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Sample records for reactive barrier los

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

    Energy Technology Data Exchange (ETDEWEB)

    Kaszuba, J. P. (John P.); Longmire, P. A. (Patrick A.); Strietelmeier, E. A. (Elizabeth A.); Taylor, T. P. (Tammy P.); Den-Baars, P. S. (Peter 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

  2. Permeable Reactive Barrier: Technology Update

    Science.gov (United States)

    2011-06-01

    Reactivity of Partially Reduced Arylhydroxylamine and Nitrosoarene Metabolites of 2,4,6-Trinitrotoluene (TNT) Towards Biomass and Humic Acids...Electron micrograph of bone- char phosphate pellets illustrating morphology and microporosity of apatite materials...groundwater velocity of approximately threefold indicate partial clogging due to the formation of mineral precipitates. Monitoring results from a large

  3. Reactive barriers for 137Cs retention.

    Science.gov (United States)

    Krumhansl, J L; Brady, P V; Anderson, H L

    2001-02-01

    137Cs was dispersed globally by cold war activities and, more recently, by the Chernobyl accident. Engineered extraction of 137Cs from soils and groundwaters is exceedingly difficult. Because the half-life of 137Cs is only 30.2 years, remediation might be more effective (and less costly) if 137Cs 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 135Cs (half-life 2.3 x 10(6) years) in addition to 137Cs. 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 desorption 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 LiNO3 and LiCl washes. Washed clays 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-Ill 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 Cs-doped for 110 days and subjected to an extreme and prolonged rinsing process. All the clays exhibited some capacity for irreversible Cs uptake. However, the residual loading was greatest on K-Mbt (approximately 0.33 wt.% Cs). Thus, this clay would be the optimal material for constructing artifical reactive barriers.

  4. Reactive barriers: hydraulic performance and design enhancements.

    Science.gov (United States)

    Painter, B D M

    2004-01-01

    The remediation of contaminated ground water is a multibillion-dollar global industry. Permeable reactive barriers (PRBs) are one of the leading technologies being developed in the search for alternatives to the pump-and-treat method. Improving the hydraulic performance of these PRBs is an important part of maximizing their potential to the industry. Optimization of the hydraulic performance of a PRB can be defined in terms of finding the balance between capture, residence time, and PRB longevity that produces a minimum-cost acceptable design. Three-dimensional particle tracking was used to estimate capture zone and residence time distributions. Volumetric flow analysis was used for estimation of flow distribution across a PRB and in the identification of flow regimes that may affect the permeability or reactivity of portions of the PRB over time. Capture zone measurements extended below the base of partially penetrating PRBs and were measured upgradient from the portion of aquifer influenced by PRB emplacement. Hydraulic performance analysis of standard PRB designs confirmed previously presented research that identified the potential for significant variation in residence time and capture zone. These variations can result in the need to oversize the PRB to ensure that downgradient contaminant concentrations do not exceed imposed standards. The most useful PRB design enhancements for controlling residence time and capture variation were found to be customized downgradient gate faces, velocity equalization walls, deeper emplacement of the funnel than the gate, and careful manipulation of the hydraulic conductivity ratio between the gate and the aquifer.

  5. Reactive Membrane Barriers for Containment of Subsurface Contamination

    Energy Technology Data Exchange (ETDEWEB)

    William A. Arnold; Edward L. Cussler

    2007-02-26

    The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe{sup 0}) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe{sup 0} and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu{sup 2+}) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe{sup 0} barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a

  6. Laboratory Research into Permeable Reactive Barriers for Groundwater Remediation

    Institute of Scientific and Technical Information of China (English)

    Anthony Adzomani; Jun Dong; Yan Jin

    2003-01-01

    Permeable Reactive Barriers (PRB) is a new technology for groundwater pollution remediation. Contaminants are converted into harmless by products in situ as the polluted water passes through a reactive wall. Experimental results demonstrate how reactive media can be used to remove contaminants from polluted water by laying the reactive wall across the flow direction of the water. The most comprehensively studied and applied reactive barrier type uses granulated Zero Valent Iron (ZVI) particles. In this process elemental iron provides a reducing environment which makes reductive dechlorination of chlorinated organic compounds feasible or changes redox sensitive metals, so that they are immobilized by a precipitation reaction. A reactive wall column which is made up of ZVI, sand and zeolite has shown the highest contaminant removal capacity compared to the other two which have different components. The potentials of ZVI, zeolite and Powdered Activated Carbon (PAC) to remove contaminants are due to their different physico-chemical proper-ties which make them to "sorb"metal contaminants. The results of this experiment show that PRB technology is an efficient method for the treatment of leachate-contaminated groundwater.

  7. Automated Impedance Tomography for Monitoring Permeable Reactive Barrier Health

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Murdoch, L. [FRx Inc., Cincinnati, OH (United States)]|[Clemson Univ., SC (United States); Siegrist, B. [Oak Ridge National Lab., TN (United States); Vesper, S. [Univ. of Cincinnati, OH (United States)] [and others

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  11. Assessment of solid reactive mixtures for the development of biological permeable reactive barriers.

    Science.gov (United States)

    Pagnanelli, Francesca; Viggi, Carolina Cruz; Mainelli, Sara; Toro, Luigi

    2009-10-30

    Solid reactive mixtures were tested as filling material for the development of biological permeable reactive barriers for the treatment of heavy metals contaminated waters. Mixture selection was performed by taking into account the different mechanisms operating in sulphate and cadmium removal with particular attention to bioprecipitation and sorption onto the organic matrices in the mixtures. Suspensions of eight reactive mixtures were tested for sulphate removal (initial concentration 3 g L(-1)). Each mixture was made up of four main functional components: a mix of organic sources for bacterial growth, a neutralizing agent, a porous medium and zero-valent iron. The best mixture among the tested ones (M8: 6% leaves, 9% compost, 3% zero-valent iron, 30% silica sand, 30% perlite, 22% limestone) presented optimal conditions for SRB growth (pH 7.8 +/- 0.1; E(h)= -410 +/- 5 mV) and 83% sulphate removal in 22 days (25% due to bioreduction, 32% due to sorption onto compost and 20% onto leaves). M8 mixture allowed the complete abatement of cadmium with a significant contribution of sorption over bioprecipitation (6% Cd removal due to SRB activity). Sorption properties, characterised by potentiometric titrations and related modelling, were mainly due to carboxylic sites of organic components used in reactive mixtures.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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.

  14. Development of Permeable Reactive Barriers (PRB) Using Edible Oils

    Science.gov (United States)

    2008-06-01

    Remediation Technology Roundtable GC gas chromatograph GMO Glycerol Monooleate GRAS Generally Recognized As Safe H2O2 Hydrogen Peroxide HLB...Emulsions prepared from food -grade edible oils have been used in a variety of locations to stimulate anaerobic biodegradation of chlorinated solvents... food -grade edible oils and then injected into the contaminated aquifer in a barrier configuration using either conventional wells or Geoprobe

  15. Redox-active media for permeable reactive barriers

    Energy Technology Data Exchange (ETDEWEB)

    Sivavec, T.M. [General Electric Corp. Research and Development Center, Schenectady, NY (United States); 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.

  16. Treatment of fue diesel with a permeable reactive barrier technology

    Directory of Open Access Journals (Sweden)

    SANTIAGO ALONSO CARDONA GALLO

    2007-01-01

    Full Text Available La investigación estudió el tratamiento de diesel combustibles de producción mexicana contenidos en agua con un sistema de barrera reactiva permeables a escala de laboratorio (siete columnas. Se uso un suelo agrícola como medio reactivo. Se aplico peroxido de hidrógeno al 50% industrial como fuente de oxigeno y nitrógeno en urea al 46% como nutriente. Se caracterizo el medio reactivo con los principales parámetros de interés (humedad, materia orgánica, pH, nitrógeno total, fósforo disponible, clasificación del suelo, conductividad eléctrica, sólidos suspendidos volátiles, densidad real y aparente, porosidad, textura, color, salinidad, conductividad hidráulica, capacidad de campo y densidad de bacterias. Se determinaron las cinéticas de degradación y la capacidad de adsorción del diesel en el medio reactivo. Las barreras reactivas permeables se diseñaron con los resultados cinéticos obtenidos en los reactores por lotes. Las columnas tenían dimensiones de 30 cm de longitud y 10 cm de diámetro. Las cinéticas de determinaron durante 18 días y las columnas se corrieron durante 70 días presentando remociones arriba del 80%. Se usaron concentraciones iniciales de diesel de 15,000 mg/L. Para la modelación de la adsorción se aplicaron las ecuaciones de Freundlich y Langmuir, donde esta ultima presentó un mejor ajuste a los datos a los datos experimentales y una mayor capacidad de adsorción. Para el suministro de los nutrientes y oxigeno se aplico el modelo propuesto por McCarty y la ecuación media para diesel propuesta por Jackson. Se determinó una velocidad de degradación de 0.0908 d-1, un coeficiente de distribución del diesel en el medio reactivo de 0.8 ml/g, una capacidad de adsorción de diesel en el medio reactivo de 13.50 mg/L y un factor de retardo de 3.69

  17. Groundwater protection from cadmium contamination by permeable reactive barrier in Qian'an of Jilin, China

    Institute of Scientific and Technical Information of China (English)

    Alkali Mohammed; Changlai XIAO; Chao DU

    2008-01-01

    This research studies the reliability of an activated carbon permeable reactive barrier in removing cadmium from a contaminated shallow aquifer. Laboratory tests have been performed to characterize the equilibrium and kinetic adsorption properties of the activated carbon in cadmium-containing aqueous solutions. A 2D numerical model has been used to describe pollutant transport within a groundwater and the pollutant adsorption on the permeable reactive barrier (PRB). In particular, it has been considered the case of a PAB used to protect a lake or downstream from Cd (Ⅱ) contaminated groundwater. Numerical results show that the PAB can achieve a long-term efficiency by preventing lake or downstream pollution for several months.

  18. Removal of chromate in a permeable reactive barrier using zero-valent iron

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Locht, T

    2002-01-01

    Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces by the pre......Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces...

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

    Science.gov (United States)

    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.

  20. Dexou low pH plume baseline permeable reactive barrier options

    Energy Technology Data Exchange (ETDEWEB)

    Phifer, M.A.

    2000-06-20

    The current Environmental Restoration Department (ERD) Permeable Reactive Barrier (PRB) baseline configuration consists of a limestone trench and a granular cast iron trench in series. This report provides information relative to the use of PRB technology for the remediation of the D-Area low pH groundwater plumes.

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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...

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

    Science.gov (United States)

    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...

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

    NARCIS (Netherlands)

    Mahmoodlu, M.G.; Hassanizadeh, S.M.; Hartog, Niels; Raoof, A.

    2014-01-01

    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 oxi

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

    Science.gov (United States)

    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.

  7. A calcite permeable reactive barrier for the remediation of Fluoride from spent potliner (SPL) contaminated groundwater

    DEFF Research Database (Denmark)

    Turner, B.D.; Binning, Philip John; Sloan, S.W.

    2008-01-01

    The use of calcite (CaCO3) as a substrate for a permeable reactive barrier (PRB) for removing fluoride from contaminated groundwater is proposed and is illustrated by application to groundwater contaminated by spent potliner leachate (SPL), a waste derived from the aluminium smelting process....... The paper focuses on two issues in the implementation of calcite permeable reactive barriers for remediating fluoride contaminated water: the impact of the groundwater chemical matrix and CO2 addition on fluoride removal. Column tests comparing pure NaF solutions, synthetic SPL solutions, and actual SPL...... leachate indicate that the complex chemical matrix of the SPL leachate can impact fluoride removal significantly. For SPL contaminant mixtures, fluoride removal is initially less than expected from idealized, pure, solutions. However, with time, the effect of other contaminants on fluoride removal...

  8. Decontamination of groundwater by permeable reactive barriers; Descontaminacion de aguas subterraneas mediante barreras reactivas permeables

    Energy Technology Data Exchange (ETDEWEB)

    Navarro Flores, A.; Chimenos, J. M.

    2002-07-01

    Passive in-situ remediation techniques have seen increased application at contaminated aquifers in recent years as a means of contaminant control and as means of passively treating contaminants in groundwater, because of their low economic cost and minor ground occupation. Permeable reactive barriers (PRBs) are based on the creation of a subsurface barrier, where groundwater contaminants are intercepted in the saturated zone, establishing a passive system of control and contamination treatment, in particular in the heavy metals removal. This paper discusses, related to PRBs experimentation, the results obtained from laboratory experiences by means of Mg oxides and sandy soils as barrier materials, showing a high removal of Cd, Cu, Ni, Fe, Pb and Zn. (Author) 21 refs.

  9. Decolorization of reactive textile dyes using water falling film dielectric barrier discharge.

    Science.gov (United States)

    Dojčinović, Biljana P; Roglić, Goran M; Obradović, Bratislav M; Kuraica, Milorad M; Kostić, Mirjana M; Nešić, Jelena; Manojlović, Dragan D

    2011-08-30

    Decolorization of reactive textile dyes Reactive Black 5, Reactive Blue 52, Reactive Yellow 125 and Reactive Green 15 was studied using advanced oxidation processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film dielectric barrier discharge (DBD). Used initial dye concentrations in the solution were 40.0 and 80.0mg/L. The effects of different initial pH of dye solutions, and addition of homogeneous catalysts (H(2)O(2), Fe(2+) and Cu(2+)) on the decolorization during subsequent recirculation of dye solution through the DBD reactor, i.e. applied energy density (45-315kJ/L) were studied. Influence of residence time was investigated over a period of 24h. Change of pH values and effect of pH adjustments of dye solution after each recirculation on the decolorization was also tested. It was found that the initial pH of dye solutions and pH adjustments of dye solution after each recirculation did not influence the decolorization. The most effective decolorization of 97% was obtained with addition of 10mM H(2)O(2) in a system of 80.0mg/L Reactive Black 5 with applied energy density of 45kJ/L, after residence time of 24h from plasma treatment. Toxicity was evaluated using the brine shrimp Artemia salina as a test organism.

  10. Solid phase studies and geochemical modelling of low-cost permeable reactive barriers

    Energy Technology Data Exchange (ETDEWEB)

    Bartzas, Georgios, E-mail: gbartzas@metal.ntua.gr [Laboratory of Metallurgy, School of Mining and Metallurgical Engineering, National Technical University of Athens, Zografos Campus, 15780 Athens (Greece); Komnitsas, Kostas [Department of Mineral Resources Engineering, Technical University of Crete, 73100 Chania (Greece)

    2010-11-15

    A continuous column experiment was carried out under dynamic flow conditions in order to study the efficiency of low-cost permeable reactive barriers (PRBs) to remove several inorganic contaminants from acidic solutions. A 50:50 w/w waste iron/sand mixture was used as candidate reactive media in order to activate precipitation and promote sorption and reduction-oxidation mechanisms. Solid phase studies of the exhausted reactive products after column shutdown, using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), confirmed that the principal Fe corrosion products identified in the reactive zone are amorphous iron (hydr)oxides (maghemite/magnetite and goethite), intermediate products (sulfate green rust), and amorphous metal sulfides such as amFeS and/or mackinawite. Geochemical modelling of the metal removal processes, including interactions between reactive media, heavy metal ions and sulfates, and interpretation of the ionic profiles was also carried out by using the speciation/mass transfer computer code PHREEQC-2 and the WATEQ4F database. Mineralogical characterization studies as well as geochemical modelling calculations also indicate that the effect of sulfate and silica sand on the efficiency of the reactive zone should be considered carefully during design and operation of low-cost field PRBs.

  11. Reactive barrier system for nitrate removal from mine effluents in northern Sweden: Laboratory experiments

    Science.gov (United States)

    Herbert, Roger

    2010-05-01

    Laboratory column experiments have been conducted to determine nitrate removal rates from mine effluents by denitrification, with the purpose of providing initial data for the construction of a pilot scale reactive barrier system at the Malmberget iron mine, Sweden. Experiments were conducted at several different flow rates at 5C, 10C and room temperature; annual mean temperatures at the Malmberget site lie close to 0C. Columns were filled with an organic substrate consisting of sawdust mixed with sewage sludge, the source of denitrifying bacteria, supported by oven-dried clay pellets. Apparent denitrification rates, calculated from inflow and outflow nitrate concentrations and column hydraulic residence time, ranged from 5 to 13 mg N/L/d, with the lowest rates corresponding to the 5C experiments. These rates are, however, limited to a certain degree by the low flow rate and the supply of electrons acceptors (i.e. nitrate) to denitrifying bacteria. Results from the column experiment have been used to construct a barrier system in Malmberget, Sweden. Trial runs with the pilot-scale barrier will be conducted during 2010, with the purpose of determining the performance of the barrier as mean air temperatures increase from below to above 0C and saturated flow commences in the barrier. The barrier system is constructed as a rectangular container with steel sheet walls (9m length in flow direction, 1.5m deep), and the flow rate will be adjusted to a hydraulic residence time of 1 day. The pilot-scale barrier system currently lies above ground, but a permanent barrier system would be installed below the ground surface so that the system can be maintained at positive temperatures throughout the year.

  12. Reactivity of nano zero-valent iron in permeable reactive barriers

    Directory of Open Access Journals (Sweden)

    Pawluk Katarzyna

    2015-03-01

    Full Text Available In this paper, the ability of nZVI to remove heavy metals (Cd, Cu, Ni, Pb, Zn from multicomponent aqueous solutions was investigated through batch experiments. The experimental data were fitted to a second-order kinetic model based on solid capacity. The data for copper and lead fitted well into the second-order kinetic model, thus suggesting that the adsorption had a physical character. The values of the removal ratio and the second-order rate constant indicated that the order of adsorption priority of nZVI was as follows: Pb>Cu>Zn>Cd>Ni. The adsorption isotherm data were described by the most conventional models (Henry, Freundlich, and Langmuir. Equilibrium tests showed that copper and zinc were removed from the solution by adsorption processes, i.e., complexation and competitive adsorption. The test results suggested that the removal processes using nZVI are more kinetic than equilibrium. The study demonstrated that nZVI is favorable reactive material; however, comprehensive investigation should be performed for further in situ applications in PRB technology.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  15. Decolorization of reactive textile dyes using water falling film dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Dojcinovic, Biljana P. [Institute of Chemistry, Technology and Metallurgy, Center of Chemistry, Studentski trg 12-16, 11000 Belgrade (Serbia); Roglic, Goran M. [Faculty of Chemistry, University of Belgrade, P.O. Box 158, 11000 Belgrade (Serbia); Obradovic, Bratislav M., E-mail: obrat@ff.bg.ac.rs [Faculty of Physics, University of Belgrade, P.O. Box 368, 11000 Belgrade (Serbia); Kuraica, Milorad M. [Faculty of Physics, University of Belgrade, P.O. Box 368, 11000 Belgrade (Serbia); Kostic, Mirjana M. [Faculty of Technology and Metallurgy, Department of Textile Engineering, Karnegijeva 4, 11000 Belgrade (Serbia); Nesic, Jelena; Manojlovic, Dragan D. [Faculty of Chemistry, University of Belgrade, P.O. Box 158, 11000 Belgrade (Serbia)

    2011-08-30

    Highlights: {yields} Decolorization of four reactive textile dyes using non-thermal plasma reactor. {yields} Influence of applied energy on decolorization. {yields} Effects of initial pH and addition of homogeneous catalysts. {yields} Toxicity evaluation using the brine shrimp as a test organism. - Abstract: Decolorization of reactive textile dyes Reactive Black 5, Reactive Blue 52, Reactive Yellow 125 and Reactive Green 15 was studied using advanced oxidation processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film dielectric barrier discharge (DBD). Used initial dye concentrations in the solution were 40.0 and 80.0 mg/L. The effects of different initial pH of dye solutions, and addition of homogeneous catalysts (H{sub 2}O{sub 2}, Fe{sup 2+} and Cu{sup 2+}) on the decolorization during subsequent recirculation of dye solution through the DBD reactor, i.e. applied energy density (45-315 kJ/L) were studied. Influence of residence time was investigated over a period of 24 h. Change of pH values and effect of pH adjustments of dye solution after each recirculation on the decolorization was also tested. It was found that the initial pH of dye solutions and pH adjustments of dye solution after each recirculation did not influence the decolorization. The most effective decolorization of 97% was obtained with addition of 10 mM H{sub 2}O{sub 2} in a system of 80.0 mg/L Reactive Black 5 with applied energy density of 45 kJ/L, after residence time of 24 h from plasma treatment. Toxicity was evaluated using the brine shrimp Artemia salina as a test organism.

  16. Sea sand for reactive barriers; Arena de mar para barreras reactivas

    Energy Technology Data Exchange (ETDEWEB)

    Garcia R, G.; Ordonez R, E.; Ordonez R, En. [Instituto Nacional de Investigaciones Nucleares, Km. 36.5 Carretera Mexico-Toluca, Municipio de Ocoyoacac, 52045 Estado de Mexico (Mexico)

    2002-07-01

    Some phosphates have the property to suck in radioactive metals in solution, what it is taken in advance to make reactive barriers which are placed in the nuclear waste repositories. In an effort for contributing to the study of this type of materials, it has been obtained the zirconium silicate (ZrSiO{sub 4}) and the alpha zirconium hydrogen phosphate (Zr(HPO{sub 4}) 2H{sub 2}O) starting from sea sand in an easy and economic way. (Author)

  17. Transformation of reactive iron minerals in a permeable reactive barrier (biowall) used to treat TCE in groundwater.

    Science.gov (United States)

    He, Y Thomas; Wilson, John T; Wilkin, Richard T

    2008-09-01

    Iron and sulfur reducing conditions generally develop in permeable reactive barrier systems (PRB) constructed to treat contaminated groundwater. These conditions allow formation of FeS mineral phases. FeS readily degrades TCE, but a transformation of FeS to FeS2 could dramatically slow the rate of TCE degradation in the PRB. This study uses acid volatile sulfide (AVS) and chromium reducible sulfur (CRS) as probes for FeS and FeS2 to investigate iron sulfide formation and transformation in a column study and PRB field study dealing with TCE degradation. Solid phase iron speciation shows that most of the iron is reduced and sulfur partitioning measurements show that AVS and CRS coexist in all samples, with the conversion of AVS to CRS being most significant in locations with potential oxidants available. In the column study, 54% of FeS was transformed to FeS2 after 2.4 years. In the field scale PRB, 43% was transformed after 5.2 years. Microscopy reveals FeS, Fe3S4 and FeS2 formation in the column system; however, only pyrite formation was confirmed byX-ray diffraction. The polysulfide pathway is most likely the primary mechanism of FeS transformation in the system, with S0 as an intermediate species formed through H2S oxidation.

  18. Performance Assessment and Monitoring of a Permeable Reactive Barrier for the Remediation of a Contaminated Site

    Directory of Open Access Journals (Sweden)

    Valerio Zolla

    2007-01-01

    Full Text Available The present study illustrates the long-term monitoring plan carried out in order to investigate the performance of a zero-valent iron permeable reactive barrier (PRB at a chlorinated solvents’ site. The cleanup intervention has been undertaken at an industrial landfill located near the city of Turin (Italy and represents the first full-scale application of this technology in Italy. The monitoring plan started in November 2005 with the aim to verify the attainment of the cleanup goals and to evaluate the efficiency status of the PRB. Controls focuses not only on contaminant monitoring but also on the hydraulic and chemical conditions created by the barrier, in order to evaluate potential long term effects of secondary biogeochemical processes (e.g. mineral precipitation, microbially-mediated redox transformation, gas accumulation on PRB performance. The monitoring plan provides controls on groundwater chemistry (target contaminants and geochemical indicators and core sampling for mineralogical analysis of zero-valent iron by X-ray diffraction and scanning electron microscopy. The first, partial results of the monitoring activity are illustrated. Monitoring data clearly indicate that the plume is being adequately captured and treated in order to accomplish the clean-up goals with a good safety margin. However, it results that mineral precipitation and gas phase accumulation could determine, over time, a decreasing in hydraulic conductivity and porosity of the barrier, thus modifying the flow field through the reactive cell. Besides the monitoring controls, further investigations will be performed to assess the occurring microbial process and to evaluate their impact on PRB performance.

  19. Polymer/Silicate composites – New Materials for Subsurface Permeable Reactive Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Mason K. Harrup; Michael G. Jones; Linda Polson; Byron White

    2008-09-01

    Investigations were performed into the suitability of novel nanocomposites to serve as materials for subsurface permeable reactive barriers (PRBs). These new materials are Type I nanocomposites – they are preformed organic polymers embedded in an inorganic matrix without significant covalent bonding between the components. The required properties for these materials to function efficiently are: 1) a tunable water passing rate to approximate the hydraulic conductivity of the subsurface environment where the PRB will be placed, 2) sufficient mechanical strength (both wet and dry) to maintain barrier integrity, 3) the ability to incorporate selective metal sequestration agents so that they remain active – yet do not leach from the barrier, and 4) to be deployable through direct injection methods such that trenching is not needed. Additionally, there is a need to keep the technology as low cost as possible, while remaining reliable. Results recently obtained in our laboratory show that our materials, remarkably, exhibit all of these properties and show great promise as vadose zone deployable PRBs.

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

    Science.gov (United States)

    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.

    Science.gov (United States)

    Spéder, Pauline; Brand, Andrea H

    2014-08-11

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2012-11-06

    A novel reactive electrochemical flow system consisting of an iron anode and a 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 protons 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 the foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (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 in 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.

  5. [Health-worker barriers to syphilis screening in pregnant women in Bolivia's Los Andes network].

    Science.gov (United States)

    Tinajeros, Freddy; Ares, Lucila Rey; Elías, Vanessa; Reveiz, Ludovic; Sánchez, Franz; Mejía, Martha; Hernández, Rosalinda; Revollo, Rita

    2017-05-25

    Identify health-worker barriers that keep pregnant women who receive prenatal care from being screened for syphilis (Los Andes Health Network, Bolivia). Semi-structured interviews were done with 46 health care providers and 249 clinical health records of pregnant women were analyzed in eight public health facilities in the Los Andes network. Health-worker barriers to syphilis screening in pregnant women included lack of time by personnel to raise awareness of the benefit of syphilis screening; some mentioned that syphilis tests should only be done in facilities that attend deliveries and have a laboratory; lack of communication between clinicians and laboratory personnel; and problems with provision of supplies and reagents. The clinical record review found that only 55.4% contained syphilis laboratory results and only 37.4% of perinatal clinical histories had records of laboratory results. The interviews found that providers believe that syphilis screening is done in 100% of pregnant women receiving prenatal care. Syphilis screening is not being done according to Bolivia's strategy for the elimination of congenital syphilis, and is not done on more than half of pregnant women in prenatal care with perinatal clinical history records. This is not perceived by health professionals and can become a barrier to syphilis screening in pregnant women.

  6. Reactive fluxes delivered by dielectric barrier discharge filaments to slightly wounded skin

    Science.gov (United States)

    Babaeva, Natalia Yu; Kushner, Mark J.

    2013-01-01

    The application of atmospheric-pressure plasmas to human tissue has been shown to have therapeutic effects for wound healing and in treatment of skin diseases. In this paper, we report on a computational study of the intersection of plasma filaments in a dielectric barrier discharge (DBD) with a small wound in human skin in the context of plasma medicine. The wound is represented as a small cut in the epidermal layer of cells. Intracellular structures and their electrical properties were incorporated into the two-dimensional computational mesh in order to self-consistently couple gas phase plasma transport with the charging of the surface of the wound. We quantify the fluxes of reactive oxygen and nitrogen species, ions and photons produced in or diffusing into the wound as might occur during the first few discharge pulses of treatment. Comparison is made to fluxes predicted by global modelling. We show that the relative location of the plasma filament with respect to the wound is important on plasma time scales (ns) for ions and photons, and for radicals directly produced by electron impact processes. On the longer-term diffusion time scales (ms) the position of the plasma filament relative to the wound is not so critical. For typical DBD conditions, the magnitude of these fluxes to the cellular surfaces corresponds to fluences of radicals nearly equal to the surface site density. These results imply that the biological reactivity is limited by reaction probabilities and not the availability of radical fluxes.

  7. Decolorization of reactive black 5 using dielectric barrier discharge in the presence of inorganic salts

    Directory of Open Access Journals (Sweden)

    Dojčinović Biljana P.

    2012-01-01

    Full Text Available Inorganic salts improve the coloration of textiles, which increase pollution load on dyehouse effluent in general. Decolorization of reactive textile dye C.I. Reactive Black 5 was studied using Advanced Oxidation Processes (AOPs in a non-thermal plasma reactor, based on coaxial water falling film Dielectric Barrier Discharge (DBD. Initial dye concentration in the solution was 40.0 mg L-1. The effects of addition of inorganic salt different high concentrations (NaCl, Na2SO4 and Na2CO3 on the degree of decolorization were studied. Recirculation of dye solution through the DBD reactor with applied energy density 45-315 kJ L-1 was used. The influence of residence time was investigated after 5 minutes and 24 hours of plasma treatment. Decolorization of the dyes was monitored by spectrophotometric measurement. Changes of pH values and the conductivity of dye solution after each recirculation were tested. The most effective decolorization of over 90% was obtained with the addition of NaCl (50 g L-1, applied energy density of 135 kJ L-1 and after residence time of 24 hours of plasma treatment. Decolorization of solutions containing inorganic salts Na2SO4 and Na2CO3 were lower than for the solution without salt.

  8. In situ Remediation of Petroleum Contaminated Groundwater by Permeable Reactive Barrier with Hydrothermal Palygorskite as Medium

    Institute of Scientific and Technical Information of China (English)

    ZHANG Sheng-yu; ZHANG Yu-ling; SU Xiao-si; ZHANG Ying

    2013-01-01

    The permeable reactive barrier(PRB) has proven to be a cost-effective technique to remediate the petroleum contaminated groundwater at a northeast field site in China.In this study,the geology,hydrogeology and contamination characterization of the field site were investigated and the natural hydrothermal palygorskite was chosen as a reactive medium.Furthermore,the adsorption of the total petroleum hydrocarbons(TPH) in the groundwater onto hydrothermal palygorskite and the adsorption kinetics were investigated.The results indicate that the removal rates of TPH,benzene,naphthalene and phenantharene could all reach up to 90% by hydrothermal palygorskite with a diameter of 0.25-2.00 mm that had been thermally pretreated at 140 ℃.The adsorption of TPH onto hydrothermal palygorskite after pretreatment followed a pseudo-second-order kinetic model and a Langmuir adsorption isotherm,suggesting that the theoretic adsorption capacity of hydrothermal palygorskite for adsorbate could be 4.2 g/g.Scanning electron microscopy(SEM),infrared spectroscopy(IR),X-ray diffraction(XRD) and X-ray fluorescence spectroscopy(XRF) were carried out to analyze the adsorption mechanism.The results reveal that hydrothermal palygorskite is a fibrous silicate mineral enriched in Mg and A1 with large surface area and porosity.The dense cluster acicular and fibrous crystal of hydrothermal palygorskite,and its effect polar group —OH played an important role in the physical and chemical adsorption processes of it for contaminants.This study has demonstrated hydrothermal palygorskite is a reliable reactive medium for in situ remediation of petroleum contaminated groundwater at field sites.

  9. Analytical solutions for the flow fields near funnel-and-gate reactive barriers with hydraulic losses

    Science.gov (United States)

    Klammler, Harald; Hatfield, Kirk

    2009-02-01

    Permeable reactive barriers (PRBs) are a passive in situ technology that is based on the interception and physical, chemical, and/or biological remediation of a contaminant plume through installation of reactive material in an aquifer. The present work is an extension and generalization of a previous paper and derives analytical expressions for flow fields toward PRBs in two dimensions on the basis of the conformal mapping approach. Considered is the classic funnel-and-gate configuration with perpendicular funnel arms (PFGs) as well as PRBs with velocity equalization walls. While the aquifer is assumed to be homogeneous in a uniform far field, the hydraulic conductivity of the reactive material is allowed to take arbitrary values above or below the aquifer conductivity. At the up- and down-gradient interfaces between reactor and aquifer, highly permeable gravel packs are assumed to establish constant head conditions. The flow fields are analyzed regarding the widths and shapes of respective capture zones as functions of PRB type and dimensions, reactor hydraulic resistance (including flow divergence and longevity), and ambient groundwater flow direction. Expressions for discharge fields are developed as needed for particle-tracking algorithms. Charts of relative capture width are given to facilitate PRB design and may be included in more comprehensive PRB design/optimization approaches. An efficient approach is presented to estimate reactor conductivity and capture flow from monitoring the hydraulic loss at the reactor. Inherent assumptions and results are validated against numerical flow field solutions and water level field data for the PFG PRB at the Moffett Federal Airfield, California.

  10. Electrical Resistivity Modeling of a Permeable Reactive Barrier for Vista Engineering Technologies: Summary

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, A L; Daily, W D

    2003-11-21

    We have performed a numerical modeling study that evaluated the capacity of electrical resistance tomography (ERT) to detect flaws in a passive reactive barrier (PRB). The model barrier is based on a real barrier described in the literature Slater and Binley (2003). It consists of highly conducting, granular iron emplaced within a trench. We assumed that the barrier was filled with a mixture of iron and sand, and that vertical electrode arrays were embedded within the barrier. We have considered (a) characterization and (b) monitoring scenarios. For (a), the objective is to use tomographs of absolute resistivity to detect construction flaws and inhomogeneities in iron distribution shortly after installation. For (b), the objective is to use resistivity change tomographs to detect iron oxidation and barrier plugging as a function of time. The study considered varying PRB hole sizes and locations. For any given model, a hole was located right next to and near the center of an electrode array (maximum sensitivity and resolution expected), at the center between two electrode arrays (moderate sensitivity and resolution), or near the bottom centered between the two arrays (minimum sensitivity and resolution). We also considered various hole sizes. The smallest hole considered had a height and a width of 0.33 m (0.11 m{sup 2}), or 1/2 of the electrode spacing within an array; the depth of the hole was always equal to the thickness of the barrier (0.66m). The largest hole had a height and a width of 1.22 m (1.74 m{sup 2}). We also modeled a medium sized hole with a height and a width of 0.66 m (0.44 m{sup 2}). The PRB material had an electrical resistivity of 0.3 ohm-m (sand/iron mix) while the hole's resistivity was 3.0 ohm-m. The study also considered various array aspect ratios because it is well known that aspect ratio controls sensitivity and resolution when line arrays of electrodes are used (Ramirez et al., 1993). Aspect ratio is defined as the distance between

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

    Science.gov (United States)

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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. Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

    DEFF Research Database (Denmark)

    Muchitsch, Nanna; Nooten, Thomas Van; Bastiaens, Leen;

    2011-01-01

    An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important r...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C.; Szecsody, James (PNNL); Rigali, Mark J.; Vermuel, Vince (PNNL); Leullen, Jon (AECOM)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    Science.gov (United States)

    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.

  20. Exact analytical evaluation of time dependent transmission coefficient from the method of reactive flux for an inverted parabolic barrier.

    Science.gov (United States)

    Chakrabarti, Rajarshi

    2007-04-01

    The paper demonstrates an elegant way of combining the normal mode analysis and the method of reactive flux to evaluate the time dependent transmission coefficient for a classical particle coupled to a set of harmonic oscillators, surmounting a one dimensional barrier. The author's analysis reproduces the results of Kohen and Tannor [J. Chem. Phys. 103, 6013 (1995)] and Bao [J. Chem. Phys. 124, 114103 (2006)]. Moreover the use of normal mode analysis has a better physical meaning.

  1. Assessing the performance of a permeable reactive barrier-aquifer system using a dual-domain solute transport model

    Science.gov (United States)

    Chen, Jui-Sheng; Hsu, Shao-Yiu; Li, Ming-Hsu; Liu, Chen-Wuing

    2016-12-01

    Transport behavior through a permeable reactive barrier (PRB)-aquifer system is complicated because of the different physical and chemical properties of the PRB and the aquifer. Dual-domain solute transport models are efficient tools for better understanding the various processes and mechanisms of reactive solute transport through a PRB-aquifer system. This study develops a dual-domain analytical model to assess the physical and chemical processes of two-dimensional reactive solute transport through a PRB-aquifer system. The dispersion processes of a dual-domain system on the solute transport are investigated. The results show that the dispersion parameters in a dual-domain system synchronously govern the dynamic shape of the contaminant plume. The low longitudinal and transverse dispersion coefficients of a dual-domain system may restrict the spreading of the plume and elevate the plume's concentration level. The derived analytical solution is applied to explore how the different reactive transport processes affect the performance of a PRB-aquifer system. The results show that the first-order decay rate constant of the PRB has a critical effect on the performance of the PRB-aquifer system, whereas the effects of the physical dispersion properties on PRB performance are less significant.

  2. Attenuation of pyrite oxidation with a fly ash pre-barrier: Reactive transport modelling of column experiments

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, R.; Cama, J.; Nieto, J.M.; Ayora, C.; Saaltink, M.W. [University of Huelva, Huelva (Spain). Dept. of Geology

    2009-09-15

    Conventional permeable reactive barriers (PRBs) for passive treatment of groundwater contaminated by acid mine drainage (AMD) use limestone as reactive material that neutralizes water acidity. However, the limestone-alkalinity potential ceases as inevitable precipitation of secondary metal-phases on grain surfaces occurs, limiting its efficiency. In the present study, fly ash derived from coal combustion is investigated as an alternative alkalinity generating material for the passive treatment of AMD using solution-saturated column experiments. Unlike conventional systems, the utilization of fly ash in a pre-barrier to intercept the non-polluted recharge water before this water reacts with pyrite-rich wastes is proposed. Chemical variation in the columns was interpreted with the reactive transport code RETRASO. In parallel, kinetics of fly ash dissolution at alkaline pH were studied using flow-through experiments and incorporated into the model. In a saturated column filled solely with pyritic sludge-quartz sand (1: 10), oxidation took place at acidic conditions (pH 3.7). According to SO{sub 4}{sup 2-} release and pH, pyrite dissolution occurred favourably in the solution-saturated porous medium until dissolved O{sub 2} was totally consumed. In a second saturated column, pyrite oxidation took place at alkaline conditions (pH 10.45) as acidity was neutralized by fly ash dissolution in a previous level. At this pH Fe release from pyrite dissolution was immediately depleted as Fe-oxy(hydroxide) phases that precipitated on the pyrite grains, forming Fe-coatings (microencapsulation). With time, pyrite microencapsulation inhibited oxidation in practically 97% of the pyritic sludge. Rapid pyrite-surface passivation decreased its reactivity, preventing AMD production in the relatively short term.

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

    Science.gov (United States)

    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.

  4. Permeable reactive barriers for the remediation of groundwater in a mining area: results for a pilot-scale project

    Science.gov (United States)

    Martinez-Sanchez, Maria Jose; Perez-Sirvent, Carmen; Garcia-Lorenzo, Maria Luz; Martinez-Lopez, Salvadora; Perez-Espinosa, Victor; Gonzalez-Ciudad, Eva; Belen Martinez-Martinez, Lucia; Hernandez, Carmen; Molina-Ruiz, Jose

    2017-04-01

    The Sierra Minera of Cartagena-La Union is located in the Region of Murcia, Southeast of Spain. This zone presents high levels of heavy metals due to natural, geogenic reasons. In addition, the prolonged mining activity, and subsequent abandonment of farms, has had consequences on the environment, including severe affectation of the groundwater in the area. To remediate this situation, the Permeable Reactive Barrier (PRB) technology was assayed, which required in addition to the hydro-geological study of the zone, a careful optimization study for the design and construction of PRBs. For such a purpose a pilot-scale project was developed, and this communication reports some of the most relevant findings obtained after a four-years monitorization period. The selected reactive material for the PRBs was limestone filler. The filler is a waste material produced in many factories in the zone. These residues have good adsorption properties, high alkalinity, low cost and high availability, which make them suitable for use in remediation. The PRB was constituted by a 50% limestone filler and 50% sand, a proportion optimized by means of independent batch experiments. A layer of gravel was placed at the top, and on it a layer of natural soil. The barrier was designed in the form of a continuous trench, because the level of the contaminated groundwater was not very deep. In this way, the barrier could be prepared with standard excavation equipment. Parallel to the barrier, 6 wells where arranged downstream for sample collection. The pH and conductivity of the samples was measured directly in situ, and the content of Zn, Cd, Cu, Fe, and Pb were analyzed in the laboratory. All the samples collected after the PRB was constructed had basic pH values between 7.5 and 8. The conductivity was between 5 and 11 mS / cm except for the well 4, which had a value of 3.70 mS / cm. The concentration values of trace elements were below the detection limit (atomic absorption measurement) in

  5. Degassing, gas retention and release in Fe(0) permeable reactive barriers.

    Science.gov (United States)

    Ruhl, Aki S; Jekel, Martin

    2014-04-01

    Corrosion of Fe(0) has been successfully utilized for the reductive treatment of multiple contaminants. Under anaerobic conditions, concurrent corrosion leads to the generation of hydrogen and its liberation as a gas. Gas bubbles are mobile or trapped within the irregular pore structure leading to a reduction of the water filled pore volume and thus decreased residence time and permeability (gas clogging). With regard to the contaminant transport to the reactive site, the estimation of surface properties of the reactive material indicated that individual gas bubbles only occupied minor contact areas of the reactive surface. Quantification of gas entrapment by both gravimetrical and tracer investigations revealed that development of preferential flow paths was not significant. A novel continuous gravimetrical method was implemented to record variations in gas entrapment and gas bubble releases from the reactive filling. Variation of grain size fractions revealed that the pore geometry had a significant impact on gas release. Large pores led to the release of comparably large gas amounts while smaller volumes were released from finer pores with a higher frequency. Relevant processes are explained with a simplified pictorial sequence that incorporates relevant mechanisms.

  6. Study of the interactions bacteria - phenanthrene - activated carbon for the preparation of a permeable reactive barrier; Etude des interactions bacteries - phenanthrene - charbon en vue de l'elaboration d'une barriere permeable reactive

    Energy Technology Data Exchange (ETDEWEB)

    Leglize, P.

    2004-12-01

    Permeable Reactive Barrier (PRB) is a new way for the remediation of contaminated groundwater, but up to now Polycyclic Aromatic Hydrocarbons (PAHs) were rarely considered. We investigated PAH - bacteria - materials interactions in order to validate the feasibility of PRB for PAH contamination. PHE Adsorption/desorption kinetics onto different materials, activated carbons (CA), pozzolana (Pz) and pozzolana coated with heavy fuel (PzF), were investigated. PHE biodegradation were performed on batch using PAH degrading bacteria and the PRB materials. CA was a good media for PRB process: Phenanthrene sorption capacity is 100 to 10000 fold higher than PzF and Pz. Phenanthrene mineralization with CA was higher than without material. Bacterial properties affected PHE biodegradation. Bio-film production improved PHE biodegradation by PAH degrading bacteria. Column studies showed that inoculation of the column improved its efficiency: adsorbed PHE degradation and increased retardation of PHE. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Baohua [ORNL; Watson, David B [ORNL; Phillips, Debra H. [Queen' s University, Belfast; Liang, Liyuan [ORNL

    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

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

    Science.gov (United States)

    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.

  9. Structural modification of the skin barrier by OH radicals: a reactive molecular dynamics study for plasma medicine

    Science.gov (United States)

    Van der Paal, J.; Verlackt, C. C.; Yusupov, M.; Neyts, E. C.; Bogaerts, A.

    2015-04-01

    While plasma treatment of skin diseases and wound healing has been proven highly effective, the underlying mechanisms, and more generally the effect of plasma radicals on skin tissue, are not yet completely understood. In this paper, we perform ReaxFF-based reactive molecular dynamics simulations to investigate the interaction of plasma generated OH radicals with a model system composed of free fatty acids, ceramides, and cholesterol molecules. This model system is an approximation of the upper layer of the skin (stratum corneum). All interaction mechanisms observed in our simulations are initiated by H-abstraction from one of the ceramides. This reaction, in turn, often starts a cascade of other reactions, which eventually lead to the formation of aldehydes, the dissociation of ceramides or the elimination of formaldehyde, and thus eventually to the degradation of the skin barrier function.

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

    Science.gov (United States)

    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.

  11. Assessing degradation rates of chlorinated ethylenes in column experiments with commercial iron materials used in permeable reactive barriers.

    Science.gov (United States)

    Ebert, Markus; Köber, Ralf; Parbs, Anika; Plagentz, Volkmar; Schäfer, Dirk; Dahmke, Andreas

    2006-03-15

    Multiple column experiments were performed using two commercial iron materials to evaluate the necessity and usefulness of preliminary investigations in permeable reactive barrier (PRB) design for chlorinated organics. Experiments were performed with contaminated groundwater and involved fresh iron granules or altered iron material excavated from PRBs. The determination of first-order rate coefficients by global nonlinear least-squares fittings indicated a variability in rate coefficients on 1 or 2 orders of magnitude. Geometric mean values of surface area normalized rate coefficients (in 10(-5) L m(-2) h(-1)) for fresh gray cast iron and iron sponge, respectively, are: tetrachloroethene (4.5, 2.6), trichloroethene (8.1, 3.3), cis-1,2-dichloroethene (3.1, 2.9), trans-1,2-dichloroethene (9.5, 5.3), 1,1-dichloroethene (4.0, 4.4), and vinyl chloride (1.6, 6.1). The increasing rate coefficients with decreasing grade of chlorination, which characterize degradation at iron sponge are linearly related to diffusion coefficients in water, suggesting diffusion limitation in the degradation process for this particular material, possibly due to a high inner surface. The variability in rate coefficients seems to be too high to use mean rate coefficients from published studies in the design procedure of PRBs, and variabilities cannot be related to groundwater characteristics, waterflow through the reactive cells, or secondary corrosion reactions.

