared to observations, from an area of supercritical flow adjustment between Pt. Sur and Pt. Conception, California. Simulations at different model horizontal resolutions, from 54 to 2 km are performed. While the model produces realistic results with increasing details at higher resolution, the results do not fully converge even at a resolution of only few kilometres and an objective analysis of model errors do not show an increased skill with increasing resolution. Based on all available information, a compromise resolution appears to be at least 6 km. New methods may have to be developed to evaluate models at very high resolution.

  20. Finite element solution of a Schelkunoff vector potential for frequency domain, EM field simulation

    NASA Astrophysics Data System (ADS)

    Kordy, M. A.; Wannamaker, P. E.; Cherkaev, E.

    2011-12-01

    A novel method for the 3-D diffusive electromagnetic (EM) forward problem is developed and tested. A Lorentz-gauge, Schelkunoff complex vector potential is used to represent the EM field in the frequency domain and the nodal finite element method is used for numerical simulation. The potential allows for three degrees of freedom per node, instead of four if Coulomb-gauge vector and scalar potentials are used. Unlike the finite-difference method, which minimizes error at discrete points, the finite element method minimizes error over the entire domain cell volumes and may easily adapt to complex topography. Existence and uniqueness of this continuous Schelkunoff potential is proven, boundary conditions are found and a governing equation satisfied by the potential in weak form is obtained. This approach for using a Schelkunoff potential in the finite element method differs from other trials found in the literature. If the standard weak form of the Helmholtz equation is used, the obtained solution is continuous and has continuous normal derivative across boundaries of regions with different physical properties; however, continuous Schelkunoff potential components do not have continuous normal derivative, divergence of the potential divided by (complex) conductivity and magnetic permeability is continuous instead. The weak form of governing equation used here imposes proper boundary conditions on the solution. Moreover, as the solution is continuous, nodal shape functions are used instead of edge elements. Magnetotelluric (MT) simulation results using the new method are compared with those from other MT forward codes

  1. Large eddy simulation of turbulence and solute transport in a forested headwater stream

    NASA Astrophysics Data System (ADS)

    Khosronejad, A.; Hansen, A. T.; Kozarek, J. L.; Guentzel, K.; Hondzo, M.; Guala, M.; Wilcock, P.; Finlay, J. C.; Sotiropoulos, F.

    2016-01-01

    The large eddy simulation (LES) module of the Virtual StreamLab (VSL3D) model is applied to simulate the flow and transport of a conservative tracer in a headwater stream in Minnesota, located in the south Twin Cities metropolitan area. The detailed geometry of the stream reach, which is ˜135 m long, ˜2.5 m wide, and ˜0.15 m deep, was surveyed and used as input to the computational model. The detailed geometry and location of large woody debris and bed roughness elements up to ˜0.1 m in size were also surveyed and incorporated in the numerical simulation using the Curvilinear Immersed Boundary approach employed in VSL3D. The resolution of the simulation, which employs up to a total of 25 million grid nodes to discretize the flow domain, is sufficiently fine to directly account for the effect of large woody debris and small cobbles (on the streambed) on the flow patterns and transport processes of conservative solutes. Two tracer injection conditions, a pulse and a plateau release, and two cross sections of measured velocity were used to validate the LES results. The computed results are shown to be in good agreement with the field measurements and tracer concentration time series. To our knowledge, the present study is the first attempt to simulate via high-resolution LES solute transport in a natural stream environment taking into account a range of roughness length scales spanning an order of magnitude: from small cobbles on the streambed (˜0.1 m in diameter) to large woody debris up to ˜3 m long.

  2. One-Step Direct Aeroacoustic Simulation Using Space-Time Conservation Element and Solution Element Method

    NASA Astrophysics Data System (ADS)

    Ho, C. Y.; Leung, R. C. K.; Zhou, K.; Lam, G. C. Y.; Jiang, Z.

    2011-09-01

    One-step direct aeroacoustic simulation (DAS) has received attention from aerospace and mechanical high-pressure fluid-moving system manufacturers for quite some time. They aim to simulate the unsteady flow and acoustic field in the duct simultaneously in order to investigate the aeroacoustic generation mechanisms. Because of the large length and energy scale disparities between the acoustic far field and the aerodynamic near field, highly accurate and high-resolution simulation scheme is required. This involves the use of high order compact finite difference and time advancement schemes in simulation. However, in this situation, large buffer zones are always needed to suppress the spurious numerical waves emanating from computational boundaries. This further increases the computational resources to yield accurate results. On the other hand, for such problem as supersonic jet noise, the numerical scheme should be able to resolve both strong shock waves and weak acoustic waves simultaneously. Usually numerical aeroa-coustic scheme that is good for low Mach number flow is not able to give satisfactory simulation results for shock wave. Therefore, the aeroacoustic research community has been looking for a more efficient one-step DAS scheme that has the comparable accuracy to the finite-difference approach with smaller buffer regions, yet is able to give accurate solutions from subsonic to supersonic flows. The conservation element and solution element (CE/SE) scheme is one of the possible schemes satisfying the above requirements. This paper aims to report the development of a CE/SE scheme for one-step DAS and illustrate its robustness and effectiveness with two selected benchmark problems.

  3. Characterization of Mesoscale Variability in WRF - a Coastal Low-Level Jet Case Study

    NASA Astrophysics Data System (ADS)

    Tay, K.; Lundquist, J. K.; Skote, M.; Koh, T. Y.

    2014-12-01

    Mesoscale weather models have increasingly been featured in wind resource assessment development. The incorporation of real meteorological conditions into such assessments allow a more realistic, physical determination of the wind loads that will be experienced within a wind farm site. Large-Eddy Simulation (LES) confers the advantage of representing finer scale turbulence, such as wake effects. However, nesting LES within real mesoscale simulations is still in the nascent stage of development. One of the difficulties lies in providing accurate mesoscale forcing boundaries for the LES domain. This study aims to characterize the mesoscale variability in WRF to lay the groundwork for future mesoscale-LES nested simulations. A low-level jet (LLJ) event that was observed during the CBLAST-Low 2001 campaign (07 Aug to 09 Aug) provides a robust case study to test the capabilities of and characterize the mesoscale variabilities in WRF. The dynamical interaction of a frontal passage with a stable boundary layer over a coastal region makes this an interesting and challenging case for real mesoscale simulation and future LES nested simulations. Sensitivities to vertical resolution, PBL schemes and initial forcing datasets were tested. This presentation will describe and explain the factors that influence the simulation of this frontal passage and the resulting LLJ. The initial forcing datasets have a major influence on spatial and temporal characteristics, as seen in Figure 1, introducing larger differences than the PBL schemes do. Furthermore, the mesoscale simulation also showed a strong dependence on the vertical resolution: increasing the vertical resolution within the atmospheric boundary layer resulted in a more accurate vertical profile for wind speed. Lastly, the simulations did show a dependency on the PBL scheme selected however, the variability between PBL schemes were not large, especially compared to the variability introduced by the boundary and initial

  4. On modelling of anisotropic viscoelasticity for soft tissue simulation: numerical solution and GPU execution.

    PubMed

    Taylor, Z A; Comas, O; Cheng, M; Passenger, J; Hawkes, D J; Atkinson, D; Ourselin, S

    2009-04-01

    Efficient and accurate techniques for simulation of soft tissue deformation are an increasingly valuable tool in many areas of medical image computing, such as biomechanically-driven image registration and interactive surgical simulation. For reasons of efficiency most analyses are based on simplified linear formulations, and previously almost all have ignored well established features of tissue mechanical response such as anisotropy and time-dependence. We address these latter issues by firstly presenting a generalised anisotropic viscoelastic constitutive framework for soft tissues, particular cases of which have previously been used to model a wide range of tissues. We then develop an efficient solution procedure for the accompanying viscoelastic hereditary integrals which allows use of such models in explicit dynamic finite element algorithms. We show that the procedure allows incorporation of both anisotropy and viscoelasticity for as little as 5.1% additional cost compared with the usual isotropic elastic models. Finally we describe the implementation of a new GPU-based finite element scheme for soft tissue simulation using the CUDA API. Even with the inclusion of more elaborate constitutive models as described the new implementation affords speed improvements compared with our recent graphics API-based implementation, and compared with CPU execution a speed up of 56.3 x is achieved. The validity of the viscoelastic solution procedure and performance of the GPU implementation are demonstrated with a series of numerical examples. PMID:19019721

  5. Charge Behaviors around Oxide Device/Pseudo-Physiological Solution Interface with Molecular Dynamic Simulations

    NASA Astrophysics Data System (ADS)

    Maekawa, Yuki; Shibuta, Yasushi; Sakata, Toshiya

    2013-12-01

    In this study, we investigated the charge behaviors of ions and water molecules at the oxide device/pseudo-physiological solution interface by use of molecular dynamics (MD) simulations because the detection principle of semiconductor-based biosensors is based on the detection of charge density changes at the oxide sensing surface in physiological environments. In particular, we designed an alpha-quartz (100) surface with some charges corresponding to pH=5.5 so that the ionic behaviors for 500 mM each of Na+ and Cl- around the interface were calculated under the surface condition with charges, considering a real system. As a result of the simulation, we defined the region of Debye length from the calculated potential distribution, in which some parameters such as diffusion coefficient and the vibration of water molecules around the interface differed from those of the bulk solution. The elucidation of the solid/liquid interfacial behaviors by the simulation technique should deepen our understanding of the detection principle of semiconductor-based biosensors and will give guidelines for the design of a bio-interface in the field of biosensing technology, because they cannot be demonstrated experimentally.

  6. 1989 Annual report on low-level radioactive waste management progress

    SciTech Connect

    Not Available

    1990-10-01

    This report summarizes the progress during 1989 of states and compacts in establishing new low-level radioactive waste disposal facilities. It also provides summary information on the volume of low-level waste received for disposal in 1989 by commercially operated low-level waste disposal facilities. This report is in response to Section 7(b) of Title I of Public Law 99--240, the Low-Level Radioactive Waste Policy Amendments Act of 1985. 2 figs., 5 tabs.

  7. Commercial low-level radioactive waste transportation liability and radiological risk

    SciTech Connect

    Quinn, G.J.; Brown, O.F. II; Garcia, R.S.

    1992-08-01

    This report was prepared for States, compact regions, and other interested parties to address two subjects related to transporting low-level radioactive waste to disposal facilities. One is the potential liabilities associated with low-level radioactive waste transportation from the perspective of States as hosts to low-level radioactive waste disposal facilities. The other is the radiological risks of low-level radioactive waste transportation for drivers, the public, and disposal facility workers.

  8. Plasma hearth process vitrification of DOE low-level mixed waste

    SciTech Connect

    Gillins, R.L.; Geimer, R.M.

    1995-11-01

    The Plasma Hearth Process (PHP) demonstration project is one of the key technology projects in the Department of Energy (DOE) Office of Technology Development Mixed Waste Focus Area. The PHP is recognized as one of the more promising solutions to DOE`s mixed waste treatment needs, with potential application in the treatment of a wide variety of DOE mixed wastes. The PHP is a high temperature vitrification process using a plasma arc torch in a stationary, refractory lined chamber that destroys organics and stabilizes the residuals in a nonleaching, vitrified waste form. This technology will be equally applicable to low-level mixed wastes generated by nuclear utilities. The final waste form will be volume reduced to the maximum extent practical, because all organics will have been destroyed and the inorganics will be in a high-density, low void-space form and little or no volume-increasing glass makers will have been added.

  9. Treatment options and flow sheets for ORNL low-level liquid waste supernate

    SciTech Connect

    Campbell, D.O.; Lee, D.D.

    1991-12-01

    Low-level liquid waste (LLLW) is currently contained in ten 50,000-gal storage and process tanks at Oak Ridge National Laboratory (ORNL) and as residual heels in an number of older tanks that are no longer in active use. Plans are being formulated to treat these wastes, along with similar LLLW that will be generated in the future, to yield decontaminated effluents that can be disposed of and stable solid waste forms that can be permanently stored. The primary purpose of this report is to summarize the performance of the most promising separations processes that are appropriate for treatment of the LLLW supernate solution to remove the two dominant radionuclides, {sup 137}Cs and {sup 90}Sr; to indicate how they can be integrated into an effective flowsheet; and to estimate the expected performance of such flowsheets in comparison to waste treatment requirements.

  10. Numerical Simulation Microstructure Morphology Evolution and Solute Microsegregation of Al-Si-Cu Ternary Alloys during Solidification Process

    NASA Astrophysics Data System (ADS)

    Xie, Shuisheng; Huang, Guojie; Cheng, Lei; Fu, Yao; Li, Qiang

    2011-06-01

    A 2D microstructure and solute microsegregation model of Al-Si-Cu ternary alloys is presented by using cellular automaton(CA) method. In CA model, an improved algorithm was presented that abandoned the assumption of solid/liquid interface position and velocity so as to calculate the solid fraction in the solid/liquid interface unit. Then, using CA model, a dendrite of Al-Si-Cu ternary alloys is simulated. Finally, solidification microstructure and solute microsegregation are simulated, and the simulated results can reflect the microstructure and different solute microsegregation during solidification process.

  11. Formation of nanoclusters under radiation pressure in solution: A Brownian dynamics simulation study

    NASA Astrophysics Data System (ADS)

    Jose, Prasanth P.; Bagchi, Biman

    2002-02-01

    When radiation is scattered by a medium, a part of its momentum is transferred to the target particles. This is purely a mechanical force which comes into effect when radiation is not coherently interacting. This force is known in literature as radiation pressure. Recent experimental studies have demonstrated the feasibility of using radiation pressure of a laser beam as a tool for cluster formation in solution. In this paper we describe the Brownian dynamics simulation of solute molecules under the perturbation induced by laser radiation. Here the force field generated by a laser beam in the fundamental mode is modeled as that of a two-dimensional harmonic oscillator. The radial distribution function of the perturbed system gives indication of high inhomogeneities in the solute distribution. An explicit analysis of the nature of these clusters is carried out by calculating the density-density correlation functions in the plane perpendicular to beam direction g(rxy); and along the direction of beam g(z), they give an average picture of shell structure formation in the different directions. The relaxation time of the first shell structure calculated from the van Hove correlation function is found to be relatively large in the perturbed solution. This is the signature of formation of stable nanoclusters in the presence of the radiation field. Our study on the dynamics of solute molecules during the cluster formation and dissolution gives the duration of collective relaxation, far away from the equilibrium to an equilibrium distribution. This relaxation time is found to be large for a perturbed solution.

  12. Life-Cycle Cost Study for a Low-Level Radioactive Waste Disposal Facility in Texas

    SciTech Connect

    B. C. Rogers; P. L. Walter; R. D. Baird

    1999-08-01

    This report documents the life-cycle cost estimates for a proposed low-level radioactive waste disposal facility near Sierra Blanca, Texas. The work was requested by the Texas Low-Level Radioactive Waste Disposal Authority and performed by the National Low-Level Waste Management Program with the assistance of Rogers and Associates Engineering Corporation.

  13. Low level laser intensity improves propulsive appliance effects on condylar cartilage

    NASA Astrophysics Data System (ADS)

    Figueiredo, Augusto C. R.; dos Santos, Fernanda C. A.; Capeletti, Lucas R.; Galdino, Marcos V. B.; Araújo, Renan V.; Marques, Mara R.

