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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. Cement solidification of simulated off-gas condensates from vitrification of low-level nuclear waste solutions.

    PubMed

    Katz, A; Brough, A R; Kirkpatrick, R J; Struble, L J; Sun, G K; Young, J F

    2001-01-01

    Solidification in a cementitious matrix is a viable alternative for low-level nuclear waste management; it is therefore important to understand the behavior and properties of such wasteforms. We have examined the cementitious solidification of simulated off-gas waste streams resulting from the vitrification of low-level nuclear waste. Different possible methods for scrubbing the off-gasses from a vitrifier give rise to three possible types of waste compositions: acidic (from aqueous dissolution of volatile NOx and POx carried over from the vitrifier), basic (from neutralizing the former with sodium hydroxide), and fully carbonated (arising from a direct-combustion vitrifier). Six binder compositions were tested in which ordinary Portland cement was replaced at different proportions by fly ash and/or ground granulated blast furnace slag. A high solution to binder ratio of 1l/1 kg was used to minimize the volume of the wasteform and 10% attapulgite clay was added to all mixes to ensure that the fresh mix did not segregate prior to setting. The 28-day compressive strengths decreased when a high proportion of cement was replaced with fly ash, but were increased significantly when the cement was replaced with slag. The heats of hydration at early age for the various solids compositions decreased when cement was replaced with either fly ash or slag; however, for the fly ash mix the low heat was also associated with a significant decrease in compressive strength. High curing temperature (60 degrees C) or the use of extra-fine slag did not significantly affect the compressive strength. Recommendations for choice of binder formulations and treatment of off-gas condensates are discussed.

  3. 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.

  4. Simulating Roll Clouds associated with Low-Level Convergence.

    NASA Astrophysics Data System (ADS)

    Prasad, A. A.; Sherwood, S. C.

    2015-12-01

    Convective initiation often takes place when features such as fronts and/or rolls collide, merge or otherwise meet. Rolls indicate boundary layer convergence and may initiate thunderstorms. These are often seen in satellite and radar imagery prior to the onset of deep convection. However, links between convergence driven rolls and convection are poor in global models. The poor representation of convection is the source of many model biases, especially over the Maritime Continent in the Tropics. We simulate low-level convergence lines over north-eastern Australia using the Weather Research and Forecasting (WRF) Model (version 3.7). The simulations are events from September-October 2002 driven by sea breeze circulations. Cloud lines associated with bore-waves that form along the low-level convergence lines are thoroughly investigated in this study with comparisons from satellite and surface observations. Initial simulations for a series of cloud lines observed on 4th October, 2002 over the Gulf of Carpentaria showed greater agreement in the timing and propagation of the disturbance and the low-level convergence, however the cloud lines or streets of roll clouds were not properly captured by the model. Results from a number of WRF simulations with different microphysics, cumulus and planetary boundary layer schemes, resolution and boundary conditions will also be discussed.

  5. Low-level tank waste simulant data base

    SciTech Connect

    Lokken, R.O.

    1996-04-01

    The majority of defense wastes generated from reprocessing spent N- Reactor fuel at Hanford are stored in underground Double-shell Tanks (DST) and in older Single-Shell Tanks (SST) in the form of liquids, slurries, sludges, and salt cakes. The tank waste remediation System (TWRS) Program has the responsibility of safely managing and immobilizing these tank wastes for disposal. This report discusses three principle topics: the need for and basis for selecting target or reference LLW simulants, tanks waste analyses and simulants that have been defined, developed, and used for the GDP and activities in support of preparing and characterizing simulants for the current LLW vitrification project. The procedures and the data that were generated to characterized the LLW vitrification simulants were reported and are presented in this report. The final section of this report addresses the applicability of the data to the current program and presents recommendations for additional data needs including characterization and simulant compositional variability studies.

  6. The simulation of natural low level light under lab's condition

    NASA Astrophysics Data System (ADS)

    Lin, Wanyi; Wang, Jinsong; Wang, Xuan; An, Zhiyong; Jiang, Hong

    2014-02-01

    Considering the needs of glimmer night vision system experiment, this paper has analyzed the working environment of glimmer night vision system, and based on this analysis the paper adopted double integrating sphere and collimator to simulate natural shimmer environment under the laboratory condition. By further analysis, we can conclude that as long as the field of collimator is larger than the field of night vision system, the natural micro light of night vision system testing can be simulated under the laboratory conditions, And the feasibility of this method is verified by experiment.

  7. 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.

  8. 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.

  9. Separation of strontium from low level radioactive waste solutions using hydrous manganese dioxide composite materials

    NASA Astrophysics Data System (ADS)

    Valsala, T. P.; Joseph, Annie; Sonar, N. L.; Sonavane, M. S.; Shah, J. G.; Raj, Kanwar; Venugopal, V.

    2010-09-01

    90Sr is one of the major isotopes present in the low level radioactive liquid waste (LLW) generated during operation of nuclear reactors and spent fuel reprocessing plants. A composite ion exchange material consisting of hydrous manganese oxide and poly methyl methacrylate (PMMA) was developed for removal of strontium from aqueous radioactive waste. The prepared composite material showed very good strontium adsorption properties in aqueous solutions. Sorption of strontium on the composite material as a function of pH, equilibration time and strontium ion concentrations were studied. The process of sorption of strontium from solution was analysed using different isotherm models like Langmuir, D-R and Freundlich. Four different error functions were employed to find out the most suitable isotherm model to represent the experimental data and it was found that Freundlich model best fits the sorption of strontium on the composite material. Analysis of the data obtained from the sorption kinetics studies showed that the data fitted better to the pseudo-second order kinetic model. Lab scale column performance study of the composite material revealed that the material could be effectively used in column operations to remove strontium from LLW solutions.

  10. Low-Level Laser Effects on Simulated Orthodontic Tension Side Periodontal Ligament Cells

    PubMed Central

    Huang, Tsui-Hsien; Liu, Shiau-Lee; Chen, Chih-Lin; Shie, Ming-You

    2013-01-01

    Abstract Objective: The purpose of this study was to analyze proliferation, inflammation, and osteogenic effects on periodontal ligament (PDL) cells after low-level laser therapy (LLLT) under simulated orthodontic tension conditions. Background data: Low-level lasers affect fibroblast proliferation and collagen synthesis and reduce inflammation. Few studies have focused on the LLLT changes in the PDL caused by moving teeth. Materials and methods: A human PDL cell line was cultured in a −100 kPa tension incubator. The PDL cells were treated with a 670 nm low-level diode laser, output power of 500 mW (continuous wave modus) for 2.5 or 5 sec, spot area 0.25 cm2, corresponding to 1.25 and 2.5 J at an energy density of 5 or 10 J/cm2, respectively. PDL cell viability was assayed by detecting the ability of the cells to cleave tetrazolium salt to formazan dye. Inflammation and osteogenic markers were analyzed by Western blot analysis. Results: PDL cell viablity increased in the experimental group, based on the ability of the cells to cleave tetrazolium salt at day 7 (p<0.05). The experimental group showed no difference in PDL cellular morphology compared with the control group. The inflammation markers inducible NO synthase (iNOS), cyclooxygenase (COX)-2 and interleukin (IL)-1 showed stronger expression in 5 and 10 J/cm2 therapy at days 1 and 5, but decreased in expression at day 7. The osteogenic marker osteocalcin (OC) expression level was significantly higher at day 7 (p<0.05) than in the control cells. Conclusions: LLLT significantly increased PDL cell proliferation, decreased PDL cell inflammation, and increased PDL OC activity under the tension conditions used in this study. PMID:23327633

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Mesoscale model simulation of low level equatorial winds over Borneo during the haze episode of September 1997

    NASA Astrophysics Data System (ADS)

    Mahmud, Mastura

    2009-08-01

    The large-scale vegetation fires instigated by the local farmers during the dry period of the major El Niño event in 1997 can be considered as one of the worst environmental disasters that have occurred in southeast Asia in recent history. This study investigated the local meteorology characteristics of an equatorial environment within a domain that includes the northwestern part of Borneo from the 17 to 27 September 1997 during the height of the haze episode by utilizing a limited area three-dimensional meteorological and dispersion model, The Air Pollution Model (TAPM). Daily land and sea breeze conditions near the northwestern coast of Borneo in the state of Sarawak, Malaysia were predicted with moderate success by the index of agreement of less than one between the observed and simulated values for wind speed and a slight overprediction of 2.3 of the skill indicator that evaluates the standard deviation to the observed values. The innermost domain of study comprises an area of 24,193 km2, from approximately 109°E to 111°E, and from 1°N to 2.3°N, which includes a part of the South China Sea. Tracer analysis of air particles that were sourced in the state of Sarawak on the island of Borneo verified the existence of the landward and shoreward movements of the air during the simulation of the low level wind field. Polluted air particles were transported seawards during night-time, and landwards during daytime, highlighting the recirculation features of aged and newer air particles during the length of eleven days throughout the model simulation. Near calm conditions at low levels were simulated by the trajectory analysis from midnight to mid-day on the 22 of September 1997. Low-level turbulence within the planetary boundary layer in terms of the total kinetic energy was weak, congruent with the weak strength of low level winds that reduced the ability of the air to transport the pollutants. Statistical evaluation showed that parameters such as the systematic

  16. 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.

  17. Reduced exercise time in competitive simulations consequent to low level ozone exposure

    SciTech Connect

    Schelegle, E.S.; Adams, W.C.

    1986-08-01

    Ten highly trained endurance athletes were studied to determine the effects of exposure to low ozone (O/sub 3/) concentrations on simulated competitive endurance performance and associated physiological and subjective symptom responses. Each subject was randomly exposed to filtered air (FA), and to 0.12, 0.18, and 0.24 ppm O/sub 3/ while performing a 1 h competitive simulation protocol on a bicycle ergometer. Endurance performance was evaluated by the number of subjects unable to complete rides (last 30 min at an intense work load of approximately 86% VO/sub 2/max). All subjects completed the FA exposure, whereas one, five, and seven subjects did not complete the 0.12, 0.18, and 0.24 ppm O/sub 3/ exposures, respectively. Statistical analysis indicated a significant (P less than 0.05) increase in the inability of subjects to complete the competitive simulations with increasing O/sub 3/ concentration, including a significant difference between the 0.24 ppm O/sub 3/ and FA exposure. Significant decreases (P less than 0.05) were also observed following the 0.18 and 0.24 ppm O/sub 3/ exposures, respectively, in forced vital capacity (-7.8 and -9.9%), and forced expiratory volume in 1 s (-5.8 and -10.5%). No significant O/sub 3/ effect was observed for exercise respiratory metabolism or ventilatory pattern responses. However, the number of reported subjective symptoms increased significantly following the 0.18 and 0.24 ppm O/sub 3/ protocols. These data demonstrate significant decrements in simulated competitive endurance performance and in pulmonary function, with accompanying enhanced subjective symptoms, following exposure to low O/sub 3/ levels commonly observed in numerous metropolitan environments during the summer months.

  18. 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

  19. Electroreduction and photometric detection of low-level uranium in aqueous Purex solutions. Consolidated Fuel-Reprocessing Program

    SciTech Connect

    Bostick, D T; Strain, J E

    1983-04-01

    During proper operation of the Purex process for the recovery of uranium and plutonium from spent reactor fuel, there are only trace levels of uranium in the aqueous waste. In the event of an upset in the extraction columns the aqueous waste stream would give the first indication of breakthrough. From the standpoint of process control it would be desirable to have an in-line, real-time sensor for uranium in the aqueous waste stream. It was toward this end that this investigation was undertaken. The measurement technique that seems to provide the most sensitive method without addition of reagents appears to be the electrochemical reduction of UO{sub 2}{sup 2+} to U(IV) followed by spectral measurement. The electrochemical reduction to U(IV) increases the sensitivity by a factor of three to five and shifts the measurement wavelength to a spectral area (647 nm and 1075 nm) unaffected by fission products. Using the proposed analysis sequence it is possible to determine uranium at a level of 0.2 g/L in the presence of relatively high spectral background. This report details the electrochemical reduction of U(VI) in nitric acid solutions (0.5 M to 2.0 M) with platinum-vitreous carbon electrodes and examines the spectral behavior of U(IV) as a function of nitric acid concentration.

  20. Preparation of Simulated Waste Solutions

    SciTech Connect

    Walker, D.D.

    1999-06-08

    Waste Processing Technology personnel routinely prepare 0.5 to 10 L batches of salt solutions simulating Savannah River Site (SRS) soluble waste. This report describes the compositions and preparation methods.

  1. Solution-based direct readout surface enhanced Raman spectroscopic (SERS) detection of ultra-low levels of thiram with dogbone shaped gold nanoparticles.

    PubMed

    Saute, Benjamin; Narayanan, Radha

    2011-02-01

    We report the use of two different sizes of dogbone shaped gold nanoparticles as colloidal substrates for surface enhanced Raman spectroscopy (SERS) based detection of ultra-low levels of thiram, a dithiocarbamate fungicide. We demonstrate the ability to use a solution based, direct readout SERS method as a quantitative tool for the detection of ultra-low levels of thiram. The two different sizes of dogbone shaped gold nanoparticles are synthesized by using the seed-mediated growth method and characterized by using UV-visible spectroscopy and transmission electron microscopy (TEM). The smaller dogbone shaped nanoparticles have an average size of 43 ± 13 nm. The larger dogbone shaped gold nanoparticles have an average size of 65 ± 15 nm. The nanoparticle concentration is 1.25 × 10(11) nanoparticles per mL for the smaller dogbone shaped gold nanoparticles and is 1.13 × 10(11) nanoparticles per mL for the larger dogbone shaped gold nanoparticles. Different concentrations of thiram are allowed to bind to the two different sizes of dogbone shaped gold nanoparticles and the SERS spectra are obtained. From the calibration curve, the limit of detection for thiram is 43.9 ± 6.2 nM when the smaller dogbone shaped gold nanoparticles are used as colloidal SERS substrates In the case of the larger dogbone shaped gold nanoparticles, the limit of detection for thiram is 11.8 ± 3.2 nM. The lower limit of detection obtained by using the larger dogbone shaped gold nanoparticles as colloidal substrates is due to the lightning rod effect, higher contributions from the electromagnetic enhancement effect, and larger number of surface sites for thiram to bind.

  2. Visual cues in low-level flight - Implications for pilotage, training, simulation, and enhanced/synthetic vision systems

    NASA Technical Reports Server (NTRS)

    Foyle, David C.; Kaiser, Mary K.; Johnson, Walter W.

    1992-01-01

    This paper reviews some of the sources of visual information that are available in the out-the-window scene and describes how these visual cues are important for routine pilotage and training, as well as the development of simulator visual systems and enhanced or synthetic vision systems for aircraft cockpits. It is shown how these visual cues may change or disappear under environmental or sensor conditions, and how the visual scene can be augmented by advanced displays to capitalize on the pilot's excellent ability to extract visual information from the visual scene.

  3. 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.

  4. Structure of a microbial community in soil after prolonged addition of low levels of simulated acid rain

    PubMed

    Pennanen; Fritze; Vanhala; Kiikkila; Neuvonen; Baath

    1998-06-01

    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.

  5. 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.

  6. 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

  7. 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.

  8. Volatility and entrainment of feed components and product glass characteristics during pilot-scale vitrification of simulated Hanford site low-level waste

    SciTech Connect

    Shade, J.W.

    1996-05-03

    Commercially available melter technologies were tested for application to vitrification of Hanford site low-level waste (LLW). Testing was conducted at vendor facilities using a non-radioactive LLW simulant. Technologies tested included four Joule-heated melter types, a carbon electrode melter, a cyclone combustion melter, and a plasma torch-fired melter. A variety of samples were collected during the vendor tests and analyzed to provide data to support evaluation of the technologies. This paper describes the evaluation of melter feed component volatility and entrainment losses and product glass samples produced during the vendor tests. All vendors produced glasses that met minimum leach criteria established for the test glass formulations, although in many cases the waste oxide loading was less than intended. Entrainment was much lower in Joule-heated systems than in the combustion or plasma torch-fired systems. Volatility of alkali metals, halogens, B, Mo, and P were severe for non-Joule-heated systems. While losses of sulfur were significant for all systems, the volatility of other components was greatly reduced for some configurations of Joule-heated melters. Data on approaches to reduce NO{sub x} generation, resulting from high nitrate and nitrite content in the double-shell slurry feed, are also presented.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. 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);…

  15. 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.

  16. 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.

  17. Field observations and model simulations of low-level flows in the mid-Atlantic during August 1-5, 2006

    NASA Astrophysics Data System (ADS)

    Rabenhorst, Scott Daniel

    For years, basic mountain, sea breeze, and low-level jet (LLJ) circulations have been studied, usually in locations with a high frequency of occurrence, sharp gradients, or significant geographic prominence. However, there is evidence that similar circulations exist in non-classic locations with more mild topography and atmospheric gradients. One such understudied area is the U.S. Mid-Atlantic region. The Water Vapor Variability -- Satellite/Sondes (WAVES) 2006 field campaign provided a contiguous 5-day period of concentrated high resolution observations to examine fine-scale details of a weather pattern typical of the Mid-Atlantic summertime. These measurements presented an opportunity for an intensive modeling study to further investigate peculiar phenomena with verification against research-grade observations. The observations captured two significant events: an official LLJ and a cold front with a prefrontal trough. A pronounced diurnal cycle was revealed which can be categorized into three stages: (1) daytime growth of the planetary boundary layer (PBL), (2) flow intensification into a LLJ regime after dusk, and (3) interruption by downslope winds (DW) after midnight. The third stage is most interesting owing to the lack of literature documenting similar occurrences in the Mid-Atlantic, which can impact air quality forecasting. Prior to high resolution modeling of the case study, sensitivity studies were conducted examining four areas to which the model was believed most sensitive: (1) initial condition data, (2) cumulus schemes, (3) PBL parameterizations, and (4) initialization times. Results also revealed shortcomings in model precipitation and PBL profiles, model biases, urban anomalies, and tendencies for forecast convergence. High resolution regional modeling showed the evolution of these nocturnal events and were verified against WAVES observations. A hybrid solenoidal influenced afternoon and early evening circulation east of the mountains. Afternoon

  18. 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

  19. 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.

  20. Staggered solution procedures for multibody dynamics simulation

    NASA Astrophysics Data System (ADS)

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

    1990-04-01

    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. A simulation of the transport and fate of radon-220 derived from thorium-232 low-level waste in the near-surface zone of the Radioactive Waste Management Site in Area 5 of the Nevada Test Site

    SciTech Connect

    Lindstrom, F.T.; Cawlfield, D.E.; Donahue, M.E.; Emer, D.F.; Shott, G.J.

    1992-07-01

    US Department of Energy (DOE) Order 5820.2A (DOE, 1988) requires performance assessment of all new and existing low-level radioactive waste (LLW) disposal sites. An integral part of performance assessment is estimating the fluxes of radioactive gases such as radon-220 and radon-222. Mathematical models, which point out data needs and therefore drive site characterization, provide a logical means of performing the required flux estimations. Thorium-232 Waste, consisting largely of thorium hydroxide and thorium oxides, has been approved for disposal in shallow trenches and pits at the LLW Radioactive Waste Management Site in Area 5 of the Nevada Test Site. A sophisticated gas transport model, CASCADR8 (Lindstrom et al., 1992), was used to simulate the transport and fate of radon-220 from its source of origin nine feet below a closure cap of native soil, through the dry alluvial earth, to its point of release to the atmosphere. CASCADR8 is an M-chain gas-phase radionuclide transport and fate model. It has been tailored to the site-specific needs of the dry desert environment of southern Nevada. It is based on the mass balance principle for each radionuclide and uses gas-phase diffusion as well as barometric pressure-induced advection as its main modes of transport.

  3. A simulation of the transport and fate of radon-222 derived from thorium-230 low-level waste in the near-surface zone of the Radioactive Waste Management Site in Area 5 of the Nevada Test Site

    SciTech Connect

    Lindstrom, F.T.; Cawlfield, D.E.; Donahue, M.E.; Emer, D.F.; Shott, G.J.

    1993-12-01

    US Department of Energy (DOE) Order 5820.2A (DOE, 1988) requires performance assessments on all new and existing low-level radioactive waste (LLW) disposal sites. An integral part of performance assessment is estimating the fluxes of radioactive gases such as radon-220 and radon-222. Data needs pointed out by mathematical models drive site characterization. They provide a logical means of performing the required flux estimations. Thorium-230 waste, consisting largely of thorium hydroxide and thorium oxides, has been approved for disposal in shallow trenches and pits at the LLW Radioactive Waste Management Site in Area 5 of the Nevada Test Site. A sophisticated gas transport model, CASCADR8 (Lindstrom et al., 1992b), was used to simulate the transport and fate of radon-222 from its source of origin, nine feet below a closure cap of native soil, through the dry alluvial earth, to its point of release into the atmosphere. CASCADR8 is an M-chain gas-phase radionuclide transport and fate model. It has been tailored to the site-specific needs of the dry desert environment of southern Nevada. It is based on the mass balance principle for each radionuclide and uses gas-phase diffusion as well as barometric pressure-induced advection as its main modes of transport. CASCADR8 uses both reversible and irreversible sorption kinetic rules as well as the usual classical Bateman (1910) M-chain decay rules for its kinetic processes. Worst case radon-222 gas-phase concentrations, as well as surface fluxes, were estimated over 40 days. The maximum flux was then used in an exposure assessment model to estimate the total annual dose equivalent received by a person residing in a standard 2500-square-foot house with 10-foot walls. Results are described.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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…

  10. A case study of a low level jet during OPALE

    NASA Astrophysics Data System (ADS)

    Gallée, H.; Barral, H.; Vignon, E.; Genthon, C.

    2014-12-01

    A case study of a low level jet during the OPALE (Oxidant Production over Antarctic Land and its Export) summer campaign is presented. It has been observed at Dome C (East Antarctica) and is simulated accurately by the three-dimensional version of the Modèle Atmosphérique Régional (MAR). It is found that this low level jet is not related to an episode of thermal wind, conforting that Dome C may be a~place where turbulence on flat terrain can be studied.

  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. 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).

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  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. Disposal of low-level radioactive wastes.