  12. Inactivation of dinoflagellate Scrippsiella trochoidea in synthetic ballast water by reactive species generated from dielectric barrier discharges

    Energy Technology Data Exchange (ETDEWEB)

    Tang Qiong; Jiang Wenju; Yang Zhishan [Institute of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Zhang Yi; Lim Tuti Mariana, E-mail: TMLim@ntu.edu.s [Institute of Environmental Science and Engineering, Nanyang Technology University, Innovation Center, Block 2, Unit 237, 18 Nanyang Drive, 637723 Singapore (Singapore)

    2009-05-07

    The inactivation of dinoflagellate Scrippsiella trochoidea in synthetic ballast water by a dielectric barrier discharge (DBD) system was investigated. The OH{sup .} radical, ozone and hydrogen peroxide generated from the DBD system were measured. Before and after the treatment, the viability of dinoflagellate S. trochoidea was evaluated by analyzing chlorophyll a, protein and saccharide content and morphology of the cells, as well as the pH of the cell culture media. The results show OH{sup .} radical was the major reactive species when humid air was used. The inactivation of S. trochoidea was found to be dependent on the applied voltage and the gas flow rate, and was completed within 4 min at a gas flow rate of 7 L min{sup -1} and an applied voltage of 20 kV. The change of chlorophyll a, protein and saccharide concentrations of S. trochoidea and the morphology of the cells indicates that the reactive species generated from the DBD system can break up the cells via oxidation.

  13. 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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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...

  15. Oxidation of volatile organic compound vapours by potassium permanganate in a horizontal permeable reactive barrier under unsaturated conditions: experiments and modeling

    NARCIS (Netherlands)

    Ghareh Mahmoodlu, Mojtaba

    2014-01-01

    In this research we evaluated the potential of using solid potassium permanganate to create a horizontal permeable reactive barrier (HPRB) for oxidizing VOC vapours in the unsaturated zone. We have performed batch experiments, short column, and long column experiments, and have fully analyzed the da

  16. 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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2012-12-30

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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

  2. A binding-site barrier affects imaging efficiency of high affinity amyloid-reactive peptide radiotracers in vivo.

    Directory of Open Access Journals (Sweden)

    Jonathan S Wall

    Full Text Available Amyloid is a complex pathology associated with a growing number of diseases including Alzheimer's disease, type 2 diabetes, rheumatoid arthritis, and myeloma. The distribution and extent of amyloid deposition in body organs establishes the prognosis and can define treatment options; therefore, determining the amyloid load by using non-invasive molecular imaging is clinically important. We have identified a heparin-binding peptide designated p5 that, when radioiodinated, was capable of selectively imaging systemic visceral AA amyloidosis in a murine model of the disease. The p5 peptide was posited to bind effectively to amyloid deposits, relative to similarly charged polybasic heparin-reactive peptides, because it adopted a polar α helix secondary structure. We have now synthesized a variant, p5R, in which the 8 lysine amino acids of p5 have been replaced with arginine residues predisposing the peptide toward the α helical conformation in an effort to enhance the reactivity of the peptide with the amyloid substrate. The p5R peptide had higher affinity for amyloid and visualized AA amyloid in mice by using SPECT/CT imaging; however, the microdistribution, as evidenced in micro-autoradiographs, was dramatically altered relative to the p5 peptide due to its increased affinity and a resultant "binding site barrier" effect. These data suggest that radioiodinated peptide p5R may be optimal for the in vivo detection of discreet, perivascular amyloid, as found in the brain and pancreatic vasculature, by using molecular imaging techniques; however, peptide p5, due to its increased penetration, may yield more quantitative imaging of expansive tissue amyloid deposits.

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

    Science.gov (United States)

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

    2015-12-10

    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.

  4. Performance of iron filings and activated sludge as media for permeable reactive barriers to treat zinc contaminated groundwater

    Directory of Open Access Journals (Sweden)

    Chayapat Hassapak

    2015-02-01

    Full Text Available Zinc is one of the important contaminants in groundwater. Removal of zinc by iron filings, activated sludge and lateritic soil was studied with batch test. The lowest optimum pH for removal of zinc by iron filings, activated sludge and lateritic soil was 6. From isotherm studies iron filings and activated sludge were chosen as media for permeable reactive barrier (PRB. The PRB of 0.5-m thick was simulated in the unconfined aquifer with the distance of 21.5 m downgradient of the zinc contaminated site having constant concentration of 100 mg/l. The groundwater flow in the site was induced by the hydraulic gradient of 0.02. Simulation results indicated that the concentration of zinc of treated groundwater was less than 5 mg/l, which met Thai Groundwater Quality Standard for Drinking Purposes. The continuous PRBs using iron filings and activated sludge could treat zinc for 2,170 and 2,248 days, respectively

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

    Science.gov (United States)

    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.

  6. Enhanced remediation of Cr(VI)-contaminated soil by incorporating a calcined-hydrotalcite-based permeable reactive barrier with electrokinetics.

    Science.gov (United States)

    Zhang, Jia; Xu, Yunfeng; Li, Wentao; Zhou, Jizhi; Zhao, Jun; Qian, Guangren; Xu, Zhi Ping

    2012-11-15

    This paper describes the enhanced Cr(VI)-contaminated soil remediation via a combination of electrokinetics (EK) with a calcined-hydrotalcite-based permeable reactive barrier (PRB). First, this combination proved to be feasible, and remarkably facilitated Cr(VI) remediation in a column test. Then, lightly-to-severely (0.16-1.65 mg/g) Cr(VI)-contaminated soil was remediated in a simulated test with the calcined hydrotalcite as the PRB under an voltage of 10-30 V (i.e. an electric field intensity of 0.7-2.0 V/cm). The observations demonstrated that both PRB and EK are critical to efficient remediation and the high de-contamination efficiency is supposedly attributed to the synergistic effect, for which EK concentrates anionic chromate to the anode region and PRB media (calcined hydrotalcite) absorbs and immobilizes it. Thus we have shown that the combined PRB-EK system is highly adaptive and effective in remediation of a larger area contaminated with chromate and various anionic pollutants.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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

  13. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

    Energy Technology Data Exchange (ETDEWEB)

    Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Cao Limei; Guo Rui; Jia Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m{sup 2} g{sup -1}, the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

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

    Science.gov (United States)

    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.

  15. A review of permeable reactive barrier technologies%可渗透反应栅(墙)技术综述

    Institute of Scientific and Technical Information of China (English)

    廖梓龙; 魏永富; 郭中小; 龙胤慧

    2012-01-01

    为了促进可渗透反应栅(墙)PRB技术在我国地下水修复领域的应用和发展,对PRB技术进行简要综述,包括PRB类型、原理,污染羽流的类型和污染方式,设计和安装PRB之前勘察的内容,反应介质材料类型的介绍和选择等,PRB的设计与施工、后期的维护与监测,并对PRB技术的经济性进行评价与分析.提出我国在研究PRB技术时,不应局限于研究反应介质,还应考虑前期勘察、结构、运行监测等方面的因素,并选择合理的地下水修复投融资方式和途径.%In order to promote the application of permeable reactive barrier ( PRB) technologies to ground-water remediation in China, this paper presents a brief review of PRB technologies, including the types and concept of PRB, the types of contaminant plumes and ways of contamination, the investigated items before design and installation of PRB, the introduction to and selection of material types of the reaction medium, and design and construction of PRB and post-maintenance and monitoring. Moreover, the economics of PRB technologies is evaluated and analyzed. It is pointed out that research focuses should be placed not only on the reaction medium, but also on pre-investigation, structure, monitoring, and reasonable investment and financing policies for groundwater remediation.

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

    Science.gov (United States)

    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.

  17. Lipoteichoic acid from Staphylococcus aureus induces lung endothelial cell barrier dysfunction: role of reactive oxygen and nitrogen species.

    Directory of Open Access Journals (Sweden)

    Amy Barton Pai

    Full Text Available Tunneled central venous catheters (TCVCs are used for dialysis access in 82% of new hemodialysis patients and are rapidly colonized with Gram-positive organism (e.g. Staphylococcus aureus biofilm, a source of recurrent infections and chronic inflammation. Lipoteichoic acid (LTA, a cell wall ribitol polymer from Gram-positive organisms, mediates inflammation through the Toll-like receptor 2 (TLR2. The effect of LTA on lung endothelial permeability is not known. We tested the hypothesis that LTA from Staphylococcus aureus induces alterations in the permeability of pulmonary microvessel endothelial monolayers (PMEM that result from activation of TLR2 and are mediated by reactive oxygen/nitrogen species (RONS. The permeability of PMEM was assessed by the clearance rate of Evans blue-labeled albumin, the activation of the TLR2 pathway was assessed by Western blot, and the generation of RONS was measured by the fluorescence of oxidized dihydroethidium and a dichlorofluorescein derivative. Treatment with LTA or the TLR2 agonist Pam((3CSK((4 induced significant increases in albumin permeability, IκBα phosphorylation, IRAK1 degradation, RONS generation, and endothelial nitric oxide synthase (eNOS activation (as measured by the p-eNOS(ser1177:p-eNOS(thr495 ratio. The effects on permeability and RONS were effectively prevented by co-administration of the superoxide scavenger Tiron, the peroxynitrite scavenger Urate, or the eNOS inhibitor L-NAME and these effects as well as eNOS activation were reduced or prevented by pretreatment with an IRAK1/4 inhibitor. The results indicate that the activation of TLR2 and the generation of ROS/RNS mediates LTA-induced barrier dysfunction in PMEM.

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

    Science.gov (United States)

    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/N2, 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Golshani, Negin, E-mail: negingolshani@gmail.com; Mohammadi, V.; Schellevis, H.; Beenakker, C. I. M.; Ishihara, R. [ECTM, DIMES, Faculty of Electrical Engineering (EWI), Delft University of Technology (TU Delft), Feldmannweg 17, P.O. Box 5053, 2628 CT Delft (Netherlands)

    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.

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

    Directory of Open Access Journals (Sweden)

    Negin Golshani

    2014-10-01

    Full Text Available 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/N2, 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.

  1. Experimental Studies of Engineered Barrier Systems Conducted at Los Alamos National Laboratory (FY16)

    Energy Technology Data Exchange (ETDEWEB)

    Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maner, James [Univ. of Oklahoma, Norman, OK (United States). School of Geology and Geophysics; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-08-04

    Over the past five years the Used Fuel Campaign has investigated Engineered Barrier Systems (EBS) at higher heat loads (up to 300°C) and pressure (150 bar). This past year experimental work was hindered due to a revamping of the hydrothermal lab. Regardless, two experiments were run this past year, EBS-18 and EBS-19. EBS-18 was run using Low Carbon Steel (LCS) and opalinus clay in addition to the bentonite and opalinus brine. Many of the past results were confirmed in EBS-18, such as the restriction of illite formation due to the bulk chemistry, pyrite degradation, and zeolite formation dependent on the bentonite and opalinus clay. The LCS show vast amounts of pit corrosion (over 100μm of corrosion in six weeks), leading a corrosion rate of 1083 μm/year. In addition, a mineral goethite, an iron-bearing hydroxide, formed in the pits of the LCS. Preliminary results from EBS-19 water chemistry are included but SEM imaging, micro probe and XRD are still needed for further results. Copper corrosion was investigated further and over 850 measurements were taken. It was concluded that pitting and pyrite degradation drastically increase the corrosion rate from 0.12 to 0.39 μm/day. However, the growth of a layer of the mineral chalcocite is thought to subdue the corrosion rate to 0.024 μm/day as observed in the EBS-13, a sixth month experiment. This document presents the findings of this past year.

  2. Experimental Studies of Engineered Barrier Systems Conducted at Los Alamos National Laboratory (FY16)

    Energy Technology Data Exchange (ETDEWEB)

    Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maner, James [Univ. of Oklahoma, Norman, OK (United States). School of Geology and Geophysics; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences; Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-08-04

    Over the past five years the Used Fuel Campaign has investigated Engineered Barrier Systems (EBS) at higher heat loads (up to 300°C) and pressure (150 bar). This past year experimental work was hindered due to a revamping of the hydrothermal lab. Regardless, two experiments were run this past year, EBS-18 and EBS-19. EBS-18 was run using Low Carbon Steel (LCS) and opalinus clay in addition to the bentonite and opalinus brine. Many of the past results were confirmed in EBS-18 such as the restriction of illite formation due to the bulk chemistry, pyrite degradation, and zeolite formation dependent on the bentonite and opalinus clay. The LCS show vast amounts of pit corrosion over 100μm of corrosion in six weeks, leading a corrosion rate of 1083 μm/year. In addition, a mineral goethite, an iron bearing hydroxide, formed in the pits of the LCS. Preliminary results from EBS-19 water chemistry are included but SEM imaging, micro probe and XRD are still needed for further results. Copper corrosion was investigated further and over 850 measurements were taken. It was concluded that pitting and pyrite degradation drastically increase the corrosion rate from 0.12 to 0.39 μm/day. However, the growth of a layer of the mineral chalcocite is thought to subdue the corrosion rate to 0.024 μm/day as observed in the EBS-13 a sixth month experiment. This document presents the findings of this past year.

  3. Los

    OpenAIRE

    Francismar Alex Lopes de Carvalho

    2005-01-01

    El objetivo de este texto es analizar la compleja trama de interrelaciones políticas, de guerra y de paz, entre los grupos étnicos nativos y los adventicios implicados en el movimiento de las Monzones. Para ello, utilizo, como base de mis reflexiones, un texto sobre el asalto habido en 1730 en el cual el grupo Payaguá atacó la monzón del Ouvidor Lanhas Peixoto, que conducía el quinto Real de las minas de Cuiabá a São Paulo. A través del enfoque de las interacciones y las alianzas políticas en...

  4. An Innovative Project Breaks Down Barriers to Oral Health Care for Vulnerable Young Children in Los Angeles County.

    Science.gov (United States)

    Crall, James J; Illum, Jackie; Martinez, Ana; Pourat, Nadereh

    2016-06-01

    Despite the high rate of untreated tooth decay, many young children in California under six years of age have never been to a dentist. Numerous and complex barriers to access to oral health care for young children exist, and a multifaceted approach is required to improve receipt of preventive and treatment services that could improve the oral health of this population. This policy brief describes the UCLA-First 5 LA 21st Century Dental Homes Project, which was designed to improve oral health care for young children in 12 Federally Qualified Health Center (FQHC) clinic sites with co-located dental and primary care services and its accessibility in their service areas throughout Los Angeles County. The project funded infrastructure and staffing, provided technical assistance to improve operations, trained clinical personnel to provide oral health care to young children, implemented a quality improvement learning collaborative, trained parents and child care providers in oral hygiene and healthy habits, and disseminated information to promote effective policies. Early data on the project indicated twofold increases in delivery of both diagnostics and treatment visits for young children, and a threefold increase in preventive services for young children during the program.

  5. Contamination movement around a permeable reactive barrier at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2009

    Science.gov (United States)

    Vroblesky, Don A.; Petkewich, Matthew D.; Conlon, Kevin J.

    2010-01-01

    The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound groundwater contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina, beginning in 2000. In early 2004, groundwater contaminants began moving around the southern end of a permeable reactive barrier (PRB) installed by a consultant in December 2002. The PRB is a 130-foot-long and 3-foot-wide barrier consisting of varying amounts of zero-valent iron with or without sand mixture. Contamination moving around the PRB probably has been transported at least 75 feet downgradient from the PRB at a rate of about 15 to 29 feet per year.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  7. Fatty acid ethyl esters induce intestinal epithelial barrier dysfunction via a reactive oxygen species-dependent mechanism in a three-dimensional cell culture model.

    Directory of Open Access Journals (Sweden)

    Elhaseen Elamin

    Full Text Available BACKGROUND & AIMS: Evidence is accumulating that ethanol and its oxidative metabolite, acetaldehyde, can disrupt intestinal epithelial integrity, an important factor contributing to ethanol-induced liver injury. However, ethanol can also be metabolized non-oxidatively generating phosphatidylethanol and fatty acid ethyl esters (FAEEs. This study aims to investigate the effects of FAEEs on barrier function, and to explore the role of oxidative stress as possible mechanism. METHODS: Epithelial permeability was assessed by paracellular flux of fluorescein isothiocyanate-conjugated dextran using live cell imaging. Cell integrity was evaluated by lactate dehydrogenase release. Localization and protein levels of ZO-1 and occludin were analyzed by immunofluorescence and cell-based ELISA, respectively. Intracellular oxidative stress and cellular ATP levels were measured by dichlorofluorescein and luciferase driven bioluminescence, respectively. RESULTS: In vitro, ethyl oleate and ethyl palmitate dose dependently increased permeability associated with disruption and decreased ZO-1 and occludin protein levels, respectively, and increased intracellular oxidative stress without compromising cell viability. These effects could partially be attenuated by pretreatment with the antioxidant, resveratrol, pointing to the role of oxidative stress in the FAEEs-induced intestinal barrier dysfunction. CONCLUSIONS: These findings show that FAEEs can induce intestinal barrier dysfunction by disrupting the tight junctions, most likely via reactive oxygen species-dependent mechanism.

  8. Development of Reactive Barrier Polymers against Corrosion for the Oil and Gas Industry: From Formulation to Qualification through the Development of Predictive Multiphysics Modeling

    Directory of Open Access Journals (Sweden)

    Lefebvre X.

    2015-02-01

    Full Text Available Corrosion is a key issue for operators in the oil and gas industry since production fluids contain some water and both CO2 and H2S acid gases. In this context, this paper illustrates the development of a reactive barrier polymer against corrosion by H2S of offshore flexible pipes. The role of this reactive material, called anti-H2S material, is to avoid H2S reaching the structural steel layers of the flexible pipe during the whole service life of the structure, usually 20 years, and hence to place the steel layers in a sweet service environment. Placed between the existing pressure sheath and the steel layers, the anti-H2S material has the ability to neutralize H2S during its diffusion within the material. The neutralization is ensured by an irreversible chemical reaction on reactive components that are dispersed in the material. The raw material selection is based on both accurate requirements for their use in a flexible pipe and expected performances in a sour service environment over a long period of time. Some laboratory qualifications and experimental techniques are used to qualify the behavior of the material and build the material database. A dedicated multiphysics model is developed based on the coupling of permeation mechanisms and gas-solid reactions. Qualification of both the material and the model is performed thanks to middle-scale and full-scale tests conducted in representative sour service conditions.

  9. Assessing Current and Future Performance of the Alamitos Gap Seawater Intrusion Barrier with a New Flow and Transport Model, Los Angeles and Orange Counties, CA

    Science.gov (United States)

    Sigda, J. M.; Deeds, N.; Jordan, D. L.; Sengebush, R.

    2010-12-01

    Seawater intrusion has threatened aquifers that supply Los Angeles residents since the 1920s, but now millions depend on effective resource management, especially for the four injection barriers. Even with ~6,000 acre-ft/yr injected through the Alamitos Gap barrier, which straddles the San Gabriel River, chloride concentrations have continued to increase in several aquifers inland of the barrier. On behalf of the Orange County Water District, the Water Replenishment District of Southern California, and the Los Angeles Department of Public Works, INTERA created a new flow and solute transport model for permitting, management, and performance assessment of the injection barrier. We devised a new conceptual model, water balance, geologic model, and numerical flow and solute transport models in five months to meet a regulatory deadline. Quickly developing a hydrogeologic framework was challenging because erosion and deposition on the uplifted transgression-regression system of aquitards and aquifers created pathways within the Gap for seawater to travel inland. The pathways, called mergence zones, connect the seawater-intruded Recent Aquifer with several of the deeper aquifers used for water supply. Capturing their locations and geometries was critical to effectively simulating past and future seawater intrusion. We extended the new hydrogeologic framework beyond and below previous frameworks by combining traditional geologic interpretation, GIS analysis, and an innovative geologic modeling software tool. Using the new conceptual and geologic models as a foundation, INTERA constructed a three-dimensional transient groundwater flow model, the Alamitos Barrier Flow Model (ABFM), using the MODFLOW 2000 code. The ABFM was calibrated in three ways: (1) a steady-state calibration to average heads for the 1999-2009 period, (2) transient calibration to the heads observed from 1999 through 2009, and (3) final flow calibration adjustments based on the chloride transport

  10. Chemical dynamics between wells across a time-dependent barrier: Self-similarity in the Lagrangian descriptor and reactive basins

    Science.gov (United States)

    Junginger, Andrej; Duvenbeck, Lennart; Feldmaier, Matthias; Main, Jörg; Wunner, Günter; Hernandez, Rigoberto

    2017-08-01

    In chemical or physical reaction dynamics, it is essential to distinguish precisely between reactants and products for all times. This task is especially demanding in time-dependent or driven systems because therein the dividing surface (DS) between these states often exhibits a nontrivial time-dependence. The so-called transition state (TS) trajectory has been seen to define a DS which is free of recrossings in a large number of one-dimensional reactions across time-dependent barriers and thus, allows one to determine exact reaction rates. A fundamental challenge to applying this method is the construction of the TS trajectory itself. The minimization of Lagrangian descriptors (LDs) provides a general and powerful scheme to obtain that trajectory even when perturbation theory fails. Both approaches encounter possible breakdowns when the overall potential is bounded, admitting the possibility of returns to the barrier long after the trajectories have reached the product or reactant wells. Such global dynamics cannot be captured by perturbation theory. Meanwhile, in the LD-DS approach, it leads to the emergence of additional local minima which make it difficult to extract the optimal branch associated with the desired TS trajectory. In this work, we illustrate this behavior for a time-dependent double-well potential revealing a self-similar structure of the LD, and we demonstrate how the reflections and side-minima can be addressed by an appropriate modification of the LD associated with the direct rate across the barrier.

  11. Divergent Perceptions of Barriers to Diabetic Retinopathy Screening Among Patients and Care Providers, Los Angeles, California, 2014–2015

    Science.gov (United States)

    Lu, Yang; Serpas, Lilian; Genter, Pauline; Anderson, Betty; Campa, David

    2016-01-01

    Introduction Despite availability of screening for diabetic retinopathy, testing is underused by many low-income and racial/ethnic minority patients with diabetes. We examined perceived barriers to diabetic retinopathy screening among low-income patients and their health care providers and provider staffers. Methods We collected survey data from 101 patients with diabetes and 44 providers and staffers at a safety-net clinic where annual diabetic retinopathy screening rates were low. Barriers specified in the survey were derived from the literature. Results Patients surveyed (mean [standard deviation] age, 54.0 [7.7] y; 41% were male) were primarily Hispanics (70%) and African Americans (27%) of low socioeconomic status. Overall, 55% of patients received diabetic retinopathy screening in the previous year. Patients who could not explain why this screening is needed reported more barriers than patients who could (2.5 vs 1.4 barriers, P = .02). Fewer patients reported that they experienced barriers such as transportation (15%), language issues (15%), cultural beliefs or myths (4%), denial (8%), and fear (5%), which providers and staffers considered very or extremely important (all P perceptions of barriers to diabetic retinopathy screening. Patients with poor understanding of the need for screening were more likely to report such barriers. These results suggest a need for active community engagement to find key elements for education programs and other interventions to increase rates of diabetic retinopathy screening, particularly among low-income, minority populations. PMID:27710765

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

    Science.gov (United States)

    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.

  13. Gas-phase Reactive Oxygen and Nitrogen Species in Air Surface Dielectric Barrier Discharges by FTIR and UV spectroscopy

    Science.gov (United States)

    Chang, Hung-Wen; Sakiyama, Yukinori; Hsu, Cheng-Che; Graves, David B.

    2012-10-01

    Atmospheric pressure plasmas are considered promising for biomedical treatment purpose due to the production of reactive oxygen species and reactive nitrogen species during the discharge. In this study, a surface micro-discharge system which operates at 10 kHz, 0.01 -- 1 W/cm^2 in ambient air is used. FTIR and UV-absorbance are used to investigate the time-average gas phase composition and time-resolved ozone concentration, respectively. The results showed that the gas composition is greatly influenced by the power consumption in plasmas. At 0.3 W/cm^2, the gas phase is dominant by NOx species and nearly no ozone is observed while at 0.05 W/cm^2 the amount of NOx is less and the ozone is dominant. Also, time-resolved ozone measurement by means of UV (254 nm) absorbance shows that ozone concentration reaches higher than 1000 ppm in the first tens of seconds and quenched within 1 minutes at high power condition. However, at low power condition no obvious quench of ozone is observed and the ozone concentration attains a steady state in response to the equilibrium of ozone generation and diffusion loss

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. Reactivation of Endogenous Genes and Epigenetic Remodeling Are Barriers for Generating Transgene-Free Induced Pluripotent Stem Cells in Pig.

    Directory of Open Access Journals (Sweden)

    Kwang-Hwan Choi

    Full Text Available Cellular reprogramming of committed cells into a pluripotent state can be induced by ectopic expression of genes such as OCT4, SOX2, KLF4, and MYC. Reprogrammed cells can be maintained by activating endogenous pluripotent networks without transgene expression. Although various research groups have attempted to generate pig induced pluripotent stem cells (iPSCs, authentic iPSCs have not be obtained, instead showing dependence on transgene expression. In this study, iPSCs were derived from porcine fetal fibroblasts via drug-inducible vectors carrying human transcription factors (OCT4, SOX2, KLF4, and MYC. Therefore, this study investigated characteristics of iPSCs and reprogramming mechanisms in pig. The iPSCs were stably maintained over an extended period with potential in vitro differentiation into three germ layers. In addition, the pluripotent state of iPSCs was regulated by modulating culture conditions. They showed naive- or primed-like pluripotent states in LIF or bFGF supplemented culture conditions, respectively. However, iPSCs could not be maintained without ectopic expression of transgenes. The cultured iPSCs expressed endogenous transcription factors such as OCT4 and SOX2, but not NANOG (a known gateway to complete reprogramming. Endogenous genes related to mesenchymal-to-epithelial transition (DPPA2, CDH1, EPCAM, and OCLN were not sufficiently reactivated, as measured by qPCR. DNA methylation analysis for promoters of OCT4, NANOG, and XIST showed that epigenetic reprogramming did not occur in female iPSCs. Based on our results, expression of exogenous genes could not sufficiently activate the essential endogenous genes and remodel the epigenetic milieu to achieve faithful pluripotency in pig. Accordingly, investigating iPSCs could help us improve and develop reprogramming methods by understanding reprogramming mechanisms in pig.

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

    Science.gov (United States)

    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.

  19. Performance of a field-scale permeable reactive barrier based on organic substrate and zero-valent iron for in situ remediation of acid mine drainage.

    Science.gov (United States)

    Gibert, Oriol; Cortina, José Luis; de Pablo, Joan; Ayora, Carlos

    2013-11-01

    A permeable reactive barrier (PRB) was installed in Aznalcóllar (Spain) in order to rehabilitate the Agrio aquifer groundwater severely contaminated with acid mine drainage after a serious mining accident. The filling material of the PRB consisted of a mixture of calcite, vegetal compost and, locally, Fe(0) and sewage sludge. Among the successes of the PRB are the continuous neutralisation of pH and the removal of metals from groundwater within the PRB (removals of >95%). Among the shortcomings are the improper PRB design due to the complexity of the internal structure of the Agrio alluvial deposits (which resulted in an inefficient capture of the contaminated plume), the poor degradability of the compost used and the short residence time within the PRB (which hindered a complete sulphate reduction), the clogging of a section of the PRB and the heterogeneities of the filling material (which resulted in preferential flows within the PRB). Undoubtedly, it is only through accumulated experience at field-scale systems that the potentials and limits of the PRB technology can be determined.

  20. Surface reactive species on MnOx(0.4)-CeO2 catalysts towards soot oxidation assisted with pulse dielectric barrier discharge

    Institute of Scientific and Technical Information of China (English)

    付名利; 林俊敏; 朱文波; 吴军良; 陈礼敏; 黄碧纯; 叶代启

    2014-01-01

    MnOx(0.4)-CeO2 was investigated for soot oxidation assisted with a pulse dielectric barrier discharge (DBD). The catalysts were evaluated and characterized with TPO (temperature programmed oxidation), X-ray diffraction (XRD), Raman and X-ray photo-electron spectroscopy (XPS). The ignition temperature Ti for soot oxidation decreased from 240.8 to 216.4 ºC with the increase of the pulse DBD frequencies from 50 to 400 Hz, lower than that of the case without pulse DBD present (253.4 ºC). The results of XRD, Raman and XPS agreed well with the TPO activities of MnOx(0.4)-CeO2 towards soot oxidation. More solid solution of ceria and manganese, and surface reactive species including O2-, O-and Mn4+were responsible for the enhancement of soot oxidation due to pulse DBD injection in the present study. For solid solution favors to the activation and transformation of those species, which are be-lieved to be involved in the soot oxidation in a hybrid catalysis-plasma.

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

    Science.gov (United States)

    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.

  2. 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

    Directory of Open Access Journals (Sweden)

    Mohamed Nawfal Ghazzal

    2015-10-01

    Full Text Available 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.

  3. 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.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, David; Roos, Gillian [Golder Associates Ltd., 2390 Argentia Road, Mississauga, ON L5N 5Z7 (Canada); Ferguson Jones, Andrea [MMM Group Ltd., 100 Commerce Valley Drive West, Thornhill, ON L3T 0A1 (Canada); Case, Glenn [AECL Port Hope Area Initiative Management Office, 115 Toronto Road, Port Hope, ON L1A 3S4 (Canada); Yule, Adam [Public Works and Government Services Canada, 4900 Yonge Street, 11th Floor, Toronto, ON, M2N 6A6 (Canada)

    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

  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.

    Science.gov (United States)

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

    Science.gov (United States)

    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.

  7. Management of Animal Carcass Disposal Sites Using a Biochar Permeable Reactive Barrier and Fast Growth Tree (Populus euramericana: A Field Study in Korea

    Directory of Open Access Journals (Sweden)

    Jung-Hwan Yoon

    2017-03-01

    Full Text Available Among many disposal options of animal carcasses due to animal diseases including foot-and-mouth disease (FMD and avian influenza (AI, on-farm burial has been the most frequently used one in Korea. Animal carcasses generate contaminants such as ammonium-N and chloride. This study aimed at testing biochar (BC as a permeable reactive barrier (PRB material in combination with fast growing tree species (Populus euramericana to mitigate groundwater pollution from animal burial sites. For this, a PRB filled with BC was installed and 400 poplar tree (P. euramericana seedlings were planted. Tested BC was obtained from rice husk and its efficiency to mitigate contaminant migration from a burial site of pig carcasses was tested using ammonium-N, chloride, electrical conductivity (EC, and pH as monitoring parameters. Monitoring wells downstream from the burial site were used. Leachates from a monitoring well, three wells inside the burial site close to PRB and three wells outside the burial site close to PRB were sampled and analyzed for ammonium-N, Cl−, EC, and pH for four years from PRB installation. The pH, EC, and ammonium-N of leachate fluctuated during the test period depending on precipitation. pH, EC, and ammonium-N of the leachate samples collected from outside of the burial site close to PRB decreased compared to those from inside of the burial site close to PRB. The concentrations of ammonium-N in the leachate from the monitoring well kept under the threshold value of 10 mg·L−1 for two years from PRB construction. In addition, the growth of poplar plants appeared to be increased via uptaking available N and P released from the burial sites. Achieved results suggest that BC PRBs can be used to in situ mitigate contaminant release from buried animal carcasses.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. 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

    Energy Technology Data Exchange (ETDEWEB)

    Naftz, D.L.; Freethey, G.W. [Geological Survey, Salt Lake City, UT (United States); Davis, J.A. [Geological Survey, Menlo Park, CA (United States)] [and others

    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.

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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

  14. 去除地下水中硝酸盐的渗透性反应墙研究%Removal of Nitrate from Groundwater Using Permeable Reactive Barrier

    Institute of Scientific and Technical Information of China (English)

    李秀利; 杨君君; 卢晓霞; 张姝; 侯珍

    2013-01-01

    通过土柱试验模拟地下水环境,研究以发酵树皮和沙子混合物为反应介质的渗透性反应墙(生物墙)对地下水中硝酸盐的去除情况,探讨其作用机制与影响因素,为硝酸盐污染地下水的修复提供经济有效的方法.结果表明,从模拟生物墙运行的第3d起,墙内为强还原环境(Eh在-100 mV之下),有利于硝酸盐的还原降解.在15 d的运行时间内,模拟生物墙对水中硝态氮(NO3--N)的去除率为80% ~ 90%左右(NO3-N由进水的20 mg·L-1可降至出水的1.6 mg·L-1);出水中亚硝态氮(NO2-N)的浓度较低,一直小于2.5mg·L-1;出水中铵态氮(NH4+-N)的浓度在前2d较低,从第3d起升至12 mg·L-1.模拟生物墙对NO3--N的去除机制主要为吸附和微生物降解.提高模拟生物墙内水流速度后,NO3-N的去除率有所下降,出水中NH4+-N的浓度明显降低.在模拟生物墙下游串联一个模拟沸石墙,可去除水中98%的NH4-N.%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·L-1 in the inlet water to 1.6 mg·L-1 in the outlet water); the concentration of nitrite nitrogen ( NO2- -N) in the outlet water was below 2. 5 mg· L-1 ; the concentration of ammonium nitrogen ( NH4+ -N) was low in the first two days but increased to about 12 mg·L-1 since day three. The major mechanisms involved in the removal of nitrate

  15. Modelación de los efectos de la compensación de potencia reactiva en sistemas de suministro eléctrico Modelation of effects on reactive power compensation in secondary power systems

    Directory of Open Access Journals (Sweden)

    Davel Borges Vasconcellos

    2012-08-01

    Full Text Available Se presentan los inconvenientes de la potencia reactiva y a partir de allí se realiza la modelación matemática de los efectos económicos de ésta, aplicable a sistemas de suministro eléctrico. Los efectos tomados en cuenta son: los costos de inversión de los bancos de capacitores, los gastos de amortización de los bancos, los gastos de pérdidas de energía activa de los bancos, los beneficios por la mejora del factor de potencia, incluida la reducción de pérdidas de energía activa en el sistema, así como los beneficios por la liberación de la capacidad de carga, para el caso de empresas donde este aspecto pueda representar un atractivo económico. Para el análisis de los estados de carga antes y después de la compensación se utilizan algoritmos de flujos de potencia trifásicos, con el empleo de modelos de gráficos de carga ajustados, como aspecto novedoso. Estos efectos, de acuerdo con el sistema de tarifas eléctricas de Cuba, son integrados en una función de análisis económico, en este caso el Valor Actual Neto (VAN, la cual sirve de base para el planteamiento del problema de optimización, que puede derivar en la correcta selección de los dispositivos compensadores.The inconveniences of the reactive power are presented and from this are carried out the mathematical models of its economic effects applicable to secondary power systems. The effects taken into account are: the costs of the capacitors banks, the expenses of paying-off to the banks, the expenses of power losses to the banks, the benefits for the improvement of the power factor, included the reduction of power loss in the system, as well as the benefits for the liberation of the load capacity, to the case of companies where the latest aspect can represent an economic attractiveness. For the analysis after and before compensation, are consider load flow algorithm witch load model adjust. According to electrical tariff structures in Cuba, these effects are

  16. Las barreras de acceso a los servicios de salud en la población indígena de Rabinal en Guatemala Barriers to accessing health care services for the indigenous population in Rabinal, Guatemala

    Directory of Open Access Journals (Sweden)

    Maeve Hautecoeur

    2007-04-01

    Full Text Available OBJETIVO: Identificar y documentar las barreras de acceso a los servicios de salud en la población indígena de Rabinal en Guatemala. MATERIAL Y MÉTODOS: Se privilegió el análisis cualitativo y la recopilación de datos se realizó en Rabinal durante dos meses (Guatemala. Se realizaron quince entrevistas semi dirigidas a indígenas achís y cinco entrevistas a profesionales de la salud. Un grupo de discusión fue formado para validar la información recogida durante las entrevistas individuales; la retranscripción de éstas y la compilación de los datos permitieron hacer el análisis de contenido. RESULTADOS: Las barreras de acceso están interrelacionadas y las barreras geográficas están relacionadas con la distancia y con la escasez de transporte; las barreras económicas son los precios de las consultas y de los medicamentos, además, entre las barreras culturales, la lengua española es un obstáculo. Los indígenas tienen otra concepción de la medicina y de los tratamientos y se quejan en ocasiones de trato abusivo por parte de los profesionales sanitarios. A su vez, los profesionales de la salud reconocen que el trauma de la guerra está presente y critican las malas condiciones de vida y la falta de recursos. CONCLUSIONES: Los servicios de salud no son adecuados ni suficientes para responder a las necesidades de la población local.OBJECTIVE: To identify and document access barriers to health care services for the indigenous population in Rabinal, Guatemala. MATERIAL AND METHODS: A qualitative analysis was used. Over a period of two months, 20 semi-directional interviews were conducted in Rabinal, Guatemala: 15 with Achis indigenous people and five with health professionals. A focus group was done to verify the information collected during the individual interviews. The qualitative analysis was based on the transcription of interviews and the compilation of the data. RESULTS: Barriers to access are inter-relational. Geographic

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

    Directory of Open Access Journals (Sweden)

    Mehrnaz Nouri

    Full Text Available 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.

  18. Penetration Deep into Tissues of Reactive Oxygen Species Generated in Floating-Electrode Dielectric Barrier Discharge (FE-DBD): in Vitro Agarose Gel Model Mimicking an Open Wound

    CERN Document Server

    Dobrynin, Danil; Friedman, Gary; Fridman, Alexander

    2013-01-01

    In this manuscript we present an in vitro model based on agarose gel that can be used to simulate a dirty, oily, bloody, and morphologically complex surface of, for example, an open wound. We show this models effectiveness in simulating depth of penetration of reactive species generated in plasma deep into tissue of a rat and confirm the penetration depths with agarose gel model. We envision that in the future such a model could be used to study plasma discharges (and other modalities) and minimize the use of live animals: plasma can be optimized on the agarose gel wound model and then finally verified using an actual wound.

  19. Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater.

    Science.gov (United States)

    Han, Weijiang; Fu, Fenglian; Cheng, Zihang; Tang, Bing; Wu, Shijiao

    2016-01-25

    The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+) was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+) were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd(2+), Ni(2+), Cu(2+), and Zn(2+)) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed.

  20. Evaluación de la dimensión fractal reactiva de los glicinatos de magnesio, manganeso y zinc Evaluation of the reactive fractal dimension of magnesium, manganese and zinc glycinates

    Directory of Open Access Journals (Sweden)

    Julie Fernanda Benavides Arevalo

    2012-03-01

    Full Text Available Introducción: complejos de glicina con los cationes magnesio, manganeso y zinc podrían ser parte de una formulación de un suplemento nutricional que proporcione una adecuada absorción de los metales en el organismo sin generar molestias gastrointestinales. Objetivo: realizar una aproximación a la solubilidad de los complejos de glicina con los cationes magnesio, manganeso y zinc. Métodos: se efectuaron estudios de disolución y análisis de imagen. Se realizó la síntesis y la verificación de formación de los complejos por espectroscopia infrarroja, calorimetría de barrido diferencial, análisis termogravimétrico y difracción de rayos X de polvos. Resultados: se obtuvieron por análisis de imagen los descriptores: circularidad, diámetro de Feret y dimensión fractal; esta última se relacionó con el proceso de disolución en agua, para obtener dos propiedades relacionadas: la dimensión fractal superficial y la dimensión fractal reactiva. Conclusiones: los resultados muestran que el proceso de disolución de los glicinatos, se realiza a través de los poros o grietas de la superficie de las partículas de estos y que son aptos para su empleo en formulaciones nutricionales como fuentes de magnesio, manganeso y zinc.Introduction: Complexes of glycine and cations magnesium, manganese and zinc, could be included in the formulation of a nutritional supplement that provides adequate absorption of these metals into the body without gastrointestinal disturbances. Objective: to study the solubility of complexes of glycine and cations manganese, zinc and magnesium. Methods: dissolution and image analysis studies were performed. The synthesis and verification of the formation of complexes were carried out by infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and X-ray diffraction of dust. Results: the image analysis showed some descriptors such as circularity, the Ferret diameter and the fractal dimension

  1. 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

    Energy Technology Data Exchange (ETDEWEB)

    Siegrist, R.L. [Oak Ridge National Lab., TN (United States)]|[Colorado School of Mines, Golden, CO (United States). Environmental Science and Engineering Div.; Lowe, K.S. [Oak Ridge National Lab., Grand Junction, CO (United States). Life Sciences Div.; Murdoch, L.D. [FRx, Inc., Cincinnati, OH (United States)]|[Clemson Univ., SC (United States); Slack, W.W. [FRx, Inc., Cincinnati, OH (United States); Houk, T.C. [Lockheed Martin Energy Systems, Piketon, OH (United States)

    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.

  2. Study of corrosion behaviour in saturated bentonite barrier Corroben; Estudio de los productos de corrosion de la capsula y su interaccion con la berrar arcillosa de bentonita Corroben

    Energy Technology Data Exchange (ETDEWEB)

    Azkarate, I.; Insausti, M.; Medina, V.

    2004-07-01

    The corrosion behavior in saturated bentonite of various candidate metallic materials, to be used in the fabrication of containers of high level radioactive waste granite repositories, has been studied in this project. Due to the multi-barrier concept in which the canisters are surrounded by a clay barrier of compacted bentonite blocks, special attention has been paid to the characterization of corrosion products and the interaction between these and the repository sealing bentonite. The following metallic materials have been studied: S355 carbon steel, AISI 316L stainless steel, Cu-ETP electrolytic copper and Cu30Ni alloy. Samples of the alloys have been embedded in saturated bentonite to a water content of 25%, and compacted. The obtained pastilles have been introduced in autoclaves and tested at different temperatures and times ranging from one to 18 months. Once tests have concluded, several parameters have been evaluated: corrosion morphology, general corrosion rates calculated by gravimetric methods, nature and composition of the corrosion products and penetration of the corrosion products into the bentonite. Experimental data obtained are used to developed models of the corrosion behavior of canisters under disposal conditions. Results show that S355 carbon steel has suffered the highest general corrosion attack, with average corrosion rates of 10 per year and maximum penetration of 100 measured in specimens tested at 75C during 18 months. The most common analyzed corrosion product has been siderite, FeCO3. Formation of siderite, in the test conditions, effectively passivated the steel because of its stable and adherent feature. In test carried out at 25 and 5 C, sulfur rich corrosion products are observed, thus indicating a microbiologically corrosion phenomena due to the metabolic activity of bacteria present in the bentonite. No appreciable general corrosion rates, nor sensitivity to localized corrosion, has been observed in the AISI 316L stainless steel

  3. Transformation and existing form of ammonia-N in a multi-media permeable reactive barrier%多介质渗透反应格栅中氨氮的转化与存在形态

    Institute of Scientific and Technical Information of China (English)

    杨应钊; 刘菲; 孔祥科; 李圣品; 马剑飞

    2013-01-01

    在利用渗透反应格栅技术修复地下水氨氮污染过程中,掌握氨氮在不同介质环境中的转化规律及存在形态对多介质渗透反应格栅中各介质作用及氮转化过程的控制十分重要.针对进水氨氮浓度约10 mg/L的模拟地下水,以天然河沙、释氧材料、斜发沸石及海绵铁为反应介质,设计了一套多介质渗透反应格栅模拟氨氮在各介质环境中的转化及归宿.结果表明,在天然河沙层,氨氮优先被河沙吸附固定,但去除量有限(△C<1.5 mg/L),氨氮主要以离子态溶于模拟地下水.在好氧沸石层,氨氮经沸石吸附及生物硝化协同作用几乎被完全去除,该层出水氨氮浓度低于0.01 mg/L,且氮主要存在形态为硝酸盐氮(C=10~26.6 mg/L).在铁厌氧层,部分硝酸盐氮经海绵铁化学还原和生物反硝化作用,分别被转化为氨氮(△C=2~9.5 mg/L)和氮气(△C<8 mg/L),其余硝酸盐氮以离子态继续存留于模拟地下水.%In the process of using permeable reactive barrier to remediate ammonia-N pollution in the groundwater,in order to control different media' s effect and nitrogen transformation process in multi-media permeable reactive barrier,it was important to understand the transformation and existing form of ammonia-N in different media environments.Natural river sand,oxygen releasing compounds,clinoptilolite and sponge iron were selected as reaction media to simulate the transformation and fate of ammonia-N in various media environments,which influent concentrations were about 10 mg/L in the simulative groundwater.The experimental results showed that,in natural river sand layer,ammonia-N was prior adsorbed and fixed by river sand,however,the removal quantity was limited (△ C < 1.5 mg/L).Ammonia-N mainly dissolved in the simulative groundwater with ionic form.In aerobic clinoptilolite layer,ammonia-N was nearly completely removed by the clinoptilolite adsorption and bio-nitrification,the effluent

  4. MEDICIÓN EXPERIMENTAL DE LA MAGNITUD DE LAS FUERZAS REACTIVAS EN LOS APOYOS DE LAS MAZAS DEL MOLINO PANELERO APOLO 5 EXPERIMENTAL MEASUREMENT OF MAGNITUDE REACTIVE FORCES IN MACE SUPPORTS OF PANELA MILL APOLO 5

    Directory of Open Access Journals (Sweden)

    Juan Fernando Ramírez Patiño

    2008-06-01

    Full Text Available La producción de panela en Colombia es una actividad a la que se dedican miles de campesinos, en la cual basan su economía y sustento y la cual lleva décadas sin ningún tipo de avance tecnológico en la maquinaria y las diferentes etapas del proceso de producción de la misma. En específico la maquinaria usada para la extracción de jugo de caña se basa en tecnología de mas de 100 años, en la que no se han hecho mayores esfuerzos por su mejoramiento, quizá debido al desconocimiento de las variables implicadas en el proceso de extracción y su influencia sobre las fuerzas y esfuerzos que se generan sobre las cureñas de los molinos, lo cual dificulta el mejoramiento de éstas desde el punto de vista de la forma, materiales y dimensiones. En este trabajo se presenta el desarrollo experimental para la medición de las fuerzas reactivas en los apoyos de los ejes de las mazas del molino panelero marca Apolo 5. Se incluyen la correcta selección de los puntos de medición en el molino, la elección de la técnica de medición y el diseño de los dispositivos para la medición, así como el procedimiento a seguir para la instrumentación del molino. Los resultados obtenidos permiten identificar las zonas en las cureñas y en los ejes donde se aplican las máximas fuerzas.The panela production in Colombia is an activity for thousands of farmers in which base their economy and sustenance and in which technology takes decades without any type of technological advance in machinery and different stages of production process in the same one. Specifically the machinery used for the extraction of cane juice is based on technology of more than 100 years with few efforts for its improvement, maybe due to ignorance of the implied variables in the extraction process and its influence on forces and stresses that are generated on mill cureñas, which makes difficult the improvement of these from the point of view of form, materials and dimensions. This work

  5. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation; Langzeitverhalten von elementarem Eisen und Hydroxylapatit zur Uranrueckhaltung in permeablen reaktiven Waenden bei der Grundwassersanierung

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, V.