    2012-01-01

    Mandibular propulsive appliance (MPA) stimulates cell proliferation and gene expression on mandible condylar cartilage (Marques et al., 2008). However, its association with low level laser therapy (LLLT) is unknown. This study evaluated the effects of LLLT associated to MPA on mandibular condyle. Twenty Wistar rats were divided into four groups. Group I received any treatment. Group II was bilaterally irradiated on temporomandibular joint with 10 J/cm2 low level laser (780nm, 40mW and 10s) on alternate days. Group III used the propulsive appliance for ten hours daily and Group IV used the appliance daily and was irradiated on alternate days. After 15 days the animals were killed by lethal doses of anesthetics. The condyles were fixed in Methacarn solution and decalcified in 4.13% EDTA solution for 30 days. Seriate saggital 5 μm-thick sections were stained by the hematoxilin-eosin method. Morphological and morphometric analyses were performed to measure the length and the height of the mandibular condyle, the thickness of the condilar cartilage and the bone mass. Results were expressed as mean +/- standard deviation (one-way ANOVA, Tukey's post-test.) The appliance increased all measures compared to the control group, except bone mass. Alone, LLLT had no effects on all measures, however, the association of the appliance with the LLLT increased condylar cartilage and bone mass significantly compared to the others groups. These results suggest that LLLT improves the effects of mandibular propulsive appliance in the condylar cartilage growth and formation of bone mass.

  14. Mineral Dissolution and Secondary Precipitation on Quartz Sand in Simulated Hanford Tank Solutions Affecting Subsurface Porosity

    SciTech Connect

    Wang, Guohui; Um, Wooyong

    2012-11-23

    Highly alkaline nuclear waste solutions have been released from underground nuclear waste storage tanks and pipelines into the vadose zone at the U.S. Department of Energy’s Hanford Site in Washington, causing mineral dissolution and re-precipitation upon contact with subsurface sediments. High pH caustic NaNO3 solutions with and without dissolved Al were reacted with quartz sand through flow-through columns stepwise at 45, 51, and 89°C to simulate possible reactions between leaked nuclear waste solution and primary subsurface mineral. Upon reaction, Si was released from the dissolution of quartz sand, and nitrate-cancrinite [Na8Si6Al6O24(NO3)2] precipitated on the quartz surface as a secondary mineral phase. Both steady-state dissolution and precipitation kinetics were quantified, and quartz dissolution apparent activation energy was determined. Mineral alteration through dissolution and precipitation processes results in pore volume and structure changes in the subsurface porous media. In this study, the column porosity increased up to 40.3% in the pure dissolution column when no dissolved Al was present in the leachate, whereas up to a 26.5% porosity decrease was found in columns where both dissolution and precipitation were observed because of the presence of Al in the input solution. The porosity change was also confirmed by calculation using the dissolution and precipitation rates and mineral volume changes.

  15. Radiolysis of Bicarbonate and Carbonate Aqueous Solutions: Product Analysis and Simulation of Radiolytic Processes

    SciTech Connect

    Cai Zhongli; Li Xifeng; Katsumura, Yosuke; Urabe, Osamu

    2001-11-15

    An understanding of the radiation-induced effects in groundwater is essential to evaluate the safe geological disposal of spent fuel. In groundwater, the bicarbonate ion is the predominant and common anion; this work investigated radiation-induced chemical reactions of (bi)carbonate aqueous solutions with steady-state irradiation and pulse radiolysis methods. Aqueous solutions of sodium (bi)carbonate as high as 50 mmol.dm{sup -3} were used. The formation of formate, oxalate, and H{sub 2}O{sub 2} were measured under different conditions. A complete set of reaction steps and reliable kinetic data for the radiolysis of (bi)carbonate aqueous solutions at ionic strength close to the groundwater were proposed. Kinetic calculations were completed based on the proposed reaction steps and the kinetic data obtained in the present work. The results from the calculation are in good agreement with the experimental results. With these proposed reaction steps and kinetic data, computer simulation can be performed to predict the yield of radiolytic products of (bi)carbonate aqueous solutions as a function of irradiation time and used to evaluate the safety of geological disposal options of spent fuel.

  16. 1D simulation of polymer flooding including the viscoelastic effect of polymer solution

    SciTech Connect

    Masuda, Y.; Tang, K.C.; Miyazawa, M.; Tanaka, S. )

    1992-05-01

    This paper reports that simple simulation models are constructed to predict the performance of 1D polymer flooding. In the models, two phases of oil and polymer solution were assumed to be immiscible with each other. Because the displacing fluid was non-Newtonian, the Buckley-Leverett equation could be modified and a new approach developed to calculate fractional-flow curves. The rheological behavior of polymer solution was modeled with an Ellis type model and a viscoelastic model. To verify the models, two 1D flooding experiments were carried out on 2.8-cm-diameter, 47-cm-long, unconsolidated cores packed with glass beads (70/100 mesh). Porosities of the cores are about 37% and permeabilities are around 26{mu}m{sup 2}. Two white mineral oils of viscosities 25 and 60 mPa {center dot} s and a 200-ppm polyacrylamide solution were used. In each experiment, polymer flooding was done after waterflooding. Initial water saturation was controlled to be almost the same at the start of each flood. The calculated polymer-flooding performances were compared with experimental data. On the other hand, the viscoelastic model predicted fractional-flow curves, oil recovery performances, and breakthrough times of the experiments very well. The viscoelastic effect of polymer solution is thought to play an important role in the improvement of oil recovery.

  17. ABSINTH: A new continuum solvation model for simulations of polypeptides in aqueous solutions

    PubMed Central

    Vitalis, Andreas; Pappu, Rohit V.

    2009-01-01

    A new implicit solvation model for use in Monte Carlo simulations of polypeptides is introduced. The model is termed ABSINTH for self-Assembly of Biomolecules Studied by an Implicit, Novel, and Tunable Hamiltonian. It is designed primarily for simulating conformational equilibria and oligomerization reactions of intrinsically disordered proteins in aqueous solutions. The paradigm for ABSINTH is conceptually similar to the EEF1 model of Lazaridis and Karplus (Proteins: Struct. Func. Genet., 1999, 35: 133-152). In ABSINTH, the transfer of a polypeptide solute from the gas phase into a continuum solvent is the sum of a direct mean field interaction (DMFI), and a term to model the screening of polar interactions. Polypeptide solutes are decomposed into a set of distinct solvation groups. The DMFI is a sum of contributions from each of the solvation groups, which are analogs of model compounds. Continuum-mediated screening of electrostatic interactions is achieved using a framework similar to the one used for the DMFI. Promising results are shown for a set of test cases. These include the calculation of NMR coupling constants for short peptides, the assessment of the thermal stability of two small proteins, reversible folding of both an alpha-helix and a beta-hairpin forming peptide, and the polymeric properties of intrinsically disordered polyglutamine peptides of varying lengths. The tests reveal that the computational expense for simulations with the ABSINTH implicit solvation model increase by a factor that is in the range of 2.5-5.0 with respect to gas-phase calculations. PMID:18506808

  18. SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport

    USGS Publications Warehouse

    Langevin, Christian D.; Thorne, Daniel T., Jr.; Dausman, Alyssa M.; Sukop, Michael C.; Guo, Weixing

    2008-01-01

    The SEAWAT program is a coupled version of MODFLOW and MT3DMS designed to simulate three-dimensional, variable-density, saturated ground-water flow. Flexible equations were added to the program to allow fluid density to be calculated as a function of one or more MT3DMS species. Fluid density may also be calculated as a function of fluid pressure. The effect of fluid viscosity variations on ground-water flow was included as an option. Fluid viscosity can be calculated as a function of one or more MT3DMS species, and the program includes additional functions for representing the dependence on temperature. Although MT3DMS and SEAWAT are not explicitly designed to simulate heat transport, temperature can be simulated as one of the species by entering appropriate transport coefficients. For example, the process of heat conduction is mathematically analogous to Fickian diffusion. Heat conduction can be represented in SEAWAT by assigning a thermal diffusivity for the temperature species (instead of a molecular diffusion coefficient for a solute species). Heat exchange with the solid matrix can be treated in a similar manner by using the mathematically equivalent process of solute sorption. By combining flexible equations for fluid density and viscosity with multi-species transport, SEAWAT Version 4 represents variable-density ground-water flow coupled with multi-species solute and heat transport. SEAWAT Version 4 is based on MODFLOW-2000 and MT3DMS and retains all of the functionality of SEAWAT-2000. SEAWAT Version 4 also supports new simulation options for coupling flow and transport, and for representing constant-head boundaries. In previous versions of SEAWAT, the flow equation was solved for every transport timestep, regardless of whether or not there was a large change in fluid density. A new option was implemented in SEAWAT Version 4 that allows users to control how often the flow field is updated. New options were also implemented for representing constant

  19. Simultaneous potential and circuit solution for 1D bounded plasma particle simulation codes

    SciTech Connect

    Verboncoeur, J.P.; Vahedi, V.; Birdsall, C.K. ); Alves, M.V. , S.J. dos Campos )

    1993-02-01

    A general second-order accurate method for solving the combined potential and circuit equations in a one-dimensional electrostatic bounded plasma PIC simulation is presented. The boundary conditions include surface charge on the electrodes, which are connected to a series RLC circuit with driving terms V(t) or l(t). The solution is obtained for planar, cylindrical, and spherical electrodes. The result is a tridiagonal matrix which is readily solved using well-known methods. The method is implemented in the codes PDPL (plasma device planar 1 D), PDC1 (cylindrical), and PDS1 (spherical).

  20. Simultaneous potential and circuit solution for bounded plasma particle simulation codes

    SciTech Connect

    Verboncoeur, J.P.; Alves, M.V.; Vahedi, V.

    1990-08-07

    A second-order accurate method for solving the combined potential and circuit equations in an electrostatic bounded plasma PIC simulation is presented. The boundary conditions include surface charge on the electrodes, which are connected to a series RLC circuit with driving terms V(t) and I(t). The solution is obtained for planar, cylindrical, and spherical electrodes. The result is a tridiagonal matrix which is readily solved using well-known methods. The method is implemented in the codes PDP1 (Plasma Device Planar 1D), PDC1 (Cylindrical), and PDS1 (Spherical). 11 refs., 10 figs.

  1. Self-Assembly of Pluronic Block Copolymers in Solutions: Simulation and Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Zhe; Hong, Kunlun; Do, Changwoo; Biology and Soft-Matter Division, Oak Ridge National Laboratory Team; Chemical Science Division, Oak Ridge National Laboratory Team

    2014-03-01

    Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers in water solution display various phase behaviors such as micellar, lamellar, and hexagonal phases and have been of great interest to researchers for their wide range of applications including templates of various nanostructures in solar cell and transportation of nanoparticles in drug delivery. In this study, we combined density functional theory-based mesoscale simulation and small-angle neutron scattering (SANS) experiments to investigate equilibrium structures of L62/water systems at different concentrations. Various simulation parameters found in the literature have been revisited with the experimental findings. Scattering experiments were found to be an excellent. This research is supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Energy Division.

  2. Behavior of aqueous solutions in hydrophobic confinement studied using molecular simulations

    NASA Astrophysics Data System (ADS)

    Sharma, Sumit

    Biological processes, such as formation of cell membranes, vesicles and folding of protein molecules, entail formation of a predominantly hydrophobic interior devoid of water. These processes occur in crowded aqueous environments comprising of amino acids, carbohydrates, ionic species, protein molecules, etc. Kinetics of these processes involve drying of hydrophobic pockets. Previous studies reveal that the kinetics of evaporation of water in hydrophobic confinement significantly slow down as the confinement gap increases. Presumably, the constituents of aqueous environment in biological systems modulate the kinetics of evaporation of confined water. In this work, we employ forward flux sampling in molecular dynamics simulations to study the role of solutes at different concentrations in modulating the kinetics and mechanism of evaporation of water under hydrophobic confinement. The results of these simulations will be useful for understanding optimum conditions for protein folding and other biological self-assembly processes.

  3. Low-Level Primary Blast Causes Acute Ocular Trauma in Rabbits.

    PubMed

    Jones, Kirstin; Choi, Jae-Hyek; Sponsel, William E; Gray, Walt; Groth, Sylvia L; Glickman, Randolph D; Lund, Brian J; Reilly, Matthew A

    2016-07-01

    The objective of this study was to determine whether clinically significant ocular trauma can be induced by a survivable isolated primary blast using a live animal model. Both eyes of 18 Dutch Belted rabbits were exposed to various survivable low-level blast overpressures in a large-scale shock tube simulating a primary blast similar to an improvised explosive device. Eyes of the blast-exposed rabbits (as well as five control rabbits) were thoroughly examined before and after blast to detect changes. Clinically significant changes in corneal thickness arose immediately after blast and were sustained through 48 h, suggesting possible disruption of endothelial function. Retinal thickness (RT) increased with increasing specific impulse immediately after exposure. Intraocular pressure (IOP) was inversely correlated with the specific impulse of the blast wave. These findings clearly indicate that survivable primary blast causes ocular injuries with likely visual functional sequelae of clinical and military relevance. PMID:26393900

  4. GTS Duratek, phase I Hanford low-level waste melter tests: Final report

    SciTech Connect

    Eaton, W.C.

    1995-10-26

    A multiphase program was initiated in 1994 to test commercially available melter technologies for the vitrification of the low-level waste (LLW) stream from defense waste stored in underground tanks at the Hanford Site in southeastern Washington State. Phase 1 of the melter demonstration tests using simulated LLW was completed during fiscal year 1995. This document is the final report on testing performed by GTS Duratek Inc. in Columbia, Maryland. GTS Duratek (one of the seven vendors selected) was chosen to demonstrate Joule heated melter technology under WHC subcontract number MMI-SVV-384215. The report contains description of the tests, observations, test data and some analysis of the data as it pertains to application of this technology for LLW vitrification. The document also contains summaries of the melter offgas reports issued as separate documents for the 100 kg melter (WHC-SD-WM-VI-028) and for the 1000 kg melter (WHC-SD-WM-VI-029).

  5. BNFL Lysimeter programme to investigate the leaching of radionuclides from low-level radioactive waste

    SciTech Connect

    Clayton, K.; Clegg, R.; Holmes, R.G.G.; Newton, G.W.A.

    1993-12-31

    British Nuclear Fuels plc has initiated an experimental programme to measure the leaching behavior of radionuclides from various low level radioactive waste (LLW) materials using Lysimeters. The programme commenced in 1986 and to date 10 lysimeters have been commissioned. These have concentrated on simulating shallow trench conditions but a further programme is now planned to study concrete vault environments. The aim of the study is to provide information on leaching processes as part of the ongoing Drigg Near Field Programme, and also to yield input data for radiological assessment purposes. Towards this end, data have been gained from the lysimeters on basic chemistry, gas generation and radionuclide Release Coefficients. This paper concentrates on one of the lysimeters which has recently been decommissioned and for which interim analytical data are available. Some general comments are given on BNFL`s experience using lysimeters and their applicability as a rapid and effective technique for studying near field degradation processes.

  6. Validating Solution Ensembles from Molecular Dynamics Simulation by Wide-Angle X-ray Scattering Data

    PubMed Central

    Chen, Po-chia; Hub, Jochen S.

