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Sample records for stable atmospheric condition

  1. Experimental and numerical study of atmospheric turbulence and dispersion in stable conditions and in near field at a complex site

    International Nuclear Information System (INIS)

    Wei, Xiao

    2016-01-01

    - ε closure adapted for atmospheric flows and a canopy model for the forest. These simulations are shown to reproduce correctly the characteristics of the mean flow on the measurements site, especially the impact of the forest for different wind directions, in both neutral and stable conditions. Simulation results also show the directional wind shear and the turbulent kinetic energy increase induced by the forest. A sensitivity study has been made for various values of forest density and shows that the typical features of canopy flow become more pronounced as canopy density increases. Pollutant dispersion study is made for several IOPs. Concentration data analysis shows a consistency with previous measurements made in a near-source region where the plume scale is smaller than the large-scale turbulence eddies. Concentration fluctuations are characterized through concentration time series, histogram and statistical analysis. The inertial sub-range can be observed in the concentration spectra. Next, pollutant dispersion is modelled by transport equations for concentration and its variance. The mean concentrations show a good agreement with measurements in values for all the IOPs studied, except that the position of the concentration peak depends on the accuracy of simulated wind rotation below the forest height. The concentration fluctuations obtained from simulations seem to be affected significantly by the condition at the source and the modelling of the dissipation term. A sensitivity study to the parameterization is then presented. (author) [fr

  2. Experimental and numerical study of atmospheric turbulence and dispersion in stable conditions and in near field at a complex site

    International Nuclear Information System (INIS)

    Wei, Xiao

    2016-01-01

    -ε closure adapted for atmospheric flows and a canopy model for the forest. These simulations are shown to reproduce correctly the characteristics of the mean flow on the measurements site, especially the impact of the forest for different wind directions, in both neutral and stable stratification. Simulations results also show the directional wind shear and the turbulent kinetic energy increase induced by the forest. A sensitivity study has been made for various values of forest density and shows that the typical features of canopy flow become more pronounced as canopy density increases. Pollutants dispersion study are made for several IOPs. Concentration data analysis shows a consistency with previous measurements made in a near-source region where the plume scale is smaller than the large-scale turbulence eddies. Concentration fluctuations are characterized through concentration time series, histogram and statistical analysis. The internal sub-range can be observed in the concentration spectra. Next, pollutants dispersion are modelled by transport equations for concentration and its variance. The mean concentrations show a good agreement with measurements in values for all the IOPs studied, except that the position of the concentration peak depends on the accuracy of simulated wind rotation below the forest height. The concentration fluctuations obtained from simulations seem to be affected significantly by the initial condition and the modelling of the dissipation term. A sensitivity study to the parameterization is then presented. (author)

  3. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled:

    Modelling Stable Atmospheric Boundary Layers over Snow

    H.A.M. Sterk

    Wageningen, 29th of April, 2015

    Summary

    The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs

  4. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled: Modelling Stable Atmospheric Boundary Layers over Snow H.A.M. Sterk Wageningen, 29th of April, 2015 Summary The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs typically form at night and in polar

  5. Improved Atmospheric Stable Boundary Layer Formulations for Navy Seasonal Forecasting

    Science.gov (United States)

    2012-09-30

    Long-term goals are to develop methods, descriptions and parameterizations that will alleviate long-standing problems in basically all large-scale numerical atmospheric models in dealing with statically stable and/or very stable conditions, and to implement these for Navy extended forecasting

  6. Changes in calcification of coccoliths under stable atmospheric CO2

    DEFF Research Database (Denmark)

    Berger, C.; Meier, K. J. S.; Kinkel, H.

    2014-01-01

    The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural...... North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected...

  7. Unconditionally stable perfectly matched layer boundary conditions

    NARCIS (Netherlands)

    De Raedt, H.; Michielsen, K.

    2007-01-01

    A brief review is given of a systematic, product-formula based approach to construct unconditionally stable algorithms for solving the time-dependent Maxwell equations. The fundamental difficulties that arise when we want to incorporate uniaxial perfectly matched layer boundary conditions into this

  8. Exploring Scintillometry in the Stable Atmospheric Surface Layer

    NARCIS (Netherlands)

    Hartogensis, O.K.

    2006-01-01

    The main objective of this thesis is to investigate observation methods of heat and momentum exchange and key variables that characterise turbulence in the atmospheric stable surface layer (SSL), a layer defined as the lower part of the stable boundary layer (SBL) where surface fluxes do not change

  9. An atmospheric dispersion model for linear sources in calm wind, stable conditions; Un modello di dispersione atmosferica per sorgenti lineari in condizioni di vento debole

    Energy Technology Data Exchange (ETDEWEB)

    Cirillo, M. C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Buratti, D. [Rome Univ. La Sapienza, Rome (Italy). Facolta' di Scienze Statistiche; Metallo, M. C.; Poli, A.A. [ESA s.a.s., Bracciano, RM (Italy)

    1999-07-01

    In this report a dispersion model is proposed that provides an estimate of concentration of gaseous pollutants emitted by an highway, or in general by a line source, in presence of low wind speed. This aim was pursued because available models have not a satisfactory behaviour in such conditions, which is critical for dispersion of gaseous pollutants. This lack is due to difficulty of simulating dispersion turbulent component which is determined by fluctuation of wind speed and wind direction, and in presence of calm conditions it assumes values comparable with transport component. The proposed model overcomes this difficulty, as it is shown by sensitivity analysis and comparison with experimental data. The capability of simulating dispersion eve in critical conditions, like the presence of low level inversion, and the absence of source geometrical approximations make the model a tool that, properly used, may contribute to the efficient planning and management of environmental resources. [Italian] In questo rapporto viene proposto un modello per la stima delle concentrazioni di inquinanti aeriformi emessi da un'arteria stradale, o in generale da una sorgente lineare, in presenza di vento debole. Questo scopo e' stato perseguito in quanto in questa condizione, nonostante la dispersione degli inquinanti risulti fortemente problematica, i modelli disponibili in letteratura non hanno un comportamento soddisfacente. Questa mancanca e' attribuibile alla difficolta' di simulare la componente turbolenta della dispersione, dovuta alla fluttuazione della direzione e della velocita' del vento che, in presenza di vento debole, assume valori confrontabili alla componente di trasporto. Il modello qui di seguito proposto supera questa difficolta', come dimostrano l'analisi di sensibilita' e il confronto con un caso reale; la capacita' di simulare la dispersione anche in condizioni fisicamente critiche quali la presenza di inversione a

  10. Fractionation of Stable Isotopes in Atmospheric Aerosol Reactions

    DEFF Research Database (Denmark)

    Meusinger, Carl

    Aerosols - particles suspended in air - are the single largest uncertainty in our current understanding of Earth's climate. They also affect human health, infrastructure and ecosystems. Aerosols are emitted either directly into the atmosphere or are formed there for instance in response to chemical...... reactions and undergo complex chemical and physical changes during their lifetimes. In order to assess processes that form and alter aerosols, information provided by stable isotopes can be used to help constrain estimates on the strength of aerosol sources and sinks. This thesis studies (mass......-independent) fractionation processes of stable isotopes of C, N, O and S in order to investigate three different systems related to aerosols: 1. Post-depositional processes of nitrate in snow that obscure nitrate ice core records 2. Formation and aging of secondary organic aerosol generated by ozonolysis of X...

  11. Microwave generation of stable atmospheric-pressure fireballs in air

    Science.gov (United States)

    Stephan, Karl D.

    2006-11-01

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed.

  12. Effect of Atmospheric Conditions on LIBS Spectra

    Directory of Open Access Journals (Sweden)

    Andrew J. Effenberger

    2010-05-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS is typically performed at ambient Earth atmospheric conditions. However, interest in LIBS in other atmospheric conditions has increased in recent years, especially for use in space exploration (e.g., Mars and Lunar or to improve resolution for isotopic signatures. This review focuses on what has been reported about the performance of LIBS in reduced pressure environments as well as in various gases other than air.

  13. Highly stable superhydrophobic surfaces under flow conditions

    Science.gov (United States)

    Lee, Moonchan; Yim, Changyong; Jeon, Sangmin

    2015-01-01

    We synthesized hydrophobic anodic aluminum oxide nanostructures with pore diameters of 35, 50, 65, and 80 nm directly on quartz crystal microresonators, and the stability of the resulting superhydrophobicity was investigated under flow conditions by measuring changes in the resonance frequency and dissipation factor. When the quartz substrates were immersed in water, their hydrophobic surfaces did not wet due to the presence of an air interlayer. The air interlayer was gradually replaced by water over time, which caused decreases in the resonance frequency (i.e., increases in mass) and increases in the dissipation factor (i.e., increases in viscous damping). Although the water contact angles of the nanostructures increased with increasing pore size, the stability of their superhydrophobicity increased with decreasing pore size under both static conditions (without flow) and dynamic conditions (with flow); this increase can be attributed to an increase in the solid surface area that interacts with the air layer above the nanopores as the pore size decreases. Further, the effects of increasing the flow rate on the stability of the superhydrophobicity were quantitatively determined.

  14. Stable isotope composition of atmospheric carbon monoxide. A modelling study

    International Nuclear Information System (INIS)

    Gromov, Sergey S.

    2014-01-01

    This study aims at an improved understanding of the stable carbon and oxygen isotope composition of the carbon monoxide (CO) in the global atmosphere by means of numerical simulations. At first, a new kinetic chemistry tagging technique for the most complete parameterisation of isotope effects has been introduced into the Modular Earth Submodel System (MESSy) framework. Incorporated into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, an explicit treatment of the isotope effects on the global scale is now possible. The expanded model system has been applied to simulate the chemical system containing up to five isotopologues of all carbon- and oxygen-bearing species, which ultimately determine the δ 13 C, δ 18 O and Δ 17 O isotopic signatures of atmospheric CO. As model input, a new stable isotope-inclusive emission inventory for the relevant trace gases has been compiled. The uncertainties of the emission estimates and of the resulting simulated mixing and isotope ratios have been analysed. The simulated CO mixing and stable isotope ratios have been compared to in-situ measurements from ground-based observatories and from the civil-aircraft-mounted CARIBIC-1 measurement platform. The systematically underestimated 13 CO/ 12 CO ratios of earlier, simplified modelling studies can now be partly explained. The EMAC simulations do not support the inferences of those studies, which suggest for CO a reduced input of the highly depleted in 13 C methane oxidation source. In particular, a high average yield of 0.94 CO per reacted methane (CH 4 ) molecule is simulated in the troposphere, to a large extent due to the competition between the deposition and convective transport processes affecting the CH 4 to CO reaction chain intermediates. None of the other factors, assumed or disregarded in previous studies, however hypothesised to have the potential in enriching tropospheric CO in 13 C, were found significant when explicitly simulated. The

  15. Numerical study of aircraft wake vortex evolution near ground in stable atmospheric boundary layer

    Directory of Open Access Journals (Sweden)

    Mengda LIN

    2017-12-01

    Full Text Available The evolutions of aircraft wake vortices near ground in stable atmospheric boundary layer are studied by Large Eddy Simulation (LES. The sensitivity of vortex evolution to the Monin-Obukhov (M-O scale is studied for the first time. The results indicate that increasing stability leads to longer lifetimes of upwind vortices, while downwind vortices will decay faster due to a stronger crosswind shear under stable conditions. Based on these results, an empirical model of the vortex lifetime as a function of 10-m-high crosswind and the M-O scale is summarized. This model can provide an estimate of the upper boundary of the vortex lifetime according to the real-time crosswind and atmospheric stability. In addition, the lateral translation of vortices is also inspected. The results show that vortices can travel a furthest distance of 722 m in the currently-studied parameter range. This result is meaningful to safety analysis of airports that have parallel runways. Keywords: Aerodynamics, Aircraft, Aircraft wake vortex, Large eddy simulation, Stable atmosphere boundary layer

  16. Biosensors engineered from conditionally stable ligand-binding domains

    Energy Technology Data Exchange (ETDEWEB)

    Church, George M.; Feng, Justin; Mandell, Daniel J.; Baker, David; Fields, Stanley; Jester, Benjamin Ward; Tinberg, Christine Elaine

    2017-09-19

    Disclosed is a biosensor engineered to conditionally respond to the presence of specific small molecules, the biosensors including conditionally stable ligand-binding domains (LBDs) which respond to the presence of specific small molecules, wherein readout of binding is provided by reporter genes or transcription factors (TFs) fused to the LBDs.

  17. Using stable isotopes to resolve eco-hydrological dynamics of soil-plant-atmosphere feedbacks

    Science.gov (United States)

    Dubbert, M.; Piayda, A.; Kübert, A.; Cuntz, M.; Werner, C.

    2016-12-01

    Water is the main driver of ecosystem productivity in most terrestrial ecosystems worldwide. Extreme events are predicted to increase in frequency in many regions and dynamic responses in soil-vegetation-atmosphere feedbacks play a privotal role in understanding the ecosystem water balance and functioning. In this regard, more interdisciplinary approaches, bridging hydrology, ecophysiology and atmospheric sciences are needed and particularly water stable isotopes are a powerful tracer of water transfer in soils and at the soil-plant interface (Werner and Dubbert 2016). Here, we present observations 2 different ecosystems. Water fluxes, atmospheric concentrations and their isotopic compositions were measured using laser spectroscopy. Soil moisture and its isotopic composition in several depths as well as further water sources in the ecosystem were monitored throughout the year. Using these isotopic approaches we disentangled soil-plant-atmosphere feedback processes controlling the ecosystem water cycle including vegetation effects on soil water infiltration and distribution, event water use of vegetation and soil fluxes, vegetational soil water uptake depths plasticity and partitioning of ecosystem water fluxes. In this regard, we review current strategies of ET partitioning and highlight pitfalls in the presented strategies (Dubbert et al. 2013, Dubbert et al.2014a). We demonstrate that vegetation strongly influenced water cycling, altering infiltration and distribution of precipitation. In conclusion, application of stable water isotope tracers delivers a process based understanding of interactions between soil, understorey and trees governing ecosystem water cycling necessary for prediction of climate change impact on ecosystem productivity and vulnerability. ReferencesDubbert, M. et al. (2013): Partitioning evapotranspiration - Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes. Journal of Hydrology Dubbert

  18. Stable isotope ratio measurements in atmospheric sulfate studies

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, P.T.; Holt, B.D.

    1976-01-01

    The isotopic composition of atmospheric sulfate has been determined by a number of workers and the results interpreted in terms of contributing sources and mechanisms of origin. A correlation between the /sup 18/O enrichment of atmospheric water and airborne particulate sulfate has been observed. Laboratory preparations of sulfate made from sulfur dioxide by two sets of sequential reactions, hydrolysis followed by oxidation and oxidation followed by hydrolysis, yielded products of distinguishable oxygen-isotope composition. Oxygen isotopic analysis of simultaneously collected field samples of ambient sulfate, sulfur dioxide, and water vapor indicated seasonal trends for all of the major constituents of atmospheric sulfation processes. Some isotopic data were also obtained on precipitation and precipitation sulfates. Field results suggest that ambient sulfates collected in the area of Argonne correpond more closely in oxygen isotope composition to a sulfate molecule containing two oxygens originating from sulfur dioxide, one oxygen from air and one oxygen from condensed-phased atmospheric water, SO/sub s/O/sub s/O/sub cw/O/sup 2 -//sub a/, than to the molecule SO/sub s/O/sub s/O/sub wv/O/sup 2//sub a/ in which one oxygen originates from vapor-phase atmospheric water.

  19. Stable isotope ratio measurements in atmospheric sulfate studies

    International Nuclear Information System (INIS)

    Cunningham, P.T.; Holt, B.D.

    1976-01-01

    The isotopic composition of atmospheric sulfate has been determined by a number of workers and the results interpreted in terms of contributing sources and mechanisms of origin. A correlation between the 18 O enrichment of atmospheric water and airborne particulate sulfate has been observed. Laboratory preparations of sulfate made from sulfur dioxide by two sets of sequential reactions, hydrolysis followed by oxidation and oxidation followed by hydrolysis, yielded products of distinguishable oxygen-isotope composition. Oxygen isotopic analysis of simultaneously collected field samples of ambient sulfate, sulfur dioxide, and water vapor indicated seasonal trends for all of the major constituents of atmospheric sulfation processes. Some isotopic data were also obtained on precipitation and precipitation sulfates. Field results suggest that ambient sulfates collected in the area of Argonne correpond more closely in oxygen isotope composition to a sulfate molecule containing two oxygens originating from sulfur dioxide, one oxygen from air and one oxygen from condensed-phased atmospheric water, SO/sub s/O/sub s/O/sub cw/O 2- /sub a/, than to the molecule SO/sub s/O/sub s/O/sub wv/O 2 /sub a/ in which one oxygen originates from vapor-phase atmospheric water

  20. Fractionation of Stable Isotopes in Atmospheric Aerosol Reactions

    DEFF Research Database (Denmark)

    Meusinger, Carl

    reactions and undergo complex chemical and physical changes during their lifetimes. In order to assess processes that form and alter aerosols, information provided by stable isotopes can be used to help constrain estimates on the strength of aerosol sources and sinks. This thesis studies (mass......-independent) fractionation processes of stable isotopes of C, N, O and S in order to investigate three different systems related to aerosols: 1. Post-depositional processes of nitrate in snow that obscure nitrate ice core records 2. Formation and aging of secondary organic aerosol generated by ozonolysis of X...... as required. The kndings provide important results for the studies' respective felds, including a description of the isotopic fractionation and quantum yield of nitrate photolysis in snow, equilibrium fractionation in secondary organic aerosol and fractionation constants of different oxidation pathways of SO2....

  1. Stable Atmospheric Boundary Layer Experiment in Spain (SABLES 98) : a report

    NARCIS (Netherlands)

    Cuxart, J.; Yague, C.; Morales, G.; Terradelles, E.; Orbe, J.; Calvo, J.; Vilu-Guerau, de J.; Soler, M.R.; Infante, C.; Buenestado, P.; Espinalt, A.; Jorgensem, H.E.

    2000-01-01

    This paper describes the Stable Atmospheric Boundary Layer Experiment in Spain (SABLES 98), which took place over the northern Spanish plateau comprising relatively flat grassland, in September 1998. The main objectives of the campaign were to study the properties of the mid-latitude stable boundary

  2. Stable atmospheric boundary-layer experiment in Spain (SABLES 98): A report

    DEFF Research Database (Denmark)

    Cuxart, J.; Yague, C.; Morales, G.

    2000-01-01

    This paper describes the Stable Atmospheric Boundary Layer Experiment in Spain (SABLES 98), which took place over the northern Spanish plateau comprising relatively flat grassland, in September 1998. The main objectives of the campaign were to study the properties of the mid-latitude stable...

  3. Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric CO2 by the Phoenix Lander

    Science.gov (United States)

    Niles, Paul B.; Boynton, W. V.; Hoffman, J. H.; Ming, D. W.; Hamara, D.

    2010-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars [1]. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils.

  4. Lateral Dispersion of Pollutants in a Very Stable Atmosphere - The Effect of Meandering

    DEFF Research Database (Denmark)

    Kristensen, Leif; Jensen, Niels Otto; Lundtang Petersen, Erik

    1981-01-01

    A model based on single particle diffusion is introduced to account for the effect of “meandering” on lateral plume dispersion in a very stable atmosphere. It is assumed that small scale atmospheric turbulence is absent, so that only large horizontal eddies are effective. A formula for the lateral....... Meteorological data from Risø and the small island Sprogø have been analysed in order to identify all situations in which the atmosphere is so stable that small scale turbulence cannot exist. The purpose is to see in how many of these situations meandering is also absent. The results show that, as a rule...

  5. Advection of pollutants by internal solitary waves in oceanic and atmospheric stable stratifications

    Directory of Open Access Journals (Sweden)

    G. W. Haarlemmer

    1998-01-01

    Full Text Available When a pollutant is released into the ocean or atmosphere under turbulent conditions, even a steady release is captured by large eddies resulting in localized patches of high concentration of the pollutant. If such a cloud of pollutant subsequently enters a stable stratification-either a pycnocline or thermocline-then internal waves are excited. Since large solitary internal waves have a recirculating core, pollutants may be trapped in the sclitary wave, and advected large distances through the waveguide provided by the stratification. This paper addresses the mechanisms, through computer and physical simulation, by which a localized release of a dense pollutant results in solitary waves that trap the pollutant or disperse the pollutant faster than in the absence of the waves.

  6. Large-eddy simulation of stable atmospheric boundary layers to develop better turbulence closures for climate and weather models

    Science.gov (United States)

    Bou-Zeid, Elie; Huang, Jing; Golaz, Jean-Christophe

    2011-11-01

    A disconnect remains between our improved physical understanding of boundary layers stabilized by buoyancy and how we parameterize them in coarse atmospheric models. Most operational climate models require excessive turbulence mixing in such conditions to prevent decoupling of the atmospheric component from the land component, but the performance of such a model is unlikely to be satisfactory under weakly and moderately stable conditions. Using Large-eddy simulation, we revisit some of the basic challenges in parameterizing stable atmospheric boundary layers: eddy-viscosity closure is found to be more reliable due to an improved alignment of vertical Reynolds stresses and mean strains under stable conditions, but the dependence of the magnitude of the eddy viscosity on stability is not well represented by several models tested here. Thus, we propose a new closure that reproduces the different stability regimes better. Subsequently, tests of this model in the GFDL's single-column model (SCM) are found to yield good agreement with LES results in idealized steady-stability cases, as well as in cases with gradual and sharp changes of stability with time.

  7. Stable atmospheric methane in the 2000s: key-role of emissions from natural wetlands

    OpenAIRE

    I. Pison; B. Ringeval; P. Bousquet; C. Prigent; F. Papa

    2013-01-01

    Two atmospheric inversions (one fine-resolved and one process-discriminating) and a process-based model for land surface exchanges are brought together to analyze the variations of methane emissions from 1990 to 2009. A focus is put on the role of natural wetlands and on the years 2000–2006, a period of stable atmospheric concentrations. From 1990 to 2000, the two inversions agree on the time-phasing of global emission anomalies. The process-discriminating inversion further indicates...

  8. Studying biosphere-atmosphere exchange of CO2 through Carbon-13 stable isotopes

    NARCIS (Netherlands)

    Velde, van der I.R.

    2015-01-01

    Summary Thesis ‘Studying biosphere-atmosphere exchange of CO2 through carbon-13 stable isotopes’ Ivar van der Velde Making predictions of future climate is difficult, mainly due to large uncertainties in the carbon cycle. The rate at which carbon is stored in the oceans and terrestrial

  9. Studying biosphere-atmosphere exchange of CO2 through Carbon-13 stable isotopes

    NARCIS (Netherlands)

    Velde, van der I.R.

    2015-01-01

    Summary Thesis ‘Studying biosphere-atmosphere exchange of CO2 through

    carbon-13 stable isotopes’

    Ivar van der Velde

    Making predictions of future climate is difficult, mainly due to large uncertainties in the carbon cycle. The rate at which carbon is stored in the oceans and

  10. The role of ions in particle nucleation under atmospheric conditions

    DEFF Research Database (Denmark)

    Enghoff, Martin B.; Pedersen, J. O. P.; Bondo, T.

    2008-01-01

    Aerosol nucleation has been studied experimentally in purified, atmospheric air, containing trace amounts of water vapor, ozone, and sulfur dioxide. The results are compared with model calculations. It is found that an increase in ionization by a factor of 10 increases the production rate of stable...

  11. Taking the atmosphere's pulse: The application of GC-IRMS to stable isotopes in atmospheric trace gases

    International Nuclear Information System (INIS)

    Lowe, D.C.; Ferretti, D.J.; Francey, R.J.; Allison, C.E.

    2001-01-01

    Since the industrial revolution, the abundance of many atmospheric trace gases has changed significantly. This is of concern because many of these trace species play a fundamental role in determining physical and chemical properties of the atmosphere important for maintaining life on earth. The impacts of the changes have been studied by a combination of analytical and theoretical modelling techniques. Stable isotope measurements made by conventional dual inlet IRMS for example, have provided valuable constraints on the budgets and removal mechanisms of key atmospheric trace gases. Unfortunately, in most cases, the application of these methods has been limited, because large air samples and cumbersome off line processing techniques are required to pre-concentrate enough gas for analysis. GC-IRMS offers a very attractive alternative because it combines on line processing with air sample size requirements typically 1000 times less than used in conventional techniques. In this article we focus on the requirements imposed on GC-IRMS by some of the current applications in atmospheric trace gas research. In addition, we examine some of the analytical and calibration aspects of the method applied to this kind of work. We finish with a summary of some of the comparative advantages and disadvantages of the GC-IRMS technique and some suggestions for future research using the method applied to specific atmospheric trace gases. (author)

  12. Reactive gas control of non-stable plasma conditions

    International Nuclear Information System (INIS)

    Bellido-Gonzalez, V.; Daniel, B.; Counsell, J.; Monaghan, D.

    2006-01-01

    Most industrial plasma processes are dependant upon the control of plasma properties for repeatable and reliable production. The speed of production and range of properties achieved depend on the degree of control. Process control involves all the aspects of the vacuum equipment, substrate preparation, plasma source condition, power supplies, process drift, valves (inputs/outputs), signal and data processing and the user's understanding and ability. In many cases, some of the processes which involve the manufacturing of interesting coating structures, require a precise control of the process in a reactive environment [S.J. Nadel, P. Greene, 'High rate sputtering technology for throughput and quality', International Glass Review, Issue 3, 2001, p. 45. ]. Commonly in these circumstances the plasma is not stable if all the inputs and outputs of the system were to remain constant. The ideal situation is to move a process from set-point A to B in zero time and maintain the monitored signal with a fluctuation equal to zero. In a 'real' process that's not possible but improvements in the time response and energy delivery could be achieved with an appropriate algorithm structure. In this paper an advanced multichannel reactive plasma gas control system is presented. The new controller offers both high-speed gas control combined with a very flexible control structure. The controller uses plasma emission monitoring, target voltage or any process sensor monitoring as the input into a high-speed control algorithm for gas input. The control algorithm and parameters can be tuned to different process requirements in order to optimize response times

  13. A First Look at Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric C02 by the Phoenix Lander

    Science.gov (United States)

    Niles, P.B.; Ming, D.W.; Boynton, W.V.; Hamara, D.; Hoffman, J.H.

    2009-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (isotope fractionations under martian surface conditions. The Thermal Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander included a magnetic sector mass spectrometer (EGA) which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature magnetic sector instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils. Ions produced in the ion source are drawn out by a high voltage and focused by a magnetic field onto a set of collector slits. Four specific trajectories are selected to cover the mass ranges, 0.7 - 4, 7 - 35, 14 - 70, and 28 - 140 Da. Using four channels reduces the magnitude of the mass scan and provides simultaneous coverage of the mass ranges. Channel electron multiplier (CEM) detectors that operate in the pulse counting mode detect the ion beams.

  14. Extraction of 10–30-Day Stable Components from a Boreal Atmosphere during ENSO Phases

    Directory of Open Access Journals (Sweden)

    Kuo Wang

    2015-01-01

    Full Text Available Distinguishing the predictable 10–30-day stable components (STs in the actual atmosphere has been important in atmospheric science research. In this study, a new method for extracting 10–30-day STs was developed with the use of historical observations. We extracted and analyzed 10–30-day STs via statistical extrapolation tests. The results show that the STs are maintained uniformly at the intraseasonal time scale; the overall trends in the atmospheric motion are revealed. Comparisons between pentad-by-pentad changes in the explained variances of the 10–30-day STs under ENSO phases show that the explained variance transmission attenuation trends for El Niño and La Niña years are weaker and more continuous than those of neutral years. Data for 10–30-day STs can remain continuous and stable from one month to the next. The proposed method and results present a new means of extracting predictable STs from the atmosphere using historical data.

  15. Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

    Directory of Open Access Journals (Sweden)

    S. Moukhtar

    2011-11-01

    Full Text Available A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter is presented. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. Particulate matter was collected on quartz fibre filters using dichotomous high volume air samplers. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography and solid phase extraction. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyltrifluoroacetamide, was added for Gas Chromatography-Mass Spectrometry analysis. The second half of the sample was stored in a refrigerator. For samples with concentrations exceeding 1 ng μl−1, the second half of the sample was used for measurement of stable carbon isotope ratios by Gas Chromatography-Isotope Ratio Mass Spectrometry.

    The procedure described in this paper provides a method for the analysis of methylnitrophenols in atmospheric particulate matter at concentrations as low as 0.3 pg m−3 and for stable isotope ratios with an accuracy of better than ±0.5‰ for concentrations exceeding 100 pg m−3.

    In all atmospheric particulate matter samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol, with concentrations ranging from the low pg m−3 range in rural areas to more than 200 pg m−3 in some samples from a suburban location.

  16. Atmospheric conditions important for the assessment of population exposure

    International Nuclear Information System (INIS)

    Vidic, S.

    2005-01-01

    Atmospheric distribution of a pollutant can be predicted using numerical weather prediction models and atmospheric dispersion models. The first provides prediction on the evaluation of the meteorological fields for specified time period and the second uses this information to determine the evolution of the dispersing cloud in time and space. There is a number of conditions and features that limit the performance of both models, as they contain a degree of parametrisation that may be a source of error. This paper discusses influential parameters and conditions.(author)

  17. Quality of Golden papaya stored under controlled atmosphere conditions.

    Science.gov (United States)

    Martins, Derliane Ribeiro; de Resende, Eder Dutra

    2013-10-01

    This work evaluated physicochemical parameters of Golden papaya stored under refrigeration in controlled atmospheres. The fruits were kept at 13  in chambers containing either 3 or 6% O2 combined with 6%, 10% or 15% CO2. Moreover, a normal atmosphere was produced with 20.8% O2 and 0.03% CO2 with ethylene scrubbing, and a control treatment was used with ambient conditions. Evaluations were performed at the following times: before storage, after 30 days of storage in controlled atmosphere, and after removal from controlled atmosphere and storage for 7 days in the cold room. At the lower O2 levels and higher CO2 levels, the ripening rate was decreased. The drop in pulp acidity was avoided after 30 days of storage at 3% O2, but the fruits reached normal acidity after removal from controlled atmosphere and storage for 7 days in the cold room. The reducing sugars remained at a higher concentration after 30 days under 3% O2 and 15% CO2 even 7 days after removal from controlled atmosphere and storage in the cold room. This atmosphere also preserved the content of ascorbic acid at a higher level.

  18. Ocean-atmosphere interaction and synoptic weather conditions in ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Ocean-atmosphere interaction and synoptic weather conditions in association with the two contrasting phases of monsoon during BOBMEX-1999. S P Ghanekar, V R Mujumdar, P Seetaramayya and U V Bhide. Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411 008. Surface meteorological ...

  19. Polyelectrolyte brushes: a novel stable lubrication system in aqueous conditions.

    Science.gov (United States)

    Kobayashi, Motoyasu; Terada, Masami; Takahara, Atsushi

    2012-01-01

    Surface-initiated controlled radical copolymerizations of 2-dimethylaminoethyl methacrylate (DMAEMA), 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), 2-(methacryloyloxy)ethyltrimethylammonium chloride) (MTAC), and 3-sulfopropyl methacrylate potassium salt (SPMK) were carried out on a silicon wafer and glass ball to prepare polyelectrolyte brushes with excellent water wettability. The frictional coefficient of the polymer brushes was recorded on a ball-on-plate type tribometer by linear reciprocating motion of the brush specimen at a selected velocity of 1.5 x 10(-3) m s-1 under a normal load of 0.49 N applied to the stationary glass ball (d = 10 mm) at 298 K. The poly(DMAEMA-co-MPC) brush partially cross-linked by bis(2-iodoethoxy)ethane maintained a relatively low friction coefficient around 0.13 under humid air (RH > 75%) even after 200 friction cycles. The poly(SPMK) brush revealed an extremely low friction coefficient around 0.01 even after 450 friction cycles. We supposed that the abrasion of the brush was prevented owing to the good affinity of the poly(SPMK) brush for water forming a water lubrication layer, and electrostatic repulsive interactions among the brushes bearing sulfonic acid groups. Furthermore, the poly(SPMK-co-MTAC) brush with a chemically cross-linked structure showed a stable low friction coefficient in water even after 1400 friction cycles under a normal load of 139 MPa, indicating that the cross-linking structure improved the wear resistance of the brush layer.

  20. The height of the atmospheric boundary layer during unstable conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gryning, S.E.

    2005-11-01

    The height of the convective atmospheric boundary layer, also called the mixed-layer, is one of the fundamental parameters that characterise the structure of the atmosphere near the ground. It has many theoretical and practical applications such as the prediction of air pollution concentrations, surface temperature and the scaling of turbulence. However, as pointed out by Builtjes (2001) in a review paper on Major Twentieth Century Milestones in Air Pollution Modelling and Its Application, the weakest point in meteorology data is still the determination of the height of the mixed-layer, the so-called mixing height. A simple applied model for the height of the mixed-layer over homogeneous terrain is suggested in chapter 2. It is based on a parameterised budget for the turbulent kinetic energy. In the model basically three terms - the spin-up term and the production of mechanical and convective turbulent kinetic energy - control the growth of the mixed layer. The interplay between the three terms is related to the meteorological conditions and the height of the mixed layer. A stable layer, the so-called entrainment zone, which is confined between the mixed layer and the free air above, caps the mixed layer. A parameterisation of the depth of the entrainment zone is also suggested, and used to devise a combined model for the height of the mixed layer and the entrainment zone. Another important aspect of the mixed layer development exists in coastal areas where an internal boundary layer forms downwind from the coastline. A model for the growth of the internal boundary layer is developed in analogy with the model for mixed layer development over homogeneous terrain. The strength of this model is that it can operate on a very fine spatial resolution with minor computer resources. Chapter 3 deals with the validation of the models. It is based in parts on data from the literature, and on own measurements. For the validation of the formation of the internal boundary layer

  1. Areal-averaged trace gas emission rates from long-range open-path measurements in stable boundary layer conditions

    Directory of Open Access Journals (Sweden)

    K. Schäfer

    2012-07-01

    Full Text Available Measurements of land-surface emission rates of greenhouse and other gases at large spatial scales (10 000 m2 are needed to assess the spatial distribution of emissions. This can be readily done using spatial-integrating micro-meteorological methods like flux-gradient methods which were evaluated for determining land-surface emission rates of trace gases under stable boundary layers. Non-intrusive path-integrating measurements are utilized. Successful application of a flux-gradient method requires confidence in the gradients of trace gas concentration and wind, and in the applicability of boundary-layer turbulence theory; consequently the procedures to qualify measurements that can be used to determine the flux is critical. While there is relatively high confidence in flux measurements made under unstable atmospheres with mean winds greater than 1 m s−1, there is greater uncertainty in flux measurements made under free convective or stable conditions. The study of N2O emissions of flat grassland and NH3 emissions from a cattle lagoon involves quality-assured determinations of fluxes under low wind, stable or night-time atmospheric conditions when the continuous "steady-state" turbulence of the surface boundary layer breaks down and the layer has intermittent turbulence. Results indicate that following the Monin-Obukhov similarity theory (MOST flux-gradient methods that assume a log-linear profile of the wind speed and concentration gradient incorrectly determine vertical profiles and thus flux in the stable boundary layer. An alternative approach is considered on the basis of turbulent diffusivity, i.e. the measured friction velocity as well as height gradients of horizontal wind speeds and concentrations without MOST correction for stability. It is shown that this is the most accurate of the flux-gradient methods under stable conditions.

  2. The exchange of acetaldehyde between plants and the atmosphere: Stable carbon isotope and flux measurements

    Science.gov (United States)

    Jardine, Kolby Jeremiah

    The exchange of acetaldehyde between plant canopies and the atmosphere may significantly influence regional atmospheric chemistry and plant metabolism. While plants are known to both produce and consume acetaldehyde, the exchange of this compound with forested ecosystems is complicated by physical, biological, and chemical processes that range from being poorly understood to completely unknown. This precludes a quantitative understanding of acetaldehyde exchange rates between the atmosphere and the biosphere. In this study, the processes controlling the exchange of acetaldehyde with plant canopies was investigated using concentration, flux, and natural abundance 13C measurements of gas phase acetaldehyde from individual plants, soils, and entire ecosystems. Although previously only considered important in anoxic tissues, it was discovered that acetaldehyde is produced and consumed in leaves through ethanolic fermentation coupled to the pyruvate dehydrogenase bypass system under normal aerobic conditions. These coupled pathways determine the acetaldehyde compensation point, a major factor controlling its exchange with the atmosphere. Carbon isotope analysis suggests a new pathway for acetaldehyde production from plants under stress involving the peroxidation of membrane fatty acids. This pathway may be a major source of acetaldehyde to the atmosphere from plants under biotic and abiotic stresses. Plant stomata were found to be the dominant pathway for the exchange of acetaldehyde with the atmosphere with stomatal conductance influencing both emission and uptake fluxes. In addition, increasing temperature and solar radiation was found to increase the compensation point by increasing the rates of acetaldehyde production relative to consumption. Under ambient conditions, bare soil was neutral to the exchange of acetaldehyde while senescing and decaying leaves were found to be strong source of acetaldehyde to the atmosphere due to increased decomposition processes and

  3. Climatological and atmospheric dispersion conditions at the Cattenom site

    International Nuclear Information System (INIS)

    Jove, J.; Marchand, O.

    1993-03-01

    The statistics in the ''Meteorology'' chapter of the Cattenom safety report concern conditions relating to site climatology (temperature, relative humidity, precipitations, wind speed and direction) and atmospheric dispersion (influence of rain and atmospheric stability on wind speed and wind direction distribution. The data used were provided by the weather station continuously operating on the site, comprising a surface station MISTRAL and a solar. The statistics are based on measurements performed between May 90 and December 92. Generally speaking, these statistics show: -that the Cattenom climatological conditions are very close to those of Metz, - that wind distribution is characterized by a channel effect corresponding to the Moselle valley, - that in rainy weather, the winds come from the SW and are stronger than in dry weather, - that the ''low diffusion'' category corresponds to slight winds oriented through the Moselle valley, whereas in the ''normal diffusion'' category, West winds prevail. (authors). 6 figs., 10 tabs

  4. Design of Multijunction Photovoltaic Cells Optimized for Varied Atmospheric Conditions

    Directory of Open Access Journals (Sweden)

    C. Zhang

    2014-01-01

    Full Text Available Band gap engineering provides an opportunity to not only provide higher overall conversion efficiencies of the reference AM1.5 spectra but also customize PV device design for specific geographic locations and microenvironments based on atmospheric conditions characteristic to that particular location. Indium gallium nitride and other PV materials offer the opportunity for limited bandgap engineering to match spectra. The effects of atmospheric conditions such as aerosols, cloud cover, water vapor, and air mass have been shown to cause variations in spectral radiance that alters PV system performance due to both overrating and underrating. Designing PV devices optimized for spectral radiance of a particular region can result in improved PV system performance. This paper presents a new method for designing geographically optimized PV cells with using a numerical model for bandgap optimization. The geographic microclimate spectrally resolved solar flux for twelve representative atmospheric conditions for the incident radiation angle (zenith angle of 48.1° and fixed array angle of 40° is used to iteratively optimize the band gap for tandem, triple, and quad-layer of InGaN-based multijunction cells. The results of this method are illustrated for the case study of solar farms in the New York region and discussed.

  5. Drying kinetics of RDX under atmospheric pressure and vacuum conditions

    International Nuclear Information System (INIS)

    Zhang, Yaoxuan; Chen, Houhe; Chen, Teng

    2014-01-01

    Highlights: • In this study, RDX is dried in the ranges of 60–90 °C under atmospheric pressure and vacuum conditions. • Ten models are used to describe the drying of RDX. • The Midilli–Kucuk model is determined as the most suitable model. • Effective moisture diffusivity and activation energy for drying process are determined. - Abstract: The drying characteristics of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are investigated in the ranges of 60–90 °C of drying temperature under atmospheric pressure and vacuum conditions in a laboratory scale dryer. The effect of drying temperature and absolute pressure on the drying characteristics is determined. In order to estimate and select the suitable form of RDX drying curves, the curves are fitted to ten different semi-theoretical and/or empirical thin-layer drying models and coefficients are evaluated by non-linear regression analysis. The models are compared based on their coefficient of determination, such as mean bias error, root mean square error, reduced chi-square and modeling efficiency between experimental and predicted moisture ratios. It is deduced that Midilli–Kucuk model has shown a better fit to the experimental drying data as compared to other models. A diffusion model is used to describe the moisture transfer and the effective diffusivity for RDX drying is also determined at each temperature. Beside, the activation energy is also expressed using Arrhenius-type relationship under atmospheric pressure and vacuum conditions

  6. BOREAS RSS-03 Atmospheric Conditions from a Helicopter-Mounted Sunphotometer

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains Helicopter-based measurements of atmospheric conditions acquired during the BOReal Ecosystem-Atmosphere Study (BOREAS) processed to estimates of aerosol...

  7. BOREAS RSS-03 Atmospheric Conditions from a Helicopter-Mounted Sunphotometer

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Contains Helicopter-based measurements of atmospheric conditions acquired during the BOReal Ecosystem-Atmosphere Study (BOREAS) processed to estimates of...

  8. Alteration of municipal and industrial slags under atmospheric conditions

    Science.gov (United States)

    Rafał Kowalski, Piotr; Michalik, Marek

    2014-05-01

    The Waste Management System in Poland is being consequently built since 1998. After important changes in legislation, local governments have taken over the duty of waste collection. New points of selective collection of wastes have been opened and new sorting and composting plants were built. The last stage of introducing the Waste Management System is construction of waste incineration power plants. From nine installations which were planned, six are now under construction and they will start operating within the next two years. It is assumed that the consumption of raw wastes for these installations will reach 974 thousand tons per year. These investments will result in increased slags and ashes production. Now in Poland several local waste incinerators are operating and predominant amount of produced incineration residues is landfilled. These materials are exposed to atmospheric conditions in time of short term storage (just after incineration) and afterwards for a longer period of time on the landfill site. During the storage of slags low temperature mineral transformations and chemical changes may occur and also some components can be washed out. These materials are stored wet because of the technological processes. The aim of this study is to investigate the influence of storage in atmospheric conditions on slags from incineration of industrial and municipal wastes. The experiment started in January 2013. During this period slag samples from incineration of industrial and municipal wastes were exposed to atmospheric conditions. Samples were collected after 6 and 12 months. Within this time the pH value was measured monthly, and during the experimental period remained constant on the level of 9.5. After 6 months of exposure only slight changes in mineral compositions were observed in slags. The results of XRD analysis of municipal slags showed increase in content of carbonate minerals in comparison to the raw slag samples. In industrial slags, a decrease in

  9. Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

    Science.gov (United States)

    Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

    2014-12-01

    Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

  10. Wind turbine aerodynamic response under atmospheric icing conditions

    DEFF Research Database (Denmark)

    Etemaddar, M.; Hansen, Martin Otto Laver; Moan, T.

    2014-01-01

    -four hours of icing, with time varying wind speed and atmospheric icing conditions, was simulated on a rotor. Computational fluid dynamics code, FLUENT, was used to estimate the aerodynamic coefficients of the blade after icing. The results were also validated against wind tunnel measurements performed at LM...... Wind Power using a NACA64618 airfoil. The effects of changes in geometry and surface roughness are considered in the simulation. A blade element momentum code WT-Perf is then used to quantify the degradation in performance curves. The dynamic responses of the wind turbine under normal and iced...

  11. Theoretical predictions of arsenic and selenium species under atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Monahan-Pendergast, M.T.; Przybylek, M.; Lindblad, M.; Wilcox, J. [Worcester Polytechnic Institute, Worcester, MA (United States). Dept. of Chemical Engineering

    2008-03-15

    Thermochemical properties of arsenic and selenium species thought to be released into the atmosphere during the coal combustion were examined using ab initio methods. At various levels of theory, calculated geometries and vibrational frequencies of the species were compared with experimental data, where available. Through a comparison of equilibrium constants for a series of gaseous arsenic and selenium oxidation reactions involving OH and HO{sub 2}, five thermodynamically favored reactions were found. In addition, it was determined that all favored reactions were more likely to go to completion tinder tropospheric, rather than stratospheric, conditions.

  12. Recent advances in understanding atmospheric CO based on stable isotope measurements

    Science.gov (United States)

    Popa, Maria Elena; Naus, Stijn; Ferrero Lopez, Noelia; Vijverberg, Sem; de Leeuw, Selma; Röckmann, Thomas

    2017-04-01

    Carbon monoxide (CO) plays an important role for atmospheric chemistry and for carbon cycling in the atmosphere. Via its reaction with the OH radical it influences concentrations of many other trace gases, it is an important precursor for O3 formation, and its oxidation leads to the formation of about 1 Pg C per year of CO2. The natural and anthropogenic sources of CO are subject to relatively large temporal changes due to natural variability (e.g. biomass burning), industrial activity and mitigation measures (e.g. fossil fuel burning), variations in precursor compounds (e.g. CH4 and VOC) and variations in the abundance of the OH radical in the atmosphere, which are difficult to quantify. Isotope measurements can be used to distinguish between the effects of individual sources and sinks to put tighter constrains on its budget, but the isotopic characterization of the CO sources is in many cases still based on a few relatively old measurements that did not allow to account for dependence on parameters. We will present an update of the isotopic composition of several sources and removal processes of CO that have been carried out in the past years with the automated continuous-flow IRMS system at Utrecht University. This includes: - the previously unknown isotopic composition of direct biogenic CO emissions - a surprisingly large variability in the isotopic composition of CO emitted by different vehicles and single vehicles under various driving conditions - previously very poorly investigated signatures, like the fractionation in the removal of CO by soils, and its interaction with CO that is simultaneously emitted from soil. These results from process specific investigations will be linked to recent atmospheric measurements at various locations.

  13. The effects of atmospheric optical conditions on perceived scenic beauty

    Science.gov (United States)

    Latimer, Douglas A.; Hogo, Henry; Daniel, Terry C.

    This paper describes the results from the first year of a currently on-going study, the objective of which is to investigate the relationships between atmospheric optical conditions and human perceptions of scenic beauty. Color photographs and atmospheric optical measurements, using telephotometers and nephelometers, were taken in the western U.S.A. (Grand Canyon National Park and Mt. Lemmon near Tucson, Arizona) and in the eastern United States (Great Smoky Mountains and Shenandoah national parks). Over 1300 individual observers rated color slides for either visual air quality or scenic beauty using a 10-point rating scale. Ratings were transformed to indices using standard psychophysical techniques. Relationships between these perceptual indices and physical parameters characteristic of the given landscape represented in the color slides were investigated using scatter plots, correlation analysis, and multiple linear regression. Physical parameters included visual range, horizon sky chromaticity and luminance, solar zenith and scattering angles, and cloud conditions. Results show that observers' ratings of visual air quality and scenic beauty are sensitive to visual range, sky color, and scattering angle. However, in some of the areas investigated, scenic beauty ratings were not affected by changes in visual range. The sensitivity of the scenic beauty of a vista to changes in the extinction coefficient may be useful for establishing visibility goals and priorities.

  14. Stable atmospheric methane in the 2000s: key-role of emissions from natural wetlands

    Science.gov (United States)

    Pison, I.; Ringeval, B.; Bousquet, P.; Prigent, C.; Papa, F.

    2013-12-01

    Two atmospheric inversions (one fine-resolved and one process-discriminating) and a process-based model for land surface exchanges are brought together to analyse the variations of methane emissions from 1990 to 2009. A focus is put on the role of natural wetlands and on the years 2000-2006, a period of stable atmospheric concentrations. From 1990 to 2000, the top-down and bottom-up visions agree on the time-phasing of global total and wetland emission anomalies. The process-discriminating inversion indicates that wetlands dominate the time-variability of methane emissions (90% of the total variability). The contribution of tropical wetlands to the anomalies is found to be large, especially during the post-Pinatubo years (global negative anomalies with minima between -41 and -19 Tg yr-1 in 1992) and during the alternate 1997-1998 El-Niño/1998-1999 La-Niña (maximal anomalies in tropical regions between +16 and +22 Tg yr-1 for the inversions and anomalies due to tropical wetlands between +12 and +17 Tg yr-1 for the process-based model). Between 2000 and 2006, during the stagnation of methane concentrations in the atmosphere, the top-down and bottom-up approaches agree on the fact that South America is the main region contributing to anomalies in natural wetland emissions, but they disagree on the sign and magnitude of the flux trend in the Amazon basin. A negative trend (-3.9 ± 1.3 Tg yr-1) is inferred by the process-discriminating inversion whereas a positive trend (+1.3 ± 0.3 Tg yr-1) is found by the process model. Although processed-based models have their own caveats and may not take into account all processes, the positive trend found by the B-U approach is considered more likely because it is a robust feature of the process-based model, consistent with analysed precipitations and the satellite-derived extent of inundated areas. On the contrary, the surface-data based inversions lack constraints for South America. This result suggests the need for a re

  15. Atmospherically stable nanoscale zero-valent iron particles formed under controlled air contact: characteristics and reactivity.

    Science.gov (United States)

    Kim, Hong-Seok; Ahn, Jun-Young; Hwang, Kyung-Yup; Kim, Il-Kyu; Hwang, Inseong

    2010-03-01

    Atmospherically stable NZVI (nanoscale zero-valent iron) particles were produced by modifying shell layers of Fe(H2) NZVI particles (RNIP-10DS) by using a controlled air contact method. Shell-modified NZVI particles were resistant to rapid aerial oxidation and were shown to have TCE degradation rate constants that were equivalent to 78% of those of pristine NZVI particles. Fe(H2) NZVI particles that were vigorously contacted with air (rapidly oxidized) showed a substantially compromised reactivity. Aging of shell-modified particles in water for one day resulted in a rate increase of 54%, implying that depassivation of the shell would play an important role in enhancing reactivity. Aging of shell-modified particles in air led to rate decreases by 14% and 46% in cases of one week and two months of aging, respectively. A series of instrumental analyses using transmission electron microscopy, X-ray diffractography, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure showed that the shells of modified NZVI particles primarily consisted of magnetite (Fe(3)O(4)). Analyses also implied that the new magnetite layer produced during shell modification was protective against shell passivation. Aging of shell-modified particles in water yielded another major mineral phase, goethite (alpha-FeOOH), whereas aging in air produced additional shell phases such as wustite (FeO), hematite (alpha-Fe(2)O(3)), and maghemite (gamma-Fe(2)O(3)).

  16. Variance Method to Determine Turbulent Fluxes of Momentum And Sensible Heat in The Stable Atmospheric Surface Layer

    NARCIS (Netherlands)

    Debruin, H.A.R.; Hartogensis, O.K.

    2005-01-01

    Evidence is presented that in the stable atmospheric surface layer turbulent fluxes of heat and momentum can be determined from the standard deviations of longitudinal wind velocity and temperature, ¿u and ¿T respectively, measured at a single level. An attractive aspect of this method is that it

  17. Atmospheric conditions at Cerro Armazones derived from astronomical data

    Science.gov (United States)

    Lakićević, Maša; Kimeswenger, Stefan; Noll, Stefan; Kausch, Wolfgang; Unterguggenberger, Stefanie; Kerber, Florian

    2016-04-01

    Aims: We studied the precipitable water vapour (PWV) content near Cerro Armazones and discuss the potential use of our technique of modelling the telluric absorbtion lines for the investigation of other molecular layers. The site is designated for the European Extremely Large Telescope (E-ELT) and the nearby planned site for the Čerenkov Telescope Array (CTA). Methods: Spectroscopic data from the Bochum Echelle Spectroscopic Observer (BESO) instrument were investigated by using a line-by-line radiative transfer model (LBLRTM) for the Earth's atmosphere with the telluric absorption correction tool molecfit. All observations from the archive in the period from December 2008 to the end of 2014 were investigated. The dataset completely covers the El Niño event registered in the period 2009-2010. Models of the 3D Global Data Assimilation System (GDAS) were used for further comparison. Moreover, we present a direct comparison for those days for which data from a similar study with VLT/X-Shooter and microwave radiometer LHATPRO at Cerro Paranal are available. Results: This analysis shows that the site has systematically lower PWV values, even after accounting for the decrease in PWV expected from the higher altitude of the site with respect to Cerro Paranal, using the average atmosphere found with radiosondes. We found that GDAS data are not a suitable basis for predicting local atmospheric conditions - they usually systematically overestimate the PWV values. The large sample furthermore enabled us to characterize the site with respect to symmetry across the sky and variation with the years and within the seasons. This technique of studying the atmospheric conditions is shown to be a promising step into a possible monitoring equipment for the CTA. Based on archival observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile and of the Cerro Armazones Observatory facilities of the Ruhr Universität Bochum.Full Table 1

  18. ultra-Stable Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (5STAR)

    Science.gov (United States)

    Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Holben, B. N.; Schmid, B.; Flynn, C. J.; Fahey, L.; LeBlanc, S. E.; Liss, J.; Kacenelenbogen, M. S.; Segal-Rosenhaimer, M.; Shinozuka, Y.; Dahlgren, R. P.; Pistone, K.; Karol, Y.

    2017-12-01

    The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air pollution and climate. Direct beam hyperspectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. Hyperspectral cloud-transmitted radiance measurements enable the retrieval of cloud properties from below clouds. These measurements tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking/ sky-scanning optical head with optical fiber signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical tracking head, and future detector evolution. 4STAR has supported a broad range of flight experiments since it was first flown in 2010. This experience provides the basis for a series of improvements directed toward reducing measurement uncertainty and calibration complexity, and expanding future measurement capabilities, to be incorporated into a new 5STAR instrument. A 9-channel photodiode radiometer with AERONET-matched bandpass filters will be incorporated to improve calibration stability. A wide dynamic range tracking camera will provide a high precision solar position tracking signal as well as an image of sky conditions around the solar axis. An ultrasonic window cleaning system design will be tested. A UV spectrometer tailored for formaldehyde and SO2 gas retrievals will be added to the spectrometer enclosure. Finally, expansion capability for a 4 channel polarized radiometer to measure the Stokes polarization vector of sky light will be incorporated. This paper presents initial progress on this next-generation 5STAR instrument. Keywords: atmosphere; climate; pollution; radiometry; technology; hyperspectral; fiber optic

  19. Inferring atmospheric weather conditions in volcanic environments using infrasound

    Science.gov (United States)

    Ortiz, H. D.; Johnson, J. B.; Ruiz, M. C.

    2015-12-01

    We use infrasound produced by Tungurahua Volcano (Ecuador) to infer local time-varying atmospheric conditions, which can be used to improve gas flux measurements and tephra dispersal modeling. Physical properties of the atmosphere, including wind and temperature (which controls adiabatic sound speed), can be quantified by studying the travel times of acoustic waves produced during volcanic activity. The travel times between Tungurahua's vent and five infrasound stations located in a network configuration over an area of 90 km2 were used in this study. We are able to quantify the arrival time differences of acoustic waves for ten unique station pairs and use this information to model the average speed of sound between source and receiver. To identify what parameters best fit the observed arrival times, we perform a grid search for a homogeneous two-dimensional wind velocity as well as for air temperature. Due to travel time dependence on the specific path taken by waves, we account for topography using a 5 meter resolution digital elevation model of Tungurahua. To investigate the time-varying atmospheric structure we use data recorded at Tungurahua volcano, during a strombolian eruptive phase in August 2012, however the methodology can be applied to continuous network infrasound data collected since July 2006 as part of the Japanese-Ecuadorian Cooperation Project: "Enhancement of the Volcano Monitoring Capacity in Ecuador". We propose that the computation of wind velocities will help to improve gas flux measurements that are based on remote sensing techniques like Differential Optical Absorption Spectroscopy (DOAS), resulting in better estimates of sulfur fluxes that can then be related to magma fluxing into the volcanic system. Further, wind field quantification close to the volcano can improve numerical models that are used to forecast tephra deposits, thereby helping to mitigate their effect on inhabitants, infrastructure, livestock, and crops.

  20. Atmospheric conditions create freeways, detours and tailbacks for migrating birds.

    Science.gov (United States)

    Shamoun-Baranes, Judy; Liechti, Felix; Vansteelant, Wouter M G

    2017-07-01

    The extraordinary adaptations of birds to contend with atmospheric conditions during their migratory flights have captivated ecologists for decades. During the 21st century technological advances have sparked a revival of research into the influence of weather on migrating birds. Using biologging technology, flight behaviour is measured across entire flyways, weather radar networks quantify large-scale migratory fluxes, citizen scientists gather observations of migrant birds and mechanistic models are used to simulate migration in dynamic aerial environments. In this review, we first introduce the most relevant microscale, mesoscale and synoptic scale atmospheric phenomena from the point of view of a migrating bird. We then provide an overview of the individual responses of migrant birds (when, where and how to fly) in relation to these phenomena. We explore the cumulative impact of individual responses to weather during migration, and the consequences thereof for populations and migratory systems. In general, individual birds seem to have a much more flexible response to weather than previously thought, but we also note similarities in migratory behaviour across taxa. We propose various avenues for future research through which we expect to derive more fundamental insights into the influence of weather on the evolution of migratory behaviour and the life-history, population dynamics and species distributions of migrant birds.

  1. Historical (1850–2010 mercury stable isotope inventory from anthropogenic sources to the atmosphere

    Directory of Open Access Journals (Sweden)

    Ruoyu Sun

    2016-02-01

    Full Text Available Abstract Mercury (Hg stable isotopes provide a new tool to trace the biogeochemical cycle of Hg. An inventory of the isotopic composition of historical anthropogenic Hg emissions is important to understand sources and post-emission transformations of Hg. We build on existing global inventories of anthropogenic Hg emissions to the atmosphere to develop the first corresponding historical Hg isotope inventories for total Hg (THg and three Hg species: gaseous elemental Hg (GEM, gaseous oxidized Hg (GOM and particulate-bound Hg (PBM. We compile δ202Hg and Δ199Hg of major Hg emissions source materials. Where possible, δ202Hg and Δ199Hg values in emissions are corrected for the mass dependent Hg isotope fractionation during industrial processing. The framework and Hg isotope inventories can be updated and improved as new data become available. Simulated THg emissions from all sectors between 1850s and 2010s generally show an increasing trend (−1.1‰ to −0.7‰ for δ202Hg, and a stable trend (−0.02‰ to −0.04‰ for Δ199Hg. Δ200Hg are near-zero in source materials and therefore emissions. The δ202Hg trend generally reflects a shift of historically dominant Hg emissions from 19th century Hg mining and liquid Hg0 uses in Au/Ag refining to 20th century coal combustion and non-ferrous metal production. The historical δ202Hg and Δ199Hg curves of GEM closely follow those of THg. The δ202Hg curves of GOM and PBM show no trends. Δ199Hg values for both GOM and PBM decrease from the 1850s to 1950s by ∼0.1‰, and then gradually rebound towards the 2010s. Our updated δ202Hg values (−0.76 ± 0.11 ‰, 1SD, n=9 of bulk emissions from passively degassing volcanoes overlap with δ202Hg of present-day anthropogenic THg emissions.

  2. Cost-effective fabrication of thermal- and chemical-stable ZIF-9 nanocrystals at ammonia atmosphere

    Science.gov (United States)

    Ebrahimi, Arash; Mansournia, Mohammadreza

    2017-12-01

    In this study, room temperature synthesis of zeolitic imidazolate framework-9 (ZIF-9) nanocrystals is reported for the first time at ammonia atmosphere in the absence of any organic additive. High thermal stability of the as-fabricated ZIF-9 up to 300 °C is illustrated by TG and XRD data. Also, the chemical resistance of product to harsh and severe solvothermal conditions introduces it to be an objective as potential material in many applications. Besides, the modest microporosity of the as-obtained ZIF-9 materials attracts more attentions for further investigation compared to those fabricated in organic solvents. By and large, the represented low-cost and room temperature synthetic method can be applicable in the large scale preparation of ZIF-9 for potentially practical utilization.

  3. Filter Media Tests Under Simulated Martian Atmospheric Conditions

    Science.gov (United States)

    Agui, Juan H.

    2016-01-01

    Human exploration of Mars will require the optimal utilization of planetary resources. One of its abundant resources is the Martian atmosphere that can be harvested through filtration and chemical processes that purify and separate it into its gaseous and elemental constituents. Effective filtration needs to be part of the suite of resource utilization technologies. A unique testing platform is being used which provides the relevant operational and instrumental capabilities to test articles under the proper simulated Martian conditions. A series of tests were conducted to assess the performance of filter media. Light sheet imaging of the particle flow provided a means of detecting and quantifying particle concentrations to determine capturing efficiencies. The media's efficiency was also evaluated by gravimetric means through a by-layer filter media configuration. These tests will help to establish techniques and methods for measuring capturing efficiency and arrestance of conventional fibrous filter media. This paper will describe initial test results on different filter media.

  4. A thermal model for photovoltaic panels under varying atmospheric conditions

    International Nuclear Information System (INIS)

    Armstrong, S.; Hurley, W.G.

    2010-01-01

    The response of the photovoltaic (PV) panel temperature is dynamic with respect to the changes in the incoming solar radiation. During periods of rapidly changing conditions, a steady state model of the operating temperature cannot be justified because the response time of the PV panel temperature becomes significant due to its large thermal mass. Therefore, it is of interest to determine the thermal response time of the PV panel. Previous attempts to determine the thermal response time have used indoor measurements, controlling the wind flow over the surface of the panel with fans or conducting the experiments in darkness to avoid radiative heat loss effects. In real operating conditions, the effective PV panel temperature is subjected to randomly varying ambient temperature and fluctuating wind speeds and directions; parameters that are not replicated in controlled, indoor experiments. A new thermal model is proposed that incorporates atmospheric conditions; effects of PV panel material composition and mounting structure. Experimental results are presented which verify the thermal behaviour of a photovoltaic panel for low to strong winds.

  5. Dissolved inorganic carbon and stable carbon isotopic evolution of neutral mine drainage interacting with atmospheric CO2(g).

    Science.gov (United States)

    Abongwa, Pride Tamasang; Atekwana, Eliot Anong; Puckette, James

    2016-03-01

    We investigated the spatial variations in the concentrations of dissolved inorganic carbon (DIC), the stable carbon isotopic composition (δ(13)C) of DIC and the δ(13)C of carbonate precipitated from neutral mine drainage interacting with the atmospheric CO2(g). We assessed the chemical, DIC and δ(13)CDIC evolution of the mine drainage and the δ(13)C evolution of carbonate precipitates for a distance of 562 m from the end of an 8 km tunnel that drains a mine. Our results show that as the mine drainage interacts with atmospheric CO2(g) the outgassing of CO2 due to the high initial partial pressure of CO2 (pCO2) causes the DIC to evolve under kinetic conditions followed by equilibration and then under equilibrium conditions. The carbonate evolution was characterized by spatial increases in pH, decreasing concentrations of Ca(2+) and DIC and by the precipitation of carbonate. The δ(13)CDIC showed a larger enrichment from the tunnel exit to 38 m, moderate continuous enrichment to 318 m and almost no enrichment to 562 m. On the other hand, the δ(13)C of the carbonate precipitates also showed large enrichment from the tunnel exit to 38 m, moderate enrichment to 318 m after which the δ(13)C remained nearly constant. The enrichment in the δ(13)C of the DIC and the carbonate precipitates from 0 to 38 m from kinetic fractionation caused by CO2(g) outgassing was followed by a mix of kinetic fractionation and equilibrium fractionation controlled by carbon exchange between DIC and atmospheric CO2(g) to 318 m and then by equilibrium fractionation from 318 to 562 m. From the carbonate evolution in this neutral mine drainage, we estimated that 20% of the carbon was lost via CO2 outgassing, 12% was sequestered in sediments in the drainage ponds from calcite precipitation and the remainder 68% was exported to the local stream. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Process Model for Studying Regional 13C Stable Isotope Exchange between Vegetation and Atmosphere

    Science.gov (United States)

    Chen, J. M.; Chen, B.; Huang, L.; Tans, P.; Worthy, D.; Ishizawa, M.; Chan, D.

    2007-12-01

    The variation of the stable isotope 13CO2 in the air in exchange with land ecosystems results from fractionation processes in both plants and soil during photosynthesis and respiration. Its diurnal and seasonal variations therefore contain information on the carbon cycle. We developed a model (BEPS-iso) to simulate its exchange between vegetation and the atmosphere. To be useful for regional carbon cycle studies, the model has the following characteristics: (i) it considers the turbulent mixing in the vertical profile from the soil surface to the top of the planetary boundary layer (PBL); (ii) it scales individual leaf photosynthetic discrimination to the whole canopy through the separation of sunlit and shaded leaf groups; (iii) through simulating leaf-level photosynthetic processes, it has the capacity to mechanistically examine isotope discrimination resulting from meteorological forcings, such as radiation, precipitation and humidity; and (iv) through complete modeling of radiation, energy and water fluxes, it also simulates soil moisture and temperature needed for estimating ecosystem respiration and the 13C signal from the soil. After validation using flask data acquired at 20 m level on a tower near Fraserdale, Ontario, Canada, during intensive campaigns (1998-2000), the model has been used for several purposes: (i) to investigate the diurnal and seasonal variations in the disequilibrium in 13C fractionation between ecosystem respiration and photosynthesis, which is an important step in using 13C measurements to separate these carbon cycle components; (ii) to quantify the 13C rectification in the PBL, which differs significantly from CO2 rectification because of the diurnal and seasonal disequilibriums; and (iii) to model the 13C spatial and temporal variations over the global land surface for the purpose of CO2 inversion using 13C as an additional constraint.

  7. A new first-order turbulence mixing model for the stable atmospheric boundary-layer: development and testing in large-eddy and single column models

    Science.gov (United States)

    Huang, J.; Bou-Zeid, E.; Golaz, J.

    2011-12-01

    Parameterization of the stably-stratified atmospheric boundary-layer is of crucial importance to different aspects of numerical weather prediction at regional scales and climate modeling at global scales, such as land-surface temperature forecasts, fog and frost prediction, and polar climate. It is well-known that most operational climate models require excessive turbulence mixing of the stable boundary-layer to prevent decoupling of the atmospheric component from the land component under strong stability, but the performance of such a model is unlikely to be satisfactory under weakly and moderately stable conditions. In this study we develop and test a general turbulence mixing model of the stable boundary-layer which works under different stabilities and for steady as well as unsteady conditions. A-priori large-eddy simulation (LES) tests are presented to motivate and verify the new parameterization. Subsequently, an assessment of this model using the GFDL single-column model (SCM) is performed. Idealized test cases including continuously varying stability, as well as stability discontinuity, are used to test the new SCM against LES results. A good match of mean and flux profiles is found when the new parameterization is used, while other traditional first-order turbulence models using the concept of stability function perform poorly. SCM spatial resolution is also found to have little impact on the performance of the new turbulence closure, but temporal resolution is important and a numerical stability criterion based on the model time step is presented.

  8. Modeling Daily Rainfall Conditional on Atmospheric Predictors: An application to Western Greece

    Science.gov (United States)

    Langousis, Andreas; Kaleris, Vassilios

    2013-04-01

    Due to its intermittent and highly variable character, daily precipitation is the least well reproduced hydrologic variable by both General Circulation Models (GCMs) and Limited Area Models (LAMs). To that extent, several statistical procedures (usually referred to as downscaling schemes) have been suggested to generate synthetic rainfall time series conditional on predictor variables that are descriptive of the atmospheric circulation at the mesoscale. In addition to be more accurately simulated by GCMs and LAMs, large-scale atmospheric predictors are important indicators of the local weather. Currently used downscaling methods simulate rainfall series using either stable statistical relationships (usually referred to as transfer functions) between certain characteristics of the rainfall process and mesoscale atmospheric predictor variables, or simple stochastic schemes (e.g. properly transformed autoregressive models) with parameters that depend on the large-scale atmospheric conditions. The latter are determined by classifying large-scale circulation patterns into broad categories of weather states, using empirical or theoretically based classification schemes, and modeled by resampling from those categories; a process usually referred to as weather generation. In this work we propose a statistical framework to generate synthetic rainfall timeseries at a daily level, conditional on large scale atmospheric predictors. The latter include the mean sea level pressure (MSLP), the magnitude and direction of upper level geostrophic winds, and the 500 hPa geopotential height, relative vorticity and divergence. The suggested framework operates in continuous time, avoiding the use of transfer functions, and weather classification schemes. The suggested downscaling approach is validated using atmospheric data from the ERA-Interim archive (see http://www.ecmwf.int/research/era/do/get/index), and daily rainfall data from Western Greece, for the 14-year period from 01 October

  9. A stable penalty method for the compressible Navier-Stokes equations: I. Open boundary conditions

    DEFF Research Database (Denmark)

    Hesthaven, Jan; Gottlieb, D.

