Radionuclide Transport Modeling of Diffusion Cell Experiments Specific to a Backfill Barrier in a Salt Repository

1983 ◽  
Vol 26 ◽  
Author(s):  
Harold M. Anderson ◽  
John M. Pietz ◽  
Douglas M. Smith
Keyword(s):  
Transport Model ◽  
Finite Difference Methods ◽  
Solution Technique ◽  
Radionuclide Transport ◽  
Diffusion Cell ◽  
Radionuclide Migration ◽  
Integral Equation Approach ◽  
Cell Data ◽  
Diffusion Cell Experiments

ABSTRACTExperimental radionuclide migration diffusion cell data have been collected as part of the WIPP Waste Package Performance Program. This data was collected under conditions approximating geologic isolation of a backfill barrier in a salt repository. The experiments are designed to aid in the evaluation of engineered backfill barriers.This paper describes a radionuclide transport model designed to aid interpreting experimental diffusion cell migration data and eventually to simulate the long-term effectiveness of the backfill barrier in a salt repository. The model is designed to test a variety of expressions representative of potential mechanisms for retardation within the backfill for the best-fit with experimental data. From the comparison, the aim is to select the appropriate mechanism from the host of potential mechanisms for retardation. The model employs a novel integral equation approach to the solution of the transport equation with nonlinear retardation terms. The solution technique used in this model is a semi-analytical, iterative method for the general nonlinear problem. It is felt the technique offers improved computational efficiency over comparable finite difference methods.Comparisons between experimental migration diffusion cell data and the model predictions are presented in this paper. Tentative conclusions concerning the importance of the retardation mechanism to radionuclide transport in the backfill barrier will be drawn.

Nonlinear Concentration Effects on Radionuclide Diffusion and Mobility in Compacted Bentonite.

1984 ◽  
Vol 44 ◽  
Author(s):  
Harold M. Anderson ◽  
Frank S. Chiao
Keyword(s):  
Transport Model ◽  
Freundlich Isotherm ◽  
Migration Behavior ◽  
Radionuclide Migration ◽  
Concentration Effects ◽  
Compacted Bentonite ◽  
Numerical Studies ◽  
Highly Nonlinear ◽  
Integral Equation Approach

AbstractThis paper examines some previously reported experimental results on the migration behavior of selected radionuclides in compacted bentonite and demonstrates that a much better agreement between observed and theoretically predicted migration behavior can be obtained when the model considers nonlinear concentration effects. The radionuclide transport model used in this study employs a semianalytic, integral equation approach to the solution of the diffusion equation with nonlinear retardation mechanisms. The effect of radionuclide concentration on species mobility is modeled as a highly nonlinear Freundlich isotherm.Several empirical correlations using the Freundlich isotherm form for retardation are presented and are shown to account for the deviation from linearity in the diffusion model for migration behavior. These correlations are then used in further numerical studies of long term backfill barrier performance for 3 and 4 member chain species after a hypothetical canister failure. The overall importance of nonlinear concentration effects to radionuclide migration estimation is discussed.

scholarly journals Long-Term Exposure to Fine and Coarse Particulate Matter and COVID-19 Incidence and Mortality Rate in Chile during 2020

2021 ◽  
Vol 18 (14) ◽  
pp. 7409
Author(s):  
Macarena Valdés Salgado ◽  
Pamela Smith ◽  
Mariel Opazo ◽  
Nicolás Huneeus
Keyword(s):  
Mortality Rate ◽  
Incidence Rate ◽  
Air Pollutants ◽  
Negative Binomial ◽  
Transport Model ◽  
Surface Concentration ◽  
Mortality Rates ◽  
Incidence And Mortality ◽  
Pm2.5 And Pm10

Background: Several countries have documented the relationship between long-term exposure to air pollutants and epidemiological indicators of the COVID-19 pandemic, such as incidence and mortality. This study aims to explore the association between air pollutants, such as PM2.5 and PM10, and the incidence and mortality rates of COVID-19 during 2020. Methods: The incidence and mortality rates were estimated using the COVID-19 cases and deaths from the Chilean Ministry of Science, and the population size was obtained from the Chilean Institute of Statistics. A chemistry transport model was used to estimate the annual mean surface concentration of PM2.5 and PM10 in a period before the current pandemic. Negative binomial regressions were used to associate the epidemiological information with pollutant concentrations while considering demographic and social confounders. Results: For each microgram per cubic meter, the incidence rate increased by 1.3% regarding PM2.5 and 0.9% regarding PM10. There was no statistically significant relationship between the COVID-19 mortality rate and PM2.5 or PM10. Conclusions: The adjusted regression models showed that the COVID-19 incidence rate was significantly associated with chronic exposure to PM2.5 and PM10, even after adjusting for other variables.