    PubMed

    Hendee, W R

    1986-07-01

    The generation of low-level radioactive waste is a natural consequence of the societal uses of radioactive materials. These uses include the application of radioactive materials to the diagnosis and treatment of human disease and to research into the causes of human disease and their prevention. Currently, low level radioactive wastes are disposed of in one of three shallow land-burial disposal sites located in Washington, Nevada, and South Carolina. With the passage in December 1980 of Public Law 96-573, "The Low-Level Radioactive Waste Policy Act," the disposal of low-level wastes generated in each state was identified as a responsibility of the state. To fulfill this responsibility, states were encouraged to form interstate compacts for radioactive waste disposal. At the present time, only 37 states have entered into compact agreements, in spite of the clause in Public Law 96-573 that established January 1, 1986, as a target date for implementation of state responsibility for radioactive wastes. Recent action by Congress has resulted in postponement of the implementation date to January 1, 1993.

  19. Natural Artificial Languages: Low-Level Processes.

    ERIC Educational Resources Information Center

    Perlman, Gary

    This paper explores languages for communicating precise ideas within limited domains, which include mathematical notation and general purpose and high level computer programming languages. Low-level properties of such natural artificial languages are discussed, with emphasis on those in which names are chosen for concepts and symbols are chosen…

  20. 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.

  1. Phase behaviors of polymer solutions using molecular simulation technique.

    PubMed

    Yang, Jung Ho; Bae, Young Chan

    2008-08-14

    Phase behaviors of polymer solutions are estimated using a combination of thermodynamic models and molecular simulation technique. In general, many parameters of binary systems are determined by fitting a thermodynamic model with experimental data. In this study, we obtained all parameters using molecular simulation. To take the specific interaction into account, we assume that it only occurs between a solvent molecule and a specific group. Our results show that the theoretical treatment accounting for the specific interaction gives more accurate predictions than those without consideration of specific interaction. Also, our approach describes the phase equilibria of various polymer solutions over the entire concentration remarkably well.

  2. Computer simulation of grain growth kinetics with solute drag

    SciTech Connect

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

    1999-03-01

    The effects of solute drag on the grain growth kinetics were studied in two-dimensional (2D) 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 {ital 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 {ital 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. {copyright} {ital 1999 Materials Research Society.}

  3. 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.

  4. A digital retina-like low-level vision processor.

    PubMed

    Mertoguno, S; Bourbakis, N G

    2003-01-01

    This correspondence presents the basic design and the simulation of a low level multilayer vision processor that emulates to some degree the functional behavior of a human retina. This retina-like multilayer processor is the lower part of an autonomous self-organized vision system, called Kydon, that could be used on visually impaired people with a damaged visual cerebral cortex. The Kydon vision system, however, is not presented in this paper. The retina-like processor consists of four major layers, where each of them is an array processor based on hexagonal, autonomous processing elements that perform a certain set of low level vision tasks, such as smoothing and light adaptation, edge detection, segmentation, line recognition and region-graph generation. At each layer, the array processor is a 2D array of k/spl times/m hexagonal identical autonomous cells that simultaneously execute certain low level vision tasks. Thus, the hardware design and the simulation at the transistor level of the processing elements (PEs) of the retina-like processor and its simulated functionality with illustrative examples are provided in this paper.

  5. 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.

  6. Scalable parallel solution coupling for multi-physics reactor simulation.

    SciTech Connect

    Tautges, T. J.; Caceres, A.; Mathematics and Computer Science

    2009-01-01

    Reactor simulation depends on the coupled solution of various physics types, including neutronics, thermal/hydraulics, and structural mechanics. This paper describes the formulation and implementation of a parallel solution coupling capability being developed for reactor simulation. The coupling process consists of mesh and coupler initialization, point location, field interpolation, and field normalization. We report here our test of this capability on an example problem, namely, a reflector assembly from an advanced burner test reactor. Performance of this coupler in parallel is reasonable for the chosen problem size and range of processor counts. The runtime is dominated by startup costs, which amortize over the entire coupled simulation. Future efforts will include adding more sophisticated interpolation and normalization methods, to accommodate different numerical solvers used in various physics modules and to obtain better conservation properties for certain field types.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Solid low-level waste certification strategy

    SciTech Connect

    Smith, M.A.

    1991-08-01

    The purpose of the Solid Low-Level Waste (SLLW) Certification Program is to provide assurance that SLLW generated at the ORNL meets the applicable waste acceptance criteria for those facilities to which the waste is sent for treatment, handling, storage, or disposal. This document describes the strategy to be used for certification of SLLW or ORNL. The SLLW Certification Program applies to all ORNL operations involving the generation, shipment, handling, treatment, storage and disposal of SLLW. Mixed wastes, containing both hazardous and radioactive constituents, and transuranic wastes are not included in the scope of this document. 13 refs., 3 figs.

  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. 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.

  17. Brownian Dynamics Simulation of Protein Solutions: Structural and Dynamical Properties

    SciTech Connect

    Mereghetti, Paolo; Gabdoulline, Razif; Wade, Rebecca C.

    2010-12-01

    The study of solutions of biomacromolecules provides an important basis for understanding the behavior of many fundamental cellular processes, such as protein folding, self-assembly, biochemical reactions, and signal transduction. Here, we describe a Brownian dynamics simulation procedure and its validation for the study of the dynamic and structural properties of protein solutions. In the model used, the proteins are treated as atomically detailed rigid bodies moving in a continuum solvent. The protein-protein interaction forces are described by the sum of electrostatic interaction, electrostatic desolvation, nonpolar desolvation, and soft-core repulsion terms. The linearized Poisson-Boltzmann equation is solved to compute electrostatic terms. Simulations of homogeneous solutions of three different proteins with varying concentrations, pH, and ionic strength were performed. The results were compared to experimental data and theoretical values in terms of long-time self-diffusion coefficients, second virial coefficients, and structure factors. The results agree with the experimental trends and, in many cases, experimental values are reproduced quantitatively. There are no parameters specific to certain protein types in the interaction model, and hence the model should be applicable to the simulation of the behavior of mixtures of macromolecules in cell-like crowded environments.

  18. Primitive chain network simulations for entangled DNA solutions

    NASA Astrophysics Data System (ADS)

    Masubuchi, Yuichi; Furuichi, Kenji; Horio, Kazushi; Uneyama, Takashi; Watanabe, Hiroshi; Ianniruberto, Giovanni; Greco, Francesco; Marrucci, Giuseppe

    2009-09-01

    Molecular theories for polymer rheology are based on conformational dynamics of the polymeric chain. Hence, measurements directly related to molecular conformations appear more appealing than indirect ones obtained from rheology. In this study, primitive chain network simulations are compared to experimental data of entangled DNA solutions [Teixeira et al., Macromolecules 40, 2461 (2007)]. In addition to rheological comparisons of both linear and nonlinear viscoelasticities, a molecular extension measure obtained by Teixeira et al. through fluorescent microscopy is compared to simulations, in terms of both averages and distributions. The influence of flow on conformational distributions has never been simulated for the case of entangled polymers, and how DNA molecular individualism extends to the entangled regime is not known. The linear viscoelastic response and the viscosity growth curve in the nonlinear regime are found in good agreement with data for various DNA concentrations. Conversely, the molecular extension measure shows significant departures, even under equilibrium conditions. The reason for such discrepancies remains unknown.

  19. Molecular Dynamics Simulations of Lignin Peroxidase in Solution

    PubMed Central

    Francesca Gerini, M.; Roccatano, Danilo; Baciocchi, Enrico; Nola, Alfredo Di

    2003-01-01

    The dynamical and structural properties of lignin peroxidase and its Trp171Ala mutant have been investigated in aqueous solution using molecular dynamics (MD) simulations. In both cases, the enzyme retained its overall backbone structure and all its noncovalent interactions in the course of the MD simulations. Very interestingly, the analysis of the MD trajectories showed the presence of large fluctuations in correspondence of the residues forming the heme access channel; these movements enlarge the opening and facilitate the access of substrates to the enzyme active site. Moreover, steered molecular dynamics docking simulations have shown that lignin peroxidase natural substrate (veratryl alcohol) can easily approach the heme edge through the access channel. PMID:12770894

  20. 48-Pack low level waste storage facility

    SciTech Connect

    Bilik, T.J.

    1995-11-01

    ComEd has completed a design for a low level radioactive waste (LLW) storage facility, dubbed the {open_quotes}48-Pack{close_quotes}. The 48-Pack, so named because of its ability to hold 48 high integrity containers (HICs), is a modular, heavily shielded, concrete bunker. The facility was designed to serve as an effective means of augmenting the Company`s existing process waste storage capacity if and when the need arose. This paper identifies how ComEd addressed the potential need to supplement the storage capacity at its six nuclear stations through the development of the 48-Pack. Based on the criteria of meeting safety and regulatory requirements, low cost, short lead time for construction, universal design, and modularity, the 48-Pack concept was anticipated to meet and exceed the Company`s storage needs which were anticipated to end with the availability of a Central Midwest Compact (CMC) disposal facility.

  1. Low level counting from meteorites to neutrinos

    SciTech Connect

    Heusser, Gerd

    2005-09-08

    The development in low level counting at Heidelberg with NaI(Tl) crystals, proportional counters and Germanium detectors is reviewed throughout the course of almost 40 years of experience. Research subjects changed from cosmogenic radionuclides in meteorites to solar neutrinos and double beta decay. Driven by screening measurements for these rare event experiments, the sensitivity in single gamma counting has gained almost 3 orders of magnitude. With Ge spectrometry the {mu}Bq/kg range is now accessible. It is discussed how further improvements can be realized. There is potential to reach a sensitivity at the level of 10 to 100 nBq/kg for cryogenic liquid type Gespectroscopy, a technique which the next generation 76Ge double beta decay experiment GERDA is based on.

  2. 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.

  3. 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.

  4. Draft low level waste technical summary

    SciTech Connect

    Powell, W.J.; Benar, C.J.; Certa, P.J.; Eiholzer, C.R.; Kruger, A.A.; Norman, E.C.; Mitchell, D.E.; Penwell, D.E.; Reidel, S.P.; Shade, J.W.

    1995-09-01

    The purpose of this document is to present an outline of the Hanford Site Low-Level Waste (LLW) disposal program, what it has accomplished, what is being done, and where the program is headed. This document may be used to provide background information to personnel new to the LLW management/disposal field and to those individuals needing more information or background on an area in LLW for which they are not familiar. This document should be appropriate for outside groups that may want to learn about the program without immediately becoming immersed in the details. This document is not a program or systems engineering baseline report, and personnel should refer to more current baseline documentation for critical information.

  5. Low-level therapy in ophthalmology

    NASA Astrophysics Data System (ADS)

    Pankov, O. P.

    1999-07-01

    Extremely slow introduction of low-level laser therapy into the practice of ophthalmologists is restricted by the lack of good methodological recommendation and modern equipment adopted to the needs of ophthalmology. The most perspective is considered to be further improvement of the methods and the elaboration of the medical equipment, working in several wave bands, combined with magnetotherapy and working with the use of various modes of the modulation of the intensity of the luminous flux. It may be asserted that unlike the mode of continuous radiation, in some cases, the effectiveness of the treatment increases when the modulated light with the frequency of one to a few tens HZ is used. Moreover, the methods are being elaborated, when the modulation frequency of laser light and the biorhythms of man physiologic parameters are synchronized. Very perspective seems the computerization of the treatment process with the simultaneous electrophysiological control of the condition of visual functions.

  6. 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.

  7. Polyethylene solidification of low-level wastes

    NASA Astrophysics Data System (ADS)

    Kalb, P. D.; Colombo, P.

    1985-02-01

    The results of an investigation on the solidification of low-level radioactive waste in polyethylene are discussed. Waste streams 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.

  8. 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

  9. Purification of Simulated Neptunium Filtrate Solution by Anion Exchange

    SciTech Connect

    Crowder, Mark L.; Kyser, Edward A. III

    2007-07-01

    Full text of publication follows: Anion exchange was investigated as a means to recover and purify neptunium (Np) from solutions containing significant plutonium (Pu), sodium (Na), and manganese (Mn) impurities and a high nitrate concentration. The solution being evaluated resulted from lean filtrate and precipitator clean-out solutions which were generated during Np processing at the Savannah River Site. Prior to anion exchange, valence adjustment of the Np using ferrous sulfamate (i.e., Fe{sub 2}(SO{sub 3}NH{sub 2}){sub 2} or FS) was evaluated. For testing, a simulated filtrate solution was made with {approx}1.5 g Np/L and slightly elevated levels of impurities. Two anion exchange column runs were performed. In both runs, Np was loaded onto Reillex HPQ resin in high nitric acid (HNO{sub 3}) solution, typical for Np processing. The resin wash step differed in the two runs, but the elution step was the same. In the first column run, 12 column bed volumes (BV) of reductive or partition wash with 6.4 M nitric acid / 0.05 M FS were used. In the second run, six BV of 5 M HNO{sub 3} / 0.05 M FS were used as the reductive wash. Reported results will include Pu rejection, Np losses and decontamination factors for Na and Mn. (authors)

  10. 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.

  11. 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.

  12. 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.

  13. Molecular dynamics simulations of glycine crystal-solution interface

    NASA Astrophysics Data System (ADS)

    Banerjee, Soumik; Briesen, Heiko

    2009-11-01

    Glycine is an amino acid that has several applications in the pharmaceutical industry. Hence, growth of α-glycine crystals through solution crystallization is an important process. To gain a fundamental understanding of the seeded growth of α-glycine from aqueous solution, the (110) face of α-glycine crystal in contact with a solution of glycine in water has been simulated with molecular dynamics. The temporal change in the location of the interface of the α-glycine crystal seed has been characterized by detecting a density gradient. It is found that the α-glycine crystal dissolves with time at a progressively decreasing rate. Diffusion coefficients of glycine adjacent to (110) face of α-glycine crystal have been calculated at various temperatures (280, 285, 290, 295, and 300 K) and concentrations (3.6, 4.5, and 6.0 mol/l) and compared to that in the bulk solution. In order to gain a fundamental insight into the nature of variation in such properties at the interface and the bulk, the formation of hydrogen bonds at various temperatures and concentrations has been investigated. It is found that the nature of interaction between various atoms of glycine molecules, as characterized by radial distribution functions, can provide interesting insight into the formation of hydrogen bonds that in turn affect the diffusion coefficients at the interface.

  14. Health-promoting low level laser therapy

    NASA Astrophysics Data System (ADS)

    Yuan, Jian-Qin; Liu, Timon Cheng-Yi; Li, Jiang-Hua; Liu, Xiao-Guang; Xu, Xiao-Yang; Liu, Song-Hao

    2008-12-01

    Homeostasis is a classical concept of physiology, and will be developed into function-specific homeostasis (FSH) in this paper. FSH is a negative-feedback response of a biosystem to maintain the function-specific conditions inside the biosystem. Let Q be the quality of a FSH. A person might simultaneously have many kinds of FSH, {FSHi, i = 1, 2,... n}, and then has {Qi, i = 1, 2,...,n}. Let Qmax=max{Qi, i = 1, 2,...n}. Qmax represents the health level, and might be enhanced by training. An individual system might be classified as FSH-essential subsystems (FESs) and FSH-non-essential subsystems (FNSs) which homeostasis can be written as FESHs and FNSHs for short, respectively. The training to establish a new FSH can also be classified as extraordinary training (ET) and ordinary training (OT). ET disrupts the present FSH and establishes FESHs. OT maintains FESHs and establishes FNSHs and then a new FSH, and then maintains the new FSH. The cellular rehabilitation of low level laser irradiation or monochromatic light might promote the establishment of FESHs, FNSHs and then FSH, shorten ET or OT period and then promote health.

  15. 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.

  16. Low-level efficacy of cosmetic preservatives.

    PubMed

    Lundov, M D; Johansen, J D; Zachariae, C; Moesby, L

    2011-04-01

    Preservation using combinations of preservatives has several advantages. This study shows that the concentration of some of the most frequently used allergenic preservatives can be markedly lowered when they are combined with phenoxyethanol. The antimicrobial efficacy of cosmetic preservatives and known allergens of various potency [diazolidinyl urea, methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), methylisothiazolinone (MI) and phenoxyethanol] was tested alone and in various combinations of two or three preservatives together. The preservatives were tested for minimum inhibitory concentration (MIC) values and possible synergy using fractional inhibitory concentration. MCI/MI was the only preservative showing low-level MIC against all four tested microorganisms: Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Different combinations of the preservatives indicated additive effects against the microorganisms. No combination of preservatives showed any inhibitory action on each other. Challenge tests with different concentrations and combinations were performed in a cosmetic cream. Diazolidinyl urea and MCI/MI alone were ineffective against C. albicans in a challenge test at concentrations up to 16 times higher than the observed MIC values. When combining phenoxyethanol with either one of the allergenic preservatives diazolidinyl urea, MCI/MI or MI, the cosmetic cream was adequately preserved at concentrations well below the preservatives' MIC values as well as 10-20 times below the maximum permitted concentrations. By using combinations of preservatives, effective preservation can be achieved with lower concentrations of allergenic preservatives.

  17. 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.

  18. 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.

  19. 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

  20. Low level laser therapy on experimental myopathy

    PubMed Central

    Dávila, Soledad; Vignola, María Belén; Cremonezzi, David; Simes, Juan C.; Soriano, Fernando; Campana, Vilma R.

    2011-01-01

    Purpose: The aim of the present work was to study the effect of Helium-Neon (HeNe) and Gallium Arsenide (GaAs) laser upon nitric oxide (NO) plasma levels, an inflammatory biomarker associated with oxidative stress, in rats with experimental myopathy. These were evaluated through histological assessment. Materials and Methods: The groups studied were: (A) control (intact rats that received LLLT sham exposures), (B) rats with myopathy and sacrificed at 24 h later, (C) rats with myopathy and sacrificed 8 days later, (D) rats with myopathy and treated with HeNe laser, (E) rats with myopathy and treated with GaAs laser, (F) intact rats treated with HeNe laser and (G) intact rats treated with GaAs laser. Myopathy was induced by injecting 50μl of 1% carrageenan λ (type IV) in the left gastrocnemius muscle. Low Level Laser Therapy (LLLT) was applied with 9.5 J.cm−2 daily for 10 consecutive days with each laser. The determination of the NO was made by spectrophotometry. The muscles were stained with Hematoxylin-Eosin and examined by optic microscopy. Quantitative variables were statistically analyzed by the Fisher test, and categorical by applying Pearson's Chi Squared test at p <0.05 for all cases. Results: In groups B and C, NO was significantly increased compared to groups A, D, E, F and G (p<0.05). In group C, the percentage of area with inflammatory infiltration was significantly increased compared to the other groups (p<0.001). Conclusions: LLLT decreased plasma levels of NO in rats with experimental myopathies and significant muscle recovery. PMID:24155539

  1. Electrical properties of polarizable ionic solutions. II. Computer simulation results

    NASA Astrophysics Data System (ADS)

    Caillol, J. M.; Levesque, D.; Weis, J. J.

    1989-11-01

    We present molecular dynamics simulations for two limiting models of ionic solutions: one where the solvent molecules are polar, but nonpolarizable; the other where they are only polarizable (but have no permanent dipole moment). For both models, the static two-body correlation functions, the frequency-dependent dielectric constant and conductivity are calculated and the statistical uncertainty on these quantities estimated for molecular dynamics runs of the order of 105 integration steps. For the case of the polar solvent, the accuracy of the computed static interionic correlation functions allows a valuable test of the hypernetted chain integral equation theory at an ionic concentration of 0.04. The quantitative variation of the fluctuations of polarization and electrical current with change of boundary conditions is evaluated within the context of the second model (polarizable nonpolar solvent). Applying the relationships derived in Part I between the phenomenological coefficients and susceptibilities, it is shown that consistent values for the dielectric constant and electrical conductivity are obtained. The sum rules which generalize the Stillinger-Lovett conditions to ionic solutions are computed and shown to be satisfied in our simulations. The evaluation of these sum rules constitutes an important test of the convergence of the electrolyte system to an equilibrium state.

  2. 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.

  3. 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.

  4. 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

  5. Monte Carlo simulations of single crystals from polymer solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Jianing; Muthukumar, M.

    2007-06-01

    A novel "anisotropic aggregation" model is proposed to simulate nucleation and growth of polymer single crystals as functions of temperature and polymer concentration in dilute solutions. Prefolded chains in a dilute solution are assumed to aggregate at a seed nucleus with an anisotropic interaction by a reversible adsorption/desorption mechanism, with temperature, concentration, and seed size being the control variables. The Monte Carlo results of this model resolve the long-standing dilemma regarding the kinetic and thermal roughenings, by producing a rough-flat-rough transition in the crystal morphology with increasing temperature. It is found that the crystal growth rate varies nonlinearly with temperature and concentration without any marked transitions among any regimes of polymer crystallization kinetics. The induction time increases with decreasing the seed nucleus size, increasing temperature, or decreasing concentration. The apparent critical nucleus size is found to increase exponentially with increasing temperature or decreasing concentration, leading to a critical nucleus diagram composed in the temperature-concentration plane with three regions of different nucleation barriers: no growth, nucleation and growth, and spontaneous growth. Melting temperatures as functions of the crystal size, heating rate, and concentration are also reported. The present model, falling in the same category of small molecular crystallization with anisotropic interactions, captures most of the phenomenology of polymer crystallization in dilute solutions.

  6. 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.

  7. 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.

  8. Cobalt incorporation in calcite: thermochemistry of (Ca,Co)CO3 solid solutions from density functional theory simulations

    NASA Astrophysics Data System (ADS)

    González-López, Jorge; Ruiz-Hernández, Sergio E.; Fernández-González, Ángeles; Jiménez, Amalia; de Leeuw, Nora H.; Grau-Crespo, Ricardo

    2015-04-01

    solution. Thus, even in equilibrium with a very Co-rich aqueous solution, calcite is predicted to have a very low level of cobalt impurities, which is unfortunate as it means that Co/Ca substitution in calcite is not an effective way to immobilize Co(II) cations in solution. On the other hand, our results also mean that if spherocobaltite could be formed (which is admittedly difficult due to competition from other cobalt-bearing phases), almost perfect immobilization of the Co2+ ions would be achieved as there would be negligible Ca2+/Co2+ ion exchange with aqueous solutions.

  9. 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.

  10. 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.

  11. 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.

  12. Molecular dynamics simulations of lysozyme in water/sugar solutions

    NASA Astrophysics Data System (ADS)

    Lerbret, A.; Affouard, F.; Bordat, P.; Hédoux, A.; Guinet, Y.; Descamps, M.

