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Sample records for ammonia fluxes obtained

  1. Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

    Science.gov (United States)

    Hensen, A.; Nemitz, E.; Flynn, M. J.; Blatter, A.; Jones, S. K.; Sørensen, L. L.; Hensen, B.; Pryor, S. C.; Jensen, B.; Otjes, R. P.; Cobussen, J.; Loubet, B.; Erisman, J. W.; Gallagher, M. W.; Neftel, A.; Sutton, M. A.

    2009-11-01

    The exchange of Ammonia (NH3) between grassland and the atmosphere was determined using Relaxed Eddy Accumulation (REA) measurements. The use of REA is of special interest for NH3, since the determination of fluxes at one height permits multiple systems to be deployed to quantify vertical flux divergence (either due to effects of chemical production or advection). During the Braunschweig integrated experiment four different continuous-sampling REA systems were operated during a period of about 10 days and were compared against a reference provided by independent application of the Aerodynamic Gradient Method (AGM). The experiment covered episodes before and after both cutting and fertilizing and provided a wide range of fluxes -60-3600 ng NH3 m-2 s-1 for testing the REA systems. The REA systems showed moderate to good correlation with the AGM estimates, with r2 values for the linear regressions between 0.3 and 0.82. For the period immediately after fertilization, the REA systems showed average fluxes 20% to 70% lower than the reference. At periods with low fluxes REA and AGM can agree within a few %. Overall, the results show that the continuous REA technique can now be used to measure NH3 surface exchange fluxes. While REA requires greater analytical precision in NH3 measurement than the AGM, a key advantage of REA is that reference sampling periods can be introduced to remove bias between sampling inlets. However, while the data here indicate differences consistent with advection effects, significant improvements in sampling precision are essential to allow robust determination of flux divergence in future studies. Wet chemical techniques will be developed further since they use the adsorptive and reactive properties of NH3 that impedes development of cheaper optical systems.

  2. Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

    Directory of Open Access Journals (Sweden)

    M. A. Sutton

    2009-11-01

    Full Text Available The exchange of Ammonia (NH3 between grassland and the atmosphere was determined using Relaxed Eddy Accumulation (REA measurements. The use of REA is of special interest for NH3, since the determination of fluxes at one height permits multiple systems to be deployed to quantify vertical flux divergence (either due to effects of chemical production or advection. During the Braunschweig integrated experiment four different continuous-sampling REA systems were operated during a period of about 10 days and were compared against a reference provided by independent application of the Aerodynamic Gradient Method (AGM. The experiment covered episodes before and after both cutting and fertilizing and provided a wide range of fluxes −60–3600 ng NH3 m−2 s−1 for testing the REA systems. The REA systems showed moderate to good correlation with the AGM estimates, with r2 values for the linear regressions between 0.3 and 0.82. For the period immediately after fertilization, the REA systems showed average fluxes 20% to 70% lower than the reference. At periods with low fluxes REA and AGM can agree within a few %. Overall, the results show that the continuous REA technique can now be used to measure NH3 surface exchange fluxes. While REA requires greater analytical precision in NH3 measurement than the AGM, a key advantage of REA is that reference sampling periods can be introduced to remove bias between sampling inlets. However, while the data here indicate differences consistent with advection effects, significant improvements in sampling precision are essential to allow robust determination of flux divergence in future studies. Wet chemical techniques will be developed further since they use the adsorptive and reactive properties of NH3 that impedes development of cheaper optical systems.

  3. Inter-comparison of ammonia fluxes obtained using the relaxed eddy accumulation technique

    Directory of Open Access Journals (Sweden)

    A. Hensen

    2008-10-01

    Full Text Available The exchange of NH3 between grassland and the atmosphere was determined using Relaxed Eddy Accumulation (REA measurements. The use of REA is of special interest for NH3, since the determination of fluxes at one height permits multiple systems to be deployed to quantify vertical flux divergence (either due to effects of chemical production or advection. During the Braunschweig integrated experiment four different continuous-sampling REA systems were operated during a period of about 10 days and were compared against a reference provided by independent application of the Aerodynamic Gradient Method (AGM. The experiment covered episodes before, after cutting and fertilising and provided a wide range of fluxes −60–3600 ng NH3 m−2 s−1 for testing the REA systems. The REA systems showed moderate to good correlation with the AGM estimates, with r2 values for the linear regressions between 0.3 and 0.82. For the period immediately after fertilization, the REA systems showed average fluxes 20% to 70% lower than the reference. At periods with low fluxes REA and AGM can agree within a few %. Overall, the results show that the continuous REA technique can now be used to measure NH3 surface exchange fluxes. While REA requires greater analytical precision in NH3 measurement than the AGM, a key advantage of REA is that auto-referencing periods can be introduced to remove bias between sampling inlets. However, while the data here indicate differences consistent with advection effects, further improvements in sampling precision are needed to allow measurement of flux divergence. Wet chemical techniques will be developed further since they use the sticky and reactive properties of NH3 that impedes development of cheaper optical systems.

  4. Inter-comparison of ammonia fluxes obtained using the Relaxed Eddy Accumulation technique

    DEFF Research Database (Denmark)

    Hensen, A.; Nemitz, E.; Flynn, M.J.;

    2009-01-01

    divergence (either due to effects of chemical production or advection). During the Braunschweig integrated experiment four different continuous-sampling REA systems were operated during a period of about 10 days and were compared against a reference provided by independent application of the Aerodynamic...... between 0.3 and 0.82. For the period immediately after fertilization, the REA systems showed average fluxes 20% to 70% lower than the reference. At periods with low fluxes REA and AGM can agree within a few %. Overall, the results show that the continuous REA technique can now be used to measure NH3...... surface exchange fluxes. While REA requires greater analytical precision in NH3 measurement than the AGM, a key advantage of REA is that reference sampling periods can be introduced to remove bias between sampling inlets. However, while the data here indicate differences consistent with advection effects...

  5. Fluxes of ammonia in the coastal marine boundary layer

    DEFF Research Database (Denmark)

    Sørensen, L.L.; Hertel, O.; Skjøth, C.A.;

    2003-01-01

    Concentrations of ammonia in air and ammonium in surface water were measured from a platform in the Southern North Sea close to the Dutch coast. Fluxes were derived from the measurements applying Monin-Obukhov similarity theory and exchange velocities calculated. The fluxes and air concentrations...

  6. Measurements of ammonia concentrations, fluxes and dry deposition velocities to a spruce forest 1991-1995

    DEFF Research Database (Denmark)

    Andersen, H.V.; Hovmand, M.F.; Hummelshøj, P.;

    1999-01-01

    The dry deposition velocities and fluxes of ammonia have been estimated from measurements of the vertical gradient of ammonia and micrometeorology above a spruce forest in western Jutland, Denmark. Measurements have been made in seven periods, each lasting about one week and covering all seasons...... measuring period characterized by easterly winds with dry conditions and high ammonia concentrations, and the emissions might relate to evaporation from ammonia saturated surfaces or emission from mineralization in the forest soil. In general, relatively high net deposition velocities were observed during...... at conditions with easterly winds, the air have passed central Jutland with large emission areas. Some of the relatively low deposition velocities or emissions were observed during conditions with low ammonia concentration and westerly winds. These observations might relate to a compensation point of the forest...

  7. Aqua ammonia 15 N obtaining and application with vainness for sugar-cane fertilization

    International Nuclear Information System (INIS)

    Nitrogen compounds marked with the isotope 15 N are continuously being used in agronomic studies and, when associated to the isotopic dilution technique, they constitute an important tool in clarifying the N cycle. At the Centro de Energia Nuclear na Agricultura (CENA/USP), it was obtained ( 15 NH4)2SO4 enhanced at 3,5% of 15 N atoms, by means of the ionic exchange chromatography technique, which made possible to produce aqua ammonia (15 NH3aq). Four repetitions were taken to the aqua ammonia production process to use the nitrogen compound in the field experiment. In each process 150g of ammonium sulfate enhanced at 3,5% of 15 N atoms was used, obtaining 31,0 ± 1,6 g of aqua ammonia on the average (80% yield), with the same enhancement. The incidence of isotopic dilution has not been observed during the procedure, what made the use of such methodology possible. After obtaining the aqua ammonia 15 N through this procedure, it was added to the vinasse (an equivalent to 50 m3 ha-1 ) in doses that corresponded to 70 kg ha-1 of N-NH3aq. The mixture was applied to the sugar-cane straw on the soil's surface, aimed to the crop's fertilization. The compound's isotopic composition was analyzed by means of a spectrometer of masses ANCA-SL Europe Scientific, while the total-N volatilized, by the micro-Kjeldahl. Method. In accordance to the low NH3 (6,4 ± 1,9 kg ha-1 ) volatilization results, it could be concluded that the application of vinasse and aqua ammonia mixture to the straw on the soil's surface was efficient, due to the vinasse's acid character, which allowed the NH3, in presence of the ion H+, to stay in the NH4+ form in solution. (author)

  8. Flux balance analysis of ammonia assimilation network in E. coli predicts preferred regulation point.

    Directory of Open Access Journals (Sweden)

    Lu Wang

    Full Text Available Nitrogen assimilation is a critical biological process for the synthesis of biomolecules in Escherichia coli. The central ammonium assimilation network in E. coli converts carbon skeleton α-ketoglutarate and ammonium into glutamate and glutamine, which further serve as nitrogen donors for nitrogen metabolism in the cell. This reaction network involves three enzymes: glutamate dehydrogenase (GDH, glutamine synthetase (GS and glutamate synthase (GOGAT. In minimal media, E. coli tries to maintain an optimal growth rate by regulating the activity of the enzymes to match the availability of the external ammonia. The molecular mechanism and the strategy of the regulation in this network have been the research topics for many investigators. In this paper, we develop a flux balance model for the nitrogen metabolism, taking into account of the cellular composition and biosynthetic requirements for nitrogen. The model agrees well with known experimental results. Specifically, it reproduces all the (15N isotope labeling experiments in the wild type and the two mutant (ΔGDH and ΔGOGAT strains of E. coli. Furthermore, the predicted catalytic activities of GDH, GS and GOGAT in different ammonium concentrations and growth rates for the wild type, ΔGDH and ΔGOGAT strains agree well with the enzyme concentrations obtained from western blots. Based on this flux balance model, we show that GS is the preferred regulation point among the three enzymes in the nitrogen assimilation network. Our analysis reveals the pattern of regulation in this central and highly regulated network, thus providing insights into the regulation strategy adopted by the bacteria. Our model and methods may also be useful in future investigations in this and other networks.

  9. DETERMINATION OF AMMONIA MASS EMISSION FLUX FROM HOG WASTE EFFLUENT SPRAYING OPERATION USING OPEN PATH TUNABLE DIODE LASER SPECTROSCOPY WITH VERTICAL RADIAL PLUME MAPPING ANALYSIS

    Science.gov (United States)

    Emission of ammonia from concentrated animal feeding operations represents an increasingly important environmental issue. Determination of total ammonia mass emission flux from extended area sources such as waste lagoons and waste effluent spraying operations can be evaluated usi...

  10. The effects of management on ammonia fluxes over a cut grassland as measured by use of dynamic chambers

    Directory of Open Access Journals (Sweden)

    M. David

    2009-01-01

    Full Text Available Grassland management may lead to strong modification of the canopy structure and hence fluxes of carbon and nitrogen in the soil-plant-atmosphere system. Mowing or grazing removes green leaves, which are often a sink for ammonia. Consequently, the ratio between actively growing leaves and senescing/dead parts of the plants is strongly changed in favour of the latter, which may constitute a large source of ammonia. Moreover, fertilisers are a known source of ammonia through direct volatilisation.

    The effects of grassland management, e.g. growing, cutting and fertilisation, on ammonia emission were investigated using a dynamic chamber. This technique made it possible to monitor ammonia emissions in the field at the plant level. With ammonia-free air at the inlet, the ammonia emissions from mature sward did not exceed 4 ng NH3 m−2 s−1. They were approximately 20 times larger above a sward re-growing after cutting and 200 times larger after fertilisation, where 0.5–1.0% of the applied inorganic nitrogen fertiliser was lost by volatilisation.

    Cutting implied three main changes in ammonia sources and sinks within the canopy: (i physiological changes with nitrogen remobilisation to the growing leaves and increase in senescence, (ii changes in compartment proportions with only 5% of green leaves remaining after cutting as opposed to equal proportions of dead leaves as green leaves before cutting, (iii microclimate changes within the canopy especially for litter with higher turbulence, temperature, and alternation of dry (day and wet (night conditions after cutting. These changes promoted ammonia volatilisation from the litter, which could account for the increased ammonia loss following cutting. Another potential source was the wounded surfaces of the stubble which may have emitted ammonia during bleeding and evaporation of sap containing significant levels of ammonium.

    These results

  11. Ammonia concentrations and fluxes over a forest in the midwestern USA

    DEFF Research Database (Denmark)

    Pryor, S.C.; Barthelmie, R.J.; Sørensen, L.L.;

    2001-01-01

    We present measurements of ammonia (NH3) over a deciduous forest in southern Indiana collected during four field campaigns; two in the spring during the transition to leaf-out and two during the winter. Above canopy NH3 concentrations measured continuously using two Wet Effluent Diffusion Denuders...... indicate mean concentrations of 0.6-1.2 mug m(-3) during the spring and 0.3 mug m(-3) during the winter. Measurements suggest that on average the Forest act as a sink of NH3, with a representative daily deposition flux of 1.8 mg-NH3: m(-2) during the spring. However, on some days during the spring inverted...

  12. The effect of heat fluxes on ammonia emission from swine waste lagoon based on neural network analyses

    Science.gov (United States)

    Understanding factors that affect ammonia emissions from swine waste lagoons or any animal waste receptacles is a necessary first step in deploying potential remediation options. In this study, we examined the various meteorological factors (i.e., air temperatures, solar radiation, and heat fluxes)...

  13. Obtaining and Characterization of Flux-Based Products

    Directory of Open Access Journals (Sweden)

    Cosmina Maria Bogăţean

    2015-11-01

    Full Text Available The purpose of creating this assortment was to remind the public of a long forgotten sugar based product, with a high energy value and which can be easily associated both with plain or mineral water consumption. Also we have taken into consideration the well-known '' home-made'' and ''vintage'' concepts. The purpose of this scientific research is to obtain a laboratory created product, as well as obtaining both the cocoa and the lemon sorbet. In the technological process this type of products can be redefined under a new form. The great advantage comes with the fact that it dosen't currently exit on the market and so it can be considered as being a brand new product. The anbalyses both on the raw materials and on the final deliverable product were done in the Faculty's laboratories and it was proven to meet the standars.

  14. Eddy covariance flux measurements of ammonia by high temperature chemical ionisation mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Sintermann

    2011-03-01

    Full Text Available A system for fast ammonia (NH3 measurements with chemical ionisation mass spectrometry (CIMS based on a commercial Proton Transfer Reaction-Mass Spectrometer (PTR-MS is presented. It uses electron transfer reaction as ionisation pathway and features a drift tube of polyetheretherketone (PEEK and silica-coated steel. Heating the instrumental inlet and the drift tube to 180 °C enabled an effective time resolution of ~1 s and made it possible to apply the instrument for eddy covariance (EC measurements. EC fluxes of NH3 were measured over two agricultural fields in Oensingen, Switzerland, following fertilisations with cattle slurry. Air was aspirated close to a sonic anemometer at a flow of 100 STP L min−1 and was directed through a 23 m long 1/2" PFA tube heated to 150 °C to an air-conditioned trailer where the gas was sub-sampled from the large bypass stream. This setup minimised damping of fast NH3 concentration changes between the sampling point and the actual measurement. High-frequency attenuation loss of the NH3 fluxes of 20 to 40% was quantified and corrected for using an empirical ogive method. The instrumental NH3 background signal showed a minor interference with H2O which was characterised in the laboratory. The resulting correction of the NH3 flux after slurry spreading was less than 1‰. The flux detection limit of the EC system was about 5 ng m−2 s−1 while the accuracy of individual flux measurements was estimated 16% for the high-flux regime during these experiments. The NH3 emissions after broad spreading of the slurry showed an initial maximum of 150 μg m−2 s−1 with a fast decline in the following hours.

  15. Eddy covariance flux measurements of ammonia by electron transfer reaction-mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Sintermann

    2010-11-01

    Full Text Available A system for fast ammonia (NH3 measurements based on a commercial Proton Transfer Reaction-Mass Spectrometer is presented. It uses electron transfer reaction (eTR as ionisation pathway and features a drift tube of polyetheretherketone (PEEK and silica-coated steel. Heating the instrumental inlet and the drift tube to 180° C enabled an effective time resolution of ~1 s and made it possible to apply the eTR-MS for eddy covariance (EC measurements. EC fluxes of NH3 were measured over two agricultural fields in Oensingen, Switzerland, following fertilisations with cattle slurry. Air was aspirated close to a sonic anemometer at a flow of 100 STP L min−1 and was directed through a 23 m long 1/2" PFA tube heated to 150°C to an air-conditioned trailer where the eTR-MS sub-sampled from the large bypass stream. This setup minimised damping of fast NH3 concentration changes between the sampling point and the actual measurement. High-frequency attenuation loss of the NH3 fluxes of 20 to 40% was quantified and corrected for using an empirical ogive method. The instrumental NH3 background signal showed a minor interference with H2O which was characterised in the laboratory. The resulting correction of the NH3 flux after slurry spreading was less than 1‰. The flux detection limit of the EC system was about 5 ng m−2 s−1 while the accuracy of individual flux measurements was estimated 16% for the high-flux regime during these experiments. The NH3 emissions after broad spreading of the slurry showed an initial maximum of 150 μg m2 s−1 with a fast decline in the following hours.

  16. Field Measurements Of Ammonia Fluxes Above A Douglas-fir Forest In Speuld, Holland Using Chemical Ionization Mass Spectrometry (CIMS)

    Science.gov (United States)

    McGillen, M. R.; Gallagher, M. W.; Flynn, M. J.; Percival, C. J.

    2009-12-01

    Ammonia (NH3) is an important component of the atmospheric nitrogenous species on regional scales and is a major contributor to the nitrogen budget across the UK and Western Europe. It represents the major atmospheric alkaline gas and in its interaction with acidic gases such as nitric acid, leads to the formation of particulate matter (e.g., Asman, 1998). As sulphur emissions decline across Western Europe, regions of excess ammonia are becoming more widespread and ammonium nitrate aerosol is becoming a significant component of atmospheric nitrogen . NH3 is efficiently lost to the semi-natural vegetation, typical of many natural ecosystems prevalent in Western Europe. Deposition of atmospheric NH3 to ecosystems can lead to deleterious effects such as eutrophication and acidification of soils, contributing to forest decline and a decrease in biological diversity (e.g., Fangmeier et al., 1994). Ammonia measurements were performed using chemical ionization mass spectrometry (CIMS) utilizing the protonated acetone dimer as the precursor ion. NH3 flux measurements were evaluated using the eddy covariance technique at a height of 46m above ground at Speuld forest. The Speuld fieldsite is a mature plantation of Douglas-fir (Pseudotsuga menziesii), located in the centre of the Netherlands (52°13'N, 5 ° 39'E). Data was collected over a two week period (June 25th - July 8th 2009), and fluxes will be determined using the eddy covariance technique. To the authors’ knowledge, these measurements represent the only NH3 flux measurements using CIMS, indeed few studies exist that directly determine fluxes using the this technique. Eddy covariance flux measurements are the most direct way to estimate NH3 removal near the surface. Preliminary data will be presented and compared with the GRadient Ammonia High Accuracy Monitor (GRAHAM) method. References: Asman, W. A. H., Sutton, M. A., and Schjorring, J. K.: Ammonia: emission, atmospheric transport and deposition, New Phytol., 139

  17. Using passive flux samplers to determine the ammonia emission from mechanically ventilated animal houses

    NARCIS (Netherlands)

    Mosquera Losada, J.; Ogink, N.W.M.; Scholtens, R.

    2003-01-01

    Ammonia emissions from animal houses are an important environmental issue in the Netherlands. The current technique in the Netherlands to measure ammonia emissions in mechanically ventilated animal houses is the chemiluminescence method (using a NOx monitor after conversion of NH3 to NO). During cam

  18. Development and evaluation of an ammonia bidirectional flux parameterization for air quality models

    Science.gov (United States)

    Ammonia is an important contributor to particulate matter in the atmosphere and can significantly impact terrestrial and aquatic ecosystems. Surface exchange between the atmosphere and biosphere is a key part of the ammonia cycle. New modeling techniques are being developed for u...

  19. The annual ammonia budget of fertilised cut grassland – Part 1: Micrometeorological flux measurements and emissions after slurry application

    Directory of Open Access Journals (Sweden)

    C. Spirig

    2010-02-01

    Full Text Available Two commercial ammonia (NH3 analysers were customised to allow continuous measurements of vertical concentration gradients. The gradients were used to derive ammonia exchange fluxes above a managed grassland site at Oensingen (Switzerland by application of the aerodynamic gradient method. The measurements from July 2006 to October 2007 covered five complete growth-cut cycles and included six applications of liquid cattle slurry. The average accuracy of the flux measurements during unstable and near-neutral conditions was 20% and the detection limit was 10 ng NH3 m−2 s−1. Hence the flux measurements are considered sufficiently accurate for studying typical NH3 deposition rates over growing vegetation. Quantifying the overall emissions after slurry applications required the application of elaborate interpolations because of difficulties capturing the initial emissions during broadspreading of liquid manure. The emissions were also calculated with a mass balance method yielding similar fluxes. NH3 losses after slurry application expressed as percentage of emitted nitrogen versus applied total ammoniacal nitrogen (TAN varied between 4 and 19%, which is roughly a factor of three lower than the values for broadspreading of liquid manure in emission inventories. The comparatively low emission factors appear to be a consequence of the low dry matter content of the applied slurry and soil properties favouring ammonium adsorption.

  20. The annual ammonia budget of fertilised cut grassland – Part 1: Micrometeorological flux measurements and emissions after slurry application

    Directory of Open Access Journals (Sweden)

    C. Spirig

    2009-10-01

    Full Text Available Two commercial ammonia (NH3 analysers were customised to allow continuous measurements of vertical concentration gradients. The gradients were used to derive ammonia exchange fluxes above a managed grassland site at Oensingen (Switzerland by application of the aerodynamic gradient method (AGM. The semi-continuous measurements during 1.5 years covered five complete growth-cut cycles and included six applications of liquid cattle slurry. The average accuracy of the flux measurements during conditions of well established turbulence was 20% and the detection limit 10 ng NH3 m−2 s−1, hence sufficient for studying the background exchange of NH3. Quantifying emissions after slurry applications required the application of elaborate interpolations because of difficulties capturing the initial emissions during manure spreading in some parts of the experiments. The emissions were also calculated with a mass balance method (MBM yielding similar fluxes. NH3 losses after slurry application expressed as percentage of emitted nitrogen versus applied total ammoniacal nitrogen (TAN varied between 4 and 19%, which is lower than typical values for broadspreading of liquid manure. The comparatively low emission factors appear to be a consequence of the rather thin slurry applied here and soil properties favouring ammonium adsorption.

  1. Influence of gas-particle partitioning on ammonia and nitric acid fluxes above a deciduous forest in the Midwestern USA

    DEFF Research Database (Denmark)

    Hansen, Kristina; Sørensen, Lise Lotte; Hornsby, Karen E.;

    +. Therefore, the phase partitioning between gas and aerosol phases can have a significant effect on local budgets and atmospheric transport distances (Nemitz et al., Atmos. Chem. Phys., 2004). In this study, fluxes of NH3, HNO3 and carbon dioxide (CO2) along with size-resolved N-aerosol concentrations......Quantifying the atmosphere-biosphere exchange of reactive nitrogen gasses (including ammonia (NH3) and nitric acid (HNO3)) is crucial to assessing the impact of anthropogenic activities on natural and semi-natural ecosystems. However, measuring the deposition of reactive nitrogen is challenging due...... to bi-directionality of the flux, and the dynamics of the chemical gas/aerosol equilibrium of NH3 and HNO3 (or other atmospheric acids) with aerosol-phase ammonium (NH4+) and nitrate (NO3-). NH3 and HNO3 are both very reactive and typically exhibit higher deposition velocities than aerosol NH4...

  2. Improved passive flux samplers for measuring ammonia emissions from animal houses, part 1: Basic principles

    NARCIS (Netherlands)

    Scholtens, R.; Hol, J.M.G.; Wagemans, M.J.M.; Phillips, V.R.

    2003-01-01

    At present, precise, expensive and laborious methods with a high resolution in time are needed, to determine ammonia emission rates from animal houses. The high costs for equipment, maintenance and labour limit the number of sites that can be measured. This study examines a new, simpler concept for

  3. Direct and indirect effects of ammonia, ammonium and nitrate on phosphatase activity and carbon fluxes from decomposing litter in peatland.

    Science.gov (United States)

    Johnson, David; Moore, Lucy; Green, Samuel; Leith, Ian D; Sheppard, Lucy J

    2010-10-01

    Here we investigate the response of soils and litter to 5 years of experimental additions of ammonium (NH4), nitrate (NO3), and ammonia (NH3) to an ombrotrophic peatland. We test the importance of direct (via soil) and indirect (via litter) effects on phosphatase activity and efflux of CO2. We also determined how species representing different functional types responded to the nitrogen treatments. Our results demonstrate that additions of NO3, NH4 and NH3 all stimulated phosphatase activity but the effects were dependent on species of litter and mechanism (direct or indirect). Deposition of NH3 had no effect on efflux of CO2 from Calluna vulgaris litter, despite it showing signs of stress in the field, whereas both NO3 and NH4 reduced CO2 fluxes. Our results show that the collective impacts on peatlands of the three principal forms of nitrogen in atmospheric deposition are a result of differential effects and mechanisms on individual components.

  4. Coefficients de-noising with wavelet transform for magnetic flux leakage data obtained from oil pipeline

    Institute of Scientific and Technical Information of China (English)

    Han Wenhua; Que Peiwen

    2005-01-01

    This paper considers the problem of noise cancellation for the magnetic flux leakage (MFL) data obtained from the inspection of oil pipelines. MFL data is contaminated by various sources of noise, and the noise can considerably reduce the detectability of flaw signals in MFL data. This paper presents a new de-noising approach for removing the system noise contained in the MFL data by using the coefficients de-noising with wavelet transform. Experimental results are presented to demonstrate the advantages of this de-noising approach over the conventional wavelet de-noising method.

  5. Background concentrations and fluxes of atmospheric ammonia over a deciduous forest

    DEFF Research Database (Denmark)

    Hansen, K.; Pryor, S. C.; Boegh, E.;

    2015-01-01

    . In this study, we present two months of half-hourly NH3 fluxes and concentrations measured using a Relaxed Eddy Accumulation system during late summer and fall 2013 above a remote forest site in the central Midwest in USA. Supplementary nitric acid (HNO3) flux and size-resolved aerosol-N measurements are used.......11 μg NH3-N m−2 s−1. The wetness of the forest surfaces (assessed using a proxy of time since precipitation) was found to be crucial in controlling both deposition and emission of atmospheric NH3. Size resolved aerosol concentrations (of NH4+, NO3−, Cl− and SO42−) indicated that the aerosol and gas...

  6. An Optimal Estimation Method to Obtain Surface Layer Turbulent Fluxes from Profile Measurements

    Science.gov (United States)

    Kang, D.

    2015-12-01

    In the absence of direct turbulence measurements, the turbulence characteristics of the atmospheric surface layer are often derived from measurements of the surface layer mean properties based on Monin-Obukhov Similarity Theory (MOST). This approach requires two levels of the ensemble mean wind, temperature, and water vapor, from which the fluxes of momentum, sensible heat, and water vapor can be obtained. When only one measurement level is available, the roughness heights and the assumed properties of the corresponding variables at the respective roughness heights are used. In practice, the temporal mean with large number of samples are used in place of the ensemble mean. However, in many situations the samples of data are taken from multiple levels. It is thus desirable to derive the boundary layer flux properties using all measurements. In this study, we used an optimal estimation approach to derive surface layer properties based on all available measurements. This approach assumes that the samples are taken from a population whose ensemble mean profile follows the MOST. An optimized estimate is obtained when the results yield a minimum cost function defined as a weighted summation of all error variance at each sample altitude. The weights are based one sample data variance and the altitude of the measurements. This method was applied to measurements in the marine atmospheric surface layer from a small boat using radiosonde on a tethered balloon where temperature and relative humidity profiles in the lowest 50 m were made repeatedly in about 30 minutes. We will present the resultant fluxes and the derived MOST mean profiles using different sets of measurements. The advantage of this method over the 'traditional' methods will be illustrated. Some limitations of this optimization method will also be discussed. Its application to quantify the effects of marine surface layer environment on radar and communication signal propagation will be shown as well.

  7. Why should we keep measuring zenital dependence of muon flux? Results obtained at Campinas (SP) BR

    CERN Document Server

    Daniel, B; Nunes, M; Vieira, T V; Kemp, E

    2013-01-01

    The zenital dependence of muon flux which reaches the earth's surface is well known as proportional to cos^n(\\theta). Generally, for practical purposes and simplicity in calculations, n is taken as 2. However, compilations of measurements show dependence on the geographical location of the experiments as well as the muons energy range. Since analytical solutions appear to be increasingly less necessary because of the higher accessibility to low cost computational power, accurate and precise determination of the value of the exponent n, under different conditions, can be useful in the necessary calculations to estimate signals and backgrounds, either for terrestrial and underground experiments. In this work we discuss a method for measuring n using a simple muon telescope and the results obtained for measurements taken at Campinas (SP), Brazil. After validation of the method, we intend to extend the measurements for different geographic locations due to the simplicity of the method, and thus collect more value...

  8. Anthropogenic point and non-point nitrogen inputs into Huai River Basin and their impacts on riverine ammonia-nitrogen flux

    OpenAIRE

    W. S. Zhang; D. P. Swaney; Li, X.Y.; Hong, B.; Howarth, R. W.; Ding, S. H.

    2015-01-01

    This study provides a new approach to estimate both anthropogenic non-point and point nitrogen (N) inputs to the landscape, and determines their impacts on riverine ammonia-nitrogen (AN) flux, providing a foundation for further exploration of anthropogenic effects on N pollution. Our study site is Huai River Basin of China, a watershed with one of the highest levels of N input in the world. Multi-year average (2003–2010) inputs of N to the watershed are 27 2...

  9. Soil-atmosphere exchange of ammonia in a non-fertilized grassland: measured emission potentials and inferred fluxes

    Science.gov (United States)

    Wentworth, G. R.; Murphy, J. G.; Gregoire, P. K.; Cheyne, C. A. L.; Tevlin, A. G.; Hems, R.

    2014-10-01

    A 50-day field study was carried out in a semi-natural, non-fertilized grassland in south-western Ontario, Canada during the late summer and early autumn of 2012. The purpose was to explore surface-atmosphere exchange processes of ammonia (NH3) with a focus on bi-directional fluxes between the soil and atmosphere. Measurements of soil pH and ammonium concentration ([NH4+]) yielded the first direct quantification of soil emission potential (Γsoil = [NH4+]/[H+]) for this land type, with values ranging from 35 to 1850 (an average of 290). The soil compensation point, the atmospheric NH3 mixing ratio below which net emission from the soil will occur, exhibited both a seasonal trend and diurnal trend. Higher daytime and August compensation points were attributed to higher soil temperature. Soil-atmosphere fluxes were estimated using NH3 measurements from the Ambient Ion Monitor Ion Chromatograph (AIM-IC) and a simple resistance model. Vegetative effects were ignored due to the short canopy height and significant Γsoil. Inferred fluxes were, on average, 2.6 ± 4.5 ng m-2 s-1 in August (i.e. net emission) and -5.8 ± 3.0 ng m-2 s-1 in September (i.e. net deposition). These results are in good agreement with the only other bi-directional exchange study in a semi-natural, non-fertilized grassland. A Lagrangian dispersion model (Hybrid Single-Particle Lagrangian Integrated Trajectory - HYSPLIT) was used to calculate air parcel back-trajectories throughout the campaign and revealed that NH3 mixing ratios had no directional bias throughout the campaign, unlike the other atmospheric constituents measured. This implies that soil-atmosphere exchange over a non-fertilized grassland can significantly moderate near-surface NH3 concentrations. In addition, we provide indirect evidence that dew and fog evaporation can cause a morning increase of [NH3]g. Implications of our findings on current NH3 bi-directional exchange modelling efforts are also discussed.

  10. Soil-atmosphere exchange of ammonia in a non-fertilized grassland: measured emission potentials and inferred fluxes

    Directory of Open Access Journals (Sweden)

    G. R. Wentworth

    2014-05-01

    Full Text Available A 50 day field study was carried out in a semi-natural, non-fertilized grassland in south-western Ontario, Canada during the late summer and early autumn of 2012. The purpose was to explore surface–atmosphere exchange processes of ammonia (NH3 with a focus on bi-directional fluxes between the soil and atmosphere. Measurements of soil pH and ammonium concentration ([NH4+] yielded the first direct quantification of soil emission potential (Γsoil=[NH4+]/[H+] for this land type, with values ranging from 35 to 1850 (an average of 290. The soil compensation point, the atmospheric NH3 mixing ratio below which net emission from the soil will occur, exhibited both a seasonal trend and diurnal trend. Higher daytime and August compensation points were attributed to higher soil temperature. Soil-atmosphere fluxes were estimated using NH3 measurements from the Ambient Ion Monitor Ion Chromatograph (AIM-IC and a~simple resistance model. Vegetative effects were neglected due to the short canopy height and significant Γsoil. Inferred fluxes were, on average, 2.6 ± 4.5 ng m−2 s−1 in August (i.e. net emission and −5.8 ± 3.0 ng m−2 s−1 in September (i.e. net deposition. These results are in good agreement with the only other bi-directional exchange study in a semi-natural, non-fertilized grassland. A Lagrangian dispersion model (HYSPLIT was used to calculate air parcel back trajectories throughout the campaign and revealed that NH3 mixing ratios had no directional bias throughout the campaign, unlike the other atmospheric constituents measured. This implies that soil-atmosphere exchange over a non-fertilized grassland can significantly moderate near-surface NH3 concentrations. In addition, we provide indirect evidence that dew and fog evaporation can cause a morning increase of [NH3(g]. Implications of our findings on current NH3 bi-directional exchange modelling efforts are also discussed.

  11. Cd{sub 1−x}Zn{sub x}S thin films with low Zn content obtained by an ammonia-free chemical bath deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Carreón-Moncada, I. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, Av. Industria Metalúrgica 1062, CP. 25900, Ramos Arizpe, Coah., México (Mexico); González, L.A., E-mail: luis.gonzalez@cinvestav.edu.mx [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, Av. Industria Metalúrgica 1062, CP. 25900, Ramos Arizpe, Coah., México (Mexico); Pech-Canul, M.I. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, Av. Industria Metalúrgica 1062, CP. 25900, Ramos Arizpe, Coah., México (Mexico); Ramírez-Bon, R. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Apartado Postal 1-798, CP. 76001 Querétaro, Qro., México (Mexico)

    2013-12-02

    Cd{sub 1−x}Zn{sub x}S films with low Zn content were obtained on glass substrates by an ammonia-free chemical bath deposition process. Alkaline reaction solutions were prepared using cadmium chloride, zinc chloride, sodium citrate, thiourea and potassium hydroxide. As a result of varying the mixture ratio between Cd and Zn precursors, microstructural studies from X-ray diffraction reveal that the resulting films have hexagonal, wurzite type, crystalline structure with changes in the preferential growth orientation. Important changes on the surface morphology and thickness of the Cd{sub 1−x}Zn{sub x}S films were also observed as effects of adding Zn to the CdS lattice. Optical studies show that Cd{sub 1−x}Zn{sub x}S thin films with energy band gaps in the range from 2.48 to 2.65 eV were obtained. - Highlights: • Cd{sub 1−x}Zn{sub x}S layers were grown on glass by ammonia-free chemical bath deposition • Films with low Zn content were obtained using reaction solutions with pH11.5 • Zn addition produced changes on the orientation growth and morphology of the films • Cd{sub 1−x}Zn{sub x}S films have energy band gap values from 2.48 to 2.65 eV.

  12. Spatial distribution of the neutron flux in the IEA-R1 reactor core obtained by means of foil activation

    International Nuclear Information System (INIS)

    A three-dimensional distribution of the neutron flux in IEA-R1 reactor, obtained by activating gold foils, is presented. The foils of diameter 8mm and thickness 0,013mm were mounted on lucite plates and located between the fuel element plates. Foil activities were measured using a 3x3 inches Nal(Tl) scintilation detector calibrated against a 4πβγ coincidence detector. Foil positions were chosen to minimize the errors of measurement; the overall estimated error on the measured flux is 5%. (Author)

  13. System N transporters are critical for glutamine release and modulate metabolic fluxes of glucose and acetate in cultured cortical astrocytes: changes induced by ammonia.

    Science.gov (United States)

    Zielińska, Magdalena; Dąbrowska, Katarzyna; Hadera, Mussie Ghezu; Sonnewald, Ursula; Albrecht, Jan

    2016-01-01

    Glutamine (Gln) is synthesized in astrocytes from glutamate (Glu) and ammonia, whereupon it can be released to be transferred to neurons. This study evaluated the as yet not definitely established role of the astrocytic Gln transporters SN1 and SN2 (Slc38a3 and Slc38a5 respectively) in Gln release and metabolic fluxes of glucose and acetate, the canonical precursors of Glu. Cultured neocortical astrocytes were grown in the absence or presence of ammonia (5 mM NH4 Cl, 24 h), which deregulates astrocytic metabolism in hyperammonemic encephalopathies. HPLC analyses of cell extracts of SN1/SN2 siRNA-treated (SN1/SN2-) astrocytes revealed a ~ 3.5-fold increase in Gln content and doubling of glutathione, aspartate, alanine and glutamate contents, as compared to SN1/SN2+ astrocytes. Uptake and efflux of preloaded [(3) H]Gln was likewise significantly decreased in SN1/SN2- astrocytes. The atom percent excess (13) C values (given as M + 1) for alanine, aspartate and glutamate were decreased when the SN1/SN2- cells were incubated with [1-(13) C] glucose, while Gln consumption was not changed. No difference was seen in M + 1 values in SN1/SN2- cells incubated with [2-(13) C] acetate, which were not treated with ammonia. In SN1/SN2- astrocytes, the increase in Gln content and the decrease in radiolabeled Gln release upon exposure to ammonia were found abrogated, and glutamate labeling from [2-(13) C]acetate was decreased as compared to SN1/SN2+ astrocytes. The results underscore a profound role of SN1 and/or SN2 in Gln release from astrocytes under physiological conditions, but less so in ammonia-overexposed astrocytes, and appear to manifest dependence of astrocytic glucose metabolism to Glu/Gln on unimpaired SN1/SN2- mediated Gln release from astrocytes. The astrocytic N system transporters SN1 and SN2 show preponderance to mediate glutamine (Gln) efflux. Under hyperammonemic conditions, accumulation of Gln, a direct product of ammonia detoxification, may deregulate

  14. Anthropogenic point-source and non-point-source nitrogen inputs into Huai River basin and their impacts on riverine ammonia-nitrogen flux

    Science.gov (United States)

    Zhang, W. S.; Swaney, D. P.; Li, X. Y.; Hong, B.; Howarth, R. W.; Ding, S. H.

    2015-07-01

    This study provides a new approach to estimate both anthropogenic non-point-source and point-source nitrogen (N) inputs to the landscape, and determines their impacts on riverine ammonia-nitrogen (AN) flux, providing a foundation for further exploration of anthropogenic effects on N pollution. Our study site is Huai River basin of China, a water-shed with one of the highest levels of N input in the world. Multi-year average (2003-2010) inputs of N to the watershed are 27 200 ± 1100 kg N km-2 yr-1. Non-point sources comprised about 98 % of total N input, and only 2 % of inputs are directly added to the aquatic ecosystem as point sources. Fertilizer application was the largest non-point source of new N to the Huai River basin (69 % of net anthropogenic N inputs), followed by atmospheric deposition (20 %), N fixation in croplands (7 %), and N content of imported food and feed (2 %). High N inputs showed impacts on riverine AN flux: fertilizer application, point-source N input, and atmospheric N deposition were proved as more direct sources to riverine AN flux. Modes of N delivery and losses associated with biological denitrification in rivers, water consumption, interception by dams may influence the extent of export of riverine AN flux from N sources. Our findings highlight the importance of anthropogenic N inputs from both point sources and non-point sources in heavily polluted watersheds, and provide some implications for AN prediction and management.

  15. Rejection of seamless pipe noise in magnetic flux leakage data obtained from gas pipeline inspection

    Science.gov (United States)

    Afzal, Muhammad; Udpa, Satish; Udpa, Lalita; Lord, William

    2000-05-01

    Natural gas is traditionally transmitted from production facilities to customer locations through a vast pipeline network. A major segment of this network employs seamless pipes. This is especially true for smaller diameter transmission and distribution lines. Manufacturing process associated with the production of seamless pipes contribute to a helical variation in the pipe along the axis. The deformation introduces an artifact in the data obtained from MFL inspection of these pipelines. This seamless pipe noise is usually correlated with signals generated by defects and other elements (joints, tees, etc.) in pipelines, and can therefore, mask their indications in MFL data. This warrants the need for methods to improve signal-to-noise ratio (SNR) in MFL data from seamless pipes. This paper presents a technique for detecting signals in MFL data from seamless pipes. The approach processes the data in various steps. First, a wavelet based denoising technique is applied to reduce the noise due to instrumentation and other sources. An adaptive filtering approach is then applied to reject seamless noise in the data. Since the inspection of pipelines typically generates vast amounts of data, it is imperative that the algorithm be computationally efficient. The processing method has to be robust in that it should be data independent. The approach described in this paper meet these criteria. Results from application of the approach to data from field tests are presented.

  16. Simple model for the prediction of ammonia volatilization from water basin: effect of water temperature and pH

    Directory of Open Access Journals (Sweden)

    Intamanee, J.

    2004-03-01

    Full Text Available Ammonia is a primary chemical used for preserving rubber latex. Consequently, the wastewater from concentrated rubber latex processing contains high ammonia concentration. The volatilization of ammonia from such wastewater may cause an air pollution problem such as the formation of an acid rain or an aerosol of ammonium nitrate and ammonium sulfate, which can seriously affect environment and human being. To assess the air pollution problem regarding atmospheric ammonia volatized from wastewater, the model for the prediction of ammonia volatilization rate and flux is therefore desirable. The purposes of this study were to investigate the effects of water temperature and pH on ammonia volatilization process and to develop a model to describe ammonia volatilization rate and flux including such effects.Ammonia volatilization from water was studied by using a volatilization tank (surface area = 780 cm2, volume = 7 L placed in a water bath in order to control the water temperature. The temperature and pH in the range of 25 to 50ºC and 5 to 11 were respectively investigated. The overall mass transfer coefficients of ammonia were measured as a function of temperature and pH. The quadratic multiple regression technique was used to obtain the model for mass transfer coefficient from experimental data. The model suggests that the overall mass transfer coefficient of ammonia increases with increasing water temperature and pH while the temperature-pH interaction retards the increasing characteristic of mass transfer coefficient. Thus the increasing in mass transfer coefficient at higher temperature and pH was slower than that at the lower one. The simple model for the prediction of ammonia volatilization rate and flux was developed based on mass transfer theory and mass transfer coefficient model obtained from this study. This simple ammonia emission model can be used to predict ammonia volatilization rate and flux at any pH, water temperature and

  17. [Characteristics and Transport Patterns of Ammonia, Nitrites, Nitrates and Inorganic Nitrogen Flux at Epikarst Springs and a Subterranean Stream in Nanshan, Chongqing].

    Science.gov (United States)

    Zhang, Yuan-zhu; He, Qiu-fang; Jiang, Yong-jun; Li, Yong

    2016-04-15

    In a karst groundwater system, it develops complex multiple flows because of its special geological structure and unique physical patterns of aquifers. In order to investigate the characteristics and transport patterns of ammonia, nitrite and nitrate in epikarst water and subterranean stream, the water samples were collected monthly in a fast-urbanizing karst region. The results showed distinctive characteristics of three forms of inorganic nitrogen. The concentration of inorganic nitrogen was stable in the epikarst water while it was fluctuant in the subterranean stream. Epikarst water was less affected by rainfall and sewage compared with subterranean stream. In epikarst water, the nitrate concentration was much higher than the ammonia concentration. Dissolved inorganic nitrogen, mainly from non-point source pollution related to agricultural activities, passed in and out of the epikarst water based on a series of physical; chemical and biological processes in the epikarst zone, such as ammonification, adsorption and nitrification. On the contrary, subterranean stream showed a result of NH₄⁺-N > NO₃⁻-N in dry seasons and NO₃⁻-N > NH₄⁺-N in rainy seasons. This can be due to the fact that sanitary and industrial sewage flowed into subterranean river through sinkholes, fissures and grikes in dry season. Dissolved inorganic nitrogen in subterranean river was mainly from the non-point source pollution in wet season. Non-point source pollutants entered into subterranean water by two transport ways, one by penetration along with vadose flow through fissures and grikes, and the other by conduit flow through sinkholes from the surface runoff, soil water flow and epikarst flow. The export flux of DIN was 56.05 kg · (hm² · a)⁻¹, and NH₄⁺-N and NO₃⁻-N accounted for 46.03% and 52.51%, respectively. The contributions of point-source pollution and non point-source pollution to the export flux of DIN were 25.08% and 74.92%, respectively, based on run

  18. The final power calibration of the IPEN/MB-01 nuclear reactor for various configurations obtained from the measurements of the absolute average neutron flux

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alexandre Fonseca Povoa da, E-mail: alexandre.povoa@mar.mil.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Bitelli, Ulysses d' Utra; Mura, Luiz Ernesto Credidio; Lima, Ana Cecilia de Souza; Betti, Flavio; Santos, Diogo Feliciano dos, E-mail: ubitelli@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The use of neutron activation foils is a widely spread technique applied to obtain nuclear parameters then comparing the results with those calculated using specific methodologies and available nuclear data. By irradiation of activation foils and subsequent measurement of its induced activity, it is possible to determine the neutron flux at the position of irradiation. The power level during operation of the reactor is a parameter which is directly proportional to the average neutron flux throughout the core. The objective of this work is to gather data from irradiation of gold foils symmetrically placed along a cylindrically configured core which presents only a small excess reactivity in order to derive the power generated throughout the spatial thermal and epithermal neutron flux distribution over the core of the IPEN/MB-01 Nuclear Reactor, eventually lending to a proper calibration of its nuclear channels. The foils are fixed in a Lucite plate then irradiated with and without cadmium sheaths so as to obtain the absolute thermal and epithermal neutron flux. The correlation between the average power neutron flux resulting from the gold foils irradiation, and the average power digitally indicated by the nuclear channel number 6, allows for the calibration of the nuclear channels of the reactor. The reactor power level obtained by thermal neutron flux mapping was (74.65 ± 2.45) watts to a mean counting per seconds of 37881 cps to nuclear channel number 10 a pulse detector, and 0.719.10{sup -5} ampere to nuclear linear channel number 6 (a non-compensated ionization chamber). (author)

  19. Modeling the effect of heat fluxes on ammonia and nitrous oxide emissions from an anaerobic swine waste treatment lagoon using artificial neural network

    Science.gov (United States)

    Understanding factors that affect ammonia and nitrous emissions from anaerobic swine waste treatment lagoons or any animal waste receptacles is a necessary first step in deploying potential remediation options. In this study, we examined the various meteorological factors (i.e., air temperatures, s...

  20. Aquatic carbon fluxes in HD: using in-situ sensors to obtain a high definition picture of carbon cycling in streams (Invited)

    Science.gov (United States)

    Clow, D. W.; Dornblaser, M.; Saraceno, J.; Pellerin, B. A.; Mast, A.; Shanley, J. B.

    2013-12-01

    In-situ sensors provide a means to collect water-quality data in streams at time resolutions ranging from minutes to days, weeks, or months. Instruments may be deployed individually to investigate specific constituents of interest or in sensor arrays to provide a more complete picture for a suite of related compounds. Data from the instruments can provide direct measurements of some constituents (e.g., nitrate or dissolved CO2), or may be used as surrogates for other parameters (e.g., FDOM as a surrogate for DOC). These data may be used to improve estimates of nutrient or carbon fluxes, and to investigate processes influencing high-frequency variability in constituent concentrations. In this study, we examine high-temporal-resolution data from a suite of sensor arrays installed in mountain streams in Rocky Mountain National Park, Colorado. The sensor arrays include fluorescing dissolved organic matter (FDOM), turbidity, and CO2 sensors, which are being used to characterize variability in dissolved and particulate forms of carbon. We will (1) compare these data to concentrations obtained through manual grab sampling to document the utility of in-situ measurements as surrogates for dissolved organic carbon (DOC) and particulate organic carbon (POC), (2) compare stream-water fluxes of carbon calculated using a conventional sample-based approach to those computed using high-temporal resolution data from in-situ sensors, and (3) use ancillary data from co-located stream gages (e.g. streamflow) and meteorological stations (e.g., solar radiation) to investigate the influences of hydrology and climate on high-frequency variability in carbon fluxes in streams.

  1. The relationship between ammonia emissions from a poultry farm and soil NO and N2O fluxes from a downwind source

    Directory of Open Access Journals (Sweden)

    S. Tang

    2005-08-01

    Full Text Available Intensive livestock farms emit large concentrations of NH3, most of which is deposited very close to the source. The presence of trees enhances the deposition. Rates to down wind forests can exceed 40 kg N ha-1. The steep gradient in large NH3 concentration and deposition at the edge of a downwind forest to background concentrations within a few hundred meters provides an ideal site to study the effect of different rates of N deposition on biological and chemical processes under similar environmental conditions. We have investigated the effect of different rates of NH3 deposition (62, 45, 24 and 5 kg NH3-N ha-1 y-1 on the flux of NO and N2O from soil in a mixed woodland downwind of a large poultry farm (160000 birds in Scotland, which has been operating for about 40 years. Measurements were carried out for a 6 month period, with hourly NO flux measurements, daily N2O fluxes close to the farm and monthly at all sites and monthly cumulative wet and dry N deposition. The increased NH3 and NH4+ deposition to the woodland increased emissions of NO and N2O and soil available NH4+ and NO3- concentrations. Average NO and N2O fluxes measured 15, 25 and 45 m downwind of the farm were 111.2±41.1, 123.3±40.7, 38.3±28.8 µg NO-N m-2 h-1 and 9.9±7.5, 34.3±33.3 and 21.2±6.1 µg NO-N m-2 h-1, respectively. At the background site 270 m downwind the N2O flux was reduced to 1.75±2.1 µg N2O-N m-2 h-1. NO emissions were significantly influenced by seasonal and daily changes in soil temperature and followed a diurnal pattern with maximum emissions approximately 3h after noon. For N2O no consistent diurnal pattern was observed. Changes in soil moisture content had a less clear effect on the NO and N2O flux. On average the NO emissions expressed as a fraction of the elevated N deposited were 7.1% (at 15 m, 6% (at 25 m and 2.3% (at 45 m downwind of the farm, whereas for N2O the emissions were only 2.8% (at 15 m, 3% (at 25 m and 3% (at 45 m downwind. These

  2. Ammonia emissions from deciduous forest after leaf fall

    Directory of Open Access Journals (Sweden)

    K. Hansen

    2013-07-01

    Full Text Available The understanding of biochemical feedback mechanisms in the climate system is lacking knowledge in relation to bi-directional ammonia (NH3 exchange between natural ecosystems and the atmosphere. We therefore study the atmospheric NH3 fluxes during a 25-day period during autumn 2010 (21 October to 15 November for the Danish beech forest Lille Bøgeskov to address the hypothesis that NH3 emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH3 fluxes and model calculations. Vegetation status was observed using plant area index (PAI and leaf area index (LAI. NH3 fluxes were measured using the relaxed eddy accumulation (REA method. The REA-based NH3 concentrations were compared to NH3 denuder measurements. Model calculations of the atmospheric NH3 concentration were obtained with the Danish Ammonia MOdelling System (DAMOS. The relative contribution from the forest components to the atmospheric NH3 flux was assessed using a simple two-layer bi-directional canopy compensation point model. A total of 57.7% of the fluxes measured showed emission and 19.5% showed deposition. A clear tendency of the flux going from deposition of −0.25 ± 0.30 μg NH3-N m−2 s−1 to emission of up to 0.67 ± 0.28 μg NH3-N m−2 s−1 throughout the measurement period was found. In the leaf fall period (23 October to 8 November, an increase in the atmospheric NH3 concentrations was related to the increasing forest NH3 flux. Following leaf fall, the magnitude and temporal structure of the measured NH3 emission fluxes could be adequately reproduced with the bi-directional resistance model; it suggested the forest ground layer (soil and litter to be the main contributing component to the NH3 emissions. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall, but during and after leaf fall, the modelled concentrations are too low. The results indicate that the

  3. Diffusion of ammonia gas in PDMS characterized by ATR spectroscopy

    Science.gov (United States)

    Levinský, Petr; Kalvoda, Ladislav; Aubrecht, Jan; Fojtíková, Jaroslava

    2015-01-01

    The kinetic parameters of a chemo-optical transducer layer sensitive to gaseous ammonia are characterized by means of attenuation total reflection method. The tested layer consists of cross-linked polydimethylsiloxane matrix sensitized by quinoline-based organometallic dye showing the selective chemical reaction with ammonia. Upper and lower limits of the ammonia diffusion coefficient and the ammonia-dye reaction constant are derived from the obtained experimental data and compared with other data available in literature and obtained from computer simulations.

  4. Surface/atmosphere exchange of ammonia over grazed pasture.

    OpenAIRE

    Plantaz, M.A.H.G.

    1998-01-01

    This thesis deals with the exchange of ammonia between the atmosphere and grazed pasture in an area of intensive livestock breeding. The term exchange is used because gaseous ammonia can be taken up (dry deposition) as well as released (emission) by this type of surface.Ammonia exchange fluxes over the grass pasture of a research farm for dairy cattle breeding at Zegveld (the Netherlands) were measured continuously from July 1992 until July 1994. The main objective was to investigate the long...

  5. Molecular Characterization of Soil Ammonia-Oxidizing Bacteria Based on the Genes Encoding Ammonia Monooxygenase

    OpenAIRE

    Alzerreca, Jose Javier

    1999-01-01

    Ammonia-oxidizing bacteria (AOB) are chemolithotrophs that oxidize ammonia/ammonium to nitrite in a two-step process to obtain energy for survival. AOB are difficult to isolate from the environment and iso lated strains may not represent the diversity in soil. A genetic database and molecular tools were developed based on the ammonia monooxygenase (AMO) encoding genes that can be used to assess the diversity of AOB that exist in soil and aquatic environments without the isolation of pure cult...

  6. Direct Measurements of the Surface-Atmosphere Exchange of Ammonia

    Science.gov (United States)

    Tevlin, A.; Murphy, J. G.; Wentworth, G.; Gregoire, P.

    2012-12-01

    As the dominant atmospheric base, ammonia plays an important role in the formation and growth of inorganic aerosols. Surface-atmosphere exchange of ammonia has been observed to occur as a bidirectional flux governed by the relative magnitudes of atmospheric gas phase concentration and a temperature-dependent surface compensation point. In order to better characterise the links between gas-particle and surface-atmosphere exchanges, more direct measurements of these exchanges are necessary. Eddy Covariance (EC) can provide the most direct surface-atmosphere flux measurements, but its requirement for high frequency data combined with the reactive nature of ammonia have limited its application for this species. In order to address this lack, an investigation into the instrumental sensitivity and time response requirements for EC ammonia flux measurements was carried out using a Quantum Cascade-Tunable Infrared Laser Differential Absorption Spectrometer (QC-TILDAS) capable of measuring ammonia concentration at 10 Hz. Time response was additionally improved through the use of a heated sample line and custom glass inlet, and the system was deployed over a short grass field in rural Ontario. The ammonia measurements were used along with three dimensional sonic anemometer wind speed data to calculate EC ammonia fluxes. When combined with simultaneous measurements of the inorganic composition of gas and particle phases made by Ambient Ion Monitor - Ion Chromatography (AIM-IC), these flux measurements can provide insight into the links between gas-particle and surface-atmosphere exchange.

  7. Calibration of the nuclear power channels of the IPEN/MB-01 reactor obtained from the measurements of the spatial thermal neutron flux distribution in the reactor core through the irradiation of infinitely diluted gold foils

    International Nuclear Information System (INIS)

    Several nuclear parameters are obtained through the gamma spectrometry of targets irradiated in a research reactor core and this is the case of the activation foils which make possible, through the measurements of the activity induced, to determine the neutron flux in the place where they had been irradiated. The power level operation of the reactor is a parameter directly proportional to the average neutron flux in the core. This work aims to get the power operation of the reactor through of spatial neutron flux distribution in the core of IPEN/MB-01 reactor by the irradiation of infinitely diluted gold foils and prudently located in its interior. These foils were made in the form of metallic alloy in concentration levels such that the phenomena of flux disturbance, as the self-shielding factors to neutrons become worthless. These activation foils has only 1% of dispersed gold atoms in an aluminium matrix content of 99% of this element. The irradiations of foils have been carried through with and without cadmium plate. The total correlation between the average thermal neutron flux obtained by irradiation of infinitely diluted activation foils and the average digital value of current of the nuclear power channels 5 and 6 (non-compensated ionization chambers - CINC), allow the calibration of the nuclear channels of the IPEN/MB-01 reactor. (author)

  8. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  9. Assessing Ammonia Treatment Options

    Science.gov (United States)

    This is the second of three articles to help water system operators understand ammonia and how to monitor and control its effects at the plant and in the distribution system. The first article (Opflow, April 2012) provided an overview of ammonia's chemistry, origins, and water sy...

  10. Method for forming ammonia

    Science.gov (United States)

    Kong, Peter C.; Pink, Robert J.; Zuck, Larry D.

    2008-08-19

    A method for forming ammonia is disclosed and which includes the steps of forming a plasma; providing a source of metal particles, and supplying the metal particles to the plasma to form metal nitride particles; and providing a substance, and reacting the metal nitride particles with the substance to produce ammonia, and an oxide byproduct.

  11. Ammonia transformation in a biotrickling air filter

    DEFF Research Database (Denmark)

    Nielsen, Lars Peter; Nielsen, Marie Louise; Andersen, Mathias;

    2007-01-01

    measurements and model was obtained by using conventional substrate and inhibition kinetics of ammonium and nitrite oxidizing bacteria. Highest rates of ammonia removal were observed in the central section of the filter. Near the air outlet and water inlet the process was ammonia limited, while high nitrous...... acid concentrations almost excluded any biological activity near the air inlet and water outlet. Nitrous acid inhibition also stabilized pH at 6.5-7 all through the filter. Being sensitive to both ammonia and nitrous acid the nitrite oxidation process occurred mainly in the filter sections near the air...... outlet / water inlet, and only 8% of the nitrite was turned into nitrate. Water supply only exceeded evaporation by 20% but modelling indicated that additional watering would have limited effect on filter efficiency. The filter was also robust to varying loading, as a 4-fold increase in ammonia inlet...

  12. Ammonia emissions from beech forest after leaf fall – measurements and modelling

    Directory of Open Access Journals (Sweden)

    K. Hansen

    2012-11-01

    Full Text Available The understanding of biochemical feed-back mechanisms in the climate system is lacking knowledge in relation to bi-directional ammonia (NH3 exchange between natural ecosystems and the atmosphere. We therefore study the atmospheric NH3 fluxes during a 25 days period during autumn 2010 (21 October–15 November for the Danish beech forest, Lille Bøgeskov, to address the hypothesis that NH3 emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH3 fluxes and model calculations. Vegetation status was observed using plant area index (PAI and leaf area index (LAI. NH3 fluxes were measured using the relaxed eddy accumulation (REA method. The REA based NH3 concentrations were compared to NH3 denuder measurements. Model calculations were obtained with the Danish Ammonia MOdelling System (DAMOS. 57.7% of the fluxes measured showed emission and 19.5% showed deposition. The mean NH3 flux was 0.087 ± 0.19 μg NH3-N m−2 s−1. A clear tendency of the flux going from negative (deposition to positive (emission fluxes of up to 0.96 ± 0.40 μg NH3-N m−2 s−1 throughout the measurement period was found. In the leaf fall period (23 October–8 November, an increase in the atmospheric NH3 concentrations was related to the increasing forest NH3 flux. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall. During and after leaf fall, the modelled concentrations are too low. The results indicate that the missing contribution to atmospheric NH3 concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH

  13. Using ammonia as a sustainable fuel

    Science.gov (United States)

    Zamfirescu, C.; Dincer, I.

    In this study, ammonia is identified as a sustainable fuel for mobile and remote applications. Similar to hydrogen, ammonia is a synthetic product that can be obtained either from fossil fuels, biomass, or other renewable sources. Some advantages of ammonia with respect to hydrogen are less expensive cost per unit of stored energy, higher volumetric energy density that is comparable with that of gasoline, easier production, handling and distribution with the existent infrastructure, and better commercial viability. Here, the possible ways to use ammonia as a sustainable fuel in internal combustion engines and fuel-cells are discussed and analysed based on some thermodynamic performance models through efficiency and effectiveness parameters. The refrigeration effect of ammonia, which is another advantage, is also included in the efficiency calculations. The study suggests that the most efficient system is based on fuel-cells which provide simultaneously power, heating and cooling and its only exhaust consists of water and nitrogen. If the cooling effect is taken into consideration, the system's effectiveness reaches 46% implying that a medium size car ranges over 500 km with 50 l fuel at a cost below 2 per 100 km. The cooling power represents about 7.2% from the engine power, being thus a valuable side benefit of ammonia's presence on-board.

  14. Reactor for removing ammonia

    Science.gov (United States)

    Luo, Weifang; Stewart, Kenneth D.

    2009-11-17

    Disclosed is a device for removing trace amounts of ammonia from a stream of gas, particularly hydrogen gas, prepared by a reformation apparatus. The apparatus is used to prevent PEM "poisoning" in a fuel cell receiving the incoming hydrogen stream.

  15. Ammonia Clouds on Jupiter

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

  16. Crystal Structure of an Ammonia-Permeable Aquaporin.

    Science.gov (United States)

    Kirscht, Andreas; Kaptan, Shreyas S; Bienert, Gerd Patrick; Chaumont, François; Nissen, Poul; de Groot, Bert L; Kjellbom, Per; Gourdon, Pontus; Johanson, Urban

    2016-03-01

    Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants.

