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Sample records for reactive barriers final

  1. PERMEABLE REACTIVE BARRIERS FOR GROUNDWATER REMEDIATION

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  2. PERMEABLE REACTIVE BARRIERS FOR GROUND WATER REMEDIATION

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  3. In Situ Removal of Cadmium and Chromium from Groundwater Using ZeoTech Reactive Barriers. Final Report for period October 1999-April 2000.

    SciTech Connect

    Rostami, H.; Silverstrim, T.

    2000-05-01

    The use of novel permeable reactive barrier (PRB) to remove and to stabilize heavy metals such as Cd and Cr from groundwater was studied. The barrier was made of fly ash, an appropriate material for high volume ion exchange. The fly ash is combined with chemicals to create activated ash material or AAM. PRB's, made from activated fly ash, AAM-PRB's, were used to treat contaminated water in situ. It was shown that the AAM-PRB was effective in removal of Cd and Cr from contaminated water, while at the same time utilizing waste fly ash that otherwise would be have to be landfilled.

  4. EVALUATION OF PERMEABLE REACTIVE BARRIER PERFORMANCE

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology represents a passive option for long-term treatment of ground-water contamination. PRBs are a potentially more cost-effective treatment option for a variety of dissolved contaminants, such as certain types of chlorinated solvents, ...

  5. EPA/ITRC-RTDF permeable reactive barrier short course. Permeable reactive barriers: Application and deployment

    SciTech Connect

    1999-11-01

    This report focuses on the following: Permeable Reactive Barriers: Application and Deployment; Introduction to Permeable Reactive Barriers (PRBs) for Remediating and Managing Contaminated Groundwater in Situ; Collection and Interpretation of Design Data 1: Site Characterization for PRBs; Reactive Materials: Zero-Valent Iron; Collection and Interpretation of Design Data 2: Laboratory and Pilot Scale Tests; Design Calculations; Compliance Monitoring, Performance Monitoring and Long-Term Maintenance for PRBs; PRB Emplacement Techniques; PRB Permitting and Implementation; Treatment of Metals; Non-Metallic Reactive Materials; Economic Considerations for PRB Deployment; and Bibliography.

  6. EPA/ITRC-RTDF permeable reactive barrier short course. Permeable reactive barriers: Application and deployment

    SciTech Connect

    Not Available

    1999-01-01

    This report focuses on the following: Permeable Reactive Barriers: Application and Deployment; Introduction to Permeable Reactive Barriers (PRBs) for Remediating and Managing Contaminated Groundwater in Situ; Collection and Interpretation of Design Data 1: Site Characterization for PRBs; Reactive Materials: Zero-Valent Iron; Collection and Interpretation of Design Data 2: Laboratory and Pilot Scale Tests; Design Calculations; Compliance Monitoring, Performance Monitoring and Long-Term Maintenance for PRBs; PRB Emplacement Techniques; PRB Permitting and Implementation; Treatment of Metals; Non-Metallic Reactive Materials; Economic Considerations for PRB Deployment; and Bibliography.

  7. Clamshell excavation of a permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Molfetta, Antonio Di; Sethi, Rajandrea

    2006-06-01

    Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.

  8. Reactive Membrane Barriers for Containment of Subsurface Contamination

    SciTech Connect

    William A. Arnold; Edward L. Cussler

    2007-02-26

    factor of three when groundwater was used in place of deionized water. The performance of high density polyethylene (HDPE) membranes containing Fe{sup 0} was then evaluating using carbon tetrachloride as the target contaminant. Only with a hydrophilic additive (glycerol), was the iron able to extend lag times. Lag times were increased by a factor of 15, but only 2-3% of the iron was used, likely due to formation of oxide precipitates on the iron surface, which slowed the reaction. With thicker membranes and lower carbon tetrachloride concentrations, it is expected that performance will improve. Previous models for reactive membranes were also extended. The lag time is a measurement of when the barrier is breached, but contaminants do slowly leak through prior to the lag time. Thus, two parameters, the leakage and the kill time, were developed to determine when a certain amount of pollutant has escaped (the kill time) or when a given exposure (concentration x time) occurs (the leakage). Finally, a model was developed to explain the behavior of mobile reaction products in reactive barrier membranes. Although the goal of the technology is to avoid such products, it is important to be able to predict how these products will behave. Interestingly, calculations show that for any mobile reaction products, one half of the mass will diffuse into the containment area and one half will escape, assuming that the volumes of the containment area and the surrounding environment are much larger than the barrier membrane. These parameters/models will aid in the effective design of barrier membranes.

  9. Reactive barriers for {sup 137}Cs retention

    SciTech Connect

    KRUMHANSL,JAMES L.; BRADY,PATRICK V.; ANDERSON,HOWARD L.

    2000-05-19

    {sup 137}Cs was dispersed globally by cold war activities and, more recently, by the Chernobyl accident. Engineered extraction of {sup 137}Cs from soils and groundwaters is exceedingly difficult. Because the half life of {sup 137}Cs is only 30.2 years, remediation might be more effective (and less costly) if {sup 137}Cs bioavailability could be demonstrably limited for even a few decades by use of a reactive barrier. Essentially permanent isolation must be demonstrated in those few settings where high nuclear level wastes contaminated the environment with {sup 135}Cs (half life 2.3x10{sup 6} years) in addition to {sup 137}Cs. Clays are potentially a low-cost barrier to Cs movement, though their long-term effectiveness remains untested. To identify optimal clays for Cs retention Cs resorption was measured for five common clays: Wyoming Montmorillonite (SWy-1), Georgia Kaolinites (KGa-1 and KGa-2), Fithian Illite (F-Ill), and K-Metabentonite (K-Mbt). Exchange sites were pre-saturated with 0.16 M CsCl for 14 days and readily exchangeable Cs was removed by a series of LiNO{sub 3} and LiCl washes. Washed clay were then placed into dialysis bags and the Cs release to the deionized water outside the bags measured. Release rates from 75 to 139 days for SWy-1, K-Mbt and F- 111 were similar; 0.017 to 0.021% sorbed Cs released per day. Both kaolinites released Cs more rapidly (0.12 to 0.05% of the sorbed Cs per day). In a second set of experiments, clays were doped for 110 days and subjected to an extreme and prolonged rinsing process. All the clays exhibited some capacity for irreversible Cs uptake so most soils have some limited ability to act as a natural barrier to Cs migration. However, the residual loading was greatest on K-Mbt ({approximately} 0.33 wt% Cs). Thus, this clay would be the optimal material for constructing artificial reactive barriers.

  10. Automated Impedance Tomography for Monitoring Permeable Reactive Barrier Health

    SciTech Connect

    LaBrecque, D J; Adkins, P L

    2009-07-02

    The objective of this research was the development of an autonomous, automated electrical geophysical monitoring system which allows for near real-time assessment of Permeable Reactive Barrier (PRB) health and aging and which provides this assessment through a web-based interface to site operators, owners and regulatory agencies. Field studies were performed at four existing PRB sites; (1) a uranium tailing site near Monticello, Utah, (2) the DOE complex at Kansas City, Missouri, (3) the Denver Federal Center in Denver, Colorado and (4) the Asarco Smelter site in East Helena, Montana. Preliminary surface data over the PRB sites were collected (in December, 2005). After the initial round of data collection, the plan was modified to include studies inside the barriers in order to better understand barrier aging processes. In September 2006 an autonomous data collection system was designed and installed at the EPA PRB and the electrode setups in the barrier were revised and three new vertical electrode arrays were placed in dedicated boreholes which were in direct contact with the PRB material. Final data were collected at the Kansas City, Denver and Monticello, Utah PRB sites in the fall of 2007. At the Asarco Smelter site in East Helena, Montana, nearly continuous data was collected by the autonomous monitoring system from June 2006 to November 2007. This data provided us with a picture of the evolution of the barrier, enabling us to examine barrier changes more precisely and determine whether these changes are due to installation issues or are normal barrier aging. Two rounds of laboratory experiments were carried out during the project. We conducted column experiments to investigate the effect of mineralogy on the electrical signatures resulting from iron corrosion and mineral precipitation in zero valent iron (ZVI) columns. In the second round of laboratory experiments we observed the electrical response from simulation of actual field PRBs at two sites: the

  11. CARBON-BASED REACTIVE BARRIER FOR NITRATE ...

    EPA Pesticide Factsheets

    Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constructed for in-situ bioremediation of a ground water nitrate plume caused by leakage from a swine CAFO (concentrated animal feeding operation) lagoon. The swine CAFO, located in Logan County, Oklahoma, was in operation from 1992-1999. The overall site remediation strategy includes an ammonia recovery trench to intercept ammonia-contaminated ground water and a hay straw PRB which is used to intercept a nitrate plume caused by nitrification of sorbed ammonia. The PRB extends approximately 260 m to intercept the nitrate plume. The depth of the trench averages 6 m and corresponds to the thickness of the surficial saturated zone; the width of the trench is 1.2 m. Detailed quarterly monitoring of the PRB began in March, 2004, about 1 year after construction activities ended. Nitrate concentrations hydraulically upgradient of the PRB have ranged from 23 to 77 mg/L N, from 0 to 3.2 mg/L N in the PRB, and from 0 to 65 mg/L N hydraulically downgradient of the PRB. Nitrate concentrations have generally decreased in downgradient locations with successive monitoring events. Mass balance considerations indicate that nitrate attenuation is dominantly from denitrification but with some component of

  12. PERMEABLE REACTIVE BARRIER TECHNOLOGIES FOR CONTAMINANT REMEDIATION

    EPA Science Inventory

    Environmental scientists are generally familiar with the concept of barriers for restricting the movement of contaminant plumes in ground water. Such barriers are typically constructed of highly impermeable emplacements of materials such as grouts, slurries, or sheet pilings to ...

  13. Reactive composite compositions and mat barriers

    SciTech Connect

    Langton, Christine A.; Narasimhan, Rajendran; Karraker, David G.

    2001-01-01

    A hazardous material storage area has a reactive multi-layer composite mat which lines an opening into which a reactive backfill and hazardous material are placed. A water-inhibiting cap may cover the hazardous material storage area. The reactive multi-layer composite mat has a backing onto which is placed an active layer which will neutralize or stabilize hazardous waste and a fronting layer so that the active layer is between the fronting and backing layers. The reactive backfill has a reactive agent which can stabilize or neutralize hazardous material and inhibit the movement of the hazardous material through the hazardous material storage area.

  14. TREATMENT OF INORGANIC CONTAMINANTS USING PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers are an emerging alternative to traditional pump and treat systems for groundwater remediation. This technique has progressed rapidly over the past decade from laboratory bench-scale studies to full-scale implementation. Laboratory studies indicate the ...

  15. INTRODUCTION TO PERMEABLE REACTIVE BARRIERS FOR GROUND WATER REMEDIATION

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  16. PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  17. REGULATORY ASPECTS AND IMPLEMENTATION FOR PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  18. Iron Nanoparticles in Reactive Environmental Barriers

    SciTech Connect

    Nuxoll, Eric E.; Shimotori, Tsutomu; Arnold, William A.; Cussler, Edward L.

    2003-09-23

    Zero-valent iron is cheap, environmentally innocuous, and effective at reducing chlorinated organics. It has, as a result, become a popular candidate for remediating aquifers contaminated with trichloroethylene and other halogenated pollutants. In this paper, we discuss one such system, where iron nanoparticles are synthesized and incorporated into polyvinyl alcohol membranes, forming water-permeable barriers to these pollutants. These barriers are tested against a variety of contaminants, including carbon tetrachloride, copper, and chromate.

  19. Monitoring of Zero-Valent Iron Permeable Reactive Barriers: Electrical Properties and Barrier Aging

    NASA Astrophysics Data System (ADS)

    Labrecque, D. J.; Adkins, P. L.; Slater, L. D.; Versteeg, R.; Sharpe, R.

    2007-12-01

    An innovative method of groundwater remediation invented in the 1990"s, Permeable Reactive Barriers, use sand-sized grains of scrap iron placed in trenches or injected under pressure to remediate a number of organic and inorganic contaminants. Monitoring the aging of these barriers becomes increasingly important as many of these barriers approach their predicted life spans. In-situ resistivity and induced polarization studies have been conducted at six barriers at four different sites: Monticello, Utah; the Denver Federal Center; Kansas City, Missouri; and East Helena, Montana. As some barriers tend to age dramatically faster than others, for this study we consider low permeability barriers as of greater age, as "old" barriers tend to loose permeability rather than exhaust reactive materials. One complicating factor is that two of the barriers studied appear to have issues related to installation. One site, the former Asarco Smelter Site near East Helena, Montana, has been instrumented with an autonomous monitoring system allowing continuous monitoring of the evolution of a relatively new (less than three years old) barrier. The barrier showed surprisingly rapid evolution over the first year of monitoring with changes in both resistivity and chargeability of tens of percent per month. In general, the electrical properties of all of the barriers studied follow a pattern. New barriers are fairly resistive with in-situ conductivity only a few times background (outside the barrier) values. Older barriers get increasingly conductive, with failed barriers showing values of over 100 S/m. The induced polarization response is more complicated. Chargeability values increase over time for young barriers, are largest for healthy barriers in the middle of their lifespan, and decrease as the barrier ages.

  20. Advances in Permeable Reactive Barrier Technologies

    DTIC Science & Technology

    2002-08-01

    technical methods, such as jetting and hydraulic fracturing , has improved the ability to access deeper aquifers. Table 1 describes the established and...34, Cape Canaveral Air Station, FL. Hydraulic Fracturing 120 A series of wells are installed along the length of the PRB. A vertical fracture is...especially helpful with deep instal- lation methods, such as hydraulic fracturing , where the barrier installed is just a few inches thick. A second, new type

  1. Permeable Reactive Barriers for Treatment of Cr6

    EPA Science Inventory

    Several options are available for treatment of hexavalent chromium (Cr(VI)) in groundwater using the permeable reactive barrier (PRB) approach. They include conventional trench-and-fill systems, chemical redox curtains, and organic carbon redox curtains. Each of these PRB syste...

  2. MICROBIAL CHARACTERIZATION OF MANURE BASED PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    The implementation of permeable reactive barriers (PRB) provides a viable option for the remediation of contaminants of environmental significance such as dissolved metals (i.e., chromium), chlorinated solvents, and nitrate/ammonia. The designs of PRBs are usually based on the a...

  3. COLLECTION OF DESIGN DATA: SITE CHARACTERIZATION FOR PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers (PRBs) for the restoration of contaminated ground water are no longer innovative. PRBs have evolved from innovative to accepted, standard practice, for the containment and treatment of a variety of contaminants in ground water. Like any remedial tech...

  4. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED

    EPA Science Inventory

    This presentation will provide an overview of research efforts at EPA on the application, monitoring, and performance of Permeable Reactive Barriers (PRBs) for groundwater restoration. Over the past 10 years, research projects conducted by research staff at EPA's National Risk M...

  5. PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF INORGANIC CONTAMINANTS

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology is an in-situ approach for groundwater remediation that couples subsurface flow management with a passive chemical or biochemical treatment zone. The development and application of the PRB technology has progressed over the last de...

  6. Cryogenic Barrier Demonstration Project. Final report

    SciTech Connect

    Johnson, L.A.; Yarmak, E.; Long, E.L.

    2000-03-01

    A long-term frozen soil barrier was implemented at the HRE (Homogeneous Reactor Experiment) Pond facility at the Oak Ridge National Laboratory in 1997. This was performed to verify the technical feasibility and costs of deploying a frozen barrier at a radiologically contaminated site. Work began in September 1996 and progressed through to December 1999. The frozen barrier has been operational since November 1997. Verification of the barrier integrity was performed independently by the EPA's SITE Program. This project showed frozen barriers offer a proven technology to retain below grade hazardous substances at relatively low costs with minimal effect on the environment.

  7. Microbiological characteristics in a zero-valent iron reactive barrier.

    PubMed

    Gu, Baohua; Watson, David B; Wu, Liyou; Phillips, Debra H; White, David C; Zhou, Jizhong

    2002-08-01

    Zero-valent iron (Fe0)-based permeable reactive barrier treatment has been generating great interest for passive groundwater remediation, yet few studies have paid particular attention to the microbial activity and characteristics within and in the vicinity of the Fe0-barrier matrix. The present study was undertaken to evaluate the microbial population and community composition in the reducing zone of influence by Fe0 corrosion in the barrier at the Oak Ridge Y-12 Plant site. Both phospholipid fatty acids and DNA analyses were used to determine the total microbial population and microbial functional groups, including sulfate-reducing bacteria, denitrifying bacteria, and methanogens, in groundwater and soil/iron core samples. A diverse microbial community was identified in the strongly reducing Fe0 environment despite a relatively high pH condition within the Fe0 barrier (up to pH approximately 10). In comparison with those found in the background soil/groundwater samples, the enhanced microbial population ranged from approximately 1 to 3 orders of magnitude and appeared to increase from upgradient of the barrier to downgradient soil. In addition, microbial community composition appeared to change over time, and the bacterial types of microorganisms increased consistently as the barrier aged. DNA analysis indicated the presence of sulfate-reducing and denitrifying bacteria in the barrier and its surrounding soil. However, the activity of methanogens was found to be relatively low, presumably as a result of the competition by sulfate/metal-reducing bacteria and denitrifying bacteria because of the unlimited availability of sulfate and nitrate in the site groundwater. Results of this study provide evidence of a diverse microbial population within and in the vicinity of the iron barrier, although the important roles of microbial activity, either beneficially or detrimentally, on the longevity and enduring efficiency of the Fe0 barriers are yet to be evaluated.

  8. Microbiological characteristics in a zero-valent iron reactive barrier

    SciTech Connect

    Gu, Baohua; Watson, David B; Wu, Liyou; Phillips, Debra Helen; White, David C.; Zhou, Jizhong

    2002-01-01

    Zero-valent iron (Fe{sup 0})-based permeable reactive barrier treatment has been generating great interest for passive groundwater remediation, yet few studies have paid particular attention to the microbial activity and characteristics within and in the vicinity of the Fe{sup 0}-barrier matrix. The present study was undertaken to evaluate the microbial population and community composition in the reducing zone of influence by Fe{sup 0} corrosion in the barrier at the Oak Ridge Y-12 Plant site. Both phospholipid fatty acids and DNA analyses were used to determine the total microbial population and microbial functional groups, including sulfate-reducing bacteria, denitrifying bacteria, and methanogens, in groundwater and soil/iron core samples. A diverse microbial community was identified in the strongly reducing Fe{sup 0} environment despite a relatively high pH condition within the Fe{sup 0} barrier (up to pH {approx} 10). In comparison with those found in the background soil/groundwater samples, the enhanced microbial population ranged from {approx} 1 to 3 orders of magnitude and appeared to increase from upgradient of the barrier to downgradient soil. In addition, microbial community composition appeared to change overtime, and the bacterial types of microorganisms increased consistently as the barrier aged. DNA analysis indicated the presence of sulfate-reducing and denitrifying bacteria in the barrier and its surrounding soil. However, the activity of methanogens was found to be relatively low, presumably as a result of the competition by sulfate/metal-reducing bacteria and denitrifying bacteria because of the unlimited availability of sulfate and nitrate in the site groundwater. Results of this study provide evidence of a diverse microbial population within and in the vicinity of the iron barrier, although the important roles of microbial activity, either beneficially or detrimentally, on the longevity and enduring efficiency of the Fe{sup 0} barriers are yet

  9. Novel oximes as blood-brain barrier penetrating cholinesterase reactivators.

    PubMed

    Garcia, Gregory E; Campbell, Amy J; Olson, John; Moorad-Doctor, Deborah; Morthole, Venee I

    2010-09-06

    The US Army utilizes pralidoxime (2-PAM) for the reactivation of OP-inhibited AChE. While 2-PAM effectively reactivates acetylcholinesterase (AChE) in the body, it does not cross the blood-brain barrier (BBB) at therapeutically relevant levels. To address this problem of central nervous system AChE reactivation, novel sugar-oxime conjugates were utilized. These 'sugar-oximes' would potentially be transported across the BBB because they contain a sugar moiety which would be recognized by the facilitative glucose transporters. Eight previously reported, but understudied sugar-oximes, as well as six novel sugar-oximes were synthesized, and their ability to reactivate both human red blood cell AChE and plasma butyrylcholinesterase poisoned with DFP, paraoxon, sarin and VX were tested. The results show that the novel sugar-oxime 13c was more active than the other compounds with a reactivation potential similar to 2-PAM. The sugar-oxime 8b had low toxicity with a LD(50) of 1,590 mg/kg from a single IM dose in the guinea pig and >2,000 mg/kg IP in the mouse. Histopathological analysis showed that there were no apparent differences in hippocampus, heart, liver, kidney sciatic nerve, or skeletal muscle between treated and untreated animals. These results show that sugar-oximes can be effective reactivators and suggest that high treatment doses may be possible.

  10. AMELIORATION OF ACID MINE DRAINAGE USING REACTIVE MIXTURES IN PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    The generation and release of acidic drainage from mine wastes is an environmental problem of international scale. The use of zero-valent iron and/or iron mixtures in subsurface Permeable Reactive Barriers (PRB) presents a possible passive alternative for remediating acidic grou...

  11. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUNDWATER: VOLUME 3 MULTICOMPONENT REACTIVE TRANSPORT MODELING

    EPA Science Inventory

    Reactive transport modeling has been conducted to describe the performance of the permeable reactive barrier at the Coast Guard Support Center near Elizabeth City, NC. The reactive barrier was installed to treat groundwater contaminated by hexavalent chromium and chlorinated org...

  12. Analytical solutions for flow fields near continuous wall reactive barriers

    NASA Astrophysics Data System (ADS)

    Klammler, Harald; Hatfield, Kirk

    2008-05-01

    Permeable reactive barriers (PRBs) are widely applied for in-situ remediation of contaminant plumes transported by groundwater. Besides the goal of a sufficient contaminant remediation inside the reactive cell (residence time) the width of plume intercepted by a PRB is of critical concern. A 2-dimensional analytical approach is applied to determine the flow fields towards rectangular PRBs of the continuous wall (CW) configuration with and without impermeable side walls (but yet no funnel). The approach is based on the conformal mapping technique and assumes a homogeneous aquifer with a uniform ambient flow field. The hydraulic conductivity of the reactive material is furthermore assumed to exceed the conductivity of the aquifer by at least one order of magnitude as to neglect the hydraulic gradient across the reactor. The flow fields are analyzed regarding the widths and shapes of the respective capture zones as functions of the dimensions (aspect ratio) of the reactive cell and the ambient groundwater flow direction. Presented are an improved characterization of the advantages of impermeable side walls, a convenient approach to improved hydraulic design (including basic cost-optimization) and new concepts for monitoring CW PRBs. Water level data from a CW PRB at the Seneca Army Depot site, NY, are used for field demonstration.

  13. Advanced hydraulic fracturing methods to create in situ reactive barriers

    SciTech Connect

    Murdoch, L. |; Siegrist, B.; Vesper, S.

    1997-12-31

    Many contaminated areas consist of a source area and a plume. In the source area, the contaminant moves vertically downward from a release point through the vadose zone to an underlying saturated region. Where contaminants are organic liquids, NAPL may accumulate on the water table, or it may continue to migrate downward through the saturated region. Early developments of permeable barrier technology have focused on intercepting horizontally moving plumes with vertical structures, such as trenches, filled with reactive material capable of immobilizing or degrading dissolved contaminants. This focus resulted in part from a need to economically treat the potentially large volumes of contaminated water in a plume, and in part from the availability of construction technology to create the vertical structures that could house reactive compounds. Contaminant source areas, however, have thus far remained largely excluded from the application of permeable barrier technology. One reason for this is the lack of conventional construction methods for creating suitable horizontal structures that would place reactive materials in the path of downward-moving contaminants. Methods of hydraulic fracturing have been widely used to create flat-lying to gently dipping layers of granular material in unconsolidated sediments. Most applications thus far have involved filling fractures with coarse-grained sand to create permeable layers that will increase the discharge of wells recovering contaminated water or vapor. However, it is possible to fill fractures with other compounds that alter the chemical composition of the subsurface. One early application involved development and field testing micro-encapsulated sodium percarbonate, a solid compound that releases oxygen and can create aerobic conditions suitable for biodegradation in the subsurface for several months.

  14. Long-Term Monitoring of Permeable Reactive Barriers - Progress Report

    SciTech Connect

    Liang, L.

    2001-04-12

    The purpose of this project is to conduct collaborative research to evaluate and maximize the effectiveness of permeable reactive barriers (PRBs) with a broad-based working group including representatives from the U.S. Department of Energy (DOE), U.S. Department of Defense (DoD), and the U.S. Environmental Protection Agency (EPA). The Naval Facilities Engineering Service Center (NFESC) and its project partner, Battelle, are leading the DoD effort with funding from DoD's Environmental Security Technology Certification Program (ESTCP) and Strategic Environmental Research and Development Program (SERDP). Oak Ridge National Laboratory (ORNL) is coordinating the DOE effort with support from Subsurface Contaminant Focus Area (SCFA), a research program under DOEs Office of Science and Technology. The National Risk Management Research Laboratory's Subsurface Protection and Remediation Division is leading EPA's effort. The combined effort of these three agencies allows the evaluation of a large number of sites. Documents generated by this joint project will be reviewed by the participating agencies' principal investigators, the Permeable Barriers Group of the Remediation Technologies Development Forum (RTDF), and the Interstate Technology and Regulatory Cooperation (ITRC). The technical objectives of this project are to collect and review existing field data at selected PRB sites, identify data gaps, conduct additional measurements, and provide recommendations to DOE users on suitable long-term monitoring strategies. The specific objectives are to (1) evaluate geochemical and hydraulic performance of PRBs, (2) develop guidelines for hydraulic and geochemical characterization/monitoring, and (3) devise and implement long-term monitoring strategies through the use of hydrological and geochemical models. Accomplishing these objectives will provide valuable information regarding the optimum configuration and lifetime of barriers at specific sites. It will also permit

  15. Iron Hydroxy Carbonate Formation in Zerovalent Iron Permeable Reactive Barriers: Characterization and Evaluation of Phase Stability

    EPA Science Inventory

    Predicting the long-term potential of permeable reactive barriers for treating contaminated groundwater relies on understanding the endpoints of biogeochemical reactions between influent groundwater and the reactive medium. Iron hydroxy carbonate (chukanovite) is frequently obs...

  16. Reactivity monitoring. Final report, Task 2

    SciTech Connect

    Reier, M.; Ching, J.

    1980-05-05

    A study has been made of a pulsed neutron technique which can be used to estimate the reactivity worth of spent fuel assemblies prior to storage. Nuclear design has been performed of a subcritical facility which can accommodate a test assembly of fresh fuel as well as one with a high degree of burnup. Calculations include the k/sub eff/ of the system and the gamma shielding required to protect personnel and instrumentation from fission product radiation. In addition, the technique and relevant equations to analyze the data are discussed. The calculations indicate that the technique can provide a rough differentiation between assemblies based on reactivity. However, practical problems involving the shield and neutron source impose severe limitations on the use of this method.

  17. Zeolite in horizontal permeable reactive barriers for artificial groundwater recharge

    NASA Astrophysics Data System (ADS)

    Leal, María; Martínez-Hernández, Virtudes; Lillo, Javier; Meffe, Raffaella; de Bustamante, Irene

    2013-04-01

    The Spanish Water Reuse Royal Decree 1620/2007 considers groundwater recharge as a feasible use of reclaimed water. To achieve the water quality established in the above-mentioned legislation, a tertiary wastewater treatment is required. In this context, the infiltration of effluents generated by secondary wastewater treatments through a Horizontal Permeable Reactive Barrier (HPRB) may represent a suitable regeneration technology. Some nutrients (phosphate and ammonium) and some Pharmaceutical and Personal Care Products (PPCPs) are not fully removed in conventional wastewater treatment plants. To avoid groundwater contamination when effluents of wastewater treatments plants are used in artificial recharge activities, these contaminants have to be removed. Due to its sorption capacities, zeolite is among the most used reactive materials in Permeable Reactive Barrier (PRB). Therefore, the main goal of this study is to evaluate the zeolite retention effectiveness of nutrients and PPCPs occurring in treated wastewater. Batch sorption experiments using synthetic wastewater (SWW) and zeolite were performed. A 1:4 zeolite/SWW ratio was selected due to the high sorption capacity of the reactive material.The assays were carried out by triplicate. All the bottles containing the SWW-zeolite mixture were placed on a mechanical shaker during 24 hours at 140 rpm and 25 °C. Ammonium and phosphate, as main nutrients, and a group of PPCPs were selected as compounds to be tested during the experiments. Nutrients were analyzed by ion chromatography. For PPCPs determination, Solid Phase Extraction (SPE) was applied before their analysis by liquid chromatography-mass spectrometry time of flight (LC-MS/ TOF). The experimental data were fitted to linearized Langmuir and Freundlich isotherm equations to obtain sorption parameters. In general, Freundlich model shows a greater capability of reproducing experimental data. To our knowledge, sorption of the investigated compounds on zeolite

  18. Evaluation of a permeable reactive barrier technology for use at Rocky Flats Environmental Technology Site (RFETS)

    SciTech Connect

    DWYER,BRIAN P.

    2000-01-01

    Three reactive materials were evaluated at laboratory scale to identify the optimum treatment reagent for use in a Permeable Reactive Barrier Treatment System at Rocky Flats Environmental Technology Site (RFETS). The contaminants of concern (COCS) are uranium, TCE, PCE, carbon tetrachloride, americium, and vinyl chloride. The three reactive media evaluated included high carbon steel iron filings, an iron-silica alloy in the form of a foam aggregate, and a peculiar humic acid based sorbent (Humasorb from Arctech) mixed with sand. Each material was tested in the laboratory at column scale using simulated site water. All three materials showed promise for the 903 Mound Site however, the iron filings were determined to be the least expensive media. In order to validate the laboratory results, the iron filings were further tested at a pilot scale (field columns) using actual site water. Pilot test results were similar to laboratory results; consequently, the iron filings were chosen for the fill-scale demonstration of the reactive barrier technology. Additional design parameters including saturated hydraulic conductivity, treatment residence time, and head loss across the media were also determined and provided to the design team in support of the final design. The final design was completed by the Corps of Engineers in 1997 and the system was constructed in the summer of 1998. The treatment system began fill operation in December, 1998 and despite a few problems has been operational since. Results to date are consistent with the lab and pilot scale findings, i.e., complete removal of the contaminants of concern (COCs) prior to discharge to meet RFETS cleanup requirements. Furthermore, it is fair to say at this point in time that laboratory developed design parameters for the reactive barrier technology are sufficient for fuel scale design; however,the treatment system longevity and the long-term fate of the contaminants are questions that remain unanswered. This

  19. Directed site exploration for permeable reactive barrier design

    USGS Publications Warehouse

    Lee, J.; Graettinger, A.J.; Moylan, J.; Reeves, H.W.

    2009-01-01

    Permeable reactive barriers (PRBs) are being employed for in situ site remediation of groundwater that is typically flowing under natural gradients. Site characterization is of critical importance to the success of a PRB. A design-specific site exploration approach called quantitatively directed exploration (QDE) is presented. The QDE approach employs three spatially related matrices: (1) covariance of input parameters, (2) sensitivity of model outputs, and (3) covariance of model outputs to identify the most important location to explore based on a specific design. Sampling at the location that most reduces overall site uncertainty produces a higher probability of success of a particular design. The QDE approach is demonstrated on the Kansas City Plant, Kansas City, MO, a case study where a PRB was installed and failed. It is shown that additional quantitatively directed site exploration during the design phase could have prevented the remedial failure that was caused by missing a geologic body having high hydraulic conductivity at the south end of the barrier. The most contributing input parameter approach using head uncertainty clearly indicated where the next sampling should be made toward the high hydraulic conductivity zone. This case study demonstrates the need to include the specific design as well as site characterization uncertainty when choosing the sampling locations. ?? 2008 Elsevier B.V.

  20. ECONOMICS ANALYSIS OF THE IMPLEMENTATION OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    This report presents an analysis of the cost of using permeable reactive barriers to remediate contaminated ground water. When possible, these costs are compared with the cost of pump-and-treat technology for similar situations. Permeable reactive barriers are no longer perceiv...

  1. Final rapid reactivation project environmental assessment

    SciTech Connect

    1999-02-10

    The US Department of Energy (DOE) has prepared an environmental assessment (EA) for the Rapid Reactivation Project at Sandia National Laboratories, New Mexico. The EA analyzes the potential effects of a proposal to increase production of neutron generators from the current capability of 600 units per year up to 2,000 units per year. The project would use existing buildings and infrastructure to the maximum extent possible to meet the additional production needs. The increased production levels would necessitate modifications and additions involving a total area of approximately 26,290 gross square feet at Sandia National Laboratories, New Mexico, Technical Area 1. Additional production equipment would be procured and installed. The no-action alternative would be to continue production activities at the current capability of 600 units per year. The EA analyzes effects on health, safety, and air quality, resulting from construction and operation and associated cumulative effects. A detailed description of the proposed action and its environmental consequences is presented in the EA.

  2. [Removal of nitrate from groundwater using permeable reactive barrier].

    PubMed

    Li, Xiu-Li; Yang, Jun-Jun; Lu, Xiao-Xia; Zhang, Shu; Hou, Zhen

    2013-03-01

    To provide a cost-effective method for the remediation of nitrate-polluted groundwater, column experiments were performed to study the removal of nitrate by permeable reactive barrier filled with fermented mulch and sand (biowall), and the mechanisms and influence factors were explored. The experimental results showed that the environmental condition in the simulated biowall became highly reduced after three days of operation (oxidation-reduction potential was below - 100 mV), which was favorable for the reduction of nitrate. During the 15 days of operation, the removal rate of nitrate nitrogen (NO3(-) -N) by the simulated biowall was 80%-90% (NO3(-)-N was reduced from 20 mg x L(-1) in the inlet water to 1.6 mg x L(-1) in the outlet water); the concentration of nitrite nitrogen (NO2(-) -N) in the outlet water was below 2.5 mg x L(-1); the concentration of ammonium nitrogen (NH4(+) -N) was low in the first two days but increased to about 12 mg x L(-1) since day three. The major mechanisms involved in the removal of nitrate nitrogen were adsorption and biodegradation. When increasing the water flow velocity in the simulated biowall, the removal rate of NO3(-) -N was reduced and the concentration of NH4(+) -N in the outlet water was significantly reduced. A simulated zeolite wall was set up following the simulated biowall and 98% of the NH4(+) -N could be removed from the water.

  3. SPATIAL DISTRIBUTION OF CARBON AND SULFUR PRECIPITATING WITHIN PERMEABLE REACTIVE BARRIERS: DEVELOPMENT OF ANALYTICAL METHODS

    EPA Science Inventory

    A permeable reactive barrier (PRB) is a wall of porous reactive material placed in the path of a dissolved contaminant plume for the purpose of removing contaminants from ground water. Chemical processes within these reactive materials remove both inorganic and organic contamina...

  4. Evaluation of Dairy Whey as a Subsurface Reactive Barrier Material

    NASA Astrophysics Data System (ADS)

    Semkiw, E.; Barcelona, M.; Kim, M.

    2006-05-01

    Subsurface permeable reactive barriers (PRBs) in remediation of contaminated ground water are currently being utilized and refined as an alternative/supplement to costly pump-and-treat remediation. Identification of efficient reactive materials that are effective in the long-term is essential for the ultimate success of PRBs in ground water remediation. A variety of enhancements have been used: oxidants, reductants or sorbents. Electron donors create/strengthen reducing conditions that are favorable for microbial degradation of chlorinated hydrocarbons. Inexpensive, food-grade electron donors effectively enhance dechlorination activity, and those that are solids that can be slurried and then pressure grouted are the best candidates for maintaining an active biobarrier at low cost. Dried dairy whey (~70% alpha-lactose), a slowly dissolving solid, is a prime candidate. To determine the efficiency of whey in promoting dechlorination, it is essential to identify the aerobic and anaerobic metabolic pathways and perform quantitative analysis of breakdown products. We hypothesize that dissolved whey will undergo microbial degradation (aerobic and anaerobic) to form carboxylic acids, and that in a suboxic/reducing environment the anaerobic products will stimulate the microbial dechlorination of chlorinated hydrocarbons PCE, TCE, and DCE. Analysis of the breakdown products in the absence as well as the presence of chlorinated hydrocarbons will result in the calculation of rate constants. Kinetics will, in turn, provide us with residence time, loading (whey mass), and projected lifetime of the whey PRB under estimated loads of total chlorinated hydrocarbon contamination. Early results from our field-scale effort to treat a TCE-contaminated site show increased concentrations of cis- DCE and VC downgradient from the whey PRBs, indicative of enhanced TCE dechlorination. Results from an initial microcosm experiment show complete disappearance of chlorinated hydrocarbons in the

  5. Iron Sulfide as a Sustainable Reactive Material for Permeable Reactive Barriers

    NASA Astrophysics Data System (ADS)

    Henderson, A. D.; Demond, A. H.

    2012-12-01

    Permeable reactive barriers (PRBs) are gaining acceptance for groundwater remediation, as they operate in situ and do not require continuous energy input. The majority of PRBs use zero-valent iron (ZVI). However, some ZVI PRBs have hydraulically failed [1,2], due to the fact that ZVI may reduce not only contaminants but also water and non-contaminant solutes. These reactions may form precipitates or gas phases that reduce permeability. Therefore, there is a need to assess the hydraulic suitability of possible alternatives, such as iron sulfide (FeS). The capability of FeS to remove both metals and halogenated organics from aqueous systems has been demonstrated previously [3,4], and FeS formed in situ within a ZVI PRB has been linked to contaminant removal [5]. These results suggest possible applications in groundwater remediation as a permeable reactive barrier (PRB) material. However, the propensity of FeS for permeability loss, due to solids and gas production, must be evaluated in order to address its suitability for PRBs. The reduction in permeability for FeS-coated sands under the anoxic conditions often encountered at contaminated groundwater sites was examined through column experiments and geochemical modeling under conditions of high calcium and nitrate, which have been previously shown to cause significant permeability reduction in zero-valent iron (ZVI) systems [6]. The column experiments showed negligible production of both solids and gases. The geochemical model was used to estimate solid and gas volumes generated under conditions of varying FeS concentration. Then, the Kozeny-Carman equation and a power-law relationship was used to predict permeability reduction, with a maximum reduction in permeability of 1% due to solids and about 30% due to gas formation under conditions for which a complete loss of permeability was predicted for ZVI systems. This difference in permeability reduction is driven by the differences in thermodynamic stability of ZVI

  6. Performance of a sequential reactive barrier for bioremediation of coal tar contaminated groundwater

    SciTech Connect

    Oriol Gibert; Andrew S. Ferguson; Robert M. Kalin; Rory Doherty; Keith W. Dickson; Karen L. McGeough; Jamie Robinson; Russell Thomas

    2007-10-01

    Following a thorough site investigation, a biological Sequential Reactive Barrier (SEREBAR), designed to remove polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, xylene (BTEX) compounds was installed at a former manufactured gas pPlant (FMGP) site currently used for gas storage and distribution within the UK. The novel design of the barrier comprises, in series, an interceptor and six reactive chambers. The first four chambers (2 nonaerated-2 aerated) were filled with sand to encourage microbial colonization. Sorbant granular activated carbon (GAC) was present in the final two chambers in order to remove any recalcitrant compounds. The SEREBAR has been in continuous operation for 2 years at different operational flow rates (ranging from 320 L/d to 4000 L/d, with corresponding residence times in each chamber of 19 days and 1.5 days, respectively). Under low flow rate conditions (320-520 L/d) the majority of contaminant removal ({gt}93%) occurred biotically within the interceptor and the aerated chambers. Under high flow rates (1000-4000 L/d) and following the installation of a new interceptor to prevent passive aeration, the majority of contaminant removal ({gt}80%) again occurred biotically within the aerated chambers. The sorption zone (GAC) proved to be an effective polishing step, removing any remaining contaminants to acceptable concentrations before discharge down-gradient of the SEREBAR (overall removals {gt}95%). 22 refs., 4 figs., 1 tab.

  7. Performance Assessment of a Permeable Reactive Barrier for Ground Water Remediation Fifteen Years After Installation

    EPA Science Inventory

    The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminanttreatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium sourc...

  8. LONG-TERM PERFORMANCE ASSESSMENT OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRBs) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. The few pilot and commercial installations which have been implemented ...

  9. PERMEABLE REACTIVE BARRIERS FOR IN-SITU TREATMENT OF ARSENIC-CONTAMINATED GROUNDWATER

    EPA Science Inventory

    Laboratory and field research has shown that permeable reactive barriers (PRBs) containing a variety of materials can treat arsenic (As) contaminated groundwater. Sites where these PRBs are located include a mine tailings facility, fertilizer and chemical manufacturing sites, a...

  10. PERFORMANCE OF PERMEABLE REACTIVE BARRIER AT U.S. COAST GUARD SITE, ELIZABETH CITY, NC

    EPA Science Inventory

    Permeable reactive barriers are innovative and cost-effective remedial technologies and are becoming more desirable methods for in-situ passive remediation of ground water contaminated with chlorinated hydrocarbons and redox-sensitive metals. As contaminated water passes through ...

  11. COST ANALYSIS OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF GROUND WATER

    EPA Science Inventory

    ABSTRACT

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating contaminated groundwater that combine subsurface fluid flow management with a passive chemical treatment zone. PRB's are a potentially more cost effective treatment...

  12. PERFORMANCE MONITORING OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. Removal of contaminants from the groundwater plume is achieved by alt...

  13. REMEDIATION OF TCE-CONTAMINATED GROUNDWATER BY A PERMEABLE REACTIVE BARRIER FILLED WITH PLANT MULCH (BIOWALL)

    EPA Science Inventory

    A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base (in Oklahoma, USA) to treat trichloroethylene (TCE) contamination in ground water emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 ...

  14. ACCUMULATION RATE OF MICROBIAL BIOMASS AT TWO PERMEABLE REACTIVE BARRIER SITES

    EPA Science Inventory

    Accumulation of mineral precipitates and microbial biomass are key factors that impact the long-term performance of in-situ Permeable Reactive Barriers for treating contaminated groundwater. Both processes can impact remedial performance by decreasing zero-valent iron reactivity...

  15. Transformation of Reactive Iron Minerals in a Permeable Reactive Barrier (Biowall) Used to Treat TCE in Groundwater

    EPA Science Inventory

    Abstract: Iron and sulfur reducing conditions are generally created in permeable reactive barrier (PRB) systems constructed for groundwater treatment, which usually leads to formation of iron sulfide phases. Iron sulfides have been shown to play an important role in degrading ch...

  16. Reactive Membrane Barriers for Containment of Subsurface Contamination

    SciTech Connect

    Arnold, William A.; Cussler, Edward L.

    2006-06-01

    This report focuses on progress made in the last 12 months, with prior results briefly summarized. We emphasize that the key to our work is an increase in barrier properties. Thus, much of our work has focused on poor, thin barriers composed of PVA. WE have done so because experiments are then able to be conducted over reasonable times. At the same time, we have developed and experimentally verified theories showing how our short experiments can be extrapolated to real situations.

  17. Reactive Membrane Barriers for Containment of Subsurface Contamination

    SciTech Connect

    Arnold, William

    2005-06-01

    This report focuses on progress made in the last 12 months, with prior results briefly summarized. We emphasize that the key to our work is an increase in barrier properties. Thus, much of our work has focused on poor, thin barriers composed of PVA. WE have done so because experiments are then able to be conducted over reasonable times. At the same time, we have developed and experimentally verified theories showing how our short experiments can be extrapolated to real situations.

  18. In Situ Formation Of Reactive Barriers For Pollution Control

    DOEpatents

    Gilmore, Tyler J.; Riley, Robert G.

    2004-04-27

    A method of treating soil contamination by forming one or more zones of oxidized material in the path of percolating groundwater is disclosed. The zone or barrier region is formed by delivering an oxidizing agent into the ground for reaction with an existing soil component. The oxidizing agent modifies the existing soil component creating the oxidized zone. Subsequently when soil contaminates migrate into the zone, the oxidized material is available to react with the contaminates and degrade them into benign products. The existing soil component can be an oxidizable mineral such as manganese, and the oxidizing agent can be ozone gas or hydrogen peroxide. Soil contaminates can be volatile organic compounds. Oxidized barriers can be used single or in combination with other barriers.

  19. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    SciTech Connect

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  20. REACTIVE BARRIER TREATMENT WALL TECHNOLOGY FOR REMEDIATION OF INORGANIC CONTAMINATED GROUNDWATER

    SciTech Connect

    T. TAYLOR; ET AL

    2001-03-01

    The potential for subsurface reactive barrier wall technology to aid in remediation of contaminated groundwater in situ has prompted testing of novel porous media. Treatability testing of contaminants contacted with various media has been conducted using equilibrium batch techniques, one-dimensional (1-D) columns and 2-D boxes. Continuous mode column and box experiments are useful for assessing critical design parameters under dynamic flow conditions. Experiments have been conducted using a multi-layer barrier treatment approach to immobilize a suite of contaminants. For example, basalt coated with a cationic polymer (poly diallyl dimethyl ammonium chloride [Catfloc{reg_sign}]) was used to agglomerate colloids, Apatite II{reg_sign} sorbed aqueous phase metals and radionuclides including {sup 85,87}Sr and {sup 235}U and facilitated reduction of nitrate and perchlorate, crushed pecan shells sorbed aqueous phase metals and served as a secondary medium for reduction of nitrate and perchlorate concentrations, and finally limestone raised the pH of exiting pore waters close to natural levels.

  1. Scar Functions, Barriers for Chemical Reactivity, and Vibrational Basis Sets.

    PubMed

    Revuelta, F; Vergini, E; Benito, R M; Borondo, F

    2016-07-14

    The performance of a recently proposed method to efficiently calculate scar functions is analyzed in problems of chemical interest. An application to the computation of wave functions associated with barriers relevant for the LiNC ⇄ LiCN isomerization reaction is presented as an illustration. These scar functions also constitute excellent elements for basis sets suitable for quantum calculation of vibrational energy levels. To illustrate their efficiency, a calculation of the LiNC/LiCN eigenfunctions is also presented.

  2. Redox-active media for permeable reactive barriers

    SciTech Connect

    Sivavec, T.M.; Mackenzie, P.D.; Horney, D.P.; Baghel, S.S.

    1997-12-31

    In this paper, three classes of redox-active media are described and evaluated in terms of their long-term effectiveness in treating TCE-contaminated groundwater in permeable reactive zones. Zero-valent iron, in the form of recycled cast iron filings, the first class, has received considerable attention as a reactive media and has been used in about a dozen pilot- and full-scale subsurface wall installations. Criteria used in selecting commercial sources of granular iron, will be discussed. Two other classes of redox-active media that have not yet seen wide use in pilot- or full-scale installations will also be described: Fe(II) minerals and bimetallic systems. Fe(II) minerals, including magnetite (Fe{sub 3}O{sub 4}), and ferrous sulfide (troilite, FeS), are redox-active and afford TCE reduction rates and product distributions that suggest that they react via a reductive mechanism similar to that which operates in the FeO system. Fe(II) species within the passive oxide layer coating the iron metal may act as electron transfer mediators, with FeO serving as the bulk reductant. Bimetallic systems, the third class of redox-active media, are commonly prepared by plating a second metal onto zero-valent iron (e.g., Ni/Fe and Pd/Fe) and have been shown to accelerate solvent degradation rates relative to untreated iron metal. The long-term effectiveness of this approach, however, has not yet been determined in groundwater treatability tests. The results of a Ni-plated iron column study using site groundwater indicate that a change in reduction mechanism (to catalytic dehydrohalogenation/hydrogenation) accounts for the observed rate enhancement. A significant loss in media reactivity was observed over time, attributable to Ni catalyst deactivation or poisoning. Zero-valent iron systems have not shown similar losses in reactivity in long-term laboratory, pilot or field investigations.

  3. Laboratory and Pilot Scale Evaluation of a Permeable Reactive Barrier Technology for Use at Rocky Flats Environmental Technology Site (RFETS)

    SciTech Connect

    Dwyer, B.P.; Hankins, M.G.

    1999-02-01

    Three reactive materials were evaluated to identify the optimum treatment reagent for use in a Permeable Reactive Barrier Treatment System at Rocky Flats Environmental Technology Site (RFETS). The three reactive media evaluated included high carbon steel iron filings, an iron-silica alloy in the form of a foam aggregate, and a pellicular humic acid based sorbent (Humasorb from Arctech) mixed with sand. Each material was tested in the laboratory at column scale using simulated site water. All three materials showed promise for the 903 Mound Site; however, the iron filings were determined to be the most cost effective media. In order to validate the laboratory results, the iron filings were further tested at a pilot scale (field columns) using actual site water. Pilot test results were similar to laboratory results; consequently, the iron filings were chosen for the full scale demonstration of this reactive barrier technology. Design parameters including saturated hydraulic conductivity, treatment residence time, and head loss across the media were provided to the design team in support of the final design.

  4. A clay permeable reactive barrier to remove Cs-137 from groundwater: Column experiments.

    PubMed

    De Pourcq, K; Ayora, C; García-Gutiérrez, M; Missana, T; Carrera, J

    2015-11-01

    Clay minerals are reputed sorbents for Cs-137 and can be used as a low-permeability material to prevent groundwater flow. Therefore, clay barriers are employed to seal Cs-137 polluted areas and nuclear waste repositories. This work is motivated by cases where groundwater flow cannot be impeded. A permeable and reactive barrier to retain Cs-137 was tested. The trapping mechanism is based on the sorption of cesium on illite-containing clay. The permeability of the reactive material is provided by mixing clay on a matrix of wood shavings. Column tests combined with reactive transport modeling were performed to check both reactivity and permeability. Hydraulic conductivity of the mixture (10(-4) m/s) was sufficient to ensure an adequate hydraulic performance of an eventual barrier excavated in most aquifers. A number of column experiments confirmed Cs retention under different flow rates and inflow solutions. A 1D reactive transport model based on a cation-exchange mechanism was built. It was calibrated with batch experiments for high concentrations of NH4+ and K+ (the main competitors of Cs in the exchange positions). The model predicted satisfactorily the results of the column experiments. Once validated, it was used to investigate the performance and duration of a 2 m thick barrier under different scenarios (flow, clay content, Cs-137 and K concentration).

  5. Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

    2014-08-01

    The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

  6. Advanced hydraulic fracturing methods to create in situ reactive barriers

    SciTech Connect

    Murdoch, L. |; Siegrist, B.; Meiggs, T.

    1997-12-31

    This article describes the use of hydraulic fracturing to increase permeability in geologic formations where in-situ remedial action of contaminant plumes will be performed. Several in-situ treatment strategies are discussed including the use of hydraulic fracturing to create in situ redox zones for treatment of organics and inorganics. Hydraulic fracturing methods offer a mechanism for the in-situ treatment of gently dipping layers of reactive compounds. Specialized methods using real-time monitoring and a high-energy jet during fracturing allow the form of the fracture to be influenced, such as creation of assymmetric fractures beneath potential sources (i.e. tanks, pits, buildings) that should not be penetrated by boring. Some examples of field applications of this technique such as creating fractures filled with zero-valent iron to reductively dechlorinate halogenated hydrocarbons, and the use of granular activated carbon to adsorb compounds are discussed.

  7. GEOCHEMISTRY OF SUBSURFACE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    Reactive barriers that couple subsurface fluid flow with a passive chemical treatment zone are emerging, cost effective approaches for in-situ remediation of contaminated groundwater. Factors such as the build-up of surface precipitates, bio-fouling, and changes in subsurface tr...

  8. CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION AT A FORMER SWINE CAFO

    EPA Science Inventory

    Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

  9. PERFORMANCE EVALUATION OF A CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION

    EPA Science Inventory

    Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

  10. RATE OF TCE DEGRADATION IN A PLANT MULCH PASSIVE REACTIVE BARRIER (BIOWALL)

    EPA Science Inventory

    A passive reactive barrier was installed at the OU-1 site at Altus Air Force Base, Oklahoma to treat TCE contamination in ground water from a landfill. Depth to ground water varies from 1.8 to 2.4 meters below land surface. To intercept and treat the plume of contaminated groun...

  11. Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites

    DTIC Science & Technology

    2002-04-24

    sand- fracking ) Naval Weapons CRB Industrial Reserve Plant, TX (a) PRB is not keyed in to aquitard. CRB =Continuous reactive barrier. JAG= Jet...of 5 months. Pumps may be damaged by biofouling due to polysaccharide contained in fracking tluids. Reduced average perchlorate concentrations

  12. GROUND WATER REMEDIATION RESEARCH: PERMEABLE REACTIVE BARRIERS AND SOURCE ZONE REMEDIATION

    EPA Science Inventory

    An overview of ground water remediation research conducted at the Subsurface Protection and Remediation Division is provided. The focus of the overview is on Permeable Reactive Barriers for treatment of organic and inorganic contaminants and remediation of DNAPL source zones.

  13. PERMEABLE REACTIVE BARRIER PERFORMANCE MONITORING: LONG-TERM TRENDS IN GEOCHEMICAL PARAMETERS AT TWO SITES

    EPA Science Inventory

    A major goal of research on the long-term performance of subsurface reactive barriers is to identify standard ground-water monitoring parameters that may be useful indicators of declining performance or impending system failure. Results are presented from studies conducted over ...

  14. RATE OF TCE DEGRADATION IN PASSIVE REACTIVE BARRIERS CONSTRUCTED WITH PLANT MULCH (BIOWALLS)

    EPA Science Inventory

    This presentation reviews a case study at Altus AFB on the extent of treatment of TCE in a passive reactive barrier constructed with plant mulch. It presents data from a tracer test to estimate the rate of ground water flow at the site, and the residence time of water and TCE in...

  15. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS TO REMEDIATE CONTAMINATED GROUND WATER

    EPA Science Inventory

    This research brief presents findings over the past four years at two sites where detailed investigations by the U.S. Environmental Protection Agency (U.S. EPA) have focused on the long-term performance of PRBs under a Tri-Agency Permeable Reactive Barrier Initiative (TRI). This ...

  16. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED, FUTURE DIRECTIONS

    EPA Science Inventory

    Recently, a synthesis of research findings by EPA has been prepared and presented in an EPA report titled Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation (EPA/600/R-03/045 a,b). Another report has also be...

  17. PERMEABLE REACTIVE BARRIER PERFORMANCE MONITORING: LONG-TERM TRENDS IN GEOCHEMICAL PARAMETERS AT TWO SITES

    EPA Science Inventory

    A major goal of research on the long-term performance of subsurface reactive barriers is to identify standard ground water monitoring parameters that may be useful indicators of declining performance or impending system failure. Results are presented from ground water monitoring ...

  18. CHROMIUM REMOVAL PROCESSES DURING GROUNDWATER REMEDIATION BY A ZEROVALENT IRON PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    Solid-phase associations of chromium were examined in core materials collected from a full-scale, zerovalent iron, permeable reactive barrier (PRB) at the U.S. Coast Guard Support Center located near Elizabeth City (NC). The PRB was installed in 1996 to treat groundwater contami...

  19. A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

    EPA Science Inventory

    A tracer test was conducted to characterize the flow of ground water surrounding a permeable reactive barrier constructed with plant mulch (a biowall) at the OU-1 site on Altus Air Force Base, Oklahoma. This biowall is intended to intercept and treat ground water contaminated by ...

  20. Nanosized iron based permeable reactive barriers for nitrate removal - Systematic review

    NASA Astrophysics Data System (ADS)

    Araújo, Rui; Castro, Ana C. Meira; Santos Baptista, João; Fiúza, António

    2016-08-01

    It is unquestionable that an effective decision concerning the usage of a certain environmental clean-up technology should be conveniently supported. Significant amount of scientific work focussing on the reduction of nitrate concentration in drinking water by both metallic iron and nanomaterials and their usage in permeable reactive barriers has been worldwide published over the last two decades. This work aims to present in a systematic review of the most relevant research done on the removal of nitrate from groundwater using nanosized iron based permeable reactive barriers. The research was based on scientific papers published between 2004 and June 2014. It was performed using 16 combinations of keywords in 34 databases, according to PRISMA statement guidelines. Independent reviewers validated the selection criteria. From the 4161 records filtered, 45 met the selection criteria and were selected to be included in this review. This study's outcomes show that the permeable reactive barriers are, indeed, a suitable technology for denitrification and with good performance record but the long-term impact of the use of nanosized zero valent iron in this remediation process, in both on the environment and on the human health, is far to be conveniently known. As a consequence, further work is required on this matter, so that nanosized iron based permeable reactive barriers for the removal of nitrate from drinking water can be genuinely considered an eco-efficient technology.

  1. EVALUATION OF PERMEABLE REACTIVE BARRIER PERFORMANCE: A TRI-AGENCY INITIATIVE

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology represents a passive option for long-term treatment of ground-water contamination. PRBs are a potentially more cost-effective treatment option for a variety of dissolved contaminants, such as certain types of chlorinated solvents, ...

  2. COST ANALYSIS OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF GROUND WATER

    EPA Science Inventory

    The U. S. Environmental Protection Agency's Office of Research and Development and its contractor have evaluated cost data from 22 sites where permeable reactive barriers (PRBs) have been utilized to remediate contaminated ground water resources. Most of the sites evaluated wer...