    2007-11-21

    Elemental iron (Fe{sup 0}) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using {sup 237}U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}OH, 99 % < 0.42 mm) supplied by Che-mische Fabrik Budenheim CFB, Germany. Both materials exhibited uranium retention of more than 99.9% and sorption capacities of up to 28.3 mg U/g HAP and more than 38.4 mg U/g Fe{sup 0} (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe{sup 0} columns with effluent uranium con-centrations being below the detection limit of 10 {mu}g/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe{sup 0} columns with 200 PV of uranium free AGW. However, columns with high Fe{sup 0} content ({>=} 50%) suffered from severe loss of permeability when AGW with {>=} 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 {mu}g/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing

  6. 地下水中氯代烃的格栅水处理技术%TREATMENT TECHNOLOGY OF VOLATILE CHLORINATED ORGANIC COMPOUNDS IN GROUNDWATER BY PERMEABLE REACTIVE BARRIER

    Institute of Scientific and Technical Information of China (English)

    刘菲; 钟佐燊

    2001-01-01

    Volatile chlorinated organic compounds are the kind of organic contaminant that has the higher detection frequency in groundwater, and that is the main byproducts of drinking water disinfected with chlorine. The volatile chlorinated organic compounds have been proved to be harmful to human’s health by USEPA. This paper described the treatment technology of volatile chlorinated organic compounds in groundwater by permeable reactive barrier (PRB) including the materials of PRB, degradation mechanism, the factors of dechlorination efficient, and the problems of engineering and development direction. It introduces the newest development and practical value of reductive dechlorination by PRB. It proposes the potential and problems to be solved. Particularly, there are problems of catalytic principle and catalyst deactivation in bimetallic systems. The paper will give some study information for domestic researcher.%挥发性氯代烃是地下水中检出率较高的有机污染物,同时也是饮用水氯气消毒的副产物,而它对人体的危害也已经得到了USEPA等机构的认同。文中主要从格栅材料、降解机理、影响还原性脱氯效率的因素、实际工程中应注意的问题以及发展方向等方面,对地下水中挥发性氯代烃的处理技术进行了阐述,介绍了格栅处理地下水中挥发性氯代烃的最新进展和实际意义,提出了格栅系统的实际应用潜力和存在的问题,特别是双金属系统的催化机理和催化剂失活问题,给国内这方面的研究者提供思路。

  7. Relación entre los niveles séricos de la proteína C reactiva y medidas antropométricas: una revisión sistemática de los estudios realizados en Suramérica Relation of serum levels of C-reactive protein to anthropometric meaurements: a sustematic review of studies in South America

    Directory of Open Access Journals (Sweden)

    M.ª M Ramírez Alvarado

    2012-08-01

    Full Text Available En muchos estudios el Índice de Masa Corporal (IMC se ha relacionado con marcadores séricos de inflamación como la proteína C reactiva. En la obesidad se observa un aumento de tejido adiposo que se traduce en un aumento del IMC. Se ha descrito que el tejido adiposo presenta una elevada producción y secreción de una variedad de moléculas proinflamatorias como Factor de Necrosis Tumoral-α, Interleuquina-6, Interleuquina-8 y la proteína C reactiva, que pueden tener efectos locales en la fisiología de la célula adiposa y también efectos sistémicos en otros órganos. Objetivo: Realizar una revisión sistemática de los estudios realizados en Suramérica donde se relacione los niveles séricos de PCR y las medidas antropométricas como IMC y circunferencia de cintura (CC en la población adulta sana. Metodología: Se realizó una búsqueda en la base de datos PubMed de artículos publicados hasta enero de 2012, en inglés, español y portugués, donde se relacione los niveles séricos de PCR y las medidas antropométricas como IMC y CC. Para la búsqueda se utilizaron las palabras PCR, IMC y CC y los nombres de cada uno de los países suramericanos (Argentina, Bolivia, Brasil, Chile, Colombia, Ecuador, Guyana, Paraguay, Perú, Surinam, Uruguay y Venezuela. Resultados: Se localizaron 141 posibles de estudios, de los cuales 8 cumplían los criterios de inclusión. En los estudios incluidos los niveles séricos de la PCR se correlacionaron positivamente con el IMC (r: 0,08 a 0,84 y con la CC (r: 0,27 a 1,03, siendo de gran relevancia la correlación entre IMC y CC con los niveles séricos de PCR observada en obesos en la población suramericana. Conclusión: Los niveles séricos de PCR, y por tanto la inflamación subclínica parece estar relacionada al aumento en los índices de medidas antropométricas en la población suramericana. Un mayor conocimiento de los mecanismos y de los componentes moleculares de la respuesta inflamatoria

  8. Neutropenia Inmune - Aloinmune neonatal: IgG sérica reactiva y fenotipo específico de los neutrófilos evaluados por citometría de flujo Autoimmune-alloimmune neonatal neutropenia: Serum reactive IgG and neutrophil-specific phenotype detected by flow cytometry

    Directory of Open Access Journals (Sweden)

    Norma E. Riera

    2006-10-01

    Full Text Available La neutropenia inmune se diagnostica por la presencia de auto o aloanticuerpos reactivos con los neutrófilos. La neutropenia aloinmune neonatal es consecuencia de la sensibilización materna a los antígenos específicos de los neutrófilos paternos que afectan al neonato al atravesar la barrera placentaria. Se presentan 4 casos de niños, 2 de ellos hermanos consanguíneos con doble vínculo. Se estudiaron los sueros de los pacientes y sus padres. Por citometría de flujo se establecen los valores de referencia de la IgG sérica reactiva con los neutrófilos en voluntarios sanos, para 3 diluciones (1/2, 1/5 y 1/20 en reacción autóloga (suero y células de un mismo individuo y heteróloga (suero y células de diferentes individuos. Los resultados se expresan por un índice definido como el cociente entre la mediana de la intensidad de fluorescencia media del suero incógnita y la de un suero utilizado como referencia. Por leucoaglutinación se evaluó la dilución del suero 1/20. Se determinó el nivel de complejos inmunes circulantes. Se determinó el fenotipo, para los epitopes HNA-1a, HNA-1b y HNA-2a. En los 4 niños se encontró IgG reactiva y/o factores aglutinantes; 2/3 sueros maternos fueron reactivos con los neutrófilos del cónyuge y de los hijos. Los complejos inmunes circulantes fueron positivos en 2/4 sueros negativos en 3/3 sueros maternos. Se encontró incompatibilidad materno-infantil en los 4 casos. Las 3 madres tenían igual fenotipo: homocigotos NA1/NA1, NB1+. En síntesis, se presenta el hallazgo de 4 casos con neutropenia inmune: 3/4 auto-inmune, 1/3 se asocia a complejos inmunes circulantes y 1/4 con neutropenia neonatal aloinmune.Auto or alloantibodies reactive with neutrophils define immune neutropenia. Alloimmune neonatal neutropenia is caused by maternal sensitization to paternal neutrophil antigens, resulting in IgG antibodies that are transferred to the fetus through the placenta. We present the studies in 4

  9. Reactive multiphase flow simulation workshop summary

    Energy Technology Data Exchange (ETDEWEB)

    VanderHeyden, W.B.

    1995-09-01

    A workshop on computer simulation of reactive multiphase flow was held on May 18 and 19, 1995 in the Computational Testbed for Industry at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. Approximately 35 to 40 people attended the workshop. This included 21 participants from 12 companies representing the petroleum, chemical, environmental and consumer products industries, two representatives from the DOE Office of Industrial Technologies and several from Los Alamos. The dialog at the meeting suggested that reactive multiphase flow simulation represents an excellent candidate for government/industry/academia collaborative research. A white paper on a potential consortium for reactive multiphase flow with input from workshop participants will be issued separately.

  10. Reactive Hypoglycemia

    Science.gov (United States)

    ... from low blood sugar (hypoglycemia) that occurs while fasting. Signs and symptoms of reactive hypoglycemia may include ... and very important. It's also important to include physical activity in your daily routine. Your doctor can help ...

  11. Reactive Arthritis

    Directory of Open Access Journals (Sweden)

    Eren Erken

    2013-06-01

    Full Text Available Reactive arthritis is an acute, sterile, non-suppurative and inflammatory arthropaty which has occured as a result of an infectious processes, mostly after gastrointestinal and genitourinary tract infections. Reiter syndrome is a frequent type of reactive arthritis. Both reactive arthritis and Reiter syndrome belong to the group of seronegative spondyloarthropathies, associated with HLA-B27 positivity and characterized by ongoing inflammation after an infectious episode. The classical triad of Reiter syndrome is defined as arthritis, conjuctivitis and urethritis and is seen only in one third of patients with Reiter syndrome. Recently, seronegative asymmetric arthritis and typical extraarticular involvement are thought to be adequate for the diagnosis. However, there is no established criteria for the diagnosis of reactive arthritis and the number of randomized and controlled studies about the therapy is not enough. [Archives Medical Review Journal 2013; 22(3.000: 283-299

  12. Los volcanes y los hombres

    OpenAIRE

    García, Carmen

    2007-01-01

    Desde las entrañas de la tierra, los volcanes han creado la atmósfera, el agua de los océanos, y esculpido los relieves del planeta: son, pues, los zahoríes de la vida. Existen volcanes que los hombres explotan o cultivan, y otros sobre los cuales se han construido observatorios en los que se llevan a cabo avanzadas investigaciones científicas.

  13. Los Neutrinos Los Neutrinos

    Directory of Open Access Journals (Sweden)

    Julián Félix

    2012-02-01

    Full Text Available From all the proposals to understand the structure of matter, and the way the natural world is conformed, the one about neutrinos is the most enigmatic, abstract, and foreign to immediate experience; however, this is the one that has delved more deeply over the nearly eighty years since it was formulated by Wolfgang Pauli –in 1930- as a radical proposition to understand nucleon decay, and the decay of other particles, without the violation of the principle of conservation of energy and momentum at subatomic level. This proposition has evolved through the years, and from Pauli’s original idea only the basic elements remain.This article contains the tale of the hypothesis of neutrinos, its early history, its evolution up to present day, and the efforts done nowadays to study them. In summary, this is the physics of neutrinos. De todas las propuestas para entender la estructura de la materia, y la conformación del mundo natural, los neutrinos es la más enigmática, abstracta, y ajena a la experiencia inmediata; sin embargo, es la que más hondo ha ido calando a lo largo de los ya casi ochenta años de haber sido formulada por Wolfgang Pauli –en el año 1930- como una medida radical para entender el decaimiento de los nucleones, y otras partículas, sin que se violara el principio de la conservación de la energía y del momento a nivel subatómico. La propuesta ha evolucionado a lo largo de los años, y de la idea original de Pauli ya sólo lo básico permanece. En este artículo está el relato de la hipótesis de los neutrinos, su historia primera, su evolución hasta el presente, los esfuerzos que en la actualidad se realizan para estudiarlos. En breve, ésta es la física de los neutrinos.

  14. Regeneración de los defectos periodontales intraóseos: combinación de membranas barrera y material de relleno: evidencia preclínica y clínica Regenerative procedure for intra-bony periodontal defects: Combination of barrier membrane and filling material, clinical and preclinical evidence

    Directory of Open Access Journals (Sweden)

    N. Discepoli

    2012-12-01

    Full Text Available La terapia periodontal regenerativa tiene como objetivo lo de restaurar los tejidos de soporte periodontal y debería resultar en la formación de nueva inserción conectiva y (nuevo cemento con nuevas fibras del ligamento periodontal insertada y nuevo hueso. Evidencia histológica en modelos preclínicos ha demostrado regeneración después de tratamiento con membranas barreras, distintos tipos de material de relleno y una combinación de los dos. De todas formas, todavía no queda claro en qué extensión la combinación de membranas barreras y material de relleno puede promover de manera adicional el proceso de regeneración en comparación con tratamientos únicos.Regenerative periodontal therapy aims to predictably restore the tooth's supporting periodontal tissues and should result in formation of a new connective tissue attachment (i.e. new cementum with inserting periodontal ligament fibres and new alveolar bone. Histologic evidence from preclinical models has demonstrated periodontal regeneration following treatment with barrier membranes, various types of grafting materials or a combination thereof. However, it is still not clear to what extenta combination of barrier membranes and grafting materials may additionally enhance the regeneration process compared with barrier membranes alone, grafting materials alone or open flap debridement.

  15. Reactividad Química de los Azo Colorantes Amarillo Anaranjado y Rojo Allura mediante Descriptores Globales y la Función de Fukui Chemical Reactivity of the Azo dyes Sunset Yellow and Allura Red by Global Descriptors and the Fukui Function

    Directory of Open Access Journals (Sweden)

    Adolfo E Ensuncho

    2012-01-01

    Full Text Available Se calcularon descriptores globales y locales de la reactividad para los colorantes amarillo anaranjado y rojo allura con el fin de analizar su reactividad química intrínseca. Los cálculos computacionales se llevaron a cabo tanto en vacio como en la fase acuosa, la cual se representó por medio de una constante dieléctrica de 78.5 e introducida por el modelo de solvente del continuo polarizado. Los resultados mostraron que el colorante rojo allura es menos susceptible a la adición nucleofílica que el amarillo anaranjado, ya que los sustituyentes electrodonadores metilo y metoxilo disminuyen la capacidad del grupo azo para aceptar electrones. El análisis de la función condensada de Fukui para el ataque nucleofílico e índice de electrofilicidad local, mostraron que el sitio preferido de ataque del agente reductor (ión bisulfito fue C4, lo cual estuvo en concordancia con los reportes experimentales.In the present work local and global descriptors of the reactivity were calculated for sunset yellow and allura red to analyze its intrinsic reactivity. The computational calculations were carried out in vacuum and aqueous phase. The aqueous phase is represented by a dielectric constant of 78.5, introduced by polarizable continuum model. The results show that allura red is less susceptible to nucleophilic addition than sunset yellow, because the electrodonor substituents methyl and methoxy decrease the capability of the azo group to accept electrons. The analysis of condensed Fukui function for a nucleophilic attack and local electrophilicity index showed that the preferred direction of attack the reducing agent (bisulfite ion occurs on C4, which was in good agreement with experimental reports.

  16. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  17. Cytokines and the Skin Barrier

    Directory of Open Access Journals (Sweden)

    Jens Malte Baron

    2013-03-01

    Full Text Available The skin is the largest organ of the human body and builds a barrier to protect us from the harmful environment and also from unregulated loss of water. Keratinocytes form the skin barrier by undergoing a highly complex differentiation process that involves changing their morphology and structural integrity, a process referred to as cornification. Alterations in the epidermal cornification process affect the formation of the skin barrier. Typically, this results in a disturbed barrier, which allows the entry of substances into the skin that are immunologically reactive. This contributes to and promotes inflammatory processes in the skin but also affects other organs. In many common skin diseases, including atopic dermatitis and psoriasis, a defect in the formation of the skin barrier is observed. In these diseases the cytokine composition within the skin is different compared to normal human skin. This is the result of resident skin cells that produce cytokines, but also because additional immune cells are recruited. Many of the cytokines found in defective skin are able to influence various processes of differentiation and cornification. Here we summarize the current knowledge on cytokines and their functions in healthy skin and their contributions to inflammatory skin diseases.

  18. What Is Reactive Arthritis?

    Science.gov (United States)

    ... 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 ...

  19. Los adolescentes y los estigmas

    OpenAIRE

    Janin, Beatriz

    2013-01-01

    En este trabajo se desarrolla el tema de los diagnósticos tempranos en los que se rotula a un niño como deficitario y de las dificultades de los adolescentes que llegan a esa etapa crítica de la vida portando algún “cartel" que los señala como un “sindrome" o un “trastorno de...". Este estigma suele dificultarles el rearmado narcisista, la relación con el grupo de pares y la salida exogámica. Se habla de la crisis adolescente y de los avatares particulares de la sexualidad en estos casos. ...

  20. Barreiras e soluções nos Cuidados Continuados a Pessoas Idosas: percepções de Enfermeiros(as Barreras y soluciones en los Cuidados Continuos a Personas Ancianas: percepciones de Enfermeros(as Barriers and solutions in Continuing Care for the Elderly: Nurses’ perceptions

    Directory of Open Access Journals (Sweden)

    João Paulo de Almeida Tavares

    2010-07-01

    -estructuradas con trece enfermeros(as y analizados con base en el método hermenéutico-dialéctico. Los resultados del estudio evidenciaron que las barreras y las posibles soluciones son mayoritariamente de orden administrativo, financiero y organizacional, las cuales dificultan la efectividad de los cuidados continuos a las personas ancianas en esta unidad.The National Network for Integrated Continuing Care (RNCCI was created in Portugal, in 2006 to provide continuing care for the elderly and for dependent citizens. In this context, where nurses play an class="medium-text1">a leading role, there is a lack of studies which could identify barriers to Continuing Care (CC. Therefore, the aim of this study was to identify the barriers perceived by nurses to the development of continuing care for the elderly in an Integrated Continuing Care Unit and possible solutions to improve effectiveness. A qualitative, exploratory, descriptive approach was adopted for the study. Data were collected through semi-structured interviews with 13 nurses and analyzed using a hermeneutic-dialectic method. The results showed that the barriers and possible solutions which hinder the effectiveness of CC for the elderly in this unit are mainly administrative, financial and organisational.

  1. Local Chemical Reactivity of a Metal Alloy Surface

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Scheffler, Matthias

    1995-01-01

    The chemical reactivity of a metal alloy surface is studied by density functional theory investigating the interaction of H2 with NiAl(110). The energy barrier for H2 dissociation is largely different over the Al and Ni sites without, however, reflecting the barriers over the single component metal...

  2. Los insomnios

    OpenAIRE

    Takeuchi Tan, Yuri; Fundación Valle de Lili

    1998-01-01

    Los insomnios/El sueño normal/Otros trastornos de sueño que producen insomnio pero también hipersomnio (excesiva somnolencia diurna)/Manejo y tratamiento de los insomnios/Higiene del sueño/Instrucciones para la higiene del sueño/Técnicas conductuales/Terapia farmacológica.

  3. Surfactantes reativos não-iônicos em polimerização em emulsão de látices de acetato de vinila - vinil neodecanoato: influência nas propriedades de barreira à água Nonionic reactive surfactants in emulsion polymerization of vinyl acetate - vinyl neodecanoate latexes: influence on the water barrier properties

    Directory of Open Access Journals (Sweden)

    Jorge M. de Oliveira

    2009-01-01

    Full Text Available A indústria de tintas é grande consumidora de látex obtido por polimerização em emulsão. Os surfactantes, essenciais à estabilidade do látex, exercem papel fundamental na produção e na aplicação destes polímeros. Contudo, podem também produzir efeitos adversos nas propriedades do produto, em razão de sua adsorção física às partículas de polímero. Os surfactantes não ligados podem migrar através do filme para as interfaces, formando agregados que podem aumentar a sensibilidade à água, afetando desta forma as propriedades de barreira. Um caminho promissor para minimizar este efeito dos surfactantes convencionais tem sido o uso de surfactantes polimerizáveis, ou reativos, que estão covalentemente ligados ao polímero e, desta forma, não podem ser dessorvidos e migrarem durante a formação do filme. Neste trabalho foram preparados látices de acetato de vinila - vinil neodecanoato (VeoVa 10®, estabilizados com surfactantes não-iônicos convencionais e reativos, e avaliado o desempenho dos filmes obtidos a partir destes látices. Os resultados demonstraram que o uso de surfactantes não-iônicos polimerizáveis pode, sob determinadas condições, trazer ganhos para as propriedades de barreira.The paint industry is a huge consumer of latex from emulsion polymerization. The surfactants, essential to the stability of the latex, play a crucial role in the production and application of emulsion polymers. However, they can also have adverse effects on product properties due to their physical adsorption on the polymer particles. The unbound surfactants can migrate through the film toward the interfaces forming aggregates which increase water sensitivity of the film, thus affecting its barrier properties. A promising way to reduce the negative effects of the conventional surfactants is to use polymerizable or reactive surfactants (surfmers that are covalently linked to the polymer, which avoids its desorption and migration

  4. Los Cactos

    Directory of Open Access Journals (Sweden)

    García Paredes Antonio

    1942-12-01

    Full Text Available El Cacto Cactus es uno de los géneros de plantas de la familia de las Cacteas Nopaleas que contiene muchas especies y variedades todas de formas extrañas, propias de la América intertropical y que habitan en los climas fríos y templados, en terrenos secos y estériles, desde el norte de Méjico hasta la Patagonia. Algunos cactos se cultivan por sus frutos que son sanosy sabrosos, otros como plantas ornamentales en los parques y jardines, otros como auxiliares para la industria, como los nopales en los que se cría la Cochinilla, insecto de la familia de los Hemípteros que produce la laca o carmín, materia colorante indispensable en la pintura al óleo y la acuarela, y por último, hoy están en moda y se cultivan con esmero una gran variedad de diminutos cactos exóticosque se mantienen sobre arena húmeda en pequeñas maceteras de porcelana, en los lugares más visibles de las habitaciones.

  5. Trends in reactivity of oxides

    DEFF Research Database (Denmark)

    Toftelund, Anja

    , and I) and OH on a wide range of rutile oxide surfaces. Furthermore, Brønsted-Evans-Polanyi (BEP) relations are found for the adsorption of a large number of molecules (including Cl, Br and I) on transition metal oxides. In these relations the activation energies scale linearly with the dissociative...... chemisorption energies. It turns out that the BEP relation for rutile oxides is almost coinciding with the dissociation line, i.e. no barrier exists for the reactive surfaces. The heterogeneous catalytic oxidation of hydrogen halides (HCl, HBr, and HI) is investigated. A micro-kinetic model is solved...

  6. Evaluación del efecto de la ingesta de una sobrecarga de glucosa sobre los niveles séricos de la proteína C reactiva y de la α1-antitripsina en mujeres obesas Effect of a high glucose load on serum concentrations of C-reactive protein and α1-antitrypsin in obese women

    Directory of Open Access Journals (Sweden)

    M.ª M. Ramírez A.

    2008-08-01

    Full Text Available La obesidad está asociada con un estado inflamatorio. La proteína C reactiva (PCR es una molécula proinflamatoria y la α1-antitripsina es una proteína plasmática sensible a inflamación. El proceso proinflamatorio puede ser influenciado por la hiperglicemia postprandial. Objetivo: Evaluar el efecto de la ingesta de una sobrecarga de glucosa sobre los niveles séricos de PCR y de α1-antitripsina en mujeres obesas con tolerancia normal a la glucosa. Metodología: La población estuvo conformada por 15 mujeres obesas (edad = 34,4 ± 4,3 años, IMC = 35,3 ± 5,3 kg/m² y 15 mujeres normopeso (edad = 33,9 ± 2,9 años, IMC = 21,8 ± 1,9 kg/m². Los sujetos en ayuno se sometieron a una prueba de tolerancia oral a la glucosa (75 g y 2 h. Se midió los niveles pre y postprandiales de PCR y de α1-antitripsina. Los parámetros antropométricos y bioquímicos se midieron en ambos grupos. Resultados: Las mujeres obesas presentaron mayores niveles de PCR en ayuno (P = 0,05 diferencia con el nivel preprandial. Los niveles séricos de PCR se correlacionaron positivamente con el índice de masa corporal (IMC en el grupo obeso. Los niveles séricos de α1-antitripsina no se correlacionaron con el IMC en ninguno de los dos grupos estudio. Conclusión: La ingesta de una sobrecarga de glucosa no tiene ningún efecto sobre los niveles séricos de PCR y α1-antitripsina. Los niveles séricos de α1-antitripsina no están incrementados en mujeres obesas. Los niveles séricos de PCR están incrementados en mujeres obesas y se correlacionan positivamente con el IMC.Obesity is associated with increased inflammation. C-reactive protein (CRP is a proinflammatory molecule, and α1-antitrypsin is an inflammation-sensitive plasma protein. Proinflammatory process may be influenced by postprandial hyperglycemia. Objective: The aim of the present study was to evaluate the role of high-glucose load on postprandial circulating levels of PCR and α1-antitrypsin in obese

  7. los aprendizajes

    Directory of Open Access Journals (Sweden)

    Graciela Pérez Rivera

    2007-01-01

    Full Text Available En este documento se presentan algunos resultados, obtenidos hasta el momento, de un estudio sobre las prácticas de evaluación de profesores universitarios. El propósito del estudio es participar en la búsqueda de las relaciones existentes entre los conceptos y las prácticas educativas, en este caso de evaluación. Se identifican las principales tendencias en cuanto a la concepción de la evaluación del aprendizaje y las funciones que se le otorgan, los propósitos con los que se evalúa, los objetos o contenidos a evaluar, las formas en que se lleva a cabo la evaluación y el uso que se da a los resultados. Identificar cuáles son las tendencias de las prácticas de evaluación en nuestras aulas universitarias representa un paso que puede ayudar a cuidar que este proceso tan importante recobre su papel formativo para todos aquellos quienes participamos en los procesos educativos; además, representa la posibilidad de construir formas para lograr mejorar nuestra labor docente en general, y en particular, nuestra práctica evaluativa.

  8. Smart parking barrier

    KAUST Repository

    Alharbi, Abdulrazaq M.

    2016-05-06

    Various methods and systems are provided for smart parking barriers. In one example, among others, a smart parking barrier system includes a movable parking barrier located at one end of a parking space, a barrier drive configured to control positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking space and a second position that allows access to the parking space. The parking controller can initiate movement of the movable parking barrier in response to a positive identification of an individual allowed to use the parking space. The parking controller can identify the individual through, e.g., a RFID tag, a mobile device (e.g., a remote control, smartphone, tablet, etc.), an access card, biometric information, or other appropriate identifier.

  9. Los compadres

    Directory of Open Access Journals (Sweden)

    Luis Muñoz

    2010-03-01

    Full Text Available De lejos parecen ser personas muy silenciosas y cuando hablan lo hacen con una entonación diferente. Comienza un día hermoso en el que vamos a visitarlos y el humor es la disculpa más agradable para hacer alianzas. La señora va y viene del cuarto oscuro donde se encuentra el fogón, interviniendo a veces, con su presencia viva en la charla, aunque no lo parece. Un café, una taza de leche y roscones, un vaso de guarapo, una y otra vez. No sé como llamarlos; si cuenteros, poetas, hombres hablando. Los percibo como portadores de una tradición oral, compartiendo con nosotros sus pensamientos y creencias más profundos, en tomo a todos los matices de su realidad social. En la tradición oral se piensa el mundo de una manera integral mientras la cotidianidad está cada vez más condicionada por un mundo segmentado y especializado. Los cuentos innumerables que conocen han sido escuchados y modificados por niños, hombres y mujeres de todas las edades. Cualquier actividad diaria es buena para contar. Las noches en la caza de Luis son acogedoras, la señora Angelita prepara una sopa de maíz y tomamos hasta dos platos llenos para calentamos. La única esperma que ilumina la penumbra de la conversación se consume poco a poco. Los primeros días de mi visita sentí lo que llamaría miedos culturales, como mi obsesión por los insectos que imaginaba dentro de la casa, la cual se fue disipando en la medida en que afirmábamos nuestros lazos. Noches de tertulia, de diálogo, de cuentos. Generalmente Luis pasa esas horas escribiendo o leyendo, dedicado a su mayor afición que es la literatura, conversando con doña Angelita y escuchando cuando ella relata cuentos y anécdotas. Al joven escritor autodidacta lo cautivan las vivencias y fantasías humanas. Escribe sobre su gente y está interesado en las tradiciones literarias de la región. Trabaja como jornalero en fincas o haciendas, realizando varios oficios como la carpintería, la agricultura, la

  10. Reactive Kripke semantics

    CERN Document Server

    Gabbay, Dov M

    2013-01-01

    This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

  11. Brain Barrier Breakdown as a Cause and Consequence of Neuroinflammation in Sepsis.

    Science.gov (United States)

    Danielski, Lucineia Gainski; Giustina, Amanda Della; Badawy, Marwa; Barichello, Tatiana; Quevedo, João; Dal-Pizzol, Felipe; Petronilho, Fabrícia

    2017-01-14

    The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) are important for the maintenance of brain homeostasis. During sepsis, peripheral production of proinflammatory cytokines and reactive oxygen species are responsible for structural alterations in those brain barriers. Thus, an increasing permeability of these barriers can lead to the activation of glial cells such as microglia and the production of cytotoxic mediators which in turn act on the brain barriers, damaging them further. Thereby, in this review, we try to highlight how the brain barrier's permeability is not only a cause but a consequence of brain injury in sepsis.

  12. Safety-barrier diagrams

    DEFF Research Database (Denmark)

    Duijm, Nijs Jan

    2007-01-01

    are discussed. A simple method for quantification of safety-barrier diagrams is proposed, including situations where safety barriers depend on shared common elements. It is concluded that safety-barrier diagrams provide a useful framework for an electronic data structure that integrates information from risk......Safety-barrier diagrams and the related so-called "bow-tie" diagrams have become popular methods in risk analysis. This paper describes the syntax and principles for constructing consistent and valid safety-barrier diagrams. The relation with other methods such as fault trees and Bayesian networks...... analysis with operational safety management....

  13. Extremal surface barriers

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Netta; Wall, Aron C. [Department of Physics, University of California,Santa Barbara, CA 93106 (United States)

    2014-03-13

    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.

  14. Permeable Reactive Barriers: Lessons Learned/New Directions

    Science.gov (United States)

    2005-02-01

    treatment was not clear. It is possible that the nitrate was reduced to ammonia abiotically or that some microbially mediated denitrification within the...industrial needs. For consideration in a PRB design, the zeolitic mineral clinoptilolite olid solution composition [(Ca, Mg, Na2, K2) (Al2Si10O24...2005 An example pilot program evaluating the use of the zeolite clinoptilolite to remove Sr-90 from groundwater was initiated in 1999 at the West

  15. Innovative reactive barrier technologies for regional contaminated groundwater

    NARCIS (Netherlands)

    Merkel, P.; Weiβ, H.; Teutsch, G.; Rijnaarts, H.H.M.

    2000-01-01

    At many industrial sites inadequate waste disposal, leakages and war damages have led to severe groundwater contamination on a regional scale. Standard hydraulic groundwater remediation methods, such as pump-and-treat, in most cases do not lead to satisfactory results, due to the persistence of orga

  16. Innovative reactive barrier technologies for regional contaminated groundwater

    NARCIS (Netherlands)

    Merkel, P.; Weiβ, H.; Teutsch, G.; Rijnaarts, H.H.M.

    2000-01-01

    At many industrial sites inadequate waste disposal, leakages and war damages have led to severe groundwater contamination on a regional scale. Standard hydraulic groundwater remediation methods, such as pump-and-treat, in most cases do not lead to satisfactory results, due to the persistence of

  17. Diffusion barriers evoked in the rat cortex by reactive astrogliosis.

    Science.gov (United States)

    Roitbak, T; Syková, E

    1999-10-01

    Changes in extracellular space (ECS) diffusion parameters in astrogliotic tissue around a unilateral cortical stab wound were determined from concentration-time profiles of tetramethylammonium (TMA(+)) using TMA(+)-selective microelectrodes. Three diffusion parameters-ECS volume fraction alpha (alpha = ECS volume/ total tissue volume), tortuosity lambda (lambda(2) = D/ADC; where D is the free and ADC is the apparent diffusion coefficient of TMA(+) in the brain), and nonspecific TMA(+)uptake k'-were determined at 3, 7, 21, and 35 days postwounding (dpw), in the hemispheres ipsilateral and contralateral to the lesion. Following diffusion experiments, tissue sections were immunostained for glial fibrillary acidic protein (GFAP) and chondroitin-sulphate proteoglycans (CSPG). In the area 300-1000 micron around the wound, alpha was increased at 3, 7, and 21 dpw by about 20% but returned to control values at 35 dpw; lambda was increased at all four intervals, reaching a maximum at 7 dpw. k' was lower than in the contralateral hemisphere at 7, 21, and 35 dpw. Measurements 1,500-2,000 micron from the wound revealed only an increase in lambda at 7 dpw. The time course of changes in ECS diffusion parameters closely correlated with increased staining for GFAP and CSPG. Our results show that astrogliosis significantly changes the diffusion properties of nervous tissue, making it less permissive. Both hypertrophied astrocytic processes and an enhanced formation of some extracellular matrix molecules could affect, through changes in the diffusion of molecules in the ECS, neuron-glia communication, "cross-talk" between synapses, extrasynaptic transmission, and regenerative processes.

  18. Los ensayos

    Directory of Open Access Journals (Sweden)

    Beatriz Caballero

    2003-01-01

    Full Text Available Después de Suramérica, tierra del hombre y Latinoamérica, un mundo por hacer, al tiempo que papá es Swann, periodista, liberal, político, está escribiendo ensayo: en el 45 El nuevo príncipe, en el 47 el Breviario del Quijote. En el 48 asiste en Sevilla a la Asamblea Cervantina como delegado de la Academia Colombiana de la Lengua donde presenta y es publicada su Contribución de la crítica colombiana al estudio de Cervantes. En el 49 se edita Cartas colombianas, en el 50 Ancha es Castilla , en el 52 los Sueños gramaticales de Luciano Pulgar, en el 57 Americanos y europeos y en el 60 Historia privada de los colombianos. Los campesinos es una recopilación de notas periodísticas que puede considerarse un ensayo sobre la preocupación por el campo, y Yo, el alcalde del 72 puede considerarse un tratado sobre la administración municipal.

  19. Reactive Attachment Disorder

    Science.gov (United States)

    ... Reactive Attachment Disorder and Disinhibited Social Engagement Disorder. Reactive Attachment Disorder (RAD) Children with RAD are less likely to interact with other people because of negative experiences with adults in their early years. They have difficulty calming ...

  20. Reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Yadav Mukesh

    2009-01-01

    Full Text Available Reactive perforating collagenosis is a rare cutaneous disorder of unknown etiology. We hereby describe a case of acquired reactive perforating collagenosis in a patient of diabetes and chronic renal failure.

  1. Chemical gel barriers as low-cost alternative to containment and in situ cleanup of hazardous wastes to protect groundwater

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    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.

  2. Monadic Functional Reactive Programming

    NARCIS (Netherlands)

    Ploeg, A.J. van der; Shan, C

    2013-01-01

    Functional Reactive Programming (FRP) is a way to program reactive systems in functional style, eliminating many of the problems that arise from imperative techniques. In this paper, we present an alternative FRP formulation that is based on the notion of a reactive computation: a monadic computatio

  3. Los inmigrados

    Directory of Open Access Journals (Sweden)

    Lojze Kovačič

    2007-12-01

    Full Text Available Lojze Kovačič nació el 9 de noviembre de 1928 en Basilea, Suiza, en una familia de emigrantes, de madre alemana y padre esloveno. En 1938, cuando las autoridades suizas expulsaron del país a todos los emigrantes que no tenían ciudadanía suiza, se fue a vivir con su familia a Eslovenia, primero a Novo mesto, luego a Ljubljana donde frecuentó la escuela primaria, secundaria y la academia de pedagogía. Vivió en Ljubljana donde trabajó primero como periodista y luego como pedagogo. Murió el 1 de mayo de 2004 en la capital eslovena. Escribió obras autobiográficas y de ficción: Ljubljanske razglednice / Postales de Ljubljana (1956, Ključi mesta / Las llaves de la ciudad (1967, Deček in smrt / El niño y la muerte (1968, Sporočila v spanju – Resničnost / Mensajes en el sueño – Realidad (1972, Pet fragmentov / Cinco fragmentos (1981, Pri{leki / Los inmigrados (trilogía 1983–85, Basel / Basilea (1986, Prah / Polvo (1988, Kristalni čas / Tiempo de cristal (1990, Zgodbe s panjskih končnic / Relatos de las tablas de la colmena (1992, Knji`evna delavnica – {ola pisanja / Taller de literatura – escuela de la escritura (1997. A continuación se presentan dos fragmentos de la primera parte de la trilogía Pri{leki / Los inmigrados, una historia marcadamente autobiográfica del retorno a Eslovenia de una familia desalojada de Basilea, narrada a través de la voz de un niño de diez años, traducida al castellano por Xavier Farré y publicada por la editorial Siruela de Madrid en 2007.

  4. Los Wayuu

    OpenAIRE

    Vásquez Hernán De Correa, Socorro; Investigadores Departamento de Antropología. Universidad Javeriana Este artículo hace parte de una investigación realizada para el Instituto Colombiano de Cultura Hispánica, 1991.

    2004-01-01

    Estar presentes hoy, luego de estos 500 años, le ha significado a los Wayuú, indígenas habitantes de la Península de La Guajira; pasar por profundos cambios culturales que han sido la urdimbre que ha sostenido su cultura y la ha fortalecido permitien­do la supervivencia misma del pueblo Wayuú, el cual no fue sometido, redu­cido o aniquilado como otros pueblos aborígenes del continente, y por el contrario ha consolidado en su terri­torio unas formas de vida propia y de convivencia con la socie...

  5. Barriers to screening mammography.

    Science.gov (United States)

    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.

  6. Diagnóstico da tuberculose em pessoas idosas: barreiras de acesso relacionadas aos serviços de saúde El diagnóstico de la tuberculosis em las personas mayores: las barreras relacionadas con el acceso a los servicios de salud Tuberculosis diagnosis in the aged: barriers to accessing health services

    Directory of Open Access Journals (Sweden)

    Annelissa Andrade Virgínio de Oliveira

    2013-02-01

    de su vulnerabilidad, se sugiere que las acciones de control en ancianos sean emprendidas por los servicios de salud intentando evitar que la enfermedad se convierta en una patología común en dicho segmento poblacional.This study was performed with the objective to analyze the barriers to diagnosing tuberculosis in the aged and access to health services in the city of João Pessoa, Paraíba, Brazil. This qualitative study included the participation of seven aged women with tuberculosis. Interviews were used for data collection. The empirical material was organized using Atlas.ti 6.0, and analyzed according to the techniques of discourse analysis. The identified barriers related to the access to health services to confirm the diagnosis were: the operating hours of family health units; transferred responsibilities; home visits without controlling communicants; delay of the health service in suspecting the disease and the patient's repeated visits to the health center before being informed about the diagnosis. Despite the identification of common barriers that tuberculosis patients of all ages must deal with, because of the vulnerability of the elderly, health services should implement control actions so as to prevent the disease becoming a common condition in this population.

  7. Converse Barrier Certificate Theorems

    DEFF Research Database (Denmark)

    Wisniewski, Rafael; Sloth, Christoffer

    2016-01-01

    This paper shows that a barrier certificate exists for any safe dynamical system. Specifically, we prove converse barrier certificate theorems for a class of structurally stable dynamical systems. Other authors have developed a related result by assuming that the dynamical system has neither sing...

  8. Skin barrier function

    DEFF Research Database (Denmark)

    2016-01-01

    Renowned experts present the latest knowledge Although a very fragile structure, the skin barrier is probably one of the most important organs of the body. Inward/out it is responsible for body integrity and outward/in for keeping microbes, chemicals, and allergens from penetrating the skin. Since...... the role of barrier integrity in atopic dermatitis and the relationship to filaggrin mutations was discovered a decade ago, research focus has been on the skin barrier, and numerous new publications have become available. This book is an interdisciplinary update offering a wide range of information...... on the subject. It covers new basic research on skin markers, including results on filaggrin and on methods for the assessment of the barrier function. Biological variation and aspects of skin barrier function restoration are discussed as well. Further sections are dedicated to clinical implications of skin...

  9. Reactive Programming in Java

    CERN Document Server

    CERN. Geneva

    2017-01-01

    Reactive Programming in gaining a lot of excitement. Many libraries, tools, and frameworks are beginning to make use of reactive libraries. Besides, applications dealing with big data or high frequency data can benefit from this programming paradigm. Come to this presentation to learn about what reactive programming is, what kind of problems it solves, how it solves them. We will take an example oriented approach to learning the programming model and the abstraction.

  10. Converse Barrier Certificate Theorem

    DEFF Research Database (Denmark)

    Wisniewski, Rafael; Sloth, Christoffer

    2013-01-01

    This paper presents a converse barrier certificate theorem for a generic dynamical system.We show that a barrier certificate exists for any safe dynamical system defined on a compact manifold. Other authors have developed a related result, by assuming that the dynamical system has no singular...... points in the considered subset of the state space. In this paper, we redefine the standard notion of safety to comply with generic dynamical systems with multiple singularities. Afterwards, we prove the converse barrier certificate theorem and illustrate the differences between ours and previous work...

  11. Recycler barrier RF buckets

    Energy Technology Data Exchange (ETDEWEB)

    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. Los migrantes indocumentados y los derechos humanos

    National Research Council Canada - National Science Library

    Forero, Eduardo Andrés Sandoval

    2007-01-01

    ... con la migración desde la perspectiva multicultural. Se argumenta la necesidad de empoderar a los migrantes con los derechos humanos de tal forma que se defiendan de las violaciones a sus derechos laborales...

  13. Use of Postpartum Care: Predictors and Barriers

    Directory of Open Access Journals (Sweden)

    Jessica N. DiBari

    2014-01-01

    Full Text Available This study aimed to identify actual and perceived barriers to postpartum care among a probability sample of women who gave birth in Los Angeles County, California in 2007. Survey data from the 2007 Los Angeles Mommy and Baby (LAMB study (N = 4,075 were used to identify predictors and barriers to postpartum care use. The LAMB study was a cross-sectional, population-based study that examined maternal and child health outcomes during the preconception, prenatal, and postpartum periods. Multivariable analyses identified low income, being separated/divorced and never married, trying hard to get pregnant or trying to prevent pregnancy, Medi-Cal insurance holders, and lack of prenatal care to be risk factors of postpartum care nonuse, while Hispanic ethnicity was protective. The most commonly reported barriers to postpartum care use were feeling fine, being too busy with the baby, having other things going on, and a lack of need. Findings from this study can inform the development of interventions targeting subgroups at risk for not obtaining postpartum care. Community education and improved access to care can further increase the acceptability of postpartum visits and contribute to improvements in women’s health. Postpartum care can serve as a gateway to engage underserved populations in the continuum of women’s health care.

  14. [Vascular endothelial Barrier Function].

    Science.gov (United States)

    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.

  15. Barriers to Effective Listening.

    Science.gov (United States)

    Hulbert, Jack E.

    1989-01-01

    Discusses the following barriers which interfere with listening efficiency: content, speaker, medium, distractions, mindset, language, listening speed, and feedback. Suggests ways to combat these obstacles to accurate comprehension. (MM)

  16. Barriers to SCM implementing

    OpenAIRE

    M.E. Rosli; B. Md Dero; A. R. Ismail; M. N. Ab Rahman

    2008-01-01

    Purpose: This paper explores the barriers faced by Malaysian manufacturing companies in successfullyimplementing the Supply Chain Management (SCM). The study has highlighted some pertinent factorsperforming the barriers that are most frequently reported by the studied companies. Sixteen companies, fromservice and manufacturing companies were studied over a period of two years to assess their SCM practicesthrough survey and interview processes.Design/methodology/approach: This part discusses t...

  17. Performance characteristics of a self-sealing/self-healing barrier

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, R.G. [Water Technology International Corp., Burlington, Ontario (Canada)]|[Canadian Clean Technology Centre, Burlington, Ontario (Canada); Stegemann, J.A. [Canadian Clean Technology Centre, Burlington, Ontario (Canada)

    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.

  18. Los árboles

    Directory of Open Access Journals (Sweden)

    Jaime Paredes Pardo

    1964-09-01

    Full Text Available Los árboles son hijos del viento que transporta las semillas. En los valles anda de prisa, tanto que a veces alcanza a los trenes y a la melena de los caballos que espanta la algarabía de los pasajeros. Como los trenes, el viento tiene una frente de humo. De niebla como las montañas. ¿Pensará el viento?

  19. Reactive Power Compensation Method Considering Minimum Effective Reactive Power Reserve

    Science.gov (United States)

    Gong, Yiyu; Zhang, Kai; Pu, Zhang; Li, Xuenan; Zuo, Xianghong; Zhen, Jiao; Sudan, Teng

    2017-05-01

    According to the calculation model of minimum generator reactive power reserve of power system voltage stability under the premise of the guarantee, the reactive power management system with reactive power compensation combined generator, the formation of a multi-objective optimization problem, propose a reactive power reserve is considered the minimum generator reactive power compensation optimization method. This method through the improvement of the objective function and constraint conditions, when the system load growth, relying solely on reactive power generation system can not meet the requirement of safe operation, increase the reactive power reserve to solve the problem of minimum generator reactive power compensation in the case of load node.

  20. Reactive standard deontic logic

    OpenAIRE

    Gabbay, Dov M.; Straßer, Christian

    2015-01-01

    We introduce a reactive variant of SDL (standard deontic logic): SDLR1 (reactive standard deontic logic). Given a Kripkean view on the semantics of SDL in terms of directed graphs where arrows -> represent the accessibility relation between worlds, reactive models add two elements: arrows -> are labelled as 'active' or 'inactive', and double arrows a dagger connect arrows, e.g. (x(1) -> x(2)) a dagger (x(3) -> x(4)). The idea is that passing through x(1) -> x(2) activates a switch represented...