    2008-04-01

    Structural and dynamical properties of the solvent at the protein/solvent interface have been investigated by molecular dynamics simulations of lysozyme in trehalose, maltose and sucrose solutions. Results are discussed in the framework of the bioprotection phenomena. The analysis of the relative concentration of water oxygen atoms around lysozyme suggests that lysozyme is preferentially hydrated. When comparing the three sugars, trehalose is seen more excluded than maltose and sucrose. The preferential exclusion of sugars from the protein surface induces some differences in the behavior of trehalose and maltose, particularly at 50 and 60 wt% concentrations, that are not observed experimentally in binary sugar/mixtures. The dynamical slowing down of the solvent is suggested to mainly arise from the homogeneity of the water/sugar matrices controlled by the percolation of the sugar hydrogen bonds networks. Furthermore, lysozyme strongly increases relaxation times of solvent molecules at the protein/solvent interface.

  13. Effective interactions in molecular dynamics simulations of lysozyme solutions

    NASA Astrophysics Data System (ADS)

    Pellicane, Giuseppe; Sarkisov, Lev

    2014-09-01

    In this article we explore a problem of effective interactions between two rotationally restrained lysozyme molecules forming a crystal contact in aqueous solution. We perform non-equilibrium molecular dynamics simulations in order to estimate the interaction energy as a function of the distance between the two proteins obtained from direct application of the Jarzynski equality (JE), and compare it with that calculated by means of another non-equilibrium approach (Forward-Reverse method) and constrained force methods. The performance of the JE equality when applied to solvated protein interactions is discussed. All of the equilibrium and non-equilibrium methods show clear evidence that the potentials of mean force (PMF) are short-ranged, do not exceed few kTs, and that there is an accumulation of anions in the presence of hydrophobic surfaces.

  14. Simulation of solute transport across low-permeability barrier walls

    USGS Publications Warehouse

    Harte, P.T.; Konikow, L.F.; Hornberger, G.Z.

    2006-01-01

    Low-permeability, non-reactive barrier walls are often used to contain contaminants in an aquifer. Rates of solute transport through such barriers are typically many orders of magnitude slower than rates through the aquifer. Nevertheless, the success of remedial actions may be sensitive to these low rates of transport. Two numerical simulation methods for representing low-permeability barriers in a finite-difference groundwater-flow and transport model were tested. In the first method, the hydraulic properties of the barrier were represented directly on grid cells and in the second method, the intercell hydraulic-conductance values were adjusted to approximate the reduction in horizontal flow, allowing use of a coarser and computationally efficient grid. The alternative methods were tested and evaluated on the basis of hypothetical test problems and a field case involving tetrachloroethylene (PCE) contamination at a Superfund site in New Hampshire. For all cases, advective transport across the barrier was negligible, but preexisting numerical approaches to calculate dispersion yielded dispersive fluxes that were greater than expected. A transport model (MODFLOW-GWT) was modified to (1) allow different dispersive and diffusive properties to be assigned to the barrier than the adjacent aquifer and (2) more accurately calculate dispersion from concentration gradients and solute fluxes near barriers. The new approach yields reasonable and accurate concentrations for the test cases. ?? 2006.

  15. Simulation of solute transport across low-permeability barrier walls.

    PubMed

    Harte, Philip T; Konikow, Leonard F; Hornberger, George Z

    2006-05-30

    Low-permeability, non-reactive barrier walls are often used to contain contaminants in an aquifer. Rates of solute transport through such barriers are typically many orders of magnitude slower than rates through the aquifer. Nevertheless, the success of remedial actions may be sensitive to these low rates of transport. Two numerical simulation methods for representing low-permeability barriers in a finite-difference groundwater-flow and transport model were tested. In the first method, the hydraulic properties of the barrier were represented directly on grid cells and in the second method, the intercell hydraulic-conductance values were adjusted to approximate the reduction in horizontal flow, allowing use of a coarser and computationally efficient grid. The alternative methods were tested and evaluated on the basis of hypothetical test problems and a field case involving tetrachloroethylene (PCE) contamination at a Superfund site in New Hampshire. For all cases, advective transport across the barrier was negligible, but preexisting numerical approaches to calculate dispersion yielded dispersive fluxes that were greater than expected. A transport model (MODFLOW-GWT) was modified to (1) allow different dispersive and diffusive properties to be assigned to the barrier than the adjacent aquifer and (2) more accurately calculate dispersion from concentration gradients and solute fluxes near barriers. The new approach yields reasonable and accurate concentrations for the test cases.

  16. The structure of aqueous sodium hydroxide solutions: a combined solution x-ray diffraction and simulation study.

    PubMed

    Megyes, Tünde; Bálint, Szabolcs; Grósz, Tamás; Radnai, Tamás; Bakó, Imre; Sipos, Pál

    2008-01-28

    To determine the structure of aqueous sodium hydroxide solutions, results obtained from x-ray diffraction and computer simulation (molecular dynamics and Car-Parrinello) have been compared. The capabilities and limitations of the methods in describing the solution structure are discussed. For the solutions studied, diffraction methods were found to perform very well in describing the hydration spheres of the sodium ion and yield structural information on the anion's hydration structure. Classical molecular dynamics simulations were not able to correctly describe the bulk structure of these solutions. However, Car-Parrinello simulation proved to be a suitable tool in the detailed interpretation of the hydration sphere of ions and bulk structure of solutions. The results of Car-Parrinello simulations were compared with the findings of diffraction experiments.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Synthetic vision for rotorcraft: low level flight

    NASA Astrophysics Data System (ADS)

    Szoboszlay, Zoltan; Jennings, Chad; Tiana, Carlo

    2006-05-01

    Two topics are discussed in this paper. The first is the Integrated Multi-sensor Synthetic Imagery System (IMSIS), being developed under an Army SBIR contract. The system updates on-board, pre-stored, terrain elevation data with 3D terrain elevation sensor data (such as radar). The system also merges 2D image contrast sensor data (such as infrared imagery) with the updated 3D terrain elevation data to render a synthetic image of the terrain on the rotorcraft pilot's display. The second topic is the testing of a new flight path marker, to show the pilot the predicted location of the aircraft with respect to the synthetic terrain (at 100m distance), as well as the predicted height above the terrain, the desired height above the terrain, and the point on the terrain the aircraft is expected to fly over. The Altitude and ground Track Predicting Flight Path Marker (ATP-FPM) symbol takes advantage of knowledge of terrain elevations ahead of the aircraft from a synthetic vision system, such as IMSIS. In simulation, the maximum low altitude error and maximum ground track error were both reduced by a factor of 2 with the ATP-FPM compared to the traditional instantaneous flight path marker. Pilot-to-pilot variations in performance were reduced and workload decreased with the ATP-FPM.

  2. 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)

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

    USGS Publications Warehouse

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

    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. 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.

  5. 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.

  6. Disposal of low-level and mixed low-level radioactive waste during 1990

    SciTech Connect

    Not Available

    1993-08-01

    Isotopic inventories and other data are presented for low-level radioactive waste (LLW) and mixed LLW disposed (and occasionally stored) during calendar year 1990 at commercial disposal facilities and Department of Energy (DOE) sites. Detailed isotopic information is presented for the three commercial disposal facilities located near Barnwell, SC, Richland, WA, and Beatty, NV. Less information is presented for the Envirocare disposal facility located near Clive, UT, and for LLW stored during 1990 at the West Valley site. DOE disposal information is included for the Savannah River Site (including the saltstone facility), Nevada Test Site, Los Alamos National Laboratory, Idaho National Engineering Laboratory, Hanford Site, Y-12 Site, and Oak Ridge National Laboratory. Summary information is presented about stored DOE LLW. Suggestions are made about improving LLW disposal data.

  7. Electrolytic decontamination of metal low level waste (LLW) and mixed low level waste (MLLW)

    SciTech Connect

    1998-11-01

    Metal objects resulting from ER activities were decontaminated using electrolytic methods. The project involved about 500 kg of ballistic test projectiles, 23 augers and drill heads, and 50 pieces of shrapnel containing lead. All objects were free-released and either reclaimed as scrap metal or reused. Electrolytic decontamination was proven to be an effective method to decontaminate metal waste objects to free-release standards. A cost analysis showed the process to be economical, especially when applied to decontamination of mixed waste, TRU waste, or when the recovered materials could be reused or recycled. The cost of decontamination of scrap iron is approximately equal to the cost of its land disposal as low level waste.

  8. Multiscale theory in the molecular simulation of electrolyte solutions.

    PubMed

    Zhang, W; You, X; Pratt, L R

    2014-07-17

    To define a role for AIMD simulation on the limited time and space scales accessible to those demanding methods, this paper organizes McMillan-Mayer theory, the potential distribution approach, and quasi-chemical theory to provide theory for the thermodynamic effects associated with long-length scales. The theory treats composition fluctuations that would be accessed by larger-scale calculations, and also longer-ranged interactions that are of special interest for electrolyte solutions. The quasi-chemical organization breaks-up governing free energies into physically distinct contributions: packing, outer-shell, and chemical contributions. Here we study specifically the outer-shell contributions that express electrolyte screening. For that purpose we adopt a primitive model suggested by observation of ion-pairing in tetraethylammonium tetrafluoroborate dissolved in propylene carbonate. Gaussian statistical models are shown to be effective physical models for outer-shell contributions, and they are conclusive for the free energies within the quasi-chemical formulation. With the present data set the Gaussian physical approximation obtains more accurate mean activity coefficients than does the Bennett direct evaluation of that free energy.

  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. Solution structures of rat amylin peptide: simulation, theory, and experiment.

    PubMed

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

    2010-02-01

    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 alpha-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 alpha-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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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)

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. 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).

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. Managing low-level radioactive wastes: a proposed approach

    SciTech Connect

    Not Available

    1980-08-01

    This document is a consensus report of the Low-Level Waste Strategy Task Force. It covers system-wide issues; generation, treatment, and packaging; transportation; and disposal. Recommendations are made. (DLC)

  1. Bibliographic Data on Low-Level Radioactive Waste Documents

    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.

  2. 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.

  3. A case study of a low-level jet during OPALE

    NASA Astrophysics Data System (ADS)

    Gallée, H.; Barral, H.; Vignon, E.; Genthon, C.

    2015-06-01

    A case study of a low-level jet (LLJ) during the OPALE (Oxidant Production over Antarctic Land and its Export) summer campaign is presented. It has been observed at Dome C (East Antarctica) and is simulated accurately by the three-dimensional version of the Modèle Atmosphérique Régional (MAR). It is found that this low-level jet is not related to an episode of thermal wind, suggesting that Dome C may be a place where turbulence on flat terrain can be studied.

  4. 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.

  5. 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)

  6. Low-Level Radioactive Waste temporary storage issues

    SciTech Connect

    Not Available

    1992-04-01

    The Low-Level Radioactive Waste Policy Act of 1980 gave responsibility for the disposal of commercially generated low-level radioactive waste to the States. The Low-Level Radioactive Waste Policy Amendments Act of 1985 attached additional requirements for specific State milestones. Compact regions were formed and host States selected to establish disposal facilities for the waste generated within their borders. As a result of the Low-Level Radioactive Waste Policy Amendments Act of 1985, the existing low-level radioactive waste disposal sites will close at the end of 1992; the only exception is the Richland, Washington, site, which will remain open to the Northwest Compact region only. All host States are required to provide for disposal of low-level radioactive waste by January 1, 1996. States also have the option of taking title to the waste after January 1, 1993, or taking title by default on January 1, 1996. Low-level radioactive waste disposal will not be available to most States on January 1, 1993. The most viable option between that date and the time disposal is available is storage. Several options for storage can be considered. In some cases, a finite storage time will be permitted by the Nuclear Regulatory Commission at the generator site, not to exceed five years. If disposal is not available within that time frame, other options must be considered. There are several options that include some form of extension for storage at the generator site, moving the waste to an existing storage site, or establishing a new storage facility. Each of these options will include differing issues specific to the type of storage sought.

  7. Brownian dynamics simulations of nanosheet solutions under shear.

    PubMed

    Xu, Yueyi; Green, Micah J

    2014-07-14

    The flow-induced conformation dynamics of nanosheets are simulated using a Brownian Dynamics (BD) formulation applied to a bead-rod sheetlike molecular model. This is the first-ever use of BD to simulate flow-induced dynamics of two-dimensional structures. Using this framework, we simulate dilute suspensions of coarse-grained nanosheets and compute conformation dynamics for simple shear flow. The data show power law scaling relationships between nanosheet parameters (such as bending moduli and molecular weight) and the resulting intrinsic viscosity and conformation. For nonzero bending moduli, an effective dimension of 2.77 at equilibrium is calculated from the scaling relationship between radius of gyration and molecular weight. We also find that intrinsic viscosity varies with molecular weight with an exponent of 2.12 ± 0.23; this dependence is significantly larger than those found for linear polymers. Weak shear thinning is observed at high Weissenberg number (Wi). This simulation method provides a computational basis for developing manufacturing processes for nanosheet-derived materials by relating flow forces and nanosheet parameters to the resulting material morphology.

  8. 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.

  9. 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.

  10. 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.

  11. Low-level radioactive waste: Gamma rays in the garbage

    SciTech Connect

    Saleska, S. )

    1990-04-01

    Of the four categories of radioactive waste (uranium mill tailings, high-level waste, transuranic, and low-level), the last term, low-level, proves to be the most misleading. The author suggests that a better term for this category would be miscellaneous radioactive junk, since it is by definition everything not included in the other three categories. Ted Taylor, a New York State resident and physicist and former nuclear weapons designer, points out that this category includes such intensely radioactive materials as reactor components that would deliver in a few minutes a lethal dose of gamma rays to anyone standing nearby. It is pointed out that of the original 6 low-level radioactive waste disposal sites, only 3 are still operating and two of those are slated to be closed in 1993 when they will be full. Unquestionably, new standards and policies are needed to deal sensibly with the problem; these are discussed briefly. 9 refs.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Development of a low-level (37)Ar calibration standard.

    PubMed

    Williams, R M; Aalseth, C E; Bowyer, T W; Day, A R; Fuller, E S; Haas, D A; Hayes, J C; Hoppe, E W; Humble, P H; Keillor, M E; LaFerriere, B D; Mace, E K; McIntyre, J I; Miley, H S; Myers, A W; Orrell, J L; Overman, C T; Panisko, M E; Seifert, A

    2016-03-01

    Argon-37 is an environmental signature of an underground nuclear explosion. Producing and quantifying low-level (37)Ar standards is an important step in the development of sensitive field measurement instruments. This paper describes progress at Pacific Northwest National Laboratory in developing a process to generate and quantify low-level (37)Ar standards, which can be used to calibrate sensitive field systems at activities consistent with soil background levels. This paper presents a discussion of the measurement analysis, along with assumptions and uncertainty estimates. PMID:26701655

  18. 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.

  19. 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.

  20. Model Evaluation for Low-Level Cloud Feedback

    NASA Astrophysics Data System (ADS)

    Shin, S.-H.

    2012-04-01

    , we give a courteous answer to the question of whether low-level clouds act as a positive or negative feedback to climate change.

  1. 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.

  2. A novel solution for LED wall lamp design and simulation

    NASA Astrophysics Data System (ADS)

    Ge, Rui; Hong, Weibin; Li, Kuangqi; Liang, Pengxiang; Zhao, Fuli

    2014-11-01

    The model of the wall washer lamp and the practical illumination application have been established with a new design of the lens to meet the uniform illumination demand for wall washer lamp based on the Lambertian light sources. Our secondary optical design of freeform surface lens to LED wall washer lamp based on the conservation law of energy and Snell's law can improve the lighting effects as a uniform illumination. With the relationship between the surface of the lens and the surface of the target, a great number of discrete points of the freeform profile curve were obtained through the iterative method. After importing the data into our modeling program, the optical entity was obtained. Finally, to verify the feasibility of the algorithm, the model was simulated by specialized software, with both the LED Lambertian point source and LED panel source model.

  3. 60. VIEW OF LOW LEVEL CHECK STATION ON THE ARIZONA ...

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

    60. VIEW OF LOW LEVEL CHECK STATION ON THE ARIZONA CANAL, NEAR THE DEER VALLEY TREATMENT PLANT, LOOKING WEST. THE ARIZONA CANAL DIVERSION CHANNEL IS VISIBLE ON THE RIGHT SIDE OF THE PHOTOGRAPH Photographer: James Eastwood, July 1990 - Arizona Canal, North of Salt River, Phoenix, Maricopa County, AZ

  4. 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.

  5. 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)

  6. Low-level waste vitrification contact maintenance viability study

    SciTech Connect

    Leach, C.E., Westinghouse Hanford

    1996-07-12

    This study investigates the economic viability of contact maintenance in the Low-Level Waste Vitrification Facility, which is part of the Hanford Site Tank Waste Remediation System. This document was prepared by Flour Daniel, Inc., and transmitted to Westinghouse Hanford Company in September 1995.

  7. Low Level Lead Toxicity: The Hidden Challenge for Educators.

    ERIC Educational Resources Information Center

    McCabe, Patrick P.

    1991-01-01

    Discusses the widespread problem of low level lead toxicity and how it affects young children's behavior and learning ability. Discusses what medical and environmental measures can be taken to remedy the problem. Briefly notes what role states have taken. Also suggests actions early childhood teachers can take to remedy the problem. (BB)

  8. Advanced Academic Skills in the Low-Level ESL Class.

    ERIC Educational Resources Information Center

    Pearson, Christine R.

    1981-01-01

    Suggests and gives examples of how a few advanced skills and concepts are related to successful reading and writing and can be introduced in low-level ESL classes. Examples include generality-specificity distinction, relevance-irrelevance distinction, underlining and making notes, paraphrasing, and summarizing. This conceptually integrated…

  9. Low-Level Violence: A Neglected Aspect of School Culture.

    ERIC Educational Resources Information Center

    Dupper, David R.; Meyer-Adams, Nancy

    2002-01-01

    Examines the extent of low-level violence in public schools and its impact on school performance, asserting that the way to reduce such violence is to create a more positive school culture and climate. Guidelines for preventing or minimizing such violence at school are presented. (SM)

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Monte Carlo simulations of Fe-Cr solid solution

    NASA Astrophysics Data System (ADS)

    Lavrentiev, Mikhail Yu.; Nguyen-Manh, Duc; Drautz, Ralf; Klaver, Peter; Dudarev, Sergei L.

    2007-12-01

    Iron-chromium alloys are characterised by a complex phase diagram, the small negative heat of formation at low Cr concentrations in bcc α-structure of Fe and by the inversion of short-range order parameter. We present Monte Carlo simulations of Fe-Cr alloy based on cluster expansion (CE) approximation for the enthalpy of the system. The set of cluster expansion coefficients is validated versus the DFT results on small clusters in bcc structure. The enthalpy of mixing is negative at small Cr concentrations up to high temperatures. Also, at small concentrations chromium atoms are well separated from each other. Clustering of Cr atoms begins at concentrations of about 10% at 800 K and 20% at 1400 K. Short-range order parameters were calculated and it was confirmed that negative values of the first and second parameters at low Cr concentrations change sign at about 10.5% Cr, in agreement with experiment. We demonstrate that complex ordering reactions in Fe-Cr and its properties may be described by 12 concentration-independent expansion coefficients.

  16. Effect of chlorides on reinforcing steel exposed to simulated concrete solutions

    SciTech Connect

    Kitowski, C.J.; Wheat, H.G.

    1997-03-01

    The behavior of steel in chloride-free and chloride-contaminated simulated concrete solutions was studied to observe the degradation of steel as a result of addition of chlorides. One of the simulated concrete solutions was a saturated calcium hydroxide (Ca[OH]{sub 2}) solution while the other was a solution made up of 0.6 M potassium hydroxide (KOH) + 0.2 M sodium hydroxide (NaOH) + 0.001 M Ca(OH){sub 2}. Corrosion behavior of the steel was studied electrochemically, and changes in the steel surfaces were studied using scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). Behavior was compared to that of reinforced concrete cylinders subjected to alternating wetting and drying in 3.5% sodium chloride (NaCl) solutions.

  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. 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.

  19. 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

  20. 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.

  1. Controlling low-level image properties: the SHINE toolbox.

    PubMed

    Willenbockel, Verena; Sadr, Javid; Fiset, Daniel; Horne, Greg O; Gosselin, Frédéric; Tanaka, James W

    2010-08-01

    Visual perception can be influenced by top-down processes related to the observer's goals and expectations, as well as by bottom-up processes related to low-level stimulus attributes, such as luminance, contrast, and spatial frequency. When using different physical stimuli across psychological conditions, one faces the problem of disentangling the contributions of low- and high-level factors. Here, we make available the SHINE (spectrum, histogram, and intensity normalization and equalization) toolbox for MATLAB, which we have found useful for controlling a number of image properties separately or simultaneously. The toolbox features functions for specifying the (rotational average of the) Fourier amplitude spectra, for normalizing and scaling mean luminance and contrast, and for exact histogram specification optimized for perceptual visual quality. SHINE can thus be employed for parametrically modifying a number of image properties or for equating them across stimuli to minimize potential low-level confounds in studies on higher level processes.

  2. Ocean dumping of low-level radioactive wastes

    NASA Astrophysics Data System (ADS)

    Templeton, W. L.

    1982-10-01

    Scientific bases, developed internationally over the last 20 years, to control and restrict to acceptable levels the resultant radiation doses that potentially could occur from the dumping of low-level radioactive wastes in the deep oceans were presented. It is concluded that present evaluations of the disposal of radioactive wastes into the oceans, coastal and deep ocean, indicate that these are being conducted within the ICRP recommended dose limits. However, there are presently no international institutions or mechanisms to deal with the long-term radiation exposure at low-levels to large numbers of people on a regional basis if not a global level. Recommendations were made to deal with these aspects through the established mechanisms of NEA/OECD and the London Dumping Convention, in cooperation with ICRP, UNSCEAR and the IAEA.

  3. 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.

  4. Immobilization of low level hazardous organics using recycled materials

    SciTech Connect

    Conner, J.R.; Smith, F.G.