  17. Crystal Structure of an Ammonia-Permeable Aquaporin.

    Directory of Open Access Journals (Sweden)

    Andreas Kirscht

    2016-03-01

    Full Text Available Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants.

  18. Crystal Structure of an Ammonia-Permeable Aquaporin.

    Science.gov (United States)

    Kirscht, Andreas; Kaptan, Shreyas S; Bienert, Gerd Patrick; Chaumont, François; Nissen, Poul; de Groot, Bert L; Kjellbom, Per; Gourdon, Pontus; Johanson, Urban

    2016-03-01

    Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants. PMID:27028365

  19. Ammonia Induces Autophagy through Dopamine Receptor D3 and MTOR.

    Science.gov (United States)

    Li, Zhiyuan; Ji, Xinmiao; Wang, Wenchao; Liu, Juanjuan; Liang, Xiaofei; Wu, Hong; Liu, Jing; Eggert, Ulrike S; Liu, Qingsong; Zhang, Xin

    2016-01-01

    Hyperammonemia is frequently seen in tumor microenvironments as well as in liver diseases where it can lead to severe brain damage or death. Ammonia induces autophagy, a mechanism that tumor cells may use to protect themselves from external stresses. However, how cells sense ammonia has been unclear. Here we show that culture medium alone containing Glutamine can generate milimolar of ammonia at 37 degrees in the absence of cells. In addition, we reveal that ammonia acts through the G protein-coupled receptor DRD3 (Dopamine receptor D3) to induce autophagy. At the same time, ammonia induces DRD3 degradation, which involves PIK3C3/VPS34-dependent pathways. Ammonia inhibits MTOR (mechanistic target of Rapamycin) activity and localization in cells, which is mediated by DRD3. Therefore, ammonia has dual roles in autophagy: one to induce autophagy through DRD3 and MTOR, the other to increase autophagosomal pH to inhibit autophagic flux. Our study not only adds a new sensing and output pathway for DRD3 that bridges ammonia sensing and autophagy induction, but also provides potential mechanisms for the clinical consequences of hyperammonemia in brain damage, neurodegenerative diseases and tumors.

  20. Ammonia in the environment: From ancient times to the present

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, M.A.; Erisman, J.W.; Dentener, F.; Moller, D. [Centre for Ecology and Hydrology, Penicuik (United Kingdom). Edinburgh Research Station

    2008-12-15

    Recent research on atmospheric ammonia has made good progress in quantifying sources/sinks and environmental impacts. This paper reviews the achievements and places them in their historical context. It considers the role of ammonia in the development of agricultural science and air chemistry, showing how these arose out of foundations in 18th century chemistry and medieval alchemy, and then identifies the original environmental sources from which the ancients obtained ammonia. Ammonia is revealed as a compound of key human interest through the centuries, with a central role played by sal ammoniac in alchemy and the emergence of modern science. The review highlights how recent environmental research has emphasized volatilization sources of ammonia. Conversely, the historical records emphasize the role of high-temperature sources, including dung burning, coal burning, naturally burning coal seams and volcanoes. Present estimates of ammonia emissions from these sources are based on few measurements, which should be a future priority.

  1. Ammonia emissions from deciduous forest after leaf fall

    DEFF Research Database (Denmark)

    Hansen, Kristina; Sørensen, Lise Lotte; Hertel, Ole;

    2013-01-01

    to 15 November) for the Danish beech forest Lille Bøgeskov to address the hypothesis that NH3 emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH3 fluxes and model calculations. Vegetation status was observed using plant...... area index (PAI) and leaf area index (LAI). NH3 fluxes were measured using the relaxed eddy accumulation (REA) method. The REA-based NH3 concentrations were compared to NH3 denuder measurements. Model calculations of the atmospheric NH3 concentration were obtained with the Danish Ammonia MOdelling...... from deposition of −0.25 ± 0.30 μg NH3-N m−2 s−1 to emission of up to 0.67 ± 0.28 μg NH3-N m−2 s−1 throughout the measurement period was found. In the leaf fall period (23 October to 8 November), an increase in the atmospheric NH3 concentrations was related to the increasing forest NH3 flux. Following...

  2. Treatment of biomass to obtain ethanol

    Science.gov (United States)

    Dunson, Jr., James B.; Elander, Richard T.; Tucker, III, Melvin P.; Hennessey, Susan Marie

    2011-08-16

    Ethanol was produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

  3. Hydrolyzabilities of different corn stover fractions after aqueous ammonia pretreatment.

    Science.gov (United States)

    Sun, Zongping; Ge, Xiaoyan; Xin, Donglin; Zhang, Junhua

    2014-02-01

    The effect of aqueous ammonia pretreatment on the hydrolysis of different corn stover fractions (rind, husk, leaf, and pith) by xylanase (XYL) with cellulases (CELs) was evaluated. The aqueous ammonia pretreatment had excellent delignification ability (above 66%) for different corn stover fractions. The corn rind exhibited the lowest susceptibility to aqueous ammonia pretreatment. The pretreated rind showed the lowest hydrolyzability by CEL and XYL, which was supported by a high content of crystalline cellulose in the hydrolyzed residues of rind, as confirmed by X-ray diffraction (XRD). With the addition of 1 mg XYL/g dry matter, a high glucose yield (above 90%) could be obtained from the pretreated rind by CEL. The results revealed that a high hydrolyzate yield of corn rind after aqueous ammonia pretreatment could be obtained with 1 mg xylanase/g dry matter, showing that aqueous ammonia pretreatment and xylanase addition to cellulases have great potential for the efficient hydrolysis of corn stover without previous fractionation.

  4. Respiratory ammonia output and blood ammonia concentration during incremental exercise

    NARCIS (Netherlands)

    Ament, W; Huizenga, [No Value; Kort, E; van der Mark, TW; Grevink, RG; Verkerke, GJ

    1999-01-01

    The aim of this study was to investigate whether the increase of ammonia concentration and lactate concentration in blood was accompanied by an increased expiration of ammonia during graded exercise. Eleven healthy subjects performed an incremental cycle ergometer test. Blood ammonia, blood lactate

  5. Detection of Ammonia-Oxidizing Archaea in Fish Processing Effluent Treatment Plants

    OpenAIRE

    Devivaraprasad Reddy, A.; Subrahmanyam, Gangavarapu; Shivani Kallappa, Girisha; Karunasagar, Iddya; Karunasagar, Indrani

    2014-01-01

    Ammonia oxidation is the rate limiting step in nitrification and thus have an important role in removal of ammonia in natural and engineered systems with participation of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). However, their relative distribution and activity in fish processing effluent treatment plants (FPETPs) though significant, is hitherto unreported. Presence of AOA in sludge samples obtained from FPETPs was studied by amplification and sequencing of t...

  6. Liberation of ammonia by cyanobacteria

    International Nuclear Information System (INIS)

    Photoheterotrophic nitrogen-fixing cyanobacteria release ammonia when treated with methionine sulfoximine (MSX) to inhibit nitrogen incorporation into protein. This released ammonia can be derived from recently fixed nitrogen (nitrogen atmosphere) or endogenous reserves (argon atmosphere). Anaerobic ammonia release requires light and is stimulated by the photosystem II herbicides DCMU and Atrazine, regardless of the source of ammonia. As much as one quarter of the total cellular nitrogen can be released as ammonia by cyanbacteria treated with MSX and DCMU under argon in light. Chromatography of cell extracts indicates that virtually all cellular proteins are degraded. DCMU and Atrazine, at very low concentration, inhibit sustained uptake of the ammonia analog 14C methylamine. These data indicate that the herbicides interrupt ammonia uptake and retention by the cells, and support a role for photosystem II in ammonia metabolism

  7. Ammonia downstream from HH 80 North

    Science.gov (United States)

    Girart, Jose M.; Rodriguez, Luis F.; Anglada, Guillem; Estalella, Robert; Torrelles, Jose, M.; Marti, Josep; Pena, Miriam; Ayala, Sandra; Curiel, Salvador; Noriega-Crespo, Alberto

    1994-01-01

    HH 80-81 are two optically visible Herbig-Haro (HH) objects located about 5 minutes south of their exciting source IRAS 18162-2048. Displaced symmetrically to the north of this luminous IRAS source, a possible HH counterpart was recently detected as a radio continuum source with the very large array (VLA). This radio source, HH 80 North, has been proposed to be a member of the Herbig-Haro class since its centimeter flux density, angular size, spectral index, and morphology are all similar to those of HH 80. However, no object has been detected at optical wavelengths at the position of HH 80 North, possibly because of high extinction, and the confirmation of the radio continuum source as an HH object has not been possible. In the prototypical Herbig-Haro objects HH 1 and 2, ammonia emission has been detected downstream of the flow in both objects. This detection has been intepreted as a result of an enhancement in the ammonia emission produced by the radiation field of the shock associated with the HH object. In this Letter we report the detection of the (1,1) and (2,2) inversion transitions of ammonia downstream HH 80 North. This detection gives strong suppport to the interpretation of HH 80 North as a heavily obscured HH object. In addition, we suggest that ammonia emission may be a tracer of embedded Herbig-Haro objects in other regions of star formation. A 60 micrometer IRAS source could be associated with HH 80 North and with the ammonia condensation. A tentative explanation for the far-infrared emission as arising in dust heated by their optical and UV radiation of the HH object is presented.

  8. Net summertime emission of ammonia from corn and triticale fields

    Science.gov (United States)

    Richter, Undine; Smith, Jeremy; Brümmer, Christian

    2016-04-01

    Recent advancements in laser spectrometry offer new opportunities to investigate ecosystem-atmosphere exchange of environmentally relevant trace gases. In this study, we used a quantum cascade laser (QCL) absorption spectrometer to continuously measure high-frequency concentrations of ammonia and the net exchange between an agricultural site and the atmosphere based on the eddy-covariance approach. The footprint was split into two main sectors, one planted with corn (Zea mays) and the other one with triticale. Ammonia concentrations were highly variable between 2 and almost 100 ppb with an average value of 8.1 ppb during the observation period from April to September 2015. While both deposition and emission of ammonia was observed, the total campaign exchange resulted in a loss of 3.3 kg NH3-N ha‑1. Highest average emission fluxes of 65 ng N m‑2 s‑1 were recorded after fertilization at the beginning of the campaign in April and May. Afterwards the exchange of ammonia with the atmosphere decreased considerably, but the site remained on average a consistent source with sporadic lower peaks and an average flux of 13 ng N m‑2 s‑1. While management in the form of fertilization was the main driver for ammonia concentration and exchange at the site, biophysical controls from temperature, wind regime, and surface wetness are also presented.

  9. Recovery of ammonia and sulfate from waste streams and bioenergy production via bipolar bioelectrodialysis.

    Science.gov (United States)

    Zhang, Yifeng; Angelidaki, Irini

    2015-11-15

    Ammonia and sulfate, which are prevalent pollutants in agricultural and industrial wastewaters, can cause serious inhibition in several biological treatment processes, such as anaerobic digestion. In this study, a novel bioelectrochemical approach termed bipolar bioelectrodialysis was developed to recover ammonia and sulfate from waste streams and thereby counteracting their toxicity during anaerobic digestion. Furthermore, hydrogen production and wastewater treatment were also accomplished. At an applied voltage of 1.2 V, nitrogen and sulfate fluxes of 5.1 g NH4(+)-N/m(2)/d and 18.9 g SO4(2-)/m(2)/d were obtained, resulting in a Coulombic and current efficiencies of 23.6% and 77.4%, respectively. Meanwhile, H2 production of 0.29 L/L/d was achieved. Gas recirculation at the cathode increased the nitrogen and sulfate fluxes by 2.3 times. The applied voltage, initial (NH4)2SO4 concentrations and coexistence of other ions were affecting the system performance. The energy balance revealed that net energy (≥ 16.8 kWh/kg-N recovered or ≥ 4.8 kWh/kg-H2SO4 recovered) was produced at all the applied voltages (0.8-1.4 V). Furthermore, the applicability of bipolar bioelectrodialysis was successfully demonstrated with cattle manure. The results provide new possibilities for development of cost-effective technologies, capable of waste resources recovery and renewable energy production.

  10. Fiber Optic Detection of Ammonia Gas

    Directory of Open Access Journals (Sweden)

    L. Kalvoda

    2006-01-01

    Full Text Available Bathochromic shifts accompanying the formation of several bivalent metallic complexes containing 5-(4’-dimethylaminophenylimino quinolin-8-one (L1, and 7-chlore-5(4’-diethylamino-2-methylphenylimino quinolin-8-one (L2 ligands in ethanol solutions were evaluated by VIS-NIR spectroscopy. The [L1-Cu-L1] sulphide complex was selected as a reagent for further tests on optical fibres. Samples of multimode siloxane-clad fused-silica fibre were sensitized by diffusing an ethanol/chloroform solution of the dye into the cladding polymer, and tested by VIS-NIR optical spectroscopy (12 cm long fibre sections, and optical time domain reflectometry (OTDR; 20 ns laser pulses, wavelength 850 nm, 120 m long fibre sensitized within the interval 104–110 m. A well-resolved absorption band of the reagent could be identified in the absorption spectra of the fibres. After exposure to dry ammonia/nitrogen gas with increasing ammonia concentration (0–4000 ppm, the short fibre samples showed subsequent decay of NIR optical absorption; saturation was observed for higher ammonia levels. The concentration resolution r ? 50 ppm and forward response time t90 ? 30 sec were obtained within the interval 0–1000 ppm. The OTDR courses showed an enhancement of the back-scattered light intensity coming from the sensitized region after diffusion of the initial reagent, and decay after exposure to concentrated ammonia/nitrogen gas (10000 ppm.

  11. Nitrocarburising in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2010-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammoniapropene- hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere...... and straightforward control of the carburizing and nitriding potentials is in principle possible. The nitrocarburising response of unalloyed (ARMCO) Fe was investigated in a thermobalance during controlled nitrocarburising at 580°C. The “cases” obtained on nitrocarburised iron were characterized by reflected light...

  12. Ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2012-01-01

    The NEC (National Emission Ceiling) directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries...... technology is adopted quicker and that the farm has the right location. It is concluded that the new application process so far has not lived up to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely...

  13. Ammonia in the environment: From ancient times to the present

    International Nuclear Information System (INIS)

    Recent research on atmospheric ammonia has made good progress in quantifying sources/sinks and environmental impacts. This paper reviews the achievements and places them in their historical context. It considers the role of ammonia in the development of agricultural science and air chemistry, showing how these arose out of foundations in 18th century chemistry and medieval alchemy, and then identifies the original environmental sources from which the ancients obtained ammonia. Ammonia is revealed as a compound of key human interest through the centuries, with a central role played by sal ammoniac in alchemy and the emergence of modern science. The review highlights how recent environmental research has emphasized volatilization sources of ammonia. Conversely, the historical records emphasize the role of high-temperature sources, including dung burning, coal burning, naturally burning coal seams and volcanoes. Present estimates of ammonia emissions from these sources are based on few measurements, which should be a future priority. - Past ammonia applications reveal new emphases in biospheric transformations

  14. Ammonia Partitioning into the Condensed Phase in Winter Time Conditions

    Science.gov (United States)

    Green, J. R.; Bililign, S.; Fiddler, M. N.; Leen, J. B.; Holloway, J. S.; Fibiger, D. L.; McDuffie, E. E.; Thornton, J. A.; Brown, S. S.

    2015-12-01

    Secondary aerosol (SOA) formation has been linked to health problems and environmental damage in regions impacted by the emission of gaseous NH3 and SO2. SOA formation, (NH4)2SO4 and NH4NO3, in the presence of NO NO2, is favored under high relative humidity and low temperature and low temperature conditions. In the East and Mid Atlantic regions of the United States humidity is low in wintertime. Utilizing ambient concentration data of gaseous NO, NO2, SO2 and NH3 collected aboard a survey aircraft we examined the partitioning of gaseous NH3 towards aerosol products. The calculated mixing ratio of gaseous SO2/NH3 correlated with relative humidity will give an indication of the potential SOA formation when the mixing ratio of other reactants is small in the region of interest. The data obtained originates from a series of night and day survey flights on a C-130 aircraft that occurred from February 3 to March 13, 2015 over the Eastern coastal region of the United States extending from New York to Florida. NOx was obtained from the Airborne Ring-down Nitrogen Oxide Laser Detector (ARNOLD) instrument (NOAA) and Thermal Dissociation-Laser Induced Fluorescence (TD-LIF) (UC Berkley). SO2 measurements were done using the TECO 43C SO2 analyzer and for NH3 measurements the an Ammonia Analyzer - Trace (NH3) (Los Gatos Research). Estimates of aerosol dry deposition fluxes are presented.

  15. Separation of ammonia from the ammonia rinsing liquor of resin adsorbed molybdenum and tungsten by membrane technology%膜法分离氨淋洗吸附钼钨树脂后淋洗液中的氨

    Institute of Scientific and Technical Information of China (English)

    胡磊; 肖连生; 张贵清

    2012-01-01

    以钨湿法冶金中的一种氨淋洗吸附钼钨树脂后淋洗液为料液,采用膜分离技术实现氨的分离.通过比较多种纳滤和反渗透膜对钼钨与氨的分离效果,从中选择了一种合适的低压反渗透膜,考察了膜分离过程中原料液浓度、操作压力、浓缩比、温度因素对透过液通量、钼钨截留率、氨回收率(或透过率)以及钼钨与氨分离系数的影响,在操作压力2.41MPa,温度在36℃,浓缩比为4∶1的条件下,透过液通量达27 L/(m2·h),Mo、WO3的截留率接近100%,Mo、WO3与NH3的分离系数分别达18和51,料液中76%的氨得到回收.以实验室的试验结果为依据,选用低压反渗透膜用于工业生产,取得了良好的效果.%A membrane technology was used to separate ammonia from the ammonia rinsing liquor of resin adsorbed molybdenum and tungsten in the process of tungsten hydromctallurgy. Compared with the separating effect of molybdenum-tungsten from ammonia of various nanofiltration membranes and reverse osmosis membranes,a low-pressure RO membrane was selected. The effects of feed liquor concentration, operation pressure,concentration ratio and temperature on the parameters of permeation flux,molybdenum and tungsten retention rate,ammonia recovery rate(or transparence rate),the separation coefficient of Mo and WO3 over ammonia were studied. And the optimum technical conditions, were obtained: operation pressure 2. 41 MPa, temperature 36℃ with concentration ratio 4: 1. Under these conditions, the permeation flux reached 27 L/(m2 · h) with nearly 100% retention rate of Mo and WO3, the recovery rate of ammonia reached 76% and the separation coefficient of Mo and WO3 over NH3 were 18 and 51, respectively. The successful application of this process in industry has delivered good economical benefits.

  16. SIRT5 regulation of ammonia-induced autophagy and mitophagy.

    Science.gov (United States)

    Polletta, Lucia; Vernucci, Enza; Carnevale, Ilaria; Arcangeli, Tania; Rotili, Dante; Palmerio, Silvia; Steegborn, Clemens; Nowak, Theresa; Schutkowski, Mike; Pellegrini, Laura; Sansone, Luigi; Villanova, Lidia; Runci, Alessandra; Pucci, Bruna; Morgante, Emanuela; Fini, Massimo; Mai, Antonello; Russo, Matteo A; Tafani, Marco

    2015-01-01

    In liver the mitochondrial sirtuin, SIRT5, controls ammonia detoxification by regulating CPS1, the first enzyme of the urea cycle. However, while SIRT5 is ubiquitously expressed, urea cycle and CPS1 are only present in the liver and, to a minor extent, in the kidney. To address the possibility that SIRT5 is involved in ammonia production also in nonliver cells, clones of human breast cancer cell lines MDA-MB-231 and mouse myoblast C2C12, overexpressing or silenced for SIRT5 were produced. Our results show that ammonia production increased in SIRT5-silenced and decreased in SIRT5-overexpressing cells. We also obtained the same ammonia increase when using a new specific inhibitor of SIRT5 called MC3482. SIRT5 regulates ammonia production by controlling glutamine metabolism. In fact, in the mitochondria, glutamine is transformed in glutamate by the enzyme glutaminase, a reaction producing ammonia. We found that SIRT5 and glutaminase coimmunoprecipitated and that SIRT5 inhibition resulted in an increased succinylation of glutaminase. We next determined that autophagy and mitophagy were increased by ammonia by measuring autophagic proteolysis of long-lived proteins, increase of autophagy markers MAP1LC3B, GABARAP, and GABARAPL2, mitophagy markers BNIP3 and the PINK1-PARK2 system as well as mitochondrial morphology and dynamics. We observed that autophagy and mitophagy increased in SIRT5-silenced cells and in WT cells treated with MC3482 and decreased in SIRT5-overexpressing cells. Moreover, glutaminase inhibition or glutamine withdrawal completely prevented autophagy. In conclusion we propose that the role of SIRT5 in nonliver cells is to regulate ammonia production and ammonia-induced autophagy by regulating glutamine metabolism.

  17. Electrochemically driven extraction and recovery of ammonia from human urine.

    Science.gov (United States)

    Luther, Amanda K; Desloover, Joachim; Fennell, Donna E; Rabaey, Korneel

    2015-12-15

    Human urine contains high concentrations of nitrogen, contributing about 75% of the nitrogen in municipal wastewaters yet only 1% of the volume. Source separation of urine produces an ideal waste stream for nitrogen and phosphorus recovery, reducing downstream costs of nutrient treatment at wastewater treatment facilities. We examined the efficiency and feasibility of ammonia extraction and recovery from synthetic and undiluted human urine using an electrochemical cell (EC). EC processing of synthetic urine produced an ammonium flux of 384 ± 8 g N m(-2) d(-1) with a 61 ± 1% current efficiency at an energy input of 12 kWh kg(-1) N removed. EC processing of real urine displayed similar performance, with an average ammonium flux of 275 ± 5 g N m(-2) d(-1) sustained over 10 days with 55 ± 1% current efficiency for ammonia and at an energy input of 13 kWh kg(-1) N removed. With the incorporation of an ammonia stripping and absorption unit into the real urine system, 57 ± 0.5% of the total nitrogen was recovered as ammonium sulfate. A system configuration additionally incorporating stripping of the influent headspace increased total nitrogen recovery to 79% but led to reduced performance of the EC as the urine ammonium concentration decrease. Direct stripping of ammonia (NH3) from urine with no chemical addition achieved only 12% total nitrogen recovery at hydraulic retention times comparable with the EC systems. Our results demonstrate that ammonia can be extracted via electrochemical means at reasonable energy inputs of approximately 12 kWh kg(-1) N. Considering also that the hydrogen generated is worth 4.3 kWh kg(-1) N, the net electrical input for extraction becomes approximately 8 kWh kg(-1) N if the hydrogen can be used. Critical for further development will be the inclusion of a passive means for ammonia stripping to reduce additional energy inputs.

  18. Potential for Ammonia Recapture by Farm Woodlands: Design and Application of a New Experimental Facility

    Directory of Open Access Journals (Sweden)

    Mark R. Theobald

    2001-01-01

    Full Text Available There has been increasing pressure on farmers in Europe to reduce the emissions of ammonia from their land. Due to the current financial climate in which farmers have to operate, it is important to identify ammonia control measures that can be adopted with minimum cost. The planting of trees around farmland and buildings has been identified as a potentially effective and low-cost measure to enhance ammonia recapture at a farm level and reduce long-range atmospheric transport. This work assesses experimentally what fraction of ammonia farm woodlands could potentially remove from the atmosphere. We constructed an experimental facility in southern Scotland to simulate a woodland shelterbelt planted in proximity to a small poultry unit. By measuring horizontal and vertical ammonia concentration profiles within the woodland, and comparing this to the concentration of an inert tracer (SF6 we estimate the depletion of ammonia due to dry deposition to the woodland canopy. Together with measurements of mean ammonia concentrations and throughfall fluxes of nitrogen, this information is used to provide a first estimate of the fraction of emitted ammonia that is recaptured by the woodland canopy. Analysis of these data give a lower limit of recapture of emitted ammonia, at the experimental facility, of 3%. By careful design of shelterbelt woodlands this figure could be significantly higher.

  19. Review of Options for Ammonia/Ammonium Management

    Energy Technology Data Exchange (ETDEWEB)

    Nash, C. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-05-06

    This report is a review of literature supporting practical ammonia/ammonium destruction processes. Melter research supporting Hanford Low Activity Waste (LAW) glass production has shown that significant amounts of ammonia will be in the melter offgas condensate. Further work with secondary waste forms indicates the potential need to remove the ammonia, perhaps by an oxidative process. This review finds likely practical chemical methods to oxidize ammonia in aqueous solution at moderate temperatures and atmospheric pressure, using easily obtained reagents. Leading candidates include nitrite oxidation to produce nitrogen gas, various peroxide oxidative processes, and air stripping. This work reviews many other processes and provides reasoning to not consider those processes further for this application.

  20. Lattice dynamics of ammonia

    International Nuclear Information System (INIS)

    The frequencies of selected intermolecular modes of vibration and libration in a single crystal of deuterated ammonia (ND3) have been measured by the technique of coherent inelastic neutron scattering, at temperatures of 20 and 95K. The results are compared with the previous optical measurements at the Γ point, and with calculations based on two different models for the intermolecular potential function. A detailed assessment of these data leads to a set of mode frequencies for the Γ, R, and M points. The elastic constants are calculated from the measured acoustic mode dispersion curves propagating along the three major symmetry directions. The existing intermolecular force models are in good qualitative agreement with experiment, but significant discrepancies remain to be resolved by future theoretical refinements. (author)

  1. [Study on Ammonia Emission Rules in a Dairy Feedlot Based on Laser Spectroscopy Detection Method].

    Science.gov (United States)

    He, Ying; Zhang, Yu-jun; You, Kun; Wang, Li-ming; Gao, Yan-wei; Xu, Jin-feng; Gao, Zhi-ling; Ma, Wen-qi

    2016-03-01

    It needs on-line monitoring of ammonia concentration on dairy feedlot to disclose ammonia emissions characteristics accurately for reducing ammonia emissions and improving the ecological environment. The on-line monitoring system for ammonia concentration has been designed based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology combining with long open-path technology, then the study has been carried out with inverse dispersion technique and the system. The ammonia concentration in-situ has been detected and ammonia emission rules have been analyzed on a dairy feedlot in Baoding in autumn and winter of 2013. The monitoring indicated that the peak of ammonia concentration was 6.11 x 10(-6) in autumn, and that was 6.56 x 10(-6) in winter. The concentration results show that the variation of ammonia concentration had an obvious diurnal periodicity, and the general characteristic of diurnal variation was that the concentration was low in the daytime and was high at night. The ammonia emissions characteristic was obtained with inverse dispersion model that the peak of ammonia emissions velocity appeared at noon. The emission velocity was from 1.48 kg/head/hr to 130.6 kg/head/hr in autumn, and it was from 0.004 5 kg/head/hr to 43.32 kg/head/hr in winter which was lower than that in autumn. The results demonstrated ammonia emissions had certain seasonal differences in dairy feedlot scale. In conclusion, the ammonia concentration was detected with optical technology, and the ammonia emissions results were acquired by inverse dispersion model analysis with large range, high sensitivity, quick response without gas sampling. Thus, it's an effective method for ammonia emissions monitoring in dairy feedlot that provides technical support for scientific breeding.

  2. Ammonia Ice Clouds on Jupiter

    Science.gov (United States)

    2007-01-01

    The top cloud layer on Jupiter is thought to consist of ammonia ice, but most of that ammonia 'hides' from spectrometers. It does not absorb light in the same way ammonia does. To many scientists, this implies that ammonia churned up from lower layers of the atmosphere 'ages' in some way after it condenses, possibly by being covered with a photochemically generated hydrocarbon mixture. The New Horizons Linear Etalon Imaging Spectral Array (LEISA), the half of the Ralph instrument that is able to 'see' in infrared wavelengths that are absorbed by ammonia ice, spotted these clouds and watched them evolve over five Jupiter days (about 40 Earth hours). In these images, spectroscopically identified fresh ammonia clouds are shown in bright blue. The largest cloud appeared as a localized source on day 1, intensified and broadened on day 2, became more diffuse on days 3 and 4, and disappeared on day 5. The diffusion seemed to follow the movement of a dark spot along the boundary of the oval region. Because the source of this ammonia lies deeper than the cloud, images like these can tell scientists much about the dynamics and heat conduction in Jupiter's lower atmosphere.

  3. Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils

    OpenAIRE

    Zhang, Li-Mei; Hu, Hang-Wei; Shen, Ju-Pei; He, Ji-Zheng

    2011-01-01

    Increasing evidence demonstrated the involvement of ammonia-oxidizing archaea (AOA) in the global nitrogen cycle, but the relative contributions of AOA and ammonia-oxidizing bacteria (AOB) to ammonia oxidation are still in debate. Previous studies suggest that AOA would be more adapted to ammonia-limited oligotrophic conditions, which seems to be favored by protonation of ammonia, turning into ammonium in low-pH environments. Here, we investigated the autotrophic nitrification activity of AOA...

  4. 21 CFR 573.180 - Anhydrous ammonia.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Anhydrous ammonia. 573.180 Section 573.180 Food... Additive Listing § 573.180 Anhydrous ammonia. (a) The food additive anhydrous ammonia is applied directly...: (1)(i) The food additive anhydrous ammonia is applied as a component of an aqueous premix...

  5. Treatment of biomass to obtain a target chemical

    Science.gov (United States)

    Dunson, Jr., James B.; Tucker, III, Melvin P.; Elander, Richard T.; Hennessey, Susan Marie

    2010-08-24

    Target chemicals were produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

  6. Atmospheric Fate and Transport of Agricultural Dust and Ammonia

    Science.gov (United States)

    Hiranuma, N.; Brooks, S. D.; Thornton, D. C.; Auvermann, B. W.; Fitz, D. R.

    2008-12-01

    Agricultural fugitive dust and odor are significant sources of localized air pollution in the semi-arid southern Great Plains. Daily episodes of ground-level fugitive dust emissions from the cattle feedlots associated with increased cattle activity in the early evenings are routinely observed, while consistently high ammonia is observed throughout the day. Here we present measurements of aerosol size distributions and concentrations of gas and particulate phase ammonia species collected at a feedlot in Texas during summers of 2006, 2007 and 2008. A GRIMM sequential mobility particle sizer and GRIMM 1.108 aerosol spectrometer were used to determine aerosol size distributions in the range of 10 nm to 20 µm aerodynamic diameter at the downwind and upwind edges of the facility. Using aqueous scrubbers, simultaneous measurements of both gas phase and total ammonia species present in the gas and particle phases were also collected. In addition to the continuous measurements at the edges of the facility, coincident aerosol and ammonia measurements were obtain at an additional site further downwind (~3.5 km). Taken together our measurements will be used to quantify aerosol and ammonia dispersion and transport. Relationships between the fate and transport of the aerosols and ammonia will be discussed.

  7. Solubility of ammonia in rainwater

    OpenAIRE

    G. P. Ayers; Gras, J. L.; Adriaansen, A.; Gillett, R. W.

    2011-01-01

    Partitioning of ammonia between the gaseous and rainwater phases has been investigated at theAustralian Baseline Air Pollution Station during in-situ experiments in which rainwater andammonia gas were sampled concurrently. The relationship between ammonia concentrations inthe gaseous and aqueous phases did not follow either traditional solubility theory based onHenry’s Law, or a recent modified theory that includes secondary equilibria between dissolvedammonia and carbon dioxide.DOI: 10.1111/...

  8. Removal of Ammonia from Air, using Three Iranian Natural Zeolites

    Directory of Open Access Journals (Sweden)

    H Asilian

    2004-06-01

    Full Text Available Ammonia in air can be hazardous to human and animal life and should be removed from the environment. Recently the removal of environmental pollutants such as ammonia by means of natural and modified zeolites has attracted a lot of attention and interests. In this study the capability of three Iranian natural zeolites (Clinoptilolite in point of view of removal of ammonia from air was investigated. Through this research, different zeolites from various regions of Iran including Semnan, Meyaneh, and Firoozkooh resources were considered to be studied. These samples of zeolites were ground and granulized into 425 µm to 4 mm and were utilized in dynamic sorption experiments. Curves of sorption were plotted and breakthrough and saturated points of zeolite samples were obtained. The adsorption capacities at different ammonia concentrations, temperatures, and flow – rates were also calculated. Results obtained showed that, the natural Iranian zeolite (Clinoptilolite was identified to be more efficient adsorbent than the others to remove ammonia from the air. In the same conditions, the obtained breakthrough time for clinoptilolite sample of Meyaneh was longer than the others ( 135min , while, the adsorption capacity of Semnan clinoptilolite was higher than adsorbents ( 6.30 mg /g (P<0.0001.

  9. Positron emission tomography of hepatic first-pass metabolism of ammonia in pig

    DEFF Research Database (Denmark)

    Keiding, S; Munk, O L; Roelsgaard, K;

    2001-01-01

    scan data were analysed by a model of sinusoidal zonation of ammonia metabolism with periportal urea formation and perivenous formation of glutamine. The hepatic extraction fraction of (13)NH(3) was 0.73+/-0.16 (mean+/-SD, n=7 pigs). Values of clearance of ammonia to urea and to glutamine were obtained......, as were rate constants for washout of these two metabolites. Overall, the modelling showed half of the ammonia uptake to be converted to urea and half to glutamine. The washout rate constant for glutamine was about one-tenth of that for urea. We conclude that hepatic first-pass metabolism of ammonia...

  10. Experimental study of separation of ammonia synthesis vent gas by hydrate formation

    Institute of Scientific and Technical Information of China (English)

    Dong Taibin; Wang Leiyan; Liu Aixian; Guo Xuqiang; Ma Qinglan; Li Guowen; Sun Qiang

    2009-01-01

    Termodynamic data on methane hydrate formation in the presence of ammonia are very important for upgrading of ammonia synthesis vent gas using hydrate formation.This paper is focused on the formation conditions of methane hydrate in the presence of ammonia and the effects of gas-liquid ratio and temperature on the separation of vent gas by hydrate formation.Equilibrium data for methane hydrate within an ammonia mole concentration range from 1% to 5 % were obtained.The experimental results indicated that ammonia has an inhibitive effect on hydrate formation.The higher the ammonia concentration, the higher is the pressure reguired for methane hydrate formation would be.The primary experimental results showed that when volume ratio of gas to liquid was 80:1 and temperature was 283.15 K, total mole fraction of (H2+N2) in gas phase could reach 96.9 %.

  11. Measurements of the horizontal gradient of ammonia over a conifer forest in Denmark

    DEFF Research Database (Denmark)

    Hovmand, M.F.; Andersen, H.V.; Løfstrøm, P.;

    1998-01-01

    Horizontal gradients of ammonia have been measured in order to determine the spatial variation of the concentration above a forest as a function of distance from ammonia emitting areas. Measurements were carried out in June 1994 during conditions with winds from north and west. Concentration levels...... of ammonia were generally low, ranging from 0.04 to 0.7 mu g NH3-N m(-3). At northerly winds the concentration levels were about four times higher than at westerly winds, which relates well to more intensive and larger areas of ammonia emission towards north of the forest. The ammonia concentration decreases...... in the forest; in general the percentage decreases were lower during northerly winds (16%) than those obtained during westerly winds (67%). This is probably due to the larger extension of emitting areas towards north than towards the west. Model calculations are comparable with the measured ammonia...

  12. Anaerobic digestion of swine manure: Inhibition by ammonia

    DEFF Research Database (Denmark)

    Hansen, Kaare Hvid; Angelidaki, Irini; Ahring, Birgitte Kiær

    1998-01-01

    A stable anaerobic degradation of swine manure with ammonia concentration of 6 g-N/litre was obtained in continuously stirred tank reactors with a hydraulic retention time of 15 days, at Four different temperatures. Methane yields of 188, 141, 67 and 22 ml-CH4/g-VS were obtained at 37, 45, 55...... and 60 degrees C, respectively. The yields were significantly lower than the potential biogas yield of the swine manure used (300 ml-CH4/g-VS). A free ammonia concentration of 1.1 g-N/litre or more was found to cause inhibition in batch cultures at pH 8.0 (reactor pH), and higher free ammonia...

  13. Water and ammonia abundances in S140 with the Odin satellite

    NARCIS (Netherlands)

    Persson, C. M.; Olberg, M.; Hjalmarson, A.; Spaans, M.; Black, J. H.; Frisk, U.; Liljestrom, T.; Olofsson, A. O. H.; Poelman, D. R.; Sandqvist, Aa.

    2009-01-01

    Aims. We investigate the effect of the physical environment on water and ammonia abundances across the S140 photodissociation region (PDR) with an embedded outflow. Methods. We used the Odin satellite to obtain strip maps of the ground-state rotational transitions of ortho-water and ortho-ammonia, a

  14. Global Seabird Ammonia Emissions

    Science.gov (United States)

    Riddick, S. N.; Blackall, T. D.; Dragosits, U.; Daunt, F. H.; Braban, C. F.; Tang, Y. S.; Trathan, P.; Wanless, S.; Sutton, M. A.

    2010-12-01

    Seabird colonies represent a major source of atmospheric ammonia (NH3) in remote coastal and marine systems in temperate, tropical and polar regions. Previous studies have shown that NH3 emissions from Scottish seabird colonies were substantial - of similar magnitude to the most intensive agricultural point source emissions. The UK data were used to model global seabird NH3 emissions and suggested that penguins are a major source of emissions on and around the Antarctic continent. The largest seabird colonies are in the order of millions of seabirds. Due to the isolation of these colonies from anthropogenic nitrogen sources, they may play a major role in the nitrogen cycle within these ecosystems. A global seabird database was constructed and used in conjunction with a species-specific seabird bioenergetics model to map the locations of NH3 emissions from seabird colonies. The accuracy of the modelled emissions was validated with field data of NH3 emissions measured at key seabird colonies in different climatic regions of the world: temperate (Isle of May, Scotland), tropical (Ascension Island) and polar (Signy Island, South Georgia). The field data indicated good agreement between modelled and measured NH3 emissions. The measured NH3 emissions also showed the variability of emission with climate. Climate dependence of seabird NH3 emissions may have further implications under a changing global climate. Seabird colonies represent NH3 emission ‘hotspots’, often far from anthropogenic sources, and are likely to be the major source of nitrogen input to these remote coastal ecosystems. The direct manuring by seabirds at colony locations may strongly influence species richness and biodiversity. The subsequent volatilisation and deposition of NH3 increases the spatial extent of seabird influence on nitrogen cycling in their local ecosystem. As many seabird populations are fluctuating due to changing food supply, climate change or anthropogenic pressures, these factors

  15. Development of Ammonia Gas Sensor Using Optimized Organometallic Reagent

    Directory of Open Access Journals (Sweden)

    J. Aubrecht

    2016-01-01

    Full Text Available Reliable, continuous, and spatially distributed monitoring of dangerous or irritating chemical substances belongs to standard functions of contemporary industrial and public security systems. Fiber-optic-based detection provides feasible platform to fulfill such aims. This paper deals with characterization of ammonia sensing elements based on multimode polysiloxane-clad silica-core optical fibers sensitized with 5-(4′-dioctylamino phenylimino quinoline-8-1 cobalt bromide complex reagent immobilized into the cross-linked polymer matrix from a proper mixture of organic solvents and a radical scavenger contributing to the desired long-term stability of optical properties. The applied sensing mechanism combines optical detection principle with chemical reaction of the reagent and ammonia resulting in changes in the visible near-infrared optical absorption spectrum of the cladding layer, influencing via evanescent optical field interactions the spectral distribution of the guided light intensity. Reaction kinetics of short fiber sections exposed to ammonia/nitrogen mixture of various ammonia concentrations is tested and evaluated. The obtained sensitivity, limit of detection, and forward response time of the prepared sensors amount to 1.52⁎10-5 ppm−1, 31 ppm, and 25 s, respectively. The obtained results are promising for fabrication of distributed fiber-optic sensors applicable to detection and location of ammonia gas leaks in industrial as well as general public premises.

  16. Spatial Variability in Nitrification Rates and Ammonia-Oxidizing Microbial Communities in the Agriculturally Impacted Elkhorn Slough Estuary, California ▿ †

    OpenAIRE

    Scott D Wankel; Mosier, Annika C.; Hansel, Colleen M.; Paytan, Adina; Francis, Christopher A.

    2010-01-01

    Ammonia oxidation—the microbial oxidation of ammonia to nitrite and the first step in nitrification—plays a central role in nitrogen cycling in coastal and estuarine systems. Nevertheless, questions remain regarding the connection between this biogeochemical process and the diversity and abundance of the mediating microbial community. In this study, we measured nutrient fluxes and rates of sediment nitrification in conjunction with the diversity and abundance of ammonia-oxidizing archaea (AOA...

  17. Energy efficient ammonia heat pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Claus; Pijnenburg, B.; Schumann Grindorf, H. [Danish Technological Institute, Aarhus (Denmark); Christensen, Rolf [Alfa Laval, Lund (Sweden); Rasmussen, Bjarne D. [Grundfos, Bjerringbro (Denmark); Gram, S.; Fredborg Jakobsen, D. [Svedan Industri Koeleanlaeg, Greve (Denmark)

    2013-09-15

    The report describes the development of a highly effective ammonia heat pump. Heat pumps play an increasingly important role in the search for more effective use of energy in our society. Highly efficient heat pumps can contribute to reduced energy consumption and improved economy of the systems which they are a part of. An ammonia heat pump with high pressure reciprocating compressor and a novel split condenser was developed to prove potential for efficiency optimization. The split of the condenser in two parts can be utilized to obtain smaller temperature approaches and, thereby, improved heat pump efficiency at an equal heat exchanger area, when compared to the traditional solution with separate condenser and de-superheater. The split condenser design can also be exploited for heating a significant share of the total heating capacity to a temperature far above the condensing temperature. Furthermore, the prototype heat pump was equipped with a plate type evaporator combined with a U-turn separator with a minimum liquid height and a liquid pump with the purpose of creating optimum liquid circulation ratio for the highest possible heat transfer coefficients at the lowest possible pressure drop. The test results successfully confirmed the highest possible efficiency; a COP of 4.3 was obtained when heating water from 40 deg. C to 80 deg. C while operating with evaporating/condensing temperatures of +20 deg C/+73 deg C. (Author)

  18. Ammonia Volatilization Losses from Urea Applied to Wheat on a Paddy Soil in Taihu Region, China

    Institute of Scientific and Technical Information of China (English)

    FAN Xiao-Hui; SONG Yong-Sheng; LIN De-Xi; YANG Lin-Zhang; ZHOU Jian-Min

    2005-01-01

    Ammonia volatilization losses from urea applied as a basal fertilizer and a top dressing at tillering stage in a wheat field of Taihu Region, China, were measured with a micrometeorological technique. Urea as fertilizer was surface broadcast at 81 (low N) and 135 (high N) kg N ha-1 as basal at the 3-leaf stage of the wheat seedling on December 2002, and 54(low N) and 90 (high N) kg N ha-1 as top dressing on February 2003. Ammonia volatilization losses occurred mainly in the first week after applying N fertilizer and mainly during the period after basal fertilizer application, which accounted for more than 80% of the total ammonia volatilization over the entire wheat growth period. Regression analysis showed that ammonia volatilization was affected mainly by pH and NH4+-N concentration of the surface soil and air temperature.Ammonia volatilization flux was significantly correlated with pH and NH4+-N concentration of the surface soil and with daily air average temperature and highest temperature. Thus, application of urea N fertilizer to wheat should consider the characteristics of ammonia volatilization in different periods of N application so as to reduce ammonia losses.

  19. Flux balance analysis in the production of clavulanic acid by Streptomyces clavuligerus.

    Science.gov (United States)

    Sánchez, Claudia; Quintero, Juan Carlos; Ochoa, Silvia

    2015-01-01

    In this work, in silico flux balance analysis is used for predicting the metabolic behavior of Streptomyces clavuligerus during clavulanic acid production. To choose the best objective function for use in the analysis, three different optimization problems are evaluated inside the flux balance analysis formulation: (i) maximization of the specific growth rate, (ii) maximization of the ATP yield, and (iii) maximization of clavulanic acid production. Maximization of ATP yield showed the best predictions for the cellular behavior. Therefore, flux balance analysis using ATP as objective function was used for analyzing different scenarios of nutrient limitations toward establishing the effect of limiting the carbon, nitrogen, phosphorous, and oxygen sources on the growth and clavulanic acid production rates. Obtained results showed that ammonia and phosphate limitations are the ones most strongly affecting clavulanic acid biosynthesis. Furthermore, it was possible to identify the ornithine flux from the urea cycle and the α-ketoglutarate flux from the TCA cycle as the most determinant internal fluxes for promoting clavulanic acid production.

  20. DETERMINATION OF AMMONIA IN EAR-LOBE CAPILLARY BLOOD IS AN ALTERNATIVE TO ARTERIAL BLOOD AMMONIA

    NARCIS (Netherlands)

    HUIZENGA, [No Value; GIPS, CH; CONN, HO; JANSEN, PLM

    1995-01-01

    Blood ammonia determination is a laboratory test to diagnose hepatic encephalopathy. Arterial blood is superior to peripheral venous blood ammonia because of ammonia metabolism in muscle. We have compared capillary with arterial whole blood ammonia as capillary sampling is an attractive alternative.

  1. Niche specialization of terrestrial archaeal ammonia oxidizers

    OpenAIRE

    Gubry-Rangin, Cécile; Hai, Brigitte; Quince, Christopher; Engel, Marion; Thomson, Bruce C.; James, Phillip; Schloter, Michael; Robert I. Griffiths; Prosser, James I.; Nicol, Graeme W.

    2011-01-01

    Soil pH is a major determinant of microbial ecosystem processes and potentially a major driver of evolution, adaptation, and diversity of ammonia oxidizers, which control soil nitrification. Archaea are major components of soil microbial communities and contribute significantly to ammonia oxidation in some soils. To determine whether pH drives evolutionary adaptation and community structure of soil archaeal ammonia oxidizers, sequences of amoA, a key functional gene of ammonia oxidation, were...

  2. Direct analysis of human breath ammonia using corona discharge ion mobility spectrometry.

    Science.gov (United States)

    Jazan, Elham; Mirzaei, Hadi

    2014-01-01

    In this study, ammonia in human breath was directly determined using corona discharge ionization ion mobility spectrometry (CD-IMS) technique with several important advantages including high sensitivity, low cost, high speed, and ease of maintenance. The temperature effect on the ammonia signal was evaluated too. The results indicated that the best temperature for the investigation of breath ammonia was 150°C. The analytical results showed that the linear dynamic range was between 12 and 810ppb and the detection limit was 6.6ppb. The relative standard deviation (RSD) was obtained to be 5, 3, and 3 for 290, 348, and 522ppb, respectively. The amounts of ammonia in breath of eight healthy volunteers were measured. The values were between 236 and 1218ppb. Also, the inequality in breath ammonia levels was scrutinized over a 6h working day for three healthy volunteers. The results showed a drop in breath ammonia from the morning amount to the mid-day measurement and then, a progressive increase while the day continued. In addition, the amounts of ammonia were determined to be 1494-1553ppb in exhaled breath of two renal failure patients. The results obtained in this work revealed that the method was conveniently established without any considerable sample pretreatment for direct analysis of ammonia in human breath. PMID:24120979

  3. Forced convection of ammonia. 2. part.: gaseous ammonia - very high wall temperatures (1000 to 3000 K)

    International Nuclear Information System (INIS)

    Heat transfer coefficients and pressure drop of gaseous ammonia in forced convection are experimentally determined. The fluid flows (mass flow rate 0.6 to 2.4 g/s) in a long tungsten tube (di = 2.8 mm, de = 5.1 mm, L = 700 mm) electrically heated. The temperature of the wall reaches 3000 deg. K and the fluid 2500 deg. K; maximum heat flux 530 w/cm2. Ammonia is completely dissociated and the power necessary for dissociation reaches 30 per cent of the total power exchanged. Inlet pressure varies between 6 and 16 bars and the maximum pressure drop in the tube reaches 15 bars. Two regimes of dissociation have been shown: catalytic and homogeneous and the variation of dissociation along the length of the tube is studied. The measured heat transfer coefficients may be about 10 times these calculated by the means of classical formulae. A correlation of experimental results using enthalpy as a driving force for heat transmission is presented. Pressure drops may be calculated by the means of a classical friction factor. (authors)

  4. 46 CFR 154.1760 - Liquid ammonia.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Liquid ammonia. 154.1760 Section 154.1760 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR....1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo...

  5. 27 CFR 21.96 - Ammonia, aqueous.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent...

  6. Ammonia oxidation rates and nitrification in the Arabian Sea

    Science.gov (United States)

    Newell, Silvia E.; Babbin, Andrew R.; Jayakumar, Amal; Ward, Bess B.

    2011-12-01

    Nitrification rates, as well as the relationships between rates and ammonia oxidizer abundance (both archaeal and bacterial), were investigated in the Arabian Sea. Ammonia oxidation rates were measured directly using 15N-NH4+stable isotope additions in gas-impermeable, trace metal clean trilaminate bags (500 mL) at in situ temperature. Tracer incubations were performed at three stations at depths above, below, and within the oxycline of the open-ocean oxygen minimum zone (OMZ). Ammonia oxidation rates were similar to previous open-ocean measurements, ranging from undetectable to 21.6 ± 0.1 nmol L-1 d-1. The highest rates at each station occurred at the primary nitrite maximum (above the OMZ), and rates were very low at depths greater than 900 m. The abundances of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were estimated using theamoA gene by quantitative polymerase chain reaction (qPCR). Both AOA and AOB amoA were detected above, within, and below the OMZ, although the AOA were always more abundant than the AOB, by a factor of 35-216. Nitrification rates were not directly correlated to AOA or AOB amoA abundance. These rates offer new insight into the role of nitrification in the mesopelagic zone. The abundance of AOA amoA genes at 1000 m suggests that ˜50% of the microbial biomass could be autotrophic. Additionally, the integrated nitrification rate at depth implies that nitrification could consume most of the ammonium produced by the flux of organic carbon in the mesopelagic zone.

  7. Parameter Optimization on Experimental Study to Reduce Ammonia Escape in CO2 Absorption by Ammonia Scrubbing

    Institute of Scientific and Technical Information of China (English)

    Hao Leng; Jianmin Gao; Mingyue He; Min Xie; Qian Du; Rui Sun; Shaohua Wu

    2016-01-01

    In order to research ammonia escape in CO2 absorption by ammonia scrubbing, ammonia escape was studied in CO2 absorption process using the bubbling reactor in different conditions as gas flow rate, CO2 ratio, absorbent temperature and ammonia concentration and quantity of escaped ammonia was measured by chemical titration. The results indicated that, the amount of ammonia escape can be around 20% of original amount in 90 min and the escaped amount will increase with the rise of gas flow rate, absorbent temperature, concentration of ammonia while decrease as CO2 ratio goes up. Through the analysis of the law of ammonia escape, at the same time, combined with ammonia escape and the influence of the relationship between the CO2 absorption efficiency, reducing ammonia escape working condition parameter optimization is given.

  8. Inhibiting Wet Oxidation of Ammonia

    Science.gov (United States)

    Onisko, D. B. L.

    1985-01-01

    Simple modification of wet-oxidation process for treating organicwaste reduces loss of fixed nitrogen, potentially valuable byproduct of process. Addition of sufficient sulfuric acid to maintain reaction pH below 3 greatly reduces oxidation of ammonia to free nitrogen. No equipment modification required.

  9. Forthcoming Oversupply for Synthetic Ammonia

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhantong

    2007-01-01

    @@ Stable output increase The total capacity of synthetic ammonia in China is 52.0 million t/a today.There are around 540 producers mainly located in Shandong, Shanxi, Hebei,Henan, Jiangsu and Sichuan provinces.The cumulative capacity in Shandong province ranks the highest, accounting for 14.6% of the national total.

  10. Hydrogen production using ammonia borane

    Science.gov (United States)

    Hamilton, Charles W; Baker, R. Thomas; Semelsberger, Troy A; Shrestha, Roshan P

    2013-12-24

    Hydrogen ("H.sub.2") is produced when ammonia borane reacts with a catalyst complex of the formula L.sub.nM-X wherein M is a base metal such as iron, X is an anionic nitrogen- or phosphorus-based ligand or hydride, and L is a neutral ancillary ligand that is a neutral monodentate or polydentate ligand.

  11. Ammonia in power plant emission

    Science.gov (United States)

    Hammerich, Mads; Henningsen, J. O.; Olafsson, Ari

    1990-08-01

    Ammonia monitoring is needed in most schemes for denitrification of power plant emission. In the PALAMON system we use a 500 MHz tunable, single mode, single line, CO2 laser as light source for a low pressure, high temperature, photoacoustic cell. With this cell we can resolve the sR(5,O) line of the ammonia spectrum, and suppress the interfering C02(9R30) absorption line down to a lppm NH3 detection limit. The validity of the measured ammonia concentrations is strongly dependent on details of the sampling system and on the reliability of the calibration routines. In particular calibration with certified mixtures of NH3:N2 has proved insufficient due to the multiple and long time constants caused by adsorption of ammonia to different materials in the system. Presence of water vapor in the gas greatly reduces these time constants. Therefore a number of methods for simple production of moist calibration gases from macroscopic amounts of NH3 are applied. The calibrations are translated to response from an easily managable absorber in order to allow automated recalibration of the photoacoustic response. Data from a field test of the system, and calibration data will be presented.

  12. Transcriptional Response of the Archaeal Ammonia Oxidizer Nitrosopumilus maritimus to Low and Environmentally Relevant Ammonia Concentrations

    OpenAIRE

    Nakagawa, Tatsunori; Stahl, David A.

    2013-01-01

    The ability of chemoautotrophic ammonia-oxidizing archaea to compete for ammonia among marine microorganisms at low ambient concentrations has been in part attributed to their extremely high affinity for ammonia, but as yet there is no mechanistic understanding of supporting metabolism. We examined transcription of selected genes for anabolic functions (CO2 fixation, ammonia transport, and cell wall synthesis) and a central catabolic function (ammonia oxidation) in the thaumarchaeon Nitrosopu...

  13. Flux Creep and Flux Jumping

    CERN Document Server

    Mints, R G

    1995-01-01

    We consider the flux jump instability of the Bean's critical state arising in the flux creep regime in type-II superconductors. We find the flux jump field, $B_j$, that determines the superconducting state stability criterion. We calculate the dependence of $B_j$ on the external magnetic field ramp rate, magnetization experiments the slope of the current-voltage curve in the flux creep regime determines the stability of the Bean's critical state, {\\it i.e.}, the value of $B_j$. We show that a flux jump can be preceded by the magneto-thermal oscillations and find the frequency of these oscillations as a function of $\\dot B_e$.

  14. Modulation of sheep ruminal urea transport by ammonia and pH.

    Science.gov (United States)

    Lu, Zhongyan; Stumpff, Friederike; Deiner, Carolin; Rosendahl, Julia; Braun, Hannah; Abdoun, Khalid; Aschenbach, Jörg R; Martens, Holger

    2014-09-01

    Ruminal fermentation products such as short-chain fatty acids (SCFA) and CO2 acutely stimulate urea transport across the ruminal epithelium in vivo, whereas ammonia has inhibitory effects. Uptake and signaling pathways remain obscure. The ruminal expression of SLC14a1 (UT-B) was studied using polymerase chain reaction (PCR). The functional short-term effects of ammonia on cytosolic pH (pHi) and ruminal urea transport across native epithelia were investigated using pH-sensitive microelectrodes and via flux measurements in Ussing chambers. Two variants (UT-B1 and UT-B2) could be fully sequenced from ovine ruminal cDNA. Functionally, transport was passive and modulated by luminal pH in the presence of SCFA and CO2, rising in response to luminal acidification to a peak value at pH 5.8 and dropping with further acidification, resulting in a bell-shaped curve. Presence of ammonia reduced the amplitude, but not the shape of the relationship between urea flux and pH, so that urea flux remained maximal at pH 5.8. Effects of ammonia were concentration dependent, with saturation at 5 mmol/l. Clamping the transepithelial potential altered the inhibitory potential of ammonia on urea flux. Ammonia depolarized the apical membrane and acidified pHi, suggesting that, at physiological pH (< 7), uptake of NH4 (+) into the cytosol may be a key signaling event regulating ruminal urea transport. We conclude that transport of urea across the ruminal epithelium involves proteins subject to rapid modulation by manipulations that alter pHi and the cytosolic concentration of NH4 (+). Implications for epithelial and ruminal homeostasis are discussed.

  15. Path integrated optical remote sensing technique to estimate ammonia and methane gas emissions from CAFOs

    Science.gov (United States)

    The U.S. EPA recently demonstrated the open-path optical remote sensing technology to identify hot spots and estimate mass flux of fugitive gases from closed landfill. The objective of this research is to validate this technology for estimating ammonia and methane emission from concentrated animal f...

  16. Flow boiling heat transfer of ammonia/water mixture in a plate heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Taboas, Francisco [Universidad de Cordoba, Campus de Rabanales, Edificio Leonardo da Vinci, 14014 Cordoba (Spain); Valles, Manel; Bourouis, Mahmoud; Coronas, Alberto [CREVER - Universitat Rovira i Virgili, Av. Paisos Catalans No. 26, 43007 Tarragona (Spain)

    2010-06-15

    The objective of this work is to contribute to the development of plate heat exchangers as desorbers for ammonia/water absorption refrigeration machines driven by waste heat or solar energy. In this study, saturated flow boiling heat transfer and the associated frictional pressure drop of ammonia/water mixture flowing in a vertical plate heat exchanger is experimentally investigated. Experimental data is presented to show the effects of heat flux between 20 and 50 kW m{sup -2}, mass flux between 70 and 140 kg m{sup -2} s{sup -1}, mean vapour quality from 0.0 to 0.22 and pressure between 7 and 15 bar, for ammonia concentration between 0.42 and 0.62. The results show that for the selected operating conditions, the boiling heat transfer coefficient is highly dependent on the mass flux, whereas the influence of heat flux and pressure are negligible mainly at higher vapour qualities. The pressure drop increases with increasing mass flux and quality. However, the pressure drop is independent of the imposed heat flux. (author)

  17. Ammonia as efficient fuel for SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Fuerte, A.; Valenzuela, R.X.; Escudero, M.J. [CIEMAT, Departamento de Energia, Av. Complutense 22, 28040 Madrid (Spain); Daza, L. [CIEMAT, Departamento de Energia, Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2009-07-01

    Ammonia is a possible candidate as the fuel for SOFCs. In this work, the influence on the performance of a tubular SOFC running on ammonia is studied. Analysis of open circuit voltages (OCVs) on the cell indicated the oxidation of ammonia within a SOFC is a two-stage process: decomposition of the inlet ammonia into nitrogen and hydrogen, followed by oxidation of hydrogen to water. For comparison, cell was also tested with hydrogen as the fuel and air as oxidant at different temperatures showing a similar behaviour. The performance of the cell tested under various conditions shows the high potential of ammonia as fuel for SOFCs. (author)

  18. Methane Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Methane (CH4) flux is the net rate of methane exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS LandCarbon project...

  19. Coumarin meets fluorescein: a Förster resonance energy transfer enhanced optical ammonia gas sensor.

    Science.gov (United States)

    Widmer, Susanne; Dorrestijn, Marko; Camerlo, Agathe; Urek, Špela Korent; Lobnik, Aleksandra; Housecroft, Catherine E; Constable, Edwin C; Scherer, Lukas J

    2014-09-01

    This study focuses on the development of an optical ammonia gas sensor, the sensing mechanism of which is based on Förster resonance energy transfer (FRET) between coumarin and fluorescein. The dyes were immobilized into an organically modified silicate matrix during polymerizing methyltriethoxysilane with trifluoropropyltrimethoxysilane on a poly(methyl methacrylate) substrate. The resulting dye-doped xerogel films were exposed to different gaseous ammonia concentrations. A logarithmic decrease of the coumarin fluorescence emission band at 442 nm was observed with increasing gaseous ammonia concentrations, which was due to enhanced FRET between coumarin and fluorescein. The coumarin/fluorescein composition was optimized in order to obtain the best ammonia sensitivity. First experiments in a flow cell gas sensor setup demonstrated a sensitive and reversible response to gaseous ammonia. PMID:25004956

  20. [Spectroscopic study on the high voltage fast pulsed discharge of nitrogen, ammonia or their mixture].

    Science.gov (United States)

    Liu, Z P; Wang, P N; Yang, W D; Zheng, J B; Li, F M

    2001-10-01

    The emission spectra from the pulsed discharge plasma of nitrogen, ammonia or their mixture were measured. In the discharge of pure nitrogen gas, as the pressure increased, the discharge volume decreased and more dissociation of nitrogen molecules occurred due to the higher energy density. In the discharge of ammonia, N,N+ and NH+ were observed, but no NH2 and NH3 were detected, indicating that ammonia, which has the lower dissociation and ionization energies as compared to nitrogen, was highly dissociated. The discharge of the mixture of N2 and NH3 was also studied. The dependence of the dissociation of nitrogen on the ratio of nitrogen to ammonia was investigated by emission spectra. The optimal ratio for nitrogen dissociation was obtained. The advantage of using the mixture of nitrogen and ammonia in the synthesis of nitrides was discussed. PMID:12945317

  1. Surface-atmosphere exchange of ammonia over peatland using QCL-based eddy-covariance measurements and inferential modeling

    DEFF Research Database (Denmark)

    Zöll, Undine; Brümmer, Christian; Schrader, Frederik;

    2016-01-01

    Recent advances in laser spectrometry offer new opportunities to investigate ecosystem-atmosphere exchange of environmentally relevant trace gases. In this study, we demonstrate the applicability of a quantum cascade laser (QCL) absorption spectrometer to continuously measure ammonia concentratio...... as important additional instruments within long-term monitoring research infrastructures such as ICOS or NEON at sites with strong nearby ammonia sources leading to relatively high mean background concentrations and fluxes....