  1. Los Ritos de paso entre los bubi

    OpenAIRE

    Eteo Soriso, José Francisco

    2014-01-01

    Los ritos de paso entre los bubi es una etnografía sobre los rituales de nacimiento y de muerte entre los bubi de la isla de Bioko, Guinea Ecuatorial (África central). Está estructurada en dos partes: una etnográfica general y otra centrada en la ritualidad. La primera ofrece un marco suficientemente amplio sobre la sociedad bubi que permite introducir la segunda parte más específica sobre estructuras rituales. Los capítulos etnográficos introductorios se centran en algunos temas clave de la ...

  2. Perceptions of drugs benefits and barriers to quit by undergraduate health students Percepción de los beneficios del consumo de drogas y barreras para su abandono entre estudiantes del área de salud Percepção dos benefícios do consumo de drogas e das barreiras para seu abandono entre estudantes da área da saúde

    Directory of Open Access Journals (Sweden)

    Patricia Cid Henriquéz

    2008-08-01

    Full Text Available Several studies have exposed the consumption of drugs by undergraduate students in the health area, who are supposed to be examples of behavior and health educators. This descriptive correlation study aimed to relate the benefits of tobacco consumption and barriers to quit according to the perception of undergraduate students. Eighty third-year students, in three different courses, answered a self-applied questionnaire. The studied variables were: consumption conditions, barriers and benefits regarding drug consumption, family and personal characteristics. One-third of the students reported tobacco use; 5% reported the use of marijuana; 15% alcohol and 6% tranquilizers, more than once a month; 18% reported the consumption of tobacco and 13% reported the use of alcohol even before the age of 15. The perceived benefits were: relaxation, pleasure and social acceptance, whereas barriers for quitting were: habituation and addiction. According to the results, promoting self-responsibility of these future health professionals is recommended in their educational context.Diversos estudios evidencian consumo de drogas en estudiantes universitarios del área de la salud, de quienes se espera que sean modelos de rol y educadores en salud. El propósito de esta investigación descriptiva-correlacional fue establecer los beneficios que perciben los estudiantes universitarios del área de la salud para consumir tabaco y las barreras para abandonarlo. Respondieron un cuestionario autoadministrado 80 estudiantes del tercer año de tres carreras de salud. Las variables fueron condición de consumo, barreras y beneficios percibidos del consumo de drogas y características personales y familiares. Un tercio de los estudiantes fumaba tabaco. Más de una vez al mes declararon consumir marihuana un 5%; alcohol 15%; tranquilizantes 6%. Antes de los 15 años ya fumaba un 18% y un 13% bebía. Beneficios percibidos del consumo son relajación, placer y aceptación social

  3. Hedging Double Barriers with Singles

    NARCIS (Netherlands)

    Sbuelz, A.

    2000-01-01

    Double barrier options provide risk managers with good-deal flexibility in tailoring portfolio returns.Their hedges offer full protection only if unwound along the barriers.This work provides non-dynamic hedges that project the risk of double barriers on to single barriers.Non-dynamic hedges overcom

  4. Vacuum barrier for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, Roger P. (Jemez Springs, NM)

    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.

  5. Vacuum barrier for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Reactive Boundary Conditions as Limits of Interaction Potentials for Brownian and Langevin Dynamics

    CERN Document Server

    Chapman, S Jonathan; Isaacson, Samuel A

    2015-01-01

    A popular approach to modeling bimolecular reactions between diffusing molecules is through the use of reactive boundary conditions. One common model is the Smoluchowski partial absorption condition, which uses a Robin boundary condition in the separation coordinate between two possible reactants. This boundary condition can be interpreted as an idealization of a reactive interaction potential model, in which a potential barrier must be surmounted before reactions can occur. In this work we show how the reactive boundary condition arises as the limit of an interaction potential encoding a steep barrier within a shrinking region in the particle separation, where molecules react instantly upon reaching the peak of the barrier. The limiting boundary condition is derived by the method of matched asymptotic expansions, and shown to depend critically on the relative rate of increase of the barrier height as the width of the potential is decreased. Limiting boundary conditions for the same interaction potential in b...

  7. Nonquaternary Cholinesterase Reactivators.

    Science.gov (United States)

    1982-08-30

    1978, 34, 523. 30. Lehninger , A. L., " Biochemistry ," Worth Publ. Inc., New York, 1970, p. 161. 31. Green, A. L.; Smith, H. J.; Biochem. J., 1958, 68...nerve agent antidotes focuses on nonquaternary cholinesterase reactivators. In principle , it should be possible to find nonquaternary hydroximic acid...elicit pronounced physiological responses. In principle , it should be possible to develop nonquaternary AChE reactivators that would not only equal

  8. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  9. MENDING THE IN SITU MANIPULATION BARRIER

    Energy Technology Data Exchange (ETDEWEB)

    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

  10. MENDING THE IN SITU MANIPULATION BARRIER

    Energy Technology Data Exchange (ETDEWEB)

    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

  11. Influencia del índice de masa corporal y de otros factores de interés metabólico en los niveles de proteína C reactiva: Consideraciones sobre su posible valoración como marcador de comorbilidad y aspectos psiquiátricos Influence of the body mass index and other metabolic factors on the C-reactive protein: Considerations as a possible biomarker of comorbidity and psychiatric aspects

    Directory of Open Access Journals (Sweden)

    Jesús Medialdea Cruz

    2012-09-01

    Full Text Available Objetivos: El sobrepeso y la obesidad, por su frecuencia y la importancia médica de las complicaciones que conllevan, se han estudiado bajo muchos aspectos por su complejidad y heterogeneidad. El presente trabajo trata de estudiar en una muestra de 123 sujetos pertenecientes al sector aéreo (pilotos, controladores y tripulantes aéreos los siguientes aspectos: 1 Influencia del índice de masa corporal (IMC en los niveles de proteína C reactiva (PCR; 2 Frecuencia del Síndrome Metabólico (SM en la muestra seleccionada; 3 Relación entre la presencia de SM y los niveles de PCR; 4 valoración del nivel de PCR en función del número de criterios de SM; 5 Por último, algunas consideraciones bajo el punto de vista psiquiátrico de los resultados, según la literatura consultada. Material y métodos: A la muestra aleatoria seleccionada de 123 sujetos se les valoró los datos antropométricos (peso, talla, circunferencia de cintura, IMC y tensión arterial sistólica y diastólica, y se les determinó en suero el nivel de colesterol total, lipoproteínas de alta densidad (HDL, glucosa y triglicéridos, así como la PCR por métodos ultrasensibles. Resultados: Los resultados reflejaron una frecuencia de 36,5 % de individuos que cumplían los criterios de SM. Así mismo, se observó un incremento significativo de los niveles de PCR, que estaba relacionado con el número de criterios utilizados en el diagnóstico del mismo, así como un incremento de la PCR en aquellos sujetos con sobrepeso u obesidad con respecto a los sujetos con peso normal. Conclusiones: La PCR, como respuesta a un status inflamatorio, puede ayudarnos como marcador de comorbilidad de SM y de sujetos con sobrepeso y/o obesidad, y sugerirnos la existencia de una base inflamatoria que pueda tener influencia en el desarrollo de enfermedades cardiovasculares, metabólicas o en la aparición de trastornos psiquiátricos (sobre todo de tipo depresivo y su posible aplicación terap

  12. Barriers to cancer screening.

    Science.gov (United States)

    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

  13. Los pesticidas y los recursos costeros.

    Directory of Open Access Journals (Sweden)

    Evenor Martínez González.

    1998-10-01

    Full Text Available Los recursos costeros son de gran importancia para los países ribereños. Tanto la pesca como la acuicultura son actividades que generan divisas y dan empleo a una gran cantidad de personas. En nuestro país, la agricultura siempre ha sido dependiente del uso de los agroquímicos. Esta práctica, sumada al mal manejo de los suelos agrícolas y al despale en pendiente, ha tenido efectos negativos importantes en nuestros recursos acuáticos, la sedimentación. Los plaguicidas han contaminado a moluscos (conchas negras, peces y crustáceos (jaibas y camarones. En estos organismos los pesticidas se han acumulado causando su muerte.

  14. [Low reactive laser therapy].

    Science.gov (United States)

    Saeki, Shigeru

    2012-07-01

    The type, characteristics and effect of low reactive laser equipment used for pain treatment in Japan are described in this section. Currently, low reactive laser therapy equipments marketed and used in Japan include diode laser therapeutic device with semiconductor as a medium consisting of aluminum, gallium and arsenic. Low reactive laser equipment comes in three models, the first type has a capacity of generating 1,000 mW output, and the second type has a capacity of generating 10 W output. The third type has four channels of output, 60, 100, 140 and 180 mW and we can select one channel out of the four channels. This model is also used as a portable device because of its light weight, and we can carry it to wards and to the outside of the hospital. Semiconductor laser has the capacity of deepest penetration and the effect tends to increase proportionally to the increasing output. Low reactive laser therapy is less invasive and lower incidence of complications. Although low reactive laser therapy might be effective for various pain disorders, the effect is different depending on the type of pain. We should keep in mind that this therapy will not give good pain relief equally in all patients with pain.

  15. Support or Barrier?

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    This study offers a critical look at how corporate-level language management influences front-line language practices among employees in three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data, we examine, firstly, what front-line practices emplo...... to a discussion of how a company’s language policy may be seen as both support and a barrier....

  16. Overcoming Language Barriers

    Science.gov (United States)

    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

  17. Barriers to obesity treatment.

    Science.gov (United States)

    Mauro, Marina; Taylor, Valerie; Wharton, Sean; Sharma, Arya M

    2008-05-01

    Obesity, one of the most prevalent health problems in the Western world, is a chronic and progressive condition. Therefore, as with other chronic diseases, patients with obesity require lifelong treatment. Long-term efficacy and effectiveness of obesity treatments is notoriously poor. This may in part be attributable to the substantial barriers that undermine long-term obesity management strategies. These can include lack of recognition of obesity as a chronic condition, low socioeconomic status, time constraints, intimate saboteurs, and a wide range of comorbidities including mental health, sleep, chronic pain, musculoskeletal, cardiovascular, respiratory, digestive and endocrine disorders. Furthermore, medications used to treat some of these disorders may further undermine weight-loss efforts. Lack of specific obesity training of health professionals, attitudes and beliefs as well as coverage and availability of obesity treatments can likewise pose important barriers. Health professionals need to take care to identify, acknowledge and address these barriers where possible to increase patient success as well as compliance and adherence with treatments. Failure to do so may further undermine the sense of failure, low self esteem and self efficacy already common among obese individuals. Addressing treatment barriers can save resources and increase the prospect of long-term success.

  18. Barrier Coatings for Refractory Metals and Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    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.

  19. Interactive chemical reactivity exploration.

    Science.gov (United States)

    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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Interactive Chemical Reactivity Exploration

    CERN Document Server

    Haag, Moritz P; Bosson, Mael; Redon, Stephane; Reiher, Markus

    2014-01-01

    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.

  1. Barrier mechanisms in the Drosophila blood-brain barrier

    OpenAIRE

    Samantha Jane Hindle; Roland Jerome Bainton

    2014-01-01

    The invertebrate blood-brain barrier field is growing at a rapid pace and, in recent years, studies have shown a physiologic and molecular complexity that has begun to rival its vertebrate counterpart. Novel mechanisms of paracellular barrier maintenance through GPCR signaling were the first demonstrations of the complex adaptive mechanisms of barrier physiology. Building upon this work, the integrity of the invertebrate blood-brain barrier has recently been shown to require coordinated funct...

  2. Geophysical characterization of subsurface barriers

    Energy Technology Data Exchange (ETDEWEB)

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier.

  3. Reactive Nanoengineered Coatings

    Science.gov (United States)

    2007-04-30

    membranes would not remove salt from seawater, they would remove viruses and other contaminants from drinking water at rates up to 1000 times those...by studies of the diffusion of chlorinated hydrocarbons across polyethylene films. The polyethylene is what is actually used as a barrier for landfills

  4. Los valores distintivos de los panistas

    Directory of Open Access Journals (Sweden)

    Iván Zavala Echavarría

    2009-01-01

    Full Text Available En este artículo, el autor se propone demostrar que el hecho de ser simpatizante del partido Acción Nacional (pan es función de seis variables independientes: inculcar la fe, confiar en otros, interés en la política y auto-ubicación sobre los ejes izquierda-derecha, igualdad>desigualdad, y propiedad privada>gubernamental. La influencia de esas variables no es sólo aislada sino en conjunto. Estas variables son distintivas de los simpatizantes del Partido (de Acción Nacional, es decir los distinguen de los del Partido Revolucionario Institucional y de los del Partido de la Revolución Democrática.

  5. De los deslumbramientos a los alumbramientos

    Directory of Open Access Journals (Sweden)

    William Fernando Torres

    1996-10-01

    Full Text Available Este texto es un relato sobre las ansiedades que hoy abruman en secreto a los profesores de la escuela básica periférica. Sin embargo, no se queda en la anécdota: evidencia que esas inquietudes tienen raíz en las dificultades de los docentes para apropiarse críticamente las culturas escritas y audiovisuales/digitales electrónicas y, por tanto, para construirse una comprensión global de los procesos culturales contemporáneos. Estas circunstancias llevan a los maestros a incomunicarse y a entrar en conflicto con las y los jóvenes. Como alternativas posibles se propone autorreconocerse, aprender a crecer siendo vulnerables, engendrar un pensamiento del contexto y lo complejo.

  6. Reactive Turing machines

    NARCIS (Netherlands)

    Baeten, J.C.M.; Luttik, B.; Tilburg, P.J.A. van

    2013-01-01

    We propose reactive Turing machines (RTMs), extending classical Turing machines with a process-theoretical notion of interaction, and use it to define a notion of executable transition system. We show that every computable transition system with a bounded branching degree is simulated modulo diverge

  7. A Universal Reactive Machine

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif; Mørk, Simon; Sørensen, Morten U.

    1997-01-01

    Turing showed the existence of a model universal for the set of Turing machines in the sense that given an encoding of any Turing machine asinput the universal Turing machine simulates it. We introduce the concept of universality for reactive systems and construct a CCS processuniversal...

  8. Spring 5 & reactive streams

    CERN Document Server

    CERN. Geneva; Clozel, Brian

    2017-01-01

    Spring is a framework widely used by the world-wide Java community, and it is also extensively used at CERN. The accelerator control system is constituted of 10 million lines of Java code, spread across more than 1000 projects (jars) developed by 160 software engineers. Around half of this (all server-side Java code) is based on the Spring framework. Warning: the speakers will assume that people attending the seminar are familiar with Java and Spring’s basic concepts. Spring 5.0 and Spring Boot 2.0 updates (45 min) This talk will cover the big ticket items in the 5.0 release of Spring (including Kotlin support, @Nullable and JDK9) and provide an update on Spring Boot 2.0, which is scheduled for the end of the year. Reactive Spring (1h) Spring Framework 5.0 has been released - and it now supports reactive applications in the Spring ecosystem. During this presentation, we'll talk about the reactive foundations of Spring Framework with the Reactor project and the reactive streams specification. We'll al...

  9. Clojure reactive programming

    CERN Document Server

    Borges, Leonardo

    2015-01-01

    If you are a Clojure developer who is interested in using Reactive Programming to build asynchronous and concurrent applications, this book is for you. Knowledge of Clojure and Leiningen is required. Basic understanding of ClojureScript will be helpful for the web chapters, although it is not strictly necessary.

  10. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    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).

  11. Effect of five acetylcholinesterase reactivators on tabun-intoxicated rats: induction of oxidative stress versus reactivation efficacy.

    Science.gov (United States)

    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.

  12. Vacuum barrier for excimer lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, R.P.

    1990-10-10

    This invention is comprised of 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 yearns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

  13. [The cultural barrier in care].

    Science.gov (United States)

    Djadaoudjee, Lisa

    2013-11-01

    French cultural diversity is evident within French hospitals, where nurses are confronted with communication problems resulting from the language barrier. While communication is indeed essential, there is another important aspect of caring for a patient for behind the language barrier lies a cultural barrier which must be taken into account in order to provide high-quality care.

  14. Thermal barrier coating materials

    Directory of Open Access Journals (Sweden)

    David R. Clarke

    2005-06-01

    Full Text Available Improved thermal barrier coatings (TBCs will enable future gas turbines to operate at higher gas temperatures. Considerable effort is being invested, therefore, in identifying new materials with even better performance than the current industry standard, yttria-stabilized zirconia (YSZ. We review recent progress and suggest that an integrated strategy of experiment, intuitive arguments based on crystallography, and simulation may lead most rapidly to the development of new TBC materials.

  15. Quistes de los maxilares

    OpenAIRE

    Ivan Alberto Manotas Arevalo

    2013-01-01

    Los Grandes Quistes de los Maxilares han estado vinculados siempre a la humanidad, desde tiempos remotos, pues han sido halladas en restos de especimenes fosiles, han llamado la atencion de los clínicos, en torno a su etiologia, en la que se ha introducido la participacion de la genetica, (demostrada en el desarrollo de los queratoquistes maxilares), la fisiopatologia, caracteristicas histologicas (inmunohistoquimica), posibilidades diagnosticas por la imagen, (como la tomografia computarizad...

  16. Long term performance of the Waterloo denitrification barrier

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, W.D.; Cherry, J.A. [Univ. of Waterloo, Ontario (Canada)

    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.

  17. Intrinsic barriers for H-atom transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Camaioni, D.M.; Autrey, S.T.; Franz, J.A.

    1994-08-01

    Hydrogen transfer reactions play a well-recognized role in coal liquefaction. While H-abstraction reactions between radicals and H-donors have been well-studied, understanding of structure-reactivity relationships remains surprisingly incomplete. Another form of hydrogen transfer known as radical hydrogen transfer (radical donation of H to an unsaturated compound) is currently the subject of much speculation. The barriers for identity reactions are key parameters in the Evans-Polanyi equation for estimating reaction barriers and are fundamentally significant for the insight they provide about bond reorganization energies for formation of transition state structures. Although knowable from experiment, relatively few H-abstraction identity barriers and no barriers for hydrocarbon radical hydrogen transfer reactions have been measured. This paper seeks to supplement and extend existing experimental data with results obtained by calculation. The authors have used ab initio and semiempirical molecular orbital methods (MNDO-PM3) to calculate barriers for a series of H-atom abstraction and radical-hydrogen-transfer identity reactions for alkyl, alkenyl, arylalkyl and hydroaryl systems. Details of this methodology and analyses of how barrier heights correlate with reactant and transition state properties will be presented and discussed.

  18. Engineered barriers for radioactive waste confinement

    Directory of Open Access Journals (Sweden)

    Fernández, R.

    2011-09-01

    Full Text Available Nuclear power plants generate long-lived radioactive waste of high toxicity. The security assessment of repositories destined to definitive confinement of radioactive waste has been studied for several decades. Deep geological repositories are technically feasible and begin to be built by some pioneer countries. The scientific evaluation of interactions between the different engineered barriers is studied by laboratory experiments, natural analogues and modeling studies. The three methods are able to represent and validate the main geochemical processes that take place in the near field. This paper reviews the scientific and technical basis of the concept of geological disposal, with particular focus on the methods of study applied to the evaluation of geochemical stability of the bentonite barrier.

    Las centrales nucleares generan residuos radiactivos de elevada peligrosidad y permanencia en el tiempo. La evaluación de la seguridad de repositorios destinados al alojamiento definitivo de estos residuos lleva estudiándose desde hace varias décadas. El almacenamiento geológico es técnicamente factible y empieza ya a desarrollarse en países pioneros. La evaluación científica de las interacciones entre las distintas barreras de ingeniería se estudia mediante ensayos de laboratorio, análisis de análogos naturales y modelos teóricos. Las tres vías de estudio son capaces de representar y validar los principales procesos geoquímicos que tienen lugar en el campo cercano al repositorio. Este artículo revisa los fundamentos científicos y técnicos del concepto de almacenamiento geológico detallando, en particular, los métodos de estudio aplicados a la evaluación de la estabilidad geoquímica de la barrera de bentonita.

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

    Science.gov (United States)

    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

  20. Los presupuestos del Concurso

    OpenAIRE

    Línea de Investigación “De la Crisis Empresarial

    2006-01-01

    Este escrito es el resultado de uno de los proyectos de investigación adelantados por el Departamento de Derecho Comercial de la Universidad Externado de Colombia. En el se hace una aproximación histórica a los presupuestos para acceder a los trámites concursales en Perú, Argentina y España, analizándolos desde los puntos doctrinal, académico y legal.Así mismo, es parte integrante de un trabajo más amplio que pretende elaborar un documento contentivo del tratamiento que se da a los presupuest...

  1. Reactive Air Aluminization

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Barrier mechanisms in the Drosophila blood-brain barrier

    Directory of Open Access Journals (Sweden)

    Samantha Jane Hindle

    2014-12-01

    Full Text Available The invertebrate blood-brain barrier field is growing at a rapid pace and, in recent years, studies have shown a physiologic and molecular complexity that has begun to rival its vertebrate counterpart. Novel mechanisms of paracellular barrier maintenance through GPCR signaling were the first demonstrations of the complex adaptive mechanisms of barrier physiology. Building upon this work, the integrity of the invertebrate blood-brain barrier has recently been shown to require coordinated function of all layers of the compound barrier structure, analogous to signaling between the layers of the vertebrate neurovascular unit. These findings strengthen the notion that many blood-brain barrier mechanisms are conserved between vertebrates and invertebrates, and suggest that novel findings in invertebrate model organisms will have a significant impact on the understanding of vertebrate BBB functions. In this vein, important roles in coordinating localized and systemic signaling to dictate organism development and growth are beginning to show how the blood-brain barrier can govern whole animal physiologies. This includes novel functions of blood-brain barrier gap junctions in orchestrating synchronized neuroblast proliferation, and of blood-brain barrier secreted antagonists of insulin receptor signaling. These advancements and others are pushing the field forward in exciting new directions. In this review, we provide a synopsis of invertebrate blood-brain barrier anatomy and physiology, with a focus on insights from the past 5 years, and highlight important areas for future study.

  3. Los nenes con los zombies, las nenas con los vampiros

    OpenAIRE

    López Corral, Manuela

    2012-01-01

    En este artículo nos circunscribiremos, dentro de este género literario, a las sagas de reciente salida editorial y, con mayor precisión, a las sagas de novelas románticas para adolescentes tales como Crepúsculo (Stephenie Meyer, 2005), Hush Hush (Becca Fitzpatrick, 2009), Cazadores de Sombras (Cassandra Clare, 2007), Fallen (Lauren Kate, 2010), y otras similares, dejando de lado sagas con otro tipo de particularidades como los citados libros de Harry Potter o los pertenecientes a la trilogía...

  4. Los nenes con los zombies, las nenas con los vampiros

    OpenAIRE

    López Corral, Manuela

    2012-01-01

    En este artículo nos circunscribiremos, dentro de este género literario, a las sagas de reciente salida editorial y, con mayor precisión, a las sagas de novelas románticas para adolescentes tales como Crepúsculo (Stephenie Meyer, 2005), Hush Hush (Becca Fitzpatrick, 2009), Cazadores de Sombras (Cassandra Clare, 2007), Fallen (Lauren Kate, 2010), y otras similares, dejando de lado sagas con otro tipo de particularidades como los citados libros de Harry Potter o los pertenecientes a la trilogía...

  5. Reactividad Química de los Azo Colorantes Amarillo Anaranjado y Rojo Allura mediante Descriptores Globales y la Función de Fukui Chemical Reactivity of the Azo dyes Sunset Yellow and Allura Red by Global Descriptors and the Fukui Function

    OpenAIRE

    Ensuncho,Adolfo E.; Jesús M López; Juana Robles

    2012-01-01

    Se calcularon descriptores globales y locales de la reactividad para los colorantes amarillo anaranjado y rojo allura con el fin de analizar su reactividad química intrínseca. Los cálculos computacionales se llevaron a cabo tanto en vacio como en la fase acuosa, la cual se representó por medio de una constante dieléctrica de 78.5 e introducida por el modelo de solvente del continuo polarizado. Los resultados mostraron que el colorante rojo allura es menos susceptible a la adición nucleofílica...

  6. Theoretical investigations of the reactivities of four-membered N-heterocyclic carbene analogues of the group 13 elements.

    Science.gov (United States)

    Wu, Chi-Shiun; Su, Ming-Der

    2012-01-05

    The potential energy surfaces for the chemical reactions of four-membered N-heterocyclic group 13 heavy carbeneoid species have been studied using density functional theory (Becke, 3-parameter, Lee-Yang-Parr (B3LYP)/Los Alamos National Laboratory 2-Double-Zeta (LANL2DZ)). Five four-membered group 13 heavy carbeneoid species, iPr2NC(NAr)2E:, where E ¼ B, Al, Ga, In, and Tl, have been chosen as model reactants in this work. Also, three kinds of chemical reactions, CAH bond insertion, alkene cycloaddition, and dimerization, have been used to study the chemical reactivities of these group 13 fourmembered N-heterocyclic carbeneoid species. In principle, our present theoretical work predicts that the larger the ffNEN bond angle of the four-membered group 13 iPr2NC(NAr)2E: species, the smaller the singlet–triplet splitting, the lower the activation barrier, and, in turn, the more rapid its chemical reactions to various chemical species. Moreover, our theoretical investigations suggest that the relative carbenic reactivity decreases in the following order: B > Al > Ga > In > Tl. That is, the heavier the group 13 atom (E), the more stable its fourmembered carbeneoid toward chemical reactions is. As a result, our computations predict that the four-membered heavy group 13 iPr2NC(NAr)2E: species (E ¼ Al, Ga, In, and Tl) should be both kinetically and thermodynamically stable, and can be readily synthesized and isolated at room temperature. Furthermore, the singlet–triplet energy splitting of the four-membered group 13 iPr2NC(NAr)2E: species, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict their reactivities. The results obtained allow a number of predictions to be made. 2011 Wiley Periodicals, Inc.

  7. Reactive Transport Modeling and Changes in Porosity at Reactive Interfaces in a HLW repository in Clay

    Science.gov (United States)

    Samper, J.; Mon, A.; Montenegro, L.; Naves, A.; Fernández, J.

    2016-12-01

    High-level radioactive waste disposal in a deep geological repository is based on a multibarrier concept which combines natural barriers such as the geological formation and artificial barriers such as metallic containers, bentonite and concrete buffers and sealing materials. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyperalkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyperalkaline plume at the concrete-clay interface. Here we present a nonisothermal reactive transport model of the long-term interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. This problem involves large pH changes with a hyperalkaline high-pH plume, complex mineral dissolution/precipitation patterns, cation exchange reactions and proton surface complexation. These reactions lead to large changes in porosity which can even lead to pore clogging. Model results show that magnetite, the main corrosion product, precipitates and reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The zones affected by pore clogging at the canister-bentonite, bentonite-concrete and concrete-clay interfaces at 1 Ma are equal to 10, 25 and 25 mm thick, respectively. The results of our simulations share many of the features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Narrow alteration zones; and 2) Pore clogging at the canister-bentonite, bentonite-concrete and concrete

  8. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst...

  9. [Barrier methods of contraception].

    Science.gov (United States)

    Goldsmith, A; Edelman, D A

    1982-01-01

    Vaginal methods of contraception were the earliest types used and some references to them date back to antiquity. Most of the vaginal contraceptive agents identified by the ancient Greeks, Indians, Japanese, and Chinese have been found in modern laboratory tests to have spermicidal properties, but it is doubtful that the methods were fully reliable or were used by many people. During the 19th century the condom, vaginal spermicides, and diaphragm became available. The development of nonoxynol-9 and other nonirritating but effective spermicidal agents improved vaginal contraceptives greatly by the 1950s, but starting in the 1960s newer methods began to replace the vaginal methods. Interest in barrier methods has been reawakened somewhat by concern about the health effects of hormonal methods. At present all barrier methods leave something to be desired. Failure rates of 3-30% for barrier methods in general have been estimated, but the higher rates are believed due to incorrect or inconsistent use. Theoretical failure rates of condoms and diaphragms have been estimated at 3/100 women-years, but in actual use failure rates may reach 15 for condoms and 13 for diaphragms used with spermicides. Use-effectiveness rates are greatly influenced by motivation. For a variety of reasons, the acceptability of barrier methods is low, especially in developing countries. New developments in spermicidal agents include sperm inhibitors, which impede the fertilizing capacity of sperm rather than attempting a spermicidal effect; a number of such agents have been studied and have proven more effective in animal tests than conventional spermicides. Neosampoon, a new spermicidal foam, has attracted an increasing number of users, especially in developing countries. A new condom, made of thin polymers and containing a standard dose of nonoxynol-9, has been designed to dissolve in the vaginal fluid. Further studies are needed of its acceptability, efficacy, and side effects before it becomes

  10. Technical barrier challenges

    Institute of Scientific and Technical Information of China (English)

    李思佳

    2014-01-01

    according to a famouse report,the foreign Technical Barriers to Trade(TBT)have some effects on the exports of the People’s Republic of China.Major findings are as follows:(1)TBT makes it more difficult for China to export;(2)TBT increases the costs of Chinese export commodities;(3)TBT causes friction and confilicts in the international trade;(4)SOME developed countries have moved their phase-outs to China and other developing countries,which have become victims of TBT.

  11. Support or Barrier?

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    This study offers a critical look at how corporate-level language management influences front-line language practices among employees in three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data, we examine, firstly, what front-line practices...... employees use to cross language boundaries in their everyday work, and, secondly, how these practices relate to top-down language management in the case companies. Our findings show that employees are often dependent on ad hoc and informal solutions in cross- language situations, which leads us...... to a discussion of how a company’s language policy may be seen as both support and a barrier....

  12. Optimum Barrier Height for SiC Schottky Barrier Diode

    OpenAIRE

    Mohamed Abd El-Latif; Alaa El-Din Sayed Hafez

    2013-01-01

    The study of barrier height control and optimization for Schottky barrier diode (SBD) from its physical parameters have been introduced using particle swarm optimization (PSO) algorithm. SBD is the rectifying barrier for electrical conduction across the metal semiconductor (MS) junction and, therefore, is of vital importance to the successful operation of any semiconductor device. 4H-SiC is used as a semiconductor material for its good electrical characteristics with high-power semiconductor ...

  13. Nanomedicine Faces Barriers

    Directory of Open Access Journals (Sweden)

    Paul Debbage

    2010-10-01

    Full Text Available 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?

  14. Higgs vacua behind barriers

    CERN Document Server

    Tamarit, Carlos

    2014-01-01

    Scenarios in which the Higgs vacuum arises radiatively and separated from the origin by a potential barrier at zero temperature are known to be attainable in models with extra singlet scalars, which in the limit of zero barrier height give rise to Coleman-Weinberg realizations of electroweak symmetry breaking. However, this requires large values of Higgs-portal couplings or a large number N of singlets. This is quantified in detail by considering, for varying N, the full two-loop effective potential at zero temperature, as well as finite temperature effects including the dominant two-loop corrections due to the singlets. Despite the large couplings, two-loop effects near the electroweak scale are under control, and actually better behaved in models with larger couplings yet fewer singlets. Strong first-order phase transitions are guaranteed even in the Coleman-Weinberg scenarios. Cubic Higgs couplings and Higgs associated-production cross sections exhibit deviations from the Standard Model predictions which c...

  15. Stability of barrier buckets with zero RF-barrier separations

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Programming Reactive Extensions and LINQ

    CERN Document Server

    Liberty, Jesse

    2011-01-01

    Pro Reactive Extensions and LINQ is a deep dive into the next important technology for .NET developers: Reactive Extensions. This in-depth tutorial goes beyond what is available anywhere else to teach how to write WPF, Silverlight, and Windows Phone applications using the Reactive Extensions (Rx) to handle events and asynchronous method calls. Reactive programming allows you to turn those aspects of your code that are currently imperative into something much more event-driven and flexible. For this reason, it's sometimes referred to as LINQ for Events. Reactive programming hinges on the concep

  17. Performance of PRD Welled Surfaces in T Shape Noise Barriers for Controlling Environmental Noise

    Directory of Open Access Journals (Sweden)

    S Momen Bellah

    2010-07-01

    Full Text Available "n "n "nBackgrounds and Objectives: There is a considerable notice in the use of noise barriers in recent years. Noise barriers as a control noise solution can increase the insertion loss to protect receivers. This paper presents the results of an investigation about the acoustic efficiency of primitive root sequence diffuser (PRD on environmental single T-shape barrier."nMaterials and Methods: A 2D boundary element method (BEM is used to predict the insertion loss of the tested barriers. The results of rigid and with quadratic residue diffuser (QRD coverage are also predicted for comparison."nResults: It is found that decreasing the design frequency of PRD shifts the frequency effects towards lower frequencies, and therefore the overall A-weighted insertion loss is improved. It is also found that using wire mesh with reasonably efficient resistivity on the top surface of PRD improves the efficiency of the reactive barriers; however utilizing wire meshes with flow resistivity higher than specific acoustic impedance of air on the PRD top of a diffuser barrier significantly reduces the performance of the barrier within the frequency bandwidth of the diffuser. The performance of PRD covered T-shape barrier at 200 Hz was found to be higher than that of its equivalent QRD barriers in both the far field and areas close to the ground. The amount of improvement compared made by PRD barrier compared with its equivalent rigid barrier at far field is about 2 to 3 dB, while this improvement relative to barrier model .QR4. can reach up to 4- 6 dB."nConclusion: Employing PRD on the top surface of T-shape barrier is found to improve the performance of barriers compared with using rigid and QRD coverage at the examined receiver locations.

  18. Los viajes de los europeos al extranjero

    Directory of Open Access Journals (Sweden)

    Juan Manuel López Sevillano

    2001-01-01

    Full Text Available En este capítulo se incluyen las últimas mediciones acerca de los viajes y vacaciones que efectuaron los europeos al extranjero entre 1995 y 1997. Comentaremos algunas cuestiones de este estudio que refleja un volumen total de 250 millones de viajes en 1995 y de 270 millones de viajes en 1997, lo que supone un aumento del 7% en dos años, cifras que continúan en aumento, aunque la mayoría de los viajeros europeos que efectúan más viajes pertenecen a países desarrollados de la Unión Europea y en menor medida a los países del Este. Entre las preferencias europeas esta el viajar por Europa, ocupando el primer lugar España (que en estas fechas se consolidó como el país más visitado de Europa y en segundo lugar Francia, además de otros países de la Europa Mediterránea como lugares preferidos por los europeos

  19. Los presupuestos del Concurso

    Directory of Open Access Journals (Sweden)

    Línea de Investigación “De la Crisis Empresarial

    2006-01-01

    Full Text Available Este escrito es el resultado de uno de los proyectos de investigación adelantados por el Departamento de Derecho Comercial de la Universidad Externado de Colombia. En el se hace una aproximación histórica a los presupuestos para acceder a los trámites concursales en Perú, Argentina y España, analizándolos desde los puntos doctrinal, académico y legal.Así mismo, es parte integrante de un trabajo más amplio que pretende elaborar un documento contentivo del tratamiento que se da a los presupuestos concursales a nivel mundial.En este orden de ideas, nos permitimos presentar un análisis minucioso de la legislación de los citados países iberoamericanos.

  20. Los presupuestos del Concurso

    Directory of Open Access Journals (Sweden)

    Línea de Investigación “De la Crisis Empresarial

    2006-12-01

    Full Text Available Este escrito es el resultado de uno de los proyectos de investigación adelantados por el Departamento de Derecho Comercial de la Universidad Externado de Colombia. En el se hace una aproximación histórica a los presupuestos para acceder a los trámites concursales en Perú, Argentina y España, analizándolos desde los puntos doctrinal, académico y legal.Así mismo, es parte integrante de un trabajo más amplio que pretende elaborar un documento contentivo del tratamiento que se da a los presupuestos concursales a nivel mundial. En este orden de ideas, nos permitimos presentar un análisis minucioso de la legislación de los citados países iberoamericanos.

  1. cultural de los chicanos

    Directory of Open Access Journals (Sweden)

    Patricia Casasa

    2003-01-01

    Full Text Available En Estados Unidos los diferentes grupos étnicos de habla hispana, entre ellos los chicanos, se enfrentan al problema de definir su identidad frente a la cultura anglosajona dominante, y este proceso puede ser descrito como un fenómeno de autoreconocimiento colectivo, o sea, la percepción diferencial de una colectividad suficientemente integrada y consistente, en contraposición con otras. Cualquier elemento que integra una configuración cultural, como son las pautas de comportamiento, los estilos de vida, las fiestas, los cantos, los mitos, los usos del ceremonial laico y religioso, la organización social del espacio, el lenguaje, la vida cotidiana o la utilización y percepción del medio físico, etcétera, pueden desempeñar este papel.

  2. Nonquaternary Cholinesterase Reactivators.

    Science.gov (United States)

    2014-09-26

    C2H5O(e)P(O)OX + H20 - products (15) K BOX __a__ OX + H+ (16) Equations (7) and (8) show the reaction of enzyme (EOH) with EPMP to yield ethyl ...kinetics. The reactivation of ethyl methylphosphonyl-AChE proceeds via the mechanism shown in equation (14): K rr OX + EOP [OX°EOP] - EOP + products (14... ether eluant. The crude product was dissolved in a minimal amount of ether and placed on a silica-gel column. Fractions of 40 mL were collected and

  3. Los cardinales romanos

    OpenAIRE

    Segura Ramos, Bartolomé

    2005-01-01

    Tratamos en el presente trabajo de estudiar los números cardinales romanos desde el punto de vista de su simbología (el origen de la misma), así como los principios subyacentes a dichos símbolos y la «mecánica» del sistema decimal romano (de proveniencia i.e.), a saber, el origen de los nombres de los números y el procedimiento de constitución de las decenas, especialmente. We are in this paper concerned with the study of the Roman cardinal numerals as symbolic signs, its origin and subjac...

  4. en los nuevos medios

    Directory of Open Access Journals (Sweden)

    Jaime Alonso

    2005-01-01

    Full Text Available El presente artículo se plantea como objetivo mostrar algunas consideraciones acerca de una investigación realizada durante los años 2000-2004 sobre los procesos de comunicación en Internet, que se centró en el análisis de los “nuevos medios”: diarios digitales, buscadores y directorios, portales, comunidades virtuales, redes ciudadanas y bitácoras. La investigación desplegó una metodología fundamentalmente exploratoria, debido a la ausencia de investigaciones de carácter general sobre la cuestión –dada la novedad que implica Internet– , y se basó en el análisis de varios parámetros: análisis de los objetivos de los medios, contenidos (tipologías y sujetos (actividades de los sujetos en los medios. En este artículo se comentan, exclusivamente, algunas ideas referidas a este tercer parámetro: la actividad de los sujetos en los nuevos medios.

  5. Silicon Carbide Schottky Barrier Diode

    Science.gov (United States)

    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.

  6. Translating barriers into potential improvements

    DEFF Research Database (Denmark)

    Altintzoglou, Themistoklis; Hansen, Karina Birch; Valsdottir, Thora

    2010-01-01

    Purpose: The aim of this study is to explore potential barriers to seafood consumption by The aim of this study is to explore potential barriers to seafood consumption by young adults and the parents of young children. Knowledge of these barriers will be used to assist the development of new...... to lead to practical input The present study combines qualitative methods to lead to practical input for NPD focusing on overcoming the barriers that keep consumers from choosing existing healthy seafood products. The importance of the consumers' confidence in their ability to successfully prepare...

  7. Los niños y los videojuegos

    OpenAIRE

    Orrego Gaviria, Jaime; Fundación Valle de Lili

    2007-01-01

    Los niños y los videojuegos / Efectos perjudiciales de la utilización de los videojuegos por los niños y adolescentes/ Efectos benéficos de la de la utilización de los videojuegos por los niños y adolescentes/ Recomendaciones para favorecer el uso adecuado/ Sistema de clasificación de los videojuegos

  8. Geohydrology model of the geothermal reservoirs at Los Humeros, Puebla, Mexico; Modelo hidrogeologico de los yacimientos geotermicos de los Humeros, Puebla, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Cedillo Rodriguez, Fidel [Comision Federal de Electricidad, Perote, Veracruz (Mexico)

    1999-12-01

    the regional lateral water recharge. On the other hand, the circular faults of the collapsed calderas of Los Humeros and Los Petreros form impermeable barriers to lateral water flow. Geothermal reservoir recharge only occurs inside the collapsed Los Humeros caldera. [Spanish] Los estudios de petrologia de agua y gases, e ingenieria de yacimientos de los pozos geotermicos, indican la existencia de dos yacimientos geotermicos. Las correlaciones petrograficas estructurales y el estado de las tuberias de produccion de los pozos geotermicos reparados, desviados y no invertidos, confirma la presencia de dos yacimientos, uno superior no agresivo con pH neutro y fluido bicarbonatado-sodico alojado en andesitas de augita; el otro, inferior, de alta temperatura y pH acido, contenido en andesitas de hornblenda y basaltos con fluidos clorurados-sodicos, ambos separados por un horizonte de tobas vitreas. Las grandes elevaciones de los niveles potenciometricos de los pozos geotermicos impide inferir la direccion de flujo de los fluidos geotermicos profundos. Los resultados litologicos y piezometricos de los pozos geothermohidrologicos perforados dentro de la caldera de Los Humeros, tambien muestra la existencia de dos acuiferos superficiales, uno relativamente frio y otro caliente. Debido a las grandes distancias entre estos pozos, y al medio geologico en que se encuentran, tampoco en ellos es posible inferir la direccion de flujo. Los estudios regionales de hidrogeologia, geofisica, hidrogeoquimica y geologico- estructurales, permiten afirmar que los acuiferos (frio y caliente) no tienen comunicacion hidraulica, ni relacion geoquimica o geologica con los pozos, norias y manantiales de los alrededores de la region de Los Humeros. Por consiguiente, la recarga de los acuiferos frio y caliente ocurre dentro de la cuenca cerrada de la caldera de Los Humeros, delimitada por el parte aguas orografico. Estos acuiferos recargan a los yacimientos geotermicos a traves de fallas y fracturas

  9. Countermeasures and barriers

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Johannes [Oersted - DTU, Automation, Kgs. Lyngby (Denmark)

    2005-10-01

    In 1973 Haddon proposed ten strategies for reducing and avoiding damages based on a model of potential harmful energy transfer (Haddon, 1973). The strategies apply to a large variety of unwanted phenomena. Haddon's pioneering work on countermeasures has had a major influence on later thinking about safety. Considering its impact it is remarkable that the literature offers almost no discussions related to the theoretical foundations of Haddon's countermeasure strategies. The present report addresses a number of theoretical issues related to Haddon's countermeasure strategies, which are: 1) A reformulation and formalization of Haddon's countermeasure strategies. 2) An identification and description of some of the problems associated with the term 'barrier'. 3) Suggestions for a more precise terminology based on the causal structure of countermeasures. 4) Extending the scope of countermeasures to include sign-based countermeasures. (au)

  10. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst......The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... groups, the sociology of work needs to develop a better understanding of the way in which linguistic diversity influences the formation of social capital, i.e. resources such as the trust and reciprocity inherent in social relations in such workplaces. Drawing on theories about intergroup contact...

  11. Regeneración de los defectos periodontales intraóseos: combinación de membranas barrera y material de relleno: evidencia preclínica y clínica Regenerative procedure for intra-bony periodontal defects: Combination of barrier membrane and filling material, clinical and preclinical evidence

    OpenAIRE

    N Discepoli; X. Costa Berenguer; A. Bascones-Martínez

    2012-01-01

    La terapia periodontal regenerativa tiene como objetivo lo de restaurar los tejidos de soporte periodontal y debería resultar en la formación de nueva inserción conectiva y (nuevo cemento con nuevas fibras del ligamento periodontal insertada) y nuevo hueso. Evidencia histológica en modelos preclínicos ha demostrado regeneración después de tratamiento con membranas barreras, distintos tipos de material de relleno y una combinación de los dos. De todas formas, todavía no queda claro en qué exte...

  12. Los apoyos en los centros docentes

    OpenAIRE

    2008-01-01

    Se describen las funciones del maestro de pedagogía terapéutica y de audición y lenguaje y de los educadores en la normativa de la Comunidad Valenciana. maestro de pedagogía terapéutica, maestro de audición y lenguaje, educadores

  13. Los libros de los moriscos y los eruditos orientales

    Directory of Open Access Journals (Sweden)

    Rodríguez Mediano, Fernando

    2010-12-01

    Full Text Available The aim of this paper is to show how the Orientalist scholarship of Christian Arabs who had come to Spain from the Middle East (via Italy adressed the literature of the Moriscos, to examine how it was understood by such scholars and what they used it for. We show that these scholars, from among whom we have chosen the examples of Marcus Dobelius and Miguel Casiri, could not carry out their Orientalist work using the Arabic manuscripts of the El Escorial library without confronting the Morisco problem in the form of Morisco texts held in several collections confiscated by the Inquisition. The knowledge and activities of these Moriscos served to trace the broad outlines of an intellectual history of the Arabic language in Europe, in which Morisco activity was interppreted in relation to its linguistic and doctrinal variables. This was achieved by means of the construction of a scholarly discipline (Orientalism at a time of religious polemic between the Reformation and the Counter-Reformation, i.e. during the period of the development of religious dissidence and skepticism in early modern Europe.Pretendemos, en este trabajo, mostrar cómo la erudición orientalista de árabes cristianos venidos a España desde Oriente (a través de Italia se aproximó a la literatura de los moriscos, cómo la entendió y para qué la utilizó. Mostramos que estos eruditos, de entre los que elegimos los casos de Marcos Dobelio y Miguel Casiri, no pudieron realizar su trabajo orientalista, que se basa en una fuerte vinculación con los manuscritos árabes de la Biblioteca de El Escorial, sin evitar el problema morisco en forma de su producción escrita aparecida en diversos fondos requisados por la Inquisición. Sus saberes y su actividad sirven para trazar los contornos amplios de una historia intelectual de la lengua árabe en Europa, en la que el hecho morisco es interpretado en función de sus variables lingüsticas y doctrinales, a partir de la constitución de

  14. CONTRIBUTION OF QUADRATIC RESIDUE DIFFUSERS TO EFFICIENCY OF TILTED PROFILE PARALLEL HIGHWAY NOISE BARRIERS

    Directory of Open Access Journals (Sweden)

    M. R. Monazzam ، P. Nassiri

    2009-10-01

    Full Text Available This paper presents the results of an investigation on the acoustic performance of tilted profile parallel barriers with quadratic residue diffuser (QRD tops and faces. A 2D boundary element method (BEM is used to predict the barrier insertion loss. The results of rigid and with absorptive coverage are also calculated for comparisons. Using QRD on the top surface and faces of all tilted profile parallel barrier models introduced here is found to improve the efficiency of barriers compared with rigid equivalent parallel barrier at the examined receiver positions. Applying a QRD with frequency design of 400 Hz on 5 degrees tilted parallel barrier improves the overall performance of its equivalent rigid barrier by 1.8 dB(A. Increase in the treated surfaces with reactive elements shifts the effective performance toward lower frequencies. It is found that by tilting the barriers from 0 to 10 degrees in parallel set up, the degradation effects in parallel barriers is reduced but the absorption effect of fibrous materials and also diffusivity of the quadratic residue diffuser is reduced significantly. In this case all the designed barriers have better performance with 10 degrees tilting in parallel set up. The most economic traffic noise parallel barrier which produces significantly high performance, is achieved by covering the top surface of the barrier closed to the receiver by just a QRD with frequency design of 400 Hz and tilting angle of 10 degrees. The average A-weighted insertion loss in this barrier is predicted to be 16.3 dB (A.