    1996-12-31

    Rust Remedial Services, Inc. (RRS) recently conducted a major study on the effectiveness of additives, both virgin and recycled, in the immobilization of low-level organics in soils. Using a clean soil spiked with a mixture of hazardous organic chemicals, twelve different stabilization formulations were comparatively tested using leaching (TCLP) and total analysis (TCA) methods. TCLP reduction levels illustrated the effectiveness of the stabilization treatment on a wide variety of low level organics in contaminated soil, with the proper selection of stabilization admixtures. A specially prepared, comminuted, rubber particulate was especially effective in reducing the apparent presence of certain semi-volatile organic compounds in soil, as measured by TCA methods. Most semi-volatile organic compounds were so strongly held by the rubber particles that they were not recovered in the analytical procedure.

  5. Low level laser therapy in the treatment of aphthous ulcer.

    PubMed

    Anand, Vishal; Gulati, Minkle; Govila, Vivek; Anand, Bhargavi

    2013-01-01

    Recurrent aphthous stomatitis (RAS) is one of the most common and painful ulcerative lesions of the oral cavity, but until now no cure has been recognized for it. Two patients diagnosed with minor RAS were treated in a single sitting with low level laser therapy using 940-nm diode laser. The lesions healed completely within 3-4 days and a follow-up for 1 showed no recurrence in these patients. According to the results of this study, low level laser therapy can decrease the healing time, pain intensity, size, and recurrence of the lesion in patients with minor RAS, and hence can be considered the most appropriate treatment modality for minor RAS, with greatest clinical effectiveness.

  6. Low-level flow conditions hazardous to aircraft

    NASA Technical Reports Server (NTRS)

    Alexander, M. B.; Camp, D. W.

    1983-01-01

    Low level flow conditions known to be hazardous to aircraft during takeoff/climbout and approach/landing operations are turbulence, wind shear, and vertical motion. These conditions can and frequently do occur separately and in combinations. The identification and selection were completed of representative data cases to determine magnitude, frequency, duration, and simultaneity of occurrence of turbulence (gustiness and gust factor), wind shear (speed and direction), and vertical motion (updraft and downdraft), along with temperature inversions. New representations of temporal and spatial variations in the atmospheric boundary layer were developed. Efforts continued relative to low level flow conditions where published results imply strong vertical shear with virtually no horizontal shear and where order of magnitude analyses of the equations of motion for an aircraft illustrates that low values of horizontal shear (along the flight path) are much more hazardous than larger values of vertical wind shear (altitude).

  7. 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

  8. 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.

  9. 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)

  10. 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.

  11. 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.

  12. Department of Energy low-level radioactive waste disposal concepts

    SciTech Connect

    Ozaki, C.; Page, L.; Morreale, B.; Owens, C.

    1990-01-01

    The Department of Energy (DOE) manages its low-level waste (LLW), regulated by DOE Order 5820.2A by using an overall systems approach. This systems approach provides an improved and consistent management system for all DOE LLW waste, from generation to disposal. This paper outlines six basic disposal concepts used in the systems approach, discusses issues associated with each of the concepts, and outlines both present and future disposal concepts used at six DOE sites. 3 refs., 9 figs.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Exploding solutions of the complex two-dimensional Burgers equations: Computer simulations

    NASA Astrophysics Data System (ADS)

    Boldrighini, C.; Frigio, S.; Maponi, P.

    2012-08-01

    We study by computer simulations the complex solutions of the two-dimensional Burgers equations in the whole plane in absence of external forces. For such model the existence of singularities, corresponding to a divergence of the total energy at a finite time, is proved by Li and Sinai ["Singularities of complex-valued solutions of the two-dimensional Burgers system," J. Math. Phys. 51, 015205 (2010)], 10.1063/1.3276099 for a large class of initial data. The simulations show that the blow-up takes place in a very short time, of the order of 10-5 time units. Moreover near the blow-up time the support of the solution in Fourier space moves out to infinity along a straight line. In x-space the solutions are concentrated in a finite region, with large space derivatives, as one would expect for physical phenomena such as tornadoes.

  7. 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.

  8. Measurement and interpretation of low levels of dissolved oxygen in ground water

    USGS Publications Warehouse

    White, A.F.; Peterson, M.L.; Solbau, R.D.

    1990-01-01

    A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors

  9. 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.

  10. Melter technology evaluation for vitrification of Hanford Site low-level waste

    SciTech Connect

    Wilson, C.N.; Burgard, K.C.; Weber, E.T.; Brown, N.R.

    1995-04-01

    The current plan at the Hanford Site, in accordance with the Tri-Party Agreement among Washington State, the US Environmental Protection Agency, and the US Department of Energy, is to convert the low-level tank waste fraction into a silicate glass. The low-level waste will be composed primarily of sodium nitrate and nitrite salts concentrated in a highly alkaline aqueous solution. The capability to process up to 200 metric tons/day off glass will be established to produce an estimated 210,000 m{sup 3} for onsite disposal. A program to test and evaluate high-capacity melter technologies is in progress. Testing performed by seven different industrial sources using Joule heating, combustion, plasma, and carbon arc melters is described.

  11. Actinide extraction from simulated and irradiated spent nuclear fuel using TBP solutions in HFC-134a

    SciTech Connect

    Shadrin, A.; Babain, V.; Kamachev, V.; Murzin, A.; Shafikov, D.; Dormidonova, A.

    2008-07-01

    It was demonstrated that solutions of TBP-nitric acid adduct in liquid Freon HFC-134a (1.2 MPa, 25 deg. C) allowed for recovery of uranium with nearly the same effectiveness as supercritical CO{sub 2} at 30 MPa. At nearly quantitative recovery of U and Pu, a DF of ca. 10 can be attained on dissolution and extraction of simulated SNF samples. The possibility of recovery of actinides contained in cakes produced by oxide conversion of simulated and irradiated SNF with solutions of TBP and DBE in Freon HFC-134a was shown. (authors)

  12. Thermal Properties of Simulated and High-Level Waste Solutions Used for the Solvent Extraction Demonstration

    SciTech Connect

    Fondeur, F.F.

    2001-06-27

    Researchers measured the heat capacity and thermal conductivity of supernate from a blend of Tank 37H and 44F, of a simulant of this blend, and of a simulant specifically designed for solvent extraction experiments. The measured heat capacity of the blend from the Tanks 37H and 44F equaled 0.871 cal/(g degrees C). The simulant of this blend produced an identical result. The heat capacity of the simulant designed for solvent extraction testing equaled 0.859 cal/(g degrees C). All three solutions have thermal conductivities in the range of 0.54 to 0.6 Watts/(m degrees C). The slight variation in the thermophysical properties of these solutions successfully explains the different flowmeter readings observed during the real waste demonstration of the solvent extraction technology.

  13. 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.

  14. 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.

  15. Analytical characterization of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte

    SciTech Connect

    Montemor, M.F.; Simoes, A.M.P.; Ferreira, M.G.S.

    1998-05-01

    Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) were used to study the effect of chloride (Cl{sup {minus}}) and fly ash on behavior of the passive film formed on steel in solutions simulating the concrete interstitial electrolyte. Results showed the presence of fly ash and of Cl{sup {minus}} led to an increase in the amount of iron oxyhydroxide (FeOOH) in outer layers of the film and to an increase in the thickness and water content of the passive film. Significant differences in composition and thickness were observed between the films formed in paste solutions and in calcium hydroxide (Ca[OH]{sub 2}) solutions.

  16. 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.

  17. 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.

  18. 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).

  19. 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.

  20. 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.

  1. 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

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

    DOE PAGES

    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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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 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 study provides support for confidence

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Simulation of solute transport in a mountain pool-and-riffle stream: a transient storage model.

    USGS Publications Warehouse

    Bencala, K.E.; Walters, R.A.

    1983-01-01

    A transient storage model, which couples dead zones with the one-dimensional convection-dispersion equation, simulates the general characteristics of the solute transport behavior and a set of simulation parameters were determined that yield an adequate fit to the data. However, considerable uncertainty remains in determining physically realistic values of these parameters. The values of the simulation parameters used are compared to values used by other authors for other streams. The comparison supports, at least qualitatively, the determined parameter values. -from Authors

  13. 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…

  14. Biocorrosion properties of antibacterial Ti-10Cu sintered alloy in several simulated biological solutions.

    PubMed

    Liu, Cong; Zhang, Erlin

    2015-03-01

    Ti-10Cu sintered alloy has shown strong antibacterial properties against S. aureus and E. coli and good cell biocompatibility, which displays potential application in dental application. The corrosion behaviors of the alloy in five different simulated biological solutions have been investigated by electrochemical technology, surface observation, roughness measurement and immersion test. Five different simulated solutions were chosen to simulate oral condition, oral condition with F(-) ion, human body fluids with different pH values and blood system. It has been shown that Ti-10Cu alloy exhibits high corrosion rate in Saliva pH 3.5 solution and Saliva pH 6.8 + 0.2F solution but low corrosion rate in Hank's, Tyrode's and Saliva pH 6.8 solutions. The corrosion rate of Ti-10Cu alloy was in a order of Hank's, Tyrode's, Saliva pH 6.8, Saliva-pH 3.5 and Saliva pH 6.8 + 0.2F from slow to fast. All results indicated acid and F(-) containing conditions prompt the corrosion reaction of Ti-Cu alloy. It was suggested that the Cu ion release in the biological environments, especially in the acid and F(-) containing condition would lead to high antibacterial properties without any cell toxicity, displaying wide potential application of this alloy.

  15. 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.

  16. 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.

  17. Low level lead inhibits the human brain cation pump

    SciTech Connect

    Bertoni, J.M.; Sprenkle, P.M. )

    1991-01-01

    The impact of low level lead exposure on human central nervous system function is a major public health concern. This study addresses the inhibition of the cation pump enzyme Na,K-ATPase by low level lead. Human brain tissue was obtained at autopsy and frozen until use. Brain homogenates were preincubated with PbCl{sub 2} for 20 min at 0{degree}C. Inhibition of K-paranitrophenylphosphatase (pNPPase), a measure of the dephosphorylation step of Na,K-ATPase, reached steady state within 10 min. K-pNPPase activity, expressed as a percentage of control, fell to 96.3 {plus minus} 0.9% at 0.25 uM (PbCl{sub 2}) to 82.0 {plus minus} 1.6% at 2.5 uM (PbCl{sub 2}) in homogenates prepared from normal brain. Similar results were obtained with homogenates prepared from brains of patients with a history of alcohol abuse and of those with other miscellaneous conditions. Since the mean blood level of lead in the US has ranged recently from m9.2 to 16.0 ug/dl, these results indicate that current in vivo levels of lead exposure may impair important human brain function.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. A semi-analytical solution for simulating contaminant transport subject to chain-decay reactions.

    PubMed

    Sudicky, Edward A; Hwang, Hyoun-Tae; Illman, Walter A; Wu, Yu-Shu; Kool, Jan B; Huyakorn, Peter

    2013-01-01

    We present a set of new, semi-analytical solutions to simulate three-dimensional contaminant transport subject to first-order chain-decay reactions. The aquifer is assumed to be areally semi-infinite, but finite in thickness. The analytical solution can treat the transformation of contaminants into daughter products, leading to decay chains consisting of multiple contaminant species and various reaction pathways. The solution in its current form is capable of accounting for up to seven species and four decay levels. The complex pathways are represented by means of first-order decay and production terms, while branching ratios account for decay stoichiometry. Besides advection, dispersion, bio-chemical or radioactive decay and daughter product formation, the model also accounts for sorption of contaminants on the aquifer solid phase with each species having a different retardation factor. First-type contaminant boundary conditions are utilized at the source (x=0 m) and can be either constant-in-time for each species, or the concentration can be allowed to undergo first-order decay. The solutions are obtained by exponential Fourier, Fourier cosine and Laplace transforms. Limiting forms of the solutions can be obtained in closed form, but we evaluate the general solutions by numerically inverting the analytical solutions in exponential Fourier and Laplace transform spaces. Various cases are generated and the solutions are verified against the HydroGeoSphere numerical model.

  7. 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

  8. 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.

  9. 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

  10. Simulation of bead-and-spring chain models for semidilute polymer solutions in shear flow

    NASA Astrophysics Data System (ADS)

    Fetsko, S. W.; Cummings, P. T.

    1994-11-01

    We report preliminary results of simulations of the steady-state rheological behavior for semidilute polymer solutions of head-and-spring chain models in planar Couette now. The simulations include examination of the effects of excluded volume. hydrodynamic interactions and density. Hydrodynamic interactions are modeled by the Rotne -Prager Yamakawa tensor. The simulations are based on the nonequilibrium Brownian dynamics algorithm of Ermak and McCammon. In addition to the spring potential between neighboring beads in the chain. the interaction between any two beads in the solution is modeled using a shifted, repulsive Leonard-Jones potential. Lees Edward sliding brick boundary conditions are used for consistency with the Couette flow field.

  11. The mechanism of low levels of nitrogen dioxide reaction with unsaturated fatty acid esters

    SciTech Connect

    Gallon, A.A.

    1990-01-01

    Nitrogen dioxide is a toxic air pollutant that exists at less than 0.5 ppm in the atmosphere. This toxic compound is known to initiate autoxidation of unsaturated fatty acids both in vivo and in vitro. When autoxidation occurs in vivo, membrane damage that can lead to cell death can occur. Low concentrations of nitrogen dioxide were shown to react with the polyunsaturated fatty acid esters, methyl linoleate and methyl linoleate, by a H-abstraction mechanism. However, methyl oleate, an unsaturated fatty acid ester, was demonstrated to react with a low concentration of nitrogen dioxide by only an addition mechanism. Although methyl oleate reacts by an addition mechanism, a 50:50 molar solution of methyl oleate and methyl linoleate reacted with a low level of nitrogen dioxide exclusively by a H-abstraction mechanism. Therefore, low levels of nitrogen dioxide will probably react with polyunsaturated fatty acid components of pulmonary lipids by a H-abstraction mechanism forming nitrous acid directly in the cell membrane. Vitamin E was demonstrated to be able to act as a preventative antioxidant in the nitrogen dioxide and methyl linoleate reactions; but vitamin C could not prevent nitrogen dioxide from reacting with methyl linoleate by a H-abstraction mechanism. These results suggest that low levels of nitrogen dioxide will react with polyunsaturated fatty acids by a H-abstraction mechanism and that vitamin E can be used to prevent the reaction from occurring.

  12. 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.

  13. Fat liquefaction: effect of low-level laser energy on adipose tissue.

    PubMed

    Neira, Rodrigo; Arroyave, José; Ramirez, Hugo; Ortiz, Clara Lucía; Solarte, Efrain; Sequeda, Federico; Gutierrez, Maria Isabel

    2002-09-01

    Low-level laser energy has been increasingly used in the treatment of a broad range of conditions and has improved wound healing, reduced edema, and relieved pain of various etiologies. This study examined whether 635-nm low-level lasers had an effect on adipose tissue in vivo and the procedural implementation of lipoplasty/liposuction techniques. The experiment investigated the effect of 635-nm, 10-mW diode laser radiation with exclusive energy dispersing optics. Total energy values of 1.2 J/cm(2), 2.4 J/cm(2), and 3.6 J/cm(2) were applied on human adipose tissue taken from lipectomy samples of 12 healthy women. The tissue samples were irradiated for 0, 2, 4, and 6 minutes with and without tumescent solution and were studied using the protocols of transmission electron microscopy and scanning electron microscopy. Nonirradiated tissue samples were taken for reference. More than 180 images were recorded and professionally evaluated. All microscopic results showed that without laser exposure the normal adipose tissue appeared as a grape-shaped node. After 4 minutes of laser exposure, 80 percent of the fat was released from the adipose cells; at 6 minutes of laser exposure, 99 percent of the fat was released from the adipocyte. The released fat was collected in the interstitial space. Transmission electron microscopic images of the adipose tissue taken at x60,000 showed a transitory pore and complete deflation of the adipocytes. The low-level laser energy affected the adipose cell by causing a transitory pore in the cell membrane to open, which permitted the fat content to go from inside to outside the cell. The cells in the interstitial space and the capillaries remained intact. Low-level laser-assisted lipoplasty has a significant impact on the procedural implementation of lipoplasty techniques. PMID:12172159

  14. 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.

  15. 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.

  16. Explicit- and implicit-solvent simulations of micellization in surfactant solutions.

    PubMed

    Jusufi, Arben; Panagiotopoulos, Athanassios Z

    2015-03-24

    In this article, we focus on simulation methodologies to obtain the critical micelle concentration (cmc) and equilibrium distribution of aggregate sizes in dilute surfactant solutions. Even though it is now relatively easy to obtain micellar aggregates in simulations starting from a fully dispersed state, several major challenges remain. In particular, the characteristic times of micelle reorganization and transfer of monomers from micelles to free solution for most systems of practical interest exceed currently accessible molecular dynamics time scales for atomistic surfactant models in explicit solvent. In addition, it is impractical to simulate highly dilute systems near the cmc. We have demonstrated a strong dependence of the free surfactant concentration (frequently, but incorrectly, taken to represent the cmc in simulations) on the overall concentration for ionic surfactants. We have presented a theoretical framework for making the necessary extrapolations to the cmc. We find that currently available atomistic force fields systematically underpredict experimental cmc's, pointing to the need for the development of improved models. For strongly micellizing systems that exhibit strong hysteresis, implicit-solvent grand canonical Monte Carlo simulations represent an appealing alternative to atomistic or coarse-grained, explicit-solvent simulations. We summarize an approach that can be used to obtain quantitative, transferrable effective interactions and illustrate how this grand canonical approach can be used to interpret experimental scattering results.

  17. Oestrogen, ocular function and low-level vision: a review.

    PubMed

    Hutchinson, Claire V; Walker, James A; Davidson, Colin

    2014-11-01

    Over the past 10 years, a literature has emerged concerning the sex steroid hormone oestrogen and its role in human vision. Herein, we review evidence that oestrogen (oestradiol) levels may significantly affect ocular function and low-level vision, particularly in older females. In doing so, we have examined a number of vision-related disorders including dry eye, cataract, increased intraocular pressure, glaucoma, age-related macular degeneration and Leber's hereditary optic neuropathy. In each case, we have found oestrogen, or lack thereof, to have a role. We have also included discussion of how oestrogen-related pharmacological treatments for menopause and breast cancer can impact the pathology of the eye and a number of psychophysical aspects of vision. Finally, we have reviewed oestrogen's pharmacology and suggest potential mechanisms underlying its beneficial effects, with particular emphasis on anti-apoptotic and vascular effects.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Costs of mixed low-level waste stabilization options

    SciTech Connect

    Schwinkendorf, W.E.; Cooley, C.R.

    1998-03-01

    Selection of final waste forms to be used for disposal of DOE`s mixed low-level waste (MLLW) depends on the waste form characteristics and total life cycle cost. In this paper the various cost factors associated with production and disposal of the final waste form are discussed and combined to develop life-cycle costs associated with several waste stabilization options. Cost factors used in this paper are based on a series of treatment system studies in which cost and mass balance analyses were performed for several mixed low-level waste treatment systems and various waste stabilization methods including vitrification, grout, phosphate bonded ceramic and polymer. Major cost elements include waste form production, final waste form volume, unit disposal cost, and system availability. Production of grout costs less than the production of a vitrified waste form if each treatment process has equal operating time (availability) each year; however, because of the lower volume of a high temperature slag, certification and handling costs and disposal costs of the final waste form are less. Both the total treatment cost and life cycle costs are higher for a system producing grout than for a system producing high temperature slag, assuming equal system availability. The treatment costs decrease with increasing availability regardless of the waste form produced. If the availability of a system producing grout is sufficiently greater than a system producing slag, then the cost of treatment for the grout system will be less than the cost for the slag system, and the life cycle cost (including disposal) may be less depending on the unit disposal cost. Treatment and disposal costs will determine the return on investment in improved system availability.

  11. Shallow land burial of low-level radioactive waste

    SciTech Connect

    Cannon, J.B.; Jacobs, D.G.; Lee, D.W.; Gilmore, C.C.; Ketelle, R.H.; Kornegay, F.C.; Roop, R.D.; Staub, W.P.; Stratton, L.E.; Thoma, R.E.

    1986-02-01

    The performance objectives included in regulations for disposal of low-level radioactive waste (10 CFR 61 for commercial waste and DOE Order 5820.2 for defense waste) are generic principles that generate technical requirements which must be factored into each phase of the development and operation of a shallow land burial facility. These phases include a determination of the quantity and characteristics of the waste, selection of a site and appropriate facility design, use of sound operating practices, and closure of the facility. The collective experience concerning shallow land burial operations has shown that achievement of the performance objectives (specifically, waste isolation and radionuclide containment) requires a systems approach, factoring into consideration the interrelationships of the phases of facility development and operation and their overall impact on performance. This report presents the technical requirements and procedures for the development and operation of a shallow land burial facility for low-level radioactive waste. The systems approach is embodied in the presentation. The report is not intended to be an instruction manual; rather, emphasis is placed on understanding the technical requirements and knowing what information and analysis are needed for making informed choices to meet them. A framework is developed for using the desired site characteristics to locate potentially suitable sites. The scope of efforts necessary for characterizing a site is then described and the range of techniques available for site characterization is identified. Given the natural features of a site, design options for achieving the performance objectives are discussed, as are the operating practices, which must be compatible with the design. Site closure is presented as functioning to preserve the containment and isolation provided at earlier stages of the development and operation of the facility.

  12. 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.

  13. Hydrophilic solutes in modified carbon dioxide extraction-prediction of the extractability using molecular dynamic simulation.

    PubMed

    Günther, Martina; Maus, Martin; Wagner, Karl Gerhard; Schmidt, Peter Christian

    2005-06-01

    Super- and subcritical carbon dioxide (CO2) extractions of crude drugs were simulated by molecular modelling to predict the extractability of different hydrophilic plant constituents under various extraction conditions. The CO2 extraction fluids were simulated either with pure CO2 or with solvent modified CO2 at different pressures and temperatures. Molecular modelling resulted in three different solubility parameters: the total solubility parameter delta and the partial solubility parameters delta(d) for the van der Waals and delta(EL) for the polar forces. Thus, delta(EL) enabled the estimation of the polarity of the extraction fluids and the solute molecules. If the value of delta(EL) of the extraction fluid reached the value of the solute molecule in the crude drug, i.e. minimum extraction value, the compound was soluble at the distinct extraction conditions. For a further increase in yield of the hydrophilic solutes, the polarity of the extraction fluid had to be increased, too. That means delta(EL) of the fluid exceeded the minimum extraction value. All simulations were verified by CO2 extractions of the secondary roots of Harpagophytum procumbens (harpagoside, stachyose) and the seeds of Aesculus hippocastanum (aescin). CO2 extractions of the flowers of Matricaria recutita ((-)-alpha-bisabolol) were obtained from literature data. These four constituents with different properties, like molecular size and the allocation of polar functional groups were extracted, analysed, simulated and the extract content was correlated with the extraction fluid used, respectively. PMID:15911229

  14. 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.