    2014-01-01

    Wide-angle x-ray scattering (WAXS) experiments of biomolecules in solution have become increasingly popular because of technical advances in light sources and detectors. However, the structural interpretation of WAXS profiles is problematic, partly because accurate calculations of WAXS profiles from structural models have remained challenging. In this work, we present the calculation of WAXS profiles from explicit-solvent molecular dynamics (MD) simulations of five different proteins. Using only a single fitting parameter that accounts for experimental uncertainties because of the buffer subtraction and dark currents, we find excellent agreement to experimental profiles both at small and wide angles. Because explicit solvation eliminates free parameters associated with the solvation layer or the excluded solvent, which would require fitting to experimental data, we minimize the risk of overfitting. We further find that the influence from water models and protein force fields on calculated profiles are insignificant up to q≈15nm−1. Using a series of simulations that allow increasing flexibility of the proteins, we show that incorporating thermal fluctuations into the calculations significantly improves agreement with experimental data, demonstrating the importance of protein dynamics in the interpretation of WAXS profiles. In addition, free MD simulations up to one microsecond suggest that the calculated profiles are highly sensitive with respect to minor conformational rearrangements of proteins, such as an increased flexibility of a loop or an increase of the radius of gyration by < 1%. The present study suggests that quantitative comparison between MD simulations and experimental WAXS profiles emerges as an accurate tool to validate solution ensembles of biomolecules. PMID:25028885

  7. A microbial fuel cell driven capacitive deionization technology for removal of low level dissolved ions.

    PubMed

    Feng, Cuijie; Hou, Chia-Hung; Chen, Shaohua; Yu, Chang-Ping

    2013-04-01

    The microbial fuel cell (MFC) is an emerging technology, which uses exoelectrogenic microorganisms to oxidize organic matter in the wastewater to produce electricity. However, the low energy output limits its application in practice. Capacitive deionization (CDI), an electrochemically controlled method for deionization by the adsorption of ions in the electrical double layer region at an electrode-solution interface, requires a low external power supply. Therefore, in this study, we investigated the MFC driven CDI (MFC-CDI) technology to integrate deionization with wastewater treatment and electricity production. Taking advantage of the low potential requirement of CDI, voltage generated from a continuous flow MFC could be used to drive the CDI to achieve removal of the electrolyte to a stable status. The results indicated that among the three connection types of MFCs including single-, series-, and parallel-configuration, the parallel connection of two MFCs resulted in the highest potential (0.63V) applied to CDI and the conductivity removal of NaCl solution was more than 60%. The electrosorption capacities under different electrolyte concentrations of 50, 100 and 150 mg L(-1) were 150, 346 and 295 μg g(-1), respectively. These results suggest that the new MFC-CDI technology, which utilizes energy recovery from the wastewater, has great potential to be an energy saving technology to remove low level dissolved ions from aqueous solutions for the water and wastewater treatment processes. PMID:23375820

  8. Practical solutions for reducing container ships' waiting times at ports using simulation model

    NASA Astrophysics Data System (ADS)

    Sheikholeslami, Abdorreza; Ilati, Gholamreza; Yeganeh, Yones Eftekhari

    2013-12-01

    The main challenge for container ports is the planning required for berthing container ships while docked in port. Growth of containerization is creating problems for ports and container terminals as they reach their capacity limits of various resources which increasingly leads to traffic and port congestion. Good planning and management of container terminal operations reduces waiting time for liner ships. Reducing the waiting time improves the terminal's productivity and decreases the port difficulties. Two important keys to reducing waiting time with berth allocation are determining suitable access channel depths and increasing the number of berths which in this paper are studied and analyzed as practical solutions. Simulation based analysis is the only way to understand how various resources interact with each other and how they are affected in the berthing time of ships. We used the Enterprise Dynamics software to produce simulation models due to the complexity and nature of the problems. We further present case study for berth allocation simulation of the biggest container terminal in Iran and the optimum access channel depth and the number of berths are obtained from simulation results. The results show a significant reduction in the waiting time for container ships and can be useful for major functions in operations and development of container ship terminals.

  9. Simulation and experimental study of maskless convex corner compensation in TMAH water solution

    NASA Astrophysics Data System (ADS)

    Smiljanić, Milče M.; Radjenović, Branislav; Radmilović-Radjenović, Marija; Lazić, Žarko; Jović, Vesna

    2014-11-01

    Maskless etching with convex corner compensation in the form of a <1 0 0> oriented beam is investigated using both experiments and simulations. The maskless convex corner compensation technique is defined as a combination of masked and maskless anisotropic etching of {1 0 0} silicon in 25 wt% TMAH water solution at a temperature of 80 °C. This technique enables fabrication of three-level micromachined silicon structures with compensated convex corners at the bottom of the etched structure. All crystallographic planes that appear during etching are determined and their etch rates are used to calculate the etch rate value in an arbitrary crystallographic direction necessary for simulation by an interpolation procedure. A 3D simulation of the profile evolution of the etched structure during masked and maskless etching of silicon based on the level set method is presented. All crystallographic planes of the etched silicon structures determined in the experiment are recognized in the corresponding simulated etching profiles obtained by the level set method.

  10. Development of Satellite-based Climatology of Low-level Cloud and Fog in Mountain Terrain

    NASA Astrophysics Data System (ADS)

    Duan, Y.; Barros, A. P.

    2014-12-01

    The presence of orographic clouds and fog has major environmental and economic implications that the potential shift in the space-time distribution can effectively redistribute freshwater resources and threaten the sustainability of the ecology, geomorphology and hydrology of mountainous regions and adjacent basins. This includes the Southern Appalachian Mountains, which rely closely on the moisture input from fog, cap clouds and light rainfall, as well as cloud forests in the Andes with frequent occurrence of dense fog. However, the applicability of fog forecasting models becomes limited in regions of complex terrain. The motivation of this project is to develop a satellite-based hydroclimatology and physical parameterization of orographic low-level clouds and fog regimes in the Southern Appalachians using a general methodology that can be applied to mountainous regions elsewhere. An algorithm for the detection and extraction of stratus clouds and fog was developed using changes in vertical gradients of CPR reflectivity and liquid water products from almost 5-years of CLOUDSAT and SRTM terrain data. This population of low-level clouds and fog will be analyzed with GOES infrared and visible imagery, MODIS and CALIPSO products, and with airport cloud height and visibility records to expand the spatial coverage beyond narrow satellite sensor swaths. The climatology will be further developed through integration with results from WRF simulations for selected periods since the bulk of the PMM network has been in place (2008-present) to aid in defining meteorological and time-of-day constraints in the interpretation of simulated satellite radar reflectivity profiles. The overarching goal is to infer a representation of the diurnal cycle, seasonal and inter-annual variations of the vertical distribution of LWC and hydrometeors in orographic clouds and fog that vary spatially with landform toward developing a more general parameterization of seeder-feeder interactions in

  11. Low Level and Transuranic Waste Segregation and Low Level Waste Characterization at the 200 Area of the Hanford Site - 12424

    SciTech Connect

    Donohoue, Tom; Martin, E. Ray; Mason, John A.; Blackford, Ty; Estes, Michael; Jasen, William; Cahill, Michael

    2012-07-01

    This paper describes the waste measurement and waste characterization activities carried out by ANTECH Corporation (ANTECH) and CH2M Hill Plateau Remediation Company (CHPRC) at the 200 Area of the Hanford Site under Contracts No. 22394 and No. 40245 for the US Department of Energy (DOE). These include Low Level Waste (LLW) and Transuranic (TRU) Waste segregation and LLW characterization for both 55-gallon (200-litre) drums with gross weight up to 454 kg and 85-gallon over-pack drums. In order to achieve efficient and effective waste drum segregation and assay, ANTECH deployed an automated Gamma Mobile Assay Laboratory (G-MAL) at the trench face in both 200 Area West and East. The unit consists of a modified 40 foot ISO shipping container with an automatic flow through roller conveyor system with internal drum weigh scale, four measurement and drum rotation positions, and four high efficiency high purity Germanium (HPGe) detectors with both detector and shadow shields. The unit performs multiple far-field measurements and is able to segregate drums at levels well below 100 nCi/g. The system is sufficiently sensitive that drums, which are classified as LLW, are characterized at measurement levels that meet the Environmental Restoration Disposal Facility (ERDF) Waste Acceptance Criteria (WAC). With measurement times of between 20 and 30 minutes the unit can classify and characterize over 40 drums in an 8-hour shift. The system is well characterized with documented calibrations, lower limits of detection (LLD) and total measurement uncertainty. The calibrations are confirmed and verified using nationally traceable standards in keeping with the CHPRC measurement requirements. The performance of the system has been confirmed and validated throughout the measurement process by independent CHPRC personnel using traceable standards. All of the measurement and maintenance work has been conducted during the period under a Quality Assurance Plan (QAP) compliant with the

  12. Biodegradation testing of solidified low-level waste streams

    SciTech Connect

    Piciulo, P.L.; Shea, C.E.; Barletta, R.E.

    1985-05-01

    The NRC Technical Position on Waste Form (TP) specifies that waste should be resistant to biodegradation. The methods recommended in the TP for testing resistance to fungi, ASTM G21, and for testing resistance to bacteria, ASTM G22, were carried out on several types of solidified simulated wastes, and the effect of microbial activity on the mechanical strength of the materials tested was examined. The tests are believed to be sufficient for distinguishing between materials that are susceptible to biodegradation and those that are not. It is concluded that failure of these tests should not be regarded of itself as an indication that the waste form will biodegrade to an extent that the form does not meet the stability requirements of 10 CFR Part 61. In the case of failure of ASTM G21 or ASTM G22 or both, it is recommended that additional data be supplied by the waste generator to demonstrate the resistance of the waste form to microbial degradation. To produce a data base on the applicability of the biodegradation tests, the following simulated laboratory-scale waste forms were prepared and tested: boric acid and sodium sulfate evaporator bottoms, mixed-bed bead resins and powdered resins each solidified in asphalt, cement, and vinyl ester-styrene. Cement solidified wastes supported neither fungal nor bacterial growth. Of the asphalt solidified wastes, only the forms of boric acid evaporator bottoms did not support fungal growth. Bacteria grew on all of the asphalt solidified wastes. Cleaning the surface of these waste forms did not affect bacterial growth and had a limited effect on the fungal growth. Only vinyl esterstyrene solidified sodium sulfate evaporator bottoms showed viable fungi cultures, but surface cleaning with solvents eliminated fungal growth in subsequent testing. Some forms of all the waste streams solidified in vinyl ester-styrene showed viable bacteria cultures. 13 refs., 12 tabs.

  13. Adaptive resolution simulation of an atomistic DNA molecule in MARTINI salt solution

    NASA Astrophysics Data System (ADS)

    Zavadlav, J.; Podgornik, R.; Melo, M. N.; Marrink, S. J.; Praprotnik, M.

    2016-07-01

    We present a dual-resolution model of a deoxyribonucleic acid (DNA) molecule in a bathing solution, where we concurrently couple atomistic bundled water and ions with the coarse-grained MARTINI model of the solvent. We use our fine-grained salt solution model as a solvent in the inner shell surrounding the DNA molecule, whereas the solvent in the outer shell is modeled by the coarse-grained model. The solvent entities can exchange between the two domains and adapt their resolution accordingly. We critically asses the performance of our multiscale model in adaptive resolution simulations of an infinitely long DNA molecule, focusing on the structural characteristics of the solvent around DNA. Our analysis shows that the adaptive resolution scheme does not produce any noticeable artifacts in comparison to a reference system simulated in full detail. The effect of using a bundled-SPC model, required for multiscaling, compared to the standard free SPC model is also evaluated. Our multiscale approach opens the way for large scale applications of DNA and other biomolecules which require a large solvent reservoir to avoid boundary effects.

  14. Coarse-grained simulations of poly(propylene imine) dendrimers in solution.

    PubMed

    Smeijers, A F; Markvoort, A J; Pieterse, K; Hilbers, P A J

    2016-02-21

    The behavior of poly(propylene imine) (PPI) dendrimers in concentrated solutions has been investigated using molecular dynamics simulations containing up to a thousand PPI dendrimers of generation 4 or 5 in explicit water. To deal with large system sizes and time scales required to study the solutions over a wide range of dendrimer concentrations, a previously published coarse-grained model was applied. Simulation results on the radius of gyration, structure factor, intermolecular spacing, dendrimer interpenetration, and water penetration are compared with available experimental data, providing a clear concentration dependent molecular picture of PPI dendrimers. It is shown that with increasing concentration the dendrimer volume diminishes accompanied by a reduction of internalized water, ultimately resulting in solvent filled cavities between stacked dendrimers. Concurrently dendrimer interpenetration increases only slightly, leaving each dendrimer a separate entity also at high concentrations. Moreover, we compare apparent structure factors, as calculated in experimental studies relying on the decoupling approximation and the constant atomic form factor assumption, with directly computed structure factors. We demonstrate that these already diverge at rather low concentrations, not because of small changes in form factor, but rather because the decoupling approximation fails as monomer positions of separate dendrimers become correlated at concentrations well below the overlap concentration. PMID:26896998

  15. Relaxation dynamics of lysozyme in solution under pressure: Combining molecular dynamics simulations and quasielastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Calandrini, V.; Hamon, V.; Hinsen, K.; Calligari, P.; Bellissent-Funel, M.-C.; Kneller, G. R.

    2008-04-01

    This paper presents a study of the influence of non-denaturing hydrostatic pressure on the relaxation dynamics of lysozyme in solution, which combines molecular dynamics simulations and quasielastic neutron scattering experiments. We compare results obtained at ambient pressure and at 3 kbar. Experiments have been performed at pD 4.6 and at a protein concentration of 60 mg/ml. For both pressures we checked the monodispersity of the protein solution by small angle neutron scattering. To interpret the simulation results and the experimental data, we adopt the fractional Ornstein-Uhlenbeck process as a model for the internal relaxation dynamics of the protein. On the experimental side, global protein motions are accounted for by the model of free translational diffusion, neglecting the much slower rotational diffusion. We find that the protein dynamics in the observed time window from about 1 to 100 ps is slowed down under pressure, while its fractal characteristics is preserved, and that the amplitudes of the motions are reduced by about 20%. The slowing down of the relaxation is reduced with increasing q-values, where more localized motions are seen.

  16. Matrix-free Brownian dynamics simulation technique for semidilute polymeric solutions

    NASA Astrophysics Data System (ADS)

    Saadat, Amir; Khomami, Bamin

    2015-09-01

    Evaluating the concentration dependence of static and dynamic properties of macromolecules in semidilute polymer solutions requires accurate calculation of long-range hydrodynamic interactions (HI) and short range excluded volume (EV) forces. In conventional Brownian dynamics simulations (BDS), computation of HI necessitates construction of a dense diffusion tensor commonly performed via Ewald summation. Krylov subspace techniques allow efficient decomposition of this tensor [computational cost scales as O (N2) , where N is the total number of beads in bead-spring representation of macromolecules in a simulation box] and computation of Brownian displacements in the box. In this paper, a matrix-free approach for calculation of HI is implemented which leads to O (N logN ) scaling of computational expense. The fidelity of the algorithm is demonstrated by evaluating the asymptotic value of center-of-mass diffusivity of polymer molecules at very low concentrations and their radius of gyration scaling as a function of number of beads for dilute and semidilute solutions (with concentrations up to 5 times the overlap concentration). In turn, a favorable comparison between our results and the blob theory is shown.

  17. Ultraviolet Spectroscopy of Protein Backbone Transitions in Aqueous Solution: combined QM and MM Simulations

    PubMed Central

    Jiang, Jun; Abramavicius, Darius; Bulheller, Benjamin M.; Hirst, Jonathan D.; Mukamel, Shaul

    2010-01-01

    A generalized approach combining Quantum Mechanics (QM) and Molecular Mechanics (MM) calculations is developed to simulate the n → π* and π → π* backbone transitions of proteins in aqueous solution. These transitions, which occur in the ultraviolet (UV) at 180–220 nm, provide a sensitive probe for secondary structures. The excitation Hamiltonian is constructed using high level electronic structure calculations of N-methylacetamide (NMA). Its electrostatic fluctuations are modeled using a new algorithm, EHEF, which combines a molecular dynamics (MD) trajectory obtained with a molecular mechanics forcefield, and electronic structures of sampled MD snapshots calculated by QM. The lineshapes and excitation split-tings induced by the electrostatic environment in the experimental UV linear absorption (LA) and circular dichroism (CD) spectra of several proteins in aqueous solution are reproduced by our calculations. The distinct CD features of α-helix and β-sheet protein structures are observed in the simulations and can be assigned to different backbone geometries. The fine structure of the UV spectra is accurately characterized and enables us to identify signatures of secondary structures. PMID:20503991

  18. Microbial transformation of low-level radioactive waste

    SciTech Connect

    Francis, A.J.