    1996-01-01

    The purpose of this paper is to present asymptotically stable open boundary conditions for the numerical approximation of the compressible Navier-Stokes equations in three spatial dimensions. The treatment uses the conservation form of the Navier-Stokes equations and utilizes linearization...

  10. Entropy Stable Wall Boundary Conditions for the Three-Dimensional Compressible Navier-Stokes Equations

    Science.gov (United States)

    Parsani, Matteo; Carpenter, Mark H.; Nielsen, Eric J.

    2015-01-01

    Non-linear entropy stability and a summation-by-parts framework are used to derive entropy stable wall boundary conditions for the three-dimensional compressible Navier-Stokes equations. A semi-discrete entropy estimate for the entire domain is achieved when the new boundary conditions are coupled with an entropy stable discrete interior operator. The data at the boundary are weakly imposed using a penalty flux approach and a simultaneous-approximation-term penalty technique. Although discontinuous spectral collocation operators on unstructured grids are used herein for the purpose of demonstrating their robustness and efficacy, the new boundary conditions are compatible with any diagonal norm summation-by-parts spatial operator, including finite element, finite difference, finite volume, discontinuous Galerkin, and flux reconstruction/correction procedure via reconstruction schemes. The proposed boundary treatment is tested for three-dimensional subsonic and supersonic flows. The numerical computations corroborate the non-linear stability (entropy stability) and accuracy of the boundary conditions.

  11. Entropy Stable Wall Boundary Conditions for the Compressible Navier-Stokes Equations

    Science.gov (United States)

    Parsani, Matteo; Carpenter, Mark H.; Nielsen, Eric J.

    2014-01-01

    Non-linear entropy stability and a summation-by-parts framework are used to derive entropy stable wall boundary conditions for the compressible Navier-Stokes equations. A semi-discrete entropy estimate for the entire domain is achieved when the new boundary conditions are coupled with an entropy stable discrete interior operator. The data at the boundary are weakly imposed using a penalty flux approach and a simultaneous-approximation-term penalty technique. Although discontinuous spectral collocation operators are used herein for the purpose of demonstrating their robustness and efficacy, the new boundary conditions are compatible with any diagonal norm summation-by-parts spatial operator, including finite element, finite volume, finite difference, discontinuous Galerkin, and flux reconstruction schemes. The proposed boundary treatment is tested for three-dimensional subsonic and supersonic flows. The numerical computations corroborate the non-linear stability (entropy stability) and accuracy of the boundary conditions.

  12. Numerical experiments on the atmospheric response to cold Equatorial Pacific conditions ('La Nina') during northern summer

    International Nuclear Information System (INIS)

    Storch, H. von; Schriever, D.; Arpe, K.; Branstator, G.W.; Legnani, R.; Ulbrich, U.

    1993-01-01

    The effect of cold conditions in the central and eastern Equatorial Pacific during Northern Summer is examined in a series of numerical experiments with the low resolution (T21) atmospheric general circulation model ECHAM2. Anomalous sea surface temperatures (SST) as observed in June 1988 were prescribed and the effect on the global circulation is examined. In the model atmosphere, the anomalous cold water in the Equatorial Pacific excites a strong and stable response over the tropical Central and East Pacific. From here stationary Rossby waves radiate into both hemispheres. The Northern Hemisphere wave train is weak and affects only the Northeast Pacific area; the Southern Hemisphere wave train arches from the Central Pacific over the southern tip of South America to the South Atlantic. This response is not only present in the basic anomaly experiment with the T21 GCM but also in experiments with SST anomalies confined to the tropics and with an envelope-formulation of the SST anomalies, in experiments with a linear model, and in high resolution (T42) model experiments. The model output is also compared to the actually observed atmospheric state in June 1988. (orig./KW)

  13. Neutral molecular cluster formation of sulfuric acid–dimethylamine observed in real time under atmospheric conditions

    Science.gov (United States)

    Kürten, Andreas; Jokinen, Tuija; Simon, Mario; Sipilä, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C.; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H.; Steiner, Gerhard; Tomé, António; Tröstl, Jasmin; Winkler, Paul M.; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S.; Kulmala, Markku; Worsnop, Douglas R.; Curtius, Joachim

    2014-01-01

    For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even though the neutral particles are stable against evaporation from the SA dimer onward, the formation rates of particles at 1.7-nm size, which contain about 10 SA molecules, are up to 4 orders of magnitude smaller compared with those of the dimer due to coagulation and wall loss of particles before they reach 1.7 nm in diameter. This demonstrates that neither the atmospheric particle formation rate nor its dependence on SA can simply be interpreted in terms of cluster evaporation or the molecular composition of a critical nucleus. PMID:25288761

  14. Preliminary Interpretations of Atmospheric Stable Isotopes and Argon from Mars Science Laboratory (SAM)

    Science.gov (United States)

    Jones, J. H.; Niles, P. B.; Webster, C. R.; Mahaffy, P. R.; Flesch, G. J.; Christensen, L. E.; Leshin, L. A.; Franz, H.; Wong, M.; Atreya, S. K.; hide

    2013-01-01

    Given the broad agreement between C, H, and O isotopic ratios in the modern atmosphere and the ALH 84001 meteorite, it is possible that these reservoirs were established after early atmospheric loss prior to 4 Ga. The preservation of these signals over this long period of history can be explained in several slightly different ways: 1) C, O, and H have remained static in the atmosphere and have not exchanged with the surface over the past 4 Ga; 2) C, O, and H in the atmosphere have potentially varied widely over history but have been continually buffered by larger reservoirs in the crust which have remained unchanged over the past 4 Ga. This second possibility allows for potentially large variations in atmospheric pressure to occur as CO2 is recycled back into the atmosphere from crustal reservoirs or degassed from the mantle.

  15. Approaches to daily body condition management in patients with stable chronic obstructive pulmonary disease.

    Science.gov (United States)

    Kawada, Terue

    2016-11-01

    To clarify the characteristics of sub-groups of patients with stable chronic obstructive pulmonary disease having similar approaches to daily body condition management. Prior literature has shed light on the experience of patients with chronic obstructive pulmonary disease and revealed that these patients engage in many activities and try different things in their daily lives to regulate and manage their body condition. The research so far has all been qualitative, comprising mostly interviews, and no quantitative studies have been performed. In this study, cluster analysis was used to show that subgroups of patients with similar characteristics undertake similar approaches to body condition management. Descriptive, correlational study. Invitations to participate in the survey were extended to patients with stable chronic obstructive pulmonary disease. Cluster analysis was performed on the basis of questionnaire scores relating to nine different categories of daily body condition management actions. The characteristics of the body condition management approaches, in each subgroup, were investigated using analysis of variance and multiple comparisons. The cluster analysis produced six subgroups, each defined by the effort expended as part of their body condition management. The subgroups also differed depending on patient age and disease severity. Body condition management approaches taken by patients with stable chronic obstructive pulmonary disease are overall, comprehensive approaches. Patients with chronic obstructive pulmonary disease were subgrouped based on their engagement in body conditioning. Relationships between the subgroups and the engagement in body conditioning, age and shortness of breath severity were observed. The care of patient support should be comprehensive and depend on their age and the duration of the disease. In addition, it should be long term and recognise that the patients are living their own respective lives. Such considerations and

  16. Conditions for maximum isolation of stable condensate during separation in gas-condensate systems

    Energy Technology Data Exchange (ETDEWEB)

    Trivus, N.A.; Belkina, N.A.

    1969-02-01

    A thermodynamic analysis is made of the gas-liquid separation process in order to determine the relationship between conditions of maximum stable condensate separation and physico-chemical nature and composition of condensate. The analysis was made by considering the multicomponent gas-condensate fluid produced from Zyrya field as a ternary system, composed of methane, an intermediate component (propane and butane) and a heavy residue, C/sub 6+/. Composition of 5 ternary systems was calculated for a wide variation in separator conditions. At each separator pressure there is maximum condensate production at a certain temperature. This occurs because solubility of condensate components changes with temperature. Results of all calculations are shown graphically. The graphs show conditions of maximum stable condensate separation.

  17. Description of atmospheric conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)

    NARCIS (Netherlands)

    Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antici'c, T.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Baecker, T.; Badescu, A. M.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Baeuml, J.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Bluemer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Caballero-Mora, K. S.; Caccianiga, B.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chirinos Diaz, J.; Chudoba, J.; Clay, R. W.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordiera, A.; Coutu, S.; Covault, C. E.; Creusota, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; de la Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; del Rio, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Luis, P. Facal San; Tapia, I. Fajardo; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Filevich, A.; Filipcic, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Froehlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Gascon, A.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gomez Berisso, M.; Gomez Vitale, P. F.; Goncalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Guzman, A.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hoerandel, J. R.; Horneffer, A.; Horvath, P.; Hrabovsky, M.; Huber, D.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D. -H.; Kotera, K.; Krohm, N.; Kroemer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; LaHurd, D.; Latronico, L.; Lauer, R.; Lautridou, P.; Le Coz, S.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Agueera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Mi'canovi'c, S.; Micheletti, M. I.; Minaya, I. A.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Mostafa, M.; Moura, C. A.; Muller, M. A.; Mueller, G.; Muenchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Oehlschlaeger, J.; Olinto, A.; Ortiz, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pieroni, P.

    Atmospheric conditions at the site of a cosmic ray observatory must be known for reconstructing observed extensive air showers. The Global Data Assimilation System (GDAS) is a global atmospheric model predicated on meteorological measurements and numerical weather predictions. GDAS provides

  18. Modeling movie success when "nobody knows anything": Conditional stable distribution analysis of film returns

    OpenAIRE

    W David Walls

    2004-01-01

    In this paper we apply a recently-developed statistical model that explicitly accounts for the extreme uncertainty surrounding film returns. The conditional distribution of box-office returns is analyzed using the stable distribution regression model. The regression coefficients in this model represent what is known about the correlates of film success while at the same time permitting the variance of film success at the box office to be infinite. The empirical analysis shows that the conditi...

  19. Does toxicity of aromatic pollutants increase under remote atmospheric conditions?

    Science.gov (United States)

    Kroflič, Ana; Grilc, Miha; Grgić, Irena

    2015-03-09

    Aromatic compounds contribute significantly to the budget of atmospheric pollutants and represent considerable hazard to living organisms. However, they are only rarely included into atmospheric models which deviate substantially from field measurements. A powerful experimental-simulation tool for the assessment of the impact of low- and semi-volatile aromatic pollutants on the environment due to their atmospheric aqueous phase aging has been developed and introduced for the first time. The case study herein reveals that remote biotopes might be the most damaged by wet urban guaiacol-containing biomass burning aerosols. It is shown that only after the primary pollutant guaiacol has been consumed, its probably most toxic nitroaromatic product is largely formed. Revising the recent understanding of atmospheric aqueous phase chemistry, which is mostly concerned with the radical nitration mechanisms, the observed phenomenon is mainly attributed to the electrophilic nitrogen-containing reactive species. Here, their intriguing role is closely inspected and discussed from the ecological perspective.

  20. On the formation of sulphuric acid – amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation

    Directory of Open Access Journals (Sweden)

    I. K. Ortega

    2012-10-01

    Full Text Available Sulphuric acid is a key component in atmospheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate particle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (JA2B2 at varying atmospherically relevant conditions with respect to concentrations of sulphuric acid ([H2SO4], dimethylamine ([DMA] and trimethylamine ([TMA], temperature and relative humidity (RH. We also tested how the model results change if we assume that the clusters with two sulphuric acid and two amine molecules would act as seeds for heterogeneous nucleation of organic vapours (other than amines with higher atmospheric concentrations than sulphuric acid. The modelled formation rates JA2B2 were functions of sulphuric acid concentration with close to quadratic dependence, which is in good agreement with atmospheric observations of the connection between the particle formation rate and sulphuric acid concentration. The coefficients KA2B2 connecting the cluster formation rate and sulphuric acid concentrations as JA2B2=KA2B2[H2SO4]2 turned out to depend also on amine concentrations, temperature and relative humidity. We compared the modelled coefficients KA2B2 with the corresponding coefficients calculated from the atmospheric observations (Kobs from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of JA2B2 as a function of [H2SO4], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the traditional semi-empirical formulae based on sulphuric acid concentration only. The formation rates of clusters with two sulphuric acid and two amine molecules with different amine compositions (DMA or TMA or one of both had

  1. CFD Modeling of Non-Neutral Atmospheric Boundary Layer Conditions

    DEFF Research Database (Denmark)

    Koblitz, Tilman

    . All implementations in the ABL model are tuning free, and except for standard site specific input parameters, no additional model coefficients need to be specified before the simulation. In summary the results show that the implemented modifications are applicable and reproduce the main flow......For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface-layer. Physical processes like the Coriolis force, buoyancy forces and heat transport, that are important...... to the atmospheric boundary-layer, are mostly ignored so far. In order to decrease the uncertainty of wind resource assessment, the present work focuses on atmospheric flows that include atmospheric stability and the Coriolis effect. Within the present work a RANS model framework is developed and implemented...

  2. Study of stable atmospheric boundary layer characterization over highveld region of South Africa

    CSIR Research Space (South Africa)

    Luhunga, P

    2011-09-01

    Full Text Available : Earth and Environmental Science 13 (2010) 012012 doi:10.1088/1755-1315/13/1/012012 Businger JA, Wyngaard JC, Uzumi Y and EF Bradley, 1971, Flux-profile relationship in the atmospheric surface layer, J Atm Sci, 28, 181-189. Kolmogorov AN, 1941... ATMOSPHERIC BOUNDARY LAYER CHARACTERIZATION OVER HIGHVELD REGION OF SOUTH AFRICA Philbert Luhunga1, 2, 3, George Djolov1, Venkataraman Sivakumar1,4,5 1 University of Pretoria, Department of Geography Geoinformatics and Meterology, Lynnwood road, 0001...

  3. A Study of stable Atmospheric Boundary Layer over highveld South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Luhunga, P; Djolov, G [University of Pretoria (South Africa); Esau, I, E-mail: george.djolov@up.ac.z

    2010-08-15

    The study is part of the South African - Norwegian Programme for Research and Co-operation Phase II 'Analysis and Possibility for Control of Atmospheric Boundary Layer Processes to Facilitate Adaptation to Environmental Changes'. The research strategy of the project is based on 4 legged approach. 1) Application and further development of contemporary atmospheric boundary layer theory. 2) Use of modeling based on large eddy simulation techniques. 3) Experimental investigation of turbulent fluxes. 4) Training and developing academics capable of dealing with the present and new challenges. The paper presents some preliminary results on the micrometeorological variability of the basic meteorological parameters and turbulent fluxes.

  4. Stable isotope characterization of pan-derived and directly sampled atmospheric water vapour

    International Nuclear Information System (INIS)

    Maric, R.; St. Amour, N.A.; Gibson, J.J.; Edwards, T.W.D.

    2002-01-01

    Isotopic characterization of atmospheric water vapour, δ A , and its temporal variability are important prerequisites for quantifying water balance of surface reservoirs and partitioning of evaporation and transpiration fluxes using isotope techniques. Here we present results from a detailed comparison of several methods for determining δ A in field situations, (i) by back-calculation from isotopic and micrometeorological monitoring of a steady-state terminal reservoir (standard Class-A evaporation pan) using boundary-layer mass transfer models [1], (ii) through direct (cryogenic) sampling of ambient atmospheric moisture, and (iii) using the precipitation-equilibrium approximation (i.e., δ A =δ P - ε*)

  5. Preface: GEWEX Atmospheric Boundary-layer Study (GABLS) on Stable Boundary Layers

    NARCIS (Netherlands)

    Holtslag, A.A.M.

    2006-01-01

    The Global Energy and Water Cycle Experiment (GEWEX) is a program initiated by the World Climate Research Programme (WCRP) to observe, understand and model the hydrological cycle and the related energy fluxes in the atmosphere, at the land surface and in the upper oceans. Consequently the

  6. Ocean-atmosphere interaction and synoptic weather conditions in ...

    Indian Academy of Sciences (India)

    ... period of strong north-south pressure gradient over the Bay region. Events of prominent fall in SST and in the upper 15m ocean layer mean temperature and salinity values during typical rainfall events are cited. The impact of monsoon disturbances on ocean-atmosphere interface transfer processes has been investigated.

  7. The role of ions in particle nucleation under atmospheric conditions

    DEFF Research Database (Denmark)

    Enghoff, Martin B.; Pedersen, J. O. P.; Bondo, T.

    2008-01-01

    Aerosol nucleation has been studied experimentally in purified, atmospheric air, containing trace amounts of water vapor, ozone, and sulfur dioxide. The results are compared with model calculations. It is found that an increase in ionization by a factor of 10 increases the production rate of stab...

  8. Computer Modeling of the Effects of Atmospheric Conditions on Sound Signatures

    Science.gov (United States)

    2016-02-01

    goals of the project were to analyze the effects of atmospheric conditions on sound propagation, create a filter to model effects under different ...layer-by-layer description of the atmosphere. The atmospheric propagation effect at different distances is then generated as a matrix of decibel...between 9 different ground conditions: New Fallen Snow, 2-Layer Snow, Sugar Snow, Forest Floor, Grass Covered Pasture, Roadside Dirt, Packed Sandy Silt

  9. Development and field testing of a rapid and ultra-stable atmospheric carbon dioxide spectrometer

    OpenAIRE

    B. Xiang; D. D. Nelson; J. B. McManus; M. S. Zahniser; R. Wehr; S. C. Wofsy

    2014-01-01

    We present field test results for a new spectroscopic instrument to measure atmospheric carbon dioxide (CO2) with high precision (0.02 ppm at 1 Hz) and demonstrate high stability (within 0.1 ppm over more than 8 months), without the need for hourly, daily, or even monthly calibration against high-pressure gas cylinders. The technical novelty of this instrument (ABsolute Carbon dioxide, ABC) is the spectral null method using an internal quartz reference cell with known...

  10. Xe anions in stable Mg-Xe compounds: the mechanism of missing Xe in earth atmosphere

    OpenAIRE

    Miao, Mao-sheng

    2013-01-01

    The reactivity of noble gas elements is important for both fundamental chemistry and geological science. The discovery of the oxidation of Xe extended the doctrinal boundary of chemistry that a complete shell is inert to reaction. The oxidations of Xe by various geological substances have been researched in order to explain the missing Xe in earth atmosphere. Among many proposals, the chemistry mechanisms are straightforward as they identify chemical processes that can capture Xe in earth int...

  11. Treatment of stable and recalcitrant depigmented skin conditions by autologous punch grafting

    Directory of Open Access Journals (Sweden)

    Lahiri Koushik

    1997-01-01

    Full Text Available Sixty cases of stable and refractory depigmented skin conditions which include local vitiligo, segmental vitiligo, chemical leucoderma, vitiligo vulgaris, post-burn depigmentation etc constitute the study group. 39 of them were female and 21 male. Age ranged between 6 and 67 years. 1057 grafts were placed over 114 lesions and the cases were followed up to a period of 18 months. 70% to 100% repigmentation was observed in 56 lesions of 31 patients. Rate and extent of perigraft pigment spread was noted. Patients under PUVASOL showed a distinctly better response. Sequelae like cobble-stoning and polka-dotting were found to be disappearing with time or interference.

  12. Thermophysical Properties Measurement of High-Temperature Liquids Under Microgravity Conditions in Controlled Atmospheric Conditions

    Science.gov (United States)

    Watanabe, Masahito; Ozawa, Shumpei; Mizuno, Akotoshi; Hibiya, Taketoshi; Kawauchi, Hiroya; Murai, Kentaro; Takahashi, Suguru

    2012-01-01

    Microgravity conditions have advantages of measurement of surface tension and viscosity of metallic liquids by the oscillating drop method with an electromagnetic levitation (EML) device. Thus, we are preparing the experiments of thermophysical properties measurements using the Materials-Science Laboratories ElectroMagnetic-Levitator (MSL-EML) facilities in the international Space station (ISS). Recently, it has been identified that dependence of surface tension on oxygen partial pressure (Po2) must be considered for industrial application of surface tension values. Effect of Po2 on surface tension would apparently change viscosity from the damping oscillation model. Therefore, surface tension and viscosity must be measured simultaneously in the same atmospheric conditions. Moreover, effect of the electromagnetic force (EMF) on the surface oscillations must be clarified to obtain the ideal surface oscillation because the EMF works as the external force on the oscillating liquid droplets, so extensive EMF makes apparently the viscosity values large. In our group, using the parabolic flight levitation experimental facilities (PFLEX) the effect of Po2 and external EMF on surface oscillation of levitated liquid droplets was systematically investigated for the precise measurements of surface tension and viscosity of high temperature liquids for future ISS experiments. We performed the observation of surface oscillations of levitated liquid alloys using PFLEX on board flight experiments by Gulfstream II (G-II) airplane operated by DAS. These observations were performed under the controlled Po2 and also under the suitable EMF conditions. In these experiments, we obtained the density, the viscosity and the surface tension values of liquid Cu. From these results, we discuss about as same as reported data, and also obtained the difference of surface oscillations with the change of the EMF conditions.

  13. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    Science.gov (United States)

    Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  14. Stable Carbon Isotope Ratios in Atmospheric VOC across the Asian Summer Monsoon Anticyclone obtained during the OMO-ASIA campaign

    Science.gov (United States)

    Krebsbach, Marc; Koppmann, Ralf; Meisehen, Thomas

    2017-04-01

    The automated high volume air sampling system (MIRAH) has been deployed during the atmospheric measurement campaign OMO-ASIA (Oxidation Mechanism Observations) with the German High Altitude - Long-range research aircraft (HALO) in July and August 2015. The intensive measurement period with base stations in Paphos (Cyprus) and Gan (Maldives) focussed on oxidation processes and air pollution chemistry downwind of the South Asia summer monsoon anticyclone, a pivot area critical for air quality and climate change, both regionally and worldwide. The measurement region covered the Eastern Mediterranean region, the Arabian Peninsula, Egypt, and the Arabian Sea. In total 194 air samples were collected on 17 flights in a height region from 3 km up to 15 km. The air samples were analysed for stable carbon isotope ratios in VOC with GC-C-IRMS in the laboratory afterwards. We determined stable carbon isotope ratios and mixing ratios of several aldehydes, ketones, alcohols, and aromatics. The large extent of the investigated area allowed for encountering air masses with different origin, characteristic, and atmospheric processing, e.g. Mediterranean air masses, crossing of polluted filaments and remnants of the Asian monsoon outflow, split of the Asian monsoon anticyclone. In this presentation we will show first results and interpretations supported by HYSPLIT backward trajectories.

  15. Ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions

    DEFF Research Database (Denmark)

    Selsted, Merete Bang

    on ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions, shows that extended summer drought in combination with elevated temperature will ensure permanent dryer soil conditions, which decreases carbon turnover, while elevated atmospheric CO2 concentrations will increase....... Fluxes of CO2 from soil to atmosphere depend on a physical equilibrium between those two medias, why it is important to keep the CO2 gradient between soil and atmosphere unchanged during measurement. Uptake to plants via photosynthesis depends on a physiological process, which depends strongly...... on the atmospheric CO2 concentration. Photosynthesis and respiration run in parallel during measurements of net ecosystem exchange, and these measurements should therefore be performed with care to both the atmospheric CO2 concentration and the CO2 soil-atmosphere gradient....

  16. Development and field testing of a rapid and ultra-stable atmospheric carbon dioxide spectrometer

    OpenAIRE

    B. Xiang; D. D. Nelson; J. B. McManus; M. S. Zahniser; R. A. Wehr; S. C. Wofsy

    2014-01-01

    We present field test results for a new spectroscopic instrument to measure atmospheric carbon dioxide (CO2) with high precision (0.02 μmol mol−1, or ppm at 1 Hz) and demonstrate high stability (within 0.1 ppm over more than 8 months), without the need for hourly, daily, or even monthly calibration against high-pressure gas cylinders. The technical novelty of this instrument (ABsolute Carbon dioxide, ABC) is the spectral null method using an internal quartz reference cell wi...

  17. Atmospheric conditions, lunar phases, and childbirth: a multivariate analysis

    Science.gov (United States)

    Ochiai, Angela Megumi; Gonçalves, Fabio Luiz Teixeira; Ambrizzi, Tercio; Florentino, Lucia Cristina; Wei, Chang Yi; Soares, Alda Valeria Neves; De Araujo, Natalucia Matos; Gualda, Dulce Maria Rosa

    2012-07-01

    Our objective was to assess extrinsic influences upon childbirth. In a cohort of 1,826 days containing 17,417 childbirths among them 13,252 spontaneous labor admissions, we studied the influence of environment upon the high incidence of labor (defined by 75th percentile or higher), analyzed by logistic regression. The predictors of high labor admission included increases in outdoor temperature (odds ratio: 1.742, P = 0.045, 95%CI: 1.011 to 3.001), and decreases in atmospheric pressure (odds ratio: 1.269, P = 0.029, 95%CI: 1.055 to 1.483). In contrast, increases in tidal range were associated with a lower probability of high admission (odds ratio: 0.762, P = 0.030, 95%CI: 0.515 to 0.999). Lunar phase was not a predictor of high labor admission ( P = 0.339). Using multivariate analysis, increases in temperature and decreases in atmospheric pressure predicted high labor admission, and increases of tidal range, as a measurement of the lunar gravitational force, predicted a lower probability of high admission.

  18. New Polymorph of Fe3O4 Stable at Core-Mantle Boundary Conditions

    Science.gov (United States)

    Greenberg, E.; Prakapenka, V. B.

    2017-12-01

    Magnetite Fe3O4 (and its high-pressure polymorphs) is one of the most studied iron bearing minerals. One reason for the interest in magnetite is that it contains both Fe2+ and Fe3+, which is especially important for understanding the physical and chemical properties of Earth's deep interior. Early studies on magnetite debated the nature of the structural phase transition at 35 GPa [1-4]. This high-pressure structure was shown to be of the CaTi2O4-type [5], but with Fe3+ occupying multiple sites. Furthermore, at pressures above 65 GPa a second structural transition to a Pmma space group was shown to take place [5], similar to that in Fe3-xTixO4 solid solution [6]. Other studies have focused on the P-T stability of Fe3O4. Early studies by Lazor et al. [7] predicted that Fe3O4 might disproportionate into FeO and h-Fe2O3 at 50 GPa. Other studies suggested that the high-pressure phase should be stable up to 100 GPa [3]. A more recent experimental study by Ricolleau and Fei [8] revealed that Fe3O4 is stable at least up to 103 GPa. Thus far, structural studies of Fe3O4 have been limited to pressures below 105 GPa. We have studied Fe3O4 up to pressures of 175 GPa and temperatures above 4000K, using diamond anvil cells in combination with synchrotron x-ray diffraction and an online pulsed laser-heating system to study the stability of Fe3O4 at relevant pressure-temperature conditions. Our results show that Fe3O4 is stable up to at least 176 GPa and 4200 K. We have discovered a new polymorph of Fe3O4 at these high P-T conditions. This new phase is stable in the pressure range of at least 100Review B 70, 174106 (2004). [5] Greenberg et al. Physical Review B 95, 195150 (2017). [6] Yamanaka et al. American Mineralogist 98, 736 (2013). [7] Lazor et al. Journal of Geophysical Research 109, B05201 (2004). [8] Ricolleau and Fei. American Mineralogist 101, 719 (2016).

  19. Modified atmospheric conditions controlling fungal growth on cheese

    DEFF Research Database (Denmark)

    Nielsen, Per Væggemose

    1997-01-01

    a competitive advantage over other fungi in moist conditions with high carbon dioxide levels, such as inside a roquefort cheese or in gas tight grain storage. The key to success in food packaging is to recognise the food ecosystem, as it enables us to identify which micro......Effective control of fungal growth on cheese under storage conditions is of great concern for the dairy industry. Therefore we designed a research project together with the Danish dairy industry on modelling fungal growth on cheese as affected by the combined effect of storage conditions (O2 and CO...

  20. Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes.

    Science.gov (United States)

    Vizza, Carmella; Sanderson, Beth L; Coe, Holly J; Chaloner, Dominic T

    2017-03-01

    Stable isotope ratios (δ 13 C and δ 15 N) have been used extensively to trace nutrients from Pacific salmon, but salmon transfer more than carbon and nitrogen to stream ecosystems, such as phosphorus, minerals, proteins, and lipids. To examine the importance of these nutrients, metrics other than isotopes need to be considered, particularly when so few studies have made direct links between these nutrients and how they affect riparian organisms. Our study specifically examined δ 13 C and δ 15 N of riparian organisms from salmon and non-salmon streams in Idaho, USA, at different distances from the streams, and examined whether the quality of riparian plants and the body condition of invertebrates varied with access to these nutrients. Overall, quality and condition metrics did not mirror stable isotope patterns. Most notably, all riparian organisms exhibited elevated δ 15 N in salmon streams, but also with proximity to both stream types suggesting that both salmon and landscape factors may affect δ 15 N. The amount of nitrogen incorporated from Pacific salmon was low for all organisms (1950s. In addition, our results support those of other studies that have cautioned that inferences from natural abundance isotope data, particularly in conjunction with mixing models for salmon-derived nutrient percentage estimates, may be confounded by biogeochemical transformations of nitrogen, physiological processes, and even historical legacies of nitrogen sources. Critically, studies should move beyond simply describing isotopic patterns to focusing on the consequences of salmon-derived nutrients by quantifying the condition and fitness of organisms putatively using those resources.

  1. Muscle activation during push-ups performed under stable and unstable conditions.

    Science.gov (United States)

    Borreani, Sebastien; Calatayud, Joaquin; Colado, Juan Carlos; Moya-Nájera, Diego; Triplett, N Travis; Martin, Fernando

    2015-12-01

    The purpose of this study was to analyze muscle activation when performing push-ups under different stability conditions. Physically fit young male university students ( N  = 30) performed five push-ups under stable conditions (on the floor) and using four unstable devices (wobble board, stability disc, fitness dome, and the TRX Suspension Trainer). The push-up speed was controlled using a metronome, and the testing order was randomized. The average amplitudes of the electromyographic (EMG) root mean square of the anterior deltoid (DELT), serratus anterior (SERRA), lumbar multifidus (LUMB), and rectus femoris (FEM) were recorded. The electromyographic signals were normalized to the maximum voluntary isometric contraction (MVIC). No significant differences were found for the DELT [ F (4,112) = 1.978; p  = 0.130] among the conditions. However, statistically significant differences were found among the different conditions for the SERRA [ F (4,60) = 17.649; p  ups performed on the floor showed lower SERRA activation than those performed with all unstable devices. Not all unstable devices enhance muscle activation compared to traditional push-ups.

  2. Ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions

    DEFF Research Database (Denmark)

    Selsted, Merete Bang

    on ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions, shows that extended summer drought in combination with elevated temperature will ensure permanent dryer soil conditions, which decreases carbon turnover, while elevated atmospheric CO2 concentrations will increase...... carbon turnover. In the full future climate scenario, carbon turnover is over all expected to increase and the heathland to become a source of atmospheric CO2. The methodology of static chamber CO2 flux measurements and applying the technology in a FACE (free air CO2 enrichment) facility is a challenge...... on the atmospheric CO2 concentration. Photosynthesis and respiration run in parallel during measurements of net ecosystem exchange, and these measurements should therefore be performed with care to both the atmospheric CO2 concentration and the CO2 soil-atmosphere gradient....

  3. Indoor and outdoor urban atmospheric CO2: Stable carbon isotope constraints on mixing and mass balance

    International Nuclear Information System (INIS)

    Yanes, Yurena; Yapp, Crayton J.

    2010-01-01

    suggests that the intercept of a mixing line defined by two data points (CO 2 input from the local ventilation system and CO 2 in the ambient air of the room) could be a reasonable estimate of the average δ 13 C value of the CO 2 exhaled by the human occupants. Thus, such indoor spaces appear to constitute effective 'sample vessels' for collection of CO 2 that can be used to determine the average proportions of C 3 and C 4 -derived C in the diets of the occupants. For the various groups occupying the rooms sampled in this study, C 4 -derived C appears to have constituted ∼40% of the average diet. The average concentration of outdoor Dallas atmospheric CO 2 was ∼17 ppm higher than the average of CO 2 concentrations measured on the same campus 10 a ago. In addition, Dallas outdoor CO 2 concentrations at both times were higher than the contemporaneous global atmospheric CO 2 concentrations. This observation, plus the fact that the increase of ∼17 ppm in the average concentration of Dallas outdoor CO 2 was comparable to the global increase of ∼18 ppm over the same 10-a interval, is consistent with a significant role for urban CO 2 'factories' in the global atmospheric CO 2 budget.

  4. Atmospheric synoptic conditions of snow precipitation in East Antarctica using ice core and reanalysis data

    Science.gov (United States)

    Scarchilli, Claudio; Ciardini, Virginia; Bonazza, Mattia; Frezzotti, Massimo; Stenni, Barbara

    2014-05-01

    In the framework of the International Partnerships in Ice Core Sciences (IPCS) initiatives the GV7 site (70°41' S - 158°51' E) in East Antarctica was chosen as the new drilling site for the Italian contribution to the understanding of the climatic variability in the last 2000 years (IPICS 2k Array). Water stable isotopes and snow accumulation (SMB) values from a shallow firn core, obtained at GV7 during the 2001-2002 International Trans-Antarctic Scientific Expedition (ITASE) traverse, are analyzed and compared with different meteorological model output in order to characterize the atmospheric synoptic conditions driving precipitation events at the site. On annual basis, ECMWF +24h forecasted snowfalls (SF) seem to well reproduce GV7 SMB values trend for the period from 1980 to 2005. Calculated air mass back-trajectories show that Eastern Indian - Western Pacific oceans represent the main moisture path toward the site during autumn - winter season. Analysis of the ECMWF 500 hPa Geopotential height field (GP500) anomalies shows that atmospheric blocking events developing between 130° E and 150° W at high latitudes drive the GV7 SMB by blocking zonal flow and conveying warm and moist deep air masses from ocean into the continental interior. On inter-annual basis, The SF variability over GV7 region follows the temporal oscillation of the third CEOF mode (CEOF3 10% of the total explained variance) of a combined complex empirical orthogonal function (CEOF) performed over GP500 and SF field. The CEOF3 highlights an oscillating feature, with wavenumber 2, in GP500 field over the Western Pacific-Eastern Indian Oceans and propagating westward. The pattern is deeply correlated with the Indian Dipole Oscillation and ENSO and their associated quasi-stationary Rossby waves propagating from the lower toward the higher latitudes.

  5. Necessary Conditions For Establishing Quasi-Stable Double Layers in Earth's Auroral Upward Current Region

    Science.gov (United States)

    Main, D. S.; Newman, D.; Ergun, R. E.

    2010-12-01

    Observations from the Fast Auroral SnapshoT (FAST) spacecraft indicate that a strong localized electric field often exists at the boundary between the ionosphere and auroral cavity in the upward current region. The observed electric field structures are found to have widths that are on the order of tens of electron Debye lengths and have components both parallel and perpendicular to Earth’s magnetic field and are therefore said to be an “oblique” electric field. These oblique electric fields have previously been modeled by static BGK double layer solutions. Dynamic Vlasov simulations have shown that a non-oblique double layer models the parallel component of the observed electric field structures well, is quasi-stable and persists long enough to account for the often observed ion phase space holes in the auroral cavity. However, to date, it has not been clear how an oblique double layer can form and remain quasi-stable. Using an open boundary 1D3V particle-in-cell simulation, we present a parameter study of over 20 simulations in which we vary cold electron density and temperature and show the necessary conditions for maintaining both oblique and non-oblique double layers at the lower boundary of the upward current region. The simulation includes an assumed density cavity, hot auroral cavity electrons, cold ionospheric electrons, a hot H+ component and anti-earthward traveling H+ and O+ ion beams. We do not assume that any localized potential drop initially exists. Rather, if a DL forms, it does so self-consistently at the interface of the dense ionosphere and tenuous auroral cavity. Based on the PIC results, we find that the oblique double layer requires a cold (< 5 eV) ionospheric electron population to remain quasi-stable. We also compare the shape of the simulated double layer with observed double layers and show that the observed asymmetric shape can also be explained by the temperature and density of the cold ionospheric electrons. We will also present

  6. Development and field testing of a rapid and ultra-stable atmospheric carbon dioxide spectrometer

    Science.gov (United States)

    Xiang, B.; Nelson, D. D.; McManus, J. B.; Zahniser, M. S.; Wehr, R. A.; Wofsy, S. C.

    2014-12-01

    We present field test results for a new spectroscopic instrument to measure atmospheric carbon dioxide (CO2) with high precision (0.02 μmol mol-1, or ppm at 1 Hz) and demonstrate high stability (within 0.1 ppm over more than 8 months), without the need for hourly, daily, or even monthly calibration against high-pressure gas cylinders. The technical novelty of this instrument (ABsolute Carbon dioxide, ABC) is the spectral null method using an internal quartz reference cell with known CO2 column density. Compared to a previously described prototype, the field instrument has better stability and benefits from more precise thermal control of the optics and more accurate pressure measurements in the sample cell (at the mTorr level). The instrument has been deployed at a long-term ecological research site (the Harvard Forest, USA), where it has measured for 8 months without on-site calibration and with minimal maintenance, showing drift bounds of less than 0.1 ppm. Field measurements agree well with those of a commercially available cavity ring-down CO2 instrument (Picarro G2301) run with a standard calibration protocol. This field test demonstrates that ABC is capable of performing high-accuracy, unattended, continuous field measurements with minimal use of reference gas cylinders.

  7. Stable isotopes in atmospheric water vapor and applications to the hydrologic cycle

    Science.gov (United States)

    Galewsky, Joseph; Steen-Larsen, Hans Christian; Field, Robert D.; Worden, John; Risi, Camille; Schneider, Matthias

    2016-12-01

    The measurement and simulation of water vapor isotopic composition has matured rapidly over the last decade, with long-term data sets and comprehensive modeling capabilities now available. Theories for water vapor isotopic composition have been developed by extending the theories that have been used for the isotopic composition of precipitation to include a more nuanced understanding of evaporation, large-scale mixing, deep convection, and kinetic fractionation. The technologies for in situ and remote sensing measurements of water vapor isotopic composition have developed especially rapidly over the last decade, with discrete water vapor sampling methods, based on mass spectroscopy, giving way to laser spectroscopic methods and satellite- and ground-based infrared absorption techniques. The simulation of water vapor isotopic composition has evolved from General Circulation Model (GCM) methods for simulating precipitation isotopic composition to sophisticated isotope-enabled microphysics schemes using higher-order moments for water and ice size distributions. The incorporation of isotopes into GCMs has enabled more detailed diagnostics of the water cycle and has led to improvements in its simulation. The combination of improved measurement and modeling of water vapor isotopic composition opens the door to new advances in our understanding of the atmospheric water cycle, in processes ranging from the marine boundary layer, through deep convection and tropospheric mixing, and into the water cycle of the stratosphere. Finally, studies of the processes governing modern water vapor isotopic composition provide an improved framework for the interpretation of paleoclimate proxy records of the hydrological cycle.

  8. Response of stable carbon isotope in epilithic mosses to atmospheric nitrogen deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xueyan, E-mail: liuxueyan@vip.skleg.c [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Xiao Huayun; Liu Congqiang [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Li Youyi; Xiao Hongwei; Wang Yanli [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002 (China); Graduate University of Chinese Academy of Sciences, Yuquanlu, Beijing 100049 (China)

    2010-06-15

    Epilithic mosses are characterized by insulation from substratum N and hence meet their N demand only by deposited N. This study investigated tissue C, total Chl and delta{sup 13}C of epilithic mosses along 2 transects across Guiyang urban (SW China), aiming at testing their responses to N deposition. Tissue C and total Chl decreased from the urban to rural, but delta{sup 13}C{sub moss} became less negative. With measurements of atmospheric CO{sub 2} and delta{sup 13}CO{sub 2}, elevated N deposition was inferred as a primary factor for changes in moss C and isotopic signatures. Correlations between total Chl, tissue C and N signals indicated a nutritional effect on C fixation of epilithic mosses, but the response of delta{sup 13}C{sub moss} to N deposition could not be clearly differentiated from effects of other factors. Collective evidences suggest that C signals of epilithic mosses are useful proxies for N deposition but further works on physiological mechanisms are still needed. - Photosynthetic {sup 13}C discrimination of bryophytes might increase with elevated N deposition.

  9. Formation of stable direct current microhollow cathode discharge by venturi gas flow system for remote plasma source in atmosphere

    International Nuclear Information System (INIS)

    Park, Ki Wan; Lee, Tae Il; Hwang, Hyeon Seok; Noh, Joo Hyon; Baik, Hong Koo; Song, Kie Moon

    2008-01-01

    We introduce a microhollow cathode configuration with venturi gas flow to ambient air in order to obtain glow discharge at atmospheric pressure. Stable microhollow cathode discharge was formed in a 200 μm diameter at 9 mA and the optimum value of gas velocityxdiameter for hollow cathode effect was obtained in our system. In order to confirm hollow cathode effect, we measured the enhancement of E/N strength for 200 μm (0.31 m 2 /s) and 500 μm (0.78 m 2 /s) air discharge at 8 mA under the velocity of 156 m/s. As a result, an increase of 46.7% in E/N strength of the discharge of 200 μm hole was obtained compare to that of 500 μm

  10. Lidar Observation of Aerosol and Temperature Stratification over Urban Area During the Formation of a Stable Atmospheric PBL

    Science.gov (United States)

    Kolev, I.; Parvanov, O.; Kaprielov, B.; Mitev, V.; Simeonov, V.; Grigorov, I.

    1992-01-01

    In recent years, the processes in the atmospheric planetary boundary layer (PBL) over urban areas were intensely investigated, due to ecological problems related to the air, soil, and water pollution. New pollution sources in new residential districts, when in contradiction to the microclimate and topography requirements of that region, create a number of considerable hazards and problems. The present study is a continuation of our preceding investigations and aims at revealing the aerosol structure and stratification during the transition after sunset as measured by two lidars. Such observation of the nocturnal, stable PBL formation over an urban area in Bulgaria has not been reported before. The lidars' high time and spatial resolutions allow the changes of the internal structure of the PBL's part located above the surface layer to be observed.

  11. Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads.

    Science.gov (United States)

    Vázquez-Guerrero, Jairo; Moras, Gerard; Baeza, Jennifer; Rodríguez-Jiménez, Sergio

    2016-01-01

    The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries.

  12. Stable condition of dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid ( DMDTAV) in landfill leachate

    Science.gov (United States)

    Kwon, E.; Yoon, H. O.; Kim, J. A.; Lee, H.; Jung, S.; Kim, Y. T.

    2015-12-01

    When waste containing arsenic (As) are disposed of landfill, such facilities (i.e., landfill) can play an important role in disseminating As to the surrounding environment. These disposal of waste containing As might cause a serious environmental pollution due to potentially As remobilization in landfill. Especially, As species containing sulfur such as DMDTAv and DMMTAv found occasionally high concentration in landfill leachate. These As species (i.e., DMDTAv and DMMTAv) had the higher toxicity to human cells compared to other pentavalent As species. However, there was no chemical standard material of these As species (i.e., DMDTAv and DMMTAv) commercially. In this study, we synthesized DMDTAv and DMMTAv by simulating reaction with the sufficient sulfur condition from DMAv. DMMTAv was quite changeable to DMDTAv due to its short life time from our preliminary study. Thus, it is important to find the stable condition of synthesis process for DMDTAv and DMMTAv under suitable environmental condition. This study can be very significant in quantitative analysis area to detect the various As species in environmental media such as landfill.

  13. A Carbon Source Apportionment Shift in Mexico City Atmospheric Particles During 2003-2004 as Determined with Stable Carbon Isotopes

    Science.gov (United States)

    Lopez-Veneroni, D. G.; Vega, E.

    2013-05-01

    The stable carbon isotope composition of atmospheric particles (PM2.5) was measured at La Merced (MER), a commercial site in the eastern sector, and at Xalostoc (XAL) an industrial site in the NE sector of Mexico City, during three sampling periods in autumn 2003, and spring and autumn 2004. At each site and sampling campaign particle samples were collected daily with minivol samplers during two week periods. Ancillary data included organic and elemental carbon, trace elements and ionic species. This data base was complement with air quality data from the RAMA (Automatic Atmospheric Monitoring Network). In general, particle concentrations, ionic species and some air quality species showed higher concentrations in autumn and lowest values in spring. Moreover, the concentrations of these chemical species were highest at XAL compared to MER. The stable carbon isotope composition of PM2.5 during autumn 2003 and spring 2004 had and average value of -26.04 (± 1.54) ‰ vs. PDB. Differences in the isotopic composition between the two sites were non significant. The average δ13C during these seasons were 1 ‰ lighter relative to data collected previously at these sites during 2000 and 2001, and is consistent with a predominant source of hydrocarbon combustion. In autumn 2004, however, average δ13C at XAL and MER increased to -22.8 (± 0.9) and -20.6 (± 3.1) ‰, respectively. Organic carbon concentrations during this period increased concomitantly at these sites. The shift in the isotopic composition in ambient particles suggests a predominance of soil-derived carbon during this period. The possible causes and implications of this are discussed.

  14. Response in atmospheric circulation and sources of Greenland precipitation to glacial boundary conditions

    DEFF Research Database (Denmark)

    Langen, Peter Lang; Vinther, Bo Møllesøe

    2009-01-01

    The response in northern hemisphere atmospheric circulation and the resulting changes in moisture sources for Greenland precipitation to glacial boundary conditions are studied in NCAR's CCM3 atmospheric general circulation model fitted with a moisture tracking functionality. We employ both...... seasonality, condensation temperatures and source temperatures are assessed. Udgivelsesdato: June 2009...

  15. Measurement of forest condition and response along the Pennsylvania atmospheric deposition gradent

    Science.gov (United States)

    D.D. David; J.M. Skelly; J.A. Lynch; L.H. McCormick; B.L. Nash; M. Simini; E.A. Cameron; J.R. McClenahen; R.P. Long

    1991-01-01

    Research in the oak-hickory forest of northcentral Pennsylvania is being conducted to detect anomalies in forest condition that may be due to atmospheric deposition, with the intent that such anomalies will be further studied to determine the role, if any, of atmospheric deposition. This paper presents the status of research along a 160-km gradient of sulfate/nitrate...

  16. Atmospheric corrosion of copper under wet/dry cyclic conditions

    Energy Technology Data Exchange (ETDEWEB)

    EL-Mahdy, Gamal A. [Department of Metallurgical System Engineering, Yonsei University, 134-Shinchon-dong, Seodaemun-Ku, Seoul, 120-749 (Korea, Republic of)

    2005-06-01

    The polarization resistance of copper subjected to NaCl and an ammonium sulfate solution under wet/dry cycling conditions was monitored using an EIS impedance technique. The copper samples were exposed to 1 h of immersion using different solutions of pH, temperature and surface orientation and 7 h of drying. The copper plates corroded more substantially on the skyward side than those for a ground ward side. The degree of protection copper oxide provides decrease in an acidic medium (pH 4) more than in a neutral medium (pH 7). The corrosion rate of copper increases rapidly during the initial stages of exposure then decreases slowly and eventually attains the steady state during the last stages of exposure. The corrosion products were analyzed using X-ray diffraction. The corrosion mechanism for copper studied under wet/dry cyclic conditions was found to proceed under the dissolution-precipitation mechanism.

  17. Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads.

    Directory of Open Access Journals (Sweden)

    Jairo Vázquez-Guerrero

    Full Text Available The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010 and peak force output differed between all loads for each condition (P < 0.045. Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001. There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries.

  18. Surface layer conditions of the atmosphere over western Bay of Bengal during Monex

    Digital Repository Service at National Institute of Oceanography (India)

    Anto, A.F.; Rao, L.V.G.; Somayajulu, Y.K.

    Based on surface meteorological data and wave data collected from 2 stations in the western Bay of Bengal in July 1979, surface layer (SL) conditions of the atmosphere for different situations of surface circulations and the associated sea surface...

  19. Model test study of evaporation mechanism of sand under constant atmospheric condition

    OpenAIRE

    CUI, Yu Jun; DING, Wenqi; SONG, Weikang

    2014-01-01

    The evaporation mechanism of Fontainebleau sand using a large-scale model chamber is studied. First, the evaporation test on a layer of water above sand surface is performed under various atmospheric conditions, validating the performance of the chamber and the calculation method of actual evaporation rate by comparing the calculated and measured cumulative evaporations. Second,the evaporation test on sand without water layer is conducted under constant atmospheric condition. Both the evoluti...

  20. Response Analysis of a Spar-Type Floating Offshore Wind Turbine Under Atmospheric Icing Conditions

    DEFF Research Database (Denmark)

    Etemaddar, Mahmoud; Hansen, Martin Otto Laver; Moan, Torgeir

    2014-01-01

    One of the challenges for the development of wind energy in offshore cold-climate regions is atmospheric icing. This paper examines the effects of atmospheric icing on power production, overall performance, and extreme loads of a 5-MW spar-type floating offshore wind turbine during power producti......, as are the effects of atmospheric icing on land-based and offshore wind turbines.......One of the challenges for the development of wind energy in offshore cold-climate regions is atmospheric icing. This paper examines the effects of atmospheric icing on power production, overall performance, and extreme loads of a 5-MW spar-type floating offshore wind turbine during power production......, normal and emergency rotor shutdown, extreme gusts, and survival conditions. Atmospheric icing is simulated by using the ice accretion simulation code LEWICE. A CFD method is used to estimate the blade aerodynamic degradation due to icing. The effects of icing on one, two, or three blades are compared...

  1. Development of a setup to enable stable and accurate flow conditions for membrane biofouling studies

    KAUST Repository

    Bucs, Szilard

    2015-07-10

    Systematic laboratory studies on membrane biofouling require experimental conditions that are well defined and representative for practice. Hydrodynamics and flow rate variations affect biofilm formation, morphology, and detachment and impacts on membrane performance parameters such as feed channel pressure drop. There is a suite of available monitors to study biofouling, but systems to operate monitors have not been well designed to achieve an accurate, constant water flow required for a reliable determination of biomass accumulation and feed channel pressure drop increase. Studies were done with membrane fouling simulators operated in parallel with manual and automated flow control, with and without dosage of a biodegradable substrate to the feedwater to enhance biofouling rate. High flow rate variations were observed for the manual water flow system (up to ≈9%) compared to the automatic flow control system (<1%). The flow rate variation in the manual system was strongly increased by biofilm accumulation, while the automatic system maintained an accurate and constant water flow in the monitor. The flow rate influences the biofilm accumulation and the impact of accumulated biofilm on membrane performance. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. Stable and accurate feedwater flow rates are essential for biofouling studies in well-defined conditions in membrane systems. © 2015 Balaban Desalination Publications. All rights reserved.

  2. Attributing Climate Conditions for Stable Malaria Transmission to Human Activity in sub-Saharan Africa

    Science.gov (United States)

    Sheldrake, L.; Mitchell, D.; Allen, M. R.

    2015-12-01

    Temperature and precipitation limit areas of stable malaria transmission, but the effects of climate change on the disease remain controversial. Previously, studies have not separated the influence of anthropogenic climate change and natural variability, despite being an essential step in the attribution of climate change impacts. Ensembles of 2900 simulations of regional climate in sub-Saharan Africa for the year 2013, one representing realistic conditions and the other how climate might have been in the absence of human influence, were used to force a P.falciparium climate suitability model developed by the Mapping Malaria Risk in Africa project. Strongest signals were detected in areas of unstable transmission, indicating their heightened sensitivity to climatic factors. Evidently, impacts of human-induced climate change were unevenly distributed: the probability of conditions being suitable for stable malaria transmission were substantially reduced (increased) in the Sahel (Greater Horn of Africa (GHOA), particularly in the Ethiopian and Kenyan highlands). The length of the transmission season was correspondingly shortened in the Sahel and extended in the GHOA, by 1 to 2 months, including in Kericho (Kenya), where the role of climate change in driving recent malaria occurrence is hotly contested. Human-induced warming was primarily responsible for positive anomalies in the GHOA, while reduced rainfall caused negative anomalies in the Sahel. The latter was associated with anthropogenic impacts on the West African Monsoon, but uncertainty in the RCM's ability to reproduce precipitation trends in the region weakens confidence in the result. That said, outputs correspond well with broad-scale changes in observed endemicity, implying a potentially important contribution of anthropogenic climate change to the malaria burden during the past century. Results support the health-framing of climate risk and help indicate hotspots of climate vulnerability, providing

  3. Atmospheric-radiation boundary conditions for high-frequency waves in time-distance helioseismology

    Science.gov (United States)

    Fournier, D.; Leguèbe, M.; Hanson, C. S.; Gizon, L.; Barucq, H.; Chabassier, J.; Duruflé, M.

    2017-12-01

    The temporal covariance between seismic waves measured at two locations on the solar surface is the fundamental observable in time-distance helioseismology. Above the acoustic cut-off frequency ( 5.3 mHz), waves are not trapped in the solar interior and the covariance function can be used to probe the upper atmosphere. We wish to implement appropriate radiative boundary conditions for computing the propagation of high-frequency waves in the solar atmosphere. We consider recently developed and published radiative boundary conditions for atmospheres in which sound-speed is constant and density decreases exponentially with radius. We compute the cross-covariance function using a finite element method in spherical geometry and in the frequency domain. The ratio between first- and second-skip amplitudes in the time-distance diagram is used as a diagnostic to compare boundary conditions and to compare with observations. We find that a boundary condition applied 500 km above the photosphere and derived under the approximation of small angles of incidence accurately reproduces the "infinite atmosphere" solution for high-frequency waves. When the radiative boundary condition is applied 2 Mm above the photosphere, we find that the choice of atmospheric model affects the time-distance diagram. In particular, the time-distance diagram exhibits double-ridge structure when using a Vernazza Avrett Loeser atmospheric model.

  4. Soil moisture under contrasted atmospheric conditions in Eastern Spain

    Science.gov (United States)

    Azorin-Molina, César; Cerdà, Artemi; Vicente-Serrano, Sergio M.

    2014-05-01

    Soil moisture plays a key role on the recently abandoned agriculture land where determine the recovery and the erosion rates (Cerdà, 1995), on the soil water repellency degree (Bodí et al., 2011) and on the hydrological cycle (Cerdà, 1999), the plant development (García Fayos et al., 2000) and the seasonality of the geomorphological processes (Cerdà, 2002). Moreover, Soil moisture is a key factor on the semiarid land (Ziadat and Taimeh, 2013), on the productivity of the land (Qadir et al., 2013) and soils treated with amendments (Johnston et al., 2013) and on soil reclamation on drained saline-sodic soils (Ghafoor et al., 2012). In previous study (Azorin-Molina et al., 2013) we investigated the intraannual evolution of soil moisture in soils under different land managements in the Valencia region, Eastern Spain, and concluded that soil moisture recharges are much controlled by few heavy precipitation events; 23 recharge episodes during 2012. Most of the soil moisture recharge events occurred during the autumn season under Back-Door cold front situations. Additionally, sea breeze front episodes brought isolated precipitation and moisture to mountainous areas within summer (Azorin-Molina et al., 2009). We also evidenced that the intraanual evolution of soil moisture changes are positively and significatively correlated (at pGeoderma, 160, 599-607. 10.1016/j.geoderma.2010.11.009 Cerdà, A. 1995. Soil moisture regime under simulated rainfall in a three years abandoned field in Southeast Spain. Physics and Chemistry of The Earth, 20 (3-4), 271-279. Cerdà, A. 1999. Seasonal and spatial variations in infiltration rates in badland surfaces under Mediterranean climatic conditions. Water Resources Research, 35 (1) 319-328. Cerdà, A. 2002. The effect of season and parent material on water erosion on highly eroded soils in eastern Spain. Journal of Arid Environments, 52, 319-337. García-Fayos, P. García-Ventoso, B. Cerdà, A. 2000. Limitations to Plant establishment

  5. Detection of adenovirus and respiratory syncytial virus in patients with chronic obstructive pulmonary disease: Exacerbation versus stable condition.

    Science.gov (United States)

    Kokturk, Nurdan; Bozdayi, Gulendam; Yilmaz, Senay; Doğan, Bora; Gulbahar, Ozlem; Rota, Seyyal; Tatlicioglu, Turkan

    2015-08-01

    Latent infection with adenovirus and respiratory syncytial virus (RSV) is associated with chronic obstructive pulmonary disease (COPD). The role of respiratory viral infections are emerging in COPD exacerbations. The present study aimed to investigate the prevalence of adenovirus and RSV serotypes A and B in individuals with acute exacerbations of COPD (COPD-AE) and stable COPD. Twenty seven patients with COPD-AE were evaluated using a prospective longitudinal study design. Induced sputum, sera and nasal smears were sampled from patients experiencing COPD-AE and those in a stable condition. Adenoplex® multiplex polymerase chain reaction (PCR) kits and Invitek RTP® DNA/RNA Virus Mini kits were used for PCR assays of adenovirus and RSV, respectively. Eighteen patients who experienced a COPD-AE were also evaluated while in a stable condition. The results showed that three sputum samples were positive for adenovirus in patients experiencing an exacerbation, while one was positive among the patients in a stable condition. RSV serotype A was detected in 17/27 (63%) patients with COPD-AE and 10/18 (55.6%) patients in a stable condition. RSV serotype B was not detected. Patients with COPD-AE, who were positive for RSV serotype A exhibited higher serum fibrinogen levels than those who were negative (438.60 ± 126.08 mg/dl compared with 287.60 ± 85.91 mg/dl; P=0.004). Eight/ten patients who were positive for RSV serotype A while in a stable condition, were also positive during COPD-AE. The results of the present study suggested that RSV infection may be prevalent in patients with COPD-AE and in those in a stable condition. Therefore, chronic RSV infection may occur in COPD. The detection and prevention of RSV may be useful in the management of COPD.

  6. Variations in stable hydrogen and oxygen isotopes in atmospheric water vapor in the marine boundary layer across a wide latitude range.

    Science.gov (United States)

    Liu, Jingfeng; Xiao, Cunde; Ding, Minghu; Ren, Jiawen

    2014-11-01

    The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of δ(18)O and δ(2)H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature (Tair), with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial-temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world. Copyright © 2014. Published by Elsevier B.V.

  7. Catalysts and conditions for the highly efficient, selective and stable heterogeneous oligomerisation of ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Heveling, J.; Nicolaides, C.P.; Scurrell [Catalysis Programme, Division of Energy Technology, CSIR, PO Box 395, Pretoria 0001 (South Africa)

    1998-10-11

    The oligomerisation of ethylene into products in the C{sub 4}-C{sub 20} range over heterogeneous nickel catalysts in a fixed-bed reactor at low temperature and high pressure (LT-HP) is reported. The catalysts were obtained by Ni(II) exchange or impregnation of two differently prepared amorphous and mesoporous silica-alumina supports. A plot of catalytic activity versus temperature at 35bar and MHSV=2 produces a volcano-type curve with a maximum around 120C. Experiments performed under the LT-HP reaction conditions, viz. 120C, 35bar and MHSV=2, give an ethylene conversion level of 99% and a 97% selectivity to products with an even number of carbon atoms. The product spectrum (C{sub n} distribution) was dependent on the type of catalyst used, with the percentage of the C{sub 10+} coligomers lying in the range 23-41% by mass. Of practical significance, these types of catalyst were found to be extremely stable in use showing no detectable drop in conversion after 108 days on stream under the LT-HP employed

  8. Contribution of Atmospheric Diffusion Conditions to the Recent Improvement in Air Quality in China.

    Science.gov (United States)

    Wang, Xiaoyan; Wang, Kaicun; Su, Liangyuan

    2016-11-02

    This study analyzed hourly mass concentration observations of PM 2.5 (particulate matters with diameter less than 2.5 μm) at 512 stations in China from December 2013 to May 2015. We found that the mean concentrations of PM 2.5 during the winter and spring of 2015 Dec. 2014 to Feb. 2015 and Mar. 2015 to May 2015) decreased by 20% and 14% compared to the previous year, respectively. Hazardous air-quality days decreased by 11% in 2015 winter, with more frequent good to unhealthy days; and the good and moderate air-quality days in 2015 spring increased by 9% corresponding to the less occurrence of unhealthy conditions. We compared the atmospheric diffusion conditions during these two years and quantified its contribution to the improvement of air quality during the first half of 2015 over China. Our results show that during the 2015 winter and spring, 70% and 57% of the 512 stations experienced more favorable atmospheric diffusion conditions compared to those of previous year. Over central and northern China, approximately 40% of the total decrease in PM 2.5 during the 2015 winter can be attributed to the favorable atmospheric diffusion conditions. The atmospheric diffusion conditions during the spring of 2015 were not as favorable as in winter; and the average contributions of the atmospheric conditions were slight.

  9. Study on the flow reduction of forced flow superconducting magnet and its stable operation condition

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Makoto [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2001-03-01

    The forced flow superconducting coil especially made from a Cable-in-Conduit Conductor (CICC) is applied for large-scale devices such as fusion magnets and superconducting magnet energy storage (SMES) because it has high mechanical and electrical performance potential. The flow reduction phenomena caused by AC loss generation due to the pulsed operation was found based on the experimental results of three forced flow superconducting coils. And relation between the AC loss generation and flow reduction was defined from viewpoint of the engineering design and operation of the coils. Also the mechanism of flow reduction was investigated and stable operation condition under the flow reduction was clarified for forced flow superconducting coils. First, experiments of three different large-scale superconducting coils were carried out and experimental database of the flow reduction by AC loss generation was established. It was found experimentally that the flow reduction depends on the AC loss generation (W/m{sup 3}) in all of coils. It means the stable operation condition is defined not only the electro magnetism of superconducting coil but also flow condition. Mechanism of the flow reduction was investigated based on the experimental database. Hydraulics was applied to supercritical helium as a coolant. Also performances of the cryogenic pump by which coolant are supplied to the coil and friction of the superconductor as cooling path is considered for hydraulic estimation. The flow reduction of the coil is clarified and predictable by the equations of continuity, momentum and energy balance. Also total mass flow rate of coolant was discussed. The estimation method in the design phase was developed for total mass flow rate which are required under the flow reduction by AC losses. The friction of the superconductor and performance of cryogenic pump should be required for precise prediction of flow reduction. These values were obtained by the experiment data of coil and

  10. Ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bang Selsted, M.

    2010-07-15

    Global change is a reality. Atmospheric CO{sub 2} levels are rising as well as mean global temperature and precipitation patterns are changing. These three environmental factors have separately and in combination effect on ecosystem processes. Terrestrial ecosystems hold large amounts of carbon, why understanding plant and soil responses to such changes are necessary, as ecosystems potentially can ameliorate or accelerate global change. To predict the feedback of ecosystems to the atmospheric CO{sub 2} concentrations experiments imitating global change effects are therefore an important tool. This work on ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions, shows that extended summer drought in combination with elevated temperature will ensure permanent dryer soil conditions, which decreases carbon turnover, while elevated atmospheric CO{sub 2} concentrations will increase carbon turnover. In the full future climate scenario, carbon turnover is over all expected to increase and the heathland to become a source of atmospheric CO{sub 2}. The methodology of static chamber CO{sub 2} flux measurements and applying the technology in a FACE (free air CO{sub 2} enrichment) facility is a challenge. Fluxes of CO{sub 2} from soil to atmosphere depend on a physical equilibrium between those two medias, why it is important to keep the CO{sub 2} gradient between soil and atmosphere unchanged during measurement. Uptake to plants via photosynthesis depends on a physiological process, which depends strongly on the atmospheric CO{sub 2} concentration. Photosynthesis and respiration run in parallel during measurements of net ecosystem exchange, and these measurements should therefore be performed with care to both the atmospheric CO{sub 2} concentration and the CO{sub 2} soil-atmosphere gradient. (author)

  11. Ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions

    DEFF Research Database (Denmark)

    Selsted, Merete Bang

    on ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions, shows that extended summer drought in combination with elevated temperature will ensure permanent dryer soil conditions, which decreases carbon turnover, while elevated atmospheric CO2 concentrations will increase......Global change is a reality. Atmospheric CO2 levels are rising as well as mean global temperature and precipitation patterns are changing. These three environmental factors have separately and in combination effect on ecosystem processes. Terrestrial ecosystems hold large amounts of carbon, why...... understanding plant and soil responses to such changes are necessary, as ecosystems potentially can ameliorate or accelerate global change. To predict the feedback of ecosystems to the atmospheric CO2 concentrations experiments imitating global change effects are therefore an important tool. This work...

  12. Ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions

    DEFF Research Database (Denmark)

    Selsted, Merete Bang

    Global change is a reality. Atmospheric CO2 levels are rising as well as mean global temperature and precipitation patterns are changing. These three environmental factors have separately and in combination effect on ecosystem processes. Terrestrial ecosystems hold large amounts of carbon, why...... understanding plant and soil responses to such changes are necessary, as ecosystems potentially can ameliorate or accelerate global change. To predict the feedback of ecosystems to the atmospheric CO2 concentrations experiments imitating global change effects are therefore an important tool. This work...... on ecosystem-atmosphere exchange of carbon in a heathland under future climatic conditions, shows that extended summer drought in combination with elevated temperature will ensure permanent dryer soil conditions, which decreases carbon turnover, while elevated atmospheric CO2 concentrations will increase...

  13. Influence factor analysis of atmospheric electric field monitoring near ground under different weather conditions

    International Nuclear Information System (INIS)

    Wan, Haojiang; Wei, Guanghui; Cui, Yaozhong; Chen, Yazhou

    2013-01-01

    Monitoring of atmospheric electric field near ground plays a critical role in atmospheric environment detecting and lightning warning. Different environmental conditions (e.g. buildings, plants, weather, etc.) have different influences on the data's coherence in an atmospheric electric field detection network. In order to study the main influence factors of atmospheric electric field monitoring under different weather conditions, with the combination of theoretical analysis and experiments, the electric field monitoring data on the ground and on the top of a building are compared in fair weather and thunderstorm weather respectively in this paper. The results show that: In fair weather, the field distortion due to the buildings is the main influence factor on the electric field monitoring. In thunderstorm weather, the corona ions produced from the ground, besides the field distortion due to the buildings, can also influence the electric field monitoring results.

  14. Tracing the Sources of Atmospheric Phosphorus Deposition to a Tropical Rain Forest in Panama Using Stable Oxygen Isotopes.

    Science.gov (United States)

    Gross, A; Turner, B L; Goren, T; Berry, A; Angert, A

    2016-02-02

    Atmospheric dust deposition can be a significant source of phosphorus (P) in some tropical forests, so information on the origins and solubility of atmospheric P is needed to understand and predict patterns of forest productivity under future climate scenarios. We characterized atmospheric dust P across a seasonal cycle in a tropical lowland rain forest on Barro Colorado Nature Monument (BCNM), Republic of Panama. We traced P sources by combining remote sensing imagery with the first measurements of stable oxygen isotopes in soluble inorganic phosphate (δ(18)OP) in dust. In addition, we measured soluble inorganic and organic P concentrations in fine (1 μm) aerosol fractions and used this data to estimate the contribution of P inputs from dust deposition to the forest P budget. Aerosol dry mass was greater in the dry season (December to April, 5.6-15.7 μg m(-3)) than the wet season (May to November, 3.1-7.1 μg m(-3)). In contrast, soluble P concentrations in the aerosols were lower in the dry season (980-1880 μg P g(-1)) than the wet season (1170-3380 μg P g(-1)). The δ(18)OP of dry-season aerosols resembled that of nearby forest soils (∼19.5‰), suggesting a local origin. In the wet season, when the Trans-Atlantic Saharan dust belt moves north close to Panama, the δ(18)OP of aerosols was considerably lower (∼15.5‰), suggesting a significant contribution of long-distance dust P transport. Using satellite retrieved aerosol optical depth (AOD) and the P concentrations in aerosols we sampled in periods when Saharan dust was evident we estimate that the monthly P input from long distance dust transport during the period with highest Saharan dust deposition is 88 ± 31 g P ha(-1) month(-1), equivalent to between 10 and 29% of the P in monthly litter fall in nearby forests. These findings have important implications for our understanding of modern nutrient budgets and the productivity of tropical forests in the region under future climate scenarios.