  2. Ammonia for hydrogen storage: challenges and opportunities

    DEFF Research Database (Denmark)

    Klerke, Asbjørn; Christensen, Claus H.; Nørskov, Jens Kehlet;

    2008-01-01

    The possibility of using ammonia as a hydrogen carrier is discussed. Compared to other hydrogen storage materials, ammonia has the advantages of a high hydrogen density, a well-developed technology for synthesis and distribution, and easy catalytic decomposition. Compared to hydrocarbons...... and alcohols, it has the advantage that there is no CO2 emission at the end user. The drawbacks are mainly the toxicity of liquid ammonia and the problems related to trace amounts of ammonia in the hydrogen after decomposition. Storage of ammonia in metal ammine salts is discussed, and it is shown...... that this maintains the high volumetric hydrogen density while alleviating the problems of handling the ammonia. Some of the remaining challenges for research in ammonia as a hydrogen carrier are outlined....

  3. Control of ammonia air pollution through the management of thermal processes in cowsheds.

    Science.gov (United States)

    Bleizgys, Rolandas; Bagdoniene, Indre

    2016-10-15

    Experimental researches performed in manufacturing cowsheds have demonstrated a variation of ammonia concentration and the factors influencing this most during different periods of the year. The process of ammonia evaporation from manure is influenced by many varying and interrelated factors with temperature and the intensity of air ventilation being the most critical ones. The influence of these factors on the process of ammonia evaporation was established by laboratory researches. An increase in temperature results in an exponential increase in ammonia emission, whereas the dependence of the emission on the air velocity is best expressed by a second degree polynomial. The results obtained may be used as a forecast of the ammonia emissions from cowsheds during different periods of the year. Intensive ventilation is required for the removal of excess moisture from the housing, and this limits the possibilities to reduce ammonia emissions by controlling the intensity of ventilation. A reduction in the amount of ventilation is only recommended if the air quality indices meet the requirements applied to the housing. Better opportunities to reduce ammonia emissions are provided through management of the thermal processes in a cowshed. If the average annual air temperature (11.3°C) is reduced by one degree in a cubicle housing cowshed, the ammonia emissions will decrease by 10%. PMID:27350091

  4. Accuracy of cuticular resistance parameterizations in ammonia dry deposition models

    Science.gov (United States)

    Schrader, Frederik; Brümmer, Christian; Richter, Undine; Fléchard, Chris; Wichink Kruit, Roy; Erisman, Jan Willem

    2016-04-01

    Accurate representation of total reactive nitrogen (Nr) exchange between ecosystems and the atmosphere is a crucial part of modern air quality models. However, bi-directional exchange of ammonia (NH3), the dominant Nr species in agricultural landscapes, still poses a major source of uncertainty in these models, where especially the treatment of non-stomatal pathways (e.g. exchange with wet leaf surfaces or the ground layer) can be challenging. While complex dynamic leaf surface chemistry models have been shown to successfully reproduce measured ammonia fluxes on the field scale, computational restraints and the lack of necessary input data have so far limited their application in larger scale simulations. A variety of different approaches to modelling dry deposition to leaf surfaces with simplified steady-state parameterizations have therefore arisen in the recent literature. We present a performance assessment of selected cuticular resistance parameterizations by comparing them with ammonia deposition measurements by means of eddy covariance (EC) and the aerodynamic gradient method (AGM) at a number of semi-natural and grassland sites in Europe. First results indicate that using a state-of-the-art uni-directional approach tends to overestimate and using a bi-directional cuticular compensation point approach tends to underestimate cuticular resistance in some cases, consequently leading to systematic errors in the resulting flux estimates. Using the uni-directional model, situations where low ratios of total atmospheric acids to NH3 concentration occur lead to fairly high minimum cuticular resistances, limiting predicted downward fluxes in conditions usually favouring deposition. On the other hand, the bi-directional model used here features a seasonal cycle of external leaf surface emission potentials that can lead to comparably low effective resistance estimates under warm and wet conditions, when in practice an expected increase in the compensation point due to

  5. Data Acquisition and Flux Calculations

    DEFF Research Database (Denmark)

    Rebmann, C.; Kolle, O; Heinesch, B;

    2012-01-01

    In this chapter, the basic theory and the procedures used to obtain turbulent fluxes of energy, mass, and momentum with the eddy covariance technique will be detailed. This includes a description of data acquisition, pretreatment of high-frequency data and flux calculation.......In this chapter, the basic theory and the procedures used to obtain turbulent fluxes of energy, mass, and momentum with the eddy covariance technique will be detailed. This includes a description of data acquisition, pretreatment of high-frequency data and flux calculation....

  6. Simultaneous heat and mass transfer of a packed distillation column for ammonia-water absorption refrigeration systems

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Sieres, Jaime; Vazquez, Manuel [Area de Maquinas y Motores Termicos, Escuela Tecnica Superior de Ingenieros Industriales de Vigo, Universidad de Vigo, Campus Lagoas-Marcosende, N circle 9, 36200, Vigo (Spain)

    2002-10-01

    This paper presents a study on the NH{sub 3}-H{sub 2}O distillation process using a packed column with liquid reflux from the condenser in an absorption refrigeration system. A differential mathematical model has been developed on the basis of mass and energy balances and the heat and mass transfer equations. A net molar flux between the liquid and vapour phases has been considered in the mass transfer equation, which obviates the need to assume equimolar counter-diffusion. The model equations have been solved using the finite-difference method. Results obtained for a specific application are shown, including parameter distributions along the column length. The influence of rectifying and stripping lengths, mass and heat transfer coefficients and volumetric heat rejection from the column, on the distillate ammonia concentration has been analysed. (authors)

  7. Ammonia abatement by slurry acidification

    DEFF Research Database (Denmark)

    Petersen, Søren O.; Hutchings, Nicholas John; Hafner, Sasha;

    2016-01-01

    Livestock production systems can be major sources of trace gases including ammonia (NH3), the greenhouse gases methane (CH4) and nitrous oxide (N2O), and odorous compounds such as hydrogen sulphide (H2S). Short-term campaigns have indicated that acidification of livestock slurry during in...... generally high. It was concluded that the contribution from floors to NH3 emissions was effect on N2O emissions was observed. The effect...

  8. Ammonia Production, Excretion, Toxicity, and Defense in Fish: A Review

    OpenAIRE

    Yuen K Ip; Chew, Shit F.

    2010-01-01

    Many fishes are ammonotelic but some species can detoxify ammonia to glutamine or urea. Certain fish species can accumulate high levels of ammonia in the brain or defense against ammonia toxicity by enhancing the effectiveness of ammonia excretion through active NH 4 + transport, manipulation of ambient pH, or reduction in ammonia permeability through the branchial and cutaneous epithelia. Recent reports on ammonia toxicity in mammalian brain reveal the importance of permeation of ammonia thr...

  9. Fiber-Optic Ammonia Sensors

    Science.gov (United States)

    Carter, Michael T.

    2003-01-01

    Reversible, colorimetric fiber-optic sensors are undergoing development for use in measuring concentrations of ammonia in air at levels relevant to human health [0 to 50 parts per million (ppm)]. A sensor of this type includes an optical fiber that has been modified by replacing a portion of its cladding with a polymer coat that contains a dye that reacts reversibly with ammonia and changes color when it does so. The change in color is measured as a change in the amount of light transmitted from one end of the fiber to the other. Responses are reversible and proportional to the concentration of ammonia over the range from 9 to 175 ppm and in some cases the range of reversibility extends up to 270 ppm. The characteristic time for the response of a sensor to rise from 10 to 90 percent of full scale is about 25 seconds. These sensors are fully operational in pure carbon dioxide and are not adversely affected by humidity. This work was done by Michael T. Carter

  10. Planar waveguide sensor of ammonia

    Science.gov (United States)

    Rogoziński, Roman; Tyszkiewicz, Cuma; Karasiński, Paweł; Izydorczyk, Weronika

    2015-12-01

    The paper presents the concept of forming ammonia sensor based on a planar waveguide structure. It is an amplitude sensor produced on the basis of the multimode waveguide. The technological base for this kind of structure is the ion exchange method and the sol-gel method. The planar multimode waveguide of channel type is produced in glass substrate (soda-lime glass of Menzel-Glaser company) by the selective Ag+↔Na+ ion exchange. On the surface of the glass substrate a porous (~40%) silica layer is produced by the sol-gel method. This layer is sensitized to the presence of ammonia in the surrounding atmosphere by impregnation with Bromocresol Purple (BCP) dye. Therefore it constitutes a sensor layer. Spectrophotometric tests carried out showed about 50% reduction of cross-transmission changes of such sensor layer for a wave λ=593 nm caused by the presence of 25% ammonia water vapor in its ambience. The radiation source used in this type of sensor structure is a light emitting diode LED. The gradient channel waveguide is designed for frontal connection (optical glue) with a standard multimode telecommunications waveguide 62.5/125μm.

  11. Kinetics and thermodynamics of Si(111) surface nitridation in ammonia

    Science.gov (United States)

    Mansurov, Vladimir G.; Malin, Timur V.; Galitsyn, Yurij G.; Shklyaev, Alexander A.; Zhuravlev, Konstantin S.

    2016-05-01

    Kinetics and thermodynamics of Si(111) surface nitridation under an ammonia flux at different substrate temperatures are investigated by reflection high-energy electron diffraction. Two different stages of the nitridation process were revealed. The initial stage is the fast (within few seconds) formation of ordered two-dimensional SiN phase, occuring due to the topmost active surface Si atom (Sisurf) interaction with ammonia molecules. It is followed by the late stage consisting in the slow (within few minutes) amorphous Si3N4 phase formation as a result of the interaction of Si atoms in the lattice site (Siinc) with chemisorbed ammonia molecules. It was found that the ordered SiN phase formation rate decreases, as the temperature increases. The kinetic model of the initial stage was developed, in which the ordered SiN phase formation is the two-dimensional phase transition in the lattice gas with SiN cells. The enthalpy of the active surface Si atom generation on the clean Si(111) surface was estimated to be about 1.5 eV. In contrast, the amorphous Si3N4 phase formation is the normal (thermally activated) chemical process with the first-order kinetics, whose activation energy and pre-exponential factor are 2.4 eV and 108 1/s, respectively.

  12. A low-temperature process for the denitration of Hanford single-shell tank, nitrate-based waste utilizing the nitrate to ammonia and ceramic (NAC) or nitrate to ammonia and glass (NAG) process: Phase 2 report

    International Nuclear Information System (INIS)

    Continuing benchtop studies using Hanford single-shell tank (SST) simulants and actual Oak Ridge National Laboratory (ORNL) low-level waste (LLW), employing a new denitration process for converting nitrate to ammonia and ceramic (NAC), have conclusively shown that between 85 and 99% of the nitrate can be readily converted to gaseous ammonia. In this process, aluminum powders can be used to convert alkaline, nitrate-based supernate to ammonia and an aluminum oxide-sodium aluminate-based solid. The process may be able to use contaminated aluminum scrap metal from DOE sites to effect the conversion. The final, nitrate-free ceramic product can be pressed and sintered like other ceramics or silica and/or fluxing agents can be added to form a glassy ceramic or a flowable glass product. Based upon the starting volumes of 6.2 and 3.1 M sodium nitrate solution, volume reductions of 50 to 70% were obtained for the waste form produced. Sintered pellets produced from supernate from Melton Valley Storage Tanks (MVSTs) have been leached in accordance with the 16.1 leach test for the radioelements 85Sr and 137Cs. Despite lengthy counting times, 85Sr could not be detected in the leachates. 137Cs was only slightly above background and corresponded to a leach index of 12.2 to 13.7 after 8 months of leaching. Leach testing of unsintered and sintered reactor product spiked with hazardous metals proved that both sintered and unsintered product passed the Toxicity Characteristic Leaching Procedure (TCLP) test. Design of the equipment and flowsheet for a pilot demonstration-scale system to prove the nitrate destruction portion of the NAC process and product formation is under way

  13. Carbon Dioxide Flux Measurement Systems (CO2Flux) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, M

    2005-01-01

    The Southern Great Plains (SGP) carbon dioxide flux (CO2 flux) measurement systems provide half-hour average fluxes of CO2, H2O (latent heat), and sensible heat. The fluxes are obtained by the eddy covariance technique, which computes the flux as the mean product of the vertical wind component with CO2 and H2O densities, or estimated virtual temperature. A three-dimensional sonic anemometer is used to obtain the orthogonal wind components and the virtual (sonic) temperature. An infrared gas analyzer is used to obtain the CO2 and H2O densities. A separate sub-system also collects half-hour average measures of meteorological and soil variables from separate 4-m towers.

  14. Growth at low ammonium concentrations and starvation response as potential factors involved in niche differentiation among ammonia-oxidizing bacteria

    NARCIS (Netherlands)

    Bollmann, A.; Bär-Gilissen, M.J.; Laanbroek, H.J.

    2002-01-01

    In nature, ammonia-oxidizing bacteria have to compete with heterotrophic bacteria and plants for limiting amounts of ammonium. Previous laboratory experiments conducted with Nitrosomonas europaea suggested that ammonia-oxidizing bacteria are weak competitors for ammonium. To obtain a better insight

  15. REGENERATION OF AMMONIA SOLUTION FOR CO2 CAPTURE IN POSTCOMBUSTION

    Directory of Open Access Journals (Sweden)

    CAROL TORO

    2014-01-01

    Full Text Available This study investigated enthalpy of solutions and solubility for a NH3/CO2 system. Measurements were performed in a thermoregulated Lewis-type cell reactor, temperatures ranging from 278 to 303 K and mass concentrations from 2 wt% to 5 wt%. Enthalpies of solution of CO2 and solubility have been obtained as function of loading, α (moles CO2/mol NH3. Results show that ammonia solutions concentrations of 3 and 5 wt% promote the formation of ammonium bicarbonate. Beside, ammonia concentration of 2 wt% promotes the formation of ammonium carbonate. Therefore, to use ammonia concentrations of 3 and 5 wt% need less energy that a concentration of 2 wt% to reverse the reaction. Regeneration system was simulated using Aspen plus™ software for a pulverised coal fired power plant (CF in a post-combustion process. Model analysis established that NH3 heat duty is lower than MEA and MDEA ones. The energy consumption reaches 2.83 GJ•t-1 CO2. Regarding heat duty and ammonia losses, 3 wt% NH3 is the suitable concentration to capture CO2.

  16. Ammonia Process by Pressure Swing Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Dr Felix Jegede

    2010-12-27

    The overall objective of the project is to design, develop and demonstrate a technically feasible and commercially viable system to produce ammonia along with recovery of the products by adsorption separation methods and significantly decrease the energy requirement in ammonia production. This is achieved through a significantly more efficient ammonia psa recovery system. The new ammonia recovery system receives the reactor effluents and achieves complete ammonia recovery, (which completely eliminates the energy intensive refrigeration and condensation system currently used in ammonia production). It also recovers the unused reactants and recycles them back to the reactor, free of potential reactor contaminants, and without the need for re-compression and re-heat of recycle stream thereby further saving more energy. The result is a significantly lower energy consumption, along with capital cost savings.

  17. Ammonia emission from crop residues : quantification of ammonia volatilization based on crop residue properties

    NARCIS (Netherlands)

    Ruijter, de F.J.; Huijsmans, J.F.M.

    2012-01-01

    This paper gives an overview of available literature data on ammonia volatilization from crop residues. From these data, a relation is derived for the ammonia emission depending on the N-content of crop residue.

  18. Autotrophic ammonia oxidation by soil thaumarchaea

    OpenAIRE

    Zhang, Li-Mei; Offre, Pierre R.; He, Ji-Zheng; Verhamme, Daniel T.; Nicol, Graeme W.; Prosser, James I.

    2010-01-01

    Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, bu...

  19. A process-based model for ammonia emission from urine patches, GAG (Generation of Ammonia from Grazing: description, validation and sensitivity analysis

    Directory of Open Access Journals (Sweden)

    A. Móring

    2015-07-01

    Full Text Available In this paper a new process-based, weather-driven model for ammonia (NH3 emission from a urine patch has been developed and its sensitivity to various factors assessed. This model, the GAG model (Generation of Ammonia from Grazing was developed as a part of a suite of weather-driven NH3 exchange models, as a necessary basis for assessing the effects of climate change on NH3 related atmospheric processes. GAG is capable of simulating the TAN (Total Ammoniacal Nitrogen content, pH and the water content of the soil under a urine patch. To calculate the TAN budget, GAG takes into account urea hydrolysis as a TAN input and NH3 volatilization as a loss. In the water budget, in addition to the water content of urine, precipitation and evaporation are also considered. In the pH module we assumed that the main regulating processes are the dissociation and dissolution equilibria related to the two products of urea hydrolysis: ammonium and bicarbonate. Finally, in the NH3 exchange flux calculation we adapted a canopy compensation point model that accounts for exchange with soil pores and stomata as well as deposition to the leaf surface. We validated our model against measurements, and carried out a sensitivity analysis. The validation showed that the simulated parameters (NH3 exchange flux, soil pH, TAN budget and water budget are well captured by the model (r > 0.5 for every parameter at p 3 emission. In addition, our results suggested that more sophisticated simulation of CO2 emission in the model could potentially improve the modelling of pH. The sensitivity analysis highlighted the vital role of temperature in NH3 exchange; however, presumably due to the TAN limitation, the GAG model currently provides only a modest overall temperature dependence in total NH3 emission compared with the values in the literature. Since all the input parameters can be obtained for study at larger scales, GAG is potentially suitable for larger scale application, such as

  20. A process-based model for ammonia emission from urine patches, GAG (Generation of Ammonia from Grazing): description, validation and sensitivity analysis

    Science.gov (United States)

    Móring, A.; Vieno, M.; Doherty, R. M.; Laubach, J.; Taghizadeh-Toosi, A.; Sutton, M. A.

    2015-07-01

    In this paper a new process-based, weather-driven model for ammonia (NH3) emission from a urine patch has been developed and its sensitivity to various factors assessed. This model, the GAG model (Generation of Ammonia from Grazing) was developed as a part of a suite of weather-driven NH3 exchange models, as a necessary basis for assessing the effects of climate change on NH3 related atmospheric processes. GAG is capable of simulating the TAN (Total Ammoniacal Nitrogen) content, pH and the water content of the soil under a urine patch. To calculate the TAN budget, GAG takes into account urea hydrolysis as a TAN input and NH3 volatilization as a loss. In the water budget, in addition to the water content of urine, precipitation and evaporation are also considered. In the pH module we assumed that the main regulating processes are the dissociation and dissolution equilibria related to the two products of urea hydrolysis: ammonium and bicarbonate. Finally, in the NH3 exchange flux calculation we adapted a canopy compensation point model that accounts for exchange with soil pores and stomata as well as deposition to the leaf surface. We validated our model against measurements, and carried out a sensitivity analysis. The validation showed that the simulated parameters (NH3 exchange flux, soil pH, TAN budget and water budget) are well captured by the model (r > 0.5 for every parameter at p CO2 emission in the model could potentially improve the modelling of pH. The sensitivity analysis highlighted the vital role of temperature in NH3 exchange; however, presumably due to the TAN limitation, the GAG model currently provides only a modest overall temperature dependence in total NH3 emission compared with the values in the literature. Since all the input parameters can be obtained for study at larger scales, GAG is potentially suitable for larger scale application, such as in regional atmospheric and ecosystem models.

  1. Cylinder supplied ammonia scrubber testing in IDMS

    International Nuclear Information System (INIS)

    This report summarizes the results of the off-line testing the Integrated DWPF Melter System (IDMS) ammonia scrubbers using ammonia supplied from cylinders. Three additional tests with ammonia are planned to verify the data collected during off-line testing. Operation of the ammonia scrubber during IDMS SRAT and SME processing will be completed during the next IDMS run. The Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) scrubbers were successful in removing ammonia from the vapor stream to achieve ammonia vapor concentrations far below the 10 ppM vapor exit design basis. In most of the tests, the ammonia concentration in the vapor exit was lower than the detection limit of the analyzers so results are generally reported as <0.05 parts per million (ppM). During SRAT scrubber testing, the ammonia concentration was no higher than 2 ppM and during SME testing the ammonia concentration was no higher than 0.05 m

  2. Tetraammineplatinum(II dichloride ammonia tetrasolvate

    Directory of Open Access Journals (Sweden)

    Tobias Grassl

    2014-07-01

    Full Text Available The title compound, [Pt(NH34]Cl2·4NH3, was crystallized in liquid ammonia from the salt PtCl2. The platinum cation is coordinated by four ammonia molecules, forming a square-planar complex. The chloride anions are surrounded by nine ammonia molecules, either bound within the platinum complex or solvent molecules. The solvent ammonia molecules are packed in such a way that an extended network of N—H...N and N—H...Cl hydrogen bonds is formed. The structure is isotypic with [Pd(NH34]Cl2·4NH3 [Grassl & Korber (2014. Acta Cryst. E70, i32].

  3. Ammonia and urea permeability of mammalian aquaporins

    DEFF Research Database (Denmark)

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which...... and 9 are found together with Rh proteins in cells exposed to portal blood coming from the intestine. In the kidney, AQP3 might participate in the excretion of NH(4) (+) in the collecting duct. The interplay between the ammonia-permeable aquaporins and the other types of ammonia- and urea...

  4. Theoretical study of Moessbauer hyperfine parameters of Fe bound to ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Terra, J.; Guenzburger, D.

    1995-01-01

    The first-principles Discrete Variational method was employed to study the species formed by the interaction of an Fe atom and ammonia. Total energy calculations were performed for several configurations. The hyperfine parameters isomer shift, quadrupole splitting and magnetic hyperfine were calculated for the ground state found, and compared to reported experimental values obtained by Moessbauer spectroscopy in frozen ammonia. (author). 14 refs, 1 tab.

  5. Ammonia Decomposition over Bimetallic Nitrides Supported on γ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    Chun Shan LU; Xiao Nian LI; Yi Feng ZHU; Hua Zhang LIU; Chun Hui ZHOU

    2004-01-01

    A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the ammonia decomposition activity were investigated. TPR-MS, XRD were also carried out to obtain better insight into the structure of the bimetallic nitride. The results of ammonia decomposition activity show that bimetallic nitrides are more active than monometallic nitrides or bimetallic oxides.

  6. Analysis of Cryogenic Ammonia System for Energy Conservation

    OpenAIRE

    B. Raei; F. Shahraki; Khorrami, M.; A. Ghadi

    2010-01-01

    There are several alternatives to enhance the efficiency of energy usage and to decrease energy losses. Pinch technology is the best method of approach to enhance energy efficiency. Heat exchangers network (HEN) of refrigeration unit of ammonia production process was analyzed to use pinch technology to decrease energy usage. The obtained results showed that pinch technology was unsuccessful for the shaft work targeting capabilities. In contrast, it is posed that for optimization of such syste...

  7. Reducing ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2011-01-01

    The NEC directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries with the largest reductions since 1990...... to the high expectations at the outset. Despite this, the paper concludes that Denmark is likely to reduce emission by 50% from 1990 to 2020 and reach the likely 2020 NEC ceiling....

  8. Ammonia synthesis at low temperatures

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2000-01-01

    have been carried out to evaluate its feasibility. The calculations suggest that it might be possible to catalytically produce ammonia from molecular nitrogen at low temperatures and pressures, in particular if energy is fed into the process electrochemically. (C) 2000 American Institute of Physics........ In contrast to the biological process, the industrial process requires high temperatures and pressures to proceed, and an explanation of this important difference is discussed. The possibility of a metal surface catalyzed process running at low temperatures and pressures is addressed, and DFT calculations...

  9. Determinants of [13N]ammonia kinetics in hepatic PET experiments: a minimal recirculatory model

    International Nuclear Information System (INIS)

    The aim of this study was the development of a modelling approach for the analysis of the systemic kinetics of the tracer nitrogen-13 ammonia administered for dynamic liver scanning. The radioactive half-life of this tracer is 9.8 min, which limits the time span in which data are available in a positron emission tomography experimental setting. A circulatory pharmacokinetic model was applied to the metabolism of ammonia in anaesthetised pigs, which incorporated data from serial measurements of [13N]ammonia and [13N]metabolite activity in arterial and portal venous blood together with blood flow rates through the portal vein and through the hepatic artery obtained over 20 min after intravenous injection of [13N]ammonia. Model analysis showed that up to 20 min after injection the time course of [13N]ammonia concentration in arterial blood is primarily determined by distribution kinetics (steady-state volume of distribution 1,856±531 ml kg-1). Simultaneous fitting of arterial ammonia and metabolite blood concentrations allowed for estimation of the hepatic [13N]ammonia clearance (10.25±1.84 ml min-1 kg-1), which accounted for the formation of the circulating metabolites. (orig.)

  10. Critical flux determination by flux-stepping

    DEFF Research Database (Denmark)

    Beier, Søren; Jonsson, Gunnar Eigil

    2010-01-01

    values are more or less useless in itself as critical flux predictors, and constant flux verification experiments have to be conducted to check if the determined critical fluxes call predict sustainable flux regimes. However, it is shown that using the step-by-step predicted critical fluxes as start...

  11. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    Science.gov (United States)

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-03-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many highelevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  12. Mathematical Modeling of Ammonia Electro-Oxidation on Polycrystalline Pt Deposited Electrodes

    Science.gov (United States)

    Diaz Aldana, Luis A.

    The ammonia electrolysis process has been proposed as a feasible way for electrochemical generation of fuel grade hydrogen (H2). Ammonia is identified as one of the most suitable energy carriers due to its high hydrogen density, and its safe and efficient distribution chain. Moreover, the fact that this process can be applied even at low ammonia concentration feedstock opens its application to wastewater treatment along with H 2 co-generation. In the ammonia electrolysis process, ammonia is electro-oxidized in the anode side to produce N2 while H2 is evolved from water reduction in the cathode. A thermodynamic energy requirement of just five percent of the energy used in hydrogen production from water electrolysis is expected from ammonia electrolysis. However, the absence of a complete understanding of the reaction mechanism and kinetics involved in the ammonia electro-oxidation has not yet allowed the full commercialization of this process. For that reason, a kinetic model that can be trusted in the design and scale up of the ammonia electrolyzer needs to be developed. This research focused on the elucidation of the reaction mechanism and kinetic parameters for the ammonia electro-oxidation. The definition of the most relevant elementary reactions steps was obtained through the parallel analysis of experimental data and the development of a mathematical model of the ammonia electro-oxidation in a well defined hydrodynamic system, such as the rotating disk electrode (RDE). Ammonia electro-oxidation to N 2 as final product was concluded to be a slow surface confined process where parallel reactions leading to the deactivation of the catalyst are present. Through the development of this work it was possible to define a reaction mechanism and values for the kinetic parameters for ammonia electro-oxidation that allow an accurate representation of the experimental observations on a RDE system. Additionally, the validity of the reaction mechanism and kinetic parameters

  13. Evaluation of ammonia metabolism in the skeletal muscles of patients with cirrhosis using N-13 ammonia PET

    International Nuclear Information System (INIS)

    liver cirrhosis. Both ascites and encephalopathy were present. The red blood cell count was 365 X 104/ml, the platelet count was 6.2 X l04/ml, the serum albumin concentration was 3.1 g/dl, the cholinesterase activity was 228 IU/l, the total bilirubin concentration was 2.1 mg/dl, the blood ammonia was 120 g/dl, the prothrombin time was 63%, and BTR was 2.09. This study conformed to the ethical guidelines of the Declaration of Helsinki and was approved by the Ethics Committee of Osaka City University Medical School. Informed consent was obtained from both patients. N-13 ammonia was produced with an NKK-Oxford superconducting cyclotron and an NKK synthesis system (AMANO1, NKK Co., Muroran, Japan). PET images were obtained by a PET scanner (HEADTOME IV SET-1400W-10, Shimadzu Co., Kyoto, Japan), which had 4 detector rings providing 7 contiguous slices at 13-mm intervals with an intrinsic resolution of 4.5 mm full width at half maximum (FWHM). Attenuation correction of the reconstructed images was accomplished by acquiring a patient-specific transmission study using a Ge-68 ring source. PET studies were performed before and 2 hours after drip injection of BCAA (Morihepamin, AJIMONOTO Pharmaceutical Co., Ltd., Tokyo, Japan). Serial dynamic PET scans (2 min x lo frames) were started simultaneously with a 185 MBq N-13 ammonia injection. For quantitative evaluation, ROIs were placed over both thighs. The average activity within each ROI was subsequently corrected for radioactive decay, and standardized uptake values (SUV) were calculated by dividing the tissue activity by the injected dose of radioactivity per unit body weight. Results: After intravenous administration of N-13 ammonia, SUV in the skeletal muscles increased gradually in both patients. The difference of SUV from the last frame to the first frame before administration of BCAA was higher in case 2 than in case 1 (0.67 and 0.32, respectively). In case l, there was little difference in the rate of increase in

  14. Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors

    Directory of Open Access Journals (Sweden)

    F. X. Meixner

    2009-10-01

    Full Text Available The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient. The significance of the measured concentration difference is crucial for the significant determination of surface exchange fluxes. Additionally, measurements of surface exchange fluxes of ammonia, nitric acid and ammonium nitrate are often strongly affected by phase changes between gaseous and particulate compounds of the triad, which make measurements of the four individual species (NH3, HNO3, NH4+, NO3– necessary for a correct interpretation of the measured concentration differences. We present here a rigorous analysis of results obtained with a multi-component, wet-chemical instrument, able to simultaneously measure gradients of both gaseous and particulate trace substances. Basis for our analysis are two field experiments, conducted above contrasting ecosystems (grassland, forest. Precision requirements of the instrument as well as errors of concentration differences and micrometeorological exchange parameters have been estimated, which, in turn, allows the establishment of thorough error estimates of the derived fluxes of NH3, HNO3, NH4+, and NO3–. Derived median flux errors for the grassland and forest field experiments were: 39 and 50% (NH3, 31 and 38% (HNO3, 62 and 57% (NH4+, and 47 and 68% (NO3–, respectively. Additionally, we provide the basis for using field data to characterize the instrument performance, as well as subsequent quantification of surface exchange fluxes and underlying mechanistic processes under realistic ambient measurement conditions.

  15. Atmospheric behaviour of ammonia and ammonium.

    NARCIS (Netherlands)

    Asman, W.A.J.

    1987-01-01

    1.4.1 Scope of this thesisA few models for ammonia and ammonium exist. Russell et al. (1983) made a multi-layer Lagrangian transport model describing the transport and formation of ammonium nitrate aerosol for California. They did not take reactions of ammonia and sulphuric acid into account, nor we

  16. Nitrocarburizing in ammonia-hydrocarbon gas mixtures

    DEFF Research Database (Denmark)

    Pedersen, Hanne; Christiansen, Thomas; Somers, Marcel A. J.

    2011-01-01

    The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammonia-propene-hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere and str...

  17. Regeneration of ammonia borane from polyborazylene

    Science.gov (United States)

    Sutton, Andrew; Gordon, John C; Ott, Kevin C; Burrell, Anthony K

    2013-02-05

    Method of producing ammonia borane, comprising providing a reagent comprising a dehydrogenated material in a suitable solvent; and combining the reagent with a reducing agent comprising hydrazine, a hydrazine derivative, or combinations thereof, in a reaction which produces a mixture comprising ammonia borane.

  18. Method for releasing hydrogen from ammonia borane

    Science.gov (United States)

    Varma, Arvind; Diwan, Moiz; Shafirovich, Evgeny; Hwang, Hyun-Tae; Al-Kukhun, Ahmad

    2013-02-19

    A method of releasing hydrogen from ammonia borane is disclosed. The method comprises heating an aqueous ammonia borane solution to between about 80-135.degree. C. at between about 14.7 and 200 pounds per square inch absolute (psia) to release hydrogen by hydrothermolysis.

  19. Ammonia and hydrogen sulfide removal using biochar

    Science.gov (United States)

    Reducing ammonia and hydrogen sulfide emissions from livestock facilities is an important issue for many communities and livestock producers. Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality. Hydrogen sulfide is highly toxic at elev...

  20. Ammonia Solubility in High Concentration Salt Solutions

    International Nuclear Information System (INIS)

    Solubility data for ammonia in water and various dilute solutions are abundant in the literature. However, there is a noticeable lack of ammonia solubility data for high salt, basic solutions of various mixtures of salts including those found in many of the Hanford Washington underground waste tanks. As a result, models based on solubility data for dilute salt solutions have been used to extrapolate to high salt solutions. These significant extrapolations need to be checked against actual laboratory data. Some indirect vapor measurements have been made. A more direct approach is to determine the ratio of solubility of ammonia in water to its solubility in high salt solutions. In various experiments, pairs of solutions, one of which is water and the other a high salt solution, are allowed to come to equilibrium with a common ammonia vapor pressure. The ratio of concentrations of ammonia in the two solutions is equal to the ratio of the respective ammonia solubilities (Henry's Law constants) at a given temperature. This information can then be used to refine the models that predict vapor space compositions of ammonia. Ammonia at Hanford is of concern because of its toxicity in the environment and its contribution to the flammability of vapor space gas mixtures in waste tanks

  1. Ammonia Sensor Using Wavelength Modulation Spectroscopy

    KAUST Repository

    Farooq, Aamir

    2015-09-01

    An ammonia sensor can include a laser detector configured to provide stable sample readings. The sensor can implement a method including processing the recorded intensity of the laser beam to determine a first harmonic component and a second harmonic component and the amount of ammonia in the sample.

  2. Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults.

    Science.gov (United States)

    Spacek, Lisa A; Mudalel, Matthew; Tittel, Frank; Risby, Terence H; Solga, Steven F

    2015-12-01

    Blood ammonia is routinely used in clinical settings to assess systemic ammonia in hepatic encephalopathy and urea cycle disorders. Despite its drawbacks, blood measurement is often used as a comparator in breath studies because it is a standard clinical test. We sought to evaluate sources of measurement error and potential clinical utility of breath ammonia compared to blood ammonia. We measured breath ammonia in real time by quartz enhanced photoacoustic spectrometry and blood ammonia in 10 healthy and 10 cirrhotic participants. Each participant contributed 5 breath samples and blood for ammonia measurement within 1 h. We calculated the coefficient of variation (CV) for 5 breath ammonia values, reported medians of healthy and cirrhotic participants, and used scatterplots to display breath and blood ammonia. For healthy participants, mean age was 22 years (±4), 70% were men, and body mass index (BMI) was 27 (±5). For cirrhotic participants, mean age was 61 years (±8), 60% were men, and BMI was 31 (±7). Median blood ammonia for healthy participants was within normal range, 10 μmol L(-1) (interquartile range (IQR), 3-18) versus 46 μmol L(-1) (IQR, 23-66) for cirrhotic participants. Median breath ammonia was 379 pmol mL(-1) CO2 (IQR, 265-765) for healthy versus 350 pmol mL(-1) CO2 (IQR, 180-1013) for cirrhotic participants. CV was 17  ±  6%. There remains an important unmet need in the evaluation of systemic ammonia, and breath measurement continues to demonstrate promise to fulfill this need. Given the many differences between breath and blood ammonia measurement, we examined biological explanations for our findings in healthy and cirrhotic participants. We conclude that based upon these preliminary data breath may offer clinically important information this is not provided by blood ammonia.

  3. Adsorption of ammonia on treated stainless steel and polymer surfaces

    Science.gov (United States)

    Vaittinen, O.; Metsälä, M.; Persijn, S.; Vainio, M.; Halonen, L.

    2014-05-01

    Adsorption of dynamically diluted ammonia at part-per-billion to low part-per-million concentrations in dry nitrogen was studied with treated and non-treated stainless steel and polymer test tubes. The treatments included electropolishing and two types of coatings based on amorphous silicon. Cavity ring-down spectroscopy with an external cavity diode laser operating in the near-infrared wavelength range was used to monitor the adsorption process in real time in continuous-flow conditions to obtain quantitative assessment of the adsorptive properties of the studied surfaces. The investigated polymers were all less adsorptive than any of the treated or non-treated stainless steel surfaces. Some of the commercial coatings reduced the adsorption loss of stainless steel by a factor of ten or more. Polyvinylidene fluoride was found to be superior (less adsorption) to the four other studied polymer coatings. The number of adsorbed ammonia molecules per surface area obtained at different ammonia gas phase concentrations was modeled with Langmuir and Freundlich isotherms. The time behavior of the adsorption-desorption process occurring in the time scale of seconds and minutes was simulated with a simple kinetic model.

  4. Surface Flux Modeling for Air Quality Applications

    Directory of Open Access Journals (Sweden)

    Limei Ran

    2011-08-01

    Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

  5. Atmospheric ammonia over China: emission estimates and impacts on air quality

    Science.gov (United States)

    Zhang, Lin; Zhao, Yuanhong; Chen, Youfan; Henze, Daven

    2016-04-01

    Ammonia (NH3) in the atmosphere is an important precursor of inorganic aerosols, and its deposition through wet and dry processes can cause adverse effects on ecosystems. The ammonia emissions over China are particularly large due to intensive agricultural activities, yet our current estimates of Chinese ammonia emissions and associated consequences on air quality are subject to large errors. Here we use the GEOS-Chem chemical transport model and its adjoint model to better quantify this issue. The TES satellite observations of ammonia concentrations and surface measurements of wet deposition fluxes are assimilated into the model to constrain the ammonia emissions over China. Optimized emissions show a strong seasonal variability with emissions in summer a factor of 3 higher than winter. We improve the bottom-up estimate of Chinese ammonia emissions from fertilizer use by using more practical feritilizer application rates for different crop types, which explains most of the discrepancies between our top-down estimates and prior emission estimates. We further use the GEOS-Chem adjoint at 0.25x0.3125 degree resolution to examine the sources contributing to the PM2.5 air pollution over North China. We show that wintertime PM2.5 over Beijing is largely contributed by residential and industrial sources, and ammonia emissions from agriculture activities. PM2.5 concentrations over North China are particularly sensitive to NH3 emissions in cold seasons due to strong nitrate formation. By converting shorted-lived nitric acid to aerosol nitrate, NH3 significantly promotes the regional transport influences of PM2.5 sources.

  6. Biogas upgrading by chemical absorption using ammonia rich absorbents derived from wastewater.

    Science.gov (United States)

    McLeod, Andrew; Jefferson, Bruce; McAdam, Ewan J

    2014-12-15

    The use of ammonia (NH3) rich wastewaters as an ecological chemical absorption solvent for the selective extraction of carbon dioxide (CO2) during biogas upgrading to 'biomethane' has been studied. Aqueous ammonia absorbents of up to 10,000 gNH3 m(-3) demonstrated CO2 absorption rates higher than recorded in the literature for packed columns using 20,000-80,000 g NH3 m(-3) which can be ascribed to the process intensification provided by the hollow fibre membrane contactor used in this study to support absorption. Centrifuge return liquors (2325 g m(-3) ionised ammonium, NH4(+)) and a regenerant (477 gNH4(+) m(-3)) produced from a cationic ion exchanger used to harvest NH4(+) from crude wastewater were also tested. Carbon dioxide fluxes measured for both wastewaters compared reasonably with analogue ammonia absorption solvents of equivalent NH3 concentration. Importantly, this demonstrates that ammonia rich wastewaters can facilitate chemically enhanced CO2 separation which eliminates the need for costly exogenic chemicals or complex chemical handling which are critical barriers to implementation of chemical absorption. When testing NH3 analogues, the potential to recover the reaction product ammonium bicarbonate (NH4HCO3) in crystalline form was also illustrated. This is significant as it suggests a new pathway for ammonia separation which avoids biological nitrification and produces ammonia stabilised into a commercially viable fertiliser (NH4HCO3). However, in real ammonia rich wastewaters, sodium bicarbonate and calcium carbonate were preferentially formed over NH4HCO3 although it is proposed that NH4HCO3 can be preferentially formed by manipulating both ion exchange and absorbent chemistry. PMID:25277752

  7. Removal of Ammonia from air using Iranian natural (clinoptilolite) zeolites

    International Nuclear Information System (INIS)

    Nowadays environmental pollution abatement through the use of natural absorbents are becoming more important, therefore, in this project the absorption behavior of ammonia on some natural zeolites (clinoptilolite) is studied. In this regard, three clinoptilolite samples of various region in Iran (Semnan, Meyaneh and Firuzkooh) were crushed, sieved and particle size of 425 μm to 4mm were used in the dynamic experiments. The breakthrough curves were plotted, and breakthrough, saturation capacity were calculated in various concentrations, temperatures and flow rates. In general, the obtained preliminary results showed that, the Iranian natural clinoptilolites are suitable absorbents for ammonia gas. In similar conditions, breakthrough time of Meyaneh sample (135 min) and absorption capacity of Semnan sample (6.35 mg/g) was higher than others

  8. Physiological plasticity of the thermophilic ammonia oxidizing archaeon Nitrosocaldus yellowstonii in response to a changing environment

    Science.gov (United States)

    Jewell, T.; Johnson, A.; Gelsinger, D.; de la Torre, J. R.

    2012-12-01

    Our understanding of nitrogen biogeochemical cycling in high temperature environments underwent a dramatic revision with the discovery of ammonia oxidizing archaea (AOA). The importance of AOA to the global nitrogen cycle came to light when recent studies of marine AOA demonstrated the dominance of these organisms in the ocean microbiome and their role as producers of the greenhouse gas nitrous oxide (N2O). Understanding how AOA respond to fluctuating environments is crucial to fully comprehending their contribution to global biogeochemical cycling and climate change. In this study we use the thermophilic AOA Nitrosocaldus yellowstonii strain HL72 to explore the physiological plasticity of energy metabolism in these organisms. Previous studies have shown that HL72 grows autotrophically by aerobically oxidizing ammonia (NH3) to nitrite (NO2-). Unlike studies of marine AOA, we find that HL72 can grow over a wide ammonia concentration range (0.25 - 10 mM NH4Cl) with comparable generation times when in the presence of 0.25 to 4 mM NH4Cl. However, preliminary data indicate that amoA, the alpha subunit of ammonia monooxygenase (AMO), is upregulated at low ammonia concentrations (urea transporter. Urea ((NH2)2CO) is an organic compound ubiquitous to aquatic and soil habitats that, when hydrolyzed, forms NH3 and CO2. We examined urea as an alternate source of ammonia for the ammonia oxidation pathway. HL72 grows over a wide range of urea concentrations (0.25 - 10 mM) at rates comparable to growth on ammonia. In a substrate competition experiment HL72 preferentially consumed NH3 from NH4Cl when both substrates were provided in equal molar concentrations. However, the urease alpha subunit ureC was expressed in both the presence and absence of urea. One consequence of urea hydrolysis is consumption of intracellular protons during the reaction. As ammonia oxidation produces H+, leading to a decrease in pH, the hydrolysis of urea prior to ammonia oxidation may help alleviate

  9. Biological Removal of Ammonia from Contaminated Air Streams Using Biofiltration System

    Directory of Open Access Journals (Sweden)

    MR Shahmansouri, H Taghipour, B Bina, H Movahdian

    2005-04-01

    Full Text Available Ammonia is a colorless, toxic, reactive and corrosive gas with a sharp odor. It is irritating to the skin, eyes, nose, throat, and lungs. Ammonia gas occurs in the environment naturally and is emitted by many industries and, therefore, its control is essential. Biofiltration is a new emerging technology that is being used as a control procedure. This study evaluates the use of a mixture of compost, sludge, and pieces of PVC as biofilter media to remove ammonia gas. The study investigates the effects of parameters such as inlet concentration, accumulation time, and depth of filter media to evaluate the removal efficiency. A laboratory scale biofilter column was built and operated to investigate the removal of ammonia from a waste gas stream. The findings indicate that for inlet concentrations of 236 ppm, and ammonia loading of less than 9.86 g-NH3/m3.h at empty bed residence time of 1 min, an ammonia removal efficiency of more than 99.9% was obtained. The acclimation period of the bacteria was 10 days. The average pressure drop during measurement was 4.44 mm H2O. The study also revealed that for concentration levels of 99, 211, and 236 ppmv, biofilter media depths of 40, 80, and 120 cm will be required, respectively. The results obtained in this study indicate that the biofiltration system composed of compost in the mixture of sludge and smashed polyvinyl chloride as biofilter media is an efficient method for the removal of ammonia from waste gas streams. It is also found that the optimum depth of biofilter media depends on the inlet concentration of ammonia.

  10. Vertical Distribution and Flux of Nutrients in the Sediments of the Mangrove Reclamation Region of Muara Angke Kapuk, Jakarta

    Directory of Open Access Journals (Sweden)

    Anna Ida Sunaryo Purwiyanto

    2012-12-01

    Full Text Available The reclaimed mangrove estuary in Muara Angke Kapuk is a reclaimed area that has not evaded the impacted of pollution and waste in the areas surrounding Cengkareng, Jakarta. This is apparent from the fact that almost all sediments under the mangrove trees are buried under heaps of plastic trash. However, the reclaimed region still has variety of organism, which indicating that the region still has an internal carrying capacity, especially nutrients from sediment. The purpose of this research was to examine the condition of sediment nutrients in this mangrove reclamation region. The research was conducted by taking water samples using a modification of the stratified cup at a sediment depth of 0-15 cm with depth intervals of 2.5 cm, and taking sediment samples using the sediment ring. Pore water samples were measured for dissolved oxygen (DO and concentrations of ammonia, nitrite, nitrate, and phosphate. Sediment samples were used to obtain porosity values. The data obtained is used to make vertical concentration profiles and analysis of vertical nutrient flux. Vertical nutrient flux analysis was performed with the aid of QUAL2K software version 2.11. The results showed different vertical distributions and flux of nutrients, where influx for ammonia and phosphate and an increase in line with increasing sediment depth, while nitrate efflux and a decreased concentration. The flux calculation of nitrite as transitory nutrient was not done, but the concentration decreased after a depth of 2.5 cm. This indicates that the high contamination on the surface does not prevent the natural chemical processes so the reclaimed region can still provide nutritional support for its organism.

  11. A rigorous calculation of the critical point from the fundamental equation of state for the water + ammonia mixture

    Energy Technology Data Exchange (ETDEWEB)

    Akasaka, Ryo [Faculty of Humanities, Kyushu Lutheran College, 3-12-16 Kurokami, Kumamoto 860-8520 (Japan)

    2009-01-15

    The critical point of the water + ammonia mixture was calculated directly from the Helmholtz free energy formulation. The calculation was performed according to the critical point criteria expressed in terms of the derivatives of the Helmholtz free energy with respect to mole numbers. Smooth critical locus linking between the critical points of pure water and ammonia was obtained. The critical locus showed a good agreement with the most reliable experimental data. Simple correlations for the critical temperature, pressure, and molar volume for a given composition were developed. The information obtained in this study is helpful for design and simulation of the cycles using the water + ammonia mixture as working fluid. (author)

  12. Low-cost anodes for ammonia electrooxidation

    Science.gov (United States)

    Selverston, Steven M.

    This research focused on the development of low-cost electrodes for the electrochemical oxidation of ammonia to nitrogen, a reaction that has possible applications in hydrogen generation, direct ammonia fuel cells, water treatment, and sensors. Statistical design of experiments was used to help develop an efficient and scalable process for electrodeposition of platinum with a specific electrochemical surface area of over 25 m2 /g. Catalyst surface area and activity were evaluated using cyclic voltammetry, and the material microstructure and morphology were investigated using x-ray diffraction and scanning electron microscopy. The synthesized electrodes were found to be active toward the ammonia electrooxidation reaction, particularly when supporting electrolyte was added. However, supporting electrolyte was not required in order to oxidize the ammonia. As proof of concept, a homemade direct ammonia fuel cell employing a commercial anion exchange membrane was tested at room temperature with gravity-fed fuel and without supporting electrolyte. At room temperature, with passive reactant supply and using dissolved oxygen at the cathode, the cell produced about one quarter the power of a direct methanol fuel cell that used active transport of humidified oxygen and preheated (50 °C) methanol. With continued development of the membrane, cathode and membrane electrode assembly, the passive direct ammonia fuel cell using anion exchange membrane could have performance similar to the equivalent direct methanol fuel cell, and it could benefit from many advantages of ammonia over methanol such as lower cost, higher energy density, and reduced greenhouse gas emissions.

  13. WOOD COLOR CHANGES BY AMMONIA FUMING

    Directory of Open Access Journals (Sweden)

    Josip Miklečić,

    2012-06-01

    Full Text Available This paper studies the influence of ammonia gas on wood color changes in response to an increasing demand for dark colored wood specimens. The darker wood color in ammonia fuming is accomplished through chemical reactions between ammonia gas and wood compounds. We exposed oak, maple, spruce, and larch wood samples to ammonia gas for 16 days. During fuming, the color changes were studied using CIE L*a*b* parameters. After fuming, the changes in extractives content, tannin, and nitrogen content were analyzed. The chemical changes of wood and residues of wood extractives after fuming were analyzed by FTIR spectroscopy. Oak wood reacted intensively with ammonia gas in a very short time, and the darkening was prominent for all the investigated wood species. It was established that tannin had no major influence on color changes of maple and larch wood in the ammonia-fuming process. The FTIR spectra of fumed wood indicated involvement of carbonyl groups, and the FTIR spectra of wood extractives indicated involvement of carbonyl, aromatic, and alcohol groups in reaction with ammonia gas.

  14. Resveratrol prevents ammonia toxicity in astroglial cells.

    Directory of Open Access Journals (Sweden)

    Larissa Daniele Bobermin

    Full Text Available Ammonia is implicated as a neurotoxin in brain metabolic disorders associated with hyperammonemia. Acute ammonia toxicity can be mediated by an excitotoxic mechanism, oxidative stress and nitric oxide (NO production. Astrocytes interact with neurons, providing metabolic support and protecting against oxidative stress and excitotoxicity. Astrocytes also convert excess ammonia and glutamate into glutamine via glutamine synthetase (GS. Resveratrol, a polyphenol found in grapes and red wines, exhibits antioxidant and anti-inflammatory properties and modulates glial functions, such as glutamate metabolism. We investigated the effect of resveratrol on the production of reactive oxygen species (ROS, GS activity, S100B secretion, TNF-α, IL-1β and IL-6 levels in astroglial cells exposed to ammonia. Ammonia induced oxidative stress, decreased GS activity and increased cytokines release, probably by a mechanism dependent on protein kinase A (PKA and extracellular signal-regulated kinase (ERK pathways. Resveratrol prevented ammonia toxicity by modulating oxidative stress, glial and inflammatory responses. The ERK and nuclear factor-κB (NF-κB are involved in the protective effect of resveratrol on cytokines proinflammatory release. In contrast, other antioxidants (e.g., ascorbic acid and trolox were not effective against hyperammonemia. Thus, resveratrol could be used to protect against ammonia-induced neurotoxicity.

  15. Ammonia synthesis using magnetic induction method (MIM)

    Science.gov (United States)

    Puspitasari, P.; Razak, J. Abd; Yahya, N.

    2012-09-01

    The most challenging issues for ammonia synthesis is to get the high yield. New approach of ammonia synthesis by using Magnetic Induction Method (MIM) and the Helmholtz Coils has been proposed. The ammonia detection was done by using Kjeldahl Method and FTIR. The system was designed by using Autocad software. The magnetic field of MIM was vary from 100mT-200mT and the magnetic field for the Helmholtz coils was 14mT. The FTIR result shows that ammonia has been successfully formed at stretching peaks 1097,1119,1162,1236, 1377, and 1464 cm-1. UV-VIS result shows the ammonia bond at 195nm of wavelength. The ammonia yield was increase to 244.72μmole/g.h by using the MIM and six pairs of Helmholtz coils. Therefore this new method will be a new promising method to achieve the high yield ammonia at ambient condition (at 25δC and 1atm), under the Magnetic Induction Method (MIM).

  16. Heat Flux Apportionment to Heterogeneous Surfaces Using Flux Footprint Analysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Heat flux data collected from the Baiyangdian Heterogeneous Field Experiment were analyzed using the footprint method. High resolution (25 m) Landsat-5 satellite imaging was used to determine the land cover as one of four surface types: farmland, lake, wetland, or village. Data from two observation sites in September 2005 were used. One site (Wangjiazhai) was characterized by highly heterogeneous surfaces in the central area of the Baiyangdian: lake/wetland. The other site (Xiongxian) was on land with more uniform surface cover. An improved Eulerian analytical flux footprint model was used to determine "source areas" of the heat fluxes measured at towers located at each site from surrounding landscapes of mixed surface types.In relative terms results show that wetland and lake areas generally contributed most to the observed heat flux at Wangjiazhai, while farmland contributed most at Xiongxian. Given the areal distribution of surface type contributions, calculations were made to obtain the magnitudes of the heat flux from lake, wetland and farmland to the total observed flux and apportioned contributions of each surface type to the sensible and latent heat fluxes. Results show that on average the sensible heat flux from wetland and farmland were comparable over the diurnal cycle, while the latent heat flux from farmland was somewhat larger by about 30-50 W m-2 during daytime. The latent and sensible fluxes from the lake source in daytime were about 50 W m-2 and 100 W m-2 less, respectively, than from wetland and farmland. The results are judged reasonable and serve to demonstrate the potential for flux apportionment over heterogeneous surfaces.

  17. [Use of open-path TDL technique and the backward Lagrangian stochastic model to monitor ammonia emission from summer maize field].

    Science.gov (United States)

    Yang, Wen-Liang; Zhu, An-Ning; Zhang, Jia-Bao; Zhang, Yu-Jun; He, Ying; Wang, Li-Ming; Chen, Xiao-Min; Chen, Wen-Chao

    2012-11-01

    The backward Lagrangian stochastic dispersion model in conjunction with open-path tunable diode absorption spectroscopy was used to quantify ammonia emissions from farmland based on the high-temporal resolution data, aiming to provide innovative achievements to diagnose patterns of ammonia flux. The results indicate that the bLS dispersion technique using open-path lasers to measure atmospheric ammonia concentrations is suitable for determining ammonia emissions from farmland continuously, especially for characterizing diurnal characteristics of NH3 emissions. The ammonia emissions have a significant diurnal pattern with two emission peaks from urea applied to maize on a calcareous sandy loam fluvo-aquic soil in the North China Plain. We believe that the first peak starting at approximately 9:00 am is due to NH3 absorbed by the dew re-emission at night as the dew evaporates. The maximum of ammonia flux at 14:00 corresponds to the peak of soil temperature and solar radiation. The ammonia emission increased rapidly, but the duration of emission peaks lasted approximately 4 d. Cumulative NH3 emission was 25.3% of the applied N over the entire measurement period. The NH3 emissions measured with bLS dispersion technique and venting method had certain difference. PMID:23387189

  18. Measured and simulated nitrogen fluxes after field application of food-processing and municipal organic wastes.

    Science.gov (United States)

    Parnaudeau, V; Génermont, S; Hénault, C; Farrugia, A; Robert, P; Nicolardot, B

    2009-01-01

    The aims of this study were to (i) assess N fluxes (mineralization, volatilization, denitrification, leaching) caused by spreading various organic wastes from food-processing industries during a field experiment, and (ii) to identify the main factors affecting N transformation processes after field spreading. Experimental treatments including the spreading of six types of waste and a control soil were set up in August 2000 and studied for 22 mo under bare soil conditions. Ammonia and nitrous oxide emissions, and nitrogen mineralization were measured in experimental devices and extrapolated to field conditions or computed in calculation models. The ammonia emissions varied from 80 to 580 g kg(-1) NH4+-N applied, representing 0 to 90 g N kg(-1) total N applied. Under these meteorologically favorable conditions (dry and warm weather), waste pH was the main factor affecting volatilization rates. Cumulated N2O-N fluxes were estimated at 2 to 5 g kg(-1) total N applied, which was quite low due to the low soil water content during the experimental period; water-filled pore space (WFPS) was confirmed as the main factor affecting N2O fluxes. Nitrogen mineralization from wastes represented 126 to 723 g N kg(-1) organic N added from the incorporation date to 14 May 2001 and was not related to the organic C to organic N ratio of wastes. Nitrogen lost by leaching during the equivalent period ranged from 30 to 890 g kg(-1) total N applied. The highest values were obtained for wastes having the highest inorganic N content and mineralization rates.

  19. Evaluating Ammonia Deposition Rates for Deciduous Forest using Measurements and Modelling

    DEFF Research Database (Denmark)

    Hansen, Kristina; Geels, Camilla; Hertel, Ole;

    these impacts, quantifying the magnitude of the NH3 flux in the biosphere atmosphere system is essential. Model simulations using the Danish Ammonia Modelling System (DAMOS) have recently indicated that particular forest ecosystems are exposed to critical load exceedances of N (Geels et al., not yet submitted...... atmospheric mean concentrations of NH3 agreed well within the range of 0.56-0.68 g NH3-N m-3, however, observed emission fluxes of up to app. 0.8 g NH3-N m-2 s-1 after leaf fall were not represented by DAMOS because the model system does not consider vegetative and soil NH3 emissions from non...

  20. Evaluating Ammonia Deposition Rates for Deciduous Forest using Measurements and Modelling

    DEFF Research Database (Denmark)

    Hansen, Kristina; Geels, Camilla; Hertel, Ole;

    these impacts, quantifying the magnitude of the NH3 flux in the biosphere atmosphere system is essential. Model simulations using the Danish Ammonia Modelling System (DAMOS) have recently indicated that particular forest ecosystems are exposed to critical load exceedances of N (Geels et al., not yet submitted......). However, there are relatively few datasets of atmospheric NH3 fluxes available for forests which can contribute verifying model results. The atmospheric dry deposition of NH3 for the beech (Fagus sylvatica) forest, Lille Bøgeskov, in Sorø, Denmark, is investigated using the high resolution...

  1. Ammonia as a Suitable Fuel for Fuel Cells

    OpenAIRE

    Lan, Rong; Tao, Shanwen

    2014-01-01

    Ammonia, an important basic chemical, is produced at a scale of 150 million tons per year. Half of hydrogen produced in chemical industry is used for ammonia production. Ammonia containing 17.5 wt% hydrogen is an ideal carbon-free fuel for fuel cells. Compared to hydrogen, ammonia has many advantages. In this mini-review, the suitability of ammonia as fuel for fuel cells, the development of different types of fuel cells using ammonia as the fuel and the potential applications of ammonia fuel ...

  2. Ammonia Volatilization from Urea Applied to Acid Paddy Soil in Southern China and Its Control

    Institute of Scientific and Technical Information of China (English)

    CAIGUI-XIN; PENGGUANG-HAO; 等

    1992-01-01

    Results showed that ammonia loss from urea broadcast into floodwater and incorporated into soil at transplanting was as high as 40% of applied N,and the corresponding total nitrogen (N) loss was 56%.Ammonia loss was measured with simplified micrometeorological method (ammonia sampler),and total N loss was concurrently measured using 15N balance technique.The experiment was conducted under strong sunshine conditions on acid paddy soil derived from Quaternary red clay.The ammonia loss in this particular condition was much greater than those obtained from previous studies when urea was also applied to acid paddy soil but under cloudy conditions.It is concluded that the strong sunshine conditions with high temperature and shallow floodwater during the period of present experiment favoured ammonia volatilization.Application of stearyl alcohol on the surface of the floodwater reduced ammonia loss to 23% of applied N.However,the effect of stearyl alcohol was short-lived,probably due to the microbiological decomposition.

  3. Model Research on the Effect of Surface Film on Ammonia Volatilization from Rice Field

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Shun-yao; YIN Bin; ZHU Zhao-liang

    2002-01-01

    Pan and field experiments were conducted to investigate the effect of surface film on ammonia volatilization from water and paddy soil. The results showed that the addition of the surface film on floodwater reduced the rate of ammonia volatilization, however, the reduction of the latter varied greatly with its rates of addition. Jayaweera-Mikkelsen ammonia volatilization model with the introduction of a parameter Kf, a relative measure of the resistance of the surface film on ammonia volatilization, was used to elucidate the effectiveness of the surface film on lowering ammonia volatilization. The Kf value was calculated from the results obtained in the pan experiment with different rates of surface film addition. With the modified model and the optimized Kf value, the effects of the surface film in reducing ammonia volatilization under different environmental conditions were simulated and analyzed. However, it was found that the simulation was not satisfactory in the field experiment and the parameter Kf should be further tuned so as to improve the simulation and to optimize the addition rate of the surface film in field conditions.

  4. Fabrication of interdigitated electrodes by inkjet printing technology for apllication in ammonia sensing

    Science.gov (United States)

    Dam Le, Duy; Nhien Nguyen, Thi Ngoc; Chanh Tin Doan, Duc; Dung Dang, Thi My; Chien Dang, Mau

    2016-06-01

    In this paper interdigitated electrodes for gas sensors were fabricated by inkjet printing technology. Silver electrodes were inkjet printed on Si/SiO2 substrates instead of traditional photolithography method. The inkjet printing parameters to obtain desired dimensions, thickness of the electrodes and distance between the interdigitated electrodes were optimized in this study. The fabricated interdigitated silver electrodes were tested for application in ammonia gas sensors. Conductive polyaniline (PANI) layer was coated on the silver interdigitated electrodes by drop-coating. Ammonia detection of the PANI-coated chips was characterized with a gas measurement system in which humidity and ammonia concentrations were well-controlled. The electrical conductivity of the PANI films coated on the electrodes was measured when the PANI films were exposed to nitrogen and ammonia. The conductivity of the PANI films decreased significantly due to the deprotonation process of PANI upon ammonia expodure. The recovery time was about 15 min by heating up the polymer chip at 60 °C. The results showed that the silver electrodes fabricated by inkjet printing technique could be used as a sensor platform for ammonia detection.

  5. Measurement of Ammonia Emission Following Surface Application of Urea Fertilizer from Irrigated Paddy Rice Fields

    Institute of Scientific and Technical Information of China (English)

    Md.Toufiq Iqbal; TIAN Guang-ming; LIANG Xin-qiang; Fatima Rukshana

    2005-01-01

    Ammonia emission is one of the most important pathways of nitrogen loss from agricultural cultivated field. In this paper, we report the measurement of ammonia emission from paddy rice field obtained by surface application of urea fertilizer with water management. The main objective of the present study were to assess the amount of NH3 emission and the loss of nitrogen from paddy field as affected by various N doses, i.e., 0 (control), 90 (N1), 180 (N2), 270 (N3) and 360 (N4) kg ha-1, following field surface application of urea fertilizer with water management. Ammonia emissions were measured by continuous airflow enclosure method from plots fertilized with the application of surface urea. Increase in urea-N dosage increased NH3 emission thatwas measured from paddy rice field. Ammonia emission started immediately and was almost complete within 12 days after top dressing of urea application to the soils. Ammonia emissions were nearly constant in all treatments from 12 days after fertilizer application. Highest ammonia emission rate was 28 g/day and total amount of ammonia emission was 56.21 kg ha-1 for 360 kg N ha-1 dose. No remarkable observation was found about temperature for ammonia emission. Due to proper water management practices less emission was observed throughout the experiment period. The results also show that N loss through NH3 emission accounted for 11 to 16% during the ricegrowing season. These magnitudes of loss of N appear to be most important for environmental point of view.