  3. Zero-Valent Iron Permeable Reactive Barriers: A Review of Performance

    SciTech Connect

    Korte, NE

    2001-06-11

    This report briefly reviews issues regarding the implementation of the zero-valent iron permeable reactive barrier (PRB) technology at sites managed by the U.S. Department of Energy (DOE). Initially, the PRB technology, using zero-valent iron for the reactive media, was received with great enthusiasm, and DOE invested millions of dollars testing and implementing PRBs. Recently, a negative perception of the technology has been building. This perception is based on the failure of some deployments to satisfy goals for treatment and operating expenses. The purpose of this report, therefore, is to suggest reasons for the problems that have been encountered and to recommend whether DOE should invest in additional research and deployments. The principal conclusion of this review is that the most significant problems have been the result of insufficient characterization, which resulted in poor engineering implementation. Although there are legitimate concerns regarding the longevity of the reactive media, the ability of zero-valent iron to reduce certain chlorinated hydrocarbons and to immobilize certain metals and radionuclides is well documented. The primary problem encountered at some DOE full-scale deployments has been an inadequate assessment of site hydrology, which resulted in misapplication of the technology. The result is PRBs with higher than expected flow velocities and/or incomplete plume capture. A review of the literature reveals that cautions regarding subsurface heterogeneity were published several years prior to the full-scale implementations. Nevertheless, design and construction have typically been undertaken as if the subsurface was homogeneous. More recently published literature has demonstrated that hydraulic heterogeneity can cause so much uncertainty in performance that use of a passive PRB is precluded. Thus, the primary conclusion of this review is that more attention must be given to site-specific issues. Indeed, the use of a passive PRB requires

  4. Permeable bio-reactive barriers to address petroleum hydrocarbon contamination at subantarctic Macquarie Island.

    PubMed

    Freidman, Benjamin L; Terry, Deborah; Wilkins, Dan; Spedding, Tim; Gras, Sally L; Snape, Ian; Stevens, Geoffrey W; Mumford, Kathryn A

    2017-05-01

    A reliance on diesel generated power and a history of imperfect fuel management have created a legacy of petroleum hydrocarbon contamination at subantarctic Macquarie Island. Increasing environmental awareness and advances in contaminant characterisation and remediation technology have fostered an impetus to reduce the environmental risk associated with legacy sites. A funnel and gate permeable bio-reactive barrier (PRB) was installed in 2014 to address the migration of Special Antarctic Blend diesel from a spill that occurred in 2002, as well as older spills and residual contaminants in the soil at the Main Power House. The PRB gate comprised of granular activated carbon and natural clinoptilolite zeolite. Petroleum hydrocarbons migrating in the soil water were successfully captured on the reactive materials, with concentrations at the outflow of the barrier recorded as being below reporting limits. The nutrient and iron concentrations delivered to the barrier demonstrated high temporal variability with significant iron precipitation observed across the bed. The surface of the granular activated carbon was largely free from cell attachment while natural zeolite demonstrated patchy biofilm formation after 15 months following PRB installation. This study illustrates the importance of informed material selection at field scale to ensure that adsorption and biodegradation processes are utilised to manage the environmental risk associated with petroleum hydrocarbon spills. This study reports the first installation of a permeable bio-reactive barrier in the subantarctic.

  5. Sex Bias Barriers to Vocational Education Enrollment. Final Report.

    ERIC Educational Resources Information Center

    Brown, Judy Palmer; And Others

    A study was conducted to identify barriers and develop programatic strategies necessary to overcome those barriers that deter both male and female students from enrolling in vocational education programs of their choice. The study utilized a modified delphi technique to collect the perceptions of the sample groups wanting to enroll in…

  6. Hydraulic performance of a permeable reactive barrier at Casey Station, Antarctica.

    PubMed

    Mumford, K A; Rayner, J L; Snape, I; Stevens, G W

    2014-12-01

    A permeable bio-reactive barrier (PRB) was installed at Casey Station, Antarctica in 2005/06 to intercept, capture and degrade petroleum hydrocarbons from a decade old fuel spill. A funnel and gate configuration was selected and implemented. The reactive gate was split into five separate cells to enable the testing of five different treatment combinations. Although different treatment materials were used in each cell, each treatment combination contained the following reactive zones: a zone for the controlled release of nutrients to enhance degradation, a zone for hydrocarbon capture and enhanced degradation, and a zone to capture excess nutrients. The materials selected for each of these zones had other requirements, these included; not having any adverse impact on the environment, being permeable enough to capture the entire catchment flow, and having sufficient residence time to fully capture migrating hydrocarbons. Over a five year period the performance of the PRB was extensively monitored and evaluated for nutrient concentration, fuel retention and permeability. At the end of the five year test period the material located within the reactive gate was excavated, total petroleum hydrocarbon concentrations present on the material determined and particle size analysis conducted. This work found that although maintaining media reactivity is obviously important, the most critical aspect of PRB performance is preserving the permeability of the barrier itself, in this case by maintaining appropriate particle size distribution. This is particularly important when PRBs are installed in regions that are subject to freeze thaw processes that may result in particle disintegration over time.

  7. Heavy metals removal and hydraulic performance in zero-valent iron/pumice permeable reactive barriers.

    PubMed

    Moraci, Nicola; Calabrò, Paolo S

    2010-11-01

    Long-term behaviour is a major issue related to the use of zero-valent iron (ZVI) in permeable reactive barriers for groundwater remediation; in fact, in several published cases the hydraulic conductivity and removal efficiency were progressively reduced during operation, potentially compromising the functionality of the barrier. To solve this problem, the use of granular mixtures of ZVI and natural pumice has recently been proposed. This paper reports the results of column tests using aqueous nickel and copper solutions of various concentrations. Three configurations of reactive material (ZVI only, granular mixture of ZVI and pumice, and pumice and ZVI in series) are discussed. The results clearly demonstrate that iron-pumice granular mixtures perform well both in terms of contaminant removal and in maintaining the long-term hydraulic conductivity. Comparison with previous reports concerning copper removal by ZVI/sand mixtures reveals higher performance in the case of ZVI/pumice.

  8. Remediation of TNT and RDX in Groundwater Using Zero-Valent Iron Permeable Reactive Barriers

    DTIC Science & Technology

    2008-04-01

    outside diameter ORP oxidation reduction potential P&T pumping and treatment PRB permeable reactive barrier PTA Pilot Test Area PV present value PVC... States Environmental Protection Agency UHU ultra high vacuum UV ultraviolet XPS x-ray photoelectron spectroscopy ZVI zero-valent iron...groundwater typically involve groundwater extraction and treatment (pump-and-treat) with treatment by carbon adsorption or ultraviolet (UV) oxidation

  9. Semi-analytical Solution of One-dimensional Multispecies Reactive Transport in a Permeable Reactive Barrier-aquifer System

    NASA Astrophysics Data System (ADS)

    Mieles, J. M.; Zhan, H.

    2010-12-01

    Permeable reactive barriers (PRBs) have been accepted by the EPA as an effective groundwater remediation technology. Effective implementation of this in-situ technology requires accurate site characterization to identify the chemicals of concern (COCs) present, their interactions (if any), and their required residence time in the PRB to achieve regulatory concentrations at the point of compliance (POC). Therefore, minimizing performance uncertainties in the design phase is key. Among these uncertainties determining the required PRB thickness is the most important and has been examined in other studies. Less attention, however, has been devoted to developing a practical yet rigorous tool for modeling multi-species reactive transport in the barrier-aquifer system. In this study Park and Zhan’s [2009] mass conservative semi-analytical solution - developed to calculate the required PRB thickness based on the decay of one species - is expanded to four reactive species. For example, the expanded solution could be used to model the degradation pathway from tetrachloroethylene (PCE) to vinyl chloride (VC). The solution is presented in two forms: The steady-state solution programmed into Excel can quickly assist designers in determining the required PRB thickness so that all COCs involved in the degradation pathway achieve regulatory limits at the POC. The second form is the transient solution which is solved by numerically inverting the Laplace transform. The semi-analytical solution presented in this study has several advantages over prior solutions. For example, the influent and effluent boundary conditions of the PRB are mass conservative and both dispersion and decay rate differences between the PRB and aquifer are considered. In addition, the transient solution allows for different retardation factors to be considered in both transport media and for each species.

  10. Potential performance of pillared inorgano- organo bentonite for soil mix technology permeable reactive barrier (Invited)

    NASA Astrophysics Data System (ADS)

    Abunada, Z. M.; Al-Tabbaa, A.

    2013-12-01

    Modified bentonite has gained more interest for their effect in contaminant removal and environmental protection. This study is investigating the use of three different modified inorgano-organo bentonite (IOB) in soil mixing permeable reactive barrier. IOB were prepared using pillaring agents and quaternary ammonium cations (QAC) with different loading ratios. The permeabilities of compacted specimens containing IOB with two different soil types (sandy and gravelly soil) were measured for site contaminated groundwater, pure water and TEX compounds to study the potential of soil mix permeable reactive barrier (PRB). The soil permeability decreased by 1-2 order of magnitude once mixed with IOB. It also decreased by about 100 in case of TEX compound and site groundwater. The IOB was tested to remove Toluene, Ethyl-benzene, and o-Xylene (TEX) compound from model contaminated water in both batch and column test. Physical characteristics such as pore volume, porosity and specific structure in addition to level of surfactant loading were determined. Materials removal efficiency varied due to the surfactant loading, soil type and contaminant molecular weight. Sorption isotherm showed that the adsorbates preference increased in the order of T>E>X in all IOB types. Maximum TEX compound sorptive capacity varied also due to soil type with the highest was 86.89% 93.19% and 90.2% for T,E,X respectively on sandy soil. Key words: Inorgano-organo bentonite, permeability, reactive barrier, soil mix, sorption

  11. In situ formation of magnetite reactive barriers in soil for waste stabilization

    DOEpatents

    Moore, Robert C.

    2003-01-01

    Reactive barriers containing magnetite and methods for making magnetite reactive barriers in situ in soil for sequestering soil contaminants including actinides and heavy metals, organic materials, iodine and technetium are disclosed. According to one embodiment, a two-step reagent introduction into soil takes place. In the first step, free oxygen is removed from the soil by separately injecting into the soil aqueous solutions of iron (II) salt, for example FeCl.sub.2, and base, for example NaOH or NH.sub.3 in about a 1:1 volume ratio. Then, in the second step, similar reagents are injected a second time (however, according to about a 1:2 volume ratio, iron to salt) to form magnetite. The magnetite formation is facilitated, in part, due to slow intrusion of oxygen into the soil from the surface. The invention techniques are suited to injection of reagents into soil in proximity to a contamination plume or source allowing in situ formation of the reactive barrier at the location of waste or hazardous material. Mixing of reagents to form. precipitate is mediated and enhanced through movement of reagents in soil as a result of phenomena including capillary action, movement of groundwater, soil washing and reagent injection pressure.

  12. Improved Barriers to Turbine Engine Fragments: Final Annual Report

    DTIC Science & Technology

    2002-06-01

    failure behavior in the vicinity of a pegged hole. A series of these fabric corner failure tests in both Zylon and Kevlar fabrics determined that...barrier) upon the ballistic efficiency of the barrier. In some cases, Keviar could be as effective as (or more effective than) Zylon , due to the larger...fraction of impact energy consumed in producing comer tearing. A considerable database of large-scale fragment impact tests into Zylon and Kevlar fabric

  13. Methods and apparatuses for reagent delivery, reactive barrier formation, and pest control

    DOEpatents

    Gilmore, Tyler [Pasco, WA; Kaplan, Daniel I [Aiken, SC; Last, George [Richland, WA

    2002-07-09

    A reagent delivery method includes positioning reagent delivery tubes in contact with soil. The tubes can include a wall that is permeable to a soil-modifying reagent. The method further includes supplying the reagent in the tubes, diffusing the reagent through the permeable wall and into the soil, and chemically modifying a selected component of the soil using the reagent. The tubes can be in subsurface contact with soil, including groundwater, and can be placed with directional drilling equipment independent of groundwater well casings. The soil-modifying reagent includes a variety of gases, liquids, colloids, and adsorbents that may be reactive or non-reactive with soil components. The method may be used inter alia to form reactive barriers, control pests, and enhance soil nutrients for microbes and plants.

  14. Structure-Reactivity Relationships in Multi-Component Transition Metal Oxide Catalysts FINAL Report

    SciTech Connect

    Altman, Eric I.

    2015-10-06

    The focus of the project was on developing an atomic-level understanding of how transition metal oxide catalysts function. Over the course of several renewals the specific emphases shifted from understanding how local structure and oxidation state affect how molecules adsorb and react on the surfaces of binary oxide crystals to more complex systems where interactions between different transition metal oxide cations in an oxide catalyst can affect reactivity, and finally to the impact of cluster size on oxide stability and reactivity. Hallmarks of the work were the use of epitaxial growth methods to create surfaces relevant to catalysis yet tractable for fundamental surface science approaches, and the use of scanning tunneling microscopy to follow structural changes induced by reactions and to pinpoint adsorption sites. Key early findings included the identification of oxidation and reduction mechanisms on a tungsten oxide catalyst surface that determine the sites available for reaction, identification of C-O bond cleavage as the rate limiting step in alcohol dehydration reactions on the tungsten oxide surface, and demonstration that reduction does not change the favored reaction pathway but rather eases C-O bond cleavage and thus reduces the reaction barrier. Subsequently, a new reconstruction on the anatase phase of TiO2 relevant to catalysis was discovered and shown to create sites with distinct reactivity compared to other TiO2 surfaces. Building on this work on anatase, the mechanism by which TiO2 enhances the reactivity of vanadium oxide layers was characterized and it was found that the TiO2 substrate can force thin vanadia layers to adopt structures they would not ordinarily form in the bulk which in turn creates differences in reactivity between supported layers and bulk samples. From there, the work progressed to studying well-defined ternary oxides where synergistic effects between the two cations can induce

  15. LONG-TERM PERFORMANCE OF IN-SITU PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating groundwater contamination that combine subsurface fluid flow management with a passive chemical treatment zone. The few pilot and commercial installations which have been implemented...

  16. Interim Report: Field Demonstration Of Permeable Reactive Barriers To Remove Dissolved Uranium From Groundwater, Fry Canyon, Utah

    EPA Pesticide Factsheets

    The Fry Canyon site in southeastern Utah was selected in 1996 as a long-term field demonstration site to assess the performance of selected permeable reactive barriers for the removal of uranium (U) from groundwater.

  17. Long-Term Groundwater Monitoring Optimization, Clare Water Supply Superfund Site, Permeable Reactive Barrier and Soil Remedy Areas, Clare, Michigan

    EPA Pesticide Factsheets

    This report contains a review of the long-term groundwater monitoring network for the Permeable Reactive Barrier (PRB) and Soil Remedy Areas at the Clare Water Supply Superfund Site in Clare, Michigan.

  18. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: AN UPDATE ON A U.S. MULTI-AGENCY INITIATIVE

    EPA Science Inventory

    Permeable reactive barriers (PRB's) are an emerging, alternative in-situ approach for remediating contaminated groundwater that combine subsurface fluid flow management with a passive chemical treatment zone. PRB's are a potentially more cost effective treatment option at seve...

  19. CARBON AND SULFUR ACCUMULATION AND IRON MINERAL TRANSFORMATION IN PERMEABLE REACTIVE BARRIERS CONTAINING ZERO-VALENT IRON

    EPA Science Inventory

    Permeable reactive barrier technology is an in-situ approach for remediating groundwater contamination that combines subsurface fluid flow management with passive chemical treatment. Factors such as the buildup of mineral precipitates, buildup of microbial biomass (bio-fouling...

  20. Impact of sample preparation on mineralogical analysis of zero-valent iron reactive barrier materials

    SciTech Connect

    Phillips, Debra Helen; Gu, Baohua; Watson, David B; Roh, Yul

    2003-03-01

    Permeable reactive barriers (PRBs) of zero-valent iron (Fe{sup 0}) are increasingly being used to remediate contaminated ground water. Corrosion of Fe{sup 0} filings and the formation of precipitates can occur when the PRB material comes in contact with ground water and may reduce the lifespan and effectiveness of the barrier. At present, there are no routine procedures for preparing and analyzing the mineral precipitates from Fe{sup 0} PRB material. These procedures are needed because mineralogical composition of corrosion products used to interpret the barrier processes can change with iron oxidation and sample preparation. The objectives of this study were (i) to investigate a method of preparing Fe{sup 0} reactive barrier material for mineralogical analysis by X-ray diffraction (XRD), and (ii) to identify Fe mineral phases and rates of transformations induced by different mineralogical preparation techniques. Materials from an in situ Fe{sup 0} PRB were collected by undisturbed coring and processed for XRD analysis after different times since sampling for three size fractions and by various drying treatments. We found that whole-sample preparation for analysis was necessary because mineral precipitates occurred within the PRB material in different size fractions of the samples. Green rusts quickly disappeared from acetone-dried samples and were not present in air-dried and oven-dried samples. Maghemite/magnetite content increased over time and in oven-dried samples, especially after heating to 105 C. We conclude that care must be taken during sample preparation of Fe{sup 0} PRB material, especially for detection of green rusts, to ensure accurate identification of minerals present within the barrier system.

  1. Performance Evaluation of In-Situ Iron Reactive Barriers at the Oak Ridge Y-12 Site

    SciTech Connect

    Watson, D.B.

    2003-12-30

    In November 1997, a permeable iron reactive barrier trench was installed at the S-3 Ponds Pathway 2 Site located at the Y-12 Plant, Oak Ridge, Tennessee. The overall goal of the project is to evaluate the ability of permeable reactive barrier technology to remove uranium, nitrate, and other inorganic contaminants in groundwater and to assess impacts of biogeochemical interactions on long-term performance of the treatment system. Zero-valent iron (Fe0) was used as the reactive medium, which creates a localized zone of reduction or low oxidation reduction potential (ORP), elevated pH, and dissolved H{sub 2} as Fe{sup 0} corrodes in groundwater. These conditions favor the removal of metals and radionuclides (such as uranium and technetium) through redox-driven precipitation and/or sorption to iron corrosion byproducts, such as iron oxyhydroxides. The technology is anticipated to be economical and low in maintenance as compared with conventional pump-and-treat technology. Groundwater monitoring results indicate that the iron barrier is effectively removing uranium and technetium, the primary contaminants of concern, as anticipated from our previous laboratory studies. In addition to uranium and technetium, nitrate, sulfate, bicarbonate, calcium, and magnesium are also found to be removed, either partially or completely by the iron barrier. Elevated concentrations of ferrous ions and sulfide, and pH were observed within the iron barrier. Although ferrous iron concentrations were initially very high after barrier installation, ferrous ion concentrations have decreased to low to non-detectable levels as the pH within the iron has increased over time (as high as 9 or 10). Iron and soil core samples were taken in February 1999 and May 2000 in order to evaluate the iron surface passivation, morphology, mineral precipitation and cementation, and microbial activity within and in the vicinity of the iron barrier. Results indicate that most of the iron filings collected in cores

  2. Permanganate treatment of DNAPLs in reactive barriers and source zone flooding schemes. 1997 annual progress report

    SciTech Connect

    Schwartz, F.W.

    1997-01-01

    'The goals of this study are (1) to elucidate the basic mechanisms by which potassium permanganate oxidizes common chlorinated solvents, various constituents in aqueous solution, and porous-medium solids, and (2) to assess the potential for chemical oxidation by potassium permanganate to serve as a remedial scheme involving either source zone flooding or reactive barriers. The research plan involves a combined experimental/modeling study that builds on the extensive previous work in the area of reactive barrier systems, and modeling of reactive contaminant transport. The experimental studies are being undertaken at The Ohio State University by Dr. Schwartz and his co-workers. The modeling work is being conducted in Albuquerque, NM by Dr. Zhang of Intera, Inc. The workplan for this study is designed around the following four objectives (1) to describe through batch experiments the kinetics and mechanisms by which potassium permanganate oxidizes dissolved tetrachloroethene (PCE), trichloroethene (TCE), and dichloroethene (DCE), (2) to examine using column studies the nature and kinetics of reactions between potassium permanganate, residual DNAPLs (PCE, TCE, and DCE) and porous medium solids, (3) to represent the process understanding in flow and transport models that demonstrate the potential applicability of the approach, and (4) to apply the resulting computer code in the development of appropriate field tests for assessing the approach.'

  3. Fungal permeable reactive barrier to remediate groundwater in an artificial aquifer.

    PubMed

    Folch, Albert; Vilaplana, Marcel; Amado, Leila; Vicent, Teresa; Caminal, Glòria

    2013-11-15

    Biobarriers, as permeable reactive barriers (PRBs), are a common technology that mainly uses bacteria to remediate groundwater in polluted aquifers. In this study, we propose to use Trametes versicolor, a white-rot fungus, as the reactive element because of its capacity to degrade a wide variety of highly recalcitrant and xenobiotic compounds. A laboratory-scale artificial aquifer was constructed to simulate groundwater flow under real conditions in shallow aquifers. Orange G dye was chosen as a contaminant to visually monitor the hydrodynamic behaviour of the system and any degradation of the dye by the fungus. Batch experiments at different pH values (6 and 7) and several temperatures (15 °C, 18 °C, 20 °C and 25 °C) were performed to select the appropriate residence time and glucose consumption rate required for continuous treatment. The maximum Orange G degradation was 97%. Continuous degradation over 85% was achieved for more than 8 days. Experimental results indicate for the first time that this fungus can potentially be used as a permeable reactive barrier in real aquifers.

  4. Iron hydroxy carbonate formation in zerovalent iron permeable reactive barriers: Characterization and evaluation of phase stability

    SciTech Connect

    Wilkin, Richard T.; Lee, T.R.

    2010-10-22

    Predicting the long-term potential of permeable reactive barriers for treating contaminated groundwater relies on understanding the endpoints of biogeochemical reactions between influent groundwater and the reactive medium. Iron hydroxy carbonate (chukanovite) is frequently observed as a secondary mineral precipitate in granular iron PRBs. Mineralogical characterization was carried out using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and X-ray absorption spectroscopy on materials collected from three field-based PRBs in the US (East Helena, MT; Elizabeth City, NC; Denver Federal Center, CO). These PRBs were installed to treat a range of contaminants, including chlorinated organics, hexavalent chromium, and arsenic. Results obtained indicate that chukanovite is a prevalent secondary precipitate in the PRBs. Laboratory experiments on high-purity chukanovite separates were carried out to constrain the room-temperature solubility for this mineral. An estimated Gibbs energy of formation ({Delta}{sub f}G{sup o}) for chukanovite is - 1174.4 {+-} 6 kJ/mol. A mineral stability diagram is consistent with observations from the field. Water chemistry from the three reactive barriers falls inside the predicted stability field for chukanovite, at inorganic carbon concentrations intermediate to the stability fields of siderite and ferrous hydroxide. These new data will aid in developing better predictive models of mineral accumulation in zerovalent iron PRBs.

  5. TRICHLOROETHYLENE REMOVAL FROM GROUNDWATER IN FLOW-THROUGH COLUMNS SIMULATING A PERMEABLE REACTIVE BARRIER CONSTRUCTED WITH PLANT MULCH

    EPA Science Inventory

    Ground water contaminated with TCE is commonly treated with a passive reactive barrier (PRB) constructed with zero-valence iron. The cost of iron as the reactive matrix has driven a search for less costly alternatives, and composted plant mulch has been used as an alternative re...

  6. Electrical Properties of Reacted Iron Cores Extracted From a Permeable Reactive Barrier Installation

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Slater, L.; Korte, N.

    2005-12-01

    We conducted experiments to investigate the application of non-invasive electrical method for monitoring iron corrosion and mineral precipitation processes on angle cores recovered from the Kansas City Plant reactive iron barrier. Electrical measurements showed continuous changes from the soil/iron interface into the barrier for all three cores. Scanning electron microscopy (SEM) identified iron surface alteration with thickest corrosion rind, indicating most severe corrosion, occurred close to upgradient soil/iron interface relative to locations further into the cores. Nitrogen adsorption measurements showed decreases in specific surface area of iron minerals from upgradient soil/iron interface into the barrier. X-ray diffractometry (XRD) identified precipitation of iron oxide/hydroxide, carbonate minerals, iron sulfide as well as green rusts in all three cores, and magnetite was identified as the dominant phase. Electrical measurements correlated well with solid phase analysis and illustrated the sensitivity of low frequency electrical method to iron corrosion and mineral precipitation processes. Electrical signature changes are attributed to (1) higher complex interfacial conductivity due to increased surface area and mineralogical alteration, and (2) increased electronic conduction due to enhanced electron transfer across the iron-fluid interface facilitated by mineralogical alternation and increased specific surface area during iron corrosion and mineral precipitation. Electrical measurements along with solid phase analysis also revealed more severe corrosion occurred at north end relative to south end of the barrier correlated with more groundwater flow through north end of the barrier. Our results on field cores are consistent with laboratory studies on synthetic iron columns presented previously and demonstrate that electrical measurements are a proxy indicator of Fe0 surface alteration and could be implemented for field barrier corrosion process monitoring.

  7. Summary abstract: reactivity sputtered RuO/sub 2/ and Mo-O diffusion barriers

    SciTech Connect

    So, F.C.; Kolawa, E.; Zhao, X.; Pan, E.T.; Nicolet, M.

    1987-12-01

    Diffusion barriers are indispensable in present very large scale integrated (VLSI) contact technologies to preserve the integrity of shallow junctions and Schottky barriers from aluminum spiking during postmetallization processing. While a mammoth effort has been devoted to refractory metal nitrides, little attention is paid to the suitability of thin films of conducting transition-metal oxides for diffusion barrier applications. This attitude probably springs from the fact that most transition-metal oxides are electrically insulating. There are, however, transition-metal oxides that exhibit conductivities at room temperatures. One type of conducting oxide has an oxygen to metal ratio of 2. Two groups can be distinguished. The first one consists of the dioxides of the platinum-group metals which crystallize in the rutile structure: ruthenium dioxide, osmium dioxide, iridium dioxide, and rhodium dioxide. Among the four, RuO/sub 2/ is reported to possess the lowest bulk resistivity. The other class is made up of the dioxides that adopt distorted variants of the rutile structure: CrO/sub 2/, molybdenum dioxide, and WO/sub 2/. Single crystals of MoO/sub 2/ are monoclinic and have a room-temperature resistivity of approx. 90 micro ohms sq. cm. This report summarizes the important aspects of the deposition behavior of RuO/sub 2/ and Mo-O films formed by radio-frequency (rf) reactive sputtering and their diffusion barrier properties against interdiffusion in aluminum-silicon couples.

  8. Characteristics of reactively sputtered niobium nitride thin films as diffusion barriers for Cu metallization

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Lin; Lai, Chih-Huang; Tsai, Po-Hao; Huang, Hsing-An; Lin, Jing-Cheng; Lee, Chiapyng

    2013-09-01

    NbN films were prepared by radio frequency reactive magnetron sputtering and then employed as diffusion barriers between Cu and Si. The microstructure of the NbN films was an assembly of very small columnar crystallites with a cubic structure. To investigate the properties as diffusion barriers, we performed metallurgical reactions of Cu/NbN0.8/Si, Cu/Nb/Si and Cu/TaN0.7/Si for comparisons. The sheet resistance increased dramatically after annealing above 750°C for Cu/NbN0.80/Si, and above 500°C for both Cu/Nb/Si and Cu/TaN0.7/Si. The interfaces were deteriorated seriously and formation of Cu3Si was observed when the sheet resistance was significantly increased. The diffusion coefficient of Cu in NbN barrier films was estimated by using the change of resistance (Δ R s / R s %). Compared with TaN0.7, NbN0.8 films possess larger grain size and lower Cu diffusion coefficient. Our results suggest that the NbN film can be used as a diffusion barrier for Cu metallization as compared to the well-known TaN film.

  9. Design and synthesis of reactive separation systems. Final report

    SciTech Connect

    Doherty, M.F.

    1992-12-31

    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  10. Mollusc C-reactive protein crosses species barrier and reverses hepatotoxicity of lead in rodent models.

    PubMed

    Mukherjee, Sandip; Chatterjee, Sarmishtha; Sarkar, Shuvasree; Agarwal, Soumik; Kundu, Rakesh; Maitra, Sudipta; Bhattacharya, Shelley

    2013-08-01

    Achatina fulica C-reactive protein (ACRP) reversed the toxic effects of lead nitrate both in vivo in mice and in vitro in rat hepatocytes restoring the basal level of cell viability, lipid peroxidation, reduced glutathione and superoxides. Cytotoxicity was also significantly ameliorated in rat hepatocytes by in vitro pre-treatments with individual subunits (60, 62, 90 and 110 kDa) of ACRP. Annexin V-Cy3/CFDA dual staining showed significant reduction in the number of apoptotic hepatocytes pre-treated with ACRP. ACRP induced restoration of mitochondrial membrane potential was remarkable. ACRP pre-treatment prevented Pb-induced apoptosis mediated by caspase activation. The antagonistic effect of ACRP may be due to scavenging of reactive oxygen species which maintained the homeostasis of cellular redox potential as well as reduced glutathione status. The results suggest that ACRP crosses the species barrier and it may be utilized as a viable exogenous agent of cytoprotection against heavy metal related toxicity.

  11. Simulation of Two Strategies to Limit the Impact of Fouling in Permeable Reactive Barriers

    NASA Astrophysics Data System (ADS)

    Li, L.; Benson, C.

    2008-12-01

    Ground water flow (MODFLOW) and geochemical reactive transport models (RT3D) were used to assess the effectiveness of two strategies in limiting mineral fouling and its impact on hydraulic behavior of continuous- wall permeable reactive barriers (PRBs) employing granular zero valent iron (ZVI). A geochemical algorithm including kinetic expressions of oxidation-reduction and mineral precipitation-dissolution was developed for RT3D. The two strategies that were evaluated are (i) adding pea gravel equalization zones upgradient and down gradient of the reactive zone and (ii) placement of sacrificial pretreatment zones upgradient of the reactive zone. The PRB locates at a three-dimensional heterogeneous sandy aquifer. The sacrificial pretreatment zone contains mixtures of pea gravel and ZVI. Results of simulations show that installation of pea gravel zones provides a more conductive path for ground water flow through the ZVI, which enhances preferential flow and causes greater porosity reductions and shorter residence time in the PRB. After installation of pea gravel zones, the residence time decreases which is caused by short travel distances in the ZVI due to short circuit of preferential flow. Sacrificial pretreatment zones can be used to elevate the ground water pH and consume many of the mineral forming ions to form secondary minerals in before the reactive zone is reached. The remaining mineral forming ions that pass into the reactive zone cause less mineral fouling. However, mineral fouling by Fe(OH)2 still occurs, and this mineral is formed regardless of the influent mineral forming ions. Addition of the sacrificial pretreatment zone slightly decreases the initial median residence time. However, the pretreatment zone retains higher residence time after 30 yrs due to less mineral fouling in the pure ZVI zone.

  12. Simulation of Two Strategies to Enhance Permeable Reactive Barriers in Heterogeneous Aquifer

    NASA Astrophysics Data System (ADS)

    Li, L.; Benson, C.

    2007-12-01

    Ground water flow (MODFLOW) and geochemical reactive transport models (RT3D) were used to assess the effectiveness of two strategies in limiting mineral fouling and its impact on hydraulic behavior of continuous-wall permeable reactive barriers (PRBs) employing granular zero valent iron (ZVI). A geochemical algorithm including kinetic expressions of oxidation-reduction and mineral precipitation-dissolution was developed for RT3D. The two strategies that were evaluated are (i) adding pea gravel equalization zones upgradient and down gradient of the reactive zone and (ii) placement of sacrificial pretreatment zones upgradient of the reactive zone. The PRB locates at a three-dimensional heterogeneous sandy aquifer. The sacrificial pretreatment zone contains mixtures of pea gravel and ZVI. Results of simulations show that installation of pea gravel zones provides a more conductive path for ground water flow through the ZVI, which enhances preferential flow and causes greater porosity reductions and shorter residence time in the PRB. After installation of pea gravel zones, the esidence time decreases which is caused by short travel distances in the ZVI due to short circuit of preferential flow. Sacrificial pretreatment zones can be used to elevate the ground water pH and consume many of the mineral forming ions to form secondary minerals in before the reactive zone is reached. The remaining mineral forming ions that pass into the reactive zone cause less mineral fouling. However, mineral fouling by Fe(OH)2 still occurs, and this mineral is formed regardless of the influent mineral forming ions. Addition of the sacrificial pretreatment zone slightly decreases the initial median residence time. However, the pretreatment zone retains higher residence time after 30 yrs due to less mineral fouling in the pure ZVI zone.

  13. Reactivation of Memory by Hypnosis and Suggestion. Final Report.

    ERIC Educational Resources Information Center

    London, Perry; Cooper, Leslie M.

    This study tested the hypothesis that the memory of meaningful material can be reactivated without relearning by means of hypnotic suggestion. Very susceptible (T) and non-susceptible (UT) subjects were sought from among those who volunteered for the experiment. Two forms of a memory test for connected meaningful material were developed. Each form…

  14. Development of permeable reactive barriers to prevent radionuclide migration from the nuclear waste repositories

    SciTech Connect

    Zakharova, E.; Kalmykov, S.; Batuk, O.; Kazakovskaya, T.; Shapovalov, V.; Haire, M.J.

    2007-07-01

    This paper is focused on three possible materials for permeable reactive barriers (PRB): 1) depleted uranium oxide that is accumulated as a residual product of the natural uranium enrichment process, 2) zero-valent iron and, 3) the composite material based on montmorillonite clay modified with different anion exchangers. The main aim of permeable reactive barriers is to prevent release of radionuclides emerging from a repository waste package containing spent nuclear fuel to outside the control area of the nuclear waste repository sites. The most experimentally developed material is depleted uranium oxide. It can be used both as a component of radiation shielding and as an absorbent for migrating long-lived radionuclides (especially {sup 237}Np and {sup 99}Tc). Experiments demonstrate the high sorption properties of depleted uranium oxide towards Np and Tc both from deionized water and from solution that simulates Yucca Mountain. Zero-valent iron, and the composite based on montmorillonite clay, also seem to be very promising to use in a PRB. Nano-particles of zero-valent iron with high surface will reduce high valency Np and Tc to the tetravalent state and thus immobilize them due to the extremely low solubility of corresponding hydroxides. The composite based on montmorillonite clay modified with different anion exchangers will possess high sorption affinity towards anionic and cationic species. (authors)

  15. An Injectable Apatite Permeable Reactive Barrier for In Situ 90Sr Immobilization

    SciTech Connect

    Vermeul, Vincent R.; Szecsody, James E.; Fritz, Brad G.; Williams, Mark D.; Moore, Robert C.; Fruchter, Jonathan S.

    2014-04-16

    An injectable permeable reactive barrier (PRB) technology was developed to sequester 90Sr in groundwater through the in situ formation of calcium-phosphate mineral phases, specifically apatite that incorporates 90Sr into the chemical structure. An integrated, multi-scale development and testing approach was used that included laboratory bench-scale experiments, an initial pilot-scale field test, and the emplacement and evaluation of a 300-ft-long treatability-test-scale PRB. Standard groundwater wells were used for emplacement of the treatment zone, allowing treatment of contaminants too deep below ground surface for trench-and-fill type PRB technologies. The apatite amendment formulation uses two separate precursor solutions, one containing a Ca-citrate complex and the other a Na-phosphate solution, to form apatite precipitate in situ. Citrate is needed to keep calcium in solution long enough to achieve a more uniform and areally extensive distribution of precipitate formation. In the summer of 2008, the apatite PRB technology was applied as a 91-m (300-ft) -long permeable reactive barrier on the downgradient edge of a 90Sr plume beneath the Hanford Site in Washington State. The technology was deployed to reduce 90Sr flux discharging to the Columbia River. Performance assessment monitoring data collected to date indicate the barrier is meeting performance objectives. The average reduction in 90Sr concentrations at four downgradient compliance monitoring locations was 95% relative to the high end of the baseline range approximately 1 year after treatment, and continues to meet remedial objectives more than 4 years after treatment.

  16. Remediation of TCE-contaminated groundwater by a permeable reactive barrier filled with plant mulch (Biowall).

    PubMed

    Lu, Xiaoxia; Wilson, John T; Shen, Hai; Henry, Bruce M; Kampbell, Donald H

    2008-01-01

    A pilot-scale permeable reactive barrier filled with plant mulch was installed at Altus Air Force Base in Oklahoma, USA to treat trichloroethylene (TCE) contamination in groundwater emanating from a landfill. The barrier was constructed in June 2002. It was 139 meters long, 7 meters deep, and 0.5 meters wide. The barrier is also called a Biowall because one of the mechanisms for removal of TCE is anaerobic biodegradation. This study aimed at evaluating the performance of the pilot-scale Biowall after its installation. Data from over four years' monitoring indicated that the Biowall greatly changed geochemistry in the study area and stimulated TCE removal. The concentration of TCE in the Biowall and downgradient of the Biowall was greatly reduced as compared to that in ground water upgradient of the Biowall, while the concentration of cis-DCE in the Biowall and downgradient of the Biowall was much higher than that observed upgradient of the Biowall. Over time, the concentration of vinyl chloride in the Biowall and downgradient of the Biowall increased. Dehalococcoides DNA was detected within and downgradient of the Biowall, corresponding to the observation that vinyl chloride was produced at these locations. Results from a tracer study indicated that the regional groundwater flow pattern ultimately determined the flow direction in the area around the Biowall. The natural groundwater velocity was estimated at an average of 0.060 +/- 0.015 m/d.

  17. A nano-selenium reactive barrier approach for managing mercury over the life-cycle of compact fluorescent lamps.

    PubMed

    Lee, Brian; Sarin, Love; Johnson, Natalie C; Hurt, Robert H

    2009-08-01

    Compact fluorescent lamps contain small quantities of mercury, release of which can lead to human exposures of potential concern in special cases involving multiple lamps, confined spaces, or young children. The exposure scenarios typically involve solid lamp debris that slowly releases elemental mercury vapor to indoor spaces. Here we propose and demonstrate a reactive barrier approach for the suppression of that mercury release, and demonstrate the concept using uncoated amorphous nanoselenium as the reactive component. Multilayer structures containing an impregnated reactive layer and a mercury vapor barrier are fabricated, characterized, and evaluated in three exposure prevention scenarios: carpeted break sites, disposal/recycling bags, and boxes as used for retail sales, shipping, and collection. The reactive barriers achieve significant suppression of mercury release to indoor spaces in each of thethree scenarios. The nanoselenium barriers also exhibit a unique indicator function that can reveal the location of Hg contamination by local reaction-induced change in optical properties. The article also presents results on equilibrium Hg vapor pressure above lamp debris, mathematical modeling of reaction and transport processes within reactive barriers, and landfill stability of nanoselenium and its reaction products.

  18. A Nano-Selenium Reactive Barrier Approach for Managing Mercury over the Life-Cycle of Compact Fluorescent Lamps

    PubMed Central

    Lee, Brian; Sarin, Love; Johnson, Natalie C.; Hurt, Robert H.

    2013-01-01

    Compact fluorescent lamps contain small quantities of mercury, whose release can lead to human exposures of potential concern in special cases involving multiple lamps, confined spaces, or young children. The exposure scenarios typically involve solid lamp debris that slowly releases elemental mercury vapor to indoor spaces. Here we propose and demonstrate a reactive barrier approach for the suppression of that mercury release, and demonstrate the concept using uncoated amorphous nano-selenium as the reactive component. Multi-layer structures containing an impregnated reactive layer and a mercury vapor barrier are fabricated, characterized, and evaluated in three exposure prevention scenarios: carpeted break sites, disposal/recycling bags, and boxes as used for retail sales, shipping and collection. The reactive barriers achieve significant suppression of mercury release to indoor spaces in each of the three scenarios. The nano-selenium barriers also exhibit a unique indicator function that can reveal the location of Hg-contamination by local reaction-induced change in optical properties. The article also presents results on equilibrium Hg vapor pressure above lamp debris, mathematical modeling of reaction and transport processes within reactive barriers, and landfill stability of nano-selenium and its reaction products. PMID:19731697

  19. Life-cycle case study comparison of permeable reactive barrier versus pump-and-treat remediation.

    PubMed

    Higgins, Monica R; Olson, Terese M

    2009-12-15

    A permeable reactive barrier (PRB) is a passive remediation technology, which over decades of use, may reduce lifetime environmental impacts when compared with a conventional pump-and-treat system (PTS). Greater material production requirements to install PRBs may offset the expected reductions in operational phase impacts and the trade-offs can be investigated in a life-cycle assessment (LCA). The life-cycle environmental impacts of a zerovalent iron (ZVI) containing PRB with a funnel and gate configuration and a PTS were compared in a case study. Potential impacts of the model PRB are driven by the ZVI reactive medium and the energy usage during construction, while for the PTS they are driven by the operational energy demand. Medium longevity governed the magnitude of the potential PRB impacts and the extent to which it was optimal relative to the PTS. Even at conservatively low estimates of longevity, the PRB offers significant environmental advantages in impact categories of human health and ozone depletion. The minimum ZVI longevity for PRB benefit over the PTS system in all impact categories was 10 years. Suggested PRB design innovations to reduce environmental impacts include the development of alternative reactive media and construction methods.

  20. Sustained-Release Permanganate: Passive Reactive Barriers for Green and Sustainable Remediation

    NASA Astrophysics Data System (ADS)

    Dugan, P. J.

    2011-12-01

    Reactive materials in permeable reactive barriers (PRBs) have proven very useful for transforming or destroying organic waste in situ. Once emplaced they typically do not require a continued supply of electrical power and have the added benefit of creating a reactive zone for the destruction of contaminants in place. Controlled-release techniques have been utilized extensively in diverse fields such as pharmaceutical and agrochemical technologies. However, controlled- and sustained release of an oxidant during in situ chemical oxidation (ISCO) is an emerging concept that is extremely relevant to the field of environmental remediation, yet to-date has received little attention. ISCO using the oxidants permanganate, persulfate, and catalyzed hydrogen peroxide has shown great promise for remediation of many recalcitrant organic contaminants of concern (COC). Because the oxidant also reacts with natural organic matter, inorganic soil constituents, and other reduced compounds, the presence of a protective barrier that controls oxidant release may enhance the efficiency of ISCO and allow for long-term low-cost treatment of chlorinated solvents. To this end, sustained-release permanganate (SRP) was developed. Paraffin wax was used as the environmentally benign and biodegradable matrix material for encapsulating the solid potassium permanganate (KMnO4) particles. The paraffin matrix protects the solid KMnO4 particles from fast dissolution and potentially undesirable nonproductive reactions. The SRP material contains between 60%-80% permanganate and can be formed as candles for direct push applications in reactive barriers, or chipped material for hydro-fracturing into low permeability media. One-dimensional (1-D) SRP column experiments were conducted to evaluate permanganate release behavior using deionized (DI) water as the influent or COC removal efficiency using dissolved trichloroethene (TCE) as the influent. The influent dissolved TCE concentrations were 1 mg/L and

  1. Gap Junction Proteins in the Blood-Brain Barrier Control Nutrient-Dependent Reactivation of Drosophila Neural Stem Cells

    PubMed Central

    Spéder, Pauline; Brand, Andrea H.

    2014-01-01

    Summary Neural stem cells in the adult brain exist primarily in a quiescent state but are reactivated in response to changing physiological conditions. How do stem cells sense and respond to metabolic changes? In the Drosophila CNS, quiescent neural stem cells are reactivated synchronously in response to a nutritional stimulus. Feeding triggers insulin production by blood-brain barrier glial cells, activating the insulin/insulin-like growth factor pathway in underlying neural stem cells and stimulating their growth and proliferation. Here we show that gap junctions in the blood-brain barrier glia mediate the influence of metabolic changes on stem cell behavior, enabling glia to respond to nutritional signals and reactivate quiescent stem cells. We propose that gap junctions in the blood-brain barrier are required to translate metabolic signals into synchronized calcium pulses and insulin secretion. PMID:25065772

  2. Predicting longevity of iron permeable reactive barriers using multiple iron deactivation models

    NASA Astrophysics Data System (ADS)

    Carniato, L.; Schoups, G.; Seuntjens, P.; Van Nooten, T.; Simons, Q.; Bastiaens, L.

    2012-11-01

    In this study we investigate the model uncertainties involved in predicting long-term permeable reactive barrier (PRB) remediation efficiency based on a lab-scale column experiment under accelerated flow conditions. A PRB consisting of 20% iron and 80% sand was simulated in a laboratory-scale column and contaminated groundwater was pumped into the column for approximately 1 year at an average groundwater velocity of 3.7E - 1 m d- 1. Dissolved contaminants (PCE, TCE, cis-DCE, trans-DCE and VC) and inorganic (Ca2 +, Fe2 +, TIC and pH) concentrations were measured in groundwater sampled at different times and at eight different distances along the column. These measurements were used to calibrate a multi-component reactive transport model, which subsequently provided predictions of long-term PRB efficiency under reduced flow conditions (i.e., groundwater velocity of 1.4E - 3 m d- 1), representative of a field site of interest in this study. Iron reactive surface reduction due to mineral precipitation and iron dissolution was simulated using four different models. All models were able to reasonably well reproduce the column experiment measurements, whereas the extrapolated long-term efficiency under different flow rates was significantly different between the different models. These results highlight significant model uncertainties associated with extrapolating long-term PRB performance based on lab-scale column experiments. These uncertainties should be accounted for at the PRB design phase, and may be reduced by independent experiments and field observations aimed at a better understanding of reactive surface deactivation mechanisms in iron PRBs.

  3. Overview on backfill materials and permeable reactive barriers for nuclear waste disposal facilities.

    SciTech Connect

    Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Holt, Kathleen Caroline; Hasan, Mahmoud A. (Egyptian Atomic Energy Authority, Cairo, Egypt)

    2003-10-01

    A great deal of money and effort has been spent on environmental restoration during the past several decades. Significant progress has been made on improving air quality, cleaning up and preventing leaching from dumps and landfills, and improving surface water quality. However, significant challenges still exist in all of these areas. Among the more difficult and expensive environmental problems, and often the primary factor limiting closure of contaminated sites following surface restoration, is contamination of ground water. The most common technology used for remediating ground water is surface treatment where the water is pumped to the surface, treated and pumped back into the ground or released at a nearby river or lake. Although still useful for certain remediation scenarios, the limitations of pump-and-treat technologies have recently been recognized, along with the need for innovative solutions to ground-water contamination. Even with the current challenges we face there is a strong need to create geological repository systems for dispose of radioactive wastes containing long-lived radionuclides. The potential contamination of groundwater is a major factor in selection of a radioactive waste disposal site, design of the facility, future scenarios such as human intrusion into the repository and possible need for retrieving the radioactive material, and the use of backfills designed to keep the radionuclides immobile. One of the most promising technologies for remediation of contaminated sites and design of radioactive waste repositories is the use of permeable reactive barriers (PRBs). PRBs are constructed of reactive material(s) to intercept and remove the radionuclides from the water and decontaminate the plumes in situ. The concept of PRBs is relatively simple. The reactive material(s) is placed in the subsurface between the waste or contaminated area and the groundwater. Reactive materials used thus far in practice and research include zero valent iron

  4. Organic/inorganic nanocomposites, methods of making, and uses as a permeable reactive barrier

    DOEpatents

    Harrup, Mason K.; Stewart, Frederick F.

    2007-05-15

    Nanocomposite materials having a composition including an inorganic constituent, a preformed organic polymer constituent, and a metal ion sequestration constituent are disclosed. The nanocomposites are characterized by being single phase, substantially homogeneous materials wherein the preformed polymer constituent and the inorganic constituent form an interpenetrating network with each other. The inorganic constituent may be an inorganic oxide, such as silicon dioxide, formed by the in situ catalyzed condensation of an inorganic precursor in the presence of the solvated polymer and metal ion sequestration constituent. The polymer constituent may be any hydrophilic polymer capable of forming a type I nanocomposite such as, polyacrylonitrile (PAN), polyethyleneoxide (PEO), polyethylene glycol (PEG), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), and combinations thereof. Nanocomposite materials of the present invention may be used as permeable reactive barriers (PRBs) to remediate contaminated groundwater. Methods for making nanocomposite materials, PRB systems, and methods of treating groundwater are also disclosed.

  5. Ground water remediation of chromium using zero-valent iron in a permeable reactive barrier

    SciTech Connect

    Puls, R.W.; Powell, R.M.; Paul, C.J.; Blowes, D.

    1998-09-01

    A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of iron and in systems with iron mixed with aquifer materials. Various geochemical parameters were measured to confirm the proposed reactions. Laboratory experiments were scaled up to pilot and full-scale field demonstrations. Intensive geochemical sampling in the field tests corroborate laboratory results and successfully demonstrate the effectiveness of this innovative in situ approach to remediate chromate-contaminated ground water using a permeable reactive barrier composed of zero-valent iron.

  6. Design, installation, and performance of a multi-layered permeable reactive barrier, Los Alamos National Laboratory

    SciTech Connect

    Kaszuba, J. P.; Longmire, P. A.; Strietelmeier, E. A.; Taylor, T. P.; Den-Baars, P. S.

    2004-01-01

    A multi-layered permeable reactive barrier (PRB) has been installed in Mortandad Canyon, on the Pajarito Plateau in the north-central part of LANL, to demonstrate in-situ treatment of a suite of contaminants with dissimilar geochemical properties. The PRB will also mitigate possible vulnerabilities from downgradient contaminant movement within alluvial and deeper perched groundwater. Mortandad Canyon was selected as the location for this demonstration project because the flow of alluvial groundwater is constrained by the geology of the canyon, a large network of monitoring wells already were installed along the canyon reach, and the hydrochemistry and contaminant history of the canyon is well-documented. The PRB uses a funnel-and-gate system with a series of four reactive media cells to immobilize or destroy contaminants present in alluvial groundwater, including strontium-90, plutonium-238,239,240, americium-241, perchlorate, and nitrate. The four cells, ordered by sequence of contact with the groundwater, consist of gravel-sized scoria (for colloid removal); phosphate rock containing apatite (for metals and radionuclides); pecan shells and cotton seed admixed with gravel (bio-barrier, to deplete dissolved oxygen and destroy potential RCRA organic compounds, nitrate and perchlorate); and limestone (pH buffering and anion adsorption). Design elements of the PRB are based on laboratory-scale treatability studies and on a field investigation of hydrologic, geochemical, and geotechnical parameters. The PRB was designed with the following criteria: 1-day residence time within the biobarrier, 10-year lifetime, minimization of surface water infiltration and erosion, optimization of hydraulic capture, and minimization of excavated material requiring disposal. Each layer has been equipped with monitoring wells or ports to allow sampling of groundwater and reactive media, and monitor wells are located immediately adjacent to the up- and down-gradient perimeter of the

  7. Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater

    PubMed Central

    Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N.

    2012-01-01

    A novel reactive electrochemical flow system consisting of iron anode and porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides proton and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (< 7.5 mg/L) and high current (> 45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants from flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures. PMID:23067023

  8. The Effect of Chemical Reactivity and Charge Transfer on Gallium-Arsenide (110) Schottky Barrier Formation.

    NASA Astrophysics Data System (ADS)

    Williams, Michael Duryea

    Transition and near noble metals have been deposited in sequential steps on atomically clean cleaved Gallium Arsenide (GaAs) surfaces under ultra-high vacuum conditions. Soft X-ray and ultra-violet photoemission spectroscopies were used to elucidate the room temperature (RT) chemistry and Fermi level pinning behaviors of these systems. The results show that the nature or degree of the chemical reaction has little effect on the Schottky barrier (SB) height of the metal-semiconductor contact. Silver (Ag), Gold (Au), Copper (Cu) and Palladium (Pd) for example, exhibit a range of chemical reactivities with the substrate going from non-reactive in the case of Ag to very reactive for Pd. These all have a SB height of 0.9 electron volts (eV) for n-type GaAs. Nickel (Ni), Chromium (Cr) and Titanium (Ti), on the other hand, also react strongly but have a SB height of 0.7 eV. The pinning position of the Fermi level at the interface for the established barrier (with the exception of the Ag contact) is also found to be independent of whether the substrate is doped n or p-type. An examination of trends in charge transfer parameters between the metal overlayer and the substrate has led to a strong correlation between the electronegativity (Pauling's scale) of the metal and the observed SB height. It is suggested that the formation of a dipole at the interface effects a charge transfer between the adatom induced defect levels and the metal overlayer consistent with charge neutrality. As a test, two additional sets of experiments were performed. The first is a study of Ytterbium (Yb) on the GaAs suabstrate. The unique chemistry of the rare earth metal provides further proof that the SB height is independent of chemistry. The second set of experiments is a kinetic study of the development of the Aluminum (Al)/GaAs SB. The RT and low temperature ((LESSTHEQ)-50(DEGREES)C) substrates show a significant variation in the pinning behavior of the interfacial Fermi level with coverage. The

  9. TREATMENT OF METALS IN GROUND WATER USING AN ORGANIC-BASED SULFATE-REDUCING PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    A pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI) filings, limestone and pea gravel was evaluated at a former phosphate fertilizer manufacturing facility in Charleston, S.C. The PRB is designed to treat arsenic and heavy met...

  10. Fifteen-year Assessment of a Permeable Reactive Barrier for Treatment of Chromate and Trichloroethylene in Groundwater

    EPA Science Inventory

    The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium sou...

  11. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS USING ZERO-VALENT IRON: GEOCHEMICAL AND MICROBIOLOGICAL EFFECTS

    EPA Science Inventory

    Geochemical and microbiological factors that control long-term performance of subsurface permeable reactive barriers were evaluated at the Elizabeth City, NC and the Denver Federal Center, CO sites. These ground water treatment systems use zero-valent iron filings (Peerless Meta...

  12. Permeable Reactive Barriers Designed To Mitigate Eutrophication Alter Bacterial Community Composition and Aquifer Redox Conditions.

    PubMed

    Hiller, Kenly A; Foreman, Kenneth H; Weisman, David; Bowen, Jennifer L

    2015-10-01

    Permeable reactive barriers (PRBs) consist of a labile carbon source that is positioned to intercept nitrate-laden groundwater to prevent eutrophication. Decomposition of carbon in the PRB drives groundwater anoxic, fostering microbial denitrification. Such PRBs are an ideal habitat to examine microbial community structure under high-nitrate, carbon-replete conditions in coastal aquifers. We examined a PRB installed at the Waquoit Bay National Estuarine Research Reserve in Falmouth, MA. Groundwater within and below the PRB was depleted in oxygen compared to groundwater at sites upgradient and at adjacent reference sites. Nitrate concentrations declined from a high of 25 μM upgradient and adjacent to the barrier to <0.1 μM within the PRB. We analyzed the total and active bacterial communities filtered from groundwater flowing through the PRB using amplicons of 16S rRNA and of the 16S rRNA genes. Analysis of the 16S rRNA genes collected from the PRB showed that the total bacterial community had high relative abundances of bacteria thought to have alternative metabolisms, such as fermentation, including candidate phyla OD1, OP3, TM7, and GN02. In contrast, the active bacteria had lower abundances of many of these bacteria, suggesting that the bacterial taxa that differentiate the PRB groundwater community were not actively growing. Among the environmental variables analyzed, dissolved oxygen concentration explained the largest proportion of total community structure. There was, however, no significant correlation between measured environmental parameters and the active microbial community, suggesting that controls on the active portion may differ from the community as a whole.

  13. Monitoring Performance of a Dual Wall Permeable Reactive Barrier for Treating Perchlorate and TCE

    NASA Astrophysics Data System (ADS)

    Dowman, C. E.; Hashimoto, Y.; Warner, S.; Bennett, P.; Gandhi, D.; Szerdy, F.; Neville, S.; Fennessy, C.; Scow, K. M.

    2008-12-01

    AMEC Geomatrix, through collaboration with Aerojet General Corporation and the University of California, Davis (UCD), has performed work leading to the installation of a dual wall permeable reactive barrier (PRB) system capable of treating perchlorate and chlorinated aliphatic hydrocarbon compounds (CAHs), including trichloroethylene (TCE), at Aerojet's Area 40 site in Sacramento, California. This unique system consisted of an upgradient zero-valent iron (ZVI) permeable reactive barrier (PRB) that is intended to not only degrade CAHs, but also, provide hydrogen generated from the ZVI corrosion process, to a downgradient bio-effective PRB (carbohydrate solution circulated through a gravel-packed trench) for destroying perchlorate. The subsurface was characterized during a site investigation, and numerous logistical and site-specific challenges of installation were addressed. The site-specific challenges included installation of a passive remediation system in a remote location with no access to electricity. The selected remediation system was keyed into the undulating bedrock 20 to 25 feet below the ground surface without the use of shoring. Under a collaborative effort, UCD provided initial bench testing. AMEC Geomatrix designed and installed the dual wall system consisting of two approximately parallel 50-foot long by 2-foot thick by 25-foot deep PRB segments which are separated by about 8 feet perpendicular to the approximate direction of groundwater flow. AMEC Geomatrix performed the installation of performance monitoring network, which consisted of 21 wells, and monitored these points for a 6-month period. Monitoring and sampling techniques were designed to measure water levels and water quality parameters in the subsurface during sampling events, to better assess the hydrologic and chemical processes. The monitoring results indicate that the upgradient ZVI PRB effectively treats groundwater with TCE concentrations approaching 60 mg/L, and in addition, may

  14. Application Of Immobilized Sulfate Reducing Bacteria For Permeable Reactive Barriers In Abandoned Coal Mines

    NASA Astrophysics Data System (ADS)

    Kim, K.; Hur, W.; Choi, S.; Min, K.; Baek, H.

    2006-05-01

    The decline of the Korean coal industry has been drastic in production and consumption. This has been resulted mainly from the environmental concern and the collapse of commercial viability, which has eventually necessitated the government to implement the coal industry rationalization policies to reduce coal production and close down uneconomical mines. The overall drainage rates from abandoned coal mines reaches up to 80,000 ton/day. As a measure of controlling the acid mine drainage from abandoned coal mines, reactive materials in the pathways of drainage, designed to intercept and to transform the contaminants into environmentally acceptable forms can be applied at mines with small drainage rates. The main objective of this study is to design a permeable reactive barrier(PRB) to treat low flow and/or low contaminant loads of acid mine drainage. The PRB is comprised of immobilized sulfate reducing bacteria in hard beads and limestone to remove heavy metals and to raise the pH of AMD. A laboratory reactor was used to prepare a mixed culture of sulfate reducing bacteria. The microbes were separated and mixed with biodegradable matrix to form spherical beads. In order to maintain the viability of micro-organisms for a prolonged period, substrates such as saw dust, polysaccharide or glycerol was supplemented for the beads preparation. The strength of beads fortified by powered limestone to control the permeability of PRB. Different mixtures of limestone and the immobilized beads were tested to determine hydraulic conductivity and AMD treatment capacities. The characteristics of the spherical beads at various pH of AMD was investigated.

  15. Ammonium removal from groundwater using a zeolite permeable reactive barrier: a pilot-scale demonstration.

    PubMed

    Li, Shengpin; Huang, Guoxin; Kong, Xiangke; Yang, Yingzhao; Liu, Fei; Hou, Guohua; Chen, Honghan

    2014-01-01

    In situ remediation of ammonium-contaminated groundwater is possible through a zeolite permeable reactive barrier (PRB); however, zeolite's finite sorption capacity limits the long-term field application of PRBs. In this paper, a pilot-scale PRB was designed to achieve sustainable use of zeolite in removing ammonium (NH(4)(+)-N) through sequential nitrification, adsorption, and denitrification. An oxygen-releasing compound was added to ensure aerobic conditions in the upper layers of the PRB where NH(4)(+)-N was microbially oxidized to nitrate. Any remaining NH(4)(+)-N was removed abiotically in the zeolite layer. Under lower redox conditions, nitrate formed during nitrification was removed by denitrifying bacteria colonizing the zeolite. During the long-term operation (328 days), more than 90% of NH(4)(+)-N was consistently removed, and approximately 40% of the influent NH(4)(+)-N was oxidized to nitrate. As much as 60% of the nitrate formed in the PRB was reduced in the zeolite layer after 300 days of operation. Removal of NH(4)(+)-N from groundwater using a zeolite PRB through bacterial nitrification and abiotic adsorption is a promising approach. The zeolite PRB has the advantage of achieving sustainable use of zeolite and immediate NH(4)(+)-N removal.