  15. Subsurface Conditions Controlling Uranium Incorporation in Iron Oxides: A Redox Stable Sink

    Energy Technology Data Exchange (ETDEWEB)

    Fendorf, Scott [Stanford Univ., CA (United States)

    2016-04-05

    Toxic metals and radionuclides throughout the U.S. Department of Energy Complex pose a serious threat to ecosystems and to human health. Of particular concern is the redox-sensitive radionuclide uranium, which is classified as a priority pollutant in soils and groundwaters at most DOE sites owing to its large inventory, its health risks, and its mobility with respect to primary waste sources. The goal of this research was to contribute to the long-term mission of the Subsurface Biogeochemistry Program by determining reactions of uranium with iron (hydr)oxides that lead to long-term stabilization of this pervasive contaminant. The research objectives of this project were thus to (1) identify the (bio)geochemical conditions, including those of the solid-phase, promoting uranium incorporation in Fe (hydr)oxides, (2) determine the magnitude of uranium incorporation under a variety of relevant subsurface conditions in order to quantify the importance of this pathway when in competition with reduction or adsorption; (3) identify the mechanism(s) of U(VI/V) incorporation in Fe (hydr)oxides; and (4) determine the stability of these phases under different biogeochemical (inclusive of redox) conditions. Our research demonstrates that redox transformations are capable of achieving U incorporation into goethite at ambient temperatures, and that this transformation occurs within days at U and Fe(II) concentrations that are common in subsurface geochemical environments with natural ferrihydrites—inclusive of those with natural impurities. Increasing Fe(II) or U concentration, or initial pH, made U(VI) reduction to U(IV) a more competitive sequestration pathway in this system, presumably by increasing the relative rate of U reduction. Uranium concentrations commonly found in contaminated subsurface environments are often on the order of 1-10 μM, and groundwater Fe(II) concentrations can reach exceed 1 mM in reduced zones of the subsurface. The redox-driven U(V) incorporation

  16. Description of Atmospheric Conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, P.; /Lisbon, IST; Aglietta, M.; /Turin U. /INFN, Turin; Ahlers, M.; /Wisconsin U., Madison; Ahn, E.J.; /Fermilab; Albuquerque, I.F.M.; /Sao Paulo U.; Allard, D.; /APC, Paris; Allekotte, I.; /Buenos Aires, CONICET; Allen, J.; /New York U.; Allison, P.; /Ohio State U.; Almela, A.; /Natl. Tech. U., San Nicolas /Buenos Aires, CONICET; Alvarez Castillo, J.; /Mexico U., ICN /Santiago de Compostela U.

    2012-01-01

    Atmospheric conditions at the site of a cosmic ray observatory must be known for reconstructing observed extensive air showers. The Global Data Assimilation System (GDAS) is a global atmospheric model predicated on meteorological measurements and numerical weather predictions. GDAS provides altitude-dependent profiles of the main state variables of the atmosphere like temperature, pressure, and humidity. The original data and their application to the air shower reconstruction of the Pierre Auger Observatory are described. By comparisons with radiosonde and weather station measurements obtained on-site in Malargue and averaged monthly models, the utility of the GDAS data is shown.

  17. CCN activity of secondary aerosols from terpene ozonolysis under atmospheric relevant conditions

    Science.gov (United States)

    Yuan, Cheng; Ma, Yan; Diao, Yiwei; Yao, Lei; Zhou, Yaoyao; Wang, Xing; Zheng, Jun

    2017-04-01

    Gas-phase ozonolysis of terpenes is an important source of atmospheric secondary organic aerosol. The contribution of terpene-derived aerosols to the atmospheric cloud condensation nucleus (CCN) burden under atmospheric conditions, however, remains highly uncertain. The results obtained in previous studies under simple laboratory conditions may not be applicable to atmospheric relevant conditions. Here we present that CCN activities of aerosols from terpene ozonolysis can be significantly affected by atmospheric relevant species that can act as stabilized Criegee intermediate (SCI) or OH scavengers. Ozonolysis reactions of α-pinene, limonene, α-cedrene, and α-humulene were conducted in a 4.5 m3 collapsible fluoropolymer chamber at near-atmospheric concentrations in the presence of different OH scavengers (cyclohexane, 2-butanol, or CO) and SCI scavengers (CH3COOH, H2O, or SO2). The number size distribution and CCN activity of aerosol particles formed during ozonolysis were simultaneously determined. Additionally, particulate products were chemically analyzed by using a Filter Inlet for Gases and AEROsols High-Resolution Time-of-Flight Chemical-Ionization Mass Spectrometer. Results showed that aerosol CCN activity following monoterpene ozonolysis was more sensitive to the choice of OH scavengers, while that from sesquiterpene ozonolysis was significantly affected by SCI scavengers. Combined with chemical analysis results, it was concluded that the unimolecular decomposition of CIs giving hygroscopic organic products can be largely suppressed by bimolecular reactions during sesquiterpene ozonolysis but was not significantly impacted in monoterpene ozonolysis. Our study underscores the key role of CIs in the CCN activity of terpene ozonolysis-derived aerosols. The effects of atmospheric relevant species (e.g., SO2, H2O, and CO) need to be considered when assessing the contribution of biogenic terpenes to the atmospheric CCN burden under ambient conditions.

  18. Variability in the combustion-derived fraction of urban humidity in Salt Lake City winter estimated from stable water vapor isotopes and its relationship to atmospheric stability and inversion structure

    Science.gov (United States)

    Fiorella, R.; Bares, R.; Lin, J. C.; Strong, C.; Bowen, G. J.

    2017-12-01

    Water released from the combustion of fossil fuels, while a negligible part of the global hydrological cycle, may be a significant contributor to urban humidity as fossil fuel emissions are strongly concentrated in space and time. The fraction of urban humidity comprised of combustion-derived vapor (CDV) cannot be observed through humidity measurements alone. However, the distinct stable isotopic composition of CDV, which arises from the reaction of 18O-enriched atmospheric O2 with 2H-depleted organic molecules, represents a promising method to apportion observed humidity between CDV and advected vapor. We apply stable water vapor isotopes to investigate variability in CDV amount and its relationship to atmospheric conditions in Salt Lake City, Utah. The Salt Lake Valley experiences several periods of atmospheric stratification during winter known as cold air pools, during which concentrations of CDV and pollutants can be markedly elevated due to reduced atmospheric mixing. Therefore, the SLV during winter is an ideal place to investigate variability in CDV fraction across a spectrum of boundary layer conditions, ranging from well-mixed to very stable. We present water vapor isotope data from four winters (2013-2017) from the top of a 30 m building on the University of Utah (U of U) Campus. Additionally, we present water vapor isotope data from the summit of Hidden Peak from the 2016-2017 winter, 25 km SE and 2000 m above the U of U site. The Hidden Peak site is consistently above the cold air pool emplaced in the SLV during stable events. We find the expression of the CDV signal in the valley is related to the atmospheric structure of the cold air pools in the SLV, and that the fraction of CDV inferred in the valley is likely related to the mixing height within the cold air pool. Furthermore, we find that patterns between the Hidden Peak and U of U sites during inversion events may record the large-scale atmospheric dynamics promoting emplacement of the cold air

  19. 29 CFR 1918.94 - Ventilation and atmospheric conditions (See also § 1918.2, definitions of Hazardous cargo...

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ventilation and atmospheric conditions (See also § 1918.2.... § 1918.94 Ventilation and atmospheric conditions (See also § 1918.2, definitions of Hazardous cargo... that the compartment's atmosphere is within allowable limits. (See paragraph (b)(3) of this section...

  20. Relative Influence of Initial Surface and Atmospheric Conditions on Seasonal Water and Energy Balances

    Science.gov (United States)

    Oglesby, Robert J.; Marshall, Susan; Roads, John O.; Robertson, Franklin R.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    We constructed and analyzed wet and dry soil moisture composites for the mid-latitude GCIP region of the central US using long climate model simulations made with the NCAR CCM3 and reanalysis products from NCEP. Using the diagnostic composites as a guide, we have completed a series of predictability experiments in which we imposed soil water initial conditions in CCM3 for the GCIP region for June 1 from anomalously wet and dry years, with atmospheric initial conditions taken from June 1 of a year with 'near-normal' soil water, and initial soil water from the near-normal year and atmospheric initial conditions from the wet and dry years. Preliminary results indicate that the initial state of the atmosphere is more important than the initial state of soil water determining the subsequent late spring and summer evolution of sod water over the GCIP region. Surprisingly, neither the composites or the predictability experiments yielded a strong influence of soil moisture on the atmosphere. To explore this further, we have made runs with extreme dry soil moisture initial anomalies imposed over the GCIP region (the soil close to being completely dry). These runs did yield a very strong effect on the atmosphere that persisted for at least three months. We conclude that the magnitude of the initial soil moisture anomaly is crucial, at least in CCM3, and are currently investigating whether a threshold exists, below which little impact is seen. In a complementary study, we compared the impact of the initial condition of snow cover versus the initial atmospheric state over the western US (corresponding to the westward extension of the GAPP program follow-on to GCIP). In this case, the initial prescription of snow cover is far more important than the initial atmospheric state in determining the subsequent evolution of snow cover. We are currently working to understand the very different soil water and snow cover results.

  1. STEEL CORROSION AT 600°C IN SINGLE AND DUAL CONDITION IN OXYFUEL ATMOSPHERE

    Directory of Open Access Journals (Sweden)

    Daniel Massari de Souza Coelho

    2014-10-01

    Full Text Available Coal-fired power plants using the Oxyfuel process are being developed to produce electricity with zero CO2 emission. Steels used in this and other processes are often exposed to different atmospheres in each side of the material, especially in heat exchangers and solid oxide fuel cells. Some studies have shown that steels exposed to different hydrogen partial pressures in each side have a different corrosion behavior from steels exposed to a single atmosphere condition. In this investigation, two experimental steels were studied at 600°C and 1 atm in dual atmospheres containing water vapor in one side and flue gas in the other and they were compared to steels oxidized in single atmospheres. The gas composition used is similar to the ones found in Oxyfuel coal power plants, where there is a great concentration of CO2, and also H2O and SO2. Analyses were made using SEM and TEM.

  2. Serum adiponectin level in obese and non-obese COPD patients during acute exacerbation and stable conditions

    Directory of Open Access Journals (Sweden)

    Magdy Mohammad Omar

    2014-04-01

    Conclusion: Serum adiponectin was significantly higher in obese and nonobese COPD than controls, the rising is more during exacerbation than stable condition and more in non obese than obese COPD and non significant correlation between changes in adiponectin and ventilatory functions was found.

  3. Assessing the Impacts of Atmospheric Conditions under Climate Change on Air Quality Profile over Hong Kong

    Science.gov (United States)

    Hei Tong, Cheuk

    2017-04-01

    Small particulates can cause long term impairment to human health as they can penetrate deep and deposit on the wall of the respiratory system. Under the projected climate change as reported by literature, atmospheric stability, which has strong effects on vertical mixing of air pollutants and thus air quality Hong Kong, is also varying from near to far future. In addition to domestic emission, Hong Kong receives also significant concentration of cross-boundary particulates that their natures and movements are correlated with atmospheric condition. This study aims to study the relation of atmospheric conditions with air quality over Hong Kong. Past meteorological data is based on Modern Era Retrospective Analysis for Research and Applications (MERRA) reanalysis data. Radiosonde data provided from HKO are also adopted in testing and validating the data. Future meteorological data is simulated by the Weather Research and Forecasting Model (WRF), which dynamically downscaled the past and future climate under the A1B scenario simulated by ECHAM5/MPIOM. Air quality data is collected on one hand from the ground station data provided by Environment Protection Department, with selected stations revealing local emission and trans-boundary emission respectively. On the other hand, an Atmospheric Light Detection and Ranging (LiDAR), which operates using the radar principle to detect Rayleigh and Mie scattering from atmospheric gas and aerosols, has also been adopted to measure vertical aerosol profile, which has been observed tightly related to the high level meteorology. Data from scattered signals are collected, averaged or some episode selected for characteristic comparison with the atmospheric stability indices and other meteorological factors. The relation between atmospheric conditions and air quality is observed by statistical analysis, and statistical models are built based on the stability indices to project the changes in sulphur dioxide, ozone and particulate

  4. Stable Isotope Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

  5. Source apportionment of atmospheric ammonia before, during, and after the 2014 APEC summit in Beijing using stable nitrogen isotope signatures

    Directory of Open Access Journals (Sweden)

    Y. Chang

    2016-09-01

    Full Text Available Stable nitrogen isotope composition (δ15N offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3, a vital precursor of PM2.5 (particulate matters with aerodynamic diameter equal or less than 2.5 µm inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle to over 6000 (human excreta µg m−3, different NH3 sources have generally different δ15N values (ranging from −52.0 to −9.6 ‰. Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (−14.2 ± 2.8 ‰, which can be distinguished from other sources emitted at environmental temperature (−29.1 ± 1.7, −37.8 ± 3.6, and −50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively. The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource. The method was used to quantify the sources of ambient NH3 before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %, 7.3 (8.8, 24.9, 14.3, and 52.0 %, and 12.7 (29.4, 23.6, 31.7, and 15.4 % µg m−3, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH3 mass concentrations. During (after the summit, the contributions of traffic, waste, livestock, and fertilizer

  6. Stable isotope ratios of the atmospheric CH{sub 4}, CO{sub 2} and N{sub 2}O in Tokai-mura

    Energy Technology Data Exchange (ETDEWEB)

    Porntepkasemsan, Boonsom; Andoh, Mariko A.; Amano, Hikaru [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-11-01

    This report presents the results and interpretation of stable isotope ratios of the atmospheric CH{sub 4}, CO{sub 2} and N{sub 2}O from a variety of sources in Tokai-mura. The seasonal changes of {delta}{sup 13}CH{sub 4}, {delta}{sup 13}CO{sub 2} and {delta}{sup 15}N{sub 2}O were determined under in-situ conditions in four sampling sites and one control site. Such measurements are expected to provide a useful means of estimating the transport mechanisms of the three trace gases in the environment. These isotopic signatures were analyzed by Isotope Ratio Mass Spectrometer (IRMS, Micromass Isoprime). Our data showed the significant seasonal fluctuation in the Hosoura rice paddy during the entire growing season in 1999. Possible causes for the variation are postulated. Additional measurements on soil properties and on organic {delta}{sup 13}C in rice plant are suggested. Cited outstanding original papers are summarized in the references. (author)

  7. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

    Science.gov (United States)

    Samuel M. Simkin; Edith B. Allen; William D. Bowman; Christopher M. Clark; Jayne Belnap; Matthew L. Brooks; Brian S. Cade; Scott L. Collins; Linda H. Geiser; Frank S. Gilliam; Sarah E. Jovan; Linda H. Pardo; Bethany K. Schulz; Carly J. Stevens; Katharine N. Suding; Heather L. Throop; Donald M. Waller

    2016-01-01

    Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these...

  8. Peak precipitation intensity in relation to atmospheric conditions and large-scale forcing at midlatitudes

    NARCIS (Netherlands)

    Loriaux, J.M.; Lenderink, Geert; Siebesma, A.P.

    2016-01-01

    Research on relations between atmospheric conditions and extreme precipitation is important to understand and model present-day climate extremes and assess how precipitation extremes might evolve in a future climate. Here we present a statistical analysis of the relation between large-scale

  9. Oxidative stability of n-3-enriched chicken patties under different package-atmosphere conditions.

    Science.gov (United States)

    Penko, Ana; Polak, Tomaž; Lušnic Polak, Mateja; Požrl, Tomaž; Kakovič, Damir; Žlender, Božidar; Demšar, Lea

    2015-02-01

    The oxidation processes were studied in chicken patties, enriched with n-3 fatty acids, after 8days of storage at 4°C, under different aerobic conditions, and following heat treatment. Significant effects were seen on lipid and cholesterol oxidation and the sensory qualities for whole flaxseed addition in the chicken feed (i.e., n-3 fatty acid enrichment), and for the different package-atmosphere conditions. For the raw chicken patties, n-3 enrichment increased the colour L(∗) values while, after the heat treatment, there were higher thiobarbituric acid-reactive substances (TBARs) and cholesterol oxidation products (COPs), and the rancidity was more pronounced. In comparison with the low O2 (atmosphere condition, O2 enrichment (80%) increased the instrumentally measured colour values, TBARs, total and individual COPs, and the rancidity became pronounced. The most suitable package-atmosphere condition of these raw n-3-enriched chicken patties is a very low O2 atmosphere, with or without an O2 scavenger. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Integrated Monitoring Study (IMS) 1995: Characterization of micrometeorological phenomena mixing and diffusion in low wind speed stable conditions: Study design and preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Gray, H.A.; Carr, E.L.; Guo, Z. [Systems Applications International, Inc., San Rafael, CA (United States)] [and others

    1996-12-31

    The objective of the current research effort is to improve the characterization and understanding of mixing and dispersion during low wind speed periods. An outcome of the study will be the development of an enhanced modeling treatment of micrometeorological phenomena within the San Joaquin Valley of California, to be applied during stable atmospheric periods characterized by low wind speeds. The first phase of the study consisted of a literature review and assessment of the current understanding of dispersion under low wind speed conditions, including an evaluation of current modeling approaches. In the second phase of the study, recommendations were made for monitoring, data analysis, and modeling approaches that could be employed during stable low wind speed conditions to increase our understanding and fill critical data gaps. Finally, Phase III includes the execution of the measurement program and subsequent data and modeling analyses. This report presents results of Phase I and Phase II, and describes the measurement program that was conducted in Phase III. Data analysis and modeling will be presented in future reports. 24 refs., 3 figs., 4 tabs.

  11. Numberical Calculations of Atmospheric Conditions over Tibetan Plateau by Using WRF Model

    International Nuclear Information System (INIS)

    Qian, Xuan; Yao, Yongqiang; Wang, Hongshuai; Liu, Liyong; Li, Junrong; Yin, Jia

    2015-01-01

    The wind field, precipitable water vapor are analyzed by using the mesoscale numerical model WRF over Tibetan Plateau, and the aerosol is analyzed by using WRF- CHEM model. The spatial and vertical distributions of the relevant atmospheric factors are summarized, providing truth evidence for selecting and further evaluating an astronomical site. It has been showed that this method could provide good evaluation of atmospheric conditions. This study serves as a further demonstration towards astro-climate regionalization, and provides with essential database for astronomical site survey over Tibetan Plateau. (paper)

  12. Examination of atmospheric dynamic model's performance over complex terrain under temporally changing synoptic meteorological conditions

    International Nuclear Information System (INIS)

    Nagai, Haruyasu; Yamazawa, Hiromi

    1995-01-01

    The mesoscale atmospheric dynamic model, a submodel of the numerical atmospheric dispersion model named PHYSIC, was improved and its performance was examined in a coastal area with a complex terrain. To introduce temporally changing synoptic meteorological conditions into the model, the initial and boundary conditions were improved. Moreover, land surface temperature calculations were modified to apply the model to snow-covered areas. These improvements worked effectively in the model simulation of four series of the observations during winter and summer in 1992. The model successfully simulated the wind fields and its temporal variations under the condition of strong westerlies and a land and sea breeze. Limitation of model's performance caused by the temporal and spatial resolutions of input data was also discussed. (author)

  13. Interaction of oxides of nitrogen and aromatic hydrocarbons under simulated atmospheric conditions

    International Nuclear Information System (INIS)

    Obrien, R.J.; Green, P.J.; Doty, R.A.; Vanderzanden, J.W.; Easton, R.R.; Irwin, R.P.

    1979-01-01

    The reactions of nitrogen oxides with aromatic hydrocarbons under simulated atmospheric conditions are investigated. Gaseous reaction products formed when toluene is irradiated under simulated atmospheric conditions in the presence of nitrogen oxides were analyzed by gas chromatography. Reaction products detected include acetylene, water, acetaldehyde, acetone, toluene, benzaldehyde, ortho-, meta- and para-cresol, benzyl nitrate and meta- and para-nitrotoluene. Reaction mechanisms yielding the various products are illustrated. The assumption that all the nitrogen oxides observed to be lost from the reaction products can be accounted for by nitric acid formation in the absence of ozone formation is verified by a model in which the hydroxyl radical is assumed to be the only means of removing toluene. Under conditions in which ozone is formed, nitrogen oxide loss is accounted for by ozone formation in addition to nitric acid formation

  14. A coupled model study on the Atlantic Meridional Overturning Circulation under extreme atmospheric CO2 conditions

    Directory of Open Access Journals (Sweden)

    Rita Lecci

    2016-05-01

    Full Text Available This study investigates the climate sensitivity to a strong CO2 atmospheric forcing focusing on the North Atlantic Ocean (NA. The analysis is based on a set of 600 years long experiments performed with a state-of-the-art coupled general circulation model (CGCM with the 1990 reference value of atmospheric CO2 multiplied by 4, 8 and 16. Extreme increases in atmospheric CO2 concentration have been applied to force the climate system towards stable states with different thermo-dynamical properties and analyze how the different resulting oceanic stratification and diffusion affect the Atlantic Meridional Overturning Circulation (AMOC. The AMOC weakens in response to the induced warming with distinctive features in the extreme case: a southward shift of convective sites and the formation of a density front at mid-latitudes. The analysis of the density fluxes reveals that NA loses density at high latitudes and gains it southward of 40°N mainly due to the haline contribution. Our results indicate that the most important processes that control the AMOC are active in the high latitudes and are related to the stability of the water column. The increased ocean stratification stabilizes the ocean interior leading to a decreased vertical diffusivity, a reduction in the formation of deep water and a weaker circulation. In particular, the deep convection collapses mainly in the Labrador Sea as a consequence of the water column stratification under high latitudes freshening.

  15. Characteristics of energetic electron precipitation into the earth's polar atmosphere and geomagnetic conditions

    Science.gov (United States)

    Makhmutov, V. S.; Bazilevskaya, G. A.; Krainev, M. B.

    A number of energetic electron precipitation events (EPEs) were observed in the Earth's polar atmosphere (Murmansk region, geographical coordinates 68.57 N, 33.03 E and Mirny, Antarctica, 66.34 S, 92.55 E) during the long-term cosmic ray balloon experiment from 1957 up to now. During geomagnetic storms significant X-ray fluxes caused by precipitating electrons at the top of the atmosphere sometimes penetrated to the atmospheric depth of 60 gcm-2. We show that (1) there is a quasi-11-year cycle in EPE occurrence shifted with respect to solar activity cycle, and (2) the yearly rate of EPE occurrence has an ascending trend during the period 1965-1999. The EPE characteristics evaluated from the balloon experiment are compared with the available data on geomagnetic activity and the possible relations between the features of EPE events and geomagnetic conditions are discussed.

  16. Photolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling

    Directory of Open Access Journals (Sweden)

    J. M. F. Martins

    2009-11-01

    Full Text Available The nitrogen (δ15N and triple oxygen (δ17O and δ18O isotopic composition of nitrate (NO3 was measured year-round in the atmosphere and snow pits at Dome C, Antarctica (DC, 75.1° S, 123.3° E, and in surface snow on a transect between DC and the coast. Comparison to the isotopic signal in atmospheric NO3 shows that snow NO3 is significantly enriched in δ15N by >200‰ and depleted in δ18O by <40‰. Post-depositional fractionation in Δ17O(NO3 is small, potentially allowing reconstruction of past shifts in tropospheric oxidation pathways from ice cores. Assuming a Rayleigh-type process we find fractionation constants ε of −60±15‰, 8±2‰ and 1±1‰, for δ15N, δ18O and Δ17O, respectively. A photolysis model yields an upper limit for the photolytic fractionation constant 15ε of δ15N, consistent with lab and field measurements, and demonstrates a high sensitivity of 15ε to the incident actinic flux spectrum. The photolytic 15ε is process-specific and therefore applies to any snow covered location. Previously published 15ε values are not representative for conditions at the Earth surface, but apply only to the UV lamp used in the reported experiment (Blunier et al., 2005; Jacobi et al., 2006. Depletion of oxygen stable isotopes is attributed to photolysis followed by isotopic exchange with water and hydroxyl radicals. Conversely, 15N enrichment of the NO3 fraction in the snow implies 15N depletion of emissions. Indeed, δ15N in atmospheric NO3 shows a strong decrease from background levels (4±7‰ to −35‰ in spring followed by recovery during summer, consistent with significant snowpack

  17. Conditions for Stable Chip Breaking and Provision of Machined Surface Quality While Turning with Asymmetric Tool Vibrations

    OpenAIRE

    Шелег, В. К.; Молочко, В. И.; Данильчик, С. С.

    2015-01-01

    The paper considers a process of turning structural steel with asymmetric tool vibrations directed along feeding. Asymmetric vibrations characterized by asymmetry coefficient of vibration cycle, their frequency and amplitude are additionally transferred to the tool in the turning process with the purpose to crush chips. Conditions of stable chip breaking and obtaining optimum dimensions of chip elements have been determined in the paper. In order to reduce a negative impact of the vibration a...

  18. New insights to the use of ethanol in automotive fuels: a stable isotopic tracer for fossil- and bio-fuel combustion inputs to the atmosphere.

    Science.gov (United States)

    Giebel, Brian M; Swart, Peter K; Riemer, Daniel D

    2011-08-01

    Ethanol is currently receiving increased attention because of its use as a biofuel or fuel additive and because of its influence on air quality. We used stable isotopic ratio measurements of (13)C/(12)C in ethanol emitted from vehicles and a small group of tropical plants to establish ethanol's δ(13)C end-member signatures. Ethanol emitted in exhaust is distinctly different from that emitted by tropical plants and can serve as a unique stable isotopic tracer for transportation-related inputs to the atmosphere. Ethanol's unique isotopic signature in fuel is related to corn, a C4 plant and the primary source of ethanol in the U.S. We estimated a kinetic isotope effect (KIE) for ethanol's oxidative loss in the atmosphere and used previous assumptions with respect to the fractionation that may occur during wet and dry deposition. A small number of interpretive model calculations were used for source apportionment of ethanol and to understand the associated effects resulting from atmospheric removal. The models incorporated our end-member signatures and ambient measurements of ethanol, known or estimated source strengths and removal magnitudes, and estimated KIEs associated with atmospheric removal processes for ethanol. We compared transportation-related ethanol signatures to those from biogenic sources and used a set of ambient measurements to apportion each source contribution in Miami, Florida-a moderately polluted, but well ventilated urban location.

  19. Gravity Waves and Wind-Farm Efficiency in Neutral and Stable Conditions

    Science.gov (United States)

    Allaerts, Dries; Meyers, Johan

    2018-02-01

    We use large-eddy simulations (LES) to investigate the impact of stable stratification on gravity-wave excitation and energy extraction in a large wind farm. To this end, the development of an equilibrium conventionally neutral boundary layer into a stable boundary layer over a period of 8 h is considered, using two different cooling rates. We find that turbulence decay has considerable influence on the energy extraction at the beginning of the boundary-layer transition, but afterwards, energy extraction is dominated by geometrical and jet effects induced by an inertial oscillation. It is further shown that the inertial oscillation enhances gravity-wave excitation. By comparing LES results with a simple one-dimensional model, we show that this is related to an interplay between wind-farm drag, variations in the Froude number and the dispersive effects of vertically-propagating gravity waves. We further find that the pressure gradients induced by gravity waves lead to significant upstream flow deceleration, reducing the average turbine output compared to a turbine in isolated operation. This leads us to the definition of a non-local wind-farm efficiency, next to a more standard wind-farm wake efficiency, and we show that both can be of the same order of magnitude. Finally, an energy flux analysis is performed to further elucidate the effect of gravity waves on the flow in the wind farm.

  20. Efficacy of passive sampler collection for atmospheric NO2 isotopes under simulated environmental conditions.

    Science.gov (United States)

    Coughlin, Justin G; Yu, Zhongjie; Elliott, Emily M

    2017-07-30

    Nitrogen oxides or NO x (NO x = NO + NO 2 ) play an important role in air quality, atmospheric chemistry, and climate. The isotopic compositions of anthropogenic and natural NO 2 sources are wide-ranging, and they can be used to constrain sources of ambient NO 2 and associated atmospheric deposition of nitrogen compounds. While passive sample collection of NO 2 isotopes has been used in field studies to determine NO x source influences on atmospheric deposition, this approach has not been evaluated for accuracy or precision under different environmental conditions. The efficacy of NO 2 passive sampler collection for NO 2 isotopes was evaluated under varied temperature and relative humidity (RH) conditions in a dynamic flux chamber. The precision and accuracy of the filter NO 2 collection as nitrite (NO 2 - ) for isotopic analysis were determined using a reference NO 2 gas tank and through inter-calibration with a modified EPA Method 7. The bacterial denitrifer method was used to convert 20 μM of collected NO 2 - or nitrate (NO 3 - ) into N 2 O and was carried out on an Isoprime continuous flow isotope ratio mass spectrometer. δ 15 N-NO 2 values determined from passive NO 2 collection, in conditions of 11-34 °C, 1-78% RH, have an overall accuracy and precision of ±2.1 ‰, and individual run precision of ±0.6 ‰. δ 18 O-NO 2 values obtained from passive NO 2 sampler collection, under the same conditions, have an overall precision of ± 1.3 ‰. Suitable conditions for passive sampler collection of NO 2 isotopes are in environments ranging from 11 to 34 °C and 1 to 78% RH. The passive NO 2 isotope measurement technique provides an accurate method to determine variations in atmospheric δ 15 N-NO 2 values and a precise method for determining atmospheric δ 18 O-NO 2 values. The ability to measure NO 2 isotopes over spatial gradients at the same temporal resolution provides a unique perspective on the extent and seasonality of fluctuations in atmospheric NO 2

  1. Some aspects of atmospheric dispersion in the stratified atmospheric boundary layer over homogeneous terrain

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik

    1999-01-01

    The ability to simulate atmospheric dispersion with models developed for applied use under stable atmospheric stability conditions is discussed. The paper is based on model simulations of three experimental data sets reported in the literature. The Hanford data set covered weakly stable condition...

  2. Atmospheric propagation of high power laser radiation at different weather conditions

    OpenAIRE

    Pargmann, Carsten; Hall, Thomas; Duschek, Frank; Handke, Jürgen

    2016-01-01

    Applications based on the propagation of high power laser radiation through the atmosphere are limited in range and effect, due to weather dependent beam wandering, beam deterioration, and scattering processes. Security and defense related application examples are countermeasures against hostile projectiles and the powering of satellites and aircrafts. For an examination of the correlations between weather condition and laser beam characteristics DLR operates at Lampoldshausen a 130 m long fr...

  3. Generation of a severe convective ionospheric storm under stable Rayleigh–Taylor conditions: triggering by meteors?

    Directory of Open Access Journals (Sweden)

    M. C. Kelley

    2016-02-01

    Full Text Available Here we report on four events detected using the Jicamarca Radio Observatory (JRO over an 18-year period, in which huge convective ionospheric storms (CISs occur in a stable ionosphere. We argue that these rare events could be initiated by meteor-induced electric fields. The meteor-induced electric fields map to the bottomside of the F region, causing radar echoes and a localized CIS. If and when a localized disturbance reaches 500 km, we argue that it becomes two-dimensionally turbulent and cascades structure to both large and small scales. This leads to long-lasting structure and, almost certainly, to scintillations over a huge range of latitudes some ±15° wide and to 3 m irregularities, which backscatter the VHF radar waves. These structures located at high altitudes are supported by vortices shed by the upwelling bubble in a vortex street.

  4. Physico-chemical characteristics of apples stored in chilling and controlled atmosphere conditions

    Directory of Open Access Journals (Sweden)

    Mirela Calu

    2010-08-01

    Full Text Available Freshness represents one of the main characteristics of consumer choice of fruits and vegetables. Fruit quality characteristics such as color, firmness and storage potential have long been known to be related to the concentrations of certain fruit glucids (glucose and vitamin C. In this article, three types of apples stored in chilling industrial conditions have been characterized alongside other four types stored in controlled atmosphere conditions, assessing for 7 months, some physico-chemical parameters (extract content, pH, and firmness and glucose and vitamin C content.

  5. Comprehensive assessment of conditions of human activity in stable risk regions of Republic of Kazakhstan

    International Nuclear Information System (INIS)

    Bajbolov, S.M.

    2000-01-01

    It is noted that dozens of hectares of Kazakhstan's land are removed from national use due to high level of ecologically permissible effect. In some regions there is treat of complete loss of lands due to technogene pollution. There are areales of toxic and radioactive industrial wastes and environmental radiation contamination zones forming in result of: activity of Semipalatinsk nuclear test site and nuclear explosions of period 1949-1961; activity of military-industrial, atomic-industrial and military-space enterprises; mining and processing of mineral resources with high content of radioactive elements; wind transfer of radionuclides and radioactive particles of both the natural and the technogene origin; radiation background of natural (In average by Republic 11-18 μR/h) landscapes. Most dangerous are consequences of tests on nuclear and space sites. Kazakhstan is single place on the Earth where nuclear strategic programs were carried out in full volume, beginning from mining and processing of uranium containing raw by producing and testing of nuclear warheads, missiles destroying and disposal of uranium and other radioactive and toxic wastes of military-industrial complex. So, there were 500 atmosphere and underground explosions in former Semipalatinsk, Kostanaj, Akmola, Aktyube, South-Kazakhstan, West-Kazakhstan, Mangistau and Atyrau oblasts. In West Kazakhstan on known nuclear sites (Azgir, Tojsogan, Central) and on Kapustin Yar fly-test complex more than 30 nuclear explosions were carried out in both the atmosphere and the underground. More than hundred military units were tested and exposed and 20 thousand of missiles were destroyed. Powerful sources of pollution are Bojkonyr spaceport and Saryshgan and Elba test sites. Authors noted, that it is necessary develop criteria of definition of payments for resources use, indexes to base taxes, pay for damages. Some problems of regional management could be solved with help this assessment mechanism

  6. A wind turbine wake in changing atmospheric conditions: LES and lidar measurements

    Science.gov (United States)

    Vollmer, L.; C-Y Lee, J.; Steinfeld, G.; Lundquist, J. K.

    2017-05-01

    This work aims to reproduce the measured atmospheric conditions during one day of the CWEX-11 campaign, with a transient LES. The selected period includes several interesting atmospheric conditions for wind power generation such as a nocturnal low-level jet, a highly turbulent convective daytime boundary layer, as well as a distinct evening transition between daytime and nocturnal boundary layers. To include synoptic conditions, large-scale forcing profiles for the LES were derived from a mesoscale simulation with the WRF model. A comparison with lidar measurements shows that the trend of the wind conditions and the diurnal cycle is well replicated by the model chain. Selected periods of the day are simulated with the NREL 5MW turbine model, followed by a qualitative comparison of measured and simulated wakes. We find a strong dependency of the meandering and the shape of the wake on wind profile and turbulence, while a categorization by Obukhov length is less representative for the different conditions. As the veer in the wind profile increases, the deviation of the wind direction at hub height from the direction of the largest wake impact also increases.

  7. Atmospheric conditions measured by a wireless sensor network on the local scale

    Science.gov (United States)

    Lengfeld, K.; Ament, F.

    2010-09-01

    Atmospheric conditions close to the surface, like temperature, wind speed and humidity, vary on small scales because of surface heterogeneities. Therefore, the traditional measuring approach of using a single, highly accurate station is of limited representativeness for a larger domain, because it is not able to determine these small scale variabilities. However, both the variability and the domain averages are important information for the development and validation of atmospheric models and soil-vegetation-atmosphere-transfer (SVAT) schemes. Due to progress in microelectronics it is possible to construct networks of comparably cheap meteorological stations with moderate accuracy. Such a network provides data in high spatial and temporal resolution. The EPFL Lausanne developed such a network called SensorScope, consisting of low cost autonomous stations. Each station observes air and surface temperature, humidity, wind direction and speed, incoming solar radiation, precipitation, soil moisture and soil temperature and sends the data via radio communication to a base station. This base station forwards the collected data via GSM/GPRS to a central server. The first measuring campaign took place within the FLUXPAT project in August 2009. We deployed 15 stations as a twin transect near Jülich, Germany. To test the quality of the low cost sensors we compared two of them to more accurate reference systems. It turned out, that although the network sensors are not highly accurate, the measurements are consistent. Consequently an analysis of the pattern of atmospheric conditions is feasible. The transect is 2.3 km long and covers different types of vegetation and a small river. Therefore, we analyse the influence of different land surfaces and the distance to the river on meteorological conditions. For example, we found a difference in air temperature of 0.8°C between the station closest to and the station farthest from the river. The decreasing relative humidity with

  8. Use of Ensemble Numerical Weather Prediction Data for Inversely Determining Atmospheric Refractivity in Surface Ducting Conditions

    Science.gov (United States)

    Greenway, D. P.; Hackett, E.

    2017-12-01

    Under certain atmospheric refractivity conditions, propagated electromagnetic waves (EM) can become trapped between the surface and the bottom of the atmosphere's mixed layer, which is referred to as surface duct propagation. Being able to predict the presence of these surface ducts can reap many benefits to users and developers of sensing technologies and communication systems because they significantly influence the performance of these systems. However, the ability to directly measure or model a surface ducting layer is challenging due to the high spatial resolution and large spatial coverage needed to make accurate refractivity estimates for EM propagation; thus, inverse methods have become an increasingly popular way of determining atmospheric refractivity. This study uses data from the Coupled Ocean/Atmosphere Mesoscale Prediction System developed by the Naval Research Laboratory and instrumented helicopter (helo) measurements taken during the Wallops Island Field Experiment to evaluate the use of ensemble forecasts in refractivity inversions. Helo measurements and ensemble forecasts are optimized to a parametric refractivity model, and three experiments are performed to evaluate whether incorporation of ensemble forecast data aids in more timely and accurate inverse solutions using genetic algorithms. The results suggest that using optimized ensemble members as an initial population for the genetic algorithms generally enhances the accuracy and speed of the inverse solution; however, use of the ensemble data to restrict parameter search space yields mixed results. Inaccurate results are related to parameterization of the ensemble members' refractivity profile and the subsequent extraction of the parameter ranges to limit the search space.

  9. The formation of cubic ice under conditions relevant to Earth's atmosphere.

    Science.gov (United States)

    Murray, Benjamin J; Knopf, Daniel A; Bertram, Allan K

    2005-03-10

    An important mechanism for ice cloud formation in the Earth's atmosphere is homogeneous nucleation of ice in aqueous droplets, and this process is generally assumed to produce hexagonal ice. However, there are some reports that the metastable crystalline phase of ice, cubic ice, may form in the Earth's atmosphere. Here we present laboratory experiments demonstrating that cubic ice forms when micrometre-sized droplets of pure water and aqueous solutions freeze homogeneously at cooling rates approaching those found in the atmosphere. We find that the formation of cubic ice is dominant when droplets freeze at temperatures below 190 K, which is in the temperature range relevant for polar stratospheric clouds and clouds in the tropical tropopause region. These results, together with heat transfer calculations, suggest that cubic ice will form in the Earth's atmosphere. If there were a significant fraction of cubic ice in some cold clouds this could increase their water vapour pressure, and modify their microphysics and ice particle size distributions. Under specific conditions this may lead to enhanced dehydration of the tropopause region.

  10. [Startup, stable operation and process failure of EBPR system under the low temperature and low dissolved oxygen condition].

    Science.gov (United States)

    Ma, Juan; Li, Lu; Yu, Xiao-Jun; Wei, Xue-Fen; Liu, Juan-Li

    2015-02-01

    A sequencing batch reactor (SBR) was started up and operated with alternating anaerobic/oxic (An/O) to perform enhanced biological phosphorus removal (EBPR) under the condition of 13-16 degrees C. The results showed that under the condition of low temperature, the EBPR system was successfully started up in a short time (<6 d). The reactor achieved a high and stable phosphorus removal performance with an influent phosphate concentration of 20 mg x L(-1) and the dissolved oxygen (DO) concentration of 2 mg x L(-1). The effluent phosphate concentration was lower than 0.5 mg x L(-1). It was found that decreasing DO had an influence on the steady operation of EBPR system. As DO concentration of aerobic phase decreased from 2 mg x L(-1) to 1 mg x L(-1), the system could still perform EBPR and the phosphorus removal efficiency was greater than 97.4%. However, the amount of phosphate released during anaerobic phase was observed to decrease slightly compared with that of 2 mg x L(-1) DO condition. Moreover, the phosphorus removal performance of the system deteriorated immediately and the effluent phosphate concentration couldn't meet the national integrated wastewater discharge standard when DO concentration was further lowered to 0.5 mg x L(-1). The experiments of increasing DO to recover phosphorus removal performance of the EBPR suggested the process failure resulted from low DO was not reversible in the short-term. It was also found that the batch tests of anoxic phosphorus uptake using nitrite and nitrate as electron acceptors had an impact on the stable operation of EBPR system, whereas the resulting negative influence could be recovered within 6 cycles. In addition, the mixed liquid suspended solids (MLSS) of the EBPR system remained stable and the sludge volume index (SVI) decreased to a certain extend in a long run, implying long-term low temperature and low DO condition favored the sludge sedimentation.

  11. The effect of the atmospheric condition on the extensive air shower analysis at the Telescope Array experiment

    International Nuclear Information System (INIS)

    Kobayashi, Y.; Tsunesada, Y.; Tokuno, H.; Kakimoto, F.; Tomida, T.

    2011-01-01

    The accuracies in determination of air shower parameters such as longitudinal profiles or primary energies with the fluorescence detection technique are strongly dependent on atmospheric conditions of the molecular and aerosol components. Moreover, air fluorescence photon yield depends on the atmospheric density, and the transparency of the air for fluorescence photons depends on the atmospheric conditions from EAS to FDs. In this paper, we describe the atmospheric monitoring system in the Telescope Array (TA experiment), and the impact of the atmospheric conditions in air shower reconstructions. The systematic uncertainties of the determination of the primary cosmic ray energies and of the measurement of depth of maximum development (X max ) of EASs due to atmospheric variance are evaluated by Monte Carlo simulation.

  12. Standard test method for determination of resistance to stable crack extension under low-constraint conditions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This standard covers the determination of the resistance to stable crack extension in metallic materials in terms of the critical crack-tip-opening angle (CTOAc), ψc and/or the crack-opening displacement (COD), δ5 resistance curve (1). This method applies specifically to fatigue pre-cracked specimens that exhibit low constraint (crack-length-to-thickness and un-cracked ligament-to-thickness ratios greater than or equal to 4) and that are tested under slowly increasing remote applied displacement. The recommended specimens are the compact-tension, C(T), and middle-crack-tension, M(T), specimens. The fracture resistance determined in accordance with this standard is measured as ψc (critical CTOA value) and/or δ5 (critical COD resistance curve) as a function of crack extension. Both fracture resistance parameters are characterized using either a single-specimen or multiple-specimen procedures. These fracture quantities are determined under the opening mode (Mode I) of loading. Influences of environment a...

  13. Handel's Maser-Soliton Theory of ball lightning: The creation of stable three-dimensional cavitons by an atmospheric maser within an open resonator

    Science.gov (United States)

    Carlson, Glenn Andrew

    This dissertation develops details of Handel's Maser-Soliton Theory of ball lightning. The atmosphere between a thundercloud and the Earth's surface is modeled as an idealized stable open resonator with water vapor as the active medium and the thundercloud and Earth's surface as reflecting surfaces. The stable resonator generates a maser beam that narrows to the beam waist at the Earth's surface, which is assumed to be planar. Two candidate rotational transitions are identified within the ν1ν 2ν3 = 010 vibrational band of water having wavelengths of 13.9 cm and 1.12 cm, and relevant spectroscopic parameters are retrieved from the HITRAN 2008 molecular spectroscopic database. The maser is modeled as a continuously pumped four-level maser that includes the effects of nonradiative relaxation due to molecular collisions and of microwave absorption in atmospheric oxygen. Since maser spiking is highly unlikely to occur due to the high rate of collisional relaxation at normal atmospheric pressure, the electrical breakdown of air must be achieved by the steady state output of the atmospheric maser. A parametric analysis is performed to relate the size of the atmospheric maser to the pumping rate needed to create a steady state population inversion sufficient to generate maser radiation intense enough at the beam waist to result in the electrical breakdown of air. The analysis suggests that electric field intensities at the beam waist sufficient to cause electrical breakdown of air could only be created through huge pumping rates (˜105 to 107 times the critical pumping rate) and only for the most highly curved clouds (g ≈ 0) that give the narrowest beam waists.

  14. Soil-plant-atmosphere conditions regulating convective cloud formation above southeastern US pine plantations.

    Science.gov (United States)

    Manoli, Gabriele; Domec, Jean-Christophe; Novick, Kimberly; Oishi, Andrew Christopher; Noormets, Asko; Marani, Marco; Katul, Gabriel

    2016-06-01

    Loblolly pine trees (Pinus taeda L.) occupy more than 20% of the forested area in the southern United States, represent more than 50% of the standing pine volume in this region, and remove from the atmosphere about 500 g C m-2 per year through net ecosystem exchange. Hence, their significance as a major regional carbon sink can hardly be disputed. What is disputed is whether the proliferation of young plantations replacing old forest in the southern United States will alter key aspects of the hydrologic cycle, including convective rainfall, which is the focus of the present work. Ecosystem fluxes of sensible (Hs) and latent heat (LE) and large-scale, slowly evolving free atmospheric temperature and water vapor content are known to be first-order controls on the formation of convective clouds in the atmospheric boundary layer. These controlling processes are here described by a zero-order analytical model aimed at assessing how plantations of different ages may regulate the persistence and transition of the atmospheric system between cloudy and cloudless conditions. Using the analytical model together with field observations, the roles of ecosystem Hs and LE on convective cloud formation are explored relative to the entrainment of heat and moisture from the free atmosphere. Our results demonstrate that cloudy-cloudless regimes at the land surface are regulated by a nonlinear relation between the Bowen ratio Bo=Hs/LE and root-zone soil water content, suggesting that young/mature pines ecosystems have the ability to recirculate available water (through rainfall predisposition mechanisms). Such nonlinearity was not detected in a much older pine stand, suggesting a higher tolerance to drought but a limited control on boundary layer dynamics. These results enable the generation of hypotheses about the impacts on convective cloud formation driven by afforestation/deforestation and groundwater depletion projected to increase following increased human population in the

  15. Neutral molecular cluster formation of sulfuric acid–dimethylamine observed in real time under atmospheric conditions

    CERN Document Server

    Kürten, Andreas; Simon, Mario; Sipilä, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P; Riccobono, Francesco; Rissanen, Matti P; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H; Steiner, Gerhard; Tomé, António; Tröstl, Jasmin; Winkler, Paul M; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S; Kulmala, Markku; Worsnop, Douglas R; Curtius, Joachim

    2014-01-01

    For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even tho...

  16. Selective and Stable Ethylbenzene Dehydrogenation to Styrene over Nanodiamonds under Oxygen-lean Conditions.

    Science.gov (United States)

    Diao, Jiangyong; Feng, Zhenbao; Huang, Rui; Liu, Hongyang; Hamid, Sharifah Bee Abd; Su, Dang Sheng

    2016-04-07

    For the first time, significant improvement of the catalytic performance of nanodiamonds was achieved for the dehydrogenation of ethylbenzene to styrene under oxygen-lean conditions. We demonstrated that the combination of direct dehydrogenation and oxidative dehydrogenation indeed occurred on the nanodiamond surface throughout the reaction system. It was found that the active sp(2)-sp(3) hybridized nanostructure was well maintained after the long-term test and the active ketonic carbonyl groups could be generated in situ. A high reactivity with 40% ethylbenzene conversion and 92% styrene selectivity was obtained over the nanodiamond catalyst under oxygen-lean conditions even after a 240 h test, demonstrating the potential of this procedure for application as a promising industrial process for the ethylbenzene dehydrogenation to styrene without steam protection. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. The effect of glaze on the quality of frozen stored Alaska pollack (Theragra chalcogramma fillets under stable and unstable conditions

    Directory of Open Access Journals (Sweden)

    Peter Žoldoš

    2011-01-01

    Full Text Available Frozen fillets (n = 288 of Alaska pollack (Theragra chalcogramma were used to evaluate the effect of glaze on lipid oxidation and microbiological indicators during 6 months of freezing storage under stable (−18 °C and unstable temperature (varying from −5 to −18 °C conditions. The amount of glaze, moisture, fat and protein content were measured. Despite the low fat content in Alaska pollack, a positive effect of glazing and stable freezing conditions of storage on the range of oxidative changes of lipids expressed as thiobarbituric acid reactive substances was found. Total counts of viable cells slightly rose before the end of the storage period in both groups with commercially glazed fish. The average counts of psychrotrophs in each group ( were at the same level, ranging from 9.1 ×103 CFU·g-1 to 1.1 × 104 CFU·g-1. According to the microbiological results fillets stored under unstable conditions were considered to be acceptable, but sensory evaluation showed that at the end of frozen storage they could not be consumed because of rancidity. Based on our results, glaze application ranged from 10 to 15% guarantee of final quality, however, prevention of temperature fluctuation during storage is important to keep the quality of the frozen fillets. This is the first similar study in Alaska pollack.

  18. Catalysts and conditions for the highly efficient, selective and stable heterogeneous oligomerisation of ethylene

    CSIR Research Space (South Africa)

    Heveling, J

    1998-10-11

    Full Text Available analysis On- and off-line analyses were carried out using Carlo Erba 4200 gas chromatographs equipped with FID detectors and a 60 m SEG OV1 or BP-1 capillary column. Liquid products were condensed with a water-cooled condenser and the volume of gaseous... that the unhydrogenated gasoline fraction, on the other hand, had a RON of 86.2. Further, from 13C ? NMR it can be determined that aromatics are essentially absent from the fuel samples produced under the LT-HP conditions [14]. An estimation of the amount of linear...

  19. Stable engraftment of human microbiota into mice with a single oral gavage following antibiotic conditioning.

    Science.gov (United States)

    Staley, Christopher; Kaiser, Thomas; Beura, Lalit K; Hamilton, Matthew J; Weingarden, Alexa R; Bobr, Aleh; Kang, Johnthomas; Masopust, David; Sadowsky, Michael J; Khoruts, Alexander

    2017-08-01

    Human microbiota-associated (HMA) animal models relying on germ-free recipient mice are being used to study the relationship between intestinal microbiota and human disease. However, transfer of microbiota into germ-free animals also triggers global developmental changes in the recipient intestine, which can mask disease-specific attributes of the donor material. Therefore, a simple model of replacing microbiota into a developmentally mature intestinal environment remains highly desirable. Here we report on the development of a sequential, three-course antibiotic conditioning regimen that allows sustained engraftment of intestinal microorganisms following a single oral gavage with human donor microbiota. SourceTracker, a Bayesian, OTU-based algorithm, indicated that 59.3 ± 3.0% of the fecal bacterial communities in treated mice were attributable to the donor source. This overall degree of microbiota engraftment was similar in mice conditioned with antibiotics and germ-free mice. Limited surveys of systemic and mucosal immune sites did not show evidence of immune activation following introduction of human microbiota. The antibiotic treatment protocol described here followed by a single gavage of human microbiota may provide a useful, complimentary HMA model to that established in germ-free facilities. The model has the potential for further in-depth translational investigations of microbiota in a variety of human disease states.

  20. Modelling of the diffusion of pollutants in the atmosphere under varying conditions in large cultivated regions

    International Nuclear Information System (INIS)

    Wueneke, C.D.; Schultz, H.

    1975-01-01

    The most important routines of a numerical code based on the particle-in-cell-method for calculating the transport and the turbulent dispersion of inert and radio-active pollutants in the atmosphere have been programmed and have been tested successfully on the CDC computer CYBER 73/76 of the Regional Computer Centre for Niedersachsen in Hanover. Compared to the Gaussian plume model such a numerical code based on the particle-in-cell-method offers several advantages for the computation of the diffusion under varying conditions in large cultivated regions. (orig.) [de

  1. Forest condition and chemical characteristics of atmospheric depositions: research and monitoring network in Lombardy

    Directory of Open Access Journals (Sweden)

    Flaminio DI GIROLAMO

    2002-09-01

    Full Text Available Since 1987, the Regional Forestry Board of Lombardy and the Water Research Institute of the National Research Council have been carrying out surveys of forest conditions and the response of the ecosystem to environmental factors. The study approach is based on a large number of permanent plots for extensive monitoring (Level 1. At this level, crown condition is assessed annually, and soil condition and the nutritional status of forests surveyed. Some of the permanent plots were selected for intensive monitoring (Level 2, focussing mainly on the impact of atmospheric pollution on forest ecosystems. Level 2 monitoring also includes increment analyses, ground vegetation assessment, atmospheric deposition, soil solution analyses and climatic observations. This paper summarises the main results of a pluriannual research, which provides a general picture of the state of forest health in the region and focuses on more detailed investigations, described as case studies. Modified wet and dry samplers which use a water surface to collect dry deposition were used in a pluriannual field campaign at five sites in alpine and prealpine areas, to measure the total atmospheric depositions and to evaluate the nitrogen and sulphate exceedances of critical loads. Throughfall and bulk precipitation chemistry were studied for five years (June 1994-May 1999 at two high elevation forest sites (Val Gerola and Val Masino which were known to differ in terms of tree health, as assessed by live crown condition. Results indicated a higher contribution from the dry deposition of N-NO3 -, N-NH4 + and H+ and considerable canopy leaching of Ca2+, K+ and weak organic acids at Val Gerola, where the symptoms of damage were more evident. In the area of Val Masino (SO, included since 1997 in the national CONECOFOR network, investigations focused on the effectiveness of the biological compartment in modifying fluxes of atmospheric elements, and on the role of nitrogen both as an

  2. Nocturnal surface ozone enhancement over Portugal during winter: Influence of different atmospheric conditions

    KAUST Repository

    Kulkarni, Pavan S.

    2016-09-24

    Four distinct nocturnal surface ozone (NSO) enhancement events were observed, with NSO concentration exceeding 80μg/m3, at multiple ozone (O3) monitoring stations (32 sites) in January, November and December between year 2000–2010, in Portugal. The reasonable explanation for the observed bimodal pattern of surface ozone with enhanced NSO concentration during nighttime has to be transport processes, as the surface ozone production ceases at nighttime. Simultaneous measurements of O3 at multiple stations during the study period in Portugal suggest that horizontal advection alone cannot explain the observed NSO enhancement. Thus, detailed analysis of the atmospheric conditions, simulated with the Weather Research and Forecasting (WRF) model, were performed to evaluate the atmospheric mechanisms responsible for NSO enhancement in the region. Simulations revealed that each event occurred as a result of one or the combination of different atmospheric processes such as, passage of a cold front followed by a subsidence zone; passage of a moving surface trough, with associated strong horizontal wind speed and vertical shear; combination of vertical and horizontal transport at the synoptic scale; formation of a low level jet with associated vertical mixing below the jet stream. The study confirmed that large-scale flow pattern resulting in enhanced vertical mixing in the nocturnal boundary layer, plays a key role in the NSO enhancement events, which frequently occur over Portugal during winter months. © 2016 Elsevier Ltd

  3. Cloud Microphysics and Aerosols as Drivers of Variability in Orographic Precipitation Under Atmospheric River Conditions

    Science.gov (United States)

    Voss, K. K.; Martin, A.; Prather, K. A.

    2017-12-01

    In this study, semi-idealized simulations of flow over a hill using a mesoscale numerical weather prediction model were used in order to study the sensitivity of simulated orographic precipitation under atmospheric river (AR) conditions to cloud microphysics and to aerosol concentration. Semi-idealized atmospheric soundings were constructed using sounding observations from AR events off of the California coast near the Sierra Nevada mountain range allowing them to be constrained by observed moisture-flux precipitation relationships. These ensembles were run using three microphysics schemes with varying complexity. An additional ensemble was run with ice nucleating aerosol concentrations representative of in-situ ice nucleating particle measurements taken during the 2015 CalWater field campaign. AR orographic precipitation simulations were shown to be heavily dependent on the microphysics scheme used. Each scheme resulted in different cloud structure and 24-hr accumulated precipitation amount. These results highlight the need for continued development of modeled microphysics and inclusion of aerosol parameterization in order to improve prediction of precipitation from atmospheric river events.

  4. Stepping towards new parameterizations for non-canonical atmospheric surface-layer conditions

    Science.gov (United States)

    Calaf, M.; Margairaz, F.; Pardyjak, E.

    2017-12-01

    Representing land-atmosphere exchange processes as a lower boundary condition remains a challenge. This is partially a result of the fact that land-surface heterogeneity exists at all spatial scales and its variability does not "average" out with decreasing scales. Such variability need not rapidly blend away from the boundary thereby impacting the near-surface region of the atmosphere. Traditionally, momentum and energy fluxes linking the land surface to the flow in NWP models have been parameterized using atmospheric surface layer (ASL) similarity theory. There is ample evidence that such representation is acceptable for stationary and planar-homogeneous flows in the absence of subsidence. However, heterogeneity remains a ubiquitous feature eliciting appreciable deviations when using ASL similarity theory, especially in scalars such moisture and air temperature whose blending is less efficient when compared to momentum. The focus of this project is to quantify the effect of surface thermal heterogeneity with scales Ο(1/10) the height of the atmospheric boundary layer and characterized by uniform roughness. Such near-canonical cases describe inhomogeneous scalar transport in an otherwise planar homogeneous flow when thermal stratification is weak or absent. In this work we present a large-eddy simulation study that characterizes the effect of surface thermal heterogeneities on the atmospheric flow using the concept of dispersive fluxes. Results illustrate a regime in which the flow is mostly driven by the surface thermal heterogeneities, in which the contribution of the dispersive fluxes can account for up to 40% of the total sensible heat flux. Results also illustrate an alternative regime in which the effect of the surface thermal heterogeneities is quickly blended, and the dispersive fluxes provide instead a quantification of the flow spatial heterogeneities produced by coherent turbulent structures result of the surface shear stress. A threshold flow

  5. Beam steering mechanism for earthcare atmospheric lidar instrument ATLID: an ultra-stable piezoelectric tip tilt mechanism

    Science.gov (United States)

    Prevost, E.; Pain, T.; Weickman, A.; Belmana, S.; Bourgain, F.; Sosnicki, O.; Claeyssen, F.

    2017-09-01

    ATLID (ATmospheric LIDar) is one of the four instruments of EarthCARE satellite, it shall determine vertical profiles of cloud and aerosol physical parameters such as altitude, optical depth, backscatter ratio and depolarisation ratio. The BSA (Beam Steering Assembly), included in emission path, aims at deviating a pulsed high energy UV laser beam to compensate the pointing misalignment between the emission and reception paths of ATLID [1]. It requires a very high stability and high resolution.

  6. Influence of different land surfaces on atmospheric conditions measured by a wireless sensor network

    Science.gov (United States)

    Lengfeld, Katharina; Ament, Felix

    2010-05-01

    Atmospheric conditions close to the surface, like temperature, wind speed and humidity, vary on small scales because of surface heterogeneities. Therefore, the traditional measuring approach of using a single, highly accurate station is of limited representativeness for a larger domain, because it is not able to determine these small scale variabilities. However, both the variability and the domain averages are important information for the development and validation of atmospheric models and soil-vegetation-atmosphere-transfer (SVAT) schemes. Due to progress in microelectronics it is possible to construct networks of comparably cheap meteorological stations with moderate accuracy. Such a network provides data in high spatial and temporal resolution. The EPFL Lausanne developed such a network called SensorScope, consisting of low cost autonomous stations. Each station observes air and surface temperature, humidity, wind direction and speed, incoming solar radiation, precipitations, soil moisture and soil temperature and sends the data via radio communication to a base station. This base station forwards the collected data via GSM/GPRS to a central server. Within the FLUXPAT project in August 2009 we deployed 15 stations as a twin transect near Jülich, Germany. One aim of this first experiment was to test the quality of the low cost sensors by comparing them to more accurate reference measurements. It turned out, that although the network is not highly accurate, the measurements are consistent. Consequently an analysis of the pattern of atmospheric conditions is feasible. For example, we detect a variability of ± 0.5K in the mean temperature at a distance of only 2.3 km. The transect covers different types of vegetation and a small river. Therefore, we analyzed the influence of different land surfaces and the distance to the river on meteorological conditions. On the one hand, some results meet our expectations, e.g. the relative humidity decreases with increasing

  7. Land surface and atmospheric conditions associated with heat waves in the South Central United States

    Science.gov (United States)

    Lee, Eungul; Bieda, Rahama; Shanmugasundaram, Jothiganesh; Richter, Heather

    2017-04-01

    Exposure to extreme heat was reconstructed based on regional land-atmosphere processes from 1979 to 2010 in the South Central U.S. The study region surrounds the Chickasaw Nation (CN), a predominantly Native American population with a highly prevalent burden of climate-sensitive chronic diseases. Land surface and atmospheric conditions for summer heat waves were analyzed during spring (March-April-May, MAM) and summer (June-July-August, JJA) based on the Climate and Ocean: Variability, Predictability, and Change maximum temperature definition for heat wave frequency (HWF). The spatial-temporal pattern of HWF was determined using empirical orthogonal function (EOF) analysis and the corresponding principle component time series of the first EOF of HWF. Statistically significant analyses of observed conditions indicated that sensible heat increased and latent heat fluxes decreased with high HWF in the South Central U.S. The largest positive correlations of sensible heat flux to HWF and the largest negative correlations of latent heat flux to HWF were specifically observed over the CN. This is a significantly different energy transfer regime due to less available soil moisture during the antecedent MAM and JJA. The higher sensible heat from dry soil could cause significant warming from the near surface (> 2.0°C) to the lower troposphere (> 1.5°C), and accumulated boundary layer heat could induce the significant patterns of higher geopotential height and enhance anticyclonic circulations (negative vorticity anomaly) at the midtroposphere. Results suggested a positive land-atmosphere feedback associated with heat waves and called attention to the need for region-specific climate adaptation planning.

  8. THE QUANTITATIVE COMPONENT’S DIAGNOSIS OF THE ATMOSPHERIC PRECIPITATION CONDITION IN BAIA MARE URBAN AREA

    Directory of Open Access Journals (Sweden)

    S. ZAHARIA

    2012-12-01

    Full Text Available The atmospheric precipitation, an essential meteorological element for defining the climatic potential of a region, presents through its general and local particularities a defining influence for the evolution of the other climatic parameters, conditioning the structure of the overall geographic landscape. Their quantitative parameters sets up the regional natural setting and differentiation of water resources, soil, vegetation and fauna, in the same time influencing the majority of human activities’ aspects, through the generated impact over the agriculture, transportation, construction, for tourism etc. Especially, through the evolution of the related climatic parameters (production type, quantity, duration, frequency, intensity and their spatial and temporal fluctuations, the pluviometric extremes set out the maxim manifestation of the energy gap of the hydroclimatic hazards/risks which induce unfavourable or even damaging conditions for the human activities’ progress. Hence, the production of atmospheric precipitation surpluses conditions the triggering, or reactivation of some intense erosion processes, landslides, and last but not least, floods. Just as dangerous are the adverse amounts of precipitation or their absence on longer periods, determining the appearance of droughts, aridity phenomena, which if associated with the sharp anthropic pressure over the environment, favours the expansion of desertification, with the whole process of the arising negative effects. In this context, this paper aims to perform the diagnosis of atmospheric precipitation condition in Baia Mare urban area, through its quantitative component, in multiannual condition (1971-2007, underlining through the results of the analyzed climatic data and their interpretation, the main characteristics that define it. The data bank from Baia Mare station from the National Meteorological Administration network, representative for the chosen study area, was used. Baia

  9. Solubility of AmOHCO3 in aqueous solution under atmospheric conditions

    International Nuclear Information System (INIS)

    Nitsche, H.

    1987-12-01

    Modeling calculations on the solubility of americium have indicated that basic americium carbonate, and not americium trihydroxide, is the solubility-controlling solid in the pH range from 6 to 10 under the influence of atmospheric CO 2 . The solubility of crystalline 243 AmOHCO 3 has been investigated in batch experiments in near-neutral and basic solutions as a function of dissolution time in 0.1 M NaClO 4 at room temperature under oxic conditions. After the solutions reached steady-state conditions, the influence of dissolved solids on the americium concentration in the supernatant solution was studied by utilizing several experimental methods to separate the solution phase from the solid. The solids were characterized by X-ray powder diffraction analysis

  10. Frigate birds track atmospheric conditions over months-long transoceanic flights.

    Science.gov (United States)

    Weimerskirch, Henri; Bishop, Charles; Jeanniard-du-Dot, Tiphaine; Prudor, Aurélien; Sachs, Gottfried

    2016-07-01

    Understanding how animals respond to atmospheric conditions across space is critical for understanding the evolution of flight strategies and long-distance migrations. We studied the three-dimensional movements and energetics of great frigate birds (Fregata minor) and showed that they can stay aloft for months during transoceanic flights. To do this, birds track the edge of the doldrums to take advantage of favorable winds and strong convection. Locally, they use a roller-coaster flight, relying on thermals and wind to soar within a 50- to 600-meter altitude band under cumulus clouds and then glide over kilometers at low energy costs. To deal with the local scarcity of clouds and gain longer gliding distances, birds regularly soar inside cumulus clouds to use their strong updraft, and they can reach altitudes of 4000 meters, where freezing conditions occur. Copyright © 2016, American Association for the Advancement of Science.

  11. Oxidative degradation of organic pollutants in aqueous solution using zero valent copper under aerobic atmosphere condition.

    Science.gov (United States)

    Wen, Gang; Wang, Sheng-Jun; Ma, Jun; Huang, Ting-Lin; Liu, Zheng-Qian; Zhao, Lei; Xu, Jin-Lan

    2014-06-30

    Oxidative degradation of organic pollutants and its mechanism were investigated in aqueous solution using zero valent copper (ZVC) under aerobic atmosphere condition. Diethyl phthalate (DEP) was completely oxidized after 120 min reaction by ZVC at initial pH 2.5 open to the air. DEP degradation followed the pseudo-first-order kinetics after the lag period, and the degradation rate of DEP increased gradually with the increase of ZVC dosage, and the decrease of initial pH from 5.8 to 2.0. ZVC required a shorter induction time and exhibited persistent oxidation capacity compared to that of zero valent iron and zero valent aluminium. The mechanism investigation showed that remarkable amount of Cu(+)/Cu(2+) and H2O2 were formed in ZVC acidic system, which was due to the corrosive dissolution of ZVC and the concurrent reduction of oxygen. The addition of tert-butanol completely inhibited the degradation of DEP and the addition of Fe(2+) greatly enhanced the degradation rate, which demonstrated that hydroxyl radical was mainly responsible for the degradation of DEP in ZVC acidic system under aerobic atmosphere condition, and the formation of hydroxyl radical was attributed to the Fenton-like reaction of in situ formed Cu(+) with H2O2. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Atmospheric propagation of high power laser radiation at different weather conditions

    Science.gov (United States)

    Pargmann, Carsten; Hall, Thomas; Duschek, Frank; Handke, Jürgen

    2016-05-01

    Applications based on the propagation of high power laser radiation through the atmosphere are limited in range and effect, due to weather dependent beam wandering, beam deterioration, and scattering processes. Security and defense related application examples are countermeasures against hostile projectiles and the powering of satellites and aircrafts. For an examination of the correlations between weather condition and laser beam characteristics DLR operates at Lampoldshausen a 130 m long free transmission laser test range. Sensors around this test range continuously monitor turbulence strength, visibility, precipitation, temperature, and wind speed. High power laser radiation is obtained by a TruDisk 6001 disk laser (Trumpf company) yielding a maximum output power of 6 kW at a wavelength of 1030 nm. The laser beam is expanded to 180 mm and focused along the beam path. Power and intensity distribution are measured before and after propagation, providing information about the atmospheric transmission and alterations of diameter and position of the laser beam. Backscattered laser light is acquired by a photo receiver. As a result, measurements performed at different weather conditions show a couple of correlations to the characteristics of the laser beam. The experimental results are compared to a numerical analysis. The calculations are based on the Maxwell wave equation in Fresnel approximation. The turbulence is considered by the introduction of phase screens and the "von Karman" spectrum.

  13. Efficacy of entomopathogenic fungi (Ascomycetes: Hypocreales) against adult Haematobia irritans (Diptera: Muscidae) under stable conditions in the Mexican dry tropics.