  15. Los Alamos National Laboratory.

    Science.gov (United States)

    Hammel, Edward F., Jr.

    1982-01-01

    Current and post World War II scientific research at the Los Alamos National Laboratory (New Mexico) is discussed. The operation of the laboratory, the Los Alamos consultant program, and continuation education, and continuing education activities at the laboratory are also discussed. (JN)

  16. Los pasos cantados

    Directory of Open Access Journals (Sweden)

    Eduardo Carranza

    1969-03-01

    Full Text Available EL documento presenta los siguientes poemas: "Los pasos cantados"; "La patria es como una carta..."; "Preludio para un himno a la bandera de Colombia"; "El extranjero"; "Romanza con unas violetas"; "Nueva Kasida del vino"; "Día lejano"; "Decir amor"; "Hacia la soledad"; "El  capitan siembra una espada" y "El poeta canta desde lo alto de un caballo".

  17. los recursos culturales tangibles

    Directory of Open Access Journals (Sweden)

    Isabel Montero Muradas

    2005-01-01

    Full Text Available La formulación de estrategias de marketing de turismo cultural necesita una correcta evaluación de los recursos culturales tangibles disponibles para el soporte de las mismas. En esta investigación se desarrolla una metodología, basada en el Modelo de Rasch, para el diseño un instrumento de medida que nos permita jerarquizar, a partir de su nivel de disponibilidad, tanto los recursos culturales, como los municipios en que están ubicados. Los datos utilizados corresponden a los municipios de la Comunidad canaria registrados en la Guía de Recursos y Espacios Culturales de las Islas Canarias

  18. Informal export barriers and poverty

    OpenAIRE

    Porto, Guido G.

    2004-01-01

    The author investigates the poverty impacts of informal export barriers like transport costs, cumbersome customs practices, costly regulations, and bribes. He models these informal barriers as export taxes that distort the efficient allocation of resources. In low-income agricultural economies, this distortion lowers wages and household agricultural income, thereby leading to higher pover...

  19. Barriers to Women in Science

    Science.gov (United States)

    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…

  20. Barriers to Women in Science

    Science.gov (United States)

    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…

  1. BARRIERS OF STRATEGIC ALLIANCES ORGANIZATION

    Directory of Open Access Journals (Sweden)

    Vladislav M. Sannikov

    2014-01-01

    Full Text Available General barriers of organization of different types of strategic alliances have beenconsidered in the article. There are several recommendations for overcoming themin cases of international alliances, and in case of work in one state. The article also identified goals and tasks of single coordination center of alliance to overcome organization barriers.

  2. Spanning trees crossing few barriers

    NARCIS (Netherlands)

    Asano, T.; Berg, M. de; Cheong, O.; Guibas, L.J.; Snoeyink, J.; Tamaki, H.

    2002-01-01

    We consider the problem of finding low-cost spanning trees for sets of n points in the plane, where the cost of a spanning tree is defined as the total number of intersections of tree edges with a given set of m barriers. We obtain the following results: (i) if the barriers are possibly intersecting

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

    Science.gov (United States)

    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.

  4. A tutorial for understanding chemical reactivity through the valence bond approach.

    Science.gov (United States)

    Usharani, Dandamudi; Lai, Wenzhen; Li, Chunsen; Chen, Hui; Danovich, David; Shaik, Sason

    2014-07-21

    This is a tutorial on the usage of valence bond (VB) diagrams for understanding chemical reactivity in general, and hydrogen atom transfer (HAT) reactivity in particular. The tutorial instructs the reader how to construct the VB diagrams and how to estimate HAT barriers from raw data, starting with the simplest reaction H + H2 and going all the way to HAT in the enzyme cytochrome P450. Other reactions are treated as well, and some unifying principles are outlined. The tutorial projects the unity of reactivity treatments, following Coulson's dictum "give me insight, not numbers", albeit with its modern twist: giving numbers and insight.

  5. Epistemological barriers to radical behaviorism.

    Science.gov (United States)

    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.

  6. Epistemological barriers to radical behaviorism

    Science.gov (United States)

    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

  7. Familial reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Bhat Yasmeen

    2009-01-01

    Full Text Available Background: Reactive perforating collagenosis (RPC is one of the rare forms of transepidermal elimination in which genetically altered collagen is extruded from the epidermis. This disease usually starts in early childhood as asymptomatic umbilicated papules on extremities, and the lesions become more conspicuous with age. Aims: The objective of our study was to determine the clinico-pathological features of RPC and the response to various treatment modalities. Methods: Ten patients of RPC, belonging to five different families, were studied clinically. Various laboratory investigations were carried out and diagnosis was made by histopathology of the lesions. Patients were given various topical and oral treatments. Results: RPC is familial in most cases without any definite inheritance pattern. It begins in childhood and the lesions are usually recurrent and become profuse and large with age. Systemic diseases have no role in the onset of lesions. Conclusion: Oral and topical retinoids in combination with emollients is the best treatment option.

  8. Ecuador: el derrumbe de los partidos tradicionales

    Directory of Open Access Journals (Sweden)

    Juan Carlos Machado Puertas

    2007-01-01

    Full Text Available Este artículo hace una revisión de la coyuntura política, económica y social en Ecuador durante el 2006. Se pone especial énfasis en los resultados electorales que significaron el desplazamiento de los partidos tradicionales por fuerzas políticas emergentes y candidatos outsiders. Se subraya también el rol más reactivo que proactivo de un gobierno políticamente débil que finalmente se acomodó a su naturaleza de gobierno de transiciónThis article reviews the most salient political, economical and social events that took place in Ecuador during year 2006. It discusses in greater detail the presidential and legislative elections that resulted in the displacement of traditional parties by emerging ones and outsiders' candidacies. The article also highlights the reactive role assumed by a weak and transitional government

  9. Development of engineered barrier

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Kwan Sik; Cho, Won Jin; Lee, Jae Owan; Kim, Seung Soo; Kang, Mu Ja

    1999-03-01

    Engineered barrier development was carried out into the three research fields : waste form, disposal container, and buffer. The waste form field dealt with long-term leaching tests with borosilicate waste glasses surrounded by compacted bentonite. The leach rate decreased with increasing time, and was higher for the waste specimen rich in U and Na. In the container field, preliminary concepts of disposal containers were recommended by conducting structural analysis, thermal analysis, and shielding analysis, and major properties of stainless steel, copper, and titanium as a container material were surveyed. The sensitization degrees of SUS 316 and316L were lower than those of SUS 304 and 304L, respectively. The crevice corrosion of sensitized stainless steel was sensitive to the content of salt. Researches into the buffer included establishment of its performance criteria followed by investigating major properties of buffer using potential material in Korea. Experiments were made for measuring hydraulic conductivities, swelling properties, mechanical properties, thermal conductivities, pore-water chemistry properties, and adsorption properties was also investigated. (author)

  10. de los derechos humanos

    Directory of Open Access Journals (Sweden)

    Javier Pardo Falcón

    2007-01-01

    Full Text Available A pesar de su uso en determinados foros políticos con connotaciones claramente negativas, el término globalización tiene un significado neutro que también puede hacer referencia a fines de bondad indudable. Así, tanto la Declaración Universal de los Derechos Humanos como otros instrumentos internacionales aprobados por las Naciones Unidas son normas jurídicas globalizadoras, surgidas con la idea de extender la vigencia de los derechos básicos de la persona a todos los países del mundo. Desde esta otra visión de la globalización, conseguir la efectiva vigencia de los derechos humanos en los países de Centroamérica resulta una tarea particularmente urgente y necesaria. En efecto, salvo Costa Rica, que puede considerarse una afortunada excepción en la turbulenta historia política centroamericana, todos los demás Estados de la región comparten un pasado marcado por los graves conflictos internos y el escaso desarrollo económico, circunstancias ambas que explican en buena parte un presente caracterizado por la debilidad de las instituciones, la falta de cohesión social y, en consecuencia, la insuficiente garantía de los derechos más básicos de la mayoría de la población. En este contexto, y desde su compromiso con la mejora de las condiciones materiales de vida de sus conciudadanos menos favorecidos, seis autores y autoras centroamericanos abordan, desde distintas perspectivas, la situación actual de los derechos fundamentales en sus respectivos países.

  11. Remover los dogmas

    OpenAIRE

    Jaime Cárdenas Gracia

    2002-01-01

    El autor plantea una serie de reflexiones en torno a cinco temas a los que califica como dogmas de la teoría de la Constitución: el principio de legalidad, la división de poderes, el control de la constitucionalidad, el prevalecimiento del derecho interno sobre el externo y los métodos de interpretación. En su concepción, estos dogmas son barreras que desde la experiencia académica van incorporándose a los conceptos jurídicos, empobreciendo y reduciendo la realidad jurídica, al no tomar en cu...

  12. Instrucciones para los autores

    Directory of Open Access Journals (Sweden)

    Revista Facultad de Ingenieria

    2010-11-01

    Full Text Available REVISTA FACULTAD DE INGENIERÍA, publicación editada por el Centro de Estudios, nvestigación y Educación Continuada de la Facultad de Ingeniería (CEDEC de la Universidad Pedagógica y Tecnológica de Colombia, UPTC, busca contribuir a la difusión de los nuevos conocimientos científicos y tecnológicos que se producen en el campo de las ingenierías, como resultados de los procesos investigativos que llevan a cabo los docentes y estudiantes, principalmente, de esta Facultad.

  13. Capitulo uno. Los Mineros

    OpenAIRE

    Lavaud, Jean-Pierre

    2015-01-01

    Si existe un sector organizado cuya oposición recurrente ha preocupado a los gobernantes, ése es el de los mineros. La revisión de las huelgas y batallas de todo tipo en las que se han visto comprometidos, su fuerza de arrastre ante los demás sindicatos, su importancia en la COB es impresionante y constituye la evidencia de su poder. Y, si aun fuera necesaria una otra prueba de su vigor, se podría mencionar la inaudita capacidad de recuperación de sus sindicatos, después que las sangrientas r...

  14. Los calculistas mentales

    Directory of Open Access Journals (Sweden)

    Salvador Galindo Uribarri

    2014-01-01

    Full Text Available Los calculistas mentales, sujetos que realizan en un instante complejas operaciones aritméticas, han desarrollado habilidades que nos parecen -al resto de mortales- sorprendentes y aún increíbles. Estos sujetos se distinguen por su capacidad de concentración e increíble memoria y además emplean procedimientos de cálculo dis - tintos a los que ordinariamente ocupamos en nuestra vida cotidiana. Este trabajo trata sobre dichos procedimientos mostrando que difieren de los algoritmos tradicionales.

  15. Los quechuismos en Colombia

    Directory of Open Access Journals (Sweden)

    Víctor Sánchez Montenegro

    1962-06-01

    Full Text Available Como una pequeña introducción a este estudio, debo dar algunos datos sobre el descubrimiento del Perú y la historia de los "Trece de la Fama" que se relacionan íntimamente con nuestra Isla del Gallo, en las cercanías de Tumaco, asombroso episodio que, siendo verdadera historia, tiene todos los aspectos de la más extraordinaria leyenda de esa época superior a cualquier relación mítica de los Libros de Caballería.

  16. Rectores: los virreyes cautivos

    OpenAIRE

    2014-01-01

    Los rectores de las universidades españolas en la actualidad, particularmente los de las públicas, son una especia de virreyes, es decir, desempeñan un papel de administradores, pero no de creadores de auténticos objetivos para sus instituciones. Por eso la autonomía universitaria es hoy más un mecanismo de autogestión que de facilitamiento de estrategias concretas para cada universidad. Los rectores se convierten así, cautivos de un complejo e intrincado andamio legislativo. El papel del rec...

  17. Reactivity of water vapor in an atmospheric pressure DBD -Application to LDPE surfaces

    CERN Document Server

    Collette, S; Viville, Pascal; Reniers, François

    2016-01-01

    The reactivity of water vapor introduced in an atmospheric dielectric barrier discharge supplied in argon is investigated through optical emission spectroscopy measurements. This discharge is also used for the treatment of LDPE surfaces. Water contact angles measurements, XPS and AFM techniques are used to study the grafting of oxygen functions on the LDPE surface and increase its hydrophilicity.

  18. Tritium/hydrogen barrier development

    Energy Technology Data Exchange (ETDEWEB)

    Hollenberg, G.W.; Simonen, E.P. [Pacific Northwest Lab., Richland, WA (United States); Kalinen, G. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany). International Thermonuclear Experimental Reactor (ITER) Team; Terlain, A. [CEA Centre d`Etudes de Fontenay-aux-Roses, 92 (France). Service de la Corrosion, d`Electrochimie et Chimie des Fluides

    1994-06-01

    A review of hydrogen permeation barriers that can be applied to structural metals used in fusion power plants is presented. Both implanted and chemically available hydrogen isotopes must be controlled in fusion plants. The need for permeation barriers appears strongest in Li17-Pb blanket designs, although barriers also appear necessary for other blanket and coolant systems. Barriers that provide greater than a 1000 fold reduction in the permeation of structural metals are desired. In laboratory experiments, aluminide and titanium ceramic coatings provide permeation reduction factors, PRFS, from 1000 to over 100,000 with a wide range of scatter. The rate-controlling mechanism for hydrogen permeation through these barriers may be related to the number and type of defects in the barriers. Although these barriers appear robust and resistant to liquid metal corrosion, irradiation tests which simulate blanket environments result in very low PRFs in comparison to laboratory experiments, i.e., <150. It is anticipated from fundamental research activities that the REID enhancement of hydrogen diffusion in oxides may contribute to the lower permeation reduction factors during in-reactor experiments.

  19. Influencia del zinc administrado a pacientes críticos con nutrición parenteral sobre los niveles de zinc plasmático, proteína C reactiva, interleuquina-6 y receptor soluble de interleuquina-6 Influence of zinc administered by total parenteral nutrition on plasmatic zinc levels, on reactive C protein, on serum interleukin-6 and on serum interleukin-6 soluble receptor, in critical patients

    Directory of Open Access Journals (Sweden)

    A. M.ª Menéndez

    2009-06-01

    Full Text Available Objetivos: Estudiar, en pacientes críticos, la respuesta de los niveles de Zn en plasma (ZnPl, de IL-6 sérica, del IL-6sR y de la PCR en relación al Zn administrado en la NPT, para evitar la deficiencia o el exceso de Zn. Métodos: 17 pacientes que recibieron NPT, por pancreatitis aguda o luego de una cirugía abdominal mayor. Al inicio (To y a la finalización (Tf de la NPT (6 a 21 días se determinó en suero: IL-6 y IL-6 sR (ELISA; PCR (inmunoturbidimetría; ZnPl y Zn en NPT (Espectrometría de Absorción Atómica. Características físicas: edad, años (promedio ± DE y rangos: 60,6 ± 11,7 (37-77; BMI (kg/m²: 26,0 ± 3,4 (19,9-34,0. Resultados: Promedio ± DE (y rangos: aporte de Zn en la NPT: 6,1 ± 2,0 mg/día (2,8 a 10,8; parámetros bioquímicos, a To y Tf, respectivamente: Zn Pl (μg/dl: 104 ± 46 (35-177; 120 ± 55 (52-229; IL-6 (pg/mL 93 ± 74 (10-262; 117 ± 180 (7-761; IL6sR (pg/mL: 1012 ± 322 (589-1.855; 1.269 ± 451 (631-2.195; PCR (mg/L: 71 ± 63 (2-196; 65 ± 43 (0-137. Dos pacientes, que fallecieron, incrementaron más de 4 veces los niveles de IL6, mantuvieron altos niveles de IL-6sR, pero disminuyendo los de PCR, recibiendo 4,2 y 5,2 mg/d de Zn. El 60% de los pacientes con evolución clínica favorable presentó una disminución de los niveles de IL6. Conclusiones: en los pacientes críticos, con evolución favorable, dosis de Zn de 2,8 a 10,8 mg/d en la NPT no exacerbaron la respuesta inflamatoria, evaluada mediante los niveles de IL-6, IL6sR y PCR.Objectives: To study the interrelationship between serum Interleukin-6 (IL-6, serum Interleukin-6 soluble Receptor (IL-6 sR, C-Reactive Protein (C-RP, plasmatic Zinc levels (PlZn and their response in relation to Zn administered by TPN, in critical patients. Methods: 17 patients, receiving TPN as a consequence of acute pancreatitis (n = 4 or after a major abdominal surgery due to intestinal cancer (n = 7, intestinal fístula (n = 3, intestinal obstruction (n = 2 or

  20. Facilitadores e barreiras para a implementação e participação em projetos sociais que envolvem atividades esportivas: os casos dos projetos Vila na Escola e Esporte Ativo Facilitadores y barreras para la implementación y participación en proyectos sociales que involucren actividades deportivas: el caso de los proyectos Barrio en la Escuela y Deporte Activo Facilitators and barriers to the implementation and participation in social projects that involve sport activities: the case of Village School Program and of the Active Sport projects

    Directory of Open Access Journals (Sweden)

    Doralice Lange de Souza

    2012-09-01

    barrera es falta de seguridad camino de casa al local de actividades y viceversa. Los resultados de este estudio proporcionan apoyo para desarrollo de estos proyectos y otros similares.This paper presents the main facilitators and barriers for the implementation of two social projects and for the participation of children in them. The research was qualitative and data were collected through semi-structured interviews with children and their parents/guardians; professionals and volunteers of the projects. Some factors are sometimes facilitators or barriers to implementation: the presence or absence of qualified professionals and of support for their work, quantity and/or quality of partnerships; level of consistency in the work of the partners, quantity and quality of space and equipment available; level of involvement of the community and/or parents. The main facilitators for participation are: access to sport activities, socialization opportunities, and perception of the projects as saver than streets. The main barrier is lack of security in the passage to and from the projects. The results of this research can contribute to the improved of these and other similar projects.

  1. Reactive Programming of Cellular Automata

    OpenAIRE

    Boussinot, Frédéric

    2004-01-01

    Implementation of cellular automata using reactive programming gives a way to code cell behaviors in an abstract and modular way. Multiprocessing also becomes possible. The paper describes the implementation of cellular automata with the reactive programming language LOFT, a thread-based extension of C. Self replicating loops considered in artificial life are coded to show the interest of the approach.

  2. A LOOK AT CULTURAL BARRIERS

    Directory of Open Access Journals (Sweden)

    Carmen A. VRÂNCEANU

    2015-06-01

    Full Text Available Nowadays the global market allows each individual to work in foreign countries. This fact is a great opportunity for business development, but also puts into light the problem of cultural barriers. Ineffective cross-cultural communication and collaboration can harm employees, customers, and other stakeholders. A company with employees from different cultures must acknowledge and understand these barriers in order to overcome them and to obtain the desired performance. The present study aims to expose the cultural barriers encountered by foreigners in a multinational company from Romania.

  3. Barriers in Concurrent Separation Logic

    Science.gov (United States)

    Hobor, Aquinas; Gherghina, Cristian

    We develop and prove sound a concurrent separation logic for Pthreads-style barriers. Although Pthreads barriers are widely used in systems, and separation logic is widely used for verification, there has not been any effort to combine the two. Unlike locks and critical sections, Pthreads barriers enable simultaneous resource redistribution between multiple threads and are inherently stateful, leading to significant complications in the design of the logic and its soundness proof. We show how our logic can be applied to a specific example program in a modular way. Our proofs are machine-checked in Coq.

  4. A Tariff for Reactive Power

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Kirby, Brendan J [ORNL; Li, Fangxing [ORNL; Tufon, Christopher [Pacific Gas and Electric Company; Isemonger, Alan [California Independent System Operator

    2008-07-01

    Two kinds of power are required to operate an electric power system: real power, measured in watts, and reactive power, measured in volt-amperes reactive or VARs. Reactive power supply is one of a class of power system reliability services collectively known as ancillary services, and is essential for the reliable operation of the bulk power system. Reactive power flows when current leads or lags behind voltage. Typically, the current in a distribution system lags behind voltage because of inductive loads such as motors. Reactive power flow wastes energy and capacity and causes voltage droop. To correct lagging power flow, leading reactive power (current leading voltage) is supplied to bring the current into phase with voltage. When the current is in phase with voltage, there is a reduction in system losses, an increase in system capacity, and a rise in voltage. Reactive power can be supplied from either static or dynamic VAR sources. Static sources are typically transmission and distribution equipment, such as capacitors at substations, and their cost has historically been included in the revenue requirement of the transmission operator (TO), and recovered through cost-of-service rates. By contrast, dynamic sources are typically generators capable of producing variable levels of reactive power by automatically controlling the generator to regulate voltage. Transmission system devices such as synchronous condensers can also provide dynamic reactive power. A class of solid state devices (called flexible AC transmission system devices or FACTs) can provide dynamic reactive power. One specific device has the unfortunate name of static VAR compensator (SVC), where 'static' refers to the solid state nature of the device (it does not include rotating equipment) and not to the production of static reactive power. Dynamic sources at the distribution level, while more costly would be very useful in helping to regulate local voltage. Local voltage regulation would

  5. Los pactos parasociales

    Directory of Open Access Journals (Sweden)

    Lina Henao

    2013-12-01

    Full Text Available Los pactos parasociales son acuerdos celebrados al margen de la regulación societaria, entre los socios, entre estos y la sociedad, o con terceros, que constituyen una herramienta de uso frecuente en el desarrollo de las relaciones corporativas pese a la ausencia de una regulación legal integral, y que tienen por finalidad regular extremos no recogidos estatutariamente. Su validez, eficacia e incumplimiento estarán determinados en mayor medida por las normas de derecho civil y en menor proporción por el orden jurídico societario. El artículo desarrolla una presentación de la noción, notas características, naturaleza jurídica y las vicisitudes que subyacen en esta materia a la luz de los principales ordenamientos jurídicos de los sistemas de Civil Law y de Common Law.

  6. Sudafrica en los BRICS

    National Research Council Canada - National Science Library

    Harrison, Philip

    2014-01-01

    La membresia de Sudafrica en los BRICS ha generado controversia. Un gran numero de observadores han argumentado que este pais es demasiado pequeno en terminos de economia y poblacion para ser un miembro real de este grupo...

  7. Los beneficios del TLC

    Directory of Open Access Journals (Sweden)

    Martín Uribe Arbeláez

    2007-11-01

    Full Text Available El TLC usa-Colombia aumenta la protección de la propiedad intelectual por encima de la normatividad internacional plasmada en los Acuerdos adpic de la omc y en la Decisión 486 de 2000, de la Comunidad Andina de Naciones. Intensifica la llamada “apertura económica” consagrando un modelo exportador. El propósito de este ensayo es analizar lo que representa para el desarrollo económico y social, con énfasis en los dramáticos cambios que se introducen en el Régimen Común de Propiedad Industrial. El saqueo de la biodiversidad, “patentes a plantas o animales”, los enormes costos para la salud pública, la competitividad basada en las maquilas y la pauperización social, contradicen los sofismas que parecen evocar el realismo mágico como explicación de nuestra historia.

  8. Los estilos de gerencia

    Directory of Open Access Journals (Sweden)

    Jorge Noriega Santos

    1990-04-01

    Full Text Available RESUMEN Es fundamental para cada persona saber cómo  se puede manejar una organización y los resultados que puede obtener de su gestión. Existen diversas formas o estilos de gerencia que podemos utilizar para  el logro de los objetivos. En este artículo basado en la teoría de Robert  Blake y Jane Mounton conocida con el  nombre de “Malla Gerencial “se trata de exponer los diversos  estilos de gerencia  y los efectos que cada uno de ellos producen en nuestras empresas o instituciones

  9. Los pactos parasociales

    Directory of Open Access Journals (Sweden)

    Lina Henao

    2013-12-01

    Full Text Available Los pactos parasociales son acuerdos celebrados al margen de la regulación societaria, entre los socios, entre estos y la sociedad, o con terceros, que constituyen una herramienta de uso frecuente en el desarrollo de las relaciones corporativas pese a la ausencia de una regulación legal integral, y que tienen por finalidad regular extremos no recogidos estatutariamente. Su validez, eficacia e incumplimiento estarán determinados en mayor medida por las normas de derecho civil y en menor proporción por el orden jurídico societario. El artículo desarrolla una presentación de la noción, notas características, naturaleza jurídica y las vicisitudes que subyacen en esta materia a la luz de los principales ordenamientos jurídicos de los sistemas de Civil Law y de Common Law.

  10. Historia de los Medicamentos

    Directory of Open Access Journals (Sweden)

    Alfredo Jácome Roca

    2003-10-01

    Full Text Available

    Cómo evolucionaron los medicamentos

    La historia de los medicamentos hace parte del devenir del hombre y de la historia de la medicina.

    Desde siempre, el ser humano buscó una explicación a los fenómenos y una solución a sus males. El pensamiento mágico, más acentuado en las tribus y en las más antiguas civilizaciones, hizo importante el poder de los conjuros y la influencia de los dioses sobre las pócimas.

    Con algunas excepciones, hasta que Paracelso introdujo en terapéutica las sustancias inorgánicas, los medicamentos eran hierbas. Gobernantes estudiosos del tema (el Emperador Rojo -padre de la Herbología china- y Mitrìdates VI -inventor y consumidor consuetudinario de la famosa teriaca- vivieron obsesionados con el temor al envenenamiento. Tanto que el último, septuagenario y derrotado por sus antiguos aliados romanos, trató de envenenarse para acabar con su vida, mas no fue posible pues estaba inmunizado contra los tóxicos; tuvo que rogarle a un esclavo que atravesara su pecho con la espada. Dioscórides y Plinio el Viejo eran eruditos conocedores de la botánica; el primero escribió la “Materia Médica”, el segundo, la “Historia Natural”.

    La aparición de la medicina como oficio, en casos como los de Hipócrates y Galeno, estuvo rodeada de prestigio; pero en los más fue tarea de esclavos, labor de sirvientes. Estos colegas de la antigüedad aprendieron a manejar sus propios medicamentos, preparados en algunas trastiendas o “boticas”. Los farmacéuticos se iniciaron como simples dispensadores y tuvieron auge entre los árabes, civilización donde aparecieron también los primeros recetarios, listados de medicinas o primitivas farmacopeas. Pero siempre las mismas hierbas con los mismos hierbateros, para llamar de alguna manera a los empíricos que ejercían artesanalmente la medicina.

    Refiriéndose a las curas de su médico tratante, Adriano –considerado por aquel

  11. Los factores de riesgo

    Directory of Open Access Journals (Sweden)

    Justo Senado Dumoy

    1999-01-01

    Full Text Available Sobre el fundamento filosófico de los conceptos de la Dialéctica Materialista, se presenta un análisis en relación con el concepto e interpretación de los Factores de Riesgo.A analysis on the concept and interpretation of risk factors is presented based on the philosophical foundation of the concepts of materialist dialectics.

  12. Generalized Reactive Manufacturing System

    Institute of Scientific and Technical Information of China (English)

    李蓓智

    2001-01-01

    Generalized reactive manufacturing system named GRMS is introduced. GRMS is a human-centered system based on Multi-agent. Its management and control organization is made up of three types of agents named device agent,task agent and shop-floor agent. GRMS adopts a top down and bottom- up competition and cooperation strategy based on the dynamic sifter and funnel To constrain the behavior of agents, a reward and penaity policy is introduced into the system and the closed-loop adjustment of GRMS is realized through such policy.Agents for the same task should be cooperated with each other and agents for different tasks should compete for survival in the dynamic changing environment. A distributed-hierarchical architecture with three levels of master-slave relationships among agents are proposed.Self-propelled process planning is also discussed. In order to evaluate GRMS, a time-driven simulation system-GRMOSS is developed to check the physical consistency of GRMS.

  13. Estereotipos hacia los ancianos

    Directory of Open Access Journals (Sweden)

    Marta Gil Barreiro

    1997-02-01

    Full Text Available Se realizó un estudio descriptivo en 4 grupos etáreos diferentes: 20; 40; 60 y 70 años, del área de salud que abarca el Policlínico Docente "Lawton", con vistas a determinar cómo se estructuran los estereotipos hacia los ancianos. El instrumento de evaluación utilizado se confeccionó para la ocasión: la escala de adjetivos. El estereotipo más positivo hacia los ancianos lo evidenciaron los individuos de 40 años, a los que le siguieron, en orden decreciente, los de 70; 20 y 60 años.A descriptive study was a carried out in four different age groups: 20, 40, 60, and 70 years old, in the health area belonging to the "Lawton" Teaching Policlinic, in order to determine how the stereotypes towards the older people are formulated. The adjective scale was the assessing instrument built for the ocassion. The most positive stereotype towards the elder was demonstrated by individuals 40 years of age, followed in decreasing order, by the 70, 20, and 60 years old groups.

  14. SOCIALES DE LOS PROFESORES

    Directory of Open Access Journals (Sweden)

    CAROLINA GARCÍA GONZÁLEZ

    2011-01-01

    Full Text Available Desde comienzos de la década de 1990 en Chile se han impulsado Reformas Educativas orientadas a mejorar la calidad y la equidad de la educación, sin embargo, no se han experimentado las mejoras esperadas. Los resultados solo han registrado leves avances, mientras se ha ido consolidando la segmentación del sistema educativo. Esta investigación abordó la problemática desde las Representaciones Sociales de los profesores sobre las implicancias de las reformas estandarizadoras en la gestión del conocimiento, aspecto fundamental en el proceso educativo. Los resultados permitieron determinar que para los docentes la estandarización ha significado un importante desafío para la gestión del conocimiento que deben desarrollar. Su implementación indiscriminada los ha enfrentado ante el desafío de tener que equilibrar la formación integral de los estudiantes para que cuenten con las habilidades que la sociedad del conocimiento les exige, y la obtención de altos resultados en las pruebas estandarizadas.

  15. de los movimientos sociales

    Directory of Open Access Journals (Sweden)

    Juliana Flórez-Flórez

    2005-01-01

    Full Text Available Desde el giro de los ochenta hasta hoy, los análisis de la acción colectiva tienden a concluir que la lucha de los movimientos latinoamericanos se halla anclada a la ilustración. Sea porque reivindican necesidades básicas, porque su principal interlocutor es el Estado, porque su contexto de lucha es atrasado o porque están atadas a localismos. En cualquiera de estos casos, se entiende que esos actores difícilmente pueden cuestionar los límites de la modernidad globalizada. En este artículo planteamos que tales conclusiones asumen un pensamiento dicotómico que diferencia y jerarquiza las dinámicas sociales según su mayor o menor distanciamiento de la tradición; una operación ilustrada que, paradójicamente, las teorías de movimientos deben a las perspectivas críticas de la ilustración; más específicamente, a su noción eurocéntrica de la modernidad. A partir de la revisión que de ese concepto ofrecen las posturas postcoloniales, concretamente el Programa de Investigación Modernidad/Colonialidad, dejamos sentadas algunas claves interpretativas que cambiarían los términos del debate sobre el escaso potencial de los movimientos latinoamericanos como actores críticos de la modernidad.

  16. Method and apparatus for constructing an underground barrier wall structure

    Science.gov (United States)

    Dwyer, Brian P.; Stewart, Willis E.; Dwyer, Stephen F.

    2002-01-01

    A method and apparatus for constructing a underground barrier wall structure using a jet grout injector subassembly comprising a pair of primary nozzles and a plurality of secondary nozzles, the secondary nozzles having a smaller diameter than the primary nozzles, for injecting grout in directions other than the primary direction, which creates a barrier wall panel having a substantially uniform wall thickess. This invention addresses the problem of the weak "bow-tie" shape that is formed during conventional jet injection when using only a pair of primary nozzles. The improvement is accomplished by using at least four secondary nozzles, of smaller diameter, located on both sides of the primary nozzles. These additional secondary nozzles spray grout or permeable reactive materials in other directions optimized to fill in the thin regions of the bow-tie shape. The result is a panel with increased strength and substantially uniform wall thickness.

  17. Tungsten-titanium diffusion barriers for silver metallization

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, Shekhar [Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287-6006 (United States); Han, Hauk [Science and Engineering of Materials Program, Center for Solid State Science, Arizona State University, Tempe, Arizona 85287-1706 (United States); Alford, T.L. [Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287-6006 (United States)]. E-mail: alford@asu.edu

    2006-12-05

    Diffusion barrier properties and thermal stability of reactive sputtered W-Ti films between Ag and Si were studied using X-ray diffractometry, X-ray fluorescence spectrometry, Rutherford backscattering spectrometry, four point probe analysis, and field emission scanning electron microscopy. These films were annealed in vacuum at different temperatures for 1 h. Silver layers were found to be stable up to 600 deg. C; after which, Ag agglomerated at 700 deg. C. Rutherford backscattering analysis showed that interfacial reactions took place at temperatures higher than 400 deg. C. Four point probe resistivity measurements showed that the films were stable up to 600 deg. C. At 700 deg. C the resistivity increased abnormally. These results support further investigation of W-Ti films as a potential barrier layer for Ag metallization in the high temperature electronics.

  18. Coastal Structures and Barriers 2012

    Data.gov (United States)

    California Department of Resources — This dataset is a compilation of the UCSC Sand Retention Structures, MC Barriers, and USACE Coastal Structures. UCSC Sand Retention Structures originate from a...

  19. and use of barrier techniques

    African Journals Online (AJOL)

    Attitudes of Nigerian dentists towards hepatitis B vaccination and use of barrier techniques .... tine screening of only high-risk patients has been recommended.“ .... i337-1342. Sote EO. AIDS and infection Control: experiences, attitudes,.

  20. Barriers for recess physical activity

    DEFF Research Database (Denmark)

    Pawlowski, Charlotte Skau; Tjørnhøj-Thomsen, Tine; Schipperijn, Jasper

    2014-01-01

    they would like to have more secluded areas added to the school playground, even in large schoolyards where lack of space was not a barrier. This aligned with girls' requests for more "hanging-out" facilities, whereas boys primarily wanted activity promoting facilities. CONCLUSION: Based on the results from......BACKGROUND: Many children, in particular girls, do not reach the recommended amount of daily physical activity. School recess provides an opportunity for both boys and girls to be physically active, but barriers to recess physical activity are not well understood. This study explores gender....... This was verified by a thematic analysis of transcripts from the open discussions and go-along interviews. RESULTS: The most frequently identified barriers for both boys and girls were weather, conflicts, lack of space, lack of play facilities and a newly-found barrier, use of electronic devices. While boys...

  1. Coastal Structures and Barriers 2012

    Data.gov (United States)

    California Department of Resources — This dataset is a compilation of the UCSC Sand Retention Structures, MC Barriers, and USACE Coastal Structures. UCSC Sand Retention Structures originate from a...

  2. Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  3. Guided tissue regeneration. Absorbable barriers.

    Science.gov (United States)

    Wang, H L; MacNeil, R L

    1998-07-01

    Over the past 15 years, techniques aimed at regeneration of lost periodontal tissue have become widely used and accepted in clinical practice. Among these techniques are those which use the principles of guided tissue regeneration (GTR), wherein barriers (i.e., membranes) are used to control cell and tissue repopulation of the periodontal wound. A variety of non-absorbable and absorbable barriers have been developed and used for this purpose, with a trend in recent years toward increased use of absorbable GTR materials. This article describes the evolution of absorbable barrier materials and overview materials available for clinical use today. In addition, advantages and disadvantages of these materials are discussed, as well as possible new developments in barrier-based GTR therapy.

  4. Dielectric barrier structure with hollow electrodes and its recoil effect

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shuang; Chen, Qunzhi; Liu, Jiahui; Wang, Kaile [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Jiang, Zhe; Sun, Zhili [College of Engineering, Peking University, Beijing 100871 (China); Zhang, Jue; Fang, Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

    2015-06-15

    A dielectric barrier structure with hollow electrodes (HEDBS), in which gas flow oriented parallel to the electric field, was proposed. Results showed that with this structure, air can be effectively ignited, forming atmospheric low temperature plasma, and the proposed HEDBS could achieve much higher electron density (5 × 10{sup 15}/cm{sup 3}). It was also found that the flow condition, including outlet diameter and flow rate, played a key role in the evolution of electron density. Optical emission spectroscopy diagnostic results showed that the concentration of reactive species had the same variation trend as the electron density. The simulated distribution of discharge gas flow indicated that the HEDBS had a strong recoil effect on discharge gas, and could efficiently promote generating electron density as well as reactive species.

  5. Nonlocal reflection by photonic barriers

    OpenAIRE

    Vetter, R. -M.; A. Haibel; Nimtz, G.

    2001-01-01

    The time behaviour of microwaves undergoing partial reflection by photonic barriers was measured in the time and in the frequency domain. It was observed that unlike the duration of partial reflection by dielectric layers, the measured reflection duration of barriers is independent of their length. The experimental results point to a nonlocal behaviour of evanescent modes at least over a distance of some ten wavelengths. Evanescent modes correspond to photonic tunnelling in quantum mechanics.

  6. Schooling Inequality and Language Barriers

    OpenAIRE

    Parker, Susan W.; Rubalcava, Luis; Teruel, Graciela

    2005-01-01

    This article estimates the impact of language barriers on school achievement and the potential ameliorating role of bilingual education. Using large household data sets from poor rural communities in Mexico, we find that parental language (failure to speak Spanish) represents an important barrier to the schooling of indigenous children. We provide an empirical test suggesting that this largely reflects parental human capital related to culture/language, rather than unobserved wealth effects. ...

  7. Economic alternatives for containment barriers

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson, P.J.; Jasperse, B.H.; Fisher, M.J. [Geo-Con, Inc., Monroeville, PA (United States)

    1997-12-31

    Fixation, barriers, and containment of existing landfills and other disposal areas are often performed by insitu auger type soil mixing and jet grouting. Cement or other chemical reagents are mixed with soil to form both vertical and horizontal barriers. Immobilization of contaminants can be economically achieved by mixing soil and the contaminants with reagents that solidify or stabilize the contaminated area. Developed in Japan, and relatively new to the United States, the first large scale application was for a vertical barrier at the Jackson Lake Dam project in 1986. This technology has grown in both the civil and environmental field since. The paper describes current United States practice for Deep Soil Mixing (over 12 meters in depth), and Shallow Soil Mixing for vertical barriers and stabilization/solidification, and Jet Grouting for horizontal and vertical barriers. Creating very low permeability barriers at depth with minimal surface return often makes these techniques economical when compared to slurry trenches. The paper will discuss equipment, materials, soil and strength parameters, and quality control.

  8. Boletines de calificaciones para los derechos de los refugiados

    OpenAIRE

    Forster, Bruce

    2011-01-01

    El Comité de los Estados Unidos para los Refugiados e Inmigrantes ha proporcionado información valiosa en sus “boletines de calificaciones en los derechos de los refugiados”, pero un análisis posterior produce información más útil todavía.

  9. Reatividade animal Confinement reactivity

    Directory of Open Access Journals (Sweden)

    Walsiara Estanislau Maffei

    2009-07-01

    Full Text Available A reatividade é definida como a reação do animal quando contido num ambiente de contenção móvel. Ela é quantificada por meio do teste de reatividade animal em ambiente de contenção móvel - REATEST®. Este teste consiste num dispositivo eletrônico acoplado à balança e num software específico. O dispositivo capta a movimentação que o animal provoca na balança, durante 20 segundos e a envia para o software que a processa determinando a reatividade do animal numa escala contínua de pontos. Pontuações maiores são de animais mais reativos (mais agressivo. A reatividade foi criada com os objetivos de solucionar os problemas até então existentes na seleção para temperamento e de permitir estimação de parâmetros genéticos mais confiáveis. Ela é uma característica objetiva que tem grande variabilidade fenotípica e é de quantificação rápida, fácil e segura, além de poder ser quantificada em qualquer tipo de balança, o que permite maior aplicabilidade. Ela não interfere nas práticas de manejo das fazendas porque é quantificada no momento da pesagem dos animais. Sua herdabilidade na raça Nelore é de 0,39 ao ano e 0,23 ao sobreano e suas correlações genéticas com ganho de peso diário são de -0,28 do nascimento até desmama e de -0,49 do desmame até ano. Já suas correlações genéticas com desenvolvimento do perímetro escrotal do ano ao sobreano variam de -0,25 e -0,41.The confinement reactivity (CR has been used as a measure of temperament in Brazil and it is defined as the animal reaction when contained in the scale. It is quantified through the animal reactivity test - REATEST®. This test consists of an electronic device coupled to the scale and of specific software. The device captures the movement that the animal provokes in the scale, during 20 seconds and sends it for the software that processes this movement and determines the animal CR in a continuous scale of points. Higher punctuations belong to

  10. LOS TRIBUNALES DE FAMILIA

    Directory of Open Access Journals (Sweden)

    Susan Turner Saelzer

    2002-01-01

    Full Text Available El proyecto de ley que crea los Tribunales de Familia, actualmente en tramitación, responde a imperativos provenientes tanto del derecho nacional como del derecho internacional. En efecto, en la formulación de un nuevo Derecho de Familia resulta indispensable adecuar los órganos jurisdiccionales llamados a conocer de los conflictos que se suscitan en el ámbito familiar y dotarlos de una competencia amplia para conocer de todos los asuntos que tengan repercusiones sobre la familia. En la primera parte del presente trabajo, se estudia el contexto que enmarca la idea de la creación de los Tribunales de Familia y en la segunda, se analiza en forma pormenorizada los aspectos del proyecto referidos a la estructura y composición de los Tribunales de Familia, a su competencia y procedimientos, y por último, a las vías de solución alternativa de conflictos consagrados.The current legislative draft that would introduce the so called «Family Courts» to the Chilean court system responds to both national and international law imperatives. In fact, it is necessary to reform the court system so as to allow that a single specialized court resolves all legal issues arising from a particular family conflict. The first part of this paper refers to the principles, ideas and institutional context behind the creation of the Family Courts. The second part contains a detailed analysis of the project regarding the organization and composition of the Family Courts, their jurisdiction, proceedings and alternative means of conflict resolution.

  11. Suboxic dolomite formation linked to the sedimentary Mn cycle, Archipelago Los Roques, Venezuela

    Science.gov (United States)

    Petrash, D.; Lalonde, S.; Gonzalez, G.; Gingras, M.; Konhauser, K.

    2013-12-01

    The preferential formation of Ca-rich dolomite precursors in modern peritidal environments has been associated with the degradation of buried microbial mats, with complexation of Ca and Mg cations by extracellular polysaccharides, and alkalinity generation, mostly through bacterial sulfate reduction. However, it remains unclear why Ca-dolomite would not occur in suboxic sediments where bacterial Mn(IV) and/or Fe(III) reduction are important sources of alkalinity, and the role, if any, of Fe- and Mn-recycling in its diagenetic stabilization to more stoichiometric dolomite is unknown. In a shoaling-upward parasequence in the Archipelago Los Roques, Venezuela, an abundance of Ca-dolomite coincides with a relative decrease in bulk-sediment iron concentrations. These sediments were analyzed with multiple analytical tools, including EPMA, ICP-MS, synchrotron-based XRF, XRD, and spatially resolved XANES. Results demonstrate that the distribution of spheroidal aggregates of nanometer-scale Ca-rich dolomite rhombohedra is linked with interstitial elemental sulfur and manganese accumulations, with Mn occurring in several oxidation states (Fig. 1). Based on our observations at this novel dolomite-forming site, we suggest that in peritidal settings the burial of metal-reactive microbial mats act as a barrier capable of concentrating dissolved reactive species that promote greater sediment residence times in suboxic (manganic) zones, where the recycling of Mn not only plays an important role in the remineralization of organic matter, but also sustains elevated alkalinity and dissolved pore water sulfide concentrations. The last two effects have been previously suggested to promote Mg dehydration, the major kinetic barrier to dolomite nucleation. Figure 1. Normalized Mn K-edge merged spectra of a 5 x 5 μm analytical area bearing dolomite cements. A: The K-edge exhibits two main features at about 6554 and 6558 eV. B: Intermediate Mn (III) is identified by the positive slope of

  12. Conservation of reactive electromagnetic energy in reactive time

    CERN Document Server

    Kaiser, Gerald

    2015-01-01

    The complex Poynting theorem (CPT) is extended to a canonical time-scale domain $(t,s)$. Time-harmonic phasors are replaced by the positive-frequency parts of general fields, which extend analytically to complex time $t+is$, with $s>0$ interpreted as a time resolution scale. The real part of the extended CPT gives conservation in $t$ of a time-averaged field energy, and its imaginary part gives conservation in $s$ of a time-averaged reactive energy. In both cases, the averaging windows are determined by a Cauchy kernel of width $\\Delta t\\sim \\pm s$. This completes the time-harmonic CPT, whose imaginary part is generally supposed to be vaguely `related to' reactive energy without giving a conservation law, or even an expression, for the latter. The interpretation of $s$ as reactive time, tracking the leads and lags associated with stored capacitative and inductive energy, gives a simple explanation of the volt-ampere reactive (var) unit measuring reactive power: a var is simply one Joule per reactive second. T...