    1980-06-01

    Microorganisms play a significant role in the transformation of the radioactive waste and waste forms disposed of at shallow-land burial sites. Microbial degradation products of organic wastes may influence the transport of buried radionuclides by leaching, solubilization, and formation of organoradionuclide complexes. The ability of indigenous microflora of the radioactive waste to degrade the organic compounds under aerobic and anaerobic conditions was examined. Leachate samples were extracted with methylene chloried and analyzed for organic compounds by gas chromatography and mass spectrometry. In general, several of the organic compounds in the leachates were degraded under aerobic conditions. Under anaerobic conditions, the degradation of the organics was very slow, and changes in concentrations of several acidic compounds were observed. Several low-molecular-weight organic acids are formed by breakdown of complex organic materials and are further metabolized by microorganisms; hence these compounds are in a dynamic state, being both synthesized and destroyed. Tributyl phosphate, a compound used in the extraction of metal ions from solutions of reactor products, was not degraded under anaerobic conditions.

  19. Approximate solutions of the filtered radiative transfer equation in large eddy simulations of turbulent reactive flows

    SciTech Connect

    Coelho, P.J.

    2009-05-15

    An analysis of the relevance of turbulence-radiation interaction in the numerical simulation of turbulent reactive flows is presented. A semi-causal stochastic model was used to generate a time-series of turbulent scalar fluctuations along optical paths of Sandia flame D, a widely studied piloted turbulent jet nonpremixed flame. The radiative transfer equation was integrated along these paths for every realization using a grid resolution typical of a direct numerical simulation. The correlated k-distribution method was employed to compute the radiative properties of the medium. The results were used to determine the ensemble average, as well as the extreme values, of quantities that indicate the importance of the turbulence-radiation interaction. Several approximate methods are then proposed to solve the filtered radiative transfer equation in the framework of large eddy simulations. The proposed methods are applicable along with combustion models that either assume the filtered probability density function of a conserved scalar or solve a transport equation for a joint scalar or joint scalar/velocity filtered density function. It is concluded that the errors resulting from neglecting the turbulence-radiation interaction in large eddy simulations are much lower than those found in Reynolds-averaged Navier-Stokes calculations. The optically thin fluctuation approximation may be extended to large eddy simulations yielding predictions in excellent agreement with the reference solution. If the turbulence-radiation interaction is accounted for using this approximation, the average relative error of the filtered total radiation intensity is generally below 0.3% for the studied flame. (author)

  20. Dietary fibers affect viscosity of solutions and simulated human gastric and small intestinal digesta.

    PubMed

    Dikeman, Cheryl L; Murphy, Michael R; Fahey, George C

    2006-04-01

    Two experiments were conducted to determine the viscosities of both soluble and insoluble dietary fibers. In Expt. 1, corn bran, defatted rice bran, guar gum, gum xanthan, oat bran, psyllium, soy hulls, stabilized rice bran, wheat bran, wood cellulose, and 2 methylcellulose controls (Ticacel 42, Ticacel 43) were hydrated in water overnight at 0.5, 1, 1.5, or 2% concentrations. In Expt. 2, guar gum, oat bran, psyllium, rice bran, wheat bran, and wood cellulose were subjected to a 2-stage in vitro gastric and small intestinal digestion simulation model. Viscosity was measured every 2 and 3 h during gastric and small intestinal simulation, respectively. Viscosities in both experiments were measured at multiple shear rates. Viscosities of all fiber solutions were concentration- and shear rate-dependent. Rice brans, soy hulls, and wood cellulose had the lowest viscosities, whereas guar gum, psyllium, and xanthan gum had the highest viscosities, regardless of concentration. During gastric simulation, viscosity was higher (P < 0.05) at 4 h than at 0 h for guar gum, psyllium, rice bran, and wheat bran. During small intestinal simulation, viscosities were higher (P < 0.05) between 3 and 9 h compared with 18 h for guar gum, oat bran, and rice bran. Guar gum, psyllium, and oat bran exhibited viscous characteristics throughout small intestinal simulation, indicating potential for these fibers to elicit blood glucose and lipid attenuation. Wheat and rice brans and wood cellulose did not exhibit viscous characteristics throughout small intestinal digestion; thus, they may be beneficial for laxation. PMID:16549450

  1. Size-exclusion partitioning of neutral solutes in crosslinked polymer networks: A Monte Carlo simulation study

    SciTech Connect

    Quesada-Pérez, Manuel; Maroto-Centeno, José Alberto; Adroher-Benítez, Irene

    2014-05-28

    In this work, the size-exclusion partitioning of neutral solutes in crosslinked polymer networks has been studied through Monte Carlo simulations. Two models that provide user-friendly expressions to predict the partition coefficient have been tested over a wide range of volume fractions: Ogston's model (especially devised for fibrous media) and the pore model. The effects of crosslinking and bond stiffness have also been analyzed. Our results suggest that the fiber model can acceptably account for size-exclusion effects in crosslinked gels. Its predictions are good for large solutes if the fiber diameter is assumed to be the effective monomer diameter. For solutes sizes comparable to the monomer dimensions, a smaller fiber diameter must be used. Regarding the pore model, the partition coefficient is poorly predicted when the pore diameter is estimated as the distance between adjacent crosslinker molecules. On the other hand, our results prove that the pore sizes obtained from the pore model by fitting partitioning data of swollen gels are overestimated.

  2. Nitrate-cancrinite precipitation on quartz sand in simulated Hanford tank solutions.

    PubMed

    Bickmore, B R; Nagy, K L; Young, J S; Drexler, J W

    2001-11-15

    Caustic NaNO3 solutions containing dissolved Al were reacted with quartz sand at 89 degrees C to simulate possible reactions between leaked nuclear waste and primary subsurface minerals at the U.S. Department of Energy's Hanford site in Washington. Nitrate-cancrinite began to precipitate onto the quartz after 2-10 days, cementing the grains together. Estimates of the equilibrium constant for the precipitation reaction differ for solutions with 0.1 or 1.0 m OH- (log Keq = 30.4 +/- 0.8 and 36.2 +/- 0.6, respectively). The difference in solubility may be attributable to more perfect crystallinity (i.e., fewer stacking faults) in the higher-pH cancrinite structure. This is supported by electron micrographs of crystal morphology and measured rates of Na volatilization under an electron beam. Precipitate crystallinity may affect radionuclide mobility, because stacking faults in the cancrinite structure can diminish its zeolitic cation exchange properties. The precipitation rate near the onset of nucleation depends on the total Al and Si concentrations in solution. The evolution of experimental Si concentrations was modeled by considering the dependence of quartz dissolution rate on AI(OH)4- activity, cancrinite precipitation, and the reduction of reactive surface area of quartz due to coverage by cancrinite. PMID:11757605

  3. Molecular modeling simulations in phase stability of polyethylene solutions at elevated pressures

    NASA Astrophysics Data System (ADS)

    Shahamat, Moeed; Rey, Alejandro D.

    2013-03-01

    Molecular dynamics (MD) simulations using the OPLS-AA force field are conducted to compute pressure, molecular weight dependence of Hildebrand's solubility parameters (SP) and density of hexane and high-density polyethylene (HDPE) at high pressures from 100 to 3000 bar. The electrostatic energy contribution to the cohesive energy and density leads to increases in the SP with pressure for molecular mechanical models (MMM) with and without electrostatic terms. The Flory-Huggins interaction parameter (IP) predicted from the pressure dependence of SPs and molar volumes decreases upon increasing pressure, indicating that miscibility improves by raising pressure. This is consistent with the solution polymerization process for producing PE, where pressure-induced phase separation (PIPS) is used to separate the polymer from solution. Exclusion of electrostatic potentials in the MMM results in larger IPs while the decreasing trend remains intact with and without electrostatic forces. There is a pressure limit beyond which the IP has less sensitivity to pressure indicating that PE miscibility is not further affected. It is shown that pressure increases the chemical potential factor of the phase stability condition, stabilizing the solution. These results contribute to the fundamental understanding of PIPS, an important demixing process poorly understood when compared to thermally-induced phase separation.

  4. Influence of Acidity on Uranyl Nitrate Association in Aqueous Solutions: A Molecular Dynamics Simulation Study

    SciTech Connect

    de Almeida, Valmor F; Cui, Shengting; Khomami, Bamin; Ye, Xianggui; Smith, Rodney Bryan

    2010-01-01

    Uranyl ion complexation with water and nitrate is a key aspect of the uranium/plutonium extraction process. We have carried out a molecular dynamics simulation study to investigate this complexation process, including the molecular composition of the various complex species, the corresponding structure, and the equilibrium distribution of the complexes. The observed structures of the complexes suggest that in aqueous solution, uranyls are generally hydrated by 5 water molecules in the equatorial plane. When associating with nitrate ions, a water molecule is replaced by a nitrate ion, preserving the five-fold coordination and planar symmetry. Analysis of the pair correlation function between uranyl and nitrate suggests that nitrates bind to uranyl in aqueous solution mainly in a monodentate mode, although a small portion of bidentates occur. Dynamic association and dissociation between uranyls and nitrates take place in aqueous solution with a substantial amount of fluctuation in the number of various uranyl nitrate species. The average number of the uranyl mononitrate complexes shows a dependence on acid concentration consistent with equilibrium-constant analysis, namely, the concentration of [UO2NO3]+ increases with nitric acid concentration.

  5. Leaching studies of low-level radioactive waste forms

    SciTech Connect

    Dayal, R.; Arora, H.; Clinton, J.C.; Milian, L.

    1985-01-01

    A research program has been under way at the Brookhaven National Laboratory to investigate the radionuclide release behavior of ion exchange bead resin waste solidified in Portland cement. An important aspect of this program is to develop and evaluate testing procedures and methodologies which enable the long-term performance evaluation of waste forms under simulated field conditions. Cesium and strontium release behavior using a range of testing procedures, including intermittent leachant flow conditions, has been investigated. For cyclic wet/dry leaching tests, extended dry periods tend to enhance the release of Cs and suppress the release of Sr. Under extended wet period leaching conditions, however, both Cs and Sr exhibit suppressed releases. In contrast, radionuclide releases observed under continuously saturated leaching conditions, as represented by conventional leaching tests, are significantly different. The relevance and aplicability of these laboratory data obtained under a wide range of leaching conditions to the performance evaluation of waste forms under anticipated field conditions is discussed. 12 refs., 9 figs., 3 tabs.

  6. Thermal stability testing of low-level waste forms

    SciTech Connect

    Piciulo, P.L.; Chan, S.F.

    1985-05-01

    The NRC Technical Position (TP) on Waste Form specifies that waste forms should be resistant to thermal degradation. The thermal cycle testing procedure outlined in the TP on Waste Form was carried out and is believed adequate for demonstrating the thermal stability of solidified waste forms. The inclusion of control samples and the monitoring of sample temperature are recommended additions to the test. An outline for reporting thermal cycling test results is given. To produce a data base on the applicability of the thermal cycling test, the following simulated laboratory-scale waste forms were prepared and tested: boric acid and sodium sulfate evaporator bottoms, mixed bed bead resins, and powdered resins each solidified in asphalt, cement and vinyl ester-styrene. Thermal cycling does not significantly affect the compressive strength of the solidified wastes, except powdered resins solidified in cement which disintegrated during the test and bead resins in cement which showed a loss of compressive strength. After temperature cycling, cement solidified bead resins showed areas of spalling and solidified sodium sulfate forms had surface deterioration. Asphalt solidified wastes, except powdered resins, deformed by slumping on temperature cycling. Free liquid was released from vinyl esterstyrene solidifed waste forms as a result of thermal cycling. Dewatered bead and powdered resins were also tested and no free liquid was released on temperature cycling. 11 refs., 12 figs., 4 tabs.

  7. Simulation of in situ uraninite leaching-part III: The effects of solution concentration

    NASA Astrophysics Data System (ADS)

    Liddell, Knona C.; Bautista, Renato G.

    1995-08-01

    The effects of variations in the concentrations of leaching reagents have been simulated for in situ leaching of UO2 by H2O-(NH4)2CO3-NH4HCO3. The model used in the simulations incorporates rate laws for the mineral reactions, equilibrium reactions among the solution species, and a mixing cell representation of solution flow. Of the component concentrations, the major factor affecting the rate of uraninite dissolution is the oxidant concentration. High peroxide concentrations lead to more rapid reaction with an early maximum in the U(VI) concentration. If lower oxidant concentrations are used, the reaction is under mixed kinetic and mass transfer control and the U(VI) concentration is lower but approximately constant for an extended period. Because they increase the concentration of the HCO 3/- anion, high ammonium carbonate and ammonium bicarbonate concentrations also result in some enhancement in the rate of U leaching; the reaction is known to be half-order in both HCO3 - and H2O2. A 10:1 ratio of (NH4)2CO3 to NH4HCO3 concentrations was found to result in a nearly constant pH during most of the leaching process. Calcite-containing gangue causes an immediate pH increase from about 8.9 to 9.4. The rate of the calcite reaction, calcite saturation index, and porosity are all independent of the lixiviant concentrations. Detailed calculations of solution speciation are necessary to predict the concentrations of individual species from those of components.

  8. Electrokinetics for removal of low-level radioactivity from soil

    SciTech Connect

    Pamukcu, S.; Wittle, J.K.

    1993-03-01

    The electrokinetic process is an emerging technology for in situ soil decontamination in which chemical species, both ionic and nonionic, are transported to an electrode site in soil. These products are subsequently removed from the ground via collection systems engineered for each specific application. The work presented here describes part of the effort undertaken to investigate electrokinetically enhanced transport of soil contaminants in synthetic systems. These systems consisted of clay or clay-sand mixtures containing known concentrations of a selected heavy-metal salt solution. These metals included surrogate radionuclides such as Sr, Cs and U, and an anionic species of Cr. Degree of removal of these metals from soil by the electrokinetic treatment process was assessed through the metal concentration profiles generated across the soil between the electrodes. Removals of some metal species up to 99% were achieved at the anode or cathode end of the soil upon 24 to 48 hours of treatment or a maximum of 1 pore volume of water displacement toward the cathode compartment. Transient pH change through the soil had an effect on the metal movement, as evidenced by accumulation of the metals at the discharge ends of the soil specimens. This accumulation was attributed to the precipitation of the metal and increased cation retention capacity of the clay in high pH environment at the cathode end. In general, the reduced mobility and dissociation of the ionic species as they encounter areas of higher ionic concentration in their path of migration resulted in the accumulation of the metals at the discharge ends of the soil specimens.