    Science.gov (United States)

    Galindo-Velasco, E; Lezama-Gutiérrez, R; Cruz-Vázquez, C; Pescador-Rubio, A; Angel-Sahagún, C A; Ojeda-Chi, M M; Rodríguez-Vivas, R I; Contreras-Lara, D

    2015-04-30

    The purpose of this paper is to evaluate the effect of five strains of Metarhizium anisopliae (Ma) and three strains of Isaria fumosorosea (Ifr) at a concentration of 1×10(8)colony-forming units/ml applied by spraying onto bovines with controlled infestation of Haematobia irritans under stable conditions in the Mexican dry tropics. Four experiments were performed, in each of which three treatments (two fungal strains and one control) were evaluated with eight repetitions for each one, by carrying out a single application of the aqueous suspension of each strain. The animals were isolated in individual cages and direct counts of the infestation were carried out for 13 days. It was observed that strains Ma2, Ma6, Ma10, Ma14, and Ma34 caused 94-100% reduction in infestation between days 12 and 13 post-treatment, while strains Ifr19, Ifr11, and Ifr12 reduced infestation from 90% to 98% up to day 13 post-application. There was an effect in the generation of horn flies from the excrement of bovines that were treated with different strains, reducing the reproduction of subsequent generations. It was concluded that the strains of M. anisopliae and I. fumosorosea evaluated in this study can be used as biocontrol agents in infestations of H. irritans in stabled bovines. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Stable isotope evidence for an atmospheric origin of desert nitrate deposits in northern Chile and southern California, U.S.A.

    Science.gov (United States)

    Böhlke, J.K.; Ericksen, G.E.; Revesz, K.

    1997-01-01

    Natural surficial accumulations of nitrate-rich salts in the Atacama Desert, northern Chile, and in the Death Valley region of the Mojave Desert, southern California, are well known, but despite many geologic and geochemical studies, the origins of the nitrates have remained controversial. N and O isotopes in nitrate, and S isotopes in coexisting soluble sulfate, were measured to determine if some proposed N sources could be supported or rejected, and to determine if the isotopic signature of these natural deposits could be used to distinguish them from various types of anthropogenic nitrate contamination that might be found in desert groundwaters. High-grade caliche-type nitrate deposits from both localities have ??15N values that range from -5 to +5???, but are mostly near 0???. Values of ??15N near 0??? are consistent with either bulk atmospheric N deposition or microbial N fixation as major sources of the N in the deposits. ??18O values of those desert nitrates with ??15N near 0??? range from about +31 to + 50??? (V-SMOW), significantly higher than that of atmospheric O2 (+ 23.5???). Such high values of ??18O are considered unlikely to result entirely from nitrification of reduced N, but rather resemble those of modern atmospheric nitrate in precipitation from some other localities. Assuming that limited modern atmospheric isotope data are applicable to the deposits, and allowing for nitrification of co-deposited ammonium, it is estimated that the fraction of the nitrate in the deposits that could be accounted for isotopically by atmospheric N deposition may be at least 20% and possibly as much as 100%. ??34S values are less diagnostic but could also be consistent with atmospheric components in some of the soluble sulfates associated with the deposits. The stable isotope data support the hypothesis that some high-grade caliche-type nitrate-rich salt deposits in some of the Earth's hyperarid deserts represent long-term accumulations of atmospheric deposition

  15. Suspended Particulates Concentration (PM10 under Unstable Atmospheric Conditions over Subtropical Urban Area (Qena, Egypt

    Directory of Open Access Journals (Sweden)

    M. El-Nouby Adam

    2013-01-01

    Full Text Available The main purpose of this study is to evaluate the suspended particulates (PM10 in the atmosphere under unstable atmospheric conditions. The variation of PM10 was investigated and primary statistics were employed. The results show that, the PM10 concentrations values ranged from 6.00 to 646.74 μg m−3. The average value of PM10 is equal to 114.32 μg m−3. The high values were recorded in April and May (155.17 μg m−3 and 171.82 μg m−3, respectively and the low values were noted in February and December (73.86 μg m−3 and 74.05 μg m−3, respectively. The average value of PM10 of the hot season (125.35 × 10−6 g m−3 was higher than its value for the cold season (89.27 μg m−3. In addition, the effect of weather elements (air temperature, humidity and wind on the concentration of PM10 was determined. The multiple R between PM10 and these elements ranged from 0.05 to 0.47 and its value increased to reach 0.73 for the monthly average of the database used. Finally, the PM10 concentrations were grouped depending on their associated atmospheric stability class. These average values were equal to 122.80 ± 9 μg m−3 (highly unstable or convective, 109.37 ± 12 μg m−3 (moderately unstable and 104.42 ± 15 μg m−3 (slightly unstable.

  16. Low-energy-electron interactions with DNA: approaching cellular conditions with atmospheric experiments

    International Nuclear Information System (INIS)

    Alizadeh, E.; Sanche, L.

    2014-01-01

    A novel technique has been developed to investigate low energy electron (LEE)-DNA interactions in the presence of small biomolecules (e.g., N 2 , O 2 , H 2 O) found near DNA in the cell nucleus, in order to simulate cellular conditions. In this technique, LEEs are emitted from a metallic surface exposed by soft X-rays and interact with DNA thin films at standard ambient temperature and pressure (SATP). Whereas atmospheric N 2 had little effect on the yields of LEE-induced single and double strand breaks, both O 2 and H 2 O considerably modified and increased such damage. The highest yields were obtained when DNA is embedded in a combined O 2 and H 2 O atmosphere. In this case, the amount of additional double strand breaks was supper-additive. The effect of modifying the chemical and physical stability of DNA by platinum-based chemotherapeutic agents (Pt-drugs) including cisplatin, carboplatin and oxaliplatin was also investigated with this technique. The results obtained provide information on the role played by subexcitation-energy electrons and dissociative electron attachment in the radiosensitization of DNA by Pt-drugs, which is an important step to unravel the mechanisms of radiosensitization of these agents in chemo-radiation cancer therapy. (authors)

  17. Elevated Atmospheric CO2 Affects Ectomycorrhizal Species Abundance and Increases Sporocarp Production under Field Conditions

    Directory of Open Access Journals (Sweden)

    Douglas L. Godbold

    2015-04-01

    Full Text Available Anthropogenic activities during the last century have increased levels of atmospheric CO2. Forest net primary productivity increases in response to elevated CO2, altering the quantity and quality of carbon supplied to the rhizosphere. Ectomycorrhizal fungi form obligate symbiotic associations with the fine roots of trees that mediate improved scavenging for nutrients in exchange for a carbohydrate supply. Understanding how the community structure of ectomycorrhizal fungi is altered by climate change is important to further our understanding of ecosystem function. Betula pendula and Fagus sylvatica were grown in an elevated CO2 atmosphere delivered using free air carbon dioxide enrichment (FACE under field conditions in the U.K., and Picea abies was grown under elevated CO2 in glass domes in the Czech Republic. We used morphotyping and sequencing of the internal transcribed spacer region of the fungal ribosomal operon to study ectomycorrhizal community structure. Under FACE, un-colonised roots tips increased in abundance for Fagus sylvatica, and during 2006, sporocarp biomass of Peziza badia significantly increased. In domes, ectomycorrhizal community composition shifted from short-distance and smooth medium-distance to contact exploration types. Supply and competition for carbon belowground can influence ectomycorrhizal community structure with the potential to alter ecosystem function.

  18. Low-energy-electron interactions with DNA: approaching cellular conditions with atmospheric experiments

    Science.gov (United States)

    Alizadeh, Elahe; Sanche, Léon

    2014-04-01

    A novel technique has been developed to investigate low energy electron (LEE)-DNA interactions in the presence of small biomolecules (e.g., N2, O2, H2O) found near DNA in the cell nucleus, in order to simulate cellular conditions. In this technique, LEEs are emitted from a metallic surface exposed by soft X-rays and interact with DNA thin films at standard ambient temperature and pressure (SATP). Whereas atmospheric N2 had little effect on the yields of LEE-induced single and double strand breaks, both O2 and H2O considerably modified and increased such damage. The highest yields were obtained when DNA is embedded in a combined O2 and H2O atmosphere. In this case, the amount of additional double strand breaks was supper-additive. The effect of modifying the chemical and physical stability of DNA by platinum-based chemotherapeutic agents (Pt-drugs) including cisplatin, carboplatin and oxaliplatin was also investigated with this technique. The results obtained provide information on the role played by subexcitation-energy electrons and dissociative electron attachment in the radiosensitization of DNA by Pt-drugs, which is an important step to unravel the mechanisms of radiosensitisation of these agents in chemoradiation cancer therapy.

  19. On the atmospheric conditions affecting the variation of tritium concentration in rainfall

    International Nuclear Information System (INIS)

    Moon, S.-E.; Kim, Y.-K.; Park, J.-K.

    1992-01-01

    Atmospheric conditions affecting the variation of tritium concentration in rainfall were investigated by meteorological analysis during 1980 in Pusan, Korea. Tritium concentrations were high in winter, autumn and spring, in comparison with summer. It was found that there is generally a negative correlation between tritium concentration in rainfall and the mixing ratio, and atmospheric thicknesses. In winter, spring and autumn, high tritium concentrations occurred as the southward continental polar air masses from the north merged into the low pressure air mass in southern China; and relatively low concentrations of tritium appeared when the southward polar air masses combined with the northward low pressure air mass from the East China Sea. In the rainy season, extremely low concentrations of tritium were found when a stationary front was located to the south of Korea, allowing a warm and humid southwest airflow to travel toward the Korean peninsula, and here the potential instability and the existence of active convective clouds were major factors affecting the variation of tritium concentration. (Author)

  20. On the analytic and numeric optimisation of airplane trajectories under real atmospheric conditions

    Science.gov (United States)

    Gonzalo, J.; Domínguez, D.; López, D.

    2014-12-01

    From the beginning of aviation era, economic constraints have forced operators to continuously improve the planning of the flights. The revenue is proportional to the cost per flight and the airspace occupancy. Many methods, the first started in the middle of last century, have explore analytical, numerical and artificial intelligence resources to reach the optimal flight planning. In parallel, advances in meteorology and communications allow an almost real-time knowledge of the atmospheric conditions and a reliable, error-bounded forecast for the near future. Thus, apart from weather risks to be avoided, airplanes can dynamically adapt their trajectories to minimise their costs. International regulators are aware about these capabilities, so it is reasonable to envisage some changes to allow this dynamic planning negotiation to soon become operational. Moreover, current unmanned airplanes, very popular and often small, suffer the impact of winds and other weather conditions in form of dramatic changes in their performance. The present paper reviews analytic and numeric solutions for typical trajectory planning problems. Analytic methods are those trying to solve the problem using the Pontryagin principle, where influence parameters are added to state variables to form a split condition differential equation problem. The system can be solved numerically -indirect optimisation- or using parameterised functions -direct optimisation-. On the other hand, numerical methods are based on Bellman's dynamic programming (or Dijkstra algorithms), where the fact that two optimal trajectories can be concatenated to form a new optimal one if the joint point is demonstrated to belong to the final optimal solution. There is no a-priori conditions for the best method. Traditionally, analytic has been more employed for continuous problems whereas numeric for discrete ones. In the current problem, airplane behaviour is defined by continuous equations, while wind fields are given in a

  1. Pressure and Humidity Measurements at the MSL Landing Site Supported by Modeling of the Atmospheric Conditions

    Science.gov (United States)

    Harri, A.; Savijarvi, H. I.; Schmidt, W.; Genzer, M.; Paton, M.; Kauhanen, J.; Atlaskin, E.; Polkko, J.; Kahanpaa, H.; Kemppinen, O.; Haukka, H.

    2012-12-01

    The Mars Science Laboratory (MSL) called Curiosity Rover landed safely on the Martian surface at the Gale crater on 6th August 2012. Among the MSL scientific objectives are investigations of the Martian environment that will be addressed by the Rover Environmental Monitoring Station (REMS) instrument. It will investigate habitability conditions at the Martian surface by performing a versatile set of environmental measurements including accurate observations of pressure and humidity of the Martian atmosphere. This paper describes the instrumental implementation of the MSL pressure and humidity measurement devices and briefly analyzes the atmospheric conditions at the Gale crater by modeling efforts using an atmospheric modeling tools. MSL humidity and pressure devices are based on proprietary technology of Vaisala, Inc. Humidity observations make use of Vaisala Humicap® relative humidity sensor heads and Vaisala Barocap® sensor heads are used for pressure observations. Vaisala Thermocap® temperature sensors heads are mounted in a close proximity of Humicap® and Barocap® sensor heads to enable accurate temperature measurements needed for interpretation of Humicap® and Barocap® readings. The sensor heads are capacitive. The pressure and humidity devices are lightweight and are based on a low-power transducer controlled by a dedicated ASIC. The transducer is designed to measure small capacitances in order of a few pF with resolution in order of 0.1fF (femtoFarad). The transducer design has a good spaceflight heritage, as it has been used in several previous missions, for example Mars mission Phoenix as well as the Cassini Huygens mission. The humidity device has overall dimensions of 40 x 25 x 55 mm. It weighs18 g, and consumes 15 mW of power. It includes 3 Humicap® sensor heads and 1 Thermocap®. The transducer electronics and the sensor heads are placed on a single multi-layer PCB protected by a metallic Faraday cage. The Humidity device has measurement range

  2. Lipid oxidation and color changes of goose meat stored under vacuum and modified atmosphere conditions.

    Science.gov (United States)

    Orkusz, A; Haraf, G; Okruszek, A; Werenska-Sudnik, M

    2017-03-01

    The objective of the work was to investigate the color and lipid oxidation changes of goose breast meat packaged in vacuum and modified atmosphere (MA) conditions consisting of 80% O2, 20% CO2, and stored in refrigerated conditions at 4°C. Color stability was monitored by determining total heme pigments concentration; relative concentration of myoglobin, oxymyoglobin, and metmyoglobin; parameters of color L*, a*, b*, and sensory evaluation of the surface color. Lipid stability was measured by determining thiobarbituric acid reactive substances (TBARS). The samples were examined in 24 h after slaughter (unpacked muscles) and on d 4, 7, 9, 11 of storage (muscles packed in vacuum and in MA). Through the time of storage, samples packed in MA had higher TBARS values in comparison to the meat packed in vacuum. For samples packed in two types of atmospheres, the total pigments concentration decreased gradually within 11 d of storage. It was observed that relative metmyoglobin concentration increased whereas relative oxymyoglobin concentration decreased in total heme pigments in the MA stored muscle. The relative concentration of all three myoglobin forms sample packed in vacuum remained unchanged. The color parameters (L*, a*, b*) did not change for 11 d of storage for the vacuum packed meat. The value of the color parameter a* decreased and the value of the color parameters L* and b* increased in the samples packaged in MA. The data prove that if you store goose meat in MA (consisting of 80% O2, 20% CO2) or vacuum, the unchanged surface color is preserved for 9 and 11 day, respectively.Vacuum appears to be a better method as regards the maintaining of lipid stability in goose meat. © 2016 Poultry Science Association Inc.

  3. Computational Design of a pH Stable Enzyme: Understanding Molecular Mechanism of Penicillin Acylase's Adaptation to Alkaline Conditions

    Science.gov (United States)

    Suplatov, Dmitry; Panin, Nikolay; Kirilin, Evgeny; Shcherbakova, Tatyana; Kudryavtsev, Pavel; Švedas, Vytas

    2014-01-01

    Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties. PMID:24959852

  4. Computational design of a pH stable enzyme: understanding molecular mechanism of penicillin acylase's adaptation to alkaline conditions.

    Directory of Open Access Journals (Sweden)

    Dmitry Suplatov

    Full Text Available Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties.

  5. Stabilization of atmospheric carbon dioxide via zero emissions—An alternative way to a stable global environment. Part 1: Examination of the traditional stabilization concept

    Science.gov (United States)

    MATSUNO, Taroh; MARUYAMA, Koki; TSUTSUI, Junichi

    2012-01-01

    The concept of “stabilization” of atmospheric CO2 concentration is re-examined in connection with climate-change mitigation strategies. A new “zero-emissions stabilization (Z-stabilization)” is proposed, where CO2 emissions are reduced to zero at some time and thereafter the concentration is decreased by natural removal processes, eventually reaching an equilibrated stable state. Simplified climate experiments show that, under Z-stabilization, considerably larger emissions are permissible in the near future compared with traditional stabilization, with the same constraint on temperature rise. Over longer time scales, the concentration and temperature decrease close to their equilibrium values, much lower than those under traditional stabilization. The smaller temperature rise at final state is essential to avoid longer-term risk of sea level rise, a significant concern under traditional stabilization. Because of these advantages a Z-stabilization pathway can be a candidate of practical mitigation strategies as treated in Part 2. PMID:22850727

  6. Stabilization of atmospheric carbon dioxide via zero emissions--an alternative way to a stable global environment. Part 1: examination of the traditional stabilization concept.

    Science.gov (United States)

    Matsuno, Taroh; Maruyama, Koki; Tsutsui, Junichi

    2012-01-01

    The concept of "stabilization" of atmospheric CO(2) concentration is re-examined in connection with climate-change mitigation strategies. A new "zero-emissions stabilization (Z-stabilization)" is proposed, where CO(2) emissions are reduced to zero at some time and thereafter the concentration is decreased by natural removal processes, eventually reaching an equilibrated stable state. Simplified climate experiments show that, under Z-stabilization, considerably larger emissions are permissible in the near future compared with traditional stabilization, with the same constraint on temperature rise. Over longer time scales, the concentration and temperature decrease close to their equilibrium values, much lower than those under traditional stabilization. The smaller temperature rise at final state is essential to avoid longer-term risk of sea level rise, a significant concern under traditional stabilization. Because of these advantages a Z-stabilization pathway can be a candidate of practical mitigation strategies as treated in Part 2.

  7. Seasonality of stable isotope composition of atmospheric water input at the southern slopes of Mt. Kilimanjaro, Tanzania

    Science.gov (United States)

    Otte, Insa; Detsch, Florian; Gutlein, Adrian; Scholl, Martha A.; Kiese, Ralf; Appelhans, Tim; Nauss, Thomas

    2017-01-01

    To understand the moisture regime at the southern slopes of Mt. Kilimanjaro, we analysed the isotopic variability of oxygen (δ18O) and hydrogen (δD) of rainfall, throughfall, and fog from a total of 2,140 samples collected weekly over 2 years at 9 study sites along an elevation transect ranging from 950 to 3,880 m above sea level. Precipitation in the Kilimanjaro tropical rainforests consists of a combination of rainfall, throughfall, and fog. We defined local meteoric water lines for all 3 precipitation types individually and the overall precipitation, δDprec = 7.45 (±0.05) × δ18Oprec + 13.61 (±0.20), n = 2,140, R2 = .91, p research site. We found an altitude effect of δ18Orain = −0.11‰ × 100 m−1, which varied according to precipitation type and season. The relatively weak isotope or altitude gradient may reveal 2 different moisture sources in the research area: (a) local moisture recycling and (b) regional moisture sources. Generally, the seasonality of δ18Orain values follows the bimodal rainfall distribution under the influences of south- and north-easterly trade winds. These seasonal patterns of isotopic composition were linked to different regional moisture sources by analysing Hybrid Single Particle Lagrangian Integrated Trajectory backward trajectories. Seasonality of dexcess values revealed evidence of enhanced moisture recycling after the onset of the rainy seasons. This comprehensive dataset is essential for further research using stable isotopes as a hydrological tracer of sources of precipitation that contribute to water resources of the Kilimanjaro region.

  8. Investigation of aromatic compound degradation under atmospheric conditions in the outdoor simulation chamber SAPHIR

    Science.gov (United States)

    Nehr, Sascha; Bohn, Birger; Rohrer, Franz; Tillmann, Ralf; Wegener, Robert; Dorn, Hans-Peter; Häseler, Rolf; Brauers, Theo; Wahner, Andreas

    2010-05-01

    Ozone is produced in the lower troposphere by the OH-initiated photooxidation of volatile organic compounds in the presence of NOx. Aromatic hydrocarbons from anthropogenic sources are a major contributor to the OH-reactivity and thus to ozone formation in urban areas [1]. Moreover, their degradation leads to formation of secondary organic aerosol. Aromatic compounds are therefore important trace constituents with regard to air quality. We will present the results of photooxidation experiments which were conducted in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich. The experiments were designed to investigate the degradation mechanisms of benzene and p-xylene, which are among the most abundant aromatics in urban air samples. Benzene and p-xylene were selected because they have high structural symmetry which limits the number of potential isomers of secondary products. The experiments were performed under low-NOx-conditions (≤ 2 ppb). SAPHIR was equipped with instruments for the measurement of the parent aromatics and their major oxidation products, OH radicals, important radical precursors (O3, HONO, HCHO), photolysis frequencies and particulate matter. As shown in previous studies, simulation chamber data from the photooxidation of aromatics cannot be explained satisfactorily with current photochemistry mechanisms. For example the MCMv3.1 tends to overestimate the ozone-concentration and to underestimate the OH-concentration [2]. In this study, we will contrast model calculations with experimental results to check if similar discrepancies can be observed in SAPHIR and how they can be resolved. Based on the results of this preparatory study, further simulation chamber experiments with special emphasis on the radical budget are scheduled in 2010. References: [1] J. G. Calvert, R. Atkinson, K.H. Becker, R.M. Kamens, J.H. Seinfeld, T.J. Wallington, G. Yarwood: The mechanisms of atmospheric oxidation of aromatic hydrocarbons, Oxford University

  9. Future changes in atmospheric condition for the baiu under RCP scenarios

    Science.gov (United States)

    Okada, Y.; Takemi, T.; Ishikawa, H.

    2015-12-01

    This study focuses on atmospheric circulation fields during the baiu in Japan with global warming projection experimental data conducted using a 20-km mesh global atmospheric model (MRI-AGCM3.2) under Representative Concentration Pathways (RCP) scenarios. This model also used 4 different sea surface temperature (SST) initial conditions. Support of this dataset is provided by the Meteorological Research Institute (MRI). The baiu front indicated by the north-south gradient of moist static energy moves northward in present-day climate, whereas this northward shift in future climate simulations is very slow during May and June. In future late baiu season, the baiu front stays in the northern part of Japan even in August. As a result, the rich water vapor is transported around western Japan and the daily precipitation amount will increase in August. This northward shift of baiu front is associated with the westward expansion of the enhanced the North Pacific subtropical high (NPSH) into Japan region. However, the convective activity around northwest Pacific Ocean is inactive and is unlikely to occur convective jump (CJ). These models show that the weak trough exists in upper troposphere around Japan. Therefore, the cold advection stays in the northern part of Japan during June. In July, the front due to the strengthening of the NPSH moves northward, and then it stays until August. This feature is often found between the clustered SSTs, Cluster 2 and 3. The mean field of future August also show the inflow of rich water vapor content to Japan islands. In this model, the extreme rainfall suggested tends to almost increase over the Japan islands during future summer. This work was conducted under the Program for Risk Information on Climate Change supported by the Ministry of Education, Culture, Sports, Science, and Technology-Japan (MEXT).

  10. Impacts of Boundary Conditions on the Simulation of Atmospheric Fields Using RegCM4 over CORDEX East Asia

    OpenAIRE

    Myoung Seok Suh; Seok Geun Oh

    2015-01-01

    The impacts of boundary conditions (BCs) on simulations of RegCM4 for mid-to-upper atmospheric fields over the CORDEX (COordinated Regional Downscaling EXperiment) East Asia domain were investigated using two datasets from integrations over 20 years (1989–2008) with two BCs (ERA and R2). The two datasets showed large differences for the atmospheric variables regardless of the geographic locations, heights, and seasons. The ERA dataset at 850 hPa displayed stronger northerly winds in the west...

  11. Effect of modified atmosphere packaging and storage conditions on quality characteristics of cucumber.

    Science.gov (United States)

    Manjunatha, M; Anurag, Rahul K

    2014-11-01

    Cucumbers (Cucumis sativus L.) stored in perforated modified atmosphere packaging (MAP) under cold room (4 ± 1 °C and 90 ± 2 % RH) and ambient condition (23-26 °C and 63-66 % RH) were evaluated for firmness, weight loss (WL), colour, chilling injury and sensory characteristics. The firmness of cucumbers was decreased to 0.333 and 0.326 N on 6th and 12th day of storage, respectively from initial value of 0.38 N. After 12 days of storage, the WL was in the range of 1.62-12.89 % whereas the cucumber stored under MAP having 2 perforations at 4 ± 1 °C and 90 ± 2 % RH recorded least WL of 1.62 %. The minimum change in colour (Hunter L, a and b values) was observed in the cucumber samples stored at cold room condition. The increase in 'b' values (yellowness) was more in the sample stored at ambient condition with unsealed sample registered highest 'b' values (35.82). On 12th day of storage, sensory quality evaluation revealed that samples stored under perforated MAP at 4 ± 1 °C and 90 ± 2 % RH were acceptable in condition with sensory score of 7.1 and 7.5. Chilling injury was severe in sample unsealed (4.4 chilling injury score) and slight to moderate chilling injury was observed in 2 and 4 perforated package samples stored under cold room condition. The study revealed that cucumber can be stored under MAP with 2 perforations at 4 ± 1 °C and 90 ± 2 % RH and ambient condition (23-26 °C and 63-66 % RH) for 12 and 6 days, respectively.

  12. [Concordance between central venous and arterial blood gases in post-surgical myocardial revascularization patients in stable condition].

    Science.gov (United States)

    Santos-Martínez, Luis Efren; Guevara-Carrasco, Marlene; Naranjo-Ricoy, Guillermo; Baranda-Tovar, Francisco Martín; Moreno-Ruíz, Luis Antonio; Herrera-Velázquez, Marco Antonio; Magaña-Serrano, José Antonio; Valencia-Sánchez, Jesús Salvador; Calderón-Abbo, Moisés Cutiel

    2014-01-01

    The concordance between the parameters of arterial and central venous blood gases has not been defined yet. We studied the concordance between both parameters in post-surgical myocardial revascularization patients in stable condition. Consecutive subjects were studied in a cross-sectional design. The position of the central venous catheter was performed and simultaneously we obtained arterial and central venous blood samples prior to discharge from the intensive care unit. Data are expressed according to Bland-Altman statistical method and the intraclass correlation coefficient. Statistical result was accepted at P<.05. Two hundred and six samples were studied of 103 post-surgical patients, pH and lactate had a mean difference (limits of agreement) 0.029±0.048 (-0018, 0.077) and -0.12±0.22 (-0.57, 0.33) respectively. The magnitude of the intraclass correlation coefficient was 0.904 and 0.943 respectively. The values related to oxygen pressure were 27.86±6.08 (15.9, 39.8) and oxygen saturation 33.02±6.13 (21, 45), with magnitude of 0.258 and 0.418 respectively. The best matching parameters between arterial and central venous blood samples were pH and lactate. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

  13. Extensive Evaluation of a Diffusion Denuder Technique for the Quantification of Atmospheric Stable and Radioactive Molecular Iodine

    DEFF Research Database (Denmark)

    Huang, Ru-Jin; Hou, Xiaolin; Hoffmann, Thorsten

    2010-01-01

    In this paper we present the evaluation and optimization of a new approach for the quantification of gaseous molecular iodine (I2) for laboratory- and field-based studies and its novel application for the measurement of radioactive molecular iodine. α-Cyclodextrin (α-CD) in combination with 129I......, and condition of release and derivatization of iodine, is extensively evaluated and optimized. The collection efficiency is larger than 98% and the limit of detection (LOD) obtained is 0.17 parts-per-trillion-by-volume (pptv) for a sampling duration of 30 min at 500 mL min−1. Furthermore, the potential use...... of this protocol for the determination of radioactive I2 at ultra trace level is also demonstrated when 129I− used in the coating is replaced by 127I− and a multiple denuder system is used. Using the present method we observed 25.7−108.6 pptv 127I2 at Mweenish Bay, Ireland and 108 molecule m−3 129I2 at Mainz...

  14. Atmospheric turbulence conditions leading to focused and folded sonic boom wave fronts.

    Science.gov (United States)

    Piacsek, Andrew A

    2002-01-01

    The propagation and subsequent distortion of sonic booms with rippled wave fronts are investigated theoretically using a nonlinear time-domain finite-difference scheme. This work seeks to validate the rippled wave front approach as a method for explaining the significant effects of turbulence on sonic booms [A. S. Pierce and D. J. Maglieri, J. Acoust. Soc. Am. 51, 702-721 (1971)]. A very simple description of turbulence is employed in which velocity perturbations within a shallow layer of the atmosphere form strings of vortices characterized by their size and speed. Passage of a steady-state plane shock front through such a vortex layer produces a periodically rippled wave front which, for the purposes of the present investigation, serves as the initial condition for a finite-difference propagation scheme. Results show that shock strength and ripple curvature determine whether ensuing propagation leads to wave front folding. High resolution images of the computed full wave field provide insights into the spiked and rounded features seen in sonic booms that have propagated through turbulence.

  15. Study of the atmospheric conditions affecting infrared astronomical measurements at White Mountain, California

    Science.gov (United States)

    Field, G. B.

    1974-01-01

    Measurements are described of atmospheric conditions affecting astronomical observations at White Mountain, California. Measurements were made at more than 1400 times spaced over more than 170 days at the Summit Laboratory and a small number of days at the Barcroft Laboratory. The recorded quantities were ten micron sky noise and precipitable water vapor, plus wet and dry bulb temperatures, wind speed and direction, brightness of the sky near the sun, fisheye lens photographs of the sky, description of cloud cover and other observable parameters, color photographs of air pollution astronomical seeing, and occasional determinations of the visible light brightness of the night sky. Measurements of some of these parameters have been made for over twenty years at the Barcroft and Crooked Creek Laboratories, and statistical analyses were made of them. These results and interpretations are given. The bulk of the collected data are statistically analyzed, and disposition of the detailed data is described. Most of the data are available in machine readable form. A detailed discussion of the techniques proposed for operation at White Mountain is given, showing how to cope with the mountain and climatic problems.

  16. Neural Partial Differentiation for Aircraft Parameter Estimation Under Turbulent Atmospheric Conditions

    Science.gov (United States)

    Kuttieri, R. A.; Sinha, M.

    2012-07-01

    An approach based on neural partial differentiation is suggested for aircraft parameter estimation using the flight data gathered under turbulent atmospheric conditions. The classical methods such as output error and equation error methods suffer from severe convergence issues; resulting in biased, inaccurate, and inconsistent estimates. Though filter error method yields better estimates while dealing with the flight data having process noise, it has few demerits like computational overheads and it allows estimation of a single set of process noise distribution matrix. The proposed neural method does not face any such problem of the classical methods. Moreover, the neural method does not require parameter initialization and a priori knowledge of the model structure. The neural network maps the aircraft state and control variables into the output variables corresponding to aerodynamic forces and moments. The parameter estimation, pertaining to lateral-directional motion, of the research aircraft de Havilland DHC-2 with simulated process noise, is presented. The results obtained using the neural partial differentiation are compared with the nominal values given in literature and with the classical methods. The neural method yields the aerodynamic derivatives very close to the nominal values and having quite low standard deviation. The neural methodology is also validated by comparing actual output variables with the neural predicted and neural reconstructed variables.

  17. Instrumentation for comparing night sky quality and atmospheric conditions of CTA site candidates

    International Nuclear Information System (INIS)

    Fruck, C.; Schweizer, T.; Häfner, D.; Lorentz, E.; Teshima, M.; Gaug, M.; Ernenwein, J.-P.; Costantini, H.; Mandát, D.; Pech, M.; Bulik, T.; Cieslar, M.; Dominik, M.; Ebr, J.; Garczarczyk, M.; Pareschi, G.; Puerto-Giménez, I.

    2015-01-01

    Many atmospheric and climatic criteria have to be taken into account for the selection of a suitable site for the next generation of imaging air-shower Cherenkov telescopes, the ''Cherenkov Telescope Array'' CTA. Such data are not available with sufficient precision, thus a comparison of the proposed sites and final decision based on a comprehensive characterization is impossible. Identical cross-calibrated instruments have been developed which allow for precise comparison between sites, the cross-validation of existing data, and the ground-validation of satellite data. The site characterization work package of the CTA consortium opted to construct and deploy 9 copies of an autonomous multi-purpose weather sensor, incorporating an infrared cloud sensor, a newly developed sensor for measuring the light of the night sky, and an All-Sky-Camera, the whole referred to as Autonomous Tool for Measuring Observatory Site COnditions PrEcisely (ATMOSCOPE). We present here the hardware that was combined into the ATMOSCOPE and characterize its performance

  18. Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Yinhuan Ao

    2017-01-01

    Full Text Available This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT, net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1 affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL, (2 deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3 the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4 integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5 the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude.

  19. Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and vacuum conditions

    International Nuclear Information System (INIS)

    Freeman, J.R.; Harilal, S.S.; Diwakar, P.K.; Verhoff, B.; Hassanein, A.

    2013-01-01

    In this study we examine the emission from brass plasma produced by ns and fs laser ablation under both vacuum and atmosphere environments using identical laser fluences in order to better understand the differences in emission features and plasma dynamics. Optical emission spectra show increased continuum and emission from lower-charged ions for ns laser-produced plasma (LPP), while fs plasma emission spectra show emission primarily from excited neutral species with negligible continuum. Plasma excitation temperature and electron density as a function of time show similar trends for both lasers, though fs LPP expansion appears to be approximately two times faster than ns LPP expansion for the conditions studied. Confinement by the ambient gas is shown to significantly enhance and maintain plasma temperature and density and hence, emission, at later times. ICCD images of plasma expansion showed a broader angular distribution for ns LPP, but narrower angular distribution for fs LPP. Images also confirm the significant effect that the ambient environment has in confining plume expansion. - Highlights: • Emission from ns and fs LIBS plumes are compared under different pressure environments. • Ablation mechanisms for each laser are used to explain different emission features. • Ambient pressure plays a critical role in plume temperature and density evolution. • Visible emission from fs LIBS plume is almost entirely from neutral species. • Spectra collection time delay is shown to be very important in improving S/N and S/B

  20. On cosmic rays flux variations in midlatitudes and their relations to geomagnetic and atmospheric conditions

    Science.gov (United States)

    Morozova, Anna; Blanco, Juan Jose; Mendes Ribeiro, Paulo Fernando

    The cosmic rays flux is globally modulated by the solar cycle and shows anti-correlation with the sunspot number. Near to the Earth it is modulated by the solar wind and the Earth's magnetic field. The analysis of the secondary cosmic rays produced when they interact in the low stratosphere allows extracting information about solar wind structures surrounding Earth's orbit, the magnetic field of the Earth and the temperature of the stratosphere. Recently, a new cosmic ray detector, the TRAGALDABAS, composed by RPC (Resistive Plate Chamber) planes, has been developed and installed to go deeper into the understanding of the cosmic rays arriving to the Earth surface. An international collaboration has been organized for keeping the detector operative and for analyzing the data. Here we present the analysis of the cosmic rays flux variations measured by two cosmic rays detectors of different types located in Spain (Castilla-La Mancha Neutron Monitor - CaLMa - in Guadalajara and TRAGALDABAS in Santiago de Compostela) and their comparison to changes both in the geomagnetic field components measured by the Coimbra Geomagnetic Observatory (Portugal) and in the atmospheric conditions (tropo- and stratosphere) measured by Spanish and Portuguese meteorological stations. The study is focused on a number of recent cosmic rays events and pays specific attention to the comparison of the CaLMa series and the preliminary TRAGALDABAS data.

  1. Impact of local environmental conditions on atmospheric electrical potential gradient measurements

    Science.gov (United States)

    Buzás, Attila; Barta, Veronika; Steinbach, Péter; Bór, József

    2017-04-01

    The atmospheric electrical potential gradient (PG) is a fundamental parameter of the global electric circuit (GEC) which comprises all large scale quasi-static electrical processes occurring in between the surface of the Earth and the lower ionosphere. The observation of PG near the Earth's surface plays a pivotal role in surveying our atmospheric electrical environment. The PG shows high variability in different temporal and spatial scales and it is especially sensitive to local effects. Therefore, obtaining a PG value which represents the general state of the GEC over a larger area rather than various effects due to measuring site-specific local factors is a challenging task. PG measurements are going on in the Széchenyi István Geophysical Observatory (NCK, 47°38' N, 16°43' E) of the Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences near Nagycenk, Hungary since 1961. PG sensors are set up in NCK in an open area surrounded by buildings and trees within 20 m distance. The effect of the changing vegetation on the long-term trend observed in the PG variation at NCK has been subject of debates [1,2,3]. In order to examine the possible bias in the measured PG values due to the relatively close buildings and trees at NCK, two sets of simultaneous PG measurements from two EFM-100 field mills were compared. One field mill was kept at a fixed location while the other was moved to grid points covering the open area around the fixed field mill. The measurement was done in fair weather conditions in summer and was repeated during the winter. The poster demonstrates the performance of this method in surveying the effect of various objects and the state of vegetation on the measured PG values by comparing the measured PG differences to those obtained from electrostatic models calculated by the finite element method using the FEMM 4.2 software package. [1] F. Märcz and R. G. Harrison, 2003, Annales Gephysicae, 21: 2193-2200 [2] F. Märcz and R

  2. Undergraduate Research at a Minority University: Studying the Atmospheric Conditions in Urban vs. Rural Areas

    Science.gov (United States)

    Morris, P. A.; Green Garcia, A.; Hromis, A.; Vaquiz, E.; Wright, J. M.; Austin, S. A.; Johnson, L. P.; Musselwhite, D.; Walter, D.

    2009-12-01

    A grant from the National Science Foundation (NFS) funded a three year atmospheric science program known as the Minority University Consortium for Earth and Space Science (MUCESS) that supports undergraduate research programs devoted to studying ozone (O3) profiles. MUCESS institutions are represented by the University of Houston-Downtown (UHD), Medgar Evers College of the City University of New York (MEC), and South Carolina State University (SCSU). The primary strength of the program lies in the fact that it provides a venue for students from the participating minority institutions to build bridges of dialogue and strengthen research capabilities. A secondary strength of MUCESS is that the collaborative institutions are widely separated geographically but they have excellent communications and the ability to coordinate launches and support annual workshops. MUCESS supported a series of ozonesonde launches from multiple sites between April and July 2009. Both urban and rural sites were chosen based on their proximity to the three participating minority universities. Balloon and ozone monitoring technology facilitated data acquisition from cost-effective, environmentally friendly, and reproducible experiments. Payloads consisting of an ozonesonde, Vaisala® radiosonde, and GPS receiver provided information on dynamic atmospheric conditions that exist from ground level through altitudes up to one hundred thousand feet. Preparations for the collaborative launch included an initial calibration phase where identical calibration procedures prepared all three payloads. This calibration phase was performed five to seven days in advance of the launch. An additional calibration was performed the day of launch to verify communications between in-flight and ground radio transmitter and receiver, as well as to validate partial pressure and O3 concentration output from the ozonesonde. Each payload was tethered to a 600 gram weather balloon which was then carried up to the

  3. Sensitive versus Rough Dependence under Initial Conditions in Atmospheric Flow Regimes

    Directory of Open Access Journals (Sweden)

    Anthony R. Lupo

    2016-12-01

    Full Text Available In this work, we will identify the existence of “rough dependence on initial conditions” in atmospheric phenomena, a concept which is a problem for weather analysis and forecasting. Typically, two initially similar atmospheric states will diverge slowly over time such that forecasting the weather using the Navier-Stokes equations is useless after some characteristic time scale. With rough dependence, two initial states diverge very quickly, implying forecasting may be impossible. Using previous research in atmospheric science, rough dependence is characterized by using quantities that can be calculated using atmospheric data and quantities. Rough dependence will be tested for and identified in atmospheric phenomena at different time scales using case studies. Data were provided for this project by archives outside the University of Missouri (MU and by using the MU RADAR at the South Farm experiment station.

  4. Analysis and experimental study on formation conditions of large-scale barrier-free diffuse atmospheric pressure air plasmas in repetitive pulse mode

    Science.gov (United States)

    Li, Lee; Liu, Lun; Liu, Yun-Long; Bin, Yu; Ge, Ya-Feng; Lin, Fo-Chang

    2014-01-01

    Atmospheric air diffuse plasmas have enormous application potential in various fields of science and technology. Without dielectric barrier, generating large-scale air diffuse plasmas is always a challenging issue. This paper discusses and analyses the formation mechanism of cold homogenous plasma. It is proposed that generating stable diffuse atmospheric plasmas in open air should meet the three conditions: high transient power with low average power, excitation in low average E-field with locally high E-field region, and multiple overlapping electron avalanches. Accordingly, an experimental configuration of generating large-scale barrier-free diffuse air plasmas is designed. Based on runaway electron theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as a discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform E-field are structured. Experimental results show that the volume-scaleable, barrier-free, homogeneous air non-thermal plasmas have been obtained between the gap spacing with the copper-wire electrodes. The area of air cold plasmas has been up to hundreds of square centimeters. The proposed formation conditions of large-scale barrier-free diffuse air plasmas are proved to be reasonable and feasible.

  5. Autofluorescence of atmospheric bioaerosols - Biological standard particles and the influence of environmental conditions

    Science.gov (United States)

    Pöhlker, Christopher; Huffman, J. Alex; Förster, Jan-David; Pöschl, Ulrich

    2013-04-01

    standard bioparticles (pollen, fungal spores, and bacteria) as well as atmospherically relevant chemical substances. We addressed the sensitivity and selectivity of autofluorescence based online techniques. Moreover, we investigated the influence of environmental conditions, such as relative humidity and oxidizing agents in the atmosphere, on the autofluorescence signature of standard bioparticles. Our results will support the molecular understanding and quantitative interpretation of data obtained by real-time FBAP instrumentation [5,6]. [1] Elbert, W., Taylor, P. E., Andreae, M. O., & Pöschl, U. (2007). Atmos. Chem. Phys., 7, 4569-4588. [2] Huffman, J. A., Treutlein, B., & Pöschl, U. (2010). Atmos. Chem. Phys., 10, 3215-3233. [3] Pöschl, U., et al. (2010). Science, 329, 1513-1516. [4] Lakowicz, J., Principles of fluorescence spectroscopy, Plenum publishers, New York, 1999. [5] Pöhlker, C., Huffman, J. A., & Pöschl, U., (2012). Atmos. Meas. Tech., 5, 37-71. [6] Pöhlker, C., Huffman, J. A., Förster J.-D., & Pöschl, U., (2012) in preparation.

  6. CONDITIONS FOR STABLE CHIP BREAKING AND PROVISION OF MACHINED SURFACE QUALITY WHILE TURNING WITH ASYMMETRIC TOOL VIBRATIONS

    Directory of Open Access Journals (Sweden)

    V. K. Sheleh

    2015-01-01

    Full Text Available The paper considers a process of turning structural steel with asymmetric tool vibrations directed along feeding. Asymmetric vibrations characterized by asymmetry coefficient of vibration cycle, their frequency and amplitude are additionally transferred to the tool in the turning process with the purpose to crush chips. Conditions of stable chip breaking and obtaining optimum dimensions of chip elements have been determined in the paper. In order to reduce a negative impact of the vibration amplitude on a cutting process and quality of the machined surfaces machining must be carried out with its minimum value. In this case certain ratio of the tool vibration frequency to the work-piece rotation speed has been ensured in the paper. A formula has been obtained for calculation of this ratio with due account of the expected length of chip elements and coefficient of vibration cycle asymmetry.Influence of the asymmetric coefficient of the tool vibration cycle on roughness of the machined surfaces and cutting tool wear has been determined in the paper. According to the results pertaining to machining of work-pieces made of 45 and ШХ15 steel the paper presents mathematical relationships of machined surface roughness with cutting modes and asymmetry coefficient of tool vibration cycle. Tool feeding being one of the cutting modes exerts the most significant impact on the roughness value and increase of the tool feeding entails increase in roughness. Reduction in coefficient of vibration cycle asymmetry contributes to surface roughness reduction. However, the cutting tool wear occurs more intensive. Coefficient of the vibration cycle asymmetry must be increased in order to reduce wear rate. Therefore, the choice of the coefficient of the vibration cycle asymmetry is based on the parameters of surface roughness which must be obtained after machining and intensity of tool wear rate.The paper considers a process of turning structural steel with asymmetric

  7. Spectroscopic study of the water-soluble organic matter isolated from atmospheric aerosols collected under different atmospheric conditions

    International Nuclear Information System (INIS)

    Duarte, Regina M.B.O.; Pio, Casimiro A.; Duarte, Armando C.

    2005-01-01

    The composition of the water-soluble organic matter from fine aerosols collected in a rural location during two different meteorological conditions (summer and autumn) was investigated by UV-vis, synchronous fluorescence (with Δλ = 20 nm), FT-IR and CPMAS- 13 C NMR spectroscopies. A seasonal variation in the concentration of total carbon, organic carbon and water-soluble organic carbon was confirmed, with higher values during the autumn and lower values during the summer season. The chemical characterisation of the water-soluble organic matter showed that both samples are dominated by a high content of aliphatic structures, carboxyl groups and aliphatic carbons single bonded to one oxygen or nitrogen atom. However, the autumn sample exhibits a higher aromatic content than the summer sample, plus signals due to carbons of phenol, ketones and methoxyl groups. These signals were attributed to lignin breakdown products which are likely to be released during wood combustion processes. The obtained results put into evidence the major contribution of biomass burning processes in domestic fireplaces during low temperature conditions into both the concentration and the bulk chemical properties of the WSOC from fine aerosols

  8. Amino acid stable isotope applications to deep-sea corals: A molecular geochemistry approach to reconstructing past ocean conditions

    Science.gov (United States)

    McMahon, K.; McCarthy, M. D.; Guilderson, T. P.; Sherwood, O.; Williams, B.; Larsen, T.; Glynn, D. S.

    2017-12-01

    Future climate change is predicted to alter ocean productivity, food web dynamics, biogeochemical cycling, and the efficacy of the biological pump. Proteinaceous deep-sea corals act as "living sediment traps," providing long-term, high-resolution records of exported surface ocean production and a window into past changes in ocean condition as a historical context for potential future changes. Here, we present recent work developing the application of compound-specific stable isotope analysis of individual amino acids to proteinaceous deep-sea corals to reconstruct past changes in phytoplankton community composition and biogeochemical cycling. We present new calibrations for molecular isotope comparisons between metabolically active coral polyp tissue and bioarchival proteinaceous skeleton. We then applied these techniques to deep-sea corals from the North Pacific Subtropical Gyre (NPSG) to reconstruct centennial to millennial time scale changes in phytoplankton community composition and biogeochemical cycling as a function of regional climate change. This work suggests that the NPSG has undergone multiple major phytoplankton regime shifts over the last millennium between prokaryotic and eukaryotic phytoplankton communities and associated sources of nitrogen fueling production. The most recent regime, which started around the end of the Little Ice Age and the onset of the Industrial era, is unprecedented in the last 1000 years and resulted in a 30-50% increase in diazotrophic cyanobacteria contribution to export production and an associated 17-27% increase in N2-fixation in the NPSG over last century. By offering the first direct phylogenetic context for long-term shifts in isotopic records of exported particulate organic matter, our data represent a major step forward in understanding the evolution of marine plankton community dynamics, food web architecture, biogeochemical cycling, and the climate feedback loops through the biological pump.

  9. Instrument inter-comparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions

    Science.gov (United States)

    Thalman, R.; Baeza-Romero, M. T.; Ball, S. M.; Borrás, E.; Daniels, M. J. S.; Goodall, I. C. A.; Henry, S. B.; Karl, T.; Keutsch, F. N.; Kim, S.; Mak, J.; Monks, P. S.; Muñoz, A.; Orlando, J.; Peppe, S.; Rickard, A. R.; Ródenas, M.; Sánchez, P.; Seco, R.; Su, L.; Tyndall, G.; Vázquez, M.; Vera, T.; Waxman, E.; Volkamer, R.

    2014-08-01

    The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH3C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons, and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present results from a comprehensive instrument comparison effort at 2 simulation chamber facilities in the US and Europe that included 9 instruments, and 7 different measurement techniques: Broadband Cavity Enhanced Absorption Spectroscopy (BBCEAS), Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS), White-cell DOAS, Fourier Transform Infra-Red Spectroscopy (FTIR, two separate instruments), Laser Induced Phosphoresence (LIP), Solid Phase Micro Extraction (SPME), and Proton Transfer Reaction Mass Spectrometry (PTR-ToF-MS, two separate instruments; only methyl glyoxal as no significant response was observed for glyoxal). Experiments at the National Center for Atmospheric Research (NCAR) compare 3 independent sources of calibration as a function of temperature (293 K to 330 K). Calibrations from absorption cross-section spectra at UV-visible and IR wavelengths are found to agree within 2% for glyoxal, and 4% for methyl glyoxal at all temperatures; further calibrations based on ion-molecule rate constant calculations agreed within 5% for methyl glyoxal at all temperatures. At the EUropean PHOtoREactor (EUPHORE) all measurements are calibrated from the same UV-visible spectra (either directly or indirectly), thus minimizing potential systematic bias. We find excellent linearity under idealized conditions (pure glyoxal or methyl glyoxal, R2 > 0.96), and in complex gas mixtures characteristic of dry photochemical smog systems (o-xylene/NOx and isoprene/NOx, R2 > 0.95; R2 ~ 0.65 for offline SPME measurements of methyl glyoxal). The correlations are more variable in humid ambient air mixtures (RH > 45%) for methyl

  10. Instrument intercomparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions

    Science.gov (United States)

    Thalman, R.; Baeza-Romero, M. T.; Ball, S. M.; Borrás, E.; Daniels, M. J. S.; Goodall, I. C. A.; Henry, S. B.; Karl, T.; Keutsch, F. N.; Kim, S.; Mak, J.; Monks, P. S.; Muñoz, A.; Orlando, J.; Peppe, S.; Rickard, A. R.; Ródenas, M.; Sánchez, P.; Seco, R.; Su, L.; Tyndall, G.; Vázquez, M.; Vera, T.; Waxman, E.; Volkamer, R.

    2015-04-01

    The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH3C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present results from a comprehensive instrument comparison effort at two simulation chamber facilities in the US and Europe that included nine instruments, and seven different measurement techniques: broadband cavity enhanced absorption spectroscopy (BBCEAS), cavity-enhanced differential optical absorption spectroscopy (CE-DOAS), white-cell DOAS, Fourier transform infrared spectroscopy (FTIR, two separate instruments), laser-induced phosphorescence (LIP), solid-phase micro extraction (SPME), and proton transfer reaction mass spectrometry (PTR-ToF-MS, two separate instruments; for methyl glyoxal only because no significant response was observed for glyoxal). Experiments at the National Center for Atmospheric Research (NCAR) compare three independent sources of calibration as a function of temperature (293-330 K). Calibrations from absorption cross-section spectra at UV-visible and IR wavelengths are found to agree within 2% for glyoxal, and 4% for methyl glyoxal at all temperatures; further calibrations based on ion-molecule rate constant calculations agreed within 5% for methyl glyoxal at all temperatures. At the European Photoreactor (EUPHORE) all measurements are calibrated from the same UV-visible spectra (either directly or indirectly), thus minimizing potential systematic bias. We find excellent linearity under idealized conditions (pure glyoxal or methyl glyoxal, R2 > 0.96), and in complex gas mixtures characteristic of dry photochemical smog systems (o-xylene/NOx and isoprene/NOx, R2 > 0.95; R2 ∼ 0.65 for offline SPME measurements of methyl glyoxal). The correlations are more variable in humid ambient air mixtures (RH

  11. February 2003 marine atmospheric conditions and the bora over the northern Adriatic

    Science.gov (United States)

    Dorman, C.E.; Carniel, S.; Cavaleri, L.; Sclavo, M.; Chiggiato, J.; Doyle, J.; Haack, T.; Pullen, J.; Grbec, B.; Vilibic, I.; Janekovic, I.; Lee, C.; Malacic, V.; Orlic, M.; Paschini, E.; Russo, A.; Signell, R.P.

    2007-01-01

    A winter oceanographic field experiment provided an opportunity to examine the atmospheric marine conditions over the northern Adriatic. Mean February winds are from a northeasterly direction over most of the Adriatic and a more northerly direction along the western coast. Wind speeds are fastest in jets over the NE coast during bora events and weakest in the mid-northwestern Adriatic. Diurnal air temperature cycles are smallest on the NE coast and largest in the midwestern Adriatic. The maximum sea-air difference is +10??C on the eastern coast and near zero on the midwestern Adriatic. Boras are northeasterly (from) wind events that sweep off Croatia and Slovenia, bringing slightly colder and drier air over the northern Adriatic. The main bora season is December to March. Winter 2002-2003 was normal for bora events. Synoptic-scale temporal variations are correlated over the northern Adriatic. Fastest Bora winds and highest wind stress over the northern Adriatic is concentrated in four topographically controlled jets. The strongest is the Senj Jet, while the Trieste Jet extends across the entire northern Adriatic. Between each two jets is a weak wind zone. The greatest mean net heat loss is in bora jets in the NE Adriatic, where it was -438 W m-2 and is weakest in the midwestern northern Adriatic, where it was near zero. Wind stress is concentrated over the NE half of Adriatic in four bora jets, while wind stress is weak in the NW Adriatic. There is significant variation in wind stress mean and standard deviation structure over the northern Adriatic with each bora event. Copyright 2006 by the American Geophysical Union.

  12. CANOPY CONDUCTANCE OF PINUS TAEDA, LIQUIDAMBAR STYRACIFLUA AND QUERCUS PHELLOS UNDER VARYING ATMOSPHERIC AND SOIL WATER CONDITION

    Science.gov (United States)

    Sap flow, and atmospheric and soil water data were collected in closed-top chambers under conditions of high soil water potential for saplings of Liquidambar styraciflua L., Quercus phellos L., and Pinus taeda L., three co-occurring species in the southeastern USA. Responses of c...

  13. The preferential growth of branched GDGT source microorganisms under aerobic conditions in peat revealed by stable isotope probing experiments

    Science.gov (United States)

    Huguet, Arnaud; Meador, Travis B.; Laggoun-Défarge, Fatima; Könneke, Martin; Derenne, Sylvie; Hinrichs, Kai-Uwe

    2016-04-01

    Branched glycerol dialkyl glycerol tetraether (brGDGTs) membrane lipids are widely distributed in aquatic and terrestrial environments and are being increasingly used as temperature proxies. Nevertheless, little is known regarding the microorganisms that produce these lipids, which are found in especially high abundance in the anaerobic horizons of peat bogs. We initiated stable isotope probing incubations of peat samples from a Sphagnum-dominated peatland (Jura Mountains, France) to measure the incorporation of (D)-D2O and 13C-labeled dissolved inorganic carbon (DIC) into brGDGTs, and thus gauge the activity, growth, and turnover times of their source organisms. Peat samples were collected from two adjacent sites with contrasting humidity levels (hereafter called "fen" and "bog" sites). For each site, samples from the surficial aerobic layer (acrotelm) and deeper anaerobic layer (catotelm) were collected and were incubated under both anaerobic and aerobic conditions for the acrotelm samples and only anaerobic conditions for the catotelm. The incubations were performed at 12 ° C, consistent with the mean summer air temperature at the sampling site. After two months of incubation, there was no incorporation of 13C label in brGDGTs for samples incubated under either aerobic or anaerobic conditions, showing that brGDGT-producing bacteria are heterotrophic microorganisms, as previously observed in organo-mineral soils (Weijers et al., 2011). Similarly, little to no deuterium incorporation was observed for brGDGTs isolated from anaerobically-incubated deep samples. In contrast, in the aerobic incubations of acrotelm samples from bog and fen, the weighted average δD of brGDGT core lipids (CLs) increased by up to 3332‰ and 933‰ after two months, respectively, indicating that fresh brGDGT CLs were biosynthesized at the peat surface. D incorporation into brGDGT CLs converted to production rates ranging from 30-106 ng cm-3y-1 in the aerobic acrotelm from bog and fen

  14. Fluorescence yield in N sub 2 from quantum efficiency to atmospheric conditions

    CERN Document Server

    Lebrun, D

    2002-01-01

    The detection of cosmic Extensive Air Shower via light emission in atmosphere needs a good knowledge of the primary luminescence yield of air molecules under the impact of charged particles and the transmission of the produced light through the atmosphere as well. In the EUSO Simulation Working Group the handling of the Atmospheric Profile properties was partly devoted to the Grenoble group. It concerns mainly the radiative transfer treatment from the shower site to the ISS, but also it is concerned by the identification of atmospheric parameters whose influence on the EAS profile could be significant. Apart from usual thermodynamical variables ( pressure and temperature), several parameters, such as water vapor and/or aerosols and clouds, can have a severe influence not only on the radiative transfer of light but also on the light production itself. Two main effects are clearly identified: the Cerenkov light yield dependence upon the index of air, and the Fluorescence Yield dependence on meteorological condi...

  15. Evidence for the role of organics in aerosol particle formation under atmospheric conditions

    International Nuclear Information System (INIS)

    Metzger, A.; Dommen, J.; Duplissy, J.; Prevot, A.S.H.; Weingartner, E.; Baltensperger, U.; Verheggen, B.; Riipinen, I.; Kulmala, M.; Spracklen, D.V.; Carslaw, K.S.

    2010-01-01

    New particle formation in the atmosphere is an important parameter in governing the radiative forcing of atmospheric aerosols. However, detailed nucleation mechanisms remain ambiguous, as laboratory data have so far not been successful in explaining atmospheric nucleation. We investigated the formation of new particles in a smog chamber simulating the photochemical formation of H2SO4 and organic condensable species. Nucleation occurs at H2SO4 concentrations similar to those found in the ambient atmosphere during nucleation events. The measured particle formation rates are proportional to the product of the concentrations of H2SO4 and an organic molecule. This suggests that only one H2SO4 molecule and one organic molecule are involved in the rate-limiting step of the observed nucleation process. Parameterizing this process in a global aerosol model results in substantially better agreement with ambient observations compared to control runs.

  16. Atmospheric aerosols in Amazonia and land use change: from natural biogenic to biomass burning conditions.

    Science.gov (United States)

    Artaxo, Paulo; Rizzo, Luciana V; Brito, Joel F; Barbosa, Henrique M J; Arana, Andrea; Sena, Elisa T; Cirino, Glauber G; Bastos, Wanderlei; Martin, Scot T; Andreae, Meinrat O

    2013-01-01

    fine mode aerosol during the dry season in this region. Aerosol light scattering and absorption coefficients at the TT34 site were low during the wet season, increasing by a factor of 5, approximately, in the dry season due to long range transport of biomass burning aerosols reaching the forest site in the dry season. Aerosol single scattering albedo (SSA) ranged from 0.84 in the wet season up to 0.91 in the dry. At the PVH site, aerosol scattering coefficients were 3-5 times higher in comparison to the TT34 site, an indication of strong regional background pollution, even in the wet season. Aerosol absorption coefficients at PVH were about 1.4 times higher than at the forest site. Ground-based SSA at PVH was around 0.92 year round, showing the dominance of scattering aerosol particles over absorption, even for biomass burning aerosols. Remote sensing observations from six AERONET sites and from MODIS since 1999, provide a regional and temporal overview. Aerosol Optical Depth (AOD) at 550 nm of less than 0.1 is characteristic of natural conditions over Amazonia. At the perturbed PVH site, AOD550 values greater than 4 were frequently observed in the dry season. Combined analysis of MODIS and CERES showed that the mean direct radiative forcing of aerosols at the top of the atmosphere (TOA) during the biomass burning season was -5.6 +/- 1.7 W m(-2), averaged over whole Amazon Basin. For high AOD (larger than 1) the maximum daily direct aerosol radiative forcing at the TOA was as high as -20 W m(-2) locally. This change in the radiation balance caused increases in the diffuse radiation flux, with an increase of Net Ecosystem Exchange (NEE) of 18-29% for high AOD. From this analysis, it is clear that land use change in Amazonia shows alterations of many atmospheric properties, and these changes are affecting the functioning of the Amazonian ecosystem in significant ways.

  17. Performance and microbial population dynamics during stable operation and reactivation after extended idle conditions in an aerobic granular sequencing batch reactor.

    Science.gov (United States)

    He, Qiulai; Zhang, Wei; Zhang, Shilu; Zou, Zhuocheng; Wang, Hongyu

    2017-08-01

    The evolution of removal performance and bacterial population dynamics of an aerobic granular sequencing batch reactor were investigated during stable operation and reactivation after prolonged storage. The system was run for a period of 130days including the stable condition phase, storage period and the subsequent reactivation process. Excellent removal performance was obtained during the stable operation period, which was decayed by the extended idle conditions. The removal efficiencies for both carbon and nitrogen decayed while phosphorus removal remained unaffected. Both granules structure and physical properties could be fully restored. Microbial populations shifted sharply and the storage perturbations irreversibly altered the microbial communities at different levels. Extracellular polymeric substances (especially protein) and key groups were identified as contributors for storage and re-startup of the aerobic granular system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. DC superimposed AC high voltage: A new strategy for transferring stable He atmospheric pressure cold plasma bullets through long dielectric tubes

    Science.gov (United States)

    Siadati, S. N.; Sohbatzadeh, F.; Valinataj Omran, Azadeh

    2017-06-01

    This study developed a stable transfer of He atmospheric pressure cold plasma bullets in a large dielectric tube with a length of 70 cm and an inner diameter of 0.4-1.6 cm. DC superimposed AC voltage was used for this purpose. The DC component of the applied voltage generated corona ionization through the tube, which helped in the ignition and transfer of the plasma as a pre-ionization background. The bullets followed the frequency of the AC component; therefore, very high applied energy was not required to ignite this large-scale plasma. To our knowledge, this is the first time such a complex waveform has been reported for the transfer of a plasma bullet. The characteristics of the transferring plasma bullet, such as the power, charge, propagation speed, resistance, AC electrical field (EF) of the plasma, and electrostatic field on the tube surface, were measured. The influence of the tube diameter on these characteristics was investigated. The results showed that the power applied, charge, and power deposited on the target increased as the tube diameter increased. Less plasma resistance and radiation were observed using larger diameters. The root mean square (RMS) values of the axial AC EF of the bullet along the jet axis were higher for the larger diameters, but no special relation between the propagation speed, radial AC EF, and static surface field and tube diameter was observed.

  19. Post-wildfire natural restoration of riparian vegetation under stable hydro-geomorphic conditions: Nahal Grar, Northern Negev Desert, Israel

    Science.gov (United States)

    Egozi, Roey

    2015-04-01

    Wildfires are common to the Mediterranean region due to its defined dry season and long historical anthropogenic activities. Most of post-wildfire studies focus on mountains areas and thus refer to the hill-slope and its physical characteristics, e.g. morphology, length, angles, and aspect; its soil characteristics, e.g. type, infiltration rate, repellency; and its vegetative covers, e.g. planted trees vs. natural forest or native vs. exotic vegetation. In contrary there is very limited literature focusing on ecological and hydro-geomorphic aspects of post-wildfire of riparian vegetation / zone probably because of its negligible burned area relative to the spread of the fire, sometimes, over the whole watershed area. The limited literature on the topic is surprising given the fact that riparian vegetation zone has been acknowledged as a unique and important habitat supporting rich biodiversity. Herein we report on a wildfire event occurred on October 14th 2009 in a river section of Nahal Grar, Northern Negev Desert, Israel. The wildfire although was limited in its area (only 3 hectare) extended over the channel alone from bank to bank and thus provide a unique case study of completely burn down of riparian vegetation, mainly dense stands of Common Red (Australis Phragmites. Therefore a detailed study of this event provides an opportunity to tackle one of the basics questions which is determining the rate of natural restoration process that act at the immediate time after the wildfire event occurred. This type of information is most valuable to professional and stakeholders for better management of post-fire riparian zones. The results of the study suggest that under stable conditions, i.e. no major flood events occurred; disturbance time was short and ranged over 200 days due to, almost, immediate recovery of the riparian vegetation. However the re-growth of the riparian vegetation was not even but rather deferential and more complex then reported in the literature

  20. Source identification of N2O produced during simulated wastewater treatment under different oxygen conditions using stable isotopic analysis

    Directory of Open Access Journals (Sweden)

    T Azzaya

    2014-12-01

    Full Text Available Nitrous oxide (N2O, a potent greenhouse gas which is important in climate change, is predicted to be the most dominant ozone depleting substance. It is mainly produced by oxidation of hydroxylamine (NH2OH or reduction of nitrite (NO2- during microbiological processes such as nitrification and denitrification. Wastewater treatment plant (WWTP is one of the anthropogenic N2O sources because inorganic and organic nitrogen compounds are converted to nitrate (NO3-, in the case of standard system or N2 (in the case of advanced system by bacterial nitrification and denitrification in WWTP. We investigated the N2O production mechanisms during batch experiments that simulate wastewater treatment with activated sludge under various dissolved oxygen (DO concentrations by stable isotope analysis. About 125mL of water was sampled from 30L incubation chamber for several times during the incubation, and concentration and isotopomer ratios of N2O and N-containing species were measured using gas chromatography/isotope ratio mass spectrometry (GC/IRMS. Ammonium (NH4+ consumption was accompanied by increment of nitrite (NO2-, and at the same time dissolved N2O concentration gradually increased to 4850 and 5650 nmol kg-1, respectively, during the four-hour incubation when DO concentrations were 0.2 and 0.5 mg L-1. Observed low SP values (0.2-8.9‰ at DO-0.2 mg L-1, -5.3-6.3‰ at DO-0.5 mg L-1, -1.0-8.3‰ at DO-0.8 mg L-1 in N2O and relationship of nitrogen isotope ratios between N2O and its potential substrates (NH4+, NO3- suggested that N2O produced under the aerobic condition derived mainly from NO2- reduction by ammonia-oxidizing bacteria (nitrifier–denitrification.DOI: http://doi.dx.org/10.5564/mjc.v15i0.313Mongolian Journal of Chemistry  15 (41, 2014, p4-10  

  1. Instrumentation for surveying the lower part of the atmosphere in extremes conditions

    Science.gov (United States)

    Gobinddass, Marie-Line; Molinie, Jack; Richard, Sandrine; Jean-Louis, Sabrina

    To observe atmospheric phenomena such as clouds, precipitation and wind in order to understand how they form and evolve meteorologists use few instruments which allows to measure parameters as temperature, pressure and humidity. In the specific case of Kourou region where the French Space Agency is located the environment and safeguard group works on protecting biodiversity in and around the center. By considering a few scientific challenges in atmospheric science one of the main topics of this work consists on the understanding of the fluctuation of the atmosphere due to natural or industrials perturbations. We have considered a few experiences with many instruments in a large space of more than 1200 km per square. To differentiate and try to quantify industrial cloud from natural cloud or from natural atmosphere, the idea of using a drone has been experimented. The ratio of the cost of such experimentation with the relevance of the results which can be obtained will be discussed here. It is necessary to take into account the turbulence in the atmosphere due to industrial acid cloud or hot cloud. Finally, instead of taking the risk of having airbone measurements with a pilot we have thought of the tetherball due to it lower cost and for security reason. The technical experiment and few type of results will be presented here.

  2. Electrified atmospheric dust during disturbed weather conditions in the Negev desert

    Science.gov (United States)

    Katz, Shai; Yair, Yoav; Price, Colin; Yaniv, Roy

    2017-04-01

    Dust storms over the Negev Desert in southern Israel are common and become frequent during the spring and autumn, depending on synoptic conditions and local effects. These storms are often accompanied by significant dust electrification, most likely due to saltation and triboelectric processes. We present new atmospheric electrical measurements conducted at the Wise Observatory (WO) in Mizpe-Ramon (30035'N, 34045'E) Israel, during two strong dust storms that occurred over the Negev desert on October 27-28th and December 1st, 2016. The first event generated a local gust front due to strong downdrafts from an active Cumulonimbus cloud (known as Haboob). In the second event, a Cyprus Low with strong synoptic-scale winds lifted the local sand particles at the Negev and lowered the visibility. During the passage of the dust storms above our instruments, very large fluctuations in the electric field (Ez) and current density (Jz) were measured. In the October Haboob event, the Ez data showed a superposition of signatures generated by lightning and by the dust aloft. The Ez values fluctuated between +123 to +2144 and -15336 to +19788 V m-1 for several hour-long episodes. The respective values of the vertical current density [Jz] were between -18 and +18 pA m-2. During the December dust storm we measured Ez values up to +4000 V m-1 lasting for 3.5 hours and another episode with values up to +668 V m-1 lasting for approximately 1.5 hours. These values were accompanied by changes in the Jz values between -16.5 and +17 pA m-2. The electric field and current density variability and amplitude are significantly different from the average fair-weather values measured at the Wise Observatory (Yaniv et al., 2016), which are 180 V m-1 and 2 pA m-1. We will show that these differences in the electrical behavior between these two dust storms may be related to the speed and direction of the wind near the surface.