  6. Ammonia measurement with a pH electrode in the ammonia/urea-SCR process

    Science.gov (United States)

    Kröcher, Oliver; Elsener, Martin

    2007-03-01

    The selective catalytic reduction of nitrogen oxides with ammonia (ammonia SCR) and urea (urea SCR), respectively, is a widespread process to clean flue and diesel exhaust gases due to its simplicity and efficiency. The main challenge of the process is to minimize the ammonia emissions downstream of the SCR catalyst. We found that ammonia emissions of >10 ppm can reliably be detected with a simple pH electrode in the presence of CO2, SOx, NOx, and moderately weak organic acids. 10-20 ppm of ammonia in the exhaust gas are sufficient to neutralize the acids and to increase the pH value from 3 to 6. On this basis a continuous measuring method for ammonia was developed, which was used to control the dosage of urea in the SCR process. While keeping the ammonia emissions after the SCR catalyst at 5-30 ppm an average NOx removal efficiency (DeNOx) of >95% were achieved at a diesel test rig. The method can also be applied for exhaust gases with higher acid contents, if a basic pre-filter is added adsorbing the acidic exhaust components. Compared to water as absorption solution, more precise ammonia measurements are possible, if a 0.1 M NH4Cl absorption solution is applied, whose pH value is changing as a Nernst function of the ammonia concentration.

  7. Ammonia manipulates the ammonia-oxidizing archaea and bacteria in the coastal sediment-water microcosms.

    Science.gov (United States)

    Zhang, Yan; Chen, Lujun; Dai, Tianjiao; Sun, Renhua; Wen, Donghui

    2015-08-01

    Ammonia was observed as a potential significant factor to manipulate the abundance and activity of ammonia-oxidizing microorganisms (AOMs) in water environments. For the first time, this study confirmed this phenomenon by laboratory cultivation. In a series of estuarine sediment-coastal water microcosms, we investigated the AOM's phylogenetic composition and activity change in response to ammonia concentration. Increase of ammonia concentration promoted bacterial amoA gene abundance in a linear pattern. The ratio of transcribed ammonia-oxidizing bacteria (AOB) amoA gene/ammonia-oxidizing archaea (AOA) amoA gene increased from 0.1 to 43 as NH4 (+)-N increased from less than 0.1 to 12 mg L(-1), and AOA amoA transcription was undetected under 20 mg NH4 (+)-N L(-1). The incubation of stable isotope probing (SIP) microcosms revealed a faster (13)C-NaHCO3 incorporation rate of AOA amoA gene under 0.1 mg NH4 (+)-N L(-1) and a sole (13)C-NaHCO3 utilization of the AOB amoA gene under 20 mg NH4 (+)-N L(-1). Our results indicate that ammonia concentration manipulates the structure of AOM. AOA prefers to live and perform higher amoA transcription activity than AOB in ammonia-limited water environments, and AOB tends to take the first contributor place in ammonia-rich ones. PMID:25797330

  8. Assimilation of ammonia in Paracoccus denitrificans.

    Science.gov (United States)

    Mikes, V; Chválová, H; Mátlová, L

    1991-01-01

    Two pathways serve for assimilation of ammonia in Paracoccus denitrificans. Glutamate dehydrogenase (NADP+) catalyzes the assimilation at a high NH4+ concentration. If nitrate serves as the nitrogen source, glutamate is synthesized by glutamate-ammonia ligase and glutamate synthase (NADPH). At a very low NH4+ concentration, all three enzymes are synthesized simultaneously. No direct relationship exists between glutamate dehydrogenase (NADP+) and glutamate-ammonia ligase in P. denitrificans, while the glutamate synthase (NADPH) activity changes in parallel with that of the latter enzyme. Ammonia does not influence the induction or repression of glutamate dehydrogenase (NADP+). The inner concentration of metabolites indicates a possible repression of glutamate dehydrogenase (NADP+) by the high concentration of glutamine or its metabolic products as in the case when NH4+ is formed by assimilative nitrate reduction. No direct effect of the intermediates of nitrate assimilation on the synthesis of glutamate dehydrogenase (NADP+) was observed. PMID:1688163

  9. Ultrafast dynamics of electrons in ammonia.

    Science.gov (United States)

    Vöhringer, Peter

    2015-04-01

    Solvated electrons were first discovered in solutions of metals in liquid ammonia. The physical and chemical properties of these species have been studied extensively for many decades using an arsenal of electrochemical, spectroscopic, and theoretical techniques. Yet, in contrast to their hydrated counterpart, the ultrafast dynamics of ammoniated electrons remained completely unexplored until quite recently. Femtosecond pump-probe spectroscopy on metal-ammonia solutions and femtosecond multiphoton ionization spectroscopy on the neat ammonia solvent have provided new insights into the optical properties and the reactivities of this fascinating species. This article reviews the nature of the optical transition, which gives the metal-ammonia solutions their characteristic blue appearance, in terms of ultrafast relaxation processes involving bound and continuum excited states. The recombination processes following the injection of an electron via photoionization of the solvent are discussed in the context of the electronic structure of the liquid and the anionic defect associated with the solvated electron. PMID:25493716

  10. Ammonia Affects Astroglial Proliferation in Culture.

    Directory of Open Access Journals (Sweden)

    Guillermo Bodega

    Full Text Available Primary cultures of rat astroglial cells were exposed to 1, 3 and 5 mM NH4Cl for up to 10 days. Dose- and time-dependent reductions in cell numbers were seen, plus an increase in the proportion of cells in the S phase. The DNA content was reduced in the treated cells, and BrdU incorporation diminished. However, neither ammonia nor ammonia plus glutamine had any effect on DNA polymerase activity. iTRAQ analysis showed that exposure to ammonia induced a significant reduction in histone and heterochromatin protein 1 expression. A reduction in cell viability was also noted. The ammonia-induced reduction of proliferative activity in these cultured astroglial cells seems to be due to a delay in the completion of the S phase provoked by the inhibition of chromatin protein synthesis.

  11. Errors in airborne flux measurements

    Science.gov (United States)

    Mann, Jakob; Lenschow, Donald H.

    1994-07-01

    We present a general approach for estimating systematic and random errors in eddy correlation fluxes and flux gradients measured by aircraft in the convective boundary layer as a function of the length of the flight leg, or of the cutoff wavelength of a highpass filter. The estimates are obtained from empirical expressions for various length scales in the convective boundary layer and they are experimentally verified using data from the First ISLSCP (International Satellite Land Surface Climatology Experiment) Field Experiment (FIFE), the Air Mass Transformation Experiment (AMTEX), and the Electra Radome Experiment (ELDOME). We show that the systematic flux and flux gradient errors can be important if fluxes are calculated from a set of several short flight legs or if the vertical velocity and scalar time series are high-pass filtered. While the systematic error of the flux is usually negative, that of the flux gradient can change sign. For example, for temperature flux divergence the systematic error changes from negative to positive about a quarter of the way up in the convective boundary layer.

  12. Sanitisation of faecal sludge by ammonia

    OpenAIRE

    Fidjeland, Jörgen

    2015-01-01

    Faecal sludge contains valuable plant nutrients and can be used as a fertiliser in agriculture, instead of being emitted as a pollutant. As this involves a risk of pathogen transmission, it is crucial to inactivate the pathogens in faecal sludge. One treatment alternative is ammonia sanitisation, as uncharged ammonia (NH₃) inactivates pathogens. The aim of this thesis was to study how the pathogen inactivation depends on treatment factors, mainly NH₃ concentration, temperature and storage tim...

  13. Structures and relative stabilities of ammonia clusters at different temperatures: DFT vs. ab initio.

    Science.gov (United States)

    Malloum, Alhadji; Fifen, Jean Jules; Dhaouadi, Zoubeida; Engo, Serge Guy Nana; Jaidane, Nejm-Eddine

    2015-11-21

    A hydrogen bond network in ammonia clusters plays a key role in understanding the properties of species embedded in ammonia. This network is dictated by the structures of neutral ammonia clusters. In this work, structures of neutral ammonia clusters (NH3)n(=2-10) have been studied at M06-2X/6-31++G(d,p) and MP2/6-31++g(d,p) levels of theory. The analysis of the relative stabilities of various hydrogen bond types has also been studied and vibrational spectroscopy of the ammonia pentamer and decamer is investigated. We noted that M06-2X provides lower electronic energies, greater binding energies and higher structural resolution than MP2. We also noted that at the M06-2X level of theory, the binding energy converges to the experimental vaporization enthalpy faster than that at the MP2 level of theory. As a result, it is found that the M06-2X functional could be more suitable than the MP2 ab initio method in the description of structures and energies of ammonia clusters. However, we found that the electronic energy differences obtained at both levels of computation follow a linear relation with n (number of ammonia molecules in a cluster). As far as the structures of ammonia clusters are concerned, we proposed new "significant" isomers that have not been reported previously. The most remarkable is the global minimum electronic energy structure of the ammonia hexamer, which has an inversion centre and confirms experimental observation. Moreover, we reported the relative stabilities of neutral ammonia clusters for temperatures ranging from 25 to 400 K. The stability of isomers changes with the increase of the temperature. As a result, the branched and less bonded isomers are the most favored at high temperatures and disfavored at low temperatures, while compact and symmetric isomers dominate the population of clusters at low temperatures. In fine, from this work, the global minimum energy structures of ammonia clusters are known for the first time at a given temperature

  14. Study of the acceleration of ammonia generation process from poultry residues aiming at hydrogen production

    International Nuclear Information System (INIS)

    The hydrogen, utilized in fuel cells, can be produced from a variety of intermediate chemicals, between them, the ammonia. The ammonia gas as a raw material for the hydrogen production has been used due to its high energetic content, facility of decomposition, high availability, low prices, low storage pressure and its by-products are environmentally correct. One of the sources of ammonia is poultry and egg production systems. In these systems the ammonia is produced from the decomposition of uric acid present in the excreta of birds. The residue from the poultry-rearing farms is the broiler litter and from the egg production system is the excreta without any substrate. The characterization of these residues was performed using the Wavelength-Dispersive X-Ray Fluorescence (WDXRF), Elementary Analysis (CHN), Thermogravimetry and GC/MS - Gas chromatography/ Mass spectrometry. The studied factors which influence the ammonia volatilization were: nitrogen content, raising period, urease enzyme, temperature, pH and moisture content. The experiment results with poultry litter and excreta allow to conclude that the manipulation of the following parameters increased the ammonia emission: pH, nitrogen content, raising period, age of birds and excreta accumulation, urease enzyme and the temperature. The addition of different amounts of sand in the excreta and different volumes of water in the poultry litter inhibited the emission of ammonia. The variation of the quantity of material (broiler litter or excreta) and the volume of the flask used as incubator chamber showed no significant alterations to be chosen as a variable. The excreta was considered more appropriate than poultry litter for the objectives of this work due to the higher ammonia concentrations determined in this material. Due to the large amount of poultry litter and excreta from the production processes, the reuse of poultry residues to obtain ammonia is necessary to improve the quality of the local

  15. Study of Ammonia Emissions in a Ventilated Pig Pen

    OpenAIRE

    Rong, Li

    2011-01-01

    Pig productions cause a wide emission of odors, such as ammonia (NH3), hydrogen sulfide (H2S), and methane (CH4). Ammonia is one of the most important emissions for evaluating the air quality either in animal buildings or atmospheric environment. In studies of ammonia emission from animal buildings reported in literature, little effort has been made to investigate the accuracy of current Henry’s law constant for modeling ammonia mass transfer process and study ammonia emissions in a full scal...

  16. Corrosion inhibitor for aqueous ammonia absorption system

    Science.gov (United States)

    Phillips, Benjamin A.; Whitlow, Eugene P.

    1998-09-22

    A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.

  17. Livestock wastewater treatment: ammonia removal

    International Nuclear Information System (INIS)

    Livestock wastewater contains high concentration of ammonia. Removal of this inorganic species of nitrogen could be achieved through nitrification and de-nitrification. Nitrification process was conducted in the laboratory using activated sludge process with HRT of three and five days. After wastewater undergone nitrification process at Livestock Wastewater Treatment Plant the concentration of influent for N-NH4+ reduced from 400 mg/l to 0 mg/l and concentration of N-NO3- increased from 11 mg/l to 300 mg/l. Nitrification using lab-scale activated sludge process also recorded similar result. Concentration of N-NH4+ reduced from 400 mg/l to 2 mg/l and 380 mg/l to 1.1 mg/l for HRT=5 days and HRT=3 days respectively. N-NO3- was increased from 11 mg/l to 398 mg/l and 14 mg/l to 394 mg/l for HRT=5 days and HRT=3 days, respectively. However changes of N-NH4+ and N=NO3- were not observed using gamma irradiation. The combination of gamma irradiation with activated sludge process indicated difference and its contribution is still investigated

  18. Screening of electrocatalysts for direct ammonia fuel cell: Ammonia oxidation on PtMe (Me: Ir, Rh, Pd, Ru) and preferentially oriented Pt(1 0 0) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Vidal-Iglesias, F.J.; Solla-Gullon, J.; Montiel, V.; Feliu, J.M.; Aldaz, A. [Instituto de Electroquimica, Universidad de Alicante, Apartado 99, 03080 Alicante (Spain)

    2007-09-27

    Ammonia has attracted attention as a possible fuel for direct fuel cells since it is easy to handle and to transport as liquid or as concentrated aqueous solution. However, on noble metal electrodes ammonia oxidation is a sluggish reaction and the electrocatalyst needs to be improved for developing efficient ammonia fuel cells. In this work, ammonia electrooxidation reaction on 3-4-nm bimetallic PtMe (Ir, Rh, Pd, Ru) and on preferentially oriented Pt(1 0 0) nanoparticles is reported. PtMe nanoparticles have been prepared by using water-in-oil microemulsions to obtain a narrow size distribution whereas preferentially oriented Pt nanoparticles have been prepared through colloidal routes. Among all the bimetallic samples tested, only Pt{sub 75}Ir{sub 25} and Pt{sub 75}Rh{sub 25} nanoparticles show, at the low potential range, an enhancement of the oxidation density current with respect to the behaviour found for pure platinum nanoparticles prepared by the same method. In addition, two Pt(1 0 0) preferentially oriented nanoparticles of different particle size (4 and 9 nm) have been also studied. These oriented nanoparticles show higher current densities than polycrystalline Pt nanoparticles due to the sensitivity of ammonia oxidation toward the presence of surface sites with square symmetry. The reactivity of the different 4-nm nanoparticles parallels well with that expected from bulk PtMe alloys and Pt single crystal electrodes. (author)

  19. Screening of electrocatalysts for direct ammonia fuel cell: Ammonia oxidation on PtMe (Me: Ir, Rh, Pd, Ru) and preferentially oriented Pt(1 0 0) nanoparticles

    Science.gov (United States)

    Vidal-Iglesias, F. J.; Solla-Gullón, J.; Montiel, V.; Feliu, J. M.; Aldaz, A.

    Ammonia has attracted attention as a possible fuel for direct fuel cells since it is easy to handle and to transport as liquid or as concentrated aqueous solution. However, on noble metal electrodes ammonia oxidation is a sluggish reaction and the electrocatalyst needs to be improved for developing efficient ammonia fuel cells. In this work, ammonia electrooxidation reaction on 3-4-nm bimetallic PtMe (Ir, Rh, Pd, Ru) and on preferentially oriented Pt(1 0 0) nanoparticles is reported. PtMe nanoparticles have been prepared by using water-in-oil microemulsions to obtain a narrow size distribution whereas preferentially oriented Pt nanoparticles have been prepared through colloidal routes. Among all the bimetallic samples tested, only Pt 75Ir 25 and Pt 75Rh 25 nanoparticles show, at the low potential range, an enhancement of the oxidation density current with respect to the behaviour found for pure platinum nanoparticles prepared by the same method. In addition, two Pt(1 0 0) preferentially oriented nanoparticles of different particle size (4 and 9 nm) have been also studied. These oriented nanoparticles show higher current densities than polycrystalline Pt nanoparticles due to the sensitivity of ammonia oxidation toward the presence of surface sites with square symmetry. The reactivity of the different 4-nm nanoparticles parallels well with that expected from bulk PtMe alloys and Pt single crystal electrodes.

  20. Ammonia removal in the carbon contactor of a hybrid membrane process.

    Science.gov (United States)

    Stoquart, Céline; Servais, Pierre; Barbeau, Benoit

    2014-12-15

    The hybrid membrane process (HMP) coupling powdered activated carbon (PAC) and low-pressure membrane filtration is emerging as a promising new option to remove dissolved contaminants from drinking water. Yet, defining optimal HMP operating conditions has not been confirmed. In this study, ammonia removal occurring in the PAC contactor of an HMP was simulated at lab-scale. Kinetics were monitored using three PAC concentrations (1-5-10 g L(-1)), three PAC ages (0-10-60 days), two temperatures (7-22 °C), in ambient influent condition (100 μg N-NH4 L(-1)) as well as with a simulated peak pollution scenario (1000 μg N-NH4L(-1)). The following conclusions were drawn: i) Using a colonized PAC in the HMP is essential to reach complete ammonia removal, ii) an older PAC offers a higher resilience to temperature decrease as well as lower operating costs; ii) PAC concentration inside the HMP reactor is not a key operating parameter as under the conditions tested, PAC colonization was not limited by the available surface; iii) ammonia flux limited biomass growth and iv) hydraulic retention time was a critical parameter. In the case of a peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed reaching a 50% ammonia removal. Finally, a kinetic model based on these experiments is proposed to predict ammonia removal occurring in the PAC reactor of the HMP. The model determines the relative importance of the adsorption and biological oxidation of ammonia on colonized PAC, and demonstrates the combined role of nitrification and residual adsorption capacity of colonized PAC.

  1. Ammonia removal in the carbon contactor of a hybrid membrane process.

    Science.gov (United States)

    Stoquart, Céline; Servais, Pierre; Barbeau, Benoit

    2014-12-15

    The hybrid membrane process (HMP) coupling powdered activated carbon (PAC) and low-pressure membrane filtration is emerging as a promising new option to remove dissolved contaminants from drinking water. Yet, defining optimal HMP operating conditions has not been confirmed. In this study, ammonia removal occurring in the PAC contactor of an HMP was simulated at lab-scale. Kinetics were monitored using three PAC concentrations (1-5-10 g L(-1)), three PAC ages (0-10-60 days), two temperatures (7-22 °C), in ambient influent condition (100 μg N-NH4 L(-1)) as well as with a simulated peak pollution scenario (1000 μg N-NH4L(-1)). The following conclusions were drawn: i) Using a colonized PAC in the HMP is essential to reach complete ammonia removal, ii) an older PAC offers a higher resilience to temperature decrease as well as lower operating costs; ii) PAC concentration inside the HMP reactor is not a key operating parameter as under the conditions tested, PAC colonization was not limited by the available surface; iii) ammonia flux limited biomass growth and iv) hydraulic retention time was a critical parameter. In the case of a peak pollution, the process was most probably phosphate-limited but a mixed adsorption/nitrification still allowed reaching a 50% ammonia removal. Finally, a kinetic model based on these experiments is proposed to predict ammonia removal occurring in the PAC reactor of the HMP. The model determines the relative importance of the adsorption and biological oxidation of ammonia on colonized PAC, and demonstrates the combined role of nitrification and residual adsorption capacity of colonized PAC. PMID:25459222

  2. Fluorescence Excitation Models of Ammonia and Amidogen Radical (NH2) in Comets: Application to Comet C/2004 Q2 (Machholz)

    Science.gov (United States)

    Kawakita, Hideyo; Mumma, Michael J.

    2011-01-01

    Ammonia is a major reservoir of nitrogen atoms in cometary materials. However, detections of ammonia in comets are rare, with several achieved at radio wavelengths. A few more detections were obtained through near-infrared observations (around the 3 m wavelength region), but moderate relative velocity shifts are required to separate emission lines of cometary ammonia from telluric absorption lines in the 3 micron wavelength region. On the other hand, the amidogen radical (NH2 -- a photodissociation product of ammonia in the coma) also shows rovibrational emission lines in the 3 micron wavelength region. Thus, gas production rates for ammonia can be determined from the rovibrational emission lines of ammonia (directly) and amidogen radical (indirectly) simultaneously in the near-infrared. In this article, we present new fluorescence excitation models for cometary ammonia and amidogen radical in the near-infrared, and we apply these models to the near-infrared high-dispersion spectra of comet C/2004 Q2 (Machholz) to determine the mixing ratio of ammonia to water in the comet. Based on direct detection of NH3 lines, the mixing ratio of NH3/H2O is 0.46% +/- 0.03% in C/2004 Q2 (Machholz), in agreement with other results. The mixing ratio of ammonia determined from the NH2 observations (0.31% -- 0.79%) is consistent but has relatively larger error, owing to uncertainty in the photodissociation rates of ammonia. At the present level of accuracy, we confirm that NH3 could be the sole parent of NH2 in this comet.

  3. Determination of Energy Fluxes Over Agricultural Surfaces

    Directory of Open Access Journals (Sweden)

    Josefina Argete

    1994-12-01

    Full Text Available An energy budget was conducted over two kinds if surfaces: grass and corn canopy. The net radiative flux and the soil heat flux were directly measured while the latent and sensible heat flux were calculated from the vertical profiles if wet and dry-bulb temperature and wind speed. The crop storage flux was also estimated. Using the gradient or aerodynamic equations, the calculated fluxes when compared to the measured fluxes in the context of an energy budget gave an SEE = 63 Wm-2 over grass and SEE = 81 Wm-2 over corn canopy. The calculated fluxes compared reasonably well with those obtained using the Penman equations.For an energy budget research with limited instrumentation, the aerodynamic method performed satisfactorily in estimating the daytime fluxes, when atmospheric conditions are fully convective, but failed when conditions were stably stratified as during nighttime.

  4. Ammonia transformations and abundance of ammonia oxidizers in a clay soil underlying a manure pond.

    Science.gov (United States)

    Sher, Yonatan; Baram, Shahar; Dahan, Ofer; Ronen, Zeev; Nejidat, Ali

    2012-07-01

    Unlined manure ponds are constructed on clay soil worldwide to manage farm waste. Seepage of ammonia-rich liquor into underlying soil layers contributes to groundwater contamination by nitrate. To identify the possible processes that lead to the production of nitrate from ammonia in this oxygen-limited environment, we studied the diversity and abundance of ammonia-transforming microorganisms under an unlined manure pond. The numbers of ammonia-oxidizing bacteria and anammox bacteria were most abundant in the top of the soil profile and decreased significantly with depth (0.5 m), correlating with soil pore-water ammonia concentrations and soil ammonia concentrations, respectively. On the other hand, the numbers of ammonia-oxidizing archaea were relatively constant throughout the soil profile (10(7) amoA copies per g(soil)). Nitrite-oxidizing bacteria were detected mainly in the top 0.2 m. The results suggest that nitrate accumulation in the vadose zone under the manure pond could be the result of complete aerobic nitrification (ammonia oxidation to nitrate) and could exist as a byproduct of anammox activity. While the majority of the nitrogen was removed within the 0.5-m soil section, possibly by combined anammox and heterotrophic denitrification, a fraction of the produced nitrate leached into the groundwater.

  5. Thiourea-treated graphene aerogel as a highly selective gas sensor for sensing of trace level of ammonia.

    Science.gov (United States)

    Alizadeh, Taher; Ahmadian, Farzaneh

    2015-10-15

    As a result of this study, a new and simple method was proposed for the fabrication of an ultra sensitive, robust and reversible ammonia gas sensor. The sensing mechanism was based upon the change in electrical resistance of a graphene aerogel as a result of sensor exposing to ammonia. Three-dimensional graphene hydrogel was first synthesized via hydrothermal method in the absence or presence of various amounts of thiourea. The obtained material was heated to obtain aerogel and then it was used as ammonia gas sensor. The materials obtained were characterized using different techniques such as Fourier transform infra red spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thiourea-treated graphene aerogel was more porous (389 m(2) g(-1)) and thermally unstable and exhibited higher sensitivity, shorter response time and better selectivity toward ammonia gas, compared to the aerogel produced in the absence of thiourea. Thiourea amount, involved in the hydrogel synthesis step, was found to be highly effective factor in the sensing properties of finally obtained aerogel. The sensor response time to ammonia was short (100 s) and completely reversible (recovery time of about 500 s) in ambient temperature. The sensor response to ammonia was linear between 0.02 and 85 ppm and its detection limit was found to be 10 ppb (3S/N).

  6. Experimental study on effect of inclination angles to ammonia pulsating heat pipe

    Institute of Scientific and Technical Information of China (English)

    Xue Zhihu; Qu Wei

    2014-01-01

    In this paper, a novel study on performance of closed loop pulsating heat pipe (CLPHP) using ammonia as working fluid is experimented. The tested CLPHP, consisting of six turns, is fully made of quartz glass tubes with 6 mm outer diameter and 2 mm inner diameter. The filling ratio is 50%. The visualization investigation is conducted to observe the oscillation and circulation flow in the CLPHP. In order to investigate the effects of inclination angles to thermal performance in the ammonia CLPHP, four case tests are studied. The trends of temperature fluctuation and thermal resistance as the input power increases at different inclination angles are highlighted. The results show that it is very easy to start up and circulate for the ammonia CLPHP at an inclining angle. The thermal resistance is low to 0.02 K/W, presenting that heat fluxes can be transferred from heating section to cooling section very quickly. It is found that the thermal resistance decreases as the inclination angle increases. At the horizontal operation, the ammonia CLPHP can be easy to start up at low input power, but hard to circulate. In this case, once the input power is high, the capillary tube in heating section will be burnt out, leading to worse thermal performance with high thermal resistance.

  7. Mechanisms of Na+ uptake, ammonia excretion, and their potential linkage in native Rio Negro tetras (Paracheirodon axelrodi, Hemigrammus rhodostomus, and Moenkhausia diktyota).

    Science.gov (United States)

    Wood, Chris M; Robertson, Lisa M; Johannsson, Ora E; Val, Adalberto Luis

    2014-10-01

    Mechanisms of Na(+) uptake, ammonia excretion, and their potential linkage were investigated in three characids (cardinal, hemigrammus, moenkhausia tetras), using radiotracer flux techniques to study the unidirectional influx (J in), efflux (J out), and net flux rates (J net) of Na(+) and Cl(-), and the net excretion rate of ammonia (J Amm). The fish were collected directly from the Rio Negro, and studied in their native "blackwater" which is acidic (pH 4.5), ion-poor (Na(+), Cl(-) ~20 µM), and rich in dissolved organic matter (DOM 11.5 mg C l(-1)). J in (Na) , J in (Cl) , and J Amm were higher than in previous reports on tetras obtained from the North America aquarium trade and/or studied in low DOM water. In all three species, J in (Na) was unaffected by amiloride (10(-4) M, NHE and Na(+) channel blocker), but both J in (Na) and J in (Cl) were virtually eliminated (85-99 % blockade) by AgNO3 (10(-7) M). A time course study on cardinal tetras demonstrated that J in (Na) blockade by AgNO3 was very rapid (<5 min), suggesting inhibition of branchial carbonic anhydrase (CA), and exposure to the CA-blocker acetazolamide (10(-4) M) caused a 50 % reduction in J in (Na) .. Additionally, J in (Na) was unaffected by phenamil (10(-5) M, Na(+) channel blocker), bumetanide (10(-4) M, NKCC blocker), hydrochlorothiazide (5 × 10(-3) M, NCC blocker), and exposure to an acute 3 unit increase in water pH. None of these treatments, including partial or complete elimination of J in (Na) (by acetazolamide and AgNO3 respectively), had any inhibitory effect on J Amm. Therefore, Na(+) uptake in Rio Negro tetras depends on an internal supply of H(+) from CA, but does not fit any of the currently accepted H(+)-dependent models (NHE, Na(+) channel/V-type H(+)-ATPase), or co-transport schemes (NCC, NKCC), and ammonia excretion does not fit the current "Na(+)/NH4 (+) exchange metabolon" paradigm. Na(+), K(+)-ATPase and V-type H(+)-ATPase activities were present at similar

  8. Phase behaviour and thermoelastic properties of ammonia hydrate and ice polymorphs from 0 - 2 GPa

    Science.gov (United States)

    Fortes, A. D.; Wood, I. G.; Vocadlo, L.

    2008-12-01

    growth kinetics of the high-pressure ammonia dihydrate, ammonia monohydrate and ice polymorphs obtained from our data.

  9. The effect of outside conditions on anaerobic ammonia oxidation reaction

    Institute of Scientific and Technical Information of China (English)

    YANG Min; WANG Shu-bo

    2016-01-01

    Organic carbon, inorganic carbon, temperature, pH and ORP are all to have a certain influence on the anaerobic ammonia oxidation reaction. We can draw some conclusions on the optimum conditions of anaerobic ammonia oxidation reaction. The optimum temperature of the anaerobic ammonia oxidation reaction is 30-35℃. And the optimum pH of the anaerobic ammonia reaction is 7.5-8.3. The presence of organic matters can affect the anaerobic ammonia reaction, and different organic matters have different influence on it. The concentration of the inorganic carbon also exist great influence on the reaction. High inorganic carbon concentration also can inhibit anaerobic ammonia oxidation reaction.

  10. Ammonia synthesis over multi-promoted iron catalysts obtained by high-energy ball-milling

    DEFF Research Database (Denmark)

    Jacobsen, C.J.H.; Jiang, Jianzhong; Mørup, Steen;

    1999-01-01

    , ball-milling of fused oxidic KM1 precursor is seen to give rise to more homogeneous promoter distribution and slightly higher activity. The quite small activity increase observed in this case probably reflects the fact that the fusion process has already resulted in a close to optimal promoter...

  11. Ammonia-based intermittent aeration control optimized for efficient nitrogen removal.

    Science.gov (United States)

    Regmi, Pusker; Bunce, Ryder; Miller, Mark W; Park, Hongkeun; Chandran, Kartik; Wett, Bernhard; Murthy, Sudhir; Bott, Charles B

    2015-10-01

    This work describes the development of an intermittently aerated pilot-scale process (V = 0.45 m(3) ) operated for optimized efficient nitrogen removal in terms of volume, supplemental carbon and alkalinity requirements. The intermittent aeration pattern was controlled using a strategy based on effluent ammonia concentration set-points. The unique feature of the ammonia-based aeration control was that a fixed dissolved oxygen (DO) set-point was used and the length of the aerobic and anoxic time (anoxic time ≥25% of total cycle time) were changed based on the effluent ammonia concentration. Unlike continuously aerated ammonia-based aeration control strategies, this approach offered control over the aerobic solids retention time (SRT) to deal with fluctuating ammonia loading without solely relying on changes to the total SRT. This approach allowed the system to be operated at a total SRT with a small safety factor. The benefits of operating at an aggressive SRT were reduced hydraulic retention time (HRT) for nitrogen removal. As a result of such an operation, nitrite oxidizing bacteria (NOB) out-selection was also obtained (ammonia oxidizing bacteria [AOB] maximum activity: 400 ± 79 mgN/L/d, NOB maximum activity: 257 ± 133 mgN/L/d, P ammonia (COD/NH4 (+) -N) ratio of 10.2 ± 2.2 at 25°C within the hydraulic retention time (HRT) of 4 h and within a total SRT of 5-10 days. The TIN removal efficiency up to 91% was observed during the study, while effluent TIN was 9.6 ± 4.4 mgN/L. Therefore, this pilot-scale study demonstrates that application of the proposed on-line aeration control is capable of relatively high nitrogen removal without supplemental carbon and alkalinity addition at a low HRT.

  12. Enrichment of high ammonia tolerant methanogenic culture

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Karakashev, Dimitar Borisov; Proietti, Nicolas;

    of the current study was to isolate and identify methanogenic cultures tolerant to high ammonia concentrations. A mixed methanogenic population was stepwise exposed to ammonia concentrations (1 to 9.26 g NH4+-N L-1) during an enrichment process with successive batch cultivations. The methanogenic population...... was derived from a full scale biogas reactor (Hashøj, Denmark), fed with 75% animal manure and 25% food industries organic waste. Basal anaerobic medium was used for the enrichment along with sodium acetate (1 g HAc L-1) as a carbon source. Fluorescence insitu hybridization (FISH) was used to determine...... microbial community composition. The outcome of the enrichment process was a mesophilic aceticlastic methanogenic enriched culture able to withstand high ammonia loads and utilize acetate and form methane stoichiometrically. FISH analysis showed that the methanogens of the enriched culture belonged...

  13. Effect of dietary protein restriction on renal ammonia metabolism.

    Science.gov (United States)

    Lee, Hyun-Wook; Osis, Gunars; Handlogten, Mary E; Guo, Hui; Verlander, Jill W; Weiner, I David

    2015-06-15

    Dietary protein restriction has multiple benefits in kidney disease. Because protein intake is a major determinant of endogenous acid production, it is important that net acid excretion change in parallel during protein restriction. Ammonia is the primary component of net acid excretion, and inappropriate ammonia excretion can lead to negative nitrogen balance. Accordingly, we examined ammonia excretion in response to protein restriction and then we determined the molecular mechanism of the changes observed. Wild-type C57Bl/6 mice fed a 20% protein diet and then changed to 6% protein developed an 85% reduction in ammonia excretion within 2 days, which persisted during a 10-day study. The expression of multiple proteins involved in renal ammonia metabolism was altered, including the ammonia-generating enzymes phosphate-dependent glutaminase (PDG) and phosphoenolpyruvate carboxykinase (PEPCK) and the ammonia-metabolizing enzyme glutamine synthetase. Rhbg, an ammonia transporter, increased in expression in the inner stripe of outer medullary collecting duct intercalated cell (OMCDis-IC). However, collecting duct-specific Rhbg deletion did not alter the response to protein restriction. Rhcg deletion did not alter ammonia excretion in response to dietary protein restriction. These results indicate 1) dietary protein restriction decreases renal ammonia excretion through coordinated regulation of multiple components of ammonia metabolism; 2) increased Rhbg expression in the OMCDis-IC may indicate a biological role in addition to ammonia transport; and 3) Rhcg expression is not necessary to decrease ammonia excretion during dietary protein restriction. PMID:25925252

  14. Ammonia emission time profiles based on manure transport data improve ammonia modelling across north western Europe

    Science.gov (United States)

    Hendriks, C.; Kranenburg, R.; Kuenen, J. J. P.; Van den Bril, B.; Verguts, V.; Schaap, M.

    2016-04-01

    Accurate modelling of mitigation measures for nitrogen deposition and secondary inorganic aerosol (SIA) episodes requires a detailed representation of emission patterns from agriculture. In this study the meteorological influence on the temporal variability of ammonia emissions from livestock housing and application of manure and fertilizer are included in the chemistry transport model LOTOS-EUROS. For manure application, manure transport data from Flanders (Belgium) were used as a proxy to derive the emission variability. Using improved ammonia emission variability strongly improves model performance for ammonia, mainly by a better representation of the spring maximum. The impact on model performance for SIA was negligible as explained by the limited, ammonia rich region in which the emission variability was updated. The contribution of Flemish agriculture to modelled annual mean ammonia and SIA concentrations in Flanders were quantified at respectively 7-8 and 1-2 μg/m3. A scenario study was performed to investigate the effects of reducing ammonia emissions from manure application during PM episodes by 75%, yielding a maximum reduction in modelled SIA levels of 1-3 μg/m3 during episodes. Year-to-year emission variability and a soil module to explicitly model the emission process from manure and fertilizer application are needed to further improve the modelling of the ammonia budget.

  15. Chemical deactivation of Cu-SSZ-13 ammonia selective catalytic reduction (NH3-SCR) systems

    NARCIS (Netherlands)

    Lezcano-Gonzalez, I.; Deka, U.; van der Bij, H. E.; Paalanen, P.; Arstad, B.; Weckhuysen, B. M.; Beale, A. M.

    2014-01-01

    The chemical deactivation of Cu-SSZ-13 Ammonia Selective Catalytic Reduction (NH3-SCR) catalysts by Pt, Zn, Ca and P has been systematically investigated using a range of analytical techniques in order to study the influence on both the zeolitic framework and the active Cu2+ ions. The results obtain

  16. Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

    DEFF Research Database (Denmark)

    Bialy, Agata; Jensen, Peter Bjerre; Blanchard, Didier;

    2015-01-01

    with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained...

  17. Transformation of ammonia i biological airfilters

    DEFF Research Database (Denmark)

    Nielsen, Lars Peter; Sørensen, Karen; Andersen, Mathias;

    2007-01-01

    Ammonia is a major compound in ventilation air from animal houses. In biological filters it is with varying efficiency transformed by physical, biological, and chemical processes and ends up as ammonium, nitrate, and nitrite dissolved in water and as dinitrogen, nitrous oxide and nitric oxide emi...... removal without too much energy consumption, waste water production, green house gas emission, or suppression of the filters odor removal efficiency.......Ammonia is a major compound in ventilation air from animal houses. In biological filters it is with varying efficiency transformed by physical, biological, and chemical processes and ends up as ammonium, nitrate, and nitrite dissolved in water and as dinitrogen, nitrous oxide and nitric oxide...

  18. Aqueous Ammonia soaking of digested manure fibers

    DEFF Research Database (Denmark)

    Mirtsou-Xanthopoulou, Chrysoula; Jurado, Esperanza; Skiadas, Ioannis;

    2012-01-01

    -scale anaerobic digester to enhance their methane productivity. Soaking in six different reagent concentrations in ammonia (5%, 10%, 15%, 20%, 25%, 32%) was applied for 3 days at 22°C. An overall methane yield increase from 85% to 110% was achieved compared to controls (digested manure fibers where AAS...... in methane yield as the highest concentrations tested; it is anticipated that this will result to an even lower cost for recovery and recycling of ammonia in full-scale. Moreover, the effect of 1, 3, and 5 days AAS treatment on methane production from digested fibers was investigated with 5 and 25% w...

  19. Structure of Ramie Treated by Liquid Ammonia

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The morphology and supermolecular structures of the scoured/bleached ramie and scoured/bleached/liquid ammonia treated ramie were studied by means of scanning electron microscope, X-ray diffractometer, reverse gel permeation chromatography, etc. The results indicate that liquid ammonia treatment of the scoured/bleached ramie leads to a smoother surface, a lower crystallinity, partial crystal transformation from cellulose Ⅰ to cellulose Ⅲ, a decrease in the volume and cumulative surface area of the larger micropores and an increase in those of the smaller ones in the fiber.

  20. Chilled Ammonia Process for CO2 Capture

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; Thomsen, Kaj; Well, Willy J.M. van;

    2010-01-01

    The chilled ammonia process absorbs the CO2 at low temperature (2–10°C). The heat of absorption of carbon dioxide by ammonia is significantly lower than for amines. In addition, degradation problems can be avoided and a high carbon dioxide capacity is achieved. Hence, this process shows good...... and pressure up to 100bars. The results show that solid phases consisting of ammonium carbonate and bicarbonate are formed in the absorber. The heat requirements in the absorber and in the desorber have been studied. The enthalpy calculations show that a heat requirement for the desorber lower than 2GJ/ton CO2...

  1. Chilled ammonia process for CO2 capture

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; Thomsen, Kaj; van Well, Willy J. M;

    2009-01-01

    The chilled ammonia process absorbs the CO2 at low temperature (2-10 degrees C). The heat of absorption of carbon dioxide by ammonia is significantly lower than for amines. In addition, degradation problems can be avoided and a high carbon dioxide capacity is achieved. Hence, this process shows...... C and pressure up to 100 bars [1]. The results show that solid phases consisting of ammonium carbonate and bicarbonate are formed in the absorber. The energy requirements in the absorber and in the desorber have been studied. The enthalpy calculations show that an energy requirement for the desorber...

  2. Electrochemical ammonia production on molybdenum nitride nanoclusters

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2013-01-01

    Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...... energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen...

  3. Imaging of the umbrella motion and tunneling in the ammonia molecule by strong-field ionization

    CERN Document Server

    Förster, Johann; Magana, Alvaro; Saenz, Alejandro

    2016-01-01

    The geometry-dependent ionization behavior of the ammonia molecule is investigated. Different theoretical approaches for obtaining the ionization yield are compared, all of them showing a strong dependence of the ionization yield on the inversion coordinate at long wavelengths ($\\geq$ 800 nm). It is shown how this effect can be exploited to create and probe nuclear wave packets in neutral ammonia using Lochfra{\\ss}. Furthermore, imaging of a wave packet tunneling through the barrier of a double-well potential in real time is discussed.

  4. Electrospun Nanofibers from a Tricyanofuran-Based Molecular Switch for Colorimetric Recognition of Ammonia Gas.

    Science.gov (United States)

    Khattab, Tawfik A; Abdelmoez, Sherif; Klapötke, Thomas M

    2016-03-14

    A chromophore based on tricyanofuran (TCF) with a hydrazone (H) recognition moiety was developed. Its molecular-switching performance is reversible and has differential sensitivity towards aqueous ammonia at comparable concentrations. Nanofibers were fabricated from the TCF-H chromophore by electrospinning. The film fabricated from these nanofibers functions as a solid-state optical chemosensor for probing ammonia vapor. Recognition of ammonia vapor occurs by proton transfer from the hydrazone fragment of the chromophore to the ammonia nitrogen atom and is facilitated by the strongly electron withdrawing TCF fragment. The TCF-H chromophore was added to a solution of poly(acrylic acid), which was electrospun to obtain a nanofibrous sensor device. The morphology of the nanofibrous sensor was determined by SEM, which showed that nanofibers with a diameter range of 200-450 nm formed a nonwoven mat. The resultant nanofibrous sensor showed very good sensitivity in ammonia-vapor detection. Furthermore, very good reversibility and short response time were also observed.

  5. Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

    DEFF Research Database (Denmark)

    Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

    2015-01-01

    Ammonia-rich substrates can cause inhibition on anaerobic digestion process. Syntrophic acetate oxidizing bacteria (SAOB) and hydrogenotrophic methanogens are important for the ammonia inhibitory mechanism on anaerobic digestion. The roles and interactions of SAOB and hydrogenotrophic methanogens...

  6. The structure of polaronic electron cavities in lithium-ammonia solutions

    International Nuclear Information System (INIS)

    Neutron diffraction has been used in conjunction with isotopic substitution of deuterium for hydrogen to study the structure of lithium-ammonia solutions, at concentrations spanning the metal-nonmetal transition. Detailed analysis and visualization of our experimental data has been carried out via iterative refinement of a three-dimensional molecular model, allowing us to obtain unique insight into the formation of polaronic electron cavities in the solutions. At low electron concentrations the solutions are nonmetallic, and the ammonia molecules are orientated around cavity centres to form Bjerrum-type defects. As the electron content is increased, the solutions become metallic, and we find evidence of percolation channels through the solvent. The dissociated electrons therefore play an active role in determining the structure of these solutions, and serve to disrupt the hydrogen bonding present in liquid ammonia

  7. Recovery of ammonia and sulfate from waste streams and bioenergy production via bipolar bioelectrodialysis

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2015-01-01

    to recover ammonia and sulfate from waste streams and thereby counteracting their toxicity during anaerobic digestion. Furthermore, hydrogen production and wastewater treatment were also accomplished. At an applied voltage of 1.2 V, nitrogen and sulfate fluxes of 5.1 g View the MathML sourceNH4+-N/m2/d......Ammonia and sulfate, which are prevalent pollutants in agricultural and industrial wastewaters, can cause serious inhibition in several biological treatment processes, such as anaerobic digestion. In this study, a novel bioelectrochemical approach termed bipolar bioelectrodialysis was developed...... bioelectrodialysis was successfully demonstrated with cattle manure. The results provide new possibilities for development of cost-effective technologies, capable of waste resources recovery and renewable energy production....

  8. Ammonia production, excretion, toxicity, and defense in fish: A Review

    Directory of Open Access Journals (Sweden)

    Alex Y K Ip

    2010-10-01

    Full Text Available Many fishes are ammonotelic but some species can detoxify ammonia to glutamine or urea. Certain fish species can accumulate high levels of ammonia in the brain or defense against ammonia toxicity by enhancing the effectiveness of ammonia excretion through active NH4+ transport, manipulation of ambient pH, or reduction in ammonia permeability through the branchial and cutaneous epithelia. Recent reports on ammonia toxicity in mammalian brain reveal the importance of permeation of ammonia through the blood-brain barrier and passages of ammonia and water through transporters in the plasmalemma of brain cells. Additionally, brain ammonia toxicity could be related to the passage of glutamine through the mitochondrial membranes into the mitochondrial matrix. On the other hand, recent reports on ammonia excretion in fish confirm the involvement of Rhesus glycoproteins in the branchial and cutaneous epithelia. Therefore, this review focuses on both the earlier literature and the up-to-date information on the problems and mechanisms concerning the permeation of ammonia, as NH3, NH4+ or proton-neutral nitrogenous compounds, across mitochondrial membranes, the blood-brain barrier, the plasmalemma of neurons, and the branchial and cutaneous epithelia of fish. It also addresses how certain fishes with high ammonia tolerance defend against ammonia toxicity through the regulation of the permeation of ammonia and related nitrogenous compounds through various types of membranes. It is hoped that this review would revive the interests in investigations on the passage of ammonia through the mitochondrial membranes and the blood-brain barrier of ammonotelic fishes and fishes with high brain ammonia-tolerance, respectively.

  9. Modelling of ammonia emissions from dairy cow houses

    OpenAIRE

    Monteny, G.J.

    2000-01-01

    Dairy cow husbandry contributes to environmental acidification through the emission of ammonia. In-depth knowledge on the processes and variable factors that play a role in the emission of ammonia from dairy cow houses benefits the production of emission data, the development of low emission housing systems, and evaluation of emission levels in a farming system approach. A mechanistic simulation model for the ammonia emission from dairy cow houses was developed to facilitate this.An ammonia p...

  10. Detection of Ammonia in Liquids Using Millimeter Wave Spectroscopy

    Directory of Open Access Journals (Sweden)

    Hilmi Ozturk

    2012-01-01

    Full Text Available Detection of ammonia plays a vital role for counter-bioterrorism applications. Using millimeter wave absorption measurements, ammonia dissolved in water solution is analyzed and compared to water-only solution. The inversion of ammonia molecule results in split rotational spectral lines and transitions of these lines can be detected. Two-port measurements were carried out with vector network analyzer and measurements revealed that ammonia presence can be identified, especially between 30–35 GHz.

  11. Implementação computacional do modelo carga-fluxo de carga-fluxo de dipolo para cálculo e interpretação das intensidades do espectro infravermelho Computational implementation of the model charge-charge flux-dipole flux for calculation and analysis of infrared intensities

    Directory of Open Access Journals (Sweden)

    Thiago C. F. Gomes

    2008-01-01

    Full Text Available The first computational implementation that automates the procedures involved in the calculation of infrared intensities using the charge-charge flux-dipole flux model is presented. The atomic charges and dipoles from the Quantum Theory of Atoms in Molecules (QTAIM model was programmed for Morphy98, Gaussian98 and Gaussian03 programs outputs, but for the ChelpG parameters only the Gaussian programs are supported. Results of illustrative but new calculations for the water, ammonia and methane molecules at the MP2/6-311++G(3d,3p theoretical level, using the ChelpG and QTAIM/Morphy charges and dipoles are presented. These results showed excellent agreement with analytical results obtained directly at the MP2/6-311++G(3d,3p level of theory.

  12. Eutrophication in the northern Adriatic Sea: Benthic fluxes and nutrient budgets

    Energy Technology Data Exchange (ETDEWEB)

    Berelson, W.M.; Hammond, D.E. (Univ. of Southern California, Los Angeles (United States)); Giordani, P. (Inst. di Geologia Marina-CNR, Bologna (Italy))

    1990-01-09

    The northern Adriatic Sea has been plagued by problems of eutrophication. This area is relatively shallow (maximum depth = 60m), becoming stratified during the summer months which inhibits oxygen transport to bottom waters. Anthropogenic nutrient loading in rivers entering the northern Adriatic has increased nutrient input to this system and stimulated algai growth. Five stations in the western Adriatic (south of the Po River Delta) were occupied during September, 1988 and benthic flux chambers used to measure nutrient fluxes. These sites included 3 stations previously studied in 1982. Flux measurements of dissolved silica, nitrate, oxygen, ammonia, phosphate, CO[sub 2], alkalinity and radon were made during 24 hour incubations of flux chambers (area covered - 0.07 m[sup 2], volume = [approximately]81) that were continuously stirred and sampled periodically. Nutrient fluxes measured were generally consistent with the fluxes measured previously in June, 1982 except for radon fluxes which were 203 times greater in the earlier field season. There was a general trend in nutrient fluxes to decrease offshore, a pattern probably controlled by the sedimentation patterns because fine grained, organic matter-rich sediment are concentrated in a zone near shore. Average regional fluxes were (in mmol m[sup -2]d[sup -1], negative values indicate flux into sediment): Oxygen (-12), CO[sub 2] (19), Alkalinity (4), Silica (3.3), Ammonia (1.5), Phosphate (0.1) and Nitrate (0.3). The carbon/ammonia flux ratio is about twice the C/N ratio in marine phytoplankton, suggesting that large amounts of denitrification may be occuring in these sediments. Comparisons of benthic fluxes and sediment burial rates indicate that 50-90% of the carbon, silica, phosphorus and nitrogen arriving at the sediment-water interface is recycled before burial. The nutrient input to the water column from NW Adriatic sediments is about equal to the input from coastal rivers.

  13. Community Structure of Ammonia-Oxidizing Archaea and Ammonia-Oxidizing Bacteria in Soil Treated with the Insecticide Imidacloprid

    Directory of Open Access Journals (Sweden)

    Mariusz Cycoń

    2015-01-01

    Full Text Available The purpose of this experiment was to assess the effect of imidacloprid on the community structure of ammonia-oxidizing archaea (AOA and ammonia-oxidizing bacteria (AOB in soil using the denaturing gradient gel electrophoresis (DGGE approach. Analysis showed that AOA and AOB community members were affected by the insecticide treatment. However, the calculation of the richness (S and the Shannon-Wiener index (H values for soil treated with the field rate (FR dosage of imidacloprid (1 mg/kg soil showed no changes in measured indices for the AOA and AOB community members. In turn, the 10*FR dosage of insecticide (10 mg/kg soil negatively affected the AOA community, which was confirmed by the decrease of the S and H values in comparison with the values obtained for the control soil. In the case of AOB community, an initial decline followed by the increase of the S and H values was obtained. Imidacloprid decreased the nitrification rate while the ammonification process was stimulated by the addition of imidacloprid. Changes in the community structure of AOA and AOB could be due to an increase in the concentration of N-NH4+, known as the most important factor which determines the contribution of these microorganisms to soil nitrification.

  14. A Stability Study of Ni/Yttria-Stabilized Zirconia Anode for Direct Ammonia Solid Oxide Fuel Cells.

    Science.gov (United States)

    Yang, Jun; Molouk, Ahmed Fathi Salem; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

    2015-12-30

    In recent years, solid oxide fuel cells fueled with ammonia have been attracting intensive attention. In this work, ammonia fuel was supplied to the Ni/yttria-stabilized zirconia (YSZ) cermet anode at 600 and 700 °C, and the change of electrochemical performance and microstructure under the open-circuit state was studied in detail. The influence of ammonia exposure on the microstructure of Ni was also investigated by using Ni/YSZ powder and Ni film deposited on a YSZ disk. The obtained results demonstrated that Ni in the cermet anode was partially nitrided under an ammonia atmosphere, which considerably roughened the Ni surface. Moreover, the destruction of the anode support layer was confirmed for the anode-supported cell upon the temperature cycling test between 600 and 700 °C because of the nitriding phenomenon of Ni, resulting in severe performance degradation.

  15. Respiratory morbidity due to ammonia exposure among the employees of a urea manufacturing industry located in western part of India

    Directory of Open Access Journals (Sweden)

    Naman Zala

    2012-01-01

    Full Text Available Ammonia is produced in the fertilizer industry. The amount of ammonia inhaled by employees of a urea manufacturing industry is very high. It would be interesting to study whether such an amount has any impact on the employees working there for many years. This study explores the magnitude of respiratory morbidity among employees of a urea manufacturing industry and to establish its association with exposure to ammonia. Data was collected related to significant respiratory illnesses of all the employees over a period of 10 years using computer-based medical record system of the industry′s hospital. The results obtained from the data analysis showed that there is no cause and effect relationship between exposure to ammonia and respiratory morbidity. Thus it was advised to the medical authority at industry to go for mass treatment with anthelmintics and that all the employees should be screened for specific allergens and this information should be used while managing respiratory morbidity.

  16. Nitrite as a stimulus for ammonia-starved Nitrosomonas europaea

    NARCIS (Netherlands)

    Laanbroek, H.J.; Bär-Gilissen, M.J.; Hoogveld, H.L.

    2002-01-01

    Ammonia-starved cells of Nitrosomonas europaea are able to preserve a high level of ammonia-oxidizing activity in the absence of ammonium. However, when the nitrite-oxidizing cells that form part of the natural nitrifying community do not keep pace with the ammonia-oxidizing cells, nitrite accumulat

  17. Werkwijze voor het behandelen van ammonia-houdend afvalwater

    NARCIS (Netherlands)

    Loosdrecht, M.C.M.; Jetten, M.S.M.

    1998-01-01

    Treatment of ammonia-comprising waste water comprises: (a) subjecting the waste water to a nitrification treatment using a nitrifying microorganism and adding oxygen, to give a solution comprising an oxidation product of ammonia, and (b) converting the oxidation product of ammonia into nitrogen usin

  18. Innovative bioelectrochemical-anaerobic-digestion integrated system for ammonia recovery and bioenergy production from ammonia-rich residues

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2015-01-01

    (SMRC) and a continuous stirred tank reactor (CSTR), to prevent ammonia toxicity during anaerobic digestion by in-situ ammonia recovery and electricity production (Figure 1). In batch experiment, the ammonia concentration in the CSTR decreased from 6 to 0.7 g-N/L with an average recovery rate of 0.18 g-N/L(CSTR...... performance was enhanced. In addition, the coexistence of other cations in CSTR or cathode had no negative effect on the ammonia transportation. In continuous reactor operation, 112% extra biogas production was achieved due to ammonia recovery. High-throughput molecular sequencing analysis showed an impact...... of ammonia recovery on the microbial community composition in the integrated system. Results clearly indicate the great potential of the SMRC-CSTR-coupled system for efficient and cost-effective ammonia recovery, energy production and treatment of ammonia-rich residues....

  19. Controlling factors of biosphere-atmosphere ammonia exchange at a semi-natural peatland site

    Science.gov (United States)

    Brummer, C.; Richter, U.; Smith, J. J.; Delorme, J. P.; Kutsch, W. L.

    2014-12-01

    Recent advancements in laser spectrometry offer new opportunities to investigate net biosphere-atmosphere exchange of ammonia. During a three month field campaign from February to May 2014, we tested the performance of a quantum cascade laser within an eddy-covariance setup. The laser was operated at a semi-natural peatland site that is surrounded by highly fertilized agricultural land and intensive livestock production (~1 km distance). Ammonia concentrations were highly variable between 2 and almost 100 ppb with an average value of 15 ppb. Different concentration patterns could be identified. The variability was closely linked to the timing of management practices and the prevailing local climate, particularly wind direction, temperature and surface wetness with the latter indicating higher non-stomatal uptake under wet conditions leading to decreased concentrations. Average ammonia fluxes were around -15 ng N m-2 s-1 at the beginning of the campaign in February and shifted towards a neutral average exchange regime of -1 to 0 ng N m-2 s-1 in April and May. Intriguingly, during the time of decreasing ammonia uptake, concentrations were considerably rising, which clearly indicated N saturation in the predominant vegetation such as bog heather, purple moor-grass, and cotton grass. The cumulative net uptake for the period of investigation was ~300 g N ha-1. This stresses the importance of a thorough method inter-comparison, e.g. with denuder systems in combination with dry deposition modeling. As previous results from the latter methods showed an annual uptake of ~9 kg N ha-1 for the same site, the implementation of adequate ammonia compensation point parameterizations become crucial in surface-atmosphere exchange schemes for bog vegetation. Through their high temporal resolution, robustness and continuous measurement mode, quantum cascade lasers will help assessing the effects of atmospheric N loads to vulnerable N-limited ecosystems such as peatlands.

  20. Saccharification of newspaper waste after ammonia fiber expansion or extractive ammonia.

    Science.gov (United States)

    Montella, Salvatore; Balan, Venkatesh; da Costa Sousa, Leonardo; Gunawan, Christa; Giacobbe, Simona; Pepe, Olimpia; Faraco, Vincenza

    2016-03-01

    The lignocellulosic fractions of municipal solid waste (MSW) can be used as renewable resources due to the widespread availability, predictable and low pricing and suitability for most conversion technologies. In particular, after the typical paper recycling loop, the newspaper waste (NW) could be further valorized as feedstock in biorefinering industry since it still contains up to 70 % polysaccharides. In this study, two different physicochemical methods-ammonia fiber expansion (AFEX) and extractive ammonia (EA) were tested for the pretraetment of NW. Furthermore, based on the previously demonstrated ability of the recombinant enzymes endocellulase rCelStrep, α-L-arabinofuranosidase rPoAbf and its evolved variant rPoAbf F435Y/Y446F to improve the saccharification of different lignocellulosic pretreated biomasses (such as corn stover and Arundo donax), in this study these enzymes were tested for the hydrolysis of pretreated NW, with the aim of valorizing the lignocellulosic fractions of the MSW. In particular, a mixture of purified enzymes containing cellulases, xylanases and accessory hemicellulases, was chosen as reference mix and rCelStrep and rPoAbf or its variant were replaced to EGI and Larb. The results showed that these enzymatic mixes are not suitable for the hydrolysis of NW after AFEX or EA pretreatment. On the other hand, when the enzymes rCelStrep, rPoAbf and rPoAbf F435Y/Y446F were tested for their effect in hydrolysis of pretreated NW by addition to a commercial enzyme mixture, it was shown that the total polysaccharides conversion yield reached 37.32 % for AFEX pretreated NW by adding rPoAbf to the mix whilst the maximum sugars conversion yield for EA pretreated NW was achieved 40.80 % by adding rCelStrep. The maximum glucan conversion yield obtained (45.61 % for EA pretreated NW by adding rCelStrep to the commercial mix) is higher than or comparable to those reported in recent manuscripts adopting hydrolysis conditions similar to those used

  1. The Recovery of Ammonia Nitrogen From Aluminum Slag Ashes%铝渣灰中氨氮的回收

    Institute of Scientific and Technical Information of China (English)

    周长祥; 王卿; 张文娟; 赵伟

    2012-01-01

    铝渣灰中的氮以AIN形式存在并与其它成分紧密混杂.进行了AIN水解、回收液氨及硫酸铵的试验研究.A1N水解产生的氨经精馏、压缩、冷凝可获得成品液氨,或者经工业硫酸吸收、结晶、离心烘干得到铵盐,氨氮回收率达95%.%Ammonia exists in form of nitrogen in aluminum slag ash and is closely mixed with other components. The tests of AIN hydrolysis and the recovery of liquid nitrogen and ammonia sulfate were conducted. From the ammonia produced in the hydrolysis of AIN, Liquid ammonia could be obtained by distillation, compression and condensation, while ammonia salt could be obtained by industrial sulphuric acid absorption, crystallization and centrifugal drying, the recovery of ammonia nitrogen could reach to 95%.

  2. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...... ammonia tolerant methanogen in a CSTR reactor could completely alleviate the ammonia inhibitory effect. Furthermore, it was found that bioaugmentation with the enriched culture resulted in 25% higher methane production compared to when the bioaugmentation was achieved with pure methanogenic strains....... The bioaugmentation was performed without pausing the continuous operation of the CSTR reactor and without excluding the ammonia-rich substrate from the feedstock. Thus, bioaugmentation with mixed methanogenic cultures could potentially support the development of an efficient and cost-effective biomethanation process...

  3. Treatment of nickel-ammonia complex ion-containing ammonia nitrogen wastewater

    Institute of Scientific and Technical Information of China (English)

    MIN Xiao-bo; ZHOU Min; CHAI Li-yuan; WANG Yun-yan; SHU Yu-de

    2009-01-01

    Air stripping was adopted to treat nickel ammonia complex ion-containing wastewater in order to remove nickel and ammonia simultaneously in one technological process. The relationship among pH, the concentration of nickel ammonia complex ion and total ammonia concentration was analyzed theoretically. Influence of pH value, water temperature, airflow rate and time on air stripping was studied in detail by static experiment in laboratory. The results show that at pH 11, temperature of 60 ℃ and airflow rate of 0.12 m~3/h, NH_3 and Ni~(2+) concentrations remained in wastewater are less than 2 and 0.2 mg/L, respectively, after blowing for 75 min, which reaches the standard of the state discharge. When the tail gas is absorbed by 0.5 mol/L H_2SO_4 in order to avoid the secondary pollution, the absorption rate can achieve 70%.

  4. USDA-EPA Collaborative Ammonia Research

    Science.gov (United States)

    In 2014, a work group was formed between USDA and EPA to facilitate information exchange on ammonia emissions from agriculture, air quality impacts and emission mitigation options and to identify opportunities for collaboration. This document provides background on the work grou...

  5. Adsorption of Ammonia on Regenerable Carbon Sorbents

    Science.gov (United States)

    Wójtowicz, Marek A.; Cosgrove, Jesph E.; Serio, Michael A..; Wilburn, Monique

    2015-01-01

    Results are presented on the development of reversible sorbents for the combined carbon dioxide, moisture, and trace-contaminant (TC) removal for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). The currently available life support systems use separate units for carbon dioxide, trace contaminants, and moisture control, and the long-term objective is to replace the above three modules with a single one. Data on sorption and desorption of ammonia, which is a major TC of concern, are presented in this paper. The current TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal, which is non-regenerable, and the carbon-based sorbent under development in this project can be regenerated by exposure to vacuum at room temperature. In this study, several carbon sorbents were fabricated and tested for ammonia sorption. Ammonia-sorption capacity was related to carbon pore structure characteristics, and the temperature of oxidative carbon-surface treatment was optimized for enhanced ammonia-sorption performance.