  16. Pervious concrete reactive barrier for removal of heavy metals from acid mine drainage - column study.

    PubMed

    Shabalala, Ayanda N; Ekolu, Stephen O; Diop, Souleymane; Solomon, Fitsum

    2017-02-05

    This paper presents a column study conducted to investigate the potential use of pervious concrete as a reactive barrier for treatment of water impacted by mine waste. The study was done using acid mine drainage (AMD) collected from a gold mine (WZ) and a coalfield (TDB). Pervious concrete mixtures consisting of Portland cement CEM I 52.5R with or without 30% fly ash (FA) were prepared at a water-cementitious ratio of 0.27 then used to make cubes which were employed in the reactor columns. It was found that the removal efficiency levels of Al, Fe, Mn, Co and Ni were 75%, 98%, 99%, 94% and 95% for WZ; 87%, 96%, 99%, 98% and 90% for TDB, respectively. The high rate of acid reduction and metal removal by pervious concrete is attributed to dissolution of portlandite which is a typical constituent of concrete. The dominant reaction product in all four columns was gypsum, which also contributed to some removal of sulphate from AMD. Formation of gypsum, goethite, and Glauber's salt were identified. Precipitation of metal hydroxides seems to be the dominant metal removal mechanism. Use of pervious concrete offers a promising alternative treatment method for polluted or acidic mine water.

  17. Utilization of natural hematite as reactive barrier for immobilization of radionuclides from radioactive liquid waste.

    PubMed

    El Afifi, E M; Attallah, M F; Borai, E H

    2016-01-01

    Potential utilization of hematite as a natural material for immobilization of long-lived radionuclides from radioactive liquid waste was investigated. Hematite ore has been characterized by different analytical tools such as Fourier transformer infrared (FTIR), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal (DT) analysis, scanning electron microscopy (SEM) and BET-surface area. In this study, europium was used as REEs(III) and as a homolog of Am(III)-isotopes (such as (241)Am of 432.6 y, (242m)Am of 141 y and (243)Am of 7370 y). Micro particles of the hematite ore were used for treatment of radioactive waste containing (152+154)Eu(III). The results indicated that 96% (4.1 × 10(4) Bq) of (152+154)Eu(III) was efficiently retained onto hematite ore. Kinetic experiments indicated that the processes could be simulated by a pseudo-second-order model and suggested that the process may be chemisorption in nature. The applicability of Langmuir, Freundlich and Temkin models was investigated. It was found that Langmuir isotherm exhibited the best fit with the experimental results. It can be concluded that hematite is an economic and efficient reactive barrier for immobilization of long-lived radio isotopes of actinides and REEs(III).

  18. Mineral Precipitation Upgradient from a Zero-Valent Iron Permeable Reactive Barrier

    SciTech Connect

    Johnson, R. L.; Thoms, R. B.; Johnson, R. O.; Nurmi, J. T.; Tratnyek, Paul G.

    2008-07-01

    Core samples taken from a zero-valent iron permeable reactive barrier (ZVI PRB) at Cornhusker Army Ammunition Plant, Nebraska, were analyzed for physical and chemical characteristics. Precipitates containing iron and sulfide were present at much higher concentrations in native aquifer materials just upgradient of the PRB than in the PRB itself. Sulfur mass balance on core solids coupled with trends in ground water sulfate concentrations indicates that the average ground water flow after 20 months of PRB operation was approximately twenty fold less than the regional ground water velocity. Transport and reaction modeling of the aquifer PRB interface suggests that, at the calculated velocity, both iron and hydrogen could diffuse upgradient against ground water flow and thereby contribute to precipitation in the native aquifer materials. The initial hydraulic conductivity (K) of the native materials is less than that of the PRB and, given the observed precipitation in the upgradient native materials, it is likely that K reduction occurred upgradient to rather than within the PRB. Although not directly implicated, guar gum used during installation of the PRB is believed to have played a role in the precipitation and flow reduction processes by enhancing microbial activity.

  19. Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado.

    SciTech Connect

    Moore, Robert C.; Szecsody, James; Rigali, Mark J.; Vermuel, Vince; Leullen, Jon

    2016-02-01

    We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests to study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.

  20. Benzene and toluene biodegradation down gradient of a zero-valent iron permeable reactive barrier.

    PubMed

    Chen, Liang; Liu, Fei; Liu, Yulong; Dong, Hongzhong; Colberg, Patricia J S

    2011-04-15

    This study simulated benzene and toluene biodegradation down gradient of a zero-valent iron permeable reactive barrier (ZVI PRB) that reduces trichloroethylene (TCE). The effects of elevated pH (10.5) and the presence of a common TCE dechlorination by product [cis-1,2-dichloroethene (cis-1,2-DCE)] on benzene and toluene biodegradation were evaluated in batch experiments. The data suggest that alkaline pH (pH 10.5), often observed down gradient of ZVI PRBs, inhibits Fe(III)-mediated biotransformation of both benzene and toluene. Removal was reduced by 43% for benzene and 26% for toluene as compared to the controls. The effect of the addition of cis-1,2-DCE on benzene and toluene biodegradation was positive and resulted in removal that was greater than or equal to the controls. These results suggest that, at least for cis-1,2-DCE, its formation may not be toxic to iron-reducing benzene and toluene degrading bacteria; however, for microbial benzene and toluene removal down gradient of a ZVI PRB, it may be necessary to provide pH control, especially in the case of a biological PRB that is downstream from a ZVI PRB.

  1. Measurement and modelling of reactive transport in geological barriers for nuclear waste containment.

    PubMed

    Xiong, Qingrong; Joseph, Claudia; Schmeide, Katja; Jivkov, Andrey P

    2015-11-11

    Compacted clays are considered as excellent candidates for barriers to radionuclide transport in future repositories for nuclear waste due to their very low hydraulic permeability. Diffusion is the dominant transport mechanism, controlled by a nano-scale pore system. Assessment of the clays' long-term containment function requires adequate modelling of such pore systems and their evolution. Existing characterisation techniques do not provide complete pore space information for effective modelling, such as pore and throat size distributions and connectivity. Special network models for reactive transport are proposed here using the complimentary character of the pore space and the solid phase. This balances the insufficient characterisation information and provides the means for future mechanical-physical-chemical coupling. The anisotropy and heterogeneity of clays is represented using different length parameters and percentage of pores in different directions. Resulting networks are described as mathematical graphs with efficient discrete calculus formulation of transport. Opalinus Clay (OPA) is chosen as an example. Experimental data for the tritiated water (HTO) and U(vi) diffusion through OPA are presented. Calculated diffusion coefficients of HTO and uranium species are within the ranges of the experimentally determined data in different clay directions. This verifies the proposed pore network model and validates that uranium complexes are diffusing as neutral species in OPA. In the case of U(vi) diffusion the method is extended to account for sorption and convection. Rather than changing pore radii by coarse grained mathematical formula, physical sorption is simulated in each pore, which is more accurate and realistic.

  2. Monitoring the removal of phosphate from ground water discharging through a pond-bottom permeable reactive barrier

    USGS Publications Warehouse

    McCobb, T.D.; LeBlanc, D.R.; Massey, A.J.

    2009-01-01

    Installation of a permeable reactive barrier to intercept a phosphate (PO4) plume where it discharges to a pond provided an opportunity to develop and test methods for monitoring the barrier's performance in the shallow pond-bottom sediments. The barrier is composed of zero-valent-iron mixed with the native sediments to a 0.6-m depth over a 1100-m2 area. Permanent suction, diffusion, and seepage samplers were installed to monitor PO 4 and other chemical species along vertical transects through the barrier and horizontal transects below and near the top of the barrier. Analysis of pore water sampled at about 3-cm vertical intervals by using multilevel diffusion and suction samplers indicated steep decreases in PO4 concentrations in ground water flowing upward through the barrier. Samples from vertically aligned pairs of horizontal multiport suction samplers also indicated substantial decreases in PO4 concentrations and lateral shifts in the plume's discharge area as a result of varying pond stage. Measurements from Lee-style seepage meters indicated substantially decreased PO4 concentrations in discharging ground water in the treated area; temporal trends in water flux were related to pond stage. The advantages and limitations of each sampling device are described. Preliminary analysis of the first 2 years of data indicates that the barrier reduced PO4 flux by as much as 95%. ?? 2009 National Ground Water Association.

  3. Experimental and Theoretical Assessment of the Lifetime of a Gaseous-Reduced Vadose Zone Permeable Reactive Barrier

    SciTech Connect

    Thornton, Edward C.; Zhong, Lirong; Oostrom, Mart; Deng, Baolin

    2007-11-20

    The feasibility of using gaseous reduction to establish a vadose zone permeable reactive barrier was evaluated through a combination of laboratory testing activities and consideration of fundamental vadose zone transport concepts. For the experimental evaluation, a series of laboratory column tests were conducted in which sediment was first treated with diluted hydrogen sulfide. Water containing dissolved oxygen was then pumped through the columns at different flow rates to determine the reoxidation rate and the reductive capacity of the treated sediment. The results indicated that the treated sediment has a significant reductive capacity consistent with the basic reactions associated with the treatment and reoxidation processes. The observed reductive capacity was found to be dependent on the flow rate of water during the reoxidation phase of the tests. At lower flow rates, the reductive capacity approached the maximum value predicted on the basis of the treatment reaction. Thus, laboratory treatment tests should reliably predict the reductive capacity of the barrier under field conditions. A theoretical approach was undertaken to estimate the lifetime of the vadose zone barrier. An initial model assumed that the barrier lifetime is determined by the reoxidation of the barrier owing to the transport of oxygen through a vadose zone interval in which all sediment is unsaturated. The results of this evaluation suggest that barrier reoxidation is primarily related to diffusion of oxygen through the gas-filled portion of the sediment pore space. If so, the barrier lifetime could be fairly short (several years). However, the presence of finer grained strata with higher moisture content could potentially increase the barrier lifetime to 100 years or more owing to a decrease in the effective diffusion coefficient for oxygen. Thus, detailed stratagraphic characterization and modeling is needed to provide an accurate assessment of barrier lifetime at specific sites.

  4. Field Demonstration/Validation of Electrolytic Reactive Barriers for Energetic Compounds at Pueblo Chemical Depot

    DTIC Science & Technology

    2010-07-01

    18 6.6.2 Electrical Systems ................................................................ 20 6.6.3 Water Quality...alignment of the e-barrier. ....................................................................... 20 Figure 18. Solar power supply...21 Figure 20. Water quality sampling point attached to the e-barrier

  5. Selected hydrologic data for the field demonstration of three permeable reactive barriers near Fry Canyon, Utah, 1996-2000

    USGS Publications Warehouse

    Wilkowske, Chris D.; Rowland, Ryan C.; Naftz, David L.

    2001-01-01

    Three permeable reactive barriers (PRBs) were installed near Fry Canyon, Utah, in August 1997 to demonstrate the use of PRBs to control the migration of uranium in ground water. Reactive material included (1) bone-char phosphate, (2) zero-valent iron pellets, and (3) amorphous ferric oxyhydroxide coated gravel. An extensive monitoring network was installed in and around each PRB for collection of water samples, analysis of selected water-quality parameters, and monitoring of water levels. Water temperature, specific conductance, pH, Eh (oxidation-reduction potential), and dissolved oxygen were measured continuously within three different barrier materials, and in two monitoring wells. Water temperature and water level below land surface were electronically recorded every hour with pressure transducers. Data were collected from ground-water monitoring wells installed in and around the PRBs during 1996-98 and from surface-water sites in Fry Creek.

  6. Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

    PubMed Central

    Arjunan, Krishna Priya; Friedman, Gary; Fridman, Alexander; Clyne, Alisa Morss

    2012-01-01

    Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), has recently emerged as an efficient tool in medical applications including blood coagulation, sterilization and malignant cell apoptosis. Liquids and porcine aortic endothelial cells were treated with a non-thermal dielectric barrier discharge plasma in vitro. Plasma treatment of phosphate-buffered saline (PBS) and serum-free medium increased ROS concentration in a dose-dependent manner, with a higher concentration observed in serum-free medium compared with PBS. Species concentration inside cells peaked 1 h after treatment, followed by a decrease 3 h post treatment. Endothelial cells treated with a plasma dose of 4.2 J cm–2 had 1.7 times more cells than untreated samples 5 days after plasma treatment. The 4.2 J cm–2 plasma dose increased two-dimensional migration distance by 40 per cent compared with untreated control, while the number of cells that migrated through a three-dimensional collagen gel increased by 15 per cent. Tube formation was also enhanced by plasma treatment, with tube lengths in plasma-treated samples measuring 2.6 times longer than control samples. A fibroblast growth factor-2 (FGF-2) neutralizing antibody and ROS scavengers abrogated these angiogenic effects. These data indicate that plasma enhanced proliferation, migration and tube formation is due to FGF-2 release induced by plasma-produced ROS. Non-thermal plasma may be used as a potential tool for applying ROS in precise doses to enhance vascularization. PMID:21653568

  7. Remediation of RDX- and HMX-contaminated groundwater using organic mulch permeable reactive barriers.

    PubMed

    Ahmad, Farrukh; Schnitker, Stephen P; Newell, Charles J

    2007-02-20

    Organic mulch is a complex organic material that is typically populated with its own consortium of microorganisms. The organisms in mulch breakdown complex organics to soluble carbon, which can then be used by these and other microorganisms as an electron donor for treating RDX and HMX via reductive pathways. A bench-scale treatability study with organic mulch was conducted for the treatment of RDX- and HMX-contaminated groundwater obtained from a plume at the Pueblo Chemical Depot (PCD) in Pueblo, Colorado. The site-specific cleanup criteria of 0.55 ppb RDX and 602 ppb HMX were used as the logical goals of the study. Column flow-through tests were run to steady-state at the average site seepage velocity, using a 70%:30% (vol.:vol.) mulch:pea gravel packing to approach the formation's permeability. Significant results included: (1) Complete removal of 90 ppb influent RDX and 8 ppb influent HMX in steady-state mulch column effluent; (2) pseudo-first-order steady-state kinetic rate constant, k, of 0.20 to 0.27 h(-1) based on RDX data, using triplicate parallel column runs; (3) accumulation of reduced RDX intermediates in the steady-state column effluent at less than 2% of the influent RDX mass; (4) no binding of RDX to the column fill material; and (5) no leaching of RDX, HMX or reduction intermediates from the column fill material. The results of the bench-scale study will be used to design and implement a pilot-scale organic mulch/pea gravel permeable reactive barrier (PRB) at the site.

  8. Remediation of MSW landfill leachate by permeable reactive barrier with vegetation.

    PubMed

    Chiemchaisri, Chart; Chiemchaisri, Wilai; Witthayapirom, Chayanid

    2015-01-01

    This research was conducted to investigate in situ treatment of leachate by pilot-scale permeable reactive barrier (PRB) with vegetation. Two different types of PRB media, with and without the presence of ferric chloride sludge, for the removal of pollutants were examined. The composite media of PRB comprised a clay and sand mixture of 40:60%w/w (system 1) and a clay, ferric chloride sludge and sand mixture of 30:10:60%w/w (system 2). The system was operated at a hydraulic loading rate of 0.028 m3/m2.d and hydraulic retention time of 10 days. The results showed that the performance of system 2 was better in terms of pollutant removal efficiencies, with average biochemical oxygen demand, chemical oxygen demand and total Kjeldahl nitrogen removals of 76.1%, 68.5% and 73.5%, respectively. Fluorescence excitation-emission matrix analyses of water samples and sequential extraction of PRB media suggested the removal of humic substances through the formation of iron-organic complex. Greenhouse gas (GHG) emissions during the treatment of PRB were 8.2-52.1 mgCH4/m2.d, 69.1-601.8 mgCO2/m2.d and 0.04-0.99 mgN2O/m2.d. The use of system 2 with vegetation resulted in lower GHG emissions. The results show that PRB with vegetation could be used as a primary treatment for leachate from closed landfill sites.

  9. Chromium-Removal Processes during Groundwater Remediation by a Zerovalent Iron Permeable Reactive Barrier

    SciTech Connect

    Wilkin, Richard T.; Su, Chunming; Ford, Robert G.; Paul, Cynthia J.

    2008-06-09

    Solid-phase associations of chromium were examined in core materials collected from a full-scale, zerovalent iron permeable reactive barrier (PRB) at the U.S. Coast Guard Support Center located near Elizabeth City, NC. The PRB was installed in 1996 to treat groundwater contaminated with hexavalent chromium. After eight years of operation, the PRB remains effective at reducing concentrations of Cr from average values >1500 {micro}g L{sup -1} in groundwater hydraulically upgradient of the PRB to values <1 {micro}g L{sup -1} in groundwater within and hydraulically downgradient of the PRB. Chromium removal from groundwater occurs at the leading edge of the PRB and also within the aquifer immediately upgradient of the PRB. These regions also witness the greatest amount of secondary mineral formation due to steep geochemical gradients that result from the corrosion of zerovalent iron. X-ray absorption near-edge structure (XANES) spectroscopy indicated that chromium is predominantly in the trivalent oxidation state, confirming that reductive processes are responsible for Cr sequestration. XANES spectra and microscopy results suggest that Cr is, in part, associated with iron sulfide grains formed as a consequence of microbially mediated sulfate reduction in and around the PRB. Results of this study provide evidence that secondary iron-bearing mineral products may enhance the capacity of zerovalent iron systems to remediate Cr in groundwater, either through redox reactions at the mineral-water interface or by the release of Fe(II) to solution via mineral dissolution and/or metal corrosion.

  10. Combined use of a transformed red mud reactive barrier and electrokinetics for remediation of Cr/As contaminated soil.

    PubMed

    Cappai, G; De Gioannis, G; Muntoni, A; Spiga, D; Zijlstra, J J P

    2012-01-01

    A reactive barrier (RB) of transformed red mud (TRM), a by-product of the refinement of bauxite in alumina production, was placed adjacent to the anode of an electrokinetic (EK) system with the aim of enhancing removal of chromium or arsenic, added singly to a low permeability clayey soil, and favouring entrapment. The innovative study focused on evaluation of the synergic interaction between the EK system and the RB, and of the efficiency when compared to traditional EK remediation (control tests). The results obtained underlined the successful outcome of treatment of the Cr(VI)-contaminated soil. In presence of the TRM RB, 19.4% wt. of total Cr content was detected in the anolyte and 20.6% wt. trapped in the anodic RB after 6d, versus 6.6% wt. in the anolyte and 8.8% wt. in the soil adjacent to the anode following the control run without RB. On increasing duration of treatment up to 12d, 60.8% wt. of total initial Cr was found in the anolyte and 25.5% wt. trapped in the RB, versus 9.1% wt. and 5.3% wt., respectively, after a control run of the same duration. Finally, on increasing the mass of TRM in the RB, 60.6% wt. of initial Cr content was found to have accumulated in the RB, with Cr being completely absent from the anodic chamber. Conversely, combined treatment was much less effective on As contaminated soil, at least under the operative conditions applied. Low initial As concentration and interference with iron oxides in the soil were likely the reasons underlying low efficiency while attempting As decontamination.

  11. Risk mitigation by waste-based permeable reactive barriers for groundwater pollution control at e-waste recycling sites.

    PubMed

    Beiyuan, Jingzi; Tsang, Daniel C W; Yip, Alex C K; Zhang, Weihua; Ok, Yong Sik; Li, Xiang-Dong

    2017-02-01

    Permeable reactive barriers (PRBs) have proved to be a promising passive treatment to control groundwater contamination and associated human health risks. This study explored the potential use of low-cost adsorbents as PRBs media and assessed their longevity and risk mitigation against leaching of acidic rainfall through an e-waste recycling site, of which Cu, Zn, and Pb were the major contaminants. Batch adsorption experiments suggested a higher adsorption capacity of inorganic industrial by-products [acid mine drainage sludge (AMDS) and coal fly ash (CFA)] and carbonaceous recycled products [food waste compost (FWC) and wood-derived biochar] compared to natural inorganic minerals (limestone and apatite). Continuous leaching tests of sand columns with 10 wt% low-cost adsorbents were then conducted to mimic the field situation of acidic rainfall infiltration through e-waste-contaminated soils (collected from Qingyuan, China) by using synthetic precipitation leaching procedure (SPLP) solution. In general, Zn leached out first, followed by Cu, and finally delayed breakthrough of Pb. In the worst-case scenario (e.g., at initial concentrations equal to 50-fold of average SPLP result), the columns with limestone, apatite, AMDS, or biochar were effective for a relatively short period of about 20-40 pore volumes of leaching, after which Cu breakthrough caused non-cancer risk concern and later-stage Pb leaching considerably increased both non-cancer and lifetime cancer risk associated with portable use of contaminated water. In contrast, the columns with CFA or FWC successfully mitigated overall risks to an acceptable level for a prolonged period of 100-200 pore volumes. Therefore, with proper selection of low-cost adsorbents (or their mixture), waste-based PRBs is a technically feasible and economically viable solution to mitigate human health risk due to contaminated groundwater at e-waste recycling sites.

  12. Biogeochemical Reactions and Mineralogical Characteristics in an Iron Reactive Barrier at the Oak Ridge Y-12 Site

    NASA Astrophysics Data System (ADS)

    Gu, B.; Watson, D.; Phillips, D.

    2001-12-01

    A permeable iron reactive barrier was installed in late November, 1997 at the U.S. Department of Energy's Y-12 National Security Complex in Oak Ridge, Tennessee. The biogeochemical reactions and mineralogical and hydrological characteristics in the barrier were investigated over an extended field operation ( ~3 years). Results indicated that zero-valent iron (Fe0) reacts with a number of groundwater constituents such as bicarbonates, nitrate, and sulfate in addition to its effectiveness in removing contaminant metals or radionuclides such as uranium and technetium. Both nitrate and sulfate were reduced within or in the influence zone of the Fe0 with a low redox potential (i.e., low Eh). An increased anaerobic microbial population was also observed within and in the vicinity of the Fe0 barrier, and these microorganisms were at least partially responsible for the reduction of nitrate and sulfate in groundwater. Decreased concentrations of Ca2+ and bicarbonate in groundwater occurred as a result of the formation of minerals such as aragonite (CaCO3) and siderite (FeCO3), which coincided with the Fe0 corrosion and an increased groundwater pH. A suite of mineral precipitates was identified in the Fe0 barrier system, including amorphous iron oxyhydroxides, goethite, ferrous carbonates and sulfides, aragonite, and green rusts. These minerals were found to be responsible for the cementation and possibly clogging of Fe0 filings observed in a number of core samples from the barrier. Significant increases in cementation of the Fe0 occurred between two coring events conducted at ~1 year apart and appeared to correspond to the changes in an apparent decrease in hydraulic connectivity. The present study concludes that, while Fe0 may be used as an effective reactive medium for the retention or degradation of many redox-sensitive contaminants, its long-term reactivity and performance could be severely hindered by its reactions with other groundwater constituents; and groundwater

  13. Evaluation of a horizontal permeable reactive barrier for preventing upward diffusion of volatile organic compounds through the unsaturated zone.

    PubMed

    Mahmoodlu, Mojtaba G; Hassanizadeh, S Majid; Hartog, Niels; Raoof, Amir; van Genuchten, Martinus Th

    2015-11-01

    Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB.

  14. Cr(VI)-contaminated groundwater remediation with simulated permeable reactive barrier (PRB) filled with natural pyrite as reactive material: Environmental factors and effectiveness.

    PubMed

    Liu, Yuanyuan; Mou, Haiyan; Chen, Liqun; Mirza, Zakaria A; Liu, Li

    2015-11-15

    Permeable reactive barriers (PRBs) are efficient technologies for in situ remediation of contaminated groundwater, the effectiveness of which greatly depends on the reactive media filled. Natural pyrite is an iron sulfide material with a very low content of iron and sulfur, and a mining waste which is a potential material for Cr(VI) immobilization. In this study, we conducted a series of batch tests to research the effects of typical environmental factors on Cr(VI) removal and also simulated PRB filled with natural pyrite to investigate its effectiveness, in order to find a both environmentally and economically fine method for groundwater remediation. Batch tests showed that pH had the significant impact on Cr(VI) removal with an apparently higher efficiency under acidic conditions, and dissolved oxygen (DO) would inhibit Cr(VI) reduction; a relatively high initial Cr(VI) concentration would decrease the rate of Cr(VI) sorption; ionic strength and natural organic matter resulted in no significant effects on Cr(VI) removal. Column tests demonstrated that the simulated PRB with natural pyrite as the reactive media was considerably effective for removing Cr(VI) from groundwater, with a sorption capability of 0.6222 mg Cr per gram of natural pyrite at an initial Cr(VI) concentration of 10mg/L at pH 5.5 in an anoxic environment.

  15. Reactivation of the Shock-Tunnel Facility at Fort Cronkhite. Final report

    SciTech Connect

    Not Available

    1982-05-01

    This final report describes the results of work undertaken to reactivate the Shock Tunnel Facility at Battery Townsley, Fort Cronkhite, Marin County, California. The facility has been reactivated and can not be utilized for blast testing. The major emphasis will be testing of concepts pertaining to programs of interest to the Federal Emergency Management Agency (FEMA) and in particular to civil defense oriented research. However, a wide variety of testing requirements can be accommodated. For example, past programs at the facility have included: tests of debris from trees subjected to blast for Bell Telephone Laboratories; tests of the response of aluminum hull panels to blast loading and of the response of a model surface effects ship for the Naval Ship Research and Development center, and tests of the response of a radome prototype to blast loading conducted for ANCOM (the radome manufacturer). The Shock Tunnel Facility is located in a former coastal defense 16-inch gun emplacement constructed by the US Army beginning in 1938. It was converted in 1967 to serve as a facility for full-scale testing of the loading and response of structural elements and civil defense equipment. It remained in operation until November 1976 when Battery Townsley was turned over to the National Park Service. Work under the present purchase order consisted of the following major tasks: (I) cleanup and secure the facility, (II) reactivate the shock tunnel, and (III) design permanent facility improvements. (WHK)

  16. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier.

    PubMed

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-10

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.

  17. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

    PubMed Central

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-01

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results. PMID:28071762

  18. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

    NASA Astrophysics Data System (ADS)

    Wang, Yuping; Li, Yida; Wang, Dunyou

    2017-01-01

    A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.

  19. Remediation of groundwater contaminated with the lead-phenol binary system by granular dead anaerobic sludge-permeable reactive barrier.

    PubMed

    Faisal, Ayad A H; Abd Ali, Ziad T

    2016-12-28

    Computer solutions (COMSOL) Multiphysics 3.5a software was used for simulating the one-dimensional equilibrium transport of the lead-phenol binary system including the sorption process through saturated sandy soil as the aquifer and granular dead anaerobic sludge (GDAS) as the permeable reactive barrier. Fourier-transform infrared spectroscopy analysis proved that the carboxylic and alcohol groups are responsible for the bio-sorption of lead onto GDAS, while phosphines, aromatic and alkane are the functional groups responsible for the bio-sorption of phenol. Batch tests have been performed to characterize the equilibrium sorption properties of the GDAS and sandy soil in lead and/or phenol containing aqueous solutions. Numerical and experimental results proved that the barrier plays a potential role in the restriction of the contaminant plume migration and there is a linear relationship between longevity and thickness of the barrier. A good agreement between these results was recognized with root mean squared error not exceeding 0.04.

  20. Effectiveness of compacted soil liner as a gas barrier layer in the landfill final cover system.

    PubMed

    Moon, Seheum; Nam, Kyoungphile; Kim, Jae Young; Hwan, Shim Kyu; Chung, Moonkyung

    2008-01-01

    A compacted soil liner (CSL) has been widely used as a single barrier layer or a part of composite barrier layer in the landfill final cover system to prevent water infiltration into solid wastes for its acceptable hydraulic permeability. This study was conducted to test whether the CSL was also effective in prohibiting landfill gas emissions. For this purpose, three different compaction methods (i.e., reduced, standard, and modified Proctor methods) were used to prepare the soil specimens, with nitrogen as gas, and with water and heptane as liquid permeants. Measured gas permeability ranged from 2.03 x 10(-10) to 4.96 x 10(-9) cm(2), which was a magnitude of two or three orders greater than hydraulic permeability (9.60 x 10(-13) to 1.05 x 10(-11) cm(2)). The difference between gas and hydraulic permeabilities can be explained by gas slippage, which makes gas more permeable, and by soil-water interaction, which impedes water flow and then makes water less permeable. This explanation was also supported by the result that a liquid permeability measured with heptane as a non-polar liquid was similar to the intrinsic gas permeability. The data demonstrate that hydraulic requirement for the CSL is not enough to control the gas emissions from a landfill.

  1. Trichloroethylene removal from groundwater in flow-through columns simulating a permeable reactive barrier constructed with plant mulch.

    PubMed

    Shen, Hai; Wilson, John T

    2007-06-01

    Groundwater contaminated with TCE is commonly treated with a permeable reactive barrier (PRB) constructed with zero-valence iron. The cost of iron has driven a search for less costly alternatives, and composted plant mulch has been used as an alternative at several sites. A column study was conducted that simulated conditions in a PRB at Altus Air Force Base, Oklahoma. The reactive matrix was 50% (v/v) shredded tree mulch, 10% cotton gin trash, and 40% sand. The mean residence time of groundwater in the columns was 17 days. The estimated retardation factor for TCE was 12. TCE was supplied at concentrations near 20 microM. Over 793 days of operation, concentrations of TCE in the column effluents varied from 0.1% to 2% of the column influents. Concentrations of cis-DCE, vinyl chloride, ethylene, ethane, and acetylene could account for 1% of the TCE that was removed; however, up to 56% of 13C added as [1,2-13C] TCE in the column influents was recovered as 13C in carbon dioxide. After 383 and 793 d of operation, approximately one-half of the TCE removal was associated with abiotic reactions with FeS that accumulated in the reactive matrix.

  2. Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes - Final Report

    SciTech Connect

    Schwartz, F.W.

    2000-10-01

    This study provides a detailed process-level understanding of the oxidative destruction of the organic contaminant emphasizing on reaction pathways and kinetics. A remarkable rise in the MnO{sup {minus}} consumption rate with TCA and PCE mixtures proves that the phase transfer catalysts have the ability to increase oxidation rate of DNAPLs either in pure phase or mixtures and that there is significant potential for testing the catalyzed scheme under field conditions. Secondly, as an attempt to enhance the oxidation of DNAPL, we are trying to exploit cosolvency effects, utilizing various alcohol-water mixtures to increase DNAPL solubilization. Preliminary results of cosolvency experiments indicate the enhancement in the transfer of nonaqueous phase TCE to TBA-water solution and the rate of TCE degradation in aqueous phase.

  3. Biogeochemical mineralogical, and hydrological characteristics of an iron reactive barrier used for treatment of uranium and other contaminants

    SciTech Connect

    Gu, Baohua; Watson, David B; Phillips, Debra H.; Liang, Liyuan

    2002-05-01

    A permeable iron reactive barrier was installed in late November, 1997 at the U.S. Department of Energy's Y-12 National Security Complex in Oak Ridge, Tennessee. The overall goal of this research was to determine the effectiveness of the use of zero-valent iron (Fe{sup 0}) to retain or remove uranium and other contaminants such as technetium and nitrate in groundwater. The long-term performance issues were investigated by studying the biogeochemical interactions between Fe{sup 0} and groundwater constituents and the mineralogical and biological characteristics over an extended field operation. Results from nearly 3 years of monitoring indicated that the Fe{sup 0} barrier was performing effectively in removing contaminant radionuclides such as uranium and technetium. In addition, a number of groundwater constituents such as bicarbonates, nitrate, and sulfate were found to react with the Fe{sup 0}. Both nitrate and sulfate were reduced within or in the influence zone of the Fe{sup 0} with a low redox potential (i.e., low Eh). An increased anaerobic microbial population was also observed within and in the vicinity of the Fe{sup 0} barrier, and these microorganisms were at least partially responsible for the reduction of nitrate and sulfate in groundwater. Decreased concentrations of Ca{sup 2+} and bicarbonate in groundwater occurred as a result of the formation of minerals such as aragonite (CaCO{sub 3}) and siderite (FeCO{sub 3}), which coincided with the Fe{sup 0} corrosion and an increased groundwater pH. A suite of mineral precipitates was identified in the Fe{sup 0} barrier system, including amorphous iron oxyhydroxides, goethite, ferrous carbonates and sulfides, aragonite, and green rusts. These minerals were found to be responsible for the cementation and possibly clogging of Fe{sup 0} filings observed in a number of core samples from the barrier. Significant increases in cementation of the Fe{sup 0} occurred between two coring events conducted at {approx}1

  4. Regulatory Guidance for Permeable Reactive Barriers Designed to Remediate Chlorinated Solvents

    DTIC Science & Technology

    1999-12-01

    federal Hazardous Waste Regulations prior to disposal. The classification of the soil will determine the disposal method. State-specific requirements...installation. Any contaminated soil should be classified in accordance with state and federal Hazardous Waste Regulations prior to disposal. The classification...classified and disposed of in accordance with state and federal Hazardous Waste Regulations . Another mechanism to reestablish the reactivity of the

  5. Cement kiln dust (CKD)-filter sand permeable reactive barrier for the removal of Cu(II) and Zn(II) from simulated acidic groundwater.

    PubMed

    Sulaymon, Abbas H; Faisal, Ayad A H; Khaliefa, Qusey M

    2015-10-30

    The hydraulic conductivity and breakthrough curves of copper and zinc contaminants were measured in a set of continuous column experiments for 99 days using cement kiln dust (CKD)-filter sand as the permeable reactive barrier. The results of these experiments proved that the weight ratios of the cement kiln dust-filter sand (10:90 and 20:80) are adequate in preventing the loss of reactivity and hydraulic conductivity and, in turn, avoiding reduction in the groundwater flow. These results reveal a decrease in the hydraulic conductivity, which can be attributed to an accumulation of most of the quantity of the contaminant masses in the first sections of the column bed. Breakthrough curves for the description of the temporal contaminant transport within the barrier were found to be more representative by the Belter-Cussler-Hu and Yan models based on the coefficient of determination and Nash-Sutcliffe efficiency. The longevity of the barrier was simulated for the field scale, based on the laboratory column tests and the values verified that cement kiln dust can be effectively used in the future, as the reactive material in permeable reactive barrier technology. These results signify that the longevity of the barrier is directly proportional to its thickness and inversely to the percentage of the CKD used.

  6. Organic substrates as electron donors in permeable reactive barriers for removal of heavy metals from acid mine drainage.

    PubMed

    Kijjanapanich, P; Pakdeerattanamint, K; Lens, P N L; Annachhatre, A P

    2012-12-01

    This research was conducted to select suitable natural organic substrates as potential carbon sources for use as electron donors for biological sulphate reduction in a permeable reactive barrier (PRB). A number of organic substrates were assessed through batch and continuous column experiments under anaerobic conditions with acid mine drainage (AMD) obtained from an abandoned lignite coal mine. To keep the heavy metal concentration at a constant level, the AMD was supplemented with heavy metals whenever necessary. Under anaerobic conditions, sulphate-reducing bacteria (SRB) converted sulphate into sulphide using the organic substrates as electron donors. The sulphide that was generated precipitated heavy metals as metal sulphides. Organic substrates, which yielded the highest sulphate reduction in batch tests, were selected for continuous column experiments which lasted over 200 days. A mixture of pig-farm wastewater treatment sludge, rice husk and coconut husk chips yielded the best heavy metal (Fe, Cu, Zn and Mn) removal efficiencies of over 90%.

  7. Highly organic natural media as permeable reactive barriers: TCE partitioning and anaerobic degradation profile in eucalyptus mulch and compost.

    PubMed

    Öztürk, Zuhal; Tansel, Berrin; Katsenovich, Yelena; Sukop, Michael; Laha, Shonali

    2012-10-01

    Batch and column experiments were conducted with eucalyptus mulch and commercial compost to evaluate suitability of highly organic natural media to support anaerobic decomposition of trichloroethylene (TCE) in groundwater. Experimental data for TCE and its dechlorination byproducts were analyzed with Hydrus-1D model to estimate the partitioning and kinetic parameters for the sequential dechlorination reactions during TCE decomposition. The highly organic natural media allowed development of a bioactive zone capable of decomposing TCE under anaerobic conditions. The first order TCE biodecomposition reaction rates were 0.23 and 1.2d(-1) in eucalyptus mulch and compost media, respectively. The retardation factors in the eucalyptus mulch and compost columns for TCE were 35 and 301, respectively. The results showed that natural organic soil amendments can effectively support the anaerobic bioactive zone for remediation of TCE contaminated groundwater. The natural organic media are effective environmentally sustainable materials for use in permeable reactive barriers.

  8. Fifteen-year assessment of a permeable reactive barrier for treatment of chromate and trichloroethylene in groundwater.

    PubMed

    Wilkin, Richard T; Acree, Steven D; Ross, Randall R; Puls, Robert W; Lee, Tony R; Woods, Leilani L

    2014-01-15

    The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium source zone, reactive and hydraulic longevity of the PRB has outlived the mobile chromate plume. Chromium concentrations exceeding 3 μg/L have not been detected in regions located hydraulically down-gradient of the PRB. Trichloroethylene treatment has also been effective, although non-constant influent concentrations of trichloroethylene have at times resulted in incomplete dechlorination. Daughter products: cis-1,2-dichloroethylene, vinyl chloride, ethene, and ethane have been observed within and down-gradient of the PRB at levels <10% of the influent trichloroethylene. Analysis of potentiometric surfaces up-gradient and across the PRB suggests that the PRB may currently represent a zone of reduced hydraulic conductivity; however, measurements of the in-situ hydraulic conductivity provide values in excess of 200 m/d in some intervals and indicate no discernible loss of bulk hydraulic conductivity within the PRB. The results presented here are particularly significant because they provide the longest available record of performance of a PRB. The longevity of the Elizabeth City PRB is principally the result of favorable groundwater geochemistry and hydrologic properties of the site.

  9. Measurement of reactive species generated by dielectric barrier discharge in direct contact with water in different atmospheres

    NASA Astrophysics Data System (ADS)

    Kovačević, Vesna V.; Dojčinović, Biljana P.; Jović, Milica; Roglić, Goran M.; Obradović, Bratislav M.; Kuraica, Milorad M.

    2017-04-01

    The formation of hydroxyl radical and long-living chemical species (H2O2, O3, \\text{NO}3- and \\text{NO}2- ) generated in the liquid phase of a water falling film dielectric barrier discharge in dependence on the gas atmosphere (air, nitrogen, oxygen, argon and helium) was studied. The chemical molecular probe dimethyl sulfoxide was employed for quantification of ˙OH, and the influence of hydroxyl radical scavenging on formation of reactive oxygen and nitrogen species was investigated. In addition to liquid analysis, plasma diagnostics was applied to indicate possible reaction pathways of plasma–liquid interaction. The highest ˙OH production rate of 1.19  ×  10‑5 mol l‑1 s‑1 was found when water was treated in oxygen, with a yield of 2.75  ×  10‑2 molecules of ˙OH per 100 eV. Formation of hydrogen peroxide in air, nitrogen and argon discharges is determined by recombination reaction of hydroxyl radicals, reaching the highest yield of about 0.7 g kWh‑1 when distilled water was treated in argon discharge. Ozone formation was dominant in oxygen and air discharges. Strong acidification along with formation of reactive nitrogen species was detected in water treated in air and nitrogen discharges.

  10. Remediation of arsenic-contaminated groundwater using media-injected permeable reactive barriers with a modified montmorillonite: sand tank studies.

    PubMed

    Luo, Ximing; Liu, Haifei; Huang, Guoxin; Li, Ye; Zhao, Yan; Li, Xu

    2016-01-01

    A modified montmorillonite (MMT) was prepared using an acid activation-sodium activation-iron oxide coating method to improve the adsorption capacities of natural MMTs. For MMT, its interlamellar distance increased from 12.29 to 13.36 Å, and goethite (α-FeOOH) was intercalated into its clay layers. Two novel media-injected permeable reactive barrier (MI-PRB) configurations were proposed for removing arsenic from groundwater. Sand tank experiments were conducted to investigate the performance of the two MI-PRBs: Tank A was filled with quartz sand. Tank B was packed with quartz sand and zero-valent iron (ZVI) in series, and the MMT slurry was respectively injected into them to form reactive zones. The results showed that for tank A, total arsenic (TA) removal of 98.57% was attained within the first 60 mm and subsequently descended slowly to 88.84% at the outlet. For tank B, a similar spatial variation trend was observed in the quartz sand layer, and subsequently, TA removal increased to ≥99.80% in the ZVI layer. TA removal by MMT mainly depended on both surface adsorption and electrostatic adhesion. TA removal by ZVI mainly relied on coagulation/precipitation and adsorption during the iron corrosion. The two MI-PRBs are feasible alternatives for in situ remediation of groundwater with elevated As levels.

  11. Performance of a Zerovalent Iron Reactive Barrier for the Treatment of Arsenic in Groundwater: Part 2. Geochemical Modeling and Solid Phase Studies

    EPA Science Inventory

    Arsenic uptake processes were evaluated in a zerovalent iron reactive barrier installed at a lead smelting facility using geochemical modeling, solid-phase analysis, and X-ray absorption spectroscopy techniques. Aqueous speciation of arsenic plays a key role in directing arsenic...

  12. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED ON DESIGN, CONTAMINANT TREATMENT, LONGEVITY, PERFORMANCE MONITORING AND COST-AN OVERVIEW

    EPA Science Inventory

    This presentation will provide an overview of permeable reactive barrier performance for field sites in the U.S. evaluated over the last 10 years by the U.S. Environmental Protection Agency's Office of Research and Development (EPA-ORD) in collaboration with other U.S. federal ag...

  13. ENVIRONMENTAL RESEARCH BRIEF: LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS USING ZERO-VALENT IRON: AN EVALUATION AT TWO SITES

    EPA Science Inventory

    Geochemical and microbiological factors that control long-term performance of subsurface permeable reactive barriers were evaluated at the Elizabeth City, NC and the Denver Federal Center, CO sites. These groundwater treatment systems use zero-valent iron filings to intercept an...

  14. REMOVAL OF ADDED NITRATE IN THE SINGLE, BINARY, AND TERNARY SYSTEMS OF COTTON BURR COMPOST, ZEROVALENT IRON, AND SEDIMENT: IMPLICATIONS FOR GROUNDWATER NITRATE REMEDIATION USING PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe0) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and ...

  15. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED ON DESIGN, CONTAMINANT TREATMENT, LONGEVITY, PERFORMANCE MONITORING AND COST - AN OVERVIEW

    EPA Science Inventory

    An overview of permeable reactive barrier (PRB) performance for field sites in the U.S. was evaluated over the last 10 years by the U.S. Environmental Protection Agencys Office of Research and Development (EPA-ORD) in collaboration with other U.S. federal agencies, consulting co...

  16. INFLUENCE OF GROUNDWATER GEOCHEMISTRY ON THE LONG-TERM PERFORMANCE OF IN-SITU PERMEABLE REACTIVE BARRIERS CONTAINING ZERO-VALENT IRON

    EPA Science Inventory

    Reactive barriers that couple subsurface fluid flow with a passive chemical treatment zone are emerging, cost effective approaches for in-situ remediation of contaminated groundwater. Factors such as the build-up of surface precipitates, bio-fouling, and changes in subsurface tr...

  17. THE APPLICATION OF IN SITU PERMEABLE REACTIVE (ZERO-VALENT IRON) BARRIER TECHNOLOGY FOR THE REMEDIATION OF CHROMATE-CONTAMINATED GROUNDWATER: A FIELD TEST

    EPA Science Inventory

    A small-scale field test was initiated in September 1994 to evaluate the in situ remediation of groundwater contaminated with chromate using a permeable reactive barrier composed of a mixture of zero-valent Fe, sand and aquifer sediment. The site used was an old chrome-plating f...

  18. CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 1 PERFORMANCE EVALUATIONS AT TWO SITES

    EPA Science Inventory

    The purpose of this document is to provide detailed performance monitoring data on full-scale Permeable Reactive Barriers (PRBs) installed to treat contaminated ground water at two different sites. This report will fill a need for a readily available source of information for si...

  19. Experimental Design for One Dimensional Electrolytic Reactive Barrier for Remediation of Munition Constituent in Groundwater

    PubMed Central

    Gent, David B.; Wani, Altaf; Alshawabkeh, Akram N.

    2012-01-01

    A combination of direct electrochemical reduction and in-situ alkaline hydrolysis has been proposed to decompose energetic contaminants such as 1,3,5-Trinitroperhydro- 1,3,5-triazine and 2,4,6-Trinitrotoluene (RDX) in deep aquifers. This process utilizes natural groundwater convection to carry hydroxide produced by an upstream cathode to remove the contaminant at the cathode as well as in the pore water downstream as it migrates toward the anode. Laboratory evaluation incorporated fundamental principles of column design coupled with reactive contaminant modeling including electrokinetics transport. Batch and horizontal sand-packed column experiments included both alkaline hydrolysis and electrochemical treatment to determine RDX decomposition reaction rate coefficients. The sand packed columns simulated flow through a contaminated aquifer with a seepage velocity of 30.5 cm/day. Techniques to monitor and record the transient electric potential, hydroxide transport and contaminant concentration within the column were developed. The average reaction rate coefficients for both the alkaline batch (0.0487 hr−1) and sand column (0.0466 hr−1) experiments estimated the distance between the cathode and anode required to decompose 0.5 mg/L RDX to the USEPA drinking water lifetime Health Advisory level of 0.002 mg/L to be 145 and 152 cm. PMID:23472044

  20. Influence of hydrogeochemical processes on zero-valent iron reactive barrier performance: A field investigation

    NASA Astrophysics Data System (ADS)

    Liang, Liyuan; Moline, Gerilynn R.; Kamolpornwijit, Wiwat; West, Olivia R.

    2005-08-01

    Geochemical and mineralogical changes were evaluated at a field Fe 0-PRB at the Oak Ridge Y-12 site concerning operation performance during the treatment of U in high NO 3- groundwater. In the 5-year study period, the Fe 0 remained reactive as shown in pore-water monitoring data, where increases in pH and the removal of certain ionic species persisted. However, coring revealed varying degrees of cementation. After 3.8-year treatment, porosity reduction of up to 41.7% was obtained from mineralogical analysis on core samples collected at the upgradient gravel-Fe 0 interface. Elsewhere, Fe 0 filings were loose with some cementation. Fe 0 corrosion and pore volume reduction at this site are more severe due to the presence of NO 3- at a high level. Tracer tests indicate that hydraulic performance deteriorated: the flow distribution was heterogeneous and under the influence of interfacial cementation a large portion of water was diverted around the Fe 0 and transported outside the PRB. Based on the equilibrium reductions of NO 3- and SO 42- by Fe 0 and mineral precipitation, geochemical modeling predicted a maximum of 49% porosity loss for 5 years of operation. Additionally, modeling showed a spatial distribution of mineral precipitate volumes, with the maximum advancing from the interface toward downgradient with time. This study suggests that water quality monitoring, coupled with hydraulic monitoring and geochemical modeling, can provide a low-cost method for assessing PRB performance.

  1. Influence of hydrogeochemical processes on zero-valent iron reactive barrier performance: a field investigation.

    PubMed

    Liang, Liyuan; Moline, Gerilynn R; Kamolpornwijit, Wiwat; West, Olivia R

    2005-08-01

    Geochemical and mineralogical changes were evaluated at a field Fe0-PRB at the Oak Ridge Y-12 site concerning operation performance during the treatment of U in high NO3- groundwater. In the 5-year study period, the Fe0 remained reactive as shown in pore-water monitoring data, where increases in pH and the removal of certain ionic species persisted. However, coring revealed varying degrees of cementation. After 3.8-year treatment, porosity reduction of up to 41.7% was obtained from mineralogical analysis on core samples collected at the upgradient gravel-Fe0 interface. Elsewhere, Fe0 filings were loose with some cementation. Fe0 corrosion and pore volume reduction at this site are more severe due to the presence of NO3- at a high level. Tracer tests indicate that hydraulic performance deteriorated: the flow distribution was heterogeneous and under the influence of interfacial cementation a large portion of water was diverted around the Fe0 and transported outside the PRB. Based on the equilibrium reductions of NO3- and SO4(2-) by Fe0 and mineral precipitation, geochemical modeling predicted a maximum of 49% porosity loss for 5 years of operation. Additionally, modeling showed a spatial distribution of mineral precipitate volumes, with the maximum advancing from the interface toward downgradient with time. This study suggests that water quality monitoring, coupled with hydraulic monitoring and geochemical modeling, can provide a low-cost method for assessing PRB performance.

  2. Influence of hydrogeochemical processes on zero-valent iron reactive barrier performance: a field investigation.

    PubMed

    Liang, Liyuan; Moline, Gerilynn R; Kamolpornwijit, Wiwat; West, Olivia R

    2005-11-01

    Geochemical and mineralogical changes were evaluated at a field Fe0-PRB at the Oak Ridge Y-12 site concerning operation performance during the treatment of U in high NO3- groundwater. In the 5-yr study period, the Fe0 remained reactive as shown in pore water monitoring data, where increases in pH and the removal of certain ionic species persisted. However, coring revealed varying degrees of cementation. After 3.8-yr treatment, porosity reduction of up to 41.7% was obtained from mineralogical analysis on core samples collected at the upgradient gravel-Fe0 interface. Elsewhere, Fe0 filings were loose with some cementation. Fe0 corrosion and pore volume reduction at this site are more severe due to the presence of NO3- at a high level. Tracer tests indicate that hydraulic performance deteriorated: the flow distribution was heterogeneous and under the influence of interfacial cementation a large portion of water was diverted around the Fe0 and transported outside the PRB. Based on the equilibrium reductions of NO3- and SO4(2-) by Fe0 and mineral precipitation, geochemical modeling predicted a maximum of 49% porosity loss for 5 yr of operation. Additionally, modeling showed a spatial distribution of mineral precipitate volumes, with the maximum advancing from the interface toward downgradient with time. This study suggests that water quality monitoring, coupled with hydraulic monitoring and geochemical modeling, can provide a low-cost method for assessing PRB performance.

  3. Forecasting and Analyzing Needs and Barriers in Kentucky Vocational Education. Final Report.

    ERIC Educational Resources Information Center

    McClellan, L. Dean; Newton, Robert E.

    Objectives of a Kentucky project were to analyze existing needs and barriers and potential needs and barriers regarding (1) new and emerging occupations, (2) elimination of discrimination, (3) vocational staff development, and (4) funding vocational education. A statewide planning committee assisted in development of the method and instruments. A…

  4. Applying Reactive Barrier Technology to Enhance Microbially-mediated Denitrification during Managed Aquifer Recharge

    NASA Astrophysics Data System (ADS)

    Beganskas, S.; Weir, W. B.; Harmon, R. E.; Gorski, G.; Fisher, A. T.; Saltikov, C.; Young, K. S.; Runneals, D.; Teo, E. K.; Stoneburner, B.; Hernandez, J.

    2015-12-01

    We are running field experiments to observe and quantify microbially-mediated water quality improvement via denitrification during infiltration in the shallow subsurface. Nitrate is a pervasive groundwater contaminant, and nitrate removal through denitrification can occur during infiltration in natural and anthropogenic systems, including during managed aquifer recharge (MAR). The rate of denitrification can vary depending on factors such as infiltration rate; previous work suggests that denitrification rates can increase monotonically with infiltration rates until reaching a critical threshold. We are performing controlled field tests of variables that affect denitrification rate, including sampling to link water chemistry changes to microbial ecology and activity. This study explores how microbial activity and denitrification rates respond to different infiltration rates and the presence or absence of a reactive material (wood chips, a carbon source). We are conducting four two-week-long tests, each under different conditions. For each test, we measure bulk infiltration rate (the sum of lateral and vertical infiltration), vertical infiltration rate using heat as a tracer, and water level. We collect surface and subsurface water samples daily, and we collect soil samples at the start and end of each test. For each water sample, we are measuring NO3-, NO2-, NH3, DOC, and N and O isotopes in nitrate. Soil samples will be tested for grain size, total C/N, and the presence of microbiological genes associated with denitrification. These results will expand our knowledge of the conditions under which denitrification occurs by implicating specific microorganisms and physical infiltration parameters. Our design has the potential for additional experimentation with variables that impact water chemistry during infiltration. This study has broad applications for designing MAR systems that effectively improve water supply and water quality.

  5. Investigating the potential for long-term permeable reactive barrier (PRB) monitoring from the electrical signatures associated with the reduction in reactive iron performance

    SciTech Connect

    Slater, Lee D.; Korte, N.; Baker, J.

    2005-12-14

    The objective of this work was to conduct laboratory and field experiments to determine the sensitivity of low frequency electrical measurements (resistivity and induced polarization) to the processes of corrosion and precipitation that are believed to limit permeable reactive barrier (PRB) performance. The research was divided into four sets of experiments that were each written up and submitted to a peer-reviewed journal: [1] A laboratory experiment to define the controls of aqueous chemistry (electrolyte activity; pH; valence) and total zero valent iron (Fe0) available surface area on the electrical properties of Fe0 columns. [2] A laboratory experiment to determine the impact of corrosion and precipitation on the electrical response of synthetic Fe0 columns as a result of geochemical reactions with NaSO4 and NaCO3 electrolytes. [3] Laboratory experiments on a sequence of cores retrieved from the Kansas City PRB to determine the magnitude of electrical and geochemical changes within a field active PRB after eight years of operation [4] Field-scale cross borehole resistivity and induced polarization monitoring of the Kansas City PRB to evaluate the potential of electrical imaging as a technology for non-invasive, long-term monitoring of indicators of reduced PRB performance This report first summarizes the findings of the four major experiments conducted under this research. The reader is referred to the four papers in Appendices 1-4 for a full description of each experiment, including motivation and significance, technical details, findings and implications. The deliverables of the project, including the publications, conference papers and new collaborative arrangements that have resulted are then described. Appendices 5-6 contain two technical reports written by co-PI Korte describing (1) supporting geochemical measurements, and (2) the coring procedure, conducted at the Kansas City PRB as part of this project.

  6. Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland

    NASA Astrophysics Data System (ADS)

    Doherty, R.; Phillips, D. H.; McGeough, K. L.; Walsh, K. P.; Kalin, R. M.

    2006-05-01

    A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (<1 μm) cubic highly crystalline precipitates on the flyash, although this new crystalline zeolite growth did not occur rapidly enough to enable productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.

  7. Design of a multifunctional permeable reactive barrier for the treatment of landfill leachate contamination: laboratory column evaluation.

    PubMed

    Van Nooten, Thomas; Diels, Ludo; Bastiaens, Leen

    2008-12-01

    This study describes a laboratory-scale multifunctional permeable reactive barrier (multibarrier) for the removal of ammonium (NH4+: 313 +/- 51 mg N L(-1)), adsorbable organic halogens (AOX: 0.71 +/- 0.25 mg Cl L(-1)), chemical oxygen demand (COD: 389 +/- 36 mg L(-1)), and toxicity from leachate originating from a 40-year-old Belgian landfill. The complexity of the contamination required a sequential setup combining different reactive materials and removal processes. All target contaminants could be removed to levels below the regulatory discharge limits. Ammonium was efficiently removed in a first microbial nitrification compartment, which was equipped with diffusive oxygen emitters to ensure a sufficient oxygen supply. Ammonium was mainly oxidized to nitrite and to a lesser extent to nitrate, with an average mass recovery of 96%. Remaining ammonium concentrations could be further removed by ion exchange in a second compartment filled with clinoptilolite, exhibiting a total ammonium removal capacity of 46.7 mg N per g of clinoptilolite. Athird microbial denitrification compartment fed with sodium butyrate as a carbon source, was used to remove nitrate and nitrite formed in the first compartment. Maximum nitrification and denitrification rates at 12 degrees C indicated that hydraulic retention times of approximately 62 h and approximately 32 h were required in the columns to remove 400 mg N L(-1) by nitrification and denitrification, respectively. Leachate toxicity decreased to background levelstogetherwiththe removal of ammonium and its oxidation products. AOX and COD were efficiently removed by sorption in an additional compartment filled with granular activated carbon.

  8. Evaluation of removal of orthophosphate and ammonia from rainfall runoff using aboveground permeable reactive barrier composed of limestone and zeolite.

    PubMed

    Srinivasan, Rajani; Hoffman, Dennis W; Wolfe, June E; Prcin, Lisa J

    2008-10-01

    This paper evaluates the design and performance of an Aboveground Permeable Reactive Barrier (APRB) system made of polyethylene mesh bags (FlowBags) containing crushed limestone and zeolite for adsorption of orthophosphate-P (PO4-P) and ammonia-N (NH4-N) from rainfall runoff. Laboratory batch experiments, simulated runoff experiments and actual APRB implementations were performed to evaluate the performance of the APRB. Batch experiments were performed to determine adsorption efficiency of crushed zeolite and limestone as reactive materials in APRB for removal of dissolved ammonium nitrogen and orthophosphate phosphorus from aqueous solutions under controlled laboratory conditions. Adsorption efficiencies of zeolite and limestone were tested individually and in combination. Results show adsorption efficiency increases when the materials are used in combination. Effects of particle size, contact time, pH, and temperature were studied. Major emphasis was given to short contact times because the contact of rainfall runoff water under field conditions with APRBs would be approximately 5 minutes. Maximum removal of approximately 70% PO4-P and NH4-N was seen at 45 degrees C in 5 minutes within a pH range of 8-11. Optimum adsorbent concentration was 0.3 ppm with 20 g limestone and 10 g of zeolites. Simulated field experiments and actual APRB field installations showed variable results. Results from field evaluations of APRB showed mixed results from very high to negligible removal of orthophosphate-P and ammonia-N at different monitoring sites and storm events. Such variability may be due to the design of the bags, other biotic and abiotic factors and various physical factors, which are absent in the laboratory conditions. Some APRB design problems were also observed under field conditions and solutions are suggested. Overall results indicate that APRBs composed of combinations of crushed zeolite and limestone will offer an effective low maintenance and green alternative

  9. Enhancing the Attenuation of Acid-Mine Drainage at Davis Mine, Rowe, Massachusetts via Installation of a Permeable Reactive Barrier.

    NASA Astrophysics Data System (ADS)

    Gillmor, A. M.; Yuretich, R. F.