  3. Attribution of soil moisture dynamics - Initial conditions vs. atmospheric forcing and the role of climate change

    Science.gov (United States)

    Orth, Rene; Seneviratne, Sonia I.

    2014-05-01

    conditions versus the atmospheric forcing for monthly soil moisture variations. We find that initial soil moisture anomalies are overall more important than the forcing, even if less pronounced in summer. Especially in southern Europe we show high drought forecasting potential, whereas the forcing is more important in Central and North-eastern Europe.

  4. Atmosphere and water loss from early Mars under extreme solar wind and extreme ultraviolet conditions.

    Science.gov (United States)

    Terada, Naoki; Kulikov, Yuri N; Lammer, Helmut; Lichtenegger, Herbert I M; Tanaka, Takashi; Shinagawa, Hiroyuki; Zhang, Tielong

    2009-01-01

    The upper limits of the ion pickup and cold ion outflow loss rates from the early martian atmosphere shortly after the Sun arrived at the Zero-Age-Main-Sequence (ZAMS) were investigated. We applied a comprehensive 3-D multi-species magnetohydrodynamic (MHD) model to an early martian CO(2)-rich atmosphere, which was assumed to have been exposed to a solar XUV [X-ray and extreme ultraviolet (EUV)] flux that was 100 times higher than today and a solar wind that was about 300 times denser. We also assumed the late onset of a planetary magnetic dynamo, so that Mars had no strong intrinsic magnetic field at that early period. We found that, due to such extreme solar wind-atmosphere interaction, a strong magnetic field of about approximately 4000 nT was induced in the entire dayside ionosphere, which could efficiently protect the upper atmosphere from sputtering loss. A planetary obstacle ( approximately ionopause) was formed at an altitude of about 1000 km above the surface due to the drag force and the mass loading by newly created ions in the highly extended upper atmosphere. We obtained an O(+) loss rate by the ion pickup process, which takes place above the ionopause, of about 1.5 x 10(28) ions/s during the first water loss equivalent to a global martian ocean with a depth of approximately 8 m. Consequently, even if the magnetic protection due to the expected early martian magnetic dynamo is neglected, ion pickup and sputtering were most likely not the dominant loss processes for the planet's initial atmosphere and water inventory. However, it appears that the cold ion outflow into the martian tail, due to the transfer of momentum from the solar wind to the ionospheric plasma, could have removed a global ocean with a depth of 10-70 m during the first < or =150 million years after the Sun arrived at the ZAMS.

  5. Description of atmospheric conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)

    Czech Academy of Sciences Publication Activity Database

    Abreu, P.; Aglietta, M.; Ahlers, M.; Boháčová, Martina; Chudoba, Jiří; Ebr, Jan; Mandát, Dušan; Nečesal, Petr; Nožka, Libor; Palatka, Miroslav; Pech, Miroslav; Prouza, Michael; Řídký, Jan; Schovancová, Jaroslava; Schovánek, Petr; Šmída, R.; Trávníček, Petr; Vícha, Jakub

    2012-01-01

    Roč. 35, č. 9 (2012), s. 591-607 ISSN 0927-6505 R&D Projects: GA MŠk LC527; GA MŠk(CZ) 1M06002; GA AV ČR KJB100100904; GA AV ČR KJB300100801; GA MŠk(CZ) LA08016 Institutional research plan: CEZ:AV0Z10100502; CEZ:AV0Z10100522 Keywords : cosmic rays * extensive air shower s * atmospheric monitoring * atmospheric models Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 4.777, year: 2012 http://www.sciencedirect.com/science/article/pii/S0927650511002271

  6. Soil-plant-atmosphere conditions regulating convective cloud formation above southeastern US pine plantations

    Science.gov (United States)

    Gabriele Manoli; Jean-Christophe Domec; Kimberly Novick; Andrew C. Oishi; Asko Noormets; Marco Marani; Gabriel Katul

    2016-01-01

    Loblolly pine trees (Pinus taeda L.) occupy more than 20% of the forested area in the southern United States, representmore than 50% of the standing pine volume in this region, and remove from the atmosphere about 500 g C m_2 per year through net ecosystem exchange. Hence, their significance as a major regional carbon sink can hardly be...

  7. Modelling the autoxidation of myoglobin in fresh meat under modified atmosphere packing conditions

    DEFF Research Database (Denmark)

    Tofteskov, Jon; Hansen, Jesper Schmidt; Bailey, Nicholas

    2017-01-01

    Modified atmosphere packing (MAP) is a technique to increase the shelf life of fresh meat. Continuing development of MAP requires better understanding of the physical and chemical processes taking place, in particular the diffusion of oxygen and its reaction with myoglobin. We model these processes...

  8. Quality of meat products packaged and stored under vacuum and modified atmosphere conditions.

    Science.gov (United States)

    Stasiewicz, M; Lipiński, K; Cierach, M

    2014-09-01

    The experimental materials comprised cooked coarsely-ground and finely-ground sausages. The sausages were packaged in vacuum (V) and in modified atmospheres with the following composition: 20 % CO2, 80 % N2 (A1); 50 % CO2, 50 % N2 (A2); 80 % CO2, 20 % N2 (A3). The samples were stored at around 4 °C for 15 days. The measurements were repeated 8 times: at the completion of the production process and at 3-day intervals (day 0, 3, 6, 9, 12, 15) during storage. Drip loss changes in the package were analyzed during storage. Meat products were subjected to a sensory evaluation. The obtained results show that changes in the quality of meat products packaged under modified atmosphere are significantly influenced by the composition of the applied atmosphere. A wider range of quality changes were noted in vacuum-packaged products. Changes in the quality of modified atmosphere packaged products were less significant.

  9. Comparison of two standard test methods for determining explosion limits of gases at atmospheric conditions.

    Science.gov (United States)

    De Smedt, G; de Corte, F; Notelé, R; Berghmans, J

    1999-12-31

    A comparison is made between two internationally accepted methods to determine the explosion limits of gases at atmospheric pressure and room temperature (20 l sphere - DIN 51649). Significant differences (about 1 vol.%) in the upper explosion limits (UEL) values are found for four hydrocarbons tested. A new criterion is proposed which leads to close agreement between the UEL values obtained by the two methods.

  10. Experimental evidence for the role of ions in particle nucleation under atmospheric conditions

    DEFF Research Database (Denmark)

    Svensmark, Henrik; Pedersen, Jens Olaf Pepke; Marsh, N.D.

    2007-01-01

    Experimental studies of aerosol nucleation in air, containing trace amounts of ozone, sulphur dioxide and water vapour at concentrations relevant for the Earth's atmosphere, are reported. The production of new aerosol particles is found to be proportional to the negative ion density and yields...

  11. Homogenous Nucleation of Sulfuric Acid and Water at Close to Atmospherically Relevant Conditions

    Czech Academy of Sciences Publication Activity Database

    Brus, David; Neitola, K.; Hyvärinen, A.-P.; Petäjä, T.; Vanhanen, J.; Sipilä, M.; Paasonen, P.; Kulmala, M.; Lihavainen, H.

    2011-01-01

    Roč. 11, č. 11 (2011), s. 5277-5287 ISSN 1680-7316 Grant - others:GA FCE(FI) 1118615 Institutional research plan: CEZ:AV0Z40720504 Keywords : homogeneous nucleation rates * atmospheric measurements * sulfuric acid Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.520, year: 2011

  12. Preincubation of Penicillium commune conidia under modified atmosphere conditions: Influence on growth potential as determined by an impedimetric method

    DEFF Research Database (Denmark)

    Haasum, Iben; Nielsen, Per Væggemose

    1996-01-01

    conditions in sealed vials for 14, 35 and 56 d. Lag time and growth rates were determined using impedance microbiology on a Bactometer. Conidia survived and some swelling was observed during all experimental preincubation conditions. Regression analysis of the subsequent growth responses showed that relative......The combined effect of preincubation time, relative humidity (r.h.), headspace carbon dioxide (CO2) and oxygen (O2) on subsequent growth potential of conidia from Penicillium commune was studied using Response Surface Modelling (RSM). Native conidia were preincubated under modified atmosphere...... on the growth potential of the conidia. Increasing CO2 levels (7% to 20%) in the storage atmosphere, reduced lag times from 65 to 25 h. By the same increase in CO2 levels, at 70% r.h. growth rates were doubled. Oxygen in the range 2-18%, did not produce any significant effect on either lag time or growth rate...

  13. Microbial population dynamics in continuous anaerobic digester systems during start up, stable conditions and recovery after starvation.

    Science.gov (United States)

    de Jonge, Nadieh; Moset, Veronica; Møller, Henrik Bjarne; Nielsen, Jeppe Lund

    2017-05-01

    The evolution and population dynamics of complex anaerobic microbial communities in anaerobic digesters were investigated during stable operation and recovery after prolonged starvation. Three thermophilic reactor systems fed with cattle manure were operated continuously in parallel for 167days. Significant changes in the microbial communities were observed for both the bacterial and archaeal populations as the reactor systems were subjected to changing feeding regimes. The ecosystems developed from being relatively similar in structure to more specialised communities, with large population shifts within the acetogenic and methanogenic communities, which appeared to shift towards the hydrogenotrophic methanogenesis pathway. All reactor systems showed signs of adaptation to a harsher environment under high VFA, H 2 S and ammonia concentrations, but remained at a lower degree of stability after 45days of recovery compared to stable period of operation before starvation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Assessing the impacts of seasonal and vertical atmospheric conditions on air quality over the Pearl River Delta region

    Science.gov (United States)

    Tong, Cheuk Hei Marcus; Yim, Steve Hung Lam; Rothenberg, Daniel; Wang, Chien; Lin, Chuan-Yao; Chen, Yongqin David; Lau, Ngar Cheung

    2018-05-01

    Air pollution is an increasingly concerning problem in many metropolitan areas due to its adverse public health and environmental impacts. Vertical atmospheric conditions have strong effects on vertical mixing of air pollutants, which directly affects surface air quality. The characteristics and magnitude of how vertical atmospheric conditions affect surface air quality, which are critical to future air quality projections, have not yet been fully understood. This study aims to enhance understanding of the annual and seasonal sensitivities of air pollution to both surface and vertical atmospheric conditions. Based on both surface and vertical meteorological characteristics provided by 1994-2003 monthly dynamic downscaling data from the Weather and Research Forecast Model, we develop generalized linear models (GLMs) to study the relationships between surface air pollutants (ozone, respirable suspended particulates, and sulfur dioxide) and atmospheric conditions in the Pearl River Delta (PRD) region. Applying Principal Component Regression (PCR) to address multi-collinearity, we study the contributions of various meteorological variables to pollutants' concentration levels based on the loading and model coefficient of major principal components. Our results show that relatively high pollutant concentration occurs under relatively low mid-level troposphere temperature gradients, low relative humidity, weak southerly wind (or strong northerly wind) and weak westerly wind (or strong easterly wind). Moreover, the correlations vary among pollutant species, seasons, and meteorological variables at various altitudes. In general, pollutant sensitivity to meteorological variables is found to be greater in winter than in other seasons, and the sensitivity of ozone to meteorology differs from that of the other two pollutants. Applying our GLMs to anomalous air pollution episodes, we find that meteorological variables up to mid troposphere (∼700 mb) play an important role in

  15. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  16. Changes in body fat percentage during body weight stable conditions of increased daily protein intake vs. control.

    Science.gov (United States)

    Soenen, Stijn; Westerterp-Plantenga, Margriet S

    2010-12-02

    The objective of this study was to examine if increased protein intake vs. control influences body fat percentage during stable body weight. Body composition was assessed before and after a 3-month isoenergetic dietary intervention of 2MJ/d supplements exchanged with 2MJ/d of habitual ad libitum energy intake. The parallel design consisted of protein-rich supplements in the protein group (n=12) and an isoenergetic combination of carbohydrate and fat supplements in the control group (n=12). Daily protein intake was calculated from a 24h urinary nitrogen. Body composition was measured by a combination of underwater-weighing technique, deuterium-dilution technique and whole-body dual-energy X-ray absorptiometry (DXA), a method that allows for estimation of 4-body compartments (fat and lean; water, bone and rest). Subjects were weight stable and did not change their habitual physical activity. Daily protein intake increased in the protein group during the intervention compared to baseline with +11±14g (Pbody fat percentage showed a significant group×time interaction of decreased body fat percentage of -1.0±1.1% of the protein group vs. 0.1±0.6% of the control group (Pbody fat percentage decreased with unchanged physical activity during 3months of stable body weight. Copyright © 2010 Elsevier Inc. All rights reserved.

  17. Adaptive Artificial intelligence based fuzzy logic MPPTcontrol for stande-alone photovoltaic system under different atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Zaghba Layachi

    2015-08-01

    Full Text Available there is an increased need for analysing the effect of atmospheric variables on photovoltaic (PV production and performance. The outputs from the different PV cells in different atmospheric conditions, such as irradiation and temperature , differ from each other evidencing knowledge deficiency in PV systems [14]. Maximum power point tracking (MPPT methods are used to maximize the PV array output power by tracking continuously the maximum power point (MPP. Among all MPPT methods existing in the literature, perturb and observe (P&O is the most commonly used for its simplicity and ease of implementation; however, it presents drawbacks such as slow response speed, oscillation around the MPP in steady state, and even tracking in wrong way under rapidly changing atmospheric conditions. In order to allow a functioning around the optimal point Mopt, we have inserted a DC-DC converter (Buck–Boost for a better matching between the PV and the load. This paper, we study the Maximum power point tracking using adaptive Intelligent fuzzy logic and conventional (P&O control for stande-alone photovoltaic Array system .In particular, the performances of the controllers are analyzed under variation weather conditions with are constant temperature and variable irradiation. The proposed system is simulated by using MATLAB-SIMULINK. According to the results, fuzzy logic controller has shown better performance during the optimization.

  18. Visible spectroscopy as a tool for the assessment of storage conditions of fresh pork packaged in modified atmosphere.

    Science.gov (United States)

    Spanos, Dimitrios; Christensen, Mette; Tørngren, Mari Ann; Baron, Caroline P

    2016-03-01

    The storage conditions of fresh meat are known to impact its colour and microbial shelf life. In the present study, visible spectroscopy was evaluated as a method to assess meat storage conditions and its optimisation. Fresh pork steaks (longissimus thoracis et lumborum and semimembranosus) were placed in modified atmosphere packaging using gas mixtures containing 0, 40, 50, and 80% oxygen, and stored with or without light for up to 9days. Principal component analysis of visible reflectance spectra (400-700nm) showed that the colour of the different meat cuts was affected by presence of oxygen, illumination, and storage time. Differences in the oxygen levels did not contribute to the observed variance. Predictive models based on partial least squares regression-discriminant analysis exhibited high potency in the classification of the storage parameters of meat cuts packaged in modified atmosphere. The study demonstrates the applicability of visible spectroscopy as a tool to assess the storage conditions of meat cuts packaged in modified atmosphere. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Physical modeling of flow over an axisymmetric knoll under neutral atmospheric conditions

    International Nuclear Information System (INIS)

    Cliff, W.C.; Smith, J.D.

    1980-02-01

    A glass-walled hydraulic (water) flume was used to model physically air flow near an axisymmetric knoll in a neutral atmospheric boundary layer. The knoll was a 1:250 scale model. An upstream velocity profile (1/7 power law), characteristic of a neutral atmospheric boundary layer, was produced by locating a 10-cm-high (4-in.) trip near the flume entrance and by appropriately roughening the flume floor. Mean velocity, rms velocity, and turbulence intensity profiles were measured at locations near the knoll using an existing laser Doppler anemometer system. The flow accelerated over the knoll and produced a relatively uniform velocity profile at the crest. The measured velocity profile was in close agreement with a theoretical velocity profile developed using potential flow theory and an upstream power law velocity profile. The turbulence intensity decreased at the crest of the knoll as a result of the flow acceleration

  20. Effect of Atmospheric Conditions on Coverage of Fogger Applications in a Desert Surface Boundary Layer

    Science.gov (United States)

    2012-01-01

    the ultra-low volume (cold fogger) applicator used. Keywords. Aerosol plume, Atmospheric stability, Droplet dispersion, Lidar, Sand flies . eishmaniasis...a vector-borne disease caused by sand flies , is a persistent health threat to U.S. mil- itary personnel deployed to Iraq, Afghanistan, and...ULV) spray have been ineffective for sand flies control (Aronson, 2007). The ineffectiveness of these techniques is likely due to the nighttime

  1. Machine-Learning Techniques for the Determination of Attrition of Forces Due to Atmospheric Conditions

    Science.gov (United States)

    2018-02-01

    ARL-TR-8304 ● FEB 2018 US Army Research Laboratory Machine -Learning Techniques for the Determination of Attrition of Forces Due...when it is no longer needed. Do not return it to the originator. ARL-TR-8304 ● FEB 2018 US Army Research Laboratory Machine ...October 2015–September 2017 4. TITLE AND SUBTITLE Machine -Learning Techniques for the Determination of Attrition of Forces Due to Atmospheric

  2. SHARC, a model for calculating atmospheric and infrared radiation under non-equilibrium conditions

    Science.gov (United States)

    Sundberg, R. L.; Duff, J. W.; Gruninger, J. H.; Bernstein, L. S.; Sharma, R. D.

    1994-01-01

    A new computer model, SHARC, has been developed by the Air Force for calculating high-altitude atmospheric IR radiance and transmittance spectra with a resolution of better than 1/cm. Comprehensive coverage of the 2 to 40 microns (250/cm to 5,000/cm) wavelength region is provided for arbitrary lines of sight in the 50-300 km altitude regime. SHARC accounts for the deviation from local thermodynamic equilibrium (LTE) in vibrational state populations by explicitly modeling the detailed production, loss, and energy transfer process among the important molecular vibrational states. The calculated vibrational populations are found to be similar to those obtained from other non-LTE codes. The radiation transport algorithm is based on a single-line equivalent width approximation along with a statistical correction for line overlap. This approach is reasonably accurate for most applications and is roughly two orders of magnitude faster than the traditional LBL methods which explicitly integrate over individual line shapes. In addition to quiescent atmospheric processes, this model calculates the auroral production and excitation of CO2, NO, and NO(+) in localized regions of the atmosphere. Illustrative comparisons of SHARC predictions to other models and to data from the CIRRIS, SPIRE, and FWI field experiments are presented.

  3. SHARC, a model for calculating atmospheric infrared radiation under non-equilibrium conditions

    Science.gov (United States)

    Sundberg, R. L.; Duff, J. W.; Gruninger, J. H.; Bernstein, L. S.; Matthew, M. W.; Adler-Golden, S. M.; Robertson, D. C.; Sharma, R. D.; Brown, J. H.; Healey, R. J.

    A new computer model, SHARC, has been developed by the U.S. Air Force for calculating high-altitude atmospheric IR radiance and transmittance spectra with a resolution of better than 1 cm 4. Comprehensive coverage of the 2 to 40 μm (250 to 5,000 cm-1) wavelength region is provided for arbitrary lines of sight in the 50-300 km altitude regime. SHARC accounts for the deviation from local thermodynamic equilibrium (LTE) in state populations by explicitly modeling the detailed production, loss, and energy transfer processes among the contributing molecular vibrational states. The calculated vibrational populations are found to be similar to those obtained from other non-LTE codes. The radiation transport algorithm is based on a single-line equivalent width approximation along with a statistical correction for line overlap. This approach calculates LOS radiance values which are accurate to ±10% and is roughly two orders of magnitude faster than the traditional LBL methods which explicitly integrate over individual line shapes. In addition to quiescent atmospheric processes, this model calculates the auroral production and excitation of CO2, NO, and NO+ in localized regions of the atmosphere. Illustrative comparisons of SHARC predictions to other models and to data from the CIRRIS, SPIRE and FWI field experiments are presented.

  4. Review Article: Atmospheric conditions inducing extreme precipitation over the eastern and western Mediterranean

    Science.gov (United States)

    Dayan, U.; Nissen, K.; Ulbrich, U.

    2015-11-01

    This review discusses published studies of heavy rainfall events over the Mediterranean Basin, combining them in a more general picture of the dynamic and thermodynamic factors and processes that produce heavy rain storms. It distinguishes the western and eastern Mediterranean in order to point out specific regional peculiarities. The crucial moisture for developing intensive convection over these regions can be originated not only from the adjacent Mediterranean Sea but also from distant upwind sources. Transport from remote sources is usually in the mid-tropospheric layers and associated with specific features and patterns of the larger-scale circulations. The synoptic systems (tropical and extratropical) that account for most of the major extreme precipitation events and the coupling of circulation and extreme rainfall patterns are presented. Heavy rainfall over the Mediterranean Basin is caused at times in concert by several atmospheric processes working at different atmospheric scales, such as local convection, upper synoptic-scale-level troughs, and mesoscale convective systems. Under tropical air-mass intrusions, convection generated by static instability seems to play a more important role than synoptic-scale vertical motions. Locally, the occurrence of torrential rains and their intensity is dependent on factors such as temperature profiles and implied instability, atmospheric moisture, and lower-level convergence.

  5. Thermal evolution of an early magma ocean in interaction with the atmosphere: conditions for the condensation of a water ocean

    Directory of Open Access Journals (Sweden)

    Lebrun T.

    2014-02-01

    Full Text Available The thermal evolution of magma oceans produced by collision with giant impactors late in accretion is xpected to depend on the composition and structure of the atmosphere through the greenhouse effect of CO2 and H2O released from the magma during its crystallization. We developed a 1D parameterized convection model of a magma ocean coupled with a 1D radiative convective model of the atmosphere. We conducted a parametric study and described the influences of some important parameters such as the Sun-planet distance. Our results suggest that a steam atmosphere delays the end of the magma ocean phase by typically 1 Myr. Water vapor condenses to an ocean after 0.1 Myr, 1.5 Myr and 10 Myr for, respectively, Mars, Earth and Venus. This time would be virtually infinite for an Earth-sized planet located at less than 0.66 AU from the Sun. So there are conditions such as no water ocean is formed on Venus. Moreover, for Mars and Earth, water ocean formation time scales are shorter than typical time gaps between major impacts. This implies that successive water oceans may have developed during accretion, making easier the loss of their atmospheres by impact erosion.

  6. The influence of atmospheric conditions on the leakage current of ceramic insulators on the Colombian Caribbean coast.

    Science.gov (United States)

    Castillo Sierra, Rafael; Oviedo-Trespalacios, Oscar; Candelo, John E; Soto, Jose D

    2015-02-01

    The contamination of electrical insulators is one of the major contributors to the risk of operation outages in electrical substations, especially in coastal zones with high salinity levels and atmospheric pollution. By using the measurement of leakage-currents, which is one of the main indicators of contamination in insulators, this work seeks to the determine the correlation with climatic variables, such as ambient temperature, relative humidity, solar irradiance, atmospheric pressure and wind speed and direction. The results obtained provide an input to the behaviour of the leakage current under atmospheric conditions that are particular to the Caribbean coast of Colombia. Spearman's rank correlation coefficients and principal component analysis are utilised to determine the significant relationships among the different variables under consideration. The necessary information for the study was obtained via historical databases of both atmospheric variables and the leakage current measured in over a period of 1 year in a 220-kV potential transformer insulator. We identified the influencing factors of temperature, humidity, radiation, wind speed and direction on the magnitude of the leakage current as the most relevant.

  7. Beam wandering statistics of twin thin laser beam propagation under generalized atmospheric conditions.

    Science.gov (United States)

    Pérez, Darío G; Funes, Gustavo

    2012-12-03

    Under the Geometrics Optics approximation is possible to estimate the covariance between the displacements of two thin beams after they have propagated through a turbulent medium. Previous works have concentrated in long propagation distances to provide models for the wandering statistics. These models are useful when the separation between beams is smaller than the propagation path-regardless of the characteristics scales of the turbulence. In this work we give a complete model for these covariances, behavior introducing absolute limits to the validity of former approximations. Moreover, these generalizations are established for non-Kolmogorov atmospheric models.

  8. Improvement in Simulation of Eurasian Winter Climate Variability with a Realistic Arctic Sea Ice Condition in an Atmospheric GCM

    Science.gov (United States)

    Lim, Young-Kwon; Ham, Yoo-Geun; Jeong, Jee-Hoon; Kug, Jong-Seong

    2012-01-01

    The present study investigates how much a realistic Arctic sea ice condition can contribute to improve simulation of the winter climate variation over the Eurasia region. Model experiments are set up using different sea ice boundary conditions over the past 24 years (i.e., 1988-2011). One is an atmospheric model inter-comparison (AMIP) type of run forced with observed sea-surface temperature (SST), sea ice, and greenhouse gases (referred to as Exp RSI), and the other is the same as Exp RSI except for the sea ice forcing, which is a repeating climatological annual cycle (referred to as Exp CSI). Results show that Exp RSI produces the observed dominant pattern of Eurasian winter temperatures and their interannual variation better than Exp CSI (correlation difference up to approx. 0.3). Exp RSI captures the observed strong relationship between the sea ice concentration near the Barents and Kara seas and the temperature anomaly across Eurasia, including northeastern Asia, which is not well captured in Exp CSI. Lagged atmospheric responses to sea ice retreat are examined using observations to understand atmospheric processes for the Eurasian cooling response including the Arctic temperature increase, sea-level pressure increase, upper-level jet weakening and cold air outbreak toward the mid-latitude. The reproducibility of these lagged responses by Exp RSI is also evaluated.

  9. Optimization and improvement of stable processing condition by attaching additional masses for milling of thin-walled workpiece

    Science.gov (United States)

    Wan, Min; Dang, Xue-Bin; Zhang, Wei-Hong; Yang, Yun

    2018-03-01

    Light weight is the main design requirement for minimizing costs or fuel consumption in mechanical equipments, and it, together with the material removal rate (MRR) requirement, also brings an important source of chatter, which still remains as an essential phenomenon to be suppressed in the future. This paper investigates the stable cutting region optimization problems in milling of structures with low rigidity. An effective method is proposed to improve the chatter stability by attaching appropriate additional masses to the workpiece, and thorough studies are also carried out to reveal the effect of additional masses on chatter stability. An efficient method based on structural dynamic modification scheme is developed to calculate the varying dynamics of the in-process workpiece under the combined effect of additional masses and material removal during milling process. Typical characteristic of this method lies in that only one modal analysis is needed to be performed on the finite element (FE) model of the initial workpiece, and the mode shape and natural frequency of the workpiece after attaching additional masses and removing material at each tool position can be calculated without the requirement to rebuild the FE model of the in-process workpiece. Based on the proposed dynamic modification scheme, an optimization algorithm is established to obtain the optimized combination of additional masses and the suitable stable cutting region for the achievement of maximum MRR. The proposed method is verified by milling process of a set of thin-walled workpieces, and comparisons of predictions and measurements show the validity and reliability.

  10. Organic and inorganic markers and stable C-, N-isotopic compositions of tropical coastal aerosols from megacity Mumbai: sources of organic aerosols and atmospheric processing

    Directory of Open Access Journals (Sweden)

    S. G. Aggarwal

    2013-05-01

    Full Text Available To better understand the sources of PM10 samples in Mumbai, India, aerosol chemical composition, i.e., total carbon (TC, organic carbon (OC, elemental carbon (EC, water-soluble organic carbon (WSOC, and inorganic ions were studied together with specific markers such as methanesulfonate (MSA, oxalic acid (C2, azelaic acid (C9, and levoglucosan. The results revealed that biofuel/biomass burning and fossil fuel combustion are the major sources of the Mumbai aerosols. Nitrogen-isotopic (δ15N composition of aerosol total nitrogen, which ranged from 18.1 to 25.4‰, also suggests that biofuel/biomass burning is a predominate source in both the summer and winter seasons. Aerosol mass concentrations of major species increased 3–4 times in winter compared to summer, indicating enhanced emission from these sources in the winter season. Photochemical production tracers, C2 diacid and nssSO42−, do not show diurnal changes. Concentrations of C2 diacid and WSOC show a strong correlation (r2 = 0.95. In addition, WSOC to OC (or TC ratios remain almost constant for daytime (0.37 ± 0.06 (0.28 ± 0.04 and nighttime (0.38 ± 0.07 (0.28 ± 0.06, suggesting that mixing of fresh secondary organic aerosols is not significant and the Mumbai aerosols are photochemically well processed. Concentrations of MSA and C9 diacid present a positive correlation (r2 = 0.75, indicating a marine influence on Mumbai aerosols in addition to local/regional influence. Backward air mass trajectory analyses further suggested that the Mumbai aerosols are largely influenced by long-range continental and regional transport. Stable C-isotopic ratios (δ13C of TC ranged from −27.0 to −25.4‰, with slightly lower average (−26.5 ± 0.3‰ in summer than in winter (−25.9 ± 0.3‰. Positive correlation between WSOC/TC ratios and δ13C values suggested that the relative increment in 13C of wintertime TC may be caused by prolonged photochemical processing of organic

  11. A computational study of particulate emissions from an open pit quarry under neutral atmospheric conditions

    Science.gov (United States)

    Silvester, S. A.; Lowndes, I. S.; Hargreaves, D. M.

    2009-12-01

    The extraction of minerals from surface mines and quarries can produce significant fugitive dust emissions as a result of site activities such as blasting, road haulage, loading, crushing and stockpiling. If uncontrolled, these emissions can present serious environmental, health, safety and operational issues impacting both site personnel and the wider community. The dispersion of pollutant emissions within the atmosphere is principally determined by the background wind systems characterized by the atmospheric boundary layer (ABL). This paper presents an overview of the construction and solution of a computational fluid dynamics (CFD) model to replicate the development of the internal ventilation regime within a surface quarry excavation due to the presence of a neutral ABL above this excavation. This model was then used to study the dispersion and deposition of fugitive mineral dust particles generated during rock blasting operations. The paths of the mineral particles were modelled using Lagrangian particle tracking. Particles of four size fractions were released from five blast locations for eight different wind directions. The study concluded that dependent on the location of the bench blast within the quarry and the direction of the wind, a mass fraction of between 0.3 and 0.6 of the emitted mineral particles was retained within the quarry. The retention was largest when the distance from the blast location to the downwind pit boundary was greatest.

  12. Comparison of toluene removal in air at atmospheric conditions by different corona discharges.

    Science.gov (United States)

    Schiorlin, Milko; Marotta, Ester; Rea, Massimo; Paradisi, Cristina

    2009-12-15

    Different types of corona discharges, produced by DC of either polarity (+/-DC) and positive pulsed (+pulsed) high voltages, were applied to the removal of toluene via oxidation in air at room temperature and atmospheric pressure. Mechanistic insight was obtained through comparison of the three different corona regimes with regard to process efficiency, products, response to the presence of humidity and, for DC coronas, current/voltage characteristics coupled with ion analysis. Process efficiency increases in the order +DC Atmospheric Pressure Chemical Ionization-Mass Spectrometry), provides a powerful rationale for interpreting current/voltage characteristics of DC coronas. All experimental findings are consistent with the proposal that in the case of +DC corona toluene oxidation is initiated by reactions with ions (O(2)(+*), H(3)O(+) and their hydrates, NO(+)) both in dry as well as in humid air. In contrast, with -DC no evidence is found for any significant reaction of toluene with negative ions. It is also concluded that in humid air OH radicals are involved in the initial stage of toluene oxidation induced both by -DC and +pulsed corona.

  13. MPAS Atmospheric Boundary Layer Simulation under Selected Stability Conditions: Evaluation Using the SWIFT Datasen

    Energy Technology Data Exchange (ETDEWEB)

    Kotamarthi, V. Rao [Argonne National Lab. (ANL), Argonne, IL (United States); Feng, Yan [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-10-12

    Modeling the transition from mesoscale to microscale is necessary in order to model different processes that affect a wind farm and to develop forecasting tools that operate at the farm scale. The mesoscale-to-microscale coupling (MMC) project is an A2e (Atmosphere-toelectrons) coordinated activity for developing modeling capabilities at the wind farm scale. By moving the focus of the research from a single wind turbine to the collection of turbines that comprise a wind farm, A2e extends the range of spatial and timescales that need representation in a model from tens of meters to hundreds of kilometers and timescales from a few seconds to days (Bokharaie et al. 2016). In the atmosphere, these scales are represented by mesoscale-tomicroscale models. The modeling available at these scales has differed in its representation of various physical processes. The MMC group is responsible for evaluating existing models at these scales and recommending a set of options for coupling the mesoscale and microscale with the best-performing models. The group was organized in 2015 and will explore options for coupling strategies with real-world test problems in fiscal year (FY) 2017. The model of choice for this exercise is WRF (Weather Research Forecasting) for mesoscale and WRF-LES (Large Eddy Simulation) for microscale simulations. The MPAS (Model Prediction Across Scales) variable mesh model that can be continuously refined; it has dynamic core and physics options adopted from WRF, which offer an alternative platform for modeling the mesoscale.

  14. Under What Conditions Can Equilibrium Gas-Particle Partitioning Be Expected to Hold in the Atmosphere?

    Science.gov (United States)

    Mai, Huajun; Shiraiwa, Manabu; Flagan, Richard C; Seinfeld, John H

    2015-10-06

    The prevailing treatment of secondary organic aerosol formation in atmospheric models is based on the assumption of instantaneous gas-particle equilibrium for the condensing species, yet compelling experimental evidence indicates that organic aerosols can exhibit the properties of highly viscous, semisolid particles, for which gas-particle equilibrium may be achieved slowly. The approach to gas-particle equilibrium partitioning is controlled by gas-phase diffusion, interfacial transport, and particle-phase diffusion. Here we evaluate the controlling processes and the time scale to achieve gas-particle equilibrium as a function of the volatility of the condensing species, its surface accommodation coefficient, and its particle-phase diffusivity. For particles in the size range of typical atmospheric organic aerosols (∼50-500 nm), the time scale to establish gas-particle equilibrium is generally governed either by interfacial accommodation or particle-phase diffusion. The rate of approach to equilibrium varies, depending on whether the bulk vapor concentration is constant, typical of an open system, or decreasing as a result of condensation into the particles, typical of a closed system.

  15. Effect of Light Intensities and Atmospheric Gas Conditions on Biohydrogen Production of Microalgae Isolated from Fisheries Wastewater

    Directory of Open Access Journals (Sweden)

    Mujalin Pholchan

    2017-06-01

    Full Text Available Recently, the fishery farming industry has been developed rapidly due to increasing demand and consumption as well as the depletion of wild fish resources. Production processes in the industry usually generate large amounts of wastewater containing high nutrients, posing a threat to downstream water. However, phytoplankton removal techniques commonly used to counteract the threat, though appearing to have low efficiency, are timeconsuming and less sustainable. Microalgae are photosynthetic microorganisms that convert solar energy into hydrogen. Using the isolated algae from fish farms as a source of renewable energy production could be a promising choice for handling fisheries wastewater in a more efficient manner. However, hydrogen production processes from algae still need more studies as their efficiencies vary between algae species and growth factors. In this work, the efficiency of hydrogen production from Scenedesmus accuminatus and Arthrospira platensis harvested from fish farms under three different light intensity conditions and three atmospheric gas conditions was determined. The results showed that the best conditions for hydrogen production from both species included 24 h darkness and carbon dioxide addition. Under the atmospheric gas combination of 99% argon and 1% carbon dioxide, S. accuminatus could produce hydrogen gas as high as 0.572 mol H2/mgCh h within 12 h, while the highest hydrogen production (0.348 mol H2/mgCh h obtained from A. platensis was found under the atmospheric gas mixture of 98% argon and 2% carbon dioxide. Interestingly, S. accuminatus appeared to produce more hydrogen than A. platensis under the same conditions.

  16. Factors controlling stable isotope composition of precipitation in arid conditions: an observation network in the Tianshan Mountains, central Asia

    Directory of Open Access Journals (Sweden)

    Shengjie Wang

    2016-02-01

    Full Text Available Approximately one-third of the Earth's arid areas are distributed across central Asia. The stable isotope composition of precipitation in this region is affected by its aridity, therefore subject to high evaporation and low precipitation amount. To investigate the factors controlling stable water isotopes in precipitation in arid central Asia, an observation network was established around the Tianshan Mountains in 2012. Based on the 1052 event-based precipitation samples collected at 23 stations during 2012–2013, the spatial distribution and seasonal variation of δD and δ18O in precipitation were investigated. The values of δD and δ18O are relatively more enriched in the rainfall dominant summer months (from April to October and depleted in the drier winter months (from November to March with low D-excess due to subcloud evaporation observed at many of the driest low elevation stations. The local meteoric water line (LMWL was calculated to be δD=7.36δ18O – 0.50 (r2=0.97, p<0.01 based on the event-based samples, and δD=7.60δ18O+2.66 (r2=0.98, p<0.01 based on the monthly precipitation-weighted values. In winter, the data indicate an isotopic rain shadow effect whereby rainout leads to depletion of precipitation in the most arid region to the south of the Tianshan Mountains. The values of δ18O significantly correlate with air temperature for each station, and the best-fit equation is established as δ18O=0.78T – 16.01 (r2=0.73, p<0.01. Using daily air temperature and precipitation derived from a 0.5° (latitude×0.5° (longitude gridded data set, an isoscape of δ18O in precipitation was produced based on this observed temperature effect.

  17. Fluidized bed pyrolysis of bitumen-impregnated sandstone at sub-atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, J.V.; Deo, M.D.; Hanson, F.V.

    1993-01-01

    A 15.2 cm diameter fluidized bed reactor was designed, built, and operated to study the pyrolysis of oil sands at pressures slightly less than atmospheric. Fluidizing gas flow through the reactor was caused by reducing the pressure above the bed with a gas pump operating in the vacuum mode. Pyrolysis energy was supplied by a propane burner, and the hot propane combustion gases were used for fluidization. The fluidized bed pyrolysis at reduced pressure using combustion gases allowed the reactor to be operated at significantly lower temperatures than previously reported. At 450[degree], over 80% of the bitumen fed was recovered as a liquid product, and the spent sand contained less than 1% coke. The liquid product recovery system, by design, yielded three liquid streams with distinctly different properties.

  18. Fluidized bed pyrolysis of bitumen-impregnated sandstone at sub-atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, J.V.; Deo, M.D.; Hanson, F.V.

    1993-03-01

    A 15.2 cm diameter fluidized bed reactor was designed, built, and operated to study the pyrolysis of oil sands at pressures slightly less than atmospheric. Fluidizing gas flow through the reactor was caused by reducing the pressure above the bed with a gas pump operating in the vacuum mode. Pyrolysis energy was supplied by a propane burner, and the hot propane combustion gases were used for fluidization. The fluidized bed pyrolysis at reduced pressure using combustion gases allowed the reactor to be operated at significantly lower temperatures than previously reported. At 450{degree}, over 80% of the bitumen fed was recovered as a liquid product, and the spent sand contained less than 1% coke. The liquid product recovery system, by design, yielded three liquid streams with distinctly different properties.

  19. Muscodor albus Volatiles Control Toxigenic Fungi under Controlled Atmosphere (CA Storage Conditions

    Directory of Open Access Journals (Sweden)

    Gordon Braun

    2012-11-01

    Full Text Available Muscodor albus, a biofumigant fungus, has the potential to control post-harvest pathogens in storage. It has been shown to produce over 20 volatile compounds with fungicidal, bactericidal and insecticidal properties. However, M. albus is a warm climate endophyte, and its biofumigant activity is significantly inhibited at temperatures below 5 °C. Conidia of seven mycotoxin producing fungi, Aspergillus carbonarius, A. flavus, A. niger, A. ochraceus, Penicillium verrucosum, Fusarium culmorum and F. graminearum, were killed or prevented from germinating by exposure to volatiles from 2 g M. albus-colonized rye grain per L of headspace in sealed glass jars for 24 h at 20 °C. Two major volatiles of M. albus, isobutyric acid (IBA and 2-methyl-1-butanol (2MB at 50 µL/L and 100 µL/L, respectively, gave differential control of the seven fungi when applied individually at 20 °C. When the fungi were exposed to both IBA and 2MB together, an average of 94% of the conidia were killed or suppressed. In a factorial experiment with controlled atmosphere storage (CA at 3 °C and 72 h exposure to four concentrations of IBA and 2MB combinations, 50 µL/L IBA plus 100 µL/L 2MB killed or suppressed germination of the conidia of all seven fungi. Controlled atmosphere had no significant effect on conidial viability or volatile efficacy. Major volatiles of M. albus may have significant potential to control plant pathogens in either ambient air or CA storage at temperatures below 5 °C. However, combinations of volatiles may be required to provide a broader spectrum of control than individual volatiles.

  20. A modified surface-resistance approach for representing bare-soil evaporation: wind tunnel experiments under various atmospheric conditions

    International Nuclear Information System (INIS)

    Yamanaka, T.; Takeda, A.; Sugita, F.

    1997-01-01

    A physically based (i.e., nonempirical) representation of surface-moisture availability is proposed, and its applicability is investigated. This method is based on the surface-resistance approaches, and it uses the depth of evaporating surface rather than the water content of the surface soil as the determining factor of surface-moisture availability. A simple energy-balance model including this representation is developed and tested against wind tunnel experiments under various atmospheric conditions. This model can estimate not only the latent heat flux but also the depth of the evaporating surface simultaneously by solving the inverse problem of energy balance at both the soil surface and the evaporating surface. It was found that the depth of the evaporating surface and the latent heat flux estimated by the model agreed well with those observed. The agreements were commonly found out under different atmospheric conditions. The only limitation of this representation is that it is not valid under conditions of drastic change in the radiation input, owing to the influence of transient phase transition of water in the dry surface layer. The main advantage of the approach proposed is that it can determine the surface moisture availability on the basis of the basic properties of soils instead of empirical fitting, although further investigations on its practical use are needed

  1. Evaluation of air gap membrane distillation process running under sub-atmospheric conditions: Experimental and simulation studies

    KAUST Repository

    Alsaadi, Ahmad S.

    2015-04-16

    The importance of removing non-condensable gases from air gap membrane distillation (AGMD) modules in improving the water vapor flux is presented in this paper. Additionally, a previously developed AGMD mathematical model is used to predict to the degree of flux enhancement under sub-atmospheric pressure conditions. Since the mathematical model prediction is expected to be very sensitive to membrane distillation (MD) membrane resistance when the mass diffusion resistance is eliminated, the permeability of the membrane was carefully measured with two different methods (gas permeance test and vacuum MD permeability test). The mathematical model prediction was found to highly agree with the experimental data, which showed that the removal of non-condensable gases increased the flux by more than three-fold when the gap pressure was maintained at the saturation pressure of the feed temperature. The importance of staging the sub-atmospheric AGMD process and how this could give better control over the gap pressure as the feed temperature decreases are also highlighted in this paper. The effect of staging on the sub-atmospheric AGMD flux and its relation to membrane capital cost are briefly discussed.

  2. Impacts of Boundary Conditions on the Simulation of Atmospheric Fields Using RegCM4 over CORDEX East Asia

    Directory of Open Access Journals (Sweden)

    Myoung Seok Suh

    2015-06-01

    Full Text Available The impacts of boundary conditions (BCs on simulations of RegCM4 for mid-to-upper atmospheric fields over the CORDEX (COordinated Regional Downscaling EXperiment East Asia domain were investigated using two datasets from integrations over 20 years (1989–2008 with two BCs (ERA and R2. The two datasets showed large differences for the atmospheric variables regardless of the geographic locations, heights, and seasons. The ERA dataset at 850 hPa displayed stronger northerly winds in the western Pacific Ocean, colder temperatures around northern India, and higher relative humidity compared with the R2 dataset during summer. The large differences in the BCs resulted in the significantly different simulations of RegCM4 in both surface and atmospheric variables. The temperatures and wind simulated at 850 hPa with the ERA dataset were warmer and stronger, respectively, than those simulated with the R2 dataset during summer. In addition, RegCM4 with the ERA dataset as a BC generally simulated a stronger southerly wind at 850 hPa over eastern China and more unstable environments than with the R2 dataset, and accordingly generated more precipitation over the eastern part of the domain. Contrary to the forcing data, the trends of simulated relative humidity and the mixing ratios from the two different BCs showed similar patterns irrespective of height and season. The significant impacts of the BCs on the simulation results indicate the importance of BCs in regional climate simulations.

  3. Storage quality of shelled green peas under modified atmosphere packaging at different storage conditions.

    Science.gov (United States)

    Anurag, Rahul K; Manjunatha, M; Jha, Shyam Narayan; Kumari, Leena

    2016-03-01

    Storage quality of shelled green peas (Pisum sativum var. sativum L) was investigated under modified atmosphere packaging (MAP: perforated and non perforated) compared to unsealed samples, respectively, at T1 (4 ± 1 °C and 94 ± 2 % RH) and T2 (10 ± 1 °C and 90 ± 2 % RH) for each sample and during period of storage (8, 16 and 24 days). Modified atmosphere (MA) was created using low density polyethylene (LDPE) film packages having 107 μm of film thickness and package size of 0.022 m(2). Quality parameters viz., weight loss (WL), total phenolic content (TPC), instrumental colour, ascorbic acid (AA) and sensory characteristics were evaluated during storage period. Weight loss was in the range of 0.18 to 3.54 (zero perforation at T1), 0.21 to 6.48(unsealed samples at T2) and 0.31 to 9.64 % (zero perforation at T1) after 8, 16 and 24 days of storage, respectively. Total phenolic content significantly increased to 102.47-161.54 mg/100 g from an initial value of 91.53 mg/100 g for all the samples and treatments studied. The MAP non perforated sample stored at T2 recorded maximum Hunter 'L' and '-a' colour values than all other samples. A significant decrease in AA content was observed in all the samples with maximum loss (53.77 %) in unsealed sample stored at T2, whereas MAP (3 perforations) sample stored at T1 retained maximum AA (90.50 %). Sensory quality analysis revealed that MAP (3 perforations) sample stored at T1 was in acceptable quality, with good appearance and overall acceptance. The study shows that shelled green peas can be stored in MAP with 3 perforations (0.4 mm dia) in the temperature range of 4 to 10 °C and 90-94 % RH to extend shelf life with marketable quality for 24 days.

  4. Corrosion mechanism of model zinc-magnesium alloys in atmospheric conditions

    International Nuclear Information System (INIS)

    Prosek, T.; Nazarov, A.; Bexell, U.; Thierry, D.; Serak, J.

    2008-01-01

    Recently, superior corrosion properties of zinc coatings alloyed with magnesium have been reported. Corrosion behaviour of model zinc-magnesium alloys was studied to understand better the protective mechanism of magnesium in zinc. Alloys containing from 1 to 32 wt.% magnesium, pure zinc, and pure magnesium were contaminated with sodium chloride and exposed to humid air for 28 days. Composition of corrosion products was analyzed using infrared spectroscopy (FTIR), ion chromatography (IC), and Auger electron spectroscopy (AES). The exposure tests were completed with scanning Kelvin probe (SKP) and electrochemical measurements. Weight loss of ZnMg alloys with 1-16 wt.% magnesium was lower than that of pure zinc. Up to 10-fold drop in weight loss was found for materials with 4-8 wt.% Mg in the structure. The improved corrosion stability of ZnMg alloys was connected to the presence of an Mg-based film adjacent to the metal surface. It ensured stable passivity in chloride environment and limited the efficiency of oxygen reduction

  5. Influence of atmospheric conditions on the strength of unstabilized earthen constructions

    Directory of Open Access Journals (Sweden)

    Gerard Pierre

    2016-01-01

    Full Text Available Uniaxial compression tests and indirect tensile tests are performed on compacted clayey silt samples upon varying suctions in order to assess the influence of changes in the relative humidity conditions on the strength of unstabilized rammed earthen building materials. The results show that suction plays an important role on the strength of the material. Also the ability of the Belgian clayey silt to develop sufficient mechanical strength to be used as an unstabilized earthen construction material is demonstrated whatever the relative humidity conditions, excepted the fully water saturated state. The experimental data are interpreted in the context of unsaturated soil mechanics using the generalized effective stress concept. This constitutive framework allows defining a unified failure criterion predicting the strength of the earthen building material as a function of the environmental hygroscopic conditions.

  6. Atmospheric conditions of meso-scale convective systems over Colombia, during 1998 according to the mission TRMM and the re-analysis NCEP/NCAR

    International Nuclear Information System (INIS)

    Mejia, John Freddy; Poveda, German

    2005-01-01

    Diagnostics of prevalent atmospheric conditions during the life cycle of meso-scale convective systems (MCSs) over Colombia and the eastern tropical pacific are developed using satellite data from the tropical rainfall measuring mission (TRMM), and from the NCEP/NCAR reanalysis project. Atmospheric stability indices such as CAPE, CINE, LI, and equivalent potential temperature are quantified, as well as kinematical indices such as relative vertical vorticity and vertical wind shear. Atmospheric environments associated with MCS are studied for 1998; both as long-term means but also in terms of the seasonal cycle large-scale atmospheric indices are quantified for the most intense precipitation events within MCSs. Relationships between those indices are estimated, and atmospheric conditions are studied for the life cycle of MCSs, including antecedent and subsequent conditions surrounding MCSs activity

  7. Quality of Meat ( from Male Fallow Deer ( Packaged and Stored under Vacuum and Modified Atmosphere Conditions

    Directory of Open Access Journals (Sweden)

    N. Piaskowska

    2016-12-01

    Full Text Available This study evaluated the effect of vacuum and modified atmosphere (40% CO2+60% N2, MA packaging on the chemical composition, physicochemical properties and sensory attributes of chill-stored meat from 10 fallow deer (Dama dama bucks at 17 to 18 months of age. The animals were hunter-harvested in the forests of north-eastern Poland. During carcass dressing (48 to 54 h post mortem, both musculus longissimus muscles were cut out. Each muscle was divided into seven sections which were allocated to three groups: 0, A, and B. Samples 0 were immediately subjected to laboratory analyses. Samples A were vacuum-packaged, and samples B were packaged in MA. Packaged samples were stored for 7, 14, and 21 days at 2°C. The results of the present study showed that the evaluated packaging systems had no significant effect on the quality of fallow deer meat during chilled storage. However, vacuum-packaged meat samples were characterised by greater drip loss. Vacuum and MA packaging contributed to preserving the desired physicochemical properties and sensory attributes of meat during 21 days of storage. Regardless of the packaging method used, undesirable changes in the colour, water-holding capacity and juiciness of meat, accompanied by tenderness improvement, were observed during chilled storage.

  8. Prolonged silicon carbide integrated circuit operation in Venus surface atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Philip G. Neudeck

    2016-12-01

    Full Text Available The prolonged operation of semiconductor integrated circuits (ICs needed for long-duration exploration of the surface of Venus has proven insurmountably challenging to date due to the ∼ 460 °C, ∼ 9.4 MPa caustic environment. Past and planned Venus landers have been limited to a few hours of surface operation, even when IC electronics needed for basic lander operation are protected with heavily cumbersome pressure vessels and cooling measures. Here we demonstrate vastly longer (weeks electrical operation of two silicon carbide (4H-SiC junction field effect transistor (JFET ring oscillator ICs tested with chips directly exposed (no cooling and no protective chip packaging to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere. This represents more than 100-fold extension of demonstrated Venus environment electronics durability. With further technology maturation, such SiC IC electronics could drastically improve Venus lander designs and mission concepts, fundamentally enabling long-duration enhanced missions to the surface of Venus.

  9. ELF-VLF atmospheric waveforms under night-time ionospheric conditions

    Directory of Open Access Journals (Sweden)

    A. I. Sukhorukov

    1996-01-01

    Full Text Available Tweek atmospherics generated by lightning discharges and propagated in the night-time Earth-ionosphere waveguide, have often very pronounced dispersive features near the first few waveguide cut-off frequencies ( fcm~m\\dot{s} fc1, fc 1~1.6–1.9 kHz, m=1, 2, . . . , , being very extended in time, and have rather large amplitudes of oscillations with periods corresponding to the narrow vicinity of the cut-off frequencies. In this paper an analytical approach is developed to describe the waveform of distant tweeks. It is based on the solving of the Maxwell equations in two qualitatively different regions, whose changes are related in the first instance to the changes in the relative magnitudes of the displacement current and components of the conduction currents, and the following asymptotic matching of the solutions in the transitional region. The analytical night-time waveguide model accounts for both anisotropy and vertical inhomogeneity of the low ionosphere. The model is valid for upper ELF – lower VLF range and is well suitable for the analysis of the QTEm modes in the cut-off frequency regions, which determine the most important part of the tweek spectra and tweek amplitudes. The influence of the different ionospheric heights on the tweek characteristics is determined. The efficiency of the tweek generation by cloud-to-cloud discharge is also evaluated.

  10. Heterogeneous Reactions between Toluene and NO2 on Mineral Particles under Simulated Atmospheric Conditions.

    Science.gov (United States)

    Niu, Hejingying; Li, Kezhi; Chu, Biwu; Su, Wenkang; Li, Junhua

    2017-09-05

    Heterogeneous reactions between organic and inorganic gases with aerosols are important for the study of smog occurrence and development. In this study, heterogeneous reactions between toluene and NO 2 with three atmospheric mineral particles in the presence or absence of UV light were investigated. The three mineral particles were SiO 2 , α-Fe 2 O 3 , and BS (butlerite and szmolnokite). In a dark environment, benzaldehyde was produced on α-Fe 2 O 3 . For BS, nitrotoluene and benzaldehyde were obtained. No aromatic products were produced in the absence of NO 2 in the system. In the presence of UV irradiation, benzaldehyde was detected on the SiO 2 surface. Identical products were produced in the presence and absence of UV light over α-Fe 2 O 3 and BS. UV light promoted nitrite to nitrate on mineral particles surface. On the basisi of the X-ray photoelectron spectroscopy (XPS) results, a portion of BS was reduced from Fe 3+ to Fe 2+ with the adsorption of toluene or the reaction with toluene and NO 2 . Sulfate may play a key role in the generation of nitrotoluene on BS particles. From this research, the heterogeneous reactions between organic and inorganic gases with aerosols that occur during smog events will be better understood.

  11. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    International Nuclear Information System (INIS)

    Li, Ying; Manolache, Sorin; Qiu, Yiping; Sarmadi, Majid

    2016-01-01

    Graphical abstract: - Highlights: • The continuous ethanol flow technique can successfully modify ramie fiber surface with an increase in IFSS value up to 50%. • Response surface methodology was applied to design the plasma treatment parameters for ramie fiber modification. • The ethanol flow rate was the most influential treatment parameter in plasma modification process. - Abstract: In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  12. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [College of Material and Textile Engineering, Jiaxing University, Jiaxing 314033 (China); Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Manolache, Sorin [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); US Forest Products Laboratory, Madison, WI 53726 (United States); Qiu, Yiping, E-mail: ypqiu@dhu.edu.cn [College of Textiles, Donghua University, Shanghai 201620 (China); Sarmadi, Majid, E-mail: majidsar@wisc.edu [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2016-02-28

    Graphical abstract: - Highlights: • The continuous ethanol flow technique can successfully modify ramie fiber surface with an increase in IFSS value up to 50%. • Response surface methodology was applied to design the plasma treatment parameters for ramie fiber modification. • The ethanol flow rate was the most influential treatment parameter in plasma modification process. - Abstract: In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  13. Stable-isotope analysis of a combined nitrification-denitrification sustained by thermophilic methanotrophs under low-oxygen conditions

    NARCIS (Netherlands)

    Pel, R; Oldenhuis, R; Brand, W; Vos, A; Gottschal, JC; Zwart, KB

    To simulate growth conditions experienced by microbiota at O-2-limited interfaces of organic matter in compost, an experimental system capable of maintaining dual limitations of oxygen and carbon for extended periods, i.e., a pO(2)-auxostat, has been used. N-15 tracer studies on thermophilic (53

  14. Stable-isotope analysis of a combined nitrification- denitrification sustained by thermophilic methanotrophs under low-oxygen conditions

    NARCIS (Netherlands)

    Pel, R.; Oldenhuis, R.; Brand, W.; Vos, A.; Gottschal, J.C.; Zwart, K.B.

    1997-01-01

    To simulate growth conditions experienced by microbiota at O-2- limited interfaces of organic matter in compost, an experimental system capable of maintaining dual limitations of oxygen and carbon for extended periods, i.e., a pO(2)-auxostat, has been used. N-15 tracer studies on thermophilic (53

  15. Feasibility Study of PM Elimination by Silent Discharge Type of DPF under Room Temperature and Atmospheric Pressure Condition

    Science.gov (United States)

    Chuubachi, Minoru; Nagasawa, Takeshi

    This Silent Discharge type of DPF (Diesel Particulate Filter) has been studied for eliminating PM (Particulate Mater) we call it “SDeDPF”. Usually, exhaust gas temperature of diesel engines is under 200 or 250°C at normal city driving condition. Under that condition, generally PM is not bourn out in the normal ceramic DPF. This SDeDPF aims to remove PM electrically and chemically even at room temperature and atmospheric pressure continuously. Finally, in the basic lab test result, 95.6% reduction of PM has been verified by SDeDPF with a special MFS (Metal Fiber Sheet) for discharge electrode to reduce a back pressure, a special Turbulent Block for turbulent and slower velocity of exhaust gas, the 1mm gap between electrodes and an optimum total area of piled electrodes. Also, 98.1% reduction of PM could be designed by most suitable gap between electrodes.

  16. Preincubation of Penicillium commune conidia under modified atmosphere conditions: Influence on growth potential as determined by an impedimetric method

    DEFF Research Database (Denmark)

    Haasum, Iben; Nielsen, Per Væggemose

    1996-01-01

    The combined effect of preincubation time, relative humidity (r.h.), headspace carbon dioxide (CO2) and oxygen (O2) on subsequent growth potential of conidia from Penicillium commune was studied using Response Surface Modelling (RSM). Native conidia were preincubated under modified atmosphere...... conditions in sealed vials for 14, 35 and 56 d. Lag time and growth rates were determined using impedance microbiology on a Bactometer. Conidia survived and some swelling was observed during all experimental preincubation conditions. Regression analysis of the subsequent growth responses showed that relative...... humidity in the vials was the most significant factor affecting lag time of the conidia after preincubation for 14 and 35 d. Storage for 35 d extended lag times by 15 h when the level of r.h. was increased from 41% to 80%. After prolonged storage (56 d) r.h and CO2 levels elicited a significant effect...

  17. ELF-VLF atmospheric waveforms under night-time ionospheric conditions

    Directory of Open Access Journals (Sweden)

    A. I. Sukhorukov

    Full Text Available Tweek atmospherics generated by lightning discharges and propagated in the night-time Earth-ionosphere waveguide, have often very pronounced dispersive features near the first few waveguide cut-off frequencies ( fcm~mdot{s} fc1, fc 1~1.6–1.9 kHz, m=1, 2, . . . , , being very extended in time, and have rather large amplitudes of oscillations with periods corresponding to the narrow vicinity of the cut-off frequencies. In this paper an analytical approach is developed to describe the waveform of distant tweeks. It is based on the solving of the Maxwell equations in two qualitatively different regions, whose changes are related in the first instance to the changes in the relative magnitudes of the displacement current and components of the conduction currents, and the following asymptotic matching of the solutions in the transitional region. The analytical night-time waveguide model accounts for both anisotropy and vertical inhomogeneity of the low ionosphere. The model is valid for upper ELF – lower VLF range and is well suitable for the analysis of the QTEm modes in the cut-off frequency regions, which determine the most important part of the tweek spectra and tweek amplitudes. The influence of the different ionospheric heights on the tweek characteristics is determined. The efficiency of the tweek generation by cloud-to-cloud discharge is also evaluated.

  18. Characterization of the Enterobacteriaceae community that developed during storage of minced beef under aerobic or modified atmosphere packaging conditions.

    Science.gov (United States)

    Doulgeraki, Agapi I; Paramithiotis, Spiros; Nychas, George-John E

    2011-01-31

    The whole cell protein and macrorestriction analysis of DNA of Enterobacteriaceae isolates recovered from minced beef stored at 0, 5, 10 and 15 °C aerobically and under modified atmosphere packaging consisting of 40% CO(2)-30% O(2)-30% N(2) in the presence (MAP+) and absence (MAP-) of oregano essential oil were studied. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) profiles obtained from whole cell protein analysis of the Enterobacteriaceae isolates revealed seven groups. Moreover, application of a modified PFGE protocol with XbaI restriction, resulted into 19 different fingerprints. The Enterobacteriaceae community of fresh meat consisted of Serratia liquefaciens and Serratia proteamaculans. S. liquefaciens strain VK23 was the dominant isolate of Enterobacteriaceae for the most conditions adopted, except 10 °C and 15 °C under MAP + and 10 °C under MAP-. In the latter cases, Hafnia alvei represented the dominant fingerprint. Citrobacter freundii was recovered from minced beef stored aerobically, while H. alvei and Proteus vulgaris were recovered under MAP. Storage conditions affected the Enterobacteriaceae community; modified atmosphere packaging increased both species and strain diversity. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Modeling the impact of vapor thymol concentration, temperature, and modified atmosphere condition on growth behavior of Salmonella on raw shrimp.

    Science.gov (United States)

    Zhou, Siyuan; Sheen, Shiowshuh; Pang, Yu-Hsin; Liu, Linshu; Yam, Kit L

    2015-02-01

    Salmonella is a microorganism of concern on a global basis for raw shrimp. This research modeled the impact of vapor thymol concentration (0, 0.8, and 1.6 mg/liter), storage temperature (8, 12, and 16°C), and modified atmosphere condition (0.04 as in the natural atmosphere and 59.5% CO2) against the growth behavior of a Salmonella cocktail (six strains) on raw shrimp. Lag time (hour) and maximum growth rate (log CFU per gram per hour), chosen as two growth indicators, were obtained through DMFit software and then developed into polynomial as well as nonlinear modified secondary models (dimensional and/or dimensionless), consisting of two or even three impact factors in the equations. The models were validated, and results showed that the predictive values from both models demonstrated good matches to the observed experimental values, yet the prediction based on lag time was more accurate than maximum growth rate. The information will provide the food industry with insight into the potential safety risk of Salmonella growth on raw shrimp under stressed conditions.

  20. STATIC BALANCE MEASUREMENTS IN STABLE AND UNSTABLE CONDITIONS DO NOT DISCRIMINATE GROUPS OF YOUNG ADULTS ASSESSED BY THE FUNCTIONAL MOVEMENT SCREEN™ (FMS™).

    Science.gov (United States)

    Trindade, Matheus A; de Toledo, Aline Martins; Cardoso, Jefferson Rosa; Souza, Igor Eduardo; Dos Santos Mendes, Felipe Augusto; Santana, Luisiane A; Carregaro, Rodrigo Luiz

    2017-11-01

    The Functional Movement Screen™ (FMS™) has been the focus of recent research related to movement profiling and injury prediction. However, there is a paucity of studies examining the associations between physical performance tasks such as balance and the FMS™ screening system. The purpose of this study was to compare measures of static balance in stable and unstable conditions between different groups divided by FMS™ scores. A secondary purpose was to discern if balance indices discriminate the groups divided by FMS™ scores. Cross-sectional study. Fifty-seven physically active subjects (25 men and 32 women; mean age of 22.9 ± 3.1 yrs) participated. The outcome was unilateral stance balance indices, composed by: Anteroposterior Index; Medial-lateral Index, and Overall Balance Index in stable and unstable conditions, as provided by the Biodex balance platform. Subjects were dichotomized into two groups, according to a FMS™ cut-off score of 14: FMS1 (score > 14) and FMS2 (score ≤ 14). The independent Students t-test was used to verify differences in balance indices between FMS1 and FMS2 groups. A discriminant analysis was applied in order to identify which of the balance indices would adequately discriminate the FMS™ groups. Comparisons between FMS1 and FMS2 groups in the stable and unstable conditions demonstrated a higher unstable Anteroposterior index for FMS2 (p=0.017). No significant differences were found for other comparisons (p>0.05). The indices did not discriminate the FMS™ groups ( p  > 0.05). The balance indices adopted in this study were not useful as a parameter for identification and discrimination of healthy subjects assessed by the FMS™. 2c.

  1. Development of stable walking robot for accident condition monitoring on uneven floors in a nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Seog; Jang, You Hyun [Central Research Institute of Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)

    2017-04-15

    Even though the potential for an accident in nuclear power plants is very low, multiple emergency plans are necessary because the impact of such an accident to the public is enormous. One of these emergency plans involves a robotic system for investigating accidents under conditions of high radiation and contaminated air. To develop a robot suitable for operation in a nuclear power plant, we focused on eliminating the three major obstacles that challenge robots in such conditions: the disconnection of radio communication, falling on uneven floors, and loss of localization. To solve the radio problem, a Wi-Fi extender was used in radio shadow areas. To reinforce the walking, we developed two- and four-leg convertible walking, a floor adaptive foot, a roly-poly defensive falling design, and automatic standing recovery after falling methods were developed. To allow the robot to determine its location in the containment building, a bar code landmark reading method was chosen. When a severe accident occurs, this robot will be useful for accident condition monitoring. We also anticipate the robot can serve as a workman aid in a high radiation area during normal operations.

  2. Development of stable walking robot for accident condition monitoring on uneven floors in a nuclear power plant

    International Nuclear Information System (INIS)

    Kim, Jong Seog; Jang, You Hyun

    2017-01-01

    Even though the potential for an accident in nuclear power plants is very low, multiple emergency plans are necessary because the impact of such an accident to the public is enormous. One of these emergency plans involves a robotic system for investigating accidents under conditions of high radiation and contaminated air. To develop a robot suitable for operation in a nuclear power plant, we focused on eliminating the three major obstacles that challenge robots in such conditions: the disconnection of radio communication, falling on uneven floors, and loss of localization. To solve the radio problem, a Wi-Fi extender was used in radio shadow areas. To reinforce the walking, we developed two- and four-leg convertible walking, a floor adaptive foot, a roly-poly defensive falling design, and automatic standing recovery after falling methods were developed. To allow the robot to determine its location in the containment building, a bar code landmark reading method was chosen. When a severe accident occurs, this robot will be useful for accident condition monitoring. We also anticipate the robot can serve as a workman aid in a high radiation area during normal operations

  3. Development of Stable Walking Robot for Accident Condition Monitoring on Uneven Floors in a Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Jong Seog Kim

    2017-04-01

    Full Text Available Even though the potential for an accident in nuclear power plants is very low, multiple emergency plans are necessary because the impact of such an accident to the public is enormous. One of these emergency plans involves a robotic system for investigating accidents under conditions of high radiation and contaminated air. To develop a robot suitable for operation in a nuclear power plant, we focused on eliminating the three major obstacles that challenge robots in such conditions: the disconnection of radio communication, falling on uneven floors, and loss of localization. To solve the radio problem, a Wi-Fi extender was used in radio shadow areas. To reinforce the walking, we developed two- and four-leg convertible walking, a floor adaptive foot, a roly-poly defensive falling design, and automatic standing recovery after falling methods were developed. To allow the robot to determine its location in the containment building, a bar code landmark reading method was chosen. When a severe accident occurs, this robot will be useful for accident condition monitoring. We also anticipate the robot can serve as a workman aid in a high radiation area during normal operations.

  4. Kinetics of elementary steps in the reactions of atomic bromine with isoprene and 1,3-butadiene under atmospheric conditions.