  6. Footprints on Ammonia Concentrations from Environmental Regulations

    DEFF Research Database (Denmark)

    Skjøth, Carsten Ambelas; Ellermann, Thomas; Hertel, Ole;

    2008-01-01

    Releases of ammonia (NH3) to the atmosphere contribute significantly to the desposition of nitrogen to both terrestrial and aquatic ecosystems. This is the background for the national NH3 emission ceilings in Europe. However, in some countries the national legislation aims not only to meet theese...

  7. Ammonia in comet P/Halley

    Science.gov (United States)

    Meier, R.; Eberhardt, P.; Krankowsky, D.; Hodges, R. R.

    1994-01-01

    In comet P/Halley the abundances of ammonia relative to water reported in the literature differ by about one order of magnitude from roughly 0.1% up to 2%. Different observational techniques seem to have inherent systematic errors. Using the ion mass channels m/q = 19 amu/e, 18 amu/e and 17 amu/e of the Neutral Mass Spectrometer experiment aboard the spacecraft Giotto, we derive a production rate of ammonia of (1.5(sub -0.7)(sup +0.5))% relative to water. Inside the contact surface we can explain our data by a nuclear source only. The uncertainty in our abundance of ammonia is primarily a result of uncertainties in some key reaction coefficients. We discuss in detail these reactions and the range of error indicated results from extreme assumptions in the rate coefficients. From our data, even in the worst case, we can exclude the ammonia abundance to be only of the order of a few per mill.

  8. A porous SiC ammonia sensor

    NARCIS (Netherlands)

    Connolly, E.J.; Timmer, B.H.; Pham, H.T.M.; Groeneweg, J.; Sarro, P.M.; Olthuis, W.; French, P.J.

    2005-01-01

    When used as the dielectric in a capacitive sensing arrangement, porous SiC has been found to be extremely sensitive to the presence of ammonia (NH3) gas. The exact sensing method is still not clear, but NH3 levels as low as 0.5 ppm could be detected. We report the fabrication and preliminary charac

  9. A process-based model for ammonia emission from urine patches, GAG (Generation of Ammonia from Grazing): description and sensitivity analysis

    Science.gov (United States)

    Móring, Andrea; Vieno, Massimo; Doherty, Ruth M.; Laubach, Johannes; Taghizadeh-Toosi, Arezoo; Sutton, Mark A.

    2016-03-01

    In this paper a new process-based, weather-driven model for ammonia (NH3) emission from a urine patch has been developed and its sensitivity to various factors assessed. The GAG model (Generation of Ammonia from Grazing) is capable of simulating the TAN (total ammoniacal nitrogen) and the water content of the soil under a urine patch and also soil pH dynamics. The model tests suggest that ammonia volatilization from a urine patch can be affected by the possible restart of urea hydrolysis after a rain event as well as CO2 emission from the soil. The vital role of temperature in NH3 exchange is supported by our model results; however, the GAG model provides only a modest overall temperature dependence in total NH3 emission compared with the literature. This, according to our findings, can be explained by the higher sensitivity to temperature close to urine application than in the later stages and may depend on interactions with other nitrogen cycling processes. In addition, we found that wind speed and relative humidity are also significant influencing factors. Considering that all the input parameters can be obtained for larger scales, GAG is potentially suitable for field and regional scale application, serving as a tool for further investigation of the effects of climate change on ammonia emissions and deposition.

  10. Decomposition of indoor ammonia with TiO 2-loaded cotton woven fabrics prepared by different textile finishing methods

    Science.gov (United States)

    Dong, Yongchun; Bai, Zhipeng; Liu, Ruihua; Zhu, Tan

    Addition of urea-based antifreeze admixtures during cement mixing in construction of buildings has led to increasing indoor air pollution due to continuous transformation and emission of urea to gaseous ammonia in indoor concrete wall. In order to control ammonia pollution from indoor concrete wall, the aqueous dispersion was firstly prepared with nano-scale TiO 2 photocatalysts and dispersing agent, and then mixed with some textile additives to establish a treating bath or coating paste. Cotton woven fabrics were used as the support materials owing to their large surface area and large number of hydrophilic groups on their cellulose molecules and finished using padding and coating methods, respectively. Two TiO 2-loaded fabrics were obtained and characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). Moreover, a specifically designed ammonia photocatalytic system consisting of a small environmental chamber and a reactor was used for assessing the performance of these TiO 2-loaded fabrics as the wall cloth or curtains used in house rooms in the future and some factors affecting ammonia decomposition are discussed. Furthermore, a design equation of surface catalytic kinetics was developed for describing the decomposition of ammonia in air stream. The results indicated that increasing dosage of the TiO 2 aqueous dispersion in treating bath or coating paste improved the ammonia decomposition. And ammonia was effectively removed at low ammonia concentration or gas flow rate. When relative humidity level was 45%, ammonia decomposition was remarkably enhanced. It is the fact that ammonia could be significantly decomposed in the presence of the TiO 2-padded cotton fabric. Whereas, the TiO 2-coated cotton fabric had the reduced photocatalytic decomposition of ammonia and high adsorption to ammonia owing to their acrylic binder layer. Finally, the reaction rate constant k and the adsorption equilibrium constant K values were determined through a

  11. Optimal flux patterns in cellular metabolic networks

    Energy Technology Data Exchange (ETDEWEB)

    Almaas, E

    2007-01-20

    The availability of whole-cell level metabolic networks of high quality has made it possible to develop a predictive understanding of bacterial metabolism. Using the optimization framework of flux balance analysis, I investigate metabolic response and activity patterns to variations in the availability of nutrient and chemical factors such as oxygen and ammonia by simulating 30,000 random cellular environments. The distribution of reaction fluxes is heavy-tailed for the bacteria H. pylori and E. coli, and the eukaryote S. cerevisiae. While the majority of flux balance investigations have relied on implementations of the simplex method, it is necessary to use interior-point optimization algorithms to adequately characterize the full range of activity patterns on metabolic networks. The interior-point activity pattern is bimodal for E. coli and S. cerevisiae, suggesting that most metabolic reaction are either in frequent use or are rarely active. The trimodal activity pattern of H. pylori indicates that a group of its metabolic reactions (20%) are active in approximately half of the simulated environments. Constructing the high-flux backbone of the network for every environment, there is a clear trend that the more frequently a reaction is active, the more likely it is a part of the backbone. Finally, I briefly discuss the predicted activity patterns of the central-carbon metabolic pathways for the sample of random environments.

  12. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    Energy Technology Data Exchange (ETDEWEB)

    Anheier, N.C. Jr.; McDonald, C.E.; Cuta, J.M.; Cuta, F.M.; Olsen, K.B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose of this work was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. PNL researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH{sub 4}{sup +}). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  13. Ammonia and ammonium hydroxide sensors for ammonia/water absorption machines: Literature review and data compilation

    Science.gov (United States)

    Anheier, N. C., Jr.; McDonald, C. E.; Cuta, J. M.; Cuta, F. M.; Olsen, K. B.

    1995-05-01

    This report describes an evaluation of various sensing techniques for determining the ammonia concentration in the working fluid of ammonia/water absorption cycle systems. The purpose was to determine if any existing sensor technology or instrumentation could provide an accurate, reliable, and cost-effective continuous measure of ammonia concentration in water. The resulting information will be used for design optimization and cycle control in an ammonia-absorption heat pump. Pacific Northwest Laboratory (PNL) researchers evaluated each sensing technology against a set of general requirements characterizing the potential operating conditions within the absorption cycle. The criteria included the physical constraints for in situ operation, sensor characteristics, and sensor application. PNL performed an extensive literature search, which uncovered several promising sensing technologies that might be applicable to this problem. Sixty-two references were investigated, and 33 commercial vendors were identified as having ammonia sensors. The technologies for ammonia sensing are acoustic wave, refractive index, electrode, thermal, ion-selective field-effect transistor (ISFET), electrical conductivity, pH/colormetric, and optical absorption. Based on information acquired in the literature search, PNL recommends that follow-on activities focus on ISFET devices and a fiber optic evanescent sensor with a colormetric indicator. The ISFET and fiber optic evanescent sensor are inherently microminiature and capable of in situ measurements. Further, both techniques have been demonstrated selective to the ammonium ion (NH4(+)). The primary issue remaining is how to make the sensors sufficiently corrosion-resistant to be useful in practice.

  14. Ammonia regeneration for a combined lime/ammonia spray dryer for SO[sub 2] control

    Energy Technology Data Exchange (ETDEWEB)

    Xinjian, Yang (Cincinnati Univ., OH (United States). Dept. of Civil and Environmental Engineering)

    1992-12-23

    A research project designed to study the feasibility of ammonia regeneration for a combined lime/ammonia FGD process was conducted at the University of Cincinnati. The major objective for this project was to regenerate ammonia from a combined ammonia/calcium hydroxide spray dryer FGD byproduct for reuse which would reduce the operating cost of this FGD process. This final report covers the six phases of the project: (1) generation of original feedstock, (2) batch regeneration studies, (3) continuous regeneration studies, (4) waste characteristic analysis, (5) pilot scale demonstration and (6) economic analysis. This research has shown that regeneration of ammonia is feasible at a reasonable cost. The effects on Ohio coal use from the results of this research could be substantial, depending on the Phase II application of FGD systems for controlling SO[sub 2] emissions. In conclusion, experiments in this study have shown that ammonia recovery efficiencies greater than 90% are technically and economically feasible. In addition, the sludge produced from the regeneration process is stable and will meet existing Federal standards.

  15. Ammonia emission inventory for the state of Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Kirchstetter, Thomas W.; Maser, Colette R.; Brown, Nancy J.

    2003-12-17

    Ammonia (NH{sub 3}) is the only significant gaseous base in the atmosphere and it has a variety of impacts as an atmospheric pollutant, including the formation of secondary aerosol particles: ammonium sulfate and ammonium nitrate. NH{sub 3} preferentially forms ammonium sulfate; consequently ammonium nitrate aerosol formation may be limited by the availability of NH{sub 3}. Understanding the impact of emissions of oxides of sulfur and nitrogen on visibility, therefore, requires accurately determined ammonia emission inventories for use in air quality models, upon which regulatory and policy decisions increasingly depend. This report presents an emission inventory of NH{sub 3} for the state of Wyoming. The inventory is temporally and spatially resolved at the monthly and county level, and is comprised of emissions from individual sources in ten categories: livestock, fertilizer, domestic animals, wild animals, wildfires, soil, industry, mobile sources, humans, and publicly owned treatment works. The Wyoming NH{sub 3} inventory was developed using the Carnegie Mellon University (CMU) Ammonia Model as framework. Current Wyoming-specific activity data and emissions factors obtained from state agencies and published literature were assessed and used as inputs to the CMU Ammonia Model. Biogenic emissions from soils comprise about three-quarters of the Wyoming NH{sub 3} inventory, though emission factors from soils are highly uncertain. Published emission factors are scarce and based on limited measurements. In Wyoming, agricultural land, rangeland, and forests comprise 96% of the land area and essentially all of the estimated emissions from soils. Future research on emission rates of NH{sub 3} for these land categories may lead to a substantial change in the magnitude of soil emissions, a different inventory composition, and reduced uncertainty in the inventory. While many NH{sub 3} inventories include annual emissions, air quality modeling studies require finer temporal

  16. Flux-P: Automating Metabolic Flux Analysis

    Directory of Open Access Journals (Sweden)

    Birgitta E. Ebert

    2012-11-01

    Full Text Available Quantitative knowledge of intracellular fluxes in metabolic networks is invaluable for inferring metabolic system behavior and the design principles of biological systems. However, intracellular reaction rates can not often be calculated directly but have to be estimated; for instance, via 13C-based metabolic flux analysis, a model-based interpretation of stable carbon isotope patterns in intermediates of metabolism. Existing software such as FiatFlux, OpenFLUX or 13CFLUX supports experts in this complex analysis, but requires several steps that have to be carried out manually, hence restricting the use of this software for data interpretation to a rather small number of experiments. In this paper, we present Flux-P as an approach to automate and standardize 13C-based metabolic flux analysis, using the Bio-jETI workflow framework. Exemplarily based on the FiatFlux software, it demonstrates how services can be created that carry out the different analysis steps autonomously and how these can subsequently be assembled into software workflows that perform automated, high-throughput intracellular flux analysis of high quality and reproducibility. Besides significant acceleration and standardization of the data analysis, the agile workflow-based realization supports flexible changes of the analysis workflows on the user level, making it easy to perform custom analyses.

  17. Cerebral ammonia uptake and accumulation during prolonged exercise in humans

    DEFF Research Database (Denmark)

    Nybo, Lars; Dalsgaard, Mads K.; Steensberg, Adam;

    2005-01-01

    We evaluated whether peripheral ammonia production during prolonged exercise enhances the uptake and subsequent accumulation of ammonia within the brain. Two studies determined the cerebral uptake of ammonia (arterial and jugular venous blood sampling combined with Kety-Schmidt-determined cerebral...... blood flow; n = 5) and the ammonia concentration in the cerebrospinal fluid (CSF; n = 8) at rest and immediately following prolonged exercise either with or without glucose supplementation. There was a net balance of ammonia across the brain at rest and at 30 min of exercise, whereas 3 h of exercise...... exercise with glucose, and further to 16.1 ± 3.3 µM after the placebo trial (P

  18. Interstellar deuterated ammonia: From NH3 to ND3

    CERN Document Server

    Roueff, E; Van der Tak, F F S; Gerin, M; Goldsmith, P F

    2005-01-01

    We use spectra and maps of NH2D, ND2H, and ND3, obtained with the CSO, IRAM 30m and Arecibo telescopes, to study deuteration processes in dense cores. The data include the first detection of the hyperfine structure of ND2H. The emission of ND2H and ND3 does not seem to peak at the positions of the embedded protostars, but instead at offset positions, where outflow interactions may occur. A constant ammonia fractionation ratio in star-forming regions is generally assumed to be consistent with an origin on dust grains. However, in the pre-stellar cores studied here, the fractionation varies significantly when going from NH3 to ND3. We present a steady state model of the gas-phase chemistry for these sources, which includes passive depletion onto dust grains and multiply saturated deuterated species up to five deuterium atoms (e.g. CD5+). The observed column density ratios of all four ammonia isotopologues are reproduced within a factor of 3 for a gas temperature of 10 K. We also predict that deuterium fractiona...

  19. Ammonia sensor and antibacterial activities of green zinc oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    S. Khaleel Basha

    2016-09-01

    Full Text Available Zinc oxide nanoparticles was synthesized by alginate (A through a rapid and a facile step in the aqueous solution condition at room temperature. Fabrication of zinc oxide nanoparticles was characterized by ATR-FTIR, TEM and XRD. ATR-FTIR analysis confirmed that the A/ZnO NPs were encapsulated by the polymerized alginate. Their shape, structure and composition were assessed by SEM. TEM and XRD analysis indicated that the A/ZnO NPs give evidence of the crystalline nature of ZnO and hybrid NPs structure, which is suitable for ammonia gas sensor development. The controlled size of the A/ZnO NPs obtained using this innovative synthesis strategy minimizes the response time of 2–3 s to sense the ammonia gas significantly with a detection limit of 1 ppm were found at room temperature. The antibacterial tests revealed that the A/ZnO NPs exhibits a potent activity against gram positive and gram negative bacteria.

  20. Analysis of Cryogenic Ammonia System for Energy Conservation

    Directory of Open Access Journals (Sweden)

    B. Raei

    2010-01-01

    Full Text Available There are several alternatives to enhance the efficiency of energy usage and to decrease energy losses. Pinch technology is the best method of approach to enhance energy efficiency. Heat exchangers network (HEN of refrigeration unit of ammonia production process was analyzed to use pinch technology to decrease energy usage. The obtained results showed that pinch technology was unsuccessful for the shaft work targeting capabilities. In contrast, it is posed that for optimization of such systems, one should use the combined pinch and exergy analysis (CPEA method. In this analysis CPEA method was used in the system. It was observed that the refrigeration system use cold streams for cooling the hot streams. Therefore, retrofitting the refrigeration cycle without changing the main process is impossible. Some suggestions were made for improving the refrigeration system, such as the use of economizer after cooler, multistage cycle and removal of the 111-FFD3 stream. It was also observed that the exchanger 128-E act as an intercooler and the flashed 110-F, 111-F and 112-F act as an economizer. In addition, ammonia refrigerant was used at three different temperatures of -33,-7 and 13.5 ˚C. Also, eliminated the 111-FFD3 stream bring about 2% reduction in exergy loss.

  1. Study of Ammonia Emissions in a Ventilated Pig Pen

    DEFF Research Database (Denmark)

    Rong, Li

    reported in literature, little effort has been made to investigate the accuracy of current Henry’s law constant for modeling ammonia mass transfer process and study ammonia emissions in a full scale pig pen from fluid dynamics by CFD simulations. This will be the main objectives of this study. The ammonia...... the accuracy of Henry’s law constants to determine the ammonia concentration in the air through the air-liquid interface. None of the present Henry’s law constant models provide a respectable agreement between simulated and measured results. A simplified model to determine the ammonia concentration in the air...... through the air-liquid interface is suggested from vapor-liquid equilibrium properties of ammonia water. Furthermore, the effects of airflow and temperature on ammonia mass transfer coefficient are also analyzed under different concentration boundary conditions determined by various Henry’s law constant...

  2. Pretreatment of Biomass by Aqueous Ammonia for Bioethanol Production

    Science.gov (United States)

    Kim, Tae Hyun; Gupta, Rajesh; Lee, Y. Y.

    The methods of pretreatment of lignocellulosic biomass using aqueous ammonia are described. The main effect of ammonia treatment of biomass is delignification without significantly affecting the carbohydrate contents. It is a very effective pretreatment method especially for substrates that have low lignin contents such as agricultural residues and herbaceous feedstock. The ammonia-based pretreatment is well suited for simultaneous saccharification and co-fermentation (SSCF) because the treated biomass retains cellulose as well as hemicellulose. It has been demonstrated that overall ethanol yield above 75% of the theoretical maximum on the basis of total carbohydrate is achievable from corn stover pretreated with aqueous ammonia by way of SSCF. There are two different types of pretreatment methods based on aqueous ammonia: (1) high severity, low contact time process (ammonia recycle percolation; ARP), (2) low severity, high treatment time process (soaking in aqueous ammonia; SAA). Both of these methods are described and discussed for their features and effectiveness.

  3. Spin-state chemistry of deuterated ammonia

    Science.gov (United States)

    Sipilä, O.; Harju, J.; Caselli, P.; Schlemmer, S.

    2015-09-01

    Aims: We aim to develop a chemical model that contains a consistent description of spin-state chemistry in reactions involving chemical species with multiple deuterons. We apply the model to the specific case of deuterated ammonia, to derive values for the various spin-state ratios. Methods: We applied symmetry rules in the context of the complete scrambling assumption to calculate branching ratio tables for reactions between chemical species that include multiple protons and/or deuterons. New reaction sets for both gas-phase and grain-surface chemistry were generated using an automated routine that forms all possible spin-state variants of any given reaction with up to six H/D atoms, using the predetermined branching ratios. Both a single-point and a modified Bonnor-Ebert model were considered to study the density and temperature dependence of ammonia and its isotopologs, and the associated spin-state ratios. Results: We find that the spin-state ratios of the ammonia isotopologs are, at late times, very different from their statistical values. The ratios are rather insensitive to variations in the density, but present strong temperature dependence. We derive high peak values (~0.1) for the deuterium fraction in ammonia, in agreement with previous (gas-phase) models. The deuterium fractionation is strongest at high density, corresponding to a high degree of depletion, and also presents temperature dependence. We find that in the temperature range 5 K to 20 K, the deuterium fractionation peaks at ~15 K, while most of the ortho/para (and meta/para for ND3) ratios present a minimum at 10 K (ortho/para NH2D has instead a maximum at this temperature). Conclusions: Owing to the density and temperature dependence found in the abundances and spin-state ratios of ammonia and its isotopologs, it is evident that observations of ammonia and its deuterated forms can provide important constraints on the physical structure of molecular clouds. Appendix A is available in

  4. Efficient Total Nitrogen Removal in an Ammonia Gas Biofilter through High-Rate OLAND

    DEFF Research Database (Denmark)

    De Clippeleir, Haydée; Courtens, Emilie; Mosquera, Mariela;

    2012-01-01

    Ammonia gas is conventionally treated in nitrifying biofilters; however, addition of organic carbon to perform post-denitrification is required to obtain total nitrogen removal. Oxygen-limited autotrophic nitrification/denitrification (OLAND), applied in full-scale for wastewater treatment, can...... offer a cost-effective alternative for gas treatment. In this study, the OLAND application thus was broadened toward ammonia loaded gaseous streams. A down flow, oxygen-saturated biofilter (height of 1.5 m; diameter of 0.11 m) was fed with an ammonia gas stream (248 ± 10 ppmv) at a loading rate of 0.......86 ± 0.04 kg N m–3 biofilter d–1 and an empty bed residence time of 14 s. After 45 days of operation a stable nitrogen removal rate of 0.67 ± 0.06 kg N m–3 biofilter d–1, an ammonia removal efficiency of 99%, a removal of 75–80% of the total nitrogen, and negligible NO/N2O productions were obtained...

  5. Hot Ammonia in the Center of the Seyfert 2 galaxy NGC 3079

    CERN Document Server

    Miyamoto, Yusuke; Seta, Masumichi; Salak, Dragan; Hagiwara, Kenzaburo; Nagai, Makoto; Ishii, Shun; Yamauchi, Aya

    2014-01-01

    We present the results of ammonia observations toward the center of NGC 3079. The NH3(J, K) = (1, 1) and (2, 2) inversion lines were detected in absorption with the Tsukuba 32-m telescope, and the NH3(1,1) through (6,6) lines with the VLA, although the profile of NH3(3,3) was in emission in contrast to the other transitions. The background continuum source, whose flux density was ~50 mJy, could not be resolved with the VLA beam of ~~ 175 K, tracing hot gas associated with the interaction of the fast nuclear outflow with dense molecular material around the nucleus.

  6. Ammonia Synthesis using Ti and Nb Nitride Nano-particles Prepared by Mesoporous Graphitic C3N4

    KAUST Repository

    Kumagai, Hiromu

    2015-01-22

    TiN and NbN nanoparticles were synthesized from mesoporous graphitic C3N4 (mpg-C3N4) as a reactive template and used as the catalyst for ammonia synthesis. The obtained TiN and NbN nanoparticles possess high surface areas of 299 and 275 m2 g-1, respectively, making them attractive in the use of catalysis and support. Although most of the TiN and NbN particles show no measurable activity for ammonia formation, the nanoparticles enabled an ammonia synthesis rate of 31 μmol h-1 g-cat-1 at 673 K and 0.1 MPa of synthesis gas (N2 + 3H2) for both TiN and NbN catalysts. It is evident that the formation of nanoparticles with high nitride surface area is essential for the materials to function as catalysts in ammonia synthesis. The addition of Fe to TiN enhanced the ammonia synthesis activity, whereas it had detrimental effects on the catalytic activity of NbN. The properties of these catalysts in ammonia synthesis are discussed.

  7. Operation summary of ammonia synthesis ammonia storage safety%合成氨氨库安全运行总结

    Institute of Scientific and Technical Information of China (English)

    周荷珍; 张志翠

    2014-01-01

    介绍了氨对人体健康的危害及急救措施、氨罐的操作、汽车氨罐卸氨的原理及具体操作、氨吸收塔的操作,指出只有对氨库实行科学管理和精心操作,才能保证氨库的长期安全稳定运行。%The paper introduces damage from ammonia on human health and emergency measures, ammonia tank operation, the principle of car unloading ammonia ammonia tank and the specific operation, ammonia absorption tower operation, points out that only the ammonia base of scientific management and careful operation, in order to ensure the long-term safe and stable operation of ammonia storage.

  8. Reduction of Ammonia Volatilization through Mixing Urea with Humic and Fulvic Acids isolated from Palm Oil Mill Effluent Sludge

    Directory of Open Access Journals (Sweden)

    Shamsuddin Rosliza

    2009-01-01

    Full Text Available Problem statement: Ammonia volatilization from surface-applied urea may be substantial but it is possible to control it by mixing urea with acidic substances such as Humic Acids (HA and Fulvic Acids (FA. The objective of this study was to compare the effects of urea-HA, urea-FA, urea-acidified (HA+FA mixtures on ammonia loss, soil pH, soil exchangeable ammonium and available nitrate accumulation compared to urea alone. Approach: The effects of urea amended with or without HA and FA were evaluated in a laboratory condition using a closed-dynamic air flow system. Ammonia loss, soil pH, soil exchangeable ammonium and available nitrate were determined using standard procedures. Results: Humic acid alone was not effective in controlling ammonia volatilization even though ammonium retention was found to be significantly higher compared to urea alone. Fulvic acid significantly reduced ammonia volatilization by 50% compared to urea alone. It also caused the highest retention of soil exchangeable ammonium and available nitrate. However, there was no ammonia volatilization with acidified HA and FA. Ammonium and nitrate accumulation for FA was better than acidified HA and FA. Ammonia loss could be reduced by improving ammonium retention. It must be stressed that results obtained in the incubation experiment using an acidic (pHwater 6.32 soil of Typic Paleudults (Bekenu series may only be applicable to similar acid soils. Conclusion: Urea amended with HA or HA and FA significantly reduced ammonia loss. The outcome of this study might be contributed to the improvement of urea N use efficiency as well as reducing environmental pollution.

  9. Was early Mars warmed by ammonia?

    Science.gov (United States)

    Kasting, J. F.; Brown, L. L.; Acord, J. M.; Pollack, J. B.

    1992-01-01

    Runoff channels and valley networks present on ancient, heavily cratered Martian terrain suggests that the climate of Mars was originally warm and wet. One explanation for the formation of these channels is that the surface was warmed by the greenhouse effect of a dense, CO2 atmosphere. However, recent work shows that this theory is not consistent for the early period of the solar system. One way to increase the surface temperature predicted is to assume that other greenhouse gases were present in Mars' atmosphere in addition to CO2 and H2O. This possible gas is ammonia, NH3. If ammonia was present in sufficient quantities, it could have raised the surface temperature to 273 K. An adequate source would have been volcanic outgassing if the NH3 produced was shielded from photolysis by an ultraviolet light absorber.

  10. Computational Search for Improved Ammonia Storage Materials

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Vegge, Tejs;

    . In this project we are searching for improved mixed materials with optimal desorption temperatures and kinetics, optimally releasing all ammonia in one step. We apply Density Functional Theory, DFT, calculations on mixed compounds selected by a Genetic Algorithm (GA), relying on biological principles of natural......Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure...... selection. The GA is evolving from an initial (random) population and selecting those with highest fitness, a function based on e.g. stability, release temperature, storage capacity and the price of the elements. The search space includes all alkaline earth, 3d and 4d metals in combination with chloride...

  11. Modelling of Ammonia Heat Pump Desuperheaters

    DEFF Research Database (Denmark)

    Christensen, Stefan Wuust; Elmegaard, Brian; Markussen, Wiebke Brix;

    2015-01-01

    is that the specific heat is constant throughout the temperature glide of the refrigerant in the heat exchanger. However, considering ammonia as refrigerant, the LMTD method does not give accurate results due to significant variations of the specific heat. By comparing the actual temperature profiles from a one......This paper presents a study of modelling desuperheating in ammonia heat pumps. Focus is on the temperature profile of the superheated refrigerant. Typically, the surface area of a heat exchanger is estimated using the Log Mean Temperature Difference (LMTD) method. The assumption of this method....... The area of the heat exchanger can be increased or the condensation temperature can be raised to achieve the same temperature difference for the discretized model as for the LMTD. This would affect the compressor work, hence the COP of the system. Furthermore, for higher condenser pressure, and thus higher...

  12. Spin-state chemistry of deuterated ammonia

    OpenAIRE

    Sipilä, O.; Harju, J.; Caselli, P.; Schlemmer, S.

    2015-01-01

    Aims. We aim to develop a chemical model that contains a consistent description of spin-state chemistry in reactions involving chemical species with multiple deuterons. We apply the model to the specific case of deuterated ammonia, to derive values for the various spin-state ratios. Methods. We apply symmetry rules in the complete scrambling assumption to calculate branching ratio tables for reactions between chemical species that include multiple protons and/or deuterons. Reaction sets for b...

  13. Manufacture of Catalyst Systems for Ammonia Conversion

    Institute of Scientific and Technical Information of China (English)

    GAKH S.V.; SAVENKOV D.A.

    2012-01-01

    Platinum catalyst gauzes have been in use since the moment of development of the process of catalyst oxidation of ammonia for production of nitric acid or hydrocyanic acid.Catalyst gauzes are usually made of platinum or its alloys with rhodium and palladium.These precious metals have remarkable properties that make them ideal catalysts for acceleration of the ammonia/oxygen reaction.In 2008,OJSC "SIC ‘Supermetal’" and Umicore AG&Co.KG launched a production line for Pt-alloy-based catalyst systems to be used for ammonia oxidation in the production of weak nitric acid.Catalyst systems consist of a pack of catalyst gauzes and a pack of catchment gauzes,which are made using flat-bed knitting machines and wire-cloth looms.Today,up-to-date catalyst systems MKSpreciseTM are being manufactured,the basic advantages of which are an individual structure of gauzes and composition of the material,which allows to define precisely the position of each gauze in the catalyst pack,a high activity of the catalyst pack,direct catching of platinum and rhodium in the catalyst system,and a reasonable combination of single- and multilayer types of gauzes.This makes it possible to vary the configuration of the catalyst and select an optimum composition of the system to ensure the maximum efficiency of the ammonia oxidation process.We also produce the catchment systems that allow to find the best decision from the economic point view for each individual case.

  14. Diverse microbial species survive high ammonia concentrations

    Science.gov (United States)

    Kelly, Laura C.; Cockell, Charles S.; Summers, Stephen

    2012-04-01

    Planetary protection regulations are in place to control the contamination of planets and moons with terrestrial micro-organisms in order to avoid jeopardizing future scientific investigations relating to the search for life. One environmental chemical factor of relevance in extraterrestrial environments, specifically in the moons of the outer solar system, is ammonia (NH3). Ammonia is known to be highly toxic to micro-organisms and may disrupt proton motive force, interfere with cellular redox reactions or cause an increase of cell pH. To test the survival potential of terrestrial micro-organisms exposed to such cold, ammonia-rich environments, and to judge whether current planetary protection regulations are sufficient, soil samples were exposed to concentrations of NH3 from 5 to 35% (v/v) at -80°C and room temperature for periods up to 11 months. Following exposure to 35% NH3, diverse spore-forming taxa survived, including representatives of the Firmicutes (Bacillus, Sporosarcina, Viridibacillus, Paenibacillus, Staphylococcus and Brevibacillus) and Actinobacteria (Streptomyces). Non-spore forming organisms also survived, including Proteobacteria (Pseudomonas) and Actinobacteria (Arthrobacter) that are known to have environmentally resistant resting states. Clostridium spp. were isolated from the exposed soil under anaerobic culture. High NH3 was shown to cause a reduction in viability of spores over time, but spore morphology was not visibly altered. In addition to its implications for planetary protection, these data show that a large number of bacteria, potentially including spore-forming pathogens, but also environmentally resistant non-spore-formers, can survive high ammonia concentrations.

  15. Ammonia volatilization from sows on grassland

    Science.gov (United States)

    Sommer, S. G.; Søgaard, H. T.; Møller, H. B.; Morsing, S.

    According to regulations, sows with piglets on organic farms must graze on pastures. Volatilization of ammonia (NH 3) from urine patches may represent a significant source of nitrogen (N) loss from these farms. Inputs of N are low on organic farms and losses may reduce crop production. This study examined spatial variations in NH 3 volatilization using a movable dynamic chamber, and the pH and total ammoniacal nitrogen (TAN) content in the topsoil of pastures with grazing sows was measured during five periods between June 1998 and May 1999. Gross NH 3 volatilization from the pastures was also measured with an atmospheric mass balance technique during seven periods from September 1997 until June 1999. The dynamic chamber study showed a high variation in NH 3 volatilization because of the distribution of urine; losses were between 0 and 2.8 g NH 3-N m -2 day -1. Volatilization was highest near the feeding area and the huts, where the sows tended to urinate. Ammonia volatilization rate was linearly related to the product of NH 3 concentration in the boundary layer and wind speed. The NH 3 in the boundary layer was in equilibrium with NH 3 in soil solution. Gross NH 3 volatilization was in the range 0.07-2.1 kg NH 3-N ha -1 day -1 from a pasture with 24 sows ha -1. Ammonia volatilization was related to the amount of feed given to the sows, incident solar radiation and air temperature during measuring periods, and also to temperature, incident solar radiation and rain 1-2 days before measurements. Annual ammonia loss was 4.8 kg NH 3-N sow -1.

  16. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N₂O was 92–92,5 % at the ammonia conversion of 98–99.5 % in the optimal temperature range.

  17. Ammonia biofiltration and community analysis of ammonia-oxidizing bacteria in biofilters.

    Science.gov (United States)

    Jun, Yin; Wenfeng, Xu

    2009-09-01

    Biological removal of ammonia was investigated using compost and sludge as packing materials in laboratory-scale biofilters. The aim of this study is to characterize the composition of ammonia-oxidizing bacteria (AOB) in two biofilters designed to remove ammonia. Experimental tests and measurements included analysis of removal efficiency and metabolic products. The inlet concentration of ammonia applied was 20-100 mg m(-3). Removal efficiencies of BFC and BFS were in the range of 97-99% and 95-99%, respectively. Periodic analysis of the biofilter packing materials showed ammonia was removed from air stream by nitrification and by the improved absorption of NH(3) in the resultant acidity. Nitrate was the dominant product of NH(3) transformation. Changes in the composition of AOB were examined by using nested PCR, denaturing gradient gel electrophoresis (DGGE) and sequencing of DGGE bands. DGGE analysis of biofilter samples revealed that shifts in the community structure of AOB were observed in the experiment; however, the idle phase did not cause the structural shift of AOB. Phylogenetic analysis revealed the population of AOB showed Nitrosospira sp. remains the predominant population in BFC, while Nitrosomonas sp. is the predominant population in BFS.

  18. Ammonia emissions in Europe, part II: How ammonia emission abatement strategies affect secondary aerosols

    Science.gov (United States)

    Backes, Anna M.; Aulinger, Armin; Bieser, Johannes; Matthias, Volker; Quante, Markus

    2016-02-01

    In central Europe, ammonium sulphate and ammonium nitrate make up a large fraction of fine particles which pose a threat to human health. Most studies on air pollution through particulate matter investigate the influence of emission reductions of sulphur- and nitrogen oxides on aerosol concentration. Here, we focus on the influence of ammonia (NH3) emissions. Emission scenarios have been created on the basis of the improved ammonia emission parameterization implemented in the SMOKE for Europe and CMAQ model systems described in part I of this study. This includes emissions based on future European legislation (the National Emission Ceilings) as well as a dynamic evaluation of the influence of different agricultural sectors (e.g. animal husbandry) on particle formation. The study compares the concentrations of NH3, NH4+, NO3 -, sulphur compounds and the total concentration of particles in winter and summer for a political-, technical- and behavioural scenario. It was found that a reduction of ammonia emissions by 50% lead to a 24% reduction of the total PM2.5 concentrations in northwest Europe. The observed reduction was mainly driven by reduced formation of ammonium nitrate. Moreover, emission reductions during winter had a larger impact than during the rest of the year. This leads to the conclusion that a reduction of the ammonia emissions from the agricultural sector related to animal husbandry could be more efficient than the reduction from other sectors due to its larger share in winter ammonia emissions.

  19. The use of anhydrous ammonia for bioventing

    Energy Technology Data Exchange (ETDEWEB)

    Zytner, R.G.; Hallman, M.; Gimenez, B.F.; Jennings, R.; Leek, K. [Guelph Univ., ON (Canada). Faculty of Graduate Studies

    2002-07-01

    Soils contaminated with hydrocarbons can be effectively treated using bioventing remediation technology, an ideal method for removing residual contamination left by soil vapour extraction (SVE). Bioventing uses low or intermitted air flow rates to produce oxygen-rich conditions in the vadose zone, thereby promoting the formation of micro-organisms that can mineralize the hydrocarbons if enough nutrients are present. There is concern regarding the use of nutrients (the addition of nitrogen) to the subsurface because current applications methods cannot uniformly disperse nitrogen throughout the entire subsurface. Two research studies are being conducted using gasoline contaminated soil to address this concern. The first phase of the study focuses on how to best deliver nitrogen to the subsurface. Injecting anhydrous ammonia into the contaminated surface was one suggestion for stimulating the growth of hydrocarbon degraders. SVE extraction well models indicated this was an effective and safe way to disperse nitrogen. The second phase of the study involved the use of respirometers to compare total petroleum hydrocarbon (TPH) degradation with nitrogen additions in the form of NH{sub 4}Cl or anhydrous ammonia. The respirometers were run for about 1 month after which time it was determined that the use of anhydrous ammonia is an effective method to promote bioventing.

  20. Spin-state chemistry of deuterated ammonia

    CERN Document Server

    Sipilä, O; Caselli, P; Schlemmer, S

    2015-01-01

    Aims. We aim to develop a chemical model that contains a consistent description of spin-state chemistry in reactions involving chemical species with multiple deuterons. We apply the model to the specific case of deuterated ammonia, to derive values for the various spin-state ratios. Methods. We apply symmetry rules in the complete scrambling assumption to calculate branching ratio tables for reactions between chemical species that include multiple protons and/or deuterons. Reaction sets for both gas-phase and grain-surface chemistry are generated using an automated routine that forms all possible spin-state variants of any given reaction with up to six H/D atoms. Single-point and modified Bonnor-Ebert models are used to study the density and temperature dependence of ammonia and its isotopologs, and the associated spin-state ratios. Results. We find that the spin-state ratios of the ammonia isotopologs are, at late times, very different from their statistical values. The ratios are rather insensitive to varia...

  1. Ammonia and nitrite oxidation in the Eastern Tropical North Pacific

    Science.gov (United States)

    Peng, Xuefeng; Fuchsman, Clara A.; Jayakumar, Amal; Oleynik, Sergey; Martens-Habbena, Willm; Devol, Allan H.; Ward, Bess B.

    2015-12-01

    Nitrification plays a key role in the marine nitrogen (N) cycle, including in oceanic oxygen minimum zones (OMZs), which are hot spots for denitrification and anaerobic ammonia oxidation (anammox). Recent evidence suggests that nitrification links the source (remineralized organic matter) and sink (denitrification and anammox) of fixed N directly in the steep oxycline in the OMZs. We performed shipboard incubations with 15N tracers to characterize the depth distribution of nitrification in the Eastern Tropical North Pacific (ETNP). Additional experiments were conducted to investigate photoinhibition. Allylthiourea (ATU) was used to distinguish the contribution of archaeal and bacterial ammonia oxidation. The abundance of archaeal and β-proteobacterial ammonia monooxygenase gene subunit A (amoA) was determined by quantitative polymerase chain reaction. The rates of ammonia and nitrite oxidation showed distinct subsurface maxima, with the latter slightly deeper than the former. The ammonia oxidation maximum coincided with the primary nitrite concentration maximum, archaeal amoA gene maximum, and the subsurface nitrous oxide maximum. Negligible rates of ammonia oxidation were found at anoxic depths, where high rates of nitrite oxidation were measured. Archaeal amoA gene abundance was generally 1 to 2 orders of magnitude higher than bacterial amoA gene abundance, and inhibition of ammonia-oxidizing bacteria with 10 μM ATU did not affect ammonia oxidation rates, indicating the dominance of archaea in ammonia oxidation. These results depict highly dynamic activities of ammonia and nitrite oxidation in the oxycline of the ETNP OMZ.

  2. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    Institute of Scientific and Technical Information of China (English)

    Brooke B.OSBORNE; Jill S.BARON; Matthew D.WALLENSTEIN

    2016-01-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many high-elevation ecosystems.The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses.In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity,we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash,talus,and meadow).We found that bacteria,not archaea,dominated all ammonia oxidizer communities.Nitrification increased with moisture in all soils and under all temperature treatments.However,temperature was not correlated with nitrification rates in all soils.Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes.Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  3. Adaptation of an Ammonia Detecting Paint to Commerical Applications

    Science.gov (United States)

    Graef, Renee C.; Mallow, William A.

    1994-01-01

    An ammonia-sensitive coating was developed in feasibility studies sponsored by Lockheed Engineering. The paint comprised a cellulosic binder, a dye, a family of solvents, and plasticizer. The resulting coating formulation proved to be very sensitive to trace levels of Lewis-bases and/or nucleophiles, but was limited to concentrations of approximately 1 ppm and higher. In the months following completion of this Lockheed project, efforts to perfect and optimize the paint formulation continued with internal funding. A unique sensitivity enhancing additive was identified and patented which when applied at concentrations of approximately 10% by weight, transcended the 1 ppm sensitivity barrier to fractional ppb. The paint composition was modified by the addition of certain proprietary agents, which promoted a much more intense yellow color in the coating and enhanced its durability in high-vacuum. Paint preparation is a simple one day procedure that can be completed using conventional equipment. Most of the materials are easily obtained.

  4. Patterns of Flux Emergence

    Science.gov (United States)

    Title, A.; Cheung, M.

    2008-05-01

    The high spatial resolution and high cadence of the Solar Optical Telescope on the JAXA Hinode spacecraft have allowed capturing many examples of magnetic flux emergence from the scale of granulation to active regions. The observed patterns of emergence are quite similar. Flux emerges as a array of small bipoles on scales from 1 to 5 arc seconds throughout the region that the flux eventually condenses. Because the fields emerging from the underlying flux rope my appear many in small segments and the total flux (absolute sum) is not a conserved quantity the amount of total flux on the surface may vary significantly during the emergence process. Numerical simulations of flux emergence exhibit patterns similar to observations. Movies of both observations and numerical simulations will be presented.

  5. Ammonia tolerant enriched methanogenic cultures as bioaugmentation inocula to alleviate ammonia inhibition in continuous anaerobic reactors

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Wang, Han; Angelidaki, Irini

    . The bioaugmentation was performed without pausing the continuous operation of the CSTR reactor and without excluding the ammonia-rich substrate from the feedstock. Thus, bioaugmentation with mixed methanogenic cultures could potentially support the development of an efficient and cost-effective biomethanation process...... of a pure culture, to be used as bioaugmentation inoculum, poses technical difficulties due to the required sterile conditions and the special growing media. On the contrary acclimatized enrichment methanogenic cultures have lower requirements to sterility. In the present study, we used an enriched ammonia...... tolerant methanogenic culture as potential bioaugmentation inoculum in a continuous stirred tank reactor (CSTR) operating under “inhibited steady-state”, triggered by high ammonia levels (5 g NH4+-N L-1). The results of the current study established for the first time that bioaugmentation of an enriched...

  6. BVOC fluxes above mountain grassland

    Directory of Open Access Journals (Sweden)

    I. Bamberger

    2010-05-01

    Full Text Available Grasslands comprise natural tropical savannah over managed temperate fields to tundra and cover one quarter of the Earth's land surface. Plant growth, maintenance and decay result in volatile organic compound (VOCs emissions to the atmosphere. Furthermore, biogenic VOCs (BVOCs are emitted as a consequence of various environmental stresses including cutting and drying during harvesting. Fluxes of BVOCs were measured with a proton-transfer-reaction-mass-spectrometer (PTR-MS over temperate mountain grassland in Stubai Valley (Tyrol, Austria over one growing season (2008. VOC fluxes were calculated from the disjunct PTR-MS data using the virtual disjunct eddy covariance method and the gap filling method. Methanol fluxes obtained with the two independent flux calculation methods were highly correlated (y = 0.95×−0.12, R2 = 0.92. Methanol showed strong daytime emissions throughout the growing season – with maximal values of 9.7 nmol m−2 s−1, methanol fluxes from the growing grassland were considerably higher at the beginning of the growing season in June compared to those measured during October (2.5 nmol m−2 s−1. Methanol was the only component that exhibited consistent fluxes during the entire growing periods of the grass. The cutting and drying of the grass increased the emissions of methanol to up to 78.4 nmol m−2 s−1. In addition, emissions of acetaldehyde (up to 11.0 nmol m−2 s−1, and hexenal (leaf aldehyde, up to 8.6 nmol m−2 s−1 were detected during/after harvesting.

  7. Prediction of Transport Properties of Liquid Ammonia and Its Binary Mixture with Methanol by Molecular Simulation

    Science.gov (United States)

    Guevara-Carrion, Gabriela; Vrabec, Jadran; Hasse, Hans

    2012-03-01

    Transport properties of ammonia and of the binary mixture ammonia + methanol are predicted for a broad range of liquid states by molecular dynamics (MD) simulation on the basis of rigid, non-polarizable molecular models of the united-atom type. These models were parameterized in preceding work using only experimental vapor-liquid equilibrium data. The self- and the Maxwell-Stefan (MS) diffusion coefficients as well as the shear viscosity are obtained by equilibrium MD and the Green-Kubo formalism. Non-equilibrium MD is used for the thermal conductivity. The transport properties of liquid ammonia are predicted for temperatures between 223 K and 473 K up to pressures of 200 MPa and are compared to experimental data and correlations thereof. Generally, good agreement is achieved. The predicted self-diffusion coefficient as well as the shear viscosity deviates on average by less than 15 % from the experiment and the thermal conductivity by less than 6 %. Furthermore, the self- and the MS transport diffusion coefficients as well as the shear viscosity of the liquid mixture ammonia + methanol are studied at different compositions and compared to the available experimental data.

  8. Modeling of ammonia emission in the USA and EU countries using an artificial neural network approach.

    Science.gov (United States)

    Stamenković, Lidija J; Antanasijević, Davor Z; Ristić, Mirjana Đ; Perić-Grujić, Aleksandra A; Pocajt, Viktor V

    2015-12-01

    Ammonia emissions at the national level are frequently estimated by applying the emission inventory approach, which includes the use of emission factors, which are difficult and expensive to determine. Emission factors are therefore the subject of estimation, and as such they contribute to inherent uncertainties in the estimation of ammonia emissions. This paper presents an alternative approach for the prediction of ammonia emissions at the national level based on artificial neural networks and broadly available sustainability and economical/agricultural indicators as model inputs. The Multilayer Perceptron (MLP) architecture was optimized using a trial-and-error procedure, including the number of hidden neurons, activation function, and a back-propagation algorithm. Principal component analysis (PCA) was applied to reduce mutual correlation between the inputs. The obtained results demonstrate that the MLP model created using the PCA transformed inputs (PCA-MLP) provides a more accurate prediction than the MLP model based on the original inputs. In the validation stage, the MLP and PCA-MLP models were tested for ammonia emission predictions for up to 2 years and compared with a principal component regression model. Among the three models, the PCA-MLP demonstrated the best performance, providing predictions for the USA and the majority of EU countries with a relative error of less than 20%.

  9. Flow-based ammonia gas analyzer with an open channel scrubber for indoor environments.

    Science.gov (United States)

    Ohira, Shin-Ichi; Heima, Minako; Yamasaki, Takayuki; Tanaka, Toshinori; Koga, Tomoko; Toda, Kei

    2013-11-15

    A robust and fully automated indoor ammonia gas monitoring system with an open channel scrubber (OCS) was developed. The sample gas channel dimensions, hydrophilic surface treatment to produce a thin absorbing solution layer, and solution flow rate of the OCS were optimized to connect the OCS as in-line gas collector and avoid sample humidity effects. The OCS effluent containing absorbed ammonia in sample gas was injected into a derivatization solution flow. Derivatization was achieved with o-phthalaldehyde and sulfite in pH 11 buffer solution. The product, 1-sulfonateisoindole, is detected with a home-made fluorescence detector. The limit of detection of the analyzer based on three times the standard deviation of baseline noise was 0.9 ppbv. Sample gas could be analyzed 40 times per hour. Furthermore, relative humidity of up to 90% did not interfere considerably with the analyzer. Interference from amines was not observed. The developed gas analysis system was calibrated using a solution-based method. The system was used to analyze ammonia in an indoor environment along with an off-site method, traditional impinger gas collection followed by ion chromatographic analysis, for comparison. The results obtained using both methods agreed well. Therefore, the developed system can perform on-site monitoring of ammonia in indoor environments with improved time resolution compared with that of other methods.

  10. Optimization of biomethanation focusing on high ammonia loaded processes

    DEFF Research Database (Denmark)

    Wang, Han

    , could theoretically mitigate the ammonia inhibition problem (Angelidaki et al., 1999). Therefore, the effect of co-digestion of cattle manure with lipids (i.e. glycerol trioleate (GTO)) under high ammonia levels (5 g NH4+-N·L-1) in anaerobic continuous stirred tank (CSTR) reactors (RGTO) was assessed......” was observed, which caused a deterioration of the inhibition effect in anaerobic digestion process. On contrary, the reactor where glucose was co-digested demonstrated higher tolerance to ammonia toxicity compared with the reactor where GTO was used. Secondly, the problem of ammonia inhibition during...... in continuous reactors. Furthermore, bioaugmentation with an ammonia tolerant methanogen to alleviate ammonia toxicity could be applied for improving the efficiency of biomethanation process in full-scale continuous reactors. Finally, an innovative method, where hydrogen is injected in the anaerobic reactor...

  11. Ammonia/Hydrogen Mixtures in an SI-Engine

    DEFF Research Database (Denmark)

    Mørch, Christian Sandersen; Bjerre, Andreas; Gøttrup, Morten Piil;

    2011-01-01

    In recent years there has been increasing focus on using metal ammine complexes for ammonia storage. In this paper a fuel system for ammonia fuelled internal combustion engines using metal ammine complexes as ammonia storage is analyzed. The use of ammonia/hydrogen mixtures as an SI-engine fuel...... is investigated in the same context. Ammonia and hydrogen were introduced into the intake manifold of a CFR-engine. Series of experiments with varying excess air ratio and different ammonia to hydrogen ratios was conducted. This showed that a fuel mixture with 10 vol.% hydrogen performs best with respect...... to efficiency and power. A comparison with gasoline was made, which showed efficiencies and power increased due to the possibility of a higher compression ratio. The system analysis showed that it is possible to cover a major part of the necessary heat using the exhaust heat. It is proposed to reduce the high...

  12. Dis-aggregation of airborne flux measurements using footprint analysis

    NARCIS (Netherlands)

    Hutjes, R.W.A.; Vellinga, O.S.; Gioli, B.; Miglietta, F.

    2010-01-01

    Aircraft measurements of turbulent fluxes are generally being made with the objective to obtain an estimate of regional exchanges between land surface and atmosphere, to investigate the spatial variability of these fluxes, but also to learn something about the fluxes from some or all of the land cov

  13. Removal of Ammonia from Air, using Three Iranian Natural Zeolites

    OpenAIRE

    H. Asilian; SB Mortazavi; Kazemian, H; S Phaghiehzadeh; Sj Shahtaheri; Salem, M.

    2004-01-01

    Ammonia in air can be hazardous to human and animal life and should be removed from the environment. Recently the removal of environmental pollutants such as ammonia by means of natural and modified zeolites has attracted a lot of attention and interests. In this study the capability of three Iranian natural zeolites (Clinoptilolite) in point of view of removal of ammonia from air was investigated. Through this research, different zeolites from various regions of Iran including Semnan, Meyane...

  14. Mathematical Model of Ammonia Handling in the Rat Renal Medulla

    OpenAIRE

    Noiret, Lorette; Baigent, Stephen; Jalan, Rajiv; Thomas, S. Randall

    2015-01-01

    The kidney is one of the main organs that produces ammonia and release it into the circulation. Under normal conditions, between 30 and 50% of the ammonia produced in the kidney is excreted in the urine, the rest being absorbed into the systemic circulation via the renal vein. In acidosis and in some pathological conditions, the proportion of urinary excretion can increase to 70% of the ammonia produced in the kidney. Mechanisms regulating the balance between urinary excretion and renal vein ...

  15. Options and Costs of Controlling Ammonia Emissions in Europe

    OpenAIRE

    Klaassen, G.

    1994-01-01

    Ammonia emissions contribute to acidification in Europe. The major emission sources are livestock and fertilizer use. This study presents the costs of controlling ammonia emissions in 33 regions in Europe. Abatement options include low nitrogen feed, stable adaptations, covering manure storage, cleaning stable air, and low ammonia applications of manure. Cost estimates are based on country- and technology-specific data. The structure of livestock population and fertilizer use mean that th...

  16. Electrolysis of ammonia for hydrogen production catalyzed by Pt and Pt-Ir deposited on nickel foam

    Institute of Scientific and Technical Information of China (English)

    Min; Jiang; Dandan; Zhu; Xuebo; Zhao

    2014-01-01

    Electrolysis of ammonia in alkaline electrolyte solution was applied for the production of hydrogen. Both Pt-loaded Ni foam and Pt-Ir loaded Ni foam electrodes were prepared by electrodeposition and served as anode and cathode in ammonia electrolytic cell, respectively. The electrochemical behaviors of ammonia in KOH solution were individually investigated via cyclic voltammetry on three electrodes, i.e. bare Ni foam electrode, Pt-loaded Ni foam electrode and Pt-Ir loaded Ni foam electrode. The morphology and composition of the prepared Ni foam electrode were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Effects of the concentration of electrolyte solution and temperature of electrolytic cell on the electrolysis reaction were examined in order to enhance the efficiency of ammonia electrolysis. The competition of ammonia electrolysis and water electrolysis in the same alkaline solution was firstly proposed to explain the changes of cell voltage with the electrolysis proceeding. At varying current densities, different cell voltages could be obtained from galvanostatic curves.The low cell voltage of 0.58 V, which is less than the practical electrolysis voltage of water(1.6 V), can be obtained at a current density of2.5 mA/cm2. Based on some experimental parameters, such as the applied current, the resulting cell voltage and output of hydrogen gas, the power consumption per gram of H2produced can be estimated.

  17. Fast In Situ Airborne Measurement of Ammonia Using a Mid-Infrared Off-Axis ICOS Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Leen, J. Brian; Yu, Xiao-Ying; Gupta, Manish; Baer, Douglas S.; Hubbe, John M.; Kluzek, Celine D.; Tomlinson, Jason M.; Hubbell, Mike R.

    2013-08-23

    A new ammonia (NH3) analyzer was developed based on off-axis integrated cavity output spectroscopy. Its feasibility was demonstrated by making tropospheric measurements in flights aboard the Department of Energy Gulfstream-1 aircraft. The ammonia analyzer consists of an optical cell, quantum-cascade laser, gas sampling system, control and data acquisition electronics, and analysis software. The NH3 mixing ratio is determined from high-resolution absorption spectra obtained by tuning the laser wavelength over the NH3 fundamental vibration band near 9.67 μm. Excellent linearity is obtained over a wide dynamic range (0–101 ppbv) with a response rate (1/e) of 2 Hz and a precision of ±90 pptv (1σ in 1 s). Two research flights were conducted over the Yakima Valley in Washington State. In the first flight, the ammonia analyzer was used to identify signatures of livestock from local dairy farms with high vertical and spatial resolution under low wind and calm atmospheric conditions. In the second flight, the analyzer captured livestock emission signals under windy conditions. Finally, our results demonstrate that this new ammonia spectrometer is capable of providing fast, precise, and accurate in situ observations of ammonia aboard airborne platforms to advance our understanding of atmospheric compositions and aerosol formation.

  18. 46 CFR 98.25-5 - How anhydrous ammonia may be carried.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false How anhydrous ammonia may be carried. 98.25-5 Section 98... Anhydrous Ammonia in Bulk § 98.25-5 How anhydrous ammonia may be carried. (a) Anhydrous ammonia shall be..., except as otherwise provided in paragraph (b) of this section. (b) When anhydrous ammonia is to...

  19. Process model for ammonia volatilization from anaerobic swine lagoons incorporating varying wind speeds and biogas bubbling

    Science.gov (United States)

    Ammonia volatilization from treatment lagoons varies widely with the total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model integrating ammonia ...

  20. Benthic flux of nutrients and trace metals in the northern component of San Francisco Bay, California

    Science.gov (United States)

    Kuwabara, James S.; Topping, Brent R.; Parcheso, Francis; Engelstad, Anita C.; Greene, Valerie E.

    2009-01-01

    Two sets of sampling trips were coordinated in late summer 2008 (weeks of July 8 and August 6) to sample the interstitial and overlying bottom waters at 10 shallow locations (9 sites Brown?s Island. Except for the elevated flux at Browns Island, the benthic flux of soluble reactive phosphorus (SRP) was consistently: (1) lower than previously reported for South Bay sites, (2) an order of magnitude lower than oligotrophic Coeur d?Alene Lake, (3) two orders of magnitude lower than determined for eutrophic Upper Klamath Lake, and (4) an order of magnitude or more lower than the estimated summer riverine inputs for SRP (900 to 1,300 kilograms of phosphorous per day (kg-P d-1)). In contrast to fluxes reported for the South Bay, nitrate fluxes were consistently negative (that is, drawn from the water column into the sediment), except for one site with statistically insignificant nitrate fluxes (Site 409 within Suisun Bay). The most negative nitrate flux (-7.3?0.1 mmole m-2d-1) was observed within Grizzly Bay (Site 416). Observed nitrate fluxes bracketed the estimated summer fluvial flux of nitrate (3,500 to 5,000 kg-N d-1). With the exception of the two Grizzly Bay sites (416 and 417), the consistently positive benthic flux of ammonia generally counteracted the negative flux of nitrate to yield a net balance of dissolved inorganic nitrogen. Ammonia benthic fluxes extrapolated for Suisun Bay ranged from 320 kg-N d-1 (Site SSB009 near the entrance to Honker Bay) to 1,900 kg-N d-1 (Montezuma Island). These values represent a significant ammonia source to the water column relative to summer riverine inputs (approximately 400 to 600 kg-N d-1). Dissolved silica also displayed a consistently positive benthic flux, except for Site 409 within Suisun Bay, which showed insignificant fluxes (also insignificant for nitrate and SRP). As with the nitrate fluxes, Grizzly Bay and Browns Island sites yielded the highest dissolved silica fluxes (1.3?1.2 to 2.5?0.6 mmole m-2d-1, respectively

  1. HONO fluxes from soil surfaces: an overview

    Science.gov (United States)

    Wu, Dianming; Sörgel, Matthias; Tamm, Alexandra; Ruckteschler, Nina; Rodriguez-Caballero, Emilio; Cheng, Yafang; Pöschl, Ulrich; Weber, Bettina

    2016-04-01

    Gaseous nitrous acid (HONO) contributes up to 80% of atmospheric hydroxyl (OH) radicals and is also linked to health risks through reactions with tobacco smoke forming carcinogens. Field and modeling results suggested a large unknown HONO source in the troposphere during daytime. By measuring near ground HONO mixing ratio, up to 30% of HONO can be released from forest, rural and urban ground as well as snow surfaces. This source has been proposed to heterogeneous reactions of nitrogen dioxide (NO2) on humic acid surfaces or nitric acid photolysis. Laboratory studies showed that HONO emissions from bulk soil samples can reach 258 ng m‑2 s‑1 (in term of nitrogen), which corresponding to 1.1 × 1012 molecules cm‑2 s‑1and ˜ 100 times higher than most of the field studies, as measured by a dynamic chamber system. The potential mechanisms for soil HONO emissions include chemical equilibrium of acid-base reaction and gas-liquid partitioning between soil nitrite and HONO, but the positive correlation of HONO fluxes with pH (largest at neutral and slightly alkaline) points to the dominance of the formation process by ammonia-oxidizing bacteria (AOB). In general soil surface acidity, nitrite concentration and abundance of ammonia-oxidizing bacteria mainly regulate the HONO release from soil. A recent study showed that biological soil crusts in drylands can also emit large quantities of HONO and NO, corresponding to ˜20% of global nitrogen oxide emissions from soils under natural vegetation. Due to large concentrations of microorganisms in biological soil crusts, particularly high HONO and NO emissions were measured after wetting events. Considering large areas of arid and arable lands as well as peatlands, up to 70% of global soils are able to emitting HONO. However, the discrepancy between large soil HONO emissions measured in lab and low contributions of HONO flux from ground surfaces in field as well as the role of microorganisms should be further investigated.

  2. Ammonia pollution characteristics of centralized drinking water sources in China

    Institute of Scientific and Technical Information of China (English)

    Qing Fu; Binghui Zheng; Xingru Zhao; Lijing Wang; Changming Liu

    2012-01-01

    The characteristics of ammonia in drinking water sources in China were evaluated during 2005-2009.The spatial distribution and seasonal changes of ammonia in different types of drinking water sources of 22 provinces,5 autonomous regions and 4 municipalities were investigated.The levels of ammonia in drinking water sources follow the order of river > lake/reservoir > groundwater.The levels of ammonia concentration in river sources gradually decreased from 2005 t0 2008,while no obvious change was observed in the lakes/reservoirs and groundwater drinking water sources.The proportion of the type of drinking water sources is different in different regions.In river drinking water sources,the ammonia level was varied in different regions and changed seasonally.The highest value and wide range of annual ammonia was found in South East region,while the lowest value was found in Southwest region.In lake/reservoir drinking water sources,the ammonia levels were not varied obviously in different regions.In underground drinking water sources,the ammonia levels were varied obviously in different regions due to the geological permeability and the natural features of regions.In the drinking water sources with higher ammonia levels,there are enterprises and wastewater drainages in the protected areas of the drinking water sources.

  3. Oxydesulfurization of a Turkish hard lignite with ammonia solutions

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, S.; Kuecuekbayrak, S. [Istanbul Technical Univ. (Turkey). Chemical and Metallurgical Engineering Faculty

    1996-09-01

    In this study the desulfurization of a high pyritic and high organic sulfur lignite taken from the Gediz area (western Turkey) was investigated by the oxydesulfurization method using ammonia solutions. The influence of such parameters as the concentration of ammonia solution, partial pressure of oxygen, temperature, and reaction time were studied. The ranges of these parameters were selected as 0--10 M concentration of ammonia solution, 0--1.5 MPa partial pressure of oxygen, 403--473 K temperature, and 10--60 min reaction time. It was concluded that the use of ammonia solution as an extraction solution increased the efficiency of the oxydesulfurization process.