    2008-12-01

    Acid Mine Drainage affects thousands of streams in the United States, sustaining the need for low-cost passive treatment options. Davis Mine, a 100 years-abandoned FeS2 mine in Western Massachusetts, is representative of the types of mines best suited for passive treatments; fairly remote, abandoned, and discharging moderately affected water (pH <3, Fe >100mg/L, SO42- >500mg/L) and is a good candidate for a 'starting point' of low-cost, low environmental impact remediation. We here report the shifts in pH, SO42-, and Fe following placement of reactive fill (50% CaMg(CO3)2, 25% cow manure, 25% seaweed compost) in a permeable reactive barrier placed below ground mid-way along the acidic effluent's path. Yearlong monitoring of water from 1 multi-level well (with ports in the shallow groundwater, middle groundwater, and bedrock) placed within the tailings pile over a previous year (2003-2004) showed for the three levels, respectively; pH 3.16, 4.24, and 4.04, Fe average concentrations of 4.5 mg/L, 6.5 mg/L, and 3.2 mg/L, and SO42- average concentrations of 235mg/L, 330mg/L, and 292 mg/L. One year (2007-2008) after placement of remediation mix, the three levels now average respectively; pH 4.16, 4.60, and 4.53, Fe concentrations of 0.7 mg/L, 4.8 mg/L, and 1.4 mg/L, and SO42- concentrations of 217 mg/L, 294 mg/L, and 266 mg/L. The most noticeable improvement in pH is seen in the shallow groundwater, consistent with its proximity to the reactive fill depth. Although complex microbial communities have been characterized at the site, uncertainty remains as to whether they are active in this case, and it is possible that these results may be explained solely by neutralization reactions. Results of this study indicate a good likelihood that this low environmental impact remediation could be effective.

  10. Using dissolved gas analysis to investigate the performance of an organic carbon permeable reactive barrier for the treatment of mine drainage

    USGS Publications Warehouse

    Williams, R.L.; Mayer, K.U.; Amos, R.T.; Blowes, D.W.; Ptacek, C.J.; Bain, J.G.

    2007-01-01

    The strongly reducing nature of permeable reactive barrier (PRB) treatment materials can lead to gas production, potentially resulting in the formation of gas bubbles and ebullition. Degassing in organic C based PRB systems due to the production of gases (primarily CO2 and CH4) is investigated using the depletion of naturally occurring non-reactive gases Ar and N2, to identify, confirm, and quantify chemical and physical processes. Sampling and analysis of dissolved gases were performed at the Nickel Rim Mine Organic Carbon PRB, which was designed for the treatment of groundwater contaminated by low quality mine drainage characterized by slightly acidic pH, and elevated Fe(II) and SO4 concentrations. A simple 4-gas degassing model was used to analyze the dissolved gas data, and the results indicate that SO4 reduction is by far the dominant process of organic C consumption within the barrier. The data provided additional information to delineate rates of microbially mediated SO4 reduction and confirm the presence of slow and fast flow zones within the barrier. Degassing was incorporated into multicomponent reactive transport simulations for the barrier and the simulations were successful in reproducing observed dissolved gas trends.

  11. Biological permeable reactive barriers coupled with electrokinetic soil flushing for the treatment of diesel-polluted clay soil.

    PubMed

    Mena, Esperanza; Ruiz, Clara; Villaseñor, José; Rodrigo, Manuel A; Cañizares, Pablo

    2015-01-01

    Removal of diesel from spiked kaolin has been studied in the laboratory using coupled electrokinetic soil flushing (EKSF) and bioremediation through an innovative biological permeable reactive barriers (Bio-PRBs) positioned between electrode wells. The results show that this technology is efficient in the removal of pollutants and allows the soil to maintain the appropriate conditions for microorganism growth in terms of pH, temperature, and nutrients. At the same time, EKSF was demonstrated to be a very interesting technology for transporting pollutants, microorganisms and nutrients, although results indicate that careful management is necessary to avoid the depletion of nutrients, which are effectively transported by electro-migration. After two weeks of operation, 30% of pollutants are removed and energy consumption is under 70 kWh m(-3). Main fluxes (electroosmosis and evaporation) and changes in the most relevant parameters (nutrients, diesel, microorganisms, surfactants, moisture conductivity and pH) during treatment and in a complete post-study analysis are studied to give a comprehensive description of the most relevant processes occurring in the soil (pollutant transport and biodegradation).

  12. Comparison of permeable reactive barrier, funnel and gate, nonpumped wells, and low-capacity wells for groundwater remediation.

    PubMed

    Hudak, Paul F

    2014-01-01

    This modeling study compared the performance of a no-action and four active groundwater remediation alternatives: a permeable reactive barrier, a funnel and gate, nonpumped wells with filter media, and a low-capacity extraction and injection well. The simulated aquifer had an average seepage velocity of 0.04 m d(-1), and the initial contaminant plume was 58 m long and 13 m wide. For each active alternative, mass transport modeling identified the smallest structure necessary to contain and remove the contaminant plume. Although the no-action alternative did not contain the plume, each active alternative did contain and remove the plume, but with significantly different installation and operation requirements. Low-capacity pumping wells required the least infrastructure, with one extraction well and one injection well each discharging only 1.7 m(3) d(-1). The amount of time necessary to remove the contaminant plume was similar among active alternatives, except for the funnel and gate, which required much more time. Results of this study suggest that, for a modest seepage velocity and relatively narrow contaminant plume, low-capacity wells may be an effective alternative for groundwater remediation.

  13. Laboratory column study for evaluating a multimedia permeable reactive barrier for the remediation of ammonium contaminated groundwater.

    PubMed

    Kong, Xiangke; Bi, Erping; Liu, Fei; Huang, Guoxin; Ma, Jianfei

    2015-01-01

    In order to remediate ammonium contaminated groundwater, an innovative multimedia permeable reactive barrier (M-PRB) was proposed, which consisted of sequential columns combining oxygen releasing compound (ORC), zeolite, spongy iron and pine bark in the laboratory scale. Results showed that both ammonium and nitrate could be reduced to levels below the regulatory discharge limits through ion exchange and microbial degradation (nitrification and denitrification) in different compartments of the M-PRB system. The concentration of dissolved oxygen (DO) increased from 2 to above 20 mg/L after the simulated groundwater flowed through the oxygen releasing column packed with ORC, demonstrating that ORC could supply sufficient oxygen for subsequent microbial nitrification. Ammonium was efficiently removed from about 10 to below 0.5 mg N/L in the aerobic reaction column which was filled with biological zeolite. After 54 operating days, more than 70% ammonium could be removed by microbial nitrification in the aerobic reaction column, indicating that the combined use of ion exchange and nitrification by biological zeolite could ensure high and sustainable ammonium removal efficiency. To avoid the second pollution of nitrate produced by the former nitrification, spongy iron and pine bark were used to remove oxygen and supply organic carbon for heterotrophic denitrification in the oxygen removal column and anaerobic reaction column separately. The concentration of nitrate decreased from 14 to below 5 mg N/L through spongy iron-based chemical reduction and microbial denitrification.

  14. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    NASA Astrophysics Data System (ADS)

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-10-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR + PRB showed the lowest leaching value for each HM in the S2 and S3 regions.

  15. Column test-based optimization of the permeable reactive barrier (PRB) technique for remediating groundwater contaminated by landfill leachates.

    PubMed

    Zhou, Dan; Li, Yan; Zhang, Yinbo; Zhang, Chang; Li, Xiongfei; Chen, Zhiliang; Huang, Junyi; Li, Xia; Flores, Giancarlo; Kamon, Masashi

    2014-11-01

    We investigated the optimum composition of permeable reactive barrier (PRB) materials for remediating groundwater heavily contaminated by landfill leachate, in column tests using various mixtures of zero-valent iron (ZVI), zeolite (Zeo) and activated carbon (AC) with 0.01-0.25, 3.0-5.0 and 0.7-1.0mm grain sizes, respectively. The main contributors to the removal of organic/inorganic contaminants were ZVI and AC, and the optimum weight ratio of the three PRB materials for removing the contaminants and maintaining adequate hydraulic conductivity was found to be 5:1:4. Average reductions in chemical oxygen demand (COD) and contents of total nitrogen (TN), ammonium, Ni, Pb and 16 polycyclic aromatic hydrocarbons (PAHs) from test samples using this mixture were 55.8%, 70.8%, 89.2%, 70.7%, 92.7% and 94.2%, respectively. We also developed a systematic method for estimating the minimum required thickness and longevity of the PRB materials. A ≥ 309.6 cm layer with the optimum composition is needed for satisfactory longevity, defined here as meeting the Grade III criteria (the Chinese National Bureau of Standards: GB/T14848/93) for in situ treatment of the sampled groundwater for ≥ 10 years.

  16. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-12-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma.

  17. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier.

    PubMed

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-10-21

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR + PRB showed the lowest leaching value for each HM in the S2 and S3 regions.

  18. Formation of ferrihydrite and associated iron corrosion products in permeable reactive barriers of zero-valent iron

    NASA Technical Reports Server (NTRS)

    Furukawa, Yoko; Kim, Jin-Wook; Watkins, Janet; Wilkin, Richard T.

    2002-01-01

    Ferrihydrite, which is known to form in the presence of oxygen and to be stabilized by the adsorption of Si, PO4 and SO4, is ubiquitous in the fine-grained fractions of permeable reactive barrier (PRB) samples from the U.S. Coast Guard Support Center (Elizabeth City, NC) and the Denver Federal Center (Lakewood, CO) studied by high-resolution transmission electron microscopy and selected area electron diffraction. The concurrent energy-dispersive X-ray data indicate a strong association between ferrihydrite and metals such as Si, Ca, and Cr. Magnetite, green rust 1, aragonite, calcite, mackinawite, greigite and lepidocrocite were also present, indicative of a geochemical environment that is temporally and spatially heterogeneous. Whereas magnetite, which is known to form due to anaerobic Fe0 corrosion, passivates the Fe0 surface, ferrihydrite precipitation occurs away from the immediate Fe0 surface, forming small (<0.1 microm) discrete clusters. Consequently, Fe0-PRBs may remain effective for a longer period of time in slightly oxidized groundwater systems where ferrihydrite formation occurs compared to oxygen-depleted systems where magnetite passivation occurs. The ubiquitous presence of ferrihydrite suggests that the use of Fe0-PRBs may be extended to applications that require contaminant adsorption rather than, or in addition to, redox-promoted contaminant degradation.

  19. Examples of Department of Energy Successes for Remediation of Contaminated Groundwater: Permeable Reactive Barrier and Dynamic Underground Stripping ASTD Projects

    SciTech Connect

    Purdy, C.; Gerdes, K.; Aljayoushi, J.; Kaback, D.; Ivory, T.

    2002-02-27

    Since 1998, the Department of Energy's (DOE) Office of Environmental Management has funded the Accelerated Site Technology Deployment (ASTD) Program to expedite deployment of alternative technologies that can save time and money for the environmental cleanup at DOE sites across the nation. The ASTD program has accelerated more than one hundred deployments of new technologies under 76 projects that focus on a broad spectrum of EM problems. More than 25 environmental restoration projects have been initiated to solve the following types of problems: characterization of the subsurface using chemical, radiological, geophysical, and statistical methods; treatment of groundwater contaminated with DNAPLs, metals, or radionuclides; and other projects such as landfill covers, purge water management systems, and treatment of explosives-contaminated soils. One of the major goals of the ASTD Program is to deploy a new technology or process at multiple DOE sites. ASTD projects are encouraged to identify subsequent deployments at other sites. Some of the projects that have successfully deployed technologies at multiple sites focusing on cleanup of contaminated groundwater include: Permeable Reactive Barriers (Monticello, Rocky Flats, and Kansas City), treating uranium and organics in groundwater; and Dynamic Underground Stripping (Portsmouth, and Savannah River), thermally treating DNAPL source zones. Each year more and more new technologies and approaches are being used at DOE sites due to the ASTD program. DOE sites are sharing their successes and communicating lessons learned so that the new technologies can replace the baseline or standard approaches at DOE sites, thus expediting cleanup and saving money.

  20. Microbial and mineral evolution in zero valent iron-based permeable reactive barriers during long-term operations.

    PubMed

    Kumar, Naresh; Millot, Romain; Battaglia-Brunet, Fabienne; Omoregie, Enoma; Chaurand, Perrine; Borschneck, Daniel; Bastiaens, Leen; Rose, Jérôme

    2016-03-01

    Impacts of subsurface biogeochemical processes over time have always been a concern for the long-term performance of zero valent iron (Fe(0))-based permeable reactive barriers (PRBs). To evaluate the biogeochemical impacts, laboratory experiments were performed using flow-through glass columns for 210 days at controlled temperature (20 °C). Two different particle sizes of Fe(0) were used in the columns, and to simulate indigenous microbial activity, extra carbon source was provided in the two columns (biotic columns) and the remaining two columns were kept abiotic using gamma radiations. Heavy metals (Zn, As) were removed efficiently in all the columns, and no exhaustion of treatment capability or clogging was observed during our experimental duration. Newly formed Fe mineral phases and precipitates were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and micro-XRF techniques in solid phase at the end of the experiment. In addition, 16S rRNA gene extraction was used for microbial community identification in biotic columns. During the incubation, microbial population shifted in favor of Desulfosporosinus species (sulfate-reducing bacteria) from initial dominance of Acidithiobacillus ferrooxidans in sediments. Dominant mineral phases detected in biotic columns were mackinawite (FeS) and sulfate green rust, while in abiotic columns, magnetite/maghemite phases were more prevalent.

  1. Column test-based optimization of the permeable reactive barrier (PRB) technique for remediating groundwater contaminated by landfill leachates

    NASA Astrophysics Data System (ADS)

    Zhou, Dan; Li, Yan; Zhang, Yinbo; Zhang, Chang; Li, Xiongfei; Chen, Zhiliang; Huang, Junyi; Li, Xia; Flores, Giancarlo; Kamon, Masashi

    2014-11-01

    We investigated the optimum composition of permeable reactive barrier (PRB) materials for remediating groundwater heavily contaminated by landfill leachate, in column tests using various mixtures of zero-valent iron (ZVI), zeolite (Zeo) and activated carbon (AC) with 0.01-0.25, 3.0-5.0 and 0.7-1.0 mm grain sizes, respectively. The main contributors to the removal of organic/inorganic contaminants were ZVI and AC, and the optimum weight ratio of the three PRB materials for removing the contaminants and maintaining adequate hydraulic conductivity was found to be 5:1:4. Average reductions in chemical oxygen demand (COD) and contents of total nitrogen (TN), ammonium, Ni, Pb and 16 polycyclic aromatic hydrocarbons (PAHs) from test samples using this mixture were 55.8%, 70.8%, 89.2%, 70.7%, 92.7% and 94.2%, respectively. We also developed a systematic method for estimating the minimum required thickness and longevity of the PRB materials. A ≥ 309.6 cm layer with the optimum composition is needed for satisfactory longevity, defined here as meeting the Grade III criteria (the Chinese National Bureau of Standards: GB/T14848/93) for in situ treatment of the sampled groundwater for ≥ 10 years.

  2. Ecologically based targets for bioavailable (reactive) nitrogen discharge from the drainage basins of the Wet Tropics region, Great Barrier Reef.

    PubMed

    Wooldridge, Scott A; Brodie, Jon E; Kroon, Frederieke J; Turner, Ryan D R

    2015-08-15

    A modelling framework is developed for the Wet Tropics region of the Great Barrier Reef that links a quantitative river discharge parameter (viz. dissolved inorganic nitrogen concentration, DIN) with an eutrophication indicator within the marine environment (viz. chlorophyll-a concentration, chl-a). The model predicts catchment-specific levels of reduction (%) in end-of-river DIN concentrations (as a proxy for total potentially reactive nitrogen, PRN) needed to ensure compliance with chl-a 'trigger' guidelines for the ecologically distinct, but PRN-related issues of crown-of-thorns starfish (COTS) outbreaks, reef biodiversity loss, and thermal bleaching sensitivity. The results indicate that even for river basins dominated by agricultural land uses, quite modest reductions in end-of-river PRN concentrations (∼20-40%) may assist in mitigating the risk of primary COTS outbreaks from the mid-shelf reefs of the Wet Tropics. However, more significant reductions (∼60-80%) are required to halt and reverse declines in reef biodiversity, and loss of thermal bleaching resistance.

  3. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    PubMed Central

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-01-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR + PRB showed the lowest leaching value for each HM in the S2 and S3 regions. PMID:26486449

  4. Microbial communities and biodegradation in lab-scale BTEX-contaminated groundwater remediation using an oxygen-releasing reactive barrier.

    PubMed

    Lin, Chi-Wen; Chen, Li-Hsuan; I, Yet-Pole; Lai, Chi-Yung

    2010-03-01

    To remediate benzene, toluene, ethylbenzene and xylene (BTEX) -contaminated groundwater, a biotreatment process including biostimulation and bioaugmentation was simulated using oxygen-releasing reactive barriers (ORRB) and water with added BTEX in a lab-scale system. The results showed that the capability for BTEX removal decreases in the order of benzene, toluene, p-xylene, ethylbenzene for both added-nitrogen and no-added-nitrogen under BTEX concentrations at 30 mg l(-1). The removal efficiencies in ORRB systems were higher in the nitrogen-added condition for biostimulation compared with the no-nitrogen-added condition; moreover, an increased pattern for removal was observed during the bioaugmentation process. The oxygen content was found to be inversely proportional to the distance from the ORRB, as evidenced by observing that the average bacteria densities were two orders higher when located at 15 cm compared with 30 cm from the ORRB. The microbial community structure was similar in both cases of added-nitrogen and the no-added-nitrogen conditions.

  5. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    PubMed Central

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-01-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma. PMID:26656857

  6. Development of the SEAtrace{trademark} barrier verification and validation technology. Final report

    SciTech Connect

    Dunn, S.D.; Lowry, W.; Walsh, R.; Rao, D.V.; Williams, C.

    1998-08-01

    In-situ barrier emplacement techniques and materials for the containment of high-risk contaminants in soils are currently being developed by the Department of Energy (DOE). Because of their relatively high cost, the barriers are intended to be used in cases where the risk is too great to remove the contaminants, the contaminants are too difficult to remove with current technologies, or the potential movement of the contaminants to the water table is so high that immediate action needs to be taken to reduce health risks. Assessing the integrity of the barrier once it is emplaced, and during its anticipated life, is a very difficult but necessary requirement. Science and Engineering Associates, Inc., (SEA) and Sandia National Laboratories (SNL) have developed a quantitative subsurface barrier assessment system using gaseous tracers in support of the Subsurface Contaminants Focus Area barrier technology program. Called SEAtrace{trademark}, this system integrates an autonomous, multi-point soil vapor sampling and analysis system with a global optimization modeling methodology to locate and size barrier breaches in real time. The methodology for the global optimization code was completed and a prototype code written using simplifying assumptions. Preliminary modeling work to validate the code assumptions were performed using the T2VOC numerical code. A multi-point field sampling system was built to take soil gas samples and analyze for tracer gas concentration. The tracer concentration histories were used in the global optimization code to locate and size barrier breaches. SEAtrace{trademark} was consistently able to detect and locate leaks, even under very adverse conditions. The system was able to locate the leak to within 0.75 m of the actual value, and was able to determine the size of the leak to within 0.15 m.

  7. Linkage of Mineral Precipitation to the Development of Heterogeneity in Permeable Reactive Barrier: a Field Column Study

    NASA Astrophysics Data System (ADS)

    Kamolpornwijit, W.; Liang, L.; Liang, L.; Moline, G. R.; Sullivan, A. B.; West, O. R.

    2001-12-01

    A column study was conducted on site at Y-12, Oak Ridge, TN, to investigate the rate of mineral accumulation in relation to the hydraulic change as a result of heterogeneity development in a Fe(0) permeable reactive barrier (PRB). To better simulate the fluctuation in groundwater characteristics and the least disturbance to gas-water equilibrium, two columns filled with zero valent iron (mesh size 8-50 obtained from Peerless Industries) were set up with direct connections to a groundwater well. Water samples were taken periodically to observe iron deterioration, ionic species removal, mineral precipitation, and hydrological properties under both accelerated- and normal-groundwater flow conditions. According to the ionic species analysis and the hydraulic tracer tests, the initially established plug flow behavior in the accelerated-flow column was maintained after 150 pore volumes (PVs); the porosity loss due to mineral precipitation was estimated to be 6.2-8.7%. The precipitate volumes were calculated from mass balance with assumed precipitate species and densities of precipitates as pure compounds. As a result, this calculation represents the upper bound on precipitate amounts and porosity loss. Using literature published corrosion rate at 0.7 mM/Kg.day, the estimated lower bound for porosity loss is 2.3%. With time, the deviation from plug flow behavior was observed as the columns underwent complex heterogeneity development, which was reflected in both ionic species removals and hydrological performance. The development of preferential flow paths was caused by mineral precipitation and gas production. After 490 PVs, 4900 liters of groundwater, 215 days of column study, with an estimate of 16.7-24.7% porosity loss, the breakthrough time was shortened from 270 to 50 minutes. According to the resident time obtained from hydraulic tracer tests, the 215 days of column operation is equivalent to 9.5 years operation at a field site, based on 0.3m/d flow of 1-meter thick

  8. Low-Cost Protective Layer Coatings on Thermal Barrier Coatings via CCVD. Final Report

    SciTech Connect

    Hendrick, Michelle

    2003-09-18

    MicroCoating Technologies, Inc., investigated the use of the Combustion Chemical Vapor Deposition (CCVD) process to deposit oxygen or sintering barrier coatings for thermal barrier coating (TBC) applications. In addition, it looked at the use of its nanopowders by the NanoSpray process for developing smoothing layers on TBCs. Testing and analysis of coated substrates included heat treatments, scanning electron microscopy, x-ray diffraction and profilometry. Coatings on TBC-coated superalloy coupons were tested by an outside collaborator. Results from the investigations indicated that the thin film coatings were not well-suited as barrier layers on the rough bond coat or TBC. Subsequent investigations considered smoothing layers on the TBC, as suggested by the collaborator, using nanopowder-based coatings. Smoothing of substrate surfaces by 50% was observed by profilometry.

  9. Static reactive power compensators for high-voltage power systems. Final report

    SciTech Connect

    Not Available

    1981-04-01

    A study conducted to summarize the role of static reactive power compensators for high voltage power system applications is described. This information should be useful to the utility system planning engineer in applying static var systems (SVS) to high voltage as (HVAC) systems. The static var system is defined as a form of reactive power compensator. The general need for reactive power compensation in HVAC systems is discussed, and the static var system is compared to other devices utilized to provide reactive power compensation. Examples are presented of applying SVS for specific functions, such as the prevention of voltage collapse. The operating principles of commercially available SVS's are discussed in detail. The perormance and active power loss characteristics of SVS types are compared.

  10. FeS-coated sand for removal of arsenic(III) under anaerobic conditions in permeable reactive barriers

    USGS Publications Warehouse

    Han, Y.-S.; Gallegos, T.J.; Demond, A.H.; Hayes, K.F.

    2011-01-01

    Iron sulfide (as mackinawite, FeS) has shown considerable promise as a material for the removal of As(III) under anoxic conditions. However, as a nanoparticulate material, synthetic FeS is not suitable for use in conventional permeable reactive barriers (PRBs). This study developed a methodology for coating a natural silica sand to produce a material of an appropriate diameter for a PRB. Aging time, pH, rinse time, and volume ratios were varied, with a maximum coating of 4.0 mg FeS/g sand achieved using a pH 5.5 solution at a 1:4 volume ratio (sand: 2 g/L FeS suspension), three days of aging and no rinsing. Comparing the mass deposited on the sand, which had a natural iron-oxide coating, with and without chemical washing showed that the iron-oxide coating was essential to the formation of a stable FeS coating. Scanning electron microscopy images of the FeS-coated sand showed a patchwise FeS surface coating. X-ray photoelectron spectroscopy showed a partial oxidation of the Fe(II) to Fe(III) during the coating process, and some oxidation of S to polysulfides. Removal of As(III) by FeS-coated sand was 30% of that by nanoparticulate FeS at pH 5 and 7. At pH 9, the relative removal was 400%, perhaps due to the natural oxide coating of the sand or a secondary mineral phase from mackinawite oxidation. Although many studies have investigated the coating of sands with iron oxides, little prior work reports coating with iron sulfides. The results suggest that a suitable PRB material for the removal of As(III) under anoxic conditions can be produced through the deposition of a coating of FeS onto natural silica sand with an iron-oxide coating. ?? 2010 Elsevier Ltd.

  11. Enhanced chitosan beads-supported Fe(0)-nanoparticles for removal of heavy metals from electroplating wastewater in permeable reactive barriers.

    PubMed

    Liu, Tingyi; Yang, Xi; Wang, Zhong-Liang; Yan, Xiaoxing

    2013-11-01

    The removal of heavy metals from electroplating wastewater is a matter of paramount importance due to their high toxicity causing major environmental pollution problems. Nanoscale zero-valent iron (NZVI) became more effective to remove heavy metals from electroplating wastewater when enhanced chitosan (CS) beads were introduced as a support material in permeable reactive barriers (PRBs). The removal rate of Cr (VI) decreased with an increase of pH and initial Cr (VI) concentration. However, the removal rates of Cu (II), Cd (II) and Pb (II) increased with an increase of pH while decreased with an increase of their initial concentrations. The initial concentrations of heavy metals showed an effect on their removal sequence. Scanning electron microscope images showed that CS-NZVI beads enhanced by ethylene glycol diglycidyl ether (EGDE) had a loose and porous surface with a nucleus-shell structure. The pore size of the nucleus ranged from 19.2 to 138.6 μm with an average aperture size of around 58.6 μm. The shell showed a tube structure and electroplating wastewaters may reach NZVI through these tubes. X-ray photoelectron spectroscope (XPS) demonstrated that the reduction of Cr (VI) to Cr (III) was complete in less than 2 h. Cu (II) and Pb (II) were removed via predominant reduction and auxiliary adsorption. However, main adsorption and auxiliary reduction worked for the removal of Cd (II). The removal rate of total Cr, Cu (II), Cd (II) and Pb (II) from actual electroplating wastewater was 89.4%, 98.9%, 94.9% and 99.4%, respectively. The findings revealed that EGDE-CS-NZVI-beads PRBs had the capacity to remediate actual electroplating wastewater and may become an effective and promising technology for in situ remediation of heavy metals.

  12. Hydraulic and geochemical performance of a permeable reactive barrier containing zero-valent iron, Denver Federal Center

    USGS Publications Warehouse

    McMahon, P.B.; Dennehy, K.F.; Sandstrom, M.W.

    1999-01-01

    The hydraulic and geochemical performance of a 366 m long permeable reactive barrier (PRB) at the Denver Federal Center; Denver, Colorado, was evaluated. The funnel and gate system, which was installed in 1996 to intercept and remediate ground water contaminated with chlorinated aliphatic hydrocarbons (CAHs), contained four 12.2 m wide gates filled with zero-valent iron. Ground water mounding on the upgradient side of the PRB resulted in a tenfold increase in the hydraulic gradient and ground water velocity through the gates compared to areas of the aquifer unaffected by the PRB. Water balance calculations for April 1997 indicate that about 75% of the ground water moving toward the PRB from upgradient areas moved through the gates. The rest of the water either accumulated on the upgradient side of the PRB or bypassed the PRB. Chemical data from monitoring wells screened down-gradient, beneath, and at the ends of the PRB indicate that contaminants had not bypassed the PRB, except in a few isolated areas. Greater than 99% of the CAH mass entering the gates was retained by the iron. Fifty-one percent of the CAH carbon entering one gate was accounted for in dissolved C1 and C2 hydrocarbons, primarily ethane and ethene, which indicates that CAHs may adsorb to the iron prior to being dehalogenated. Treated water exiting the gates displaced contaminated ground water at a distance of at least 3 m downgradient from the PRB by the end of 1997. Measurements of dissolved inorganic ions in one gate indicate that calcite and siderite precipitation in the gate could reduce gate porosity by about 0.35% per year. Results from this study indicate that funnel and gate systems containing zero-valent iron can effectively treat ground water contaminated with CAHs. However, the hydrologic impacts of the PRB on the flow system need to be fully understood to prevent contaminants from bypassing the PRB.

  13. Uptake Mechanisms of Eu(III) on Hydroxyapatite: A Potential Permeable Reactive Barrier Backfill Material for Trapping Trivalent Minor Actinides.

    PubMed

    Xu, Lin; Zheng, Tao; Yang, Shitong; Zhang, Linjuan; Wang, Jianqiang; Liu, Wei; Chen, Lanhua; Diwu, Juan; Chai, Zhifang; Wang, Shuao

    2016-04-05

    The permeable reactive barrier (PRB) technique has attracted an increasing level of attention for the in situ remediation of contaminated groundwater. In this study, the macroscopic uptake behaviors and microscopic speciation of Eu(III) on hydroxyapatite (HAP) were investigated by a combination of theoretical modeling, batch experiments, powder X-ray diffraction (PXRD) fitting, and X-ray absorption spectroscopy (XAS). The underlying removal mechanisms were identified to further assess the application potential of HAP as an effective PRB backfill material. The macroscopic analysis revealed that nearly all dissolved Eu(III) in solution was removed at pH 6.5 within an extremely short reaction time of 5 min. In addition, the thermodynamic calculations, desorption experiments, and PXRD and XAS analyses definitely confirmed the formation of the EuPO4·H2O(s) phase during the process of uptake of dissolved Eu(III) by HAP via the dissolution-precipitation mechanism. A detailed comparison of the present experimental findings and related HAP-metal systems suggests that the relative contribution of precipitation to the total Eu(III) removal increases as the P:Eu ratio decreases. The dosage of HAP-based PRB for the remediation of groundwater polluted by Eu(III) and analogous trivalent actinides [e.g., Am(III) and Cm(III)] should be strictly controlled depending on the dissolved Eu(III) concentration to obtain an optimal P:M (M represents Eu, Am, or Cm) ratio and treatment efficiency.

  14. Long-term performance of permeable reactive barriers using zero-valent iron: geochemical and microbiological effects.

    PubMed

    Wilkin, Richard T; Puls, Robert W; Sewell, Guy W

    2003-01-01

    Geochemical and microbiological factors that control long-term performance of subsurface permeable reactive barriers were evaluated at the Elizabeth City, North Carolina, and the Denver Federal Center, Colorado, sites. These ground water treatment systems use zero-valent iron filings (Peerless Metal Powders Inc.) to intercept and remediate chlorinated hydrocarbon compounds at the Denver Federal Center (funnel-and-gate system) and overlapping plumes of hexavalent chromium and chlorinated hydrocarbons at Elizabeth City (continuous wall system). Zero-valent iron at both sites is a long-term sink for carbon, sulfur, calcium, silicon, nitrogen, and magnesium. After about four years of operation, the average rates of inorganic carbon (IC) and sulfur (S) accumulation are 0.09 and 0.02 kg/m2/year, respectively, at Elizabeth City where upgradient waters contain <400 mg/L of total dissolved solids (TDS). At the Denver Federal Center site, upgradient ground water contains 1000 to 1200 mg/L TDS and rates of IC and S accumulation are as high as 2.16 and 0.80 kg/m2/year, respectively. At both sites, consistent patterns of spatially variable mineral precipitation and microbial activity are observed. Mineral precipitates and microbial biomass accumulate the fastest near the upgradient aquifer-Fe0 interface. Maximum net reductions in porosity due to the accumulation of sulfur and inorganic carbon precipitates range from 0.032 at Elizabeth City to 0.062 at the Denver Federal Center (gate 2) after about four years. Although pore space has been lost due the accumulation of authigenic components, neither site shows evidence of pervasive pore clogging after four years of operation.

  15. Conflicting Assumptions as Barriers to Inter-American Communication. Final Report.

    ERIC Educational Resources Information Center

    Gorden, Raymond L.

    The general purpose of this project was to produce some reliable and valid knowledge of how differences in the non-linguistic aspects of North American and Latin American socio-cultural patterns (concepts, values, beliefs, norms, expectations, and ethnocentrism) act as barriers to cross-cultural communication. The end product was to be…

  16. Research Update: Reactively sputtered nanometer-thin ZrN film as a diffusion barrier between Al and boron layers for radiation detector applications

    SciTech Connect

    Golshani, Negin Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R.

    2014-10-01

    In this paper, optimization of the process flow for PureB detectors is investigated. Diffusion barrier layers between a boron layer and the aluminum interconnect can be used to enhance the performance and visual appearance of radiation detectors. Few nanometers-thin Zirconium Nitride (ZrN) layer deposited by reactive sputtering in a mixture of Ar/N{sub 2}, is identified as a reliable diffusion barrier with better fabrication process compatibility than others. The barrier properties of this layer have been tested for different boron layers deposited at low and high temperatures with extensive optical microscopy analyses, electron beam induced current, SEM, and electrical measurements. This study demonstrated that spiking behavior of pure Al on Si can be prevented by the thin ZrN layer thus improving the performance of the radiation detectors fabricated using boron layer.

  17. Impact of microbial activities on the mineralogy and performance of column-scale permeable reactive iron barriers operated under two different redox conditions.

    PubMed

    Van Nooten, Thomas; Lieben, François; Dries, Jan; Pirard, Eric; Springael, Dirk; Bastiaens, Leen

    2007-08-15

    The present study focuses on the impact of microbial activities on the performance of various long-term operated laboratory-scale permeable reactive barriers. The barriers contained both aquifer and Fe0 compartments and had received either sulfate or iron(III)-EDTA to promote sulfate-reducing and iron(III)-reducing bacteria, respectively. After dismantlement of the compartments after almost 3 years of operation, DNA-based PCR-DGGE analysis revealed the presence of methanogenic, sulfate-reducing, metal-reducing, and denitrifying bacteria within as well as up- and downgradient of the Fe0 matrix. Under all imposed conditions, the main secondary phases were vivianite, siderite, ferrous hydroxy carbonate, and carbonate green rust as found by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). Under sulfate-reduction promoting conditions, iron sulfides were formed in addition, resulting in 7 and 10 times higher degradation rates for PCE and TCE, respectively, compared to unreacted iron. These results indicate that the presence of sulfate-reducing bacteria in or around iron barriers and the subsequent formation of iron sulfides might increase the barrier reactivity.

  18. Corrosion barriers for silver-based telescope mirrors: comparative study of plasma-enhanced atomic layer deposition and reactive evaporation of aluminum oxide

    NASA Astrophysics Data System (ADS)

    Fryauf, David M.; Phillips, Andrew C.; Kobayashi, Nobuhiko P.

    2015-10-01

    Astronomical telescopes continue to demand high-endurance high-reflectivity silver (Ag) mirrors that can withstand years of exposure in Earth-based observatory environments. We present promising results of improved Ag mirror robustness using plasma-enhanced atomic layer deposition (PEALD) of aluminum oxide (AlOx) as a top barrier layer. Transparent AlOx is suitable for many optical applications; therefore, it has been the initial material of choice for this study. Two coating recipes developed with electron beam ion-assisted deposition (e-beam IAD) of materials including yttrium fluoride, titanium nitride, oxides of yttrium, tantalum, and silicon are used to provide variations in basic Ag mirror structures to compare the endurance of reactive e-beam IAD barriers with PEALD barriers. Samples undergo high temperature/high humidity environmental testing in a controlled environment of 80% humidity at 80°C for 10 days. Environmental testing shows visible results suggesting that the PEALD AlOx barrier offers robust protection against chemical corrosion and moisture permeation. Ag mirror structures were further characterized by reflectivity/absorption before and after deposition of AlOx barriers.

  19. Investigating a Chemoselective Grignard Reaction in an Undergraduate Discovery Lab to Predict Reactivity and Final Products

    ERIC Educational Resources Information Center

    Maher, Michael J.; Hayes, Colin O.; Vaccaro, Francesca A.; Flynn, Cailyn B.; Thedford, R. Paxton; Stephenson, Clifton J.

    2016-01-01

    A discovery-based Grignard experiment that emphasizes several important concepts in organic chemistry is reported. The Grignard reagent from 1- bromo-4-chlorobenzene was prepared and reacted with dimethylformamide (DMF) to synthesize 4-chlorobenzaldehyde. Students were tasked with predicting halogen reactivity in the formation of the Grignard…

  20. Verification and monitoring of deep granular iron permeable reactive barriers emplaced by vertical hydraulic fracturing and injection for groundwater remediation

    NASA Astrophysics Data System (ADS)

    Hubble, David Wallace

    This study evaluated the use of vertical hydraulic fracturing and injection (VHFI) to emplace granular iron as a deep passive treatment system to remove organic contaminants from groundwater at the Massachusetts Military Reservation on Cape Cod, Massachusetts. It was the first permeable reactive barrier (PRB) constructed at a depth greater than 15 m below the ground surface. VHFI propagates a vertical fracture from a slot cut through the injection-well casing at a selected depth and orientation. Granular iron is suspended in a viscous fluid using a biodegradable guar polymer and pumped through the slot to form a thin vertical sheet. Two PRBs were emplaced 6 m apart and perpendicular to the groundwater flow direction with mid-depths of about 30 m below the ground surface. Due to the depth, all of the emplacement and verification methods used down-hole tools. Resistivity imaging used salt added to the guar as an electrical tracer to map the spread of the VHFI fluid for propagation control and to estimate the extent of the completed PRB. Radar tomography before and after emplacement also provided images of the PRBs and hydraulic pulse testing and electromagnetic logging provided additional data. One PRB consisted of 40 tonnes of granular iron and was estimated to be an average of 80 mm thick. Based on geophysical imaging, the 100% iron PRB was 15 m long and extended from about 24.5 to 35.5 m depth. The second PRB consisted of a mixture of 5.6 tonnes of well sand and 4.4 tonnes of iron, but was only partially completed. Based on imaging, the sand/iron PRB comprised an area 9 m long extending from about 27 to 34.5 m below the ground surface. The proximity of screened wells, which deviated significantly from vertical toward the PRB alignment, resulted in loss of VHFI control. A sub-horizontal layer of iron formed between the 100% iron PRB and several of the wells. Similarly, piping failure zones formed between the sand/iron PRB and two geophysical wells. Selected

  1. Molecular-scale characterization of uranium sorption by bone apatite materials for a permeable reactive barrier demonstration.

    PubMed

    Fuller, C C; Bargar, J R; Davis, J A

    2003-10-15

    Uranium binding to bone charcoal and bone meal apatite materials was investigated using U L(III)-edge EXAFS spectroscopy and synchrotron source XRD measurements of laboratory batch preparations in the absence and presence of dissolved carbonate. Pelletized bone char apatite recovered from a permeable reactive barrier (PRB) at Fry Canyon, UT, was also studied. EXAFS analyses indicate that U(VI) sorption in the absence of dissolved carbonate occurred by surface complexation of U(VI) for sorbed concentrations < or = 5500 microg U(VI)/g for all materials with the exception of crushed bone char pellets. Either a split or a disordered equatorial oxygen shell was observed, consistent with complexation of uranyl by the apatite surface. A second shell of atoms at a distance of 2.9 A was required to fit the spectra of samples prepared in the presence of dissolved carbonate (4.8 mM total) and is interpreted as formation of ternary carbonate complexes with sorbed U(VI). A U-P distance at 3.5-3.6 A was found for most samples under conditions where uranyl phosphate phases did not form, which is consistent with monodentate coordination of uranyl by phosphate groups in the apatite surface. At sorbed concentrations > or = 5500 microg U(VI)/g in the absence of dissolved carbonate, formation of the uranyl phosphate solid phase, chernikovite, was observed. The presence of dissolved carbonate (4.8 mM total) suppressed the formation of chernikovite, which was not detected even with sorbed U(VI) up to 12,300 microg U(VI)/g in batch samples of bone meal, bone charcoal, and reagent-grade hydroxyapatite. EXAFS spectra of bone char samples recovered from the Fry Canyon PRB were comparable to laboratory samples in the presence of dissolved carbonate where U(VI) sorption occurred by surface complexation. Our findings demonstrate that uranium uptake by bone apatite will probably occur by surface complexation instead of precipitation of uranyl phosphate phases under the groundwater conditions

  2. Molecular-scale characterization of uranium sorption by bone apatite materials for a permeable reactive barrier demonstration

    USGS Publications Warehouse

    Fuller, C.C.; Bargar, J.R.; Davis, J.A.

    2003-01-01

    Uranium binding to bone charcoal and bone meal apatite materials was investigated using U LIII-edge EXAFS spectroscopy and synchrotron source XRD measurements of laboratory batch preparations in the absence and presence of dissolved carbonate. Pelletized bone char apatite recovered from a permeable reactive barrier (PRB) at Fry Canyon, UT, was also studied. EXAFS analyses indicate that U(VI) sorption in the absence of dissolved carbonate occurred by surface complexation of U(VI) for sorbed concentrations ??? 5500 ??g U(VI)/g for all materials with the exception of crushed bone char pellets. Either a split or a disordered equatorial oxygen shell was observed, consistent with complexation of uranyl by the apatite surface. A second shell of atoms at a distance of 2.9 A?? was required to fit the spectra of samples prepared in the presence of dissolved carbonate (4.8 mM total) and is interpreted as formation of ternary carbonate complexes with sorbed U(VI). A U-P distance at 3.5-3.6 A?? was found for most samples under conditions where uranyl phosphate phases did not form, which is consistent with monodentate coordination of uranyl by phosphate groups in the apatite surface. At sorbed concentrations ??? 5500 ??g U(VI)/g in the absence of dissolved carbonate, formation of the uranyl phosphate solid phase, chernikovite, was observed. The presence of dissolved carbonate (4.8 mM total) suppressed the formation of chernikovite, which was not detected even with sorbed U(VI) up to 12 300 ??g U(VI)/g in batch samples of bone meal, bone charcoal, and reagent-grade hydroxyapatite. EXAFS spectra of bone char samples recovered from the Fry Canyon PRB were comparable to laboratory samples in the presence of dissolved carbonate where U(VI) sorption occurred by surface complexation. Our findings demonstrate that uranium uptake by bone apatite will probably occur by surface complexation instead of precipitation of uranyl phosphate phases under the groundwater conditions found at many U

  3. Technical and economic barriers to innovative gas storage. Final report, November 1991-July 1992

    SciTech Connect

    Copeland, R.J.; Feinberg, D.A.; Hastings, G.A.

    1993-03-01

    To evaluate the technical and economic barriers to innovative natural gas storage technologies, advantages and disadvantages of several end use applications were analyzed, including on-grid deliverability of natural gas, transporting natural gas to off-grid end users, and storage of natural gas at an off-grid end user's site. Three basic innovative approaches were investigated: (1) separation of the higher molecular weight components of the pipeline gas and storage of the separated ethane, propane, butane, etc., as a liquid; (2) separation of the components with storage in the separating media; and (3) storage of the pipeline gas without changing its composition.

  4. Barriers to private-sector participation in public transportation. Final report

    SciTech Connect

    Thompson, T.A.

    1986-09-01

    Chapter One considers the full range of public-transportation services the private sector could provide looking at current U.S. examples. Chapter Two describes the Federal, state, and local barriers currently limiting private-sector provision of these services. Chapter Three summarizes the unique contribution of this study: an analysis of three New York counties utilizing private operators to provide varying percentages of public transportation under different institutional structures. The full case studies of the three New York counties - Onondaga (Syracuse), Suffolk (eastern Long Island), and Westchester (New York City suburb) - are presented in Appendices A-C. Appendices D and E exemplify purchase of service contracts currently in New York.

  5. Advancing Reactive Tracer Methods for Measurement of Thermal Evolution in Geothermal Reservoirs: Final Report

    SciTech Connect

    Mitchell A. Plummer; Carl D. Palmer; Earl D. Mattson; Laurence C. Hull; George D. Redden

    2011-07-01

    The injection of cold fluids into engineered geothermal system (EGS) and conventional geothermal reservoirs may be done to help extract heat from the subsurface or to maintain pressures within the reservoir (e.g., Rose et al., 2001). As these injected fluids move along fractures, they acquire heat from the rock matrix and remove it from the reservoir as they are extracted to the surface. A consequence of such injection is the migration of a cold-fluid front through the reservoir (Figure 1) that could eventually reach the production well and result in the lowering of the temperature of the produced fluids (thermal breakthrough). Efficient operation of an EGS as well as conventional geothermal systems involving cold-fluid injection requires accurate and timely information about thermal depletion of the reservoir in response to operation. In particular, accurate predictions of the time to thermal breakthrough and subsequent rate of thermal drawdown are necessary for reservoir management, design of fracture stimulation and well drilling programs, and forecasting of economic return. A potential method for estimating migration of a cold front between an injection well and a production well is through application of reactive tracer tests, using chemical whose rate of degradation is dependent on the reservoir temperature between the two wells (e.g., Robinson 1985). With repeated tests, the rate of migration of the thermal front can be determined, and the time to thermal breakthrough calculated. While the basic theory behind the concept of thermal tracers has been understood for some time, effective application of the method has yet to be demonstrated. This report describes results of a study that used several methods to investigate application of reactive tracers to monitoring the thermal evolution of a geothermal reservoir. These methods included (1) mathematical investigation of the sensitivity of known and hypothetical reactive tracers, (2) laboratory testing of novel

  6. Smart structures for application in ceramic barrier filter technology. Final report, August 1991--August 1994

    SciTech Connect

    Weinstein, S.J.; Lippert, T.E

    1994-12-01

    High temperature optical fiber sensors were developed to measure the in-service stressing that occurs in ceramic barrier filter systems. The optical fiber sensors were based on improvements to the sensor design developed under the DOE/METC Smart Structures for Fossil Energy Applications contract no. DE-AC21-89MC25159. In-house application testing of these sensors on both candle and cross-flow filters were performed in the Westinghouse Science and Technology Center High-Temperature, High-Pressure Filter Test Facility and the results analyzed. This report summarizes the sensor developments, methods to apply the sensors to the filters for in-situ testing, and the test results from the four in-house tests that were performed.

  7. Mild coal pretreatment to improve liquefaction reactivity. Final technical report, September 1990--February 1994

    SciTech Connect

    Miller, R.L.; Shams, K.G.

    1994-07-01

    Recent research efforts in direct coal liquefaction are focused on lowering the level of reaction severity, identification and determination of the causes of retrogressive reactions, and improving the economics of the process. Ambient pretreatment of coals using methanol and a trace amount of hydrochloric acid was extensively studied in connection with low severity coal liquefaction. Ambient pretreatment of eight Argonne coals using methanol/HCl improved THF-soluble conversions 24.5 wt % (maf basis) for Wyodak subbituminous coal and 28.4 wt % for Beulah-Zap lignite with an average increase of 14.9 wt % for the eight Argonne coals at 623 K (350{degrees}C) reaction temperature and 30 minutes reaction time. Optimal pretreatment conditions were determined using Wyodak and Illinois No. 6 coals. Acid concentration was the most important pretreatment variable studied; liquefaction reactivity increased with increasing acid concentration up to 2 vol %. The FTIR spectra of treated and untreated Wyodak coal samples demonstrated formation of carboxylic functional groups during pretreatment, a result of divalent (Ca, Mg) cationic bridge destruction. The extent of liquefaction reactivity directly correlated with the amount of calcium removed during pretreatment, and results from calcium ``addback`` experiments supported the observation that calcium adversely affected coal reactivity at low severity reaction conditions. Model compound studies using benzyl phenyl ether demonstrated that calcium cations catalyzed retrogressive reactions, inhibited hydrogenation reactions at low severity reaction conditions, and were more active at higher reaction temperatures. Based on kinetic data, mechanisms for hydrogenation-based inhibition and base-catalyzed retrogressive reactions are proposed. The base-catalyzed retrogressive reactions are shown to occur via a hydrogen abstraction mechanism where hydrogenation inhibition reactions are shown to take place via a surface quenching mechanism.

  8. Estimate of the optimum weight ratio in zero-valent iron/pumice granular mixtures used in permeable reactive barriers for the remediation of nickel contaminated groundwater.

    PubMed

    Calabrò, P S; Moraci, N; Suraci, P

    2012-03-15

    This paper presents the results of laboratory column tests aimed at defining the optimum weight ratio of zero-valent iron (ZVI)/pumice granular mixtures to be used in permeable reactive barriers (PRBs) for the removal of nickel from contaminated groundwater. The tests were carried out feeding the columns with aqueous solutions of nickel nitrate at concentrations of 5 and 50 mg/l using three ZVI/pumice granular mixtures at various weight ratios (10/90, 30/70 and 50/50), for a total of six column tests; two additional tests were carried out using ZVI alone. The most successful compromise between reactivity (higher ZVI content) and long-term hydraulic performance (higher Pumice content) seems to be given by the ZVI/pumice granular mixture with a 30/70 weight ratio.

  9. Effects of initial iron corrosion rate on long-term performance of iron permeable reactive barriers: column experiments and numerical simulation.

    PubMed

    suk O, Jin; Jeen, Sung-Wook; Gillham, Robert W; Gui, Lai

    2009-01-26

    Column experiments and numerical simulation were conducted to test the hypothesis that iron material having a high corrosion rate is not beneficial for the long-term performance of iron permeable reactive barriers (PRBs) because of faster passivation of iron and greater porosity loss close to the influent face of the PRBs. Four iron materials (Connelly, Gotthart-Maier, Peerless, and ISPAT) were used for the column experiments, and the changes in reactivity toward cis-dichloroethene (cis-DCE) degradation in the presence of dissolved CaCO3 were evaluated. The experimental results showed that the difference in distribution of the accumulated precipitates, resulting from differences in iron corrosion rate, caused a difference in the migration rate of the cis-DCE profiles and a significant difference in the pattern of passivation, indicating a faster passivation in the region close to the influent end for the material having a higher corrosion rate. For the numerical simulation, the accumulation of secondary minerals and reactivity loss of iron were coupled using an empirically-derived relationship that was incorporated into a multi-component reactive transport model. The simulation results provided a reasonable representation of the evolution of iron reactivity toward cis-DCE treatment and the changes in geochemical conditions for each material, consistent with the observed data. The simulations for long-term performance were also conducted to further test the hypothesis and predict the differences in performance over a period of 40 years under typical groundwater conditions. The predictions showed that the cases of higher iron corrosion rates had earlier cis-DCE breakthrough and more reduction in porosity starting from near the influent face, due to more accumulation of carbonate minerals in that region. Therefore, both the experimental and simulation results appear to support the hypothesis and suggest that reactivity changes of iron materials resulting from

  10. Nitrate Biogeochemistry and Reactive Transport in California Groundwater: LDRD Final Report

    SciTech Connect

    Esser, B K; Beller, H; Carle, S; Cey, B; Hudson, G B; Leif, R; LeTain, T; Moody-Bartel, C; Moore, K; McNab, W; Moran, J; Tompson, A

    2006-02-24

    Nitrate is the number one drinking water contaminant in the United States. It is pervasive in surface and groundwater systems,and its principal anthropogenic sources have increased dramatically in the last 50 years. In California alone, one third of the public drinking-water wells has been lost since 1988 and nitrate contamination is the most common reason for abandonment. Effective nitrate management in groundwater is complicated by uncertainties related to multiple point and non-point sources, hydrogeologic complexity, geochemical reactivity, and quantification of denitrification processes. In this paper, we review an integrated experimental and simulation-based framework being developed to study the fate of nitrate in a 25 km-long groundwater subbasin south of San Jose, California, a historically agricultural area now undergoing rapid urbanization with increasing demands for groundwater. The modeling approach is driven by a need to integrate new and archival data that support the hypothesis that nitrate fate and transport at the basin scale is intricately related to hydrostratigraphic complexity, variability of flow paths and groundwater residence times, microbial activity, and multiple geochemical reaction mechanisms. This study synthesizes these disparate and multi-scale data into a three-dimensional and highly resolved reactive transport modeling framework.

  11. Nondestructive reactivation of chemical protective garments. Final report, June 1985-July 1989

    SciTech Connect

    Chang, K.W.; Chang, S.Y.; Klemperer, E.

    1995-12-01

    In the near future, chemical protective combat uniforms may be worn by Army personnel on a continuous basis. Activated carbon, the operative component, has diminished capacity for sorbing chemical agents after it has been exposed to dirt, sweat, cigarette smoke, engine exhaust, petroleum products and numerous other elements routinely present in the battlefield environment. This report summarizes the development of two nondestructive methods for cleaning and reactivating soiled chemical protective garments. Complete reactivation was achieved when the aqueous i-propanol iodine displacement method of Manes, which removed all but pure hydrocarbon oil soils from the current overgarment Type III foam or Kynol activated carbon fiber material, was applied in nonaqueous solvent. Subsequently, a nonaqueous solvent method that requires less handling was chosen in designing a truck-mounted system. It features non-agitative flow of methylene chloride and methanol around the chemical-protective garments suspended between ultrasonic transducers. Both methods restore full sorptivity to the Type III foam liner. There is a one-time 10% loss of activated carbon without any loss of sorptivity. The volatile solvents are more easily removed, and can be economically recovered. Overall features of a mobile unit have been sketched.

  12. Carbon reactivation by externally-fired rotary kiln furnace. Final report Oct 75-Jan 78

    SciTech Connect

    Chen, C.; Directo, L.S.

    1980-08-01

    An externally-fired rotary kiln furnace system has been evaluated for cost-effectiveness in carbon reactivation at the Pomona Advanced Wastewater Treatment Research Facility. The pilot scale rotary kiln furnace was operated within the range of 682 kg/day (1,500 lb/day) to 909 kg/day (2,000 lb/day). The rotary kiln furnace was found to be as effective as the multiple hearth furnace in reactivating the exhausted granular activated carbon. The operating and maintenance of the rotary kiln system required less operator skill than the multiple hearth furnace system. However, the corrosion rate was higher in the rotary tube than in the multiple hearth furnace. Cost estimates based on a typical regeneration capacity of 182 kg/hr (400 lb/hr) have been made for both rotary kiln and multiple hearth furnace systems. These indicate that the capital cost for the multiple hearth furnace is about two times that of the rotary kiln furnace. The operation and maintenance costs for both furnace systems are similar. The overall process costs for the multiple hearth and rotary kiln furnace systems are estimated to be 33.2 cents/kg (15.1 cents/lb) of carbon regenerated and 29.2 cents/kg (13.3 cents/lb) of carbon regenerated, respectively.

  13. Reactive ion etching of sputtered silicon carbide and tungsten thin films for device applications. Final report

    SciTech Connect

    Pan, W.S.; Steck, A.J.

    1989-01-01

    For high-temperature processing and device applications, refractory materials, such as silicon carbide (SiC) and tungsten (W), are actively considered or evaluated as the basic semiconductor and metallization materials for future generations of integrated circuits. In order to pattern fine lines in SiC and W thin films, a selective and anisotropic etching technique needs to be developed for future device applications. Therefore, the etching process including basic mechanisms and process requirement have been chosen as the overall research goals of this project. Reactive ion etching (RIE) of SiC thin films in a variety of fluorinated gas plasmas, such as SF{sub 6}, CBrF{sub 3} and CHF{sub 3} mixed with oxygen was investigated in depth. The best anisotropic profile was observed by using CHF{sub 3} gas in the RIE mode. A typical DC bias, -300V, is concluded from etching experiments to determine the dependence of SiC etch rate and physical reaction under RIE mode. Reactive ion etching of tungsten (W) thin film was also investigated by using the different fluorinated gas plasmas, such as CF{sub 4}, SF{sub 6}, CBrF{sub 3} and CHF{sub 3} mixed with oxygen. The obtaining of anisotropic etching profiles in W etching was suggested and the mechanisms were also studied.

  14. Multilayered thermal barrier coatings by CVD. Final report, September 1996--February 1997

    SciTech Connect

    Fortini, A.J.; Heng, S.; Sherman, A.J.

    1997-05-01

    Turbine engine component life is currently limited by creep, creep-rupture, oxidation/corrosion, and thermomechanical fatigue. The use of protective coatings, such as nickel-chromium-aluminum-yttrium (NiCrAlY) and more recently platinum aluminides and various thermal barrier coatings (TBCs), has enabled higher temperatures and longer component life to be achieved, but component life and temperature capability still limit obtainable engine operating efficiency. Reduction in component temperature through the development and use of improved TBCs can dramatically extend component life, or conversely, allow higher operating temperatures to be used at constant component life. Additionally, lowering oxygen diffusion through the TBC will increase the life of the TBC itself, and reduce or eliminate oxidation and corrosion of the bondcoat and underlying component structure. Extension of TBC technology to increasingly complicated combustor, blade, and vane geometries and cooling passages requires improved application methods. In this project, Ultramet developed and demonstrated the chemical vapor deposition (CVD) of bondcoats and multilayered TBCs. Analytical modeling to quantify performance improvement predicted a 40--80 C drop in turbine blade temperature through the use of these coatings. In addition, burner rig oxidation and salt spray corrosion testing were performed on a coated blade.

  15. Adsorption And Simultaneous Dechlorination Of PCBs On GAC/Fe/Pd: Mechanistic Aspects And Reactive Capping Barrier Concept

    EPA Science Inventory

    There are many concerns and challenges in current remediation strategies for sediments contaminated with polychlorinated biphenyls (PCBs). Our efforts have been geared toward the development of granular activated carbon (GAC) impregnated with reactive iron/palladium (Fe/Pd) bime...

  16. DNA Damage and Reactive Nitrogen Species are Barriers to Vibrio cholerae Colonization of the Infant Mouse Intestine

    PubMed Central

    Davies, Bryan W.; Bogard, Ryan W.; Dupes, Nicole M.; Gerstenfeld, Tyler A. I.; Simmons, Lyle A.; Mekalanos, John J.

    2011-01-01

    Ingested Vibrio cholerae pass through the stomach and colonize the small intestines of its host. Here, we show that V. cholerae requires at least two types of DNA repair systems to efficiently compete for colonization of the infant mouse intestine. These results show that V. cholerae experiences increased DNA damage in the murine gastrointestinal tract. Agreeing with this, we show that passage through the murine gut increases the mutation frequency of V. cholerae compared to liquid culture passage. Our genetic analysis identifies known and novel defense enzymes required for detoxifying reactive nitrogen species (but not reactive oxygen species) that are also required for V. cholerae to efficiently colonize the infant mouse intestine, pointing to reactive nitrogen species as the potential cause of DNA damage. We demonstrate that potential reactive nitrogen species deleterious for V. cholerae are not generated by host inducible nitric oxide synthase (iNOS) activity and instead may be derived from acidified nitrite in the stomach. Agreeing with this hypothesis, we show that strains deficient in DNA repair or reactive nitrogen species defense that are defective in intestinal colonization have decreased growth or increased mutation frequency in acidified nitrite containing media. Moreover, we demonstrate that neutralizing stomach acid rescues the colonization defect of the DNA repair and reactive nitrogen species defense defective mutants suggesting a common defense pathway for these mutants. PMID:21379340

  17. Fundamental studies of reactive intermediates in homogeneous catalysis. Final technical report

    SciTech Connect

    1998-09-01

    The chief aims during the contract period were to design, construct and implement a new flowing afterglow-guided ion beam instrument for use in determining thermochemical properties of organometallic species pertinent to homogeneous catalysis, and to develop an electrospray ionization (ESI) source for the flowing afterglow-triple quadrupole apparatus for use in real-time analysis of reactive intermediates in catalytically active solutions. Both goals were achieved. In parallel with development of the guided ion beam and electrospray ionization experiments, the author used existing equipment to work on some of the problems outlined in the previous proposal, and to open up new research areas. A summary of research activities and publications acknowledging DOE support follows.