    Science.gov (United States)

    Laine, Patrick L; Sohn, Yoon S; Nicovich, J Michael; McKee, Michael L; Wine, Paul H

    2012-06-21

    Laser flash photolysis of CF(2)Br(2) has been coupled with time-resolved detection of atomic bromine by resonance fluorescence spectroscopy to investigate the gas-phase kinetics of early elementary steps in the Br-initiated oxidations of isoprene (2-methyl-1,3-butadiene, Iso) and 1,3-butadiene (Bu) under atmospheric conditions. At T ≥ 526 K, measured rate coefficients for Br + isoprene are independent of pressure, suggesting that hydrogen transfer (1a) is the dominant reaction pathway. The following Arrhenius expression adequately describes all kinetic data at 526 K ≤ T ≤ 673 K: k(1a)(T) = (1.22 ± 0.57) × 10(-11) exp[(-2100 ± 280)/T] cm(3) molecule(-1) s(-1) (uncertainties are 2σ and represent precision of the Arrhenius parameters). At 271 K ≤ T ≤ 357 K, kinetic evidence for the reversible addition reactions Br + Iso ↔ Br-Iso (k(1b), k(-1b)) and Br + Bu ↔ Br-Bu (k(3b), k(-3b)) is observed. Analysis of the approach to equilibrium data allows the temperature- and pressure-dependent rate coefficients k(1b), k(-1b), k(3b), and k(-3b) to be evaluated. At atmospheric pressure, addition of Br to each conjugated diene occurs with a near-gas-kinetic rate coefficient. Equilibrium constants for the addition/dissociation reactions are obtained from k(1b)/k(-1b) and k(3b)/k(-3b), respectively. Combining the experimental equilibrium data with electronic structure calculations allows both second- and third-law analyses of thermochemistry to be carried out. The following thermochemical parameters for the addition reactions 1b and 3b at 0 and 298 K are obtained (units are kJ mol(-1) for Δ(r)H and J mol(-1) K(-1) for Δ(r)S; uncertainties are accuracy estimates at the 95% confidence level): Δ(r)H(0)(1b) = -66.6 ± 7.1, Δ(r)H(298)(1b) = -67.5 ± 6.6, and Δ(r)S(298)(3b) = -93 ± 16; Δ(r)H(0)(3b) = -62.4 ± 9.0, Δ(r)H(298)(3b) = -64.5 ± 8.5, and Δ(r)S(298)(3b) = -94 ± 20. Examination of the effect of added O(2) on Br kinetics under conditions where reversible

  5. Critical review: Copper runoff from outdoor copper surfaces at atmospheric conditions.

    Science.gov (United States)

    Hedberg, Yolanda S; Hedberg, Jonas F; Herting, Gunilla; Goidanich, Sara; Odnevall Wallinder, Inger

    2014-01-01

    This review on copper runoff dispersed from unsheltered naturally patinated copper used for roofing and facades summarizes and discusses influencing factors, available literature, and predictive models, and the importance of fate and speciation for environmental risk assessment. Copper runoff from outdoor surfaces is predominantly governed by electrochemical and chemical reactions and is highly dependent on given exposure conditions (size, inclination, geometry, degree of sheltering, and orientation), surface parameters (age, patina composition, and thickness), and site-specific environmental conditions (gaseous pollutants, chlorides, rainfall characteristics (amount, intensity, pH), wind direction, temperature, time of wetness, season). The corrosion rate cannot be used to assess the runoff rate. The extent of released copper varies largely between different rain events and is related to dry and wet periods, dry deposition prior to the rain event and prevailing rain and patina characteristics. Interpretation and use of copper runoff data for environmental risk assessment and management need therefore to consider site-specific factors and focus on average data of long-term studies (several years). Risk assessments require furthermore that changes in copper speciation, bioavailability aspects, and potential irreversible retention on solid surfaces are considered, factors that determine the environmental fate of copper runoff from outdoor surfaces.

  6. Evaluation the urban atmospheric conditions in different cities using comet and micronuclei assay in Tradescantia pallida.

    Science.gov (United States)

    Sposito, Juliana Caroline Vivian; Crispim, Bruno do Amaral; Romãn, Amanda Izadora; Mussury, Rosilda Mara; Pereira, Joelson Gonçalves; Seno, Leonardo Oliveira; Grisolia, Alexeia Barufatti

    2017-05-01

    In the present study, genotoxicity and mutagenicity were investigated in Tradescantia pallida exposed to vehicular traffic at different sites in a high-altitude tropical climate. During March, May, July, September, and November 2014, a comet assay and micronucleus bioassays were conducted on young inflorescences and leaves of T. pallida collected from twelve towns in the southern region of Mato Grosso do Sul with different amounts of vehicular traffic. Weather parameters (temperature, relative humidity and rainfall) were measured and vehicles were counted to determine traffic levels in each town. A higher frequency of genotoxic and mutagenic damage was observed in the municipality of Dourados. The highest frequency of genetic damage was observed in September and November according to both assays. Relative humidity and rainfall were inversely proportional to the frequency of genetic damage in T. pallida during the collection period. Based on these results, we conclude that the bioassays are efficient for assessing the effects of vehicular traffic in these towns with respect to weather conditions over time. These bioassays can be applied to identify risk areas, which are determined by climatic conditions and air pollutants released. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. A STUDY ON LEGIONELLA PNEUMOPHILA, WATER CHEMISTRY, AND ATMOSPHERIC CONDITIONS IN COOLING TOWERS AT THE SAVANNAH RIVER SITE

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.; Brigmon, R.

    2009-10-20

    elevated Legionella concentrations when the dew point temperature was high--a summertime occurrence. However, analysis of the three years of Legionella monitoring data of the 14 different SRS Cooling Towers demonstrated that elevated concentrations are observed at all temperatures and seasons. The objective of this study is to evaluate the ecology of L. pneumophila including serogroups and population densities, chemical, and atmospheric data, on cooling towers at SRS to determine whether relationships exist among water chemistry, and atmospheric conditions. The goal is to more fully understand the conditions which inhibit or encourage L. pneumophila growth and supply this data and associated recommendations to SRS Cooling Tower personnel for improved management of operation. Hopefully this information could then be used to help control L. pneumophila growth more effectively in SRS cooling tower water.

  8. Influence of environmental factors on dissolved nitrate stable isotopes under denitrifying conditions - carbon sources and water isotopes

    Science.gov (United States)

    Wunderlich, A.; Meckenstock, R.; Einsiedl, F.

    2012-04-01

    Stable isotopes in dissolved nitrate are regularly used to identify sources of nitrate contamination in aquifers and water bodies. A dual isotope plot of 15N and 18O in nitrate can provide good evidence of the origin of such pollution as various sources have different isotopic signatures. Microbial denitrification changes both isotopic values by removing nitrate with lighter isotopes first, thereby increasing δ18O as well as δ15N. This change can distort the determination of sources but also has the potential to be used to identify and quantify microbial denitrification. Previous studies found a wide range of enrichment factors (ɛ) that did not allow conclusions towards the extent of microbial denitrification. However, it was found that during denitrification at each respective field site or laboratory experiment, there was a constant ratio in increase of the values of δ18O in relation to δ15N. That ratio was, however, not constant across field sites and the values published range from below 0.5 to more than 1.0. The reasons for these variations in enrichment factors and relative enrichment of oxygen compared to nitrogen are yet unknown. We conducted microcosm experiments with three different bacterial species to elucidate possible influences of environmental factors on these parameters. As a result we conclude that the type of carbon source available to denitrifying bacteria can play a role in the value of the enrichment factors, but not in the relative enrichment of the two isotopes. Specifically we found that complex hydrocarbons (toluene, benzoate) produce significantly different enrichment factors in nitrate than a simple hydrocarbon substrate (acetate). The relative enrichment of δ18O compared to δ15N was 0.86. We hypothesise that this influence is based on a variation in process kinetics of cross-membrane nitrate transport in relation to intracellular nitrate reduction. The core of the hypothesis is that nitrate transport into the cell becomes rate

  9. Kinetics and Mechanism of the Reaction of Hydoxyl Radicals with Acetonitrile under Atmospheric Conditions

    Science.gov (United States)

    Hynes, A. J.; Wine, P. H.

    1997-01-01

    scheme to extract kinetic information about the adduct reations with O2 and branching ratios for OH regeneration. A plausible mechanism for OH regeneration in (2) involves OH addition to the nitrogen atom followed by O2 addition to the cyano carbon atom, isomeriazation and decomposition to D2CO + DOCN + OH. Our results suggest that the OH + CH3CN reaction occurs via a complex mechanism involving both bimolecular and termolecular pathways, analogous to the mechanisms for the the important atmospheric reactions of OH with CO and HNO3.

  10. A Conditionally Stable Scheme for a Transient Flow of a Non-Newtonian Fluid Saturating a Porous Medium

    KAUST Repository

    El-Amin, Mohamed

    2012-06-02

    The problem of thermal dispersion effects on unsteady free convection from an isothermal horizontal circular cylinder to a non-Newtonian fluid saturating a porous medium is examined numerically. The Darcy-Brinkman-Forchheimer model is employed to describe the flow field. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The simultaneous development of the momentum and thermal boundary layers are obtained by using finite difference method. The stability conditions are determined for each difference equation. Using an explicit finite difference scheme, solutions at each time-step have been found and then stepped forward in time until reaching steady state solution. Velocity and temperature profiles are shown graphically. It is found that as time approaches infinity, the values of friction factor and heat transfer coefficient approach the steady state values.

  11. Influence of Last Glacial Maximum boundary conditions on the global water isotope distribution in an atmospheric general circulation model

    Directory of Open Access Journals (Sweden)

    T. Tharammal

    2013-03-01

    Full Text Available To understand the validity of δ18O proxy records as indicators of past temperature change, a series of experiments was conducted using an atmospheric general circulation model fitted with water isotope tracers (Community Atmosphere Model version 3.0, IsoCAM. A pre-industrial simulation was performed as the control experiment, as well as a simulation with all the boundary conditions set to Last Glacial Maximum (LGM values. Results from the pre-industrial and LGM simulations were compared to experiments in which the influence of individual boundary conditions (greenhouse gases, ice sheet albedo and topography, sea surface temperature (SST, and orbital parameters were changed each at a time to assess their individual impact. The experiments were designed in order to analyze the spatial variations of the oxygen isotopic composition of precipitation (δ18Oprecip in response to individual climate factors. The change in topography (due to the change in land ice cover played a significant role in reducing the surface temperature and δ18Oprecip over North America. Exposed shelf areas and the ice sheet albedo reduced the Northern Hemisphere surface temperature and δ18Oprecip further. A global mean cooling of 4.1 °C was simulated with combined LGM boundary conditions compared to the control simulation, which was in agreement with previous experiments using the fully coupled Community Climate System Model (CCSM3. Large reductions in δ18Oprecip over the LGM ice sheets were strongly linked to the temperature decrease over them. The SST and ice sheet topography changes were responsible for most of the changes in the climate and hence the δ18Oprecip distribution among the simulations.

  12. Transcriptomic analysis of fruit stored under cold conditions using controlled atmosphere in Prunus persica cv. ‘Red Pearl’

    Directory of Open Access Journals (Sweden)

    Dayan eSanhueza

    2015-09-01

    Full Text Available Cold storage (CS can induce a physiological disorder known as chilling injury (CI in nectarine fruits. The main symptom is mealiness that is perceived as non-juicy fruit by consumers. Postharvest treatments such as controlled atmosphere (CA; a high CO2 concentration and low O2 have been used under cold conditions to avoid this disorder. With the objective of exploring the mechanisms involved in the CA effect on mealiness prevention, we analyzed transcriptomic changes under six conditions of ‘Red Pearl’ nectarines by RNA-Seq. Our analysis included just harvested nectarines, juicy non-stored fruits, fruits affected for CI after CS and fruits stored in a combination of CA plus CS without CI phenotype. Nectarines stored in cold conditions combined with CA treatment resulted in less mealiness; we obtained 21.6% of juice content compared with just CS fruits (7.7%; mealy flesh. RNA-Seq data analyses were carried out to study the gene expression for different conditions assayed. During ripening, we detected that nectarines exposed to CA treatment expressed a similar number of genes compared with fruits that were not exposed to cold conditions. Firm fruits have more differentially expressed genes than soft fruits, which suggest that most important changes occur during CS. On the other hand, gene ontology analysis revealed enrichment mainly in metabolic and cellular processes. Differentially expressed genes analysis showed that low O2 concentrations combined with cold conditions slows the metabolic processes more than just the cold storage, resulting mainly in the suppression of primary metabolism and cold stress response. This is a significant step toward unraveling the molecular mechanism that explains the effectiveness of CA as a tool to prevent CI development on fruits.

  13. Behavior of Listeria monocytogenes in Sliced Ready-to-Eat Meat Products Packaged under Vacuum or Modified Atmosphere Conditions.

    Science.gov (United States)

    Menéndez, Rosa Ana; Rendueles, Eugenia; Sanz, José Javier; Capita, Rosa; García-Fernández, Camino

    2015-10-01

    The objective of this research was to determine the behavior of Listeria monocytogenes in three types of sliced ready-to-eat meat products packaged under vacuum or modified atmosphere conditions and stored at three temperatures. Slices of about 25 g of chorizo (a fermented dry pork sausage), jamón (cured ham), and cecina (a salted, dried beef product) were inoculated with L. monocytogenes NCTC 11994. Slices were packaged in a vacuum or in a modified atmosphere (20% CO2, 80% N2). After packaging, samples were stored for 6 months at three temperatures: 3, 11, or 20°C. Microbiological analyses were performed after 0, 1, 7, 15, 30, 45, 90, and 180 days of storage. The type of meat product, the type of packaging, the temperature, and the day of storage all influenced microbial levels (P < 0.001). L. monocytogenes counts decreased throughout the course of storage in samples of chorizo (quick decrease) and jamón (gradual decrease). In cecina samples, counts of L. monocytogenes increased from day 0 to day 1 of storage and then remained constant until day 90 of the study. These results may be of use for enhancing the safety of these ready-to-eat meat product types. Additional evaluation of the behavior of L. monocytogenes in cecina is needed.

  14. Ethylene reduces gas exchange and growth of lettuce plants under hypobaric and normal atmospheric conditions.

    Science.gov (United States)

    He, Chuanjiu; Davies, Fred T; Lacey, Ronald E

    2009-03-01

    Elevated levels of ethylene occur in controlled environment agriculture and in spaceflight environments, leading to adverse plant growth and sterility. The objectives of this research were to characterize the influence of ethylene on carbon dioxide (CO(2)) assimilation (C(A)), dark period respiration (DPR) and growth of lettuce (Lactuca sativa L. cv. Buttercrunch) under ambient and low total pressure conditions. Lettuce plants were grown under variable total gas pressures of 25 kPa (hypobaric) and 101 kPa (ambient) pressure. Endogenously produced ethylene accumulated and reduced C(A), DPR and plant growth of ambient and hypobaric plants. There was a negative linear correlation between increasing ethylene concentrations [from 0 to around 1000 nmol mol(-1) (ppb)] on C(A), DPR and growth of ambient and hypobaric plants. Declines in C(A) and DPR occurred with both exogenous and endogenous ethylene treatments. C(A) was more sensitive to increasing ethylene concentration than DPR. There was a direct, negative effect of increasing ethylene concentration reducing gas exchange as well as an indirect ethylene effect on leaf epinasty, which reduced light capture and C(A). While the C(A) was comparable, there was a lower DPR in hypobaric than ambient pressure plants - independent of ethylene and under non-limiting CO(2) levels (100 Pa pCO(2), nearly three-fold that in normal air). This research shows that lettuce can be grown under hypobaria ( congruent with25% of normal earth ambient total pressure); however, hypobaria caused no significant reduction of endogenous ethylene production.

  15. Standard practice for measurement of time-of-wetness on surfaces exposed to wetting conditions as in atmospheric corrosion testing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1989-01-01

    1.1 This practice covers a technique for monitoring time-of-wetness (TOW) on surfaces exposed to cyclic atmospheric conditions which produce depositions of moisture. 1.2 The practice is also applicable for detecting and monitoring condensation within a wall or roof assembly and in test apparatus. 1.3 Exposure site calibration or characterization can be significantly enhanced if TOW is measured for comparison with other sites, particularly if this data is used in conjunction with other site-specific instrumentation techniques. 1.4 The values stated in SI units are to be regarded as the standard. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  16. The effect of atmospheric thermal conditions and urban thermal pollution on all-cause and cardiovascular mortality in Bangladesh.

    Science.gov (United States)

    Burkart, Katrin; Schneider, Alexandra; Breitner, Susanne; Khan, Mobarak Hossain; Krämer, Alexander; Endlicher, Wilfried

    2011-01-01

    This study assessed the effect of temperature and thermal atmospheric conditions on all-cause and cardiovascular mortality in Bangladesh. In particular, differences in the response to elevated temperatures between urban and rural areas were investigated. Generalized additive models (GAMs) for daily death counts, adjusted for trend, season, day of the month and age were separately fitted for urban and rural areas. Breakpoint models were applied for determining the increase in mortality above and below a threshold (equivalent) temperature. Generally, a 'V'-shaped (equivalent) temperature-mortality curve with increasing mortality at low and high temperatures was observed. Particularly, urban areas suffered from heat-related mortality with a steep increase above a specific threshold. This adverse heat effect may well increase with ongoing urbanization and the intensification of the urban heat island due to the densification of building structures. Moreover, rising temperatures due to climate change could aggravate thermal stress. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    Science.gov (United States)

    Meakin, J. P.; Speight, J. D.; Sheridan, R. S.; Bradshaw, A.; Harris, I. R.; Williams, A. J.; Walton, A.

    2016-08-01

    Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.- computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd2O3 and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10-13 cm2/sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth observations at elevated temperatures in the literature. This indicates that the growth of the room temperature oxidation products are likely defect enhanced processes at the NdFeB triple junctions.

  18. Production of gasoline fraction from bio-oil under atmospheric conditions by an integrated catalytic transformation process

    International Nuclear Information System (INIS)

    Zhang, Zhaoxia; Bi, Peiyan; Jiang, Peiwen; Fan, Minghui; Deng, Shumei; Zhai, Qi; Li, Quanxin

    2015-01-01

    This work aimed to develop an integrated process for production of gasoline fraction bio-fuels from bio-oil under atmospheric conditions. This novel transformation process included the catalytic cracking of bio-oil to light olefins and the subsequent synthesis of liquid hydrocarbon bio-fuels from light olefins with two reactors in series. The yield of bio-fuel was up to 193.8 g/(kg bio-oil) along with a very low oxygen content, high RONs (research octane numbers), high LHVs (lower heating values) and low benzene content under the optimizing reaction conditions. Coke deposition seems to be the main cause of catalyst deactivation in view of the fact that the deactivated catalysts was almost recovered by on-line treating the used catalyst with oxygen. The integrated transformation potentially provides a useful way for the development of gasoline range hydrocarbon fuels using renewable lignocellulose biomass. - Graphical abstract: An integrated process for production of gasoline fraction bio-fuels from bio-oil through the catalytic cracking of bio-oil to light olefins followed by the synthesis of liquid hydrocarbon bio-fuels from light olefins in series. - Highlights: • A new route for production of gasoline-range bio-fuels from bio-oil was achieved. • The process was an integrated catalytic transformation at atmospheric pressure. • Bio-oil is converted into light olefins and then converted to biofuel in series. • C 6 –C 10 bio-fuels derived from bio-oil had high RONs and LHVs.

  19. Investigations of the ratios of stable carbon isotopes in atmospheric relevant VOC using simulation and field experiments; Untersuchungen der Verhaeltnisse stabiler Kohlenstoffisotope in atmosphaerisch relevanten VOC in Simulations- und Feldexperimenten

    Energy Technology Data Exchange (ETDEWEB)

    Spahn, Holger

    2010-07-01

    Volatile organic compounds (VOC) play an important role in the regional and global atmospheric chemistry. The author of the contribution under consideration reports on the analysis of the ratios of stable carbon isotopes ({delta}({sup 13}C) analysis) in atmospheric VOCs. At first, the state of the art of this analytical technique is described. For the first time {delta}({sup 13}C) values of different monoterpenes have been determined in the investigation of vegetable emissions at a plant chamber. By means of the oxidation of {beta}-pinene by ozone in an aerosol chamber, the kinetic isotope effect of this reaction was determined. In southern Germany, air samples for the {delta}({sup 13}C) analysis were collected using a zeppelin. This enables a height-resolved measurement of {delta}({sup 13}C) values. Based on these measurements, the average photochemical age for methanol, toluene and p-xylene at different heights was calculated.

  20. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Meakin, J.P., E-mail: jxm764@bham.ac.uk; Speight, J.D.; Sheridan, R.S.; Bradshaw, A.; Harris, I.R.; Williams, A.J.; Walton, A.

    2016-08-15

    Highlights: • Room temperature atmospheric oxidation behaviour of sintered NdFeB. • 3D laser confocal microscopy measurement of oxide phase growth. • Significant height increase of oxide phase only observed at triple points. • Raman spectroscopy identified oxide phase to be Nd{sub 2}O{sub 3}. • Diffusion coefficient determined to be 4 × 10{sup −13} cm{sup 2}/s. - Abstract: Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.— computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd{sub 2}O{sub 3} and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10{sup −13} cm{sup 2}/sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth

  1. 3-D laser confocal microscopy study of the oxidation of NdFeB magnets in atmospheric conditions

    International Nuclear Information System (INIS)

    Meakin, J.P.; Speight, J.D.; Sheridan, R.S.; Bradshaw, A.; Harris, I.R.; Williams, A.J.; Walton, A.

    2016-01-01

    Highlights: • Room temperature atmospheric oxidation behaviour of sintered NdFeB. • 3D laser confocal microscopy measurement of oxide phase growth. • Significant height increase of oxide phase only observed at triple points. • Raman spectroscopy identified oxide phase to be Nd 2 O 3 . • Diffusion coefficient determined to be 4 × 10 −13 cm 2 /s. - Abstract: Neodymium iron boron (NdFeB) magnets are used in a number of important applications, such as generators in gearless wind turbines, motors in electric vehicles and electronic goods (e.g.— computer hard disk drives, HDD). Hydrogen can be used as a processing gas to separate and recycle scrap sintered Nd-Fe-B magnets from end-of-life products to form a powder suitable for recycling. However, the magnets are likely to have been exposed to atmospheric conditions prior to processing, and any oxidation could lead to activation problems for the hydrogen decrepitation reaction. Many previous studies on the oxidation of NdFeB magnets have been performed at elevated temperatures; however, few studies have been formed under atmospheric conditions. In this paper a combination of 3-D laser confocal microscopy and Raman spectroscopy have been used to assess the composition, morphology and rate of oxidation/corrosion on scrap sintered NdFeB magnets. Confocal microscopy has been employed to measure the growth of surface reaction products at room temperature, immediately after exposure to air. The results showed that there was a significant height increase at the triple junctions of the Nd-rich grain boundaries. Using Raman spectroscopy, the product was shown to consist of Nd 2 O 3 and formed only on the Nd-rich triple junctions. The diffusion coefficient of the triple junction reaction product growth at 20 °C was determined to be approximately 4 × 10 −13 cm 2 /sec. This value is several orders of magnitude larger than values derived from the diffusion controlled oxide growth observations at elevated

  2. Intercomparison of peroxy radical measurements obtained at atmospheric conditions by laser-induced fluorescence and electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Hofzumahaus

    2009-03-01

    Full Text Available Measurements of hydroperoxy radical (HO2 and organic peroxy radical (RO2 concentrations were performed by two different techniques in the atmospheric simulation chamber SAPHIR in Jülich, Germany. The first technique was the well-established Matrix Isolation Electron Spin Resonance (MIESR, which provides absolute measurements with a time resolution of 30 min and high accuracy (10%, 2 σ. The other technique, ROxLIF, has been newly developed. It is based on the selective chemical conversion of ROx radicals (HO2 and RO2 to OH, which is detected with high sensitivity by laser-induced fluorescence (LIF. ROxLIF is calibrated by quantitative photolysis of water vapor at 185 nm and provides ambient measurements at a temporal resolution of 1 min and accuracy of 20% (2 σ. The measurements of HO2 and RO2 obtained by the two techniques were compared for two types of atmospheric simulation experiments. In one experiment, HO2 and CH3O2 radicals were produced by photooxidation of methane in air at tropospheric conditions. In the second experiment, HO2 and C2H5O2 were produced by ozonolysis of 1-butene in air at dark conditions. The radical concentrations were within the range of 16 to 100 pptv for HO2 and 12 to 45 pptv for RO2. Good agreement was found in the comparison of the ROxLIF and MIESR measurements within their combined experimental uncertainties. Linear regressions to the combined data set yield slopes of 1.02±0.13 (1 σ for RO2 and 0.98±0.08 (1 σ for HO2 without significant offsets. The results confirm the calibration of the ROxLIF instrument and demonstrate that it can be applied with good accuracy for measurements of atmospheric peroxy radical concentrations.

  3. Stable isotope (δ13C and δ15N) based interpretation of organic matter source and paleoenvironmental conditions in Al-Azraq basin, Jordan

    International Nuclear Information System (INIS)

    Ahmad, Khaldoun; Davies, Caroline

    2017-01-01

    This study examines the stable isotopes of carbon and nitrogen from cored lacustrine sediments of the Al-Azraq, an arid lake basin on the Jordan Plateau. Lacustrine sediments contain valuable records of paleoenvironmental conditions, recording local and regional responses to environmental change. Previous paleo-reconstructions on the Jordan Plateau are based on archaeology, pollen, mineralogy, and stratigraphy. The application of organic geochemistry analyses to these lake sediments identifies multiple sources of organic matter, biological production, and contributes to understanding the paleoenvironments of the Al-Azraq basin during the mid-Pleistocene period. Organic carbon concentration (Corg) provides an overview of the organic matter distribution. Carbon isotopic composition (δ13Corg) and nitrogen isotopic composition (δ15N) are indicators of organic matter sources and paleoproductivity. Magnetic susceptibility (MGSUS) measured the concentration of ferromagnetic minerals and indicated aeolian inputs. Organic geochemistry differentiated five paleoenvironmental zones with specific sources of organic matter, both aquatic and terrestrial. It identified a long period of climate wetter than the present, punctuated by a short intense period of aridity. Diagenesis plays an important role in the decomposition of organic matter and studies indicate this degradation can alter the isotopic signals of organic matter. Analyses of the isotopic signals and statistical analyses demonstrate diagenesis is not a factor in the Al-Azraq sediments in all but Zone 4 of the paleoenvironmental zones. This Zone is defined by less negative carbon isotopic composition and the presence of thick primary gypsum layers, in addition to the influx of high peaks of aeolian sediment as reflected in the magnetic susceptibility data. Stable isotope geochemistry provides detailed information on the paleoenvironments of lake sediments, and is applicable to typically challenging arid basin sediments

  4. Plasma-on-chip device for stable irradiation of cells cultured in media with a low-temperature atmospheric pressure plasma.

    Science.gov (United States)

    Okada, Tomohiro; Chang, Chun-Yao; Kobayashi, Mime; Shimizu, Tetsuji; Sasaki, Minoru; Kumagai, Shinya

    2016-09-01

    We have developed a micro electromechanical systems (MEMS) device which enables plasma treatment for cells cultured in media. The device, referred to as the plasma-on-chip, comprises microwells and microplasma sources fabricated together in a single chip. The microwells have through-holes between the microwells and microplasma sources. Each microplasma source is located on the backside of each microwells. The reactive components generated by the microplasma sources pass through the through-holes and reach cells cultured in the microwells. In this study, a plasma-on-chip device was modified for a stable plasma treatment. The use of a dielectric barrier discharge (DBD) technique allowed a stable plasma treatment up to 3 min. The plasma-on-chip with the original electrode configuration typically had the maximum stable operation time of around 1 min. Spectral analysis of the plasma identified reactive species such as O and OH radicals that can affect the activity of cells. Plasma treatment was successfully performed on yeast (Saccharomyces cerevisiae) and green algae (Chlorella) cells. While no apparent change was observed with yeast, the treatment degraded the activity of the Chlorella cells and decreased their fluorescence. The device has the potential to help understand interactions between plasma and cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Response characteristics of HPR1000 primary circuit under different working conditions of the atmospheric relief system after SBLOCA

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Danting, E-mail: suidanting@163.com [School of Nuclear Science and Engineering, North China Electric Power University, Beijing (China); Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing (China); Lu, Daogang [School of Nuclear Science and Engineering, North China Electric Power University, Beijing (China); Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing (China); Shang, Changzhong; Wei, Yuanyuan [China Nuclear Power Design Co., ltd (ShenZhen), Shenzhen (China); Zhang, Xianjie [School of Nuclear Science and Engineering, North China Electric Power University, Beijing (China); Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing (China)

    2017-04-01

    Highlights: • Response of HPR1000 under different VDA conditions after SBLOCA was investigated. • Activation of VDA can trigger ACCU SI earlier with a critical point exists. • VDA capability design should compromise the critical point with reactivity feedback. - Abstract: To cope with SBLOCA in absence of High-Head Safety Injection (HHSI) from design of HPR1000, atmospheric relief system (originally named as VDA in French) is uniquely designed to help to trigger Middle Head Safety Injection (MHSI) or Low Head Safety Injection (LHSI) earlier through cooling primary system quickly after SBLOCA. To make the best use of VDA decay heat removal capability, primary and secondary system of HPR1000 was modeled with RELAP5/SCDAP computer code. After steady-state initialization, a cold leg 30 mm break SBLOCA was simulated with six simulation conditions and five additional cases including availability of ACCU, different VDA discharge locations and area. Response characteristics of primary loop under different VDA working conditions are investigated. Pressurizer pressure decreases rapidly to lower level to trigger the reactor scram, VDA activation and accumulator safety injection sequently. Peak cladding temperature is 899.45 K occurring at 222 s, which is far below the safety limit. Activation of VDA can trigger ACCU SI earlier with a critical point, while positive reactivity will be introduced due to negative moderator temperature effect and Doppler effect. Larger VDA discharge capability will introduce larger reactivity feedback, as well as induce lower core level and SG level. It's suggested that VDA discharge condition should be chosen before the critical point, with the compromise with reactivity feedback introduced due to the negative moderator temperature effect.

  6. Shelf life of air and modified atmosphere-packaged fresh tilapia (Oreochromis niloticus) fillets stored under chilled and superchilled conditions

    Science.gov (United States)

    Cyprian, Odoli; Lauzon, Hélène L; Jóhannsson, Ragnar; Sveinsdóttir, Kolbrún; Arason, Sigurjón; Martinsdóttir, Emilía

    2013-01-01

    Optimal packaging and storage conditions for fresh tilapia fillets were established by evaluating sensory and microbiological changes, as well as monitoring physicochemical properties. Nile tilapia (Oreochromis niloticus) farmed in recirculation aquaculture system was filleted, deskinned, and packaged in air and 50% CO2/50% N2 prior to chilling and superchilling storage at 1°C and −1°C. Sensory analysis of cooked samples revealed a shelf life of 13–15 days for air-packaged fillets during storage at 1°C and 20 days at −1°C. At the end of shelf life in air-packaged fillets, total viable counts (TVC) and pseudomonads counts reached log 8 colony-forming units (CFU) g−1. In 50% CO2/50% N2-packaged fillets, the lag phase and generation time of bacteria were extended and recorded counts were below the limit for consumption (modified atmosphere (MA) packaging negatively affected color characteristics of the fillets soon after packaging (day 6). Color is an important indicator of tilapia fillets quality and a major factor in influencing retail purchase decisions. In view of that, air packaged at −1°C storage temperature was the optimal condition for fresh tilapia fillets. Total volatile basic nitrogen (TVB-N) and trimethylamine (TMA) were not good indicators of spoilage of tilapia fillets in this study. PMID:24804022

  7. Canopy conductance of Pinus taeda, Liquidambar styraciflua and Quercus phellos under varying atmospheric and soil water conditions.

    Science.gov (United States)

    Pataki, D. E.; Oren, R.; Katul, G.; Sigmon, J.

    1998-05-01

    Sap flow, and atmospheric and soil water data were collected in closed-top chambers under conditions of high soil water potential for saplings of Liquidambar styraciflua L., Quercus phellos L. and Pinus taeda L., three co-occurring species in the southeastern USA. Responses of canopy stomatal conductance (g(t)) to water stress induced by high atmospheric water vapor demand or transpiration rate were evaluated at two temporal scales. On a diurnal scale, the ratio of canopy stomatal conductance to maximum conductance (g(t)/g(t,max)) was related to vapor pressure deficit (D), and transpiration rate per unit leaf area (E(l)). High D or E(l) caused large reductions in g(t)/g(t,max) in L. styraciflua and P. taeda. The response of g(t)/g(t,max) to E(l) was light dependent in L. styraciflua, with higher g(t)/g(t,max) on sunny days than on cloudy days. In both L. styraciflua and Q. phellos, g(t)/g(t,max) decreased linearly with increasing D (indicative of a feed-forward mechanism of stomatal control), whereas g(t)/g(t,max) of P. taeda declined linearly with increasing E(l) (indicative of a feedback mechanism of stomatal control). Longer-term responses to depletion of soil water were observed as reductions in mean midday g(t)/g(t,max), but the reductions did not differ significantly between species. Thus, species that employ contrasting methods of stomatal control may show similar responses to soil water depletion in the long term.

  8. High-Dose Sirolimus and Immune-Selective Pentostatin plus Cyclophosphamide Conditioning Yields Stable Mixed Chimerism and Insufficient Graft-versus-Tumor Responses.

    Science.gov (United States)

    Mossoba, Miriam E; Halverson, David C; Kurlander, Roger; Schuver, Bazetta Blacklock; Carpenter, Ashley; Hansen, Brenna; Steinberg, Seth M; Ali, Syed Abbas; Tageja, Nishant; Hakim, Frances T; Gea-Banacloche, Juan; Sportes, Claude; Hardy, Nancy M; Hickstein, Dennis D; Pavletic, Steven Z; Khuu, Hanh; Sabatini, Marianna; Stroncek, David; Levine, Bruce L; June, Carl H; Mariotti, Jacopo; Rixe, Olivier; Fojo, Antonio Tito; Bishop, Michael R; Gress, Ronald E; Fowler, Daniel H

    2015-10-01

    We hypothesized that lymphoid-selective host conditioning and subsequent adoptive transfer of sirolimus-resistant allogeneic T cells (T-Rapa), when combined with high-dose sirolimus drug therapy in vivo, would safely achieve antitumor effects while avoiding GVHD. Patients (n = 10) with metastatic renal cell carcinoma (RCC) were accrued because this disease is relatively refractory to high-dose conditioning yet may respond to high-dose sirolimus. A 21-day outpatient regimen of weekly pentostatin (P; 4 mg/m(2)/dose) combined with daily, dose-adjusted cyclophosphamide (C; ≤200 mg/d) was designed to deplete and suppress host T cells. After PC conditioning, patients received matched sibling, T-cell-replete peripheral blood stem cell allografts, and high-dose sirolimus (serum trough target, 20-30 ng/mL). To augment graft-versus-tumor (GVT) effects, multiple T-Rapa donor lymphocyte infusions (DLI) were administered (days 0, 14, and 45 posttransplant), and sirolimus was discontinued early (day 60 posttransplant). PC conditioning depleted host T cells without neutropenia or infection and facilitated donor engraftment (10 of 10 cases). High-dose sirolimus therapy inhibited multiple T-Rapa DLI, as evidenced by stable mixed donor/host chimerism. No antitumor responses were detected by RECIST criteria and no significant classical acute GVHD was observed. Immune-selective PC conditioning represents a new approach to safely achieve alloengraftment without neutropenia. However, allogeneic T cells generated ex vivo in sirolimus are not resistant to the tolerance-inducing effects of in vivo sirolimus drug therapy, thereby cautioning against use of this intervention in patients with refractory cancer. ©2015 American Association for Cancer Research.

  9. Rainfall Downscaling Conditional on Upper-air Atmospheric Predictors: Improved Assessment of Rainfall Statistics in a Changing Climate

    Science.gov (United States)

    Langousis, Andreas; Mamalakis, Antonis; Deidda, Roberto; Marrocu, Marino

    2015-04-01

    To improve the level skill of Global Climate Models (GCMs) and Regional Climate Models (RCMs) in reproducing the statistics of rainfall at a basin level and at hydrologically relevant temporal scales (e.g. daily), two types of statistical approaches have been suggested. One is the statistical correction of climate model rainfall outputs using historical series of precipitation. The other is the use of stochastic models of rainfall to conditionally simulate precipitation series, based on large-scale atmospheric predictors produced by climate models (e.g. geopotential height, relative vorticity, divergence, mean sea level pressure). The latter approach, usually referred to as statistical rainfall downscaling, aims at reproducing the statistical character of rainfall, while accounting for the effects of large-scale atmospheric circulation (and, therefore, climate forcing) on rainfall statistics. While promising, statistical rainfall downscaling has not attracted much attention in recent years, since the suggested approaches involved complex (i.e. subjective or computationally intense) identification procedures of the local weather, in addition to demonstrating limited success in reproducing several statistical features of rainfall, such as seasonal variations, the distributions of dry and wet spell lengths, the distribution of the mean rainfall intensity inside wet periods, and the distribution of rainfall extremes. In an effort to remedy those shortcomings, Langousis and Kaleris (2014) developed a statistical framework for simulation of daily rainfall intensities conditional on upper air variables, which accurately reproduces the statistical character of rainfall at multiple time-scales. Here, we study the relative performance of: a) quantile-quantile (Q-Q) correction of climate model rainfall products, and b) the statistical downscaling scheme of Langousis and Kaleris (2014), in reproducing the statistical structure of rainfall, as well as rainfall extremes, at a

  10. Observations of atmospheric methane and its stable isotope ratio (δ13C) over the East Arctic seas from the ship cruises in the autumn of 2016

    Science.gov (United States)

    Pankratova, Natalia; Skorokhod, Andrey; Belikov, Igor; Semiletov, Igor; Berezina, Elena

    2017-04-01

    Methane (CH4) is the third most important greenhouse gas after water vapor and carbon dioxide (CO2) which has an integral radiative effect on the contemporary terrestrial climatic system. The methane radiative effect is 20 times as strong as carbon dioxide per unit mole. Taking into account the characteristic life time of the greenhouse gases molecules in the atmosphere, the methane global warming potential at the 100-year time interval is 20 times higher than the CO2 potential. Atmospheric CH4 mixing ratio and the changes in the methane 13C:12C ratio (reported the changes relative to a reference ratio and denoted as δ13C-CH4 and reported , in units of per mil) were measured from aboard the research vessel Akademik M.A. Lavrentiev from September to November 2016 in the Laptev, East Siberian and Chukchi Seas and as well as the North Pacific and the Sea of Japan. The measurements were made performed using a Cavity-Ring-Down Spectrometer (CRDS) from Picarro™ (model G2132-i). Together with methane concentrations of other trace gases (CO2, NO, NO2, O3) were measured. Air was sampled from an inlet at the front of the deck at 11 meters above sea level. A significant increase in methane concentration over the shelf areas of the Arctic seas and in the deltas of the large Siberian rivers is revealed in the expeditions. The measurements have confirmed the possibility of the formation of extreme methane concentrations (above 3 ppm) in the air over the areas of methane seeps of the Eastern shelf of the Arctic Ocean. The present study allowed to identify the sources of atmospheric methane in the Arctic. The measurements were compared with the surface methane data from the NOAA/ESRL arctic sites and the Tiksi station located on the shore of the Laptev Sea.

  11. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  12. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  13. A One-Dimensional Atmospheric Boundary Layer Model: Intermittent Wind Shears and Thermal Stability at Night

    National Research Council Canada - National Science Library

    Turnick, Arnold

    2001-01-01

    A one-dimensional, time-dependent computer model of the atmospheric boundary layer was developed to simulate intermittent turbulence and the near-ground microclimate under nighttime stable conditions...

  14. Application of {sup 13}C and {sup 15}N stable isotope probing to characterize RDX degrading microbial communities under different electron-accepting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Kun-Ching; Lee, Do Gyun [Zachry Department of Civil Engineering, Texas A& M University, College Station, TX 77843-3136 (United States); Fuller, Mark E.; Hatzinger, Paul B.; Condee, Charles W. [CB& I Federal Services, Lawrenceville, NJ (United States); Chu, Kung-Hui, E-mail: kchu@civil.tamu.edu [Zachry Department of Civil Engineering, Texas A& M University, College Station, TX 77843-3136 (United States)

    2015-10-30

    Highlights: • SIP characterized RDX-degrading communities under different e-accepting conditions. • Dominant RDX degradation pathways differed under different e-accepting conditions. • More complete detoxification of RDX occurred under methanogenic and sulfate-reducing conditions than under manganese(IV) and iron(III)-reducing conditions. - Abstract: This study identified microorganisms capable of using the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) or its metabolites as carbon and/or nitrogen sources under different electron-accepting conditions using {sup 13}C and {sup 15}N stable isotope probing (SIP). Mesocosms were constructed using groundwater and aquifer solids from an RDX-contaminated aquifer. The mesocosms received succinate as a carbon source and one of four electron acceptors (nitrate, manganese(IV), iron(III), or sulfate) or no additional electron acceptor (to stimulate methanogenesis). When RDX degradation was observed, subsamples from each mesocosm were removed and amended with {sup 13}C{sub 3}- or ring-{sup 15}N{sub 3}-, nitro-{sup 15}N{sub 3}-, or fully-labeled {sup 15}N{sub 6}-RDX, followed by additional incubation and isolation of labeled nucleic acids. A total of fifteen 16S rRNA sequences, clustering in α- and γ-Proteobacteria, Clostridia, and Actinobacteria, were detected in the {sup 13}C-DNA fractions. A total of twenty seven sequences were derived from different {sup 15}N-DNA fractions, with the sequences clustered in α- and γ-Proteobacteria, and Clostridia. Interestingly, sequences identified as Desulfosporosinus sp. (in the Clostridia) were not only observed to incorporate the labeled {sup 13}C or {sup 15}N from labeled RDX, but also were detected under each of the different electron-accepting conditions. The data suggest that {sup 13}C- and {sup 15}N-SIP can be used to characterize microbial communities involved in RDX biodegradation, and that the dominant pathway of RDX biodegradation may differ under different

  15. Unconditionally stable methods for simulating multi-component two-phase interface models with Peng-Robinson equation of state and various boundary conditions

    KAUST Repository

    Kou, Jisheng

    2015-03-01

    In this paper, we consider multi-component dynamic two-phase interface models, which are formulated by the Cahn-Hilliard system with Peng-Robinson equation of state and various boundary conditions. These models can be derived from the minimum problems of Helmholtz free energy or grand potential in the realistic thermodynamic systems. The resulted Cahn-Hilliard systems with various boundary conditions are fully coupled and strongly nonlinear. A linear transformation is introduced to decouple the relations between different components, and as a result, the models are simplified. From this, we further propose a semi-implicit unconditionally stable time discretization scheme, which allows us to solve the Cahn-Hilliard system by a decoupled way, and thus, our method can significantly reduce the computational cost and memory requirements. The mixed finite element methods are employed for the spatial discretization, and the approximate errors are also analyzed for both space and time. Numerical examples are tested to demonstrate the efficiency of our proposed methods. © 2015 Elsevier B.V.

  16. Increasing Juniperus virginiana L. pollen in the Tulsa atmosphere: long-term trends, variability, and influence of meteorological conditions.

    Science.gov (United States)

    Flonard, Michaela; Lo, Esther; Levetin, Estelle

    2018-02-01

    In the Tulsa area, the Cupressaceae is largely represented by eastern red cedar (Juniperus virginiana L.). The encroachment of this species into the grasslands of Oklahoma has been well documented, and it is believed this trend will continue. The pollen is known to be allergenic and is a major component of the Tulsa atmosphere in February and March. This study examined airborne Cupressaceae pollen data from 1987 to 2016 to determine long-term trends, pollen seasonal variability, and influence of meteorological variables on airborne pollen concentrations. Pollen was collected through means of a Burkard sampler and analyzed with microscopy. Daily pollen concentrations and yearly pollen metrics showed a high degree of variability. In addition, there were significant increases over time in the seasonal pollen index and in peak concentrations. These increases parallel the increasing population of J. virginiana in the region. Pollen data were split into pre- and post-peak categories for statistical analyses, which revealed significant differences in correlations of the two datasets when analyzed with meteorological conditions. While temperature and dew point, among others were significant in both datasets, other factors, like relative humidity, were significant only in one dataset. Analyses using wind direction showed that southerly and southwestern winds contributed to increased pollen concentrations. This study confirms that J. virginiana pollen has become an increasing risk for individuals sensitive to this pollen and emphasizes the need for long-term aerobiological monitoring in other areas.

  17. To a scientific substantiation of a practical method of inspection of radiating conditions on territories, polluted with atmospheric fallout

    International Nuclear Information System (INIS)

    Burmistrov, V.R; Makarenko, N.G.; Karimova, L.M.

    2001-01-01

    Full text: In the report a question on necessity of practical development of a method of inspection of radiating fields, adapted to a nature of pollution is put. 50-year study of radionuclides pollution, dropping out from atmosphere after nuclear tests or failures, have shown non-perspective of traditional techniques of inspection of a radiating conditions on large territories. The detailed measurements covering surface without gaps are very expensive, and use of a unloaded grid requires interpolation irregular mosaic structure. Detection Fractal structure at the analysis Chernobyl losses and pollution of fragments of Semipalatinsk test nuclear site specify necessity of the account of self-similar properties of pollution in philosophy of measurement. For realization of potential opportunities Fractal field the special circuit of measurements, distinguished from, is required standard. Fractal approach requires shooting with system of crossed vicinities on chosen detailed platforms, making a rather small part of surveyed territory. These data will allow to reveal scale laws, which are universal in a significant range of scales. Using scaling of small platforms, it is possible to receive correct estimation of structure of pollution of large territories. The stated above reasons are based on our experiments on fractal approach to the analysis of continuous shooting (aero-scale shooting of scale 1:5000) in a zone of Semipalatinsk test site on three platforms by the sizes on 1000x400 m 2 . Our results specify necessity revision almost of all conclusions, received earlier on the basis of traditional techniques

  18. Increasing Juniperus virginiana L. pollen in the Tulsa atmosphere: long-term trends, variability, and influence of meteorological conditions

    Science.gov (United States)

    Flonard, Michaela; Lo, Esther; Levetin, Estelle

    2018-02-01

    In the Tulsa area, the Cupressaceae is largely represented by eastern red cedar ( Juniperus virginiana L.). The encroachment of this species into the grasslands of Oklahoma has been well documented, and it is believed this trend will continue. The pollen is known to be allergenic and is a major component of the Tulsa atmosphere in February and March. This study examined airborne Cupressaceae pollen data from 1987 to 2016 to determine long-term trends, pollen seasonal variability, and influence of meteorological variables on airborne pollen concentrations. Pollen was collected through means of a Burkard sampler and analyzed with microscopy. Daily pollen concentrations and yearly pollen metrics showed a high degree of variability. In addition, there were significant increases over time in the seasonal pollen index and in peak concentrations. These increases parallel the increasing population of J. virginiana in the region. Pollen data were split into pre- and post-peak categories for statistical analyses, which revealed significant differences in correlations of the two datasets when analyzed with meteorological conditions. While temperature and dew point, among others were significant in both datasets, other factors, like relative humidity, were significant only in one dataset. Analyses using wind direction showed that southerly and southwestern winds contributed to increased pollen concentrations. This study confirms that J. virginiana pollen has become an increasing risk for individuals sensitive to this pollen and emphasizes the need for long-term aerobiological monitoring in other areas.

  19. Linking atmospheric synoptic transport, cloud phase, surface energy fluxes, and sea-ice growth: observations of midwinter SHEBA conditions

    Science.gov (United States)

    Persson, P. Ola G.; Shupe, Matthew D.; Perovich, Don; Solomon, Amy

    2017-08-01

    Observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) project are used to describe a sequence of events linking midwinter long-range advection of atmospheric heat and moisture into the Arctic Basin, formation of supercooled liquid water clouds, enhancement of net surface energy fluxes through increased downwelling longwave radiation, and reduction in near-surface conductive heat flux loss due to a warming of the surface, thereby leading to a reduction in sea-ice bottom growth. The analyses provide details of two events during Jan. 1-12, 1998, one entering the Arctic through Fram Strait and the other from northeast Siberia; winter statistics extend the results. Both deep, precipitating frontal clouds and post-frontal stratocumulus clouds impact the surface radiation and energy budget. Cloud liquid water, occurring preferentially in stratocumulus clouds extending into the base of the inversion, provides the strongest impact on surface radiation and hence modulates the surface forcing, as found previously. The observations suggest a minimum water vapor threshold, likely case dependent, for producing liquid water clouds. Through responses to the radiative forcing and surface warming, this cloud liquid water also modulates the turbulent and conductive heat fluxes, and produces a thermal wave penetrating into the sea ice. About 20-33 % of the observed variations of bottom ice growth can be directly linked to variations in surface conductive heat flux, with retarded ice growth occurring several days after these moisture plumes reduce the surface conductive heat flux. This sequence of events modulate pack-ice wintertime environmental conditions and total ice growth, and has implications for the annual sea-ice evolution, especially for the current conditions of extensive thinner ice.

  20. A reconstruction of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the last glacial inception

    Directory of Open Access Journals (Sweden)

    R. Schneider

    2013-11-01

    δ13Catm level in the Penultimate (~ 140 000 yr BP and Last Glacial Maximum (~ 22 000 yr BP, which can be explained by either (i changes in the isotopic composition or (ii intensity of the carbon input fluxes to the combined ocean/atmosphere carbon reservoir or (iii by long-term peat buildup. Our isotopic data suggest that the carbon cycle evolution along Termination II and the subsequent interglacial was controlled by essentially the same processes as during the last 24 000 yr, but with different phasing and magnitudes. Furthermore, a 5000 yr lag in the CO2 decline relative to EDC temperatures is confirmed during the glacial inception at the end of MIS5.5 (120 000 yr BP. Based on our isotopic data this lag can be explained by terrestrial carbon release and carbonate compensation.

  1. Observations of atmospheric methane and its stable isotope ratio (δ13C) over the Arctic seas from ship cruises in the summer and autumn of 2015

    Science.gov (United States)

    Skorokhod, Andrey; Belikov, Igor; Pankratova, Natalia; Novigatsky, Alexander; Thompson, Rona

    2016-04-01

    Atmospheric methane (CH4) is the second most important long-lived greenhouse gas. The Arctic has significant sources of CH4, such as from wetlands and possibly also from methane hydrates, which may act as a positive feedback on the climate system. Despite significant efforts in establishing a network of ground-based CH4 observations in the Arctic zone, there is still a lack of measurements over the Arctic Ocean and sub-polar seas. From 21 July to 9 October 2015, concentrations of CH4 and CO2, as well as of the 13C:12C isotopic ratio in CH4, i.e., δ13C, were measured in the marine boundary layer from aboard the Research Vessel "Akademik Mstislav Keldysh" by the Shirshov Institute of Oceanology. Measurements were made using a Cavity Ring Down Spectroscopy instrument from Picarro™ (model G2132-i). The cruises covered a vast area including the North Atlantic up to 70°N, the Baltic, North, Norwegian, Greenland, Barents, White, Kara and Laptev Seas. To the best of our knowledge, these are the first measurements of their type made in these regions. Concentrations of CH4 typically had low variations (in the range of a few ppb) in the open sea but relatively large variations (of the order of 100 ppb) were recorded near and during stops in ports. High variability of atmospheric CH4 was also registered near the delta of the Lena River in the Laptev Sea, which has been suggested to be a large CH4 reservoir and where bubbles rising through the water column have been observed. The obtained set of δ13CCH4 is characterized by significant range of the measured values varying from open Atlantic to polluted regions near large sea ports. The Keeling plot analyses were implemented to study possible CH4 sources according to its isotopic signature. Footprint analyses are presented for the shipboard observations, as well as comparisons to simulated CH4 concentrations and δ13C using the Lagrangian transport model, FLEXPART. This work has been carried-out with the financial support of

  2. Using stable isotopes of hydrogen to quantify biogenic and thermogenic atmospheric methane sources: A case study from the Colorado Front Range

    Science.gov (United States)

    Townsend-Small, Amy; Botner, E. Claire; Jimenez, Kristine L.; Schroeder, Jason R.; Blake, Nicola J.; Meinardi, Simone; Blake, Donald R.; Sive, Barkley C.; Bon, Daniel; Crawford, James H.; Pfister, Gabriele; Flocke, Frank M.

    2016-11-01

    Global atmospheric concentrations of methane (CH4), a powerful greenhouse gas, are increasing, but because there are many natural and anthropogenic sources of CH4, it is difficult to assess which sources may be increasing in magnitude. Here we present a data set of δ2H-CH4 measurements of individual sources and air in the Colorado Front Range, USA. We show that δ2H-CH4, but not δ13C, signatures are consistent in air sampled downwind of landfills, cattle feedlots, and oil and gas wells in the region. Applying these source signatures to air in ground and aircraft samples indicates that at least 50% of CH4 emitted in the region is biogenic, perhaps because regulatory restrictions on leaking oil and natural gas wells are helping to reduce this source of CH4. Source apportionment tracers such as δ2H may help close the gap between CH4 observations and inventories, which may underestimate biogenic as well as thermogenic sources.

  3. Determining Carbon and Oxygen Stable Isotope Systematics in Brines at Elevated p/T Conditions to Enhance Monitoring of CO2 Induced Processes in Carbon Storage Reservoirs

    Science.gov (United States)

    Becker, V.; Myrttinen, A.; Mayer, B.; Barth, J. A.

    2012-12-01

    Stable carbon isotope ratios (δ13C) are a powerful tool for inferring carbon sources and mixing ratios of injected and baseline CO2 in storage reservoirs. Furthermore, CO2 releasing and consuming processes can be deduced if the isotopic compositions of end-members are known. At low CO2 pressures (pCO2), oxygen isotope ratios (δ18O) of CO2 usually assume the δ18O of the water plus a temperature-dependent isotope fractionation factor. However, at very high CO2 pressures as they occur in CO2 storage reservoirs, the δ18O of the injected CO2 may in fact change the δ18O of the reservoir brine. Hence, changing δ18O of brine constitutes an additional tracer for reservoir-internal carbon dynamics and allows the determination of the amount of free phase CO2 present in the reservoir (Johnson et al. 2011). Further systematic research to quantify carbon and oxygen isotope fractionation between the involved inorganic carbon species (CO2, H2CO3, HCO3-, CO32-, carbonate minerals) and kinetic and equilibrium isotope effects during gas-water-rock interactions is necessary because p/T conditions and salinities in CO2 storage reservoirs may exceed the boundary conditions of typical environmental isotope applications, thereby limiting the accuracy of stable isotope monitoring approaches in deep saline formations (Becker et al. 2011). In doing so, it is crucial to compare isotopic patterns observed in laboratory experiments with artificial brines to similar experiments with original fluids from representative field sites to account for reactions of dissolved inorganic carbon (DIC) with minor brine components. In the CO2ISO-LABEL project, funded by the German Ministry for Education and Research, multiple series of laboratory experiments are conducted to determine the influence of pressure, temperature and brine composition on the δ13C of DIC and the δ18O of brines in water-CO2-rock reactions with special focus placed on kinetics and stable oxygen and carbon isotope fractionation

  4. Diurnal variations of organic molecular tracers and stable carbon isotopic composition in atmospheric aerosols over Mt. Tai in the North China Plain: an influence of biomass burning

    Directory of Open Access Journals (Sweden)

    P. Q. Fu

    2012-09-01

    Full Text Available Organic tracer compounds, as well as organic carbon (OC, elemental carbon (EC, water-soluble organic carbon (WSOC, and stable carbon isotope ratios (δ13C of total carbon (TC have been investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006 field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs. In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3 were double those in late June (926 ± 574 ng m−3. All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, mean 403 ng m−3 was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary

  5. Diurnal variations of organic molecular tracers and stable carbon isotopic composition in atmospheric aerosols over Mt. Tai in the North China Plain: an influence of biomass burning

    Science.gov (United States)

    Fu, P. Q.; Kawamura, K.; Chen, J.; Li, J.; Sun, Y. L.; Liu, Y.; Tachibana, E.; Aggarwal, S. G.; Okuzawa, K.; Tanimoto, H.; Kanaya, Y.; Wang, Z. F.

    2012-09-01

    Organic tracer compounds, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006) field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m-3) were double those in late June (926 ± 574 ng m-3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88-1210 ng m-3, mean 403 ng m-3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the

  6. Diurnal variations of organic molecular tracers and stable carbon isotopic compositions in atmospheric aerosols over Mt. Tai in North China Plain: an influence of biomass burning

    Science.gov (United States)

    Fu, P. Q.; Kawamura, K.; Chen, J.; Li, J.; Sun, Y. L.; Liu, Y.; Tachibana, E.; Aggarwal, S. G.; Okuzawa, K.; Tanimoto, H.; Kanaya, Y.; Wang, Z. F.

    2012-04-01

    Organic tracer compounds of tropospheric aerosols, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated for aerosol samples collected during early and late periods of Mount Tai eXperiment 2006 (MTX2006) field campaign in North China Plain. Total solvent extracts were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in North China Plain were very active, the total identified organics (2090 ± 1170 ng m-3) were double those in late June (926 ± 574 ng m-3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88-1210 ng m-3, 403 ng m-3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude and then transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the OC in the Mt. Tai

  7. Stable long-term pulmonary function after fludarabine, antithymocyte globulin and i.v. BU for reduced-intensity conditioning allogeneic SCT.

    Science.gov (United States)

    Dirou, S; Malard, F; Chambellan, A; Chevallier, P; Germaud, P; Guillaume, T; Delaunay, J; Moreau, P; Delasalle, B; Lemarchand, P; Mohty, M

    2014-05-01

    Lung function decline is a well-recognized complication following allogeneic SCT (allo-SCT). Reduced-intensity conditioning (RIC) and in vivo T-cell depletion by administration of antithymocyte globulin (ATG) may have a protective role in the occurrence of late pulmonary complications. This retrospective study reported the evolution of lung function parameters within the first 2 years after allo-SCT in a population receiving the same RIC regimen that included fludarabine and i.v. BU in combination with low-dose ATG. The median follow-up was 35.2 months. With a median age of 59 years at the time of transplant, at 2 years, the cumulative incidences of non-relapse mortality was as low as 9.7%. The cumulative incidence of relapse was 33%. At 2 years, the cumulative incidences of extensive chronic GVHD (cGVHD) and of pulmonary cGVHD were 23.1% and 1.9%, respectively. The cumulative incidences of airflow obstruction and restrictive pattern were 3.8% and 9.6%, respectively. Moreover, forced expiratory volume (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio remained stable from baseline up to 2 years post transplantation (P=0.26, P=0.27 and P=0.07, respectively). These results correspond favorably with the results obtained with other RIC regimens not incorporating ATG, and suggest that ATG may have a protective pulmonary role after allo-SCT.

  8. Different Assay Conditions for Detecting the Production and Release of Heat-Labile and Heat-Stable Toxins in Enterotoxigenic Escherichia coli Isolates

    Directory of Open Access Journals (Sweden)

    Letícia B. Rocha

    2013-12-01

    Full Text Available Enterotoxigenic Escherichia coli (ETEC produce heat-labile (LT and/or heat-stable enterotoxins (ST. Despite that, the mechanism of action of both toxins are well known, there is great controversy in the literature concerning the in vitro production and release of LT and, for ST, no major concerns have been discussed. Furthermore, the majority of published papers describe the use of only one or a few ETEC isolates to define the production and release of these toxins, which hinders the detection of ETEC by phenotypic approaches. Thus, the present study was undertaken to obtain a better understanding of ST and LT toxin production and release under laboratory conditions. Accordingly, a collection of 90 LT-, ST-, and ST/LT-producing ETEC isolates was used to determine a protocol for toxin production and release aimed at ETEC detection. For this, we used previously raised anti-LT antibodies and the anti-ST monoclonal and polyclonal antibodies described herein. The presence of bile salts and the use of certain antibiotics improved ETEC toxin production/release. Triton X-100, as chemical treatment, proved to be an alternative method for toxin release. Consequently, a common protocol that can increase the production and release of LT and ST toxins could facilitate and enhance the sensitivity of diagnostic tests for ETEC using the raised and described antibodies in the present work.

  9. Seasonal and Diurnal Variation of Atmospheric Fungal Spore Concentrations in Hyderabad; Tandojam-Sindh and the Effects of Climatic Conditions

    International Nuclear Information System (INIS)

    Khan, M.; Parveen, A.; Qaisar, M.

    2016-01-01

    Airborne biological particles are present in every type of environment. Different types of geographical localities have different type of airspora, which affect human health. The current study is conducted for the first time to identify the airborne fungal spores from Hyderabad: Tando-Jam, Sindh. For this purpose, Burkard's 7-Days recording volumetric spore trap was used for a period of one year. A total of 68,183 spores/m/sup 3/ were recorded throughout the study period, belonging to 41 fungal spores types. The presented data revealed that Deuteromycetes spore type was predominant. Cladosporium sp. spores were detected in the highest concentration i.e., 50.83 percent, which was followed by Aspergillus sp. (18.63 percent) and Alternaria sp. (11.04 percent). The highest spore count was captured in the month of September-2008 (17,294 spores/m/sup 3/), while lowest spore count was found in the month of June-2009. Diurnal patterns of individual fungal spore types was observed to be mid-day to evening maxima for various species. Spearman rank correlation coefficient r was determined for correlation of fungal spore counts with climatic factors by using IBM software SPSS ver. 20. Results of the current study revealed that fungal spore concentration was increased in high humid weather while low count was found in hot and windy climate that was also confirmed by statistical analysis. The presented work demonstrated that various types of allergenic and phytopathogenic fungal spores were present in the atmosphere of Hyderabad: Tando-Jam. It was also observed that meteorological conditions had a significant impact on dispersal and concentration of fungal spores. (author)

  10. Stabilization of atmospheric carbon dioxide via zero emissions--an alternative way to a stable global environment. Part 2: a practical zero-emissions scenario.

    Science.gov (United States)

    Matsuno, Taroh; Maruyama, Koki; Tsutsui, Junichi

    2012-01-01

    Following Part 1, a comparison of CO(2)-emissions pathways between "zero-emissions stabilization (Z-stabilization)" and traditional stabilization is made under more realistic conditions that take into account the radiative forcings of other greenhouse gases and aerosols with the constraint that the temperature rise must not exceed 2 °C above the preindustrial level. It is shown that the findings in Part 1 on the merits of Z-stabilization hold under the more realistic conditions. The results clarify the scientific basis of the policy claim of 50% reduction of the world CO(2) emissions by 2050. Since the highest greenhouse gas (GHG) concentration and temperature occur only temporarily in Z-stabilization pathways, we may slightly relax the upper limit of the temperature rise. We can then search for a scenario with larger emissions in the 21st century; such a scenario may have potential for practical application. It is suggested that in this Z-stabilization pathway, larger emissions in the near future may be important from a socioeconomic viewpoint.

  11. Proton Transfer Reaction Time-of-Flight Mass Spectrometric (PTR-TOF-MS) determination of volatile organic compounds (VOCs) emitted from a biomass fire developed under stable nocturnal conditions

    Science.gov (United States)

    Brilli, Federico; Gioli, Beniamino; Ciccioli, Paolo; Zona, Donatella; Loreto, Francesco; Janssens, Ivan A.; Ceulemans, Reinhart

    2014-11-01

    Combustion of solid and liquid fuels is the largest source of potentially toxic volatile organic compounds (VOCs), which can strongly affect health and the physical and chemical properties of the atmosphere. Among combustion processes, biomass burning is one of the largest at global scale. We used a Proton Transfer Reaction “Time-of-Flight” Mass Spectrometer (PTR-TOF-MS), which couples high sensitivity with high mass resolution, for real-time detection of multiple VOCs emitted by burned hay and straw in a barn located near our measuring station. We detected 132 different organic ions directly attributable to VOCs emitted from the fire. Methanol, acetaldehyde, acetone, methyl vinyl ether (MVE), acetic acid and glycolaldehyde dominated the VOC mixture composition. The time-course of the 25 most abundant VOCs, representing ∼85% of the whole mixture of VOCs, was associated with that of carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4) emissions. The strong linear relationship between the concentrations of pyrogenic VOC and of a reference species (i.e. CO) allowed us to compile a list of emission ratios (ERs) and emission factors (EFs), but values of ER (and EF) were overestimated due to the limited mixing of the gases under the stable (non-turbulent) nocturnal conditions. In addition to the 25 most abundant VOCs, chemical formula and concentrations of the residual, less abundant VOCs in the emitted mixture were also estimated by PTR-TOF-MS. Furthermore, the evolution of the complex combustion process was described on the basis of the diverse types of pyrogenic gases recorded.

  12. Measurements of Atmospheric CO2 Column in Cloudy Weather Conditions using An IM-CW Lidar at 1.57 Micron

    Science.gov (United States)

    Lin, Bing; Obland, Michael; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Campbell, Joel; Dobler, Jeremy; Meadows, Bryon; Fan, Tai-Fang; Kooi, Susan; hide

    2015-01-01

    This study evaluates the capability of atmospheric CO2 column measurements under cloudy conditions using an airborne intensity-modulated continuous-wave integrated-path-differential-absorption lidar operating in the 1.57-m CO2 absorption band. The atmospheric CO2 column amounts from the aircraft to the tops of optically thick cumulus clouds and to the surface in the presence of optically thin clouds are retrieved from lidar data obtained during the summer 2011 and spring 2013 flight campaigns, respectively.

  13. Letter to the EditorOn the use of the sunspot number for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations

    Directory of Open Access Journals (Sweden)

    Vaquero

    2005-07-01

    Full Text Available In this short contribution the use of different sunspot numbers for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations realised by Schröder et al. (2004 is analysed. Moreover, some comments are made on the relationships between mean annual visual observations of the auroras at middle latitudes of Europe and the mean annual sunspot number during 1780–1829. Keywords. Atmospheric composition and structure (Airglow and aurora – Magnetospheric physics (Auroral phenomena, solar wind-magnetosphere interactions – History of geophysics (Solar-planetary relationship

  14. Spring soil moisture-precipitation feedback in the Southern Great Plains: How is it related to large-scale atmospheric conditions?

    KAUST Repository

    Su, Hua

    2014-02-22

    The Southern Great Plains (SGP) has been shown as a region of significant soil moisture-precipitation (S-P) coupling. However, how strong evapotranspiration (ET) can affect regional precipitation remains largely unclear, impeding a full grasp of the S-P feedback in that area. The current study seeks to unravel, in a spring month (April), the potential role played by large-scale atmospheric conditions in shaping S (ET)-P feedback. Our regional climate modeling experiments demonstrate that the presence of anomalous low (high) pressure and cyclonic (anticyclonic) flows at the upper/middle troposphere over the relevant areas is associated with strongest (minimum) positive S-P feedback in the SGP. Their impacts are interpreted in terms of large-scale atmospheric dynamical disturbance, including the intensity and location of synoptic eddies. Further analyses of the vertical velocity fields corroborate these interpretations. In addition, the relationship between lower tropospheric moisture conditions (including winds) and feedback composites is evaluated. Key Points The S-P feedback strength in SGP in April varies inter-annually The atmospheric dynamic features affect significantly the feedback strength composite moisture conditions are related to atmospheric circulation structure ©2014. American Geophysical Union. All Rights Reserved.

  15. Surface enrichment of Pt in stable Pt-Ir nano-alloy particles on MgAl 2 O 4 spinel in oxidizing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Li, Weizhen; Nie, Lei; Chen, Ying; Kovarik, Libor; Liu, Jun; Wang, Yong

    2017-04-01

    With the capability of MgAl2O4 spinel {111} nano-facets in stabilizing small Rh, Ir and Pt particles, bimetallic Ir-Pt catalysts on the same support were investigated, aiming at further lowering the catalyst cost by substituting expensive Pt with cheaper Ir in the bulk. Small Pt-Ir nano-alloy particles (< 2nm) were successfully stabilized on the spinel {111} nano-facets as expected. Interestingly, methanol oxidative dehydrogenation (ODH) rate on the surface Pt atoms increases with oxidizing aging but decreases upon reducing treatment, where Ir is almost inactive under the same reaction conditions. Up to three times enhancement in Pt exposure was achieved when the sample was oxidized at 800 °C in air for 1 week and subsequently reduced by H2 for 2 h, demonstrating successful surface enrichment of Pt on Pt-Ir nano-alloy particles. A dynamic stabilization mechanism involving wetting\

  16. Improvement of a mesoscale atmospheric dynamic model PHYSIC. Utilization of output from synoptic numerical prediction model for initial and boundary condition

    International Nuclear Information System (INIS)

    Nagai, Haruyasu; Yamazawa, Hiromi

    1995-03-01

    This report describes the improvement of the mesoscale atmospheric dynamic model which is a part of the atmospheric dispersion calculation model PHYSIC. To introduce large-scale meteorological changes into the mesoscale atmospheric dynamic model, it is necessary to make the initial and boundary conditions of the model by using GPV (Grid Point Value) which is the output of the numerical weather prediction model of JMA (Japan Meteorological Agency). Therefore, the program which preprocesses the GPV data to make a input file to PHYSIC was developed and the input process and the methods of spatial and temporal interpolation were improved to correspond to the file. Moreover, the methods of calculating the cloud amount and ground surface moisture from GPV data were developed and added to the model code. As the example of calculation by the improved model, the wind field simulations of a north-west monsoon in winter and a sea breeze in summer in the Tokai area were also presented. (author)

  17. SWiFT site atmospheric characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ennis, Brandon Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Historical meteorological tall tower data are analyzed from the Texas Tech University 200 m tower to characterize the atmospheric trends of the Scaled Wind Farm Technologies (SWiFT) site. In this report the data are analyzed to reveal bulk atmospheric trends, temporal trends and correlations of atmospheric variables. Through this analysis for the SWiFT turbines the site International Electrotechnical Commission (IEC) classification is determined to be class III-C. Averages and distributions of atmospheric variables are shown, revealing large fluctuations and the importance of understanding the actual site trends as opposed to simply using averages. The site is significantly directional with the average wind speed from the south, and particularly so in summer and fall. Site temporal trends are analyzed from both seasonal (time of the year) to daily (hour of the day) perspectives. Atmospheric stability is seen to vary most with time of day and less with time of year. Turbulence intensity is highly correlated with stability, and typical daytime unstable conditions see double the level of turbulence intensity versus that experienced during the average stable night. Shear, veer and atmospheric stability correlations are shown, where shear and veer are both highest for stable atmospheric conditions. An analysis of the Texas Tech University tower anemometer measurements is performed which reveals the extent of the tower shadow effects and sonic tilt misalignment.