  9. Development of chemically bonded phosphate ceramics for stabilizing low-level mixed wastes

    NASA Astrophysics Data System (ADS)

    Jeong, Seung-Young

    1997-11-01

    Novel chemically bonded phosphate ceramics have been developed by acid-base reactions between magnesium oxide and an acid phosphate at room temperature for stabilizing U.S. Department of Energy's low-level mixed waste streams that include hazardous chemicals and radioactive elements. Newberyite (MgHPOsb4.3Hsb2O)-rich magnesium phosphate ceramic was formed by an acid-base reaction between phosphoric acid and magnesium oxide. The reaction slurry, formed at room-temperature, sets rapidly and forms stable mineral phases of newberyite, lunebergite, and residual MgO. Rapid setting also generates heat due to exothermic acid-base reaction. The reaction was retarded by partially neutralizing the phosphoric acid solution by adding sodium or potassium hydroxide. This reduced the rate of reaction and heat generation and led to a practical way of producing novel magnesium potassium phosphate ceramic. This ceramic was formed by reacting stoichiometric amount of monopotassium dihydrogen phosphate crystals, MgO, and water, forming pure-phase of MgKPOsb4.6Hsb2O (MKP) with moderate exothermic reaction. Using this chemically bonded phosphate ceramic matrix, low-level mixed waste streams were stabilized, and superior waste forms in a monolithic structure were developed. The final waste forms showed low open porosity and permeability, and higher compression strength than the Land Disposal Requirements (LDRs). The novel MKP ceramic technology allowed us to develop operational size waste forms of 55 gal with good physical integrity. In this improved waste form, the hazardous contaminants such as RCRA heavy metals (Hg, Pb, Cd, Cr, Ni, etc) were chemically fixed by their conversion into insoluble phosphate forms and physically encapsulated by the phosphate ceramic. In addition, chemically bonded phosphate ceramics stabilized radioactive elements such U and Pu. This was demonstrated with a detailed stabilization study on cerium used as a surrogate (chemically equivalent but nonradioactive

  10. Adsorption of HMF from water/DMSO solutions onto hydrophobic zeolites: experiment and simulation.

    PubMed

    Xiong, Ruichang; León, Marta; Nikolakis, Vladimiros; Sandler, Stanley I; Vlachos, Dionisios G

    2014-01-01

    The adsorption of 5-hydroxymethylfurfural (HMF), DMSO, and water from binary and ternary mixtures in hydrophobic silicalite-1 and dealuminated Y (DAY) zeolites at ambient conditions was studied by experiments and molecular modeling. HMF and DMSO adsorption isotherms were measured and compared to those calculated using a combination of grand canonical Monte Carlo and expanded ensemble (GCMC-EE) simulations. A method based on GCMC-EE simulations for dilute solutions combined with the Redlich-Kister (RK) expansion (GCMC-EE-RK) is introduced to calculate the isotherms over a wide range of concentrations. The simulations, using literature force fields, are in reasonable agreement with experimental data. In HMF/water binary mixtures, large-pore hydrophobic zeolites are much more effective for HMF adsorption but less selective because large pores allow water adsorption because of H2 O-HMF attraction. In ternary HMF/DMSO/water mixtures, HMF loading decreases with increasing DMSO fraction, rendering the separation of HMF from water/DMSO mixtures by adsorption difficult. The ratio of the energetic interaction in the zeolite to the solvation free energy is a key factor in controlling separation from liquid mixtures. Overall, our findings could have an impact on the separation and catalytic conversion of HMF and the rational design of nanoporous adsorbents for liquid-phase separations in biomass processing. PMID:24106213

  11. Solution structure of hyaluronic acid oligomers by experimental and theoretical NMR, and molecular dynamics simulation.

    PubMed

    Donati, A; Magnani, A; Bonechi, C; Barbucci, R; Rossi, C

    2001-11-01

    The conformational properties of hyaluronic acid (HA) oligomers in aqueous solution were investigated by combining high-resolution NMR experimental results, theoretical simulation of NMR two-dimensional (2D) spectra by Complete Relaxation Matrix Analysis (CORMA), and molecular dynamics calculations. New experimental findings recorded for the tetra- and hexasaccharides enabled the stiffness of the HA and its viscoelastic properties to be interpreted. In particular, rotating frame nuclear Overhauser effect spectroscopy spectra provided new information about the arrangement of the glycosidic linkage. From (13)C NMR relaxation the rotational correlation time (tau(c)) were determined. The tau(c) were employed in the calculation of geometrical constraints, by using the MARDIGRAS algorithm. Restrained simulated annealing and 1 ns of unrestrained molecular dynamic simulations were performed on the hexasaccharide in a box of 1215 water molecules. The beta(1 --> 3) and beta(1 --> 4) glycosidic links were found to be rigid. The lack of rotational degree of freedom is due to direct and/or water-mediated interresidue hydrogen bonding. Both single or tandem water bridges were found between carboxylate group and N-acetil group. The carboxylate group of glucuronic acid is not involved in a direct link with the amide group of N-acetyl glucosamine and this facilitated bonding between the residue and the water molecules. PMID:11598878

  12. Development of a multimedia radionuclide exposure model for low-level waste management

    SciTech Connect

    Onishi, Y.; Whelan, G.; Skaggs, R.L.

    1982-03-01

    A method is being developed for assessing exposures of the air, water, and plants to low-level waste (LLW) as a part of an overall development effort of a LLW site evaluation methodology. The assessment methodology will predict LLW exposure levels in the environment by simulating dominant mechanisms of LLW migration and fate. The methodology consists of a series of physics-based models with proven histories of success; the models interact with each other to simulate LLW transport in the ecosystem. A scaled-down version of the methodology was developed first by combining the terrestrial ecological model, BIOTRAN; the overland transport model, ARM; the instream hydrodynamic model, DKWAV; and the instream sediment-contaminant transport model, TODAM (a one-dimensional version of SERATRA). The methodology was used to simulate the migration of /sup 239/Pu from a shallow-land disposal site (known as Area C) located near the head of South Mortandad Canyon on the LANL site in New Mexico. The scenario assumed that /sup 239/Pu would be deposited on the land surface through the natural processes of plant growth, LLW uptake, dryfall, and litter decomposition. Runoff events would then transport /sup 239/Pu to and in the canyon. The model provided sets of simulated LLW levels in soil, water and terrestrial plants in the region surrounding the site under a specified land-use and a waste management option. Over a 100-yr simulation period, only an extremely small quantity (6 x 10/sup -9/ times the original concentration) of buried /sup 239/Pu was taken up by plants and deposited on the land surface. Only a small fraction (approximately 1%) of that contamination was further removed by soil erosion from the site and carried to the canyon, where it remained. Hence, the study reveals that the environment around Area C has integrity high enough to curtail LLW migration under recreational land use.

  13. Greater-than-Class C low-level waste characterization. Appendix F: Greater-than-Class C low-level radioactive waste light water reactor projections

    SciTech Connect

    Tuite, P.; Tuite, K.; Levin, A.; O`Kelley, M.

    1991-08-01

    This study characterizes potential greater-than-Class C low-level radioactive waste streams, estimates the amounts of waste generated, and estimates their radionuclide content and distribution. Several types of low-level radioactive wastes produced by light water reactors were identified in an earlier study as being potential greater-than-Class C low-level waste, including specific activated metal components and certain process wastes in the form of cartridge filters and decontamination resins. Light water reactor operating parameters and current management practices at operating plants were reviewed and used to estimate the amounts of potential greater-than-Class C low-level waste generated per fuel cycle. The amounts of routinely generated activated metal components and process waste were estimated as a function of fuel cycle. Component-specific radionuclide content and distribution was calculated for activated metals components. Empirical data from actual low-level radioactive waste streams were used to estimate radionuclide content and distribution for process wastes. The greater-than-Class C low-level waste volumes that could be generated through plant closure were also estimated, along with volumes and activities for potential greater-than-Class C activated metals generated at decommissioning.

  14. Generic Procedure for Coupling the PHREEQC Geochemical Modeling Framework with Flow and Solute Transport Simulators

    NASA Astrophysics Data System (ADS)

    Wissmeier, L. C.; Barry, D. A.

    2009-12-01

    Computer simulations of water availability and quality play an important role in state-of-the-art water resources management. However, many of the most utilized software programs focus either on physical flow and transport phenomena (e.g., MODFLOW, MT3DMS, FEFLOW, HYDRUS) or on geochemical reactions (e.g., MINTEQ, PHREEQC, CHESS, ORCHESTRA). In recent years, several couplings between both genres of programs evolved in order to consider interactions between flow and biogeochemical reactivity (e.g., HP1, PHWAT). Software coupling procedures can be categorized as ‘close couplings’, where programs pass information via the memory stack at runtime, and ‘remote couplings’, where the information is exchanged at each time step via input/output files. The former generally involves modifications of software codes and therefore expert programming skills are required. We present a generic recipe for remotely coupling the PHREEQC geochemical modeling framework and flow and solute transport (FST) simulators. The iterative scheme relies on operator splitting with continuous re-initialization of PHREEQC and the FST of choice at each time step. Since PHREEQC calculates the geochemistry of aqueous solutions in contact with soil minerals, the procedure is primarily designed for couplings to FST’s for liquid phase flow in natural environments. It requires the accessibility of initial conditions and numerical parameters such as time and space discretization in the input text file for the FST and control of the FST via commands to the operating system (batch on Windows; bash/shell on Unix/Linux). The coupling procedure is based on PHREEQC’s capability to save the state of a simulation with all solid, liquid and gaseous species as a PHREEQC input file by making use of the dump file option in the TRANSPORT keyword. The output from one reaction calculation step is therefore reused as input for the following reaction step where changes in element amounts due to advection

  15. Multi-objective optimization of a conceptual model for simulating streamflow and solute concentration

    NASA Astrophysics Data System (ADS)

    Tanakamaru, H.; Tada, A.; Watanabe, K.

    2013-12-01

    This study discusses the applicability of compromise programming to multi-objective optimization of a conceptual model for simulating streamflow and solute concentration. Study area is Gojo experimental catchment of 12.82 ha located in Nara prefecture, Japan. Precipitation and streamflow data every 10 minutes from May, 2007 through April, 2011 and sodium concentration data every 15 minutes from June, 2009 through April, 2011 observed at the outlet of catchment were used here. Streamflow data were measured by a V-notch weir. Sodium concentration data (mg/l unit) were measured by the flow injection potentiometry (FIP) system using ion-selective electrodes (ISEs) and concentration data every 10 minutes were estimated by liner interpolation. Daily potential evapotranspiration estimated by Penman equation were also used. Streamflow was simulated by the Long- and Short-Term Runoff Model (LSTRM) and sodium concentration was estimated by four CQ equations of power type applied to four simulated runoff components (surface flow, interflow, subsurface flow and groundwater flow). The LSTRM consists of three storage tanks and it has 14 parameters including 3 initial storage depths to be calibrated. The CQ equation for one of runoff components has 2 parameters and 8 parameters should be calibrated. In this study, the following three parameter sets (Model A, B and C) were estimated by Root Mean Square Error (RMSE) minimizing by SCE-UA method. Model A: firstly 14 parameters of LSTRM were estimated by streamflow data and secondly 8 parameters of CQ equations were estimated by sodium concentration data. Model B: 22 parameters were estimated by using only sodium concentration data. Model C: the compromise programming (Yu, 1973; Zeleny, 1973) was applied. Firstly, the objective space which has horizontal axis of streamflow RMSE and vertical axis of concentration RMSE were set and the ideal point were plotted by streamflow RMSE of Model A and concentration RMSE of Model B. Secondly

  16. July 2012 Greenland melt extent enhanced by low-level liquid clouds.

    PubMed

    Bennartz, R; Shupe, M D; Turner, D D; Walden, V P; Steffen, K; Cox, C J; Kulie, M S; Miller, N B; Pettersen, C

    2013-04-01

    Melting of the world's major ice sheets can affect human and environmental conditions by contributing to sea-level rise. In July 2012, an historically rare period of extended surface melting was observed across almost the entire Greenland ice sheet, raising questions about the frequency and spatial extent of such events. Here we show that low-level clouds consisting of liquid water droplets ('liquid clouds'), via their radiative effects, played a key part in this melt event by increasing near-surface temperatures. We used a suite of surface-based observations, remote sensing data, and a surface energy-balance model. At the critical surface melt time, the clouds were optically thick enough and low enough to enhance the downwelling infrared flux at the surface. At the same time they were optically thin enough to allow sufficient solar radiation to penetrate through them and raise surface temperatures above the melting point. Outside this narrow range in cloud optical thickness, the radiative contribution to the surface energy budget would have been diminished, and the spatial extent of this melting event would have been smaller. We further show that these thin, low-level liquid clouds occur frequently, both over Greenland and across the Arctic, being present around 30-50 per cent of the time. Our results may help to explain the difficulties that global climate models have in simulating the Arctic surface energy budget, particularly as models tend to under-predict the formation of optically thin liquid clouds at supercooled temperatures--a process potentially necessary to account fully for temperature feedbacks in a warming Arctic climate. PMID:23552947

  17. Noise and Low-Level Dynamics Can Coordinate Multicomponent Bet Hedging Mechanisms

    PubMed Central

    Garcia-Bernardo, Javier; Dunlop, Mary J.

    2015-01-01

    To counter future uncertainty, cells can stochastically express stress response mechanisms to diversify their population and hedge against stress. This approach allows a small subset of the population to survive without the prohibitive cost of constantly expressing resistance machinery at the population level. However, expression of multiple genes in concert is often needed to ensure survival, requiring coordination of infrequent events across many downstream targets. This raises the question of how cells orchestrate the timing of multiple rare events without adding cost. To investigate this, we used a stochastic model to study regulation of downstream target genes by a transcription factor. We compared several upstream regulator profiles, including constant expression, pulsatile dynamics, and noisy expression. We found that pulsatile dynamics and noise are sufficient to coordinate expression of multiple downstream genes. Notably, this is true even when fluctuations in the upstream regulator are far below the dissociation constants of the regulated genes, as with infrequently activated genes. As an example, we simulated the dynamics of the multiple antibiotic resistance activator (MarA) and 40 diverse downstream genes it regulates, determining that low-level dynamics in MarA are sufficient to coordinate expression of resistance mechanisms. We also demonstrated that noise can play a similar coordinating role. Importantly, we found that these benefits are present without a corresponding increase in the population-level cost. Therefore, our model suggests that low-level dynamics or noise in a transcription factor can coordinate expression of multiple stress response mechanisms by engaging them simultaneously without adding to the overall cost. PMID:25564865

  18. Low-Level Waste Forum meeting report. Quarterly meeting, April 25--27, 1990

    SciTech Connect

    1990-12-31

    The Low-Level Radioactive Waste Forum is an association of representatives of states and compacts established to facilitate state and compact commission implementation of the Low-Level Radioactive Waste Policy Act of 1980 and the Low-Level Radioactive Waste Policy Amendments Act of 1985 and to promote the objectives of low-level radioactive waste regional compacts. The Forum provides an opportunity for states and compacts to share information with one another and to exchange views with officials of federal agencies. The Forum participants include representatives from regional compacts, designated host states, unaffiliated states, and states with currently-operating low-level radioactive waste facilities. This report contains information synthesizing the accomplishments of the Forum, as well as any new advances that have been made in the management of low-level radioactive wastes.

  19. Low-level Waste Forum meeting report. Summer meeting, July 21--23, 1993

    SciTech Connect

    1993-12-31

    The Low-Level Radioactive Waste Forum is an association of representatives of states and compacts established to facilitate state and compact commission implementation of the Low-Level Radioactive Waste Policy Act of 1980 and the Low-Level Radioactive Waste Policy Amendments Act of 1985 and to promote the objectives of low-level radioactive waste regional compacts. The Forum provides an opportunity for states and compacts to share information with one another and to exchange views with officials of federal agencies. The Forum participants include representatives from regional compacts, designated host states, unaffiliated states, and states with currently-operating low-level radioactive waste facilities. This report contains information synthesizing the accomplishments of the Forum, as well as any new advances that have been made in the management of low-level radioactive wastes.

  20. Low-Level Waste Forum meeting report. Quarterly meeting, July 23--24, 1990

    SciTech Connect

    1990-12-31

    The Low-Level Radioactive Waste Forum is an association of representatives of states and compacts established to facilitate state and compact commission implementation of the Low-Level Radioactive Waste Policy Act of 1980 and the Low-Level Radioactive Waste Policy Amendments Act of 1985 and to promote the objectives of low-level radioactive waste regional compacts. The Forum provides an opportunity for states and compacts to share information with one another and to exchange views with officials of federal agencies. The Forum participants include representatives from regional compacts, designated host states, unaffiliated states, and states with currently-operating low-level radioactive waste facilities. This report contains information synthesizing the accomplishments of the Forum, as well as any new advances that have been made in the management of low-level radioactive wastes.