  4. Spatial and temporal variations in ammonia emissions - a freely accessible model code for Europe

    DEFF Research Database (Denmark)

    Skjøth, Carsten Ambelas; Geels, Camilla; Berge, H.;

    2011-01-01

    demonstrates how local climate and local management can be accounted for in CTMs by applying a modular approach for deriving data as input to a dynamic ammonia emission model for Europe. Default data are obtained from information in the RAINS system, and it is demonstrated how this dynamic emission model based......Deriving a parameterisation of ammonia emissions for use in chemistry-transport models (CTMs) is a complex problem as the emission varies locally as a result of local climate and local agricultural management. In current CTMs such factors are generally not taken into account. This paper...... this domain. The model code and the obtained default values for the modelling experiments are available as supplementary information to this article for use by the modelling community on similar terms as the EMEP CTM model: the GPL licencse v3....

  5. FIRST DETECTION OF AMMONIA IN THE LARGE MAGELLANIC CLOUD: THE KINETIC TEMPERATURE OF DENSE MOLECULAR CORES IN N 159 W

    International Nuclear Information System (INIS)

    The first detection of ammonia (NH3) is reported from the Magellanic Clouds. Using the Australia Telescope Compact Array, we present a targeted search for the (J, K) = (1,1) and (2,2) inversion lines toward seven prominent star-forming regions in the Large Magellanic Cloud (LMC). Both lines are detected in the massive star-forming region N 159 W, which is located in the peculiar molecular ridge south of 30 Doradus, a site of extreme star formation strongly influenced by an interaction with the Milky Way halo. Using the ammonia lines, we derive a kinetic temperature of ∼16 K, which is 2-3 times below the previously derived dust temperature. The ammonia column density, averaged over ∼17'', is ∼6 x 1012 cm-2 (13 cm-2 over 9'' in the other six sources) and we derive an ammonia abundance of ∼4 x 10-10 with respect to molecular hydrogen. This fractional abundance is 1.5-5 orders of magnitude below those observed in Galactic star-forming regions. The nitrogen abundance in the LMC (∼10% solar) and the high UV flux, which can photo-dissociate the particularly fragile NH3 molecule, both must contribute to the low fractional NH3 abundance, and we likely only see the molecule in an ensemble of the densest, best shielded cores of the LMC.

  6. AMMONIA-FREE NOx CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Song Wu; Zhen Fan; Andrew H. Seltzer; Richard G. Herman

    2006-06-01

    This report describes a novel NOx control system that has the potential to drastically reduce cost, and enhance performance, operation and safety of power plant NOx control. The new system optimizes the burner and the furnace to achieve very low NOx levels and to provide an adequate amount of CO, and uses the CO for reducing NO both in-furnace and over a downstream AFSCR (ammonia-free selective catalytic reduction) reactor. The AF-SCR combines the advantages of the highly successful SCR technology for power plants and the TWC (three-way catalytic converter) widely used on automobiles. Like the SCR, it works in oxidizing environment of combustion flue gas and uses only base metal catalysts. Like the TWC, the AF-SCR removes NO and excess CO simultaneously without using any external reagent, such as ammonia. This new process has been studied in a development program jointed funded by the US Department of Energy and Foster Wheeler. The report outlines the experimental catalyst work performed on a bench-scale reactor, including test procedure, operating conditions, and results of various catalyst formulations. Several candidate catalysts, prepared with readily available transition metal oxides and common substrate materials, have shown over 80-90% removal for both NO and CO in oxidizing gas mixtures and at elevated temperatures. A detailed combustion study of a 400 MWe coal-fired boiler, applying computational fluid dynamics techniques to model boiler and burner design, has been carried out to investigate ways to optimize the combustion process for the lowest NOx formation and optimum CO/NO ratios. Results of this boiler and burner optimization work are reported. The paper further discusses catalyst scale-up considerations and the conceptual design of a 400 MWe size AF-SCR reactor, as well as economics analysis indicating large cost savings of the ammonia-free NOx control process over the current SCR technology.

  7. Effects of salt pond restoration on benthic flux: Sediment as a source of nutrients to the water column

    Science.gov (United States)

    Topping, Brent R.; Kuwabara, James S.; Carter, James L.; Garrettt, Krista K.; Mruz, Eric; Piotter, Sarah; Takekawa, John Y.

    2016-01-01

    Understanding nutrient flux between the benthos and the overlying water (benthic flux) is critical to restoration of water quality and biological resources because it can represent a major source of nutrients to the water column. Extensive water management commenced in the San Francisco Bay, Beginning around 1850, San Francisco Bay wetlands were converted to salt ponds and mined extensively for more than a century. Long-term (decadal) salt pond restoration efforts began in 2003. A patented device for sampling porewater at varying depths, to calculate the gradient, was employed between 2010 and 2012. Within the former ponds, the benthic flux of soluble reactive phosphorus and that of dissolved ammonia were consistently positive (i.e., moving out of the sediment into the water column). The lack of measurable nitrate or nitrite concentration gradients across the sediment-water interface suggested negligible fluxes for dissolved nitrate and nitrite. The dominance of ammonia in the porewater indicated anoxic sediment conditions, even at only 1 cm depth, which is consistent with the observed, elevated sediment oxygen demand. Nearby openestuary sediments showed much lower benthic flux values for nutrients than the salt ponds under resortation. Allochthonous solute transport provides a nutrient advective flux for comparison to benthic flux. For ammonia, averaged for all sites and dates, benthic flux was about 80,000 kg/year, well above the advective flux range of −50 to 1500 kg/year, with much of the variability depending on the tidal cycle. By contrast, the average benthic flux of soluble reactive phosphorus was about 12,000 kg/year, of significant magnitude, but less than the advective flux range of 21,500 to 30,000 kg/year. These benthic flux estimates, based on solute diffusion across the sediment-water interface, reveal a significant nutrient source to the water column of the pond which stimulates algal blooms (often autotrophic). This benthic source may be

  8. Ammonia and urea excretion in the swimming crab Portunus trituberculatus exposed to elevated ambient ammonia-N.

    Science.gov (United States)

    Ren, Qin; Pan, Luqing; Zhao, Qun; Si, Lingjun

    2015-09-01

    In the present study of the swimming crab Portunus trituberculatus exposed to 0, 1, and 5 mg L(-1) NH4Cl, the effects of ammonia exposure on ammonia and urea content in hemolymph; activity of H(+)-ATPase (subunit A) and Na(+)/K(+)-ATPase (α-subunit) (NKA) in gills; mRNA expression levels of the crustacean Rh-like ammonia transporter (Rh), K(+) Channel, Na(+)/K(+)/2Cl(-) co-transporter (NKCC), Na(+)/H(+)-exchanger (NHE), urea transporter (UT) and vesicle associated membrane protein (VAMP) in gills were investigated. The ultrastructure of gills was also evaluated. All these results in this study showed a dose-dependent effect with ammonia exposure concentration. The data displayed a significant increase in hemolymph ammonia and urea concentrations under ammonia exposure. The up-regulation of Rh mRNA together with up-regulation of K(+)-channel mRNA, NKA activity, down-regulation of NKCC and NHE mRNA suggested a coordinated protective response to maintain a relatively low ammonia concentration in the body fluids during ambient ammonia exposure. The up-regulation of VAMP, H(+)-ATPase activity along with the ultrastructure of gills suggested a mechanism of exocytotic ammonia excretion that may exit in the gill of P. trituberculatus. An increased production of urea and the up-regulated expression of UT suggested that the crab can detoxify elevated ammonia levels in the body fluids into urea when pathways of ammonia excretion are decreased after long term ammonia exposure.

  9. Distribution and Diversity of Archaeal Ammonia Monooxygenase Genes Associated with Corals▿ †

    OpenAIRE

    Beman, J. Michael; Roberts, Kathryn J.; Wegley, Linda; Rohwer, Forest; Francis, Christopher A.

    2007-01-01

    Corals are known to harbor diverse microbial communities of Bacteria and Archaea, yet the ecological role of these microorganisms remains largely unknown. Here we report putative ammonia monooxygenase subunit A (amoA) genes of archaeal origin associated with corals. Multiple DNA samples drawn from nine coral species and four different reef locations were PCR screened for archaeal and bacterial amoA genes, and archaeal amoA gene sequences were obtained from five different species of coral coll...

  10. High flux expansion divertor studies in NSTX

    CERN Document Server

    Soukhanovskii, V A; Bell, R E; Gates, D A; Kaita, R; Kugel, H W; LeBlanc, B P; Maqueda, R; Menard, J E; Mueller, D; Paul, S F; Raman, R; Roquemore, A L

    2009-01-01

    High flux expansion divertor studies have been carried out in the National Spherical Torus Experiment using steady-state X-point height variations from 22 to 5-6 cm. Small-ELM H-mode confinement was maintained at all X-point heights. Divertor flux expansions from 6 to 26-28 were obtained, with associated reduction in X-point connection length from 5-6 m to 2 m. Peak divertor heat flux was reduced from 7-8 MW/m$^2$ to 1-2 MW/m$^2$. In low X-point configuration, outer strike point became nearly detached. Among factors affecting deposition of parallel heat flux in the divertor, the flux expansion factor appeared to be dominant

  11. Ammonia synthesis from first principles calculations

    DEFF Research Database (Denmark)

    Honkala, Johanna Karoliina; Hellman, Anders; Remediakis, Ioannis;

    2005-01-01

    . When the size distribution of ruthenium particles measured by transmission electron microscopy was used as the [ink between the catalyst material and the theoretical treatment, the calculated rate was within a factor of 3 to 20 of the experimental rate. This offers hope for computer-based methods......The rate of ammonia synthesis over a nanoparticle ruthenium catalyst can be calculated directly on the basis of a quantum chemical treatment of the problem using density functional theory. We compared the results to measured rates over a ruthenium catalyst supported on magnesium aluminum spinet...

  12. Treatment of biomass to obtain fermentable sugars

    Science.gov (United States)

    Dunson, Jr., James B.; Tucker, Melvin; Elander, Richard; Hennessey, Susan M.

    2011-04-26

    Biomass is pretreated using a low concentration of aqueous ammonia at high biomass concentration. Pretreated biomass is further hydrolyzed with a saccharification enzyme consortium. Fermentable sugars released by saccharification may be utilized for the production of target chemicals by fermentation.

  13. Analysis on Ammonia Synthesis over Wuestite-Based Iron Catalyst

    Institute of Scientific and Technical Information of China (English)

    李小年; 刘化章; 等

    2003-01-01

    Wuestite-based catalyst for ammonia synthesis exhibits extremely high activity and easy to reduction under a wide range of conditions.The reaction kinetics of ammonia synthesis can be illustrated perfectly by both the classical Temkin-Pyzhev and modified Tecmkin equations with optimized α of 0.5,The pre-exponent factors and activation energies at the pressures of 8.0 and 15.0MPa are respectively κ0=1.09×1015,7.35×1014Pa0.5·s-1,and E=156.6,155.5kJ·mol-1 derived from the classical Temkin-Phyzhev equation,as well as k0=2.45×1014 ,1.83×1014Pa0.5·s-1,and E=147.7,147.2kJ·mol-1 derived from the modified Temkin equation.Although the degree of reduction under isothermal condition is primarily dependent upon temperature,low pressure seems to be imperative for reduction under high temperature and low space velocity to be considered as a high activity catalyst.The reduction behavior with dry feed gas can be illustrated perfectly by the shrinking-sphere-particle model,by which the reduction-rate constants of 4248exp(-71680/RT) and 644exp(-87260/RT) were obtained for the powder (0.045-0.054mm) and irregular shape(nominal diameter 3.17mm) catalysts respectively.The significant effect of particle size on reduction rate was observed,therefore,it is important to take into account the influence of particle size on reduction for the optimization of reduction process in industry.

  14. Kinetics of Chlorination of Benzophenone-3 in the Presence of Bromide and Ammonia.

    Science.gov (United States)

    Abdallah, Pamela; Deborde, Marie; Dossier Berne, Florence; Karpel Vel Leitner, Nathalie

    2015-12-15

    The aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia.

  15. Research on Ammonia Soaking of Calcine in Low-level Molybdenum Ore%低品位钼精矿焙砂的氨漫研究

    Institute of Scientific and Technical Information of China (English)

    邢楠楠

    2012-01-01

    The experiment studies the effect of the concentration of ammonia, time of ammonia soaking, the amount of ammonia, and the temperature of ammonia soaking on its leaching rate. The results show that after roasting lg of molybdate ore samples in the best conditions, the best leaching rate of 95.59percent is obtained with a ratio of ammonia to water of 1:1, an amount of ammonia of 4.0 mL, a soaking time of two hours, a soaking temperature of 60 ℃ and ammonia soaking at twice.%实验研究了氨水的浓度、氨水的用量、氨浸时间、温度对浸出率的影响。称取1g(精确到0.0001g)的矿样,经过最佳条件的焙烧后,最佳浸出条件是:氨水浓度为1:1,氨水用量是4.0mL,浸出时间为2小时,浸出温度为60℃,分2次浸取,浸出率为95.95%。

  16. Biofilter Treating Ammonia Gas Using Agricultural Residues Media

    Directory of Open Access Journals (Sweden)

    Thaniya Kaosol

    2012-01-01

    Full Text Available Problem statement: Agricultural residues such as manure and sugarcane bagasse are wastes from agro-industry which has low value and requires some sustainable waste management method. In this research, a mixture of manure fertilizer and sugarcane bagasse is used as a biofilter media for an ammonia gas removal application. The aim of this research is to study the ammonia gas removal efficiency of such media. Approach: The experiments were conducted in laboratory-scale biofilters. Two inlet ammonia gas concentrations were used which are 500 and 1,000 ppm. Three ratios of manure fertilizer and sugarcane bagasse were studied including 1:3, 1:5 and 1:7 by volume. All experiments were conducted for a period of 40 days. Two Empty Bed Retention Time (EBRT of these experiments were used which is 39s and 78s. The moisture content of the biofilter media was maintained at 45-60% by adding water. Results: The maximum ammonia gas removal efficiency at 89.93% is observed from the following conditions: 500 ppm of the inlet ammonia gas concentration, the manure fertilizer and sugarcane bagasse mixture ratio of 1:5 and the EBRT of 78s. The important factors of the ammonia gas removal in biofiltration process are the inlet ammonia gas concentration and the EBRT. Conclusion: The experimental results showed that the mixture of manure fertilizer and sugarcane bagasse is an effective biofilter media for ammonia gas removal applications. However, the biofilter is more effective at low inlet ammonia gas concentration, while the ratio of manure fertilizer and sugarcane bagasse has no significant effect on the ammonia gas removal efficiency. Therefore, using both residues as biofilter media for ammonia gas removal application is an alternative sustainable way to such manage argo-industry waste.

  17. Emergency planning and the acute toxic potency of inhaled ammonia.

    Science.gov (United States)

    Michaels, R A

    1999-08-01

    Ammonia is present in agriculture and commerce in many if not most communities. This report evaluates the toxic potency of ammonia, based on three types of data: anecdotal data, in some cases predating World War 1, reconstructions of contemporary industrial accidents, and animal bioassays. Standards and guidelines for human exposure have been driven largely by the anecdotal data, suggesting that ammonia at 5,000-10,000 parts per million, volume/volume (ppm-v), might be lethal within 5-10 min. However, contemporary accident reconstructions suggest that ammonia lethality requires higher concentrations. For example, 33,737 ppm-v was a 5-min zero-mortality value in a major ammonia release in 1973 in South Africa. Comparisons of secondary reports of ammonia lethality with original sources revealed discrepancies in contemporary sources, apparently resulting from failure to examine old documents or accurately translate foreign documents. The present investigation revealed that contemporary accident reconstructions yield ammonia lethality levels comparable to those in dozens of reports of animal bioassays, after adjustment of concentrations to human equivalent concentrations via U.S. Environmental Protection Agency (EPA) procedures. Ammonia levels potentially causing irreversible injury or impairing the ability of exposed people to escape from further exposure or from coincident perils similarly have been biased downwardly in contemporary sources. The EPA has identified ammonia as one of 366 extremely hazardous substances subject to community right-to-know provisions of the Superfund Act and emergency planning provisions of the Clean Air Act. The Clean Air Act defines emergency planning zones (EPZs) around industrial facilities exceeding a threshold quantity of ammonia on-site. This study suggests that EPZ areas around ammonia facilities can be reduced, thereby also reducing emergency planning costs, which will vary roughly with the EPZ radius squared.

  18. Video Meteor Fluxes

    Science.gov (United States)

    Campbell-Brown, M. D.; Braid, D.

    2011-01-01

    The flux of meteoroids, or number of meteoroids per unit area per unit time, is critical for calibrating models of meteoroid stream formation and for estimating the hazard to spacecraft from shower and sporadic meteors. Although observations of meteors in the millimetre to centimetre size range are common, flux measurements (particularly for sporadic meteors, which make up the majority of meteoroid flux) are less so. It is necessary to know the collecting area and collection time for a given set of observations, and to correct for observing biases and the sensitivity of the system. Previous measurements of sporadic fluxes are summarized in Figure 1; the values are given as a total number of meteoroids striking the earth in one year to a given limiting mass. The Gr n et al. (1985) flux model is included in the figure for reference. Fluxes for sporadic meteoroids impacting the Earth have been calculated for objects in the centimeter size range using Super-Schmidt observations (Hawkins & Upton, 1958); this study used about 300 meteors, and used only the physical area of overlap of the cameras at 90 km to calculate the flux, corrected for angular speed of meteors, since a large angular speed reduces the maximum brightness of the meteor on the film, and radiant elevation, which takes into account the geometric reduction in flux when the meteors are not perpendicular to the horizontal. They bring up corrections for both partial trails (which tends to increase the collecting area) and incomplete overlap at heights other than 90 km (which tends to decrease it) as effects that will affect the flux, but estimated that the two effects cancelled one another. Halliday et al. (1984) calculated the flux of meteorite-dropping fireballs with fragment masses greater than 50 g, over the physical area of sky accessible to the MORP fireball cameras, counting only observations in clear weather. In the micron size range, LDEF measurements of small craters on spacecraft have been used to

  19. PRETREATMENT AND FRACTIONATION OF CORN STOVER BY AMMONIA RECYCLE PERCOLATION PROCESS. (R831645)

    Science.gov (United States)

    Corn stover was pretreated with aqueous ammonia in a flow-through column reactor,a process termed as Ammonia Recycle Percolation (ARP). The aqueous ammonia causesswelling and efficient delignification of biomass at high temperatures. The ARPprocess solubilizes abou...

  20. High heat flux loop heat pipes

    Science.gov (United States)

    North, Mark T.; Sarraf, David B.; Rosenfeld, John H.; Maidanik, Yuri F.; Vershinin, Sergey

    1997-01-01

    Loop Heat Pipes (LHPs) can transport very large thermal power loads, over long distances, through flexible, small diameter tubes and against high gravitational heads. While recent LHPs have transported as much as 1500 W, the peak heat flux through a LHP's evaporator has been limited to about 0.07 MW/m2. This limitation is due to the arrangement of vapor passages next to the heat load which is one of the conditions necessary to ensure self priming of the device. This paper describes work aimed at raising this limit by threefold to tenfold. Two approaches were pursued. One optimized the vapor passage geometry for the high heat flux conditions. The geometry improved the heat flow into the wick and working fluid. This approach also employed a finer pored wick to support higher vapor flow losses. The second approach used a bidisperse wick material within the circumferential vapor passages. The bidisperse material increased the thermal conductivity and the evaporative surface area in the region of highest heat flux, while providing a flow path for the vapor. Proof-of-concept devices were fabricated and tested for each approach. Both devices operated as designed and both demonstrated operation at a heat flux of 0.70 MW/m2. This performance exceeded the known state of the art by a factor of more than six for both conventional heat pipes and for loop heat pipes using ammonia. In addition, the bidisperse-wick device demonstrated boiling heat transfer coefficients up to 100,000 W/m2.K, and the fine pored device demonstrated an orientation independence with its performance essentially unaffected by whether its evaporator was positioned above, below or level with the condenser.

  1. Ammonia Masers in W51: Interferometric Studies

    Science.gov (United States)

    Wilson, Thomas L.; Clarke, T. E.; Boboltz, D. A.; Henkel, C.; Mauersberger, R.; Wootten, H. A.; Broullet, N.; Baudry, A.; Despois, D.

    2014-01-01

    The galactic continuum sources W51D and W51e1e2 have been long recognized as remarkable centers of ammonia maser phenomena in the centimeter wavelength range. Henkel et al. (2013 A&A 549, A90) have measured 19 masers, of which 13 are newly found for W51-IRS2, otherwise known as W51D. These arise from inversion-rotation transitions. The single dish data were taken with the Effelsberg 100-m radio telescope of the MPIfR with an angular resolution of 43 arc seconds. The conclusion that these lines were caused by maser action is based on: (1) time variability, and (2) narrow linewidths. In addition, some lines showed systematic velocity variations. High brightness temperatures and compact sizes are needed to conclusively prove maser action. We have measured a sub-set of these ammonia lines with the C array of the Jansky-Very Large Array of the National Radio Astronomy Observatory in June 2013 with an angular resolution of better than 1 arc second. Source sizes, positions, excitation models and reasons why W51 shows such a plethora of masers will be presented.

  2. Nitrous oxide flux following tropical land clearing

    Science.gov (United States)

    Luizao, Flavio; Luizao, Regina; Matson, Pamela; Livingston, Gerald; Vitousek, Peter

    1989-01-01

    The importance of seasonal cycles of N2O flux from tropical ecosystems and the possibility that tropical deforestation could contribute to the ongoing global increase in N2O concentrations were assessed by measuring N2O flux from forest, cleared land, and pasture over an annual cycle in the central Amazon. A pasture that had been converted from tropical forest had threefold greater annual N2O flux than a paired forest site; similar results were obtained in spot measurements in other pastures. If these results are general, such tropical pastures represent a globally significant source of increased N2O.

  3. Controlled decoherence of floating flux qubits

    Institute of Scientific and Technical Information of China (English)

    Ji Ying-Hua; Xu Lin

    2010-01-01

    In Born-Markov approximation, this paper calculates the energy relaxation time T1 and the decoherence time T2 of a floating flux qubit by solving the set of Bloch-Redfield equations. It shows that there are two main factors influencing the floating flux qubits: coupling capacitor in the circuit and the environment resistor. It also discusses how to improvethe quantum coherence time of a qubit. Through shunt connecting/series connecting inductive elements, an inductive environment resistor is obtained and further the reactance component of the environment resistor is improved, which is beneficial to the enhancement of decoherence time of floating flux qubits.

  4. Diversity and quantity of ammonia-oxidizing Archaea and Bacteria in sediment of the Pearl River Estuary, China

    OpenAIRE

    Jin, Tao; ZHANG, Tong; Lin YE; Lee, On On; Wong, Yue Him; Qian, Pei Yuan

    2011-01-01

    The diversity and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the sediment of the Pearl River Estuary were investigated by cloning and quantitative real-time polymerase chain reaction (qPCR). From one sediment sample S16, 36 AOA OTUs (3% cutoff) were obtained from three clone libraries constructed using three primer sets for amoA gene. Among the 36 OTUs, six were shared by all three clone libraries, two appeared in two clone libraries, and the other 28...

  5. The dominant acetate degradation pathway/methanogenic composition in full-scale anaerobic digesters operating under different ammonia levels

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Karakashev, Dimitar Borisov; Angelidaki, Irini

    2014-01-01

    operating under different ammonia levels were sampled, and the residual biogas production was followed in fed-batch reactors. Acetate, labelled in the methyl group, was used to determine the methanogenic pathway by following the 14CH4 and 14CO2 production. Fluorescence in situ hybridisation was used...... to determine the methanogenic communities’ composition. Results obtained clearly demonstrated that syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis was the dominant pathway in all digesters with high ammonia levels (2.8–4.57 g NH4 +-N L−1), while acetoclastic methanogenic pathway...

  6. Modelling of ammonia emissions from dairy cow houses

    NARCIS (Netherlands)

    Monteny, G.J.

    2000-01-01

    Dairy cow husbandry contributes to environmental acidification through the emission of ammonia. In-depth knowledge on the processes and variable factors that play a role in the emission of ammonia from dairy cow houses benefits the production of emission data, the development of low emission housing

  7. Observations of ammonia in galactic H II regions

    Science.gov (United States)

    Vilas Boas, J. W. S.; Scalise, E., Jr.; Monteiro Do Vale, J. L.

    1988-02-01

    This paper presents the first results for the (J,K) = (1,1) and (2,2) ammonia transitions observed in the direction of some southern galactic H II regions, selected among the strongest H2CO emitters. Some physical parameters derived for each individual source, including several new sources of ammonia lines, are presented.

  8. Crystal Structure of an Ammonia-Permeable Aquaporin

    DEFF Research Database (Denmark)

    Kirscht, Andreas; Kaptan, Shreyas S; Bienert, Gerd Patrick;

    2016-01-01

    Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report th...

  9. Molecular physiology of the Rh ammonia transport proteins

    Science.gov (United States)

    Weiner, I. David; Verlander, Jill W.

    2013-01-01

    Purpose of review Recent studies have identified a new family of ammonia-specific transporters, Rh glycoproteins, which enable NH3-specific transport. The purpose of this review is to summarize recent evidence regarding the role of Rh glycoproteins in renal ammonia transport. Recent findings The Rh glycoproteins, RhAG/Rhag, RhBG/Rhbg and RhCG/Rhcg, transport ammonia in the form of molecular NH3, although there is some evidence suggesting the possibility of NH4+ transport. RhAG/Rhag is expressed only in erythrocytes, and not in the kidney. Rhbg and Rhcg are expressed in distal nephron sites, from the distal convoluted tubule through the inner medullary collecting duct, with basolateral Rhbg expression and both apical and basolateral Rhcg expression. Whether Rhbg contributes to renal ammonia transport remains controversial. Rhcg expression parallels ammonia excretion in multiple experimental models and genetic deletion studies, both global and collecting duct-specific, demonstrate a critical role for Rhcg in both basal and acidosis-stimulated renal ammonia excretion. X-ray crystallography has defined critical structural elements in Rh glycoprotein-mediated ammonia transport. Finally, Rh glycoproteins may also function as CO2 transporters. Summary No longer can NH3 transport be considered to occur only through diffusive NH3 movement. Transporter-mediated NH3 movement is fundamental to ammonia metabolism. PMID:20539225

  10. Dissociation and Mass Transfer Coefficients for Ammonia Volatilization Models

    Science.gov (United States)

    Process-based models are being used to predict ammonia emissions from manure sources, but their accuracy has not been fully evaluated for cattle manure. Laboratory trials were conducted to measure the dissociation and mass transfer coefficients for ammonia volatilization from media of buffered ammon...

  11. An infrared spectroscopy method to detect ammonia in gastric juice.

    Science.gov (United States)

    Giovannozzi, Andrea M; Pennecchi, Francesca; Muller, Paul; Balma Tivola, Paolo; Roncari, Silvia; Rossi, Andrea M

    2015-11-01

    Ammonia in gastric juice is considered a potential biomarker for Helicobacter pylori infection and as a factor contributing to gastric mucosal injury. High ammonia concentrations are also found in patients with chronic renal failure, peptic ulcer disease, and chronic gastritis. Rapid and specific methods for ammonia detection are urgently required by the medical community. Here we present a method to detect ammonia directly in gastric juice based on Fourier transform infrared spectroscopy. The ammonia dissolved in biological liquid samples as ammonium ion was released in air as a gas by the shifting of the pH equilibrium of the ammonium/ammonia reaction and was detected in line by a Fourier transform infrared spectroscopy system equipped with a gas cell for the quantification. The method developed provided high sensitivity and selectivity in ammonia detection both in pure standard solutions and in a simulated gastric juice matrix over the range of diagnostic concentrations tested. Preliminary analyses were also performed on real gastric juice samples from patients with gastric mucosal injury and with symptoms of H. pylori infection, and the results were in agreement with the clinicopathology information. The whole analysis, performed in less than 10 min, can be directly applied on the sample without extraction procedures and it ensures high specificity of detection because of the ammonia fingerprint absorption bands in the infrared spectrum. This method could be easily used with endoscopy instrumentation to provide information in real time and would enable the endoscopist to improve and integrate gastroscopic examinations.

  12. Method of treating ammonia-comprising waste water

    NARCIS (Netherlands)

    Van Loosdrecht, M.C.M.; Jetten, M.S.M.

    1998-01-01

    The invention relates to a method of treating ammonia-comprising waste water in which the bicarbonate ion is the counter ion of the ammonium ion present in the waste water. According to the invention half the ammonium is converted into nitrite, yielding an ammonia- and nitrite-containing solution, a

  13. Managing Ammonia Emissions From Screwworm Larval Rearing Media.

    Science.gov (United States)

    Sagel, Agustin; Phillips, Pamela; Chaudhury, Muhammad; Skoda, Steven

    2016-02-01

    Mass production, sterilization, and release of screwworms (Cochliomyia hominivorax (Coquerel)) that were competitive in the field significantly contributed to the successful application of the sterile insect technique for eradication of screwworms from continental North America. Metabolic byproducts resulting from protein-rich diets required for larval screwworms lead to ammonia liberation, sometimes at high levels, within the mass rearing facility. Until recently a sodium polyacrylate gel bulking agent was used for the larval media and adsorbed much of the ammonia. A need to replace the gel with an environmentally "friendly" bulking agent, while not increasing ammonia levels in the rearing facility, led to a series of experiments with the objective of developing procedures to reduce ammonia emissions from the larval media bulked with cellulose fiber. Additives of ammonia-converting bacteria, potassium permanganate, and Yucca schidigera Roezl ex Otrgies powder extract, previously reported to reduce ammonia levels in organic environments, were evaluated. Ammonia-converting bacteria did not have a positive effect. Addition of Y. schidigera powder extract (∼1% of total volume), potassium permanganate (∼250 ppm), and a combination of these two additives (at these same concentrations) kept ammonia at equivalent levels as when larval media was bulked with gel. Potassium permanganate also had sufficient antimicrobial properties that the use of formaldehyde in the diet was not necessary. Further testing is needed, at a mass rearing level, before full implementation into the screwworm eradication program.

  14. Bioluminescent bioreporter integrated circuit devices and methods for detecting ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Michael L [Knoxville, TN; Paulus, Michael J [Knoxville, TN; Sayler, Gary S [Blaine, TN; Applegate, Bruce M [West Lafayette, IN; Ripp, Steven A [Knoxville, TN

    2007-04-24

    Monolithic bioelectronic devices for the detection of ammonia includes a microorganism that metabolizes ammonia and which harbors a lux gene fused with a heterologous promoter gene stably incorporated into the chromosome of the microorganism and an Optical Application Specific Integrated Circuit (OASIC). The microorganism is generally a bacterium.

  15. Managing Ammonia Emissions From Screwworm Larval Rearing Media.

    Science.gov (United States)

    Sagel, Agustin; Phillips, Pamela; Chaudhury, Muhammad; Skoda, Steven

    2016-02-01

    Mass production, sterilization, and release of screwworms (Cochliomyia hominivorax (Coquerel)) that were competitive in the field significantly contributed to the successful application of the sterile insect technique for eradication of screwworms from continental North America. Metabolic byproducts resulting from protein-rich diets required for larval screwworms lead to ammonia liberation, sometimes at high levels, within the mass rearing facility. Until recently a sodium polyacrylate gel bulking agent was used for the larval media and adsorbed much of the ammonia. A need to replace the gel with an environmentally "friendly" bulking agent, while not increasing ammonia levels in the rearing facility, led to a series of experiments with the objective of developing procedures to reduce ammonia emissions from the larval media bulked with cellulose fiber. Additives of ammonia-converting bacteria, potassium permanganate, and Yucca schidigera Roezl ex Otrgies powder extract, previously reported to reduce ammonia levels in organic environments, were evaluated. Ammonia-converting bacteria did not have a positive effect. Addition of Y. schidigera powder extract (∼1% of total volume), potassium permanganate (∼250 ppm), and a combination of these two additives (at these same concentrations) kept ammonia at equivalent levels as when larval media was bulked with gel. Potassium permanganate also had sufficient antimicrobial properties that the use of formaldehyde in the diet was not necessary. Further testing is needed, at a mass rearing level, before full implementation into the screwworm eradication program. PMID:26468514

  16. Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

    DEFF Research Database (Denmark)

    Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

    Substrates that contain high ammonia levels can cause inhibition on anaerobic digestion process and unstable biogas production. The aim of the current study was to assess the effects of different ammonia levels on pure strains of (syntrophic acetate oxidizing) SAO bacteria and hydrogenotrophic...

  17. New technology for ammonia recovery from poultry litter

    Science.gov (United States)

    Abatement of gaseous ammonia in poultry houses is beneficial to both improve health/productivity of the birds and to reduce emissions into the environment surrounding the production facility. Current ammonia abatement technologies from poultry houses can be classified into four broad categories: 1) ...

  18. The excretion of isotope in urea and ammonia for estimating protein turnover in man with [15N]glycine

    International Nuclear Information System (INIS)

    Four normal adults were given [15N]-glycine in a single dose either orally or intravenously. Rates of whole-body protein turnover were estimated from the excretion of 15N in ammonia and in urea during the following 9 h. The rate derived from urea took account of the [15N]urea retained in body water. In postabsorptive subjects the rates of protein synthesis given by ammonia were equal to those from urea, when the isotope was given orally, but lower when an intravenous dose was given. In subjects receiving equal portions of food every 2 h rates of synthesis calculated from ammonia were much lower than those from urea whether an oral or intravenous isotope was given. Comparison of rates obtained during the postabsorptive and absorptive periods indicated regulation by food intake primarily of synthesis when measurements were made on urea, but regulation primarily of breakdown when measurements were made on ammonia. These inconsistencies suggest that changes in protein metabolism might be assessed better by correlating results given by different end-products, and it is suggested that the mean value given by urea and ammonia will be useful for this purpose. (author)

  19. Scavenging of ammonia by raindrops in Saturn's great storm clouds

    Science.gov (United States)

    Delitsky, M. L.; Baines, Kevin

    2016-10-01

    Observations of the great Saturn storms of 2010-2011 by Cassini instruments showed a very large depletion in atmospheric ammonia. While dynamics will play a role, the very high solubility of ammonia in water may be another important contributor to ammonia depletion in storms. Ammonia exists in Earth's atmosphere and rainstorms dissolve ammonia to a great degree, leaving almost no NH3 in the atmosphere. Studies by Elperin et al (2011, 2013) show that scavenging of ammonia is greatest as a rainstorm starts and lessens as raindrops fall, tapering off to almost zero by the time the rain reaches the ground (Elperin et al 2009). Ammonia is reaching saturation as it dissolves in the aqueous solution. As concentration increases, NH3 is then converted to aqueous species (NH3)x.(H2O)y (Max and Chapados 2013).Ammonia has the highest solubility in water compared to all other gases in the Saturn atmosphere. The Henry's Law constant for NH3 in water is 60 M/atm at 25 C. For H2S, it is 0.001 M/atm. In Saturn storms, it is "raining UP": As water-laden storm clouds convectively rise, ammonia gas will be scavenged and go into solution to a great degree, whilst all the other gases remain mostly in the gas phase. Aqueous ammonia acts as an antifreeze: if ammonia is dissolved in water cloud droplets to the limit of its solubility, as water droplets rise, they can stay liquid (and continue to scavenge NH3) to well below their normal freezing point of 0 Celsius (273 K). The freezing point for a 30 wt % water-ammonia solution is ~189 K. The pressure level where T = 189 K is at 2.8 bars. The normal freezing point of water occurs at the 9 bar pressure level in Saturn's atmosphere. 2.8 bars occurs at the -51 km altitude (below the 1 bar level). 9 bars is at the -130 km level: a difference of 79 km. A water droplet containing 30 wt% NH3 can move upwards from 9 bars to 2.8 bars (79 km) and still remain liquid, only freezing above that altitude. Calculations by the E-AIM model show that ammonia

  20. Alkaline Ammonia Electrolysis on Electrodeposited Platinum for Controllable Hydrogen Production.

    Science.gov (United States)

    Gwak, Jieun; Choun, Myounghoon; Lee, Jaeyoung

    2016-02-19

    Ammonia is beginning to attract a great deal of attention as an alternative energy source carrier, because clean hydrogen can be produced through electrolytic processes without the emission of COx . In this study, we deposited various shapes of Pt catalysts under potentiostatic mode; the electrocatalytic oxidation behavior of ammonia using these catalysts was studied in alkaline media. The electrodeposited Pt was characterized by both qualitative and quantitative analysis. To discover the optimal structure and the effect of ammonia concentration, the bulk pH value, reaction temperature, and applied current of ammonia oxidation were investigated using potential sweep and galvanostatic methods. Finally, ammonia electrolysis was conducted using a zero-gap cell, producing highly pure hydrogen with an energy efficiency over 80 %. PMID:26530809

  1. Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

    DEFF Research Database (Denmark)

    Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

    2015-01-01

    Ammonia-rich substrates can cause inhibition on anaerobic digestion process. Syntrophic acetate oxidizing bacteria (SAOB) and hydrogenotrophic methanogens are important for the ammonia inhibitory mechanism on anaerobic digestion. The roles and interactions of SAOB and hydrogenotrophic methanogens...... to ammonia inhibition effect are still unclear. The aim of the current study was to determine the ammonia toxicity levels of various pure strains of SAOB and hydrogenotrophic methanogens. Moreover, ammonia toxicity on the syntrophic cultivated strains of SAOB and hydrogenotrophic methanogens was tested. Thus......, four hydrogenotrophic methanogens (i.e. Methanoculleus bourgensis, Methanobacterium congolense, Methanoculleus thermophilus and Methanothermobacter thermautotrophicus), two SAOB (i.e. Tepidanaerobacter acetatoxydans and Thermacetogenium phaeum) and their syntrophic cultivation, were assessed under 0...

  2. Moisture insensitive adsorption of ammonia on resorcinol-formaldehyde resins.

    Science.gov (United States)

    Seredych, Mykola; Ania, Conchi; Bandosz, Teresa J

    2016-03-15

    Phenolic-formaldehyde resins aged at 85, 90 and 95°C were used as ammonia adsorbents at dynamic conditions in dry and moist air. To avoid pressure drops 10% bentonite was added as a binder. The initial and hybrid materials (before and after ammonia adsorption) were extensively characterized from the point of view of their porosity and surface chemistry. The results showed that the addition of the binder had various effects on materials' properties depending on the chemistry of their surface groups. When the phenolic acidic groups were predominant, the largest increase in surface acidity upon the addition of the binder was found. It was linked to the exfoliation of bentonite by polar moieties of the resins, which made acidic groups from aluminosilicate layers available for ammonia adsorption. On this sample, a relatively high amount of ammonia was strongly adsorbed in dry conditions. Insensitivity to moisture is a significant asset of ammonia adsorbents.

  3. Alkaline Ammonia Electrolysis on Electrodeposited Platinum for Controllable Hydrogen Production.

    Science.gov (United States)

    Gwak, Jieun; Choun, Myounghoon; Lee, Jaeyoung

    2016-02-19

    Ammonia is beginning to attract a great deal of attention as an alternative energy source carrier, because clean hydrogen can be produced through electrolytic processes without the emission of COx . In this study, we deposited various shapes of Pt catalysts under potentiostatic mode; the electrocatalytic oxidation behavior of ammonia using these catalysts was studied in alkaline media. The electrodeposited Pt was characterized by both qualitative and quantitative analysis. To discover the optimal structure and the effect of ammonia concentration, the bulk pH value, reaction temperature, and applied current of ammonia oxidation were investigated using potential sweep and galvanostatic methods. Finally, ammonia electrolysis was conducted using a zero-gap cell, producing highly pure hydrogen with an energy efficiency over 80 %.

  4. Ammonia emissions in Europe, part I: Development of a dynamical ammonia emission inventory

    Science.gov (United States)

    Backes, Anna; Aulinger, Armin; Bieser, Johannes; Matthias, Volker; Quante, Markus

    2016-04-01

    Nitrogen input from agricultural ammonia emissions into the environment causes numerous environmental and health problems. The purpose of this study is to present and evaluate an improved ammonia emission inventory based on a dynamical temporal parameterization suitable to compare and assess ammonia abatement strategies. The setup of the dynamical time profile (DTP) consists of individual temporal profiles for ammonia emissions, calculated for each model grid cell, depending on temperature, crop type, fertilizer and manure application, as well as on local legislation. It is based on the method of Skjøth et al., 2004 and Gyldenkærne et al., 2005. The method has been modified to cover the study area and to improve the performance of the emission model. To compare the results of the dynamical approach with the results of the static time profile (STP) the ammonia emission parameterizations have been implemented in the SMOKE for Europe emission model. Furthermore, the influence on secondary aerosol formation in the North Sea region and possible changes triggered through the use of a modified temporal distribution of ammonia emissions were analysed with the CMAQ chemistry transport model. The results were evaluated with observations of the European Monitoring and Evaluation Programme (EMEP). The correlation coefficient of NH3 improved significantly for 12 out of 16 EMEP measurement stations and an improvement in predicting the Normalized Mean Error can be seen for particulate NH4+ and NO3-. The prediction of the 95th percentile of the daily average concentrations has improved for NH3, NH4+ and NO3-. The NH3 concentration modelled with the STP is 157% higher in winter, and about 22% lower in early summer than the one modelled with the new DTP. Consequently, the influence of the DTP on the formation of secondary aerosols is particularly noticeable in winter, when the PM2.5 concentration is 25% lower in comparison to the use of STP for temporal disaggregation. Besides

  5. Understanding emissions of ammonia from buildings and application of fertilizers: an example from Poland

    Science.gov (United States)

    Werner, M.; Ambelas Skjøth, C.; Kryza, M.; Dore, A. J.

    2015-01-01

    A Europe-wide dynamic ammonia (NH3) emissions model has been applied for one of the large agricultural countries in Europe, and its sensitivity on the distribution of emissions among different agricultural functions was analysed by comparing with observed ammonia concentrations and by implementing all scenarios in a chemical transport model (CTM). The results suggest that the dynamic emission model is most sensitive to emission from animal manure, in particular how animal manure and its application on fields is connected to national regulations. In contrast, the model is most robust with respect to emission from buildings and storage. To incorporate the national regulations, we obtained activity information on agricultural operations at the sub-national level for Poland, information about infrastructure on storages, and current regulations on manure practice from Polish authorities. The information was implemented in the existing emission model and was connected directly with the NWP calculations from the Weather Research and Forecasting model (WRF-ARW). The model was used to calculate four emission scenarios with high spatial (5 km × 5 km) and temporal resolution (3 h) for the entire year 2010. In the four scenarios, we have compared the Europe-wide default model settings against (1) a scenario that focuses on emission from agricultural buildings, (2) the existing emission method used in WRF-Chem in Poland, and (3) a scenario that takes into account Polish infrastructure and agricultural regulations. The ammonia emission was implemented into the CTM FRAME and modelled ammonia concentrations was compared with measurements. The results suggest that the default setting in the dynamic model is an improvement compared to a non-dynamical emission profile. The results also show that further improvements can be obtained on the national scale by replacing the default information on manure practice with information that is connected with local practice and national

  6. Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

    Directory of Open Access Journals (Sweden)

    A. Salam

    2007-07-01

    Full Text Available The ice nucleation characteristics of montmorillonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric temperatures and relative humidities with a continuous flow diffusion chamber. The montmorillonite particles were exposed to pure (100% and diluted ammonia gas (25 ppm at room temperature in a stainless steel chamber. There was no significant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure ammonia gas exposure enhanced the ice nucleating fraction of montmorillonite mineral dust particles 3 to 8 times at 90% relative humidity with respect to water (RHw and 5 to 8 times at 100% RHw for 120 min exposure time compared to unexposed montmorillonite within our experimental conditions. The percentages of active ice nuclei were 2 to 8 times higher at 90% RHw and 2 to 7 times higher at 100% RHw in 25 ppm ammonia exposed montmorillonite compared to unexposed montmorillonite. All montmorillonite particles are more efficient as ice nuclei with increasing relative humidities and decreasing temperatures. The activation temperature of montmorillonite exposed to 100% pure ammonia was 15°C higher than for unexposed montmorillonite particles at 90% RHw. In the 25 ppm ammonia exposed montmorillonite experiments, the activation temperature was 10°C warmer than unexposed montmorillonite at 90% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmorillonite mineral dust particles suggesting that the ammonia is chemically bound to the montmorillonite particle. This is the first experimental evidence that ammonia gas exposed montmorillonite mineral dust particles can enhance its activation as ice nuclei and that the activation can occur at temperatures warmer than –10°C where natural atmospheric ice nuclei are very scarce.

  7. Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant

    NARCIS (Netherlands)

    Sauder, L.A.; Peterse, F.; Schouten, S.; Neufeld, J.D.

    2012-01-01

    The first step of nitrification is catalysed by both ammonia-oxidizing bacteria (AOB) and archaea (AOA), but physicochemical controls on the relative abundance and function of these two groups are not yet fully understood, especially in freshwater environments. This study investigated ammonia-oxidiz

  8. Field inter-comparison of eleven atmospheric ammonia measurement techniques

    Directory of Open Access Journals (Sweden)

    K. von Bobrutzki

    2009-08-01

    Full Text Available Eleven instruments for the measurement of ambient concentrations of atmospheric ammonia gas (NH3, based on eight different measurement methods were inter-compared above an intensively managed agricultural field in late summer 2008 in S. Scotland. To test the instruments over a wide range of concentrations, the field was fertilised with urea midway through the experiment, leading to an increase in the average concentration from 10 to 100 ppbv. The instruments deployed included three wet-chemistry systems, one with offline analysis (annular rotating batch denuder, RBD and two with online-analysis (Annular Denuder sampling with online Analysis, AMANDA; AiRRmonia, two Quantum Cascade Laser Absorption Spectrometers (a large-cell dual system, DUAL-QCLAS, and a compact system, c-QCLAS, two photo-acoustic spectrometers (WaSul-Flux, Nitrolux-100, a Cavity Ring Down Spectrosmeter (CRDS, a Chemical Ionisation Mass Spectrometer (CIMS, an ion mobility spectrometer (IMS and an Open-Path Fourier Transform Infra-Red (OP-FTIR spectroscopy. Each instrument was compared with each other and with the average concentration of all instruments. An overall good agreement of hourly average concentrations between the instruments (R2>0.84, was observed for NH3 concentrations at the field of up to 120 ppbv with the slopes against the average ranging from 0.67 (DUAL-QCLAS to 1.13 (AiRRmonia with intercepts of –0.74 ppbv (RBD to +2.69 ppbv (CIMS. More variability was found for performance for lower concentrations (<10 ppbv. Here the overruling factors affecting measurement precision are (a the inlet design, (b the state of inlet filters (where applicable, and (c the quality of gas-phase standards (where applicable. By reference to the fast (1 Hz instruments deployed during the study, it was possible to characterize the response times of the slower instruments.

  9. A miniDOAS instrument optimised for ammonia field measurements

    Science.gov (United States)

    Sintermann, Jörg; Dietrich, Klaus; Häni, Christoph; Bell, Michael; Jocher, Markus; Neftel, Albrecht

    2016-06-01

    We present a differential optical absorption spectroscopy (DOAS) instrument, called "miniDOAS", optimised for optical open-path field-measurements of ambient ammonia (NH3) alongside nitrogen oxide (NO) and sulfur dioxide (SO2). The instrument is a further development of the miniDOAS presented by Volten et al. (2012). We use a temperature-controlled spectrometer, a deuterium light source and a modified optical arrangement. The system was set up in a robust, field-deployable, temperature-regulated housing. For the evaluation of light spectra we use a new high-pass filter routine based upon robust baseline extraction with local regression. Multiple linear regression including terms of an autoregressive-moving-average model is used to determine concentrations. For NH3 the random uncertainty is about 1.4 % of the concentration, and not better than 0.2 µg m-3. Potential biases for the slope of the calibration are given by the precision of the differential absorption cross sections (±3 %) and for the offset by the precision of the estimation of concentration offsets (cref) introduced by the reference spectrum Iref. Comparisons of miniDOAS measurements to those by NH3 acid trap devices showed good agreement. The miniDOAS can be flexibly used for a wide range of field trials, such as micrometeorological NH3 flux measurements with approaches based upon horizontal or vertical concentration differences. Results from such applications covering concentration dynamics of less than one up to several hundreds of µg m-3 are presented.

  10. Dynamics of ammonia exchange with cut grassland: strategy and implementation of the GRAMINAE Integrated Experiment

    Directory of Open Access Journals (Sweden)

    M. A. Sutton

    2008-08-01

    Full Text Available A major international experiment on ammonia (NH3 biosphere-atmosphere exchange was conducted over intensively managed grassland at Braunschweig, Germany. The experimental strategy was developed to allow an integrated analysis of different features of NH3 exchange including: a quantification of nearby emissions and advection effects, b estimation of net NH3 fluxes with the canopy by a range of micrometeorological measurements, c analysis of the sources and sinks of NH3 within the plant canopy, including soils and bioassay measurements, d comparison of the effects of grassland management options on NH3 fluxes and e assessment of the interactions of NH3 fluxes with aerosol exchange processes. Additional technical objectives included the inter-comparison of different estimates of sensible and latent heat fluxes, as well as continuous-gradient and Relaxed Eddy Accumulation (REA systems for NH3 fluxes.

    The prior analysis established the spatial and temporal design of the experiment, allowing significant synergy between these objectives. The measurements were made at 7 measurement locations, thereby quantifying horizontal and vertical profiles, and covered three phases: a tall grass canopy prior to cutting (7 days, b short grass after cutting (7 days and c re-growing sward following fertilization with ammonium nitrate (10 days. The sequential management treatments allowed comparison of sources-sinks, advection and aerosol interactions under a wide range of NH3 fluxes.

    This paper describes the experimental strategy and reports the grassland management history, soils, environmental conditions and air chemistry during the experiment, finally summarizing how the results are coordinated in the accompanying series of papers.

  11. Projecting Ammonia Dry Deposition Using Passive Samplers and a Bi-Directional Exchange Model

    Science.gov (United States)

    Robarge, W. P.; Walker, J. T.; Austin, R. E.

    2011-12-01

    Animal agriculture within the United States is known to be a source of ammonia (NH3) emissions. Dry deposition of NH3 to terrestrial ecosystems immediately surrounding large local sources of NH3 emissions (e.g. animal feeding operations) is difficult to measure, and is best estimated via models. Presented here are results for a semi-empirical modeling approach for estimating air-surface exchange fluxes of NH3 downwind of a large poultry facility (~ 3.5 million layers) using a bi-directional air-surface exchange model. The modeling domain is the western section of the Pocosin Lakes National Wildlife Refuge in Tyrrell, Washington, and Hyde Counties of eastern North Carolina in the South Atlantic Coastal Plain physiographic region. Vegetation within the modeling domain is primarily pocosin wetlands, characterized by acid (pH 3.6) peat soils and a thick canopy of shrub vegetation (leatherwood (Cyrilla racemiflora), inkberry (Ilex glabra), wax myrtle (Morella cerifera)). Land surrounding the refuge is primarily used for crop production: ~ 28%, 24%, and 45% agricultural in Tyrell, Hyde, and Washington counties, respectively. Ammonia air-surface exchange (flux) was calculated using a two-layer canopy compensation point model developed by Nemitz et al. (2001. Quart. J. Roy. Met. Soc. 127, 815 - 833.) as implemented by Walker et al. (2008. Atmos. Environ., 42, 3407 - 3418.), in which the competing processes of emission and deposition within the foliage-soil system were taken into account by relating the net canopy-scale NH3 flux to the net emission potential of the canopy (i.e., foliage and soil). Ammonia air concentrations were measured using ALPHA passive samplers (Center for Ecology and Hydrology, Edinburgh) along transects to the north and northeast of the poultry facility at distances of 800, 2000 and 3200 m, respectively. Samplers were deployed in duplicate at each location at a height of 5.8 m from July 2008 to July 2010 weekly during warm months and bi-weekly curing

  12. Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway.

    Science.gov (United States)

    Lovelock, Sarah L; Lloyd, Richard C; Turner, Nicholas J

    2014-04-25

    Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1 cB elimination mechanism.

  13. Effects of total ammonia nitrogen concentration on solid-state anaerobic digestion of corn stover.

    Science.gov (United States)

    Wang, Zhongjiang; Xu, Fuqing; Li, Yebo

    2013-09-01

    The inhibitive effect of total ammonia nitrogen (TAN) (including NH3 and NH4(+)) on solid-state anaerobic digestion of corn stover was investigated in batch reactors at 37°C. The highest methane yield of 107.0 L/kg VS(feed) was obtained at a TAN concentration of 2.5 g/kg (based on total weight). TAN concentrations greater than 2.5 g/kg resulted in decreased methane yields, with a 50% reduction observed at a concentration of 6.0 g/kg. Reduced reaction rates and microbial activities for hydrolysis of cellulose and methanogenesis from acetate were observed at TAN concentrations higher than 4.3 g/kg. Strong ammonia stress was indicated at butyrate concentrations higher than 300 mg/kg. Result showed that the effluent of liquid anaerobic digestion can provide enough nitrogen for solid-state anaerobic digestion of corn stover.

  14. Gas sensors based on carbon nanoflake/tin oxide composites for ammonia detection.

    Science.gov (United States)

    Lee, Soo-Keun; Chang, Daeic; Kim, Sang Wook

    2014-03-15

    Carbon nanoflake (CNFL) was obtained from graphite pencil by using the electrochemical method and the CNFL/SnO2 composite material assessed its potential as an ammonia gas sensor. A thin film resistive gas sensor using the composite material was manufactured by the drop casting method, and the sensor was evaluated to test in various ammonia concentrations and operating temperatures. Physical and chemical characteristics of the composite material were assessed using SEM, TEM, SAED, EDS and Raman spectroscopy. The composite material having 10% of SnO2 showed 3 times higher sensor response and better repeatability than the gas sensor using pristine SnO2 nano-particle at the optimal temperature of 350°C.

  15. Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

    Science.gov (United States)

    Kumar, Ramesh; Kaur, Amarjeet

    2016-05-01

    The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm-1 respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp2 hybridisation of carbon atoms at 1560 cm-1. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such as methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.

  16. Characterization of FeCo based catalyst for ammonia decomposition. The effect of potassium oxide

    Directory of Open Access Journals (Sweden)

    Lendzion-Bieluń Zofia

    2014-12-01

    Full Text Available FeCo fused catalyst was obtained by fusing iron and cobalt oxides with an addition of calcium, aluminium, and potassium oxides (CaO, Al2O3, K2O. An additional amount of potassium oxide was inserted by wet impregnation. Chemical composition of the prepared catalysts was determined with an aid of the XRF method. On the basis of XRD analysis it was found that cobalt was built into the structure of magnetite and solid solution of CoFe2O4 was formed. An increase in potassium content develops surface area of the reduced form of the catalyst, number of adsorption sites for hydrogen, and the ammonia decomposition rate. The nitriding process of the catalyst slows down the ammonia decomposition.

  17. Directed flux motor

    Science.gov (United States)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2011-01-01

    A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

  18. The kinetic temperature of a molecular cloud at redshift 0.9: Ammonia in the gravitational lens PKS1830-211

    CERN Document Server

    Henkel, C; Menten, K M; Ott, J

    2008-01-01

    Using the Green Bank Telescope (GBT), we have detected the (J,K) = (1,1) to (10,10) ammonia inversion lines, up to 1030 K above the ground state, in a face-on spiral galaxy viewed against the radio continuum of the lensed background source PKS 1830-211. The ammonia absorption lines, seen at redshift 0.886, appear to be optically thin with absolute peak flux densities up to 2.5 percent of the total continuum of the background source. Measured intensities are consistent with a kinetic temperature of 80 K for 80-90 percent of the ammonia column. The remaining gas is warmer, reaching at least 600 K. Column density and fractional abundance are of order (5-10) x 10^14 cm^-2 and (1.5-3.0) x 10^-8. Similarities with a hot ammonia absorption component observed toward the Sgr B2 region close to the Galactic center may suggest that the Sgr B2 component also originates from warm diffuse low-density molecular gas. The warm ammonia column observed toward PKS 1830-211 is unique in the sense that it originates in a spiral ar...

  19. Effect of including corner point fluxes on the pin power reconstruction using nodal point flux scheme

    International Nuclear Information System (INIS)

    Highlights: • Including corner fluxes improve pin power reconstruction. • The maximum errors in pin power reconstruction occur in the peripheral water region. • The errors are significantly less in the fuel region. • MSS predictions for corner pin flux are preferable. - Abstract: Although there have been well established transport based codes for core neutronics analysis, it is yet impractical to implement them in the real core treatment because their performance is not so great on ordinary server computers. For this reason, most of neutronics codes for core calculation are subject to two steps calculation procedure which consists of homogenized group constant generation and flux distribution generation which is the main concern of this work. This paper brings out a 2 dimensional nodal code based on point flux algorithm and implements two schemes for pin power reconstruction. In the first scheme, pin power reconstruction is obtained without considering corner point fluxes in the fuel assemblies but in the second method corner fluxes are included to assess their effect on pin power reconstruction. To obtain corner point fluxes, Smith’s procedure and the method of successive smoothing are used. Improvement in pin power reconstruction by including fuel assembly corner fluxes is illustrated in this paper and assessed by Monte Carlo simulation

  20. Influence of ammonia state on particle characterization of magnesium hydroxide prepared via ammonia method%氨状态对氨法制备氢氧化镁颗粒性质的影响

    Institute of Scientific and Technical Information of China (English)

    姚建平; 范天博; 王健; 李雪; 刘云义

    2012-01-01

    Ammonia method is one of the main methods to prepare magnesium hydroxide, and according to the different states of ammonia into the reaction system, ammonia method includes aqua ammonia precipitation method and gaseous ammonia precipitation method. In order to study the influence of ammonia in different states on particle characterization of magnesium hydroxide, magnesium chloride was used as reaction material, magnesium hydroxide were prepared respectively with aqua ammonia and gaseous ammonia as precipitant. Scanning electron microscope (SEM) , X-ray powder diffraction (XRD) and laser particle size analyzer were used to characterize the products. The results showed that crystal forms of the magnesium hydroxide products obtained by these two methods both tended to be perfect with increasing reaction temperature, and the dispersion property was also improved. Magnesium hydroxide prepared by gaseous ammonia precipitation method presented inerratic cubic pieces (hexahedron structure) when reaction temperature was higher than 75℃ , the dispersion property of the particles were better than those prepared by aqua ammonia precipitation method. Aqua ammonia concentration was also a significant factor affecting the morphology of magnesium hydroxide, and the particle size and dispersion property would gradually become close to the products of gaseous ammonia precipitation method with increasing aqua ammonia concentration. This work provided valuable reference for selection and application of ammoniaprecipitation method to prepare magnesium hydroxide.%氨法是制备氢氧化镁的主要方法之一,根据氨进入反应体系状态不同分为氨水法和氨气法两种工艺.为了确定氨水与氨气对氢氧化镁颗粒性质的影响,以氯化镁为原料,分别以氨水和氨气为沉淀剂制备氢氧化镁,并利用扫描电镜(SEM)、X射线衍射(XRD)、激光粒度分布仪对产品进行了表征.结果表明:两种沉淀剂制备的氢氧化镁颗粒晶型

  1. Regeneration of ammonia borane spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Andrew David [Los Alamos National Laboratory; Davis, Benjamin L [Los Alamos National Laboratory; Gordon, John C [Los Alamos National Laboratory

    2009-01-01

    A necessary target in realizing a hydrogen (H{sub 2}) economy, especially for the transportation sector, is its storage for controlled delivery, presumably to an energy producing fuel cell. In this vein, the U.S. Department of Energy's Centers of Excellence (CoE) in Hydrogen Storage have pursued different methodologies, including metal hydrides, chemical hydrides, and sorbents, for the expressed purpose of supplanting gasoline's current > 300 mile driving range. Chemical H{sub 2} storage has been dominated by one appealing material, ammonia borane (H{sub 3}N-BH{sub 3}, AB), due to its high gravimetric capacity of H{sub 2} (19.6 wt %) and low molecular weight (30.7 g mol{sup -1}). In addition, AB has both hydridic and protic moieties, yielding a material from which H{sub 2} can be readily released in contrast to the loss of H{sub 2} from C{sub 2}H{sub 6} which is substantially endothermic. As such, a number of publications have described H{sub 2} release from amine boranes, yielding various rates depending on the method applied. The viability of any chemical H{sub 2} storage system is critically dependent on efficient recyclability, but reports on the latter subject are sparse, invoke the use of high energy reducing agents, and suffer from low yields. Our group is currently engaged in trying to find and fully demonstrate an energy efficient regeneration process for the spent fuel from H{sub 2} depleted AB with a minimum number of steps. Although spent fuel composition depends on the dehydrogenation method, we have focused our efforts on the spent fuel resulting from metal-based catalysis, which has thus far shown the most promise. Metal-based catalysts have produced the fastest rates for a single equivalent of H{sub 2} released from AB and up to 2.5 equiv. of H{sub 2} can be produced within 2 hours. While ongoing work is being carried out to tailor the composition of spent AB fuel, a method has been developed for regenerating the predominant product

  2. Ammonia-Free NOx Control System

    Energy Technology Data Exchange (ETDEWEB)

    S. Wu

    2003-12-31

    Research is being conducted under United States Department of Energy (DOE) Contract DEFC26-03NT41865 to develop a new technology to achieve very low levels of NOx emissions from pulverized coal fired boiler systems by employing a novel system level integration between the PC combustion process and the catalytic NOx reduction with CO present in the combustion flue gas. The combustor design and operating conditions will be optimized to achieve atypical flue gas conditions. This approach will not only suppress NOx generation during combustion but also further reduce NOx over a downstream catalytic reactor that does not require addition of an external reductant, such as ammonia. This report describes the work performed during the October 1 to December 31, 2003 time period.

  3. Ammonia-Free NOx Control System

    Energy Technology Data Exchange (ETDEWEB)

    Song Wu; Zhen Fan; Andrew H. Seltzer; Richard G. Herman

    2004-09-30

    Research is being conducted under United States Department of Energy (DOE) Contract DEFC26-03NT41865 to develop a new technology to achieve very low levels of NOx emissions from pulverized coal fired boiler systems by employing a novel system level integration between the PC combustion process and the catalytic NOx reduction with CO present in the combustion flue gas. The combustor design and operating conditions will be optimized to achieve atypical flue gas conditions. This approach will not only suppress NOx generation during combustion but also further reduce NOx over a downstream catalytic reactor that does not require addition of an external reductant, such as ammonia. This report describes the work performed during the July 1 to September 30, 2004 time period.