  18. Continuous measurements of stable isotopes of carbon dioxide and water vapour in an urban atmosphere: isotopic variations associated with meteorological conditions.

    Science.gov (United States)

    Wada, Ryuichi; Matsumi, Yutaka; Nakayama, Tomoki; Hiyama, Tetsuya; Fujiyoshi, Yasushi; Kurita, Naoyuki; Muramoto, Kenichiro; Takanashi, Satoru; Kodama, Naomi; Takahashi, Yoshiyuki

    2017-12-01

    Isotope ratios of carbon dioxide and water vapour in the near-surface air were continuously measured for one month in an urban area of the city of Nagoya in central Japan in September 2010 using laser spectroscopic techniques. During the passages of a typhoon and a stationary front in the observation period, remarkable changes in the isotope ratios of CO 2 and water vapour were observed. The isotope ratios of both CO 2 and water vapour decreased during the typhoon passage. The decreases can be attributed to the air coming from an industrial area and the rainout effects of the typhoon, respectively. During the passage of the stationary front, δ 13 C-CO 2 and δ 18 O-CO 2 increased, while δ 2 H-H 2 Ov and δ 18 O-H 2 Ov decreased. These changes can be attributed to the air coming from rural areas and the air surrounding the observational site changing from a subtropical air mass to a subpolar air mass during the passage of the stationary front. A clear relationship was observed between the isotopic CO 2 and water vapour and the meteorological phenomena. Therefore, isotopic information of CO 2 and H 2 Ov could be used as a tracer of meteorological information.

  19. Analysis of the effect of atmospheric oscillations on physical condition of pre–reproductive bluefin tuna from the Strait of Gibraltar

    Directory of Open Access Journals (Sweden)

    Báez, J. C.

    2013-12-01

    Full Text Available The aim of this study was to explore the possible effects of atmospheric oscillations: North Atlantic Oscillation (NAO and Arctic Oscillation (AO, on the physical condition of bluefin tuna (Thunnus thynnus. We estimated a fitness ratio from 3,501 pairs of length–weight data based on bluefin tuna caught in bait–boat fisheries before the spawning season (January, February and March, for each length class and year. In order to obtain a single fitness ratio (K–mean per year we determined the average for all length classes. We also evaluated Le Cren’s condition index (KLC. We observed significant positive correlations between the atmospheric oscillations and both physical condition indexes. In the case of K–mean, the AO explained 75% of the observed variability. Regarding KLC, the NAO explained approximately 73% of the observed variability, while the AO explained 70% of the observed variability. The increase in physical conditions of bluefin tuna in association with positive atmospheric oscillations could be mediated by the increase in the prevalence of strong trade winds. We concluded that the increase in the prevalence of strong westerly winds, mediated by a positive AO or NAO, favours the trip from the Atlantic to the Mediterranean by reducing energy costs due to migration and by increasing the supply of nutrients at the surface by the mixing of deep water and surface water in local areas such as the Strait of Gibraltar.

  20. Changes in flavonoids of sliced and fried yellow onions (allium cepa L. var. zittauer) during storage at different atmospheric, temperature and light conditions

    DEFF Research Database (Denmark)

    Islek, Merve; Nilufer-Erdil, Dilara; Knuthsen, Pia

    2015-01-01

    Flavonoid changes in sliced and fried onions which were packed and stored at different atmospheric conditions (air, nitrogen and vacuum), temperatures (ambient, +5 and -18C) and light (dark or light) were investigated. Flavonoids were extracted using accelerated solvent extraction and analyzed us......, or -18C, vacuum or nitrogen atmosphere, under dark, preserved flavonoids for 21 days, whereas for fried onions, 7 days of storage at +5C, vacuum atmosphere under dark resulted in highest flavonoid content. © 2014 Wiley Periodicals, Inc.......Flavonoid changes in sliced and fried onions which were packed and stored at different atmospheric conditions (air, nitrogen and vacuum), temperatures (ambient, +5 and -18C) and light (dark or light) were investigated. Flavonoids were extracted using accelerated solvent extraction and analyzed...... using ultra performance liquid chromatography coupled with photodiode array detector. Total flavonoid content, quercetin-3,4'-O-diglucoside and quercetin-4'-O-monoglucoside contents in sliced reference onion samples were found as 1,570±176, 926±105 and 564±64μg q.e./g d.w., respectively. Frying did...

  1. Vertical variations in the turbulent structure of the surface boundary layer over vineyards under unstable atmospheric conditions

    Science.gov (United States)

    Due to their highly-structured canopy, turbulent characteristics within and above vineyards, may not conform to those typically exhibited by other agricultural and natural ecosystems. Using data collected as a part of the Grape Remote sensing and Atmospheric Profiling and Evapotranspiration Experime...

  2. Stability of water clusters on hydronium ions formed under the conditions of radioactive contamination of the atmosphere

    International Nuclear Information System (INIS)

    Shevkunov, S.V.

    1998-01-01

    The hydronium ion hydrate shell H 3 O + , formed by addition of water molecule to proton is studied with the purpose of explaining the experimentally observed noticeable accumulation of ions by the atmosphere radioactive contamination. The results of computerized simulation of water clusters on hydronium ions testify to the clearly expressed stabilizing role of the proton electrical field

  3. In the ideal condition an experimental study on migration of radon and its daughters in the atmosphere

    International Nuclear Information System (INIS)

    Zeng Bing; Zhang Jinzhao; Wang Qing

    2010-01-01

    According to the relevant theory of thermodynamics, this presentation which based on the radon migration of the cluster theory has deduced ordinarily the ideal velocity period and displacement. The purpose was to establish the theoretical model of migration of radon and its daughters in the atmosphere in the ideal case, which would provide a underlying theoretical basis for the further research. (authors)

  4. A climatological analysis of high-precipitation events in Dronning Maud Land, Antarctica, and associated large-scale atmospheric conditions

    NARCIS (Netherlands)

    Welker, Christoph; Martius, Olivia; Froidevaux, Paul; Reijmer, Carleen H.; Fischer, Hubertus

    2014-01-01

    The link between high precipitation in Dronning Maud Land (DML), Antarctica, and the large-scale atmospheric circulation is investigated using ERA-Interim data for 1979-2009. High-precipitation events are analyzed at Halvfarryggen situated in the coastal region of DML and at Kohnen Station located

  5. Fire weather conditions and fire-atmosphere interactions observed during low-intensity prescribed fires - RxCADRE 2012

    Science.gov (United States)

    Craig B. Clements; Neil P. Lareau; Daisuke Seto; Jonathan Contezac; Braniff Davis; Casey Teske; Thomas J. Zajkowski; Andrew T. Hudak; Benjamin C. Bright; Matthew B. Dickinson; Bret W. Butler; Daniel Jimenez; J. Kevin. Hiers

    2016-01-01

    The role of fire-atmosphere coupling on fire behaviour is not well established, and to date few field observations have been made to investigate the interactions between fire spread and fire-induced winds. Therefore, comprehensive field observations are needed to better understand micrometeorological aspects of fire spread. To address this need, meteorological...

  6. Non-isothermal compositional liquid gas Darcy flow: formulation, soil-atmosphere boundary condition and application to high energy geothermal simulations

    OpenAIRE

    Beaude, Laurence; Brenner, Konstantin; Lopez, Simon; Masson, Roland; Smai, Farid

    2018-01-01

    This article deals with the modelling and formulation of compositional gas liquid Darcy flow. Our model includes an advanced boundary condition at the interface between the porous medium and the atmosphere accounting for convective mass and energy transfer, liquid evaporation and liquid outflow. The formulation is based on a fixed set of unknowns whatever the set of present phases. The thermody-namic equilibrium is expressed as complementary constraints. The model and its formulation are appl...

  7. The influence of seeding conditions and shielding gas atmosphere on the synthesis of silver nanowires through the polyol process

    Science.gov (United States)

    Chen, Chang; Wang, Li; Jiang, Guohua; Yang, Qiang; Wang, Jianjun; Yu, Haojie; Chen, Tao; Wang, Chiliang; Chen, Xu

    2006-01-01

    The polyol process including the introduction of preformed seeds and the inducement of poly(vinyl pyrrolidone) (PVP) has been developed as a powerful approach for synthesizing silver nanowires. Here, silver nanowires without other metal elements as impurities were synthesized through a silver seeding polyol process in a shielding gas atmosphere. It is demonstrated that the first seeding step is critical in obtaining silver nanowires as the principal product, and we also observe that the shielding gas atmosphere not only improves the repeatability of experiments but also affects the morphology of the final product. We obtained nanocubes with hydrogen gas shielding in a short reaction time; these would scarcely appear with argon or air shielding. Our work supplies new evidence to explain the actual growth mechanism of silver nanowires.

  8. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1994-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets, with a few more additions - with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers - exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the foree of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc. (orig.)

  9. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1993-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

  10. In-soil radon anomalies as precursors of earthquakes: a case study in the SE slope of Mt. Etna in a period of quite stable weather conditions

    International Nuclear Information System (INIS)

    Vizzini, Fabio; Brai, Maria

    2012-01-01

    In-soil radon concentrations as well as climatic parameters (temperature, atmospheric pressure and relative humidity) were collected in St. Venerina (Eastern Sicily – Italy) from March 19th to May 22nd 2009, close to an active fault system called Timpe Fault System (TFS), which is strictly linked to the geodynamics of Mt. Etna. During the monitoring period no drastic climatic variations were observed and, on the other hand, important seismic events were recorded close to the monitoring site. A seismic swarm composed of 5 earthquakes was observed in the Milo area on March 25th (M max = 2.7) at just 5.1 km from the site, and on May 13th an earthquake of 3.6 magnitude was recorded in the territory of St. Venerina, at just 3.2 km from the site; the earthquake was felt by the population and reported by all local and regional media. The in-soil radon concentrations have shown anomalous increases possibly linked to the earthquakes recorded, but certainly not attributable to local meteorology. To verify this assumption the average radon concentration and the standard deviation (σ) have been calculated and the regions of ±1.5σ and ±2σ deviation from the average concentration have been investigated. Moreover, to further minimise the contribution of the meteorological parameters on the in-soil radon fluctuations, a multiple regressions method has been used. To distinguish those earthquakes which could generate in-soil radon anomalies as precursors, the Dobrovolsky radius has been applied. The results obtained suggests that a clear correlation between earthquakes and in-soil radon increases exist, and that the detection of the in-soil radon anomalies becomes surely simpler in particular favourable conditions: weather stability, earthquakes within the Dobrovolsky radius and close to the monitoring area. Moreover, the absence of large variations of the climatic parameters, which could generate incoherent noise components to the radon signal, has made the radon

  11. In-soil radon anomalies as precursors of earthquakes: a case study in the SE slope of Mt. Etna in a period of quite stable weather conditions.

    Science.gov (United States)

    Vizzini, Fabio; Brai, Maria

    2012-11-01

    In-soil radon concentrations as well as climatic parameters (temperature, atmospheric pressure and relative humidity) were collected in St. Venerina (Eastern Sicily - Italy) from March 19th to May 22nd 2009, close to an active fault system called Timpe Fault System (TFS), which is strictly linked to the geodynamics of Mt. Etna. During the monitoring period no drastic climatic variations were observed and, on the other hand, important seismic events were recorded close to the monitoring site. A seismic swarm composed of 5 earthquakes was observed in the Milo area on March 25th (M(max) = 2.7) at just 5.1 km from the site, and on May 13th an earthquake of 3.6 magnitude was recorded in the territory of St. Venerina, at just 3.2 km from the site; the earthquake was felt by the population and reported by all local and regional media. The in-soil radon concentrations have shown anomalous increases possibly linked to the earthquakes recorded, but certainly not attributable to local meteorology. To verify this assumption the average radon concentration and the standard deviation (σ) have been calculated and the regions of ±1.5σ and ±2σ deviation from the average concentration have been investigated. Moreover, to further minimise the contribution of the meteorological parameters on the in-soil radon fluctuations, a multiple regressions method has been used. To distinguish those earthquakes which could generate in-soil radon anomalies as precursors, the Dobrovolsky radius has been applied. The results obtained suggests that a clear correlation between earthquakes and in-soil radon increases exist, and that the detection of the in-soil radon anomalies becomes surely simpler in particular favourable conditions: weather stability, earthquakes within the Dobrovolsky radius and close to the monitoring area. Moreover, the absence of large variations of the climatic parameters, which could generate incoherent noise components to the radon signal, has made the radon fluctuations

  12. Modeling of methane bubbles released from large sea-floor area: Condition required for methane emission to the atmosphere

    OpenAIRE

    Yamamoto, A.; Yamanaka, Y.; Tajika, E.

    2009-01-01

    Massive methane release from sea-floor sediments due to decomposition of methane hydrate, and thermal decomposition of organic matter by volcanic outgassing, is a potential contributor to global warming. However, the degree of global warming has not been estimated due to uncertainty over the proportion of methane flux from the sea-floor to reach the atmosphere. Massive methane release from a large sea-floor area would result in methane-saturated seawater, thus some methane would reach the atm...

  13. Oceanic and atmospheric conditions associated with the pentad rainfall over the southeastern peninsular India during the North-East Indian Monsoon season

    Science.gov (United States)

    Shanmugasundaram, Jothiganesh; Lee, Eungul

    2018-03-01

    The association of North-East Indian Monsoon rainfall (NEIMR) over the southeastern peninsular India with the oceanic and atmospheric conditions over the adjacent ocean regions at pentad time step (five days period) was investigated during the months of October to December for the period 1985-2014. The non-parametric correlation and composite analyses were carried out for the simultaneous and lagged time steps (up to four lags) of oceanic and atmospheric variables with pentad NEIMR. The results indicated that NEIMR was significantly correlated: 1) positively with both sea surface temperature (SST) led by 1-4 pentads (lag 1-4 time steps) and latent heat flux (LHF) during the simultaneous, lag 1 and 2 time steps over the equatorial western Indian Ocean, 2) positively with SST but negatively with LHF (less heat flux from ocean to atmosphere) during the same and all the lagged time steps over the Bay of Bengal. Consistently, during the wet NEIMR pentads over the southeastern peninsular India, SST significantly increased over the Bay of Bengal during all the time steps and the equatorial western Indian Ocean during the lag 2-4 time steps, while the LHF decreased over the Bay of Bengal (all time steps) and increased over the Indian Ocean (same, lag 1 and 2). The investigation on ocean-atmospheric interaction revealed that the enhanced LHF over the equatorial western Indian Ocean was related to increased atmospheric moisture demand and increased wind speed, whereas the reduced LHF over the Bay of Bengal was associated with decreased atmospheric moisture demand and decreased wind speed. The vertically integrated moisture flux and moisture transport vectors from 1000 to 850 hPa exhibited that the moisture was carried away from the equatorial western Indian Ocean to the strong moisture convergence regions of the Bay of Bengal during the same and lag 1 time steps of wet NEIMR pentads. Further, the moisture over the Bay of Bengal was transported to the southeastern peninsular

  14. Evidence of weak land-atmosphere coupling under varying bare soil conditions: Are fully coupled Darcy/Navier-Stokes models necessary for simulating soil moisture dynamics?

    Science.gov (United States)

    Illangasekare, T. H.; Trautz, A. C.; Howington, S. E.; Cihan, A.

    2017-12-01

    It is a well-established fact that the land and atmosphere form a continuum in which the individual domains are coupled by heat and mass transfer processes such as bare-soil evaporation. Soil moisture dynamics can be simulated at the representative elementary volume (REV) scale using decoupled and fully coupled Darcy/Navier-Stokes models. Decoupled modeling is an asynchronous approach in which flow and transport in the soil and atmosphere is simulated independently; the two domains are coupled out of time-step via prescribed flux parameterizations. Fully coupled modeling in contrast, solves the governing equations for flow and transport in both domains simultaneously with the use of coupling interface boundary conditions. This latter approach, while being able to provide real-time two-dimensional feedbacks, is considerably more complex and computationally intensive. In this study, we investigate whether fully coupled models are necessary, or if the simpler decoupled models can sufficiently capture soil moisture dynamics under varying land preparations. A series of intermediate-scale physical and numerical experiments were conducted in which soil moisture distributions and evaporation estimates were monitored at high spatiotemporal resolutions for different heterogeneous packing and soil roughness scenarios. All experimentation was conducted at the newly developed Center for Experimental Study of Subsurface Environmental Processes (CESEP) wind tunnel-porous media user test-facility at the Colorado School of. Near-surface atmospheric measurements made during the experiments demonstrate that the land-atmosphere coupling was relatively weak and insensitive to the applied edaphic and surface conditions. Simulations with a decoupled multiphase heat and mass transfer model similarly show little sensitivity to local variations in atmospheric forcing; a single, simple flux parameterization can sufficiently capture the soil moisture dynamics (evaporation and redistribution

  15. conditions

    Directory of Open Access Journals (Sweden)

    M. Venkatesulu

    1996-01-01

    Full Text Available Solutions of initial value problems associated with a pair of ordinary differential systems (L1,L2 defined on two adjacent intervals I1 and I2 and satisfying certain interface-spatial conditions at the common end (interface point are studied.

  16. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  17. Visible spectroscopy as a tool for the assessment of storage conditions of fresh pork packaged in modified atmosphere

    DEFF Research Database (Denmark)

    Spanos, Dimitrios; Christensen, Mette; Ann Tørngren, Mari

    2016-01-01

    The storage conditions of fresh meat are known to impact its colour and microbial shelf life. In the present study, visible spectroscopy was evaluated as a method to assess meat storage conditions and its optimisation. Fresh pork steaks (longissimus thoracis et lumborum and semimembranosus) were...

  18. Modelling the prey detection performance of Rhinonicteris aurantia (Chiroptera: Hipposideridae) in different atmospheric conditions discounts the notional role of relative humidity in adaptive evolution.

    Science.gov (United States)

    Armstrong, Kyle N; Kerry, Leonard J

    2011-06-07

    We examined a recent notion that differences in echolocation call frequency amongst geographic groups of constant frequency (CF)-emitting bats is the result of a trade-off between maximising prey detection range at lower frequencies and enhancing small-prey resolution at higher frequencies in different atmospheric (relative humidity; RH) environments. Isolated populations of the endemic Australian orange leaf-nosed bat Rhinonicteris aurantia were used as an example since geographic isolation in different environments has been a precursor to differences in their characteristic echolocation call frequencies (mean difference c. 6 kHz; means of 114.64 and 120.99 kHz). The influence of both atmospheric temperature and RH on maximum prey detection range was explored through mathematical modelling. This revealed that temperature was of similar importance to relative humidity and that under certain circumstances, each could reduce the effect of the other on ultrasound attenuation rates. The newly developed models contain significant conceptual improvements in method compared to other recent approaches, and can be applied to the situation of any other species of bat. For a given set of atmospheric conditions, the prey detection range of R. aurantia was reduced slightly when call frequency increased by 6 kHz, but an increase in RH, temperature or both reduced detection range significantly. A similar trend was also evident in prey detection volume ratios calculated for the same conditions. Spatial volume ratios were applied to assess the impact of changed atmospheric conditions and prey size on foraging ecology. Reductions in detection range associated with increases in RH and/or temperature also varied in relation to the size (cross sectional area) of insect prey. Modelling demonstrated that small (6 kHz) movements in call frequency could not compensate for the changes in prey detection range and spatial detection volumes that result from significant changes in atmospheric

  19. Transmitter Spatial Diversity for FSO Uplink in Presence of Atmospheric Turbulence and Weather Conditions for Different IM Schemes

    Science.gov (United States)

    Viswanath, Anjitha; Kumar Jain, Virander; Kar, Subrat

    2017-12-01

    We investigate the error performance of an earth-to-satellite free space optical uplink using transmitter spatial diversity in presence of turbulence and weather conditions, using gamma-gamma distribution and Beer-Lambert law, respectively, for on-off keying (OOK), M-ary pulse position modulation (M-PPM) and M-ary differential PPM (M-DPPM) schemes. Weather conditions such as moderate, light and thin fog cause additional degradation, while dense or thick fog and clouds may lead to link failure. The bit error rate reduces with increase in the number of transmitters for all the schemes. However, beyond a certain number of transmitters, the reduction becomes marginal. Diversity gain remains almost constant for various weather conditions but increases with increase in ground-level turbulence or zenith angle. Further, the number of transmitters required to improve the performance to a desired level is less for M-PPM scheme than M-DPPM and OOK schemes.

  20. Methylamphetamine synthesis: does an alteration in synthesis conditions affect the δ(13) C, δ(15) N and δ(2) H stable isotope ratio values of the product?

    Science.gov (United States)

    Salouros, Helen; Collins, Michael; Cawley, Adam; Longworth, Mitchell

    2012-05-01

    Conventional chemical profiling of methylamphetamine has long been employed by national forensic laboratories to determine the synthetic route and where possible the precursor chemicals used in its manufacture. This laboratory has been studying the use of stable isotope ratio mass spectrometry (IRMS) analysis as a complementary technique to conventional chemical profiling of fully synthetic illicit drugs such as methylamphetamine. As part of these investigations the stable carbon (δ(13) C), nitrogen (δ(15) N), and hydrogen (δ(2) H) isotope values in the precursor chemicals of ephedrine and pseudoephedrine and the resulting methylamphetamine end-products have been measured to determine the synthetic origins of methylamphetamine. In this study, results are presented for δ(13) C, δ(15) N, and δ(2) H values in methylamphetamine synthesized from ephedrine and pseudoephedrine by two synthetic routes with varying experimental parameters. It was demonstrated that varying parameters, such as stoichiometry, reaction temperature, reaction time, and reaction pressure, had no effect on the δ(13) C, δ(15) N, and δ(2) H isotope values of the final methylamphetamine product, within measurement uncertainty. Therefore the value of the IRMS technique in identifying the synthetic origin of precursors, such as ephedrine and pseudoephedrine, is not compromised by the potential variation in synthetic method that is expected from one batch to the next, especially in clandestine laboratories where manufacture can occur without stringent quality control of reactions. Copyright © 2011 John Wiley & Sons, Ltd.

  1. Exchange of Volatile Organic Compounds (VOCs) at the Atmosphere-Soil Interface under Ambient Conditions: a Coated-Wall Flow Tube Study

    Science.gov (United States)

    Su, H.; Li, G.; Kuhn, U.; Meusel, H.; Poeschl, U.; Shao, M.; Cheng, Y.

    2016-12-01

    Volatile organic compounds (VOCs) represent a large fraction of organic carbon in the atmosphere and play an important role in atmospheric chemistry. Deep insight into the VOCs-related tropospheric chemistry requires a profound understanding of sources and sinks of different VOCs species. Multiphase processes on the surface of soil and airborne soil-derived particles have been suggested as an important mechanism for the production/removal of atmospheric trace gases and aerosols. In this work, we investigated the exchange of 13 species of VOCs at the atmosphere-soil interface using a coated-wall flow tube system coupled to a PTR-MS, under ambient conditions at an urban background site in Beijing. The results show that most of the species tend to be absorbed/adsorbed and further retained or converted into other products by soil (net influx into soil) while formic acid can most probably be produced by soil either due to chemical transformation of other absorbed/adsorbed species or emission from soil itself (net efflux from soil). For the species showing noticeable uptake, their uptake coefficients display a gradually decrease along the measurement time, suggesting a progressive saturation of the soil surface. The uptake of several species (e.g., methanol, acetic acid and formaldehyde), however, don't exhibit marked dependence on time. Correlation studies show a dependence of uptake on temperature or relative humidity for several species: the uptake of methanol, acetic acid and methyl ethyl ketone (MEK) decreases with increasing temperature; and the uptake of isoprene, acetaldehyde and methyl vinyl ketone/methacrolein (MVK+MACR) increases with increasing relative humidity. Based on our results, mineral soil serves as a sink rather than a source for most VOC species.

  2. Quality of Meat (Longissimus dorsi) from Male Fallow Deer (Dama dama) Packaged and Stored under Vacuum and Modified Atmosphere Conditions.

    Science.gov (United States)

    Piaskowska, N; Daszkiewicz, T; Kubiak, D; Zapotoczny, P

    2016-12-01

    This study evaluated the effect of vacuum and modified atmosphere (40% CO 2 +60% N 2 , MA) packaging on the chemical composition, physicochemical properties and sensory attributes of chill-stored meat from 10 fallow deer ( Dama dama ) bucks at 17 to 18 months of age. The animals were hunter-harvested in the forests of north-eastern Poland. During carcass dressing (48 to 54 h post mortem), both musculus longissimus muscles were cut out. Each muscle was divided into seven sections which were allocated to three groups: 0, A, and B. Samples 0 were immediately subjected to laboratory analyses. Samples A were vacuum-packaged, and samples B were packaged in MA. Packaged samples were stored for 7, 14, and 21 days at 2°C. The results of the present study showed that the evaluated packaging systems had no significant effect on the quality of fallow deer meat during chilled storage. However, vacuum-packaged meat samples were characterised by greater drip loss. Vacuum and MA packaging contributed to preserving the desired physicochemical properties and sensory attributes of meat during 21 days of storage. Regardless of the packaging method used, undesirable changes in the colour, water-holding capacity and juiciness of meat, accompanied by tenderness improvement, were observed during chilled storage.

  3. SHARC (Strategic High-Altitude Radiance Code). A computer model for calculating atmospheric radiation under non-equilibrium conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R.; Ratkowski, A.J.; Sundberg, R.L.; Duff, J.W.; Bernstein, L.S.

    1989-02-01

    The Strategic High-Altitude Radiance Code (SHARC ) is a new computer code that calculates atmospheric radiation for paths from 60 to 300 km altitude in the 2-40 micro spectral region. It models radiation due to NLTE (Non-Local Thermodynamic Equilibrium) molecular emissions which are the dominant sources at these altitudes. The initial version of SHARC, which is described in this paper, includes the five strongest IR radiators, CO/sub 2/, NO, O/sub 3/, H/sub 2/O and CO. Calculation of excited state populations is accomplished by interfacing a Monte Carlo model for radiative excitation and energy transfer with a highly flexible chemical kinetics module derived from the Sandia CHEMKIN Code. An equivalent-width, line-by-line approach for the radiation transport gives a spectral resolution of about 0.50/cm. The radiative-transport calculation includes the effects of combined Doppler-Lorentz (Voigt) line shapes. Particular emphasis was placed on modular construction and supporting data files so that models and model parameters can be modified or upgraded as additional data become available. The initial version of SHARC is now ready for distribution.

  4. Effect of irradiation and modified atmosphere packaging on the microbiological safety of minced pork stored under temperature abuse conditions

    International Nuclear Information System (INIS)

    Grant, I.R.; Patterson, M.F.

    1991-01-01

    The safety of irradiated pork packed in 25% CO 2 :75% N 2 and stored at abuse temperature (10 or 15°C) was assessed by inoculation studies involving Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Yersinia enterocolitica and Clostridium perfringens. Irradiation to a dose of 1.75 kGy reduced pathogen numbers to below the detection limit of 10 2 cells g -1 . When higher inoculum levels were used (10 6 cells g -1 ) irradiation at 1.75 kGy reduced pathogen numbers by 1 –>5 log 10 cycles depending on strain. Clostridium perfringens was the most resistant, and Y. enterocolitica the most sensitive of the pathogens studied. In all cases when high numbers (10 6 to 10 7 g -1 ) of spoilage and/or pathogenic bacteria were present initially on the pork the meat appeared spoiled, and although irradiation reduced the number of microorganisms, the meat was still unacceptable from a sensory viewpoint after treatment. It was concluded that the microbiological safety of irradiated, modified atmosphere packaged (MAP) pork is better than that of unirradiated MAP pork

  5. 400 years of summer climatic conditions in the N Carpathian Mts. (eastern Europe) based on O and C stable isotopes in Pinus Cembra L tree rings

    Science.gov (United States)

    Nagavciuc, Viorica; Popa, Ionel; Kern, Zoltán; Persoiu, Aurel

    2016-04-01

    For a better understanding of how the climate is changing and how the environment responds to these changes, it is necessary to understand how the climate has varied in the past. Romania's virgin forests have a great potential to obtain long tree-ring chronologies with annual resolution; but so far, only a few studies resulted in quantitative paleoclimatic reconstructions. In this context, the aim of this study is 1) to calibrate the relationship between the stable isotopes of oxygen and carbon in tree rings and the main climatic parameters and determine the potential of Pinus cembra (Cǎlimani Mts., N Romania, Eastern Europe) for paleoclimatic reconstructions; 2) to provide the first palaeoclimatic reconstitution in Romania based on the isotopic composition of oxygen and carbon in tree ring cellulose, and 3) to test the hypothesis that nearby sulphur mines have not altered the climatic signal recorded by the stable isotopic composition of tree rings, contrary to the similar signal recorded by TRW. For this study, we have analysed wood samples of Swiss stone pine (Pinus cembra L.) from living and dead trees from Cǎlimani Mts., NE Romania, aged between 1600 and 2012 AD. The isotopic composition of oxygen and carbon from the cellulose was analysed at the Institute for Geological and Geochemical Research, Budapest, Hungary, using a high-temperature pyrolysis system (Thermo Quest TC-EA) coupled to an isotope ratio mass spectrometer (Thermo Finningan Delta V) following a ring by ring (i.e., non-pooled) approach. The average level of δ18O and δ13C in cellulose for the period 1600-2012 was 28.83‰ and -22.63 ‰. The tree ring cellulose δ18O and δ13C values showed a strong positive correlation with maximum air temperature (r = 0.6 for δ18O and r = 0.5 for δ13C), mean temperature (r = 0.6 for δ18O and r = 0.45 for δ13C), and sunshine duration (r = 0.69 for δ18O) and negatively correlated with precipitation amount (r = -0.5 for δ18O and r = 0.3 for δ13C) and

  6. Extraction of compositional and hydration information of sulfates from laser-induced plasma spectra recorded under Mars atmospheric conditions - Implications for ChemCam investigations on Curiosity rover

    Energy Technology Data Exchange (ETDEWEB)

    Sobron, Pablo, E-mail: pablo.sobron@asc-csa.gc.ca [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, St. Louis, MO 63130 (United States); Wang, Alian [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, St. Louis, MO 63130 (United States); Sobron, Francisco [Unidad Asociada UVa-CSIC a traves del Centro de Astrobiologia, Parque Tecnologico de Boecillo, Parcela 203, Boecillo (Valladolid), 47151 (Spain)

    2012-02-15

    Given the volume of spectral data required for providing accurate compositional information and thereby insight in mineralogy and petrology from laser-induced breakdown spectroscopy (LIBS) measurements, fast data processing tools are a must. This is particularly true during the tactical operations of rover-based planetary exploration missions such as the Mars Science Laboratory rover, Curiosity, which will carry a remote LIBS spectrometer in its science payload. We have developed: an automated fast pre-processing sequence of algorithms for converting a series of LIBS spectra (typically 125) recorded from a single target into a reliable SNR-enhanced spectrum; a dedicated routine to quantify its spectral features; and a set of calibration curves using standard hydrous and multi-cation sulfates. These calibration curves allow deriving the elemental compositions and the degrees of hydration of various hydrous sulfates, one of the two major types of secondary minerals found on Mars. Our quantitative tools are built upon calibration-curve modeling, through the correlation of the elemental concentrations and the peak areas of the atomic emission lines observed in the LIBS spectra of standard samples. At present, we can derive the elemental concentrations of K, Na, Ca, Mg, Fe, Al, S, O, and H in sulfates, as well as the hydration degrees of Ca- and Mg-sulfates, from LIBS spectra obtained in both Earth atmosphere and Mars atmospheric conditions in a Planetary Environment and Analysis Chamber (PEACh). In addition, structural information can be potentially obtained for various Fe-sulfates. - Highlights: Black-Right-Pointing-Pointer Routines for LIBS spectral data fast automated processing. Black-Right-Pointing-Pointer Identification of elements and determination of the elemental composition. Black-Right-Pointing-Pointer Calibration curves for sulfate samples in Earth and Mars atmospheric conditions. Black-Right-Pointing-Pointer Fe curves probably related to the crystalline

  7. Near-bottom water warming in the Laptev Sea in response to atmospheric and sea-ice conditions in 2007

    Directory of Open Access Journals (Sweden)

    Jens A. Hölemann

    2011-05-01

    Full Text Available In this paper we present new data from ship-based measurements and two-year observations from moorings in the Laptev Sea along with Russian historical data. The observations from the Laptev Sea in 2007 indicate that the bottom water temperatures on the mid-shelf increased by more than 3°C compared to the long-term mean as a consequence of the unusually high summertime surface water temperatures. Such a distinct increase in near-bottom temperatures has not been observed before. Remnants of the relatively warm bottom water occupied the mid-shelf from September 2007 until April 2008. Strong polynya activity during March to May 2007 caused more summertime open water and therefore warmer sea surface temperatures in the Laptev Sea. During the ice-free period in August and September 2007, the prevailing cyclonic atmospheric circulation deflected the freshwater plume of the River Lena to the east, which increased the salinity on the mid-shelf north of the Lena Delta. The resulting weaker density stratification allowed more vertical mixing of the water column during storms in late September and early October, leading to the observed warming of the near-bottom layer in the still ice-free Laptev Sea. In summer and autumn 2008, when the density stratification was stronger and sea surface temperatures were close to the long-term mean, no near-bottom water warming was observed. Warmer water temperatures near the seabed may also impact the stability of the shelf's submarine permafrost.

  8. Features and range of the FSO by use of the OFDM and QAM modulation in different atmospheric conditions

    Science.gov (United States)

    Andrej, Liner; Perecar, Frantisek; Jaros, Jakub; Papes, Martin; Koudelka, Petr; Latal, Jan; Cubik, Jakub; Vasinek, Vladimir

    2014-05-01

    The FSO (Free Space Optics) communication uses the visible or infrared light for transmission. As well as cable optics FSO also uses laser for the data transmission, but the data flow is not transmitted in the fiber but in the air. This technology does not require expensive fiber optic cables and or ensure the licensing zone as it is in the case of radio networks. As well as in the cable transmissions are different modulations used. Nowadays, the most used modulations are QAM and OFDM. OFDM belongs to the border group of modulations with more carrier waves, where the information's are transmitted via subcarrier waves with lower data flow and baud rate. It is mainly used in broadband wire and wireless communications. OFDM provides very high signal resistance against the interference, chromatic dispersion (CD) and polarization mode dispersion (PMD)[l]. Modulation method involves the use of several hundreds to thousands of subcarrier waves. QAM is a composite modulation, which uses for symbol creation the combination of ASK (Amplitude Shift Keying) and PSK (Phase Shift Keying). Each state is represented by a specific value of the amplitude and phase. It's actually multistate modulation, which is able to transmit n bits by m symbols. That means that more bits are transferred at one moment. This paper deals with the modulations used in FSO. Most used modulation in FSO is OOK (On-Off Keying) , but modulations OFDM and QAM are (modulation ) ways of the future. The main task was to determine how much is the reach of modulations changing with the changes of density (visibility) of fog and the set transceiver power. As software environment for simulations has been used OptiSystem program. For the simulation of the atmosphere the FSO component has been used. In this component were simulated attenuations, which are responding to varying densities of fog [2]. At different intensities of fog were changing the received power.

  9. Modeling char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

    DEFF Research Database (Denmark)

    Brix, Jacob; Jensen, Peter Arendt; Jensen, Anker Degn

    2011-01-01

    The aim of this investigation has been to model combustion under suspension fired conditions in O2/N2 and O2/CO2 mixtures. Experiments used for model validation have been carried out in an electrically heated Entrained Flow Reactor (EFR) at temperatures between 1173 K and 1673 K with inlet O2...... concentrations between 5 and 28 vol.%. The COal COmbustion MOdel, COCOMO, includes the three char morphologies: cenospheric char, network char and dense char each divided between six discrete particle sizes. Both combustion and gasification with CO2 are accounted for and reaction rates include thermal char...... deactivation, which was found to be important for combustion at high reactor temperatures and high O2 concentrations. COCOMO show in general good agreement with experimental char conversion profiles at conditions covering zone I–III. From the experimental profiles no effect of CO2 gasification on char...

  10. The regimes of twin-fluid jet-in-crossflow at atmospheric and jet-engine operating conditions

    Science.gov (United States)

    Tan, Zu Puayen; Bibik, Oleksandr; Shcherbik, Dmitriy; Zinn, Ben T.; Patel, Nayan

    2018-02-01

    The "Twin-Fluid Jet-in-Crossflow (TF-JICF)" is a nascent variation of the classical JICF, in which a liquid jet is co-injected with an annular sleeve of gas into a gaseous crossflow. Jet-engine designers are interested in using TF-JICF for liquid-fuel injection and atomization in the next-generation combustors because it is expected to minimize combustor-damaging auto-ignition and fuel-coking tendencies. However, experimental data of TF-JICF are sparse. Furthermore, a widely accepted TF-JICF model that correlates the spray's penetration to the combined liquid-gas momentum-flux ratio (Jeff) is increasingly showing discrepancy with emerging results, suggesting a gap in the current understanding of TF-JICF. This paper describes an investigation that addressed the gap by experimentally characterizing the TF-JICF produced by a single injector across wide ranges of operating conditions (i.e., jet-A injectant, crossflow of air, crossflow Weber number = 175-1050, crossflow pressure Pcf = 1.8-9.5 atm, momentum-flux ratio J = 5-40, and air-nozzle dP = 0%-150% of Pcf). These covered the conditions previously used to develop the Jeff model, recently reported conditions that produced Jeff discrepancies, and high-pressure conditions found in jet-engines. Dye-based shadowgraph was used to acquire high-resolution (13.52 μm/pixel) images of the TF-JICF, which revealed wide-ranging characteristics such as the disrupted Rayleigh-Taylor jet instabilities, air-induced jet corrugations, spray-bifurcations, and prompt-atomization. Analyses of the data showed that contrary to the literature, the TF-JICF's penetration is not monotonically related to Jeff. A new conceptual framework for TF-JICF is proposed, where the flow configuration is composed of four regimes, each having different penetration trends, spray structures, and underlying mechanisms.

  11. Bartolome Island, Galapagos Stable Oxygen Calibration Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Galapagos Coral Stable Oxygen Calibration Data. Sites: Bartolome Island: 0 deg, 17'S, 90 deg 33' W. Champion Island: 1 deg, 15'S, 90 deg, 05' W. Urvina Bay (Isabela...

  12. Late-Holocene hydroclimate and atmospheric circulation variability in southern Patagonia: insights from triple stable isotopes (δ18O, δ13C, δD) of peat bog Sphagnum moss

    Science.gov (United States)

    Xia, Z.; Yu, Z.; Zheng, Y.; Loisel, J.; Huang, Y.

    2017-12-01

    The Southern Hemisphere Westerly Winds (SHWWs) exert important influences on regional and global climates, but their long-term behaviors and dynamics are still poorly understood but critical for projecting future changes. Here we present a 5,500-year record from a Sphagnum-dominated peat bog located on the lee side of the Andes at 54.2 °S in southern Patagonia—based on plant macrofossils, Sphagnum cellulose δ18O and δ13C, and lipid δD data—to document and understand the variability in hydroclimate and atmospheric circulation. There is a striking negative correlation between cellulose δ18O and the Southern Annular Mode (SAM) index over the last millennium; particularly the 2.5‰ negative shift of δ18O is concurrent with the observed positive trend in the SAM over the recent decades. The interval of Medieval Climate Anomaly (MCA, 850-600 yr BP) is characterized by a 2.5‰ negative shift of δ18O and low δ13C values, while the Little Ice Age (LIA, 500-300 yr BP) is characterized by a 2.5‰ positive shift of δ18O and high δ13C values. Furthermore, we find the largest negative shift of δ18O ( 3‰) at 2,300 yr BP, suggesting a significantly positive shift in the SAM. We interpret high Sphagnum abundance and high cellulose δ13C values to reflect great moss moisture conditions, while cellulose δ18O variations primarily reflect moisture sources and atmospheric circulation. During the positive phase of SAM (e.g., the MCA and recent decades), strengthened SHWWs enhance the rain-shadow effect, resulting in dry climate and 18O-depleted precipitation (low δ18O values) in the study region. During the negative phase of SAM (e.g., the LIA), weakened SHWWs reduce rain-shadow effect, resulting in wet climate and high δ18O values caused by increases in moisture contributions from the southerly and easterly flows that do not experience strong Rayleigh distillation process during air mass transports. Furthermore, coupling cellulose δ18O and lipid δD enables

  13. Integration of an optical coherence tomography (OCT) system into an examination incubator to facilitate in vivo imaging of cardiovascular development in higher vertebrate embryos under stable physiological conditions

    DEFF Research Database (Denmark)

    Happel, Christoph M.; Thrane, Lars; Thommes, Jan

    2011-01-01

    High-resolution in vivo imaging of higher vertebrate embryos over short or long time periods under constant physiological conditions is a technically challenging task for researchers working on cardiovascular development. In chick embryos, for example, various studies have shown that without...... significance, should be documented under physiological conditions. However, previous studies were mostly carried out outside of an incubator or under suboptimal environmental conditions. Here we present, to the best of our knowledge, the first detailed description of an optical coherence tomography (OCT......) system integrated into an examination incubator to facilitate real-time in vivo imaging of cardiovascular development under physiological environmental conditions. We demonstrate the suitability of this OCT examination incubator unit for use in cardiovascular development studies by examples of proof...

  14. Analysis of changes in tornadogenesis conditions over Northern Eurasia based on a simple index of atmospheric convective instability

    Science.gov (United States)

    Chernokulsky, A. V.; Kurgansky, M. V.; Mokhov, I. I.

    2017-12-01

    A simple index of convective instability (3D-index) is used for analysis of weather and climate processes that favor to the occurrence of severe convective events including tornadoes. The index is based on information on the surface air temperature and humidity. The prognostic ability of the index to reproduce severe convective events (thunderstorms, showers, tornadoes) is analyzed. It is shown that most tornadoes in North Eurasia are characterized by high values of the 3D-index; furthermore, the 3D-index is significantly correlated with the available convective potential energy. Reanalysis data (for recent decades) and global climate model simulations (for the 21st century) show an increase in the frequency of occurrence of favorable for tornado formation meteorological conditions in the regions of Northern Eurasia. The most significant increase is found on the Black Sea coast and in the south of the Far East.

  15. Effect of irradiation, active and modified atmosphere packaging, container oxygen barrier and storage conditions on the physicochemical and sensory properties of raw unpeeled almond kernels (Prunus dulcis).

    Science.gov (United States)

    Mexis, Stamatios F; Riganakos, Kyriakos A; Kontominas, Michael G

    2011-03-15

    The present study investigated the effect of irradiation, active and modified atmosphere packaging, and storage conditions on quality retention of raw, whole, unpeeled almonds. Almond kernels were packaged in barrier and high-barrier pouches, under N(2) or with an O(2) absorber and stored either under fluorescent lighting or in the dark at 20 °C for 12 months. Quality parameters monitored were peroxide value, hexanal content, colour, fatty acid composition and volatile compounds. Of the sensory attributes colour, texture, odour and taste were evaluated. Peroxide value and hexanal increased with dose of irradiation and storage time. Irradiation resulted in a decrease of polyunsaturated and monounsaturated fatty acids during storage with a parallel increase of saturated fatty acids. Volatile compounds were not affected by irradiation but increased with storage time indicating enhanced lipid oxidation. Colour parameters of samples remained unaffected immediately after irradiation. For samples packaged under a N(2) , atmosphere L and b values decreased during storage with a parallel increase of value a resulting to gradual product darkening especially in irradiated samples. Non-irradiated almonds retained acceptable quality for ca. 12 months stored at 20 °C with the O(2) absorber irrespective of lighting conditions and packaging material oxygen barrier. The respective shelf life for samples irradiated at 1.0 kGy was 12 months packaged in PET-SiOx//LDPE irrespective of lighting conditions and 12 months for samples irradiated at 3 kGy packaged in PET-SiOx//LDPE stored in the dark. Copyright © 2010 Society of Chemical Industry.

  16. Atmospheric Photochemistry

    Science.gov (United States)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  17. Conditions for the formation and atmospheric dispersion of a toxic, heavy gas layer during thermal metamorphism of coal and evaporite deposits by sill intrusion

    Science.gov (United States)

    Storey, Michael; Hankin, Robin K. S.

    2010-05-01

    There is compelling evidence for massive discharge of volatiles, including toxic species, into the atmosphere at the end of the Permian. It has been argued that most of the gases were produced during thermal metamorphism of coal and evaporite deposits in the East Siberia Tunguska basin following sill intrusion (Retallack and Jahren, 2008; Svensen et al., 2009). The release of the volatiles has been proposed as a major cause of environmental and extinction events at the end of the Permian, with venting of carbon gases and halocarbons to the atmosphere leading to global warming and atmospheric ozone depletion (Svensen et al., 2009) Here we consider the conditions required for the formation and dispersion of toxic, heavier than air, gas plumes, made up of a mixture of CO2, CH4, H2S and SO2 and formed during the thermal metamorphism of C- and S- rich sediments. Dispersion models and density considerations within a range of CO2/CH4 ratios and volatile fluxes and temperatures, for gas discharge by both seepage and from vents, allow the possibility that following sill emplacement much of the vast East Siberia Tunguska basin was - at least intermittently - covered by a heavy, toxic gas layer that was unfavorable for life. Dispersion scenarios for a heavy gas layer beyond the Siberian region during end-Permian times will be presented. REFERENCES G. J. Retallack and A. H. Jahren, Methane release from igneous intrusion of coal during Late Permian extinction events, Journal of Geology, volume 116, 1-20, 2008 H. Svensen et al., Siberian gas venting and the end-Permian environmental crisis, Earth and Planetary Science Letters, volume 277, 490-500, 2009

  18. Highly active and stable ion-exchanged Fe–Ferrierite catalyst for N2O decomposition under nitric acid tail gas conditions

    NARCIS (Netherlands)

    Melián-Cabrera, I.; Mentruit, C.; Pieterse, J.A.Z.; Brink, R.W. van den; Mul, G.; Kapteijn, F.; Moulijn, J.A.

    2005-01-01

    This communication reports on the excellent performance and durability of a wet ion-exchanged Fe–Ferrierite catalysts for N2O decomposition under conditions of nitric acid plants, especially in the presence of water (0.5% vol) and at a high space time W/F0(N2O) = 900 kgcat s mol-1. In contrast to

  19. Heavy Rainfall Episodes in the Eastern Northeast Brazil Linked to Large-Scale Ocean-Atmosphere Conditions in the Tropical Atlantic

    Directory of Open Access Journals (Sweden)

    Yves K. Kouadio

    2012-01-01

    Full Text Available Relationships between simultaneous occurrences of distinctive atmospheric easterly wave (EW signatures that cross the south-equatorial Atlantic, intense mesoscale convective systems (lifespan > 2 hour that propagate westward over the western south-equatorial Atlantic, and subsequent strong rainfall episodes (anomaly > 10 mm·day−1 that occur in eastern Northeast Brazil (ENEB are investigated. Using a simple diagnostic analysis, twelve cases with EW lifespan ranging between 3 and 8 days and a mean velocity of 8 m·s−1 were selected and documented during each rainy season of 2004, 2005, and 2006. These cases, which represent 50% of the total number of strong rainfall episodes and 60% of the rainfall amount over the ENEB, were concomitant with an acceleration of the trade winds over the south-equatorial Atlantic, an excess of moisture transported westward from Africa to America, and a strengthening of the convective activity in the oceanic region close to Brazil. Most of these episodes occurred during positive sea surface temperature anomaly patterns over the entire south-equatorial Atlantic and low-frequency warm conditions within the oceanic mixing layer. A real-time monitoring and the simulation of this ocean-atmosphere relationship could help in forecasting such dramatic rainfall events.

  20. Effect of flue gas composition on deposit induced high temperature corrosion under laboratory conditions mimicking biomass firing. Part I: Exposures in oxidizing and chlorinating atmospheres

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Kiamehr, Saeed; Montgomery, Melanie

    2017-01-01

    only in an oxidizing-chlorinating atmosphere, otherwise corrosionresults in formation of a duplex oxide. Corrosion attack on deposit-coatedsamples was higher than on deposit-free samples irrespective of the gaseousatmosphere. Specifically, severe volatilization of alloying elements occurred ondeposit......In biomass fired power plants, deposition of alkali chlorides on superheaters, aswell as the presence of corrosive flue gas species, give rise to fast corrosion ofsuperheaters. In order to understand the corrosion mechanism under thiscomplex condition, the influence of the flue gas composition...... on hightemperature corrosion of an austenitic superheater material under laboratoryconditions mimicking biomass firing is investigated in this work. Exposuresinvolving deposit (KCl)-coated and deposit-free austenitic stainless steel (TP347H FG) samples were conducted isothermally at 560 8C for 72 h, under...

  1. An Investigation of the Role of Near-Anode Plasma Conditions on Anode Spot Self-Organization in Atmospheric Pressure DC Glows

    Science.gov (United States)

    Kovach, Yao; Foster, John

    2016-09-01

    In previous work, plasma self-organization patterns were experimentally observed on both liquid surface and metal anode surface in atmospheric pressure glows. However, the origin of the self-organized pattern formation is still poorly understood and is currently under study. In this work, it was observed that the discharge current is the dominant parameter controlling the onset of the self-organization of the plasma attachment on a liquid anode. On the other hand, it is observed that interelectrode spacing is the key parameter that controls plasma self-organization on metal anodes. Presented here are experiments aimed at understanding how these parameters control conditions at the anode surface which ultimately result in self-organization. Here we determine the effects of space charge at the anode surface and also estimate the anode fall voltage in response to discharge parameter variations. Additionally, electron microscopy is used to assess anode morphological changes resulting from the self-organization plasma attachments.

  2. Stable internal reference genes for the normalization of real-time PCR in different sweetpotato cultivars subjected to abiotic stress conditions.

    Directory of Open Access Journals (Sweden)

    Sung-Chul Park

    Full Text Available Reverse transcription quantitative real-time PCR (RT-qPCR has become one of the most widely used methods for gene expression analysis, but its successful application depends on the stability of suitable reference genes used for data normalization. In plant studies, the choice and optimal number of reference genes must be experimentally determined for the specific conditions, plant species, and cultivars. In this study, ten candidate reference genes of sweetpotato (Ipomoea batatas were isolated and the stability of their expression was analyzed using two algorithms, geNorm and NormFinder. The samples consisted of tissues from four sweetpotato cultivars subjected to four different environmental stress treatments, i.e., cold, drought, salt and oxidative stress. The results showed that, for sweetpotato, individual reference genes or combinations thereof should be selected for use in data normalization depending on the experimental conditions and the particular cultivar. In general, the genes ARF, UBI, COX, GAP and RPL were validated as the most suitable reference gene set for every cultivar across total tested samples. Interestingly, the genes ACT and TUB, although widely used, were not the most suitable reference genes in different sweetpotato sample sets. Taken together, these results provide guidelines for reference gene(s selection under different experimental conditions. In addition, they serve as a foundation for the more accurate and widespread use of RT-qPCR in various sweetpotato cultivars.

  3. Role of process conditions on the microstructure, stoichiometry and functional performance of atmospheric plasma sprayed La(Sr)MnO3 coatings

    Science.gov (United States)

    Han, Su Jung; Chen, Yikai; Sampath, Sanjay

    2014-08-01

    Strontium doped lanthanum manganite (LSM) perovskite coatings were produced via atmospheric plasma spray technique to examine their applicability as electrically conductive coatings to protect chromium-poisoning of cathode side metallic interconnects in solid oxide fuel cells. Various plasma spray process conditions were manipulated including plasma power, total gas flow and content of H2 in the plasma gas in order to understand their effects on coating properties as well as efficacy as a protectant against Cr-poisoning. In-flight temperatures and velocities of spray particles were monitored for the various plasma spray conditions enabling assessment of thermal and kinetic energies of LSM particles. As anticipated, coating density improves with increasing thermal and/or kinetic energies of the LSM particles. However, the LSM particles also experienced significant phase decomposition at higher thermal exposure and longer residence time conditions. Due to preferential loss of oxygen and manganese, La2O3 phase is also formed under certain processing regimes. The resultant mixed-phase coating is ineffective both from electrical transport and as a protective coating for the metallic interconnect. Concomitantly, coatings with limited decomposition show excellent conductivity and protection characteristics demonstrating the need for mechanism driven process optimization for these functional oxide coatings.

  4. Response of northern hemisphere environmental and atmospheric conditions to climate changes using Greenland aerosol records from the Eemian to the Holocene

    Science.gov (United States)

    Fischer, H.

    2017-12-01

    The Northern Hemisphere experienced dramatic climate changes over the last glacial cycle, including vast ice sheet expansion and frequent abrupt climate events. Moreover, high northern latitudes during the last interglacial (Eemian) were warmer than today and may provide guidance for future climate change scenarios. However, little evidence exists regarding the environmental alterations connected to these climate changes. Using aerosol concentration records in decadal resolution from the North Greenland Eemian Ice Drilling (NEEM) over the last 128,000 years we extract quantitative information on environmental changes, including the first comparison of northern hemisphere environmental conditions between the warmer than present Eemian and the early Holocene. Separating source changes from transport effects, we find that changes in the ice concentration greatly overestimate the changes in atmospheric concentrations in the aerosol source region, the latter mirroring changes in aerosol emissions. Glacial times were characterized by a strong reduction in terrestrial biogenic emissions (only 10-20% of the early Holocene value) reflecting the net loss of vegetated area in mid to high latitudes, while rapid climate changes during the glacial had essentially no effect on terrestrial biogenic aerosol emissions. An increase in terrestrial dust emissions of approximately a factor of eight during peak glacial and cold stadial intervals indicates higher aridity and dust storm activity in Asian deserts. Glacial sea salt aerosol emissions increased only moderately (by approximately 50%), likely due to sea ice expansion, while marked stadial/interstadial variations in sea salt concentrations in the ice reflect mainly changes in wet deposition en route. Eemian ice contains lower aerosol concentrations than ice from the early Holocene, due to shortened atmospheric residence time during the warmer Eemian, suggesting that generally 2°C warmer climate in high northern latitudes did not

  5. Stable symbiotic nitrogen fixation under water-deficit field conditions by a stress-tolerant alfalfa microsymbiont and its complete genome sequence.

    Science.gov (United States)

    Jozefkowicz, Cintia; Brambilla, Silvina; Frare, Romina; Stritzler, Margarita; Piccinetti, Carlos; Puente, Mariana; Berini, Carolina Andrea; Pérez, Pedro Reyes; Soto, Gabriela; Ayub, Nicolás

    2017-12-10

    We here characterized the stress-tolerant alfalfa microsymbiont Sinorhizobium meliloti B401. B401-treated plants showed high nitrogen fixation rates under humid and semiarid environments. The production of glycine betaine in isolated bacteroids positively correlated with low precipitation levels, suggesting that this compound acts as a critical osmoprotectant under field conditions. Genome analysis revealed that strain B401 contains alternative pathways for the biosynthesis and uptake of glycine betaine and its precursors. Such genomic information will offer substantial insight into the environmental physiology of this biotechnologically valuable nitrogen-fixing bacterium. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Some discussions on micrometeorology and atmospheric diffusion of classic and radioactive industrial pollutions. 3

    International Nuclear Information System (INIS)

    Veverka, O.; Valenta, V.; Vlachovsky, K.

    1977-01-01

    The vertical motion of an industrial plume, either conventional or radioactive is discussed and the respective formulas are given. The solution is given for the vertical rise of the plume and for the bent-over semi-horizontal plume under neutral, stable, and unstable atmospheric conditions. A theoretical model is described for the continuous rise of the radioactive plume under stable atmospheric conditions. The effective height is defined of the plume with regard to the shape of terrain and wind velocity. (J.P.)

  7. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...

  8. The Photochemistry of Unprotected DNA and DNA inside Bacillus subtilis Spores Exposed to Simulated Martian Surface Conditions of Atmospheric Composition, Temperature, Pressure, and Solar Radiation.

    Science.gov (United States)

    Nicholson, Wayne L; Schuerger, Andrew C; Douki, Thierry

    2018-03-28

    DNA is considered a potential biomarker for life-detection experiments destined for Mars. Experiments were conducted to examine the photochemistry of bacterial DNA, either unprotected or within Bacillus subtilis spores, in response to exposure to simulated martian surface conditions consisting of the following: temperature (-10°C), pressure (0.7 kPa), atmospheric composition [CO 2 (95.54%), N 2 (2.7%), Ar (1.6%), O 2 (0.13%), and H 2 O (0.03%)], and UV-visible-near IR solar radiation spectrum (200-1100 nm) calibrated to 4 W/m 2 of UVC (200-280 nm). While the majority (99.9%) of viable spores deposited in multiple layers on spacecraft-qualified aluminum coupons were inactivated within 5 min, a detectable fraction survived for up to the equivalent of ∼115 martian sols. Spore photoproduct (SP) was the major lesion detected in spore DNA, with minor amounts of cyclobutane pyrimidine dimers (CPD), in the order TT CPD > TC CPD > CT CPD. In addition, the (6-4)TC, but not the (6-4)TT, photoproduct was detected in spore DNA. When unprotected DNA was exposed to simulated martian conditions, all photoproducts were detected. Surprisingly, the (6-4)TC photoproduct was the major photoproduct, followed by SP ∼ TT CPD > TC CPD > (6-4)TT > CT CPD > CC CPD. Differences in the photochemistry of unprotected DNA and spore DNA in response to simulated martian surface conditions versus laboratory conditions are reviewed and discussed. The results have implications for the planning of future life-detection experiments that use DNA as the target, and for the long-term persistence on Mars of forward contaminants or their DNA. Key Words: Bacillus subtilis-DNA-Mars-Photochemistry-Spore-Ultraviolet. Astrobiology 18, xxx-xxx.

  9. Effect of modified atmosphere and vacuum packaging conditions on selected chemical and physico-chemical parameters of marinated and salted Atlantic mackerel (Scomber scombrus

    Directory of Open Access Journals (Sweden)

    Ivanović Jelena S.

    2016-01-01

    Full Text Available Chemical and physico-chemical parameters of marinated and salted Atlantic mackerel (Scomber Scombrus, with emphasis on the quality and safety parameters in modified atmosphere packaging (MAP and vacuum packaging (VP, were investigated. Quality assessment of mackerel stored in MAP (40% CO2+60% N2 and VP for up to 50 days at 4±1 °C was done by the monitoring of pH value, total volatile basic nitrogen (TVB-N, thiobarbituric acid (TBA and histamine. The pH value of fish meat was significantly lower in the marinated samples. The highest concentration of TVB-N was recorded in the salted mackerel stored under VP whereas the lowest TVB-N in the marinated mackerel stored under MAP conditions. The formation of TBA increased with the time of storage and was the lowest in the marinated mackerel stored in MAP. The concentration of histamine increased during storage and its level reached over 10 mg/100 g for the salted mackerel stored under VP conditions. The marinated mackerel packed in MAP had extended shelf life at 4±1 °C compared to that packaged in VP according to physico-chemical analysis.

  10. Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

    KAUST Repository

    Sharma, Ashish

    2016-09-08

    We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface. © 2016 IOP Publishing Ltd.

  11. Atmospheric Corrections and Multi-Conditional Algorithm for Multi-Sensor Remote Sensing of Suspended Particulate Matter in Low-to-High Turbidity Levels Coastal Waters

    Directory of Open Access Journals (Sweden)

    Stéfani Novoa

    2017-01-01

    Full Text Available The accurate measurement of suspended particulate matter (SPM concentrations in coastal waters is of crucial importance for ecosystem studies, sediment transport monitoring, and assessment of anthropogenic impacts in the coastal ocean. Ocean color remote sensing is an efficient tool to monitor SPM spatio-temporal variability in coastal waters. However, near-shore satellite images are complex to correct for atmospheric effects due to the proximity of land and to the high level of reflectance caused by high SPM concentrations in the visible and near-infrared spectral regions. The water reflectance signal (ρw tends to saturate at short visible wavelengths when the SPM concentration increases. Using a comprehensive dataset of high-resolution satellite imagery and in situ SPM and water reflectance data, this study presents (i an assessment of existing atmospheric correction (AC algorithms developed for turbid coastal waters; and (ii a switching method that automatically selects the most sensitive SPM vs. ρw relationship, to avoid saturation effects when computing the SPM concentration. The approach is applied to satellite data acquired by three medium-high spatial resolution sensors (Landsat-8/Operational Land Imager, National Polar-Orbiting Partnership/Visible Infrared Imaging Radiometer Suite and Aqua/Moderate Resolution Imaging Spectrometer to map the SPM concentration in some of the most turbid areas of the European coastal ocean, namely the Gironde and Loire estuaries as well as Bourgneuf Bay on the French Atlantic coast. For all three sensors, AC methods based on the use of short-wave infrared (SWIR spectral bands were tested, and the consistency of the retrieved water reflectance was examined along transects from low- to high-turbidity waters. For OLI data, we also compared a SWIR-based AC (ACOLITE with a method based on multi-temporal analyses of atmospheric constituents (MACCS. For the selected scenes, the ACOLITE-MACCS difference was

  12. A Moisture-Stable 3D Microporous CoII -Metal-Organic Framework with Potential for Highly Selective CO2 Separation under Ambient Conditions.

    Science.gov (United States)

    Chand, Santanu; Pal, Arun; Das, Madhab C

    2018-02-13

    Selective adsorption and separation of CO 2 from flue gas and landfill gas mixtures have drawn great attention in industry. Porous MOF materials are promising alternatives to achieve such separations; however, the stability in the presence of moisture must be taken into consideration. Herein, we have constructed a microporous metal-organic framework (MOF) {[Co(OBA)(L) 0.5 ]⋅S} n (IITKGP-8), by employing a V-shaped organic linker with an azo-functionalized N,N' spacer forming a 3D network with mab topology and 1D rhombus-shaped channels along the crystallographic 'b' axis with a void volume of 34.2 %. The activated MOF reveals a moderate CO 2 uptake capacity of 55.4 and 26.5 cm 3  g -1 at 273 and 295 K/1 bar, respectively, whereas it takes up a significantly lower amount of CH 4 and N 2 under similar conditions and thus exhibits its potential for highly selective sorption of CO 2 with excellent IAST selectivity of CO 2 /N 2 (106 at 273 K and 43.7 at 295 K) and CO 2 /CH 4 (17.7 at 273 K and 17.1 at 295 K) under 1 bar. More importantly, this MOF exhibits excellent moisture stability as assessed through PXRD experiments coupled with surface area analysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Site-condition map for Portugal, Western Iberia: methodology and constraints on the performance of Vs30 proxies for stable continental regions in Europe.

    Science.gov (United States)

    Vilanova, S. P.; Narciso, J.; Carvalho, J. P.; Cancela, C.; Lopes, I.; Nemser, E. S.; Borges, J.

    2014-12-01

    Information on the amplification characteristics of the near-surface formations in a regional sense is essential to adequately represent both seismic hazard maps and ground shaking maps. Due to the scarceness of shear-wave velocity data in most regions, several methods have been proposed in order to obtain first order representations of Vs30. These include the surface geology method and the topographic slope method. The latter method has become the standard way for incorporating site effects into regional studies worldwide given the convenience provided by the global Vs30 Internet server. In the framework of project SCENE we developed a shear wave velocity database for Portugal. The database consists of 87 shear-wave velocity depth profiles from a variety of lithological and geological formations. We used an iterative three-step procedure to develop the Vs30 based site-condition map: 1) to define a preliminary set of geologically defined units based on the literature; 2) to calculate the distribution of Vs30 for each unit; and 3) to perform statistical tests in order to estimate the significance of the difference in the Vs30 distribution characteristics between the units. The units were merged according to the results of the statistical tests and the procedure was repeated. We started by classifying the sites into six generalized geological units. The final set consists of three units only: F1 (igneous, metamorphic and old sedimentary rocks); F2 (Neogene and Pleistocene formations); and F3 (Holocene deposits). We used the database to evaluate the performance of Vs30 proxies. The use of proxies based either on geological units or on correlations with the topographic slope shows relatively unbiased total residual distributions of the logarithm of Vs30. However, the performance of the methods varies significantly with the generalized geological unit analyzed. Both methods are biased towards lower values of Vs30 for rock formations. The topographic-slope method is

  14. Experimental study of the injection conditions influence over n-dodecane and diesel sprays with two ECN single-hole nozzles. Part I: Inert atmosphere

    International Nuclear Information System (INIS)

    Gimeno, Jaime; Bracho, Gabriela; Martí-Aldaraví, Pedro; Peraza, Jesús E.

    2016-01-01

    In this research, two Engine Combustion Network (ECN) mono-orifice nozzles, referred to as Spray C and Spray D respectively, were analyzed by performing visualization tests through Schlieren and Diffused Backlight Illumination (DBI) techniques under a wide range of ambient conditions in a non-reactive atmosphere. Spray C presents a straight nozzle designed with a sharp fillet in opposition to Spray D that has similar hydraulic properties, but with a convergent nozzle construction and a smoother corner. The experiments were carried out injecting two distinct fuels at different injection pressure ranges, from 50 MPa to 150 MPa with n-dodecane and to 200 MPa for diesel. The images were processed with Matlab home-built routines to calculate parameters as spray penetration, spreading angle, quasi-steady liquid length, as well as the spray penetration derivative respect to the square root of time, presented in this document as R-parameter. The results showed a clear influence of nozzle geometry in all measured parameters, due mainly to the nature of Spray C to cavitation, which increase the spreading angle and consequently a reduction in vapor penetration. On the other hand, fuel properties also affected spray penetration due to its dependency on viscous forces expressed in terms of the Reynolds number and its volatility in case of liquid length. This last parameter was calculated employing two processing methodologies, finding a good general agreement between them.

  15. Study of atmospheric condition during the heavy rain event in Bojonegoro using weather research and forecasting (WRF) model: case study 9 February 2017

    Science.gov (United States)

    Saragih, I. J. A.; Meygatama, A. G.; Sugihartati, F. M.; Sidauruk, M.; Mulsandi, A.

    2018-03-01

    During 2016, there are frequent heavy rains in the Bojonegoro region, one of which is rain on 9 February 2016. The occurrence of heavy rainfall can cause the floods that inundate the settlements, rice fields, roads, and public facilities. This makes it important to analyze the atmospheric conditions during the heavy rainfall events in Bojonegoro. One of the analytical methods that can be used is using WRF-Advanced Research WRF (WRF-ARW) model. This study was conducted by comparing the rain analysis from WRF-ARW model with the Himawari-8 satellite imagery. The data used are Final Analysis (FNL) data for the WRF-ARW model and infrared (IR) channel for Himawari-8 satellite imagery. The data are processed into the time-series images and then analyzed descriptively. The meteorological parameters selected to be analyzed are relative humidity, vortices, divergences, air stability index, and precipitation. These parameters are expected to indicate the existence of a convective activity in Bojonegoro during the heavy rainfall event. The Himawari-8 satellite imagery shows that there is a cluster of convective clouds in Bojonegoro during the heavy rainfall event. The lowest value of the cloud top temperature indicates that the cluster of convective clouds is a cluster of Cumulonimbus cloud (CB).