  18. FIELD TEST INSTRUCTION 100-NR-2 OPERABLE UNIT DESIGN OPTIMIZATION STUDY FOR SEQUESTRATION OF SR-90 SATURATED ZONE APATITE PERMEABLE REACTIVE BARRIER EXTENSION

    SciTech Connect

    BOWLES NA

    2010-10-06

    The objective of this field test instruction is to provide technical guidance for aqueous injection emplacement of an extension apatite permeable reactive barrier (PRE) for the sequestration of strontium-90 (Sr-90) using a high concentration amendment formulation. These field activities will be conducted according to the guidelines established in DOE/RL-2010-29, 100-NR-2 Design Optimization Study, hereafter referred to as the DOS. The DOS supports the Federal Facility Agreement Consent Order (EPA et al., 1989), Milestone M-16-06-01, and 'Complete Construction of a Permeable Reactive Barrier at 100-N.' Injections of apatite precursor chemicals will occur at an equal distance intervals on each end of the existing PRE to extend the PRB from the existing 91 m (300 ft) to at least 274 m (900 ft). Field testing at the 100-N Area Apatite Treatability Test Site, as depicted on Figure 1, shows that the barrier is categorized by two general hydrologic conceptual models based on overall well capacity and contrast between the Hanford and Ringold hydraulic conductivities. The upstream portion of the original barrier, shown on Figure 1, is characterized by relatively low overall well specific capacity. This is estimated from well development data and a lower contrast in hydraulic conductivity between the Hanford formation and Ringold Formations. Comparison of test results from these two locations indicate that permeability contrast between the Hanford formation and Ringold Formation is significantly less over the upstream one-third of the barrier. The estimated hydraulic conductivity for the Hanford formation and Ringold Formation over the upstream portion of the barrier based on observations during emplacement of the existing 91 m (300 ft) PRB is approximately 12 and 10 m/day (39 and 32 ft/day), respectively (PNNL-17429). However, these estimates should be used as a rough guideline only, as significant variability in hydraulic conductivity is likely to be observed in the

  19. Effect of reagent access on the reactivity of coals. Final report. [Maleic anhydride; dialkylmaleates

    SciTech Connect

    Larsen, J.W.

    1983-04-01

    The objective of this work is to determine the extent to which the mass transport of reagents into solid coals limits the reactivity of those coals. The purpose of task one is to determine the effect of reagent access on the acid catalyzed depolymerization of coals using phenols and/or alkyl phenyl ethers. For task two, the purpose is to determine the effect of coal swelling on its rate of reaction with a dienophile. Work on depolymerization of coals in hot, acidic phenol has been completed. The conclusion is that due to incomplete depolymerization, the complications of competing Friedel-Crafts alkylation, and the condensation reactions of the solvent, the depolymerization of coals in hot, acidic phenol is not a useful technique for solubilizing coals for structural investigations. In task two, the rate of the Diels-Alder reaction between bituminous coals and maleic anhydride was found to be diffusion controlled. The observations of simple Fickian diffusion and reaction rate constants much slower than the Diels-Alder reaction of maleic anhydride and anthracene have no other reasonable explanation than rate limiting mass transport. The diffusion rates were found to be independent of the degree of solvent swelling of the coal. In addition, the dependence of the observed rates on temperature and the size of the dienophile were measured. Results obtained using a series of dialkylmaleates are presented. Size was found to play only a small role as long as the reagent is planar. 2 tables.

  20. SPATIAL AND TEMPORAL TRENDS IN GROUNDWATER CHEMISTRY AND PRECIPITATE FORMATION AT THE ELIZABETH CITY PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    Accumulation of mineral precipitates and microbial biomass are key factors that impact the long-term performance of PRBs. Both processes can impact remedial performance by affecting zero-valent iron reactivity and permeability. Results will be presented from solid-phase and gro...

  1. Simulation Tool for Dielectric Barrier Discharge Plasma Actuators at Atmospheric and Sub-Atmospheric Pressures: SBIR Phase I Final Report

    NASA Technical Reports Server (NTRS)

    Likhanskii, Alexandre

    2012-01-01

    This report is the final report of a SBIR Phase I project. It is identical to the final report submitted, after some proprietary information of administrative nature has been removed. The development of a numerical simulation tool for dielectric barrier discharge (DBD) plasma actuator is reported. The objectives of the project were to analyze and predict DBD operation at wide range of ambient gas pressures. It overcomes the limitations of traditional DBD codes which are limited to low-speed applications and have weak prediction capabilities. The software tool allows DBD actuator analysis and prediction for subsonic to hypersonic flow regime. The simulation tool is based on the VORPAL code developed by Tech-X Corporation. VORPAL's capability of modeling DBD plasma actuator at low pressures (0.1 to 10 torr) using kinetic plasma modeling approach, and at moderate to atmospheric pressures (1 to 10 atm) using hydrodynamic plasma modeling approach, were demonstrated. In addition, results of experiments with pulsed+bias DBD configuration that were performed for validation purposes are reported.

  2. Combining field methods and numerical modeling to characterize the flow of a Sr-90 plume through a permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Hoppe, J.; Bain, J.; Lee, D. R.; Jeen, S.; Blowes, D.

    2012-12-01

    In 1998, a passive remediation system known as the Wall-and-Curtain was installed at the Chalk River Laboratories in Ontario, Canada, to prevent a Sr-90 plume present in the lower part of a 12 m thick aquifer from discharging into a nearby swamp. To improve knowledge of the variability of aquifer hydraulic conductivities and groundwater velocities, slug tests and borehole dilution tests were conducted in isolated intervals upgradient of the Wall-and-Curtain using stainless steel drive point piezometers. The measurements from the field study were combined with previous characterization of the hydrogeology of the site to develop a three dimensional physical flow model. The numerical computer code HydroGeoSphere was used to provide an approximate representation of groundwater flow in the aquifer and through the Wall-and-Curtain. Developing a quantitative description of the groundwater flow system is an essential step in understanding the fate of the Sr-90 plume in the Wall-and-Curtain and for conducting meaningful geochemical reactive transport simulations. The model was calibrated by comparing simulated and observed hydraulic heads across the site. The results from the field tests were compared with groundwater velocities simulated by the numerical model. The model shows good agreement with the observed heads and acceptable agreement with the field estimates of groundwater velocities, while also showing the deficiencies of the model in accurately simulating flow in the boundary regions of the domain. Ongoing work focuses on the detailed geochemical characterization of the aquifer and the reactive material (i.e., clinoptilolite), which will be used to construct a geochemical reactive transport model to evaluate the potential longevity of the reactive zone in the Wall-and-Curtain.

  3. Nonlocal transport of chemically reactive, degradable species in heterogeneous porous media. Final report

    SciTech Connect

    Cushman, J.H.

    1998-07-30

    One of the most significant challenges facing environmental engineers and scientists is predicting the movement and degradation of chemicals in hierarchical porous media. The distribution of subsurface properties is poorly known because of the inaccessibility of the subsurface environment and the random nature of the geologic deposition process. In addition, the subsurface often possesses distinct physical, chemical and biological hierarchies, which complicates the ability to successfully characterize and thus predict property distributions and processes with information from a limited number of sample locations over a limited number of scales. Knowledge of the spatial structure of microbial populations and activities and the dynamic environmental factors that control this spatial structure are important in characterizing sites for remediation and disposal, and for the ability to effectively deliver nutrients to promote degradation and stabilization. To do so effectively requires a correct theoretical formulation of the problem, implementation of this formulation for predictive purposes, and even more importantly knowledge of what should be measured and how and when to measure it. The contents of this report is as follows: (Section 2) statement of goals, (Section 3) development of nonlocal models for chemical transport with uncertainty in biological, physical and chemical data, (Section 4) a discussion of molecular-scale phenomena of relevance to adsorption and flow in nanoporous materials such as clays, (Section 5) meso and macroscale models of flow in, and deformation of, clays, (Section 6) collaborative efforts with DOE labs, (Section 7) P.I. awards, (Section 8) publications resulting from the research efforts supported through this grant, and finally students supported under this grant.

  4. A permeable reactive barrier (PRB) media sequence for the remediation of heavy metal and hydrocarbon contaminated water: A field assessment at Casey Station, Antarctica.

    PubMed

    Statham, Tom M; Stark, Scott C; Snape, Ian; Stevens, Geoffrey W; Mumford, Kathryn A

    2016-03-01

    A field trial was conducted at Casey Station, Antarctica to assess the suitability of a permeable reactive barrier (PRB) media sequence for the remediation of sites containing both hydrocarbon and heavy metal contamination. An existing PRB was modified to assess a sequence consisting of three sections: (i) Nutrient release/hydrocarbon sorption using ZeoPro™ and granular activated carbon; (ii) Phosphorus and heavy metal capture by granular iron and sand; (iii) Nutrient and excess iron capture by zeolite. The media sequence achieved a greater phosphorus removal capacity than previous Antarctic PRB configurations installed on site. Phosphorus concentrations were reduced during flow through the iron/sand section and iron concentrations were reduced within the zeolite section. However, non-ideal flow was detected during a tracer test and supported by analysis of media and liquid samples from the second summer of operation. Results indicate that the PRB media sequence trialled might be appropriate for other locations, especially less environmentally challenging contaminated sites.

  5. Performance of a zerovalent iron reactive barrier for the treatment of arsenic in groundwater: Part 2. Geochemical modeling and solid phase studies

    SciTech Connect

    Beak, Douglas G.; Wilkin, Richard T.

    2009-06-12

    Arsenic uptake processes were evaluated in a zerovalent iron reactive barrier installed at a lead smelting facility using geochemical modeling, solid-phase analysis, and X-ray absorption spectroscopy techniques. Aqueous speciation of arsenic is expected to play a key role in directing arsenic uptake processes. Geochemical modeling reveals contrasting pH-dependencies for As(III) and As(V) precipitation. At the moderately alkaline pH conditions typically encountered in zerovalent iron reactive barriers, As(III) is unlikely to precipitate as an oxide or a sulfide phase. Conversely, increasing pH is expected to drive precipitation of metal arsenates including ferrous arsenate. Bacterially mediated sulfate reduction plays an important role in field installations of granular iron. Neoformed iron sulfides provide surfaces for adsorption of oxyanion and thioarsenic species of As(III) and As(V) and are expected to provide enhanced arsenic removal capacity. X-ray absorption near edge structure (XANES) spectra indicate that arsenic is sequestered in the solid phase as both As(III) and As(V) in coordination environments with O and S. Arsenic removal in the PRB probably results from several pathways, including adsorption to iron oxide and iron sulfide surfaces, and possible precipitation of ferrous arsenate. Corrosion of granular iron appears to result in some As(III) oxidation to As(V) as the proportion of As(V) to As(III) in the solid phase is greater compared to influent groundwater. As(0) was not detected in the PRB materials. These results are broadly comparable to laboratory based studies of arsenic removal by zerovalent iron, but additional complexity is revealed in the field environment, which is largely due to the influence of subsurface microbiota.

  6. A ‘tissue model’ to study the barrier effects of living tissues on the reactive species generated by surface air discharge

    NASA Astrophysics Data System (ADS)

    He, Tongtong; Liu, Dingxin; Xu, Han; liu, Zhichao; Xu, Dehui; Li, Dong; Li, Qiaosong; Rong, Mingzhe; Kong, Michael G.

    2016-05-01

    Gelatin gels are used as surrogates of human tissues to study their barrier effects on incoming reactive oxygen and nitrogen species (RONS) generated by surface air discharge. The penetration depth of nitrite into gelatin gel is measured in real time during plasma treatment, and the permeabilities of nitrite, nitrate, O3 and H2O2 through gelatin gel films are quantified by measuring their concentrations in the water underneath such films after plasma treatment. It is found that the penetration speed of nitrite increases linearly with the mass fraction of water in the gelatin gels, and the permeabilities of nitrite and O3 are comparably smaller than that for H2O2 and nitrate due to differences in their chemistry in gelatin gels. These results provide a quantitative basis to estimate the penetration processes of RONS in human tissues, and they also confirm that the composition of RONS is strongly dependent on the tissue depth and the plasma treatment time. A small electric field of up to 20 V cm-1 can greatly reduce the barrier effects of the tissue model regardless of their directions, for which the underlying mechanism is unclear. However, the electric field force on the objective RONS should not be the dominant mechanism.

  7. Point-of-care C reactive protein for the diagnosis of lower respiratory tract infection in NHS primary care: a qualitative study of barriers and facilitators to adoption

    PubMed Central

    Huddy, Jeremy R; Ni, Melody Z; Barlow, James; Hanna, George B

    2016-01-01

    Objectives Point-of-care (POC) C reactive protein (CRP) is incorporated in National Institute of Health and Care Excellence (NICE) guidelines for the diagnosis of pneumonia, reduces antibiotic prescribing and is cost effective. Aim To determine the barriers and facilitators to adoption of POC CRP testing in National Health Service (NHS) primary care for the diagnosis of lower respiratory tract infection. Design The study followed a qualitative methodology based on grounded theory. The study was undertaken in 2 stages. Stage 1 consisted of semistructured interviews with 8 clinicians from Europe and the UK who use the test in routine practice, and focused on their subjective experience in the challenges of implementing POC CRP testing. Stage 2 was a multidisciplinary-facilitated workshop with NHS stakeholders to discuss barriers to adoption, impact of adoption and potential adoption scenarios. Emergent theme analysis was undertaken. Participants Participants included general practitioners (including those with commissioning experience), biochemists, pharmacists, clinical laboratory scientists and industry representatives from the UK and abroad. Results Barriers to the implementation of POC CRP exist, but successful adoption has been demonstrated abroad. Analysis highlighted 7 themes: reimbursement and incentivisation, quality control and training, laboratory services, practitioner attitudes and experiences, effects on clinic flow and workload, use in pharmacy and gaps in evidence. Conclusions Successful adoption models from the UK and abroad demonstrate a distinctive pattern and involve collaboration with central laboratory services. Incorporating antimicrobial stewardship into quality improvement frameworks may incentivise adoption. Further research is needed to develop scaling-up strategies to address the resourcing, clinical governance and economic impact of widespread NHS implementation. PMID:26940107

  8. Barriers to Youth Employment. Final Report, 7/1/80-6/30/81. Vocational-Technical Education Research Report.

    ERIC Educational Resources Information Center

    Passmore, David Lynn

    Provided in this report are a number of empirical and conceptual papers dealing with barriers to youth employment. The first paper, "Barriers to Youth Employment: A Review," contains a summary of more than 100 reports on causes of youth employability problems and poses several alternative strategies for formulation of youth labor market policy.…

  9. CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 2 LONG-TERM MONITORING OF PRBS: SOIL AND GROUND WATER SAMPLING

    EPA Science Inventory

    This report discusses soil and ground-water sampling methods and procedures used to evaluate the long-term performance of permeable reactive barriers (PRBS) at two sites, Elizabeth City, NC, and the Denver Federal Center near Lakewood, CO. Both PRBs were installed in 1996 and hav...

  10. Field study of moisture damage in walls insulated without a vapor barrier. Final report for the Oregon Department of Energy

    SciTech Connect

    Tsongas, G.A.

    1980-05-01

    Considerable uncertainty has existed over whether or not wall insulation installed without a vapor barrier causes an increased risk of moisture damage (wood decay) within walls. This report describes the results of one of the first major studies in the country aimed at finding out if such a moisture problem really exists. The exterior walls of a total of 96 homes in Portland, Oregon were opened, of which 70 had retrofitted insulation and 26 were uninsulated and were a control group. The types of insulation included urea-formaldehyde foam (44), mineral wool (16), and cellulose (10). In each opened wall cavity the moisture content of wood was measured and insulation and wood samples were taken for laboratory analysis of moisture content and for the determination of the presence of absence of decay fungi. Foam shrinkage was also measured. To evaluate the possible influence of the relative air tightness of the homes, fan depressurization tests were run using a door blower unit. The field and laboratory test results indicating the lack of a moisture damage problem in existing homes with wood siding in climates similar to that of western Oregon are described along with results of a statistical analysis of the data. Related problems of interest to homeowners and insulation installers are noted. The standard operating procedures used throughout the study are discussed, including the home selection process, quantitative and qualitative techniques used to identify wall locations with the highest moisture content, wall opening and data/sample collection methodology, laboratory analysis of samples, data processing and analysis, and applicability of the results. Recommendations for furutre tests are made. Finally, the potential and desirability for future retrofitting of wall insulation is explored.

  11. Reactive coating of soybean oil-based polymer on nanofibrillated cellulose film for water vapor barrier packaging.

    PubMed

    Lu, Peng; Xiao, Huining; Zhang, Weiwei; Gong, Glen

    2014-10-13

    Nanofibrillated cellulose (NFC) easily forms a high strength film but is unable to withstand the influence of water vapor when used in high moisture situations. The water vapor transmission rate (WVTR) of a NFC film was as high as 5088 g/m(2)24h (38 °C, 90% RH). The addition of beeswax latex in a NFC casting film (NFX) lowered the WVTR to 3918 g/m(2)24h. To further reduce the WVTR, a coating agent comprised of acrylated epoxidized soybean oil (AESO) and 3-aminopropyltriethoxysilane (APTS) was applied onto the NFX film using a rod coater. A combination of the suitable AESO/APTS ratio, initiator dosing, curing time and temperature could reduce the WVTR to 188 g/m(2) 24h when the coat weight was 5 g/m(2). Moreover, the coated NFX film was highly hydrophobic along with the improved transparency and thermal stability. This biodegradable polymer-coated NFC film can be used as potential packaging barrier in certain areas.

  12. Variation in structure of proteins by adjusting reactive oxygen and nitrogen species generated from dielectric barrier discharge jet

    PubMed Central

    Park, Ji Hoon; Kim, Minsup; Shiratani, Masaharu; Cho, Art. E.; Choi, Eun Ha; Attri, Pankaj

    2016-01-01

    Over the last few years, the variation in liquid chemistry due to the development of radicals generated by cold atmospheric plasma (CAP) has played an important role in plasma medicine. CAP direct treatment or CAP activated media treatment in cancer cells shows promising anticancer activity for both in vivo and in vitro studies. However, the anticancer activity or antimicrobial activity varies between plasma devices due to the different abilities among plasma devices to generate the reactive oxygen and nitrogen species (RONS) at different ratios and in different concentrations. While the generation of RONS depends on many factors, the feeding gas plays the most important role among the factors. Hence, in this study we used different compositions of feeding gas while fixing all other plasma characteristics. We used Ar, Ar-O2 (at different ratios), and Ar-N2 (at different ratios) as the working gases for CAP and investigated the structural changes in proteins (Hemoglobin (Hb) and Myoglobin (Mb)). We then analyzed the influence of RONS generated in liquid on the conformations of proteins. Additionally, to determine the influence of H2O2 on the Hb and Mb structures, we used molecular dynamic simulation. PMID:27779212

  13. Variation in structure of proteins by adjusting reactive oxygen and nitrogen species generated from dielectric barrier discharge jet

    NASA Astrophysics Data System (ADS)

    Park, Ji Hoon; Kim, Minsup; Shiratani, Masaharu; Cho, Art. E.; Choi, Eun Ha; Attri, Pankaj

    2016-10-01

    Over the last few years, the variation in liquid chemistry due to the development of radicals generated by cold atmospheric plasma (CAP) has played an important role in plasma medicine. CAP direct treatment or CAP activated media treatment in cancer cells shows promising anticancer activity for both in vivo and in vitro studies. However, the anticancer activity or antimicrobial activity varies between plasma devices due to the different abilities among plasma devices to generate the reactive oxygen and nitrogen species (RONS) at different ratios and in different concentrations. While the generation of RONS depends on many factors, the feeding gas plays the most important role among the factors. Hence, in this study we used different compositions of feeding gas while fixing all other plasma characteristics. We used Ar, Ar-O2 (at different ratios), and Ar-N2 (at different ratios) as the working gases for CAP and investigated the structural changes in proteins (Hemoglobin (Hb) and Myoglobin (Mb)). We then analyzed the influence of RONS generated in liquid on the conformations of proteins. Additionally, to determine the influence of H2O2 on the Hb and Mb structures, we used molecular dynamic simulation.

  14. Granular activated carbon adsorption and fluid-bed reactivation at Manchester, New Hampshire. Final report Mar 77-Apr 82

    SciTech Connect

    Kittredge, D.; Beaurivage, R.; Paris, D.

    1983-10-01

    Treatment performances of virgin and reactivated GAC were evaluated during three reactivation-exhaustion cycles by measuring total organic carbon (TOC), trihalomethanes (THM), and trihalomethane formation potential (THMFP). GAC adsorptive capacity was measured using traditional test parameters including iodine number, molasses decolorizing index, BET, and pore-size distribution. The GAC was reactivated on-site by a 500 lb/hr fluidized-bed unit. Results of this study demonstrated that onsite reactivation was a cost-effective method of restoring the adsorptive properties of spent GAC. During a 10-month period, more than 1.8 million lb of GAC was reactivated at a total cost of less than 22 cents/lb as compared with a delivered cost of 61.5 cents/lb for virgin GAC. The average total carbon loss resulting from transportation and reactivation was 11.5% by volume.

  15. Measurement of the atmospheric reactivity of emissions from gasoline and alternative-fueled vehicles: Assessment of available methodologies. Part 1. Indoor smog chamber study of reactivity. Part 2. Assessment of airtrak as a reactivity analyzer. Final report for the second year, March 1, 1994-February 28, 1995

    SciTech Connect

    Kelly, N.A.; Wang, P.; Hurley, M.D.; Japar, S.M.; Chang, T.

    1996-06-13

    During the second year of the GM smog chamber study of incremental reactivity the authors performed smog chamber experiments to measure three important properties of incremental reactivity. First, they challenged the linear relationship between the Carter factors and the chamber-measured reactivities found during the first-year smog chamber study. Second, they compared the predicted and measured smog formation in simple and complex mixtures. Third, they measured the incremental reactivities of three hydrocarbons (n-butane, propene, and p-xylene) as well as the urban-surrogate mixture at three different temperatures, 22 deg C, 32 deg C (the default), and 42 deg C, to determine how temperature affects both the absolute and the relative reactivity. Finally, they conducted experiments in which the incremental reactivity of NO2 was measured in order to test the Integrated Empirical Rate (IER) model.

  16. Final « pop-up » structural reactivation of the internal part of an orogenic wedge: west-central Pyrenees

    NASA Astrophysics Data System (ADS)

    Meresse, F.; Jolivet, M.; Labaume, P.; Teixell, A.

    2009-04-01

    late exhumation stage associated with the tectonic (re)activation of north-vergent thrusts in the northern part of the Axial Zone. Similarly, results from the southern flank of the Axial Zone and the northern part of the Jaca basin suggest a denudation age around 18 Ma (Meresse et al., this volume), which may be linked to out-of-sequence tectonic movements on a south-vergent basement thrust (Bielsa thrust, Jolivet et al., 2007). In conclusion, thermochronological data reveal an Early Miocene "pop-up" exhumation of the internal parts of the Pyrenean wedge, which also shows that the Pyrenean compressional deformation ended later than the generally accepted Aquitanian age deduced from tectonics-sedimentation relationships. This late exhumation was achieved through out-of-sequence (re)activation of hinterland structures linked to a final internal thickening stage in the orogenic prism.

  17. Reactivity of young chars via energetic distribution measurements. Final report, 1 September 1990--31 December 1994

    SciTech Connect

    Calo, J.M.; Zhang, L.; Lu, W.; Lilly, W.D.

    1996-01-01

    We have developed what we believe to be the very first, a priori, correlation/prediction technique for the gasification reactivity of coal char. With this method the gasification reactivity of a coal char as a function of temperature can be correlated using the data from a temperature programmed desorption (TPD) experiment following gasification under conditions where the reactivity is controlled by the thermal desorption of oxygen surface complexes formed during gasification. The current project was directed at extending and developing related techniques for the characterization and prediction/correlation of the reactivity of the ``young`` chars to CO{sub 2} and steam. Of particular interest was mapping of the reactivity behavior of the resultant chars, as revealed by the energetic heterogeneity of the complexes with char preparation conditions.

  18. Microbially mediated clinoptilolite regeneration in a multifunctional permeable reactive barrier used to remove ammonium from landfill leachate contamination: laboratory column evaluation.

    PubMed

    Nooten, Thomas Van; Diels, Ludo; Bastiaens, Leen

    2010-05-01

    This study focuses on multifunctional permeable reactive barrier (multibarrier) technology, combining microbial degradation and abiotic ion exchange processes for removal of ammonium from landfill leachate contamination. The sequential multibarrier concept relies on the use of a clinoptilolite-filled buffer compartment to ensure a robust ammonium removal in case of temporary insufficient microbial activities. An innovative strategy was developed to allow in situ clinoptilolite regeneration. Laboratory-scale clinoptilolite-filled columns were first saturated with ammonium, using real landfill leachate as well as synthetic leachates as feed media. Other inorganic metal cations, typically present in landfill leachate, had a detrimental influence on the ammonium removal capacity by competing for clinoptilolite exchange sites. On the other hand, the metals had a highly favorable impact on regeneration of the saturated material. Feeding the columns with leachate deprived from ammonium (e.g., by microbial nitrification in an upgradient compartment), resulted in a complete release of the previously sorbed ammonium from the clinoptilolite, due to exchange with metal cations present in the leachate. The released ammonium is then available for microbial consumption in a downgradient compartment. The regeneration process resulted in a slightly increased ammonium exchange capacity afterward. The described strategy throws a new light on sustainable use of sorption materials for in situ groundwater remediation, by avoiding the need for material replacement and the use of external chemical regenerants.

  19. Removal of ammonium-nitrogen from groundwater using a fully passive permeable reactive barrier with oxygen-releasing compound and clinoptilolite.

    PubMed

    Huang, Guoxin; Liu, Fei; Yang, Yingzhao; Deng, Wei; Li, Shengpin; Huang, Yuanying; Kong, Xiangke

    2015-05-01

    A novel fully passive permeable reactive barrier (PRB) with oxygen-releasing compound (ORC) and clinoptilolite was proposed for the removal of ammonium-nitrogen from groundwater. The PRB involves a combination of oxygen release, biological nitrification, ion exchange, and bioregeneration. A pilot-scale performance comparison experiment was carried out employing three parallel columns to assess the proposed PRB. The results showed that the PRB achieved nearly complete [Formula: see text] depletion (>99%). [Formula: see text] of 5.23-10.88 mg/L was removed, and [Formula: see text] of <1.93 mg/L and [Formula: see text] of 2.03-19.67 mg/L were generated. Ion exchange and biological nitrification both contributed to [Formula: see text] removal, and the latter played a dominant role under the condition of sufficient oxygen. Biological nitrification favored a delay in sorption saturation and a release of exchange sites. The ORC could sufficiently, efficiently supply oxygen for approximately 120 pore volumes. The clinoptilolite ensured a robust [Formula: see text] removal in case of temporary insufficient biological activities. No external alkalinity sources had to be supplied and no inhibition of aerobic metabolism occurred. The ceramicite had a negligible effect on the biomass growth. Based on the research findings, a full-scale continuous wall PRB was installed in Shenyang, China in 2012.

  20. Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers in a Sand and Gravel Aquifer, Cape Cod, Massachusetts, 1997-2000

    USGS Publications Warehouse

    Savoie, Jennifer G.; Kent, Douglas B.; Smith, Richard L.; LeBlanc, Denis R.; Hubble, David W.

    2004-01-01

    Two experimental permeable reactive barriers (PRBs) of granular zero-valent iron were emplaced in the path of a tetrachloroethene plume (the Chemical Spill-10 plume) at the Massachusetts Military Reservation, Cape Cod, Massachusetts, in June 1998. The goal of the field experiment was to achieve emplacement of a granular-iron PRB deeper than attempted before. The PRBs were expected to create a reducing environment and degrade the tetrachloroethene by reductive dechlorination. The goal of the work presented in this report was to observe temporary and sustained changes to the ground-water chemistry downgradient from the PRBs. A hydraulic-fracturing method involving injection of the granular iron with a guar-biopolymer and enzyme slurry was used to install the parallel 30- to 33-foot-wide wall-shaped barriers at a depth of 82 to 113 feet below land surface. An acetic acid and enzyme mixture was subsequently injected in wells near the barriers to degrade the guar biopolymer. Prior to the emplacement, tetrachloroethene concentrations in the Chemical Spill-10 plume at the study area were as high as 250 micrograms per liter. Other water properties in the plume generally were similar to the properties of uncontaminated ground water in the area, which typically has dissolved oxygen concentrations of 250 to 375 micromoles per liter, pH of 5.5 to 6.0, and specific conductance of 60 to 90 microsiemens per centimeter. Water-quality samples were collected periodically from monitoring wells near the PRBs to determine how the emplacement of the granular-iron walls altered the ground-water quality. In addition, an automated well-sampling device measured temperature, specific conductance, pH, and dissolved oxygen every 1?4 days for 16 months in a well downgradient from the two parallel PRBs. Temporary increases (lasting about 5 to 6 months) in specific conductance were observed downgradient from the PRBs as a result of the sodium chloride, potassium carbonate, and other salts

  1. Effect of SiNx diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol–gel dip coating and reactive magnetron sputtering

    PubMed Central

    Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    Summary We investigate the effect of the thickness of the silicon nitride (SiNx) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol–gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiNx diffusion barrier. Increasing the thickness of the SiNx diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol–gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiNx barrier diffusion. The SiNx barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed. PMID:26665074

  2. Effect of SiN x diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol-gel dip coating and reactive magnetron sputtering.

    PubMed

    Ghazzal, Mohamed Nawfal; Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    We investigate the effect of the thickness of the silicon nitride (SiN x ) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol-gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiN x diffusion barrier. Increasing the thickness of the SiN x diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol-gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiN x barrier diffusion. The SiN x barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed.

  3. Remediation of the Highland Drive South Ravine, Port Hope, Ontario: Contaminated Groundwater Discharge Management Using Permeable Reactive Barriers and Contaminated Sediment Removal - 13447

    SciTech Connect

    Smyth, David; Roos, Gillian; Ferguson Jones, Andrea; Case, Glenn; Yule, Adam

    2013-07-01

    The Highland Drive South Ravine (HDSR) is the discharge area for groundwater originating from the Highland Drive Landfill, the Pine Street North Extension (PSNE) roadbed parts of the Highland Drive roadbed and the PSNE Consolidation Site that contain historical low-level radioactive waste (LLRW). The contaminant plume from these LLRW sites contains elevated concentrations of uranium and arsenic and discharges with groundwater to shallow soils in a wet discharge area within the ravine, and directly to Hunt's Pond and Highland Drive South Creek, which are immediately to the south of the wet discharge area. Remediation and environmental management plans for HDSR have been developed within the framework of the Port Hope Project and the Port Hope Area Initiative. The LLRW sites will be fully remediated by excavation and relocation to a new Long-Term Waste Management Facility (LTWMF) as part of the Port Hope Project. It is projected, however, that the groundwater contaminant plume between the remediated LLRW sites and HDSR will persist for several hundreds of years. At the HDSR, sediment remediation within Hunt's Ponds and Highland Drive South Creek, excavation of the existing and placement of clean fill will be undertaken to remove current accumulations of solid-phase uranium and arsenic associated with the upper 0.75 m of soil in the wet discharge area, and permeable reactive barriers (PRBs) will be used for in situ treatment of contaminated groundwater to prevent the ongoing discharge of uranium and arsenic to the area in HDSR where shallow soil excavation and replacement has been undertaken. Bench-scale testing using groundwater from HDSR has confirmed excellent treatment characteristics for both uranium and arsenic using permeable reactive mixtures containing granular zero-valent iron (ZVI). A sequence of three PRBs containing ZVI and sand in backfilled trenches has been designed to intercept the groundwater flow system prior to its discharge to the ground surface

  4. Testing to determine relationship between explosive-contaminated sludge components and reactivity. Final report, June 1985-January 1987

    SciTech Connect

    Kristoff, F.T.; Ewing, T.W.; Johnson, D.E.

    1987-01-31

    Explosives manufacture and ammunition load, assembly and pack (LAP) operations result in the generation of explosives-contaminated wastewater. Over the years, the Department of the Army has used lagoons for treatment of these wastewaters by evaporation/percolation. These lagoons contain the remaining explosives-contaminated waters and sludges are listed as hazardous wastes under Federal regulations promulgated under the Resource Conservation and Recovery Act (RCRA). The basis for this listing is the assumed explosive reactivity of these wastes if subjected to a strong initiating source or if heated under confinement. The objective of this study was to investigate and define the reactivity of explosive-contaminated soils to flame and shock as a function of explosive composition using the Bureau of Mines (BOM) Zero Gap (shock) and Deflagration to Detonation Transition (DDT flame) tests. The resultant technical data will be used to define the reactivity of explosive-contaminated soil on the basis of compositional analyses. Extensive testing was conducted to investigate and define the reactivity of explosive-contaminated soils to flame and shock stimuli. From these tests, it is also concluded that explosive-contaminated soils can be diluted with virgin soil to reduce the total explosive content of < or = 12% and result in a composition which is not reactive in the BOM flame and shock tests.

  5. Ammonium-nitrogen-contaminated groundwater remediation by a sequential three-zone permeable reactive barrier (multibarrier) with oxygen-releasing compound (ORC)/clinoptilolite/spongy iron: column studies.

    PubMed

    Huang, Guoxin; Liu, Fei; Yang, Yingzhao; Kong, Xiangke; Li, Shengpin; Zhang, Ying; Cao, Dejun

    2015-03-01

    A novel sequential permeable reactive barrier (multibarrier), composed of oxygen-releasing compound (ORC)/clinoptilolite/spongy iron zones in series, was proposed for ammonium-nitrogen-contaminated groundwater remediation. Column experiments were performed to: (1) evaluate the overall NH4(+)-N removal performance of the proposed multibarrier, (2) investigate nitrogen transformation in the three zones, (3) determine the reaction front progress, and (4) explore cleanup mechanisms for inorganic nitrogens. The results showed that NH4 (+)-N percent removal by the multibarrier increased up to 90.43 % after 21 pore volumes (PVs) at the influent dissolved oxygen of 0.68∼2.45 mg/L and pH of 6.76∼7.42. NH4(+)-N of 4.06∼10.49 mg/L was depleted and NOx(-)-N (i.e., NO3 (-)-N + NO2(-)-N) of 4.26∼9.63 mg/L was formed before 98 PVs in the ORC zone. NH4(+)-N of ≤4.76 mg/L was eliminated in the clinoptilolite zone. NOx(-)-N of 10.44∼12.80 mg/L was lost before 21 PVs in the spongy iron zone. The clinoptilolite zone length should be reduced to 30 cm. Microbial nitrification played a dominant role in NH4(+)-N removal in the ORC zone. Ion exchange was majorly responsible for NH4(+)-N elimination in the clinoptilolite zone. Chemical reduction and hydrogenotrophic denitrification both contributed to NOx(-)-N transformation, but the chemical reduction capacity decreased after 21 PVs in the spongy iron.

  6. The role of nano-sized manganese coatings on bone char in removing arsenic(V) from solution: Implications for permeable reactive barrier technologies.

    PubMed

    Liu, Jing; He, Lile; Dong, Faqin; Hudson-Edwards, Karen A

    2016-06-01

    Although the removal of arsenic(V) (As(V)) from solution can be improved by forming metal-bearing coatings on solid media, there has been no research to date examining the relationship between the coating and As(V) sorption performance. Manganese-coated bone char samples with varying concentrations of Mn were created to investigate the adsorption and desorption of As(V) using batch and column experiments. Breakthrough curves were obtained by fitting the Convection-Diffusion Equation (CDE), and retardation factors were used to quantify the effects of the Mn coatings on the retention of As(V). Uncoated bone char has a higher retention factor (44.7) than bone char with 0.465 mg/g of Mn (22.0), but bone char samples with between 5.02 mg/g and 14.5 mg/g Mn have significantly higher retention factors (56.8-246). The relationship between retardation factor (Y) and Mn concentration (X) is Y = 15.1 X + 19.8. Between 0.2% and 0.6% of the sorbed As is desorbed from the Mn-coated bone char at an initial pH value of 4, compared to 30% from the uncoated bone char. The ability of the Mn-coated bone char to neutralize solutions increases with increased amounts of Mn on the char. The results suggest that using Mn-coated bone char in Permeable Reactive Barriers would be an effective method for remediating As(V)-bearing solutions such as acid mine drainage.

  7. Analytical model for the design of in situ horizontal permeable reactive barriers (HPRBs) for the mitigation of chlorinated solvent vapors in the unsaturated zone

    NASA Astrophysics Data System (ADS)

    Verginelli, Iason; Capobianco, Oriana; Hartog, Niels; Baciocchi, Renato

    2017-02-01

    In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a second-order reaction rate constant. Furthermore, the model accounts for the HPRB lifetime as a function of the oxidant consumption by reaction with upward vapors and its progressive dissolution and leaching by infiltrating water. Simulation results by this new model closely replicate previous lab-scale tests carried out on trichloroethylene (TCE) using a HPRB containing a mixture of potassium permanganate, water and sand. In view of field applications, design criteria, in terms of the minimum HPRB thickness required to attenuate vapors at acceptable risk-based levels and the expected HPRB lifetime, are determined from site-specific conditions such as vapor source concentration, water infiltration rate and HPRB mixture. The results clearly show the field-scale feasibility of this alternative vapor mitigation system for the treatment of chlorinated solvents. Depending on the oxidation kinetic of the target contaminant, a 1 m thick HPRB can ensure an attenuation of vapor concentrations of orders of magnitude up to 20 years, even for vapor source concentrations up to 10 g/m3. A demonstrative application for representative contaminated site conditions also shows the feasibility of this mitigation system from an economical point of view with capital costs potentially somewhat lower than those of other remediation options, such as soil vapor extraction systems. Overall, based on the experimental and theoretical evaluation thus far, field-scale tests are warranted to verify the potential and cost-effectiveness of HPRBs for vapor mitigation control under various conditions of application.

  8. Potential artifacts in interpretation of differential breakthrough of colloids and dissolved tracers in the context of transport in a zero-valent iron permeable reactive barrier

    USGS Publications Warehouse

    Zhang, P.; Johnson, W.P.; Piana, M.J.; Fuller, C.C.; Naftz, D.L.

    2001-01-01

    Many published studies have used visual comparison of the timing of peak breakthrough of colloids versus conservative dissolved tracers (hereafter referred to as dissolved tracers or tracers) in subsurface media to determine whether they are advected differently, and to elucidate the mechanisms of differential advection. This purely visual approach of determining differential advection may have artifacts, however, due to the attachment of colloids to subsurface media. The attachment of colloids to subsurface media may shift the colloidal peak breakthrough to earlier times, causing an apparent "faster" peak breakthrough of colloids relative to dissolve tracers even though the transport velocities for the colloids and the dissolved tracers may actually be equivalent. In this paper, a peak shift analysis was presented to illustrate the artifacts associated with the purely visual approach in determining differential advection, and to quantify the peak shift due to colloid attachment. This peak shift analysis was described within the context of microsphere and bromide transport within a zero-valent iron (ZVI) permeable reactive barrier (PRB) located in Fry Canyon, Utah. Application of the peak shift analysis to the field microsphere and bromide breakthrough data indicated that differential advection of the microspheres relative to the bromide occurred in the monitoring wells closest to the injection well in the PRB. It was hypothesized that the physical heterogeneity at the grain scale, presumably arising from differences in inter- versus intra-particle porosity, contributed to the differential advection of the microspheres versus the bromide in the PRB. The relative breakthrough (RB) of microspheres at different wells was inversely related to the ionic strength of ground water at these wells, in agreement with numerous studies showing that colloid attachment is directly related to solution ionic strength.

  9. Long-term performance monitoring for a permeable reactive barrier at the U.S. Coast Guard Support Center, Elizabeth City, North Carolina.

    PubMed

    Puls, R W; Blowes, D W; Gillham, R W

    1999-08-12

    A continuous hanging iron wall was installed in June, 1996, at the U. S. Coast Guard (USCG) Support Center near Elizabeth City, NC, United States, to treat overlapping plumes of chromate and chlorinated solvent compounds. The wall was emplaced using a continuous trenching machine whereby native soil and aquifer sediment was removed and the iron simultaneously emplaced in one continuous excavation and fill operation. To date, there have been seven rounds (November 1996, March 1997, June 1997, September 1997, December 1997, March 1998, and June 1998) of performance monitoring of the wall. At this time, this is the only full-scale continuous 'hanging' wall installed as a permeable reactive barrier to remediate both chlorinated solvent compounds and chromate in groundwater. Performance monitoring entails the following: sampling of 10-5 cm PVC compliance wells and 15 multi-level samplers for the following constituents: TCE, cis-dichloroethylene (c-DCE), vinyl chloride, ethane, ethene, acetylene, methane, major anions, metals, Cr(VI), Fe(II), total sulfides, dissolved H(2), Eh, pH, dissolved oxygen, specific conductance, alkalinity, and turbidity. Electrical conductivity profiles have been conducted using a Geoprobe to verify emplacement of the continuous wall as designed and to locate upgradient and downgradient wall interfaces for coring purposes. Coring has been conducted in November, 1996, in June and September, 1997, and March, 1998, to evaluate the rate of corrosion on the iron surfaces, precipitate buildup (particularly at the upgradient interface), and permeability changes due to wall emplacement. In addition to several continuous vertical cores, angled cores through the 0.6-m thick wall have been collected to capture upgradient and downgradient wall interfaces along approximate horizontal flow paths for mineralogic analyses.

  10. Recovery of Cr as Cr(III) from Cr(VI)-contaminated kaolinite clay by electrokinetics coupled with a permeable reactive barrier.

    PubMed

    Suzuki, Tasuma; Kawai, Katsunori; Moribe, Mai; Niinae, Masakazu

    2014-08-15

    Zero-valent iron (Fe(0)) and magnetite (Fe3O4) were investigated as potential reductants in an electrokinetic/permeable reactive barrier hybrid system (EK/PRB) for the recovery of Cr as Cr(III) from Cr(VI)-contaminated kaolinite. For the EK/Fe(0) PRB, regardless of the pH in the anode well, the system facilitated the reduction of Cr(VI) into Cr(III), but the recovery of the Cr(III) in the PRB was low. Conversely, the reduction of Cr(VI) occurred only in the PRB for the EK/Fe3O4 PRB. However, when the anode pH was not controlled and the soil pH values correspondingly decreased gradually from the anode side, a greater fraction of Cr(VI) sorbed onto the kaolinite; as a result, a lower amount of Cr(VI) migrated to the Fe3O4 PRB. In addition, it was found that the majority of Cr(VI) migrating to the Fe3O4 PRB retained its oxidation state without being converted into Cr(III). These two adverse effects were mitigated by maintaining the soil pH values at 6.8, but at the same time, 18% of Cr(VI) penetrated through the Fe3O4 PRB. The penetration of Cr(VI) through the Fe3O4 PRB was successfully prevented by increasing the reaction time through the introduction of a cation exchange membrane between the Fe3O4 PRB and the anode well.

  11. Chemical Imaging and Dynamical Studies of Reactivity and Emergent Behavior in Complex Interfacial Systems. Final Technical Report

    SciTech Connect

    Sibener, Steven J.

    2014-03-11

    This research program explored the efficacy of using molecular-level manipulation, imaging and scanning tunneling spectroscopy in conjunction with supersonic molecular beam gas-surface scattering to significantly enhance our understanding of chemical processes occurring on well-characterized interfaces. One program focus was on the spatially-resolved emergent behavior of complex reaction systems as a function of the local geometry and density of adsorbate-substrate systems under reaction conditions. Another focus was on elucidating the emergent electronic and related reactivity characteristics of intentionally constructed single and multicomponent atom- and nanoparticle-based materials. We also examined emergent chirality and self-organization in adsorbed molecular systems where collective interactions between adsorbates and the supporting interface lead to spatial symmetry breaking. In many of these studies we combined the advantages of scanning tunneling (STM) and atomic force (AFM) imaging, scanning tunneling local electronic spectroscopy (STS), and reactive supersonic molecular beams to elucidate precise details of interfacial reactivity that had not been observed by more traditional surface science methods. Using these methods, it was possible to examine, for example, the differential reactivity of molecules adsorbed at different bonding sites in conjunction with how reactivity is modified by the local configuration of nearby adsorbates. At the core of this effort was the goal of significantly extending our understanding of interfacial atomic-scale interactions to create, with intent, molecular assemblies and materials with advanced chemical and physical properties. This ambitious program addressed several key topics in DOE Grand Challenge Science, including emergent chemical and physical properties in condensed phase systems, novel uses of chemical imaging, and the development of advanced reactivity concepts in combustion and catalysis including carbon

  12. Dip process thermal-barrier coatings for superalloys. Final report 1 Jul 79-30 Jun 80

    SciTech Connect

    Allam, I.M.; Bartlett, R.W.; Krishnan, G.N.

    1980-06-30

    A new technique of developing thermal-barrier coatings for superalloys has been investigated. It involves hot dipping of superalloy samples into a molten bath of low melting Ce-Co or Ce-Ni alloy. By internally oxidizing these coatings, it is possible to obtain a duplex with a CeO2-rich oxide scale as the outer layer (thermal barrier) and an inner layer composite of fine cerium oxide particles dispersed in a matrix of Ni(Co)CrAl. This inner layer, or subscale, grades into the superalloy. Appropriate heat treatment can produce recrystallized CeO2 particles in the subscale that should improve adherence of the oxide scale to the subscale and substrate superalloy. The coating process does involve limited reaction between the coating alloy and superalloy. The thickness of this interaction zone can be controlled and compensated for in the design (cross section) of the superalloy component.

  13. Permeable Reactive Barrier: Technology Update

    DTIC Science & Technology

    2011-06-01

    Contrary to laboratory findings, breakdown products like TAT from TNT have not been observed under field conditions. 4.3 Organic Substrates (Biowalls...low frequency of injection required, and lower product cost relative to other slow- release substrate types. There is an economy of scale in large...fatty acids Biodegradation breakdown products and fermentation substrates . Indicator of substrate distribution. Phospholipid fatty acids Indicator of

  14. Small-scale hydroelectric demonstration project: Reactivation of the Elk Rapids Hydroelectric Facility: Final operation and maintenance report

    SciTech Connect

    Miller, R.G.

    1987-03-01

    Information related to the reactivation of the Elk River Hydroelectric Power facility is reported. This report includes a history of the power plant, pertinent cost data, emergency action plans, inspections and testing, warranty work, operating problems, project data, monthly production data, and monthly operating and maintenance costs. 15 figs., 3 tabs.

  15. Pore structure and reactivity changes in hot coal gas desulfurization sorbents. Final report, September 1987--January 1991

    SciTech Connect

    Sotirchos, S.V.

    1991-05-01

    The primary objective of the project was the investigation of the pore structure and reactivity changes occurring in metal/metal oxide sorbents used for desulfurization of hot coal gas during sulfidation and regeneration, with particular emphasis placed on the effects of these changes on the sorptive capacity and efficiency of the sorbents. Commercially available zinc oxide sorbents were used as model solids in our experimental investigation of the sulfidation and regeneration processes.

  16. Hydrologic characterization of the Fry Canyon, Utah site prior to field demonstration of reactive chemical barriers to control radionuclide and trace-element contamination in ground water

    SciTech Connect

    Naftz, D.L.; Freethey, G.W.; Davis, J.A.

    1997-12-31

    The Fry Canyon Site in southeastern Utah has been selected as a long term demonstration site to assess the performance of selected reaction barrier technologies for the removal of uranium and other trace elements from ground water. Objectives include site characterization and evaluation of barrier technologies.

  17. Weathering effects on the structure and reactivity of US coals: Final report, July 15, 1984-July 14, 1987. [Many data

    SciTech Connect

    Meuzelaar, H.L.C.; Hill, G.R.; Yun, Yongseung; Jakab, E.; Windig, W.; Urban, D.; Yon, Kyung Yol; Oestreich, J.; East, J.

    1987-01-01

    This report covers the work performed from July 1984 to July 1987 under the project entitled ''Weathering Effects on Structure and Reactivity of US Coals'' (grant number FG22-84PC70798). The main objectives of the study were to investigate the structural changes in coal during the weathering process as well as to develop a simple, reliable weathering index, which can monitor indirectly the weathering-induced changes in physical and chemical properties. Although there have been numerous publications on structure and reactivity of coal, most data reported in the literature thus far have been obtained on coal samples of uncertain weathering status and therefore need to be interpreted with great caution. Weathering has a profound effect on many important coal properties such as heating value, caking characteristics, acidity, flotability and reactivity in liquefaction, combustion and gasification processes. The objective of developing a weathering index is to predict these coal property changes due to weathering without resorting to real-time measurements or pilot plant runs. This report is comprised of four main chapters: I. Structural Changes due to Weathering; II. Material Balance in Weathering Process; III. Development of a Reliable Weathering Index; and IV. Proposed Weathering Mechanisms. A battery of sophisticated analytical tools and techniques was employed during this study. Pyrolysis mass spectrometry in time-integrated, as well as in time-resolved modes with computer-aided data analysis techniques (such as factor and discriminant analysis), gas chromatography, thermogravimetry/mass spectrometry and solvent extraction were used for determining the role of oxygen during the weathering process. Pyrolysis mass spectrometry, Free Swelling Index and a novel slurry pH technique were employed as weathering indicators. 170 refs.

  18. Final Report: Molecular Mechanisms of Interfacial Reactivity in Near Surface and Extreme Geochemical Environments (DE-SC0009362)

    SciTech Connect

    Dixon, David A

    2016-03-27

    The prediction of the long-term stability and safety of geologic sequestration of greenhouse gases requires a detailed understanding of subsurface transport and chemical interactions between the disposed greenhouse gases and the geologic media. In this regard, mineral-fluid interactions are of prime importance since reactions that occur on or near the interface can assist in the long term sequestration of CO2 by trapping in mineral phases such as carbonates, as well as influencing the subsurface migration of the disposed fluids via creation or plugging of pores or fractures in the host rock strata. Previous research on mineral-fluid interaction for subsurface CO2 storage has focused almost entirely on the aqueous phase, i.e., reactivity with aqueous solutions or brines containing dissolved CO2. However, interactions with neat to water-saturated non-aqueous fluids are of equal if not greater importance since supercritical CO2 (scCO2) is less dense than the aqueous phase or oil which will create a buoyant scCO2 plume that ultimately will dominate the pore volume within the caprock, and the injected scCO2 will contain water soon after injection and this water can be highly reactive. Collectively, therefore, mineral interactions with water-saturated scCO2-dominated fluids are pivotal and could result in the stable sequestration of CO2 by trapping in mineral phases such as metal carbonates within otherwise permeable zones in the caprock. The primary objective is to unravel the molecular mechanisms governing the reactivity of mineral phases important in the geologic sequestration of CO2 with variably wet supercritical carbon dioxide as a function of T, P, and mineral structure using computational chemistry. This work is in close collaboration with the PNNL Geosciences effort. The focus of the work at The University of Alabama is computational studies of the formation of magnesium and calcium carbonates and oxides and their reactivity and providing computational support

  19. Final Report for LDRD Project 05-ERD-050: "Developing a Reactive Chemistry Capability for the NARAC Operational Model (LODI)"

    SciTech Connect

    Cameron-Smith, P; Grant, K; Connell, P

    2008-02-11

    In support of the National Security efforts of LLNL, this project addressed the existing imbalance between dispersion and chemical capabilities of LODI (Lagrangian Operational Dispersion Integrator--the NARAC operational dispersion model). We have demonstrated potentially large effects of atmospheric chemistry on the impact of chemical releases (e.g., industrial chemicals and nerve agents). Prior to our work, LODI could only handle chains of first-order losses (exponential decays) that were independent of time and space, limiting NARAC's capability to respond when reactive chemistry is important. We significantly upgraded the chemistry and aerosol capability of LODI to handle (1) arbitrary networks of chemical reactions, (2) mixing and reactions with ambient species, (3) evaporation and condensation of aerosols, and (4) heat liberated from chemical reactions and aerosol condensation (which can cause a cold and dense plume hugging the ground to rise into the atmosphere, then descend to the ground again as droplets). When this is made operational, it will significantly improve NARAC's ability to respond to terrorist attacks and industrial accidents that involve reactive chemistry, including many chemical agents and toxic industrial chemicals (TICS). As a dual-use, the resulting model also has the potential to be a state-of-the-art air-quality model. Chemical releases are the most common type of airborne hazardous release and many operational applications involve such scenarios. The new capability we developed is therefore relevant to the needs of the Department of Energy (DOE), Department of Homeland Security (DHS) and Department of Defense (DoD).

  20. Degradation of concrete-based barriers by Mg-containing brines: From laboratory experiments via reactive transport modelling to overall safety analysis in repository scale

    NASA Astrophysics Data System (ADS)

    Niemeyer, Matthias; Wilhelm, Stefan; Hagemann, Sven; Xie, Mingliang; Wollrath, Jürgen; Preuss, Jürgen

    2010-05-01

    The Morsleben nuclear waste repository (ERAM) for low- and intermediate-level radioactive waste is located in an old rock salt and potash mine in Northern Germany. From 1971 to 1998, approximately 36 800 m3 of waste have been disposed of. Now, waste disposal is finished, and the repository has to be backfilled and sealed. The closure concept is based on extensive backfilling of the salt mine with an inexpensive concrete mixture. The major disposal areas, containing most of the waste, will be isolated from the rest of the mine building by sealing the connecting access tunnels. The good geological situation (an intact cap rock with very small flow rates) provides an excellent basic condition for a safe repository. However, the access of water to the remaining parts of the mine cannot be excluded. The brines that are formed in contact with potash salts will contain Mg in a concentration that depends on various factors and cannot be predicted. For backfill and closure of the repository, no common material chemically stable against brines of all possible compositions is available. Salt concrete has a low permeability but is corroded by brines containing Mg, whilst concrete based on Sorel phases is decomposed if the Mg-content of the brines is too low. In each of these alternatives, corrosion results in a strong increase of permeability and a loss of the mechanical integrity of the material. However, for large hydraulic seals the flow of corroding brines is limited because of the high hydraulic resistance of the barrier. Thus, the barriers will persist for a long time in spite of the chemical incompatibility of building material and brine. For the planning of the backfill and closure measures as well as for the license application procedure it is crucial to demonstrate that the seals of the major disposal areas will keep their function for a sufficient long time. This lifetime depends among others on the corrosion capacity of the brine to the building material, on the

  1. AN IN SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUNDWATER:VOLUME 2 PERFORMANCE MONITORING

    EPA Science Inventory

    A 46 m long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Support Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium [Cr(VI)] contaminated ground ...

  2. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUND WATER: VOLUME 1 DESIGN AND INSTALLATION

    EPA Science Inventory

    A 46 m long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Support Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium [Cr(VI)] contaminated ground ...

  3. Design and evaluation of improved barrier fabrics for protection against toxic aerosols and biological agents. Final report

    SciTech Connect

    Hersh, S.P.; Tucker, P.A.

    1993-09-01

    The structure of nine fabrics, their resistance to aerosol penetration, and their pore size distributions were evaluated to determine their suitability as barrier fabrics for protection against aerosols. A main objective is to gain insight and knowledge which will be useful for designing fabrics that will provide better protection with minimum discomfort. Aerosol penetration was assessed using fluorescent polystyrene latex spheres ranging in diameter from 0.6 to 4.5 um at a face velocity of 1.8 cm/s. The maximum penetration occurred for 1.01 micrometers diameter spheres. Fabric pore size distributions were measured by liquid extrusion and microscopical image analysis, and the maximum pore size was also measured by liquid critical breakthrough pressure. Results obtained by all three techniques were fairly consistent. The best correlation between fabric structure and particle penetration at this time is between fabric density and weave type, with penetration decreasing with increasing fabric areal density and being lower for plain weave fabrics than for twill weaves. Biological aerosols, Chemical protective clothing, Biological agents, Fabrics, Aerosol penetration, Aerosols, Pore size.

  4. Peptide transport through the blood-brain barrier. Final report 1 Jul 87-31 Dec 90

    SciTech Connect

    Partridge, W.M.

    1991-01-15

    Most neuropeptides are incapable of entering the brain from blood owing to the presence of unique anatomical structures in the brain capillary wall, which makes up the blood-brain barrier (BBB). Such neuropeptides could be introduced into the bloodstream by intranasal insufflation and, thus, could have powerful medicinal properties (e.g., Beta-endorphin for the treatment of pain, vasopressin analogues for treatment of memory, ACTH analogues for treatment of post-traumatic epilepsy), should these peptides be capable of traversing the BBB. One such strategy for peptide delivery through the BBB is the development of chimeric peptides, which is the basis of the present contract. The production of chimeric peptides involves the covalent coupling of a nontransportable peptide (e.g., Beta-endorphin, vasopressin) to a transportable vector peptide (e.g., insulin, transferrin, cationized albumin, histone). The transportable peptide is capable of penetrating the BBB via receptor-mediated or absorptive-mediated transcytosis. Therefore, the introduction of chimeric peptides allows the nontransportable peptide to traverse the BBB via a physiologic piggy back mechanism.

  5. Final Project Report: Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport

    SciTech Connect

    Jon Chorover, University of Arizona; Peggy O'€™Day, University of California, Merced; Karl Mueller, Penn State University; Wooyong Um, Pacific Northwest National Laboratory; Carl Steefel, Lawrence Berkeley National Laboratory

    2012-10-01

    Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided detailed characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, PCO2, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions.

  6. Final Report Coupling in silico microbial models with reactive transport models to predict the fate of contaminants in the subsurface.

    SciTech Connect

    Lovley, Derek R.

    2012-10-31

    This project successfully accomplished its goal of coupling genome-scale metabolic models with hydrological and geochemical models to predict the activity of subsurface microorganisms during uranium bioremediation. Furthermore, it was demonstrated how this modeling approach can be used to develop new strategies to optimize bioremediation. The approach of coupling genome-scale metabolic models with reactive transport modeling is now well enough established that it has been adopted by other DOE investigators studying uranium bioremediation. Furthermore, the basic principles developed during our studies will be applicable to much broader investigations of microbial activities, not only for other types of bioremediation, but microbial metabolism in diversity of environments. This approach has the potential to make an important contribution to predicting the impact of environmental perturbations on the cycling of carbon and other biogeochemical cycles.