  15. 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.

  16. Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y.; Schwegler, Eric

    2016-10-01

    Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. Such simulations are often performed at elevated temperatures to artificially "correct" for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. To address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na+, K+, and Cl- ions. We show that simulations at 390-400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. Our results suggest that an elevated temperature around 390-400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.

  17. 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.

  18. Convergence of Sampling Kirkwood-Buff Integrals of Aqueous Solutions with Molecular Dynamics Simulations.

    PubMed

    Ganguly, Pritam; van der Vegt, Nico F A

    2013-03-12

    We discuss two methods for calculating Kirkwood-Buff integrals (KBIs) of aqueous cosolvent solutions from molecular simulations. The first method is based on computing running integrals over radial distribution functions obtained from NVT or NpT simulations. The second, more recent method, originally introduced by Schnell et al. (J. Phys. Chem. B2011, 115, 10911), obtains the KBIs from direct analysis of particle number fluctuations in small, open subvolumes embedded in a larger reservoir as provided by the NVT (NpT) simulation cell. The thermodynamic limit is taken in the first method by using the plateau-values of the running KBIs for large distances, while in the second method an analytical finite-size scaling relation is applied to the KBIs of subvolumes of variable size. We find that direct analysis of particle number fluctuations at small scales provides more precise estimates of KBIs for methanol-water and urea-water solutions. Converged KBIs could, however, not be obtained from nanosecond time scale molecular dynamics simulations with either of the two methods. Based on 0.1 μs simulation trajectories of small and large system sizes time-converged KBIs were obtained with both methods. The running integral method suffers, however, from stronger finite-size artifacts than the sub-box method, also when empirical finite-size tail corrections are applied to the radial distribution functions.

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

    PubMed Central

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

    2013-01-01

    This paper extends the image charge solvation model (ICSM) [J. Chem. Phys. 131, 154103 (2009)], 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. PMID:23913979

  20. 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.

  1. 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.

  2. Simulation of oxygen saturation of hemoglobin solution, RBC suspension and hemosome by a neural network system.

    PubMed

    Kan, P; Chen, W K; Lee, C J

    1996-03-01

    Hemoglobin-based artificial blood substitutes as oxygen carrier is advantageous over current plasma expander. In this study, oxygen saturation of hemoglobin solution, red blood cell suspension and artificial blood substitute under various conditions were measured by yeast-consuming-oxygen experiments instead of spectrophotometer. The empirical results were assigned into training feedforward back-propagation neural network system in order to simulate the oxygen saturation model modulated by those factors such as pH, [Cl-], [2,3-DPG], pO2 and pCO2. Consequently, this neural network is able to simulate accurately the oxygen saturation of Hb solution. The prediction of hemosome is not agreed well possible because of the resistance of transport of oxygen. However, the results showed neural net can offer a simple and convenient way in comparison with the conventional methods, especially in dealing with complex and ambiguous problem.

  3. 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.

  4. Low frequency 2D Raman-THz spectroscopy of ionic solution: A simulation study

    NASA Astrophysics Data System (ADS)

    Pan, Zhijun; Wu, Tianmin; Jin, Tan; Liu, Yong; Nagata, Yuki; Zhang, Ruiting; Zhuang, Wei

    2015-06-01

    The 2D Raman-THz spectrum of the MgCl2 solution was simulated using the molecular dynamics simulation and the stability matrix method and compared with that of the pure water. The 2D Raman-THz signal provides more information on the ion effects on the collective water motion than the conventional 1D signal. The presence of MgCl2 suppresses the cross peak of water between the hydrogen bond bending and the other intermolecular vibrational mode, which clearly illustrates that the water hydrogen bending motion is affected by the confining effect of the ions. Our theoretical work thus demonstrates that the 2D Raman-THz technique can become a valuable nonlinear vibrational probe for the molecular dynamics in the ionic solutions.

  5. 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.

  6. Model Analysis of Low-Level Actinide Waste Disposal in Deep Boreholes

    NASA Astrophysics Data System (ADS)

    Glascoe, L. G.; Wolfsberg, A. V.

    2001-12-01

    Deep borehole disposal is considered as a possible mechanism for the safe removal of Greater Than Class C (GTCC) low level actinide waste (Am-241, Pu-239, and Pu-238). Of the three actinides in GTCC waste, only Pu-239 has a half-life greater than 500 years and, thus, will have the longest environmental presence. However, Am-241 and Pu-238 have the potential to create most of the heat associated with GTCC waste disposal in deep boreholes. Therefore, this study considers the nonisothermal release and subsequent migration toward a pumping well of the most persistent radionuclide, Pu-239, from a deep emplacement borehole taking into account the heat created by decay of all three actinides. The Finite-Element Heat- and Mass-Transfer code, FEHM, is employed to simulate three-dimensional, non-isothermal flow and solute transport using particle tracking. Multiple scenarios considering various source emplacement depths, aquifer properties, and hydraulic conditions are evaluated in a sensitivity analysis that seeks to demonstrate competing and offsetting processes affecting the concentration of Pu-239 in the pumped well 100 m down gradient from the borehole source. In general, lower groundwater fluxes, associated with lower gradients and/or lower aquifer permeabilities, lead to less dissolution of the source waste. However, conditions of decreasing groundwater flux also create larger sized capture zones by the pumping well, thus escalating the likelihood of pumping contaminants originating from a source deeper than the pumping well. Retardation by sorption of Pu-239, both in alluvial aquifers and following diffusion from fractures in a tuff aquifer, plays an important role both in delaying radionuclide migration and in reducing the peak aqueous concentration at the pumping well. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. This work was

  7. Dynamic Beam Solutions for Real-Time Simulation and Control Development of Flexible Rockets

    NASA Technical Reports Server (NTRS)

    Su, Weihua; King, Cecilia K.; Clark, Scott R.; Griffin, Edwin D.; Suhey, Jeffrey D.; Wolf, Michael G.

    2016-01-01

    In this study, flexible rockets are structurally represented by linear beams. Both direct and indirect solutions of beam dynamic equations are sought to facilitate real-time simulation and control development for flexible rockets. The direct solution is completed by numerically integrate the beam structural dynamic equation using an explicit Newmark-based scheme, which allows for stable and fast transient solutions to the dynamics of flexile rockets. Furthermore, in the real-time operation, the bending strain of the beam is measured by fiber optical sensors (FOS) at intermittent locations along the span, while both angular velocity and translational acceleration are measured at a single point by the inertial measurement unit (IMU). Another study in this paper is to find the analytical and numerical solutions of the beam dynamics based on the limited measurement data to facilitate the real-time control development. Numerical studies demonstrate the accuracy of these real-time solutions to the beam dynamics. Such analytical and numerical solutions, when integrated with data processing and control algorithms and mechanisms, have the potential to increase launch availability by processing flight data into the flexible launch vehicle's control system.

  8. FLILO (flying infrared for low-level operations): an enhanced vision system

    NASA Astrophysics Data System (ADS)

    Guell, Jeff J.

    2000-06-01

    FLILO is an Enhanced Vision System (EVS); which enhances Situational Awareness for safe low level/night time and moderate weather flight operations (including: take- off/landing, taxiing, approaches, drop zone identification, Short Austere Air Field operations, etc), by providing electronic/real time vision to the pilots. It consists of a series of imaging sensors, an Image Processor and a wide field-of-view (FOV) see-through Helmet Mounted Display (HMD) integrated with a Head Tracker. The current solution for safe night time/low level military flight operations is the use of the Turret-FLIR (Forward-Looking InfraRed). This system requires an additional operator/crew member (navigator) who controls the Turret's movement and relays the information to the pilots. The image is presented on a Head-Down-Display. FLILO presents the information directly to the pilots on an HMD, therefore each pilot has an independent view controlled by their heads position, while utilizing the same sensors that are static and fixed to the aircraft structure. Since there are no moving parts, the system provides high reliability, while remaining more affordable than the Turret-FLIR solution. FLILO does not require a ball-turret, therefore there is no extra drag or range impact on the aircraft's performance. Furthermore, with future use of real-time multi-band/multi-sensor image fusion, FLILO is the right step towards obtaining safe autonomous landing guidance/0-0 flight operations capability.

  9. 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)

  10. 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.

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

    PubMed

    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 (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 performed

  12. 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.

  13. 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

  14. Hydrated Electron Transfer to Nucleobases in Aqueous Solutions Revealed by Ab Initio Molecular Dynamics Simulations.

    PubMed

    Zhao, Jing; Wang, Mei; Fu, Aiyun; Yang, Hongfang; Bu, Yuxiang

    2015-08-01

    We present an ab initio molecular dynamics (AIMD) simulation study into the transfer dynamics of an excess electron from its cavity-shaped hydrated electron state to a hydrated nucleobase (NB)-bound state. In contrast to the traditional view that electron localization at NBs (G/A/C/T), which is the first step for electron-induced DNA damage, is related only to dry or prehydrated electrons, and a fully hydrated electron no longer transfers to NBs, our AIMD simulations indicate that a fully hydrated electron can still transfer to NBs. We monitored the transfer dynamics of fully hydrated electrons towards hydrated NBs in aqueous solutions by using AIMD simulations and found that due to solution-structure fluctuation and attraction of NBs, a fully hydrated electron can transfer to a NB gradually over time. Concurrently, the hydrated electron cavity gradually reorganizes, distorts, and even breaks. The transfer could be completed in about 120-200 fs in four aqueous NB solutions, depending on the electron-binding ability of hydrated NBs and the structural fluctuation of the solution. The transferring electron resides in the π*-type lowest unoccupied molecular orbital of the NB, which leads to a hydrated NB anion. Clearly, the observed transfer of hydrated electrons can be attributed to the strong electron-binding ability of hydrated NBs over the hydrated electron cavity, which is the driving force, and the transfer dynamics is structure-fluctuation controlled. This work provides new insights into the evolution dynamics of hydrated electrons and provides some helpful information for understanding the DNA-damage mechanism in solution.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Simulations of mean ionic activity coefficients and solubilities in aqueous electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Panagiotopoulos, Athanassios

    Aqueous electrolyte solutions play an important role in industrial, geochemical and biological applications. The mean ionic activity coefficients quantify the deviation of salt chemical potential from ideal solution behavior; experimental measurements are available for many salts over broad ranges of concentration and temperature, but there have been practically no prior simulation results, because if sampling difficulties for explicit-solvent electrolyte solutions. We have developed a new approach for determination of activity coefficients of aqueous electrolytes. Common fixed-point-charge models for water and ions are unable to reproduce simultaneously activity coefficients and solubilities. Polarizable models perform better, but still predict an incorrect temperature dependence of these properties. Work supported by the U.S. Department of Energy, Office of Basic Energy Science.

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Role of Low-Level Laser Therapy in Neurorehabilitation

    PubMed Central

    Hashmi, Javad T.; Huang, Ying-Ying; Osmani, Bushra Z.; Sharma, Sulbha K.; Naeser, Margaret A.; Hamblin, Michael R.

    2011-01-01

    This year marks the 50th anniversary of the discovery of the laser. The development of lasers for medical use, which became known as low-level laser therapy (LLLT) or photobiomodulation, followed in 1967. In recent years, LLLT has become an increasingly mainstream modality, especially in the areas of physical medicine and rehabilitation. At first used mainly for wound healing and pain relief, the medical applications of LLLT have broadened to include diseases such as stroke, myocardial infarction, and degenerative or traumatic brain disorders. This review will cover the mechanisms of LLLT that operate both on a cellular and a tissue level. Mitochondria are thought to be the principal photoreceptors, and increased adenosine triphosphate, reactive oxygen species, intracellular calcium, and release of nitric oxide are the initial events. Activation of transcription factors then leads to expression of many protective, anti-apoptotic, anti-oxidant, and pro-proliferation gene products. Animal studies and human clinical trials of LLLT for indications with relevance to neurology, such as stroke, traumatic brain injury, degenerative brain disease, spinal cord injury, and peripheral nerve regeneration, will be covered. PMID:21172691

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Body contouring using 635-nm low level laser therapy.

    PubMed

    Nestor, Mark S; Newburger, Jessica; Zarraga, Matthew B

    2013-03-01

    Noninvasive body contouring has become one of the fastest-growing areas of esthetic medicine. Many patients appear to prefer nonsurgical less-invasive procedures owing to the benefits of fewer side effects and shorter recovery times. Increasingly, 635-nm low-level laser therapy (LLLT) has been used in the treatment of a variety of medical conditions and has been shown to improve wound healing, reduce edema, and relieve acute pain. Within the past decade, LLLT has also emerged as a new modality for noninvasive body contouring. Research has shown that LLLT is effective in reducing overall body circumference measurements of specifically treated regions, including the hips, waist, thighs, and upper arms, with recent studies demonstrating the long-term effectiveness of results. The treatment is painless, and there appears to be no adverse events associated with LLLT. The mechanism of action of LLLT in body contouring is believed to stem from photoactivation of cytochrome c oxidase within hypertrophic adipocytes, which, in turn, affects intracellular secondary cascades, resulting in the formation of transitory pores within the adipocytes' membrane. The secondary cascades involved may include, but are not limited to, activation of cytosolic lipase and nitric oxide. Newly formed pores release intracellular lipids, which are further metabolized. Future studies need to fully outline the cellular and systemic effects of LLLT as well as determine optimal treatment protocols.

  13. 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.

  14. 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

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

    PubMed

    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/cm(2), 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/cm(2)) (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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Oxidation Kinetics of Spent Low-Level Radioactive Resins

    SciTech Connect

    Huang, Y.-J.; Wang, H. Paul; Chao, Chih C.; Liu, H.H.; Hsiao, M.C.; Liu, S.H.

    2005-11-15

    Experimentally, two-stage oxidation of spent low-level radioactive resin was found by thermo- gravimetric analysis (TGA). About 24% of the spent resins was oxidized at 600 to 900 K. Online Fourier transform infrared spectra showed that the decomposition of the -SO{sub 3}H species in the resin to SO{sub 2} occurred at 670 and 1020 K. The numerical calculation from TGA weight loss data at different heating rates showed that the global activation energies for oxidation of the spent resins were 108 to 138 kJ.mol{sup -1}. The reaction orders for resin and oxygen were about 1.0 and 3.5, respectively. The global rate equations for oxidation of the resin in the first and second stages can be expressed as dx{sub 1}/dt (s{sup -1}) = 2.3 x 10{sup 7} (s{sup -1})exp[-117 900(J.mol{sup -1})/T(K)][1 - x (%)]{sup 0.82} [O{sub 2} (vt%)]{sup 3.5} (x denotes the reaction conversion) and dx{sub 2}/dt = 8.4 x 10{sup 17} exp(-239 500/RT) (1 - x){sup 0.9}[O{sub 2}]{sup 4.5}, respectively.

  1. 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.

  2. Towards Smart Homes Using Low Level Sensory Data

    PubMed Central

    Khattak, Asad Masood; Truc, Phan Tran Ho; Hung, Le Xuan; Vinh, La The; Dang, Viet-Hung; Guan, Donghai; Pervez, Zeeshan; Han, Manhyung; Lee, Sungyoung; Lee, Young-Koo

    2011-01-01

    Ubiquitous Life Care (u-Life care) is receiving attention because it provides high quality and low cost care services. To provide spontaneous and robust healthcare services, knowledge of a patient’s real-time daily life activities is required. Context information with real-time daily life activities can help to provide better services and to improve healthcare delivery. The performance and accuracy of existing life care systems is not reliable, even with a limited number of services. This paper presents a Human Activity Recognition Engine (HARE) that monitors human health as well as activities using heterogeneous sensor technology and processes these activities intelligently on a Cloud platform for providing improved care at low cost. We focus on activity recognition using video-based, wearable sensor-based, and location-based activity recognition engines and then use intelligent processing to analyze the context of the activities performed. The experimental results of all the components showed good accuracy against existing techniques. The system is deployed on Cloud for Alzheimer’s disease patients (as a case study) with four activity recognition engines to identify low level activity from the raw data captured by sensors. These are then manipulated using ontology to infer higher level activities and make decisions about a patient’s activity using patient profile information and customized rules. PMID:22247682

  3. Engineered sorbent barriers for improved low-level waste disposal

    SciTech Connect

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

    1987-01-01

    The Engineered Sorbent Barriers Program at Pacific Northwest Lab., supported by the US Dept. of Energy's Low-Level Waste (LLW) Management Program, is developing sorbent materials to prevent the migration of radionuclides from LLW sites. Unlike impermeable barriers, sorbent barriers allow moisture to pass while selectively sorbing contaminants. This would prevent filling the waste site with water at humid sites, referred to as the bathtub effect. The sorptive behavior of these barriers is similar to the ion-exchange properties that many soils possess for certain radionuclides. However, the degree of sorption of radionuclides is dependent on the type of soil, the specific radionuclide, and the presence of competing ions and organic complexants. Therefore, the use of sorptive additives as radionuclide barriers is recommended to prevent radionuclide migration from the waste site. The experimental work discussed in this paper was directed toward identifying and evaluating sorbent materials for three radionuclides of major concern in defense LLW: /sup 137/Cs, /sup 60/Co, and /sup 90/Sr. No single material was found to be effective for sorbing all three radionuclides of interest. Therefore, formulations were developed containing A-51 zeolite or clinoptilolite for sorbing strontium, greensand or red pottery clay for sorbing cesium, and activated charcoal for sorbing cobalt.

  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 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Versatile Low Level RF System For Linear Accelerators

    NASA Astrophysics Data System (ADS)

    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° 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.

  12. Low-level radioactive wastes. AMA Council on Scientific Affairs.

    PubMed

    1990-02-01

    Under a federal law, each state by January 1, 1993, must provide for safe disposal of its low-level radioactive wastes. Most of the wastes are from using nuclear power to produce electricity, but 25% to 30% are from medical diagnosis, therapy, and research. Exposures to radioactivity from the wastes are much smaller than those from natural sources, and federal standards limit public exposure. Currently operating disposal facilities are in Beatty, Nev, Barnwell, SC, and Richland, Wash. National policy encourages the development of regional facilities. Planning a regional facility, selecting a site, and building, monitoring, and closing the facility will be a complex project lasting decades that involves legislation, public participation, local and state governments, financing, quality control, and surveillance. The facilities will utilize geological factors, structural designs, packaging, and other approaches to isolate the wastes. Those providing medical care can reduce wastes by storing them until they are less radioactive, substituting nonradioactive compounds, reducing volumes, and incinerating. Physicians have an important role in informing and advising the public and public officials about risks involved with the wastes and about effective methods of dealing with them.

  13. Low-level radioactive wastes. Council on Scientific Affairs.

    PubMed

    1989-08-01

    Under a federal law, each state by January 1, 1993, must provide for safe disposal of its low-level radioactive wastes. Most of the wastes are from using nuclear power to produce electricity, but 25% to 30% are from medical diagnosis, therapy, and research. Exposures to radioactivity from the wastes are much smaller than those from natural sources, and federal standards limit public exposure. Currently operating disposal facilities are in Beatty, Nev, Barnwell, SC, and Richland, Wash. National policy encourages the development of regional facilities. Planning a regional facility, selecting a site, and building, monitoring, and closing the facility will be a complex project lasting decades that involves legislation, public participation, local and state governments, financing, quality control, and surveillance. The facilities will utilize geological factors, structural designs, packaging, and other approaches to isolate the wastes. Those providing medical care can reduce wastes by storing them until they are less radioactive, substituting nonradioactive compounds, reducing volumes, and incinerating. Physicians have an important role in informing and advising the public and public officials about risks involved with the wastes and about effective methods of dealing with them.

  14. 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

  15. Observation of cloud formation caused by low-level jets

    NASA Astrophysics Data System (ADS)

    Su, J.; McCormick, M. P.; Lei, L.

    2015-12-01

    We present the results of analyses performed on high-resolution remotely-sensed and in situ atmospheric measurements of the boundary layer and lower atmosphere centered over the northeast coast of the Hampton Roads body of water in southeast Virginia. This region is adjacent to the confluence of the Chesapeake Bay and the Atlantic Ocean where often times, low-level jets (LLJs) are found in the boundary layer during summer months. An East Hampton Roads Aerosol Flux (EHRAF) campaign, was conducted from the campus of Hampton University (HU) to examine small-scale aerosol transport using aerosol, Raman, and Doppler lidars, as well as rawindsondes over a one-week period in May 2014 . LLJs were observed from evening of 20 May to the morning of 21 May, and were found to lead to cloud formation. In this paper, the cloud formation caused by LLJs is analyzed using data that includes high-resolution profiles of: aerosol backscatter, turbulence structure, temperature, wind speed and direction, and water vapor. It is found that enhanced nighttime turbulence triggered by LLJs causes the aerosol and water vapor content of boundary layer to be lifted up forming a well-mixed region. We show that this region contains the cloud condensation nuclei that are very important for the formation of clouds.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. Mixed low-level waste minimization at Los Alamos

    SciTech Connect

    Starke, T.P.

    1998-12-01

    During the first six months of University of California 98 Fiscal Year (July--December) Los Alamos National Laboratory has achieved a 57% reduction in mixed low-level waste generation. This has been accomplished through a systems approach that identified and minimized the largest MLLW streams. These included surface-contaminated lead, lead-lined gloveboxes, printed circuit boards, and activated fluorescent lamps. Specific waste minimization projects have been initiated to address these streams. In addition, several chemical processing equipment upgrades are being implemented. Use of contaminated lead is planned for several high energy proton beam stop applications and stainless steel encapsulated lead is being evaluated for other radiological control area applications. INEEL is assisting Los Alamos with a complete systems analysis of analytical chemistry derived mixed wastes at the CMR building and with a minimum life-cycle cost standard glovebox design. Funding for waste minimization upgrades has come from several sources: generator programs, waste management, the generator set-aside program, and Defense Programs funding to INEEL.