scholarly journals Improvement of the long-term stability of ZnSnO thin film transistors by tungsten incorporation using a solution-process method

RSC Advances ◽  
2018 ◽  
Vol 8 (37) ◽  
pp. 20990-20995 ◽  
Author(s):  
Xiang Yang ◽  
Shu Jiang ◽  
Jun Li ◽  
Jian-Hua Zhang ◽  
Xi-Feng Li
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thin Film Transistors ◽  
Solution Process ◽  
Solution Technique ◽  
Term Stability ◽  
Long Term Stability ◽  
Process Method

In this paper, W-doped ZnSnO (WZTO) thin films and TFT devices are successfully fabricated by a wet-solution technique.

scholarly journals Mineralogical, numerical and analytical studies of the coupled oxidation of pyrite and coal

2003 ◽  
Vol 67 (2) ◽  
pp. 381-398 ◽  
Author(s):  
K. A. Evans ◽  
C. J. Gandy ◽  
S. A. Banwart
Keyword(s):  
Reactive Transport ◽  
Transport Model ◽  
Pyrite Oxidation ◽  
Spoil Heap ◽  
Reaction Fronts ◽  
Order Of Magnitude ◽  
Magnitude Variation ◽  
Discharge Chemistry ◽  
Analytical Expressions

Mineralogical, bulk and field leachate compositions are used to identify important processes governing the evolution of discharges from a coal spoil heap in County Durham. These processes are incorporated into a numerical one-dimensional advective-kinetic reactive transport model which reproduces field results, including gas compositions, to within an order of magnitude. Variation of input parameters allows the effects of incorrect initial assumptions on elemental profiles and discharge chemistry to be assessed. Analytical expressions for widths and speeds of kinetic reaction fronts are developed and used to predict long-term development of mineralogical distribution within the heap. Results are consistent with observations from the field site. Pyrite oxidation is expected to dominate O2 consumption in spoil heaps on the decadal timescale, although C oxidation may stabilize contaminants in effluents on the centennial scale.

scholarly journals Top-Down NOX Emissions of European Cities Based on the Downwind Plume of Modelled and Space-Borne Tropospheric NO2 Columns

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2893 ◽  
Author(s):  
Willem W. Verstraeten ◽  
Klaas Folkert Boersma ◽  
John Douros ◽  
Jason E. Williams ◽  
Henk Eskes ◽  
...  
Keyword(s):  
Urban Areas ◽  
Transport Model ◽  
Nox Emissions ◽  
Inventory Data ◽  
Ozone Monitoring Instrument ◽  
Top Down ◽  
Chemistry Transport Model ◽  
European Cities ◽  
Tropospheric No2

Top-down estimates of surface NOX emissions were derived for 23 European cities based on the downwind plume decay of tropospheric nitrogen dioxide (NO2) columns from the LOTOS-EUROS (Long Term Ozone Simulation-European Ozone Simulation) chemistry transport model (CTM) and from Ozone Monitoring Instrument (OMI) satellite retrievals, averaged for the summertime period (April–September) during 2013. Here we show that the top-down NOX emissions derived from LOTOS-EUROS for European urban areas agree well with the bottom-up NOX emissions from the MACC-III inventory data (R2 = 0.88) driving the CTM demonstrating the potential of this method. OMI top-down NOX emissions over the 23 European cities are generally lower compared with the MACC-III emissions and their correlation is slightly lower (R2 = 0.79). The uncertainty on the derived NO2 lifetimes and NOX emissions are on average ~55% for OMI and ~63% for LOTOS-EUROS data. The downwind NO2 plume method applied on both LOTOS-EUROS and OMI tropospheric NO2 columns allows to estimate NOX emissions from urban areas, demonstrating that this is a useful method for real-time updates of urban NOX emissions with reasonable accuracy.

scholarly journals Validation of nine years of MOPITT V5 NIR using MOZAIC/IAGOS measurements: biases and long-term stability

2014 ◽  
Vol 7 (11) ◽  
pp. 3783-3799 ◽  
Author(s):  
A. T. J. de Laat ◽  
I. Aben ◽  
M. Deeter ◽  
P. Nédélec ◽  
H. Eskes ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transport Model ◽  
A Priori ◽  
Validation Data ◽  
Chemistry Transport Model ◽  
Large Variability ◽  
Long Term Stability ◽  
Spatio Temporal ◽  
Good Agreement