  7. Performance of Transuranic-Loaded Fully Ceramic Micro-Encapsulated Fuel in LWRs Final Report, Including Void Reactivity Evaluation

    SciTech Connect

    Michael A. Pope; R. Sonat Sen; Brian Boer; Abderrafi M. Ougouag; Gilles Youinou

    2011-09-01

    The current focus of the Deep Burn Project is on once-through burning of transuranics (TRU) in light-water reactors (LWRs). The fuel form is called Fully-Ceramic Micro-encapsulated (FCM) fuel, a concept that borrows the tri-isotropic (TRISO) fuel particle design from high-temperature reactor technology. In the Deep Burn LWR (DB-LWR) concept, these fuel particles are pressed into compacts using SiC matrix material and loaded into fuel pins for use in conventional LWRs. The TRU loading comes from the spent fuel of a conventional LWR after 5 years of cooling. Unit cell and assembly calculations have been performed using the DRAGON-4 code to assess the physics attributes of TRU-only FCM fuel in an LWR lattice. Depletion calculations assuming an infinite lattice condition were performed with calculations of various reactivity coefficients performed at each step. Unit cells and assemblies containing typical UO2 and mixed oxide (MOX) fuel were analyzed in the same way to provide a baseline against which to compare the TRU-only FCM fuel. Then, assembly calculations were performed evaluating the performance of heterogeneous arrangements of TRU-only FCM fuel pins along with UO2 pins.

  8. INVESTIGATION ON DURABILITY AND REACTIVITY OF PROMISING METAL OXIDE SORBENTS DURING SULFIDATION AND REGENERATION. QUARTERLY AND FINAL REPORT

    SciTech Connect

    K.C. KWON

    1998-08-01

    Hot-gas desulfurization for the integrated gasification combined cycle (IGCC) process has been investigated by many researchers to remove effectively hydrogen sulfide with various metal oxide sorbents at high pressures and high temperatures. Metal oxides such as zinc titanate oxides, zinc ferrite oxide, copper oxide, manganese oxide and calcium oxide, were found to be promising sorbents in comparison with other removal methods such as membrane separations and reactive membrane separations. Some metal oxide sorbents exhibited the quite favorable performance in terms of attrition resistance and sulfur capacity. Experiments on removal reaction of H{sub 2}S from coal gas mixtures with formulated metal oxide sorbents were conducted in a batch reactor or a differential reactor. The objectives of this research project are to formulate promising metal oxide sorbents for removal of sulfur from coal gas mixtures, to find initial reaction kinetics for the metal oxide-hydrogen sulfide heterogeneous reaction system, to obtain effects of hydrogen, nitrogen and moisture on dynamic absorption and equilibrium absorption at various absorption temperatures. Promising durable metal oxide sorbents with high-sulfur-absorbing capacity were formulated by mixing active metal oxide powders with inert metal oxide powders, and calcining these powder mixtures. The Research Triangle Institute (RTI), a sub-contractor of this research project, will also prepare promising metal oxide sorbents for this research project, plan experiments on removal of sulfur compounds from coal gases with metal oxide, and review experimental results.

  9. Reactive characterization as a probe of the nature of catalytic sites. Final report, April 15, 1988--February 14, 1993

    SciTech Connect

    Brenner, A.

    1998-05-01

    The primary goal of the last year of the research program was to create a new type of selective heterogeneous catalyst. The new catalysts were synthesized, their unusual selectivity assessed by a model reaction, and some of the parameters which are important in creating unusual selectivity in these catalysts determined. Near the end of this proposal, considerable excitement was generated by the discovery of high temperature superconductors. It was decided to briefly investigate the activity of some superconductors and related cuprates. This research was done in concert with a project funded by Ford Motor Company. Catalysts were investigated for two reactions useful in pollution control: CO oxidation and NO reduction. In addition, some stoichiometric measurements of the oxygen content of superconductors and related cuprates were made using a TPR apparatus in the lab. In addition, some experiments were done with the objective of preparing novel MO-Pd/Al{sub 2}O{sub 3} catalysts in which the Mo and Pd were in close contact. These catalysts have the potential of replacing much more expensive rhodium containing catalysts which are currently used for emissions control. Progress on the following is described: H{sub 2}-D{sub 2} exchange on transition metals; New method of determining the number of active sites; New method of determining the hydroxyl content of catalysts; H{sub 2}-D{sub 2} exchange on metal oxides; Reactive characterization and atomic isolation of active sites; Site isolated catalysts synthesized by selective poisoning; Catalysts prepared from high temperature superconductors; Mixed metal Pd-Mo catalysts; and Selective reduction of nitric oxide.

  10. An experimental evaluation of the instrumented flux synthesis method for the real-time estimation of reactivity. Final report

    SciTech Connect

    Hughes, J.C.; Henry, A.F.; Lanning, D.D.; Bernard, J.A.

    1996-01-01

    One method of determining the flux density is flux synthesis which approximates the flux in the core by linear combinations of precomputed shape functions. In traditional flux synthesis, the unknown mixing coefficients are determined using a weighted residual method of solving the diffusion equation. In the instrumented synthesis method, the mixing coefficients are determined using count rates from neutron detectors in the core. In this way the mixing coefficients are linked to conditions in the reactor. Using the synthesized flux, kinetics parameters, notably reactivity, can be calculated in real time. An experimental evaluation has been performed in the Massachusetts Institute of Technology Reactor, MITR-II. Detector measurements have been collected using fission chambers placed at the periphery of the core. The reactor was put into a number of various conditions, both static and transient, and data were collected using a digital acquisition system for later combination with shape functions. Transients included increasing power, decreasing power, and a reactor scram. The shape functions were generated using Version 3.0 of the QUARTZ code, a quadratic nodal diffusion theory code in triangular-Z geometry. Supernodal analysis algorithms have been added to the original program, along with subroutines to guarantee diagonal dominance of the leakage matrix in the finite difference or quadratic current approximations in the coarse mesh. The agreement between coarse mesh and fine mesh in all cases is excellent, with finite difference coarse mesh solutions generally slightly better. The synthesis method has been shown to accurately reflect the changes from an initial condition by combining representative flux shapes. It can be concluded that, with proper calibration of the measurement system and inclusion of representative flux shapes, the instrumented synthesis method will properly predict the flux in the core under a number of conditions.

  11. FINAL REPORT: Coupling Sorption to Soil Weathering During Reactive Transport: Impacts of Mineral Transformation and Sorbent Aging on Contaminant Speciation and Mobility

    SciTech Connect

    Mueller, Karl T; Chorover, John C; ODay, Peggy A; Um, Wooyong; Steefel, Carl I

    2009-10-05

    This project aimed for a predictive-mechanistic understanding of the coupling between mineral weathering and contaminant (Cs, Sr, I) transport/fate in caustic waste-impacted sediments. Based on our prior studies of model clay mineral systems, we postulated that contaminant uptake to Hanford sediments would reflect concurrent adsorption and co-precipitation effects. Our specific objectives were: (1) to assess the molecular-scale mechanisms responsible for time-dependent sequestration of contaminants (Cs, Sr and I) during penetration of waste-induced weathering fronts; (2) to determine the rate and extent of contaminant release from the sorbed state; (3) to develop a reactive transport model based on molecular mechanisms and macroscopic flow experiments [(1) and (2)] that simulates adsorption, aging, and desorption dynamics. Progress toward achieving each of these objectives is discussed in this Final Report.

  12. Identification of Barriers and Proposed Solutions to the Attainment of Equal Representation in Post-Secondary Allied Health Programs for Minorities. Final Report.

    ERIC Educational Resources Information Center

    Whittington, Marna C.; Benson, Stephen D.

    The study identified the barriers which prevent application, matriculation, and/or completion of allied health postsecondary education programs by blacks, Spanish-surnamed Americans, and Native Americans and recommended means of reducing or eliminating the barriers. Only those barriers which could be resolved or reduced through programs of public…

  13. Final Barrier: Small System Compliance

    EPA Science Inventory

    This presentation will discuss the use of point-of-use (POU) technology for small drinking water systems. Information will be provided on the USEPA regulations that allow the use of POU for compliance and the technologies that are listed as SSCT for radium and arsenic. Listing o...

  14. Permeable Reactive Zones for Groundwater Remediation

    EPA Science Inventory

    The presentation will cover aspects of the application of permeable reactive zones to treat contaminated ground water. Specific field studies will be discussed covering both granular iron-based and organic carbon-based reactive barriers. Specific contaminants addressed include:...

  15. Intestinal barrier dysfunction develops at the onset of experimental autoimmune encephalomyelitis, and can be induced by adoptive transfer of auto-reactive T cells.

    PubMed

    Nouri, Mehrnaz; Bredberg, Anders; Weström, Björn; Lavasani, Shahram

    2014-01-01

    Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system with a pathogenesis involving a dysfunctional blood-brain barrier and myelin-specific, autoreactive T cells. Although the commensal microbiota seems to affect its pathogenesis, regulation of the interactions between luminal antigens and mucosal immune elements remains unclear. Herein, we investigated whether the intestinal mucosal barrier is also targeted in this disease. Experimental autoimmune encephalomyelitis (EAE), the prototypic animal model of MS, was induced either by active immunization or by adoptive transfer of autoreactive T cells isolated from these mice. We show increased intestinal permeability, overexpression of the tight junction protein zonulin and alterations in intestinal morphology (increased crypt depth and thickness of the submucosa and muscularis layers). These intestinal manifestations were seen at 7 days (i.e., preceding the onset of neurological symptoms) and at 14 days (i.e., at the stage of paralysis) after immunization. We also demonstrate an increased infiltration of proinflammatory Th1/Th17 cells and a reduced regulatory T cell number in the gut lamina propria, Peyer's patches and mesenteric lymph nodes. Adoptive transfer to healthy mice of encephalitogenic T cells, isolated from EAE-diseased animals, led to intestinal changes similar to those resulting from the immunization procedure. Our findings show that disruption of intestinal homeostasis is an early and immune-mediated event in EAE. We propose that this intestinal dysfunction may act to support disease progression, and thus represent a potential therapeutic target in MS. In particular, an increased understanding of the regulation of tight junctions at the blood-brain barrier and in the intestinal wall may be crucial for design of future innovative therapies.

  16. Evaluation and Computational Characterization of the Faciliated Transport of Glc Carbon C-1 Oxime Reactivators Across a Blood Brain Barrier Model

    DTIC Science & Technology

    2013-01-01

    designing BBB-pene- trating SOxs and correlate this model with experimental results. 2. Materials and methods 2.1. Sugar-oxime synthesis Materials and...blood–brain barrier in its dihydropyridine pro-drug form, J. Med. Chem. 19 (1976) 113–117. [2] B.P. Melchers, I.H. Philippens, O.L. Wolthuis, Efficacy... Synthesis of glycosyl derivatives as dopamine prodrugs: interaction with glucose carrier GLUT-1, Org. Biomol. Chem. 1 (2003) 767–771. [12] T. Halmos, M

  17. Interaction of O and OH radicals with a simple model system for lipids in the skin barrier: a reactive molecular dynamics investigation for plasma medicine

    NASA Astrophysics Data System (ADS)

    Van der Paal, Jonas; Aernouts, Stefaan; van Duin, Adri C. T.; Neyts, Erik C.; Bogaerts, Annemie

    2013-10-01

    Plasma medicine has been claimed to provide a novel route to heal wounds and regenerate skin, although very little is currently known about the elementary processes taking place. We carried out a series of ReaxFF-based reactive molecular dynamics simulations to investigate the interaction of O and OH radicals with lipids, more specifically with α-linolenic acid as a model for the free fatty acids present in the upper skin layer. Our calculations predict that the O and OH radicals most typically abstract a H atom from the fatty acids, which can lead to the formation of a conjugated double bond, but also to the incorporation of alcohol or aldehyde groups, thereby increasing the hydrophilic character of the fatty acids and changing the general lipid composition of the skin. Within the limitations of the investigated model, no formation of possibly toxic products was observed.

  18. Consolidation of geologic studies of geopressured-geothermal resources in Texas: Barrier-bar tidal-channel reservoir facies architecture, Jackson Group, Prado field, South Texas; Final report

    SciTech Connect

    Seni, S.J.; Choh, S.J.

    1994-01-01

    Sandstone reservoirs in the Jackson barrier/strandplain play are characterized by low recovery efficiencies and thus contain a large hydrocarbon resource target potentially amenable to advanced recovery techniques. Prado field, Jim Hogg County, South Texas, has produced over 23 million bbl of oil and over 32 million mcf gas from combination structural-stratigraphic traps in the Eocene lower Jackson Group. Hydrocarbon entrapment at Prado field is a result of anticlinal nosing by differential compaction and updip pinch-out of barrier bar sandstone. Relative base-level lowering resulted in forced regression that established lower Jackson shoreline sandstones in a relatively distal location in central Jim Hogg County. Reservoir sand bodies at Prado field comprise complex assemblages of barrier-bar, tidal-inlet fill, back-barrier bar, and shoreface environments. Subsequent progradation built the barrier-bar system seaward 1 to 2 mi. Within the barrier-bar system, favorable targets for hydrocarbon reexploration are concentrated in tidal-inlet facies because they possess the greatest degree of depositional heterogeneity. The purpose of this report is (1) to describe and analyze the sand-body architecture, depositional facies variations, and structure of Prado field, (2) to determine controls on distribution of hydrocarbons pertinent to reexploration for bypassed hydrocarbons, (3) to describe reservoir models at Prado field, and (4) to develop new data affecting the suitability of Jackson oil fields as possible candidates for thermally enhanced recovery of medium to heavy oil.

  19. X-231A demonstration of in-situ remediation of DNAPL compounds in low permeability media by soil fracturing with thermally enhanced mass recovery or reactive barrier destruction

    SciTech Connect

    Siegrist, R.L. |; Lowe, K.S.; Murdoch, L.D. |; Slack, W.W.; Houk, T.C.

    1998-03-01

    The overall goal of the program of activities is to demonstrate robust and cost-effective technologies for in situ remediation of DNAPL compounds in low permeability media (LPM), including adaptations and enhancements of conventional technologies to achieve improved performance for DNAPLs in LPM. The technologies sought should be potential for application at simple, small sites (e.g., gasoline underground storage tanks) as well as at complex, larger sites (e.g., DOE land treatment units). The technologies involved in the X-231A demonstration at Portsmouth Gaseous Diffusion Plant (PORTS) utilized subsurface manipulation of the LPM through soil fracturing with thermally enhanced mass recovery or horizontal barrier in place destruction. To enable field evaluation of these approaches, a set of four test cells was established at the X-231A land treatment unit at the DOE PORTS plant in August 1996 and a series of demonstration field activities occurred through December 1997. The principal objectives of the PORTS X-231A demonstration were to: determine and compare the operational features of hydraulic fractures as an enabling technology for steam and hot air enhanced soil vapor extraction and mass recovery, in situ interception and reductive destruction by zero valent iron, and in situ interception and oxidative destruction by potassium permanganate; determine the interaction of the delivered agents with the LPM matrix adjacent to the fracture and within the fractured zone and assess the beneficial modifications to the transport and/or reaction properties of the LPM deposit; and determine the remediation efficiency achieved by each of the technology strategies.

  20. Reactive transport modeling for Cs retention: from batch to field experiments

    NASA Astrophysics Data System (ADS)

    De Pourcq, K.; Ayora, C.; Carrera, J.; García-Gutiérrez, M.; Missana, T.; Mingarro, M.

    2012-04-01

    A Permeable Reactive Barrier has been designed to treat 137Cs polluted groundwater. In order to check both reactivity and permeability, laboratory batch and column tests combined with reactive transport modeling have been performed. The trapping mechanism is based on the sorption of cesium mainly on illite-containing clays. Batch experiments were conducted to obtain the partition coefficients (Kd) of different clay samples in solutions with different potassium concentration. A clear correlation of Kd values with potassium content was observed. The results were modeled with a cation-exchange model. The permeability of the reactive material is provided by the dispersion of the clay on a matrix of wooden shavings. Constant head tests allowed obtaining permeability values. Several column experiments with different flow rates were conducted to confirm the 137Cs retention under different conditions. A blind 1D reactive transport model based on the cation-exchange model was able to predict reasonably well the results of column experiments. The reactive transport model, validated with the column experiments, was used to investigate the performance and duration of 1m thick barrier under different scenarios (flow, clay proportion, 137Cs and K concentration). As expected, the sensitivity tests proved that the retention capacity of dissolved 137Cs in groundwater depends linearly on the amount of clay used in the filling material. As well, the operation time increases linearly when decreasing the flow rate. Finally, the concentration of potassium in inflow water has a remarkable and non-linear influence in the retention of 137Cs. Very high concentrations of potassium are the greatest threat and can lead to the unfeasibility of a permeable reactive barrier. Due to the Cs-K competition, the barrier is comparatively more efficient to treat high concentrations of 137Cs. Up to now, preliminary results from a field scale experiment have confirmed the reactivity and permeability

  1. Measurement of the atmospheric reactivity of emissions from gasoline and alternative-fueled vehicles: Assessment of available methodologies. Part 1. Indoor smog chamber study of reactivity. Final report for the first year, January 1-December 31, 1993

    SciTech Connect

    Kelly, N.A.; Wang, P.; Japar, S.M.; Hurley, M.D.; Wallington, T.J.

    1994-06-30

    A set of multiple indoor smog chambers were used to measure the increase in smog formation (smog = NO oxidation + O3 formation) from a series of individual test volatile organic compounds (VOC`s), as well as carbon monoxide (CO), when they were added to a standard urban mixture and irradiated for 10-12 hours with a solar simulator. The chambers and the mixtures were designed to simulate the Carter incremental reactivity concept that is being used in California. The test compounds covered a wide range of mechanistic uncertainties and predicted reactivities (reactivity is the increase in smog divided by the amount of test compound added). Also, the chambers were used to test the recently developed Integrated Empirical Rate (IER) Model which predicts that the smog formation of a mixture is constant and independent of NOx in the so-called light-limited regime.

  2. Epidemiologically non-feasible singleton reactors at the final stage of BoHV1 eradication: serological evidence of BoHV2 cross-reactivity.

    PubMed

    Böttcher, Jens; Boje, Jennifer; Janowetz, Britta; Alex, Michaela; König, Patricia; Hagg, Maria; Götz, Franz; Renner, Konrad; Otterbein, Christian; Mages, Johann; Meier, Norbert; Wittkowski, Gerhard

    2012-10-12

    A voluntary marker-independent Bovine Herpesvirus 1 (BoHV1) eradication program started in 1986; in 1998 it changed to a compulsory one. Certification of free regions in European member states is based on Article 10 of directive 64/432/EEC. According to this rule Bavaria is listed as free of BoHV1 since October 2011. Surveillance of BoHV1-free dairy cattle farms is currently performed with quarterly bulk-milk testing. Non-negative bulk-milk results must be confirmed by blood tests in cattle older than nine months. An increased regional rate of non-negative bulk-milk samples and the subsequent detection of epidemiologically non-feasible singleton BoHV1-reactors by analysis of blood were observed at the final stage of eradication in southwest Bavaria. Nineteen case farms (734 animals) defined by singleton reactors born at least two years after certification of the farms as BoHV1-free, 23 negative control (NC) farms (NC I: 321 animals) from the same region, 11 NC-farms (NC II: 423 animals) from an already-certified Article 10 region in northeast Bavaria and two BoHV1-infected farms (264 animals) were analysed using BoHV1-, BoHV2- and Feline Herpesvirus 1 (FeHV1)-neutralisation tests (NTs), and three commercially available ELISAs supplied by Idexx Laboratories, B.V., The Netherlands: the CHEKIT™ Trachitest 2nd Gen. test for milk or serum (Trachitest), Herdchek™ gB- (gB-ELISA) and Herdchek™ gE-ELISA (gE-ELISA). Significantly increased levels of BoHV2 antibodies were observed on case farms compared to NC I or II farms. Additionally, reactivity by gB-ELISA and the Trachitest was significantly increased for animals with BoHV2 neutralising antibodies. Singleton BoHV1-reactors tested negative by gE-ELISA even if an elevated cut-off of 0.95±0.05 was applied. At this cut-off, the gE-ELISA was as sensitive and specific as the gB-ELISA. Comparative titration of milk samples from seropositive animals from a BoHV1-infected dairy cattle farm and from singleton BoHV1-reactors

  3. Diffusion barriers

    NASA Technical Reports Server (NTRS)

    Nicolet, M. A.

    1983-01-01

    The choice of the metallic film for the contact to a semiconductor device is discussed. One way to try to stabilize a contact is by interposing a thin film of a material that has low diffusivity for the atoms in question. This thin film application is known as a diffusion barrier. Three types of barriers can be distinguished. The stuffed barrier derives its low atomic diffusivity to impurities that concentrate along the extended defects of a polycrystalline layer. Sacrificial barriers exploit the fact that some (elemental) thin films react in a laterally uniform and reproducible fashion. Sacrificial barriers have the advantage that the point of their failure is predictable. Passive barriers are those most closely approximating an ideal barrier. The most-studied case is that of sputtered TiN films. Stuffed barriers may be viewed as passive barriers whose low diffusivity material extends along the defects of the polycrystalline host.

  4. In stream habitat and stock restoration for salmon otter creek barrier bypass subproject. Restoration project 94139-b1. Exxon Valdez oil spill restoration project final report

    SciTech Connect

    Wedemeyer, K.; Gillikin, D.

    1995-05-01

    In 1994, two barrier falls on Otter Creek, Bay of Isles, Knight Island, Prince William Sound were modified to provide upstream passage to adult pink salmon (Onchorhynchus gorbuscha). The falls were modified by using wire basket gabions, rock drills and wooden weir structures. In addition, an existing set of Alaska steeppasses were maintained and slightly modified for efficient passage of salmon.

  5. A Compendium of Research Addressing Barriers to Student Recruitment and Retention in Vocational Education in Florida. Final Report from September 1, 1984 to December 31, 1984.

    ERIC Educational Resources Information Center

    Waltz, Freddie C.; Beeman, Carl E.

    To address the issues of student recruitment and retention in Florida, a three-year research study was conducted. The three phases of the study sought the following: (1) to describe barriers to recruitment and retention of disadvantaged, unemployed, underemployed, out-of-school youth as perceived by students, teachers, counselors, and…

  6. FINAL REPORT: Coupling Sorption to Soil Weathering During Reactive Transport: Impacts of Mineral Transformation and Sorbent Aging on Contaminant Speciation and Mobility

    SciTech Connect

    O'Day, Peggy A.; Chorover, Jon; Mueller, Karl; Steefel, Carl; Serne, R. Jeff

    2009-03-21

    waste leachate (STWL) for up to 1 year in the presence and absence of CO2. Batch or column STWLreacted sediments are then subjected to column leaching experiments using simulated background pore water (BPW) solution to assess subsequent contaminant release. We used a multi-faceted approach (XAS, XRD, DRIFT, NMR, TEM/EDS, wet chemistry) to investigate molecular-scale mechanisms that give rise to macroscale response. In order to develop efficient predictive tools applicable to the Hanford site our work involves (1) production of laboratory-weathered sediments under conditions representative of caustic waste release; (2) mineralogical characterization and contaminant molecular speciation of the STWL-weathered (time = 0) sediments; (3) intensive monitoring of element release trajectories during controlled BPW infiltration; (4) mineralogical characterization and contaminant molecular speciation of BPW-leached (time = final) sediments; use of (2) through (4) to constrain mechanistic reactive transport modeling of contaminant release from weathered sediments.

  7. Design and evaluation of improved barrier fabrics for protection against toxic aerosols and biological agents. Phase 2. Final report, January 1993-December 1994

    SciTech Connect

    Hersh, S.P.; Tucker, P.A.

    1995-05-01

    The ultimate objective of this research is to develop semipermeable barrier fabrics which provide better protection for chemical protective clothing applications. In order to understand the relationship between the aerosol particle penetration and the structure of barrier fabrics, the research activities in Phase I focused on measuring the transmission of aerosols through test fabrics, determining the penetration mechanisms, and evaluating the pore size distributions in the fabrics. Based on the knowledge gained in Phase I, a set of 32 fabrics was designed, fabricated, and evaluated in Phase II using a 2-level, 7-factor, statistical design. Five additional outer fabrics and a carbon foam liner supplied by the U.S. Army Natick RDE Center (Natick) were evaluated to provide further insights into the effect of dual layers of fabrics and their relative orientations on aerosol penetration. The results of this research have been described in a Doctoral Dissertation by Dr. Surinder M. Maini (based on the 32 statistically designed fabrics) 1 and in a Master of Science thesis by Ms. Amelia Tosti 2 (on the fabrics supplied by Natick) in accordance with the research proposal. Abstracts of these two documents are presented in Section 2.0. The rest of this report describes the work and results conducted during Phase II. pg14. JMD.

  8. Final Technical Report. Reactivity of Iron-Bearing Minerals and CO2 Sequestration and Surface Chemistry of Pyrite. An Interdisciplinary Approach

    SciTech Connect

    Strongin, Daniel

    2014-12-31

    Over the course of the scientific program, two areas of research were pursued: reactions of iron oxides with supercritical CO2 and sulfide and surface reactivity of pyrite. The latter area of interest was to understand the chemistry that results when supercritical CO2 (scCO2 ) with H2 S and/or SO2 in deep saline formations (DFS) contacts iron bearing minerals. Understanding the complexities the sulfur co-injectants introduce is a critical step in developing CO2 sequestration as a climate-mitigating strategy. The research strategy was to understand macroscopic observations of this chemistry with an atomic/molecular level view using surface analytical techniques. Research showed that the exposure of iron (oxyhdr)oxides (which included ferrihydrite, goethite, and hematite) to scCO2 in the presence of sulfide led to reactions that formed siderite (FeCO3). The results have important implications for the sequestration of CO2 via carbonation reactions in the Earth’s subsurface. An earlier area of focus in the project was to understand pyrite oxidation in microscopic detail. This understanding was used to understand macroscopic observations of pyrite reactivity. Results obtained from this research led to a better understanding how pyrite reacts in a range of chemical environments. Geochemical and modern surface science techniques were used to understand the chemistry of pyrite in important environmental conditions. The program relied on a strong integration the results of these techniques to provide a fundamental understanding to the macroscopic chemistry exhibited by pyrite in the environment. Major achievements during these studies included developing an understanding of the surface sites on pyrite that controlled its reactivity under oxidizing conditions. In particular sulfur anion vacancies and/or ferric sites were sites of reactivity. Studies also showed that the

  9. Transport Properties of a Kinetic Model for Chemical Reactions without Barriers

    SciTech Connect

    Alves, Giselle M.; Kremer, Gilberto M.; Soares, Ana Jacinta

    2011-05-20

    A kinetic model of the Boltzmann equation for chemical reactions without energy barrier is considered here with the aim of evaluating the reaction rate and characterizing the transport coefficient of shear viscosity for the reactive system. The Chapman-Enskog solution of the Boltzmann equation is used to compute the chemical reaction effects, in a flow regime for which the reaction process is close to the final equilibrium state. Some numerical results are provided illustrating that the considered chemical reaction without energy barrier can induce an appreciable influence on the reaction rate and on the transport coefficient of shear viscosity.

  10. Vehicle barrier

    DOEpatents

    Hirsh, Robert A.

    1991-01-01

    A vehicle security barrier which can be conveniently placed across a gate opening as well as readily removed from the gate opening to allow for easy passage. The security barrier includes a barrier gate in the form of a cable/gate member in combination with laterally attached pipe sections fixed by way of the cable to the gate member and lateral, security fixed vertical pipe posts. The security barrier of the present invention provides for the use of cable restraints across gate openings to provide necessary security while at the same time allowing for quick opening and closing of the gate areas without compromising security.

  11. Micro heat barrier

    DOEpatents

    Marshall, Albert C.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2003-08-12

    A highly effective, micron-scale micro heat barrier structure and process for manufacturing a micro heat barrier based on semiconductor and/or MEMS fabrication techniques. The micro heat barrier has an array of non-metallic, freestanding microsupports with a height less than 100 microns, attached to a substrate. An infrared reflective membrane (e.g., 1 micron gold) can be supported by the array of microsupports to provide radiation shielding. The micro heat barrier can be evacuated to eliminate gas phase heat conduction and convection. Semi-isotropic, reactive ion plasma etching can be used to create a microspike having a cusp-like shape with a sharp, pointed tip (<0.1 micron), to minimize the tip's contact area. A heat source can be placed directly on the microspikes. The micro heat barrier can have an apparent thermal conductivity in the range of 10.sup.-6 to 10.sup.-7 W/m-K. Multiple layers of reflective membranes can be used to increase thermal resistance.

  12. Fate and transport of particle-reactive normal, alkylated and heterocyclic aromatic hydrocarbons in a sediment-water-colloid system. University research initiative. Final report

    SciTech Connect

    Means, J.C.; McMillin, D.J.

    1993-06-01

    The overall study framework is designed to investigate the fate, transport and chemical transformations of normal, alkylated and heterocyclic aromatic hydrocarbons associated with spilled oil, operational discharges and produced water discharges in coastal marine and estuarine environmental systems. In the present research, the nature of the particle reactivity or sorption/desorption equilibria which control the fate, transport and chemical transformations of hydrocarbons has been investigated throgh studies of the sorption/desorption equilibria and kinetics of selected normal, alkylated and heterocyclic PAH on various sediment types (a range of organic carbon and particle sizes) over a range of salinities and studies of the relationship between the carbon fraction of sediments and the equilibrium K(suboc) (Partition coefficient) for selected normal, alkylated and heterocyclic PAH. New trace analytical techniques for aromatic hydrocarbons were developed and applied.

  13. Barriers of the peripheral nerve

    PubMed Central

    Peltonen, Sirkku; Alanne, Maria; Peltonen, Juha

    2013-01-01

    This review introduces the traditionally defined anatomic compartments of the peripheral nerves based on light and electron microscopic topography and then explores the cellular and the most recent molecular basis of the different barrier functions operative in peripheral nerves. We also elucidate where, and how, the homeostasis of the normal human peripheral nerve is controlled in situ and how claudin-containing tight junctions contribute to the barriers of peripheral nerve. Also, the human timeline of the development of the barriers of the peripheral nerve is depicted. Finally, potential future therapeutic modalities interfering with the barriers of the peripheral nerve are discussed. PMID:24665400

  14. Effects of uncertainty in SAPRC90 rate constants and selected product yields on reactivity adjustment factors for alternative fuel vehicle emissions. Final report

    SciTech Connect

    Bergin, M.S.; Russell, A.G.; Yang, Y.J.; Milford, J.B.; Kirchner, F.; Stockwell, W.R.

    1996-07-01

    Tropospheric ozone is formed in the atmosphere by a series of reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NO{sub x}). While NOx emissions are primarily composed of only two compounds, nitrogen oxide (NO) and nitrogen dioxide (NO{sub 2}), there are hundreds of different VOCs being emitted. In general, VOCs promote ozone formation, however, the rate and extent of ozone produced by the individual VOCs varies considerably. For example, it is widely acknowledged that formaldehyde (HCHO) is a very reactive VOC, and produces ozone rapidly and efficiently under most conditions. On the other hand, VOCs such as methane, ethane, propane, and methanol do not react as quickly, and are likely to form less urban ozone than a comparable mass of HCHO. The difference in ozone forming potential is one of the bases for the use of alternative fuels. The fuels considered in this study included compressed natural gas, LPG, mixtures of methanol and gasoline, ethanol and gasoline, and a reformulated gasoline.

  15. Final Report for "Boron and Tin in Nuclear Medicien: The Development of Reactive Solid-State Reagents for PET and SPECT

    SciTech Connect

    George W. Kabalka

    2006-01-13

    The research program was directed at the use of functionalized organometallic reagents that would rapidly react with radiolabeled agents generated by a medical cyclotron or reactor. The radioisotopes included fluorine-18, oxgygen-15, nitrogen-13, carbon-11 and iodine-123; all short lived nuclides of importantce in nuclear medicine imaging studies utilizing emission tomography techniques. The early studies led to the development of extensive new isotope incorporation chemistry. These studies validated the feasibility of using reactive intermediates, such as the organoboranes, and acted as a catalyst for others to investigate organometallic agents based on mercury, tin, and silicon. A large number of radiolabeling techniques and radiopharmaceuticals were developed. These included agents for use in oncology, neurology, and metabolism. The research resulted in the generation of one hundred and one journal articles, eighty seven refereed published abstracts and forty one invited lectures. Thirteen postdoctoral students, fourteen graduate students, and twenty eight undergraduate students were trained in the scientific aspects of nuclear medicine imaging under the asupices of this grant.

  16. DOE FG02-03ER63557: Final Technical Report: Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks

    SciTech Connect

    Kathryn L. Nagy

    2009-05-04

    The purpose of the project was to investigate rates and mechanisms of reactions between primary sediment minerals and key components of waste tank solutions that leaked into the subsurface at the Hanford Site. Results were expected to enhance understanding of processes that cause (1) changes in porosity and permeability of the sediment and resultant changes in flow paths of the contaminant plumes, (2) formation of secondary precipitates that can take up contaminants in their structures, and (3) release of mineral components that can drive redox reactions affecting dissolved contaminant mobility. Measured rates can also be used directly in reactive transport models. Project tasks included (1) measurement of the dissolution rates of biotite mica from low to high pH and over a range of temperature relevant to the Hanford subsurface, (2) measurement of dissolution rates of quartz at high pH and in the presence of dissolved alumina, (3) measurement of the dissolution rates of plagioclase feldspar in high pH, high nitrate, high Al-bearing solutions characteristic of the BX tank farms, (4) incorporation of perrhenate in iron-oxide minerals as a function of pH, and (5) initiation of experiments to measure the formation of uranium(VI)-silicate phases under ambient conditions. Task 2 was started under a previous grant from the Environmental Management Science Program and Task 4 was partially supported by a grant to the PI from the Geosciences Program, Office of Basic Energy Sciences. Task 5 was continued under a subsequent grant from the Environmental Remediation Sciences Program, Office of Biological and Environmental Research.

  17. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    SciTech Connect

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  18. Language barriers

    PubMed Central

    Ngwakongnwi, Emmanuel; Hemmelgarn, Brenda R.; Musto, Richard; King-Shier, Kathryn M.; Quan, Hude

    2012-01-01

    Abstract Objective To assess use of regular medical doctors (RMDs), as well as awareness and use of telephone health lines or telehealth services, by official language minorities (OLMs) in Canada. Design Analysis of data from the 2006 postcensal survey on the vitality of OLMs. Setting Canada. Participants In total, 7691 English speakers in Quebec and 12 376 French speakers outside Quebec, grouped into those who experienced language barriers and those with no language barriers. Main outcome measures Health services utilization (HSU) by the presence of language barriers; HSU measures included having an RMD, use of an RMD’s services, and awareness of and use of telephone health lines or telehealth services. Multivariable models examined the associations between HSU and language barriers. Results After adjusting for age and sex, English speakers residing in Quebec with limited proficiency in French were less likely to have RMDs (adjusted odds ratio [AOR] 0.66, 95% CI 0.50 to 0.87) and to use the services of their RMDs (AOR 0.65, 95% CI 0.50 to 0.86), but were more likely to be aware of the existence of (AOR 1.50, 95% CI 1.16 to 1.93) and to use (AOR 1.43, 95% CI 0.97 to 2.11) telephone health lines or telehealth services. This pattern of having and using RMDs and telehealth services was not observed for French speakers residing outside of Quebec. Conclusion Overall we found variation in HSU among the language barrier populations, with lower use observed in Quebec. Age older than 45 years, male sex, being married or in common-law relationships, and higher income were associated with having RMDs for OLMs. PMID:23242902

  19. Introducing new reactivity descriptors: "Bond reactivity indices." Comparison of the new definitions and atomic reactivity indices

    NASA Astrophysics Data System (ADS)

    Sánchez-Márquez, Jesús

    2016-11-01

    A new methodology to obtain reactivity indices has been defined. This is based on reactivity functions such as the Fukui function or the dual descriptor and makes it possible to project the information of reactivity functions over molecular orbitals instead of the atoms of the molecule (atomic reactivity indices). The methodology focuses on the molecule's natural bond orbitals (bond reactivity indices) because these orbitals (with physical meaning) have the advantage of being very localized, allowing the reaction site of an electrophile or nucleophile to be determined within a very precise molecular region. This methodology gives a reactivity index for every Natural Bond Orbital (NBO), and we have verified that they have equivalent information to the reactivity functions. A representative set of molecules has been used to test the new definitions. Also, the bond reactivity index has been related with the atomic reactivity one, and complementary information has been obtained from the comparison. Finally, a new atomic reactivity index has been defined and compared with previous definitions.

  20. Skylab reactivation mission report

    NASA Technical Reports Server (NTRS)

    Chubb, W. B.

    1980-01-01

    On July 11, 1979, Skylab impacted the Earth's surface. The debris dispersion area stretched from the South Eastern Indian Ocean across a sparsely populated section of Western Australia. The events leading to the reentry of Skylab are discussed and a final assessment of the Skylab debris impact footprint is presented. Also included are detailed evaluations of the various Skylab systems that were reactivated when control of Skylab was regained in mid-1978 after having been powered down since February 4, 1974.

  1. Underground waste barrier structure

    DOEpatents

    Saha, Anuj J.; Grant, David C.

    1988-01-01

    Disclosed is an underground waste barrier structure that consists of waste material, a first container formed of activated carbonaceous material enclosing the waste material, a second container formed of zeolite enclosing the first container, and clay covering the second container. The underground waste barrier structure is constructed by forming a recessed area within the earth, lining the recessed area with a layer of clay, lining the clay with a layer of zeolite, lining the zeolite with a layer of activated carbonaceous material, placing the waste material within the lined recessed area, forming a ceiling over the waste material of a layer of activated carbonaceous material, a layer of zeolite, and a layer of clay, the layers in the ceiling cojoining with the respective layers forming the walls of the structure, and finally, covering the ceiling with earth.

  2. Reactive sintering and reactive hot

    NASA Astrophysics Data System (ADS)

    Murray, J. C.; German, R. M.

    1992-09-01

    NbAl3 has been synthesized from elemental powders by reactive sintering (RS) and reactive hot isostatic pressing (RHIP). Both processes involve a self-propagating exothermic reaction between the constituent powders to form an intermetallic compound. The RHIP approach uses simultaneous external pressurization to make a higher density product. This study focused on developing a method to use reactive synthesis to form high-density NbAl3 compacts. High RS and RHIP densities were possible with the appropriate raw materials and processing parameters. These include powder purity, particle sizes, degassing, heating rate, furnace temperature, and compaction pressures. Near full density was attained with RHIP, and up to 95 pct density was attained with RS.

  3. Barrier methods of contraception.

    PubMed

    Skrine, R L

    1985-05-01

    cervical mucus necessary for sperm transportation away from the acid vagina where the sperm is delayed and killed. The choice of available vaginal diaphragms is increasing. Despite some suggestion that the "fit" of a diaphragm is not crucial, supported by the argument that the vagina increses greatly in volume during intercourse, the best available figures for reliability are from studies of family planning clinic patients who have traditionally been fitted with great care. There are no good data about the effectiveness of the cervical and vault caps, and it is better to fit a diaphragm if this is possible. The Today polyurethane foam sponge is impregnated with the spermicide nonoxynol-9 and, as marketed, it is for use as often as desired up to 24 hours, plus 6 hours before final removal to ensure all vaginal sperm are killed. Condoms bearing the British Standards Institute Kitemark have been tested to a high standard an in view of the good results that can be obtained it seems likely that most failures are due to inefficient use. Advantages of barrier methods include some portection from sexually transmitted diseases and a reduction in the incidence of pelvic inflammatory disease.

  4. Mesoscopic Modeling of Reactive Transport Processes

    NASA Astrophysics Data System (ADS)

    Kang, Q.; Chen, L.; Deng, H.

    2012-12-01

    Reactive transport processes involving precipitation and/or dissolution are pervasive in geochemical, biological and engineered systems. Typical examples include self-assembled patterns such as Liesegang rings or bands, cones of stalactites in limestones caves, biofilm growth in aqueous environment, formation of mineral deposits in boilers and heat exchangers, uptake of toxic metal ions from polluted water by calcium carbonate, and mineral trapping of CO2. Compared to experimental studies, a numerical approach enables a systematic study of the reaction kinetics, mass transport, and mechanisms of nucleation and crystal growth, and hence provides a detailed description of reactive transport processes. In this study, we enhance a previously developed lattice Boltzmann pore-scale model by taking into account the nucleation process, and develop a mesoscopic approach to simulate reactive transport processes involving precipitation and/or dissolution of solid phases. The model is then used to simulate the formation of Liesegang precipitation patterns and investigate the effects of gel on the morphology of the precipitates. It is shown that this model can capture the porous structures of the precipitates and can account for the effects of the gel concentration and material. A wide range of precipitation patterns is predicted under different gel concentrations, including regular bands, treelike patterns, and for the first time with numerical models, transition patterns from regular bands to treelike patterns. The model is also applied to study the effect of secondary precipitate on the dissolution of primary mineral. Several types of dissolution and precipitation processes are identified based on the morphology and structures of the precipitates and on the extent to which the precipitates affect the dissolution of the primary mineral. Finally the model is applied to study the formation of pseudomorph. It is demonstrated for the first time by numerical simulation that a

  5. Barrier Formation

    PubMed Central

    Lyaruu, D.M.; Medina, J.F.; Sarvide, S.; Bervoets, T.J.M.; Everts, V.; DenBesten, P.; Smith, C.E.; Bronckers, A.L.J.J.

    2014-01-01

    Enamel fluorosis is an irreversible structural enamel defect following exposure to supraoptimal levels of fluoride during amelogenesis. We hypothesized that fluorosis is associated with excess release of protons during formation of hypermineralized lines in the mineralizing enamel matrix. We tested this concept by analyzing fluorotic enamel defects in wild-type mice and mice deficient in anion exchanger-2a,b (Ae2a,b), a transmembrane protein in maturation ameloblasts that exchanges extracellular Cl− for bicarbonate. Defects were more pronounced in fluorotic Ae2a,b−/− mice than in fluorotic heterozygous or wild-type mice. Phenotypes included a hypermineralized surface, extensive subsurface hypomineralization, and multiple hypermineralized lines in deeper enamel. Mineral content decreased in all fluoride-exposed and Ae2a,b−/− mice and was strongly correlated with Cl−. Exposure of enamel surfaces underlying maturation-stage ameloblasts to pH indicator dyes suggested the presence of diffusion barriers in fluorotic enamel. These results support the concept that fluoride stimulates hypermineralization at the mineralization front. This causes increased release of protons, which ameloblasts respond to by secreting more bicarbonates at the expense of Cl− levels in enamel. The fluoride-induced hypermineralized lines may form barriers that impede diffusion of proteins and mineral ions into the subsurface layers, thereby delaying biomineralization and causing retention of enamel matrix proteins. PMID:24170372

  6. 76 FR 38741 - Tenth Meeting: RTCA Special Committee 221: Aircraft Secondary Barriers and Alternative Flight...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... of RTCA Special Committee 221 meeting: Aircraft Secondary Barriers and Alternative Flight Deck... Special Committee 221: Aircraft Secondary Barriers and Alternative Flight Deck Security Procedures. DATES... Reports Incorporate Comments and Finalize New Document--Aircraft Secondary Barriers and Alternative...

  7. FORMATION PROCESSES AND CONSEQUENCES OF REACTIVE AND NON-REACTIVE MINERAL PRECIPITATES IN PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Mineral precipitates in zero-valent iron PRBs can be classified by formation processes into three groups: 1) those that result from changes in chemical conditions (i.e., change in pH, e.g., calcite); 2) those that are a consequence of microbial activity (i.e., sulfate reduction, ...

  8. What Is Reactive Arthritis?

    MedlinePlus

    ... Arthritis PDF Version Size: 69 KB November 2014 What is Reactive Arthritis? Fast Facts: An Easy-to- ... Information About Reactive Arthritis and Other Related Conditions What Causes Reactive Arthritis? Sometimes, reactive arthritis is set ...

  9. Effect of Al content, substrate temperature and nitrogen flow on the reactive magnetron co-sputtered nanostructure in TiAlN thin films intended for use as barrier material in DRAMs

    NASA Astrophysics Data System (ADS)

    Jalali, Reza; Parhizkar, Mojtaba; Bidadi, Hasan; Naghshara, Hamid; Hosseini, Seyd Reza; Jafari, Majid

    2015-03-01

    TiAlN thin films were deposited by using the reactive magnetron co-sputtering method whit individual Ti and Al targets, where the Ti and the Al targets were simultaneously powered by using DC and RF sources, respectively. the electrical resistivity and the structural and microstructural properties of the deposited TiAlN thin films and the effects of Al content, substrate temperature and nitrogen gas flow rate on those properties were investigated. At a low flow rate of nitrogen gas (0.51 sccm), the electrical resistivity of the films was found to increase with increasing AC power, but at a high flow rate of nitrogen gas, it was found to decrease. The structural and microstructural analyses performed by using X-ray diffraction and scanning electron microscopy (SEM) showed that with increasing substrate temperature from room temperature to 400 ℃, the films prepared at 400 ℃ have a crystalline structure while those prepared at room temperature had an amorphous nature. Also, the SEM analysis revealed that with decreasing AC power and increasing nitrogen flow rate, the size of the grains in the prepared films become larger.

  10. Addressing Identified Barriers Faced by Persons with Sensory Disabilities. Final Report of the Department for the Deaf and Hard of Hearing and the HJR 461 Task Force to the Governor and the General Assembly of Virginia. House Document No. 99.

    ERIC Educational Resources Information Center

    Virginia State Dept. for the Deaf and Hard of Hearing, Richmond.

    This report describes a special Virginia task force study of barriers faced by persons with sensory disabilities in emergency and law enforcement situations. Surveys were conducted of three populations: deaf and hard of hearing; blind and visually disabled; and PSAPs (public safety answering points--centers which answer 911 calls). The overriding…

  11. The 'reactive

    NASA Astrophysics Data System (ADS)

    Battista Piccardo, Giovanni; Guarnieri, Luisa

    2010-05-01

    The Ligurian ophiolitic peridotites [South Lanzo, Erro-Tobbio, Internal Ligurides and Corsica] are characterized by the abundance of spinel(Sp) peridotites showing depleted compositions and ranging from Cpx-poor Sp lherzolites to Sp harzburgites. They were recognized in the last decades as refractory residua by MORB-forming partial melting of the asthenosphere, and were similar to abyssal peridotites. Recent structural and compositional studies promoted a better understanding of their structural and compositional features and their genetic processes. In the field these depleted peridotites replace with primary contacts pyroxenite-bearing fertile Sp lherzolites that have been recognized as sub-continental lithospheric mantle. Field relationships evidence that decametric-hectometric bodies of pristine pyroxenite-veined lithospheric Sp lherzolites are preserved as structural remnants within the km-scale masses of depleted peridotites. The depleted peridotites show coarse-grained recrystallized textures and reaction micro-structures indicating pyroxene dissolution and olivine precipitation that have been considered as records of melt/peridotite interaction during reactive diffuse porous flow of undersaturated melts. They show, moreover, contrasting bulk and mineral chemistries that cannot be produced by simple partial melting and melt extraction. In particular, their bulk compositions are depleted in SiO2 and enriched in FeO with respect to refractory residua after any kind of partial melting, as calculated by Niu (1997), indicating that they cannot be formed by simple partial melting and melt extraction processes. Moreover, TiO2 content in Sp is usually significantly higher (up to 0.8-1.0 wt%) than typical TiO2 contents of spinels (usually < 0.1-0.2 wt %) in fertile mantle peridotites and melting refractory residua, indicating that spinel attained element equilibration with a Ti-bearing basaltic melt. The depleted peridotites usually show strongly variable Cpx modal

  12. Exposure, Uptake, and Barriers

    NASA Astrophysics Data System (ADS)

    Baeza-Squiban, Armelle; Lanone, Sophie

    The nanotechnologies market is booming, e.g., in the food industry (powder additives, etc.) and in medical applications (drug delivery, prosthetics, diagnostic imaging, etc.), but also in other industrial sectors, such as sports, construction, cosmetics, and so on. In this context, with an exponential increase in the number of current and future applications, it is particularly important to evaluate the problem of unintentional (i.e., non-medical) exposure to manufactured nanoparticles (so excluding nanoparticles found naturally in the environment). In this chapter, we begin by discussing the various parameters that must be taken into account in any serious assessment of exposure to man-made nanoparticles. We then list the potential routes by which nanoparticles might enter into the organism, and outline the mechanisms whereby they could get past the different biological barriers. Finally, we describe the biodistribution of nanoparticles in the organism and the way they are eliminated.

  13. Blood cells and endothelial barrier function

    PubMed Central

    Rodrigues, Stephen F; Granger, D Neil

    2015-01-01

    Abstract The barrier properties of endothelial cells are critical for the maintenance of water and protein balance between the intravascular and extravascular compartments. An impairment of endothelial barrier function has been implicated in the genesis and/or progression of a variety of pathological conditions, including pulmonary edema, ischemic stroke, neurodegenerative disorders, angioedema, sepsis and cancer. The altered barrier function in these conditions is often linked to the release of soluble mediators from resident cells (e.g., mast cells, macrophages) and/or recruited blood cells. The interaction of the mediators with receptors expressed on the surface of endothelial cells diminishes barrier function either by altering the expression of adhesive proteins in the inter-endothelial junctions, by altering the organization of the cytoskeleton, or both. Reactive oxygen species (ROS), proteolytic enzymes (e.g., matrix metalloproteinase, elastase), oncostatin M, and VEGF are part of a long list of mediators that have been implicated in endothelial barrier failure. In this review, we address the role of blood borne cells, including, neutrophils, lymphocytes, monocytes, and platelets, in the regulation of endothelial barrier function in health and disease. Attention is also devoted to new targets for therapeutic intervention in disease states with morbidity and mortality related to endothelial barrier dysfunction. PMID:25838983

  14. Pharmacological and alimentary alteration of the gastric barrier.

    PubMed

    Boltin, Doron; Niv, Yaron

    2014-12-01

    The gastric barrier contains several lines of defence which protect the epithelium from harmful microbes and toxins. Pre-mucosal defence mechanisms include secreted acid (HCl 0.1 mmol/L) and pepsin, which are capable of denaturing tissue. A tightly adherent mucous layer provides the next line of defence, and physically separates any potentially hazardous substance in the lumen from the mucosal surface. Apical secretion of HCO3(-) maintains a non-acidic microenvironment at the mucosal surface. Membrane-bound phospholipids repel soluble toxins, and sulphydryls scavenge reactive oxygen species. However, when noxious agents overwhelm these mechanisms, the epithelium is damaged. Herein, we discuss the pathological and physiological basis for several disease states which are associated with a breakdown in one or more components of the gastric barrier, including: Helicobacter pylori-associated gastritis, atrophic gastritis, stress-related mucosal disease, age-related gastropathy and portal hypertensive gastropathy. The effect of non-steroidal anti-inflammatory drugs and proton pump inhibitors on the gastric mucosa, is explored. Finally, we outline the alterations in mucosal defence caused by alcohol, caffeine, minerals and vitamins.

  15. Puncture detecting barrier materials

    DOEpatents

    Hermes, R.E.; Ramsey, D.R.; Stampfer, J.F.; Macdonald, J.M.

    1998-03-31

    A method and apparatus for continuous real-time monitoring of the integrity of protective barrier materials, particularly protective barriers against toxic, radioactive and biologically hazardous materials has been developed. Conductivity, resistivity or capacitance between conductive layers in the multilayer protective materials is measured by using leads connected to electrically conductive layers in the protective barrier material. The measured conductivity, resistivity or capacitance significantly changes upon a physical breach of the protective barrier material. 4 figs.

  16. Puncture detecting barrier materials

    DOEpatents

    Hermes, Robert E.; Ramsey, David R.; Stampfer, Joseph F.; Macdonald, John M.

    1998-01-01

    A method and apparatus for continuous real-time monitoring of the integrity of protective barrier materials, particularly protective barriers against toxic, radioactive and biologically hazardous materials has been developed. Conductivity, resistivity or capacitance between conductive layers in the multilayer protective materials is measured by using leads connected to electrically conductive layers in the protective barrier material. The measured conductivity, resistivity or capacitance significantly changes upon a physical breach of the protective barrier material.

  17. The Barriers Project.

    ERIC Educational Resources Information Center

    Confederation Coll. of Applied Arts and Technology, Thunder Bay (Ontario).

    In 1987, the Barriers Project was initiated by Confederation College of Applied Arts and Technology to engage 31 selected community colleges in Canada in an organized self-appraisal of institutional barriers to the enrollment of part-time credit students. From the outset, colleges were encouraged to limit their investigation to barriers over which…

  18. Extremal surface barriers

    NASA Astrophysics Data System (ADS)

    Engelhardt, Netta; Wall, Aron C.

    2014-03-01

    We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy.

  19. Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive Materials

    DTIC Science & Technology

    2015-11-30

    customized chemical gas generators based on novel energetic materials that will exhibit improved effectiveness, process stability, and fire safety...2015 Approved for Public Release; Distribution Unlimited Final Report: Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive Materials...Building, Room 209 El Paso, TX 79968 -0587 12-Sep-2015 ABSTRACT Final Report: Efficient and Safe Chemical Gas Generators with Nanocomposite Reactive

  20. Ductal barriers in mammary epithelium

    PubMed Central

    Owens, Mark B; Hill, Arnold DK; Hopkins, Ann M

    2013-01-01

    Tissue barriers play an integral role in the biology and pathobiology of mammary ductal epithelium. In normal breast physiology, tight and adherens junctions undergo dynamic changes in permeability in response to hormonal and other stimuli, while several of their proteins are directly involved in mammary tumorigenesis. This review describes first the structure of mammary ductal epithelial barriers and their role in normal mammary development, examining the cyclical changes in response to puberty, pregnancy, lactation and involution. It then examines the role of adherens and tight junctions and the participation of their constituent proteins in mammary tumorigenic functions such as migration, invasion and metastasis. Finally, it discusses the potential of these adhesion proteins as both prognostic biomarkers and potential therapeutic targets in breast cancer. PMID:24665412

  1. In situ formation of phosphate barriers in soil

    DOEpatents

    Moore, Robert C.

    2002-01-01

    Reactive barriers and methods for making reactive barriers in situ in soil for sequestering soil ontaminants including actinides and heavy metals. The barrier includes phosphate, and techniques are disclosed for forming specifically apatite barriers. The method includes injecting dilute reagents into soil in proximity to a contamination plume or source such as a waste drum to achieve complete or partial encapsulation of the waste. Controlled temperature and pH facilitates rapid formation of apatite, for example, where dilute aqueous calcium chloride and dilute aqueous sodium phosphate are the selected reagents. Mixing of reagents to form precipitate is mediated and enhanced through movement of reagents in soil as a result of phenomena including capillary action, movement of groundwater, soil washing and reagent injection pressure.

  2. Chemical gel barriers as low-cost alternative to containment and in situ cleanup of hazardous wastes to protect groundwater

    SciTech Connect

    1997-01-01

    Chemical gel barriers are being considered as a low-cost alternative for containment and in situ cleanup of hazardous wastes to protect groundwater. Most of the available gels in petroleum application are non-reactive and relative impermeable, providing a physical barriers for all fluids and contaminants. However, other potential systems can be envisioned. These systems could include gels that are chemically reactive and impermeable such that most phase are captured by the barriers but the contaminants could diffuse through the barriers. Another system that is chemically reactive and permeable could have potential applications in selectivity capturing contaminants while allowing water to pass through the barriers. This study focused on chemically reactive and permeable gel barriers. The gels used in experiment are DuPont LUDOX SM colloidal silica gel and Pfizer FLOPAAM 1330S hydrolyzed polyacrylamide (HPAM) gel.

  3. The use of NMR techniques for the analysis of water in coal and the effect of different coal drying techniques on the structure and reactivity of coal. Final report

    SciTech Connect

    Netzel, D.A.; Miknis, F.P.; Wallace, J.C. Jr.; Butcher, C.H.; Mitzel, J.M.; Turner, T.F.; Hurtubise, R.J.

    1995-02-01

    Western Research Institute has conducted a study of different methods of coal drying as pretreatment steps before liquefaction. The objectives of this study were to develop a combined chemical dehydration/nuclear magnetic resonance (NMR) method for measuring the moisture content of coal, to measure the changes in coal structure that occur during drying, and to determine the effects of different drying methods on liquefaction reactivity of coals. Different methods of drying were investigated to determine whether coal drying can be accomplished without reducing the reactivity of coals toward liquefaction. Drying methods included thermal, microwave, and chemical dehydration. Coals of rank lignite to high volatile bituminous were studied. Coals that were dried or partially dried thermally and with microwaves had lower liquefaction conversions than coals containing equilibrium moisture contents. However, chemically dried coals had conversions equal to or greater than the premoisturized coals. The conversion behavior is consistent with changes in the physical structure and cross linking reactions because of drying. Thermal and microwave drying appear to cause a collapse in the pore structure, thus preventing donor solvents such as tetralin from contacting reactive sites inside the coals. Chemical dehydration does not appear to collapse the pore structure. These results are supported by the solvent swelling measurements in which the swelling ratios of thermally dried and microwave-dried coals were lower than those of premoisturized coals, indicating a greater degree of cross linking in the dried coals. The swelling ratios of the chemically dried coals were greater than those of the premoisturized coals because the pore structure remaining unchanged or increased when water was removed. These results are consistent with the NMR results, which did not show significant changes in coal chemical structure.

  4. Effectiveness of predictive computer programs in the design of noise barriers. A before and after approach. Part 2-B: Supplement. The noise level data. Final Report, June 1975-June 1981

    SciTech Connect

    Haviland, J.K.; Noble, D.F.

    1981-06-01

    To evaluate the efficacy of the predictive computer programs used to design the barriers, noise measurements were taken before and after construction of an Earth berm and plywood wall alongside I-495 in Northern Virginia. Despite intrusive noise periodically overriding the traffic noise from I-495, the latter clearly dominated the neighborhood noise environment. Direct correlations made between variations in L10 levels and truck traffic and between L50 and L90 levels and automobile traffic seem to support the generalization that the L10 levels are controlled by trucks and the L90 levels are controlled by automobiles. See Part II-A for a description of the study and the discussion of the results.