  13. los Derechos Humanos

    Directory of Open Access Journals (Sweden)

    Luciano Barp Fontana

    2005-01-01

    Full Text Available Una declaración universal de los derechos humanos es incompleta si se reduce a un conjunto de recomendaciones para que cada persona y cada organismo de la sociedad se esfuerce para promover, mediante la enseñanza y la educación, el respeto a una serie de valores y de derechos ligados a la dignidad humana. Así se va depauperando la expresión “derechos humanos”, que actualmente tiende a confundirse con unas instancias en las que pueden frustrarse frecuentemente las esperanzas de quien busca justicia. Para que una declaración sea completa es necesario fundamentarla en la constitución universal humana. Solamente así quedará asegurada y garantizada su inviolabilidad. En efecto, la primera violación a los derechos humanos consiste en descuidar el deber urgente de aclarar la respuesta a la pregunta “¿qué es el ser humano?” De hecho, el tema de los derechos humanos debe ser fundamentalmente ontológico-antropológico. De la postura antropológica derivará el tema axiológico de la dignidad del ser humano. De la postura axiológica brotará el tema deontológico del deber ser del ser humano. Finalmente, de la postura deontológica derivará el tema jurídico de los derechos humanos de todos los humanos. Brevemente. El punto de partida es necesariamente el ser. El segundo paso es el ser humano. El tercer paso es el valor (dignidad del ser humano. El cuarto paso será el deber ser del ser humano. La fundamentación de los derechos humanos que proponemos en este artículo consiste en un proceso dinámico-histórico de una humanización concebida y realizada como una liberación de cada hombre y de todos los hombres, sin concesiones a posturas totalitarias que devalúan el valor del individuo, o bien a posturas liberales que no respetan la igualdad de todos los grupos humanos. En realidad, cada persona goza de los mismos derechos humanos, no por un beneficio concedido por una cierta clase social o por el Estado, sino precisamente por la

  14. Quistes de los maxilares

    Directory of Open Access Journals (Sweden)

    Ivan Alberto Manotas Arevalo

    2013-12-01

    Full Text Available Los Grandes Quistes de los Maxilares han estado vinculados siempre a la humanidad, desde tiempos remotos, pues han sido halladas en restos de especimenes fosiles, han llamado la atencion de los clínicos, en torno a su etiologia, en la que se ha introducido la participacion de la genetica, (demostrada en el desarrollo de los queratoquistes maxilares, la fisiopatologia, caracteristicas histologicas (inmunohistoquimica, posibilidades diagnosticas por la imagen, (como la tomografia computarizada y la resonancia nuclear magnetica y otras pruebas. Además llaman la atención al estudio, por sus alternativas de manejo especialmente las formas radicales, y el analisis de asociaciones a otras patolo-gias benignas y malignas, y de la recurrencia muy alto de algunas de estas lesiones. Mucho se ha desarrollado para elucidar su naturaleza real, estadificar adecuadamente la lesion descartando asocia-ciones patologicas sindromicas, indicar un tratamiento apropiado, y realizar seguimientos a largo plazo. Este articulo pretende recaudar una information general que de parametros para abordar el estudio de los quistes maxilares a partir de la presentacion de un caso clinico.

  15. Los acueductos Romanos

    Directory of Open Access Journals (Sweden)

    Fernández Casado, C.

    1971-12-01

    Full Text Available Con este documentado trabajo —al igual que los anteriores— damos por terminada la serie de acueductos romanos que hemos ido publicando en números precedentes de nuestra revista «INFORMES». En fecha próxima aparecerá el libro que los reúne todos en un volumen de indudable interés. El Profesor Fernández Casado ha llevado a cabo, con gran cariño, la ímproba labor de recopilar y ordenar curiosos datos sobre cada uno de los acueductos que existen en España —unos en perfecto estado de conservación e incluso en servicio, otros transformados en ruinas grandiosas, y un tercer grupo, de los que no quedan más que restos gloriosos poco definidos—, buceando en todos los lugares donde pudiera existir algún vestigio de datos de partida, labor harto difícil, dada la evidente escasa: de fuentes precisas de tipo geográfico o literario. Gracias a su esfuerzo hemos podido exponer a la admiración de todos la belleza y la recia grandeza de estas muestras de la ingeniería romana en la que, como en tantas otras facetas del Arte, de la Técnica y de la Cultura, alcanzaron las más altas cotas. V. M.

  16. Normas internacionales de los alimentos

    OpenAIRE

    Comisión CODEX ALIMENTARIUS

    2015-01-01

    Todos los textos del Codex se encuentran a disposición del público en los sitios web que se indican a continuación: Todas las normas, las directrices, los códigos de prácticas y los textos consultivos que integran el Codex Alimentarius están disponibles en la Lista de normas.

  17. Filaggrin and Skin Barrier Function.

    Science.gov (United States)

    Kezic, Sanja; Jakasa, Ivone

    2016-01-01

    The skin barrier function is greatly dependent on the structure and composition of the uppermost layer of the epidermis, the stratum corneum (SC), which is made up of flattened anucleated cells surrounded by highly organized and continuous lipid matrix. The interior of the corneocytes consists mainly of keratin filaments aggregated by filaggrin (FLG) protein. Next, together with several other proteins, FLG is cross-linked into a mechanically robust cornified cell envelope providing a scaffold for the extracellular lipid matrix. In addition to its role for the SC structural and mechanical integrity, FLG degradation products account in part for the water-holding capacity and maintenance of acidic pH of the SC, both crucial for the epidermal barrier homoeostasis by regulating activity of multiple enzymes that control desquamation, lipid synthesis and inflammation. The major determinant of FLG expression in the skin are loss-of-function mutations in FLG, the strongest genetic risk factor for atopic dermatitis (AD), an inflammatory skin disease characterized by a reduced skin barrier function. The prevalence of FLG mutations varies greatly among different populations and ranges from about 10% in Northern Europeans to less than 1% in the African populations. An impaired skin barrier facilitates absorption of potentially hazardous chemicals, which might cause adverse effects in the skin, such as contact dermatitis, or systemic toxicity after their passage into blood. In another direction, a leaky epidermal barrier will lead to enhanced loss of water from the skin. A recent study has shown that even subtle increase in epidermal water loss in newborns increases the risk for AD. Although there are multiple modes of action by which FLG might affect skin barrier it is still unclear whether and how FLG deficiency leads to the reduced skin barrier function. This chapter summarizes the current knowledge in this field obtained from clinical studies, and animal and in vitro models

  18. Hydrothermal Reactivity of Amines

    Science.gov (United States)

    Robinson, K.; Shock, E.; Hartnett, H. E.; Williams, L. B.; Gould, I.

    2013-12-01

    The reactivity of aqueous amines depends on temperature, pH, and redox state [1], all of which are highly variable in hydrothermal systems. Temperature and pH affect the ratio of protonated to unprotonated amines (R-NH2 + H+ = R-NH3+), which act as nucleophiles and electrophiles, respectively. We hypothesize that this dual nature can explain the pH dependence of reaction rates, and predict that rates will approach a maximum at pH = pKa where the ratio of protonated and unprotonated amines approaches one and the two compounds are poised to react with one another. Higher temperatures in hydrothermal systems allow for more rapid reaction rates, readily reversible reactions, and unique carbon-nitrogen chemistry in which water acts as a reagent in addition to being the solvent. In this study, aqueous benzylamine was used as a model compound to explore the reaction mechanisms, kinetics, and equilibria of amines under hydrothermal conditions. Experiments were carried out in anoxic silica glass tubes at 250°C (Psat) using phosphate-buffered solutions to observe changes in reaction rates and product distributions as a function of pH. The rate of decomposition of benzylamine was much faster at pH 4 than at pH 9, consistent with the prediction that benzylamine acts as both nucleophile and an electrophile, and our estimate that the pKa of benzylamine is ~5 at 250°C and Psat. Accordingly, dibenzylamine is the primary product of the reaction of two benzylamine molecules, and this reaction is readily reversible under hydrothermal conditions. Extremely acidic or basic pH can be used to suppress dibenzylamine production, which also suppresses the formation of all other major products, including toluene, benzyl alcohol, dibenzylimine, and tribenzylamine. This suggests that dibenzylamine is the lone primary product that then itself reacts as a precursor to produce the above compounds. Analog experiments performed with ring-substituted benzylamine derivatives and chiral

  19. Computational Study of Chemical Reactivity Using Information-Theoretic Quantities from Density Functional Reactivity Theory for Electrophilic Aromatic Substitution Reactions.

    Science.gov (United States)

    Wu, Wenjie; Wu, Zemin; Rong, Chunying; Lu, Tian; Huang, Ying; Liu, Shubin

    2015-07-23

    The electrophilic aromatic substitution for nitration, halogenation, sulfonation, and acylation is a vastly important category of chemical transformation. Its reactivity and regioselectivity is predominantly determined by nucleophilicity of carbon atoms on the aromatic ring, which in return is immensely influenced by the group that is attached to the aromatic ring a priori. In this work, taking advantage of recent developments in quantifying nucleophilicity (electrophilicity) with descriptors from the information-theoretic approach in density functional reactivity theory, we examine the reactivity properties of this reaction system from three perspectives. These include scaling patterns of information-theoretic quantities such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy and information gain at both molecular and atomic levels, quantitative predictions of the barrier height with both Hirshfeld charge and information gain, and energetic decomposition analyses of the barrier height for the reactions. To that end, we focused in this work on the identity reaction of the monosubstituted-benzene molecule reacting with hydrogen fluoride using boron trifluoride as the catalyst in the gas phase. We also considered 19 substituting groups, 9 of which are ortho/para directing and the other 9 meta directing, besides the case of R = -H. Similar scaling patterns for these information-theoretic quantities found for stable species elsewhere were disclosed for these reactions systems. We also unveiled novel scaling patterns for information gain at the atomic level. The barrier height of the reactions can reliably be predicted by using both the Hirshfeld charge and information gain at the regioselective carbon atom. The energy decomposition analysis ensued yields an unambiguous picture about the origin of the barrier height, where we showed that it is the electrostatic interaction that plays the dominant role, while the roles played by exchange-correlation and

  20. Diabetes and diet: Managing dietary barriers.

    NARCIS (Netherlands)

    Friele, R.D.

    1989-01-01

    This thesis reports on the barriers diabetic patients experience with their diet, and the ways they cope with these barriers. A dietary barrier is a hinderance to a person's well-being, induced by being advised a diet. First inventories were made of possible dietary barriers and ways of coping with

  1. Barriers to Psychosocial Services among Homeless Women Veterans.

    Science.gov (United States)

    Hamilton, Alison B; Poza, Ines; Hines, Vivian; Washington, Donna L

    2012-01-01

    Veterans comprise a disproportionate fraction of the nation's homeless population, with women veterans up to four times more likely to be homeless than non-veteran women. This paper provides a grounded description of barriers to psychosocial services among homeless women veterans. Three focus groups were held in Los Angeles, CA, with a total of 29 homeless women veterans. These women described three primary, proximal (current) barriers: lack of information about services, limited access to services, and lack of coordination across services. Compared to non-veteran homeless women, women veterans potentially face additional challenges of trauma exposure during military service, post-military readjustment issues, and few services specific to women veterans. Understanding their service needs and experiences is critical to the development of relevant and appropriate services that move homeless women veterans away from vulnerability, into safety.

  2. Instrucciones para los autores

    Directory of Open Access Journals (Sweden)

    Revista Facultad de Ingenieria

    2010-12-01

    Full Text Available REVISTA FACULTAD DE INGENIERÍA, publicación editada por el Centro de Estudios, Investigación y Educación Continuada de la Facultad de Ingeniería (CEDEC de la Universidad Pedagógica  y Tecnológica de Colombia, UPTC, busca contribuir  a  la difusión de  los nuevos conocimientos científicos y tecnológicos que se producen en el campo de  las ingenierías, como resultados de los procesos  investigativos que llevan a cabo los docentes y estudiantes, principalmente, de esta Facultad.Se reciben colaboraciones de profesores, estudiantes y administrativos de la UPTC y de otras universidades,  tanto del país como del exterior, y de  investigadores en general y tratadistas de la temática de la revista.

  3. Instrucciones para los autores

    Directory of Open Access Journals (Sweden)

    Revista Facultad de Ingenieria

    2010-11-01

    Full Text Available REVISTA INGENIERÍA, publicación editada por el Centro de Estudios, Investigación y Educación Continuada  de  la  Facultad de  Ingeniería  (CEDEC  de  la Universidad Pedagógica y Tecnológica de Colombia, UPTC, busca contribuir a la difusión de los nuevos conocimientos científicos y desarrollos  tecnológicos que se producen en el campo de  las  ingenierías, como resultados de los procesos investigativos que llevan a cabo los docentes y estudiantes, principalmente, de esta Facultad.

  4. en los noventa

    Directory of Open Access Journals (Sweden)

    Gerardo Halpern

    2005-01-01

    Full Text Available Este trabajo analiza el papel del Estado en la formación, activación y administración de los marcos interpretativos respecto de los “inmigrantes paraguayos” que viven en Argentina, en tanto producto generado, ejecutado y administrado, entre otros, por los campos jurídico y laboral, fundamentales para comprender las delimitaciones de posiciones de agentes específicos en el espacio social y sus consecuentes respuestas. Estas delimitaciones se inscriben en relaciones de poder en las que el agente por excelencia es el Estado, el cual responde, a lo largo de la historia y las coyunturas, a las necesidades del capital en su relación respecto del trabajo

  5. Los oficios del comunicador

    Directory of Open Access Journals (Sweden)

    Jesús Martín-Barbero

    2011-01-01

    Full Text Available En el presente ensayo se evalúan los oficios del comunicador a la luz de tres ámbitos problemáticos: las competencias y los oficios, las agencias de legitimación y las dinámicas de transformación. Se defiende la tesis de un cambio cualitativo, desde un comunicador-intermediario hacia un comunicador-mediador, que asume como base de su acción las asimetrías y las desigualdades sociales y culturales, al participar como actor en la construcción de una sociedad democrática. Se subraya en este contexto que, frente a las tecnologías incorporadas a los medios de comunicación, el ejercicio del comunicador debe comportar más inquietudes e interrogantes que respuestas.

  6. Los Cuchillos de Albacete

    Directory of Open Access Journals (Sweden)

    Rodríguez Lorente, Juan J.

    1967-12-01

    Full Text Available Not available.

    DE la larga honrosa tradición española en la fabricación artesana de aceros para armas blancas, que alcanzó su cima en los siglos XVI y XVII, y desapareció casi totalmente en el XVIII con la importación de los espadines franceses puestos de moda por la corte de don Felipe de Borbón, puede decirse que no queda en nuestros días vestigio alguno, si se exceptúan los modestos esfuerzos estatales centralizados en la Fábrica Nacional de Armas de Toledo, y la pujante industria cuchillera de Albacete.

  7. A design study for a medium-scale field demonstration of the viscous barrier technology

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, G. [Lawrence Berkeley National Lab., CA (United States); Yen, P. [Bechtel Corp., San Francisco, CA (United States); Persoff, P.; Finsterle, S.; Williams, P.; Myer, L.; Pruess, K. [Lawrence Berkeley National Lab., CA (United States)

    1996-09-01

    This report is the design study for a medium-scale field demonstration of Lawrence Berkeley National Laboratory`s new subsurface containment technology for waste isolation using a new generation of barrier liquids. The test site is located in central California in a quarry owned by the Los Banos Gravel Company in Los Banos, California, in heterogeneous unsaturated deposits of sand, silt, and -ravel typical of many of the and DOE cleanup sites and particularly analogous to the Hanford site. The coals of the field demonstration are (a) to demonstrate the ability to create a continuous subsurface barrier isolating a medium-scale volume (30 ft long by 30 ft wide by 20 ft deep, i.e. 1/10th to 1/8th the size of a buried tank at the Hanford Reservation) in the subsurface, and (b) to demonstrate the continuity, performance, and integrity of the barrier.

  8. Instrucciones a los Autores

    Directory of Open Access Journals (Sweden)

    revistaiid@ uptc.edu.co

    2006-12-01

    Full Text Available Ingeniería,  Investigación y Desarrollo publica  trabajos inéditos sobre geología, minería, electrónica, industrial y ciencias afines, en español. Podrán publicarse artículos originales, de investigación y/o innovación tecnológica, de revisión o réplicas de publicaciones de la propia revista. Además, se podrán incluir  resúmenes de  tesis,  reseñas de  libros y comunicaciones de  interés a estas profesiones.Para  la presentación de  los artículos  se debe  tener en cuenta que: Los artículos serán evaluados por   el comité Editorial y un árbitro, el que se reserva el derecho de decidir sobre su publicación. Los  trabajos enviados a  Ingeniería,  Investigación y Desarrollo, no podrán ser sometidos simultáneamente a evaluación por otro medio de publicación. El contenido de los trabajos   es responsabilidad exclusiva de sus autores. No se devolverán los originales de los trabajos

  9. Los poetas del Valle

    Directory of Open Access Journals (Sweden)

    Helcías Martán Góngora

    1963-10-01

    Full Text Available No es el "Azul" que sirvió a Rubén, "padre y maestro mágico", como telón de fondo en su magna aventura renovadora, sino el "Azul" Comarca serenísima -donde vive la eternidad-, el color que impera en los territorios mágicos ele Gilberto Garrido (1887, el insigne lírico nacido en las montañas de Supía, pero volcado como un río sobre el Valle del Cauca, desde los manantiales de su infancia.

  10. de los adolescentes

    Directory of Open Access Journals (Sweden)

    Laura Oliva Zárate

    2007-01-01

    Full Text Available Se evaluó el nivel de autoestima en los adolescentes que cursaban secundaria o bachillerato, cuya condición era la de ser hijos de padres emigrantes, mediante un enfoque mixto, utilizando instrumentos de evaluación y cuestionarios. Los resultados muestran que la tercera parte de dichos jóvenes manifiestan una baja autoestima en dos de las cuatro áreas valoradas, evidenciándose la necesidad de una intervención oportuna a fin de mejorarla.

  11. por los Estados parte

    Directory of Open Access Journals (Sweden)

    Boris Barrios González

    2006-01-01

    Full Text Available El autor realiza un análisis de la cosa juzgada nacional, la cual explica como una cuestión de prejudicialidad que se traduce en una condición de procedibilidad para concurrir al Sistema Interamericano de Protección de los Derechos Humanos; para luego abordar el cumplimiento de las sentencias de la Corte Interamericana, haciendo referencia a los casos más conflictivos que se destacan en la jurisprudencia de la Corte Interamericana de Derechos Humanos.

  12. Los pactos parasociales

    OpenAIRE

    Lina Henao

    2013-01-01

    Los pactos parasociales son acuerdos celebrados al margen de la regulación societaria, entre los socios, entre estos y la sociedad, o con terceros, que constituyen una herramienta de uso frecuente en el desarrollo de las relaciones corporativas pese a la ausencia de una regulación legal integral, y que tienen por finalidad regular extremos no recogidos estatutariamente. Su validez, eficacia e incumplimiento estarán determinados en mayor medida por las normas de derecho civil y en menor propor...

  13. Cuando atacan los animales

    OpenAIRE

    Erian, Alicia

    2000-01-01

    Los cuentos de Alicia Erian han aparecido recientemente en Zoetrope y Nerve. Su primera colección de narrativa breve, The Brutal Language of Love, la publicará la editorial Villard el año próximo. Alicia Erian vive en brooklyn, Nueva York, con su marido, David Franklin. «Cuando atacan los animales» es el primero de sus relatos traducidos al español. Traductor: Juan Gabriel López Guix es traductor del inglés y francés. Se dedica sobre todo a la traducción de narrativa, ensayo y divulgación cie...

  14. Los hijos de Kafka

    Directory of Open Access Journals (Sweden)

    William Díaz Villarreal

    2012-07-01

    Full Text Available Kafka intentó sin éxito publicar un libro, titulado Los hijos, en el que se reunían tres relatos compuestos en el invierno entre 1912 y 1913: “La condena”, “La metamorfosis” y “El fogonero”. En este ensayo, el autor interpreta estos tres relatos como una unidad, a partir del motivo que sugiere el título del libro proyectado por Kafka. Así, estos tres textos exploran los intentos fallidos del hijo por autoafirmarse dentro de la opresiva esfera de influencia del padre.

  15. Cylindrical air flow reversal barrier

    Energy Technology Data Exchange (ETDEWEB)

    Woznica, C.; Rodziewicz, M.

    1988-06-01

    Describes an innovative design introduced in the ZMP mine in Zory for quick reversal of ventilation air flow. Geologic mining conditions at the 705 m deep horizon, where the barrier was built, are described. According to the design used until now, a reversal system consisted of safety barriers, ventilation air locks, a ventilation bridge and stopping needed in case of a fire when air flow direction must be reversed. Nine air locks and an expensive concrete ventilation bridge were needed and the air locks had to be operated at 8 points of the region to effect reversal. The new design consists of a 2-storey cylindrical barrier which also fulfills the function of a ventilation bridge. It can be manually or remotely operated by a mechanical or pneumatic system. Tests showed that the new barrier permits immediate air flow reversal while retaining 60% of the original air, which is important in the case of fire and methane hazards. It permits improved seam panelling and splitting of pillars and brings an economy of about 40 million zlotys in construction cost. Design and operation of the barrier is illustrated and ventilation air circulation is explained. 7 figs.

  16. Structure information from fusion barriers

    Indian Academy of Sciences (India)

    S V S Sastry; S Santra

    2000-06-01

    It is shown that the analysis of fusion barrier distributions is not always an unambiguous test or a ‘fingerprint’ of the structure information of the colliding nuclei. Examples are presented with same fusion barrier distributions for nuclei having different structures. The fusion excitation functions for 16O+208Pb, using the coupled reaction channel (CRC) method and correct structure information, have been analysed. The barrier distributions derived from these excitation functions including many of the significant channels are featureless, although these channels have considerable effects on the fusion excitation function. However, a simultaneous analysis of the fusion, elastic and quasi-elastic channels would fix the structure and the reaction unambiguously

  17. Skin Barrier Function and Allergens

    DEFF Research Database (Denmark)

    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...... 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......) 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...

  18. Los dientes del caballo

    OpenAIRE

    García Verduch, Antonio

    1996-01-01

    El autor cuenta una historia sobre una discusión entre dos hombres por saber cuantos dientes tienen los caballos, recurren a escritos y libros para tratar de averiguarlo, al final se quedan sin resolverlo y todo por no mirarle la boca directamente al caballo

  19. Los beneficios del TLC

    Directory of Open Access Journals (Sweden)

    Martín Uribe Arbeláez

    2007-01-01

    Full Text Available El tlc usa-Colombia aumenta la protección de la propiedad intelectual por encima de la normatividad internacional plasmada en los Acuerdos adpic de la omc y en la Decisión 486 de 2000, de la Comunidad Andina de Naciones. Intensifica la llamada “apertura económica” consagrando un modelo exportador. El propósito de este ensayo es analizar lo que representa para el desarrollo económico y social, con énfasis en los dramáticos cambios que se introducen en el Régimen Común de Propiedad Industrial. El saqueo de la biodiversidad, “patentes a plantas o animales”, los enormes costos para la salud pública, la competitividad basada en las maquilas y la pauperización social, contradicen los sofismas que parecen evocar el realismo mágico como explicación de nuestra historia.�

  20. Los viajes de Ulises

    OpenAIRE

    Alzate, Gabriel Jaime

    2012-01-01

    El autor Gabriel Jaime Alzate nos da a conocer sobre los viajes de Ulises "Cuando emprende el viaje Ulises se entrena en el olvido y cada mañana lanza una saeta que va directa a sus mejores recuerdos. Lo que no sabe es que la saeta regresa a él

  1. Los hijos de Kafka

    National Research Council Canada - National Science Library

    William Díaz Villarreal

    2012-01-01

    Kafka intentó sin éxito publicar un libro, titulado Los hijos, en el que se reunían tres relatos compuestos en el invierno entre 1912 y 1913: “La condena”, “La metamorfosis” y “El fogonero...

  2. Tras los concursos

    OpenAIRE

    Pérez Oyarzun,Fernando 

    2007-01-01

    Los concursos de arquitectura parecen entregar garantías de la calidad del resultado, pueden promover a arquitectos jóvenes y evidencian las tensiones arquitectónicas presentes en un momento dado. El análisis a sus variantes permite entender mejor la problemática existente en torno a ellos

  3. Los murales bogotanos

    Directory of Open Access Journals (Sweden)

    Jorge Moreno Clavijo

    1966-07-01

    Full Text Available No son muchos, en realidad, los muros que en esta capital colombiana se han enriquecido con el aporte de nuestros pintores colombianos. En proporción al crecimiento urbano y al adelanto en otros terrenos, nuestros artistas han sido poco requeridos en este particular.

  4. Notes on Los Alamos

    Energy Technology Data Exchange (ETDEWEB)

    Meade, Roger Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-04-05

    In 1954 an unknown author drafted a report, reprinted below, describing the Laboratory and the community as they existed in late 1953. This report, perhaps intended to be crafted into a public relations document, is valuable because it gives us an autobiographical look at Los Alamos during the first half of the 1950s. It has been edited to enhance readability.

  5. Sound propagation over curved barriers

    Science.gov (United States)

    Pierce, Allan D.; Main, Geoffrey L.; Kearns, James A.; Hsieh, H.-A.

    1986-01-01

    Wide barriers with curved tops are studied with emphasis placed on circumstances whereby the local radius of curvature R of the barrier is continuous along the surface and is large compared to a wavelength. Results analogous to those given by Hayek et al. (1978) are reviewed and extended to cases where the radius of curvature and the surface impedance may vary with position. Circumstances not easily interpreted within the framework of the model proposed by Keller (1956) and Hayek et al. are also considered.

  6. The Solution to Green Barrier

    Institute of Scientific and Technical Information of China (English)

    Cui Yan

    2009-01-01

    @@ The recovery process of world economy is rough and full of twists and turns.Especially the trade protectionism,having reemerged under the mask of"green barrier",is making a great impact on the slowly recovering world economy and trade.Then,what are the characteristics of trade barriers in the post-crisis era?Where is the outlet of Chinese manufacturing industry?With these questions,ourreporter interviewed Professor Zhou Shijian,Standing Director to China Association of International Trade and Senior Researcher to SINO-US Relationship Research Centre of Tsinghua University.

  7. Site-specific reactivity of ethylene at distorted dangling bond configurations on Si(001)

    CERN Document Server

    Pecher, Josua; Dürr, Michael; Tonner, Ralf

    2016-01-01

    We report differences in adsorption and reaction energetics for ethylene on Si(001) with respect to different dangling bond configurations induced by hydrogen precoverage as obtained via density functional theory calculations. This can help to understand the influence of surface defects and precoverage on the reactivity of organic molecules on semiconductor surfaces in general. Our results show that the reactivity on surface dimers fully enclosed by hydrogen covered atoms is essentially unchanged compared to the clean surface. This is confirmed by our scanning tunnelling microscopy measurements. On the contrary, adsorption sites with partially covered surface dimers show a drastic increase in reactivity. This is due to a lowering of the reaction barrier by more than fifty percent compared to the clean surface, which is in line with previous experiments. Adsorption on dimers enclosed by molecule (ethylene) covered surface atoms is reported to have a highly decreased reactivity, a result of destabilization of t...

  8. A seven-degree-of-freedom, time-dependent quantum dynamics study on the energy efficiency in surmounting the central energy barrier of the OH + CH{sub 3} → O + CH{sub 4} reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Pengxiu; Wang, Yuping; Li, Yida; Wang, Dunyou, E-mail: dywang@sdnu.edu.cn [College of Physics and Electronics, Shandong Normal University, Jinan 250014 (China)

    2015-04-28

    A time-dependent, quantum reaction dynamics calculation with seven degrees of freedom was carried out to study the energy efficiency in surmounting the approximate center energy barrier of OH + CH{sub 3}. The calculation shows the OH vibration excitations greatly enhance the reactivity, whereas the vibrational excitations of CH{sub 3} and the rotational excitations hinder the reactivity. On the basis of equal amount of total energy, although this reaction has a slight early barrier, it is the OH vibrational energy that is the dominate force in promoting the reactivity, not the translational energy. The studies on both the forward O + CH{sub 4} and reverse OH + CH{sub 3} reactions demonstrate, for these central barrier reactions, a small change of the barrier location can significantly change the energy efficacy roles on the reactivity. The calculated rate constants agree with the experimental data.

  9. CAEN LOS PANTALONCILLOS

    Directory of Open Access Journals (Sweden)

    ANA MARÍA ARBOLEDA ARANGO

    2008-01-01

    Full Text Available El primer paso para pensar en la posibilidad de llevar a cabo una investigación de mercados es entender el problema de investigación. El presente estudio de caso enfrenta al estudiante a esta problemática utilizando la situación que vivía la Empresa Diseños para EL Interior S.A., empresa colombiana de confecciones que fabrica ropa interior masculina. "Caen los pantaloncillos" refleja la dinámica habitual por la que pasan los equipos de mercadeo al observar síntomas negativos en el desempeño de la marca, en este caso, una importante disminución porcentual en ventas (20% con respecto al último año. Es una dinámica habitual en la medida en que cada uno de los miembros del equipo tiene una experiencia con la marca que le permite formular hipótesis. Adicionalmente, cada miembro del grupo tiene intereses propios a los cuales espera que pueda responder la investigación de mercados. Después de discutir diferentes experiencias, hipótesis y puntos de vista, el equipo de trabajo de Diseños para EL Interior S.A. llega a la conclusión de que es necesario y útil llevar a cabo una investigación de mercados. El caso indica cómo esta iniciativa se debe ver reflejada en un brief, a través del cual se plasme la situación en la que se encuentra la marca, los objetivos de la investigación y el grupo objetivo para la misma. El caso brinda la información necesaria para que el estudiante elabore el brief pensando en la necesidad de demandar una investigación de mercados.

  10. Reactivity to nicotine cues over repeated cue reactivity sessions

    Science.gov (United States)

    LaRowe, Steven D.; Saladin, Michael E.; Carpenter, Matthew J.; Upadhyaya, Himanshu P.

    2009-01-01

    The present study investigated whether reactivity to nicotine-related cues would attenuate across four experimental sessions held one week apart. Participants were nineteen non-treatment seeking, nicotine-dependent males. Cue reactivity sessions were performed in an outpatient research center using in vivo cues consisting of standardized smoking-related paraphernalia (e.g., cigarettes) and neutral comparison paraphernalia (e.g., pencils). Craving ratings were collected before and after both cue presentations while physiological measures (heart rate, skin conductance) were collected before and during the cue presentations. Although craving levels decreased across sessions, smoking-related cues consistently evoked significantly greater increases in craving relative to neutral cues over all four experimental sessions. Skin conductance was higher in response to smoking cues, though this effect was not as robust as that observed for craving. Results suggest that, under the described experimental parameters, craving can be reliably elicited over repeated cue reactivity sessions. PMID:17537583

  11. Reactivity to nicotine cues over repeated cue reactivity sessions.

    Science.gov (United States)

    LaRowe, Steven D; Saladin, Michael E; Carpenter, Matthew J; Upadhyaya, Himanshu P

    2007-12-01

    The present study investigated whether reactivity to nicotine-related cues would attenuate across four experimental sessions held 1 week apart. Participants were nineteen non-treatment seeking, nicotine-dependent males. Cue reactivity sessions were performed in an outpatient research center using in vivo cues consisting of standardized smoking-related paraphernalia (e.g., cigarettes) and neutral comparison paraphernalia (e.g., pencils). Craving ratings were collected before and after both cue presentations while physiological measures (heart rate, skin conductance) were collected before and during the cue presentations. Although craving levels decreased across sessions, smoking-related cues consistently evoked significantly greater increases in craving relative to neutral cues over all four experimental sessions. Skin conductance was higher in response to smoking cues, though this effect was not as robust as that observed for craving. Results suggest that, under the described experimental parameters, craving can be reliably elicited over repeated cue reactivity sessions.

  12. Systems study on engineered barriers: barrier performance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stula, R.T.; Albert, T.E.; Kirstein, B.E.; Lester, D.H.

    1980-09-01

    A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been modified and applied to several package designs. The objective of the study was to develop information to be used in programmatic decision making concerning engineered barrier package design and development. The assessment model, BARIER, was developed in previous tasks of the System Study on Engineered Barriers (SSEB). The new version discussed in this report contains a refined and expanded corrosion rate data base which includes pitting, crack growth, and graphitization as well as bulk corrosion. Corrosion rates for oxic and anoxic conditions at each of the two temperature ranges are supplied. Other improvements include a rigorous treatment of radionuclide release after package failure which includes resistance of damaged barriers and backfill, refined temperature calculations that account for convection and radiation, a subroutine to calculate nuclear gamma radiation field at each barrier surface, refined stress calculations with reduced conservatism and various coding improvements to improve running time and core usage. This report also contains discussion of alternative scenarios to the assumed flooded repository as well as the impact of water exclusion backfills. The model was used to assess post repository closure performance for several designs which were all variation of basic designs from the Spent Unreprocessed Fuel (SURF) program. Many designs were found to delay the onset of leaching by at least a few hundreds of years in all geologic media. Long delay times for radionuclide release were found for packages with a few inches of sorption backfill. Release of uranium, plutonium, and americium was assessed.

  13. Tracking thermal fronts with temperature-sensitive, chemically reactive tracers

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, B.A.; Birdsell, S.A.

    1987-01-01

    Los Alamos is developing tracer techniques using reactive chemicals to track thermal fronts in fractured geothermal reservoirs. If a nonadsorbing tracer flowing from the injection to production well chemically reacts, its reaction rate will be a strong function of temperature. Thus the extent of chemical reaction will be greatest early in the lifetime of the system, and less as the thermal front progresses from the injection to production well. Early laboratory experiments identified tracers with chemical kinetics suitable for reservoirs in the temperature range of 75 to 100/sup 0/C. Recent kinetics studies have focused on the kinetics of hydrolysis of derivatives of bromobenzene. This class of reactions can be used in reservoirs ranging in temperature from 150 to 275/sup 0/C, which is of greater interest to the geothermal industry. Future studies will include laboratory adsorption experiments to identify possibly unwanted adsorption on granite, development of sensitive analytical techniques, and a field demonstration of the reactive tracer concept.

  14. De los moriscos a Cervantes

    OpenAIRE

    Bernabé Pons, Luis Fernando

    2013-01-01

    La presencia y función de los moriscos en la obra de Miguel de Cervantes ha sido analizada en muchas ocasiones, bien de forma aislada, bien poniéndola en relación con los otros personajes relacionados con el islam que aparecen en sus libros. En este trabajo se quiere pasar revista una vez más a estos personajes moriscos, especialmente los de su última etapa, cristalizada en El coloquio de los perros, Don Quijote de la Mancha y Los trabajos de Persiles y Sigismunda, a partir de los últimos aná...

  15. Neurobehavioral foundation of environmental reactivity.

    Science.gov (United States)

    Moore, Sarah R; Depue, Richard A

    2016-02-01

    Sensitivity to environmental context has been of interest for many years, but the nature of individual differences in environmental sensitivity has become of particular focus over the past 2 decades. What is particularly uncertain are the neural variables and processes that mediate the effects of environment on developmental outcomes. Accordingly, we provide a neurobehavioral foundation of reactivity to the environment in several steps. First, the different patterns of environmental sensitivity are defined to identify the significant factors involved in the manifestation of these patterns. Second, we focus on neurobiological reactivity as the construct underlying variation in sensitivity to the environment by (a) providing an organizing threshold model of elicitation of neurobiology by environmental context; and (b) integrating the literature on 2 sets of neuromodulators in terms of each modulator's (a) contribution to neural and behavioral reactivity to stimulation, and (b) relation to emotional-motivational systems (dopamine, opiates and oxytocin, corticotropin-releasing hormone) or the general modulation of those systems (serotonin, norepinephrine, and GABA). Discussion concludes with (a) a comprehensive neurobehavioral framework of environmental reactivity based on a combinatorial model of a supertrait, (b) methodological implications of the model, and (c) a developmental perspective on environmental reactivity.

  16. Bortezomib Induced Hepatitis B Reactivation

    Directory of Open Access Journals (Sweden)

    Salwa Hussain

    2014-01-01

    Full Text Available Background. It has recently been reported that hepatitis B (HBV reactivation often occurs after the use of rituximab and stem cell transplantation in patients with lymphoma who are hepatitis B surface antigen (HBsAg negative. However, clinical data on HBV reactivation in multiple myeloma (MM is limited to only a few reported cases. Bortezomib and lenalidomide have remarkable activity in MM with manageable toxicity profiles, but reactivation of viral infections may emerge as a problem. We present a case of MM that developed HBV reactivation after bortezomib and lenalidomide therapy. Case Report. A 73-year-old female with a history of marginal cell lymphoma was monitored without requiring therapy. In 2009, she developed MM, presenting as a plasmacytoma requiring vertebral decompression and focal radiation. While receiving radiation she developed renal failure and was started on bortezomib and liposomal doxorubicin. After a transient response to 5 cycles, treatment was switched to lenalidomide. Preceding therapy initiation, her serology indicated resolved infection. Serial monitoring for HBV displayed seroconversion one month after change in therapy. Conclusion. Bortezomib associated late HBV reactivation appears to be a unique event that requires further confirmation and brings to discussion whether hepatitis B core positive individuals would benefit from monitoring of HBV activation while on therapy.

  17. Plastic Schottky barrier solar cells

    Science.gov (United States)

    Waldrop, James R.; Cohen, Marshall J.

    1984-01-24

    A photovoltaic cell structure is fabricated from an active medium including an undoped, intrinsically p-type organic semiconductor comprising polyacetylene. When a film of such material is in rectifying contact with a magnesium electrode, a Schottky-barrier junction is obtained within the body of the cell structure. Also, a gold overlayer passivates the magnesium layer on the undoped polyacetylene film.

  18. Seasonal breaching of coastal barriers

    NARCIS (Netherlands)

    Tuan, Thieu Quang

    2007-01-01

    Natural or unintended breaching can be catastrophic, causing loss of human lives and damage to infrastructures, buildings and natural habitats. Quantitative understand-ing of coastal barrier breaching is therefore of great importance to vulnerability as-sessment of protection works as well as to

  19. Functional barriers: Properties and evaluation

    NARCIS (Netherlands)

    Feigenbaum, A.; Dole, P.; Aucejo, S.; Dainelli, D.; Cruz Garcia, C. de la; Hankemeier, T.; N'Gono, Y.; Papaspyrides, C.D.; Paseiro, P.; Pastorelli, S.; Pavlidou, S.; Pennarun, P.Y.; Saillard, P.; Vidal, L.; Vitrac, O.; Voulzatis, Y.

    2005-01-01

    Functional barriers are multilayer structures deemed to prevent migration of some chemicals released by food-contact materials into food. In the area of plastics packaging, different migration behaviours of mono- and multilayer structures are assessed in terms of lag time and of their influence of t

  20. Communication Barriers in Distance Education

    Science.gov (United States)

    Isman, Aytekin; Dabaj, Fahme; Altinay, Fahriye; Altinay, Zehra

    2003-01-01

    Communication is a key concept as being the major tool for people in order to satisfy their needs. It is an activity which refers as process and effective communication requires qualified communication with the elimination of communication barriers. As it is known, distance education is a new trend by following contemporary facilities and tools…

  1. FX barriers with smile dynamics

    NARCIS (Netherlands)

    Baker, Glyn; Beneder, Reimer; Zilber, Alex

    2004-01-01

    Our mandate in this work has been to isolate the features of smile consistent models that are most relevant to the pricing of barrier options. We consider the two classical approaches of stochastic and (parametric) local volatility. Although neither has been particularly successful in practice their

  2. Planar doped barrier subharmonic mixers

    Science.gov (United States)

    Lee, T. H.; East, J. R.; Haddad, G. I.

    1992-01-01

    The Planar Doped Barrier (PDB) diode is a device consisting of a p(+) doping spike between two intrinsic layers and n(+) ohmic contacts. This device has the advantages of controllable barrier height, diode capacitance and forward to reverse current ratio. A symmetrically designed PDB has an anti-symmetric current vs. voltage characteristic and is ideal for use as millimeter wave subharmonic mixers. We have fabricated such devices with barrier heights of 0.3, 0.5 and 0.7 volts from GaAs and InGaAs using a multijunction honeycomb structure with junction diameters between one and ten microns. Initial RF measurements are encouraging. The 0.7 volt barrier height 4 micron GaAs devices were tested as subharmonic mixers at 202 GHz with an IF frequency of 1 GHz and had 18 dB of conversion loss. The estimated mismatch loss was 7 dB and was due to higher diode capacitance. The LO frequency was 100.5 GHz and the pump power was 8 mW.

  3. Barrier/Cu contact resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Reid, J.S.; Nicolet, M.A. [California Inst. of Tech., Pasadena, CA (United States); Angyal, M.S.; Lilienfeld, D.; Shacham-Diamand, Y. [Cornell Univ., Ithaca, NY (United States); Smith, P.M. [Sandia National Labs., Albuquerque, NM (United States)

    1995-10-17

    The specific contact resistivity of Cu with ({alpha} + {beta})-Ta, TiN, {alpha}-W, and amorphous-Ta{sub 36}Si{sub 14}N{sub 50} barrier films is measured using a novel four-point-probe approach. Geometrically, the test structures consist of colinear sets of W-plugs to act as current and voltage probes that contact the bottom of a planar Cu/barrier/Cu stack. Underlying Al interconnects link the plugs to the current source and voltmeter. The center-to-center distance of the probes ranges from 3 to 200 {micro}m. Using a relation developed by Vu et al., a contact resistivity of roughly 7 {times} 10{sup {minus}9} {Omega} cm{sup 2} is obtained for all tested barrier/Cu combinations. By reflective-mode small-angle X-ray scattering, the similarity in contact resistivity among the barrier films may be related to interfacial impurities absorbed from the deposition process.

  4. Nota de los editores

    Directory of Open Access Journals (Sweden)

    Raquel Arias Careaga

    2007-12-01

    Full Text Available Verba Hispanica, sus editores junto con algunos de los amigos, colegas y antiguos alumnos de Julio Rodríguez Puértolas, han decidido elaborar este número especial de la revista dedicado a su obra y a su tdyectoria, no sólo por la dimensión de sus aportaciones al estudio de los hechos literarios como fenómenos propiamente históricos, haciendo de la literatura una herramienta esencial para el conocimiento -y reconocimiento material- del devenir de las sociedades -de las pocas y de sus culturas- como tales fenómenos materiales, sociales e históricos; sino, ]emás, también por el enorme peso de su magisterio, ejercido durante años, tanto en E tados Unidos, como en España, especialmente en la Universidad Autónoma de Madrid, que se ha dirigido siempre a hacer que los estudiantes entiendan el estudio de la literatur como una investigación y un trabajo en el que deben usar no solamente la expresión clara y precisa de sus conclusiones, sino una mirada interdisciplinar a los fenómenos qub son objeto de su estudio. Y finalmente por la larga y frnctífera colaboración directa -e indirecta- con nuestra revista y con nuestro Departamento de Lengua española y literaturas ~spánicas, en Ljubljana. En nuestra memoria quedará siempre su estancia e intervención en el Simposio internacional dedicado al cuarto centenario de la publicación de la primera parte de Don Quijote. Como en la memoria de todos permanecerá el impacto que supuso aquella legendaria Historia social de la literatura española (en colaboración con Iris ¡M. Zavala y Carlos Blanco Aguinaga o el estudio de la literatura fascista española, o esa forma nueva de ver y leer los textos medievales, al Arcipreste de Hita, el Romancero adicional castellano o La, Celestina, en el siglo quince; al propio Cervantes, en la edad conrictiva; o a los autores realistas del diecinueve, Clarín y, sobre todo, Galdós.

  5. Palacio de los Deportes

    Directory of Open Access Journals (Sweden)

    Candela Outeriño, F.

    1968-11-01

    Full Text Available This building was specially built for the Mexico Olympic Games, and was the site for the basketball competition. But during the design stage it was foreseen that it could be later adapted to various other uses, such as boxing matches, ice skating displays, theatre, circus, shows, etc. It has 19.834 seats for spectators. Its circular planform has a 180 m diameter, and there are three levels of organisation. — on the lower level there is accommodation for the competitors, the press and the organisers of the Olympic Competitions; — the main level houses the entrance halls, the stairs, and access to the lower and middle spectator stands; — the top level has the washrooms for the public, the special stands and access to the middle and top stands. The outstanding feature of this sports palace is its general structure, which from the outset was regarded as the dominant element of the design, and also defined its plastic and spatial quality.Este edificio, construido para los Juegos Olímpicos de México, fue destinado a los juegos de baloncesto, pero al proyectarlo se previó que posteriormente pudiera servir para múltiples usos: celebración de combates de boxeo, espectáculos sobre hielo, teatro, circo, etc. Tiene capacidad para 19.824 espectadores sentados. Su planta es circular, con un diámetro total de 180 m, y está organizada en tres niveles: — en el nivel inferior se alojan: los servicios para deportistas, prensa y organización del Certamen Olímpico; —el nivel principal alberga: los vestíbulos, escaleras y accesos a gradería baja y media; — y en el nivel superior se distribuyen: los servicios para público, palcos y accesos a gradería media y alta. En este Palacio de los Deportes destaca su estructura general que fue considerada, desde la fase del proyecto, como el elemento dominante de la composición, y el determinante de su sentido plástico y espacial.