Abstract. Validation results from a comparison between Measurement Of Pollution In The Troposphere (MOPITT) V5 Near InfraRed (NIR) carbon monoxide (CO) total column measurements and Measurement of Ozone and Water Vapour on Airbus in-service Aircraft (MOZAIC)/In-Service Aircraft for a Global Observing System (IAGOS) aircraft measurements are presented. A good agreement is found between MOPITT and MOZAIC/IAGOS measurements, consistent with results from earlier studies using different validation data and despite large variability in MOPITT CO total columns along the spatial footprint of the MOZAIC/IAGOS measurements. Validation results improve when taking the large spatial footprint of the MOZAIC/IAGOS data into account. No statistically significant drift was detected in the validation results over the period 2002–2010 at global, continental and local (airport) scales. Furthermore, for those situations where MOZAIC/IAGOS measurements differed from the MOPITT a priori, the MOPITT measurements clearly outperformed the MOPITT a priori data, indicating that MOPITT NIR retrievals add value to the MOPITT a priori. Results from a high spatial resolution simulation of the chemistry-transport model MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) showed that the most likely explanation for the large MOPITT variability along the MOZAIC-IAGOS profile flight path is related to spatio-temporal CO variability, which should be kept in mind when using MOZAIC/IAGOS profile measurements for validating satellite nadir observations.

scholarly journals Regional and intercontinental pollution signatures on modeled and measured PAN at northern mid-latitude mountain sites

2018 ◽  
Author(s):  
Arlene M. Fiore ◽  
Emily V. Fischer ◽  
Shubha Pandey Deolal ◽  
Oliver Wild ◽  
Dan Jaffe ◽  
...  
Keyword(s):  
Transport Model ◽  
Ozone Production ◽  
Anthropogenic Emissions ◽  
Chemical Transport Model ◽  
Reservoir Species ◽  
Remote Troposphere ◽  
Global Chemical Transport Model ◽  
Peroxy Acetyl Nitrate ◽  
Source Receptor Relationships

Abstract. Peroxy acetyl nitrate (PAN) is the most important reservoir species for nitrogen oxides (NOx) in the remote troposphere. Upon decomposition in remote regions, PAN promotes efficient ozone production. We evaluate monthly mean PAN abundances from global chemical transport model simulations (HTAP1) for 2001 with measurements from five northern mid-latitude mountain sites (four European and one North American). The multi-model mean generally captures the observed monthly mean PAN but individual models simulate a factor of ~ 4–8 range in monthly abundances. We quantify PAN source-receptor relationships at the measurement sites with sensitivity simulations that decrease regional anthropogenic emissions of PAN (and ozone) precursors by 20 % from North America (NA), Europe (EU), and East Asia (EA). The HTAP1 models attribute more of the observed PAN at Jungfraujoch (Switzerland) to emissions in NA and EA, and less to EU, than a prior trajectory-based estimate. The trajectory-based and modeling approaches agree that EU emissions play a role in the observed springtime PAN maximum at Jungfraujoch. The signal from anthropogenic emissions on PAN is strongest at Jungfraujoch and Mount Bachelor (Oregon, U.S.A.) during April. In this month, PAN source-receptor relationships correlate both with model differences in regional anthropogenic volatile organic compound (AVOC) emissions and with ozone source-receptor relationships. PAN observations at mountaintop sites can thus provide key information for evaluating models, including links between PAN and ozone production and source-receptor relationships. Establishing routine, long-term, mountaintop measurements is essential given the large observed interannual variability in PAN.

ASSESSMENT OF PERMEABILITY BEHAVIOR OF BERBERINE CHLORIDE ACROSS GOAT INTESTINAL MEMBRANE IN PRESENCE OF NATURAL BIOPOTENTIATOR CURCUMIN

INDIAN DRUGS ◽  
2021 ◽  
Vol 58 (4) ◽  
pp. 23-27
Author(s):  
Sarika Narade ◽  
Yogesh Pore ◽  
◽  
Keyword(s):  
Efflux Pump ◽  
Diffusion Cell ◽  
Apparent Permeability ◽  
Franz Diffusion Cell ◽  
Permeability Characteristics ◽  
Berberine Chloride ◽  
Intestinal Membrane ◽  
Permeability Studies ◽  
Cell Data ◽  
Intestinal Efflux

The present study investigates the influence of co-administration of different concentrations (2, 6, and 10 mg) of curcumin on goat intestinal permeability of berberine chloride (BBC) using Franz diffusion cell. Data obtained in triplicate from permeability studies were used to calculate percentage cumulative drug release (% CDR), apparent permeability (Papp), flux (J) and enhancement ratio (ER). Co-administration of 6 mg concentration of curcumin with BBC was found to be optimum to enhance the permeability of BBC up to 23.92 ± 0.78 % CDR, over control (8.49 ± 1.45 % CDR). At the optimized concentration of curcumin, permeability characteristics were improved significantly compared to control. The present study reveals the beneficial effect of co-administration of curcumin (6 mg) to promote membrane permeability of BBC which would be expected to improve its bioavailability, thereby therapeutic efficacy. The effect could be attributed to curcumin-mediated inhibition of intestinal efflux pump P-gp, acting as an absorption barrier for BBC.

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