  1. Low-level Waste Forum meeting report. Spring meeting, April 28--30, 1993

    SciTech Connect

    1993-12-31

    The Low-Level Radioactive Waste Forum is an association of representatives of states and compacts established to facilitate state and compact commission implementation of the Low-Level Radioactive Waste Policy Act of 1980 and the Low-Level Radioactive Waste Policy Amendments Act of 1985 and to promote the objectives of low-level radioactive waste regional compacts. The Forum provides an opportunity for states and compacts to share information with one another and to exchange views with officials of federal agencies. The Forum participants include representatives from regional compacts, designated host states, unaffiliated states, and states with currently-operating low-level radioactive waste facilities. This report contains information synthesizing the accomplishments of the Forum, as well as any new advances that have been made in the management of low-level radioactive wastes.

  2. Lunar Dust and Lunar Simulant Activation, Monitoring, Solution and Cellular Toxicity Properties

    NASA Technical Reports Server (NTRS)

    Jeevarajan, A.S.; Wallace, W.T.

    2009-01-01

    During the Apollo missions, many undesirable situations were encountered that must be mitigated prior to returning humans to the moon. Lunar dust (that part of the lunar regolith less than 20 m in diameter) was found to produce several problems with astronaut s suits and helmets, mechanical seals and equipment, and could have conceivably produced harmful physiological effects for the astronauts. For instance, the abrasive nature of the dust was found to cause malfunctions of various joints and seals of the spacecraft and suits. Additionally, though efforts were made to exclude lunar dust from the cabin of the lunar module, a significant amount of material nonetheless found its way inside. With the loss of gravity correlated with ascent of the lunar module from the lunar surface to rendezvous with the command module, much of the major portions of the contaminating soil and dust began to float, irritating the astronaut s eyes and being inhaled into their lungs. Our goal has been to understand some of the properties of lunar dust that could lead to possible hazards for humans. Due to the lack of an atmosphere, there is nothing to protect the lunar soil from ultraviolet radiation, solar wind, and meteorite impacts. These processes could all serve to activate the soil, or produce reactive surface species. In order to understand the possible toxic effects of the reactive dust, it is necessary to reactivate the dust, as samples returned during the Apollo missions were exposed to the atmosphere of the Earth. We have used grinding and UV exposure to mimic some of the processes occurring on the Moon. The level of activation has been monitored using two methods: fluorescence spectroscopy and electron paramagnetic resonance spectroscopy (EPR). These techniques allow the monitoring of hydroxyl radical production in solution. We have found that grinding of lunar dust produces 2-3 times the concentration of hydroxyl radicals as lunar simulant and 10 times that of quartz. Exposure

  3. Structure and flow properties of micelle-nanoparticle solutions from Molecular Dynamics simulations

    NASA Astrophysics Data System (ADS)

    Sureshkumar, Radhakrishna; Dhakal, Subas; Sambasivam, Abhinanden

    2014-03-01

    In aqueous media, cationic surfactant molecules spontaneously self-assemble into diverse morphologies depending upon temperature, surfactant concentration and solution ionic strength. Spherical, cylindrical and long (~ microns) flexible wormlike structures with or without branches with distinct rheological properties are observed. Inclusion of nanoparticles (NPs) provides additional means to manipulate structure and create active ``nano-fluids'' that respond to optical, magnetic or electrical stimuli. We study self-assembly, dynamics and rheology of such fluids using coarse-grained Molecular Dynamics simulations in presence of explicit solvent and salt. Specifically, we will discuss the mechanisms underlying fascinating phenomenology observed experimentally such as the pronounced non-monotonic dependence of the zero shear viscosity on salt/NP concentration, shear-induced structure formation, and isotropic to nematic transitions. NSF grants 1049489, 1049454 for the financial support, and Pittsburg Super Computer Centre for providing HPC resources.

  4. Improved implementation of Kirkwood-Buff solution theory in periodic molecular simulations.

    PubMed

    Nichols, Joseph W; Moore, Stan G; Wheeler, Dean R

    2009-11-01

    Kirkwood-Buff (KB) solution theory is a means to obtain certain thermodynamic derivatives from knowledge of molecular distributions. In actual practice the required integrals over radial distribution functions suffer inaccuracies due to finite-distance truncation effects and their use in closed systems. In this work we discuss how best to minimize these inaccuracies under traditional KB theory. In addition we implement a method for calculating KB quantities in molecular simulations with periodic boundary conditions and particularly within the canonical ensemble. The method is based on a finite-Fourier-series expansion of molecular concentration fluctuations and leads to more reliable results for a given computational effort. The procedure is validated and compared to the original method for a nonideal liquid mixture of Lennard-Jones particles intended to imitate a real system, carbon tetrafluoride, and methane. PMID:20364973

  5. Molecular dynamics simulations of poly (ethylene oxide) hydration and conformation in solutions

    NASA Astrophysics Data System (ADS)

    Dahal, Udaya; Dormidontova, Elena

    Polyethylene oxide (PEO) is one of the most actively used polymers, especially in biomedical applications due to its high hydrophilicity, biocompatibility and potency to inhibit protein adsorption. PEO solubility and conformation in water depends on its capability to form hydrogen bonds. Using atomistic molecular dynamics simulations we investigated the details of water packing around PEO chain and characterized the type and lifetime of hydrogen bonds in aqueous and mixed solvent solutions. The observed polymer chain conformation varies from an extended coil in pure water to collapsed globule in hexane and a helical-like conformation in pure isobutyric acid or isobutyric acid -water mixture in agreement with experimental observations. We'll discuss the implications of protic solvent arrangement and stability of hydrogen bonds on PEO chain conformation and mobility. This research is supported by NSF (DMR-1410928).

  6. The Electrochemical Behavior of TiN/316LSS Material in Simulated Body Fluid Solution.

    PubMed

    Thanh, Dinh Thi Mai; Pham, Thi Nam; Huong, Ho Thu; Phuong, Nguyen Thu; Hang, To Thi Xuan; Vy, Uong Van; Hoang, Thai

    2015-05-01

    We report on the fabrication and the electrochemical behavior of TiN film on the 316L stainless steel (316LSS) material in simulated body fluid (SBF) solution for implant application. The characterization results indicate that the coated TiN is completely crystalline with (111) crystal orientation. Electrochemical results of 316LSS and TiN/316LSS material after 21 days of immersion in SBF show that the durability of the TiN/316LSS is much higher than that of 316LSS, which registers a very low corrosion current density (about tens of nA cm(-2)). The formation of hydroxyapatite on the surface of the TiN/316LSS is also confirmed by SEM, EDX, X-ray and IR spectroscopy. PMID:26505019

  7. Immobilization and Waste Form Product Acceptance for Low Level and TRU Waste Forms

    SciTech Connect

    Holtzscheiter, E.W.; Harbour, J.R.

    1998-05-01

    The Tanks Focus Area is supporting technology development in immobilization of both High Level (HLW) and Low Level (LLW) radioactive wastes. The HLW process development at Hanford and Idaho is patterned closely after that of the Savannah River (Defense Waste Processing Facility) and West Valley Sites (West Valley Demonstration Project). However, the development and options open to addressing Low Level Waste are diverse and often site specific. To start, it is important to understand the breadth of Low Level Wastes categories.

  8. Comparative life-cycle cost analysis for low-level mixed waste remediation alternatives

    SciTech Connect

    Jackson, J.A.; White, T.P.; Kloeber, J.M.; Toland, R.J.; Cain, J.P.; Buitrago, D.Y.

    1995-03-01

    The purpose of this study is two-fold: (1) to develop a generic, life-cycle cost model for evaluating low-level, mixed waste remediation alternatives, and (2) to apply the model specifically, to estimate remediation costs for a site similar to the Fernald Environmental Management Project near Cincinnati, OH. Life-cycle costs for vitrification, cementation, and dry removal process technologies are estimated. Since vitrification is in a conceptual phase, computer simulation is used to help characterize the support infrastructure of a large scale vitrification plant. Cost estimating relationships obtained from the simulation data, previous cost estimates, available process data, engineering judgment, and expert opinion all provide input to an Excel based spreadsheet for generating cash flow streams. Crystal Ball, an Excel add-on, was used for discounting cash flows for net present value analysis. The resulting LCC data was then analyzed using multi-attribute decision analysis techniques with cost and remediation time as criteria. The analytical framework presented allows alternatives to be evaluated in the context of budgetary, social, and political considerations. In general, the longer the remediation takes, the lower the net present value of the process. This is true because of the time value of money and large percentage of the costs attributed to storage or disposal.

  9. Taiwan industrial cooperation program technology transfer for low-level radioactive waste final disposal - phase I.

    SciTech Connect

    Knowlton, Robert G.; Cochran, John Russell; Arnold, Bill Walter; Jow, Hong-Nian; Mattie, Patrick D.; Schelling, Frank Joseph Jr.

    2007-01-01

    Sandia National Laboratories and the Institute of Nuclear Energy Research, Taiwan have collaborated in a technology transfer program related to low-level radioactive waste (LLW) disposal in Taiwan. Phase I of this program included regulatory analysis of LLW final disposal, development of LLW disposal performance assessment capabilities, and preliminary performance assessments of two potential disposal sites. Performance objectives were based on regulations in Taiwan and comparisons to those in the United States. Probabilistic performance assessment models were constructed based on limited site data using software including GoldSim, BLT-MS, FEHM, and HELP. These software codes provided the probabilistic framework, container degradation, waste-form leaching, groundwater flow, radionuclide transport, and cover infiltration simulation capabilities in the performance assessment. Preliminary performance assessment analyses were conducted for a near-surface disposal system and a mined cavern disposal system at two representative sites in Taiwan. Results of example calculations indicate peak simulated concentrations to a receptor within a few hundred years of LLW disposal, primarily from highly soluble, non-sorbing radionuclides.

  10. Codisposal of diminimus levels of low-level radioactive waste and sanitary waste: Final report

    SciTech Connect

    Chian, E.S.K.; Ghosh, S.B.; Kahn, B.; Giabbai, M.; Pohland, F.G.

    1986-02-01

    Codisposal of low-level radioactive waste (LLRW) with municipal refuse was investigated in two pilot-scale controlled concrete lysimeters; 3.05 m x 3.05 m x 4.28 m that were lined with 0.762 mm (30-mil) HDA Gundline liner, elastomeric polyolefin alloy based high density polyethylene, and had provisions for leachate collection and recirculation. Shredded municipal refuse was placed within the landfills and spiked with radionuclides (Co-58, Sr-85, and Ce-141) at a level of 28 nCi/gm to simulate codisposal of LLRW with municipal refuse. Water was added to simulate normal rainfall events; the extent to which radionuclides and organics were leached from both landfills was recorded. To compare the effect of leachate recirculation on the indicator parameters, leachate recycle was practiced in one of the landfills, while the other was operated as a single-pass system. Analyses on leachate samples, collected from both landfills, included detection of Co-58, Sr-85, and Ce-141 along with pH, ORP, conductivity, total alkalinity, COD, BOD/sub 5/, TOC, volatile fatty acids (acetic, propionic, isobutyric, butyric, and valeric), sulfide, chloride, iron, manganese, zinc, nickel, and cobalt. 113 refs., 47 figs., 23 tabs.

  11. Report to Congress: 1995 Annual report on low-level radioactive waste management progress

    SciTech Connect

    1996-06-01

    This report is prepared in response to the Low-Level Radioactive Waste Policy Act, Public Law 96-573, 1980, as amended by the Low-Level Radioactive Waste Policy Amendments Act of 1985, Public Law 99-240. The report summarizes the progress of states and compact regions during calendar year 1995 in establishing new disposal facilities for commercially-generated low-level radioactive waste. The report emphasizes significant issues and events that have affected progress, and also includes an introduction that provides background information and perspective on United States policy for low-level radioactive waste disposal.

  12. Aggregation in concentrated protein solutions: Insights from rheology, neutron scattering and molecular simulations

    NASA Astrophysics Data System (ADS)

    Castellanos, Maria Monica

    Aggregation of therapeutic proteins is currently one of the major challenges in the bio-pharmaceutical industry, because aggregates could induce immunogenic responses and compromise the quality of the product. Current scientific efforts, both in industry and academia, are focused on developing rational approaches to screen different drug candidates and predict their stability under different conditions. Moreover, aggregation is promoted in highly concentrated protein solutions, which are typically required for subcutaneous injection. In order to gain further understanding about the mechanisms that lead to aggregation, an approach that combined rheology, neutron scattering, and molecular simulations was undertaken. Two model systems were studied in this work: Bovine Serum Albumin in surfactant-free Phosphate Buffered Saline at pH = 7.4 at concentrations from 11 mg/mL up to ˜519 mg/mL, and a monoclonal antibody in 20 mM Histidine/Histidine Hydrochloride at pH = 6.0 with 60 mg/mL trehalose and 0.2 mg/mL polysorbate-80 at concentrations from 53 mg/mL up to ˜220 mg/mL. The antibody used here has three mutations in the CH2 domain, which result in lower stability upon incubation at 40 °C with respect to the wild-type protein, based on size-exclusion chromatography assays. This temperature is below 49 °C, where unfolding of the least stable, CH2 domain occurs, according to differential scanning calorimetry. This dissertation focuses on identifying the role of aggregation on the viscosity of protein solutions. The protein solutions of this work show an increase in the low shear viscosity in the absence of surfactants, because proteins adsorb at the air/water interface forming a viscoelastic film that affects the measured rheology. Stable surfactant-laden protein solutions behave as simple Newtonian fluids. However, the surfactant-laden antibody solution also shows an increase in the low shear viscosity from bulk aggregation, after prolonged incubation at 40 °C. Small

  13. Recent Developments in Fully Fluctuating Field-Theoretic Simulations of Polymer Melts and Solutions.

    PubMed

    Delaney, Kris T; Fredrickson, Glenn H

    2016-08-11

    We review the latest developments in computational methods for direct simulation of fully fluctuating field theories of polymeric assemblies. In this context, we describe a newly developed theoretical and computational framework for accurately computing fluctuation-corrected phase diagrams of mesostructured polymer systems and report the first such complete phase diagram for a diblock copolymer melt. The method is based on complex Langevin sampling of a UV regularized field-theoretic model, with Helmholtz free energies computed using thermodynamic integration. UV regularization ensures that the free energies do not have an arbitrary reference; they can be compared between incommensurate phases, permitting for the first time the computation of order-order transitions with fluctuation corrections. We further demonstrate that computed free energies are accurate in the disordered phase by comparison to perturbation theory on the one-loop level. Importantly, we note that our method uses no uncontrolled approximations beyond the initial definition of a coarse-grained molecular model for the polymer melt or solution. The method can be applied straightforwardly to melts and solutions containing multiple species with diverse polymer architectures. PMID:27414265

  14. Dissolution characteristics of Pu-contaminated soils and sediments in lung serum simulant solution.

    PubMed

    Lee, S Y; Bondietti, E A; Tamura, T

    1982-11-01

    Dissolution characteristics of Pu from contaminated Nevada Test Site (NTS) and Rocky Flats (RF) soils, and Mound Laboratory (ML) and Oak Ridge National Laboratory (ORNL) sediments in lung serum simulant solution at 37 degrees C were investigated. The dissolved Pu concentration had reached a maximum within a day of equilibration and the percent dissolved Pu at the maximum was 0.70 (RF), 0.43 (ML), 0.02 (ORNL), and 0.02 (NTS). The Pu concentrations of the RF, ML and ORNL samples in the successively extracted solutions decreased drastically but the concentration in the NTS soil extracts did not change significantly. The differences in Pu dissolution among the samples were caused by the differences in the total Pu concentration, particle size distribution, and chemical nature of Pu in contaminated soils and sediments. The higher solubility of the particulate Pu form in the RF soil relative to the ORNL sediment contaminated by dissolved Pu suggests that contamination source alone can not explain the observed differences. Variation of Pu solubility among the samples indicates that a single solubility class for dose assessment use may not be appropriate, particularly if one attempts to make comparative assessments among different sites. PMID:7152928

  15. Poisson-Nernst-Planck equations for simulating biomolecular diffusion-reaction processes I: Finite element solutions

    SciTech Connect

    Lu Benzhuo; Andrew McCammon, J.; Zhou, Y.C.