  4. Ammonia Thermometry of Star Forming Galaxies

    CERN Document Server

    Mangum, Jeffrey G; Henkel, Christian; Menten, Karl M; MacGregor, Meredith; Svoboda, Brian E; Schinnerer, Eva

    2013-01-01

    With a goal toward deriving the physical conditions in external galaxies, we present a study of the ammonia (NH$_3$) emission and absorption in a sample of star forming systems. Using the unique sensitivities to kinetic temperature afforded by the excitation characteristics of several inversion transitions of NH$_3$, we have continued our characterization of the dense gas in star forming galaxies by measuring the kinetic temperature in a sample of 23 galaxies and one galaxy offset position selected for their high infrared luminosity. We derive kinetic temperatures toward 13 galaxies, 9 of which possess multiple kinetic temperature and/or velocity components. Eight of these galaxies exhibit kinetic temperatures $>100$ K, which are in many cases at least a factor of two larger than kinetic temperatures derived previously. Furthermore, the derived kinetic temperatures in our galaxy sample, which are in many cases at least a factor of two larger than derived dust temperatures, point to a problem with the common a...

  5. Ammonia-Free NOx Control System

    Energy Technology Data Exchange (ETDEWEB)

    S. Wu; Z. Fan; R. Herman

    2004-03-31

    Research is being conducted under United States Department of Energy (DOE) Contract DEFC26-03NT41865 to develop a new technology to achieve very low levels of NOx emissions from pulverized coal fired boiler systems by employing a novel system level integration between the PC combustion process and the catalytic NOx reduction with CO present in the combustion flue gas. The combustor design and operating conditions will be optimized to achieve atypical flue gas conditions. This approach will not only suppress NOx generation during combustion but also further reduce NOx over a downstream catalytic reactor that does not require addition of an external reductant, such as ammonia. This report describes the work performed during the January 1 to March 31, 2004 time period.

  6. Towards an ammonia-mediated hydrogen economy?

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Johannessen, Tue; Sørensen, Rasmus Zink;

    2006-01-01

    Materialization of a hydrogen economy could provide a solution to significant global challenges, In particular. the possibility of improving the efficiency and simultaneously minimizing the environmental impact of energy conversion processes, together with the opportunity to reduce the dependency...... of fossil fuels, are main drivers for the currently increasing research and development efforts. However. significant technological breakthroughs are necessary for making a hydrogen economy feasible. In particular, it is necessary to develop appropriate hydrogen storage and transportation technologies....... Recently, metal ammine salts were proposed as safe, reversible. high-density and low-cost hydrogen carriers. Here, we discuss how this development could provide a platform for using ammonia as a fuel for the hydrogen economy, We do that by comparing various possible hydrogen carriers with respect to energy...

  7. Relation of middle molecules levels and oxidative stress to erythropoietin requirements in high-flux versus low-flux hemodialysis

    Directory of Open Access Journals (Sweden)

    Hala S El-Wakil

    2013-01-01

    Full Text Available The objective of this study is to investigate the serum beta-2-microglobulin (B2MG and advanced oxidation protein products (AOPP as middle molecule uremic toxins and protein carbonyl (PCO as oxidative stress marker in uremic patients undergoing high-flux versus low-flux hemodialysis (HD and to correlate their levels to the erythropoietin requirements for those patients. Twenty patients on chronic low-flux HD were recruited in the study. At the start of the study, all patients underwent high-flux HD for eight weeks, followed by low-flux HD for two weeks as a washout period. The patients were then subjected to another eight weeks of low-flux HD. Blood samples were obtained at the beginning and at the end of the high-flux period and the low-flux period. The mean erythropoietin dose for patients using high-flux HD was significantly lower than that for low-flux HD (P = 0.0062. Post-high flux, the B2MG and PCO levels were significantly lower than the pre-high-flux levels (P = 0.026 and 0.0005, respectively, but no significant change was observed in AOPP (P = 0.68. Post-low flux, the B2MG, AOPP and PCO were significantly higher than the pre-low-flux levels (P = 0.0002, 0.021 and <0.0001, respectively. Post-low flux, the B2MG and PCO were significantly higher than the post-high-flux levels (P <0.0001, but no significant difference was observed in AOPP (P = 0.11. High-flux HD results in reduction of some of the middle molecule toxins and PCO levels better than low-flux HD, and is associated with a better response to erythropoietin.

  8. Understanding emissions of ammonia from buildings and application of fertilizers: an example from Poland

    Directory of Open Access Journals (Sweden)

    M. Werner

    2015-01-01

    To incorporate the national regulations, we obtained activity information on agricultural operations at the sub-national level for Poland, information about infrastructure on storages, and current regulations on manure practice from Polish authorities. The information was implemented in the existing emission model and was connected directly with the NWP calculations from the Weather Research and Forecasting model (WRF-ARW. The model was used to calculate four emission scenarios with high spatial (5 km × 5 km and temporal resolution (3 h for the entire year 2010. In the four scenarios, we have compared the Europe-wide default model settings against (1 a scenario that focuses on emission from agricultural buildings, (2 the existing emission method used in WRF-Chem in Poland, and (3 a scenario that takes into account Polish infrastructure and agricultural regulations. The ammonia emission was implemented into the CTM FRAME and modelled ammonia concentrations was compared with measurements. The results suggest that the default setting in the dynamic model is an improvement compared to a non-dynamical emission profile. The results also show that further improvements can be obtained on the national scale by replacing the default information on manure practice with information that is connected with local practice and national regulations. Implementing a dynamical approach for simulation of ammonia emission is a viable objective for all CTM models that continue to use fixed emission profiles. Such models should handle ammonia emissions in a similar way to other climate-dependent emissions (e.g. biogenic volatile organic compounds. Our results, compared with previous results from the DEHM and the GEOS-CHEM models, suggest that implementing dynamical approaches improves simulations in general, even in areas with limited information about the location of the agricultural fields, livestock and agricultural production methods such as Poland.

  9. Paecilomyces variotii: A Fungus Capable of Removing Ammonia Nitrogen and Inhibiting Ammonia Emission from Manure

    Science.gov (United States)

    Liu, Zhiyun; Liu, Guohua; Cai, Huiyi; Shi, Pengjun; Chang, Wenhuan; Zhang, Shu; Zheng, Aijuan; Xie, Qing; Ma, Jianshuang

    2016-01-01

    Ammonia (NH3) emissions from animal manure are a significant environmental and public concern. Despite the numerous studies regarding NH3 emissions from manure, few of them have considered microbial nitrification approaches, especially fungal nitrification. In this study, a filamentous fungus was isolated from chicken manure and was used for nitrification. The species was Paecilomyces variotii by morphological characteristics and 18S rDNA gene sequencing. It played the biggest role in the removal of ammonium at pH 4.0–7.0, C/N ratio of 10–40, temperature of 25–37°C, shaking speed of 150 rpm, and with glucose as the available carbon source. Further analysis revealed that all ammonium was removed when the initial ammonium concentration was less than 100 mg/L; 40% ammonium was removed when the initial ammonium concentration was 1100 mg/L. The results showed that the concentration of ammonia from chicken manure with strain Paecilomyces variotii was significantly lower than that in the control group. We concluded that Paecilomyces variotii has good potential for future applications in in situ ammonium removal as well as ammonia emissions control from poultry manure. PMID:27348533

  10. Nitrous Oxide Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Nitrous Oxide (N20) flux is the net rate of nitrous oxide exchange between an ecosystem and the atmosphere. Data of this variable were generated by the USGS...

  11. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  12. Aeronet Solar Flux

    Data.gov (United States)

    National Aeronautics and Space Administration — SolRad-Net (Solar Radiation Network) is an established network of ground-based sensors providing high-frequency solar flux measurements in quasi-realtime to the...

  13. Flux in Tallinn

    Index Scriptorium Estoniae

    2004-01-01

    Rahvusvahelise elektroonilise kunsti sümpoosioni ISEA2004 klubiõhtu "Flux in Tallinn" klubis Bon Bon. Eestit esindasid Ropotator, Ars Intel Inc., Urmas Puhkan, Joel Tammik, Taavi Tulev (pseud. Wochtzchee). Klubiõhtu koordinaator Andres Lõo

  14. An alternative method for the measurement of neutron flux

    Indian Academy of Sciences (India)

    Rupa Sarkar; Prasanna Kumar Mondal; Barun Kumar Chatterjee

    2015-10-01

    A simple and easy method for measuring the neutron flux is presented. This paper deals with the experimental verification of neutron dose rate–flux relationship for a non-dissipative medium. Though the neutron flux cannot be obtained from the dose rate in a dissipative medium, experimental result shows that for non-dissipative medium one can obtain the neutron flux from dose rate. We have used a 241 AmBe neutron source for neutron irradiation, and the neutron dose rate and count rate were measured using a NM2B neutron monitor and R-12 superheated droplet detector (SDD), respectively. Here, the neutron flux inferred from the neutron count rate obtained with R-12 SDD shows an excellent agreement with the flux inferred from the neutron dose rate in a non-dissipative medium.

  15. Flux Emergence (Theory

    Directory of Open Access Journals (Sweden)

    Mark C. M. Cheung

    2014-07-01

    Full Text Available Magnetic flux emergence from the solar convection zone into the overlying atmosphere is the driver of a diverse range of phenomena associated with solar activity. In this article, we introduce theoretical concepts central to the study of flux emergence and discuss how the inclusion of different physical effects (e.g., magnetic buoyancy, magnetoconvection, reconnection, magnetic twist, interaction with ambient field in models impact the evolution of the emerging field and plasma.

  16. Effect of ammonia stress on nitrogen metabolism of Ceratophyllum demersum.

    Science.gov (United States)

    Gao, Jingqing; Li, Linshuai; Hu, Zhiyuan; Yue, Hui; Zhang, Ruiqin; Xiong, Zhiting

    2016-01-01

    The objective of the present study was to determine the effect of total ammonia N concentration and pH on N metabolism of Ceratophyllum demersum and to evaluate stress as a result of inorganic N enrichment in the water column on submerged macrophytes. Carefully controlled pH values distinguished between the effects of un-ionized NH3 and ionized NH4(+). The results showed that the most obvious consequence of ammonia addition was an overall increase in ammonia content and decrease in nitrate content in all tissues of fertilized plants. The activities of nitrate reductase and glutamine synthetase were inhibited by long-term ammonia addition. At the same time, ammonia addition significantly decreased soluble protein content and increased free amino acid content in all treatments. Another clear effect of ammonia addition was a decrease in carbon reserves. Therefore, the authors concluded that increased ammonia availability could affect plant survival and lead to a decline in C. demersum proliferation through a decrease in their carbon reserves. This interaction between N and C metabolism helps to explain changes in benthic vegetation as a result of steadily increasing coastal water eutrophication.

  17. Mathematical Model of Ammonia Handling in the Rat Renal Medulla.

    Directory of Open Access Journals (Sweden)

    Lorette Noiret

    Full Text Available The kidney is one of the main organs that produces ammonia and release it into the circulation. Under normal conditions, between 30 and 50% of the ammonia produced in the kidney is excreted in the urine, the rest being absorbed into the systemic circulation via the renal vein. In acidosis and in some pathological conditions, the proportion of urinary excretion can increase to 70% of the ammonia produced in the kidney. Mechanisms regulating the balance between urinary excretion and renal vein release are not fully understood. We developed a mathematical model that reflects current thinking about renal ammonia handling in order to investigate the role of each tubular segment and identify some of the components which might control this balance. The model treats the movements of water, sodium chloride, urea, NH3 and [Formula: see text], and non-reabsorbable solute in an idealized renal medulla of the rat at steady state. A parameter study was performed to identify the transport parameters and microenvironmental conditions that most affect the rate of urinary ammonia excretion. Our results suggest that urinary ammonia excretion is mainly determined by those parameters that affect ammonia recycling in the loops of Henle. In particular, our results suggest a critical role for interstitial pH in the outer medulla and for luminal pH along the inner medullary collecting ducts.

  18. Safety assessment of ammonia as a transport fuel

    Energy Technology Data Exchange (ETDEWEB)

    Duijm, N.J.; Markert, F.; Lundtang paulsen, Jette

    2005-02-01

    This report describes the safety study performed as part of the EU supported project 'Ammonia Cracking for Clean Electric Power Technology' The study addresses the following activities: safety of operation of the ammonia-powered vehicle under normal and accident (collision) conditions, safety of transport of ammonia to the refuelling stations and safety of the activities at the refuelling station (unloading and refuelling). Comparisons are made between the safety of using ammonia and the safety of other existing or alternative fuels. The conclusion is that the hazards in relation to ammonia need to be controlled by a combination of technical and regulatory measures. The most important requirements are: - Advanced safety systems in the vehicle - Additional technical measures and regulations are required to avoid releases in maintenance workshops and unauthorised maintenance on the fuel system - Road transport of ammonia to refuelling stations in refrigerated form - Sufficient safety zones between refuelling stations and residential or otherwise public areas. When these measures are applied, the use of ammonia as a transport fuel wouldnt cause more risks than currently used fuels (using current practice). (au)

  19. Adipose tissue extracts plasma ammonia after sprint exercise in women and men

    DEFF Research Database (Denmark)

    Esbjörnsson, Mona; Bülow, Jens; Norman, Barbara;

    2006-01-01

    This study evaluates a possible contribution of adipose tissue to the elimination of plasma ammonia (NH(3)) after high-intensity sprint exercise. In 14 healthy men and women, repeated blood samples for plasma NH(3) analyses were obtained from brachial artery and from a subcutaneous abdominal vein...... before and after three repeated 30-s cycle sprints separated by 20 min of recovery. Biopsies from subcutaneous abdominal adipose tissue were obtained and analyzed for glutamine and glutamate content. After exercise, both arterial and abdominal venous plasma NH(3) concentrations were lower in women than...... in men (P adipose tissue. However, the fractional extraction (a...

  20. Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

    Directory of Open Access Journals (Sweden)

    A. Salam

    2007-01-01

    Full Text Available The ice nucleation characteristics of montmorillonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric temperatures and relative humidities with a continuous flow diffusion chamber. The montmorillonite particles were exposed to pure (100% and diluted ammonia gas (25 ppm at room temperature in a stainless steel chamber. There was no significant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure ammonia gas exposure enhanced the ice nucleating fraction of montmorillonite mineral dust particles 3 to 8 times at 90% relative humidity with respect to water (RHw and 5 to 8 times at 100% RHw for 120 min exposure time within our experimental conditions. The percentages of active ice nuclei were 2 to 9 times higher at 90% RHw and 2 to 13 times higher at 100% RHw in 25 ppm ammonia exposed montmorillonite compared to unexposed montmorillonite. All montmorillonite particles are more efficient as ice nuclei with increasing relative humidities and decreasing temperatures. The activation temperature of montmorillonite exposed to 100% pure ammonia was 12°C higher than for unexposed montmorillonite particles at 90% RHw and 10°C higher at 100% RHw. In the 25 ppm ammonia exposed montmorillonite experiments, the activation temperature was 7°C warmer than unexposed montmorillonite at 100% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmorillonite mineral dust particles. This is the first experimental evidence that ammonia gas exposed montmorillonite mineral dust particles can enhance its activation as ice nuclei and that the activation can occur at temperatures warmer than –10°C where natural atmospheric ice nuclei are very scarce.

  1. Statistical modelling of variability in sediment-water nutrient and oxygen fluxes

    Science.gov (United States)

    Serpetti, Natalia; Witte, Ursula; Heath, Michael

    2016-06-01

    Organic detritus entering, or produced, in the marine environment is re-mineralised to inorganic nutrient in the seafloor sediments. The flux of dissolved inorganic nutrient between the sediment and overlying water column is a key process in the marine ecosystem, which binds the biogeochemical sub-system to the living food web. These fluxes are potentially affected by a wide range of physical and biological factors and disentangling these is a significant challenge. Here we develop a set of General Additive Models (GAM) of nitrate, nitrite, ammonia, phosphate, silicate and oxygen fluxes, based on a year-long campaign of field measurements off the north-east coast of Scotland. We show that sediment grain size, turbidity due to sediment re-suspension, temperature, and biogenic matter content were the key factors affecting oxygen consumption, ammonia and silicate fluxes. However, phosphate fluxes were only related to suspended sediment concentrations, whilst nitrate fluxes showed no clear relationship to any of the expected drivers of change, probably due to the effects of denitrification. Our analyses show that the stoichiometry of nutrient regeneration in the ecosystem is not necessarily constant and may be affected by combinations of processes. We anticipate that our statistical modelling results will form the basis for testing the functionality of process-based mathematical models of whole-sediment biogeochemistry.

  2. Muon Fluxes From Dark Matter Annihilation

    CERN Document Server

    Erkoca, Arif Emre; Sarcevic, Ina

    2009-01-01

    We calculate the muon flux from annihilation of the dark matter in the core of the Sun, in the core of the Earth and from cosmic diffuse neutrinos produced in dark matter annihilation in the halos. We consider model-independent direct neutrino production and secondary neutrino production from the decay of taus produced in the annihilation of dark matter. We illustrate how muon energy distribution from dark matter annihilation has a very different shape than muon flux from atmospheric neutrinos. We consider both the upward muon flux, when muons are created in the rock below the detector, and the contained flux when muons are created in the (ice) detector. We contrast our results to the ones previously obtained in the literature, illustrating the importance of properly treating muon propagation and energy loss. We comment on neutrino flavor dependence and their detection.

  3. Fast responsive, optical trace level ammonia sensor for environmental monitoring

    OpenAIRE

    Abel Tobias; Ungerböck Birgit; Klimant Ingo; Mayr Torsten

    2012-01-01

    Abstract Background Ammonia is a ubiquitous chemical substance which is created in technical and biological processes and harmful to many different organisms. One specific problem is the toxicity of ammonia in fish at levels of 25 μg/l - a very common issue in today’s aqua culture. In this study we report a development of a fast responsive, optical ammonia sensor for trace concentrations. Results Different hydrogels have been investigated as host polymers for a pH based sensing mechanism base...

  4. Safety assessment of ammonia as a transport fuel

    DEFF Research Database (Denmark)

    Duijm, N.J.; Markert, Frank; Paulsen, Jette Lundtang

    2005-01-01

    of transport of ammonia to the refuelling stations and safety of the activities at the refuelling station (unloading and refuelling). Comparisons are made between the safety of using ammonia and the safety of otherexisting or alternative fuels. The conclusion is that the hazards in relation to ammonia need...... to be controlled by a combination of technical and regulatory measures. The most important requirements are: - Advanced safety systems in the vehicle -Additional technical measures and regulations are required to avoid releases in maintenance workshops and unauthorised maintenance on the fuel system. - Road...

  5. Ammonia volatilization from crop residues and frozen green manure crops

    Science.gov (United States)

    de Ruijter, F. J.; Huijsmans, J. F. M.; Rutgers, B.

    2010-09-01

    Agricultural systems can lose substantial amounts of nitrogen (N). To protect the environment, the European Union (EU) has adopted several directives that set goals to limit N losses. National Emission Ceilings (NEC) are prescribed in the NEC directive for nitrogen oxides and ammonia. Crop residues may contribute to ammonia volatilization, but sufficient information on their contribution to the national ammonia volatilization is lacking. Experiments were carried out with the aim to assess the ammonia volatilization of crop residues left on the soil surface or incorporated into the soil under the conditions met in practice in the Netherlands during late autumn and winter. Ammonia emission from residues of broccoli, leek, sugar beet, cut grass, fodder radish (fresh and frozen) and yellow mustard (frozen) was studied during two winter seasons using volatilization chambers. Residues were either placed on top of soil or mixed with soil. Mixing residues with soil gave insignificant ammonia volatilization, whereas volatilization was 5-16 percent of the N content of residues when placed on top of soil. Ammonia volatilization started after at least 4 days. Total ammonia volatilization was related to C/N-ratio and N concentration of the plant material. After 37 days, cumulative ammonia volatilization was negligible from plant material with N concentration below 2 percent, and was 10 percent of the N content of plant material with 4 percent N. These observations can be explained by decomposition of plant material by micro-organisms. After an initial built up of the microbial population, NH 4+ that is not needed for their own growth is released and can easily emit as NH 3 at the soil surface. The results of the experiments were used to estimate the contribution of crop residues to ammonia volatilization in the Netherlands. Crop residues of arable crops and residues of pasture topping may contribute more than 3 million kg NH 3-N to the national ammonia volatilization of the

  6. A spatial ammonia emission inventory for pig farming

    Science.gov (United States)

    Rebolledo, Boris; Gil, Antonia; Pallarés, Javier

    2013-01-01

    Atmospheric emissions of ammonia (NH3) from the agricultural sector have become a significant environmental and public concern as they have impacts on human health and ecosystems. This work proposes an improved methodology in order to identify administrative regions with high NH3 emissions from pig farming and calculates an ammonia density map (kg NH3-N ha-1), based on the number of pigs and available agricultural land, terrain slopes, groundwater bodies, soil permeability, zones sensitive to nitrate pollution and surface water buffer zones. The methodology has been used to construct a general tool for locating ammonia emissions from pig farming when detailed information of livestock farms is not available.

  7. Detection of Widespread Hot Ammonia in the Galactic Center

    OpenAIRE

    Mills, Elisabeth A. C.; Morris, Mark R.

    2013-01-01

    We present the detection of metastable inversion lines of ammonia from energy levels high above the ground state. We detect these lines in both emission and absorption toward fifteen of seventeen positions in the central 300 parsecs of the Galaxy. In total, we observe seven metastable transitions of ammonia: (8,8), (9,9), (10,10), (11,11), (12,12), (13,13) and (15,15), with energies (in Kelvins) ranging from 680 to 2200 K. We also map emission from ammonia (8,8) and (9,9) in two clouds in the...

  8. Effect of nitrogen fertilization and residue management practices on ammonia emissions from subtropical sugarcane production

    Science.gov (United States)

    mudi, Sanku Datta; Wang, Jim J.; Dodla, Syam Kumar; Arceneaux, Allen; Viator, H. P.

    2016-08-01

    Ammonia (NH3) emission from soil is a loss of nitrogen (N) nutrient for plant production as well as an issue of air quality, due to the fact that it is an active precursor of airborne particulate matters. Ammonia also acts as a secondary source of nitrous oxide (N2O) emission when present in the soil. In this study, the impacts of different sources of N fertilizers and harvest residue management schemes on NH3 emissions from sugarcane production were evaluated based on an active chamber method. The field experiment plots consisting of two sources of N fertilizer (urea and urea ammonium nitrate (UAN)) and two common residue management practices, namely residue retained (RR) and residue burned (RB), were established on a Commerce silt loam. The NH3 volatilized following N fertilizer application was collected in an impinger containing diluted citric acid and was subsequently analyzed using ion chromatography. The NH3 loss was primarily found within 3-4 weeks after N application. Average seasonal soil NH3 flux was significantly greater in urea plots with NH3-N emission factor (EF) twice or more than in UAN plots (2.4-5.6% vs. 1.2-1.7%). The RR residue management scheme had much higher NH3 volatilization than the RB treatment regardless of N fertilizer sources, corresponding to generally higher soil moisture levels in the former. Ammonia-N emissions in N fertilizer-treated sugarcane fields increased with increasing soil water-filled pore space (WFPS) up to 45-55% observed in the field. Both N fertilizer sources and residue management approaches significantly affected NH3 emissions.

  9. Ammonia losses and nitrogen partitioning at a southern High Plains open lot dairy

    Science.gov (United States)

    Todd, Richard W.; Cole, N. Andy; Hagevoort, G. Robert; Casey, Kenneth D.; Auvermann, Brent W.

    2015-06-01

    Animal agriculture is a significant source of ammonia (NH3). Cattle excrete most ingested nitrogen (N); most urinary N is converted to NH3, volatilized and lost to the atmosphere. Open lot dairies on the southern High Plains are a growing industry and face environmental challenges as well as reporting requirements for NH3 emissions. We quantified NH3 emissions from the open lot and wastewater lagoons of a commercial New Mexico dairy during a nine-day summer campaign. The 3500-cow dairy consisted of open lot, manure-surfaced corrals (22.5 ha area). Lactating cows comprised 80% of the herd. A flush system using recycled wastewater intermittently removed manure from feeding alleys to three lagoons (1.8 ha area). Open path lasers measured atmospheric NH3 concentration, sonic anemometers characterized turbulence, and inverse dispersion analysis was used to quantify emissions. Ammonia fluxes (15-min) averaged 56 and 37 μg m-2 s-1 at the open lot and lagoons, respectively. Ammonia emission rate averaged 1061 kg d-1 at the open lot and 59 kg d-1 at the lagoons; 95% of NH3 was emitted from the open lot. The per capita emission rate of NH3 was 304 g cow-1 d-1 from the open lot (41% of N intake) and 17 g cow-1 d-1 from lagoons (2% of N intake). Daily N input at the dairy was 2139 kg d-1, with 43, 36, 19 and 2% of the N partitioned to NH3 emission, manure/lagoons, milk, and cows, respectively.

  10. Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for mediterranean evergreen woodlands

    Science.gov (United States)

    Pinho, P.; Theobald, M. R.; Dias, T.; Tang, Y. S.; Cruz, C.; Martins-Loução, M. A.; Máguas, C.; Sutton, M.; Branquinho, C.

    2011-11-01

    Nitrogen (N) has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds have been established, such as critical loads (deposition fluxes) and levels (concentrations). For Mediterranean ecosystems, few studies have been carried out to assess these parameters. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for Mediterranean evergreen woodlands. For that we have considered changes in epiphytic lichen communities, which have been shown to be one of the most sensitive to excessive N. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done under Mediterranean climate, in evergreen cork-oak woodlands, by sampling lichen functional diversity and annual atmospheric ammonia concentrations and modelling N deposition downwind from a reduced N source (a cattle barn). By modelling the highly significant relationship between lichen functional groups and N deposition, the critical load was estimated to be below 26 kg (N) ha-1 yr-1, which is within the upper range established for other semi-natural ecosystems. By modelling the highly significant relationship of lichen functional groups with annual atmospheric ammonia concentration, the critical level was estimated to be below 1.9 μg m-3, in agreement with recent studies for other ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should be taken into account in policies that aim at protecting Mediterranean woodlands from the initial effects of excessive N.

  11. Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for mediterranean evergreen woodlands

    Directory of Open Access Journals (Sweden)

    P. Pinho

    2011-11-01

    Full Text Available Nitrogen (N has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds have been established, such as critical loads (deposition fluxes and levels (concentrations. For Mediterranean ecosystems, few studies have been carried out to assess these parameters. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for Mediterranean evergreen woodlands. For that we have considered changes in epiphytic lichen communities, which have been shown to be one of the most sensitive to excessive N. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done under Mediterranean climate, in evergreen cork-oak woodlands, by sampling lichen functional diversity and annual atmospheric ammonia concentrations and modelling N deposition downwind from a reduced N source (a cattle barn. By modelling the highly significant relationship between lichen functional groups and N deposition, the critical load was estimated to be below 26 kg (N ha−1 yr−1, which is within the upper range established for other semi-natural ecosystems. By modelling the highly significant relationship of lichen functional groups with annual atmospheric ammonia concentration, the critical level was estimated to be below 1.9 μg m−3, in agreement with recent studies for other ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should be taken into account in policies that aim at protecting Mediterranean woodlands from the initial effects of excessive N.

  12. Submersible microbial desalination cell for simultaneous ammonia recovery and electricity production from anaerobic reactors containing high levels of ammonia.

    Science.gov (United States)

    Zhang, Yifeng; Angelidaki, Irini

    2015-02-01

    High ammonia concentration in anaerobic reactors can seriously inhibit the anaerobic digestion process. In this study, a submersible microbial desalination cell (SMDC) was developed as an innovative method to lower the ammonia level in a continuous stirred tank reactor (CSTR) by in situ ammonia recovery and electricity production. In batch experiment, the ammonia concentration in the CSTR decreased from 6 to 0.7 g-N/L during 30 days, resulting in an average recovery rate of 80 g-N/m(2)/d. Meanwhile, a maximum power density of 0.71±0.5 W/m(2) was generated at 2.85 A/m(2). Both current driven NH4(+) migration and free NH3 diffusion were identified as the mechanisms responsible for the ammonia transportation. With an increase in initial ammonia concentration and a decrease in external resistance, the SMDC performance was enhanced. In addition, the coexistence of other cations in CSTR or cathode had no negative effect on the ammonia transportation.

  13. Experimental Setup for Determining Ammonia-Salt Adsorption and Desorption Behavior Under Typical Heat Pump Conditions. Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Van der Pal, M.; De Boer, R.; Veldhuis, J.B.J. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2013-09-15

    For the aim of obtaining a better understanding of the performance of a salt-ammonia sorption reactor/heat exchanger a new test-rig was developed. This test-rig enables the measurement of the performance in adsorption and desorption mode of different sorption reactor designs. It measures the speed of uptake and release of ammonia gas of various salt-ammonia reactions under well-controlled and well-monitored process conditions, similar to the heat pump conditions. The test-rig measures the ammonia uptake and release under controlled pressure and temperature conditions. Temperatures of the salt reactor can be varied from ambient temperature up to 200{sup o}C and the ammonia pressure can be varied between 0.02 to 2 MPa. These conditions can be set independently and repeated at regular time-intervals. Besides NH3-mass-flow meters, pressure and temperature sensors, the setup also contains an endoscope to observe any macroscopic structural changes in the material during uptake and release of ammonia. Measurements so far have shown a liquid phase of LiCl.3NH3 at pressures of 0.5 MPa and temperatures exceeding 90{sup o}C. Voilent foaming is observed at 120{sup o}C resulting in salt losses. A correlation was determined between the reaction rate of MgCl{sub 2}(2-6)NH3 and the relative pressure gradient yielding a reaction time of about 1500 seconds for a relative pressure difference of 1. Multiple sorption cycles of the CaCl{sub 2}(2-4)NH3 reaction, showed a reduced activity from 85% of the theoretical maximum sorbed mass at the first sorption cycle, to 15% after 300+ cycles.

  14. New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus;

    2002-01-01

    Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia......Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia...

  15. Ammonia removal from an aqueous solution and method for the production of a fertilizer material

    NARCIS (Netherlands)

    Kelder, E.M.; Ursem, W.N.J.; Roos, R.A.; Marijnissen, J.C.M.

    2011-01-01

    The invention provides method for the removal of ammonia from air and converting the ammonia in a fertilizer material, comprising (a) contacting at least part of the air with an aqueous liquid, wherein the aqueous liquid is a solvent for ammonia, to provide an ammonia containing aqueous liquid,and(b

  16. 46 CFR 111.105-32 - Bulk liquefied flammable gas and ammonia carriers.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Bulk liquefied flammable gas and ammonia carriers. 111... gas and ammonia carriers. (a) Each vessel that carries bulk liquefied flammable gases or ammonia as a.... (2) The term “gas-dangerous” does not include the weather deck of an ammonia carrier. (c)...

  17. Production of Diamino propionic acid ammonia lyase by a new strain of Salmonella typhimurium PU011

    Directory of Open Access Journals (Sweden)

    Shiva Kumar Vasanth V

    2002-03-01

    Full Text Available Abstract Background Seeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP. DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP. Results S. typhimurium PU011, a non-virulent bacterial strain isolated in our lab, was found to produce DAP ammonia lyase enzyme when grown in minimal medium containing DAP. There was a direct correlation between biomass yield and enzyme activity, until 16 h post inoculation in minimal medium containing DAP. Following ammonium sulphate precipitation and passing through Sephadex G100, CM-Sephadex and DEAE-Sephacel for crude enzyme extract preparation, about 68-fold enzyme purity was obtained. The purified enzyme gave maximum activity at pH 8.0 and was stable up to 45 degrees C. The Km value for the substrate was found to be 0.685mM, calculated from a Line Weaver Burk plot. Conclusion A new bacterial strain, S.typhimurium PU 011, which is capable of producing DAP ammonia lyase, was isolated.

  18. Biomass production from electricity using ammonia as an electron carrier in a reverse microbial fuel cell.

    Directory of Open Access Journals (Sweden)

    Wendell O Khunjar

    Full Text Available The storage of renewable electrical energy within chemical bonds of biofuels and other chemicals is a route to decreasing petroleum usage. A critical challenge is the efficient transfer of electrons into a biological host that can covert this energy into high energy organic compounds. In this paper, we describe an approach whereby biomass is grown using energy obtained from a soluble mediator that is regenerated electrochemically. The net result is a separate-stage reverse microbial fuel cell (rMFC that fixes CO₂ into biomass using electrical energy. We selected ammonia as a low cost, abundant, safe, and soluble redox mediator that facilitated energy transfer to biomass. Nitrosomonas europaea, a chemolithoautotroph, was used as the biocatalyst due to its inherent capability to utilize ammonia as its sole energy source for growth. An electrochemical reactor was designed for the regeneration of ammonia from nitrite, and current efficiencies of 100% were achieved. Calculations indicated that overall bioproduction efficiency could approach 2.7±0.2% under optimal electrolysis conditions. The application of chemolithoautotrophy for industrial bioproduction has been largely unexplored, and results suggest that this and related rMFC platforms may enable biofuel and related biochemical production.

  19. [Optimization of liquid ammonia treatment for enzymatic hydrolysis of Saccharum arundinaceum to fermentable sugars].

    Science.gov (United States)

    Liu, Jianjun; Peng, Hehuan; Zhao, Xiangjun; Cheng, Cheng; Chen, Feng; Shao, Qianjun

    2013-03-01

    China has abundant available marginal land that can be used for cultivation of lignocellulosic energy plants. Saccharum arundinaceum Retz. is a potential energy crop with both high biomass yield and low soil fertility requirements. It can be planted widely as cellulosic ethanol feedstock in southern China. In the present work Saccharum arundinaceum was pretreated by liquid ammonia treatment (LAT) to overcome biomass recalcitrance, followed by enzymatic hydrolysis. The monosaccharide contents (glucose, xylose, and arabinose) of the enzymatic hydrolysate were determined by high performance liquid chromatography. Experimental results show that the optimal LAT pretreatment conditions were 130 0C, 2:1 (W/W) ammonia to biomass ratio, 80% moisture content (dry weight basis) and 5 min residence time. Approximately 69.34% glucan and 82.60% xylan were converted after 72 h enzymatic hydrolysis at 1% glucan loading using 15 FPU/(g of glucan) of cellulase. The yields of glucose and xylose were 573% and 1 056% higher than those of the untreated biomass, and the LAT-pretreated substrates obtained an 8-fold higher of total monosaccharide yield than untreated substrates. LAT pretreatment was an effective to increase the enzymatic digestibility of Saccharum arundinaceum compared to acid impregnated steam explosion and similar to that of acid treatment and ammonia fiber expansion treatment.

  20. Room Temperature Ammonia Gas Sensing Using Mixed Conductor based TEMPOS Structures

    Directory of Open Access Journals (Sweden)

    Amita Chandra

    2008-10-01

    Full Text Available The current/voltage characteristics of mixed (ion+electron conductor-based ‘TEMPOS’ (Tunable Electronic Material with Pores in Oxide on Silicon structures are reported. TEMPOS are novel electronic MOS-like structures having etched swift heavy ion tracks (i.e., nanopores in the dielectric layer filled with some conducting material. The three contacts (two on top and one on the bottom, which resemble the classical bipolar or field effect transistor arrangements are, in principle, interchangeable when the overall electrical resistance along the tracks and on the surface are similar. Consequently, three configurations are obtained by interchanging the top contacts with the base contact in electronic circuits. The current/voltage characteristics show a diode like behaviour. Impedance measurements have been made for TEMPOS structures with tracks filled with ion conductors and also mixed conductors to study the ammonia sensing behaviour. The impedance has been found to be a function of frequency and magnitude of the applied signal and concentration of the ammonia solution. This is attributed to the large number of charge carriers (here protons available for conduction on exposure to ammonia and also to the large surface to volume ratio of the polymer composites embedded in the ion tracks. The measurement of both, the real and imaginary parts of impedance allows one to enhance the detection sensitivity greatly.

  1. An optimized and simplified method for analysing urea and ammonia in freshwater aquaculture systems

    DEFF Research Database (Denmark)

    Larsen, Bodil Katrine; Dalsgaard, Anne Johanne Tang; Pedersen, Per Bovbjerg

    2015-01-01

    This study presents a simple urease method for analysis of ammonia and urea in freshwater aquaculture systems. Urea is hydrolysed into ammonia using urease followed by analysis of released ammonia using the salicylate-hypochlorite method. The hydrolysis of urea is performed at room temperature...... and without addition of a buffer. A number of tests were performed on water samples obtained from a commercial rainbow trout farm to determine the optimal urease concentration and time for complete hydrolysis. One mL of water sample was spiked with 1.3 mL urea at three different concentrations: 50 lg L 1, 100...... lg L 1 and 200 lg L 1 urea-N. In addition, five concentrations of urease were tested, ranging from 0.1 U mL 1 to 4 U mL 1. Samples were hydrolysed for various time periods ranging from 5 to 120 min. A urease concentration of 0.4 U mL 1 and a hydrolysis period of 120 min gave the best results, with 99...

  2. Four New Dense Molecular Cores in the Taurus Molecular Cloud (TMC) Ammonia and Cyanodiacetylene Observations

    CERN Document Server

    Codella, C; Henkel, C; Benson, P; Myers, P C

    1997-01-01

    Trying to obtain a more complete picture of star forming regions in the Taurus Molecular Cloud, four newly discovered dense cores (L1521D, L1521F, L1524, L1507A) are identified and mapped through the ammonia (J,K)=(1,1) and (2,2) rotational inversion lines. These cores have sizes of 0.06-0.09 pc, hydrogen densities of order 10000 - 100000 cm-3 and kinetic temperatures between 8 and 10 K. The masses range from 0.2 - 1.0 solar masses, placing the cores with the lowest M values at the lower edge of the mass distribution for ammonia cores in the TMC. Turbulent, thermal and gravitational energies have been estimated. A comparison between these energy terms and considerations related to thermal and turbulent line broadening indicate that these cores are close to equilibrium. Moreover we report the detection of the J=9-8 transition of HC5N towards the four ammonia peak positions. The HC5N column densities are in agreement with values derived for other molecular cores in the TMC.

  3. Combination of ion exchange system and biological reactors for simultaneous removal of ammonia and organics.

    Science.gov (United States)

    Park, Wooshin; Jang, Eunhee; Lee, Myun-Joo; Yu, Seungho; Kim, Tak-Hyun

    2011-04-01

    A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH(4)(+) could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m(2) ∙ s of a maximum flux. On the other hand, the removal of NO(3)(-) was 3.5 times faster than NH(4)(+) and the maximum flux was calculated to be 3.4 mg N/m(2) ∙ s. The systems for NH(4)(+) and NO(3)(-) removal were combined for establishing the IEBR process. When the process was operated in a continuous mode, approximately 95.8% of NH(4)(+) was removed showing an average flux of 0.22 mg N/m(2) · s. The removal efficiency of total nitrogen was calculated as 94.5% whereas that of organics was 99.5%. It was concluded that the IEBR process would be effectively used for a simultaneous removal of NH(4)(+) and organics.

  4. Chromophores from photolyzed ammonia reacting with acetylene: Application to Jupiter's Great Red Spot

    Science.gov (United States)

    Carlson, R. W.; Baines, K. H.; Anderson, M. S.; Filacchione, G.; Simon, A. A.

    2016-08-01

    The high altitude of Jupiter's Great Red Spot (GRS) may enhance the upward flux of gaseous ammonia (NH3) into the high troposphere, where NH3 molecules can be photodissociated and initiate a chain of chemical reactions with downwelling acetylene molecules (C2H2). These reactions, experimentally studied earlier by (Ferris and Ishikawa [1987] Nature 326, 777-778) and (Ferris and Ishikawa [1988] J. Amer. Chem. Soc. 110, 4306-4312), produce chromophores that absorb in the visible and ultraviolet regions. In this work we photolyzed mixtures of NH3 and C2H2 using ultraviolet radiation with a wavelength of 214 nm and measured the spectral transmission of the deposited films in the visible region (400-740 nm). From these transmission data we estimated the imaginary indices of refraction. Assuming that ammonia grains at the top of the GRS clouds are coated with this material, we performed layered sphere and radiative transfer calculations to predict GRS reflection spectra. Comparison of those results with observed and previously unreported Cassini visible spectra and with true-color images of the GRS show that the unknown GRS chromophore is spectrally consistent with the coupled NH3-C2H2 photochemical products produced in our laboratory experiments. Using high-resolution mass spectrometry and infrared spectroscopy we infer that the chromophore-containing residue is composed of aliphatic azine, azo, and diazo compounds.

  5. Chromophores from photolyzed ammonia reacting with acetylene: Application to Jupiters Great Red Spot

    Science.gov (United States)

    Carlson, Robert W.; Baines, Kevin H.; Anderson, M. S.; Filacchione, G.; Simon, A. A.

    2016-01-01

    The high altitude of Jupiter's Great Red Spot (GRS) may enhance the upward flux of gaseous ammonia (NH3 ) into the high troposphere, where NH3 molecules can be photodissociated and initiate a chain of chemical reactions with downwelling acetylene molecules (C2H2 ). These reactions, experimentally studied earlier by (Ferris and Ishikawa [1987] Nature 326, 777-778) and (Ferris and Ishikawa [1988] J. Amer. Chem. Soc. 110, 4306-4312), produce chromophores that absorb in the visible and ultraviolet regions. In this work we photolyzed mixtures of NH3 and C2H2 using ultraviolet radiation with a wavelength of 214 nm and measured the spectral transmission of the deposited films in the visible region (400-740 nm). From these transmission data we estimated the imaginary indices of refraction. Assuming that ammonia grains at the top of the GRS clouds are coated with this material, we performed layered sphere and radiative transfer calculations to predict GRS reflection spectra. Comparison of those results with observed and previously unreported Cassini visible spectra and with true-color images of the GRS show that the unknown GRS chromophore is spectrally consistent with the coupled NH3-C2H2 photochemical products produced in our laboratory experiments. Using high-resolution mass spectrometry and infrared spectroscopy we infer that the chromophore-containing residue is composed of aliphatic azine, azo, and diazo compounds.

  6. Open-path, quantum cascade laser-based sensor for high resolution atmospheric ammonia measurements

    Directory of Open Access Journals (Sweden)

    D. J. Miller

    2013-07-01

    Full Text Available We demonstrate a compact, open-path, quantum cascade laser-based atmospheric ammonia sensor operating at 9.06 μm for high sensitivity, high temporal resolution, ground-based measurements. Atmospheric ammonia (NH3 is a gas-phase precursor to fine particulate matter, with implications for air quality and climate change. Currently, NH3 sensing challenges have led to a lack of widespread in-situ measurements. Our open-path sensor configuration avoids sampling artifacts associated with NH3 surface adsorption onto inlet tubing and reduced pressure sampling cells, as well as condensed-phase partitioning ambiguities. Multi-harmonic wavelength modulation spectroscopy allows for selective and sensitive detection of atmospheric-pressure broadened absorption features. An in-line ethylene reference cell provides real-time calibration (±20% accuracy and normalization for instrument drift under rapidly changing field conditions. The sensor has a sensitivity and minimum detection limit of 0.15 ppbv NH3 at 10 Hz, a mass of ~ 5 kg and consumes ~ 50 W of electrical power. In-situ field performance of this open-path NH3 sensor is demonstrated, with 10 Hz time resolution and a large dynamic response for in-situ NH3 measurements. This sensor provides the capabilities for improved in-situ gas phase NH3 sensing relevant for emission source characterization and flux measurements.

  7. Flux Pinning in Superconductors

    CERN Document Server

    Matsushita, Teruo

    2007-01-01

    The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of supercondu...

  8. Flux pinning in superconductors

    CERN Document Server

    Matsushita, Teruo

    2014-01-01

    The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of supercondu...

  9. Assessment of global and regional left ventricular function by electrocardiographic gated N-13 ammonia positron emission tomography in patients with coronary artery disease

    International Nuclear Information System (INIS)

    Electrocardiographic gated 13N-ammonia positron emission tomography (PET) enables simultaneous assessment of myocardial blood flow and left ventricular (LV) function. The aim of this study was to assess the accuracy of gated 13N-ammonia PET for evaluating global and regional LV function in patients with coronary artery disease (CAD) in comparison with conventional left ventriculography (LVG). Fifty-four patients with CAD underwent gated 13N-ammonia PET and LVG. The LV end-diastolic and end-systolic volumes (LVEDV, LVESV) and ejection fraction (LVEF) by gated 13N-ammonia PET were calculated using Cedars-Sinai automated quantitative gated single photon emission computed tomography (QGS) and compared with those obtained by LVG. The regional wall motion (RWM) was visually scored, and compared with that on LVG. There were good correlations between the 2 methods for LVEF, LVEDV and LVESV (R=0.828, R=0.821 and R=0.874 respectively). The RWM assessed by gated 13N-ammonia PET also agreed well with that by LVG (complete agreement was 70.4%, κ=0.58). Gated 13N-ammonia PET combined with QGS works reasonably well for the assessment of both global and regional LV function in CAD patients, although additional calibration may be necessary. (author)

  10. Bacteria dominate the ammonia-oxidizing community in a hydrothermal vent site at the Mid-Atlantic Ridge of the South Atlantic Ocean.

    Science.gov (United States)

    Xu, Wei; Li, Meng; Ding, Jie-Fei; Gu, Ji-Dong; Luo, Zhu-Hua

    2014-09-01

    Ammonia oxidation is the first and rate-limiting step of nitrification, which is carried out by two groups of microorganisms: ammonia-oxidizing bacteria (AOB) and the recently discovered ammonia-oxidizing archaea (AOA). In this study, diversity and abundance of AOB and AOA were investigated in five rock samples from a deep-sea hydrothermal vent site at the Mid-Atlantic Ridge (MAR) of the South Atlantic Ocean. Both bacterial and archaeal ammonia monooxygenase subunit A (amoA) gene sequences obtained in this study were closely related to the sequences retrieved from deep-sea environments, indicating that AOB and AOA in this hydrothermal vent site showed typical deep ocean features. AOA were more diverse but less abundant than AOB. The ratios of AOA/AOB amoA gene abundance ranged from 1/3893 to 1/242 in all investigate samples, indicating that bacteria may be the major members responding to the aerobic ammonia oxidation in this hydrothermal vent site. Furthermore, diversity and abundance of AOA and AOB were significantly correlated with the contents of total nitrogen and total sulfur in investigated samples, suggesting that these two environmental factors exert strong influences on distribution of ammonia oxidizers in deep-sea hydrothermal vent environment.

  11. Vaporization reduction characteristics of aqueous ammonia solutions by the addition of ethylene glycol, glycerol and glycine to the CO2 absorption process

    Institute of Scientific and Technical Information of China (English)

    Jong-Beom Seo; Soo-Bin Jeon; Je-Young Kim; Gang-Woo Lee; Jong-Hyeon Jung; Kwang-Joong Oh

    2012-01-01

    Aqueous ammonia(NH3)solution can be used as an alternative absorption for the control of CO2 emitted from flue gases due to its high absorption capacity,fast absorption rate and low corrosion problem.The emission of CO2 from iron and steel plants requires much attention,as they are higher than those emitted from power plants at a single point source.In the present work,low concentration ammonia liquor,9 wt.%,was used with various additives to obtain the kinetic properties using the blast furnace gas model.Although a solution with a high ammonia concentration enables high CO2 absorption efficiency,ammonium ions are lost as ammonia vapor,resulting in reduced CO2 absorption due to the lower concentration of the ammonia absorbent.To decrease the vaporization of ammonia,ethylene glycol,glycerol and glycine,which contain more than one hydroxyl radical,were chosen.The experiments were conducted at 313 K similar to the CO2 absorption conditions for the blast furnace gas model.

  12. Rotational dynamics in ammonia borane: Evidence of strong isotope effects

    Energy Technology Data Exchange (ETDEWEB)

    Cantelli, Rosario; Paolone, Annalisa; Palumbo, Oriele; Leardini, F.; Autrey, Thomas; Karkamkar, Abhijeet J.; Luedtke, Avery T.

    2013-12-15

    This work reports anelastic spectroscopy measurements on the partially deuterated (ND3BH3 and NH3BD3) and perdeuterated (ND3BD3) ammonia borane (NH3BH3) compounds. The relaxations previously reported in NH3BH3 are observed in all the samples, and are ascribed to the rotational and torsional dynamics of NH(D)3BH(D)3 complexes. A new thermally activated peak appears at 70 K (for a vibration frequency of 1 kHz) in the spectrum of NH3BD3 and ND3BD3. The peak is practically a single-time Debye process, indicating absence of interaction between the relaxing units, and has a strikingly high intensity. A secondary relaxation process is also detected around 55 K. The anelastic spectrum of the ND3BH3 only displays this less intense process at 55 K. The analysis of the peaks supplies information about the dynamics of the relaxing species, and the obtained results provide indications on the effect of partial and selective deuteration on the hydrogen (deuterium) dynamics.

  13. Ammonia-water absorption in vertical tubular absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Seara, Jose; Sieres, Jaime; Rodriguez, Cristobal; Vazquez, Manuel [Area de Maquinas y Motores Termicos, Escuela Tecnica Superior de Ingenieros Industriales, Campus Lagoas-Marcosende, No 9, 36200 Vigo (Spain)

    2005-03-01

    This paper presents a detailed analysis of the heat and mass transfer processes during the absorption of ammonia into water in a co-current vertical tubular absorber. The absorber configuration is of the shell and tubes type. The absorption process progresses as the vapour and liquid contact inside the tubes. Water is used as the absorber cooling medium. A differential mathematical model has been developed on the basis of mass and energy balances and heat and mass transfer equations, in order to provide further understanding of the absorber behaviour. The model takes into account separately for the churn, slug and bubbly flow patterns experimentally forecasted in this type of absorption processes inside vertical tubes and considers the simultaneous heat and mass transfer processes in both liquid and vapour phases, as well as heat transfer to the cooling medium. The model equations have been solved using the finite-difference method. Results obtained for specific data are depicted to show local values of the most important variables all along the absorber length. Parametric analyses have been performed to show the influence of design parameters and operating conditions on the absorber performance. The effect of the heat and mass transfer coefficients has also been evaluated. (authors)

  14. Exploring FeSe-based superconductors by liquid ammonia method

    Institute of Scientific and Technical Information of China (English)

    Ying Tian-Ping; Wang Gang; Jin Shi-Feng; Shen Shi-Jie; Zhang Han; Zhou Ting-Ting; Lai Xiao-Fang

    2013-01-01

    Our recent progress on the preparation of a series of new FeSe-based superconductors and the clarification of SC phases in potassium-intercalated iron selenides are reviewed here.By the liquid ammonia method,metals Li,Na,Ca,Sr,Ba,Eu,and Yb are intercalated in between FeSe layers and form superconductors with transition temperatures of 30 K~46 K,which cannot be obtained by high-temperature routes.In the potassium-intercalated iron selenides,we demonstrate that at least two SC phases exist,KxFe2Se2(NH3)y (x ≈ 0.3 and 0.6),determined mainly by the concentration of potassium.NH3 has little,if any,effect on superconductivity,but plays an important role in stabilizing the structures.All these results provide a new starting point for studying the intrinsic properties of this family of superconductors,especially for their particular electronic structures.

  15. Conversion of the refractory ammonia and acetic acid in catalytic wet air oxidation of animal byproducts

    Institute of Scientific and Technical Information of China (English)

    Virginie Fontanier; Sofiane Zalouk; Stéphane Barbati

    2011-01-01

    Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) of slaughtered animal byproducts (ABPs) were investigated.Two step experiment was carried out consisting ofa non-catalysed WAO run followed by a CWAO run at 170-275℃, 20 MPa, and reaction time 180 min.The WAO (1st step) of sample (5 g/L total organic carbon (TOC)) yielded (82.0 ± 4)% TOC removal and (78.4 ± 13.2)%conversion of the initial organic-N into NH4+-N.Four metal catalysts (Pd, Pt, Rh, Ru) supported over alumina have been tested in catalytic WAO (2nd step) at elevated pH to enhance ammonia conversion and organic matter removal, particularly acetic acid.It was found that the catalysts Ru, Pt, and Rh had significant effects on the TOC removal (95.1%, 99.5% and 96.7%, respectively) and on the abatement of ammonia (93.4%, 96.7% and 96.3%, respectively) with high nitrogen selectivity.The catalyst Pd was found to have the less activity while Pt had the best performance.The X-Ray diffraction analysis showed that the support of catalyst was not stable under the experimental conditions since it reacted with phosphate present in solution.Nitrite and nitrate ions were monitored during the oxidation reaction and it was concluded that CWAO of ammonia in real waste treatment framework was in good agreement with the results obtained from the literature for ideal solutions of ammonia.

  16. Phycoremediation of landfill leachate with chlorophytes: Phosphate a limiting factor on ammonia nitrogen removal.

    Science.gov (United States)

    Paskuliakova, Andrea; Tonry, Steven; Touzet, Nicolas

    2016-08-01

    The potential of microalgae to bioremediate wastewater has been reported in numerous studies but has not been investigated as extensively for landfill leachate, which may be attributed to its complex nature and toxicity. In this study we explored if microalgal phycoremediation could constitute an alternative biological treatment option for landfill leachate management in regions with temperate climatic conditions. The aim of this study was to assess the performance of microalgae species at relatively low temperature (15 °C) and light intensity (14:10 h, light: dark, 22 μmol m(-2) s(-1)) for reduction in energy inputs. Four chlorophyte strains originating from the North-West of Ireland were selected and used in batch experiments in order to evaluate their ability to reduce total ammonia nitrogen, oxidised nitrogen and orthophosphate in landfill leachate. The Chlamydomonas sp. strain SW15aRL isolated from raw leachate achieved the highest level of pollutant reduction whereby a decrease of 51.7% of ammonia nitrogen was observed in 10% raw leachate (∼100 mg l(-1) NH4(+)-N) by day 24 in experiments without culture agitation. However, in the experiment conducted with 10% raw leachate supplemented with phosphate, a decrease of 90.7% of ammonia nitrogen was obtained by day 24 while also achieving higher biomass production. This series of experiments pointed to phosphorus being a limiting factor in the microalgae based phycoremediation of the landfill leachate. The effective reduction of ammonia nitrogen in landfill leachate can be achieved at lower temperature and light conditions. This was attained by employing native species adapted to such conditions and by improving nutrient balance. PMID:27161884

  17. Inactivation of adenovirus, reovirus and bacteriophages in fecal sludge by pH and ammonia.

    Science.gov (United States)

    Magri, Maria Elisa; Fidjeland, Jørgen; Jönsson, Håkan; Albihn, Ann; Vinnerås, Björn

    2015-07-01

    The aim of this study was to evaluate the inactivation of adenovirus, reovirus and bacteriophages (MS2, ΦX174, 28B) in a fecal sludge. We conducted two experiments. In the first, we tested different compositions of the fecal sludge by mixing different amounts of water, feces and urine, totaling nine combinations which were kept at temperatures between 10 and 28°C. In the second study, urea was added to the mixtures, which were kept at temperatures from 5 to 33°C. The inactivation was based on a combination of temperature, pH and uncharged ammonia concentration. The increase in pH and ammonia was provided mainly by urine content (Experiment 1) and by urine and added urea (Experiment 2). The inactivation of bacteriophages was slower than the AdV and ReV. At 23°C and 28°, reasonable treatment times were obtained when pH was higher than 8.9 and NH3 concentrations were higher than 35 and 55 mM respectively. With those conditions, the maximum time for a 3 log reduction in viruses, according to this study, would be 35 days (23°C) and 21 days (28°C). However, in most applications where helminth eggs are present, the treatment time and NH3 for sanitization will be the scaling criteria, as they are more persistent. Concerning the sanitization of effluents from latrines, vacuum toilets or dry toilets in developing countries with tropical and sub-tropical climates, the use of intrinsic ammonia combined with high pH can be effective in producing a safe and highly valuable liquid that can be used as a fertilizer. In the case of the fecal sludge with very intrinsic ammonia concentration (<20 mM), sanitization could still be achieved by the addition of urea.

  18. Effect of ammonia plasma treatment on graphene oxide LB monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Gulbagh; Botcha, V. Divakar; Narayanam, Pavan K.; Sutar, D. S.; Talwar, S. S.; Major, S. S. [Department of Physics, Indian Institute of Technology Bombay, Mumbai - 400076 (India); Srinivasa, R. S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai - 400076 (India)

    2013-02-05

    Graphene oxide monolayer sheets were transferred on Si and SiO{sub 2}/Si substrates by Langmuir-Blodgett technique and were exposed to ammonia plasma at room temperature. The monolayer character of both graphene oxide and plasma treated graphene oxide sheets were ascertained by atomic force microscopy. X-ray photoelectron spectroscopy and Raman spectroscopy revealed that ammonia plasma treatment results in enhancement of graphitic carbon content along with the incorporation of nitrogen. The conductivity of graphene oxide monolayers, which was in the range of 10{sup -6}-10{sup -7} S/cm, increased to 10{sup -2}-10{sup -3} S/cm after the ammonia plasma treatment. These results indicate that the graphene oxide was simultaneously reduced and N-doped during ammonia plasma treatment, without affecting the morphological stability of sheets.

  19. Ammonia-water system : Part I. Thermodynamic properties

    International Nuclear Information System (INIS)

    The various thermodynamic properties which have direct bearing on design calculations and separation factor calculations for gaseous ammonia water system have been calculated and compiled in tabular form for easy reference. (auth.)

  20. IRIS Toxicological Review of Ammonia - Noncancer Inhalation (Final Report)

    Science.gov (United States)

    The U.S. Environmental Protection Agency's (USEPA) has finalized the Integrated Risk Information System (IRIS) Assessment of Ammonia (Noncancer Inhalation). This assessment addresses the potential noncancer human health effects from long-term inhalation exposure to ammon...

  1. Predicting catalysis: Understanding ammonia synthesis from first-principles calculations

    DEFF Research Database (Denmark)

    Hellmann, A.; Baerends, E.J.; Biczysko, M.;

    2006-01-01

    Here, we give a full account of a large collaborative effort toward an atomic-scale understanding of modern industrial ammonia production over ruthenium catalysts. We show that overall rates of ammonia production can be determined by applying various levels of theory (including transition state...... for any given point along an industrial reactor, and the kinetic results can be integrated over the catalyst bed to determine the industrial reactor yield. We find that, given the present uncertainties, the rate of ammonia production is well-determined directly from our atomic-scale calculations....... Furthermore, our studies provide new insight into several related fields, for instance, gas-phase and electrochemical ammonia synthesis. The success of predicting the outcome of a catalytic reaction from first-principles calculations supports our point of view that, in the future, theory will be a fully...

  2. Ammonia concentration in an animal radon exposure facility

    International Nuclear Information System (INIS)

    An experimental and dosimetric study on lung tumour induction by inhalation of radon daughters under indoor conditions has been started with the aim of analysing the various factors which determine the risk due to this inhalation. In the experimental part of the study, WAG/Rij rats will be exposed daily for a period of about 18 months in an exposure chamber to a relatively low concentration of radon daughter products. In chronic exposure chambers, ammonia is produced by the action of urease-positive bacteria in urine and faeces. There are reports showing that, in such exposure chambers, the ammonia concentrations will rise beyond acceptable levels. The ammonia concentration as a function of time has therefore been studied, as has means of reducing this concentration. The results demonstrate that, with the addition of Aqualloy granules the ammonia concentration can be reduced over a long period of time to a level for which no cooperative action with the radon exposure is expected. (Auth.)

  3. [Inhibition of aromatics on ammonia-oxidizing activity of sediment].

    Science.gov (United States)

    Dong, Chun-hong; Hu, Hong-ying; Wei, Dong-bin; Huang, Xia; Qian, Yi

    2004-03-01

    The inhibition of 24 aromatics on ammonia-oxidizing activity of nitrifying bacteria in sediment was measured. The effects of the kind, number and position of substituted groups on ammonia-oxidizing activity of nitrifying bacteria were discussed. The inhibition of mono-substituted benzenes on ammonia-oxidizing activity of nitrifying bacteria were in order of -OH > -NO2 > -NH2 > -Cl > -CH3 > -H. The position of substituted groups of di-substituted benzenes also affected the inhibition, and the inhibitions of dimethylbenzenes(xylene) were in order of meta-> ortho-> para-. The increase in number of substituted group on benzene-ring enhanced the inhibition of aromatics studied in this study on nitrifying bacteria. There was a linear relationship between inhibition (IC50, mumol.L-1) of aromatics on ammonia-oxidizing activity and total electronegativity (sigma E) of aromatics: lgIC50 = 14.72 - 0.91 sigma E.

  4. Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

    DEFF Research Database (Denmark)

    Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

    methanogens. Two pure strains of hydrogenotrophic methanogens (i.e: Methanoculleus bourgensis and Methanoculleus thermophiles) and two pure strains of SAO bacteria (i.e: Tepidanaerobacter acetatoxydans and Thermacetogenium phaeum) were inoculated under four different ammonia (0.26, 3, 5 and 7g NH4+-N......, the total incubation periods of hydrogenotrophic methanogens were significantly shorter compared to the SAO bacteria incubation periods. Thus, it seems that hydrogenotrophic methanogens could be equally, if not more, tolerant to high ammonia levels compared to SAO bacteria.......Substrates that contain high ammonia levels can cause inhibition on anaerobic digestion process and unstable biogas production. The aim of the current study was to assess the effects of different ammonia levels on pure strains of (syntrophic acetate oxidizing) SAO bacteria and hydrogenotrophic...

  5. Superradiance and flux conservation

    Science.gov (United States)

    Boonserm, Petarpa; Ngampitipan, Tritos; Visser, Matt

    2014-09-01

    The theoretical foundations of the phenomenon known as superradiance still continue to attract considerable attention. Despite many valiant attempts at pedagogically clear presentations, the effect nevertheless still continues to generate some significant confusion. Part of the confusion arises from the fact that superradiance in a quantum field theory context is not the same as superradiance (superfluorescence) in some condensed matter contexts; part of the confusion arises from traditional but sometimes awkward normalization conventions, and part is due to sometimes unnecessary confusion between fluxes and probabilities. We shall argue that the key point underlying the effect is flux conservation (and, in the presence of dissipation, a controlled amount of flux nonconservation), and that attempting to phrase things in terms of reflection and transmission probabilities only works in the absence of superradiance. To help clarify the situation we present a simple exactly solvable toy model exhibiting both superradiance and damping.