  3. Low-level laser therapy and invisible removal aligners.

    PubMed

    Caccianiga, G; Crestale, C; Cozzani, M; Piras, A; Mutinelli, S; Lo Giudice, A; Cordasco, G

    2016-01-01

    It seems that Low Level Laser Therapy (LLLT) stimulates orthodontic tooth movements, increasing the alveolar bone turnover. The aim of this study is to evaluate how LLLT can influence the orthodontic treatment with invisible removal aligner. A sample of 21 subjects was divided into two groups, a laser group (10 patients) and a control group (11 patients). All subjects were instructed to wear each aligner 12 hours a day for 2 weeks. Laser external bio-stimulation was given in the laser group every second week. The laser group successfully finished the treatment, while at 3rd – 5th aligner the control group did not finish the treatment. Laser treatment seemed to be better than treatment without laser. LLLT combined with aligners is able to favour, in 12 hours, the same tooth movement obtained by wearing the aligner 22 hours a day, according to the traditional protocol. This aspect could be useful for those patients who prefer not to use the aligners during the day. LLLT makes invisible removal aligner treatment more comfortable also because during the day the patients have to wear the aligners less hours than the treatment without laser. PMID:27469556

  4. 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.

  5. 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.

  6. Toxicodynamics of copper and cadmium in Folsomia candida exposed to simulated soil solutions.

    PubMed

    Ardestani, Masoud M; van Gestel, Cornelis A M

    2013-12-01

    To improve our understanding of metal bioavailability to soil-living invertebrates, the effect of porewater composition on the toxicodynamics of copper and cadmium in Folsomia candida (Collembola) was investigated. Assuming that porewater is the main exposure route, F. candida was exposed to simulated soil solutions of different composition. Toxicity of copper was slightly lower in a calcium-only solution than in a multication solution. With increasing copper concentrations from 0.005 mM to 1.37 mM, internal copper concentrations similarly increased in both exposure solutions, suggesting that a single cation nutrient solution is suitable for testing F. candida. In the second experiment, animals were exposed for 7 d to copper and cadmium in simplified soil solutions with different calcium (0.2 mM, 0.8 mM, 3.2 mM, 12.8 mM) and pH (5.0, 6.0, 7.0) levels. The median lethal concentration (LC50) values decreased with time in both the calcium and pH series. A hormetic-type effect was observed for copper in the second test, as well as in the calcium-only solution in the first experiment. Because of stronger hormesis, LC50s for copper were higher at lower calcium concentrations. For cadmium, LC50 values were higher at higher calcium concentrations, suggesting competition of calcium with the free cadmium ion. Toxicity of cadmium increased with decreasing pH, while copper was more toxic at intermediate pH. The results show that a toxicodynamics approach can help to improve the interpretation of metal toxicity to soil invertebrates, taking into account soil solution properties. PMID:23955663

  7. Toxicodynamics of copper and cadmium in Folsomia candida exposed to simulated soil solutions.

    PubMed

    Ardestani, Masoud M; van Gestel, Cornelis A M

    2013-12-01

    To improve our understanding of metal bioavailability to soil-living invertebrates, the effect of porewater composition on the toxicodynamics of copper and cadmium in Folsomia candida (Collembola) was investigated. Assuming that porewater is the main exposure route, F. candida was exposed to simulated soil solutions of different composition. Toxicity of copper was slightly lower in a calcium-only solution than in a multication solution. With increasing copper concentrations from 0.005 mM to 1.37 mM, internal copper concentrations similarly increased in both exposure solutions, suggesting that a single cation nutrient solution is suitable for testing F. candida. In the second experiment, animals were exposed for 7 d to copper and cadmium in simplified soil solutions with different calcium (0.2 mM, 0.8 mM, 3.2 mM, 12.8 mM) and pH (5.0, 6.0, 7.0) levels. The median lethal concentration (LC50) values decreased with time in both the calcium and pH series. A hormetic-type effect was observed for copper in the second test, as well as in the calcium-only solution in the first experiment. Because of stronger hormesis, LC50s for copper were higher at lower calcium concentrations. For cadmium, LC50 values were higher at higher calcium concentrations, suggesting competition of calcium with the free cadmium ion. Toxicity of cadmium increased with decreasing pH, while copper was more toxic at intermediate pH. The results show that a toxicodynamics approach can help to improve the interpretation of metal toxicity to soil invertebrates, taking into account soil solution properties.

  8. Structure simulations for the 0.22 and 1 molar aqueous dimethylammonium chloride solutions.

    PubMed

    Nagy, Peter I

    2012-01-14

    Monte Carlo simulations have been performed for characterizing the 0.22 and 1 molar aqueous dimethylammonium chloride solutions at p = 1 atm and T = 310 K. On the basis of potential of mean force curves for the two systems with increasing concentrations, the N···N separations of about 8.7 and 7.5 Å correspond to a vague and a more pronounced minimum, respectively. Nitrogen separations at the minima are considerably smaller than those what the cations would take if the solutes comprised uniform local solute density on a microscale. The derived N by N coordination numbers predict non-negligible cation association and concomitant inhomogeneity for the studied systems. The calculated N···N distance distribution in the molar solution indicates that about 12% of the N···N separations are shorter than 8.5 Å compared with R(N···N) = 11.84 Å corresponding to the closest distance in a uniform cation local density. Despite a global minimum of -1.79 ± 0.63 kcal mol(-1) at N···Cl separation of 3.24 Å, obtained from the pmf for the 0.22 molar model, the N by Cl coordination number is only 0.14 in the first coordination shell, suggesting frequent disruption of an N-H(+)···Cl(+) hydrogen bond in a relatively dilute solution. The expression for the chemical potential of a solute includes a concentration-dependent activity coefficient, whose varying values are expected to reflect the different degrees of solute association in the 0.2-1 molar range. Theoretical follow-up of the changes in the activity coefficient values is difficult, thus calculation of the K(c) equilibrium constant has been proposed by considering 1 molar solutions as the standard state.

  9. Ad-hoc Solutions for Capturing Electronic Structure Details in Classical Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Crill, John Wesley

    Traditional empirical potentials used in molecular dynamics (MD) simulations replace an explicit treatment of the electronic structure with an appropriate interatomic potential energy expression. This enables MD simulations to model atomistic processes, such as dislocation dynamics and plastic deformation, which typically require size and time domains exceeding what is currently feasible with computationally-demanding first principles techniques. However, discarding the electronic degrees of freedom prevents MD simulations from properly resolving certain phenomena which are dominated by electronic interactions. One example is thermal transport in metals, which is often underestimated by orders of magnitude in MD simulations. A recently-developed multi-scale simulation approach, allowing ad-hoc feedback from continuum heat flow solutions to thermostat atoms in an MD simulation, is used to model Joule-heating in nano-scale metallic contacts under electromagnetic stress. The simulations are carried out under conditions representative of contact surfaces in Radio Frequency Electromechanical Switches (RF MEMS) and rail/armature components of Electromagnetic Launchers (EMLs) and are used to speculate on the mechanisms for experimentally-observed material transfer. Another phenomenon that is typically neglected in MD simulations is charge transfer between atoms of dissimilar electronegativity. A common approach to incorporating a dynamic treatment of charge in a classical potential simulation is to solve atomic charges using an equalization of electronegativity in the charge equilibration (QEq) method. The current work studies the effectiveness of the QEq to mimic the charge distribution properties of f-center defects in a sodium chloride crystal. The results indicate that the QEq is able to replicate some of the electrostatic energy features of an f-center, which include an extremely localized potential well in the vicinity of the defect.

  10. Optical coherence tomography images simulated with an analytical solution of Maxwell's equations for cylinder scattering.

    PubMed

    Brenner, Thomas; Reitzle, Dominik; Kienle, Alwin

    2016-04-30

    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. PMID:27032336

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. Asthma and low level air pollution in Helsinki

    SciTech Connect

    Poenkae A5 )

    1991-09-01

    The effects of relatively low levels of air pollution and weather conditions on the number of patients who had asthma attacks and who were admitted to a hospital were studied in Helsinki during a 3-y period. The number of admissions increased during cold weather (n = 4,209), especially among persons who were of working age but not among children. Even after standardization for temperature, all admissions, including emergency ward admissions, were significantly correlated with ambient air concentrations of nitrogen dioxide (NO2), nitric oxide (NO), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), and total suspended particulates (TSP). Regression analysis revealed that NO and O3 were most strongly associated with asthma problems. Effects of air pollutants and cold were maximal if they occurred on the same day, except for O3, which had a more pronounced effect after a 1-d lag. The associations between pollutants, low temperature, and admissions were most significant among adults of working age, followed by the elderly. Among children, only O3 and NO were significantly correlated with admissions. Levels of pollutants were fairly low, the long-term mean being 19.2 micrograms/m3 for SO2, 38.6 micrograms/m3 for NO2, 22.0 micrograms/m3 or O3, and 1.3 mg/m3 for CO. In contrast, the mean concentration of TSP was high (76.3 micrograms/m3), and the mean temperature was low (+ 4.7 degrees C). These results suggest that concentrations of pollutants lower than those given as guidelines in many countries may increase the incidence of asthma attacks.

  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. 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.

  4. 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.

  5. 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.

  6. The low-level radioactivity ocean sediment standard reference material

    SciTech Connect

    Inn, K.G.W.; Lin, Z.; Liggett, W.S.; Krey, P.W.

    1995-12-31

    Over the past decades, on the order of 10{sup 15} Becquerel nuclear waste have been stored in the oceans. Potential contamination of the oceans from leaking nuclear waste has caused world wide concern. Currently, early warning of ocean contamination near the waste dumping sites rely on monitoring systems being set up by different countries and agencies. Because the determination of low-level radioactivity in ocean sediment is a difficult technical task, a basis for measurement quality assurance, methods verification, and data comparability is needed. The recently certified NIST ocean sediment Standard Reference Material (SRM-4355) is a composite of 1% contaminated Irish Sea sediment and 99% of Chesapeake Bay sediment by weight. The sediments were blended, pulverized to a median particle size of 8 {mu}m, and reblended to achieve acceptable sample homogeneity. A statistical assessment of the intercomparison results from 19 laboratories has shown the material to be homogeneous down to 10 grams. The certified radionuclide concentration range from 0.4 to 230 mBq/g. A variety of radiochemical procedures and detection techniques have been used in the measurements to minimize possible systematic bias. Twelve radionuclides including {sup 40}K, {sup 90}Sr, {sup 137}Cs, {sup 226}Ra, {sup 228}Th, {sup 230}Th, {sup 232}Th, {sup 234}U, {sup 235}U, {sup 238}U, {sup 238}Pu, and {sup (239+240)}Pu were certified. The mean values were reported for an additional 10 uncertified radionuclides: {sup 129}I, {sup 155}Eu, {sup 210}Po, {sup 210}Pb, {sup 212}Pb, {sup 214}Pb, {sup 214}Bi, {sup 228}Ra, {sup 237}Np, and {sup 241}Am. The standard reference material in unit quantities of about 100 gram each will be available by the end of 1995.

  7. Low-Level Waste Drum Assay Intercomparison Study

    SciTech Connect

    Greutzmacher, K.; Kuzminski, J.; Myers, S. C.

    2003-02-26

    Nuclear waste assay is an integral element of programs such as safeguards, waste management, and waste disposal. The majority of nuclear waste is packaged in drums and analyzed by various nondestructive assay (NDA) techniques to identify and quantify the radioactive content. Due to various regulations and the public interest in nuclear issues, the analytical results are required to be of high quality and supported by a rigorous Quality Assurance (QA) program. A valuable QA tool is an intercomparison program in which a known sample is analyzed by a number of different facilities. While transuranic waste (TRU) certified NDA teams are evaluated through the Performance Demonstration Program (PDP), low-level waste (LLW) assay specialists have not been afforded a similar opportunity. NDA specialists from throughout the DOE complex were invited to participate in this voluntary drum assay intercomparison study that was organized and facilitated by the Solid Waste Operations and the Safeguards Science and Technology groups at the Los Alamos National Laboratory and by Eberline Services. Each participating NDA team performed six replicate blind measurements of two 55-gallon drums with relatively low-density matrices (a 19.1 kg shredded paper matrix and a 54.4 kg mixed metal, rubber, paper and plastic matrix). This paper presents the results from this study, with an emphasis on discussing the lessons learned as well as desirable follow up programs for the future. The results will discuss the accuracy and precision of the replicate measurements for each NDA team as well as any issues that arose during the effort.

  8. 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?

  9. 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.

  10. Low-level laser therapy, at 830 nm, for pain reduction in experimental model of rats with sciatica.

    PubMed

    Bertolini, Gladson Ricardo Flor; Artifon, Elisangela Lourdes; Silva, Taciane Stein da; Cunha, Daniela Martins; Vigo, Priscila Regina

    2011-01-01

    Chronic pain, resulting from nerve compression, is a common clinical presentation. One means of conservative treatment is low-level laser therapy, although controversial. The aim of this study was to evaluate the effects of two doses of low-level laser, at 830 nm, on pain reduction in animals subjected to sciatica. Eighteen rats were used, divided into three groups: GS (n=6), sciatica and simulated treatment; G4J (n=6), sciatica and treatment with 4 J/cm²; and G8J (n=6), sciatica and irradiation with 8 J/cm². The right sciatic nerve was exposed and compressed using catgut thread. Five days of treatment were started on the third postoperative day. Pain was assessed by means of the paw elevation time during gait: before sciatica, before and after the first and second therapies, and the end of the fifth therapy. Low-level laser was effective in reducing the painful condition.

  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

    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

  13. 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.

  14. 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…

  15. 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

  16. [Structure of crambin in solution, crystal and in the trajectories of molecular dynamics simulations].

    PubMed

    Abaturov, L V; Nosova, N G

    2013-01-01

    The mechanisms of the three-dimensional crambin structure alterations in the crystalline environments and in the trajectories of the molecular dynamics simulations in the vacuum and crystal surroundings have been analyzed. In the crystalline state and in the solution the partial regrouping of remote intramolecular packing contacts, involved in the formation and stabilization of the tertiary structure of the crambin molecule, occurs in NMR structures. In the crystalline state it is initiated by the formation of the intermolecular contacts, the conformational influence of its appearance is distributed over the structure. The changes of the conformations and positions of the residues of the loop segments, where the intermolecular contacts of the crystal surroundings are preferably concentrated, are most observable. Under the influence of these contacts the principal change of the regular secondary structure of crambin is taking place: extension of the two-strand beta structure to the three-strand structure with the participation of the single last residue N46 of the C-terminal loop. In comparison with the C-terminal loop the more profound changes are observed in the conformation and the atomic positions of the backbone atoms and in the solvent accessibility of the residues of the interhelical loop. In the solution of the ensemble of the 8 NMR structures relative accessibility to the solvent differs more noticeably also in the region of the loop segments and rather markedly in the interhelical loop. In the crambin cryogenic crystal structures the positions of the atoms of the backbone and/or side chain of 14-18 of 46 residues are discretely disordered. The disorganizations of at least 8 of 14 residues occur directly in the regions of the intermolecular contacts and another 5 residues are disordered indirectly through the intramolecular contacts with the residues of the intermolecular contacts. Upon the molecular dynamics simulation in the vacuum surrounding as in the

  17. Assessment of Flood Mitigation Solutions Using a Hydrological Model and Refined 2D Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Khuat Duy, B.; Archambeau, P.; Dewals, B. J.; Erpicum, S.; Pirotton, M.

    2009-04-01

    Following recurrent inundation problems on the Berwinne catchment, in Belgium, a combined hydrologic and hydrodynamic study has been carried out in order to find adequate solutions for the floods mitigation. Thanks to detailed 2D simulations, the effectiveness of the solutions can be assessed not only in terms of discharge and height reductions in the river, but also with other aspects such as the inundated surfaces reduction and the decrease of inundated buildings and roads. The study is carried out in successive phases. First, the hydrological runoffs are generated using a physically based and spatially distributed multi-layer model solving depth-integrated equations for overland flow, subsurface flow and baseflow. Real floods events are simulated using rainfall series collected at 8 stations (over 20 years of available data). The hydrological inputs are routed through the river network (and through the sewage network if relevant) with the 1D component of the modelling system, which solves the Saint-Venant equations for both free-surface and pressurized flows in a unified way. On the main part of the river, the measured river cross-sections are included in the modelling, and existing structures along the river (such as bridges, sluices or pipes) are modelled explicitely with specific cross sections. Two gauging stations with over 15 years of continuous measurements allow the calibration of both the hydrologic and hydrodynamic models. Second, the flood mitigation solutions are tested in the simulations in the case of an extreme flooding event, and their effects are assessed using detailed 2D simulations on a few selected sensitive areas. The digital elevation model comes from an airborne laser survey with a spatial resolution of 1 point per square metre and is completed in the river bed with a bathymetry interpolated from cross-section data. The upstream discharge is extracted from the 1D simulation for the selected rainfall event. The study carried out with this

  18. Solution of the optimal plant location and sizing problem using simulated annealing and genetic algorithms

    SciTech Connect

    Rao, R.; Buescher, K.L.; Hanagandi, V.

    1995-12-31

    In the optimal plant location and sizing problem it is desired to optimize cost function involving plant sizes, locations, and production schedules in the face of supply-demand and plant capacity constraints. We will use simulated annealing (SA) and a genetic algorithm (GA) to solve this problem. We will compare these techniques with respect to computational expenses, constraint handling capabilities, and the quality of the solution obtained in general. Simulated Annealing is a combinatorial stochastic optimization technique which has been shown to be effective in obtaining fast suboptimal solutions for computationally, hard problems. The technique is especially attractive since solutions are obtained in polynomial time for problems where an exhaustive search for the global optimum would require exponential time. We propose a synergy between the cluster analysis technique, popular in classical stochastic global optimization, and the GA to accomplish global optimization. This synergy minimizes redundant searches around local optima and enhances the capable it of the GA to explore new areas in the search space.

  19. Investigation of the salting out of methane from aqueous electrolyte solutions using computer simulations.

    PubMed

    Docherty, H; Galindo, A; Sanz, E; Vega, C

    2007-08-01

    We calculate the excess chemical potential of methane in aqueous electrolyte solutions of NaCl using Monte Carlo computer simulations. In a recent work [Docherty et al. J. Chem. Phys. 2006, 125, 074510], we presented a new potential model for methane in water which is capable of describing accurately the excess chemical potential of methane in pure water over a range of temperatures, a quantity that can be related to the solubility and which is commonly used to study the hydrophobic effect. Here, we use the same potential model for the water-methane interactions and investigate the effect of added salt on the chemical potential of methane in the solution. The methane molecules are modeled as single Lennard-Jones (LJ) interaction sites, and the water molecules are modeled with the TIP4P/2005 model. A correcting factor of chi = 1.07 for the energetic Berthelot (geometric) combining rule of the methane-water interaction is also used, which mimics the polarization of methane in water. We consider NaCl as the salt and treat the ions with the Smith and Dang model (i.e., as charged LJ interaction sites). Ion-water, ion-ion, and ion-methane interactions are treated using Lorentz-Berthelot combining rules. In addition, the Coulombic potential is used to model charge-charge interactions which are calculated using the Ewald sum. We have carried out isobaric-isothermal (NpT) simulations to determine the equilibrium densities of the solutions. The simulation data is in excellent agreement with experimental densities of aqueous NaCl solutions of different concentration. Hydration numbers are also obtained and found to be in agreement with reported data. Canonical (NVT) simulations at the averaged densities are then performed using the Widom test-particle insertion method to obtain the excess chemical potential of methane in the saline solutions. An increase in the chemical potential of methane, corresponding to a salting out effect, is observed when salt is added to the solution

  20. Investigation of the salting out of methane from aqueous electrolyte solutions using computer simulations.

    PubMed

    Docherty, H; Galindo, A; Sanz, E; Vega, C

    2007-08-01

    We calculate the excess chemical potential of methane in aqueous electrolyte solutions of NaCl using Monte Carlo computer simulations. In a recent work [Docherty et al. J. Chem. Phys. 2006, 125, 074510], we presented a new potential model for methane in water which is capable of describing accurately the excess chemical potential of methane in pure water over a range of temperatures, a quantity that can be related to the solubility and which is commonly used to study the hydrophobic effect. Here, we use the same potential model for the water-methane interactions and investigate the effect of added salt on the chemical potential of methane in the solution. The methane molecules are modeled as single Lennard-Jones (LJ) interaction sites, and the water molecules are modeled with the TIP4P/2005 model. A correcting factor of chi = 1.07 for the energetic Berthelot (geometric) combining rule of the methane-water interaction is also used, which mimics the polarization of methane in water. We consider NaCl as the salt and treat the ions with the Smith and Dang model (i.e., as charged LJ interaction sites). Ion-water, ion-ion, and ion-methane interactions are treated using Lorentz-Berthelot combining rules. In addition, the Coulombic potential is used to model charge-charge interactions which are calculated using the Ewald sum. We have carried out isobaric-isothermal (NpT) simulations to determine the equilibrium densities of the solutions. The simulation data is in excellent agreement with experimental densities of aqueous NaCl solutions of different concentration. Hydration numbers are also obtained and found to be in agreement with reported data. Canonical (NVT) simulations at the averaged densities are then performed using the Widom test-particle insertion method to obtain the excess chemical potential of methane in the saline solutions. An increase in the chemical potential of methane, corresponding to a salting out effect, is observed when salt is added to the solution

  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. 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

  4. 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

  5. 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.

  6. 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

  7. Molecular Dynamics Simulations of the Solution-Air Interface of Aqueous Sodium Nitrate

    SciTech Connect

    Thomas, Jennie L.; Roeselova, Martina; Dang, Liem X.; Tobias, Douglas J.

    2007-04-26

    Molecular dynamics simulations have been used to investigate the behavior of aqueous sodium nitrate in interfacial environments. Polarizable potentials for the water molecules and the nitrate ion in solution were employed. Calculated surface tension data at several concentrations are in good agreement with measured surface tension data. The surface potential of NaNO3 solutions at two concentrations also compare favorably with experimental measurements. Density profiles suggest that NO3 - resides primarily below the surface of the solutions over a wide range of concentrations. When the nitrate anions approach the surface of the solution, they are significantly undercoordinated compared to in the bulk, and this may be important for reactions where solvent cage effects play a role, such as photochemical processes. Surface water orientation is perturbed by the presence of nitrate ions, and this has implications for experimental studies that probe interfacial water orientation. Nitrate ions near the surface also have a preferred orientation that places the oxygen atoms in the plane of the interface. The availability of NO3 - for reaction at the surface of aerosols in the atmosphere is discussed. The work at Pacific Northwest National Laboratory was performed under the auspices of the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy. Pacific Northwest National Laboratory is operated by Battelle for the Department of Energy.