  6. Los indios y los empedrados sotaquireños

    Directory of Open Access Journals (Sweden)

    Edwin Giovanni Quesada-Cárdenas

    2016-09-01

    Full Text Available Este artículo de investigación describe la preparación de los platos culinarios tradicionales del municipio de Sotaquirá (Boyacá, que hacen parte de los saberes ancestrales que han prevalecido generacionalmente en los habitantes del municipio; ya que caracterizan la identidad sotaquireña. También se exponen algunos elementos sobre la gestión de la administración municipal (2012-2015 para promover la permanencia y reconocimiento de estos saberes como patrimonio cultural. El contenido del artículo es el resultado de la investigación “Identidad campesina en torno a los oficios tradicionales en el municipio de Sotaquirá (2013-2015”; que tuvo como fin describir las costumbres culturales en torno a los oficios tradicionales, que configuran la identidad campesina de los habitantes del municipio de Sotaquirá. El enfoque metodológico fue cualitativo desde la corriente socio-critica; se usaron la entrevista y la observación participante para reconocer la importancia de los platos que se configuran como aspectos fundamentales de la identidad de los sotaquireños. Se destaca que este trabajo logró generar espacios de reflexión con los entrevistados respecto de los oficios tradicionales culinarios del municipio en torno al reconocimiento del valor de los platos como patrimonio cultural y las particularidades del plato de acuerdo con los contextos familiares.

  7. Surface Reactivity of Quasicrystalline Materials

    Science.gov (United States)

    Jenks, Cynthia J.

    1997-03-01

    A fundamental knowledge and understanding of the reactivity of quasicrystalline materials is of great interest because of certain practical properties these materials possess, namely low coefficients of friction and oxidation resistance. A recent "hierarchical cluster" model proposed by Janot(C. Janot Phys. Rev. B 56 (1996) 181.) predicts that quasicrystal surfaces should be intrinsically inert and rough, and is useful in explaining their interesting properties. Surface structure and preparation may play a role in the applicability of this model. In this talk, we examine these factors and present experimental measurements of the surface reactivity of some Al-based quasicrystalline materials under ultra-high vacuum conditions (less than 2 x 10-10 Torr). To gain an understanding of what properties are unique to quasicrystals, we make comparisons with the surface reactivity of crystalline alloys of similar composition and pure, crystalline aluminum. note number.

  8. Astrocytic modulation of blood brain barrier: perspectives on Parkinson's disease.

    Science.gov (United States)

    Cabezas, Ricardo; Avila, Marcos; Gonzalez, Janneth; El-Bachá, Ramon Santos; Báez, Eliana; García-Segura, Luis Miguel; Jurado Coronel, Juan Camilo; Capani, Francisco; Cardona-Gomez, Gloria Patricia; Barreto, George E

    2014-01-01

    The blood-brain barrier (BBB) is a tightly regulated interface in the Central Nervous System (CNS) that regulates the exchange of molecules in and out from the brain thus maintaining the CNS homeostasis. It is mainly composed of endothelial cells (ECs), pericytes and astrocytes that create a neurovascular unit (NVU) with the adjacent neurons. Astrocytes are essential for the formation and maintenance of the BBB by providing secreted factors that lead to the adequate association between the cells of the BBB and the formation of strong tight junctions. Under neurological disorders, such as chronic cerebral ischemia, brain trauma, Epilepsy, Alzheimer and Parkinson's Diseases, a disruption of the BBB takes place, involving a lost in the permeability of the barrier and phenotypical changes in both the ECs and astrocytes. In this aspect, it has been established that the process of reactive gliosis is a common feature of astrocytes during BBB disruption, which has a detrimental effect on the barrier function and a subsequent damage in neuronal survival. In this review we discuss the implications of astrocyte functions in the protection of the BBB, and in the development of Parkinson's disease (PD) and related disorders. Additionally, we highlight the current and future strategies in astrocyte protection aimed at the development of restorative therapies for the BBB in pathological conditions.

  9. Subsurface Barrier Formation as a CO2 Leakage Mitigation Technology

    Science.gov (United States)

    Castaneda Herrera, C. A.; Stevens, G.; Haese, R. R.

    2015-12-01

    Long-term CO2 containment in a geological storage reservoir is a key criterion for successfully implementing carbon capture and storage (CCS), however, CO2 leakage through different pathways cannot be completely ruled out in some instances. In this study we investigate the conditions for reactive barrier formation as a technology to mitigate and remediate CO2 leakage. We propose to inject a liquid reagent consistent of an alkaline sodium-silicate solution on top of the storage caprock, which will lead to silica mineral precipitation when in contact with an acidic, CO2-enriched fluid. This reaction will create a barrier that seals the leakage by reducing the permeability. Preliminary modelling has shown that the density, viscosity and alkalinity of the reagent fluid are critical for a successful seal formation, whereas differences in formation water composition and in the rock mineral composition are less important. In order to study the reaction through experiments, different reagent solutions were prepared and characterised in terms of silica concentration, density, viscosity and buffer capacity. In a static, diffusion-controlled batch experiment we observed silica mineral precipitation in the outer layer of the piece of rock inhibiting further mixing of the two fluids and slowing down the initial reaction rate. Core-flood experiments will be carried out to simulate barrier formation under fluid flow conditions. Here, the sealing efficiency of the reaction will be continuously measured in terms of a change in permeability.

  10. Changes in reactivity and in the margins to thermal limits by the inclusion of control rods of advanced type in the Laguna Verde Power plant; Cambios en la reactividad y en los margenes a limites termicos por la inclusion de barras de control de tipo avanzado en la Central Laguna Verde

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, J.L.; Perusquia, R.; Montes, J.L.; Ortiz, J.J.; Ramirez, J.R. [ININ, Depto. de Sistemas Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)]. E-mail: jlhm@nuclear.inin.mx

    2004-07-01

    The obtained results are presented when simulating with CM-PRESTO code the cycle 10 of the unit 1 of the Laguna Verde Central, using two advanced types of control bars, besides the originally loaded ones. The two advanced types, to those that are denominated 1AV and 2AV in this work, are of different design, however both have in some place of the bar, a section with hafnium like neutron absorber material. They thought about three different scenarios, in the first one, used as reference, is simulated the cycle 10 using the original control bars, while in the other two cases the advanced types are used. The values of the reactivity were compared and of some margins to the thermal limits obtained when using the bars of advanced type, with those obtained in the case in that alone they are considered those original bars. It was found that in condition of power both advanced types present bigger absorber power of neutrons that the original bars, being quantified in average this bigger power in 0.22 pcm/notch for the type 1AV and in 0.51 pcm/notch for the type 2AV. The affectation of the margins to the observed thermal limits is minimum. (Author)

  11. Microwave assisted synthesis of fluorene-based copolymers with different conjugate degreed quinoxaline segments from reactive polymer

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jixin; Song, Xiaohui; Feng, Ying [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); Wang, Zhiming, E-mail: wangzm2011@yahoo.com.cn [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012 (China); Zhang, Xiaojuan [School of Petrochemical Engineering, Shenyang University of Technology, 30 Guanghua Street, Liaoyang 111003 (China); Shen, Fangzhong; Lu, Ping [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012 (China)

    2013-10-31

    In this work, we prepared three fluorene-based copolymers with different conjugate degreed quinoxaline segments from one reactive polymer by microwave assisted method. The obtained quinoxaline-based copolymers exhibited different bright color emissions, high photoluminescence quantum, low electron affinity and electron injection barrier. This approach not only simplified the steps of similar-structure polymers, but also avoided the monomer solubility problem. - Highlights: • Quinoxaline-based copolymers were prepared in microwave-assisted synthesis. • Polymer-synthesis containing different acceptors was simplified from reactive polymer. • Multi-functions were tuned by controlling reactive monomer structures.

  12. Los misterios del dinero

    Directory of Open Access Journals (Sweden)

    Elena Esposito

    2013-01-01

    Full Text Available El presente artículo aborda los problemas relativos a la comprensión del dinero en la sociedad moderna. En la actualidad no existe una teoría sociológica adecuada para comprender las funciones y especificidades del dinero. Frente a esto el presente artículo se propone comprender al dinero en el contexto de una dimensión temporal, específicamente como un "medio de aplazamiento". Se abordan a continuación algunas consecuencias de la monetarización de la economía de la sociedad y se analizan algunas características de la economía de los "derivados". El artículo concluye con consideraciones relativas al nuevo carácter de la economía monetaria.

  13. Hasta los últimos confines

    Directory of Open Access Journals (Sweden)

    Córdoba, Joaquín Mª

    2005-04-01

    Full Text Available El 19 de mayo de 1798, la flota encargada de trasladar el ejército que iba a conquistar Egipto levó anclas del puerto de Toulon. Aunque tres años después la aventura se saldara en fracaso, el siglo XIX comenzó así con este temprano intento francés, que consiguió dominar durante algún tiempo el Valle del Nilo, soñó abrir el Canal de Suez y decidió el desarrollo moderno de los estudios sobre la cultura islámica y el antiguo Egipto. Desde entonces y hasta la I Guerra Mundial, el mundo iba a vivir la incesante expansión europea, particularmente la de sus grandes estados como Inglaterra, Francia, Alemania y Rusia, cuyos viajeros, exploradores, colonos y ejércitos llegarían a todos los rincones del mundo…

  14. Los celtas en Celtiberia

    Directory of Open Access Journals (Sweden)

    Majolie LENERZ-DE WILDE

    2009-12-01

    Full Text Available RESUMEN: Se discute la forma en que se produjo la formación de la cultura celtibérica, bien como proceso de aculturación inducido por contactos con mercenarios celtas, o bien por inmigración de una población céltica. Sobre ese fondo se sitúan y analizan los objetos relacionables con la cultura de La Teñe, Los resultados hablan en favor de una migración, si bien numéricamente pequeña.ABSTRACT: The paper discusses the question how the Celtiberian culture may have evolved: by a process of acculturation, caused by contacts with Celtic mercenaries, or by the immigration of a Celtic population. Against this background, finds which show relations to the La Tène culture, are put together and analysed. The results point to an immigration, even if only a small one.

  15. Los nuevos movimientos sociales latinoamericanos

    National Research Council Canada - National Science Library

    Emilia Brito Valdés

    2017-01-01

    Se definen los nuevos movimientos sociales latinoamericanos en la más reciente contemporaneidad a partir de cientistas sociales de talla internacional en la medida en se han presentado como los motores de la dinámica social...

  16. SOUND FIELD DIFFUSIVITY AT THE TOP SURFACE OF SCHROEDER DIFFUSER BARRIERS

    Directory of Open Access Journals (Sweden)

    M. R. Monazzam

    2006-10-01

    Full Text Available Reactive barriers are one of the most promising and novel environmental noise barriers. In this case using Schroeder diffusers (e.g. quadratic residue diffusers on the top surface of the T-shape barrier was shown to significantly improve the performance of absorbent T-shape barriers. The reasons behind the high performance of diffuser barriers are considered in this investigation. A question about the diffusivity behavior of Schroeder diffusers when they are utilized on the top of barrier was raised. Diffusion coefficients of a diffuser in different conditions at some receiver locations were predicted by using a 2D boundary element method. It was found that the diffusion coefficient of diffuser at the top of barrier is so small that the diffusivity of the structure is almost the same as rigid T-shape barrier. To find the barrier’s cap behavior, the total field above the top surface of profile barriers was also predicted. It was found that the lowest total energy is at the receiver side of the cap very close to the top surface,which could demonstrate the effect of top surface on absorbing the energy as wave transfers from source edge toward the receiver side of the cap. In this case the amount of minimum total energy depends on the frequency and the configuration of the top surface. A comparison between the reductions of total field at the source side of the cap with the improvements of barrier’s performance was also done. It was shown that the amount of decrease in total field compared to that of an absorbent barrier “Ref” is directly associated to the amount of improvement in the insertion loss made by the diffuser barrier compared to the “Ref” barrier in the wide area on the ground at the shadow zone. Finally it was concluded that the diffuser on the top of barrier does not act as a diffuser and a kind of similarity between the contribution of diffuser and absorbent material on the top of T-profile barrier is seen.

  17. Pautas para los autores

    OpenAIRE

    2013-01-01

    Memorias es una revista de ciencias sociales y humanas que publica artículos de investigación sobre el desarrollo regional, territorial y local, considerando la articulación de los factores determinantes culturales, sociales, políticos, económicos y CTI. Su público objetivo son investigadores, grupos de investigación, profesores, y estudiantes de Colombia y otros países.

  18. Los Alamos Programming Models

    Energy Technology Data Exchange (ETDEWEB)

    Bergen, Benjamin Karl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-07

    This is the PDF of a powerpoint presentation from a teleconference on Los Alamos programming models. It starts by listing their assumptions for the programming models and then details a hierarchical programming model at the System Level and Node Level. Then it details how to map this to their internal nomenclature. Finally, a list is given of what they are currently doing in this regard.

  19. Cuento: Los mellizos

    Directory of Open Access Journals (Sweden)

    Policarpo Varón

    1967-05-01

    Full Text Available Menecmo había adquirido el hábito de caminar un rato por las calles, - después de concluír su trabajo- en las tardes, antes de regresar a su cuarto. Con las manos en los bolsillos, aspirando el humo de un cigarrillo dejaba vagar sus pies al azar. Esto le proporcionaba no pocas sorpresas, y un conocimiento de la ciudad y de sus gentes, si no envidiable, sí respetable ...

  20. general de los suelos

    Directory of Open Access Journals (Sweden)

    Greco Cid L.

    2006-01-01

    Full Text Available En este trabajo se analiza y discute la introducción y el perfeccionamiento de un conjunto de ideas y criterios para la caracterización hidrofísica de suelos en áreas pequeñas como pueden ser fincas, granjas u otras, así como a escala de parcelas experimentales. El analisis está enfocado fundamentalmente desde el punto de vista metodológico, como herramienta en la caracterización de pequeñas áreas o parcelas que requieren de estudios detallados de determinadas propiedades y fenómenos que no están disponibles en mapas o informaciones obtenidas de trabajos a gran escala. Las principales propiedades físicas que se analizan se obtienen de las relaciones de masa y volumen de los constituyentes del suelo, así como de las relaciones de los constituyentes del suelo referidos tanto al volumen externo de la muestra como al volumen de solidos y los parámetros edafológicos fundamentales utilizados en el calculo de las relaciones hídricas (agua-aire en el suelo.

  1. en los pivotes centrales

    Directory of Open Access Journals (Sweden)

    Reynaldo Roque Rodés

    2005-01-01

    Full Text Available Se hace una revisión y comentarios sobre las ventajas y limitantes del empleo del LEPA (Low Enery Precision Aplication en los sistemas de riego de pivotes centrales. Estos sistemas o filosofía de manejo del agua para condiciones de escasez o mala calidad del líquido es una alternativa viable para la producción de alimentos. Introducida en la década del 80 en las planicies del sur de Texas, donde la alta evaporación del agua y la necesidad de regar grandes áreas con pivotes centrales obligaba a la búsqueda de una alternativa para incrementar al máximo la eficiencia de aplicación del riego. Aún en fase de estudio e introducción en Cuba para áreas específicas, puede ser una solución de incremento de los rendimientos de los cultivos, empleando menos agua y aguas con calidad limitada

  2. en los medios de prensa

    Directory of Open Access Journals (Sweden)

    Luis Alejandro Nitrihual Valdebenito

    2007-01-01

    Full Text Available Este trabajo presenta los resultados de un análisis de contenido realizado a la Revista de Libros de El Mercurio entre los años 2002-2004, y muestra la importancia de la publicidad en esta revista cultural y, en general, en los medios de comunicación. Con esto queremos mostrar la relevancia que tiene la empresa publicitaria en los modernos medios de comunicación.

  3. Miranda en los estados unidos

    OpenAIRE

    Castro, Hermann

    2014-01-01

    El estudio del contexto histórico de los EstadosUnidos durante los viajes de personajes clavespara la independencia de Colombia, en estecaso Francisco de Miranda, ayuda a entender laspolíticas y percepciones de los independentistasy luego estadistas que participaron en lasprimeras relaciones internacionales entre losdos países. Se propone en este trabajo darleuna dimensión histórica a las experiencias deMiranda en los Estados Unidos.

  4. Barriers to improvements in energy efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, A.K.N.

    1991-10-01

    To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the ``barriers`` literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

  5. Barriers to improvements in energy efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, A.K.N.

    1991-10-01

    To promote energy-efficiency improvements, actions may be required at one or more levels -- from the lowest level of the consumer (residential, commercial, industrial, etc.) through the highest level of the global agencies. But barriers to the implementation of energy-efficiency improvements exist or can arise at all these levels. Taking up each one of these barriers in turn, the paper discusses specific measures that can contribute to overcoming the barriers. However, a one-barrier-one-measure approach must be avoided. Single barriers may in fact involve several sub-barriers. Also, combinations of measures are much more effective in overcoming barriers. In particular, combinations of measures that simultaneously overcome several barriers are most successful. The paper discusses the typology of barriers, explores their origin and suggests measures that by themselves or in combination with other measures, will overcome these barriers. Since most of the barriers dealt with can be found in the barriers'' literature, any originality in the paper lies in its systematic organization, synoptic view and holistic treatment of this issue. This paper is intended to initiate a comprehensive treatment of barriers, their origins and the measures that contribute to overcoming them. Hopefully, such a treatment will facilitate the implementation of energy-efficiency improvements involving a wide diversity of ever-changing energy end uses and consumer preferences.

  6. Versiones y traducciones de los cuentos de los hermanos Grimm

    OpenAIRE

    Moya Herrera, Sergio

    2015-01-01

    Versiones y traducciones de los cuentos de los hermanos Grimm es un trabajo que pretende investigar el trasfondo de los cuentos de los hermanos Grimm, «Blancanieves», «Cenicienta», «Rapunzel» y «Hansel y Gretel», para entender qué esconden las narraciones. El trabajo incluye un análisis comparativo de dos versiones en alemán de los cuentos, la primera y la última, y también un estudio de dos traducciones al español para conocer cómo se tradujeron varios elementos culturales, nombres de person...

  7. Los mercados virtuales como contraste de los mercados financieros

    OpenAIRE

    Ellafi, Saif; Vilker, Ana Silvia

    2014-01-01

    ¿Se comportan los mercados de las economías virtuales de forma similar a los mercados financieros reales? Dado que los primeros son pequeños con bienes y servicios finitos, surge la posibilidad de estudiarlos como si se trataran de abstracciones de la realidad o modelos de textos de economía y finanzas que cumplen supuestos imposibles en la realidad. Entonces, se procurará extrapolar y comparar el comportamiento de los agentes en ellas, con el de los mercados financieros para observar caracte...

  8. Versiones y traducciones de los cuentos de los hermanos Grimm

    OpenAIRE

    Moya Herrera, Sergio

    2015-01-01

    Versiones y traducciones de los cuentos de los hermanos Grimm es un trabajo que pretende investigar el trasfondo de los cuentos de los hermanos Grimm, «Blancanieves», «Cenicienta», «Rapunzel» y «Hansel y Gretel», para entender qué esconden las narraciones. El trabajo incluye un análisis comparativo de dos versiones en alemán de los cuentos, la primera y la última, y también un estudio de dos traducciones al español para conocer cómo se tradujeron varios elementos culturales, nombres de person...

  9. Effects of delocalization on intrinsic barriers for H-atom transfer: Implications for the radical hydrogen transfer reaction

    Energy Technology Data Exchange (ETDEWEB)

    Camaioni, D.M.; Autrey, S.T.; Ferris, K.F.; Franz, J.A.

    1992-08-01

    PM3 calculations of transition states (TS) for both normal H-atom transfer and radical hydrogen transfer (RHT) reactions of a a wide-variety of hydrocarbon structures have enabled development of quantitative structure-reactivity relationships. Results indicate that activation barriers for RHT reactions are large enough that thermoneutral and endothermic reactions should not compete with alternative multistep pathways.

  10. Patient advocacy: barriers and facilitators

    Directory of Open Access Journals (Sweden)

    Nikravesh Mansoure

    2006-03-01

    Full Text Available Abstract Background During the two recent decades, advocacy has been a topic of much debate in the nursing profession. Although advocacy has embraced a crucial role for nurses, its extent is often limited in practice. While a variety of studies have been generated all over the world, barriers and facilitators in the patient advocacy have not been completely identified. This article presents the findings of a study exploring the barriers and facilitators influencing the role of advocacy among Iranian nurses. Method This study was conducted by grounded theory method. Participants were 24 Iranian registered nurses working in a large university hospital in Tehran, Iran. Semi-structured interviews were used for data collection. All interviews were transcribed verbatim and simultaneously Constant comparative analysis was used according to the Strauss and Corbin method. Results Through data analysis, several main themes emerged to describe the factors that hindered or facilitated patient advocacy. Nurses in this study identified powerlessness, lack of support, law, code of ethics and motivation, limited communication, physicians leading, risk of advocacy, royalty to peers, and insufficient time to interact with patients and families as barriers to advocacy. As for factors that facilitated nurses to act as a patient advocate, it was found that the nature of nurse-patient relationship, recognizing patients' needs, nurses' responsibility, physician as a colleague, and nurses' knowledge and skills could be influential in adopting the advocacy role. Conclusion Participants believed that in this context taking an advocacy role is difficult for nurses due to the barriers mentioned. Therefore, they make decisions and act as a patient's advocate in any situation concerning patient needs and status of barriers and facilitators. In most cases, they can not act at an optimal level; instead they accept only what they can do, which we called 'limited advocacy' in

  11. Session-based concurrency, reactively

    NARCIS (Netherlands)

    M. Cano (Mauricio); J. Arias (Jaime); J.A. Pérez Parra (Jorge)

    2017-01-01

    textabstractThis paper concerns formal models for the analysis of communication-centric software systems that feature declarative and reactive behaviors. We focus on session-based concurrency, the interaction model induced by session types, which uses (variants of) the Π-calculus as specification

  12. Separability of local reactivity descriptors

    Indian Academy of Sciences (India)

    Akhilesh Tanwar; Sourav Pal

    2005-09-01

    The size-dependence of different local reactivity descriptors of dimer A2 and AB type of systems is discussed. We derive analytic results of these descriptors calculated using finite difference approximation. In particular, we studied Fukui functions, relative electrophilicity and relative nucleophilicity, local softness and local philicity. The results are explained using the example of the dimer of BH3NH3.

  13. Towards a Reactive Virtual Trainer

    NARCIS (Netherlands)

    Ruttkay, Zsófia; Zwiers, Job; Welbergen, van Herwin; Reidsma, Dennis; Gratch, J.; Young, M.; Aylett, R.; Ballin, D.; Olivier, P.

    2006-01-01

    A Reactive Virtual Trainer (RVT) is an Intelligent Virtual Agent (IVA) capable of presenting physical exercises that are to be performed by a human, monitoring the user and providing feedback at different levels. Depending on the motivation and the application context, the exercises may be general o

  14. Guillain-Barre syndrome-related Campylobacter jejuni in Bangladesh: ganglioside mimicry and cross-reactive antibodies.

    Directory of Open Access Journals (Sweden)

    Zhahirul Islam

    Full Text Available BACKGROUND: Campylobacter jejuni is the predominant antecedent infection in Guillain-Barré syndrome (GBS. Molecular mimicry and cross-reactive immune responses to C. jejuni lipo-oligosaccharides (LOS precipitate the development of GBS, although this mechanism has not been established in patients from developing countries. We determined the carbohydrate mimicry between C. jejuni LOS and gangliosides, and the cross-reactive antibody response in patients with GBS in Bangladesh. METHODOLOGY: Sera from 97 GBS patients, and 120 neurological and family controls were tested for antibody reactivity against LOS from C. jejuni isolates from GBS patients in Bangladesh (BD-07, BD-39, BD-10, BD-67 and BD-94 by enzyme-linked immunosorbent assay (ELISA. Cross-reactivity to LOS was determined by ELISA. The LOS outer core structures of C. jejuni strains associated with GBS/MFS were determined by mass spectrometry. PRINCIPLE FINDINGS: IgG antibodies to LOS from C. jejuni BD-07, BD-39, BD-10, and BD-67 IgG antibodies were found in serum from 56%, 58%, 14% and 15% of GBS patients respectively, as compared to very low frequency (<3% in controls (p<0.001. Monoclonal antibodies specific for GM1 and GD1a reacted strongly with LOS from the C. jejuni strains (BD-07 and BD-39. Mass spectrometry analysis confirmed the presence of GM1 and GD1a carbohydrate mimics in the LOS from C. jejuni BD-07 and BD-39. Both BD-10 and BD-67 express the same LOS outer core, which appears to be a novel structure displaying GA2 and GD3 mimicry. Up to 90-100% of serum reactivity to gangliosides in two patients (DK-07 and DK-39 was inhibited by 50 µg/ml of LOS from the autologous C. jejuni isolates. However, patient DK-07 developed an anti-GD1a immune response while patient DK-39 developed an anti-GM1 immune response. CONCLUSION: Carbohydrate mimicry between C. jejuni LOS and gangliosides, and cross-reactive serum antibody precipitate the majority of GBS cases in Bangladesh.

  15. Guillain-Barré syndrome-related Campylobacter jejuni in Bangladesh: ganglioside mimicry and cross-reactive antibodies.

    Science.gov (United States)

    Islam, Zhahirul; Gilbert, Michel; Mohammad, Quazi D; Klaij, Kevin; Li, Jianjun; van Rijs, Wouter; Tio-Gillen, Anne P; Talukder, Kaisar A; Willison, Hugh J; van Belkum, Alex; Endtz, Hubert P; Jacobs, Bart C

    2012-01-01

    Campylobacter jejuni is the predominant antecedent infection in Guillain-Barré syndrome (GBS). Molecular mimicry and cross-reactive immune responses to C. jejuni lipo-oligosaccharides (LOS) precipitate the development of GBS, although this mechanism has not been established in patients from developing countries. We determined the carbohydrate mimicry between C. jejuni LOS and gangliosides, and the cross-reactive antibody response in patients with GBS in Bangladesh. Sera from 97 GBS patients, and 120 neurological and family controls were tested for antibody reactivity against LOS from C. jejuni isolates from GBS patients in Bangladesh (BD-07, BD-39, BD-10, BD-67 and BD-94) by enzyme-linked immunosorbent assay (ELISA). Cross-reactivity to LOS was determined by ELISA. The LOS outer core structures of C. jejuni strains associated with GBS/MFS were determined by mass spectrometry. IgG antibodies to LOS from C. jejuni BD-07, BD-39, BD-10, and BD-67 IgG antibodies were found in serum from 56%, 58%, 14% and 15% of GBS patients respectively, as compared to very low frequency (<3%) in controls (p<0.001). Monoclonal antibodies specific for GM1 and GD1a reacted strongly with LOS from the C. jejuni strains (BD-07 and BD-39). Mass spectrometry analysis confirmed the presence of GM1 and GD1a carbohydrate mimics in the LOS from C. jejuni BD-07 and BD-39. Both BD-10 and BD-67 express the same LOS outer core, which appears to be a novel structure displaying GA2 and GD3 mimicry. Up to 90-100% of serum reactivity to gangliosides in two patients (DK-07 and DK-39) was inhibited by 50 µg/ml of LOS from the autologous C. jejuni isolates. However, patient DK-07 developed an anti-GD1a immune response while patient DK-39 developed an anti-GM1 immune response. Carbohydrate mimicry between C. jejuni LOS and gangliosides, and cross-reactive serum antibody precipitate the majority of GBS cases in Bangladesh.

  16. Dielectric barrier discharges applied for optical spectrometry

    Science.gov (United States)

    Brandt, S.; Schütz, A.; Klute, F. D.; Kratzer, J.; Franzke, J.

    2016-09-01

    The present review reflects the importance of dielectric barrier discharges for optical spectrometric detection in analytical chemistry. In contrast to usual discharges with a direct current the electrodes are separated by at least one dielectric barrier. There are two main features of the dielectric barrier discharges: they can serve as dissociation and excitation devices as well as ionization sources, respectively. This article portrays various application fields of dielectric barrier discharges in analytical chemistry used for elemental and molecular detection with optical spectrometry.

  17. An easy method for the determination of active concentrations of cholinesterase reactivators in blood samples: Application to the efficacy assessment of non quaternary reactivators compared to HI-6 and pralidoxime in VX-poisoned mice.

    Science.gov (United States)

    Calas, André-Guilhem; Dias, José; Rousseau, Catherine; Arboléas, Mélanie; Touvrey-Loiodice, Mélanie; Mercey, Guillaume; Jean, Ludovic; Renard, Pierre-Yves; Nachon, Florian

    2016-03-10

    Organophosphorus nerve agents, like VX, are highly toxic due to their strong inhibition potency against acetylcholinesterase (AChE). AChE inhibited by VX can be reactivated using powerful nucleophilic molecules, most commonly oximes, which are one major component of the emergency treatment in case of nerve agent intoxication. We present here a comparative in vivo study on Swiss mice of four reactivators: HI-6, pralidoxime and two uncharged derivatives of 3-hydroxy-2-pyridinaldoxime that should more easily cross the blood-brain barrier and display a significant central nervous system activity. The reactivability kinetic profile of the oximes is established following intraperitoneal injection in healthy mice, using an original and fast enzymatic method based on the reactivation potential of oxime-containing plasma samples. HI-6 displays the highest reactivation potential whatever the conditions, followed by pralidoxime and the two non quaternary reactivators at the dose of 50 mg/kg bw. But these three last reactivators display equivalent reactivation potential at the same dose of 100 μmol/kg bw. Maximal reactivation potential closely correlates to surviving test results of VX intoxicated mice.

  18. Próxima NIIF 15: 'Los ingresos de los contratos con los clientes'

    OpenAIRE

    Rodríguez García, Ferran

    2014-01-01

    Los dos principales emisores de normas internacionales de información financiera, el International Accounting Standards Board (IASB) y el Financial Accounting Standards Board (FASB) de los EUA han emitido, a finales del pasado mes de mayo y coordinadamente, sendas y respectivas normas de contenido común en las que se regula el reconocimiento contable de los ingresos ordinarios de las empresas procedentes de los contratos establecidos con clientes. Ambas normas resultaran de aplicación efectiv...

  19. Próxima NIIF 15: 'Los ingresos de los contratos con los clientes'

    OpenAIRE

    Rodríguez García, Ferran

    2014-01-01

    Los dos principales emisores de normas internacionales de información financiera, el International Accounting Standards Board (IASB) y el Financial Accounting Standards Board (FASB) de los EUA han emitido, a finales del pasado mes de mayo y coordinadamente, sendas y respectivas normas de contenido común en las que se regula el reconocimiento contable de los ingresos ordinarios de las empresas procedentes de los contratos establecidos con clientes. Ambas normas resultaran de aplicación efectiv...

  20. Las democracias como los bosques

    Directory of Open Access Journals (Sweden)

    Tomás Rodríguez Villasante

    2005-03-01

    Full Text Available La idea de comparar a las democracias con los bosques surgió de los trabajos sobre ecofeminismo de Vandana Shiva. A semejanza de los ecosistemas, los elementos internos se pueden estar reforzando y generando sinergias y creatividad, o todo lo contrario. La cuestión es qué tipo de relaciones se están dando entre los elementos. Las democracias no pueden ser sólo unas declaraciones formales, un organigrama jerárquico, o unos procedimientos rutinarios y ceremoniales.

  1. Los Poblados Dirigidos de Madrid

    Directory of Open Access Journals (Sweden)

    Ana M. Esteban

    1999-07-01

    Full Text Available Los Poblados Dirigidos madrileños de los años cincuenta constituyeron una experiencia única dentro del panorama arquitectónico de la posguerra. La implicación personal de algunos de nuestros mejores arquitectos y de los autoconstructores de su propia vivienda aportó un carácter singular a las intervenciones. El artículo propone un recorrido por estos barrios en los que la modernidad aparece como nueva alternativa para solucionar el problema creciente de los asentamientos chabolistas periféricos.

  2. Efectos psicosociales de los videojuegos

    OpenAIRE

    Tejeiro Salguero, Ricardo; Pelegrina del Río, Manuel; Gómez Vallecillo, Jorge Luis

    2009-01-01

    Desde su aparición en los años 70, los posibles efectos psicosociales de los videojuegos, positivos o negativos, han sido objeto de una considerable polémica. La mayoría de los argumentos en uno u otro sentido se han basado más en opiniones personales y prejuicios que en los datos de investigación. En este artículo revisamos el estado de la cuestión en relación con estos argumentos, tanto negativos (adicción, agresividad, aislamiento social, rendimiento escolar, desplazamiento de otras ...

  3. Penetration through the Skin Barrier

    DEFF Research Database (Denmark)

    Nielsen, Jesper Bo; Benfeldt, Eva; Holmgaard, Rikke

    2016-01-01

    . During recent decades, the latter has received increased attention as a route for intentionally delivering drugs to patients. This has stimulated research in methods for sampling, measuring and predicting percutaneous penetration. Previous chapters have described how different endogenous, genetic...... and exogenous factors may affect barrier characteristics. The present chapter introduces the theory for barrier penetration (Fick's law), and describes and discusses different methods for measuring the kinetics of percutaneous penetration of chemicals, including in vitro methods (static and flow......-through diffusion cells) as well as in vivo methods (microdialysis and microperfusion). Then follows a discussion with examples of how different characteristics of the skin (age, site and integrity) and of the penetrants (size, solubility, ionization, logPow and vehicles) affect the kinetics of percutaneous...

  4. Security barriers with automated reconnaissance

    Science.gov (United States)

    McLaughlin, James O; Baird, Adam D; Tullis, Barclay J; Nolte, Roger Allen

    2015-04-07

    An intrusion delaying barrier includes primary and secondary physical structures and can be instrumented with multiple sensors incorporated into an electronic monitoring and alarm system. Such an instrumented intrusion delaying barrier may be used as a perimeter intrusion defense and assessment system (PIDAS). Problems with not providing effective delay to breaches by intentional intruders and/or terrorists who would otherwise evade detection are solved by attaching the secondary structures to the primary structure, and attaching at least some of the sensors to the secondary structures. By having multiple sensors of various types physically interconnected serves to enable sensors on different parts of the overall structure to respond to common disturbances and thereby provide effective corroboration that a disturbance is not merely a nuisance or false alarm. Use of a machine learning network such as a neural network exploits such corroboration.

  5. Article Including Environmental Barrier Coating System

    Science.gov (United States)

    Lee, Kang N. (Inventor)

    2015-01-01

    An enhanced environmental barrier coating for a silicon containing substrate. The enhanced barrier coating may include a bond coat doped with at least one of an alkali metal oxide and an alkali earth metal oxide. The enhanced barrier coating may include a composite mullite bond coat including BSAS and another distinct second phase oxide applied over said surface.

  6. Barrierer for realisering af energibesparelser i bygninger

    DEFF Research Database (Denmark)

    Jensen, Ole Michael

    2004-01-01

    For få bygningsejere går i gang med at investere i energibesparelser. Årsagen tilskrives en række barrierer, som møder den enkelte bygningsejer, når denne vil i gang med at foretage energirenoveringer. Men ikke alle barrierer handler om barrierer i traditionel forstand, men om tilbageholdenhed. Den...

  7. Market barriers to welfare product innovations

    NARCIS (Netherlands)

    Binnekamp, M.H.A.; Ingenbleek, P.T.M.

    2006-01-01

    New products that are based on higher animal welfare standards encounter several barriers on the road to market acceptance. The authors focus on the Dutch poultry sector and distinguish between retailer and consumer barriers. Retailer barriers include the powerful position of retailers, the price co

  8. Design of the Muong Chuoi Barrier

    NARCIS (Netherlands)

    Van Vliegen, K.; Van Oorschot, N.; Meinen, N.; Van Dijk, S.; Reimert, Z.

    2013-01-01

    Ho Chi Minh City has to deal with severe flooding in the rainy season. To prevent the city from this flooding, MARD set up plan 1547. The main idea of the plan is to build a ring dike around HCMC in combination with several movable tidal barriers. One of these barriers is the Muong Chuoi Barrier. I

  9. Barriers to Mammography among Inadequately Screened Women

    Science.gov (United States)

    Stoll, Carolyn R. T.; Roberts, Summer; Cheng, Meng-Ru; Crayton, Eloise V.; Jackson, Sherrill; Politi, Mary C.

    2015-01-01

    Mammography use has increased over the past 20 years, yet more than 30% of women remain inadequately screened. Structural barriers can deter individuals from screening, however, cognitive, emotional, and communication barriers may also prevent mammography use. This study sought to identify the impact of number and type of barriers on mammography…

  10. Market barriers to welfare product innovations

    NARCIS (Netherlands)

    Binnekamp, M.H.A.; Ingenbleek, P.T.M.

    2006-01-01

    New products that are based on higher animal welfare standards encounter several barriers on the road to market acceptance. The authors focus on the Dutch poultry sector and distinguish between retailer and consumer barriers. Retailer barriers include the powerful position of retailers, the price

  11. Flexible pile thermal barrier insulator

    Science.gov (United States)

    Anderson, G. E.; Fell, D. M.; Tesinsky, J. S. (Inventor)

    1978-01-01

    A flexible pile thermal barrier insulator included a plurality of upstanding pile yarns. A generally planar backing section supported the upstanding pile yarns. The backing section included a plurality of filler yarns forming a mesh in a first direction. A plurality of warp yarns were looped around said filler yarns and pile yarns in the backing section and formed a mesh in a second direction. A binder prevented separation of the yarns in the backing section.

  12. Overcome barriers to career success

    Energy Technology Data Exchange (ETDEWEB)

    Raudsepp, E.

    1983-04-01

    A test is given to determine if an engineer suffers from one of the three barriers to technical success: fear of success, fear of failure, or perfectionism. As in most such tests, the middle way is best. Successful engineers know that perfection cannot be attained, that they don't have time to worry about failure or success, and that by aiming and perservering in doing things well, success can be achieved.

  13. Removing Barriers to Interdisciplinary Research

    CERN Document Server

    Jacobs, Naomi

    2010-01-01

    A significant amount of high-impact contemporary scientific research occurs where biology, computer science, engineering and chemistry converge. Although programmes have been put in place to support such work, the complex dynamics of interdisciplinarity are still poorly understood. In this paper we interrogate the nature of interdisciplinary research and how we might measure its "success", identify potential barriers to its implementation, and suggest possible mechanisms for removing these impediments.

  14. Wet Work and Barrier Function.

    Science.gov (United States)

    Fartasch, Manigé

    2016-01-01

    Wet work defined as unprotected exposure to humid environments/water; high frequencies of hand washing procedures or prolonged glove occlusion is believed to cause irritant contact dermatitis in a variety of occupations. This review considers the recent studies on wet-work exposure and focuses on its influence on barrier function. There are different methods to study the effect of wet work on barrier function. On the one hand, occupational cohorts at risk can be monitored prospectively by skin bioengineering technology and clinical visual scoring systems; on the other hand, experimental test procedures with defined application of water, occlusion and detergents are performed in healthy volunteers. Both epidemiological studies and the results of experimental procedures are compared and discussed. A variety of epidemiological studies analyze occupational cohorts at risk. The measurement of transepidermal water loss, an indicator of the integrity of the epidermal barrier, and clinical inspection of the skin have shown that especially the frequencies of hand washing and water contact/contact to aqueous mixtures seem to be the main factors for the occurrence of barrier alterations. On the other hand, in a single cross-sectional study, prolonged glove wearing (e.g. occlusion for 6 h per shift in clean-room workers) without exposure to additional hazardous substances seemed not to affect the skin negatively. But regarding the effect of occlusion, there is experimental evidence that previously occluded skin challenged with sodium lauryl sulfate leads to an increased susceptibility to the irritant with an aggravation of the irritant reaction. These findings might have relevance for the real-life situation in so far as after occupational glove wearing, the skin is more susceptible to potential hazards to the skin even during leisure hours.

  15. Lake Borgne Surge Barrier Study

    Science.gov (United States)

    2010-09-01

    Savant , and Darla C. McVan September 2010 Approved for public release; distribution is unlimited. ERDC/CHL TR-10-10 September 2010 Lake...Borgne Surge Barrier Study S. Keith Martin, Gaurav Savant , and Darla C. McVan Coastal and Hydraulics Laboratory U.S. Army Engineer Research and...conducted by Keith Martin, Dr. Gaurav Savant , and Darla C. McVan. This work was conducted at the Coastal and Hydraulics Laboratory (CHL) of the

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

    Science.gov (United States)

    2010-01-01

    quantification limit PCD Pueblo Chemical Depot PID photoionization detector PI Principal Investigator PRB permeable reactive barrier PVC Polyvinyl...substrate (lactate) immediately downgradient of the former ponds • Injection of additional emulsified vegetable oil in a series of 10-20 transects...Sale (Wyoming PG-1954). Monitoring wells were constructed of 1-inch PVC pipe and 10-slot well screens. A 20-40 quartz filter sand was installed

  17. Los misterios del dinero

    OpenAIRE

    Elena Esposito

    2013-01-01

    El presente artículo aborda los problemas relativos a la comprensión del dinero en la sociedad moderna. En la actualidad no existe una teoría sociológica adecuada para comprender las funciones y especificidades del dinero. Frente a esto el presente artículo se propone comprender al dinero en el contexto de una dimensión temporal, específicamente como un "medio de aplazamiento". Se abordan a continuación algunas consecuencias de la monetarización de la economía de la sociedad y se analizan alg...

  18. Los Delitos especiales

    OpenAIRE

    2003-01-01

    La presente investigación se divide en tres Partes. La Primera Parte se ocupa del concepto de delito especial. En ella se defiende un concepto de delito especial simple y dependiente de la autoría y la tentativa. Lo primero obedece a la pluralidad de fundamentos de los delitos especiales. Lo segundo, por una parte, a que no cualquier concepto de autor, sino sólo un concepto restrictivo es compatible con el concepto de delito especial; y, por otra, a que, aunque ello no es lógicamente necesari...

  19. Delitos especiales, Los

    OpenAIRE

    2003-01-01

    La presente investigación se divide en tres Partes. La Primera Parte se ocupa del concepto de delito especial. En ella se defiende un concepto de delito especial simple y dependiente de la autoría y la tentativa. Lo primero obedece a la pluralidad de fundamentos de los delitos especiales. Lo segundo, por una parte, a que no cualquier concepto de autor, sino sólo un concepto restrictivo es compatible con el concepto de delito especial; y, por otra, a que, aunque ello no es lógicamente necesari...

  20. Los cinco sentidos

    OpenAIRE

    Tamir, Abraham; Ruiz Beviá, Francisco

    2014-01-01

    Percibimos el mundo que nos rodea por medio de nuestros cinco sentidos principales, la vista, el oído, el tacto, el gusto y el olfato. Los sentidos alimentan nuestro cerebro con bits de información que nos ayudan a construir una imagen del complicado mundo que nos rodea. Científicamente un sentido se define como un medio de recibir información del mundo exterior o de nuestro cuerpo y convertirla en un código electroquímico que es procesado por el cerebro.

  1. Los hermanos Graco

    OpenAIRE

    Antolínez Escudero, Adrián

    2016-01-01

    Las figuras delos hermanos Graco son unas de las más debatidas y cuestionadas de la historia, no solo de la historia de Roma, sino de la misma historia de Europa. Vivieron en tiempos convulsos, pues la República de Roma empezaba a mostrar signos evidentes de agotamiento, dando sus últimos coletazos, que supusieron la puerta de entrada para el surgimiento del que posteriormente se conocería como Imperio Romano. Los factores que ayudaron a acabar con el régimen republicano romano son variados, ...

  2. Los movimientos migratorios

    OpenAIRE

    Naranjo-Ramírez, J.

    1994-01-01

    Estudio del comportamiento migratorio de Córdoba capital, tradicional centro de recepción de población procedentes de la geografía provincial y, a la vez, importante foco emisor de emigración durante las décadas de 1950 a 1970. Respecto a ésta última se considera tanto la corriente migratoria interna (a otras regiones de España) como externa (dirigida al extranjero), considerando los destinos más habituales y la estructura demográfica del contingente migratorio. Igualmente se considera el ini...

  3. Cuando los mundos chocan

    Directory of Open Access Journals (Sweden)

    García-Borrás, F.J.

    2006-04-01

    Full Text Available Desde una perspectiva netamente didáctica, en este artículo se pretende analizar las posibilidades e incidencias que la ciencia-ficción2 puede tener en el aula. El período de la adolescencia encuentra en la ciencia-ficción una forma de explicar sus necesidades y sus ideas previas. Por tanto, para facilitar sus procesos de aprendizaje, al mismo tiempo que los profesores pueden ver enriquecida su metodología de enseñanza, se muestran diversas fórmulas de acercamiento al alumno por medio de un motivador entorno de aprendizaje.

  4. Coccidiosis en los animales

    OpenAIRE

    Sánchez Herrera, Manuel

    2011-01-01

    Los trabajos llevados a cabo por mí sobre coccidiosis en el Departamento de Anatomía Comparada de la Escuela de Medicina de Harvard, me dan tema para llenar el requisito reglamentario en el concurso extraordinario para Profesores Agregados en el presente año.' Las experiencias fueron hechas en 1931 bajo la direccién del Profesor de Anatomía Comparada, Dr. Ernest Edward Tyzzer, y se emplearon más o menos 150 pollos de 6 a 73 días de edad. La historia clínica de cada pollo comprendía su edad, s...

  5. Flexible Reactive Berm (FRBerm) for Removal of Heavy Metals from Runoff Water

    Science.gov (United States)

    2016-03-01

    minerals, goethite and hematite , and remained immobilized (Ford et al. 1997, Martinez and McBride 1998). 2 Copper, Pb, Ni, and Zn have also been...width), m h = water depth immediately upstream of the filter, m The primary hydraulic features of sand filter socks are shown in Figure 6, where, v...untreated storm runoff water into the entire length of the trench. Therefore, each reactive barrier in the trench functioned more as a primary

  6. Perceived Sodium Reduction Barriers Among Patients with Chronic Kidney Disease: Which Barriers Are Important and Which Patients Experience Barriers?