  16. IR-thermography-based investigation of critical heat flux in subcooled flow boiling of water at atmospheric and high pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bucci, Matteo [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Seong, Jee H. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Buongiorno, Jdacopo [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Richenderfer, Andrew [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Kossolapov, A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2017-11-01

    Here we report on MIT’s THM work in Q4 2016 and Q1 2017. The goal of this project is to design, construct and execute tests of flow boiling critical heat flux (CHF) at high-pressure using high-resolution and high-speed video and infrared (IR) thermometry, to generate unique data to inform the development of and validate mechanistic boiling heat transfer and CHF models. In FY2016, a new test section was designed and fabricated. Data was collected at atmospheric conditions at 10, 25 and 50 K subcoolings, and three mass fluxes, i.e. 500, 750 and 1000 kg/m2/s. Starting in Q4 2016 and continuing forward, new post-processing techniques have been developed to analyze the data collected. These new algorithms analyze the time-dependent temperature and heat flux distributions to calculate nucleation site density, nucleation frequency, growth and wait time, dry area fraction, and the complete heat flux partitioning. In Q1 2017 a new flow boiling loop was designed and constructed to support flow boiling tests up 10 bar pressure and 180 °C. Initial shakedown and testing has been completed. The flow loop and test section are now ready to begin high-pressure flow boiling testing.

  17. The intOA Experiment: A Study of Ocean-Atmosphere Interactions Under Moderate to Strong Offshore Winds and Opposing Swell Conditions in the Gulf of Tehuantepec, Mexico

    Science.gov (United States)

    Ocampo-Torres, F. J.; García-Nava, H.; Durazo, R.; Osuna, P.; Díaz Méndez, G. M.; Graber, H. C.

    2011-03-01

    The Gulf of Tehuantepec air-sea interaction experiment ( intOA) took place from February to April 2005, under the Programme for the Study of the Gulf of Tehuantepec (PEGoT, Spanish acronym for Programa para el Estudio del Golfo de Tehuantepec). PEGoT is underway aiming for better knowledge of the effect of strong and persistent offshore winds on coastal waters and their natural resources, as well as performing advanced numerical modelling of the wave and surface current fields. One of the goals of the intOA experiment is to improve our knowledge on air-sea interaction processes with particular emphasis on the effect of surface waves on the momentum flux for the characteristic and unique conditions that occur when strong Tehuano winds blow offshore against the Pacific Ocean long period swell. For the field campaign, an air-sea interaction spar (ASIS) buoy was deployed in the Gulf of Tehuantepec to measure surface waves and the momentum flux between the ocean and the atmosphere. High frequency radar systems (phase array type) were in operation from two coastal sites and three acoustic Doppler current profilers were deployed near-shore. Synthetic aperture radar images were also acquired as part of the remote sensing component of the experiment. The present paper provides the main results on the wave and wind fields, addressing the direct calculation of the momentum flux and the drag coefficient, and gives an overview of the intOA experiment. Although the effect of swell has been described in recent studies, this is the first time for the very specific conditions encountered, such as swell persistently opposing offshore winds and locally generated waves, to show a clear evidence of the influence on the wind stress of the significant steepness of swell waves.

  18. Jovian atmospheres

    International Nuclear Information System (INIS)

    Allison, M.; Travis, L.D.

    1986-10-01

    A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers

  19. Earth’s Earliest Atmospheres

    Science.gov (United States)

    Zahnle, Kevin; Schaefer, Laura; Fegley, Bruce

    2010-01-01

    Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth’s atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth’s subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO- or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases. PMID:20573713

  20. Stable convergence and stable limit theorems

    CERN Document Server

    Häusler, Erich

    2015-01-01

    The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

  1. Effects of Hydrated Potato Starch on the Quality of Low-fat Ttoekgalbi (Korean Traditional Patty) Packaged in Modified Atmosphere Conditions during Storage

    Science.gov (United States)

    Muhlisin, S. M. Kang; Choi, W. H.; Lee, K. T.; Cheong, S. H.; Lee, S. K.

    2012-01-01

    This study was carried out to investigate the effects of hydrated potato starch on the quality of low-fat ttoekgalbi (Korean traditional patty) packaged in modified atmosphere conditions during storage. The ttoekgalbi was prepared from 53.2% lean beef, 13.9% lean pork, 9.3% pork fat, and 23.6% other ingredients. Two low-fat ttoekgalbi treatments were prepared by substituting pork fat with hydrated potato starch; either by 50% fat replacement (50% FR) or 100% fat replacement (100% FR). Both 50% and 100% FR increased the moisture, crude protein, and decreased fat content, cooking loss, and hardness. For MAP studies, 200 g of ttoekgalbi were placed on the tray and filled with gas composed of 70% O2: 30% CO2 (70% O2-MAP) and 30% CO2: 70% N2 (70% N2-MAP), and were stored at 5°C for 12 d. During the storage time, both 50% and 100% FR showed higher protein deterioration, while no differences were found in CIE a*, CIE L*, lipid oxidation, and bacterial counts in comparison to control. The ttoekgalbi with 70% O2-MAP was more red, lighter in color, and showed higher TBARS values compared with 70% N2-MAP. The meat with 70% N2-MAP showed lower aerobic bacterial counts in control than those with 70% O2-MAP. The lower anaerobic bacterial counts were observed only in 50% FR and 100% FR packed with 70% N2-MAP in comparison with 70% O2-MAP. In conclusion, the fat replacement with hydrated potato starch showed no negative effects on the quality of low fat ttoekgalbi during storage and 70% N2-MAP was better than 70% O2-MAP for low-fat ttoekgalbi packaging. PMID:25049619

  2. Effects of Hydrated Potato Starch on the Quality of Low-fat Ttoekgalbi (Korean Traditional Patty Packaged in Modified Atmosphere Conditions during Storage

    Directory of Open Access Journals (Sweden)

    S. M. Kang Muhlisin

    2012-05-01

    Full Text Available This study was carried out to investigate the effects of hydrated potato starch on the quality of low-fat ttoekgalbi (Korean traditional patty packaged in modified atmosphere conditions during storage. The ttoekgalbi was prepared from 53.2% lean beef, 13.9% lean pork, 9.3% pork fat, and 23.6% other ingredients. Two low-fat ttoekgalbi treatments were prepared by substituting pork fat with hydrated potato starch; either by 50% fat replacement (50% FR or 100% fat replacement (100% FR. Both 50% and 100% FR increased the moisture, crude protein, and decreased fat content, cooking loss, and hardness. For MAP studies, 200 g of ttoekgalbi were placed on the tray and filled with gas composed of 70% O2: 30% CO2 (70% O2-MAP and 30% CO2: 70% N2 (70% N2-MAP, and were stored at 5°C for 12 d. During the storage time, both 50% and 100% FR showed higher protein deterioration, while no differences were found in CIE a*, CIE L*, lipid oxidation, and bacterial counts in comparison to control. The ttoekgalbi with 70% O2-MAP was more red, lighter in color, and showed higher TBARS values compared with 70% N2-MAP. The meat with 70% N2-MAP showed lower aerobic bacterial counts in control than those with 70% O2-MAP. The lower anaerobic bacterial counts were observed only in 50% FR and 100% FR packed with 70% N2-MAP in comparison with 70% O2-MAP. In conclusion, the fat replacement with hydrated potato starch showed no negative effects on the quality of low fat ttoekgalbi during storage and 70% N2-MAP was better than 70% O2-MAP for low-fat ttoekgalbi packaging.

  3. Regimes de atmosfera controlada para o armazenamento de caqui ‘Kyoto’ Controlled atmosphere conditions for ‘Kyoto’ persimmon storage

    Directory of Open Access Journals (Sweden)

    Auri Brackmann

    2004-10-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de regimes de atmosfera controlada associados ou não com o uso de baixa umidade relativa e com a aplicação pós-colheita de fungicida sobre a conservação da qualidade de caqui ‘Kyoto’. Após o período de dois meses de armazenamento refrigerado a -0,5°C mais cinco dias a 20ºC, a firmeza de polpa manteve-se mais elevada nos frutos submetidos a 0,5kPa de O2 e 5kPa de CO2. A maior incidência de podridões ocorreu nos frutos armazenados a 2kPa de O2 + 10kPa de CO2. Baixa umidade relativa (90% ou pressões parciais elevadas de CO2 (10 a 15kPa aumentaram o escurecimento da epiderme.This work aimed to evaluate the effect of different partial pressures of O2 and CO2, combined or not with the use of low relative humidity (RH and the postharvest fungicide application, on the quality of ‘Kyoto’ persimmons during controlled atmosphere (CA storage. After two months of storage at -0.5°C plus five days at 20ºC, the highest flesh firmness was obtained in fruits stored in CA conditions of 0.5kPa of O2 and 5kPa of CO2. The highest rot incidence was observed in fruits stored at 2kPa O2 + 10kPa CO2. Low RH (90% or high CO2 levels (10 to 15kPa led to increased skin blackening.

  4. Statistical prediction of far-field wind-turbine noise, with probabilistic characterization of atmospheric stability

    DEFF Research Database (Denmark)

    Kelly, Mark C.; Barlas, Emre; Sogachev, Andrey

    2018-01-01

    atmospheric stability; the latter follows from the basic form for stability distributions established by Kelly and Gryning [Boundary-Layer Meteorol. 136, 377–390 (2010)]. For each condition, a parabolic-equation acoustic propagation model is driven by an atmospheric boundary-layer (“ABL”) flow model......; the latter solves Reynolds-Averaged Navier-Stokes equations of momentum and temperature, including the effects of stability and the ABL depth, along with the drag due to the wind turbine. Sound levels are found to be highest downwind for modestly stable conditions not atypical of mid-latitude climates......, and noise levels are less elevated for very stable conditions, depending on ABL depth. The probabilistic modelling gives both the long-term (ensemble-mean) noise level and the variability as a function of distance, per site-specific atmospheric stability statistics. The variability increases...

  5. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan

    2014-01-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating...

  6. The footprint of atmospheric turbulence in power grid frequency measurements

    OpenAIRE

    Haehne, Hauke; Schottler, Jannik; Waechter, Matthias; Peinke, Joachim; Kamps, Oliver

    2018-01-01

    Fluctuating wind energy makes a stable grid operation challenging. Due to the direct contact with atmospheric turbulence, intermittent short-term variations in the wind speed are converted to power fluctuations that cause transient imbalances in the grid. We investigate the impact of wind energy feed-in on short-term fluctuations in the frequency of the public power grid, which we have measured in our local distribution grid. By conditioning on wind power production data, provided by the ENTS...

  7. Atmospheric contamination

    International Nuclear Information System (INIS)

    Gruetter, Juerg

    1997-01-01

    It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

  8. Survival of lactic acid and chlorine dioxide treated Campylobacter jejuni under suboptimal conditions of pH, temperature and modified atmosphere

    DEFF Research Database (Denmark)

    Smigic, Nada; Rajkovic, Andreja; Nielsen, Dennis Sandris

    2010-01-01

    Campylobacter jejuni cells treated with lactic acid (LA, 3% lactic acid, pH 4.0, 2 min) or chlorine dioxide (ClO(2), 20 ppm, 2 min) were inoculated in Bolton broth (pH 6.0) and incubated under 80% O(2)/20% N(2), 80% CO(2)/20% N(2), air or micro-aerophilic (10% CO(2)/85% N(2)/5% O(2)) atmosphere, at 4 degrees C...... during 7 days. Treatment with water served as a control. The most suppressive atmosphere for the survival of C. jejuni was O(2)-rich atmosphere, followed by air, micro-aerophilic and CO(2)-rich atmosphere. The survival of C. jejuni was dependent on the type of initial decontamination treatment...... on their pH(i) values. The pH(i) response was independent on the surrounding atmosphere since similar distribution of the subpopulations was observed for all tested atmospheres. However, the pH(i) response was dependent on the initial decontamination treatment. The investigation of intracellular parameters...

  9. Atmospheric transformation of volatile organic compounds

    Science.gov (United States)

    Henley, Michael V.; Bradley, William R.; Wyatt, Sheryl E.; Graziano, G. M.; Wells, J. R.

    2000-07-01

    To be able to understand and predict the concentration of a target compound in the atmosphere one must understand the atmospheric chemistry involved. The transformation of volatile organic compounds in the troposphere is predominantly driven by the interaction with the hydroxyl and nitrate radicals. The hydroxyl radical exists in daylight conditions and its reaction rate constant with an organic compound is typically very fast. The nitrate radical drives the nighttime chemistry. These radicals can scavenge hydrogen from an organic molecule generating secondary products that are often overlooked in detection schemes. Secondary products can be more stable and serve as a better target compound in detection schemes. The gas phase reaction of the hydroxyl radical (OH) with cyclohexanol (COL) has been studied. The rate coefficient was determined to be (19.0 +/- 4.8) X 10-12 cm3 molecule-1 s-1 (at 297 +/- 3 K and 1 atmosphere total pressure) using the relative rate technique with pentanal, decane, and tridecane as the reference compounds. Assuming an average OH concentration of 1 X 106 molecules cm-3, an atmospheric lifetime of 15 h is calculated for cyclohexanol. Products of the OH + COL reaction were determined to more clearly define cyclohexanol's atmospheric degradation mechanism. The observed products were: cyclohexanone, hexanedial, 3- hydroxycyclohexanone, and 4-hydroxycyclohexanone. Consideration of the potential reaction pathways suggest that each of these products is formed via hydrogen abstraction at a different site on the cyclohexanol ring.

  10. Urban atmospheric contamination

    International Nuclear Information System (INIS)

    Baldasano Jose, M.

    1997-01-01

    The problems of contamination are not only limited to this century, pale pathology evidences of the effects of the contamination of the air exist in interiors in the health of the old ones; the article mention the elements that configure the problem of the atmospheric contamination, atmospheric pollutants and emission sources, orography condition and effects induced by the urbanization process

  11. Development of a novel ozone- and photo-stable HyPer5 red fluorescent dye for array CGH and microarray gene expression analysis with consistent performance irrespective of environmental conditions

    Directory of Open Access Journals (Sweden)

    Kille Peter

    2008-11-01

    Full Text Available Abstract Background Array-based comparative genomic hybridization (CGH and gene expression profiling have become vital techniques for identifying molecular defects underlying genetic diseases. Regardless of the microarray platform, cyanine dyes (Cy3 and Cy5 are one of the most widely used fluorescent dye pairs for microarray analysis owing to their brightness and ease of incorporation, enabling high level of assay sensitivity. However, combining both dyes on arrays can become problematic during summer months when ozone levels rise to near 25 parts per billion (ppb. Under such conditions, Cy5 is known to rapidly degrade leading to loss of signal from either "homebrew" or commercial arrays. Cy5 can also suffer disproportionately from dye photobleaching resulting in distortion of (Cy5/Cy3 ratios used in copy number analysis. Our laboratory has been active in fluorescent dye research to find a suitable alternative to Cy5 that is stable to ozone and resistant to photo-bleaching. Here, we report on the development of such a dye, called HyPer5, and describe its' exceptional ozone and photostable properties on microarrays. Results Our results show HyPer5 signal to be stable to high ozone levels. Repeated exposure of mouse arrays hybridized with HyPer5-labeled cDNA to 300 ppb ozone at 5, 10 and 15 minute intervals resulted in no signal loss from the dye. In comparison, Cy5 arrays showed a dramatic 80% decrease in total signal during the same interval. Photobleaching experiments show HyPer5 to be resistant to light induced damage with 3- fold improvement in dye stability over Cy5. In high resolution array CGH experiments, HyPer5 is demonstrated to detect chromosomal aberrations at loci 2p21-16.3 and 15q26.3-26.2 from three patient sample using bacterial artificial chromosome (BAC arrays. The photostability of HyPer5 is further documented by repeat array scanning without loss of detection. Additionally, HyPer5 arrays are shown to preserve sensitivity and

  12. stableGP

    Data.gov (United States)

    National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

  13. Modeling large offshore wind farms under different atmospheric stability regimes with the Park wake model

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Réthoré, Pierre-Elouan; Rathmann, Ole

    2014-01-01

    We evaluate a modified version of the Park wake model against power data from a west-east row in the middle of the Horns Rev I offshore wind farm. The evaluation is performed on data classified in four different atmospheric stability conditions, for a narrow wind speed range, and a wide range...... turbines on the row and those using the WAsP recommended value closer to the data for the first turbines. It is generally seen that under stable and unstable atmospheric conditions the power deficits are the highest and lowest, respectively, but the wind conditions under both stability regimes...

  14. Modeling large offshore wind farms under different atmospheric stability regimes with the Park wake model

    DEFF Research Database (Denmark)

    Peña, Alfredo; Réthoré, Pierre-Elouan; Rathmann, Ole

    2013-01-01

    Here, we evaluate a modified version of the Park wake model against power data from a west-east row in the middle of the Horns Rev I offshore wind farm. The evaluation is performed on data classified in four different atmospheric stability conditions, for a narrow wind speed range, and a wide range...... turbines and those using the WAsP recommended value closer to the data for the first turbines. It is generally seen that under stable and unstable atmospheric conditions the power deficits are the highest and lowest, respectively, but the wind conditions under both stability regimes are different...

  15. Observation-based parameterization of air-sea fluxes in terms of wind speed and atmospheric stability under low-to-moderate wind conditions

    Science.gov (United States)

    Zou, Zhongshui; Zhao, Dongliang; Liu, Bin; Zhang, Jun A.; Huang, Jian

    2017-05-01

    This study explores the behavior of the exchange coefficients for wind stress (CD), sensible heat flux (CH), and water vapor flux (CE) as functions of surface wind speed (U10) and atmospheric stability using direct turbulent flux measurements obtained from a platform equipped with fast-response turbulence sensors in a low-to-moderate wind region. Turbulent fluxes are calculated using the eddy-correlation method with extensive observations. The total numbers of quality-controlled 30 min flux runs are 12,240, 5813, and 5637 for estimation of CD, CH, and CE, respectively. When adjusted to neutral stability using the Monin-Obukhov similarity theory (MOST), we found that CDN, CHN, and CEN decrease with neutral-adjusted wind speed when wind speed is less than 5 m/s. CDN is constant over the range 5 m/s 12 m/s. In contrast, CHN and CEN exhibit no clear dependence on wind speed and are generally constant, with mean values of 0.96 × 10-3 and 1.2 × 10-3, respectively. This behavior of neutral exchange coefficients is consistent with the findings of previous studies. We also found that CDN under offshore winds is generally greater than that under onshore wind conditions, which is ascribed to the younger wind waves present due to the shorter fetch in the former case. However, this behavior is not exhibited by CHN or CEN. The original CD, CH, and CE values without MOST adjustment are also investigated to develop a new parameterization based on wind speed and stability. Three stability parameters are tested, including the bulk Richardson number, stability as defined in COARE 3.0, and a simplified Richardson number using the Charnock parameter. This new parameterization is free of MOST and the associated self-correlation. Compared with previous studies and COARE 3.0 results, the new parameterization using the simplified Richardson number performs well, with an increased correlation coefficient and reduction of root-mean-square error and bias.

  16. Atmospheric circulation changes and neoglacial conditions in the Southern Hemisphere mid-latitudes: insights from PMIP2 simulations at 6 kyr

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, Maisa [University of Chile, Department of Geophysics, Santiago (Chile); Moreno, Patricio I. [University of Chile, Department of Ecology, Santiago (Chile)

    2011-07-15

    Glacial geologic studies in the Southern Hemisphere (SH) mid-latitudes (40-54 S) indicate renewed glacial activity in southern South America (Patagonia) and New Zealand's (NZ) South Island starting at {proportional_to}7 kyr, the so-called neoglaciation. Available data indicate that neoglacial advances in these regions occurred during a rising trend in atmospheric CO{sub 2} and CH{sub 4} concentrations, lower-than-present but increasing summer insolation and seasonality contrasts. In this paper we examine the climatological context in which neoglaciations occurred through analysis of the complete Paleoclimate Modelling Inter-comparison Project (PMIP2) database of simulations at 6 kyr for the SH. We observe that the amplitude of the annual insolation cycle in the SH did not change significantly at 6 kyr compared to the pre-industrial values, the largest difference occurring in autumn (MAM, negative anomalies) and spring (SON, positive anomalies). The simulated changes in temperatures over the SH respond to the insolation changes, with a 1-2 month delay over the oceans. This results in a reduced amplitude of the annual cycle of temperature and precipitation over most continental regions, except over Patagonia and NZ, that show a slight increase. In contrast, large-scale circulation features, such as the low and upper level winds and the subtropical anticyclones show an amplified annual cycle, as a direct response to the increased/decreased insolation during the transitional seasons SON/MAM. In the annual mean, there is a small but consistent equatorward shift of the latitude of maximum wind speed of 1-3 over the entire SH, which results in a small increase of wind speed over the South Pacific and Atlantic Oceans north of {proportional_to}50 S and a widespread decline south of 50 S. PMIP2 simulations for 6 kyr, indicate that in the annual mean, the SH mid-latitudes were colder, wetter and with stronger winds north of about 50 S. These conditions are consistent

  17. Mesoscale modeling of the atmosphere

    Science.gov (United States)

    Pearce, R. P.

    1993-03-01

    The Naval Research Laboratory (NRL) is presently developing a non-hydrostatic mesoscale model which is suitable for forecasting meso-Beta and gamma scale phenomena over complex terrain. The model will be delivered to the Army in 1997. However, until the non-hydrostatic model becomes operational, HOTMAC (Higher Order Turbulence Model for Atmospheric Circulation) will be used as an operational model in the U.S. Army's IMETS (Integrated METeorological System) to make a short-range (up to 24 hours) forecast of battlescale atmospheric phenomena. The U.S. Army is mainly concerned with meteorological conditions spatially within the area of 500 km x 500 km x 10 km or less and temporally within the period of 24 hours or less. The Army Research Laboratory's (ARL) prototype IMETS is currently receiving the forecast and analysis fields of meteorological variables produced from the U.S. Air Force Global Spectral Model (GSM) through the Automated Weather Distribution System (AWDS). In the near future, the Relocatable Window Model (RWM) output is expected to become available. The RWM is the Air Force's regional meso-alpha model similar to the Navy Operational Regional Atmospheric Prediction System (NORAPS). The U.S. Army is planning to use the output of GSM (or RWM) to initialize and assimilate into HOTMAC. HOTMAC has been used extensively at the ARL (formerly Atmospheric Sciences Laboratory), and simulate the evolution of locally forced circulations due to surface heating and cooling over meso-Beta and gamma scale areas. HOTMAC is numerically stable and easy to use and thus, suitable for operational use.

  18. Patterns of behavior of 14C in atmosphere-plant system under conditions of variable 14CO2 concentration in air

    International Nuclear Information System (INIS)

    Fedorov, E.A.; Ponomareva, R.P.; Milakina, L.A.

    1985-01-01

    The parameters of the behavior of 14 C in the atmosphere-plant system are examined. It was established in a growth experiment that after a one-hour exposure of plants in a 14 CO 2 atmosphere the change with time in the organ specific activity occurs according to a biexponential function with elimination half-lives T/sub 1,2/ of 2 and 40 days and fractions B/sub 1,2/ of 0.6 and 0.4. Increase in the number of exposures increases the T 2 value to 100 days and B 2 to 0.8. According to calculations, an equilibrium state in the atmosphere-leaf component occurs after 78 days

  19. Champion Island, Galapagos Stable Oxygen Calibration Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Galapagos Coral Stable Oxygen Calibration Data. Sites: Bartolome Island: 0 deg, 17 min S, 90 deg 33 min W. Champion Island: 1 deg, 15 min S, 90 deg, 05 min W. Urvina...

  20. Simulation modeling of the spread of harmful emissions into the atmosphere on the basis of geographic information system (GIS) of monitoring environmental condition of a megalopolis

    Science.gov (United States)

    Bissarinova, Aigul; Mamyrova, Aisha; Tussupova, Bella; Balgabayeva, Lyazzat; Mamyrbayev, Orken

    2016-10-01

    In this paper, a methodology of geoinformation approach to mapping of atmospheric pollution of the air basin of Almaty city is developed. The proposed method of presenting data on pollution in form of an algorithm allows building a map of contamination of the surface layer of the atmosphere closest to the actually observed one. Designed object-oriented method of presentation of environmental pollution in the form of dynamic GIS models can be used when modeling the ecological status of any area, megalopolis, i.e. where spatial data, distributed in time, is used.

  1. Modeling the impact of vapor thymol concentration, temperature and modified atmosphere condition on growth behavior of Salmonella spp. on raw shrimp

    Science.gov (United States)

    Salmonella spp. is a microorganism of concern, on a global basis, for raw shrimp. This research modeled the impact of vapor thymol concentration (0, 0.8 and 1.6 mg/l), storage temperature (8, 12 and 16 degree C) and modified atmosphere packaging (0.04 and 59.5 percent CO2) against the growth behavio...

  2. Warming of waters in an East Greenland fjord prior to glacier retreat: mechanisms and connection to large-scale atmospheric conditions

    Directory of Open Access Journals (Sweden)

    P. Christoffersen

    2011-09-01

    Full Text Available Hydrographic data acquired in Kangerdlugssuaq Fjord and adjacent seas in 1993 and 2004 are used together with reanalysis from the NEMO ocean modelling framework to elucidate water-mass change and ice-ocean-atmosphere interactions in East Greenland. The hydrographic data show that the fjord contains warm subtropical waters and that fjord waters in 2004 were considerably warmer than in 1993. The ocean reanalysis shows that the warm properties of fjord waters in 2004 are related to a major peak in oceanic shoreward heat flux into a cross-shelf trough on the outer continental shelf. The heat flux into this trough varies according to seasonal exchanges with the atmosphere as well as from deep seasonal intrusions of subtropical waters. Both mechanisms contribute to high (low shoreward heat flux when winds from the northeast are weak (strong. The combined effect of surface heating and inflow of subtropical waters is seen in the hydrographic data, which were collected after periods when along-shore coastal winds from the north were strong (1993 and weak (2004. The latter data were furthermore acquired during the early phase of a prolonged retreat of Kangerdlugssuaq Glacier. We show that coastal winds vary according to the pressure gradient defined by a semi-permanent atmospheric high-pressure system over Greenland and a persistent atmospheric low situated near Iceland. The magnitude of this pressure gradient is controlled by longitudinal variability in the position of the Icelandic Low.

  3. Chemistry and long-term decomposition of roots from Douglas-fir grown at elevated atmospheric CO2 and warming conditions

    Science.gov (United States)

    Elevated atmospheric CO2 and warming may affect litter quality of plants and its subsequent decomposition in forested ecosystems. Little data are available to test this potential feedback on root tissues. In this study, we used the fine (diameter ≤ 2 mm) and small (2-10 mm) roo...

  4. Silicon nanoparticle formation depending on the discharge conditions of an atmospheric radio-frequency driven microplasma with argon/silane/hydrogen gases

    Czech Academy of Sciences Publication Activity Database

    Barwe, B.; Riedel, F.; Cibulka, Ondřej; Pelant, Ivan; Benedikt, J.

    2015-01-01

    Roč. 48, Aug (2015), s. 314001 ISSN 0022-3727 Institutional support: RVO:68378271 Keywords : silicon nanoparticles * microplasma jets * silane * atmospheric plasma * dynamic light scattering * scanning electron microscopy Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.772, year: 2015

  5. A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory

    NARCIS (Netherlands)

    Abraham, J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E. J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anzalone, A.; Aramo, C.; Arganda, E.; Arisaka, K.; Arqueros, F.; Asch, T.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avila, G.; Baecker, T.; Badagnani, D.; Barber, K. B.; Barbosa, A. F.; Barroso, S. L. C.; Baughman, B.; Bauleo, P.; Beatty, J. J.; Beau, T.; Becker, B. R.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Bleve, C.; Bluemer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Chye, J.; Clay, R. W.; Colombo, E.; Conceicao, R.; Contreras, F.; Cook, H.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; Di Giulio, C.; Diaz, J. C.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; DuVernois, M. A.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferrer, F.; Ferrero, A.; Fick, B.; Filevich, A.; Filipcic, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Gamez, D.; Garcia-Pinto, D.; Garrido, X.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Goggin, L. M.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gomez Berisso, M.; Goncalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gora, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Gutierrez, J.; Hague, J. D.; Halenka, V.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Healy, M. D.; Hebbeker, T.; Hebrero, G.; Heck, D.; Hojvat, C.; Holmes, V. C.; Homola, P.; Horandel, J. R.; Horneffer, A.; Hrabovsky, M.; Huege, T.; Hussain, M.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kaducak, M.; Kampert, K. H.; Karova, T.; Kasper, P.; Kegl, B.; Keilhauer, B.; Kelley, J.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D. -H.; Krieger, A.; Kroemer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, K.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lautridou, P.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Lee, J.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Lopez, R.; Lopez Agueera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; McNeil, R. R.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, C.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Morris, C.; Mostafa, M.; Moura, C. A.; Mueller, S.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Newman-Holmes, C.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Nyklicek, M.; Oehlschlaeger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parlati, S.; Parsons, R. D.; Pastor, S.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; Pekala, J.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Redondo, A.; Revenu, B.; Rezende, F. A. S.; Ridky, J.; Riggi, S.; Risse, M.; Riviere, C.; Rizi, V.; Robledo, C.; Rodriguez, G.

    The air fluorescence detector of the Pierre Auger Observatory is designed to perforin calorimetric measurements of extensive air showers created by Cosmic rays of above 10(18) eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group

  6. Chemistry and Long-Term Decomposition of Roots of Douglas-Fir Grown under Elevated Atmospheric Carbon Dioxide and Warming Conditions

    Science.gov (United States)

    Elevated atmospheric CO2 concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to...

  7. Impact of the Diurnal Cycle of the Atmospheric Boundary Layer on Wind-Turbine Wakes: A Numerical Modelling Study

    Science.gov (United States)

    Englberger, Antonia; Dörnbrack, Andreas

    2018-03-01

    The wake characteristics of a wind turbine for different regimes occurring throughout the diurnal cycle are investigated systematically by means of large-eddy simulation. Idealized diurnal cycle simulations of the atmospheric boundary layer are performed with the geophysical flow solver EULAG over both homogeneous and heterogeneous terrain. Under homogeneous conditions, the diurnal cycle significantly affects the low-level wind shear and atmospheric turbulence. A strong vertical wind shear and veering with height occur in the nocturnal stable boundary layer and in the morning boundary layer, whereas atmospheric turbulence is much larger in the convective boundary layer and in the evening boundary layer. The increased shear under heterogeneous conditions changes these wind characteristics, counteracting the formation of the night-time Ekman spiral. The convective, stable, evening, and morning regimes of the atmospheric boundary layer over a homogeneous surface as well as the convective and stable regimes over a heterogeneous surface are used to study the flow in a wind-turbine wake. Synchronized turbulent inflow data from the idealized atmospheric boundary-layer simulations with periodic horizontal boundary conditions are applied to the wind-turbine simulations with open streamwise boundary conditions. The resulting wake is strongly influenced by the stability of the atmosphere. In both cases, the flow in the wake recovers more rapidly under convective conditions during the day than under stable conditions at night. The simulated wakes produced for the night-time situation completely differ between heterogeneous and homogeneous surface conditions. The wake characteristics of the transitional periods are influenced by the flow regime prior to the transition. Furthermore, there are different wake deflections over the height of the rotor, which reflect the incoming wind direction.

  8. Data for NASA's AVE 3 experiment: 25-mb sounding data and synoptic charts. [investigation of atmospheric parameters detected from satellite data under conditions of heavy snow cover

    Science.gov (United States)

    Fuelberg, H. E.; Turner, R. E.

    1975-01-01

    The atmospheric variability experiment (AVE 3) is described and tabulated rawinsonde data at 25-mb intervals from the surface to 25 mb for the 41 stations is presented. The experiment was conducted between February 6 and February 7, 1975. Brief discussions are given on methods of data processing, changes in the reduction scheme since the AVE 2 pilot experiment, and data accuracy. An example of contact data is presented as well as synoptic charts prepared from the data.

  9. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    IAS Admin

    After Maynard-Smith and Price [1] mathematically derived why a given behaviour or strategy was adopted by a certain proportion of the population at a given time, it was shown that a strategy which is currently stable in a population need not be stable in evolutionary time (across generations). Additionally it was sug-.

  10. Energy balance at the soil atmosphere interface

    NARCIS (Netherlands)

    Sedighi, M; Hepburn, B.D.P.; Thomas, HR; Vardon, P.J.

    2016-01-01

    Soil atmospheric interactions play an important role within the thermal energy balance and seasonal temperature variations of the ground. This paper presents a formulation for the surface boundary conditions related to interactions between soil and atmosphere. The boundary condition formulated

  11. Two stable steady states in the Hodgkin-Huxley axons

    OpenAIRE

    Aihara, K.; Matsumoto, G.

    1983-01-01

    Two stable steady states were found in the numerical solution of the Hodgkin-Huxley equations for the intact squid axon bathed in potassium-rich sea water with an externally applied inward current. Under the conditions the two stable steady-states exist, the Hodgkin-Huxley equations have a complex bifurcation structure including, in addition to the two stable steady-states, a stable limit cycle, two unstable equilibrium points, and one asymptotically stable equilibrium point. It was also conc...

  12. Quantifying and isolating stable soil organic carbon using long-term bare fallow experiments

    Directory of Open Access Journals (Sweden)

    P. Barré

    2010-11-01

    Full Text Available The stability of soil organic matter (SOM is a major source of uncertainty in predicting atmospheric CO2 concentration during the 21st century. Isolating the stable soil carbon (C from other, more labile, C fractions in soil is of prime importance for calibrating soil C simulation models, and gaining insights into the mechanisms that lead to soil C stability. Long-term experiments with continuous bare fallow (vegetation-free treatments in which the decay of soil C is monitored for decades after all inputs of C have stopped, provide a unique opportunity to assess the quantity of stable soil C. We analyzed data from six bare fallow experiments of long-duration (>30 yrs, covering a range of soil types and climate conditions, and sited at Askov (Denmark, Grignon and Versailles (France, Kursk (Russia, Rothamsted (UK, and Ultuna (Sweden. A conceptual three pool model dividing soil C into a labile pool (turnover time of a several years, an intermediate pool (turnover time of a several decades and a stable pool (turnover time of a several centuries or more fits well with the long term C decline observed in the bare fallow soils. The estimate of stable C ranged from 2.7 g C kg−1 at Rothamsted to 6.8 g C kg−1 at Grignon. The uncertainty associated with estimates of the stable pool was large due to the short duration of the fallow treatments relative to the turnover time of stable soil C. At Versailles, where there is least uncertainty associated with the determination of a stable pool, the soil contains predominantly stable C after 80 years of continuous bare fallow. Such a site represents a unique research platform for characterization of the nature of stable SOM and its vulnerability to global change.

  13. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  14. Atmospheric Neutrinos

    Directory of Open Access Journals (Sweden)

    Takaaki Kajita

    2012-01-01

    Full Text Available Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses atmospheric neutrino experiments and the neutrino oscillation studies with these neutrinos.

  15. Normal modified stable processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Shephard, N.

    2002-01-01

    This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...... Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process...

  16. Applications of stable isotopes

    International Nuclear Information System (INIS)

    Letolle, R.; Mariotti, A.; Bariac, T.

    1991-06-01

    This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

  17. Atmospheric electrodynamics

    International Nuclear Information System (INIS)

    Volland, H.

    1984-01-01

    The book Atmospheric Electrodynamics, by Hans Voland is reviewed. The book describes a wide variety of electrical phenomena occurring in the upper and lower atmosphere and develops the mathematical models which simulate these processes. The reviewer finds that the book is of interest to researchers with a background in electromagnetic theory but is of only limited use as a reference work

  18. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    , the conceptual foundations and protocols for the production of atmosphere in architecture might be found beneath the surface of contemporary debates. In this context, the notion of atmospheric dispositif – illustrated through an oeuvre of the German architect Werner Ruhnau and its theoretical and historical...

  19. Urban atmospheres.

    Science.gov (United States)

    Gandy, Matthew

    2017-07-01

    What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

  20. Partitioning evapotranspiration fluxes with water stable isotopic measurements: from the lab to the field

    Science.gov (United States)

    Quade, M. E.; Brueggemann, N.; Graf, A.; Rothfuss, Y.

    2017-12-01

    Water stable isotopes are powerful tools for partitioning net into raw water fluxes such as evapotranspiration (ET) into soil evaporation (E) and plant transpiration (T). The isotopic methodology for ET partitioning is based on the fact that E and T have distinct water stable isotopic compositions, which in turn relies on the fact that each flux is differently affected by isotopic kinetic effects. An important work to be performed in parallel to field measurements is to better characterize these kinetic effects in the laboratory under controlled conditions. A soil evaporation laboratory experiment was conducted to retrieve characteristic values of the kinetic fractionation factor (αK) under varying soil and atmospheric water conditions. For this we used a combined soil and atmosphere column to monitor the soil and atmospheric water isotopic composition profiles at a high temporal and vertical resolution in a nondestructive manner by combining micro-porous membranes and laser spectroscopy. αK was calculated by using a well-known isotopic evaporation model in an inverse mode with the isotopic composition of E as one input variable, which was determined using a micro-Keeling regression plot. Knowledge on αK was further used in the field (Selhausen, North Rhine-Westphalia, Germany) to partition ET of catch crops and sugar beet (Beta vulgaris) during one growing season. Soil and atmospheric water isotopic profiles were measured automatically across depths and heights following a similar modus operandi as in the laboratory experiment. Additionally, a newly developed continuously moving elevator was used to obtain water vapor isotopic composition profiles with a high vertical resolution between soil surface, plant canopy and atmosphere. Finally, soil and plant samples were collected destructively to provide a comparison with the traditional isotopic methods. Our results illustrate the changing proportions of T and E along the growing season and demonstrate the

  1. Measurement-based J(NO2) sensitivity in a cloudless atmosphere under low aerosol loading and high solar zenith angle conditions

    International Nuclear Information System (INIS)

    Frueh, B.; Trautmann, T.

    2000-01-01

    The comparison between measured and simulated photodissociation frequencies of NO 2 , J(NO 2 ), in a cloudless atmosphere in a recent paper by Frueh et al., 2000 (Journal of Geophysical Research 105, 9843-9857) revealed an overestimation of J(NO 2 ) near ground level by model calculations compared with measurements and an underestimation in the upper part of the aerosol layer. A possible reason for the disagreement is the changing sun position during the vertical ascent. To resolve this problem we carried out a sensitivity study varying the solar zenith angle of 74 o by 1.4 o (which corresponds to the change of sun position during the vertical flight patterns). This results in a considerable deviation of J(NO 2 ) of about 10%. Further sensitivity studies on J(NO 2 ) have been done. These include realistic variations in ground albedo, humidity and aerosol properties. A variation in ground albedo from the measured value of A G = 0.023 (292-420 nm wavelength) to A G = 0 and A G = 0.05, respectively, resulted in an average J(NO 2 ) reduction and enhancement of only 2% near ground level with a slight decrease with increasing altitude. Furthermore, we compared simulations based on different relative humidity profiles with results from a dry atmosphere. Compared to the dry case the deviations of J(NO 2 ) were considerable (5-16%) although the measured aerosol concentration was very low. Moreover, we doubled the aerosol particle concentration. The maximum J(NO 2 ) deviations were in the same order of magnitude as for the relative humidity (5-16%). These changes are in the range of measurement uncertainty of J(NO 2 ) (author)

  2. Analysing Stable Time Series

    National Research Council Canada - National Science Library

    Adler, Robert

    1997-01-01

    We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...

  3. Applicability of a high-resolution meso-scale meteorological model to a near-field-scale atmospheric dispersion problem

    International Nuclear Information System (INIS)

    Takimoto, Hiroshi; Michioka, Takenobu; Sato, Ayumu; Sada, Koichi

    2015-01-01

    This study examines the feasibility of numerical simulations using a meso-scale meteorological model (NuWFAS: Numerical Weather Forecasting and Analysis System) for a near-field-scale atmospheric dispersion problem. A series of observation data from a field tracer experiment was used for the validation of the model. In the experiments, the tracer was released from a tower at a height of 95 m. The receptors were located on the arc lines with distances from the source of 400, 750, 1500, and 3000 m. The numerical simulations were implemented with two different minimum spatial resolutions of 100 m and 300 m. The meteorological fields were reproduced with a reasonable accuracy, showing the less dependency on the mesh sizes of the simulation. The dispersion fields were also less dependent on the spatial resolutions except for the stable atmospheric conditions. In stable conditions, the smaller spatial resolution leads to the higher surface concentrations due to the larger turbulent diffusions. In most cases, the predicted surface concentrations agreed with the observation within the factor of ten. However, the simulation tends to underestimate the surface concentrations in stable conditions, whereas it overestimates in unstable conditions. Our study revealed that the limitation of the model in estimating the turbulent diffusion coefficients for thermally stratified conditions is the one cause of these trends. The current model underestimates the influences of atmospheric stability, which is one of the most important factors for the near-field-scale atmospheric dispersion. (author)

  4. Hygroscopic properties of atmospheric aerosol particles over the Eastern Mediterranean: implications for regional direct radiative forcing under clean and polluted conditions

    Directory of Open Access Journals (Sweden)

    M. Stock

    2011-05-01

    Full Text Available This work examines the effect of direct radiative forcing of aerosols in the eastern Mediterranean troposphere as a function of air mass composition, particle size distribution and hygroscopicity, and relative humidity (RH. During intensive field measurements on the island of Crete, Greece, the hygroscopic properties of atmospheric particles were determined using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA and a Hygroscopicity Differential Mobility Analyzer-Aerodynamic Particle Sizer (H-DMA-APS. Similar to former studies, the H-TDMA identified three hygroscopic sub-fractions of particles in the sub-μm range: a more hygroscopic group, a less hygroscopic group and a nearly hydrophobic particle group. The average hygroscopic particle growth factors at 90 % RH were a significant function of particle mobility diameter (Dp: 1.42 (± 0.05 at 30 nm compared to 1.63 (± 0.07 at 250 nm. The H-DMA-APS identified up to three hygroscopic sub-fractions at mobility diameters of 1.0 and 1.2 μm. The data recorded between 12 August and 20 October 2005 were classified into four distinct synoptic-scale air mass types distinguishing between different regions of origin (western Mediterranean vs. the Aegean Sea as well as the degree of continental pollution (marine vs. continentally influenced. The hygroscopic properties of particles with diameter Dp≥150 nm showed the most pronounced dependency on air mass origin, with growth factors in marine air masses exceeding those in continentally influenced air masses. Particle size distributions and hygroscopic growth factors were used to calculate aerosol light scattering coefficients at ambient RH using a Mie model. A main result was the pronounced enhancement of particle scattering over the eastern Mediterranean due to hygroscopic growth, both in the marine and continentally influenced air masses. When RH reached its summer daytime values around 70

  5. Thermochemical Properties of the 1-Ethyl-3-Methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquid under Conditions of Equilibrium with Atmospheric Moisture

    Science.gov (United States)

    Ramenskaya, L. M.; Grishina, E. P.; Kudryakova, N. O.

    2018-01-01

    Thermochemical properties of the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquid [EMim]NTf2 containing moisture absorbed from the atmosphere (0.242 wt %) are investigated. The phase behavior and thermal stability relative to salt dried in vacuum are studied by means of thermogravimetry and differential scanning calorimetry at different heating and cooling rates. The glass transition, crystallization, and melting temperatures, the enthalpies of phase transitions, and the changes in heat capacity during the formation of glass are determined. It is established that the absorbed water crystallizes at a temperature of around -40.6°C and has virtually no effect on the thermal stability and phase behavior of the salt. Rapid cooling results in the ionic liquid transitioning into the glass state at -91.7 °C and the formation of three mesophases with different melting temperatures; one crystalline modification that melts at a temperature of -19.3°C forms upon slow cooling.

  6. The effect of different gas permeability of packaging on physicochemical and microbiological parameters of pork loin storage under high O2 modified atmosphere packaging conditions.

    Science.gov (United States)

    Marcinkowska-Lesiak, Monika; Poławska, Ewa; Wierzbicka, Agnieszka

    2017-03-01

    The aim of this study was to determine the influence of different packaging materials on meat quality during cold storage. Therefore pork loins (m. longissimus thoracis et lumborum) obtained from crossbred pigs (Polish Landrance x Duroc, n = 6) were stored at 2 ℃ in modified atmosphere packs (80% O 2 , 20% CO 2 ) in four types of trays, which differ in gas permeability. Physicochemical (headspace gas composition, pH, colour, drip loss, cooking loss, shear force, the basic composition and fatty acid profile) and microbiological ( Salmonella spp., Escherichia coli, Enterobacteriaceae, total aerobic plates count, total psychrotrophic bacteria count, the number of lactic acid bacteria, Pseudomonas spp., the general amount of yeast and mold) parameters were monitored for up to 12 days. At the end of the storage period no differences in most physicochemical properties of pork loin due to type of packaging were found, however trays with high gas permeability had the greatest impact on total aerobic plates count and Pseudomonas spp. growth.

  7. The effect of sage, sodium erythorbate and a mixture of sage and sodium erythorbate on the quality of turkey meatballs stored under vacuum and modified atmosphere conditions.

    Science.gov (United States)

    Karpińska-Tymoszczyk, M

    2010-12-01

    1. The combined effect of sage (S), sodium erythorbate (SE), a mixture of sage and sodium erythorbate (MIX) and vacuum packaging (VP) and modified atmosphere packaging (MAP) on the quality of cooked turkey meatballs stored at 4°C was investigated. The physicochemical properties (colour, MDA, AV, pH, water activity), microbiological quality characteristics (counts of mesophilic and psychrotrophic bacteria, fungi, coliforms and Clostridium sp.) and flavour attributes of meatballs were determined. 2. The values of the colour parameters L*, a* and b* were affected by the additives and packaging method. The colour of meatballs was better protected by sodium erythorbate than by sage or a mixture of sage and sodium erythorbate. The additives effectively stabilised lipids against oxidation and slowed down hydrolytic changes in turkey meatballs. Sage and a mixture of sage and sodium erythorbate showed stronger antioxidant properties than sodium erythorbate added alone. Products with additives were characterised by better sensory quality than control samples. Sage and MIX prevented the growth of mesophilic and psychrotrophic bacteria. All additives inhibited the growth of coliforms. 3. MAP was more effective than VP in maintaining the microbial and sensory quality stability of cooked turkey meatballs. However, VP appears to be a better method as regards the maintaining of lipid stability in turkey meatballs.

  8. Ventilation conditions and atmospheric characteristics of a laboratory uranium mine. Application to the distribution of radioactive particles in the respiratory tract

    International Nuclear Information System (INIS)

    Duport, Philippe.

    1978-09-01

    The CEA laboratory uranium mine and the characteristics of its ventilation are described. A method of measuring air flows based on the determination of a tracer gas was developed. Variations of radon concentrations and of its daughter products concentrations and radioactive equilibrium were observed as a function of the various ventilation rates. Particle size distribution of radioactive aerosols was studied in the laboratory mine when unoperated. Several methods of evaluation of the free fraction were compared, and the application of the laws of aerosol physics to the production of radioactive aerosols in a mine was investigated. A study of radioactive ions showed that the usual equations of atmospheric electricity could be applied to charged radioactive aerosols in a mine. Finally an experimental method was developed in order to directly examine the deposit of an aerosol labelled by radon daughter products in the respiratory tract of animals. The experimental results obtained with aerosols in the particle size range 5.10 -8 - 5.10 -6 were compared to the theoretical data derived from models published in the literature [fr

  9. Coupled study of radionuclides and stable lead isotopes in Western Mediterranean; Etude couplee des radionucleides et des isotopes stables du plomb en Mediterranee occidentale

    Energy Technology Data Exchange (ETDEWEB)

    Miralles, J

    2004-05-15

    The aim of this work is to identified an environmental deposit able to have stored the atmospheric signal over large time-scale leaning our investigations on lead stable isotopes ({sup 206}Pb, {sup 207}Pb, {sup 208}Pb) and radionuclide ({sup 210}Pb, {sup 137}Cs, {sup 239}Pu, {sup 240}Pu) analysis. Owing to prior studies on anthropogenic lead sources, emission intensity and sedimentary accumulation, we choose to investigate the marine sediments of the Western Mediterranean. In the Gulf of Lions, the sedimentary accumulation is 110 {+-} 7 {mu}g.cm{sup -2} high in good agreement with the atmospheric inventory estimate we made from salt marshes of Camargue (99 {mu}g.cm{sup -2}). The reconstructed lead accumulation through a modelling step coupling {sup 210}Pb and stable isotopes corroborates the regional anthropogenic emissions (Ferrand, 1996). Briefly, in this context of the marine sediments are a relevant proxy to study past lead atmospheric concentration over the last hundred years. In the Alboran Sea, the study area is less constrained and more complex in terms of climatic, meteorological and hydrological conditions. The sedimentary inventory is of 153 {+-} 47 {mu}g.cm{sup -2}, 1,5 higher than in the margin sediments of the Gulf of Lions. The analysis of aerosols, sediments and settling particles evidences a continuity between the atmospheric signal and the sedimentary record. In spite of this encouraging results, the knowledge of the Alboran system is still too restricted in order to unambiguously conclude on accuracy of deep marine sediments of this area to study past atmospheric fallouts. (author)

  10. Characterization of Leuconostoc gasicomitatum sp. nov., Associated with Spoiled Raw Tomato-Marinated Broiler Meat Strips Packaged under Modified-Atmosphere Conditions

    Science.gov (United States)

    Björkroth, K. Johanna; Geisen, Rolf; Schillinger, Ulrich; Weiss, Norbert; De Vos, Paul; Holzapfel, Wilhelm H.; Korkeala, Hannu J.; Vandamme, Peter

    2000-01-01

    Lactic acid bacteria (LAB) associated with gaseous spoilage of modified-atmosphere-packaged, raw, tomato-marinated broiler meat strips were identified on the basis of a restriction fragment length polymorphism (RFLP) (ribotyping) database containing DNAs coding for 16S and 23S rRNAs (rDNAs). A mixed LAB population dominated by a Leuconostoc species resembling Leuconostoc gelidum caused the spoilage of the product. Lactobacillus sakei, Lactobacillus curvatus, and a gram-positive rod phenotypically similar to heterofermentative Lactobacillus species were the other main organisms detected. An increase in pH together with the extreme bulging of packages suggested a rare LAB spoilage type called “protein swell.” This spoilage is characterized by excessive production of gas due to amino acid decarboxylation, and the rise in pH is attributed to the subsequent deamination of amino acids. Protein swell has not previously been associated with any kind of meat product. A polyphasic approach, including classical phenotyping, whole-cell protein electrophoresis, 16 and 23S rDNA RFLP, 16S rDNA sequence analysis, and DNA-DNA reassociation analysis, was used for the identification of the dominant Leuconostoc species. In addition to the RFLP analysis, phenotyping, whole-cell protein analysis, and 16S rDNA sequence homology indicated that L. gelidum was most similar to the spoilage-associated species. The two spoilage strains studied possessed 98.8 and 99.0% 16S rDNA sequence homology with the L. gelidum type strain. DNA-DNA reassociation, however, clearly distinguished the two species. The same strains showed only 22 and 34% hybridization with the L. gelidum type strain. These results warrant a separate species status, and we propose the name Leuconostoc gasicomitatum sp. nov. for this spoilage-associated Leuconostoc species. PMID:10966388

  11. Modelling growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to commercial process conditions: chlorine washing and modified atmosphere packaging.

    Science.gov (United States)

    Posada-Izquierdo, Guiomar D; Pérez-Rodríguez, Fernando; López-Gálvez, Francisco; Allende, Ana; Selma, María V; Gil, María I; Zurera, Gonzalo

    2013-04-01

    Fresh-cut iceberg lettuce inoculated with Escherichia coli O157:H7 was submitted to chlorine washing (150 mg/mL) and modified atmosphere packaging on laboratory scale. Populations of E. coli O157:H7 were assessed in fresh-cut lettuce stored at 4, 8, 13 and 16 °C using 6-8 replicates in each analysis point in order to capture experimental variability. The pathogen was able to grow at temperatures ≥8 °C, although at low temperatures, growth data presented a high variability between replicates. Indeed, at 8 °C after 15 days, some replicates did not show growth while other replicates did present an increase. A growth primary model was fitted to the raw growth data to estimate lag time and maximum growth rate. The prediction and confidence bands for the fitted growth models were estimated based on Monte-Carlo method. The estimated maximum growth rates (log cfu/day) corresponded to 0.14 (95% CI: 0.06-0.31), 0.55 (95% CI: 0.17-1.20) and 1.43 (95% CI: 0.82-2.15) for 8, 13 and 16 °C, respectively. A square-root secondary model was satisfactorily derived from the estimated growth rates (R(2) > 0.80; Bf = 0.97; Af = 1.46). Predictive models and data obtained in this study are intended to improve quantitative risk assessment studies for E. coli O157:H7 in leafy green products. Copyright © 2012. Published by Elsevier Ltd.

  12. Graphene Membranes for Atmospheric Pressure Photoelectron Spectroscopy.

    Science.gov (United States)

    Weatherup, Robert S; Eren, Baran; Hao, Yibo; Bluhm, Hendrik; Salmeron, Miquel B

    2016-05-05

    Atmospheric pressure X-ray photoelectron spectroscopy (XPS) is demonstrated using single-layer graphene membranes as photoelectron-transparent barriers that sustain pressure differences in excess of 6 orders of magnitude. The graphene serves as a support for catalyst nanoparticles under atmospheric pressure reaction conditions (up to 1.5 bar), where XPS allows the oxidation state of Cu nanoparticles and gas phase species to be simultaneously probed. We thereby observe that the Cu(2+) oxidation state is stable in O2 (1 bar) but is spontaneously reduced under vacuum. We further demonstrate the detection of various gas-phase species (Ar, CO, CO2, N2, O2) in the pressure range 10-1500 mbar including species with low photoionization cross sections (He, H2). Pressure-dependent changes in the apparent binding energies of gas-phase species are observed, attributable to changes in work function of the metal-coated grids supporting the graphene. We expect atmospheric pressure XPS based on this graphene membrane approach to be a valuable tool for studying nanoparticle catalysis.

  13. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  14. Stable nocturnal spectral characteristics over a vineyard (Conference Presentation)

    Science.gov (United States)

    Prueger, John H.; Alfieri, joesph G.; Hipps, Lawrence E.; Kustas, William P.; Neale, Christopher M.

    2016-10-01

    Vineyards are agricultural surfaces that present a unique structural perturbation to the mean wind flow. As part of the Grape Remote Sensing Atmospheric Profiling and Evapotranspiration Experiment (GRAPEX) a 10-m profile tower of three sonic anemometers at 2, 3.75 and 8 m above ground level in in a mature vineyard having was deployed to measure high frequency diurnal variations of 3-dimensional velocity components (u, v, w) and temperature (T) throughout the growing season. Previous work has been published involving eddy covariance measurements in vineyards but these mostly represented convective daytime unstable conditions. Significantly less has been published about turbulence in vineyards during stable nocturnal periods. Hence, in this study we focused on the nocturnal stable periods under clear skies and relatively light winds typical of the northern portion of California's Central Valley. Our objective was to characterize and evaluate turbulent exchange processes in the layer near the top of a vine canopy during nocturnal periods which are often characterized by weak and intermittent turbulence. Spectra, cospectra and coherence plots were evaluated for nocturnal periods. The spectra suggest there are periods of intermittent turbulence with features indicative of local and regional scale processes. Additionally the impact of the vine structure and spacing on slow meandering flows enhance the decomposition of organized turbulent eddies resulting in intricate mechanical turbulence generated by intermittent eddies that are rapidly decomposed as eddies interact with the vine structure and spacing. Preliminary results will be discussed that provide insight into turbulence characteristics at several heights above a canopy vineyard as affected by vine structure and spacing, wind speed, direction and stable conditions.

  15. The assessment of terrain effect on the atmospheric dispersion using the CTDMPLUS code

    International Nuclear Information System (INIS)

    Jeong, Jong Tae; Yu, Dong Han; Kim, Seung Hwan; Han, Byoung Sub

    1996-12-01

    When the movement of a plume is analyzed under stable conditions in the CTDMPLUS model, the concept of critical height is introduced and the dispersion equation is applied separately to the lift conditions and the wrap conditions, When this model is applied to the dispersion of a plume under stable conditions whose height is larger than the critical height, it is shown that there are some irregular characteristics in the front and back of a hill. This is due to the fact that the value of terrain factor which is determined by the meteorological conditions and terrain characteristics influences the calculation of the dispersion coefficients. Based on these results we can find that these phenomena are determined by the slope of a hill, the location of a hill, height, and the range of long and short axis of vertical cross-section of a hill at each height. The influence of factors related with the dispersion is larger than in vertical direction than in horizontal direction. And as the height of a hill is larger, the influence of terrain factor seems to be proportional to the dispersion coefficients which have relatively small values. Therefore, in the back of a hill which have a smaller value of terrain factor. The vertical dispersion coefficients is influenced by the presence of a hill much more as the atmospheric condition is stable. As a result, the terrain effect is much larger when the atmospheric condition is maintained stable or the distance between the source an the hill is shorter. Through this study we find that the model which can treat terrain effect is essential in the atmospheric dispersion of radioactive materials and the CTDMPLUS model can be used as a useful tool. And it is suggested that modification of a model and experimental study should be made through the continuous effort. (author). 2 tabs., 24 figs., 11 refs

  16. Farmland-atmosphere feedbacks amplify decreases in diffuse nitrogen pollution in a freeze-thaw agricultural area under climate warming conditions.

    Science.gov (United States)

    Gao, Xiang; Ouyang, Wei; Hao, Zengchao; Shi, Yandan; Wei, Peng; Hao, Fanghua

    2017-02-01

    Although climate warming and agricultural land use changes are two of the primary instigators of increased diffuse pollution, they are usually considered separately or additively. This likely lead to poor decisions regarding climate adaptation. Climate warming and farmland responses have synergistic consequences for diffuse nitrogen pollution, which are hypothesized to present different spatio-temporal patterns. In this study, we propose a modeling framework to simulate the synergistic impacts of climate warming and warming-induced farmland shifts on diffuse pollution. Active accumulated temperature response for latitudinal and altitudinal directions was predicted based on a simple agro-climate model under different temperature increments (△T 0 is from 0.8°C to 1.4°C at an interval of 0.2°C). Spatial distributions of dryland shift to paddy land were determined by considering accumulated temperature. Different temperature increments and crop distributions were inserted into Soil and Water Assessment Tool model, which quantified the spatio-temporal changes of nitrogen. Warming led to a decrease of the annual total nitrogen loading (2.6%-14.2%) in the low latitudes compared with baseline, which was larger than the decrease (0.8%-6.2%) in the high latitudes. The synergistic impacts amplified the decrease of the loading in the low and high latitudes at the sub-basin scale. Warming led to a decrease of the loading at a rate of 0.35kg/ha/°C, which was lower than the synergistic impacts (3.67kg/ha/°C) at the watershed level. However, warming led to the slight increase of the annual averaged NO3 (LAT) (0.16kg/ha/°C), which was amplified by the synergistic impacts (0.22kg/ha/°C). Expansion of paddy fields led to a decrease in the monthly total nitrogen loading throughout the year, but amplified an increase in the loading in August and September. The decreased response in spatio-temporal nitrogen patterns is substantially amplified by farmland-atmosphere feedbacks

  17. Interannual variability in the extent and intensity of tropical dry forest deciduousness in the Mexican Yucatan (2000-2016): Drivers and Links to Regional Atmospheric Conditions

    Science.gov (United States)

    Cuba, Nicholas Joseph

    The dry topical forests of the southern Yucatan Peninsula experience multiple natural and anthropogenic disturbances, as well as substantial interannual climate variability that can result in stark interannual differences in vegetation phenology. Dry season deciduousness is a typical response to limit tree water loss during prolonged periods of hot and dry conditions, and this behavior has both direct implications for ecosystem functioning, and the potential to indicate climate conditions when observed using remotely-sensed data. The first research paper of this dissertation advances methods to assess the accuracy of remotely-sensed measurements of canopy conditions using in-situ observations. Linear regression models show the highest correlation (R2 = 0.751) between in-situ canopy gap fraction and Landsat NDWISWIR2. MODIS time series NDWISWIR2 are created for the period March 2000-February 2011, and exhibit stronger correlation with time series of TRMM precipitation data than do MODIS EVI time series (R2= 0.48 vs. R2 = 0.43 in deciduous forest areas). The second paper examines differences between the deciduous phenology of young forest stands and older forest stands. Land-cover maps are overlaid to determine whether forested areas are greater than or less than 22 years old in 2010, and metrics related to deciduous phenology are derived from MODIS EVI2 time series in three years, 2008 to 2011. Statistical tests that compare matched pairs of young (12-22 years) and older (>22 years) forest stand age class samples are used to detect significant differences in metrics related to the intensity and timing of deciduousness. In all three years, younger forests exhibit significantly more intense deciduousness, measured as total seasonal change of EVI2 normalized by annual maximum EVI2 (paccounted for in part by the comparatively low amount of early dry-season rainfall during these years, increasing the rate of desiccation of fuel load, and may arise from the large

  18. Seasonal atmospheric extinction

    International Nuclear Information System (INIS)

    Mikhail, J.S.

    1979-01-01

    Mean monochromatic extinction coefficients at various wavelengths at the Kottamia Observatory site have shown the existence of a seasonal variation of atmospheric extinction. The extinction of aerosol compontnts with wavelengths at winter represent exceedingly good conditions. Spring gives the highest extinction due to aerosol. (orig.)

  19. Corrosion resistance of ceramic materials in pyrochemical reprocessing atmosphere by using molten salt for spent nuclear oxide fuel. Corrosion research under chlorine gas condition

    International Nuclear Information System (INIS)

    Takeuchi, Masayuki; Hanada, Keiji; Koizumi, Tsutomu; Aose, Shinichi; Kato, Toshihiro

    2002-12-01

    Pyrochemical reprocessing using molten salts (RIAR process) has been recently developed for spent nuclear oxide fuel and discussed in feasibility study. It is required to improve the corrosion resistance of equipments such as electrolyzer because the process is operated in severe corrosion environment. In this study, the corrosion resistance of ceramic materials was discussed through the thermodynamic calculation and corrosion test. The corrosion test was basically carried out in alkali molten salt under chlorine gas condition. And further consideration about the effects of oxygen, carbon and main fission product's chlorides were evaluated in molten salt. The result of thermodynamic calculation shows most of ceramic oxides have good chemical stability on chlorine, oxygen and uranyl chloride, however the standard Gibb's free energies with carbon have negative value. On the other hand, eleven kinds of ceramic materials were examined by corrosion test, then silicon nitride, mullite and cordierite have a good corrosion resistance less than 0.1 mm/y. Cracks were not observed on the materials and flexural strength did not reduce remarkably after 480 hours test in molten salt with Cl 2 -O 2 bubbling. In conclusion, these three ceramic materials are most applicable materials for the pyrochemical reprocessing process with chlorine gas condition. (author)

  20. Blood lactate changes in men during graded workloads at normal atmospheric pressure (100 kPa) and under simulated caisson conditions (400 kPa).

    Science.gov (United States)

    Neubauer, B; Tetzlaff, K; Buslaps, C; Schwarzkopf, J; Bettinghausen, E; Rieckert, H

    1999-05-01

    A hyperbaric environment may influence lactate metabolism due to hyperoxia affecting biochemical pathways. The purpose of our study was to determine the blood lactate levels occurring at high workloads in a sample of professional divers under simulated caisson conditions. The ambient air pressure was equivalent to a diving depth of 30 m of seawater (400 kPa). A total of 23 healthy male subjects performed graded bicycle exercise in a dry hyperbaric chamber up to a maximum of 3.5 W kg(-1) body weight at normal (100 kPa) and elevated ambient air pressure (400 kPa). The blood lactate level and the heart rate were measured. In comparison with control conditions, the heart rate and the peripheral blood lactate level were significantly lower at depth for all workloads. The differences between the normobaric and hyperbaric lactate values may be explained by an overall improvement in lactate metabolism at elevated ambient pressure, especially in the working muscles and the organs responsible for the lactate reduction, i.e., the liver. The reduced heart rate may be an effect of the improved tissue oxygen supply at depth.

  1. Modeling char conversion under suspension fired conditions in O{sub 2}/N{sub 2} and O{sub 2}/CO{sub 2} atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Jacob Brix; Peter Arendt Jensen; Anker Degn Jensen [Department of Chemical and Biochemical Engineering, Lyngby (Denmark)

    2011-06-15

    The aim of this investigation has been to model combustion under suspension fired conditions in O{sub 2}/N{sub 2} and O{sub 2}/CO{sub 2} mixtures. Experiments used for model validation have been carried out in an electrically heated Entrained Flow Reactor (EFR) at temperatures between 1173 K and 1673 K with inlet O{sub 2} concentrations between 5 and 28 vol.%. The Coal Combustion Model, COCOMO, includes the three char morphologies: cenospheric char, network char and dense char each divided between six discrete particle sizes. Both combustion and gasification with CO{sub 2} are accounted for and reaction rates include thermal char deactivation, which was found to be important for combustion at high reactor temperatures and high O{sub 2} concentrations. COCOMO show in general good agreement with experimental char conversion profiles at conditions covering zone I-III. From the experimental profiles no effect of CO{sub 2} gasification on char conversion has been found. COCOMO does however suggest that CO{sub 2} gasification in oxy-fuel combustion at low O{sub 2} concentrations can account for as much as 70% of the overall char consumption rate during combustion in zone III. 54 refs., 20 figs., 4 tabs., 2 apps.

  2. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General ... Using some examples of classical games, we show how evolutionary game theory can help understand behavioural decisions of animals.

  3. The Stable Concordance Genus

    OpenAIRE

    Kearney, M. Kate

    2013-01-01

    The concordance genus of a knot is the least genus of any knot in its concordance class. Although difficult to compute, it is a useful invariant that highlights the distinction between the three-genus and four-genus. In this paper we define and discuss the stable concordance genus of a knot, which describes the behavior of the concordance genus under connected sum.

  4. Manifolds admitting stable forms

    Czech Academy of Sciences Publication Activity Database

    Le, Hong-Van; Panák, Martin; Vanžura, Jiří

    2008-01-01

    Roč. 49, č. 1 (2008), s. 101-11 ISSN 0010-2628 R&D Projects: GA ČR(CZ) GP201/05/P088 Institutional research plan: CEZ:AV0Z10190503 Keywords : stable forms * automorphism groups Subject RIV: BA - General Mathematics

  5. Stable isotope studies

    International Nuclear Information System (INIS)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  6. Interactive Stable Ray Tracing

    DEFF Research Database (Denmark)

    Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig

    2017-01-01

    Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...

  7. The stable subgroup graph

    Directory of Open Access Journals (Sweden)

    Behnaz Tolue

    2018-07-01

    Full Text Available In this paper we introduce stable subgroup graph associated to the group $G$. It is a graph with vertex set all subgroups of $G$ and two distinct subgroups $H_1$ and $H_2$ are adjacent if $St_{G}(H_1\\cap H_2\

  8. Evaluating the stability of atmospheric lines with HARPS

    Science.gov (United States)

    Figueira, P.; Pepe, F.; Lovis, C.; Mayor, M.

    2010-06-01

    Context. When searching for extrasolar systems using the radial velocity technique, the need for high-precision measurements implies that a precise wavelength calibration is required. The choice of the calibrator is a particularly important open question in the infra-red domain, where precision and achievements remain inferior to those in the optical. Aims: We investigate the long-term stability of atmospheric lines as a precise wavelength reference and analyze their sensitivity to different atmospheric and observing conditions. Methods: We use HARPS archival data for three bright stars, Tau Ceti, μ Arae, and e Eri, which span 6 years and include high-cadence measurements performed over several nights. We cross-correlate this data with an O2 mask and evaluate both radial velocity and bisector variations to a photon noise level of 1 m/s. Results: We find that the telluric lines in the three data-sets are stable down to 10 m/s (rms) over the 6 years. We also show that the radial velocity variations can be modeled by simple atmospheric models, yielding a final precision of 1-2 m/s. Conclusions: The long-term stability of atmospheric lines was 10 m/s over six years, in spite of atmospheric phenomena. Atmospheric lines can be used as a wavelength reference for short timescale programs, yielding a precision of 5 m/s without any correction. A higher precision, of 2 m/s, can be reached if the atmospheric phenomena are corrected for using the simple atmospheric model described, making it a very competitive method even on long timescales. Based on observations taken at the 3.6 m telescope at La Silla.