    2010-09-20

    In this paper we developed accurate finite element methods for solving 3-D Poisson-Nernst-Planck (PNP) equations with singular permanent charges for simulating electrodiffusion in solvated biomolecular systems. The electrostatic Poisson equation was defined in the biomolecules and in the solvent, while the Nernst-Planck equation was defined only in the solvent. We applied a stable regularization scheme to remove the singular component of the electrostatic potential induced by the permanent charges inside biomolecules, and formulated regular, well-posed PNP equations. An inexact-Newton method was used to solve the coupled nonlinear elliptic equations for the steady problems; while an Adams-Bashforth-Crank-Nicolson method was devised for time integration for the unsteady electrodiffusion. We numerically investigated the conditioning of the stiffness matrices for the finite element approximations of the two formulations of the Nernst-Planck equation, and theoretically proved that the transformed formulation is always associated with an ill-conditioned stiffness matrix. We also studied the electroneutrality of the solution and its relation with the boundary conditions on the molecular surface, and concluded that a large net charge concentration is always present near the molecular surface due to the presence of multiple species of charged particles in the solution. The numerical methods are shown to be accurate and stable by various test problems, and are applicable to real large-scale biophysical electrodiffusion problems.

  16. Diamylamylphosphonate solvent extraction of Am(VI) from nuclear fuel raffinate simulant solution

    SciTech Connect

    Bruce J. Mincher; Leigh R. Martin; Nicholas C. Schmitt

    2012-08-01

    The separation of hexavalent americium from the lanthanides in simulated PUREX raffinate solution using 1 M diamylamylphosphonate in dodecane extraction was investigated. Hexavalent americium was prepared using room-temperature sodium bismuthate oxidation. Under these conditions the majority of the lanthanides were not oxidized and remained inextractable. A separation factor of approximately 50 was provided for americium from europium over the nitric acid concentration range 6–7 M. Cerium was the exception with oxidation to CeIV resulting in its co-extraction with AmVI. However, since americium is readily reduced to AmIII it was easily stripped with a dilute acidic solution of hydrogen peroxide. Although hydrogen peroxide also reduces cerium, it does so slowly, and a selective americium strip was achieved, with a separation factor of between 15–25. Alternatively, since americium spontaneously reduced in the loaded organic phase, samples allowed to stand for 2 hours could be selectively stripped of americium by contact with 1 M HNO3 containing no additional reagents. The implications for use in fuel cycle separations are discussed.

  17. Ground-water flow and solute transport at a municipal landfill site on Long Island, New York; Part 3, Simulation of solute transport

    USGS Publications Warehouse

    Wexler, E.J.

    1988-01-01

    A solute transport model representing a 2.3-sq mi area surrounding and downgradient from a municipal landfill site in the Town of Brookhaven, N.Y. was used to simulate migration of a conservative solute (chloride) in the upper glacial aquifer. Aquifer values used in the model were: hydraulic conductivity, 200 ft/day; effective porosity, 0.30; longitudinal dispersivity, 100 ft; transverse dispersivity, 20 ft. Average concentration of chloride was set at 875.0 mg/L in leachate and 10 mg/L in recharge and in ambient groundwater. Entry of leachate into the aquifer was assumed to have begun in 1977. Chloride concentrations in the simulated plume after 6 years of travel matched reasonably well the chloride data collected in October-December 1982. After 12 years of travel, the simulated plume extended 6,200 ft and was 2,600 ft wide. Maximum predicted concentration at the site boundary was 160 mg/L. Additional simulations were made to test the model 's ability to predict the effect of several remedial strategies on the movement of solutes. These included capping the landfill with an impermeable surface, removal of contaminated groundwater through four recovery wells, and a combination of the first two actions. (USGS)

  18. A cellular automaton model adapted to sandboxes to simulate the transport of solutes

    NASA Astrophysics Data System (ADS)

    Lora, Boris; Donado, Leonardo; Castro, Eduardo; Bayuelo, Alfredo

    2016-04-01

    The increasingly use of groundwater sources for human consumption and the growth of the levels of these hydric sources contamination make imperative to reach a deeper understanding how the contaminants are transported by the water, in particular through a heterogeneous porous medium. Accordingly, the present research aims to design a model, which simulates the transport of solutes through a heterogeneous porous medium, using cellular automata. Cellular automata (CA) are a class of spatially (pixels) and temporally discrete mathematical systems characterized by local interaction (neighborhoods). The pixel size and the CA neighborhood were determined in order to reproduce accurately the solute behavior (Ilachinski, 2001). For the design and corresponding validation of the CA model were developed different conservative tracer tests using a sandbox packed heterogeneously with a coarse sand (size # 20 grain diameter 0,85 to 0,6 mm) and clay. We use Uranine and a saline solution with NaCl as a tracer which were measured taking snapshots each 20 seconds. A calibration curve (pixel intensity Vs Concentration) was used to obtain concentration maps. The sandbox was constructed of acrylic (caliber 0,8 cms) with 70 x 45 x 4 cms of dimensions. The "sandbox" had a grid of 35 transversal holes with a diameter of 4 mm each and an uniform separation from one to another of 10 cms. To validate the CA-model it was used a metric consisting in rating the number of correctly predicted pixels over the total per image throughout the entire test run. The CA-model shows that calibrations of pixels and neighborhoods allow reaching results over the 60 % of correctly predictions usually. This makes possible to think that the application of the CA- model could be useful in further researches regarding the transport of contaminants in hydrogeology.

  19. Squall Line Evolution in Response to a Developing Nocturnal Low-Level Jet and Mergers with Isolated Supercell Thunderstorms

    NASA Astrophysics Data System (ADS)

    French, Adam James

    2011-12-01

    Squall lines are a fairly ubiquitous feature around the globe, that can significantly impact society both by bringing beneficial rainfall, but also by producing a wide variety of hazardous weather. Given these potentially significant societal impacts, it is important to understand not only when and where squall lines may form, but also how squall lines may evolve. The present study addresses a portion of this problem by investigating how squall lines evolve in two complex, yet commonly observed scenarios: in the presence of a developing nocturnal low-level jet, and following mergers with isolated supercell thunderstorms. In the first part of this study, the impacts of a developing low-level jet on a mature squall line are investigated using idealized numerical simulations. These simulations are designed to mimic the environmental transition that occurs as night falls and the boundary layer stabilizes, while also including a gradually developing low-level wind maximum. The characteristics of the simulated LLJ atop a simulated stable boundary layer are based on past climatological studies of the LLJ in the central United States. A variety of jet orientations are tested, and sensitivities to jet height and the presence of low-level cooling are explored. The primary impacts of adding the LLJ are that it alters the wind shear in the layers just above and below the jet, and that it alters the magnitude of the storm-relative inflow in the jet layer. The changes to wind shear have an attendant impact on low-level lifting, in keeping with current theories for gust front lifting in squall lines. The changes to the system-relative inflow, in turn, impact total upward mass flux and precipitation output. Both are sensitive to the squall line-relative orientation of the LLJ, and change in time as the low-level cooling progresses. The second part of this study is focused on identifying features and storm evolutions common in cases of mergers between squall lines and isolated

  20. Electrodialysis of vanadium(III) and iron(II) ions from a simulated decontamination solution

    SciTech Connect

    Shim, J.B.; Oh, W.Z.; Lee, B.J.; Park, H.S.; Kim, J.D.

    1999-07-01

    The transport of vanadium(III) and iron(II) ions through the Nafion 117 cation-exchange membrane in the presence of picolinic acid was investigated by simulating the equilibrium distribution of ionic species as a function of pH, and by electrodialyzing the simulated waste solution. From distribution calculations of the model reaction systems it could be predicted that at pH 1.6 most vanadium ions exist predominantly in the form of the V{sup III}(Pic{sup {minus}}){sub 2}{sup +} complex, and this form of complex permeates across the cation-exchange membrane during electrodialysis. The experimental results, including variations in the color and cation concentrations of the catholyte, confirm the existence of the vanadium(III) picolinate complex. Iron ions permeated into the catholyte were converted to their hydroxide precipitates, which could be formed at the high pH condition resulting from the reduction of hydrogen ions and the production of OH{sup {minus}} ions by water electrolysis at the cathode. It was also found that the in-situ precipitation of iron in the electrodialyzer could be self-modulated by shifting the catholyte pH from the acidic state to the alkaline state during electrodialysis operation.

  1. Molecular dynamics simulation of electrokinetic flow of an aqueous electrolyte solution in nanochannels

    NASA Astrophysics Data System (ADS)

    Yoshida, Hiroaki; Mizuno, Hideyuki; Kinjo, Tomoyuki; Washizu, Hitoshi; Barrat, Jean-Louis

    2014-06-01

    Electrokinetic flows of an aqueous NaCl solution in nanochannels with negatively charged surfaces are studied using molecular dynamics simulations. The four transport coefficients that characterize the response to weak electric and pressure fields, namely, the coefficients for the electrical current in response to the electric field (Mjj) and the pressure field (Mjm), and those for the mass flow in response to the same fields (Mmj and Mmm), are obtained in the linear regime using a Green-Kubo approach. Nonequilibrium simulations with explicit external fields are also carried out, and the current and mass flows are directly obtained. The two methods exhibit good agreement even for large external field strengths, and Onsager's reciprocal relation (Mjm = Mmj) is numerically confirmed in both approaches. The influence of the surface charge density on the flow is also considered. The values of the transport coefficients are found to be smaller for larger surface charge density, because the counter-ions strongly bound near the channel surface interfere with the charge and mass flows. A reversal of the streaming current and of the reciprocal electro-osmotic flow, with a change of sign of Mmj due to the excess co-ions, takes places for very high surface charge density.

  2. Molecular Simulations of RNA 2’-O-Transesterification Reaction Models in Solution

    PubMed Central

    Radak, Brian K.; Harris, Michael E.

    2013-01-01

    We employ quantum mechanical/molecular mechanical umbrella sampling simulations to probe the free energy surfaces of a series of increasingly complex reaction models of RNA 2’-O-transesterification in aqueous solution under alkaline conditions. Such models are valuable for understanding the uncatalyzed processes underlying catalytic cleavage of the phosphodiester backbone of RNA, a reaction of fundamental importance in biology. The chemically reactive atoms are modeled by the AM1/d-PhoT quantum model for phosphoryl transfer, whereas the aqueous solvation environment is modeled with a molecular mechanics force field. Several simulation protocols were compared that used different ionic conditions and force field models. The results provide insight into how variation of the structural environment of the nucleophile and leaving group affects the free energy profile for the transesterification reaction. Results for a simple RNA backbone model are compared with recent experiments by Harris et al. on the specific base catalyzed cleavage of a UpG dinucleotide. The calculated and measured free energies of activation match extremely well (ΔF‡ = 19.9–20.8 versus 19.9 kcal/mol). Solvation is seen to play a crucial role and is characterized by a network of hydrogen bonds that envelopes the pentacoordinate dianionic phosphorane transition state and provides preferential stabilization relative to the reactant state. PMID:23214417

  3. Elastic turbulence in Taylor-Couette Flow of Dilute Polymeric Solutions: A Direct Numerical Simulation Study

    NASA Astrophysics Data System (ADS)

    Liu, Nansheng; Khomami, Bamin

    2011-11-01

    Despite tremendous progress in development of numerical techniques and constitutive theories for polymeric fluids in the past decade, Direct Numerical Simulation (DNS) of elastic turbulence has posed tremendous challenges to researchers engaged in developing first principles models and simulations that can accurately and robustly predict the dynamical behavior of polymeric flows. In this presentation, we report the first DNS of elastic turbulence in the Taylor-Couette (TC) flow. Specifically, our computations with prototypical constitutive equations for dilute polymeric solutions, such as the FENE-P model are capable of reproducing the essential features of the experimentally observed elastic turbulence in TC flow of this class of fluids, namely, randomly fluctuating fluid motion excited in a broad range of spatial and temporal scales, and a significant increase of the flow resistance. Moreover, the experimentally measured Power Spectral Density of radial velocity fluctuations, i.e., two contiguous regions of power-law decay, -1.1 at lower frequencies and -2.2 at high-frequencies is accurately computed. We would like to thank NSF through grant CBET-0755269 and NSFC through grant NO. 10972211 for supporting of this work.

  4. Simulation of intrathrombus fluid and solute transport using in vivo clot structures with single platelet resolution.

    PubMed

    Voronov, Roman S; Stalker, Timothy J; Brass, Lawrence F; Diamond, Scott L

    2013-06-01

    The mouse laser injury thrombosis model provides up to 0.22 μm-resolved voxel information about the pore architecture of the dense inner core and loose outer shell regions of an in vivo arterial thrombus. Computational studies were conducted on this 3D structure to quantify transport within and around the clot: Lattice Boltzmann method defined vessel hemodynamics, while passive Lagrangian Scalar Tracking with Brownian motion contribution simulated diffusive-convective transport of various inert solutes (released from lumen or the injured wall). For an input average lumen blood velocity of 0.478 cm/s (measured by Doppler velocimetry), a 0.2 mm/s mean flow rate was obtained within the thrombus structure, most of which occurred in the 100-fold more permeable outer shell region (calculated permeability of the inner core was 10(-11) cm(2)). Average wall shear stresses were 80-100 dyne/cm(2) (peak values >200 dyne/cm(2)) on the outer rough surface of the thrombus. Within the thrombus, small molecule tracers (0.1 kDa) experienced ~70,000 collisions/s and penetrated/exited it in about 1 s, whereas proteins (~50 kDa) had ~9000 collisions/s and required about 10 s (tortuosity ~2-2.5). These simulations help define physical processes during thrombosis and constraints for drug delivery to the thrombus. PMID:23423707

  5. Analysis of an anisotropic coastal aquifer system using variable-density flow and solute transport simulation

    USGS Publications Warehouse

    Souza, W.R.; Voss, C.I.

    1987-01-01

    The groundwater system in southern Oahu, Hawaii consists of a thick, areally extensive freshwater lens overlying a zone of transition to a thick saltwater body. This system is analyzed in cross section with a variable-density groundwater flow and solute transport model on a regional scale. The simulation is difficult, because the coastal aquifer system has a saltwater transition zone that is broadly dispersed near the discharge area, but is very sharply defined inland. Steady-state simulation analysis of the transition zone in the layered basalt aquifer of southern Oahu indicates that a small transverse dispersivity is characteristic of horizontal regional flow. Further, in this system flow is generally parallel to isochlors and steady-state behavior is insensitive to the longitudinal dispersivity. Parameter analysis identifies that only six parameters control the complex hydraulics of the system: horizontal and vertical hydraulic conductivity of the basalt aquifer; hydraulic conductivity of the confining "caprock" layer; leakance below the caprock; specific yield; and aquifer matrix compressibility. The best-fitting models indicate the horizontal hydraulic conductivity is significantly greater than the vertical hydraulic conductivity. These models give values for specific yield and aquifer compressibility which imply a considerable degree of compressive storage in the water table aquifer. ?? 1987.