    Science.gov (United States)

    Meuleman, Yvette; Hoekstra, Tiny; Dekker, Friedo W; van der Boog, Paul J M; van Dijk, Sandra

    2017-09-08

    The purposes of this study were to assess the importance of perceived sodium reduction barriers among patients with chronic kidney disease (CKD) and identify associated sociodemographic, clinical, and psychosocial factors. A total of 156 patients with CKD completed a questionnaire assessing sodium reduction barriers (18 self-formulated items), depressive symptoms (Beck Depression Inventory), perceived autonomy support (Modified Health Care Climate Questionnaire), and self-efficacy (Partners in Health Questionnaire). Factor analysis was used to identify barrier domains. Correlation coefficients were computed to examine relationships between barrier domains and patient characteristics. Nine barrier domains were identified. Barriers perceived as important were as follows: high sodium content in products, lack of sodium feedback, lack of goal setting and discussing strategies for sodium reduction, and not experiencing CKD-related symptoms (mean scores > 3.0 on 5-point scales, ranging from 1 'no barrier' to 5 'very important barrier'). Other barriers (knowledge, attitude, coping skills when eating out, and professional support) were rated as moderately important (rated around midpoint), and the barrier 'intrinsic motivation' was rated as somewhat important (mean score = 1.9). Sodium reduction barrier domains were not associated with gender and kidney function, but were associated with age, level of education, number of comorbidities, perceived autonomy support, depressive symptoms, and self-efficacy (range r = 0.17-0.35). Patients with lower self-efficacy and perceived autonomy support scores experienced most sodium reduction barriers. Patients with CKD experience multiple important sodium reduction barriers and could benefit from support strategies that target various sodium reduction barriers and strengthen beliefs regarding self-efficacy and autonomy support. Additionally, environmental interventions should be implemented to reduce sodium levels in processed

  7. The feasibility of a permeable reactive barrier to treat acidic sulphate ...

    African Journals Online (AJOL)

    2006-04-02

    Apr 2, 2006 ... Treatment of this water is therefore necessary before discharge. In situ passive ... conventional treatment technologies for acidic groundwater. Feasibility criteria ..... 112 351-359. SRK (2001) Status Quo Report for Waste Sites.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Remediation of Explosives in Groundwater Using a Zero-Valent Iron Permeable Reactive Barrier

    Science.gov (United States)

    2008-05-01

    contained 10 mL of 0.5 M NaOH . To collect the AVS, 10 mL of 1 M HCl were added to the first vial, resulting in the volatilization of all AVS, as...chromatog. pH 7-7.2 Electrode Eh -40 - -130 mV Electrode DO 0.0 – 0.2 mg/L Electrode Alkalinity 300-800 mg/L Hach titration Specific Conductance...well as carbonates. The AVS were then trapped in the NaOH and analyzed by the Hach colorometric sulfide method. X-ray Photoelectron Spectroscopy X

  10. Permanganate Treatment of DNAPLs in Reactive Barriers and Source Zone Flooding Schemes

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Franklin Schwartz; Dr. Hubao Zhang

    2003-12-23

    Permanganate is a simple and common chemical, which has proven useful in oxidizing common chlorinated solvents. Due to the nature of oxidation, the byproducts and products are much less harmful than those from reduction-type remedial schemes, and the degradation process is rapid. The main goal of this project is to understand oxidative destruction of chlorinated solvents using potassium permanganate. The study has provided a theoretical basis for evaluating the feasibility of in-situ applications, to couple kinetic reaction with transport models, and to develop an appropriate field test for further assessing the approach.

  11. Class barriers to psychotherapy and counselling.

    Science.gov (United States)

    Ollerton, I

    1995-01-01

    This paper focuses on the barriers to the uptake of counselling and psychotherapy from a social class perspective. It begins with a definition of class before discussing particular aspects that inhibit uptake. Barriers focused upon are those regarding travel, costs, child care, appointment times and location of actual therapists. Likewise barriers to the effective outcome, for example cognitive and verbal abilities of clients, are addressed and the way in which these barriers inhibit the referral rate from particular social groups. Finally the self-imposed barriers of certain social groups are explored regarding self exile from the counselling arena.

  12. Diffraction of sound by nearly rigid barriers

    Science.gov (United States)

    Hadden, W. J., Jr.; Pierce, A. D.

    1976-01-01

    The diffraction of sound by barriers with surfaces of large, but finite, acoustic impedance was analyzed. Idealized source-barrier-receiver configurations in which the barriers may be considered as semi-infinite wedges are discussed. Particular attention is given to situations in which the source and receiver are at large distances from the tip of the wedge. The expression for the acoustic pressure in this limiting case is compared with the results of Pierce's analysis of diffraction by a rigid wedge. An expression for the insertion loss of a finite impedance barrier is compared with insertion loss formulas which are used extensively in selecting or designing barriers for noise control.

  13. Mathematical modeling of complex noise barriers

    Energy Technology Data Exchange (ETDEWEB)

    Hayek, S.I.

    1982-01-01

    Mathematical modeling of the noise reduction efficiency of highway noise barriers depends on the shape and absorptivity of the barrier, the influence of the impedance of the ground under the receiver, the atmospheric conditions as well as traffic details. The mathematical model for a barrier's noise reduction requires the knowledge of point-to-point acoustic diffraction models. In many instances, the shape of the barrier is simple; such as thin wall (edge), sharp wedge, and cylindrically topped berms. However, new designs of more efficient barriers have been investigated recently.

  14. Los colgantes renacentistas

    Directory of Open Access Journals (Sweden)

    Natalia Horcajo Palomero

    1998-01-01

    Full Text Available La Joyería europea del siglo XVI es una disciplina muy compleja por el número de piezas que han llegado hasta nosotros, y porque muchas de ellas tienen un tema representado en su parte central. De todos los tipos de joyas, en este trabajo se analiza el denominado joyel o colgante renacentista, un colgante de forma cruciforme, en oro esmaltado trabajado con motivos decorativos del Renacimiento y decorado con piedras preciosas engarzadas entre ellos. Presenta tres tipos, el más sencillo, que le da nombre, el que tiene un tema desarrollado entre los motivos y el que muestra una hornacina con figuras en su parte central. Su análisis en cuanto ejemplares, su localización en diseños, documentos y retratos, constituye el argumento de este artículo.The Renaissance jewellery is very complete. We know a lot ofjeweis of different types and there are very much themes on them. Between the types, in this article we study the denominated joyel or Renaissance pendent, a cruciform pendent in enameled gold with Renaissance decorative motives, with precious stones linked on them. This pendent presents hree types. The most symple,one that has some theme on it and, a third wich has a niche with figures. The study of these jeweis and their localization on designe, documente and portraits, is the end of this work.

  15. LOS MEDICOS POETAS

    Directory of Open Access Journals (Sweden)

    Academia Nacional de Medicina

    1979-06-01

    Full Text Available

    JOSE FERNANDEZ MADRID

    Nació en Cartagena el 19 de febrero de 1789, Y murió en Londres el 28 de junio de 1830. Fue el cantor de Bolívar y los próceres, el poeta delicado de escenas hogareñas, el sentido autor de I dulces elegías amorosas. Con sus tragedias en verso Atala y Guatimocín, fue uno de los precursores de nuestro teatro. (José J. Ortega Torres, Poesía Colombiana, 1942.


    JOAQUIN GONZALEZ CAMARGO

    Nació en Sogamoso el 15 de enero de 1865. Fue médico y poeta como Ricardo Gutiérrez el argentino, como Manuel Acuña, el mejicano. El 9 de diciembre de 1886, en Zipaquirá, vió truncarse al golpe de la muerte sus veintiún años, llenos de ideales y de promesas. Dos composiciones le sobreviven como gala de nuestro parnaso: Estudiando y Viaje de la luz. Esta
    fue considerada por don Juan Valera como superior a las rimas de Bécquer y de Heine. (José J. Ortega Torres, Poesía Colombiana, 1942...

  16. Los Anhelos Del Agro

    Directory of Open Access Journals (Sweden)

    Chaparro G. A.

    1942-08-01

    Full Text Available Hablemos hoy del campesino y de su desventura, y hagámoslo, perfectamente libres de toda insana y falaz intención demagógica. Démosle el frente con resolución a esa obscura costumbre de halagar las pasiones de las gentes y explotar con fines proclives las profundas esperanzas y los honrados anhelos de los campesinos, y digamos que en Colombia, y en muchos países de América, se ha abusado impunemente de esa masa resignada que sustenta las economías de estos países, y se ha desconocido el meollo verdadero de sus problemas fundamentales, sin que las fórmulas prácticas de resolvemos íntegramente hayan aparecido, limitándose la acción a meras iniciativas aisladas e inconexas a veces contradictorias, cuyos resultados quedan perdidos en medio de la magnitud total de las situaciones.

  17. Los Cuadernos INTEMAC

    Directory of Open Access Journals (Sweden)

    Calavera Vayá, Ana

    2008-06-01

    Full Text Available Since it’s foundation in June 1967 the Technical Institute for Materials and Construction (INTEMAC established the incentivation of technical training and the researching vocation of it’s staff as it’s goals. For the past eighteen years INTEMAC’s quarterlies have represented the shaping of this spirit, for what the Institute has become well known in the building business. Covering more and more topics every year, the sixty-six titles which have been published until now have all been dedicated to a big variety of issues such as the pre-standardization, the creation of guides of practical application on specific subjects, pathology or the building works of a certain importance inside the national panorama. Trying to maintain, altogether, a certain balance between edification issues, civil construction and rehabilitation of already existing buildings.The publication of INTEMAC’s quarterly has never stopped, with a three-month periodicity, programmed with a lot of anticipation, and a bilingual edition in Spanish and English, which is around 2500 copies nowadays. The following text tries to be a mirror of the evolution of this publication throughout time, with a few comments which will help the reader guess what we expect from the future days.Desde su fundación, en Junio de 1967, el Instituto Técnico de Materiales y Construcciones (INTEMAC estableció como uno de sus objetivos la incentivación de la formación técnica y de la vocación investigadora de su plantilla. Durante los últimos dieciocho años los Cuadernos INTEMAC han representado la plasmación de este espíritu, por el que el Instituto ha llegado a ser bien conocido en el mundo de la Construcción. Cubriendo campos cada vez más amplios, los 66 números publicados hasta ahora se han dedicado a asuntos tan variados como la pre-normativa, la creación de guías de aplicación práctica sobre temas concretos, la patología o las obras de una especial importancia

  18. A Preliminary Analysis of the Economics of Using Distributed Energy as a Source of Reactive Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fangxing [ORNL; Kueck, John D [ORNL; Rizy, D Tom [ORNL; King, Thomas F [ORNL

    2006-04-01

    A major blackout affecting 50 million people in the Northeast United States, where insufficient reactive power supply was an issue, and an increased number of filings made to the Federal Energy Regulatory Commission by generators for reactive power has led to a closer look at reactive power supply and compensation. The Northeastern Massachusetts region is one such area where there is an insufficiency in reactive power compensation. Distributed energy due to its close proximity to loads seems to be a viable option for solving any present or future reactive power shortage problems. Industry experts believe that supplying reactive power from synchronized distributed energy sources can be 2 to 3 times more effective than providing reactive support in bulk from longer distances at the transmission or generation level. Several technology options are available to supply reactive power from distributed energy sources such as small generators, synchronous condensers, fuel cells or microturbines. In addition, simple payback analysis indicates that investments in DG to provide reactive power can be recouped in less than 5 years when capacity payments for providing reactive power are larger than $5,000/kVAR and the DG capital and installation costs are lower than $30/kVAR. However, the current institutional arrangements for reactive power compensation present a significant barrier to wider adoption of distributed energy as a source of reactive power. Furthermore, there is a significant difference between how generators and transmission owners/providers are compensated for reactive power supplied. The situation for distributed energy sources is even more difficult, as there are no arrangements to compensate independent DE owners interested in supplying reactive power to the grid other than those for very large IPPs. There are comparable functionality barriers as well, as these smaller devices do not have the control and communications requirements necessary for automatic

  19. Centrally acting oximes in reactivation of tabun-phosphoramidated AChE.

    Science.gov (United States)

    Kovarik, Zrinka; Maček, Nikolina; Sit, Rakesh K; Radić, Zoran; Fokin, Valery V; Barry Sharpless, K; Taylor, Palmer

    2013-03-25

    Organophosphates (OP) inhibit acetylcholinesterase (AChE, EC 3.1.1.7), both in peripheral tissues and central nervous system (CNS), causing adverse and sometimes fatal effects due to the accumulation of neurotransmitter acetylcholine (ACh). The currently used therapy, focusing on the reactivation of inhibited AChE, is limited to peripheral tissues because commonly used quaternary pyridinium oxime reactivators do not cross the blood brain barrier (BBB) at therapeutically relevant levels. A directed library of thirty uncharged oximes that contain tertiary amine or imidazole protonable functional groups that should cross the BBB as unionized species was tested as tabun-hAChE conjugate reactivators along with three reference oximes: DAM (diacetylmonoxime), MINA (monoisonitrosoacetone), and 2-PAM. The oxime RS150D [N-((1-(3-(2-((hydroxyimino)methyl)-1H-imidazol-1-yl)propyl)-1H-1,2,3-triazol-4-yl)methyl)benzamide] was highlighted as the most promising reactivator of the tabun-hAChE conjugate. We also observed that oximes RS194B [N-(2-(azepan-1-yl)ethyl)-2-(hydroxyimino)acetamide] and RS41A [2-(hydroxyimino)-N-(2-(pyrrolidin-1-yl)ethyl)acetamide], which emerged as lead uncharged reactivators of phosphylated hAChE with other OPs (sarin, cyclosarin and VX), exhibited only moderate reactivation potency for tabun inhibited hAChE. This implies that geometry of oxime access to the phosphorus atom conjugated to the active serine is an important criterion for efficient reactivation, along with the chemical nature of the conjugated moiety: phosphorate, phosphonate, or phosphoramidate. Moreover, modification of the active center through mutagenesis enhances the rates of reactivation. The phosphoramidated-hAChE choline-binding site mutant Y337A showed three-times enhanced reactivation capacity with non-triazole imidazole containing aldoximes (RS113B, RS113A and RS115A) and acetamide derivative (RS194B) than with 2PAM.

  20. Avoiding barriers in control of mowing robot

    Institute of Scientific and Technical Information of China (English)

    QIU Bai-jing; QIAN Guo-hong; XIANG Zhong-ping; LI Zuo-peng

    2006-01-01

    Due to complicated barriers,it is difficult to track the path of the mowing robot and to avoid barriers.In order to solve the problem,a method based on distance-measuring sensors and fuzzy control inputs was proposed.Its track was composed of beelines and was easy to tail.The fuzzy control inputs were based on the front barrier distance and the difference between the left and right barrier distance measured by ultrasonic sensors;the output was the direction angle.The infrared sensors around the robot improved its safety in avoiding barriers.The result of the method was feasible,agile,and stable.The distance between the robot and the barriers could be changed by altering the inputs and outputs of fuzzy control and the length of the beelines.The disposed sensors can fulfill the need of the robot in avoiding barriers.

  1. Dielectric barrier discharges in analytical chemistry.

    Science.gov (United States)

    Meyer, C; Müller, S; Gurevich, E L; Franzke, J

    2011-06-21

    The present review reflects the importance of dielectric barrier discharges in analytical chemistry. Special about this discharge is-and in contrast to usual discharges with direct current-that the plasma is separated from one or two electrodes by a dielectric barrier. This gives rise to two main features of the dielectric barrier discharges; it can serve as dissociation and excitation device and as ionization mechanism, respectively. The article portrays the various application fields for dielectric barrier discharges in analytical chemistry, for example the use for elemental detection with optical spectrometry or as ionization source for mass spectrometry. Besides the introduction of different kinds of dielectric barrier discharges used for analytical chemistry from the literature, a clear and concise classification of dielectric barrier discharges into capacitively coupled discharges is provided followed by an overview about the characteristics of a dielectric barrier discharge concerning discharge properties and the ignition mechanism.

  2. Engine combustion control via fuel reactivity stratification

    Energy Technology Data Exchange (ETDEWEB)

    Reitz, Rolf Deneys; Hanson, Reed M.; Splitter, Derek A.; Kokjohn, Sage L.

    2016-06-28

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  3. C-Reactive Protein (CRP) Test

    Science.gov (United States)

    ... and services. Advertising & Sponsorship: Policy | Opportunities C-Reactive Protein (CRP) Share this page: Was this page helpful? Also known as: CRP Formal name: C-Reactive Protein Related tests: ESR , Complement , Procalcitonin , ANA , Rheumatoid Factor ...

  4. Engine combustion control via fuel reactivity stratification

    Energy Technology Data Exchange (ETDEWEB)

    Reitz, Rolf Deneys; Hanson, Reed M.; Splitter, Derek A.; Kokjohn, Sage L.

    2015-07-14

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  5. Engine combustion control via fuel reactivity stratification

    Science.gov (United States)

    Reitz, Rolf Deneys; Hanson, Reed M; Splitter, Derek A; Kokjohn, Sage L

    2013-12-31

    A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choose the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

  6. the Study of Hepatitis B Virus Reactivation

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    Hepatitis B virus (HBV) reactivation after chemotherapy or immunosuppressive therapy is a cause of liver-related morbidity and mortality. Not all chronic hepatitis B patients will lead to HBV reactivation. The incidence is 0.3%-30.2%according to the reports. The mechanism of HBV reactivation is still unclear, but it is believed that the viral load is increasing due to the suppression of immune response. No uniform diagnostic criteria are available. HBV reactivation can be confirmed by an increase of serum HBV DNA level. Recently, awareness of reactivation of occult HBV has been improved, especially in HBV endemic area. Preemptive antiviral therapy was the best approach to prevent the HBV reactivation. HBV reactivation can lead to acute hepatitis, severe hepatitis and acute liver failure. Therefore, it is worthy of great attention and further study. Antiviral therapy is safe and effective to prevent HBV reactivation.

  7. Particle Swarm Optimization Based Reactive Power Optimization

    CERN Document Server

    Sujin, P R; Linda, M Mary

    2010-01-01

    Reactive power plays an important role in supporting the real power transfer by maintaining voltage stability and system reliability. It is a critical element for a transmission operator to ensure the reliability of an electric system while minimizing the cost associated with it. The traditional objectives of reactive power dispatch are focused on the technical side of reactive support such as minimization of transmission losses. Reactive power cost compensation to a generator is based on the incurred cost of its reactive power contribution less the cost of its obligation to support the active power delivery. In this paper an efficient Particle Swarm Optimization (PSO) based reactive power optimization approach is presented. The optimal reactive power dispatch problem is a nonlinear optimization problem with several constraints. The objective of the proposed PSO is to minimize the total support cost from generators and reactive compensators. It is achieved by maintaining the whole system power loss as minimum...

  8. Perceptual basis for reactive teleoperation.

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y. S.; Ewing, T. F.; Boyle, J. M.; Yule, T. J.

    2001-08-28

    To enhance task performance in partially structured environment, enhancement of teleoperation was proposed by introducing autonomous behaviors. Such autonomy is implemented based on reactive robotic architecture, where reactive motor agents that directly couples sensory inputs and motor actions become the building blocks. To this end, presented in this paper is a perceptual basis for the motor agents. The perceptual basis consists of perceptual agents that extracts environmental information from a structured light vision system and provide action oriented perception for the corresponding motor agents. Rather than performing general scene reconstruction, a perceptual agent directly provides the motion reference for the motor behavior. Various sensory mechanisms--sensor fission, fusion, and fashion--becomes basic building blocks of the perception process. Since perception is a process deeply intertwined with the motor actions, active perception may also incorporate motor behaviors as an integral perceptual process.

  9. A Search of Reactivated Comets

    Science.gov (United States)

    Ye, Quan-Zhi

    2017-05-01

    Dormant or near-dormant short-period comets can unexpectedly regain the ability to eject dust. In many known cases, the resurrection is short-lived and lasts less than one orbit. However, it is possible that some resurrected comets can remain active in later perihelion passages. We search the archival images of various facilities to look for these “reactivated” comets. We identify two candidates, 297P/Beshore and 332P/Ikeya-Murakami, both of which were found to be inactive or weakly active in the previous orbit before their discovery. We derive a reactivation rate of ˜ 0.007 {{comet}}-1 {{orbit}}-1, which implies that typical short-period comets only become temporarily dormant a few times or less. Smaller comets are prone to rotational instability and may undergo temporary dormancy more frequently. Next generation high-cadence surveys may find more reactivation events of these comets.

  10. Reactive polymer fused deposition manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Kunc, Vlastimil; Rios, Orlando; Love, Lonnie J.; Duty, Chad E.; Johs, Alexander

    2017-05-16

    Methods and compositions for additive manufacturing that include reactive or thermosetting polymers, such as urethanes and epoxies. The polymers are melted, partially cross-linked prior to the depositing, deposited to form a component object, solidified, and fully cross-linked. These polymers form networks of chemical bonds that span the deposited layers. Application of a directional electromagnetic field can be applied to aromatic polymers after deposition to align the polymers for improved bonding between the deposited layers.

  11. Los imaginarios de los futuros periodistas en Francia

    Directory of Open Access Journals (Sweden)

    M Santos-Sainz

    2013-02-01

    Full Text Available El artículo se centra en investigar las diferencias de percepción de las realidades profesionales y sociales según la pertenencia socio-profesional del ámbito familiar de los futuros periodistas y según la pertenencia de género. La metodología se basa en dos niveles de estudio. El primero responde al análisis de los datos empíricos sobre las características sociales de los estudiantes de periodismo antes de integrar los estudios dispensados por los centros de formación profesionalizada en periodismo de las universidades públicas de Estrasburgo, Burdeos, Tours y Marsella. El segundo nivel de análisis se construye a partir de toda una serie de entrevistas en profundidad que trazan el pasado familiar y permiten conocer los valores y representaciones de la profesión de los estudiantes del Instituto de Periodismo de Burdeos. Los resultados demuestran que los estudiantes de periodismo no son una categoría homogénea. Las diferencias respecto a su origen social resultan notables e influyen sobremanera en el imaginario de la profesión.

  12. Los santos patronos de los migrantes Mexicanos a Estados Unidos

    OpenAIRE

    Rafael Alarcón; Macrina Cardenas Montaño

    2013-01-01

    La mayor parte los migrantes mexicanos indocumentados que buscan encontrar un empleo en Estados Unidos son católicos, por esta razón, han incorporado a la devoción de los santos patronos sus tribulaciones que incluyen el trayecto desde sus comunidades de origen a la frontera norte, los peligros del cruce indocumentado, la búsqueda de trabajo y la posible deportación. El objetivo central de este artículo es analizar las características más importantes de tres devociones de los migrantes indocu...

  13. Los pros y los contras del uso de la mariguana

    OpenAIRE

    Cleva Villanueva

    2010-01-01

    La mariguana es la droga más usada en todo el mundo. El presente estudio analiza los efectos de los fitocanabinoides (contenidos en la mariguana) y de los canabinoides endógenos (producidos en el organismo). Se evalúan las posibilidades terapéuticas destacando el efecto antiemético (único uso aceptado). Al final se emite una opinión sobre la legalización basada en los efectos permanentes que produce y que están asociados al uso en edad temprana.

  14. Los santos patronos de los migrantes Mexicanos a Estados Unidos

    OpenAIRE

    Rafael Alarcón; Macrina Cardenas Montaño

    2013-01-01

    La mayor parte los migrantes mexicanos indocumentados que buscan encontrar un empleo en Estados Unidos son católicos, por esta razón, han incorporado a la devoción de los santos patronos sus tribulaciones que incluyen el trayecto desde sus comunidades de origen a la frontera norte, los peligros del cruce indocumentado, la búsqueda de trabajo y la posible deportación. El objetivo central de este artículo es analizar las características más importantes de tres devociones de los migrantes indocu...

  15. Quadratic reactivity fuel cycle model

    Energy Technology Data Exchange (ETDEWEB)

    Lewins, J.D.

    1985-11-01

    For educational purposes it is highly desirable to provide simple yet realistic models for fuel cycle and fuel economy. In particular, a lumped model without recourse to detailed spatial calculations would be very helpful in providing the student with a proper understanding of the purposes of fuel cycle calculations. A teaching model for fuel cycle studies based on a lumped model assuming the summability of partial reactivities with a linear dependence of reactivity usefully illustrates fuel utilization concepts. The linear burnup model does not satisfactorily represent natural enrichment reactors. A better model, showing the trend of initial plutonium production before subsequent fuel burnup and fission product generation, is a quadratic fit. The study of M-batch cycles, reloading 1/Mth of the core at end of cycle, is now complicated by nonlinear equations. A complete account of the asymptotic cycle for any order of M-batch refueling can be given and compared with the linear model. A complete account of the transient cycle can be obtained readily in the two-batch model and this exact solution would be useful in verifying numerical marching models. It is convenient to treat the parabolic fit rho = 1 - tau/sup 2/ as a special case of the general quadratic fit rho = 1 - C/sub tau/ - (1 - C)tau/sup 2/ in suitably normalized reactivity and cycle time units. The parabolic results are given in this paper.

  16. Los pishtacos: degolladores degollados

    Directory of Open Access Journals (Sweden)

    1991-01-01

    Full Text Available LES PISHTACOS : ÉGORGEURS ÉGORGÉS. A partir de douze récits de la sierra centrale du Pérou, nous analysons les multiples représentations du Pishtaco. Il est significatif que dans cette région, ces personnages maléfiques soient toujours vaincus par les taureaux (représentation des Amarus, par les chiens et par les paysans pauvres qui utilisent diverses astuces. Nous faisons une étude comparative avec d’autres régions du pays à propos du cycle de la graisse et des méthodes permettant la délivrance. En résumé, le Pishtaco est un personnage fascinant qui synthétise un ensemble de symboles et de traditions hispaniques et andines. Tomando como base doce relatos de la sierra central del Perú, se analiza las múltiples representaciones del Pishtaco. Particularmente significativo resulta el hecho de que en esta zona estos personajes malignos son siempre derrotados. Sus vencedores son los toros (metamorfosis de los Amarus, los perros y campesinos pobres que se valen del ají, del chuño y otras tretas jocosas. En cuanto al ciclo de la grasa y las contraconjuras, se hacen referencias comparativas con otras áreas geográficas del país En suma, el Pishtaco es un personaje fascinante y sintetiza una serie de símbolos y tradiciones hispano andinas. THE PISHTACOS: THE SLAUGHTERS SLAUGHTED. On the base of twelve narrations from the central sierra of Peru, we analyze the multiples representations of the Pishtaco. The fact that in this region these malefic entities are always beaten by bulls (representations of amarus by dogs and by poor peasants using different artfulness. About the grease cycle and the means of delivery reference are made to other areas of the country. Resuming, the pishtaco is a fascinating entity syntheting a whole lot of symbols and spanish traditions.

  17. Event-based modularization of reactive systems

    NARCIS (Netherlands)

    Malakuti, Somayeh; Aksit, Mehmet

    2014-01-01

    There is a large number of complex software systems that have reactive behavior. As for any other software system, reactive systems are subject to evolution demands. This paper defines a set requirements that must be fulfilled so that reuse of reactive software systems can be increased. Detailed ana

  18. The cross-reactivity of the enterovirus 71 to human brain tissue and identification of the cross-reactivity related fragments

    Directory of Open Access Journals (Sweden)

    Zhang Lian

    2010-02-01

    Full Text Available Abstract Background EV71 occasionally cause a series of severe neurological symptoms, including aseptic meningitis, encephalitis, and poliomyelitis-like paralysis. However, the neurological destruction mechanism was remained to be clarified. This study described the cross reaction between EV71 induced IgG and human brain tissue. Results Cross reaction of the IgG from 30 EV71 infected patients' sera to human tissues of cerebra was observed, which suggested that some EV71 antigens could induce IgG cross-reactivity to human cerebra. To identify the regions of EV71 virus that containing above antigens, the polypeptide of virus was divided into 19 peptides by expression in prokaryotes cell. Mouse anti-sera of these peptides was prepared and applied in immunohistochemical staining with human adult and fetus brain tissue, respectively. The result indicated the 19 peptides can be classified into three groups: strong cross-reactivity, weak cross-reactivity and no cross-reactivity with human brain tissue according the cross reaction activity. Then, the increased Blood Brain Barrier (BBB permeability and permits IgG entry in neonatal mice after EV71 infection was determined. Conclusion EV71 induced IgG could enter BBB and cross-reacted with brain tissue in EV71 infected neonatal mice, and then the peptides of EV71 that could induce cross-reactivity with brain tissue were identified, which should be avoided in future vaccine designing.

  19. Aprovechamiento sostenible de los pastizales

    Directory of Open Access Journals (Sweden)

    Salvador Rebollo

    2003-01-01

    Full Text Available Debido a la gran extensión ocupada por los ecosistemas de pastizal y a su relativamente elevado grado de naturalidad, la gestión de los pastizales tendrá importantes implicaciones en la conservación de numerosas especies silvestres de los distintos niveles tróficos. En este artículo sugerimos ideas básicas para que el aprovechamiento de los pastizales no comprometa su viabilidad futura. Para ello, repasamos el concepto de ecosistema de pastizal, describimos sus distintas configuraciones dependiendo de la intensidad del aprovechamiento, señalamos importantes componentes del pastizal que favorecen su estabilidad y que permitirán un manejo sostenible de los mismos y, finalmente, exponemos las características básicas que debe tener un plan de seguimiento y control de la explotación de los pastizales

  20. Tunneling without barriers with gravity

    CERN Document Server

    Kanno, Sugumi; Soda, Jiro

    2012-01-01

    We consider the vacuum decay of the flat Minkowski space to an anti-de Sitter space. We find a one-parameter family of potentials that allow exact, analytical instanton solutions describing tunneling without barriers in the presence of gravity. In the absence of gravity such instantons were found and discussed by Lee and Weinberg more than a quarter of a century ago. The bounce action is also analytically computed. We discuss possible implications of these new instantons to cosmology in the context of the string theory landscape.

  1. Los 'Colorados': Etnohistoria y Toponimia

    NARCIS (Netherlands)

    Gómez-Rendón, J.

    2015-01-01

    Los "colorados" comprendían varios grupos étnicos emparentados etnolingüísticamente que ocupaban el piedemonte andino occidental desde El Carchi hasta Bolívar así como las tierras bajas del Pacífico en los sistemas hidrográficos de los ríos Esmeraldas y Guayas. Aunque la ocupación "colorada" de

  2. Los 'Colorados': Etnohistoria y Toponimia

    NARCIS (Netherlands)

    Gómez-Rendón, J.

    2015-01-01

    Los "colorados" comprendían varios grupos étnicos emparentados etnolingüísticamente que ocupaban el piedemonte andino occidental desde El Carchi hasta Bolívar así como las tierras bajas del Pacífico en los sistemas hidrográficos de los ríos Esmeraldas y Guayas. Aunque la ocupación "colorada" de esta

  3. Los impactos del turismo

    Directory of Open Access Journals (Sweden)

    Tomás Franco Aliaga

    1999-01-01

    Full Text Available El turismo aparece, dentro de la economía española, como una actividad determinante desde los años sesenta. Sus efectos beneficiosos se han dejado sentir no sólo en la Balanza de Pagos o en el Producto Interior Bruto, sino que también han impactado favorablemente en el empleo y en la cultura. Sin embargo, esas repercusiones no han sido tan positivas en el medio ambiente, pues nuestras costas sufren numerosos problemas urbanísticos, infraestucturales y de contaminación diversa.Tourism appears, within the Spanish economy, as a determinant activity since the sixties. Its beneficial effects have showed not only on the Balance of Payments or the Gross Domestic Product, but also on employment and the culture. However, those effects have not been as positive for the environment since our coasts are suffering a lot from urbanism, infrastructure and pollution problems.

  4. Los palacios de Themis

    OpenAIRE

    Hugo Arciniega

    2000-01-01

    Hugo Arciniega reseña el estado en que se encontraba el sistema penitenciario mexicano al mediar el siglo xix. Por medio de un seguimiento filológico del proceso que llevó a la construcción de la cárcel de la Acordada durante el régimen colonial, y del análisis arquitectónico y urbanístico de esta cárcel, el autor expone las condiciones en que vivían los presos mexicanos hacia 1840, cuando Ignacio Cumplido, el editor de El Mosaico Mexicano, ingresó como recluso. De las críticas que hiciera es...

  5. Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Dogliani, Harold O [Los Alamos National Laboratory

    2011-01-19

    The purpose of the briefing is to describe general laboratory technical capabilities to be used for various groups such as military cadets or university faculty/students and post docs to recruit into a variety of Los Alamos programs. Discussed are: (1) development and application of high leverage science to enable effeictive, predictable and reliability outcomes; (2) deter, detect, characterize, reverse and prevent the proliferation of weapons of mass destruction and their use by adversaries and terrorists; (3) modeling and simulation to define complex processes, predict outcomes, and develop effective prevention, response, and remediation strategies; (4) energetic materials and hydrodynamic testing to develop materials for precise delivery of focused energy; (5) materials cience focused on fundamental understanding of materials behaviors, their quantum-molecular properties, and their dynamic responses, and (6) bio-science to rapidly detect and characterize pathogens, to develop vaccines and prophylactic remedies, and to develop attribution forensics.

  6. Caen Los Pantaloncillos

    Directory of Open Access Journals (Sweden)

    Ana María Arboleda Arango

    2008-07-01

    Después de discutir diferentes experiencias, hipótesis y puntos de vista, el equipo de trabajo de Diseños para EL Interior S.A. llega a la conclusión de que es necesario y útil llevar a cabo una investigación de mercados. El caso indica cómo esta iniciativa se debe ver reflejada en un brief, a través del cual se plasme la situación en la que se encuentra la marca, los objetivos de la investigación y el grupo objetivo para la misma. El caso brinda la información necesaria para que el estudiante elabore el brief pensando en la necesidad de demandar una investigación de mercados.

  7. Los otros signos

    Directory of Open Access Journals (Sweden)

    Sáez, Carlos

    2004-12-01

    Full Text Available The aim of this article is to study the signs and symbols that appear in the hispanic medieval documents and manuscripts whose form does not derive from the word subscripsi or from the cross. These signs and symbols have usually been considered simply as mere elements to validate the charters. However, these elements were useful as a mean of visual communication between the high classes, able to generate charters, and the rest of medieval society, the majority illiterate.

    Este trabajo se enmarca en el proyecto de investigación Usos, prácticas y modelos de conservación de lo escrito en la península ibérica entre los siglos XI a XVII, n° de referencia BHA 2002-02541, financiado por el Ministerio de Ciencia y Tecnología, dirigido por Carlos Sáez (Universidad de Alcalá.

  8. Los piratas en Cartagena

    Directory of Open Access Journals (Sweden)

    Soledad Acosta de Samper

    1964-06-01

    Full Text Available Cartagena ha sido siempre para mi espíritu una de las ciudades más interesantes de Colombia, no tan solo por su poética belleza, por la amable hospitalidad que siempre he recibido en ella las veces que la he visitado, y por su heroica historia -desde el descubrimiento, al empezar el siglo XVI, hasta los acontecimientos ocurridos allí en el año último--, sino también porque en sus playas vaga par a mi el recuerdo de mi padre, a cuyo lado visité en la infancia aquellas magníficas murallas; aquellas ruinas asombrosas de una grandeza que aún no ha muerto.

  9. Hasta los últimos confines

    OpenAIRE

    Córdoba, Joaquín Mª

    2005-01-01

    El 19 de mayo de 1798, la flota encargada de trasladar el ejército que iba a conquistar Egipto levó anclas del puerto de Toulon. Aunque tres años después la aventura se saldara en fracaso, el siglo XIX comenzó así con este temprano intento francés, que consiguió dominar durante algún tiempo el Valle del Nilo, soñó abrir el Canal de Suez y decidió el desarrollo moderno de los estudios sobre la cultura islámica y el antiguo Egipto. Desde entonces y hasta la I Guerra Mundial, el mundo iba a vivi...

  10. Los muertos del Floreanismo

    Directory of Open Access Journals (Sweden)

    Enrique Ayala Mora

    2008-06-01

    Full Text Available El artículo analiza el crimen político durante las primeras décadas de vida de la República del Ecuador. Específicamente centra su estudio en el período dominado por la figura de Juan José Flores, primer presidente del Ecuador. La inestabilidad política, la precariedad de las alianzas entre las élites regionales, la crisis económica generada por las guerras de Independencia, las conspiraciones y la violencia que caracterizaron al período de surgimiento de las repúblicas andinas hicieron del crimen político un “vicio de nacimiento”. El asesinato del general Antonio José de Sucre, la muerte de los miembros de la sociedad El Quiteño Libre, el homicidio de Juan Otamendi, entre otros, hicieron patente esta característica.

  11. Role of tip chemical reactivity on atom manipulation process in dynamic force microscopy.

    Science.gov (United States)

    Sugimoto, Yoshiaki; Yurtsever, Ayhan; Abe, Masayuki; Morita, Seizo; Ondráček, Martin; Pou, Pablo; Pérez, Ruben; Jelínek, Pavel

    2013-08-27

    The effect of tip chemical reactivity on the lateral manipulation of intrinsic Si adatoms toward a vacancy site on a Si(111)-(7 × 7) surface has been investigated by noncontact atomic force microscopy at room temperature. Here we measure the atom-hopping probabilities associated with different manipulation processes as a function of the tip-surface distance by means of constant height scans with chemically different types of tips. The interactions between different tips and Si atoms are evaluated by force spectroscopic measurements. Our results demonstrate that the ability to manipulate Si adatoms depends extremely on the chemical nature of the tip apex and is correlated with the maximal attractive force measured over Si adatoms. We rationalize the observed dependence of the atom manipulation process on tip-apex chemical reactivity by means of density functional theory calculations. The results of these calculations suggest that the ability to reduce the energy barrier associated with the Si adatom movement depends profoundly on tip chemical reactivity and that the level of energy barrier reduction is higher with tips that exhibit high chemical reactivity with Si adatoms. The results of this study provide a better way to control the efficiency of the atomic manipulation process for chemisorption systems.

  12. Los objetivos del desarrollo

    Directory of Open Access Journals (Sweden)

    Currie Lauchlin

    1993-12-01

    Full Text Available To broach the goals of development implies broaching the problem of economic growth in a critical manner. Not only the concept of growth but also the means of achieving it in practice should be questioned. Growth is not an end, it is a means of gaining access to development And development should not be understood as a goal, but as a permanent process of learning tending towards more control over the environment and greater levels of well-being. It is not a matter of increasing GNP linearly; development must occur, sustained growth that, without being a threat to mm or to our natural resources, can lead to the eradication of absolute and relati.ve poverty. The low rates of growth of the developing countries constitute structural problem that can /lot be reso1.ved by resorting to the neo-classical mechanisms of mobility, nor to the Keynesian formulas. These have served as a source of inspiration to the Harrod-lX:m3r·type models of growth which limit themselves to stimulating savings and ending unemployment by concentrating exclusively on the monetary demand. Getting OUt of the vicious circle of low growth implies eradicating poverty with respect into the immediateness of a direct attack on the problem. with respect to the developed counties, growth is starting to became harmful, and, given the prevalence of ostensible consumption and of pecuniary emulation, it is imperative to foment non-economic motivation that will permit the eradication of relative poverty.

    Abordar los objetivos del desarrollo implica abordar de manera crítica el problema del crecimiento econ

  13. PERSPECTIVA SEXUAL DE LOS ADOLESCENTES

    OpenAIRE

    Chaves Araya, Mariana

    2011-01-01

    El presente estudio tiene como objetivo identificar los conocimientos, actitudes y prácticas sexuales de adolescentes, con el fin de establecer el abordaje apropiado de las necesidades relacionadas con la sexualidad en este grupo de jóvenes. Para tal efecto, se realizó una encuesta al 85% de los estudiantes de décimo y undécimo años de los siete colegios del cantón central de Puntarenas, Chacarita y Barranca. Se logró determinar que los jóvenes tienen conocimientos sobre anatomía y fis...

  14. La leyenda de los Horacios

    OpenAIRE

    Rodríguez Horrillo, Miguel Ángel

    2010-01-01

    La Leyenda de los Horacios alcanza su forma canónica a lo largo de la historia de la literatura antigua. Los diferentes estadios de composición muestran cómo los poetas, oradores e historiadores interpretaron el motivo tradicional de acuerdo a los conflictos de su época, al tiempo que insertaban aspectos religiosos, legales y morales a fin de hacer la vieja narración comprensible y útil a su público. The legend of the Horatii obtains its canonical form throughout the history of the Ancient...

  15. Los jaklexa y el saber

    Directory of Open Access Journals (Sweden)

    Simón Esmeral Ariza

    2014-02-01

    Full Text Available "En aquella época, cuando el calendario n o había nacido y el tiempo no había aprendido a contar, Aluna Jaba, iniciaba su obra creadora". Ella, Aluna Jaba, la madre pensamiento,la madre Universal, la magna mater, la creadora de estemundo fantástico Yreal de los que se autodenominan "los hermanos mayores" los que en su cosmovisión han hecho de la Sierra Nevada de Santa Marta, "el corazón del mundo", de aquellos que se han autodenominado Yen verdad son los guardianes del saber, los sabios de este mundo lleno de misterios y conocimientos "LosJaklexa" , aquellos que por designio de la madre han echado sobre sus hombros el cuidado y los destinos del "Universo" son los mismos querelata el mito Kággaba en el cual los hijos de Mama Ywisa llevan sobre sus hombros el universo entero.

  16. Del ENIAC, hasta los andares

    OpenAIRE

    2014-01-01

    Si bien los computadores actuales, en todas sus variantes —portátiles, tabletas, teléfonos inteligentes—, resultan más pequeños, baratos y rápidos que los precedentes, no es menos cierto que el estudio minucioso de las viejas glorias de la historia de la informática nos puede facilitar la comprensión, no solo de algunos de los aspectos de la tecnología informática de aquel momento e incluso de la actual, sino también de los rasgos socioculturales propios del entorno científico y huma...

  17. Los 5 entierros de Pessoa

    Directory of Open Access Journals (Sweden)

    Juan Manuel Roca

    1998-05-01

    Full Text Available Nació en Medellín (Antioquia en 1946. Ha publicado, entre otros, los siguientes libros: Memoria del agua (1973, Luna de ciegos (1974, Los ladrones nocturnos (1977, Señal de cuentos (1979, Fabulario real (1980, País secreto (1988, Ciudadano de la noche (1989, Pavana con el diablo (1990, Monólogos (1994, Cuaderno de mapas (1994, La farmacia del ángel (1995, Vengo a golpear a tu puerta (1997, Tertulia de ausentes (1998. Los poemas son inéditos y su autor los ha cedido al Boletín.

  18. Los hábitos lectoescritores en los alumnos universitarios

    Directory of Open Access Journals (Sweden)

    Fernando Guzmán-Simón

    2014-01-01

    Full Text Available Esta investigación analiza y describe los hábitos lectoescritores de los estudiantes universitarios dentro y fuera de las aulas. Para ello, nos hemos apoyado en la información proporcionada por los estudiantes que ha sido recogida a través de dos cuestionarios: uno de naturaleza descriptiva aplicado a una muestra de trescientos estudiantes de dos programas de Grado de la Universidad de Sevilla; el otro, de carácter específico (con tres versiones diferentes completado por tres submuestras elegidas en función de las respuestas de los estudiantes al primer cuestionario. El análisis de dichas respuestas nos ha permitido determinar la existencia de tres perfiles representativos que describen los hábitos lectoescritores de los estudiantes: escritores/lectores segmentados, lectores privados y escritores/lectores instrumentales. Estos perfiles indican que los estudiantes tienen dificultades para acceder a un pensamiento propio capaz de generar conocimiento. Los resultados obtenidos no sólo muestran importantes carencias en el proceso de alfabetización académica sino que plantean interrogantes sobre el modo en que se está llevando a cabo dicho proceso en el ámbito de la educación universitaria.

  19. Terapia intensiva: El problema de los medios y los fines

    Directory of Open Access Journals (Sweden)

    Carlos Gherardi

    2011-12-01

    Full Text Available La tecnología médica aplicada a la medicina del paciente agudo y grave permitió la creación de un área asistencial diferenciada y el desarrollo del cuidado intensivo como una nueva especialidad. Los nuevos medios disponibles para reemplazar o asistir funciones de órganos vitales fueron los determinantes de este avance tan importante en el desarrollo de toda la alta complejidad médica en los últimos cuarenta años. Sin embargo la aplicabilidad de estos medios, que en este caso son los soportes vitales, no se han podido sustraer de la filosofía del imperativo tecnológico que ha impregnado a toda la cultura de la sociedad contemporánea. Se observa en este tiempo una influencia perniciosa que perturba el recuerdo permanente de los fines de la medicina, que no son los de evitar la muerte o a la consideración del valor vida como un absoluto ajeno a las preferencias del paciente. Las decisiones finales en circunstancias irreversibles, en que sólo es posible mantener una vida biológica, deben ser tomadas por los médicos y los familiares.

  20. On the Construction of Sorted Reactive Systems

    DEFF Research Database (Denmark)

    Birkedal, Lars; Debois, Søren; Hildebrandt, Thomas

    2008-01-01

    We develop a theory of sorted bigraphical reactive systems. Every application of bigraphs in the literature has required an extension, a sorting, of pure bigraphs. In turn, every such application has required a redevelopment of the theory of pure bigraphical reactive systems for the sorting at hand...... bigraphs. Technically, we give our construction for ordinary reactive systems, then lift it to bigraphical reactive systems. As such, we give also a construction of sortings for ordinary reactive systems. This construction is an improvement over previous attempts in that it produces smaller and much more...