  8. 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.

  9. 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.

  10. Simulation of unsteady flow and solute transport in a tidal river network

    USGS Publications Warehouse

    Zhan, X.

    2003-01-01

    A mathematical model and numerical method for water flow and solute transport in a tidal river network is presented. The tidal river network is defined as a system of open channels of rivers with junctions and cross sections. As an example, the Pearl River in China is represented by a network of 104 channels, 62 nodes, and a total of 330 cross sections with 11 boundary section for one of the applications. The simulations are performed with a supercomputer for seven scenarios of water flow and/or solute transport in the Pearl River, China, with different hydrological and weather conditions. Comparisons with available data are shown. The intention of this study is to summarize previous works and to provide a useful tool for water environmental management in a tidal river network, particularly for the Pearl River, China.

  11. Simulating Monovalent and Divalent Ions in Aqueous Solution Using a Drude Polarizable Force Field

    PubMed Central

    Yu, Haibo; Whitfield, Troy W.; Harder, Edward; Lamoureux, Guillaume; Vorobyov, Igor; Anisimov, Victor M.; MacKerell, Alexander D.; Roux, Benoît

    2010-01-01

    An accurate representation of ion solvation in aqueous solution is critical for meaningful computer simulations of a broad range of physical and biological processes. Polarizable models based on classical Drude oscillators are introduced and parametrized for a large set of monoatomic ions including cations of the alkali metals (Li+, Na+, K+, Rb+ and Cs+) and alkaline earth elements (Mg2+, Ca2+, Sr2+ and Ba2+) along with Zn2+ and halide anions (F−, Cl−, Br− and I−). The models are parameterized, in conjunction with the polarizable SWM4-NDP water model [Lamoureux et al., Chem. Phys. Lett. 418, 245 (2006)], to be consistent with a wide assortment of experimentally measured aqueous bulk thermodynamic properties and the energetics of small ion-water clusters. Structural and dynamic properties of the resulting ion models in aqueous solutions at infinite dilution are presented. PMID:20300554

  12. 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

  13. Measurement of low levels of alpha in {sup 99}Mo product solutions.

    SciTech Connect

    Conner, C.; Liberatore, M. W.; Sedlet, J.; Vandegrift, G. F.

    1998-03-05

    The conclusions of this report are that molybdenum can effectively be separated from uranium and plutonium using TRU-Resin; and that separation of the {sup 99}Mo from the actinides will reduce the analyst's exposure and simplify analysis for the actinide elements.

  14. Poleward shift in Indian summer monsoon low level jetstream under global warming

    NASA Astrophysics Data System (ADS)

    Sandeep, S.; Ajayamohan R., S.

    2015-04-01

    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 Intercomparison 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.

  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. SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport

    USGS Publications Warehouse

    Langevin, Christian D.; Thorne, Daniel T.; 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

  17. Car Parrinello molecular dynamics simulation of base-catalyzed amide hydrolysis in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zahn, Dirk

    2004-01-01

    The base catalyzed hydrolysis of N-methylacetamide is elucidated by means of Car-Parrinello simulation. The process is investigated in aqueous solution, including a quantum treatment of all electronic degrees of freedom. The rate-determining step is the attack of a hydroxide ion on the amide carbon atom. This is followed by protonation of the nitrogen atom. The final dissociation may occur via two different pathways: (i) dissociation into an amine and a carboxylic acid and (ii) oxygen deprotonation and dissociation into an amine and a carboxyl anion. The later pathway was found to be strongly favored.

  18. Impacts of an improved low-level cloud scheme on the eastern Pacific ITCZ-cold tongue complex

    NASA Astrophysics Data System (ADS)

    Dai, Fushan; Yu, Rucong; Zhang, Xuehong; Yu, Yongqiang; Li, Jianglong

    2005-07-01

    A statistically-based low-level cloud parameterization scheme is introduced, modified, and applied in the Flexible coupled General Circulation Model (FGCM-0). It is found that the low-level cloud scheme makes improved simulations of low-level cloud fractions and net surface shortwave radiation fluxes in the subtropical eastern oceans off western coasts in the model. Accompanying the improvement in the net surface shortwave radiation fluxes, the simulated distribution of SSTs is more reasonably asymmetrical about the equator in the tropical eastern Pacific, which suppresses, to some extent, the development of the double ITCZ in the model. Warm SST biases in the ITCZ north of the equator are more realistically reduced, too. But the equatorial cold tongue is strengthened and extends further westward, which reduces the precipitation rate in the western equatorial Pacific but increases it in the ITCZ north of the equator in the far eastern Pacific. It is demonstrated that the low-level cloud-radiation feedback would enhance the cooperative feedback between the equatorial cold tongue and the ITCZ. Based on surface layer heat budget analyses, it is demonstrated that the reduction of SSTs is attributed to both the thermodynamic cooling process modified by the increase of cloud fractions and the oceanic dynamical cooling processes associated with the strengthened surface wind in the eastern equatorial Pacific, but it is mainly attributed to oceanic dynamical cooling processes associated with the strengthening of surface wind in the central and western equatorial Pacific.

  19. 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.

  20. 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.

  1. 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

  2. Depth of penetration of an 850nm wavelength low level laser in human skin.

    PubMed

    Esnouf, Alan; Wright, Philip A; Moore, Joan C; Ahmed, Salim

    2007-01-01

    Low Level Laser Therapy is used for a wide variety of conditions including superficial skin sores, musculoskeletal and joint problems, and dentistry. Knowledge of the penetration depth of laser radiation in human skin is an essential prerequisite to identifying its method of action. Mathematical simulations and estimates from the literature suggest that the depth of penetration of laser radiation using wavelengths from 630nm up to 1100nm may be up to 50mm. The aim of this study is to directly measure the penetration depth of a Low Level Laser in human tissue. Human abdominal skin samples up to 0.784mm thickness were harvested by dermatome following abdominoplasty procedures. These samples were irradiated by a Gallium Aluminium Arsenide Laser (Wavelength 850nm near infra-red invisible light, 100mW, 24kHz, 0.28mm diameter probe) and the transmitted radiation measured with an Ophir Optronics 'Nova' external energy meter. The intensity of laser radiation reduced by 66% after being transmitted through a 0.784mm sample of human abdominal tissue. In this study most laser radiation was absorbed within the first 1mm of skin.

  3. [Protein conformational dynamics of crambin in crystal, solution and in the trajectories of molecular dynamics simulations].

    PubMed

    Abaturov, L V; Nosova, N G

    2013-01-01

    Atomic displacement parameters--B factors of the eight crambin crystal structures obtained at 0.54-1.5 angstroms resolution and temperatures of 100-293K have been analyzed. The comparable contributions to the B factor values are the intramolecular motions which are modeled by the harmonic vibration calculations and derived from the molecular dynamics simulation (MD) as well as rigid body changes in the position of a protein molecule as a whole. In solution for the average NMR structure of crambin the amplitudes of the backbone atomic fluctuations of the most residues of the segments with the regular backbone conformations are close to the amplitudes of the small scale harmonic vibrations. For the same residues the probability of the medium scale fluctuations fixed by the hydrogen exchange method is very low. The restricted conformational mobility of those segments is coupled with the depressed amplitudes of the fluctuation changes of the tertiary structure registered by the residue accessibility changes in an ensemble of NMR structures that forms the average NMR structure of crambin. The amplitudes of temperature fluctuations of backbone atoms and the tertiary structure raise in the segment with the irregular conformations, turn and loops. In the same segments the amplitudes of the calculated harmonic vibrations also increase, but to a lesser extent and especially in the interhelical loop with the most strong and complicated fluctuation changes of the backbone conformation. In solution for the NMR structure in this loop the conformational transitions occur between the conformational substates separated by the energy barriers, but they are not observed even in the long 100 ns trajectories from the MD simulation of crambin. These strong local fluctuation changes of the structure may play a key role in the protein functioning and modern performance improvements in the MD simulation techniques are oriented to increase the probability of protein appearance in the

  4. 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

  5. Alternatives To The Burial Of Low-Level Radioactive Waste

    SciTech Connect

    Price, J. Mark

    2008-01-15

    have been fully dismantled. Proven techniques and equipment are available to dismantle nuclear facilities safely. Most parts of a nuclear power plants do not become radioactive or are contaminated at very low levels and most metal can be recycled. There are obvious environmental benefits to the decontamination, recycle and reuse of materials. The benefits come primarily from the reduction of waste and eliminating the need to obtain fresh materials for the new product. The benefits of recycling in other industries are well recognized. Not having a waste management option can sometimes delay decommissioning of nuclear facilities. Therefore, the availability of a recycling route for the waste may accelerate decommissioning progress. With improving prospects for building new nuclear power plants, the industry would likely use the option if significant amounts of waste materials could be recycled economically. There is little consistency in national approaches to recycling radioactive waste. Many options for recycling allow for the release of materials into the public domain (after decontamination to allowable levels). There is not uniform endorsement of this practice from country to country and some stakeholders do not agree with this type of material release (often reduced to as unconditional release). There is a large amount of material that can have conditional release within the industry that assures consistent endorsement by stakeholders. This material includes: concrete, lead, carbon and stainless steel, and graphite. More work needs to be done to ensure consistency in regulation from country to country. The IAEA is working to this end.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Visual cues to geographical orientation during low-level flight

    NASA Technical Reports Server (NTRS)

    Battiste, Vernol; Delzell, Suzanne

    1991-01-01

    A field study of an operational Emergency Medical Service (EMS) unit was conducted to investigate the relationships among geographical orientation, pilot decision making, and workload in EMS flights. The map data collected during this study were compared to protocols gathered in the laboratory, where pilots viewed a simulated flight over different types of unfamiliar terrain and verbally identified the features utilized to maintain geographical orientation. The EMS pilot's questionnaire data were compared with data from non-EMS helicopter pilots with comparable flight experience.

  11. 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.

  12. Simulating the dynamics of a single polymer chain in solution: Lattice Boltzmann vs Brownian dynamics

    NASA Astrophysics Data System (ADS)

    Duenweg, Burkhard

    2010-03-01

    Two well--established and complementary methodologies to simulate the dynamics of polymers in solution are (i) Brownian Dynamics (BD), and (ii) Molecular Dynamics coupled dissipatively to a lattice Boltzmann background (MD/LB). The talk gives a brief introduction into both methods, and then presents results of a recent comparative study that applied both methods to the same model of a single chain that moves in a solvent under the influence of thermal noise. Emphasis is put on the question how to map the parameters onto each other, in particular those that are crucial for the dynamics. The agreement of static properties is perfect, as it must be. The dynamic properties agree very well, if for the MD/LB case the effects of finite box size are eliminated by extrapolation. We also find that proper thermalization of all MD/LB degrees of freedom (including the so--called ``kinetic modes'') is necessary. Small deviations between BD and MD/LB remain as a result of the different simulation methodologies. Finally, the computational efficiency of the two methods is compared. For the single--chain system, BD is clearly much faster, while scaling estimates suggest that the opposite is true for semidilute solutions. References: *Tri T. Pham, Ulf D. Schiller, J. Ravi Prakash, and B. D"unweg, J. Chem. Phys. 131, 164114 (2009). *B. D"unweg and A. J. C. Ladd, Adv. Polym. Sci. 221, 89 (2009).

  13. 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

  14. [Effect of simulated inorganic anion leaching solution of electroplating sludge on the bioactivity of Acidithiobacillus ferrooxidans].

    PubMed

    Chen, Yan; Huang, Fang; Xie, Xin-Yuan

    2014-04-01

    An Acidithiobacillus ferrooxidans strain WZ-1 (GenBank sequence number: JQ968461) was used as the research object. The effects of Cl-, NO3-, F- and 4 kinds of simulated inorganic anions leaching solutions of electroplating sludge on the bioactivity of Fe2+ oxidation and apparent respiratory rate of WZ-1 were investigated. The results showed that Cl-, NO3(-)- didn't have any influence on the bioactivity of WZ-1 at concentrations of 5.0 g x L(-1), 1.0 g x L(-1), respectively. WZ-1 showed tolerance to high levels of Cl- and NO3- (about 10.0 g x L(-1), 5.0 g x L(-1), respectively), but it had lower tolerance to F- (25 mg x L(-1)). Different kinds of simulated inorganic anions leaching solutions of electroplating sludge had significant differences in terms of their effects on bioactivity of WZ-1 with a sequence of Cl-/NO3(-)/F(-) > or = NO3(-)/F(-) > Cl-/F(-) > Cl(-)/NO3(-).

  15. 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.

  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. Continuum description of ionic and dielectric shielding for molecular-dynamics simulations of proteins in solution.

    PubMed

    Egwolf, Bernhard; Tavan, Paul

    2004-01-22

    We extend our continuum description of solvent dielectrics in molecular-dynamics (MD) simulations, which has provided an efficient and accurate solution of the Poisson equation, to ionic solvents as described by the linearized Poisson-Boltzmann (LPB) equation. We start with the formulation of a general theory for the electrostatics of an arbitrarily shaped molecular system, which consists of partially charged atoms and is embedded in a LPB continuum. This theory represents the reaction field induced by the continuum in terms of charge and dipole densities localized within the molecular system. Because these densities cannot be calculated analytically for systems of arbitrary shape, we introduce an atom-based discretization and a set of carefully designed approximations. This allows us to represent the densities by charges and dipoles located at the atoms. Coupled systems of linear equations determine these multipoles and can be rapidly solved by iteration during a MD simulation. The multipoles yield the reaction field forces and energies. Finally, we scrutinize the quality of our approach by comparisons with an analytical solution restricted to perfectly spherical systems and with results of a finite difference method.

  18. 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).

  19. 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.

  20. Low-Level waste phase 1 melter testing off gas and mass balance evaluation

    SciTech Connect

    Wilson, C.N.

    1996-06-28

    Commercially available melter technologies were tested during 1994-95 as part of a multiphase program to test candidate technologies for vitrification of the low-level waste (LLW) stream to be derived from retrieval and pretreatment of Hanford Site tank wastes. Seven vendors were selected for Phase 1 testing to demonstrate vitrification of a high sodium content liquid LLW simulant. The tested melter technologies included four Joule-heated melters, a carbon electrode melter, a combustion melter, and a plasma melter. Various dry and slurry melter feed preparation processes were also tested. Various feed material samples, product glass samples, and process offgas streams were characterized to provide data for evaluation of process decontamination factors and material mass balances for each vitrification technology. This report describes the melter mass balance evaluations and results for six of the Phase 1 LLW melter vendor demonstration tests.

  1. Controllable release from high-transition temperature magnetoliposomes by low-level magnetic stimulation.

    PubMed

    Spera, Romina; Apollonio, Francesca; Liberti, Micaela; Paffi, Alessandra; Merla, Caterina; Pinto, Rosanna; Petralito, Stefania

    2015-07-01

    High-transition temperature liposomes with embedded coated magnetite nanoparticles were prepared using the thin lipid film hydration method in order to obtain magnetoliposomes not sensitive to temperature increase (at least up to 50°C). Accordingly, drug can be released from such magnetoliposomes using a low-level electromagnetic field as triggering agent, while no delivery would be obtained with temperature increase within the physiological acceptable range. The hypothesized release mechanism involves mechanical stress of the liposome membrane due to nanoparticles oscillations and it is investigated by means of a numerical model evaluated using multiphysics simulations. The carrier content was repetitively released by switching on and off a 20kHz, 60A/m magnetic field. The results indicated high reproducibility of cycle-to-cycle release induced by the magnetic-impelled motions driving to the destabilization of the bilayer rather than the liposome phase transition or the destruction of the liposome structure.

  2. Controllable release from high-transition temperature magnetoliposomes by low-level magnetic stimulation.

    PubMed

    Spera, Romina; Apollonio, Francesca; Liberti, Micaela; Paffi, Alessandra; Merla, Caterina; Pinto, Rosanna; Petralito, Stefania

    2015-07-01

    High-transition temperature liposomes with embedded coated magnetite nanoparticles were prepared using the thin lipid film hydration method in order to obtain magnetoliposomes not sensitive to temperature increase (at least up to 50°C). Accordingly, drug can be released from such magnetoliposomes using a low-level electromagnetic field as triggering agent, while no delivery would be obtained with temperature increase within the physiological acceptable range. The hypothesized release mechanism involves mechanical stress of the liposome membrane due to nanoparticles oscillations and it is investigated by means of a numerical model evaluated using multiphysics simulations. The carrier content was repetitively released by switching on and off a 20kHz, 60A/m magnetic field. The results indicated high reproducibility of cycle-to-cycle release induced by the magnetic-impelled motions driving to the destabilization of the bilayer rather than the liposome phase transition or the destruction of the liposome structure. PMID:26042528

  3. Simulation of hydrodynamics and solute transport in the Neuse River estuary

    USGS Publications Warehouse

    Robbins, Jeanne C.; Bales, Jerad

    1995-01-01

    An investigation was conducted to characterize flow, circulation, and transport in the Neuse River estuary, North Carolina. The study included a detailed field-measurement program and the calibration, validation, and application of a physically realistic numerical model of hydro- dynamics and transport through a 40-kilometer reach of the estuary. Water level, salinity, water temperature, wind speed and direction, current velocity, and bathymetric data were collected during March 1988 through September 1992. Additional data from pre-existing continuous-record streamflow gaging stations and meteorological stations also were used. A two-dimensional, vertically averaged hydrodynamic and solute transport model was applied to the study reach. The model domain was discretized into 200- by 200-meter computational cells. Model calibration was achieved through adjustment of model parameters for the period June 1-24, 1991. Additional simulations for periods in 1989 and 1991 were run to validate the model. The model was calibrated and validated for water levels ranging from -0.104 to 0.908 meters, salinities ranging from 2.8 to 22.0 parts per thousand, and wind speed from calm to 9 meters per second. The model was tested for stratified and unstratified conditions. Simulated and observed level, salinity, and velocity data were used to evaluate the model. The calibrated model was applied to simulate flows, circulation, and salinity distributions for four simulation periods in 1989 and 1991. Comparisons of simulated results for a period in June 1991 were made between the Neuse and Pamlico models to characterize differences between the two systems.

  4. Size-exclusion partitioning of neutral solutes in crosslinked polymer networks: a Monte Carlo simulation study.

    PubMed

    Quesada-Pérez, Manuel; Adroher-Benítez, Irene; Maroto-Centeno, José Alberto

    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. PMID:24880328

  5. Comparison between numerical simulation and experimental measurement of solute segregation during directional solidification

    NASA Astrophysics Data System (ADS)

    Stelian, Carmen; Duffar, Thierry; Nicoara, Irina

    2003-07-01

    The effect of Bridgman furnace configuration on the temperature field, melt convection and the solute distribution in the resulting crystal are experimentally and numerically analyzed for the semiconductor diluted alloy solidification. The governing equations of the heat and mass transfer are solved by using the finite element method with help of the commercial software FIDAP ®. Two different solidification experiments of Ga 1- xIn xSb ( x=0.01 and 0.04) are simulated in order to compare the numerical results for thermal, velocity and solute fields. The central objective of the work is to give the conditions for which a more uniform distribution of the solute in the crystal can be obtained. It is found that crystals obtained in conditions of a strong convective regime in the vicinity of the solid-liquid interface are more homogeneous radially and on a significant length than the crystals for which solidification occurred in a quasi-diffusive regime. The results, in terms of axial and radial segregation, are compared to experimental chemical analysis.

  6. 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.

  7. Color change of newly developed esthetic restorative material immersed in food-simulating solutions.

    PubMed

    Fujita, Megumi; Kawakami, Susumu; Noda, Mamoru; Sano, Hidehiko

    2006-06-01

    Recently, an esthetic tooth coating material has been developed. The material consisted of a primer solution, a base coat, and a top coat. The purpose of this study, therefore, was to evaluate the color change of this tooth coating material and two resin composites after immersion in food-simulating, staining solutions. To this end, the newly developed coating material with and without its top coat, a flowable resin composite, and a hybrid resin composite were employed for the evaluation. The specimens were subjected to an experimental 24-hour staining cycle: 7-hour immersion in coffee, green tea or red wine, then 17-hour immersion in artificial saliva solution containing 0.3% mucin. After 24 hours, 3 days, 1, 2, and 4 weeks of immersion, the color changes of all specimen surfaces were measured. Compared with the other materials, the deltaE* value of coating material without its top coat tended to increase as the immersion period increased until 4 weeks. On the other hand, the deltaE* value of coating material with its top coat measured the lowest among the materials tested. Based on the results obtained, it was concluded that when using this recently developed tooth coating material in dental clinics, its top coat should be properly applied.

  8. Detailed study of the dielectric function of a lysozyme solution studied with molecular dynamics simulations.

    PubMed

    Floros, Stelios; Liakopoulou-Kyriakides, Maria; Karatasos, Kostas; Papadopoulos, Georgios E

    2015-12-01

    The spread of microwave technology and new microwave applications in medicine have revitalized interest in the dielectric behavior of biological systems. In this work, the Fröhlich-Kirkwood approach and the linear response theory have been applied in conjunction with molecular dynamics simulations to study the dielectric response of a lysozyme solution as a model. The overall experimental dielectric behavior of a 9.88 mM lysozyme solution has been reproduced in a quantitative manner by employing a method based on the decomposition of the hydration shells close to the solute. Detailed analysis of the calculated spectra identified two δ-processes located at 200 MHz (δ1) and about 1 GHz (δ2), respectively. δ1 is associated mainly with the first hydration shell, while δ2 mainly with bulk water and the second hydration shell. Moreover, indications for the existence of an even faster relaxation in the 10(11)-Hz frequency range were found for the first time. Finally, the static dielectric constants of lysozyme and its first and second hydration shells were calculated based on the Fröhlich-Kirkwood and the linear response theory approaches.

  9. 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.

  10. Size-exclusion partitioning of neutral solutes in crosslinked polymer networks: a Monte Carlo simulation study.

    PubMed

    Quesada-Pérez, Manuel; Adroher-Benítez, Irene; Maroto-Centeno, José Alberto

    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.