  6. Molecular dynamics simulation of electrokinetic flow of an aqueous electrolyte solution in nanochannels.

    PubMed

    Yoshida, Hiroaki; Mizuno, Hideyuki; Kinjo, Tomoyuki; Washizu, Hitoshi; Barrat, Jean-Louis

    2014-06-01

    Electrokinetic flows of an aqueous NaCl solution in nanochannels with negatively charged surfaces are studied using molecular dynamics simulations. The four transport coefficients that characterize the response to weak electric and pressure fields, namely, the coefficients for the electrical current in response to the electric field (M(jj)) and the pressure field (M(jm)), and those for the mass flow in response to the same fields (M(mj) and M(mm)), are obtained in the linear regime using a Green-Kubo approach. Nonequilibrium simulations with explicit external fields are also carried out, and the current and mass flows are directly obtained. The two methods exhibit good agreement even for large external field strengths, and Onsager's reciprocal relation (M(jm) = M(mj)) is numerically confirmed in both approaches. The influence of the surface charge density on the flow is also considered. The values of the transport coefficients are found to be smaller for larger surface charge density, because the counter-ions strongly bound near the channel surface interfere with the charge and mass flows. A reversal of the streaming current and of the reciprocal electro-osmotic flow, with a change of sign of M(mj) due to the excess co-ions, takes places for very high surface charge density. PMID:24908029

  7. Comparison of three-dimensional Poisson solution methods for particle-based simulation and inhomogeneous dielectrics

    NASA Astrophysics Data System (ADS)

    Berti, Claudio; Gillespie, Dirk; Bardhan, Jaydeep P.; Eisenberg, Robert S.; Fiegna, Claudio

    2012-07-01

    Particle-based simulation represents a powerful approach to modeling physical systems in electronics, molecular biology, and chemical physics. Accounting for the interactions occurring among charged particles requires an accurate and efficient solution of Poisson's equation. For a system of discrete charges with inhomogeneous dielectrics, i.e., a system with discontinuities in the permittivity, the boundary element method (BEM) is frequently adopted. It provides the solution of Poisson's equation, accounting for polarization effects due to the discontinuity in the permittivity by computing the induced charges at the dielectric boundaries. In this framework, the total electrostatic potential is then found by superimposing the elemental contributions from both source and induced charges. In this paper, we present a comparison between two BEMs to solve a boundary-integral formulation of Poisson's equation, with emphasis on the BEMs' suitability for particle-based simulations in terms of solution accuracy and computation speed. The two approaches are the collocation and qualocation methods. Collocation is implemented following the induced-charge computation method of D. Boda [J. Chem. Phys.JCPSA60021-960610.1063/1.2212423 125, 034901 (2006)]. The qualocation method is described by J. Tausch [IEEE Transactions on Computer-Aided Design of Integrated Circuits and SystemsITCSDI0278-007010.1109/43.969433 20, 1398 (2001)]. These approaches are studied using both flat and curved surface elements to discretize the dielectric boundary, using two challenging test cases: a dielectric sphere embedded in a different dielectric medium and a toy model of an ion channel. Earlier comparisons of the two BEM approaches did not address curved surface elements or semiatomistic models of ion channels. Our results support the earlier findings that for flat-element calculations, qualocation is always significantly more accurate than collocation. On the other hand, when the dielectric boundary

  8. Simulation of dilute solutions of linear and star-branched polymers by dissipative particle dynamics.

    PubMed

    Nardai, M M; Zifferer, G

    2009-09-28

    A most promising off-lattice technique in order to simulate not only static but in addition dynamic behavior of linear and star-branched chains is the dissipative particle dynamics (DPD) method. In this model the atomistic representation of polymer molecules is replaced by a (coarse-grained) equivalent chain consisting of beads which are repulsive for each other in order to mimic the excluded volume effect (successive beads in addition are linked by springs). Likewise solvent molecules are combined to beads which in turn are repulsive for each other as well as for the polymer segments. The system is relaxed by molecular dynamics solving Newton's laws under the influence of short ranged conservative forces (i.e., repulsion between nonbonded beads and a proper balance of repulsion and attraction between bonded segments) and dissipative forces due to friction between particles, the latter representing the thermostat in conjunction with proper random forces. A variation of the strength of the repulsion between different types of beads allows the simulation of any desired thermodynamic situation. Static and dynamic properties of isolated linear and star-branched chains embedded in athermal, exothermal, and endothermal solvent are presented and theta conditions are examined. The generally accepted scaling concept for athermal systems is fairly well reproduced by linear and star-branched DPD chains and theta conditions appear for a unique parameter independent of functionality as in the case of Monte Carlo simulations. Furthermore, the correspondence between DPD and Monte Carlo data referring to the shape of chains and stars is fairly well, too. For dilute solutions the Zimm behavior is expected for dynamic properties which is indeed realized in DPD systems. PMID:19791917

  9. Lunar Dust and Lunar Simulant Activation, Monitoring, Solution and Cellular Toxicity Properties

    NASA Technical Reports Server (NTRS)

    Wallace, William; Jeevarajan, A. S.

    2009-01-01

    During the Apollo missions, many undesirable situations were encountered that must be mitigated prior to returning humans to the moon. Lunar dust (that part of the lunar regolith less than 20 microns in diameter) was found to produce several problems with mechanical equipment and could have conceivably produced harmful physiological effects for the astronauts. For instance, the abrasive nature of the dust was found to cause malfunctions of various joints and seals of the spacecraft and suits. Additionally, though efforts were made to exclude lunar dust from the cabin of the lunar module, a significant amount of material nonetheless found its way inside. With the loss of gravity correlated with ascent from the lunar surface, much of the finer fraction of this dust began to float and was inhaled by the astronauts. The short visits tothe Moon during Apollo lessened exposure to the dust, but the plan for future lunar stays of up to six months demands that methods be developed to minimize the risk of dust inhalation. The guidelines for what constitutes "safe" exposure will guide the development of engineering controls aimed at preventing the presence of dust in the lunar habitat. This work has shown the effects of grinding on the activation level of lunar dust, the changes in dissolution properties of lunar simulant, and the production of cytokines by cellular systems. Grinding of lunar dust leads to the production of radicals in solution and increased dissolution of lunar simulant in buffers of different pH. Additionally, ground lunar simulant has been shown to promote the production of IL-6 and IL-8, pro-inflammatory cytokines, by alveolar epithelial cells. These results provide evidence of the need for further studies on these materials prior to returning to the lunar surface.

  10. Specific ion interactions with aromatic rings in aqueous solutions: Comparison of molecular dynamics simulations with a thermodynamic solute partitioning model and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Vincent, Jordan C.; Matt, Sarah M.; Rankin, Blake M.; D'Auria, Raffaella; Freites, J. Alfredo; Ben-Amotz, Dor; Tobias, Douglas J.

    2015-10-01

    Specific ion interactions of KF, and the Na+ salts of SO42-, F-, Cl-, NO3-, I-, and ClO4- with benzene in aqueous solutions were investigated using molecular dynamics simulations and compared with experimental Raman multivariate curve resolution (Raman-MCR) and thermodynamic results. Good agreement is found with the hydration-shell partition coefficients of salts obtained from the thermodynamic analysis and of halogen anions obtained from the Raman-MCR spectra of benzene and pyridine. Larger discrepancies between the simulation and thermodynamic cation partitioning results point to the influence of counter-ion interaction on cation partitioning.

  11. Removal of a hazardous heavy metal from aqueous solution using functionalized graphene and boron nitride nanosheets: Insights from simulations.

    PubMed

    Azamat, Jafar; Sattary, Batoul Shirforush; Khataee, Alireza; Joo, Sang Woo

    2015-09-01

    A computer simulation was performed to investigate the removal of Zn(2+) as a heavy metal from aqueous solution using the functionalized pore of a graphene nanosheet and boron nitride nanosheet (BNNS). The simulated systems were comprised of a graphene nanosheet or BNNS with a functionalized pore containing an aqueous ionic solution of zinc chloride. In order to remove heavy metal from an aqueous solution using the functionalized pore of a graphene nanosheet and BNNS, an external voltage was applied along the z-axis of the simulated box. For the selective removal of zinc ions, the pores of graphene and BNNS were functionalized by passivating each atom at the pore edge with appropriate atoms. For complete analysis systems, we calculated the potential of the mean force of ions, the radial distribution function of ion-water, the residence time of ions, the hydrogen bond, and the autocorrelation function of the hydrogen bond. PMID:26186492

  12. 77 FR 58416 - Comparative Environmental Evaluation of Alternatives for Handling Low-Level Radioactive Waste...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-20

    ... Spent Ion Exchange Resins From Commercial Nuclear Power Plants AGENCY: Nuclear Regulatory Commission... Environmental Evaluation of Alternatives for Handling Low-Level Radioactive Waste Spent Ion Exchange Resins from... Comparative Environmental Evaluation of Alternatives for Handling Low-Level Radioactive Waste Spent...

  13. 18th U.S. Department of Energy Low-Level Radioactive Waste Management Conference. Program

    SciTech Connect

    1997-05-20

    This conference explored the latest developments in low-level radioactive waste management through presentations from professionals in both the public and the private sectors and special guests. The conference included two continuing education seminars, a workshop, exhibits, and a tour of Envirocare of Utah, Inc., one of America's three commercial low-level radioactive waste depositories.

  14. Detritiation of low-level aqueous waste by Combined Electrolysis Catalytic Exchange

    SciTech Connect

    Rogers, M.L.

    1982-01-01

    The Combined Electrolysis Catalytic Exchange (CECE) technology is, at present, the only viable means for removing tritium from low level aqueous waste. The CECE process will be described and the results of experimentation at Mound will be discussed. Several specific low level applications that might benefit from this technology will be outlined. 4 figures, 1 table.

  15. 76 FR 20840 - Medical Devices; General and Plastic Surgery Devices; Classification of the Low Level Laser...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-14

    ... Devices; Classification of the Low Level Laser System for Aesthetic Use AGENCY: Food and Drug... level laser system for aesthetic use into class II (special controls). The special control(s) that will apply to the device is entitled ``Class II Special Controls Guidance Document: Low Level Laser...

  16. Saltstone: cement-based waste form for disposal of Savannah River Plant low-level radioactive salt waste

    SciTech Connect

    Langton, C.A.

    1984-01-01

    Defense waste processing at the Savannah River Plant will include decontamination and disposal of approximately 400 million liters of waste containing NaNO/sub 3/, NaOH, Na/sub 2/SO/sub 4/, and NaNO/sub 2/. After decontamination, the salt solution is classified as low-level waste. A cement-based waste form, saltstone, has been designed for disposal of Savannah River Plant low-level radioactive salt waste. Bulk properties of this material have been tailored with respect to salt leach rate, permeability, and compressive strength. Microstructure and mineralogy of leached and unleached specimens were characterized by SEM and x-ray diffraction analyses. The disposal system for the DWPF salt waste includes reconstitution of the crystallized salt as a solution containing 32 wt % solids. This solution will be decontaminated to remove /sup 137/Cs and /sup 90/Sr and then stabilized in a cement-based waste form. Laboratory and field tests indicate that this stabilization process greatly reduces the mobility of all of the waste constitutents in the surface and near-surface environment. Engineered trenches for subsurface burial of the saltstone have been designed to ensure compatibility between the waste form and the environment. The total disposal sytem, saltstone-trench-surrounding soil, has been designed to contain radionuclides, Cr, and Hg by both physical encapsulation and chemical fixation mechanisms. Physical encapsulation of the salts is the mechanism employed for controlling N and OH releases. In this way, final disposal of the SRP low-level waste can be achieved and the quality of the groundwater at the perimeter of the disposal site meets EPA drinking water standards.

  17. Low-level waste disposal - Grout issue and alternative waste form technology

    SciTech Connect

    Epstein, J.L.; Westski, J.H. Jr.

    1993-02-01

    Based on the Record of Decision (1) for the Hanford Defense Waste Environmental Impact Statement (HDW-EIS) (2), the US Department of Energy (DOE) is planning to dispose of the low-level fraction of double-shell tank (DST) waste by solidifying the liquid waste as a cement-based grout placed in near-surface, reinforced, lined concrete vaults at the Hanford Site. In 1989, the Hanford Grout Disposal Program (HGDP) completed a full-scale demonstration campaign by successfully grouting 3,800 cubic meters (1 million gallons) of low radioactivity, nonhazardous, phosphate/sulfate waste (PSW), mainly decontamination solution from N Reactor. The HGDP is now preparing for restart of the facility to grout a higher level activity, mixed waste double-shell slurry feed (DSSF). This greater radionuclide and hazardous waste content has resulted in a number of issues confronting the disposal system and the program. This paper will present a brief summary of the Grout Treatment Facility`s components and features and will provide a status of the HGDP, concentrating on the major issues and challenges resulting from the higher radionuclide and hazardous content of the waste. The following major issues will be discussed: Formulation (cementitious mix) development; the Performance Assessment (PA) (3) to show compliance of the disposal system to long-term environmental protection objectives; and the impacts of grouting on waste volume projections and tank space needs.

  18. Code System for Performance Assessment Ground-water Analysis for Low-level Nuclear Waste.

    Energy Science and Technology Software Center (ESTSC)

    1994-02-09

    Version 00 The PAGAN code system is a part of the performance assessment methodology developed for use by the U. S. Nuclear Regulatory Commission in evaluating license applications for low-level waste disposal facilities. In this methodology, PAGAN is used as one candidate approach for analysis of the ground-water pathway. PAGAN, Version 1.1 has the capability to model the source term, vadose-zone transport, and aquifer transport of radionuclides from a waste disposal unit. It combines themore » two codes SURFACE and DISPERSE which are used as semi-analytical solutions to the convective-dispersion equation. This system uses menu driven input/out for implementing a simple ground-water transport analysis and incorporates statistical uncertainty functions for handling data uncertainties. The output from PAGAN includes a time- and location-dependent radionuclide concentration at a well in the aquifer, or a time- and location-dependent radionuclide flux into a surface-water body.« less

  19. Plasma Hearth Process vitrification of DOE low-level mixed waste

    SciTech Connect

    Gillins, R.L.; Geimer, R.M.

    1995-11-01

    The Plasma Hearth Process (PHP) demonstration project is one of the key technology projects in the Department of Energy (DOE) Office of Technology Development Mixed Waste Focus Area. The PHP is recognized as one of the more promising solutions to DOE`s mixed waste treatment needs, with potential application in the treatment of a wide variety of DOE mixed wastes. The PHP is a high temperature vitrification process using a plasma arc torch in a stationary, refractory lined chamber that destroys organics and stabilizes the residuals in a nonleaching, vitrified waste form. This technology will be equally applicable to low-level mixed wastes generated by nuclear utilities. The final waste form will be volume reduced to the maximum extent practical, because all organics will have been destroyed and the inorganics will be in a high-density, low void-space form and little or no volume-increasing glass makers will have been added. Low volume and high integrity waste forms result in low disposal costs. This project is structured to ensure that the plasma technology can be successfully employed in radioactive service. The PHP technology will be developed into a production system through a sequence of tests on several test units, both non-radioactive and radioactive. As the final step, a prototype PHP system will be constructed for full-scale radioactive waste treatment demonstration.

  20. Tritium migration from a low-level radioactive-waste disposal site near Chicago, Illinois

    USGS Publications Warehouse

    Nicholas, J.R.; Healy, R.W.

    1988-01-01

    This paper describes the results of a study to determine the geologic and hydrologic factors that control migration of tritium from a closed, low-level radioactive-waste disposal site. The disposal site, which operated from 1943 to mid1949, contains waste generated by research activities at the world's first nuclear reactors. Tritium has migrated horizontally at least 1,300 feet northward in glacial drift and more than 650 feet in the underlying dolomite. Thin, gently sloping sand layers in an otherwise clayey glacial drift are major conduits for ground-water flow and tritium migration in a perched zone beneath the disposal site. Tritium concentrations in the drift beneath the disposal site exceed 100,000 nanocuries per liter. Regional horizontal joints in the dolomite are enlarged by solution and are the major conduits for ground-water flow and tritium migration in the dolomite. A weathered zone at the top of the dolomite also is a pathway for tritium migration. The maximum measured tritium concentration in the dolomite is 29.4 nanocuries per liter. Fluctuations of tritium concentration in the dolomite are the result of dilution by seasonal recharge from the drift.