  5. Permeable Reactive Barriers: Lessons Learned/New Directions

    DTIC Science & Technology

    2005-02-01

    uncertainties (those unknowns that confident decisions) and data uncertainties (sources of variation in s the CSM to evolve and mature as site work progresses...Once these goals and objectives are defined, a conceptual site model ( CSM ) is developed to incorporate existing knowledge about the site and to...establish what additional information and data are needed to achieve the goals. The CSM is expanded and improved as additional knowledge is obtained

  6. Development of Permeable Reactive Barriers (PRB) Using Edible Oils

    DTIC Science & Technology

    2008-06-01

    Remediation Technology Roundtable GC gas chromatograph GMO Glycerol Monooleate GRAS Generally Recognized As Safe H2O2 Hydrogen Peroxide HLB...polysorbate 21, polysorbate 85 (from UNIQUEMA) and a surfactant mixture (38% polysorbate 80, 56% glycerol monooleate ( GMO ) and 6% water from...the polysorbate 80- GMO mixture. The interfacial tension of the lecithin could not be measured because the low HLB prevented it from dissolving in

  7. Field Applications of In Situ Remediation Technologies: Permeable Reactive Barriers

    DTIC Science & Technology

    2002-01-01

    dweymann@ emconinc.com Caldwell Trucking Northern NJ 1998 TCE Hydraulic Fracturing , $1.12 M Fe0 Only 60% John Vidumsky Permeation Infilling...Oriented $1.15 M Granular No problems except Stephen H. Shoemaker Chloroform, Freon 11, Hydraulic Fracturing cast iron at recovering an Tel: 704-362...VC Massachusetts Falmouth, MA 1998 PCE, TCE Hydraulic Fracturing $160 K Fe0 Robert W. Gillham Military Reservation Tel: 519-888-4658 CS-10 Plume Fax

  8. A PERMEABLE REACTIVE BARRIER FOR TREATMENT OF HEAVY METALS

    EPA Science Inventory

    Historical storage of ore concentrate containing sulfide minerals at an industrial site in British Columbia, Canada has resulted in widespread contamination of the underlying soil and groundwater. The oxidation of sulfide minerals has released significant quantities of heavy met...

  9. Tunnelling without barriers

    SciTech Connect

    Lee, K.

    1987-01-01

    The evolution in flat and curved space-time of quantum fields in theories with relative flat potential and its consequences are considered. It is shown that bubble nucleation, a quantum mechanical tunnelling process, may occur in flat space-time, having a bounce solution, even if V(phi) has no barrier. It is shown that bubble nucleation can also occur in curved space-time even though there is no bounce solution in the standard formalism for the bubble nucleation rate in curved space-time. Additionally, bubbles can nucleate during the slow rolling period on the potential in flat and curved space-time, in this case also there is no bounce solution. It is known in the new inflationary scenario that energy density perturbations caused by quantum fluctuations of the scalar field can satisfy the presently observed bounds on density perturbations. Bubble nucleation during the slow rolling period also gives rise to density perturbations. For a model potential density perturbations by bubbles are calculated at the horizon reentering. By applying the bound from the almost isotropic microwave black body radiation on these density perturbations, a constraint on the model potential is obtained. Finally, some further implications on the galaxy formation and applications in more realistic potential are discussed.

  10. Multilayer moisture barrier

    DOEpatents

    Pankow, Joel W; Jorgensen, Gary J; Terwilliger, Kent M; Glick, Stephen H; Isomaki, Nora; Harkonen, Kari; Turkulainen, Tommy

    2015-04-21

    A moisture barrier, device or product having a moisture barrier or a method of fabricating a moisture barrier having at least a polymer layer, and interfacial layer, and a barrier layer. The polymer layer may be fabricated from any suitable polymer including, but not limited to, fluoropolymers such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), or ethylene-tetrafluoroethylene (ETFE). The interfacial layer may be formed by atomic layer deposition (ALD). In embodiments featuring an ALD interfacial layer, the deposited interfacial substance may be, but is not limited to, Al.sub.2O.sub.3, AlSiO.sub.x, TiO.sub.2, and an Al.sub.2O.sub.3/TiO.sub.2 laminate. The barrier layer associated with the interfacial layer may be deposited by plasma enhanced chemical vapor deposition (PECVD). The barrier layer may be a SiO.sub.xN.sub.y film.

  11. Barriers to screening mammography.

    PubMed

    Sarma, Elizabeth A

    2015-01-01

    Breast cancer (BRCA) is the second most commonly diagnosed cancer among women in the USA, and mammography is an effective means for the early detection of BRCA. Identifying the barriers to screening mammography can inform research, policy and practice aiming to increase mammography adherence. A literature review was conducted to determine common barriers to screening mammography adherence. PsycINFO and PubMed databases were searched to identify studies published between 2000 and 2012 that examined barriers associated with reduced mammography adherence. Three thematic groups of barriers, based on social ecology, were identified from the literature: healthcare system-level, social and individual-level barriers. Researchers must consider screening behaviour in context and, therefore, should simultaneously consider each level of barriers when attempting to understand screening behaviour and create interventions to increase mammography adherence.

  12. System for reactivating catalysts

    SciTech Connect

    Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

    2010-03-02

    A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst is provided. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

  13. Methods for fabricating a micro heat barrier

    DOEpatents

    Marshall, Albert C.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-01-06

    Methods for fabricating a highly effective, micron-scale micro heat barrier structure and process for manufacturing a micro heat barrier based on semiconductor and/or MEMS fabrication techniques. The micro heat barrier has an array of non-metallic, freestanding microsupports with a height less than 100 microns, attached to a substrate. An infrared reflective membrane (e.g., 1 micron gold) can be supported by the array of microsupports to provide radiation shielding. The micro heat barrier can be evacuated to eliminate gas phase heat conduction and convection. Semi-isotropic, reactive ion plasma etching can be used to create a microspike having a cusp-like shape with a sharp, pointed tip (<0.1 micron), to minimize the tip's contact area. A heat source can be placed directly on the microspikes. The micro heat barrier can have an apparent thermal conductivity in the range of 10.sup.-6 to 10.sup.-7 W/m-K. Multiple layers of reflective membranes can be used to increase thermal resistance.

  14. BIFUNCTIONAL ALUMINUN: A PERMEABLE BARRIER MATERIAL FOR THE DEGRADATION OF MTBE

    EPA Science Inventory

    Bifunctional aluminum is an innovative remedial material for the treatment of gasoline oxygenates in permeable reactive barriers (PRBs). PRBs represent a promising environmental technology for remediation of groundwater contamination. Although zero-valent metals (ZVM) have been...

  15. 100-NR-2 Apatite Treatability Test: An update on Barrier Performance

    SciTech Connect

    Fritz, Brad G.; Vermeul, Vincent R.; Fruchter, Jonathan S.; Szecsody, James E.; Williams, Mark D.

    2011-05-01

    This report updates a previous report covering the performance of a permeable reactive barrier installed at 100N. In this report we re-evaluate the results after having an additional year of performance monitoring data to incorporate.

  16. Low pressure stagnation flow reactor with a flow barrier

    DOEpatents

    Vosen, Steven R.

    2001-01-01

    A flow barrier disposed at the periphery of a workpiece for achieving uniform reaction across the surface of the workpiece, such as a semiconductor wafer, in a stagnation flow reactor operating under the conditions of a low pressure or low flow rate. The flow barrier is preferably in the shape of annulus and can include within the annular structure passages or flow channels for directing a secondary flow of gas substantially at the surface of a semiconductor workpiece. The flow barrier can be constructed of any material which is chemically inert to reactive gases flowing over the surface of the semiconductor workpiece.

  17. Pilot-scale tests of tuff gravel flow diversion barriers for Yucca Mountain

    SciTech Connect

    Conca, J.; Apted, M.; Kessler, J.; Kessler, J.

    1995-12-31

    This project conducts pilot-scale tests on potential sand/tuff gravel barrier designs and materials by measuring their hydraulic and barrier properties for use in modeling and final designs of possible diversion barriers at Yucca Mountain. The use of rubble composed of crushed paintbrush tuff (referred to as tuff gravel) in an engineered barrier around the waste packages can provide superior performance capabilities in a geologic repository located in the vadose zone. The effectiveness of unsaturated gravel as an hydraulic barrier to inflow of water from the surrounding environment is referred to by various names, e.g., diversion barrier, capillary barrier, or Richard`s barrier. A gravel barrier can also function as a diffusion barrier to the transport of ionic contaminants away from waste packages. Preliminary studies on tuff gravel and other gravel barriers have demonstrated their performance under a wide range of conditions anticipated in disposal scenarios.

  18. Skin Barrier Function and Allergens.

    PubMed

    Engebretsen, Kristiane Aasen; Thyssen, Jacob Pontoppidan

    2016-01-01

    The skin is an important barrier protecting us from mechanical insults, microorganisms, chemicals and allergens, but, importantly, also reducing water loss. A common hallmark for many dermatoses is a compromised skin barrier function, and one could suspect an elevated risk of contact sensitization (CS) and allergy following increased penetration of potential allergens. However, the relationship between common dermatoses such as psoriasis, atopic dermatitis (AD) and irritant contact dermatitis (ICD) and the development of contact allergy (CA) is complex, and depends on immunologic responses and skin barrier status. Psoriasis has traditionally been regarded a Th1-dominated disease, but the discovery of Th17 cells and IL-17 provides new and interesting information regarding the pathogenesis of the disease. Research suggests an inverse relationship between psoriasis and CA, possibly due to increased levels of Th17 cells and its associated cytokines. As for AD, a positive association to CS has been established in epidemiological studies, but is still unresolved. Experimental studies show, however, an inverse relationship between AD and CS. The opposing and antagonistic influences of Th1 (CS) and Th2 (AD) have been proposed as an explanation. Finally, there is convincing evidence that exposure to irritants increases the risk of CS, and patients with ICD are, therefore, at great risk of developing CA. Skin irritation leads to the release of IL-1 and TNF-α, which affects the function of antigen-presenting cells and promotes their migration to local lymph nodes, thus increasing the probability of CS and ultimately the development of CA.

  19. Transforming Education: Overcoming Barriers.

    ERIC Educational Resources Information Center

    David, Jane L.; Goren, Paul D.

    Barriers to progress in educational reform exist inside and outside the education system. Some arise where new practices encounter traditional expectations and boundaries, but others go much deeper than education, such as poverty, racism, local political conflicts, and human resistance to change. The following five categories of barriers are…

  20. OVERCOMING CULTURAL BARRIERS.

    ERIC Educational Resources Information Center

    BARRUTIA, RICHARD

    THE RELATIONSHIP OF LANGUAGE DEVELOPMENT TO CULTURAL BARRIERS AND THE TEACHING OF FOREIGN LANGUAGES IS DISCUSSED IN THIS ARTICLE. VARIOUS VIEWS OF THE MEANING OF CULTURE ARE MENTIONED IN ORDER TO SINGLE OUT ANTHROPOLOGICAL CULTURE AS A MAIN FOCAL POINT. INTERCULTURAL DIFFERENCES ARE SPELLED OUT WITH EXAMPLES OF LINGUISTIC BARRIERS, AND…

  1. Penetration resistant barrier

    DOEpatents

    Hoover, William R.; Mead, Keith E.; Street, Henry K.

    1977-01-01

    The disclosure relates to a barrier for resisting penetration by such as hand tools and oxy-acetylene cutting torches. The barrier comprises a layer of firebrick, which is preferably epoxy impregnated sandwiched between inner and outer layers of steel. Between the firebrick and steel are layers of resilient rubber-like filler.

  2. Liquid metal hydrogen barriers

    DOEpatents

    Grover, George M.; Frank, Thurman G.; Keddy, Edward S.

    1976-01-01

    Hydrogen barriers which comprise liquid metals in which the solubility of hydrogen is low and which have good thermal conductivities at operating temperatures of interest. Such barriers are useful in nuclear fuel elements containing a metal hydride moderator which has a substantial hydrogen dissociation pressure at reactor operating temperatures.

  3. Catalytic thermal barrier coatings

    DOEpatents

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  4. Retractable barrier strip

    DOEpatents

    Marts, Donna J.; Barker, Stacey G.; Wowczuk, Andrew; Vellenoweth, Thomas E.

    2002-01-01

    A portable barrier strip having retractable tire-puncture spikes for puncturing a vehicle tire. The tire-puncture spikes have an armed position for puncturing a tire and a retracted position for not puncturing a tire. The strip comprises a plurality of barrier blocks having the tire-puncture spikes removably disposed in a shaft that is rotatably disposed in each barrier block. The plurality of barrier blocks hare hingedly interconnected by complementary hinges integrally formed into the side of each barrier block which allow the strip to be rolled for easy storage and retrieval, but which prevent irregular or back bending of the strip. The shafts of adjacent barrier blocks are pivotally interconnected via a double hinged universal joint to accommodate irregularities in a roadway surface and to transmit torsional motion of the shaft from block to block. A single flexshaft cable is connected to the shaft of an end block to allow a user to selectively cause the shafts of a plurality of adjacently connected barrier blocks to rotate the tire-puncture spikes to the armed position for puncturing a vehicle tire, and to the retracted position for not puncturing the tire. The flexshaft is provided with a resiliently biased retracting mechanism, and a release latch for allowing the spikes to be quickly retracted after the intended vehicle tire is punctured.

  5. Vehicle barrier systems

    SciTech Connect

    Sena, P.A.

    1986-01-01

    The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper. 2 tabs.

  6. Vehicle barrier systems

    SciTech Connect

    Sena, P.A.

    1986-01-01

    The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment, and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper.

  7. Vehicle barrier systems

    SciTech Connect

    Sena, P.A.

    1986-01-01

    The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper.

  8. Counseling for barrier methods.

    PubMed

    Guest, F

    1979-08-01

    Despite the less serious risks of barrier methods (diaphragm, condom, foam, and other vaginal spermicides) compared with other contraceptive methods, many family planning programs find that only a minority of patients accept barrier methods as primary contraceptive choices. Some misconceptions patients have about barrier methods are: 1) they are less effective compared to oral contraceptives or IUDs, 2) foam kills sperm that are still inside a man's body, and 3) you need a prescription to use a barrier method. This article provides the following information about barrier methods to use in counseling patients: 1) couples who use barriers exactly right all the time can achieve high levels of effectiveness; average effectiveness rates for longterm users are 87% for the diaphragm, 90% for condoms, and 85% for foam; 2) noncontraceptive benefits include protection against sexually transmitted infections; barrier methods are nonhormonal and nonsurgical and posters to that effect are recommended for the counselor's waiting room; 3) patients need to be encouraged to use barrier methods even though they are less convenient in certain situations; support groups could improve patients' success; 4) counselors may be able to help users by giving them permission not to use the method on certain cycle days as a tradeoff for diligent use at other times thereby relieving the contraceptive burden; 5) recurring problems that patients should be warned about include waiting too late to put on a condom, running out of foam, using too little cream with the diaphragm, and douching after intercourse; and 6) improper care and storage problems which could cause failure are storing latex near heat, separating the foam bottle from the applicator, using old condoms and diaphragms, and suppositories that fail to melt. Patients' 2 biggest complaints about vaginal suppositories are messiness and irritation and switching to condoms can help. The last page of the article is a one page handout for

  9. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 1 - effects of solvents, catalysts and temperature conditions on conversion and structural changes of low-rank coals

    SciTech Connect

    Huang, Lili; Schobert, Harold H.; Song, Chunshan

    1998-01-01

    The main objectives of this project were to study the effects of low-temperature pretreatments on coal structure and their impacts on subsequent liquefaction. The effects of pretreatment temperatures, catalyst type, coal rank, and influence of solvent were examined. Specific objectives were to identify the basic changes in coal structure induced by catalytic and thermal pretreatments, and to determine the reactivity of the catalytically and thermally treated coals for liquefaction. In the original project management plan it was indicated that six coals would be used for the study. These were to include two each of bituminous, subbituminous, and lignite rank. For convenience in executing the experimental work, two parallel efforts were conducted. The first involved the two lignites and one subbituminous coal; and the second, the two bituminous coals and the remaining subbituminous coal. This Volume presents the results of the first portion of the work, studies on two lignites and one subbituminous coal. The remaining work accomplished under this project will be described and discussed in Volume 2 of this report. The objective of this portion of the project was to determine and compare the effects of solvents, catalysts and reaction conditions on coal liquefaction. Specifically, the improvements of reaction conversion, product distribution, as well as the structural changes in the coals and coal-derived products were examined. This study targeted at promoting hydrogenation of the coal-derived radicals, generated during thermal cleavage of chemical bonds, by using a good hydrogen donor-solvent and an effective catalyst. Attempts were also made in efforts to match the formation and hydrogenation of the free radicals and thus to prevent retrogressive reaction.

  10. Formation Processes and Impacts of Reactive and Nonreactive Minerals in Permeable Reactive Barriers

    EPA Science Inventory

    Mineral precipitates in zero-valent iron PRBs can be classified by formation processes into three groups: 1) those that result from changes in chemical conditions (i.e., changes in pH, e.g., calcite); 2) those that are a consequence of microbial activity (i.e., sulfate reduction,...

  11. Recycler barrier RF buckets

    SciTech Connect

    Bhat, C.M.; /Fermilab

    2011-03-01

    The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.

  12. Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    1993-01-01

    In order to reduce heat transfer between a hot gas heat source and a metallic engine component, a thermal insulating layer of material is placed between them. This thermal barrier coating is applied by plasma spray processing the thin films. The coating has been successfully employed in aerospace applications for many years. Lewis Research Center, a leader in the development engine components coating technology, has assisted Caterpillar, Inc. in applying ceramic thermal barrier coatings on engines. Because these large engines use heavy fuels containing vanadium, engine valve life is sharply decreased. The barrier coating controls temperatures, extends valve life and reduces operating cost. Additional applications are currently under development.

  13. Phenylethynyl reactive diluents

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor)

    1995-01-01

    A composition of matter having a specified general structure is employed to terminate a nucleophilic reagent, resulting in the exclusive production of phenylethynyl terminated reactive oligomers which display unique thermal characteristics. A reactive diluent having a specified general structure is employed to decrease the melt viscosity of a phenylethynyl terminated reactive oligomer and to subsequently react with to provide a thermosetting material of enhanced density. These materials have features which make them attractive candidates for use as composite matrices and adhesives.

  14. Barriers to Liposomal Gene Delivery: from Application Site to the Target

    PubMed Central

    Saffari, Mostafa; Moghimi, Hamid Reza; Dass, Crispin R

    2016-01-01

    Gene therapy is a therapeutic approach to deliver genetic material into cells to alter their function in entire organism. One promising form of gene delivery system (DDS) is liposomes. The success of liposome-mediated gene delivery is a multifactorial issue and well-designed liposomal systems might lead to optimized gene transfection particularly in vivo. Liposomal gene delivery systems face different barriers from their site of application to their target, which is inside the cells. These barriers include presystemic obstacles (epithelial barriers), systemic barriers in blood circulation and cellular barriers. Epithelial barriers differ depending on the route of administration. Systemic barriers include enzymatic degradation, binding and opsonisation. Both of these barriers can act as limiting hurdles that genetic material and their vector should overcome before reaching the cells. Finally liposomes should overcome cellular barriers that include cell entrance, endosomal escape and nuclear uptake. These barriers and their impact on liposomal gene delivery will be discussed in this review. PMID:28228799

  15. Optimistic barrier synchronization

    NASA Technical Reports Server (NTRS)

    Nicol, David M.

    1992-01-01

    Barrier synchronization is fundamental operation in parallel computation. In many contexts, at the point a processor enters a barrier it knows that it has already processed all the work required of it prior to synchronization. The alternative case, when a processor cannot enter a barrier with the assurance that it has already performed all the necessary pre-synchronization computation, is treated. The problem arises when the number of pre-sychronization messages to be received by a processor is unkown, for example, in a parallel discrete simulation or any other computation that is largely driven by an unpredictable exchange of messages. We describe an optimistic O(log sup 2 P) barrier algorithm for such problems, study its performance on a large-scale parallel system, and consider extensions to general associative reductions as well as associative parallel prefix computations.

  16. [Vascular endothelial Barrier Function].

    PubMed

    Ivanov, A N; Puchinyan, D M; Norkin, I A

    2015-01-01

    Endothelium is an important regulator of selective permeability of the vascular wall for different molecules and cells. This review summarizes current data on endothelial barrier function. Endothelial glycocalyx structure, its function and role in the molecular transport and leukocytes migration across the endothelial barrier are discussed. The mechanisms of transcellular transport of macromolecules and cell migration through endothelial cells are reviewed. Special section of this article addresses the structure and function of tight and adherens endothelial junction, as well as their importance for the regulation of paracellular transport across the endothelial barrier. Particular attention is paid to the signaling mechanism of endothelial barrier function regulation and the factors that influence on the vascular permeability.

  17. Great Barrier Reef

    Atmospheric Science Data Center

    2013-04-16

    article title:  Australia's Great Barrier Reef     View Larger Image ... reef, but a vast maze of reefs, passages, and coral cays (islands that are part of the reef). This nadir true-color image was acquired by ...

  18. Barrier Island Hazard Mapping.

    ERIC Educational Resources Information Center

    Pilkey, Orrin H.; Neal, William J.

    1980-01-01

    Describes efforts to evaluate and map the susceptibility of barrier islands to damage from storms, erosion, rising sea levels and other natural phenomena. Presented are criteria for assessing the safety and hazard potential of island developments. (WB)

  19. Role of Reactive Stroma in Prostate Cancer Progression

    DTIC Science & Technology

    2008-02-01

    AD_________________ Award Number: W81XWH-04-1-0189 TITLE: Role of Reactive Stroma in Prostate Cancer Progression PRINCIPAL INVESTIGATOR: David R...REPORT TYPE Final 3. DATES COVERED 12 JAN 2004 - 11 JAN 2008 4. TITLE AND SUBTITLE Role of Reactive Stroma in Prostate Cancer Progression 5a. CONTRACT...the reactive stroma of experimental prostate cancer . Using a modified approach, we are placing an inducible Cre recombinase behind the FAP gene

  20. Applications of barrier bucket RF systems at Fermilab

    SciTech Connect

    Bhat, C.M.; /Fermilab

    2006-03-01

    In recent years, the barrier rf systems have become important tools in a variety of beam manipulation applications at synchrotrons. Four out of six proton synchrotrons at Fermilab are equipped with broad-band barrier rf systems. All of the beam manipulations pertaining to the longitudinal phase space in the Fermilab Recycler (synchrotron used for antiproton storage) are carried out using a barrier system. Recently, a number of new applications of barrier rf systems have been developed- the longitudinal momentum mining, longitudinal phase-space coating, antiproton stacking, fast bunch compression and more. Some of these techniques have been critical for the recent spectacular success of the collider performance at the Fermilab Tevatron. Barrier bunch coalescing to produce bright proton bunches has a high potential to increase proton antiproton luminosity significantly. In this paper, I will describe some of these techniques in detail. Finally, I make a few general remarks on issues related to barrier systems.

  1. Curvature Dependent Reactivity of Fullerenes and Nanotubes

    NASA Technical Reports Server (NTRS)

    Park, Seongjun; Cho, Kyeongjae; Srivastava, Deepak

    2000-01-01

    Dependence of pyramidalization angle, examples of nanotube surfaces, internal and external reactivity, and binding energies are some of the topics discussed in this conference presentation preprint. Final conclusions include the relationship between the pyramidal angle of the surface and its associated external reaction energy.

  2. Production of reactive sintered nickel aluminide

    SciTech Connect

    1995-10-01

    This is the final report pertaining to the development of aluminides by reactive synthesis. Included in this report is an overview of results during the scope of this effort, details on specific task accomplishments, and a summary of customer evaluations. Opportunities for future work are also included at the end of this report.

  3. Performance characteristics of a self-sealing/self-healing barrier

    SciTech Connect

    McGregor, R.G. |; Stegemann, J.A.

    1997-12-31

    Environment Canada and the Netherlands Energy Research Foundation are co-developers of a patented Self-Sealing/Self-Healing (SS/SH) Barrier system for containment of wastes which is licensed to Water Technology International Corporation. The SS/SH Barrier is intended for use as either a liner or cover for landfills, contaminated sites, secondary containment areas, etc., in the industrial, chemical, mining and municipal sectors, and also as a barrier to hydraulic flow for the transportation and construction industry. The SS/SH Barrier`s most significant feature is its capability for self-repair in the event of a breach. By contrast, conventional barrier systems, such as clay, geomembrane, or geosynthetic clay liners can not be repaired without laborious excavation and reconstruction. Laboratory investigations have shown that the SS/SH Barrier concept will function with a variety of reactive materials. Self-Sealing/Self-Healing Barriers are cost competitive and consistently exhibit hydraulic conductivities ranging from 10{sup -9} to 10{sup -13} m/s, which decrease with time. These measurements meet or exceed the recommended hydraulic conductivity required by EPA for clay liners (<1x10{sup -9} m/s) used in landfills and hazardous waste sites. Results of mineralogical examination of the seal, diffusion testing, hydraulic conductivity measurement, and durability testing, including wet/dry, freeze/thaw cycling and leachate compatibility are also presented.

  4. Retractable barrier strip

    DOEpatents

    Marts, D.J.; Barker, S.G.; McQueen, M.A.

    1996-04-16

    A portable barrier strip is described having retractable tire-puncture means for puncturing a vehicle tire. The tire-puncture means, such as spikes, have an armed position for puncturing a tire and a retracted position for not puncturing a tire. The strip comprises a plurality of barrier blocks having the tire-puncture means removably disposed in a shaft that is rotatably disposed in each barrier block. The shaft removably and pivotally interconnects the plurality of barrier blocks. Actuation cables cause the shaft to rotate the tire-puncture means to the armed position for puncturing a vehicle tire and to the retracted position for not puncturing the tire. Each tire-puncture means is received in a hollow-bed portion of its respective barrier block when in the retracted position. The barrier strip rests in its deployed position and substantially motionless as a tire rolls thereon and over. The strip is rolled up for retrieval, portability, and storage purposes, and extended and unrolled in its deployed position for use. 13 figs.

  5. Retractable barrier strip

    DOEpatents

    Marts, Donna J.; Barker, Stacey G.; McQueen, Miles A.

    1996-01-01

    A portable barrier strip having retractable tire-puncture means for puncturing a vehicle tire. The tire-puncture means, such as spikes, have an armed position for puncturing a tire and a retracted position for not puncturing a tire. The strip comprises a plurality of barrier blocks having the tire-puncture means removably disposed in a shaft that is rotatably disposed in each barrier block. The shaft removably and pivotally interconnects the plurality of barrier blocks. Actuation cables cause the shaft to rotate the tire-puncture means to the armed position for puncturing a vehicle tire and to the retracted position for not puncturing the tire. Each tire-puncture means is received in a hollow-bed portion of its respective barrier block when in the retracted position. The barrier strip rests stable in its deployed position and substantially motionless as a tire rolls thereon and over. The strip is rolled up for retrieval, portability, and storage purposes, and extended and unrolled in its deployed position for use.

  6. Environmentally stable reactive alloy powders and method of making same

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Terpstra, R.L.

    1998-09-22

    Apparatus and method are disclosed for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloys needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment. 7 figs.

  7. Apparatus for making environmentally stable reactive alloy powders

    DOEpatents

    Anderson, I.E.; Lograsso, B.K.; Terpstra, R.L.

    1996-12-31

    Apparatus and method are disclosed for making powder from a metallic melt by atomizing the melt to form droplets and reacting the droplets downstream of the atomizing location with a reactive gas. The droplets are reacted with the gas at a temperature where a solidified exterior surface is formed thereon and where a protective refractory barrier layer (reaction layer) is formed whose penetration into the droplets is limited by the presence of the solidified surface so as to avoid selective reduction of key reactive alloyants needed to achieve desired powder end use properties. The barrier layer protects the reactive powder particles from environmental constituents such as air and water in the liquid or vapor form during subsequent fabrication of the powder to end-use shapes and during use in the intended service environment. 7 figs.

  8. Vacuum barrier for excimer lasers

    DOEpatents

    Shurter, Roger P.

    1992-01-01

    A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

  9. Vacuum barrier for excimer lasers

    DOEpatents

    Shurter, R.P.

    1992-09-15

    A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput. 3 figs.

  10. Control of tunnel barriers in multi-wall carbon nanotubes using focused ion beam irradiation.

    PubMed

    Tomizawa, H; Suzuki, K; Yamaguchi, T; Akita, S; Ishibashi, K

    2017-04-21

    We have formed tunnel barriers in individual multi-wall carbon nanotubes using the Ga focused ion beam irradiation. The barrier height was estimated by the temperature dependence of the current (Arrhenius plot) and the current-voltage curves (Fowler-Nordheim plot). It is shown that the barrier height has a strong correlation with the barrier resistance that is controlled by the dose. Possible origins for the variation in observed barrier characteristics are discussed. Finally, the single electron transistor with two barriers is demonstrated.

  11. Pseudomonas aeruginosa: breaking down barriers.

    PubMed

    Berube, Bryan J; Rangel, Stephanie M; Hauser, Alan R

    2016-02-01

    Many bacterial pathogens have evolved ingenious ways to escape from the lung during pneumonia to cause bacteremia. Unfortunately, the clinical consequences of this spread to the bloodstream are frequently dire. It is therefore important to understand the molecular mechanisms used by pathogens to breach the lung barrier. We have recently shown that Pseudomonas aeruginosa, one of the leading causes of hospital-acquired pneumonia, utilizes the type III secretion system effector ExoS to intoxicate pulmonary epithelial cells. Injection of these cells leads to localized disruption of the pulmonary-vascular barrier and dissemination of P. aeruginosa to the bloodstream. We put these data in the context of previous studies to provide a holistic model of P. aeruginosa dissemination from the lung. Finally, we compare P. aeruginosa dissemination to that of other bacteria to highlight the complexity of bacterial pneumonia. Although respiratory pathogens use distinct and intricate strategies to escape from the lungs, a thorough understanding of these processes can lay the foundation for new therapeutic approaches for bacterial pneumonia.

  12. Amorphous Ternary Diffusion Barriers for Silicon Metallizations

    NASA Astrophysics Data System (ADS)

    Reid, Jason Sven

    1995-01-01

    Reactively sputtered from transition-metal silicide or boride targets in Ar/N_2 discharges, thin amorphous films of TM-Si-N (TM = Mo, Ta, Ti, or W) and W-B-N are investigated. Resistivity, density, stress, and structure are given as functions of composition, and in some cases, temperature. Transmission electron microscopy shows that most of the films are marginally amorphous with the scale of local order ranging from 0.5 to 1.5 nm. Small -angle scattering measurements reveal chemically dissimilary regions in the films. When fully nitrided, Si appears to be preferentially bonded to nitrogen in the form of Si_3N_4 in the TM-Si-N films, according to extended energy loss fine structure (EXELFS) measurements. By tests on shallow-junction diodes, 100-nm thick TM-Si-N barriers are able to prevent aluminum overlayers from spiking the Si substrate at temperatures above aluminum's melting point, 660^circC. The exceptional stability is partly attributable to a 3 nm, self-sealing AlN layer which grows at the TM-Si-N/Al interface. The performance of the TM-Si-N and W-B-N barriers with copper overlayers is equally impressive. At the proper compositions, 100-nm barriers prevent copper from diffusing into the junction at 800^circC or higher for a 30-min vacuum annealing. Diode failure typically corresponds to the crystallization temperature of the barrier, which can be reduced by the presence of copper. Preliminary diffusion measurements of Cu in Ta _{36}Si_ {14}N_{50} films by SIMS yield an approximate diffusivity constant of D_{CU} = (0.014 cm ^2/s) times exp(-2.7 eV/kT). A 10-nm-thick TM-Si-N barrier with a Cu overlayer on MOS capacitors reveals no penetration of Cu into SiO_2 during an 80 h bias-thermal-stress at 300^circ C and 1 MV/cm applied field. Through a microscopic four-point probe lithographically defined on a Cu/barrier/Cu trilayer stack, the specific contact resistances of barrier/Cu interfaces are determined for TM-Si-N, TiN, and W barriers. In all instances, the

  13. MENDING THE IN SITU MANIPULATION BARRIER

    SciTech Connect

    PETERSEN, S.W.

    2006-02-06

    In early 2004, the U.S. Department of Energy (DOE) Richland and Fluor Hanford requested technical assistance from the DOE Headquarters EM-23 Technical Assistance Program to provide a team of technical experts to develop recommendations for mending the In Situ Redox Manipulation (ISRM) Barrier in the 100-D Area of the Hanford Site in Washington State. To accommodate this request, EM-23 provided support to convene a group of technical experts from industry, a national laboratory, and a DOE site to participate in a 2 1/2-day workshop with the objective of identifying and recommending options to enhance the performance of the 100-D Area reactive barrier and of a planned extension to the northeast. This report provides written documentation of the team's findings and recommendations. In 1995, a plume of dissolved hexavalent chromium [Cr(VI)], which resulted from operation of the D/DR Reactors at the Hanford site, was discovered along the Columbia River shoreline and in the 100-D Area. Between 1999 and 2003, a reactive barrier using the In Situ Redox Manipulation (ISRM) technology, was installed a distance of 680 meters along the river to reduce the Cr(VI) in the groundwater. The ISRM technology creates a treatment zone within the aquifer by injection of sodium dithionite, a strong reducing agent that scavenges dissolved oxygen (DO) from the aquifer and reduces ferric iron [Fe(III)], related metals, and oxy-ions. The reduction of Fe(III) to ferrous [Fe(II)] iron provides the primary reduction capacity to reduce Cr(VI) to the +3 state, which is less mobile and less toxic. Bench-scale and field-scale treatability tests were initially conducted to demonstrate proof-of principle and to provide data for estimation of barrier longevity. These calculations estimated barrier longevity in excess of twenty years. However, several years after initial and secondary treatment, groundwater in a number of wells has been found to contain elevated chromium (Cr) concentrations, indicating

  14. Method of installing subsurface barrier

    SciTech Connect

    Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

    2007-10-09

    Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

  15. Intestinal Barrier and Behavior.

    PubMed

    Julio-Pieper, M; Bravo, J A

    2016-01-01

    The intestinal barrier function contributes to gut homeostasis by modulating absorption of water, electrolytes, and nutrients from the lumen into the circulation while restricting the passage of noxious luminal substances and microorganisms. Chronic conditions such as rheumatoid arthritis, inflammatory bowel disease, and celiac disease are associated to intestinal barrier dysfunction. Here, the hypothesis is that a leaky intestinal wall allowing for indiscriminate passage of intraluminal compounds to the vascular compartment could in turn lead to systemic inflammation. An increasing number of studies are now investigating the association between gut permeability and CNS disorders, under the premise that translocation of intestinal luminal contents could affect CNS function, either directly or indirectly. Still, it is unknown whether disruption of intestinal barrier is a causative agent or a consequence in these situations. Here, we discuss the latest evidence pointing to an association between increased gut permeability and disrupted behavioral responses.

  16. Skin barrier in rosacea.

    PubMed

    Addor, Flavia Alvim Sant'Anna

    2016-01-01

    Recent studies about the cutaneous barrier demonstrated consistent evidence that the stratum corneum is a metabolically active structure and also has adaptive functions, may play a regulatory role in the inflammatory response with activation of keratinocytes, angiogenesis and fibroplasia, whose intensity depends primarily on the intensity the stimulus. There are few studies investigating the abnormalities of the skin barrier in rosacea, but the existing data already show that there are changes resulting from inflammation, which can generate a vicious circle caused a prolongation of flare-ups and worsening of symptoms. This article aims to gather the most relevant literature data about the characteristics and effects of the state of the skin barrier in rosacea.

  17. Skin barrier in rosacea*

    PubMed Central

    Addor, Flavia Alvim Sant'Anna

    2016-01-01

    Recent studies about the cutaneous barrier demonstrated consistent evidence that the stratum corneum is a metabolically active structure and also has adaptive functions, may play a regulatory role in the inflammatory response with activation of keratinocytes, angiogenesis and fibroplasia, whose intensity depends primarily on the intensity the stimulus. There are few studies investigating the abnormalities of the skin barrier in rosacea, but the existing data already show that there are changes resulting from inflammation, which can generate a vicious circle caused a prolongation of flare-ups and worsening of symptoms. This article aims to gather the most relevant literature data about the characteristics and effects of the state of the skin barrier in rosacea. PMID:26982780

  18. Thermal barrier coating system

    NASA Technical Reports Server (NTRS)

    Stecura, S. (Inventor)

    1984-01-01

    A high temperature oxidation resistant, thermal barrier coating system is disclosed for a nickel cobalt, or iron base alloy substrate. An inner metal bond coating contacts the substrate, and a thermal barrier coating covers the bond coating. NiCrAlR, FeCrAlR, and CoCrAlR alloys are satisfactory as bond coating compositions where R=Y or Yb. These alloys contain, by weight, 24.9-36.7% chromium, 5.4-18.5% aluminum, and 0.05 to 1.55% yttrium or 0.05 to 0.53% ytterbium. The coatings containing ytterbium are preferred over those containing yttrium. An outer thermal barrier coating of partial stabilized zirconium oxide (zirconia) which is between 6% and 8%, by weight, of yttrium oxide (yttria) covers the bond coating. Partial stabilization provides a material with superior durability. Partially stabilized zirconia consists of mixtures of cubic, tetragonal, and monoclinic phases.

  19. Ice barrier construction

    SciTech Connect

    Finucane, R. G.; Jahns, H. O.

    1985-06-18

    A method is provided for constructing spray ice barriers to protect offshore structures in a frigid body of water from mobile ice, waves and currents. Water is withdrawn from the body of water and is sprayed through ambient air which is below the freezing temperature of the water so that a substantial amount of the water freezes as it passes through the air. The sprayed water is directed to build up a mass of ice having a size and shape adapted to protect the offshore structure. Spray ice barriers can also be constructed for the containment of pollutant spills.

  20. Barriers to cancer screening.

    PubMed

    Womeodu, R J; Bailey, J E

    1996-01-01

    Many barriers to cancer screening have been summarized and discussed. Barriers have been documented in all patient populations, but some groups such as ethnic minorities and the elderly face unique barriers. The barriers to cancer screening, are multifactorial, but much of the responsibility for change must lie with health care providers and the health care delivery industry. This is not to free the patient of all responsibility, but some significant barriers are beyond their direct control. Take, for example, socioeconomic status, disease knowledge, and culturally related perceptions and myths about cancer detection and treatment. The health care industry must do a better job identifying and overcoming these barriers. The significant effects of provider counseling and advice must not be underestimated. Patients must first be advised, and then further actions must be taken if they reject the screening advice. Did they refuse adherence to recommendations because they do not view themselves as susceptible, because of overwhelming personal barriers, or because of a fatalistic attitude toward cancer detection and treatment? If that is the case, physicians and health care institutions must attempt to change perceptions, educate, and personalize the message so that patients accept their disease susceptibility [table: see text]. Multiple patient and provider risk factors have been identified that can be used to target patients particularly at high risk for inadequate cancer screening and providers at high risk for performing inadequate screening. Research has clearly demonstrated the effectiveness of interventions to improve tracking of patient and physician compliance with screening recommendations. Further research is needed to show the impact of managed-care penetration and payer status on screening efforts, and incentive schemes need to be tested that reward institutions and third-party payers who develop uniform standards and procedures for cancer screening. The

  1. Thermal Barrier Coating Workshop

    NASA Technical Reports Server (NTRS)

    Brindley, W. J. (Compiler); Lee, W. Y. (Compiler); Goedjen, J. G. (Compiler); Dapkunas, S. J. (Compiler)

    1995-01-01

    This document contains the agenda and presentation abstracts for the Thermal Barrier Coating Workshop, sponsored by NASA, DOE, and NIST. The workshop covered thermal barrier coating (TBC) issues related to applications, processing, properties, and modeling. The intent of the workshop was to highlight the state of knowledge on TBC's and to identify critical gaps in knowledge that may hinder TBC use in advanced applications. The workshop goals were achieved through presentations by 22 speakers representing industry, academia, and government as well as through extensive discussion periods.

  2. Thermal barrier coating system

    NASA Technical Reports Server (NTRS)

    Stecura, S.; Leibert, C. H. (Inventor)

    1977-01-01

    A coating system which contains a bond coating and a thermal barrier coating is applied to metal surfaces such as turbine blades and provides both low thermal conductivity and improved adherence when exposed to high temperature gases or liquids. The bond coating contains NiCrAlY and the thermal barrier coating contains a reflective oxide. The reflective oxides ZrO2-Y2O3 and ZrO2-MgO have demonstrated significant utility in high temperature turbine applications.

  3. 78 FR 59475 - Architectural Barriers Act Accessibility Guidelines; Outdoor Developed Areas

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-26

    ...We, the Architectural and Transportation Barriers Compliance Board (Access Board), are issuing a final rule that amends the Architectural Barriers Act Accessibility Guidelines by adding scoping and technical requirements for camping facilities, picnic facilities, viewing areas, trails, and beach access routes constructed or altered by or on behalf of federal agencies. The final rule ensures......

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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.

  6. When is arthritis reactive?

    PubMed Central

    Hamdulay, S S; Glynne, S J; Keat, A

    2006-01-01

    Reactive arthritis is an important cause of lower limb oligoarthritis, mainly in young adults. It is one of the spondyloarthropathy family; it is distinguishable from other forms of inflammatory arthritis by virtue of the distribution of affected sites and the high prevalence of characteristic extra‐articular lesions. Many terms have been used to refer to this and related forms of arthritis leading to some confusion. Reactive arthritis is precipitated by an infection at a distant site and genetic susceptibility is marked by possession of the HLA‐B27 gene, although the mechanism remains uncertain. Diagnosis is a two stage process and requires demonstration of a temporal link with a recognised “trigger” infection. The identification and management of “sexually acquired” and “enteric” forms of reactive arthritis are considered. Putative links with HIV infection are also discussed. The clinical features, approach to investigation, diagnosis, and management of reactive arthritis are reviewed. PMID:16822921

  7. Thermal barrier coating

    DOEpatents

    Bowker, Jeffrey Charles; Sabol, Stephen M.; Goedjen, John G.

    2001-01-01

    A thermal barrier coating for hot gas path components of a combustion turbine based on a zirconia-scandia system. A layer of zirconium scandate having the hexagonal Zr.sub.3 Sc.sub.4 O.sub.12 structure is formed directly on a superalloy substrate or on a bond coat formed on the substrate.

  8. The Fission Barrier Landscape

    SciTech Connect

    Phair, L.; Moretto, L. G.

    2008-04-17

    Fission excitation functions have been measured for a chain of neighboring compound nuclei from {sup 207}Po to {sup 212}Po. We present a new analysis which provides a determination of the fission barriers and ground state shell effects with nearly spectroscopic accuracy. The accuracy achieved in this analysis may lead to a future detailed exploration of the saddle mass surface and its spectroscopy.

  9. Thermal barrier coating system

    NASA Technical Reports Server (NTRS)

    Stecura, S. (Inventor)

    1985-01-01

    An oxide thermal barrier coating comprises ZrO3-Yb2O3 that is plasma sprayed onto a previously applied bond coating. The zirconia is partially stabilized with about 124 w/o ytterbia to insure cubic, monoclinic, and terragonal phases.

  10. Barriers Regarding Using Technology

    ERIC Educational Resources Information Center

    Boekenoogen, John Russell

    2014-01-01

    The University of Florida (UF) used an open-source course management system (CMS) called Sakai. Sakai was the fourth CMS the university has used to help teach live, blended (or hybrid), and online courses over the past ten years. The objective of this dissertation was to identify what barriers may be preventing university personnel from using…

  11. Overcoming Language Barriers

    PubMed Central

    De Buda, Yvonne

    1976-01-01

    Many family physicians in Canada experience language and cultural barriers between themselves and their patients. Several aspects of the ensuing problems are described and some practical suggestions for solutions are made. The importance of health education for new Canadians in the family physician's office as well as through the media and community projects is stressed. Imagesp68-ap68-bp70-a PMID:21308059

  12. Great Barrier Reef

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A better than average view of the Great Barrier Reef was captured by SeaWiFS on a recent overpass. There is sunglint northeast of the reef and there appears to be some sort of filamentous bloom in the Capricorn Channel.

  13. Final Report

    SciTech Connect

    Gurney, Kevin R.

    2015-01-12

    This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

  14. Final Report

    SciTech Connect

    DeTar, Carleton

    2012-12-10

    This document constitutes the Final Report for award DE-FC02-06ER41446 as required by the Office of Science. It summarizes accomplishments and provides copies of scientific publications with significant contribution from this award.

  15. Reactive Collision Avoidance Algorithm

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

    2010-01-01

    The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on

  16. Barrier Coatings for Refractory Metals and Superalloys

    SciTech Connect

    SM Sabol; BT Randall; JD Edington; CJ Larkin; BJ Close

    2006-02-23

    In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life.

  17. Stability of barrier buckets with short barrier separations

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2005-04-01

    A barrier bucket with very short or zero rf-barrier separation (relative to the barrier widths) has its synchrotron tune decreasing from a very large value towards the bucket boundary. As a result, chaotic region may form near the bucket center and extends outward under increasing modulation of rf voltage and/or rf phase. Application is made to those barrier buckets used in momentum mining at the Fermilab Recycler Ring.

  18. Integrating planning and reactive control

    NASA Technical Reports Server (NTRS)

    Wilkins, David E.; Myers, Karen L.

    1994-01-01

    Our research is developing persistent agents that can achieve complex tasks in dynamic and uncertain environments. We refer to such agents as taskable, reactive agents. An agent of this type requires a number of capabilities. The ability to execute complex tasks necessitates the use of strategic plans for accomplishing tasks; hence, the agent must be able to synthesize new plans at run time. The dynamic nature of the environment requires that the agent be able to deal with unpredictable changes in its world. As such, agents must be able to react to unanticipated events by taking appropriate actions in a timely manner, while continuing activities that support current goals. The unpredictability of the world could lead to failure of plans generated for individual tasks. Agents must have the ability to recover from failures by adapting their activities to the new situation, or replanning if the world changes sufficiently. Finally, the agent should be able to perform in the face of uncertainty. The Cypress system, described here, provides a framework for creating taskable, reactive agents. Several features distinguish our approach: (1) the generation and execution of complex plans with parallel actions; (2) the integration of goal-driven and event driven activities during execution; (3) the use of evidential reasoning for dealing with uncertainty; and (4) the use of replanning to handle run-time execution problems. Our model for a taskable, reactive agent has two main intelligent components, an executor and a planner. The two components share a library of possible actions that the system can take. The library encompasses a full range of action representations, including plans, planning operators, and executable procedures such as predefined standard operating procedures (SOP's). These three classes of actions span multiple levels of abstraction.

  19. Reactive Power Compensator.

    DOEpatents

    El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

    1992-07-28

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

  20. Reactive power compensator

    DOEpatents

    El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  1. Surface barrier research at the Hanford Site

    SciTech Connect

    Gee, G.W.; Ward, A.L.; Fayer, M.J.

    1997-12-31

    At the DOE Hanford Site, a field-scale prototype surface barrier was constructed in 1994 over an existing waste site as a part of a CERCLA treatability test. The above-grade barrier consists of a fine-soil layer overlying coarse layers of sands, gravels, basalt rock (riprap), and a low permeability asphalt layer. Two sideslope configurations, clean-fill gravel on a 10:1 slope and basalt riprap on a 2:1 slope, were built and are being tested. Design considerations included: constructability; drainage and water balance monitoring, wind and water erosion control and monitoring; surface revegetation and biotic intrusion; subsidence and sideslope stability, and durability of the asphalt layer. The barrier is currently in the final year of a three-year test designed to answer specific questions related to stability and long-term performance. One half of the barrier is irrigated such that the total water applied, including precipitation, is 480 mm/yr (three times the long-term annual average). Each year for the past two years, an extreme precipitation event (71 mm in 8 hr) representing a 1,000-yr return storm was applied in late March, when soil water storage was at a maximum. While the protective sideslopes have drained significant amounts of water, the soil cover (2-m of silt-loam soil overlying coarse sand and rock) has never drained. During the past year there was no measurable surface runoff or wind erosion. This is attributed to extensive revegetation of the surface. In addition, the barrier elevation has shown a small increase of 2 to 3 cm that is attributed to a combination of root proliferation and freeze/thaw activity. Testing will continue through September 1997. Performance data from the prototype barrier will be used by DOE in site-closure decisions at Hanford.

  2. Chaotic correlations in barrier billiards with arbitrary barriers

    NASA Astrophysics Data System (ADS)

    Osbaldestin, A. H.; Adamson, L. N. C.

    2013-06-01

    We study autocorrelation functions in symmetric barrier billiards for golden mean trajectories with arbitrary barriers. Renormalization analysis reveals the presence of a chaotic invariant set and thus that, for a typical barrier, there are chaotic correlations. The chaotic renormalization set is the analogue of the so-called orchid that arises in a generalized Harper equation.

  3. Apoplastic Diffusion Barriers in Arabidopsis

    PubMed Central

    Schreiber, Lukas; Franke, Rochus Benni; Geldner, Niko; Reina-Pinto, José J.; Kunst, Ljerka

    2013-01-01

    During the development of Arabidopsis and other land plants, diffusion barriers are formed in the apoplast of specialized tissues within a variety of plant organs. While the cuticle of the epidermis is the primary diffusion barrier in the shoot, the Casparian strips and suberin lamellae of the endodermis and the periderm represent the diffusion barriers in the root. Different classes of molecules contribute to the formation of extracellular diffusion barriers in an organ- and tissue-specific manner. Cutin and wax are the major components of the cuticle, lignin forms the early Casparian strip, and suberin is deposited in the stage II endodermis and the periderm. The current status of our understanding of the relationships between the chemical structure, ultrastructure and physiological functions of plant diffusion barriers is discussed. Specific aspects of the synthesis of diffusion barrier components and protocols that can be used for the assessment of barrier function and important barrier properties are also presented. PMID:24465172

  4. Work reengineering: the benefits and the barriers, an analytical review.

    PubMed

    Murphy, R

    1995-01-01

    Hospital executives who are considering patient centered care (PCC) delivery models are undertaking a fascinating and sometimes frightening journey. Although the benefits are many, several barriers are often encountered on the way to achieving successful results. Many hospitals begin this initiative with enthusiasm and optimism because it makes so much sense. However, fear of change can set in when barriers overcome the motivation to proceed. This paper explores both the benefits and strategies for successfully overcoming the barriers. In the final analysis, each hospital's executive team must answer the call to this challenge. Their decisions hold the future of their hospital in the balance.

  5. Reactive modelling of 1,2-DCA and DOC near the shoreline.

    PubMed

    Colombani, N; Pantano, A; Mastrocicco, M; Petitta, M

    2014-11-15

    1,2-Dichloroethane (1,2-DCA) was found to be the most abundant compound among chlorinated hydrocarbons detected in a petrochemical plant in southern Italy. This site is located near the coastline, and it is set above an unconfined coastal aquifer, where seawater intrusion is present. The presence of organic and inorganic contaminants at this site has required the implementation of remediation strategies, consisting of pumping wells (hydraulic barrier) and a horizontal flow barrier. The purpose of this work was to assess the influence of salt water intrusion on the degradation rate of 1,2-DCA. This was done on a three-dimensional domain relative to a limited portion of a well characterized field site, accounting for density-dependent flow and reactive transport modelling of 1,2-DCA and Dissolved Organic Carbon (DOC). The modelling procedure was performed employing SEAWAT-4.0 and PHT3D, to reproduce the complex three-dimensional flow and transport domain. In order to determine the fate of 1,2-DCA, detailed field investigations provided intensive depth profile information. Different, kinetically controlled degradation rates were simulated to explain the observed, selective degradation of pollutants in groundwater. Calibration of the model was accomplished by comparison with the two different sets of measurements obtained from the MLS devices and from pumping wells. With the calibrated model, it was possible to distinguish between dispersive non-reactive processes and bacterially mediated reactions. In the non-reactive model, 1,2-DCA sorption was simulated using linear sorption coefficient determined with field data and 1,2-DCA degradation was simulated using a first order decay coefficient using literature data as initial guess. Finally, on the reactive transport model, where a two-step approach with partial equilibrium approach was implemented, the effects of neglecting the cation exchange capacity, omitting density-dependent flow, and refining the vertical

  6. Multilayer thermal barrier coating systems

    DOEpatents

    Vance, Steven J.; Goedjen, John G.; Sabol, Stephen M.; Sloan, Kelly M.

    2000-01-01

    The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

  7. Modeling Catastrophic Barrier Island Dynamics

    NASA Astrophysics Data System (ADS)

    Whitley, J. W.; McNamara, D.

    2012-12-01

    Barrier islands, thin strips of sand lying parallel to the mainland coastline, along the U.S. Atlantic and Gulf Coasts appear to have maintained their form for thousands of years in the face of rising sea level. The mechanisms that allow barrier islands to remain robust are transport of sediment from the ocean side of barriers to the top and backside during storms, termed island overwash, and the growth and alongshore propagation of tidal deltas near barrier island inlets. Dynamically these processes provide the necessary feedbacks to maintain a barrier island in an attractor that withstands rising sea level within a phase space of barrier island geometrical characteristics. Current barrier island configurations along the Atlantic and Gulf coasts exist among a wide range of storm climate and underlying geologic conditions and therefore the environment that forces overwash and tidal delta dynamics varies considerably. It has been suggested that barrier islands in certain locations such as those between Avon and Buxton (losing 76% of island width since 1852) and Chandeleur islands (losing 85% of its surface area since 2005) along the Atlantic and Gulf coasts, respectively, may be subject to a catastrophic shift in barrier island attractor states - more numerous inlets cutting barriers in some locations and the complete disappearance of barrier islands in other locations. In contrast to common models for barrier islands that neglect storm dynamics and often only consider cross-shore response, we use an alongshore extended model for barrier island dynamics including beach erosion, island overwash and inlet cutting during storms, and beach accretion, tidal delta growth and dune and vegetation growth between storms to explore the response of barrier islands to a wide range of environmental forcing. Results will be presented that show how barrier island attractor states are altered with variations in the rate of sea level rise, storminess, and underlying geology. We will

  8. Can-Filled Crash Barrier

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1983-01-01

    Crash barrier composed largely of used aluminum beverage cans protects occupants of cars in collisions with poles or trees. Lightweight, can-filled barrier very effective in softening impact of an automobile in head-on and off-angle collisions. Preliminary results indicate barrier is effective in collisions up to 40 mi/h (64 km/h).

  9. Information Barriers: Identification and Seriousness.

    ERIC Educational Resources Information Center

    Haag, D. E.

    The project documented in this report identified barriers researchers encounter in gaining access to--i.e., identifying, acquiring, handling, and using--published information and measured the seriousness of the more significant barriers. Fifty-one barriers were identified, and a method of measuring their seriousness was developed. Thirty of the…

  10. Amosphous diffusion barriers

    NASA Technical Reports Server (NTRS)

    Kolawa, E.; So, F. C. T.; Nicolet, M-A.

    1986-01-01

    Amorphous W-Zr and W-N alloys were investigated as diffusion barriers in silicon metallization schemes. Data were presented showing that amorphous W-Zr crystallizes at 900 C, which is 200 C higher than amorphous W-Ni films, and that both films react with metallic overlayers at temperatures far below the crystllization temperature. Also, W-N alloys (crystalline temperature of 600 C) were successfully incorporated as a diffusion barrier in contact structures with both Al and Ag overlayers. The thermal stability of the electrical characteristics of shallow n(+)p junctions significantly improved by incorporating W-N layers in the contact system. One important fact demonstated was the critical influence of the deposition parameters during formation of these carriers.

  11. Skin Barrier Function

    PubMed Central

    Elias, Peter M.

    2010-01-01

    Like other inflammatory dermatoses, the pathogenesis of atopic dermatitis (AD) has been largely attributed to abnormalities in adaptive immunity. T helper (Th) cell types 1 and 2 cell dysregulation, IgE production, mast cell hyperactivity, and dendritic cell signaling are thought to account for the chronic, pruritic, and inflammatory dermatosis that characterizes AD. Not surprisingly, therapy has been directed toward ameliorating Th2-mediated inflammation and pruritus. Here, we review emerging evidence that inflammation in AD occurs downstream to inherited and acquired insults to the barrier. Therapy based upon this new view of pathogenesis should emphasize approaches that correct the primary abnormality in barrier function, which drives downstream inflammation and allows unrestricted antigen access. PMID:18606081

  12. Phenylethynyl terminated reactive oligomer

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor)

    1995-01-01

    A composition of matter having the general structure: ##STR1## (wherein X is F, Cl, or NO.sub.2, and Y is CO, SO.sub.2 or C(CF.sub.3).sub.2) is employed to terminate a nucleophilic reagent, resulting in the exclusive production of phenylethynyl terminated reactive oligomers which display unique thermal characteristics. A reactive diluent having the general structure: ##STR2## (wherein R is any aliphatic or aromatic moiety) is employed to decrease the melt viscosity of a phenylethynyl terminated reactive oligomer and to subsequently react therewith to provide a thermosetting material of enhanced density. These materials have features which make them attractive candidates for use as composite matrices and adhesives.

  13. Interactive chemical reactivity exploration.

    PubMed

    Haag, Moritz P; Vaucher, Alain C; Bosson, Maël; Redon, Stéphane; Reiher, Markus

    2014-10-20

    Elucidating chemical reactivity in complex molecular assemblies of a few hundred atoms is, despite the remarkable progress in quantum chemistry, still a major challenge. Black-box search methods to find intermediates and transition-state structures might fail in such situations because of the high-dimensionality of the potential energy surface. Here, we propose the concept of interactive chemical reactivity exploration to effectively introduce the chemist's intuition into the search process. We employ a haptic pointer device with force feedback to allow the operator the direct manipulation of structures in three dimensions along with simultaneous perception of the quantum mechanical response upon structure modification as forces. We elaborate on the details of how such an interactive exploration should proceed and which technical difficulties need to be overcome. All reactivity-exploration concepts developed for this purpose have been implemented in the samson programming environment.

  14. Development of reactive topical skin protectants against sulfur mustard and nerve agents.

    PubMed

    Koper, O; Lucas, E; Klabunde, K J

    1999-12-01

    The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the laboratory. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and crystalline morphology. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are physically and chemically compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chemical agents while promising to be compatible with skin contact.

  15. Barrier breaching device

    DOEpatents

    Honodel, C.A.

    1983-06-01

    A barrier breaching device that is designed primarily for opening holes in interior walls of buildings uses detonating fuse for explosive force. The fuse acts as the ribs or spokes of an umbrella-like device that may be opened up to form a cone. The cone is placed against the wall so that detonating fuse that rings the base of the device and which is ignited by the spoke-like fuses serves to cut a circular hole in the wall.