  11. Autolysis of cell walls from polygalacturonase-antisense tomato fruit in simulated apoplastic solutions.

    PubMed

    Almeida, Domingos P F; Huber, Donald J

    2011-06-01

    Autolysis of cell walls from polygalacturonase (PG)-antisense tomato fruit was studied in a conventional buffer designed to maximize the catalytic activity of PG (30 mM sodium acetate, 150 mM NaCl, pH 4.5), and in solutions mimicking the pH and mineral composition of the fruit apoplast at the mature-green and ripe stages. Autolytic release of uronic acids was very limited under simulated apoplastic conditions compared with the conventional buffer, but minimal differences in the release of reducing groups were observed among the incubation conditions. Autolytic release of uronic acids from active walls was lower than solubilization from enzymically inactive walls. Uronic acids that remained ionically bound to the cell walls during autolysis were subsequently extracted and analyzed by size exclusion chromatography. The elution profiles of ionically bound uronic acids from cell walls incubated under optimal conditions were similar for all ripening stages. In solutions mimicking the pH and mineral composition of the apoplast of mature-green and ripe fruit, uronic acids extracted from pink and ripe fruit cell walls showed a decrease in average molecular mass compared with polymers from mature-green cell walls. The results suggest that the composition of the incubation solution exert strong influence on PG-independent cell wall autolysis and that enzymically active walls restrain PG-independent pectin solubilization.

  12. Simulation of hydrodynamics and solute transport in the Pamlico River estuary, North Carolina

    USGS Publications Warehouse

    Bales, Jerad; Robbins, Jeanne C.

    1995-01-01

    An investigation was conducted to characterize flow, circulation, and solute transport in the Pamlico River estuary, North Carolina. The study included a detailed field-measurement program and the calibration, validation, and application of a physically realistic numerical model of hydro- dynamics and transport. Water level, salinity, water temperature, wind speed and direction, and current data were collected during March 1988 through September 1992, and were used to characterize physical conditions in the estuary. Data from pre- existing streamflow gaging stations and meteoro- logical stations were also used. A two-dimensional vertically averaged hydrodynamic and solute transport model was applied to the 48-kilometer study reach. The model domain was discretized into 5,620 separate 200- by 200-meter computational cells. Model calibration was achieved through adjustment of parameters for June 14-30, 1991. Data from selected periods in 1989 and 1991 were used for model validation. Water levels used for model calibration and validation ranged from -0.052 to 0.698 meter; salinities ranged from 0.1 to 13.1 parts per thousand; and wind speeds ranged from calm to 22 meters per second. The model was tested for stratified and unstratified conditions. Simulated and observed data were used to evaluate model performance. The calibrated model was applied for selected periods in 1989 and 1991. Instantaneous flows were simulated at each boundary and at mid- estuary. Circulation patterns were characterized using vector plots, particle tracking, and solute transport. Particle tracks showed that materials released at mid-estuary may remain in the system for 25 days or longer.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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

  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. 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).

  5. Effect of submerged vegetation on solute transport in an open channel using large eddy simulation

    NASA Astrophysics Data System (ADS)

    Lu, J.; Dai, HC

    2016-11-01

    Existence of vegetation plays a significant effect on the flow velocity distributions, turbulence structures and solute mixing in an open channel. This paper has implemented a 3D large eddy simulation model for the flow and scalar transport in the open channel with vegetation. The model can produce a typical turbulence characteristics and concentration distribution with vegetation. The scalar transport mechanism is quantitatively explained by the turbulent Schmidt number, Reynolds flux, coherent structures and quadrant conditional analysis. A dominance of ejection-sweeping events occurs in the process of the momentum and scalar flux transport. The spectral analysis is used to identify the Kelvin-Helmholtz frequency. The turbulence characteristics of the length scale of vortexes, Kelvin-Helmholtz frequency and Reynolds stress etc. are analyzed with the vegetation density. The model quantitatively predicts the trend of decreasing in the concentration distribution along the flow direction with the increasing of vegetation density.

  6. 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.

  7. 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

  8. Approximate Co-Location of Precipitation and Low-Level Westerlies in Tropical Monthly Means

    NASA Technical Reports Server (NTRS)

    Choa, Winston C.; Chen, Baode

    1999-01-01

    In summer monsoon regions the monthly mean precipitation regions coincide approximately well with regions of westerlies at low-levels. An included chart shows a 15-year (1979-1993) mean August 850 hPa zonal wind from NCEP/NCAR reanalysis dataset and Xie-Arkin precipitation. It shows a region of westerlies covering most of Northern Indian Ocean and extending to northwestern Pacific. This region coincides well with the region with precipitation greater than 6 mm/day. Obviously the coincidence is not exact; the region of larges; zonal wind in the Arabian Sea is in a region of relatively low precipitation and is far from the region of maximum precipitation in Bay of Bengal. Also, in a zonally averaged sense between 40E and 140E, the latitude of maximum precipitation is slightly higher than that of the maximum zonal wind. Low-level westerlies are also found in regions west of Central America and in western Africa north of the equator. These regions are also closely associated with precipitation centers. Across equator from these westerlies regions there are regions of strong easterlies. Also, on their poleward side the westerly regions are flanked by weaker easterly regions. In February, similar observation can be found in the Australian monsoon area and in South America monsoon region; again the regions of westerlies coincide well with regions of maximum precipitation. As in the northern hemisphere, the maximum precipitation is found to the cast of the maximum zonal wind. The two maxima lie almost at the same latitude with that of the westerlies slightly closer to the equator. In the non-monsoon seasons the low- level westerlies can also be found in the tropical precipitation regions, the longitudinal range of the westerlies is undiminished and the speed of the westerlies is not much weaker than that found in February. The interpretation of these observational facts is the goal of this investigation. The approach taken is numerical simulation with the Goddard Earth

  9. 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

  10. 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

  11. 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.

  12. Ion exchange recovery of Ni(II) from simulated electroplating waste solutions containing anionic ligands.

    PubMed

    Juang, Ruey-Shin; Kao, Hsiang-Chien; Liu, Fong-Yi

    2006-01-16

    Ion exchange is widely used for the recovery and removal of metals from process and waste streams in chemical process industries. The Na-form of strong-acid Purolite NRW-100 resin was used to recover Ni(II) from a simulated electroplating waste solution containing NiSO4, NH4Cl, NaH2PO4, and citrate. A set of mass balance equations that take into account possible aqueous complexation reactions was used to establish the pH diagram of Ni(II) species in the presence of anionic ligand citrate or phosphate. Experiments were performed as a function of initial solution pH (0.5-6.0), initial concentration of Ni(II) (0.85-11.9 mol/m3), and temperature (15-45 degrees C). It was shown that the amount of Ni(II) exchanged leveled off when the equilibrium pH was higher than around 2.5. The exchange isotherms obtained at various equilibrium pH values were well fitted by the Langmuir equation. The enthalpy of Ni(II) exchange was also evaluated based on the Langmuir constant. Finally, the kinetics of the present ion exchange process was analyzed.

  13. 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)

  14. 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.

  15. 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

  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.

  17. Pulmonary biochemical and histological alterations after repeated low-level blast overpressure exposures.

    PubMed

    Elsayed, Nabil M; Gorbunov, Nikolai V

    2007-01-01

    Blast overpressure (BOP), also known as high energy impulse noise, is a damaging outcome of explosive detonations and firing of weapons. Exposure to BOP shock waves alone results in injury predominantly to the hollow organ systems such as auditory, respiratory, and gastrointestinal systems. In recent years, the hazards of BOP that once were confined to military and professional settings have become a global societal problem as terrorist bombings and armed conflicts involving both military and civilian populations increased significantly. We have previously investigated the effects of single BOP exposures at different peak pressures. In this study, we examined the effects of repeated exposure to a low-level BOP and whether the number of exposures or time after exposure would alter the injury outcome. We exposed deeply anesthetized rats to simulated BOP at 62 +/- 2 kPa peak pressure. The lungs were examined immediately after one exposure (1 + 0), or 1 h after one (1 + 1), two (2 + 1), or three (3 + 1) consecutive exposures at 3-min interval. In one group of animals, we examined the effects of repeated exposure on lung weight, methemoglobin, transferrin, antioxidants, and lipid peroxidation. In a second group, the lungs were fixed inflated at 25 cm water, sectioned, and examined histologically after one to three repeated exposures, or after one exposure at 1, 6, and 24 h. We found that single BOP exposure causes notable changes after 1 h, and that repeating BOP exposure did not add markedly to the effect of the first one. However, the effects increased significantly with time from 1 to 24 h. These observations have biological and occupational implications, and emphasize the need for protection from low-level BOP, and for prompt treatment within the first hour following BOP exposure. PMID:17060374

  18. Simulation of intrathrombus fluid and solute transport using in vivo clot structures with single platelet resolution

    PubMed Central

    Voronov, Roman S.; Stalker, Timothy J.; Brass, Lawrence F.; Diamond, Scott L.

    2013-01-01

    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 cm2). Average wall shear stresses were 80–100 dyne/cm2 (peak values > 200 dyne/cm2) on the outer rough surface of the thrombus. Within the thrombus, small molecule tracers (0.1 kDa) experienced ~70,000 collisions/sec and penetrated/exited it in about 1 sec, whereas proteins (~50 kDa) had ~9,000 collisions/sec and required about 10 sec (tortuosity ~ 2 to 2.5). These simulations help define physical processes during thrombosis and constraints for drug delivery to the thrombus. PMID:23423707

  19. 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.

  20. 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.

  1. Molecular Properties of Astaxanthin in Water/Ethanol Solutions from Computer Simulations.

    PubMed

    Karki, Khadga Jung; Samanta, Susruta; Roccatano, Danilo

    2016-09-01

    Astaxanthin (AXT) is a reference model of xanthophyll carotenoids, which is used in medicine and food industry, and has potential applications in nanotechnology. Because of its importance, there is a great interest in understanding its molecular properties and aggregation mechanism in water and mixed solvents. In this paper, we report a novel model of AXT for molecular dynamics simulation. The model is used to estimate different properties of the molecule in pure solutions and in water/ethanol mixtures. The calculated diffusion coefficients of AXT in pure water and ethanol are (3.22 ± 0.01) × 10(-6) cm(2) s(-1) and (2.7 ± 0.4) × 10(-6) cm(2) s(-1), respectively. Our simulations also show that the content of water plays a clear effect on the morphology of the AXT aggregation in water/ethanol mixture. In up to 75% (v/v) water concentration, a loosely connected network of dimers and trimers and two-dimensional array structures are observed. At higher water concentrations, AXT molecules form more compact three-dimensional structures that are preferentially solvated by the ethanol molecules. The ethanol preferential binding and the formation of a well connected hydrogen bonding network on these AXT clusters, suggest that such preferential solvation can play an important role in controlling the aggregate structure. PMID:27536854

  2. 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.

  3. Characterization of atomic structure of oxide films on carbon steel in simulated concrete pore solutions using EELS

    NASA Astrophysics Data System (ADS)

    Gunay, H. Burak; Ghods, Pouria; Isgor, O. Burkan; Carpenter, Graham J. C.; Wu, Xiaohua

    2013-06-01

    The atomic structure of oxide films formed on carbon steel that are exposed to highly alkaline simulated concrete pore solutions was investigated using Electron Energy Loss Spectroscopy (EELS). In particular, the effect of chloride exposure on film structure was studied in two types of simulated pore solutions: saturated calcium hydroxide (CH) and a solution prepared to represent typical concrete pore solutions (CP). It was shown that the films that form on carbon steel in simulated concrete pore solutions contained three indistinct layers. The inner oxide film had a structure similar to that of FeIIO, which is known to be unstable in the presence of chlorides. The outer oxide film mainly resembled Fe3O4 (FeIIO·Fe2IIIO3) in the CH solution and α-Fe2IIIO3/Fe3O4 in the CP solution. The composition of the transition layer between the inner and outer layers of the oxide film was mainly composed of Fe3O4 (FeIIO·Fe2IIIO3). In the presence of chloride, the relative amount of the FeIII/FeII increased, confirming that chlorides induce valence state transformation of oxides from FeII to FeIII, and the difference between the atomic structures of oxide film layers diminished.

  4. Low-level Waste Forum meeting report. Winter meeting, January 26--28, 1994

    SciTech Connect

    1994-12-31

    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.

  5. 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.

  6. 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.

  7. Low-level Waste Forum meeting report. Quarterly meeting, July 25--26, 1991

    SciTech Connect

    1991-12-31

    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.

  8. 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.

  9. 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.

  10. Comparative life-cycle cost analysis for low-level mixed waste remediation alternatives. Technical report

    SciTech Connect

    Jackson, J.A.; White, T.P.; Kloeber, J.M.; Toland, R.J.; Cain, J.P.

    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 Femald Environmental Management Project near Cincinnati, OH. Life-cycle costs for virtification, 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.

  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. 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

  13. 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.

  14. Molecular Simulation of Water Extraction into a Tri-n-Butyl-Phosphate/n-Dodecane Solution

    SciTech Connect

    de Almeida, Valmor F; Ye, Xianggui; Cui, Shengting; Khomami, Bamin

    2013-01-01

    Abstract: Molecular dynamics simulations were performed to investigate water extraction into a solution of 30 vol% tri-n-butyl-phosphate (TBP) in n-dodecane. This solvent extraction mixture is commonly used in hydrometallurgical and nuclear fuel recycling operations for recovering metals from aqueous streams. It is known that water is coextracted in the organic phase and that it competes with metal ions for the available extractant agent (TBP). Therefore investigating pure water extraction provides a realistic prototype to test molecular simulation methods for the first time in this area. Our computational results indicate that the TBP electric dipole moment has a significant effect on the predicted water solubility. A larger TBP dipole moment decreases the aqueous-organic interfacial tension, leading to increased roughness of the aqueous-organic interface. Interfacial roughness has a significant effect on disrupting the interfacial water hydrogen bonding structure, resulting in a greater number of dangling water molecules at the interface. This enhances the probability of water molecules to break away from the aqueous phase and to migrate into the bulk of the organic phase. Therefore, the magnitude of the TBP dipole moment is a crucial factor in controlling water hydrogen bond breaking at the aqueous-organic interface. By slightly lowering the atomic partial charges of the TBP atoms, to produce a dipole moment that better agrees with experimental data, we were able to predict water solubility in close agreement with experimental measurements. Hence we demonstrate that a molecular modeling and simulation approach may provide quantitative support to experimental programs in this area. In addition, our simulation results shed light into the molecular mechanism of water extraction, the critical role of TBP, and the structural forms of water molecules both at the interface and in the bulk of the organic phase. Specifically, it is found that water molecules are

  15. 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

  16. Radioactive Demonstration of Caustic Recovery from Low-Level Alkaline Nuclear Waste by an Electrochemical Separation Process

    SciTech Connect

    Hobbs, D.T.

    1998-04-01

    Bench-scale radioactive tests successfully demonstrated an electrochemical process for the recovery of sodium hydroxide (caustic) from Decontaminated Salt Solution produced from the In-Tank Precipitation and Effluent Treatment Processes at the Savannah River Site (SRS). This testing evaluated two membranes: an organic-based membrane, Nafion Type 350, manufactured by E. I. duPont de Nemours {ampersand} Company, Inc. (DuPont) and an inorganic-based membrane, NAS D, being developed by Ceramatec. Both membranes successfully separated caustic from radioactive SRS waste.Key findings of the testing indicate the following attributes and disadvantages of each membrane. The commercially-available Nafion membrane proved highly conductive. Thus, the electrochemical cell can operate at high current density minimizing the number of cells at the desired volumetric processing rate. Testing indicated cesium transported across the Nafion membrane into the caustic product. Therefore, the caustic product will contain low-levels of radioactive cesium due to the presence of {sup 134,137}Cs in the waste feed. To meet customer requirements, a post treatment stage may prove necessary to remove radioactive cesium resulting in increased overall process costs and decreased cost savings. In contrast to the Nafion membrane, the NAS D membrane demonstrated the production of caustic with much lower levels of gamma radioactivity ({sup 137}Cs activity was {lt} 51 dpm/g). Therefore, the caustic product could possibly release for onsite/offsite use without further treatment. The NAS D membrane remains in the development stage and does not exist as a commercial product. Operating costs and long-term membrane durability remain unknown.Caustic recovery has been successfully demonstrated in a bench-scale, 2-compartment electrochemical reactor operated for brief periods of time with simulated and radioactive waste solutions and two different types of membranes. The next phase of testing should be directed

  17. Compaction of granular materials: numerical simulation of "elastic" compression and pressure solution creep

    NASA Astrophysics Data System (ADS)

    Bernabe, Y.; Evans, J.

    2012-12-01

    In a previous work we investigated stress transfer in a pair of grain contacts undergoing pressure solution (PS) creep, showed that stress transfer resulted in a significant decrease in overall strain rate, and concluded that PS creep rates of a randomly packed granular aggregate should be affected by packing evolution and the formation of new contacts during creep. To test these conclusions further, we are numerically simulating the "elastic" hydrostatic compression of a random pack of spheres, using a numerical method similar to that of Cundall and Strack [1979]. We assumed that the spheres were frictionless (i.e., spheres in contact only interacted through normal forces) and that the contact forces obeyed the non-linear Digby [1981] model. In order to determine the PS creep compression of the sphere pack subjected to a constant confining pressure pc, we calculated the thicknesses of the dissolved layers at each individual grain contact during a small time increment and, from these, the overall deformation of the sphere pack. We used an analytical expression discussed in our previous paper and originating from Lehner and Leroy [2004]. During these simulations, we also computed the mean coordination number of the grain contact z, the effective bulk modulus K of the sphere pack and others parameters characterizing the topological and mechanical properties of the sphere assembly. Our results show strong non-linear increase of z and K with pc during "elastic" compression and, with time, during PS creep. The packing rearrangements associated with PS creep produce complex time dependence of the overall deformation ɛ(t). We observed a regular transition from ɛ∝t^3/4 at early times (i.e., less than 0.1 years) and ɛ∝t^1/3 at late times (i.e., more than 1000 years). Cundall, P.A., and O.D.L. Strack (1979), A discrete numerical model for granular assemblies, Geotech., 29, 47-65. Digby, P.J. (1981), The effective elastic moduli of porous rocks, J. Appl. Mech., 48, 803

  18. Solvent controlled ion association in structured copolymers: Molecular dynamics simulations in dilute solutions

    NASA Astrophysics Data System (ADS)

    Aryal, Dipak; Perahia, Dvora; Grest, Gary S.

    2015-09-01

    Tailoring the nature of individual segments within ion containing block co-polymers is one critical design tool to achieve desired properties. The local structure including the size and distribution of the ionic blocks, as well as the long range correlations, are crucial for their transport ability. Here, we present molecular dynamics simulations on the effects of varying the concentrations of the ionizable groups on the conformations of pentablock ionomer that consist of a center block of ionic sulfonated styrene tethered to polyethylene and terminated by a bulky substituted styrene in dilute solutions. Sulfonation fractions f (0 ≤ f ≤ 0.55), spanning the range from ionomer to polyelectrolytes, were studied. Results for the equilibrium conformation of the chains in water and a 1:1 mixture of cyclohexane and heptane are compared to that in implicit poor solvents with dielectric constants ɛ = 1.0 and 77.73. In water, the pentablock collapses with the sulfonated groups on the outer surface. As f increases, the ionic, center block increasingly segregates from the hydrophobic regions. In the 1:1 mixture of cyclohexane and heptane, the flexible blocks swell, while the center ionic block collapses for f > 0. For f = 0, all blocks swell. In both implicit poor solvents, the pentablock collapses into a nearly spherical shape for all f. The sodium counterions disperse widely throughout the simulation cell for both water and ɛ = 77.73, whereas for ɛ = 1.0 and mixture of cyclohexane and heptane, the counterions largely condense onto the collapsed pentablock.

  19. Electron beam simulation from gun to collector: Towards a complete solution

    SciTech Connect

    Mertzig, R. Shornikov, A. Wenander, F.; Beebe, E.; Pikin, A.

    2015-01-09

    An electron-beam simulation technique for high-resolution complete EBIS/T modelling is presented. The technique was benchmarked on the high compression HEC{sup 2} test-stand with an electron beam current, current density and energy of 10 A, 10 kA/cm{sup 2} and 49.2 keV, and on the immersed electron beam at REXEBIS for electron beam characteristics of 0.4 A, 200 A/cm{sup 2} and 4.5 keV. In both Brillouin-like and immersed beams the electron-beam radius varies from several millimeters at the gun, through some hundreds of micrometers in the ionization region to a few centimeters at the collector over a total length of several meters. We report on our approach for finding optimal meshing parameters, based on the local beam properties such as magnetic field-strength, electron energy and beam radius. This approach combined with dividing the problem domain into sub-domains, and subsequent splicing of the local solutions allowed us to simulate the beam propagation in EBISes from the gun to the collector using a conventional PC in about 24–36 h. Brillouin-like electron beams propagated through the complete EBIS were used to analyze the beam behavior within the collector region. We checked whether elastically reflected paraxial electrons from a Brillouin-like beam will escape from the collector region and add to the loss current. We have also studied the power deposition profiles as function of applied potentials using two electrode geometries for a Brillouin-like beam including the effects of backscattered electrons.

  20. Reactive solute transport in streams. 2. Simulation of a pH modification experiment

    USGS Publications Warehouse

    Runkel, R.L.; McKnight, Diane M.; Bencala, K.E.; Chapra, S.C.

    1996-01-01

    We present an application of an equilibrium-based solute transport model to a pH-modification experiment conducted on the Snake River, an acidic, metal-rich stream located in the Rocky Mountains of Colorado. During the experiment, instream pH decreased from 4.2 to 3.2, causing a marked increase in dissolved iron concentrations. Model application requires specification of several parameters that are estimated using tracer techniques, mass balance calculations, and geochemical data. Two basic questions are addressed through model application: (1) What are the processes responsible for the observed increase in dissolved iron concentrations? (2) Can the identified processes be represented within the equilibrium-based transport model? Simulation results indicate that the increase in iron was due to the dissolution of hydrous iron oxides and the photoreduction of ferric iron. Dissolution from the streambed is represented by considering a trace compartment consisting of freshly precipitated hydrous iron oxide and an abundant compartment consisting of aged precipitates that are less soluble. Spatial variability in the solubility of hydrous iron oxide is attributed to heterogeneity in the streambed sediments, temperature effects, and/or variability in the effects of photoreduction. Solubility products estimated via simulation fall within a narrow range (pK(sp) from 40.2 to 40.8) relative to the 6 order of magnitude variation reported for laboratory experiments (pK(sp) from 37.3 to 43.3). Results also support the use of an equilibrium-based transport model as the predominate features of the iron and p H profiles are reproduced. The model provides a valuable tool for quantifying the nature and extent of pH- dependent processes within the context of hydrologic transport.