  16. Systematics of shape resonances in reactive collisions

    NASA Astrophysics Data System (ADS)

    Sakimoto, Kazuhiro

    2016-10-01

    Wentzel-Kramers-Brillouin (WKB) methodology is used to undertake a systematic analysis of shape resonances in exoergic reactive collisions at low energies E , and examples investigated are Li +H+ , He (2 3S )+H , and He (2 3S )+Mu (muonium). In so doing, the resonance positions should be measured by the tunneling parameter α and not by E . The resonance peak height Pres of the reaction probability and the resonance width times the vibrational period of the quasibound resonance state can be given by simple closed-form expressions with two variables, α and P0, the latter of which is a reaction probability given at collision energies much above a centrifugal barrier top and is determined by only short-range interactions. The resonance promotes the reaction maximally (i.e., Pres=1 ) when the resonance satisfies α =α0=(2π ) -1ln[(1 -P0) /P0] , in other words, when the transmission coefficient of tunneling through the centrifugal barrier happens to be equal to P0 at the resonance energy. If α0≳1 , the reaction system is rich in tunneling resonances. If α0≲0 , the prominent resonances are mostly an over-barrier type. The resonances occurring at α ≫α0 are of no significance in the reaction.

  17. Reactive modification of polyesters and their blends

    NASA Astrophysics Data System (ADS)

    Wan, Chen

    2004-12-01

    the desired rheological and structural characteristics of the final products for potential applications such as low density extrusion foaming or compatibilization of immiscible polymer blends. Important modification conditions through coagents are identified and reaction mechanisms are proposed. A high MW saturated polyester, PET, can also be rheologically modified in extruders through low MW multifunctional anhydride and epoxy compounds by chain extension/branching. Several such modifiers were successfully screened in terms of their reactivity towards PET under controlled reactive extrusion conditions. A dianhydride with medium reactivity was then successfully used in a one-step reactive modification/extrusion foaming process to produce low density foams. A similar process was successfully used to produce small cell size foams from a four component system containing PET, PP and lesser amounts of a low molecular weight multifunctional epoxy compound and an acid functionalized polyolefin, the latter acting as compatibilizers.

  18. Barrier infrared detector

    NASA Technical Reports Server (NTRS)

    Ting, David Z. (Inventor); Khoshakhlagh, Arezou (Inventor); Soibel, Alexander (Inventor); Hill, Cory J. (Inventor); Gunapala, Sarath D. (Inventor)

    2012-01-01

    A superlattice-based infrared absorber and the matching electron-blocking and hole-blocking unipolar barriers, absorbers and barriers with graded band gaps, high-performance infrared detectors, and methods of manufacturing such devices are provided herein. The infrared absorber material is made from a superlattice (periodic structure) where each period consists of two or more layers of InAs, InSb, InSbAs, or InGaAs. The layer widths and alloy compositions are chosen to yield the desired energy band gap, absorption strength, and strain balance for the particular application. Furthermore, the periodicity of the superlattice can be "chirped" (varied) to create a material with a graded or varying energy band gap. The superlattice based barrier infrared detectors described and demonstrated herein have spectral ranges covering the entire 3-5 micron atmospheric transmission window, excellent dark current characteristics operating at least 150K, high yield, and have the potential for high-operability, high-uniformity focal plane arrays.

  19. Netrin 1 regulates blood-brain barrier function and neuroinflammation.

    PubMed

    Podjaski, Cornelia; Alvarez, Jorge I; Bourbonniere, Lyne; Larouche, Sandra; Terouz, Simone; Bin, Jenea M; Lécuyer, Marc-André; Saint-Laurent, Olivia; Larochelle, Catherine; Darlington, Peter J; Arbour, Nathalie; Antel, Jack P; Kennedy, Timothy E; Prat, Alexandre

    2015-06-01

    Blood-brain barrier function is driven by the influence of astrocyte-secreted factors. During neuroinflammatory responses the blood-brain barrier is compromised resulting in central nervous system damage and exacerbated pathology. Here, we identified endothelial netrin 1 induction as a vascular response to astrocyte-derived sonic hedgehog that promotes autocrine barrier properties during homeostasis and increases with inflammation. Netrin 1 supports blood-brain barrier integrity by upregulating endothelial junctional protein expression, while netrin 1 knockout mice display disorganized tight junction protein expression and barrier breakdown. Upon inflammatory conditions, blood-brain barrier endothelial cells significantly upregulated netrin 1 levels in vitro and in situ, which prevented junctional breach and endothelial cell activation. Finally, netrin 1 treatment during experimental autoimmune encephalomyelitis significantly reduced blood-brain barrier disruption and decreased clinical and pathological indices of disease severity. Our results demonstrate that netrin 1 is an important regulator of blood-brain barrier maintenance that protects the central nervous system against inflammatory conditions such as multiple sclerosis and experimental autoimmune encephalomyelitis.

  20. Long term performance of the Waterloo denitrification barrier

    SciTech Connect

    Robertson, W.D.; Cherry, J.A.

    1997-12-31

    Beginning in 1991 a series of laboratory tests and small scale field trials were initiated to test the performance of an innovative permeable reactive barrier for treatment of nitrate from septic systems. The barrier promotes denitrification by providing an energy source in the form of solid organic carbon mixed into the porous media material. Advantages of the system for nitrate treatment are that the reaction is passive and in situ and it is possible to incorporate sufficient carbon mass in conveniently sized barriers to potentially provide treatment for long periods (decades) without the necessity for maintenance. However, longevity can only be demonstrated by careful long term monitoring of field installations. This paper documents four years of operating history at three small scale field trials; two where the denitrification barrier is installed as a horizontal layer positioned in the unsaturated zone below conventional septic system infiltration beds and one where the barrier is installed as a vertical wall intercepting a septic system plume at a downgradient location. The barriers have successfully attenuated 50-100% of NO{sup -}{sub 3}-N levels of up to 170 mg/L and treatment has remained consistent over the four year period in each case, thus considerable longevity is indicated. Other field trials have demonstrated this technology to be equally effective in treating nitrogen contamination from other sources such as landfill leachate and farm field runoff.

  1. JT90 thermal barrier coated vanes

    NASA Technical Reports Server (NTRS)

    Sheffler, K. D.; Graziani, R. A.; Sinko, G. C.

    1982-01-01

    The technology of plasma sprayed thermal barrier coatings applied to turbine vane platforms in modern high temperature commercial engines was advanced to the point of demonstrated feasibility for application to commercial aircraft engines. The three thermal barrier coatings refined under this program are zirconia stabilized with twenty-one percent magnesia (21% MSZ), six percent yttria (6% YSZ), and twenty percent yttria (20% YSZ). Improvement in thermal cyclic endurance by a factor of 40 times was demonstrated in rig tests. A cooling system evolved during the program which featured air impingement cooling for the vane platforms rather than film cooling. The impingement cooling system, in combination with the thermal barrier coatings, reduced platform cooling air requirements by 44% relative to the current film cooling system. Improved durability and reduced cooling air requirements were demonstrated in rig and engine endurance tests. Two engine tests were conducted, one of 1000 cycles and the other of 1500 cycles. All three coatings applied to vanes fabricated with the final cooling system configuration completed the final 1500 cycle engine endurance test. Results of this test clearly demonstrated the durability of the 6% YSZ coating which was in very good condition after the test. The 21% MSZ and 20% YSZ coatings had numerous occurrences of significant spalling in the test.

  2. Final Scientific/Technical Report – DE-FG02-06ER64172 – Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center – Subproject to Co-PI Eric E. Roden

    SciTech Connect

    Eric E. Roden

    2009-03-17

    This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2. Area 2 is a shallow pathway for migration of contaminated groundwater to seeps in the upper reach of Bear Creek at ORNL, mainly through a ca. 1 m thick layer of gravel located 4-5 m below the ground surface. The gravel layer is sandwiched between an overlying layer of disturbed fill material, and 2-3 m of undisturbed shale saprolite derived from the underlying Nolichucky Shale bedrock. The fill was put in place when contaminated soils were excavated and replaced by native saprolite from an uncontaminated area within Bear Creek Valley; the gravel layer was presumably installed prior to addition of the fill in order to provide a stable surface for the operation of heavy machinery. The undisturbed saprolite is highly weathered bedrock that has unconsolidated character but retains much of the bedding and fracture structure of the parent rock (shale with interbedded limestone). Hydrological tracer studies conducted during the Scheibe et al. field

  3. Disposal systems evaluations and tool development : Engineered Barrier System (EBS) evaluation.

    SciTech Connect

    Rutqvist, Jonny; Liu, Hui-Hai; Steefel, Carl I.; Serrano de Caro, M. A.; Caporuscio, Florie Andre; Birkholzer, Jens T.; Blink, James A.; Sutton, Mark A.; Xu, Hongwu; Buscheck, Thomas A.; Levy, Schon S.; Tsang, Chin-Fu; Sonnenthal, Eric; Halsey, William G.; Jove-Colon, Carlos F.; Wolery, Thomas J.

    2011-01-01

    Key components of the nuclear fuel cycle are short-term storage and long-term disposal of nuclear waste. The latter encompasses the immobilization of used nuclear fuel (UNF) and radioactive waste streams generated by various phases of the nuclear fuel cycle, and the safe and permanent disposition of these waste forms in geological repository environments. The engineered barrier system (EBS) plays a very important role in the long-term isolation of nuclear waste in geological repository environments. EBS concepts and their interactions with the natural barrier are inherently important to the long-term performance assessment of the safety case where nuclear waste disposition needs to be evaluated for time periods of up to one million years. Making the safety case needed in the decision-making process for the recommendation and the eventual embracement of a disposal system concept requires a multi-faceted integration of knowledge and evidence-gathering to demonstrate the required confidence level in a deep geological disposal site and to evaluate long-term repository performance. The focus of this report is the following: (1) Evaluation of EBS in long-term disposal systems in deep geologic environments with emphasis on the multi-barrier concept; (2) Evaluation of key parameters in the characterization of EBS performance; (3) Identification of key knowledge gaps and uncertainties; and (4) Evaluation of tools and modeling approaches for EBS processes and performance. The above topics will be evaluated through the analysis of the following: (1) Overview of EBS concepts for various NW disposal systems; (2) Natural and man-made analogs, room chemistry, hydrochemistry of deep subsurface environments, and EBS material stability in near-field environments; (3) Reactive Transport and Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes in EBS; and (4) Thermal analysis toolkit, metallic barrier degradation mode survey, and development of a Disposal Systems

  4. Effect of five acetylcholinesterase reactivators on tabun-intoxicated rats: induction of oxidative stress versus reactivation efficacy.

    PubMed

    Pohanka, Miroslav; Karasova, Jana Zdarova; Musilek, Kamil; Kuca, Kamil; Kassa, Jiri

    2009-08-01

    Oxime reactivators HI-6, obidoxime, trimedoxime, K347 and K628 were investigated as drugs designed for treatment of tabun intoxication. The experiments were performed on rats in order to simulate real conditions. Rats were intoxicated with one LD(50 )of tabun and treated with atropine and mentioned reactivators. Activities of erythrocyte acetylcholinesterase (AChE), plasma butyrylcholinesterase (BChE) and brain AChE were measured as markers of reactivation efficacy. An estimation of low molecular weight antioxidant levels using cyclic voltammetry was the second examination parameter. The evaluation of cholinesterases activity showed good reactivation potency of blood AChE and plasma BChE by commercially available obidoxime and newly synthesized K347. The potency of oximes to reactivate brain AChE was lower due to the poor blood-brain barrier penetration of used compounds. Commercially available reactivator HI-6 and newly synthesized K628 caused oxidative stress measured by cyclic voltammetry as antioxidant level. The oxidative stress provoked by HI-6 and K628 was found to be significant on probability level P = 0.05. The others reactivators did not affect antioxidant levels.

  5. CH stretching excitation in the early barrier F + CHD3 reaction inhibits CH bond cleavage.

    PubMed

    Zhang, Weiqing; Kawamata, Hiroshi; Liu, Kopin

    2009-07-17

    Most studies of the impact of vibrational excitation on molecular reactivity have focused on reactions with a late barrier (that is, a transition state resembling the products). For an early barrier reaction, conventional wisdom predicts that a reactant's vibration should not couple efficiently to the reaction coordinate and thus should have little impact on the outcome. We report here an in-depth experimental study of the reactivity effects exerted by reactant C-H stretching excitation in a prototypical early-barrier reaction, F + CHD3. Rather counterintuitively, we find that the vibration hinders the overall reaction rate, inhibits scission of the excited bond itself (favoring the DF + CHD2 product channel), and influences the coproduct vibrational distribution despite being conserved in the CHD2 product. The results highlight substantial gaps in our predictive framework for state-selective polyatomic reactivity.

  6. Rhinovirus-Induced Barrier Dysfunction in Polarized Airway Epithelial Cells Is Mediated by NADPH Oxidase 1▿

    PubMed Central

    Comstock, Adam T.; Ganesan, Shyamala; Chattoraj, Asamanja; Faris, Andrea N.; Margolis, Benjamin L.; Hershenson, Marc B.; Sajjan, Umadevi S.

    2011-01-01

    Previously, we showed that rhinovirus (RV), which is responsible for the majority of common colds, disrupts airway epithelial barrier function, as evidenced by reduced transepithelial resistance (RT), dissociation of zona occludins 1 (ZO-1) from the tight junction complex, and bacterial transmigration across polarized cells. We also showed that RV replication is required for barrier function disruption. However, the underlying biochemical mechanisms are not known. In the present study, we found that a double-stranded RNA (dsRNA) mimetic, poly(I:C), induced tight junction breakdown and facilitated bacterial transmigration across polarized airway epithelial cells, similar to the case with RV. We also found that RV and poly(I:C) each stimulated Rac1 activation, reactive oxygen species (ROS) generation, and Rac1-dependent NADPH oxidase 1 (NOX1) activity. Inhibitors of Rac1 (NSC23766), NOX (diphenylene iodonium), and NOX1 (small interfering RNA [siRNA]) each blocked the disruptive effects of RV and poly(I:C) on RT, as well as the dissociation of ZO-1 and occludin from the tight junction complex. Finally, we found that Toll-like receptor 3 (TLR3) is not required for either poly(I:C)- or RV-induced reductions in RT. Based on these results, we concluded that Rac1-dependent NOX1 activity is required for RV- or poly(I:C)-induced ROS generation, which in turn disrupts the barrier function of polarized airway epithelia. Furthermore, these data suggest that dsRNA generated during RV replication is sufficient to disrupt barrier function. PMID:21507984

  7. Chemical Reactivity Test (CRT)

    SciTech Connect

    Zaka, F.

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  8. Reactive power compensating system

    DOEpatents

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1987-01-01

    The reactive power of an induction machine is compensated by providing fixed capacitors on each phase line for the minimum compensation required, sensing the current on one line at the time its voltage crosses zero to determine the actual compensation required for each phase, and selecting switched capacitors on each line to provide the balance of the compensation required.

  9. Reactive Sensor Networks (RSN)

    DTIC Science & Technology

    2003-10-01

    Networks,” Distributed Autonomous Robotic Systems DARS 2000, pp. 471-472, Springer Verlag, Tokyo. R. R. Brooks. “Stigmergy an intelligence metric...Paper, March 2003. • R. Brooks, et al. “Reactive Sensor Networks: Mobile Code Support for Autonomous Sensor Networks,” Distributed Autonomous Robotic Systems DARS

  10. Reactive transport modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This special section in the Vadose Zone Journal focusing on reactive transport modeling was developed from a special symposium jointly sponsored by the Soil Physics and Soil Chemistry Divisions of the Soil Science Society of America at the 2010 annual meetings held in Long Beach, CA. It contains eig...

  11. Reactive Power Compensating System.

    DOEpatents

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1985-01-04

    The circuit was designed for the specific application of wind-driven induction generators. It has great potential for application in any situation where a varying reactive power load is present, such as with induction motors or generators, or for transmission network compensation.

  12. Modeling Atmospheric Reactive Nitrogen

    EPA Science Inventory

    Nitrogen is an essential building block of all proteins and thus an essential nutrient for all life. Reactive nitrogen, which is naturally produced via enzymatic reactions, forest fires and lightning, is continually recycled and cascades through air, water, and soil media. Human ...

  13. Alumina Paste Sublimation Suppression Barrier for Thermoelectric Device

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah (Inventor); Caillat, Thierry (Inventor)

    2014-01-01

    Alumina as a sublimation suppression barrier for a Zintl thermoelectric material in a thermoelectric power generation device operating at high temperature, e.g. at or above 1000K, is disclosed. The Zintl thermoelectric material may comprise Yb.sub.14MnSb.sub.11. The alumina may be applied as an adhesive paste dried and cured on a substantially oxide free surface of the Zintl thermoelectric material and polished to a final thickness. The sublimation suppression barrier may be finalized by baking out the alumina layer on the Zintl thermoelectric material until it becomes substantially clogged with ytterbia.

  14. Final Report

    SciTech Connect

    Marchant, Gary E.

    2013-04-23

    This is the final report of a two year project entitled "Governing Nanotechnology Risks and Benefits in the Transition to Regulation: Innovative Public and Private Approaches." This project examined the role of new governance or "soft law" mechanisms such as codes of conduct, voluntary programs and partnership agreements to manage the risks of emerging technologies such as nanotechnology. A series of published or in publication papers and book chapters are attached.

  15. Final Report

    SciTech Connect

    R. Paul Drake

    2001-11-30

    This final report describes work involving 22 investigators from 11 institutions to explore the dynamics present in supernova explosions by means of experiments on the Omega laser. The specific experiments emphasized involved the unstable expansion of a spherical capsule and the coupling of perturbations at a first interface to a second interface by means of a strong shock. Both effects are present in supernovae. The experiments were performed at Omega and the computer simulations were undertaken at several institutions. B139

  16. Final Report

    SciTech Connect

    Stinis, Panos

    2016-08-07

    This is the final report for the work conducted at the University of Minnesota (during the period 12/01/12-09/18/14) by PI Panos Stinis as part of the "Collaboratory on Mathematics for Mesoscopic Modeling of Materials" (CM4). CM4 is a multi-institution DOE-funded project whose aim is to conduct basic and applied research in the emerging field of mesoscopic modeling of materials.

  17. FINAL REPORT

    SciTech Connect

    Horn, Mark W; McDaniel, Anthony; Schweighardt, Frank K

    2003-05-23

    In this program the teams at Penn State University (PSU), Sandia National Laboratories (SNL), DCH Technology (DCHT), and Air Products and Chemicals Inc. (APCI), have aggressively pursued engineering solutions to eliminate barriers to solid-state chemiresistor hydrogen sensor technology. The metallurgical effects of alloying palladium with nickel have been shown to prevent phase transitions in the thin films at high H2 overpressures, making the devices more suitable for IOF process conditions. We investigated the use of thin, semi-permeable membranes that protect the catalytic surface from poisoning or other undesirable surface reactions that would otherwise reduce sensitivity or operability in harsh IOF process environments. The results of this project have provided new insight into the effects of metallurgy and protective coatings on device behavior, and open new avenues for research in this field. Commercialization of this sensor technology could be easily achieved, although not yet realized. The benefits to society, once this technology is commercialized, is a dramatic cost and energy savings to the industry, which employs these sensors. In addition, the fundamental understandings gained in this program could have an impact on both cost and safety in the future hydrogen economy utilizing hydrogen fuel cells and hydrogen storage.

  18. Allylic amination reactivity of Ni, Pd, and Pt heterobimetallic and monometallic complexes.

    PubMed

    Carlsen, Ryan W; Ess, Daniel H

    2016-06-14

    Transition metal heterobimetallic complexes with dative metal-metal interactions have the potential for novel fast reactivity. There are few studies that both compare the reactivity of different metal centers in heterobimetallic complexes and compare bimetallic reactivity to monometallic reactivity. Here we report density-functional calculations that show the reactivity of [Cl2Ti(N(t)BuPPh2)2M(II)(η(3)-methallyl)] heterobimetallic complexes for allylic amination follows M = Ni > Pd > Pt. This reactivity trend was not anticipated since the amine addition transition state involves M(II) to M(0) reduction and this could disadvantage Ni. Comparison of heterobimetallic complexes to the corresponding monometallic (CH2)2(N(t)BuPPh2)2M(II)(η(3)-methallyl) complexes reveals that this reactivity trend is due to the bimetallic interaction and that the bimetallic interaction significantly lowers the barrier height for amine addition by >10 kcal mol(-1). The impact of the early transition metal center on the amination addition barrier height depends on the late transition metal center. The lowest barrier heights for this reaction occur when late and early transition metal centers are from the same periodic table row.

  19. Reactivity Network: Secondary Sources for Inorganic Reactivity Information.

    ERIC Educational Resources Information Center

    Mellon, E. K.

    1989-01-01

    Provides an eclectic annotated bibliography of secondary sources for inorganic reactivity information of interest to reactivity network review authors and to anyone seeking information about simple inorganic reactions in order to develop experiments and demonstrations. Gives 119 sources. (MVL)

  20. Final report

    SciTech Connect

    S. H. Garofalini

    2004-11-12

    In the DOE award, DE-FG02-00ER45823, we have used molecular dynamics (MD) computer simulations of the intergranular films (IGFs) present in alumina and silicon nitride materials to address specific questions such as: What is the atomistic structure of the glassy silicate phase? Because of the extremely thin nature of the IGF, do bulk-like glass structure and properties prevail? Does distortion exist in the silicate bonds (which affects bond strength and reactivity) and how is this structure affected by the separation distance between the crystals and/or by the composition of the IGF? Does a structural ordering caused by epitaxial adsorption occur at the IGF/crystal interface? What is the correlation length of this order perpendicular to the interface? How is this ordering affected by composition of the IGF or by the crystals in question? In all simulations, a specific number of ions in stoichiometric ratio were placed as the IGF between two similar crystals, with, in some cases, different crystallographic orientations. The IGF compositions coincided with some of those observed experimentally (calcium aluminosilicate (CAS) glasses in the alumina case, calcium silicon oxy-nitride in the nitride case). The number of ions in the IGF was varied to allow for different thicknesses, although the X and Y dimensions (parallel to the interface) were usually {approx} 50 {angstrom} x 50 {angstrom}. The IGF was melted at a high temperature between the crystals, followed by a slow quench to room temperature, where structural data were collected.

  1. Field Demonstration/Validation of Electrolytic Barriers for Energetic Compounds at Pueblo Chemical Depot

    DTIC Science & Technology

    2010-01-01

    demonstration showed improvement over those previously employed. Specific advances included: • Use of four active electrodes (i.e., two sequential pairs...reactive barrier via the natural flow of groundwater. Within the barrier, contaminants are degraded as they pass through titanium screen electrodes ...Department of Defense (DoD) facilities. This included the goal of employing promising design improvements that were advanced from the 2002-2005 iii

  2. Permeable Barrier Materials for Strontium Immobilization: - UFA Determination of Hydraulic Conductivity. - Column Sorption Experiments

    DTIC Science & Technology

    1996-01-01

    Meadows clinoptilolite was also tested since it is currently being considered for use as a permeable barrier at N-Springs. 14. SUBJECT TERMS 15. NUMBER OF...permeability of reactive barrier); Soda Springs phosphate rock; and fish debris. Ash Meadows Clinoptilolite was also tested since it is currently being...follows: bone char > quartz sand > NC apatite >> fish debris:sand = Ash Meadows clinoptilolite:sand >> clinoptilolite >> hydroxyapatite > Soda Springs

  3. Stability of barrier buckets with zero RF-barrier separations

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2005-03-01

    A barrier bucket with very small separation between the rf barriers (relative to the barrier widths) or even zero separation has its synchrotron tune decreasing rather slowly from a large value towards the boundary of the bucket. As a result, large area at the bucket edges can become unstable under the modulation of rf voltage and/or rf phase. In addition, chaotic regions may form near the bucket center and extend outward under increasing modulation. Application is made to those barrier buckets used in the process of momentum mining at the Fermilab Recycler Ring.

  4. Final Report

    SciTech Connect

    R Paul Drake

    2004-01-12

    OAK-B135 This is the final report from the project Hydrodynamics by High-Energy-Density Plasma Flow and Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications. This project supported a group at the University of Michigan in the invention, design, performance, and analysis of experiments using high-energy-density research facilities. The experiments explored compressible nonlinear hydrodynamics, in particular at decelerating interfaces, and the radiation hydrodynamics of strong shock waves. It has application to supernovae, astrophysical jets, shock-cloud interactions, and radiative shock waves.

  5. Nanomedicine Faces Barriers

    PubMed Central

    Debbage, Paul; Thurner, Gudrun C.

    2010-01-01

    Targeted nanoparticles have the potential to improve drug delivery efficiencies by more than two orders of magnitude, from the ~ 0.1% which is common today. Most pharmacologically agents on the market today are small drug molecules, which diffuse across the body’s blood-tissue barriers and distribute not only into the lesion, but into almost all organs. Drug actions in the non-lesion organs are an inescapable part of the drug delivery principle, causing “side-effects” which limit the maximally tolerable doses and result in inadequate therapy of many lesions. Nanoparticles only cross barriers by design, so side-effects are not built into their mode of operation. Delivery rates of almost 90% have been reported. This review examines the significance of these statements and checks how far they need qualification. What type of targeting is required? Is a single targeting sufficient? What new types of clinical challenge, such as immunogenicity, might attend the use of targeted nanoparticles?

  6. Synthetic Eelgrass Oil Barrier

    NASA Astrophysics Data System (ADS)

    Curtis, T. G.

    2013-05-01

    Although surviving in situ micro-organisms eventually consume spilled oil, extensive inundation of shore biota by oil requires cleanup to enable ecological recovery within normal time scales. Although effective in calm seas and quiet waters, oil is advected over and under conventional curtain oil booms by wave actions and currents when seas are running. Most sorbent booms are not reusable, and are usually disposed of in landfills, creating excessive waste. A new concept is proposed for a floating oil barrier, to be positioned off vulnerable coasts, to interdict, contain, and sequester spilled oil, which can then be recovered and the barrier reused. While conventional oil boom designs rely principally on the immiscibility of oil in water and its relative buoyancy, the new concept barrier avoids the pitfalls of the former by taking advantage of the synergistic benefits of numerous fluid and material properties, including: density, buoyancy, elasticity, polarity, and surface area to volume ratio. Modeled after Zostera marina, commonly called eelgrass, the new barrier, referred to as synthetic eelgrass (SE), behaves analogously. Eelgrass has very long narrow, ribbon-like, leaves which support periphyton, a complex matrix of algae and heterotrophic microbes, which position themselves there to extract nutrients from the seawater flowing past them. In an analogous fashion, oil on, or in, seawater, which comes in contact with SE, is adsorbed on the surface and sequestered there. Secured to the bottom, in shoal waters, SE rises to the surface, and, if the tide is low enough, floats on the sea surface down wind, or down current to snare floating oil. The leaves of SE, called filaments, consist of intrinsically buoyant strips of ethylene methyl acrylate, aka EMA. EMA, made of long chain, saturated, hydrocarbon molecules with nearly homogeneous electron charge distributions, is a non-polar material which is oleophilic and hydrophobic. Oil must be in close proximity to the

  7. Final Report

    SciTech Connect

    David A. Benson

    2012-09-24

    This project combines outcrop-scale heterogeneity characterization, laboratory experiments, and numerical simulations. The study is designed to test whether established dispersion theory accurately predicts the behavior of solute transport through heterogeneous media and to investigate the relationship between heterogeneity and the parameters that populate these models. The dispersion theory tested by this work is based upon the fractional advection-dispersion equation (fADE) model. Unlike most dispersion studies that develop a solute transport model by fitting the solute transport breakthrough curve, this project will explore the nature of the heterogeneous media to better understand the connection between the model parameters and the aquifer heterogeneity. Our work at the Colorado School of Mines was focused on the following questions: 1) What are the effects of multi-scale geologic variability on transport of conservative and reactive solutes? 2) Can those transport effects be accounted for by classical methods, and if not, can the nonlocal fractional-order equations provide better predictions? 3) Can the fractional-order equations be parameterized through a link to some simple observable geologic features? 4) Are the classical equations of transport and reaction sufficient? 5) What is the effect of anomalous transport on chemical reaction in groundwater systems? The work is predicated on the observation that upscaled transport is defined by loss of information, or spatio-temporal averaging. This averaging tends to make the transport laws such as Fick's 2nd-order diffusion equation similar to central limit theory. The fractional-order advection-dispersion equations rely on limit theory for heavy-tailed random motion that has some diverging moments. The equations predict larger tails of a plume in space and/or time than those predicted by the classical 2nd-order advection-dispersion equation. The heavy tails are often seen in plumes at field sites.

  8. Comparison of skin barrier function and sensory nerve electric current perception threshold between IgE-high extrinsic and IgE-normal intrinsic types of atopic dermatitis.

    PubMed

    Mori, T; Ishida, K; Mukumoto, S; Yamada, Y; Imokawa, G; Kabashima, K; Kobayashi, M; Bito, T; Nakamura, M; Ogasawara, K; Tokura, Y

    2010-01-01

    Background Two types of atopic dermatitis (AD) have been proposed, with different pathophysiological mechanisms underlying this seemingly heterogeneous disorder. The extrinsic type shows high IgE levels presumably as a consequence of skin barrier damage and feasible allergen permeation, whereas the intrinsic type exhibits normal IgE levels and is not mediated by allergen-specific IgE. Objectives To investigate the relationship between pruritus perception threshold and skin barrier function of patients with AD in a comparison between the extrinsic and intrinsic types. Methods Enrolled in this study were 32 patients with extrinsic AD, 17 with intrinsic AD and 24 healthy individuals. The barrier function of the stratum corneum was assessed by skin surface hydration and transepidermal water loss (TEWL), and pruritus perception was evaluated by the electric current perception threshold (CPT) of sensory nerves upon neuroselective transcutaneous electric stimulation. Results Skin surface hydration was significantly lower and TEWL was significantly higher in extrinsic AD than intrinsic AD or normal controls. Although there was no statistically significant difference in CPT among extrinsic AD, intrinsic AD and normal controls, CPT was significantly correlated with skin surface hydration and inversely with TEWL in intrinsic AD and normal controls, but not extrinsic AD. Finally, CPT was correlated with the visual analogue scale of itch in the nonlesional skin of patients with extrinsic but not intrinsic AD. Conclusions Patients with extrinsic AD have an impaired barrier, which increases the pre-existing pruritus but rather decreases sensitivity to external stimuli. In contrast, patients with intrinsic AD retain a normal barrier function and sensory reactivity to external pruritic stimuli.

  9. Phenylethynyl Containing Reactive Additives

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2002-01-01

    Phenylethynyl containing reactive additives were prepared from aromatic diamine, containing phenylethvnvl groups and various ratios of phthalic anhydride and 4-phenylethynviphthalic anhydride in glacial acetic acid to form the imide in one step or in N-methyl-2-pvrrolidinone to form the amide acid intermediate. The reactive additives were mixed in various amounts (10% to 90%) with oligomers containing either terminal or pendent phenylethynyl groups (or both) to reduce the melt viscosity and thereby enhance processability. Upon thermal cure, the additives react and become chemically incorporated into the matrix and effect an increase in crosslink density relative to that of the host resin. This resultant increase in crosslink density has advantageous consequences on the cured resin properties such as higher glass transition temperature and higher modulus as compared to that of the host resin.

  10. Reactive Air Aluminization

    SciTech Connect

    Choi, Jung-Pyung; Chou, Y. S.; Stevenson, Jeffry W.

    2011-10-28

    Ferritic stainless steels and other alloys are of great interest to SOFC developers for applications such as interconnects, cell frames, and balance of plant components. While these alloys offer significant advantages (e.g., low material and manufacturing cost, high thermal conductivity, and high temperature oxidation resistance), there are challenges which can hinder their utilization in SOFC systems; these challenges include Cr volatility and reactivity with glass seals. To overcome these challenges, protective coatings and surface treatments for the alloys are under development. In particular, aluminization of alloy surfaces offers the potential for mitigating both evaporation of Cr from the alloy surface and reaction of alloy constituents with glass seals. Commercial aluminization processes are available to SOFC developers, but they tend to be costly due to their use of exotic raw materials and/or processing conditions. As an alternative, PNNL has developed Reactive Air Aluminization (RAA), which offers a low-cost, simpler alternative to conventional aluminization methods.

  11. Phenylethynyl Containing Reactive Additives

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2002-01-01

    Phenylethynyl containing reactive additives were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynylphthalic anhydride in glacial acetic acid to form the imide in one step or in N-methyl-2-pyrrolidi none to form the amide acid intermediate. The reactive additives were mixed in various amounts (10% to 90%) with oligomers containing either terminal or pendent phenylethynyl groups (or both) to reduce the melt viscosity and thereby enhance processability. Upon thermal cure, the additives react and become chemically incorporated into the matrix and effect an increase in crosslink density relative to that of the host resin. This resultant increase in crosslink density has advantageous consequences on the cured resin properties such as higher glass transition temperature and higher modulus as compared to that of the host resin.

  12. Multiple animal studies for medical chemical defense program in soldier/patient decontamination and drug development on task order 85-13: Advanced screening system for evaluating barrier compounds for protection from organophosphate chemical surety material using a nonlethal end point, acetylcholinesterase inhibition. Final report, 1 January 1985-1 September 1988

    SciTech Connect

    Joiner, R.L.; Dill, S.; Olson, T.; Kiser, C.; Feder, I.

    1988-09-01

    This task was initiated at the Medical Research and Evaluation Facility to develop a protocol for advanced screening of candidate barrier compounds for protection from nerve agents using a quantifiable nonlethal end point as a measure of effectiveness. Soman (GD), thickened GD (TGD), and VX were used to generate a family of curves for erythrocyte (RBC) acetylcholinesterase (AChE) inhibition as a function these data, a single dose was selected for each agent to challenge barrier-protected and unprotected animals. Blood samples were drawn at three times after exposure from each group of agent-challenged animals to validate the model by comparing AChE depression and rate of inhibition in unprotected and barrier-protected animals. Screen, organophosphate, chemical surety materiel, TGD, GD, VX, acetylcholinesterase inhibition, barrier compounds, nonlethal end point, PEG 540, rabbits.

  13. Performing a local barrier operation

    DOEpatents

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2014-03-04

    Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value of the counter, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

  14. Performing a local barrier operation

    DOEpatents

    Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

    2014-03-04

    Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value of the counter, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

  15. Interdigital Schottky barrier capacitor apparatus

    NASA Astrophysics Data System (ADS)

    Bierig

    1985-05-01

    The present invention relates broadly to Schottky barrier capacitors, and in particular to an interdigital Schottky barrier capacitor apparatus. In the prior art, the Schottky barrier diode is rather well known. In general, a Schottky barrier device comprises a semiconductor substrate layer that is formed by a first layer of heavily doped materials and a second layer of lightly doped materials upon which a layer of barrier metal is deposited thereon. The maximum reverse bias voltage which can be appplied to the Schottky barrier device is determined by the thickness of the lightly doped layer of semiconductive material which is deposited upon the substrate layer. This is only one of the factors that determined the reverse bias voltage, When a guardring is diffused into the lightly doped layer of semiconductive substrate material, the thickness of the layer is reduced, and therefore, the reverse bias voltage that can be applied to the Schottky device is reduced.

  16. Problems in characterizing barrier performance

    NASA Technical Reports Server (NTRS)

    Jordan, Harry F.

    1988-01-01

    The barrier is a synchronization construct which is useful in separating a parallel program into parallel sections which are executed in sequence. The completion of a barrier requires cooperation among all executing processes. This requirement not only introduces the wait for the slowest process delay which is inherent in the definition of the synchronization, but also has implications for the efficient implementation and measurement of barrier performance in different systems. Types of barrier implementation and their relationship to different multiprocessor environments are described. Then the problem of measuring the performance of barrier implementations on specific machine architecture is discussed. The fact that the barrier synchronization requires the cooperation of all processes makes the problem of performance measurement similarly global. Making non-intrusive measurements of sufficient accuracy can be tricky on systems offering only rudimentary measurement tools.

  17. Nonquaternary Cholinesterase Reactivators.

    DTIC Science & Technology

    1982-08-30

    Methylphosphonyl-AChE by la, lb, 2, and 3 . .............................................. 83 Chapter III 1 Lineweaver - Burke Plot for Compound 3a...Not determined. I11 ................ ."--..-. . . .S . -. -.. .i.,...,. _. o, . ’._ -. .-. . , , I I 1 .. .! 8.08.O 1I i i 7.0 LINEWEAVER - BURKE ...10 15 20 25 30 35 40 [AcSCh] - 1 , M -1 x 10 -4 JA-1 043-23 FIGURE 1 LINEWEAVER - BURKE PLOT FOR COMPOUND 3a 112 nonquaternary reactivators with ethyl

  18. Multiscale reactive molecular dynamics

    NASA Astrophysics Data System (ADS)

    Knight, Chris; Lindberg, Gerrick E.; Voth, Gregory A.

    2012-12-01

    Many processes important to chemistry, materials science, and biology cannot be described without considering electronic and nuclear-level dynamics and their coupling to slower, cooperative motions of the system. These inherently multiscale problems require computationally efficient and accurate methods to converge statistical properties. In this paper, a method is presented that uses data directly from condensed phase ab initio simulations to develop reactive molecular dynamics models that do not require predefined empirical functions. Instead, the interactions used in the reactive model are expressed as linear combinations of interpolating functions that are optimized by using a linear least-squares algorithm. One notable benefit of the procedure outlined here is the capability to minimize the number of parameters requiring nonlinear optimization. The method presented can be generally applied to multiscale problems and is demonstrated by generating reactive models for the hydrated excess proton and hydroxide ion based directly on condensed phase ab initio molecular dynamics simulations. The resulting models faithfully reproduce the water-ion structural properties and diffusion constants from the ab initio simulations. Additionally, the free energy profiles for proton transfer, which is sensitive to the structural diffusion of both ions in water, are reproduced. The high fidelity of these models to ab initio simulations will permit accurate modeling of general chemical reactions in condensed phase systems with computational efficiency orders of magnitudes greater than currently possible with ab initio simulation methods, thus facilitating a proper statistical sampling of the coupling to slow, large-scale motions of the system.

  19. Reactivity and Catalytic Activity of Hydrogen Atom Chemisorbed Silver Clusters.

    PubMed

    Manzoor, Dar; Pal, Sourav

    2015-06-18

    Metal clusters of silver have attracted recent interest of researchers as a result of their potential in different catalytic applications and low cost. However, due to the completely filled d orbital and very high first ionization potential of the silver atom, the silver-based catalysts interact very weakly with the reacting molecules. In the current work, density functional theory calculations were carried out to investigate the effect of hydrogen atom chemisorption on the reactivity and catalytic properties of inert silver clusters. Our results affirm that the hydrogen atom chemisorption leads to enhancement in the binding energy of the adsorbed O2 molecule on the inert silver clusters. The increase in the binding energy is also characterized by the decrease in the Ag-O and increase in the O-O bond lengths in the case of the AgnH silver clusters. Pertinent to the increase in the O-O bond length, a significant red shift in the O-O stretching frequency is also noted in the case of the AgnH silver clusters. Moreover, the hydrogen atom chemisorbed silver clusters show low reaction barriers and high heat of formation of the final products for the environmentally important CO oxidation reaction as compared to the parent catalytically inactive clusters. The obtained results were compared with those of the corresponding gold and hydrogen atom chemisorbed gold clusters obtained at the same level of theory. It is expected the current computational study will provide key insights for future advances in the design of efficient nanosilver-based catalysts through the adsorption of a small atom or a ligand.

  20. Irritants and Skin Barrier Function.

    PubMed

    Angelova-Fischer, Irena

    2016-01-01

    The barrier response to irritant challenge involves complex biologic events and can be modulated by various environmental, exposure and host-related factors. Irritant damage to the epidermal barrier elicits a cascade of homeostatic or pathologic responses that could be investigated by both in vitro and in vivo methods providing different information at biochemical and functional level. The present chapter summarizes the changes in key barrier function parameters following irritant exposure with focus on experimental controlled in vivo human skin studies.

  1. Barrier immunity and IL-17

    PubMed Central

    Marks, Benjamin R.; Craft, Joe

    2009-01-01

    CD4+ TH17 cells display a featured role in barrier immunity. This effector population of T cells is important for clearance of microorganisms but can also promote autoimmunity at barrier sites. Recent work has indicated that these effector cells share a pathway with CD4+ regulatory T cells (TR cells) that also have a critical function in barrier protection and immune regulation. The development and function of TH17 cells, and their relationship with TR cells are discussed. PMID:19386512

  2. Silicon Carbide Schottky Barrier Diode

    NASA Technical Reports Server (NTRS)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  3. Growth of organic films on semiconductor surfaces: Fundamental reactivity studies and molecular layer deposition involving isocyanates and isothiocyanates

    NASA Astrophysics Data System (ADS)

    Loscutoff, Paul W.

    The continued pursuit of smaller device dimensions by the semiconductor industry has led to an increased interest in functional organic films. Organics have great potential as advanced materials, owing to the versatility of organic moieties and vast knowledge base of organic reactivity. In order to implement organic films into semiconductor devices, the inorganic/organic hybrid interfaces must be investigated, so that the reactivity at these pivotal features is well-known. In this work organic films are studied in two environments: the Ge(100)-2x1 surface and the SiO2 surface. The reconstructed Ge(100)-2x1 surface offers a well-defined substrate, ideal for fundamental reactivity studies. Organic reactants are deposited under ultrahigh vacuum conditions, allowing reactions between gas-phase organic molecules and the surface to be isolated and analyzed by in situ spectroscopic techniques. By use of infrared (IR) spectroscopy, x-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) modeling, we investigate the reactivity of phenyl and tert-butyl isocyanate and isothiocyanate at the Ge(100)-2x1 surface. The isocyanate and isothiocyanate moieties are both highly reactive groups consisting of a cumulated double bond containing two heteroatoms, allowing for many potential products with the Ge surface. We find that dative bonding through the heteroatoms plays an important role in the surface reactions, functioning as either reaction intermediates or final products depending on the adsorbate. Various cycloaddition products are also observed at the surface, with prominent reactivity trends resulting from the differences in oxygen and sulfur reactivity. In order to study the practical implementation of organic films, molecular layer deposition (MLD) reactions are studied on the hydroxlyated SiO 2 surface. MLD is a layer-by-layer technique, where films are deposited one molecular unit at a time, allowing for film tailorability and composition control down to

  4. Thermal barrier coatings

    SciTech Connect

    Alvin, Mary Anne

    2010-06-22

    This disclosure addresses the issue of providing a metallic-ceramic overlay coating that potentially serves as an interface or bond coat layer to provide enhanced oxidation resistance to the underlying superalloy substrate via the formation of a diffusion barrier regime within the supporting base material. Furthermore, the metallic-ceramic coating is expected to limit the growth of a continuous thermally grown oxide (TGO) layer that has been primarily considered to be the principal cause for failure of existing TBC systems. Compositional compatibility of the metallic-ceramic with traditional yttria-stabilized zirconia (YSZ) top coats is provided to further limit debond or spallation of the coating during operational use. A metallic-ceramic architecture is disclosed wherein enhanced oxidation resistance is imparted to the surface of nickel-based superalloy or single crystal metal substrate, with simultaneous integration of the yttria stabilized zirconia (YSZ) within the metallic-ceramic overlayer.

  5. Schottky barrier solar cell

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.; Yeh, Y. C. M. (Inventor)

    1981-01-01

    A method of fabricating a Schottky barrier solar cell is described. The cell consists of a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive. A thin layer of heavily doped n-type polycrystalling germanium is deposited on the substrate after a passivation layer is deposited to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes to serve as a base layer on which a thin layer of gallium arsenide is vapor-epitaxilly grown followed by a thermally-grown oxide layer. A metal layer is deposited on the oxide layer and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer.

  6. Oxygen diffusion barrier coating

    NASA Technical Reports Server (NTRS)

    Unnam, Jalaiah (Inventor); Clark, Ronald K. (Inventor)

    1987-01-01

    A method for coating a titanium panel or foil with aluminum and amorphous silicon to provide an oxygen barrier abrogating oxidation of the substrate metal is developed. The process is accomplished with known inexpensive procedures common in materials research laboratories, i.e., electron beam deposition and sputtering. The procedures are conductive to treating foil gage titanium and result in submicron layers which virtually add no weight to the titanium. There are no costly heating steps. The coatings blend with the substrate titanium until separate mechanical properties are subsumed by those of the substrate without cracking or spallation. This method appreciably increases the ability of titanium to mechanically perform in high thermal environments such as those witnessed on structures of space vehicles during re-entry

  7. Barriers related to prenatal care utilization among women

    PubMed Central

    Roozbeh, Nasibeh; Nahidi, Fatemeh; Hajiyan, Sepideh

    2016-01-01

    Objectives To investigate barriers related to prenatal care utilization among women. Methods Data was collected in both English and Persian databases. English databases included: the International Medical Sciences, Medline, Web of Science, Scopus, Google Scholar. The Persian databases included: the Iranmedex, the State Inpatient Databases (SID) with the use of related keywords, and on the basis of inclusion-exclusion criteria. The keywords included are barrier, prenatal care, women, access, and preventive factors. OR and AND were Boolean operators. After the study, articles were summarized, unrelated articles were rejected, and related articles were identified. Inclusion criteria were all published articles from 1990 to 2015, written in English and Persian languages. The titles and abstracts are related, and addressed all subjects about barriers related to prenatal care utilization. At the end, all duplicated articles were excluded. There were no restrictions for exclusion or inclusion of articles. Exclusion criteria were failure in reporting in studies, case studies, and lack of access to the full text. Results After searching various databases, 112 related articles were included. After reviewing articles’ titles, 67 unrelated articles and abstracts were rejected, 45 articles were evaluated, 20 of them were duplicated. Then, the qualities of 25 articles were analyzed. Therefore, 5 articles were excluded due to not mentioning the sample size, mismatches between method and data, or results. Total of 20 articles were selected for final analysis. Prenatal care utilization barrier can be divided into various domains such as individual barriers, financial barriers, organizational barriers, social, and cultural barriers. Conclusion To increase prenatal care coverage, it is necessary to pay attention to all domains, especially individual and financial barriers.

  8. Reactivity of isobutane on zeolites: a first principles study.

    PubMed

    Zheng, Xiaobo; Blowers, Paul

    2006-02-23

    In this work, ab initio and density functional theory methods are used to study isobutane protolytic cracking, primary hydrogen exchange, tertiary hydrogen exchange, and dehydrogenation reactions catalyzed by zeolites. The reactants, products, and transition-state structures are optimized at the B3LYP/6-31G* level, and the final energies are calculated using the CBS-QB3 composite energy method. The computed activation barriers are 52.3 kcal/mol for cracking, 29.4 kcal/mol for primary hydrogen exchange, 29.9 kcal/mol for tertiary hydrogen exchange, and 59.4 kcal/mol for dehydrogenation. The zeolite acidity effects on the reaction barriers are also investigated by changing the cluster terminal Si-H bond lengths. The analytical expressions between activation barriers and zeolite deprotonation energies for each reaction are proposed so that accurate activation barriers can be obtained when using different zeolites as catalysts.

  9. GEOCENTRIFUGE STUDIES OF FLOW AND TRANSPORT IN POROUS MEDIA, FINAL REPORT FOR GRANT NUMBER DE-FG02-03ER63567 TO THE UNIVERSITY OF IDAHO (RW SMITH), ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 86598, COUPLED FLOW AND REACTIVITY IN VARIABLY SATURATED POROUS MEDIA

    SciTech Connect

    Robert W. Smith; Carl D. Palmer; Earl D. Mattson

    2007-06-15

    Improved models of contaminant migration in heterogeneous, variably saturated porous media are required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose-zone barriers to contaminant migrations. The development of these improved models requires field and laboratory results to evaluate their efficacy. However, controlled laboratory experiments simulating vadose conditions can require extensive period of time, and often are conducted at condition near saturation rather than the much drier conditions common in many contaminated arid vadose zone sites. Collaborative research undertaken by the Idaho National Laboratory (INL) and the University of Idaho as part of this Environmental Management Science Program project focused on the development and evaluation of geocentrifuge techniques and equipment that allows vadose zone experiments to be conducted for relevant conditions in time frames not possible in conventional bench top experiments. A key and novel aspect of the research was the use of the 2-meter radius geocentrifuge capabilities at the Idaho National Laboratory to conduct unsaturated transport experiments. Specifically, the following activities were conducted ** Reviewing of the theory of unsaturated flow in the geocentrifuge to establish the range of centrifuge accelerations/experimental conditions and the translation of centrifuge results to 1 gravity applications. ** Designing, constructing, and testing of in-flight experimental apparatus allowing the replication of traditional bench top unsaturated transport experiments on the geocentrifuge. ** Performing unsaturated 1-dimenstional column geocentrifuge experiments using conservative tracers to evaluate the effects of increased centrifugal acceleration on derived transport properties and assessing the scaling relationships for these properties. Because the application of geocentrifuge techniques to vadose transport

  10. Barriers to Women in Science

    ERIC Educational Resources Information Center

    Butler, Rosemary

    2013-01-01

    The Presiding Officer of the National Assembly for Wales, Rosemary Butler AM, has put the issue of barriers to women in public life at the top of the political agenda in Wales. She has held sessions with women across Wales to find out what those barriers are and how they can be tackled. On International Women's Day in February, she invited…

  11. Educator's Barriers to Using Technology

    ERIC Educational Resources Information Center

    Brown, April S.

    2012-01-01

    The study is an action research project focused on learning more about the barriers to using technology at one site in Southern California. Learning about the barriers for one school may assist this researcher in learning how to improve the changes of teachers and staff using technology in the field of education. The methodology of this study was…

  12. Psychological Barriers to Behavior Change

    PubMed Central

    Olson, James M.

    1992-01-01

    Adopting a healthy lifestyle often requires changing patterns of behavior. This article describes three categories of psychological barriers to behavior change: those that prevent the admission of a problem, those that interfere with initial attempts to change behavior, and those that make long-term change difficult. Strategies are identified that family physicians can use to overcome the barriers. PMID:21221258

  13. Final Report

    SciTech Connect

    Webb, Robert C.; Kamon, Teruki; Toback, David; Safonov, Alexei; Dutta, Bhaskar; Dimitri, Nanopoulos; Pope, Christopher; White, James

    2013-11-18

    Overview The High Energy Physics Group at Texas A&M University is submitting this final report for our grant number DE-FG02-95ER40917. This grant has supported our wide range of research activities for over a decade. The reports contained here summarize the latest work done by our research team. Task A (Collider Physics Program): CMS & CDF Profs. T. Kamon, A. Safonov, and D. Toback co-lead the Texas A&M (TAMU) collider program focusing on CDF and CMS experiments. Task D: Particle Physics Theory Our particle physics theory task is the combined effort of Profs. B. Dutta, D. Nanopoulos, and C. Pope. Task E (Underground Physics): LUX & NEXT Profs. R. Webb and J. White(deceased) lead the Xenon-based underground research program consisting of two main thrusts: the first, participation in the LUX two-phase xenon dark matter search experiment and the second, detector R&D primarily aimed at developing future detectors for underground physics (e.g. NEXT and LZ).

  14. Epistemological barriers to radical behaviorism.

    PubMed

    O'Donohue, W T; Callaghan, G M; Ruckstuhl, L E

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers.

  15. Epistemological barriers to radical behaviorism

    PubMed Central

    O'Donohue, William T.; Callaghan, Glenn M.; Ruckstuhl, L. E.

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers. PMID:22478314

  16. Hanford Protective Barriers Program asphalt barrier studies -- FY 1988

    SciTech Connect

    Freeman, H.D.; Gee, G.W.

    1989-05-01

    The Hanford Protective Barrier (HPB) Program is evaluating alternative barriers to provide a means of meeting stringent water infiltration requirements. One type of alternative barrier being considered is an asphalt-based layer, 1.3 to 15 cm thick, which has been shown to be very effective as a barrier for radon gas and, hence, should be equally effective as a barrier for the larger molecules of water. Fiscal Year 1988 studies focused on the selection and formulation of the most promising asphalt materials for further testing in small-tube lysimeters. Results of laboratory-scale formulation and hydraulic conductivity tests led to the selection of a rubberized asphalt material and an admixture of 24 wt% asphalt emulsion and concrete sand as the two barriers for lysimeter testing. Eight lysimeters, four each containing the two asphalt treatments, were installed in the Small Tube Lysimeter Facility on the Hanford Site. The lysimeter tests allow the performance of these barrier formulations to be evaluated under more natural environmental conditions.

  17. Astrocytic TYMP and VEGFA drive blood-brain barrier opening in inflammatory central nervous system lesions.

    PubMed

    Chapouly, Candice; Tadesse Argaw, Azeb; Horng, Sam; Castro, Kamilah; Zhang, Jingya; Asp, Linnea; Loo, Hannah; Laitman, Benjamin M; Mariani, John N; Straus Farber, Rebecca; Zaslavsky, Elena; Nudelman, German; Raine, Cedric S; John, Gareth R

    2015-06-01

    In inflammatory central nervous system conditions such as multiple sclerosis, breakdown of the blood-brain barrier is a key event in lesion pathogenesis, predisposing to oedema, excitotoxicity, and ingress of plasma proteins and inflammatory cells. Recently, we showed that reactive astrocytes drive blood-brain barrier opening, via production of vascular endothelial growth factor A (VEGFA). Here, we now identify thymidine phosphorylase (TYMP; previously known as endothelial cell growth factor 1, ECGF1) as a second key astrocyte-derived permeability factor, which interacts with VEGFA to induce blood-brain barrier disruption. The two are co-induced NFκB1-dependently in human astrocytes by the cytokine interleukin 1 beta (IL1B), and inactivation of Vegfa in vivo potentiates TYMP induction. In human central nervous system microvascular endothelial cells, VEGFA and the TYMP product 2-deoxy-d-ribose cooperatively repress tight junction proteins, driving permeability. Notably, this response represents part of a wider pattern of endothelial plasticity: 2-deoxy-d-ribose and VEGFA produce transcriptional programs encompassing angiogenic and permeability genes, and together regulate a third unique cohort. Functionally, each promotes proliferation and viability, and they cooperatively drive motility and angiogenesis. Importantly, introduction of either into mouse cortex promotes blood-brain barrier breakdown, and together they induce severe barrier disruption. In the multiple sclerosis model experimental autoimmune encephalitis, TYMP and VEGFA co-localize to reactive astrocytes, and correlate with blood-brain barrier permeability. Critically, blockade of either reduces neurologic deficit, blood-brain barrier disruption and pathology, and inhibiting both in combination enhances tissue preservation. Suggesting importance in human disease, TYMP and VEGFA both localize to reactive astrocytes in multiple sclerosis lesion samples. Collectively, these data identify TYMP as an

  18. Astrocytic TYMP and VEGFA drive blood–brain barrier opening in inflammatory central nervous system lesions

    PubMed Central

    Chapouly, Candice; Tadesse Argaw, Azeb; Horng, Sam; Castro, Kamilah; Zhang, Jingya; Asp, Linnea; Loo, Hannah; Laitman, Benjamin M.; Mariani, John N.; Straus Farber, Rebecca; Zaslavsky, Elena; Nudelman, German; Raine, Cedric S.

    2015-01-01

    In inflammatory central nervous system conditions such as multiple sclerosis, breakdown of the blood–brain barrier is a key event in lesion pathogenesis, predisposing to oedema, excitotoxicity, and ingress of plasma proteins and inflammatory cells. Recently, we showed that reactive astrocytes drive blood–brain barrier opening, via production of vascular endothelial growth factor A (VEGFA). Here, we now identify thymidine phosphorylase (TYMP; previously known as endothelial cell growth factor 1, ECGF1) as a second key astrocyte-derived permeability factor, which interacts with VEGFA to induce blood–brain barrier disruption. The two are co-induced NFκB1-dependently in human astrocytes by the cytokine interleukin 1 beta (IL1B), and inactivation of Vegfa in vivo potentiates TYMP induction. In human central nervous system microvascular endothelial cells, VEGFA and the TYMP product 2-deoxy-d-ribose cooperatively repress tight junction proteins, driving permeability. Notably, this response represents part of a wider pattern of endothelial plasticity: 2-deoxy-d-ribose and VEGFA produce transcriptional programs encompassing angiogenic and permeability genes, and together regulate a third unique cohort. Functionally, each promotes proliferation and viability, and they cooperatively drive motility and angiogenesis. Importantly, introduction of either into mouse cortex promotes blood–brain barrier breakdown, and together they induce severe barrier disruption. In the multiple sclerosis model experimental autoimmune encephalitis, TYMP and VEGFA co-localize to reactive astrocytes, and correlate with blood–brain barrier permeability. Critically, blockade of either reduces neurologic deficit, blood–brain barrier disruption and pathology, and inhibiting both in combination enhances tissue preservation. Suggesting importance in human disease, TYMP and VEGFA both localize to reactive astrocytes in multiple sclerosis lesion samples. Collectively, these data identify TYMP

  19. Subsurface barrier validation with the SEAtrace{trademark} system

    SciTech Connect

    Sandra Dalvit Dunn; William Lowry; Veraun Chipman

    1999-09-01

    Under contract to the Department of Energy, Science and Engineering Associates has completed development and testing of a subsurface barrier verification and monitoring system. This system, called SEAtrace{trademark}, is able to locate and size leaks with a high degree of accuracy in subsurface barriers that are emplaced in an unsaturated medium. It uses gaseous tracer injection, in-field real-time monitoring, and real time data analysis to evaluate barrier integrity. The approach is: Conservative as it measures vapor leaks in a containment system whose greatest risk is posed by liquid leaks; Applicable to any impermeable type of barrier emplacement technology in the unsaturated zone; Inexpensive as it uses readily available, non-toxic, nonhazardous gaseous tracers, does not require an inordinately large number of sampling points, and injection and sampling points can be emplaced by direct push techniques; Capable of assessing not only a barrier's initial integrity, but can also provide long-term monitoring. To date, six demonstrations of the system have been completed. Results from two of the demonstrations are detailed in this report. They include the final developmental demonstration of the SEAtrace system and a comparison demonstration of two tracer based verification technologies. The final developmental demonstration of SEAtrace was completed at a naval facility in Brunswick, Maine. The demonstration was funded solely by the DOE and was performed in cooperation with the US Navy, the Environmental Protection Agency, and the Maine Department of Environmental Protection.

  20. Glory and thresholds effects in H+D 2 reactive angular scattering

    NASA Astrophysics Data System (ADS)

    Sokolovski, D.

    2003-03-01

    We analyse H+D 2 reactive angular scattering using the S-matrix elements obtained by Aoiz et al. and Althorpe et al. Enhancement of small angle scattering in the v'=3← v=0 H+D 2 delayed reaction is attributed to a glory effect caused by threshold resonances in the v=3 vibrationally adiabatic channel. The oscillatory structures in the reactive angular distributions are shown to be of nearside-farside (NP) origin and are likely to arise from capture in a number of relatively short-lived barrier Regge states at large angular momenta. Padé reconstruction of the reactive matrix element is discussed in detail.