  6. Flux amplification in SSPX

    Science.gov (United States)

    Lodestro, Lynda; Hooper, E. B.; Jayakumar, R. J.; Pearlstein, L. D.; Wood, R. D.; McLean, H. S.

    2007-11-01

    Flux amplification---the ratio of poloidal flux enclosed between the magnetic and geometric axes to that between the separatrix and the geometric axis---is a key measure of efficiency for edge-current-driven spheromaks. With the new, modular capacitor bank, permitting flexible programming of the gun current, studies of flux amplification under various drive scenarios can be performed. Analysis of recent results of pulsed operation with the new bank finds an efficiency ˜ 0.2, in selected shots, of the conversion of gun energy to confined magnetic energy during the pulses, and suggests a route toward sustained efficiency at 0.2. Results of experiments, a model calculation of field build-up, and NIMROD simulations exploring this newly suggested scenario will be presented.

  7. First-order chemistry in the surface-flux layer

    DEFF Research Database (Denmark)

    Kristensen, L.; Andersen, C.E.; Ejsing Jørgensen, Hans;

    1997-01-01

    We have discussed the behavior of a non-conserved scalar in the stationary, horizontally homogeneous, neutral surface-flux layer and, on the basis of conventional second-order closure, derived analytic expressions for flux and for mean concentration of a gas, subjected to a first-order removal...... process, The analytic flux solution showed a clear deviation from the constant flux, characterizing a conserved scalar in the surface-flux layer. It decreases with height and is reduced by an order of magnitude of the surface flux at a height equal to about the typical mean distance a molecule can travel...... of a characteristic turbulent time scale and the scalar mean lifetime. We show that if we use only first-order closure and neglect the effect of the Damkohler ratio on the turbulent diffusivity we obtain another analytic solution for the profiles of the flux and the mean concentration which, from an experimental...

  8. Lignin solubilisation and gentle fractionation in liquid ammonia

    OpenAIRE

    Strassberger, Z.; Prinsen, P.; Klis, van der, M.; Es, van, B; Tanase, S.; Rothenberg, G.

    2014-01-01

    We present a simple method for solubilising lignin using liquid ammonia. Unlike water, which requires harsh conditions, ammonia can solubilise technical lignins, in particular kraft lignin. A commercial pine wood Kraft lignin (Indulin AT) was solubilized instantaneously at room temperature and 7–11 bars autogeneous pressure, while a commercial mixed wheat straw/Sarkanda grass soda lignin (Protobind™ 1000) was solubilized within 3 h at ambient temperature, and 30 min at. 85 °C. Hydroxide salts...

  9. Accelerated DFT-Based Design of Materials for Ammonia Storage

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Bialy, Agata; Blanchard, Didier;

    2015-01-01

    Future energy carriers are needed in order to lower the CO2 emissions resulting from the burning of fossil fuels. One possible energy carrier is ammonia, which can be stored safely and reversibly in metal halide ammines; however, the release often occurs in multiple steps at too high temperatures...... materials is the first known high-capacity ternary metal halide ammine, which we have subsequently synthesized and confirmed the ammonia storage properties using temperature-programmed desorption (TPD)....

  10. Isotopic Discrimination of Some Solutes in Liquid Ammonia

    Science.gov (United States)

    Taube, H.; Viste, A.

    1966-01-01

    The nitrogen isotopic discrimination of some salts and metals, studies in liquid ammonia solution at -50�C, decreases in magnitude in the order Pb{sup ++}, Ca{sup ++}, Li{sup +}, AG{sup +}, Na{sup +}, Li, K{sup +}, Na, K. The isotopic discrimination appears to provide qualitative information about the strength of the cation-solvent interaction in liquid ammonia.

  11. Ammonia corrodes solar modules; Salmiakgeist greift Module an

    Energy Technology Data Exchange (ETDEWEB)

    Petzold, Katrin

    2011-07-01

    Ammonia is an aggressive gas produced in animal shelters, which may cause corrosion of solar modules. Various institutions, e.g. DLG and TUeV Rheinland, therefore offer an ammonia test for solar modules. The TUeV Rheinland recently commissioned a walk-in test chamber and now issues an official seal of approval, while the DLG doubts the practical value of the test.

  12. Process for synthesis of ammonia borane for bulk hydrogen storage

    Science.gov (United States)

    Autrey, S Thomas [West Richland, WA; Heldebrant, David J [Richland, WA; Linehan, John C [Richland, WA; Karkamkar, Abhijeet J [Richland, WA; Zheng, Feng [Richland, WA

    2011-03-01

    The present invention discloses new methods for synthesizing ammonia borane (NH.sub.3BH.sub.3, or AB). Ammonium borohydride (NH.sub.4BH.sub.4) is formed from the reaction of borohydride salts and ammonium salts in liquid ammonia. Ammonium borohydride is decomposed in an ether-based solvent that yields AB at a near quantitative yield. The AB product shows promise as a chemical hydrogen storage material for fuel cell powered applications.

  13. Exhaust purification with on-board ammonia production

    Science.gov (United States)

    Robel, Wade J.; Driscoll, James Joshua; Coleman, Gerald N.

    2008-05-13

    A system of ammonia production for a selective catalytic reduction system is provided. The system includes producing an exhaust gas stream within a cylinder group, wherein the first exhaust gas stream includes NOx. The exhaust gas stream may be supplied to an exhaust passage and cooled to a predetermined temperature range, and at least a portion of the NOx within the exhaust gas stream may be converted into ammonia.

  14. Ammonia concentration modeling based on retained gas sampler data

    Energy Technology Data Exchange (ETDEWEB)

    Terrones, G.; Palmer, B.J.; Cuta, J.M.

    1997-09-01

    The vertical ammonia concentration distributions determined by the retained gas sampler (RGS) apparatus were modeled for double-shell tanks (DSTs) AW-101, AN-103, AN-104, and AN-105 and single-shell tanks (SSTs) A-101, S-106, and U-103. One the vertical transport of ammonia in the tanks were used for the modeling. Transport in the non-convective settled solids and floating solids layers is assumed to occur primarily via some type of diffusion process, while transport in the convective liquid layers is incorporated into the model via mass transfer coefficients based on empirical correlations. Mass transfer between the top of the waste and the tank headspace and the effects of ventilation of the headspace are also included in the models. The resulting models contain a large number of parameters, but many of them can be determined from known properties of the waste configuration or can be estimated within reasonable bounds from data on the waste samples themselves. The models are used to extract effective diffusion coefficients for transport in the nonconvective layers based on the measured values of ammonia from the RGS apparatus. The modeling indicates that the higher concentrations of ammonia seen in bubbles trapped inside the waste relative to the ammonia concentrations in the tank headspace can be explained by a combination of slow transport of ammonia via diffusion in the nonconvective layers and ventilation of the tank headspace by either passive or active means. Slow transport by diffusion causes a higher concentration of ammonia to build up deep within the waste until the concentration gradients between the interior and top of the waste are sufficient to allow ammonia to escape at the same rate at which it is being generated in the waste.

  15. Global Ecological Pattern of Ammonia-Oxidizing Archaea

    OpenAIRE

    Huiluo Cao; Jean-Christophe Auguet; Ji-Dong Gu

    2013-01-01

    BACKGROUND: The global distribution of ammonia-oxidizing archaea (AOA), which play a pivotal role in the nitrification process, has been confirmed through numerous ecological studies. Though newly available amoA (ammonia monooxygenase subunit A) gene sequences from new environments are accumulating rapidly in public repositories, a lack of information on the ecological and evolutionary factors shaping community assembly of AOA on the global scale is apparent. METHODOLOGY AND RESULTS: We condu...

  16. HISTIDINE BIOTRANSFORMATION MEDIATED BY L-HISTIDINE-AMMONIA-LYASE

    OpenAIRE

    Borisova, G.; Bessonova, O.

    2013-01-01

    Kinetics of the metabolism of the heterocyclic amino acid histidine exposed to the L-histidine ammonia-lyase enzyme has been investigated and the technology of extraction of histidine biotransformation products (urocanic acid and ammonia) from casein hydrolyzates enabling the subsequent use of these hydrolyzates as a milk protein concentrate for the production of specialized dietary products for the nutrition of histidinemia patients has been developed.

  17. Applying an Inverse Model to Estimate Ammonia Emissions at Cattle Feedlots Using Three Different Observation-Based Approaches

    Science.gov (United States)

    Shonkwiler, K. B.; Ham, J. M.; Nash, C.

    2014-12-01

    Accurately quantifying emissions of ammonia (NH3) from confined animal feeding operations (CAFOs) is vital not only to the livestock industry, but essential to understanding nitrogen cycling along the Front Range of Colorado, USA, where intensive agriculture, urban sprawl, and pristine ecosystems (e.g., Rocky Mtn Nat'l Park) lie within 100-km of each other. Most observation-based techniques for estimating NH3 emissions can be expensive and highly technical. Many methods rely on concentration observations on location, which implicitly depends on weather conditions. A system for sampling NH3 using on-site weather data was developed to allow remote measurement of NH3 in a simple, cost-effective way. These systems use passive diffusive cartridges (Radiello, Sigma-Aldrich) that provide time-averaged concentrations representative of a typical two-week deployment. Cartridge exposure is robotically managed so they are only visible when winds are 1.4 m/s or greater from the direction of the CAFO. These concentration data can be coupled with stability parameters (measured on-site) in a simple inverse model to estimate emissions (FIDES, UMR Environnement et Grandes Cultures). Few studies have directly compared emissions estimates of NH3 using concentration data obtained from multiple measurement systems at different temporal and spatial scales. Therefore, in the summer and autumn of 2014, several conditional sampler systems were deployed at a 25,000-head cattle feedlot concomitant with an open-path infrared laser (GasFinder2, Boreal Laser Inc.) and a Cavity Ring Down Spectrometer (CRDS) (G1103, Picarro Inc.) which each measured instantaneous NH3 concentrations. This study will test the sampler technology by first comparing concentration data from the three different methods. In livestock research, it is common to estimate NH3 emissions by using such instantaneous data in a backward Lagrangian stochastic (bLs) model (WindTrax, Thunder Beach Sci.) Considering this, NH3 fluxes

  18. Eddy Correlation Flux Measurement System Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind components and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.

  19. Solar Magnetic Flux Ropes

    Indian Academy of Sciences (India)

    Boris Filippov; Olesya Martsenyuk; Abhishek K. Srivastava; Wahab Uddin

    2015-03-01

    In the early 1990s, it was found that the strongest disturbances of the space–weather were associated with huge ejections of plasma from the solar corona, which took the form of magnetic clouds when moved from the Sun. It is the collisions of the magnetic clouds with the Earth's magnetosphere that lead to strong, sometimes catastrophic changes in space–weather. The onset of a coronal mass ejection (CME) is sudden and no reliable forerunners of CMEs have been found till date. The CME prediction methodologies are less developed compared to the methods developed for the prediction of solar flares. The most probable initial magnetic configuration of a CME is a flux rope consisting of twisted field lines which fill the whole volume of a dark coronal cavity. The flux ropes can be in stable equilibrium in the coronal magnetic field for weeks and even months, but suddenly they lose their stability and erupt with high speed. Their transition to the unstable phase depends on the parameters of the flux rope (i.e., total electric current, twist, mass loading, etc.), as well as on the properties of the ambient coronal magnetic field. One of the major governing factors is the vertical gradient of the coronal magnetic field, which is estimated as decay index (). Cold dense prominence material can be collected in the lower parts of the helical flux tubes. Filaments are, therefore, good tracers of the flux ropes in the corona, which become visible long before the beginning of the eruption. The perspectives of the filament eruptions and following CMEs can be estimated by a comparison of observed filament heights with calculated decay index distributions. The present paper reviews the formation of magnetic flux ropes, their stable and unstable phases, eruption conditions, and also discusses their physical implications in the solar corona.

  20. [Isolation of heterotrophic nitrifiers which can tolerate high concentration of ammonia-nitrogen and the optimization of their nitrogen removal efficiency in wastewater].

    Science.gov (United States)

    Si, Wen-Gong; Lü, Zhi-Gang; Xu, Chao

    2011-11-01

    The removal capabilities and tolerance of high concentration of ammonia-nitrogen of heterotrophic nitrifiers were studied. Methods included multi-point sampling, domestication, gradient dilution of domestication liquid, color indicator as rapid nitrification detection and isolation from streaking plate were conducted to screen heterotrophic nitrifiers. The strains were identified according to the sequence analysis of 16S rDNA. After inoculating the strains into ammonia-nitrogen wastewater, changes of nitrogen compounds were measured in order to understand their denitrification characteristics. The denitrification efficiency was optimized by improving the C/N ratio, changing the compatibility of the strains and mixing the compatible strains with the domesticated bacterial suspension. Finally 8 high-efficiency heterotrohic nitrifiers were obtained, and named as N1-N8 respectively. Phylogenetic analysis showed that 8 strains belonged to Comamonas genus, Rhodococcus genus, Pseudomonos genus, Arthrobacter genus and Paracoccus genus, respectively. When the initial concentration of ammonia nitrogen was 256.9 mg x L(-1) and the C/N was 5.5 of the artificial wastewater, the removal rates of ammonia nitrogen by the strains were about 65%-80%, and the stain N4 was the best. When the C/N ratio of the wastewater increased to 8.0, the ammonia nitrogen removal rates of the strains correspondingly increased to about 80% -90%. As the strains compatibility, the denitrification rate of N4 + N5 + N6 was 88.2% in the artificial wastewater with initial ammonia nitrogen concentration was 261.1 mg x L(-1) and initial C/N ratio was 5.5, which was higher than that of any single strain. The ammonia nitrogen removal rate could reach to 99.8% when N4 + N5 + N6 were combined with the domesticated bacterial suspension. In the artificial wastewater, when the initial ammonia nitrogen increased to 446.9 mg x L(-1) and the C/N ratio decreased to 3.2, the ammonia nitrogen removal rate of the mixed

  1. Thaumarchaeal Ammonia Oxidation in an Acidic Forest Peat Soil Is Not Influenced by Ammonium Amendment▿ †

    OpenAIRE

    Stopnišek, Nejc; Gubry-Rangin, Cécile; Höfferle, Špela; Nicol, Graeme W.; Mandič-Mulec, Ines; Prosser, James I.

    2010-01-01

    Both bacteria and thaumarchaea contribute to ammonia oxidation, the first step in nitrification. The abundance of putative ammonia oxidizers is estimated by quantification of the functional gene amoA, which encodes ammonia monooxygenase subunit A. In soil, thaumarchaeal amoA genes often outnumber the equivalent bacterial genes. Ecophysiological studies indicate that thaumarchaeal ammonia oxidizers may have a selective advantage at low ammonia concentrations, with potential adaptation to soils...

  2. Optimality in the zonation of ammonia detoxification in rodent liver.

    Science.gov (United States)

    Bartl, Martin; Pfaff, Michael; Ghallab, Ahmed; Driesch, Dominik; Henkel, Sebastian G; Hengstler, Jan G; Schuster, Stefan; Kaleta, Christoph; Gebhardt, Rolf; Zellmer, Sebastian; Li, Pu

    2015-11-01

    The rodent liver eliminates toxic ammonia. In mammals, three enzymes (or enzyme systems) are involved in this process: glutaminase, glutamine synthetase and the urea cycle enzymes, represented by carbamoyl phosphate synthetase. The distribution of these enzymes for optimal ammonia detoxification was determined by numerical optimization. This in silico approach predicted that the enzymes have to be zonated in order to achieve maximal removal of toxic ammonia and minimal changes in glutamine concentration. Using 13 compartments, representing hepatocytes, the following predictions were generated: glutamine synthetase is active only within a narrow pericentral zone. Glutaminase and carbamoyl phosphate synthetase are located in the periportal zone in a non-homogeneous distribution. This correlates well with the paradoxical observation that in a first step glutamine-bound ammonia is released (by glutaminase) although one of the functions of the liver is detoxification by ammonia fixation. The in silico approach correctly predicted the in vivo enzyme distributions also for non-physiological conditions (e.g. starvation) and during regeneration after tetrachloromethane (CCl4) intoxication. Metabolite concentrations of glutamine, ammonia and urea in each compartment, representing individual hepatocytes, were predicted. Finally, a sensitivity analysis showed a striking robustness of the results. These bioinformatics predictions were validated experimentally by immunohistochemistry and are supported by the literature. In summary, optimization approaches like the one applied can provide valuable explanations and high-quality predictions for in vivo enzyme and metabolite distributions in tissues and can reveal unknown metabolic functions.

  3. Interorgan ammonia metabolism in health and disease: a surgeon's view.

    Science.gov (United States)

    Souba, W W

    1987-01-01

    Ammonia is a toxic molecule that is the principal by-product of amino acid metabolism. Although the transport of ammonia in a nontoxic form protects the brain against high circulating levels, the interorgan transport of this molecule and the orchestration between tissues that has evolved is related primarily to the fact that the nitrogen molecule is an essential molecule for the maintenance of the body's nutrition economy and overall metabolic homeostasis. Efficient handling and disposal of ammonia requires a cooperative effort between tissues in order to maintain nitrogen homeostasis. The liver is the central organ of ammonia metabolism, but other organs also play a key role in the interorgan exchange of this molecule. Alterations in ammonia metabolism occur during critical illness. These changes are adaptive and are designed to maintain metabolic homeostasis. Interorgan cooperation in ammonia metabolism is necessary to insure the proper integration of the metabolic processes which contribute to and are essential for survival during critical illness. An understanding of these processes improves our knowledge of metabolic regulation and will lead to a rational approach to the nutritional and metabolic support provided to critically ill patients. PMID:3323556

  4. Triply deuterated ammonia in NGC 1333

    CERN Document Server

    Van der Tak, F F S; Müller, H S P; Lis, D C; Phillips, T G; Gerin, M; Roueff, E

    2002-01-01

    The Caltech Submillimeter Observatory has detected triply deuterated ammonia, ND3, through its 10a-00s transition near 310 GHz. Emission is found in the NGC 1333 region, both towards IRAS 4A and a position to the South-East where DCO+ peaks. In both cases, the hyperfine ratio indicates that the emission is optically thin. Column densities of ND3 are 3--6 x 10^11 cm^-2 for T_ex=10 K and twice as high for T_ex=5 K. Using a Monte Carlo radiative transfer code and a model of the structure of the IRAS source with temperature and density gradients, the estimated ND3 abundance is 3.2 x 10^-12 if ND3/H2 is constant throughout the envelope. In the more likely case that ND3/H2D+ is constant, ND3/H2 peaks in the cold outer parts of the source at a value of 1.0 x 10^-11. To reproduce the observed NH3/ND3 abundance ratio of ~1000, grain surface chemistry requires an atomic D/H ratio of ~0.15 in the gas phase, >10 times higher than in recent chemical models. More likely, the deuteration of NH3 occurs by ion-molecule reacti...

  5. Concentration and flux of bioaerosol and environmental factors

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The concentration and flux transportation of bioaerosol are analyzed using the data observed in Nanjing in July 1998. Some results are obtained: (i) the concentration and flux transportation of bioaerosol vary periodically with the cycle of the solar radiation and atmospheric turbulent intensity, (ii) The bioaerosol concentration is affected by both the bioaerosol flux transportation and the environmental factors. The bacterial concentration is obviously affected by the solar radiation while the fungi concentration is significantly affected by temperature.

  6. Glasses obtained from industrial wastes

    International Nuclear Information System (INIS)

    This paper deals with the study of the vitrification mechanism as an inertization method for industrial wastes contaminated with heavy metals. Ashes from coal (thermoelectric), wastes from mining (fluorite and feldspar) and plating residue were used to compose vitreous systems planed by mixture design. The chemical composition of the wastes was determined by XRF and the formulations were melted at 1450 deg C for 2h using 10%wt of CaCO3 (fluxing agent). The glasses were poured into a mold and annealed (600 deg C). The characteristic temperatures were determined by thermal analysis (DTA, air, 20 deg C/min) and the mechanical behavior by Vickers microhardness. As a result, the melting temperature is strongly dependent on silica content of each glass, and the fluorite residue, being composed mainly by silica, strongly affects Tm. The microhardness of all glasses is mainly affected by the plating residue due to the high iron and zinc content of this waste. (author)

  7. High-resolution ammonia mapping of the very young protostellar core Chamaeleon-MMS1

    Science.gov (United States)

    Väisälä, M. S.; Harju, J.; Mantere, M. J.; Miettinen, O.; Sault, R. S.; Walmsley, C. M.; Whiteoak, J. B.

    2014-04-01

    Aims: The aim of this study is to investigate the structure and kinematics of the nearby candidate first hydrostatic core Cha-MMS1. Methods: Cha-MMS1 was mapped in the NH3(1,1) line and the 1.2 cm continuum using the Australia Telescope Compact Array (ATCA). The angular resolution of the ATCA observations is 7″ (~1000 AU), and the velocity resolution is 50 m s-1. The core was also mapped with the 64 m Parkes Telescope in the NH3(1,1) and (2,2) lines. Observations from Herschel Space Observatory and Spitzer Space Telescope were used to help interpretation. The ammonia spectra were analysed using Gaussian fits to the hyperfine structure. A two-layer model was applied in the central parts of the core where the ATCA spectra show signs of self-absorption. Results: A compact high column density core with a steep velocity gradient (~20 km s-1 pc-1) is detected in ammonia. We derive a high gas density (~106 cm-3) in this region, and a fractional ammonia abundance compatible with determinations towards other dense cores (~10-8). This suggests that the age of the high density core is comparable to the freeze-out timescale of ammonia in these conditions, on the order of 104 years. The direction of the velocity gradient agrees with previous single-dish observations, and the overall velocity distribution can be interpreted as rotation. The rotation axis goes through the position of a compact far-infrared source detected by Spitzer and Herschel. The specific angular momentum of the core, ~10-3km s-1 pc, is typical for protostellar envelopes. A string of 1.2 cm continuum sources is tentatively detected near the rotation axis. The ammonia spectra suggest the presence of warm embedded gas in its vicinity. An hourglass-shaped structure is seen in ammonia at the cloud's average LSR velocity, also aligned with the rotation axis. Although this structure resembles a pair of outflow lobes the ammonia spectra show no indications of shocked gas. Conclusions: The observed ammonia

  8. Flux pinning and flux flow studies in superconductors using flux flow noise techniques. Progress report, April 1, 1976--December 17, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Joiner, W.C.H.

    1976-12-01

    Measurements of flux flow noise power spectra have been combined with critical current measurements and measurements of current-voltage characteristics to study flux flow and local pinning interactions effective during flux flow. A model of flux flow noise generation in the presence of local pinning interactions is developed and applied to situations where pinning is dominated by: (1) grain boundaries, (2) normal metal precipitates in a superconducting matrix, (3) gross deformation producing a critical current peak effect, and (4) surface grooves imposed on a sample surface. In the case of pinning caused by normal metal precipitates in a superconducting matrix, unusual training and hysterisis effects are observed in the flux flow characteristics. The greater sensitivity of noise spectra, as compared with bulk critical current measurements, in obtaining a detailed picture of flux flow is emphasized.

  9. Flux pinning and flux flow studies in superconductors using flux flow noise techniques. Progress report, April 1, 1976--December 17, 1976

    International Nuclear Information System (INIS)

    Measurements of flux flow noise power spectra have been combined with critical current measurements and measurements of current-voltage characteristics to study flux flow and local pinning interactions effective during flux flow. A model of flux flow noise generation in the presence of local pinning interactions is developed and applied to situations where pinning is dominated by: (1) grain boundaries, (2) normal metal precipitates in a superconducting matrix, (3) gross deformation producing a critical current peak effect, and (4) surface grooves imposed on a sample surface. In the case of pinning caused by normal metal precipitates in a superconducting matrix, unusual training and hysterisis effects are observed in the flux flow characteristics. The greater sensitivity of noise spectra, as compared with bulk critical current measurements, in obtaining a detailed picture of flux flow is emphasized

  10. Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant

    OpenAIRE

    Sauder, L.A.; Peterse, F.; Schouten, S; Neufeld, J. D.

    2012-01-01

    The first step of nitrification is catalysed by both ammonia-oxidizing bacteria (AOB) and archaea (AOA), but physicochemical controls on the relative abundance and function of these two groups are not yet fully understood, especially in freshwater environments. This study investigated ammonia-oxidizing populations in nitrifying rotating biological contactors (RBCs) from a municipal wastewater treatment plant. Individual RBC stages are arranged in series, with nitrification at each stage creat...

  11. The influence of gas-particle partitioning and surface-atmosphere exchange on ammonia during BAQS-Met

    Directory of Open Access Journals (Sweden)

    R. A. Ellis

    2011-01-01

    Full Text Available The Border Air Quality and Meteorology study (BAQS-Met was an intensive field campaign conducted in Southwestern Ontario during the summer of 2007. The focus of BAQS-Met was determining the causes of the formation of ozone and fine particulate matter (PM2.5, and of the regional significance of trans-boundary transport and lake breeze circulations on that formation. Fast (1 Hz measurements of ammonia were acquired using a Quantum Cascade Laser Tunable Infrared Differential Absorption Spectrometer (QC-TILDAS at the Harrow supersite. Measurements of PM2.5 ammonium, sulfate and nitrate were made using an Ambient Ion Monitor Ion Chromatograph (AIM-IC with hourly time resolution. The median mixing ratio of ammonia was 2.5 ppb, with occasional high spikes at night resulting from local emissions. Measurements were used to assess major local emissions of NH3, diurnal profiles and gas-particle partitioning. The measurements were compared with results from A Unified Regional Air-quality Modelling System (AURAMS. While the fraction of total ammonia (NHx≡NH3 + NH4+ observed in the gas phase peaks between 0.1 and 0.8, AURAMS tended to predict fractions of either less than 0.05 or greater than 0.8. The model frequently predicted acidic aerosol, in contrast with observations wherein NHx almost always exceeded the observed equivalents of sulfate. One explanation for our observations is that the net flux of ammonia from the land surface to the atmosphere increases when aerosol sulfate is present, effectively buffering the mixing ratio of gas phase ammonia, a process not included in the model. A simple representation of an offline bi-directional flux parameterization using the ISORROPIA thermodynamic model was successful at reducing the population of zero gas fraction points, but not the higher gas fraction points.

  12. Disconnecting Solar Magnetic Flux

    CERN Document Server

    DeForest, C E; McComas, D J

    2011-01-01

    Disconnection of open magnetic flux by reconnection is required to balance the injection of open flux by CMEs and other eruptive events. Making use of recent advances in heliospheric background subtraction, we have imaged many abrupt disconnection events. These events produce dense plasma clouds whose distinctie shape can now be traced from the corona across the inner solar system via heliospheric imaging. The morphology of each initial event is characteristic of magnetic reconnection across a current sheet, and the newly-disconnected flux takes the form of a "U"-shaped loop that moves outward, accreting coronal and solar wind material. We analyzed one such event on 2008 December 18 as it formed and accelerated at 20 m/s^2 to 320 km/s, expanding self-similarly until it exited our field of view 1.2 AU from the Sun. From acceleration and photometric mass estimates we derive the coronal magnetic field strength to be 8uT, 6 Rs above the photosphere, and the entrained flux to be 1.6x10^11 Wb (1.6x10^19 Mx). We mod...

  13. Coupled superconducting flux qubits

    NARCIS (Netherlands)

    Plantenberg, J.H.

    2007-01-01

    This thesis presents results of theoretical and experimental work on superconducting persistent-current quantum bits. These qubits offer an attractive route towards scalable solid-state quantum computing. The focus of this work is on the gradiometer flux qubit which has a special geometric design, t

  14. Tolerance response to in situ ammonia stress in a pilot-scale anaerobic digestion reactor for alleviating ammonia inhibition.

    Science.gov (United States)

    Gao, Shumei; Zhao, Mingxing; Chen, Yang; Yu, Meijuan; Ruan, Wenquan

    2015-12-01

    The anaerobic digestion (AD) of protein-rich substrates is generally inhibited by ammonia. In this study, ammonia-tolerant acclimation was exposed to a stepwise in situ ammonia stress during the continuous AD of solid residual kitchen waste by using a continuous stirred tank reactor with a 50 L active volume. The reactor worked well during the acclimation process, with an average daily biogas production of 58 L/d, an effluent soluble chemical oxygen demand of 7238 mg/L, a volatile fatty acid (VFA) content of 578 mg/L, and a VFA/alkalinity ratio of less than 0.4. Moreover, ammonia stress enhanced the activity of Coenzyme F420. The results of high-throughput 16S rDNA sequencing showed that ammonia stress increased the relative abundance of Firmicutes bacteria and hydrogenotrophic methanogens but decreased the abundance of acetotrophic methanogens. This microbial community shift was proposed to be an in situ response strategy for ammonia stress adaptation.

  15. Ammonia regeneration for a combined lime/ammonia spray dryer for SO{sub 2} control. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Xinjian, Yang [Cincinnati Univ., OH (United States). Dept. of Civil and Environmental Engineering

    1992-12-23

    A research project designed to study the feasibility of ammonia regeneration for a combined lime/ammonia FGD process was conducted at the University of Cincinnati. The major objective for this project was to regenerate ammonia from a combined ammonia/calcium hydroxide spray dryer FGD byproduct for reuse which would reduce the operating cost of this FGD process. This final report covers the six phases of the project: (1) generation of original feedstock, (2) batch regeneration studies, (3) continuous regeneration studies, (4) waste characteristic analysis, (5) pilot scale demonstration and (6) economic analysis. This research has shown that regeneration of ammonia is feasible at a reasonable cost. The effects on Ohio coal use from the results of this research could be substantial, depending on the Phase II application of FGD systems for controlling SO{sub 2} emissions. In conclusion, experiments in this study have shown that ammonia recovery efficiencies greater than 90% are technically and economically feasible. In addition, the sludge produced from the regeneration process is stable and will meet existing Federal standards.

  16. Ammonia oxidizing bacteria and archaea in horizontal flow biofilm reactors treating ammonia-contaminated air at 10 °C.

    Science.gov (United States)

    Gerrity, Seán; Clifford, Eoghan; Kennelly, Colm; Collins, Gavin

    2016-05-01

    The objective of this study was to demonstrate the feasibility of novel, Horizontal Flow Biofilm Reactor (HFBR) technology for the treatment of ammonia (NH3)-contaminated airstreams. Three laboratory-scale HFBRs were used for remediation of an NH3-containing airstream at 10 °C during a 90-d trial to test the efficacy of low-temperature treatment. Average ammonia removal efficiencies of 99.7 % were achieved at maximum loading rates of 4.8 g NH3 m(3) h(-1). Biological nitrification of ammonia to nitrite (NO2 (-)) and nitrate (NO3 (-)) was mediated by nitrifying bacterial and archaeal biofilm populations. Ammonia-oxidising bacteria (AOB) were significantly more abundant than ammonia-oxidising archaea (AOA) vertically at each of seven sampling zones along the vertical HFBRs. Nitrosomonas and Nitrosospira, were the two most dominant bacterial genera detected in the HFBRs, while an uncultured archaeal clone dominated the AOA community. The bacterial community composition across the three HFBRs was highly conserved, although variations occurred between HFBR zones and were driven by physicochemical variables. The study demonstrates the feasibility of HFBRs for the treatment of ammonia-contaminated airstreams at low temperatures; identifies key nitrifying microorganisms driving the removal process; and provides insights for process optimisation and control. The findings are significant for industrial applications of gas oxidation technology in temperate climates. PMID:26879980

  17. Aerodynamic gradient measurements of the NH3-HNO3-NH4NO3 triad using a wet chemical instrument: an analysis of precision requirements and flux errors

    OpenAIRE

    V. Wolff; Trebs, I.; Ammann, C.; Meixner, F. X.

    2010-01-01

    The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad) and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient). The significance of the measured concentration difference is crucial for the significant determination of surface exchange fluxes. Additionally,...

  18. Dynamics of ammonia exchange with cut grassland: synthesis of results and conclusions of the GRAMINAE Integrated Experiment

    Directory of Open Access Journals (Sweden)

    M. A. Sutton

    2009-12-01

    Full Text Available Improved data on biosphere-atmosphere exchange are fundamental to understanding the production and fate of ammonia (NH3 in the atmosphere. The GRAMINAE Integrated Experiment combined novel measurement and modelling approaches to provide the most comprehensive analysis of the interactions to date. Major inter-comparisons of micrometeorological parameters and NH3 flux measurements using the aerodynamic gradient method and relaxed eddy accumulation (REA were conducted. These showed close agreement, though the REA systems proved insufficiently precise to investigate vertical flux divergence. Grassland management had a large effect on fluxes: emissions increased after grass cutting (−50 to 700 ng m−2 s−1 NH3 and after N-fertilization (0 to 3800 ng m−2 s−1 compared with before the cut (−60 to 40 ng m−2 s−1.

    Effects of advection and air chemistry were investigated using horizontal NH3 profiles, acid gas and particle flux measurements. Inverse modelling of NH3 emission from an experimental farm agreed closely with inventory estimates, while advection errors were used to correct measured grassland fluxes. Advection effects were caused both by the farm and by emissions from the field, with an inverse dispersion-deposition model providing a reliable new approach to estimate net NH3 fluxes. Effects of aerosol chemistry on net NH3 fluxes were small, while the measurements allowed NH3-induced particle growth rates to be calculated and aerosol fluxes to be corrected.

    Bioassays estimated the emission potential Γ = [NH4+]/[H+] for different plant pools, with the apoplast having the smallest values (30–1000. The main within-canopy sources of NH3 emission appeared to be leaf litter and the soil surface, with Γ up to 3 million and

  19. Quantifying Representation and Using Representation Weights to Interpolate Flux Tower Measurements across the United States

    Science.gov (United States)

    Hargrove, W. W.; Hoffman, F. M.

    2003-12-01

    We are using a new multivariate statistical technique to quantitatively divide the lower 48 United States into a series of flux-relevant ecoregions. On the basis of these flux-relevant ecoregions, we will quantify the representativeness of the existing network of AmeriFlux towers, showing how well each ecoregion is represented by the current stations in the AmeriFlux network. Quantifying AmeriFlux representation will indicate the best locations where additional AmeriFlux towers should be placed. Using a "paint-by-number" approach, we are attempting to use the flux ecoregions as the statistical basis for extrapolating measurements made at the 52 actively-reporting AmeriFlux towers into a continuous 1-km grid across the United States seasonally. We will use the similarity of the suite of flux-relevant ecosystem characteristics to modify existing flux measurements and estimate fluxes within unmeasured flux ecoregions. Weights calculated for each environmental gradient will allow us to mix new "paint-by-number" colors, extending the process beyond the palette of existing flux measurements. The map of 2000 to 5000 flux ecoregions will produce a highly-resolved national map of estimated fluxes, and will be equivalent to creating thousands of new "virtual" flux towers across the nation. Once flux ecoregions and representation weights have been determined, it may be possible to use them to obtain an interpolated grid of the estimated flux at any point in time across the United States.

  20. Simulating Idealized Flux Ropes with the Flux Rope Insertion Method: A Parameter Space Exploration of Currents and Topology

    Science.gov (United States)

    Savcheva, Antonia; Tassev, Svetlin; DeLuca, Edward E.; Gibson, Sarah; Fan, Yuhong

    2016-05-01

    Knowledge of the 3D magnetic filed structure at the time of major solar eruptions is vital to the understanding of the space weather effects of these eruptions. Multiple data-constrained techniques that reconstruct the 3D coronal field based on photospheric magnetograms have been used to achieve this goal. In particular, we have used the flux rope insertion method to obtain the coronal magnetic field of multiple regions containing flux ropes or sheared arcades based on line-of-sight magnetograms and X-ray and EUV observations of coronal loops. For the purpose of developing statistical measures of the goodness of fit of these models to the observations, here we present our modeling of flux ropes based on synthetic magnetograms obtained from aFan & Gibson emerging flux rope simulation. The goal is to study the effect of of different input flux rope parameters on the geometry of currents, field line connectivity, and topology, in a controled setting. For this purpose we create a large grid of models with the flux rope insertion method with different combinations of axial and poloidal flux, which give us different morphology of the flux rope. We create synthetic images of these flux ropes in AIA passbands with the FORWARD forward-fitting code. The present parametric study will later be used to get a better handle on the initial condition for magnetofrictional and MHD simulations of observed regions containing flux ropes, such as sigmoids and polar-crown filaments.

  1. Path integral Liouville dynamics: Applications to infrared spectra of OH, water, ammonia, and methane

    International Nuclear Information System (INIS)

    Path integral Liouville dynamics (PILD) is applied to vibrational dynamics of several simple but representative realistic molecular systems (OH, water, ammonia, and methane). The dipole-derivative autocorrelation function is employed to obtain the infrared spectrum as a function of temperature and isotopic substitution. Comparison to the exact vibrational frequency shows that PILD produces a reasonably accurate peak position with a relatively small full width at half maximum. PILD offers a potentially useful trajectory-based quantum dynamics approach to compute vibrational spectra of molecular systems

  2. Path integral Liouville dynamics: Applications to infrared spectra of OH, water, ammonia, and methane.

    Science.gov (United States)

    Liu, Jian; Zhang, Zhijun

    2016-01-21

    Path integral Liouville dynamics (PILD) is applied to vibrational dynamics of several simple but representative realistic molecular systems (OH, water, ammonia, and methane). The dipole-derivative autocorrelation function is employed to obtain the infrared spectrum as a function of temperature and isotopic substitution. Comparison to the exact vibrational frequency shows that PILD produces a reasonably accurate peak position with a relatively small full width at half maximum. PILD offers a potentially useful trajectory-based quantum dynamics approach to compute vibrational spectra of molecular systems. PMID:26801034

  3. Path integral Liouville dynamics: Applications to infrared spectra of OH, water, ammonia, and methane

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian, E-mail: jianliupku@pku.edu.cn [Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Zhang, Zhijun [Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2016-01-21

    Path integral Liouville dynamics (PILD) is applied to vibrational dynamics of several simple but representative realistic molecular systems (OH, water, ammonia, and methane). The dipole-derivative autocorrelation function is employed to obtain the infrared spectrum as a function of temperature and isotopic substitution. Comparison to the exact vibrational frequency shows that PILD produces a reasonably accurate peak position with a relatively small full width at half maximum. PILD offers a potentially useful trajectory-based quantum dynamics approach to compute vibrational spectra of molecular systems.

  4. Heat flux anomalies in Antarctica revealed from satellite magnetic data

    DEFF Research Database (Denmark)

    Maule, Cathrine Fox; Purucker, Michael E.; Olsen, Nils;

    2005-01-01

    The geothermal heat flux is an important factor in the dynamics of ice sheets; it affects the occurrence of subglacial lakes, the onset of ice streams, and mass losses from the ice sheet base. Because direct heat flux measurements in ice-covered regions are difficult to obtain, we developed a met...

  5. Habitat-associated phylogenetic community patterns of microbial ammonia oxidizers.

    Directory of Open Access Journals (Sweden)

    Antoni Fernàndez-Guerra

    Full Text Available Microorganisms mediating ammonia oxidation play a fundamental role in the connection between biological nitrogen fixation and anaerobic nitrogen losses. Bacteria and Archaea ammonia oxidizers (AOB and AOA, respectively have colonized similar habitats worldwide. Ammonia oxidation is the rate-limiting step in nitrification, and the ammonia monooxygenase (Amo is the key enzyme involved. The molecular ecology of this process has been extensively explored by surveying the gene of the subunit A of the Amo (amoA gene. In the present study, we explored the phylogenetic community ecology of AOB and AOA, analyzing 5776 amoA gene sequences from >300 isolation sources, and clustering habitats by environmental ontologies. As a whole, phylogenetic richness was larger in AOA than in AOB, and sediments contained the highest phylogenetic richness whereas marine plankton the lowest. We also observed that freshwater ammonia oxidizers were phylogenetically richer than their marine counterparts. AOA communities were more dissimilar to each other than those of AOB, and consistent monophyletic lineages were observed for sediments, soils, and marine plankton in AOA but not in AOB. The diversification patterns showed a more constant cladogenesis through time for AOB whereas AOA apparently experienced two fast diversification events separated by a long steady-state episode. The diversification rate (γ statistic for most of the habitats indicated γ(AOA > γ(AOB. Soil and sediment experienced earlier bursts of diversification whereas habitats usually eutrophic and rich in ammonium such as wastewater and sludge showed accelerated diversification rates towards the present. Overall, this work shows for the first time a global picture of the phylogenetic community structure of both AOB and AOA assemblages following the strictest analytical standards, and provides an ecological view on the differential evolutionary paths experienced by widespread ammonia

  6. Extraction of molybdenum and vanadium from the spent diesel exhaust catalyst by ammonia leaching method

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhipeng; Guo, Min, E-mail: guomin@ustb.edu.cn; Zhang, Mei

    2015-04-09

    Highlights: • Mo and V were extracted from spent diesel exhaust catalyst by ammonia leaching method. • Effects of leaching parameters on the extraction of Mo and V were studied in detail. • The extraction efficiencies of Mo and V could reach 94.96% and 39.73%. • The leaching solution and the residue can be reused for preparing new catalyst. - Abstract: Molybdenum (Mo) and vanadium (V) were effectively extracted from the spent diesel exhaust catalyst (V{sub 2}O{sub 5}–MoO{sub 3}/TiO{sub 2}) by using an ammonia leaching method. Meanwhile, the structure of the spent catalyst carrier (TiO{sub 2}) was not destroyed and might be reused. The effects of ammonia (NH{sub 3}·H{sub 2}O) concentration, leaching temperature and time, concentration of hydrogen peroxide (H{sub 2}O{sub 2}) and liquid to solid ratio on the extraction of Mo and V were systematically investigated. It is shown that the extraction efficiency of Mo increased from 68.68% to 96.45% while the extraction efficiency of V remained stable at 27% with increasing ammonia concentration from 2.95 to 7.38 mol/L, leaching temperature from 298.15 to 473.15 K, and reaction time from 1 to 8 h. With the concentration of H{sub 2}O{sub 2} solution increasing from 1.0 to 2.5 mol/L, the extraction efficiency of V increased from 26.87% to 39.73%. Under the optimum conditions (the ammonia concentration of 4.5 mol/L, leaching temperature of 413.15 K, reaction time of 2 h, the H{sub 2}O{sub 2} solution concentration of 1.0 mol/L and the liquid to solid ratio of 20/1 mL/g), the extraction efficiencies of Mo and V reached 95.13% and 46.25%. Moreover, the catalyst carrier TiO{sub 2} with anatase crystal phase was also obtained.

  7. [The Research for Trace Ammonia Escape Monitoring System Based on Tunable Diode Laser Absorption Spectroscopy].

    Science.gov (United States)

    Zhang, Li-fang; Wang, Fei; Yu, Li-bin; Yan, Jian-hua; Cen, Ke-fa

    2015-06-01

    In order to on-line measure the trace ammonia slip of the commercial power plant in the future, this research seeks to measure the trace ammonia by using tunable diode laser absorption spectroscopy under ambient temperature and pressure, and at different temperatures, and the measuring temperature is about 650 K in the power plant. In recent years lasers have become commercially available in the near-infrared where the transitions are much stronger, and ammonia's spectroscopy is pretty complicated and the overlapping lines are difficult to resolve. A group of ammonia transitions near 4 433.5 cm(-1) in the v2 +v3 combination band have been thoroughly selected for detecting lower concentration by analyzing its absorption characteristic and considering other absorption interference in combustion gases where H2O and CO2 mole fraction are very large. To illustrate the potential for NH3 concentration measurements, predictions for NH3, H2O and CO2 are simultaneously simulated, NH3 absorption lines near 4 433.5 cm(-1) wavelength meet weaker H2O absorption than the commercial NH3 lines, and there is almost no CO2 absorption, all the parameters are based on the HITRAN database, and an improved detection limit was obtained for interference-free NH3 monitoring, this 2.25 μm band has line strengths several times larger than absorption lines in the 1.53 μm band which was often used by NH3 sensors for emission monitoring and analyzing. The measurement system was developed with a new Herriott cell and a heated gas cell realizing fast absorption measurements of high resolution, and combined with direct absorption and wavelenguh modulation based on tunable diode laser absorption spectroscopy at different temperatures. The lorentzian line shape is dominant at ambient temperature and pressure, and the estimated detectivity is approximately 0.225 x 10(-6) (SNR = 1) for the directed absorption spectroscopy, assuming a noise-equivalent absorbance of 1 x 10(-4). The heated cell

  8. CuS Thin Films Obtained by Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Violeta POPESCU

    2004-02-01

    Full Text Available The paper presents a study concerning the influence of deposition parameters (reagents, electron donors, surfactants, temperature of the substrate, number of consecutive layers, spraying rate on the quality of CuS thin films achieved by spray pyrolysis on glass substrate, from solutions containing CuCl2·2H2O, thiourea, electron pair donors and surfactants. As electron pairs donors ammonia and triethanolamine were used and as surfactants C12 - C14 ether-sulphate, sodium lauryl-sulphate and cetyl-pyridinium bromide were used. The optimum conditions for the obtaining of optically clear, compact and adherent CuS thin films, showing different colors in reflected light (violet, yellow, brawn, green and exhibiting in VIS and NIR light appropriate reflectance and transmittance for utilization for solar control applications were established. The film thickness falls in the range 10- 50 nm.

  9. Estimation of sensible heat, water vapor, and CO2 fluxes using the flux-variance method.

    Science.gov (United States)

    Hsieh, Cheng-I; Lai, Mei-Chun; Hsia, Yue-Joe; Chang, Tsang-Jung

    2008-07-01

    This study investigated the flux-variance relationships of temperature, humidity, and CO(2), and examined the performance of using this method for predicting sensible heat (H), water vapor (LE), and CO(2) fluxes (F(CO2)) with eddy-covariance measured flux data at three different ecosystems: grassland, paddy rice field, and forest. The H and LE estimations were found to be in good agreement with the measurements over the three fields. The prediction accuracy of LE could be improved by around 15% if the predictions were obtained by the flux-variance method in conjunction with measured sensible heat fluxes. Moreover, the paddy rice field was found to be a special case where water vapor follows flux-variance relation better than heat does. However, the CO(2) flux predictions were found to vary from poor to fair among the three sites. This is attributed to the complicated CO(2) sources and sinks distribution. Our results also showed that heat and water vapor were transported with the same efficiency above the grassland and rice paddy. For the forest, heat was transported 20% more efficiently than evapotranspiration.

  10. [Comparing the ammonia volatilization characteristic of two typical paddy soil with total wheat straw returning in Taihu Lake region].

    Science.gov (United States)

    Wang, Jun; Wang, De-Jian; Zhang, Gang; Wang, Yuan

    2013-01-01

    An experiment using monolith lysimeter was conducted to compare the characteristic of N loss by ammonia (NH3) volatilization between the gleyed paddy soil (G soil) and hydromorphic paddy soil (H soil) the Changshu National Agro-ecological Experimental Station of the Chinese Academy of Sciences(31 degrees 33' N, 123 degrees 38' E). Three treatments were designed for each soil type, i. e. control (no urea and straw applied), nitrogen solely and nitrogen plus wheat straw. Ammonia volatilization, flood water NH4(+) -N concentration, pH and top soil Eh were measured during the rice-growing season. Results showed that the NH3 volatilization flux and cumulative N losses by NH3 volatilization from G soil were significantly higher than those from H soil, the average cumulative N losses being about 41.8 kg x hm(-2) and 11.2 kg x hm(-2), or 15.2% and 3.8% of the fertilizer N, respectively. The average N loss by NH3 volatilization during the tillering stage was the highest among the three fertilization stages, accounting for 29.4% and 8.3% of the fertilizer N for G soil and H soil, respectively. Wheat straw returning significantly increased paddy filed NH3 volatilization losses. Comparing with the sole application of fertilizer-N, the cumulative N loss by NH3 volatilization of fertilizer-N in combination with wheat straw was increased by 19.8% and 20.6% for G soil and H soil, respectively. In addition, ammonia volatilization fluxes showed a positive relationship with the flood water NH4(+) -N concentration and pH for both soils, but the relationship with top soil Eh still needs further study. PMID:23487914

  11. Warped branches of flux compactifications

    CERN Document Server

    Lim, Yen-Kheng

    2012-01-01

    We consider Freund-Rubin-type compactifications which are described by (p+q)-dimensional Einstein gravity with a positive cosmological constant and a q-form flux. Using perturbative expansions of Kinoshita's ansatz for warped dS_pxS^q and AdS_pxS^q spacetimes, we obtain analytical solutions describing the warped branches and their respective phase spaces. These equations are given by inhomogeneous Gegenbauer differential equations which can be solved by the Green's function method. The requirement that the Green's functions are regular provides constraints which determine the structure of the phase space of the warped branches. We apply the perturbation results to calculate the thermodynamic variables for the warped dS_pxS^q branch. In particular, the first law of thermodynamics can be reproduced using this method.

  12. Atmospheric lepton fluxes

    Directory of Open Access Journals (Sweden)

    Gaisser Thomas K.

    2015-01-01

    Full Text Available This review of atmospheric muons and neutrinos emphasizes the high energy range relevant for backgrounds to high-energy neutrinos of astrophysical origin. After a brief historical introduction, the main distinguishing features of atmospheric νμ and νe are discussed, along with the implications of the muon charge ratio for the νµ / ν̅µ ratio. Methods to account for effects of the knee in the primary cosmic-ray spectrum and the energy-dependence of hadronic interactions on the neutrino fluxes are discussed and illustrated in the context of recent results from IceCube. A simple numerical/analytic method is proposed for systematic investigation of uncertainties in neutrino fluxes arising from uncertainties in the primary cosmic-ray spectrum/composition and hadronic interactions.

  13. ISS Ammonia Leak Detection Through X-Ray Fluorescence

    Science.gov (United States)

    Camp, Jordan; Barthelmy, Scott; Skinner, Gerry

    2013-01-01

    Ammonia leaks are a significant concern for the International Space Station (ISS). The ISS has external transport lines that direct liquid ammonia to radiator panels where the ammonia is cooled and then brought back to thermal control units. These transport lines and radiator panels are subject to stress from micrometeorites and temperature variations, and have developed small leaks. The ISS can accommodate these leaks at their present rate, but if the rate increased by a factor of ten, it could potentially deplete the ammonia supply and impact the proper functioning of the ISS thermal control system, causing a serious safety risk. A proposed ISS astrophysics instrument, the Lobster X-Ray Monitor, can be used to detect and localize ISS ammonia leaks. Based on the optical design of the eye of its namesake crustacean, the Lobster detector gives simultaneously large field of view and good position resolution. The leak detection principle is that the nitrogen in the leaking ammonia will be ionized by X-rays from the Sun, and then emit its own characteristic Xray signal. The Lobster instrument, nominally facing zenith for its astrophysics observations, can be periodically pointed towards the ISS radiator panels and some sections of the transport lines to detect and localize the characteristic X-rays from the ammonia leaks. Another possibility is to use the ISS robot arm to grab the Lobster instrument and scan it across the transport lines and radiator panels. In this case the leak detection can be made more sensitive by including a focused 100-microampere electron beam to stimulate X-ray emission from the leaking nitrogen. Laboratory studies have shown that either approach can be used to locate ammonia leaks at the level of 0.1 kg/day, a threshold rate of concern for the ISS. The Lobster instrument uses two main components: (1) a microchannel plate optic (also known as a Lobster optic) that focuses the X-rays and directs them to the focal plane, and (2) a CCD (charge

  14. Mobility Spectrometer Studies on Hydrazine and Ammonia Detection

    Science.gov (United States)

    Niu, William; Eiceman, Gary; Szumlas, Andrew; Lewis, John

    2011-01-01

    An airborne vapor analyzer for detecting sub- to low- parts-per-million (ppm) hydrazine in the presence of higher concentration levels of ammonia has been under development for the Orion program. The detector is based on ambient pressure ionization and ion mobility characterization. The detector encompasses: 1) a membrane inlet to exclude particulate and aerosols from the analyzer inlet; 2) a method to separate hydrazine from ammonia which would otherwise lead to loss of calibration and quantitative accuracy for the hydrazine determination; and 3) response and quantitative determinations for both hydrazine and ammonia. Laboratory studies were made to explore some of these features including mobility measurements mindful of power, size, and weight issues. The study recommended the use of a mobility spectrometer of traditional design with a reagent gas and equipped with an inlet transfer line of bonded phase fused silica tube. The inlet transfer line provided gas phase separation of neutrals of ammonia from hydrazine at 50 C simplifying significantly the ionization chemistry that underlies response in a mobility spectrometer. Performance of the analyzer was acceptable between ranges of 30 to 80 C for both the pre-fractionation column and the drift tube. An inlet comprised of a combined membrane with valve-less injector allowed high speed quantitative determination of ammonia and hydrazine without cross reactivity from common metabolites such as alcohols, esters, and aldehydes. Preliminary test results and some of the design features are discussed.

  15. Fast responsive, optical trace level ammonia sensor for environmental monitoring

    Directory of Open Access Journals (Sweden)

    Abel Tobias

    2012-10-01

    Full Text Available Abstract Background Ammonia is a ubiquitous chemical substance which is created in technical and biological processes and harmful to many different organisms. One specific problem is the toxicity of ammonia in fish at levels of 25 μg/l - a very common issue in today’s aqua culture. In this study we report a development of a fast responsive, optical ammonia sensor for trace concentrations. Results Different hydrogels have been investigated as host polymers for a pH based sensing mechanism based on fluorescent dyes. A porous hydrophobic fluoropolymer membrane was used as an ion barrier cover layer to achieve a good ammonia permeability. The sensor’s sensitivity towards ammonia as well as crosssensitivity towards pH-value and salinity, and the temperature dependency have been determined. Two different methods to reference fluorescence signals have been employed to eliminate intensity-based measurement drawbacks. Conclusion The presented sensor features high sensitivity and a fast response even at concentrations near 1 ppb. No cross sensitivity towards pH and salinity could be observed and temperature dependency was determined as compensateable. Both referencing approaches prove themselves to be able to provide a simple use of the sensor for in-field applications.

  16. Amine substitution into sulfuric acid – ammonia clusters

    Directory of Open Access Journals (Sweden)

    O. Kupiainen

    2011-11-01

    Full Text Available The substitution of ammonia by dimethylamine in sulfuric acid – ammonia – dimethylamine clusters was studied using a collision and evaporation dynamics model. Quantum chemical formation free energies were computed using B3LYP/CBSB7 for geometries and frequencies and RI-CC2/aug-cc-pV(T+dZ for electronic energies. We first demonstrate the good performance of our method by a comparison with an experimental study investigating base substitution in positively charged clusters, and then continue by simulating base exchange in neutral clusters, which cannot be measured directly. Collisions of a dimethylamine molecule with an ammonia containing positively charged cluster result in the instantaneous evaporation of an ammonia molecule, while the dimethylamine molecule remains in the cluster. According to our simulations, a similar base exchange can take place in neutral clusters, although the overall process is more complicated. Neutral sulfuric acid – ammonia clusters are significantly less stable than their positively charged counterparts, resulting in a competition between cluster evaporation and base exchange.

  17. Ammonia modification of oxide-free Si(111) surfaces

    Science.gov (United States)

    Chopra, Tatiana Peixoto; Longo, Roberto C.; Cho, Kyeongjae; Chabal, Yves J.

    2016-08-01

    Amination of surfaces is useful in a variety of fields, ranging from device manufacturing to biological applications. Previous studies of ammonia reaction on silicon surfaces have concentrated on vapor phase rather than wet chemical processes, and mostly on clean Si surfaces. In this work, the interaction of liquid and vapor-phase ammonia is examined on three types of oxide-free surfaces - passivated by hydrogen, fluorine (1/3 monolayer) or chlorine - combining infrared absorption spectroscopy, X-ray photoelectron spectroscopy, and first-principles calculations. The resulting chemical composition highly depends on the starting surface; there is a stronger reaction on both F- and Cl-terminated than on the H-terminated Si surfaces, as evidenced by the formation of Si-NH2. Side reactions can also occur, such as solvent reaction with surfaces, formation of ammonium salt by-products (in the case of 0.2 M ammonia in dioxane solution), and nitridation of silicon (in the case of neat and gas-phase ammonia reactions for instance). Unexpectedly, there is formation of Si-H bonds on hydrogen-free Cl-terminated Si(111) surfaces in all cases, whether vapor phase of neat liquid ammonia is used. The first-principles modeling of this complex system suggests that step-edge surface defects may play a key role in enabling the reaction under certain circumstances, despite the endothermic nature for Si-H bond formation.

  18. Ammonia disinfection of corn grains intended for ethanol fermentation

    Directory of Open Access Journals (Sweden)

    Magdalena Broda

    2009-12-01

    Full Text Available Background. Bacterial contamination is an ongoing problem for commercial bioethanol plants. It concerns factories using grain and also other raw materials for ethanol fermentation. Bacteria compete with precious yeasts for sugar substrates and micronutrients, secrete lactic and acetic acids, which are toxic for yeast and this competition leads to significant decrease of bioethanol productivity. For this study, bacterial contamination of corn grain was examined. Then the grain was treated by ammonia solution to reduce microbial pollution and after that the microbiological purity of grain was tested one more time. Disinfected and non-disinfected corn grains were ground and fermentation process was performed. Microbiological purity of this process and ethanol yield was checked out. Material and methods. The grain was disinfected by ammonia solution for two weeks. Then the grain was milled and used as a raw material for the ethanol fermentation. The fermentation process was carried out in 500-ml Erlenmeyer flasks. Samples were withdrawn for analysis at 0, 24, 48, 72 hrs. The number of total viable bacteria, lactic acid bacteria, acetic acid bacteria, anaerobic bacteria and the quantity of yeasts and moulds were signified by plate method. Results. Ammonia solution effectively reduces bacterial contamination of corn grain. Mash from grain disinfected by ammonia contains less undesirable microorganisms than mash from crude grain. Moreover, ethanol yield from disinfected grain is at the highest level. Conclusions. The ammonia solution proved to be a good disinfection agent for grain used as a raw material for bioethanol fermentation process.

  19. Simple and inexpensive quantification of ammonia in whole blood.

    Science.gov (United States)

    Ayyub, Omar B; Behrens, Adam M; Heligman, Brian T; Natoli, Mary E; Ayoub, Joseph J; Cunningham, Gary; Summar, Marshall; Kofinas, Peter

    2015-01-01

    Quantification of ammonia in whole blood has applications in the diagnosis and management of many hepatic diseases, including cirrhosis and rare urea cycle disorders, amounting to more than 5 million patients in the United States. Current techniques for ammonia measurement suffer from limited range, poor resolution, false positives or large, complex sensor set-ups. Here we demonstrate a technique utilizing inexpensive reagents and simple methods for quantifying ammonia in 100 μL of whole blood. The sensor comprises a modified form of the indophenol reaction, which resists sources of destructive interference in blood, in conjunction with a cation-exchange membrane. The presented sensing scheme is selective against other amine containing molecules such as amino acids and has a shelf life of at least 50 days. Additionally, the resulting system has high sensitivity and allows for the accurate reliable quantification of ammonia in whole human blood samples at a minimum range of 25 to 500 μM, which is clinically for rare hyperammonemic disorders and liver disease. Furthermore, concentrations of 50 and 100 μM ammonia could be reliably discerned with p = 0.0001. PMID:25936660

  20. Influence of Different Cultivars on Populations of Ammonia-Oxidizing Bacteria in the Root Environment of Rice

    OpenAIRE

    Briones, Aurelio M.; Okabe, Satoshi; Umemiya, Yoshiaki; Ramsing, Niels-Birger; Reichardt, Wolfgang; Okuyama, Hidetoshi

    2002-01-01

    Comparisons of the activities and diversities of ammonia-oxidizing bacteria (AOB) in the root environment of different cultivars of rice (Oryza sativa L.) indicated marked differences despite identical environmental conditions during growth. Gross nitrification rates obtained by the 15N dilution technique were significantly higher in a modern variety, IR63087-1-17, than in two traditional varieties. Phylogenetic analysis based on the ammonium monooxygenase gene (amoA) identified strains relat...

  1. Protein extraction and enzymatic hydrolysis of ammonia-treated cassava leaves (Manihot esculenta Crantz).

    Science.gov (United States)

    Urribarrí, Lauris; Chacón, David; González, Orlaidy; Ferrer, Alexis

    2009-05-01

    In the present work, cassava leaves were treated with 0.5 kg ammonia/kg dry matter at 78 degrees C and 30% moisture content in a 2-kg reactor. Protein extraction was carried out with a calcium hydroxide solution (pH 10) for 30 min at several temperatures (30 degrees C, 45 degrees C, 60 degrees C, 75 degrees C, and 90 degrees C) and solid/liquid ratios (1:10 and 1:15) in a thermostatized bath. Soluble protein content of the extracts was determined by Lowry's method. Dry substrate concentrations of 5%, 7.5%, and 10% and enzyme doses of 2 and 5 IU/g dry matter were used for the enzymatic hydrolysis in an orbital incubator at 50 degrees C and 100 rpm. Both cellulase and xylanase were used. Reducing sugars produced were determined with the dinitrosalicylic acid method. The highest protein extraction yield for the ammonia-treated leaves was 29.10%, which was 50% higher than with the untreated leaves (20%), and was obtained at 90 degrees C with a 1:10 solid/liquid ratio. The concentrate had a protein content of 36.35% and the amino acid profile was suitable for swine and poultry. The highest sugar yield was 54.72% with respect to theoretical and was obtained with 5% solids and an enzyme dose of 5 IU/g dry matter. This yield was 3.4 times higher than the yield of the untreated leaves (16.13%). These results indicate that cassava leaves have a great potential for animal feeding and ethanol production. Both protein extraction and sugar yields may be enhanced by optimizing the ammonia treatment.

  2. Methods of obtaining thermodynamic data

    International Nuclear Information System (INIS)

    The types of thermodynamic data needed to predict behavior of high temperature systems such as an overheated nuclear reactor in which the fuel has been exposed to water and oxygen are discussed. Procedures for obtaining the needed data are reviewed. 14 refs

  3. SURFATM-NH3: a model combining the surface energy balance and bi-directional exchanges of ammonia applied at the field scale

    Directory of Open Access Journals (Sweden)

    E. Personne

    2009-08-01

    Full Text Available A new biophysical model SURFATM-NH3, simulating the ammonia (NH3 exchange between terrestrial ecosystems and the atmosphere is presented. SURFATM-NH3 consists of two coupled models: (i an energy budget model and (ii a pollutant exchange model, which distinguish the soil and plant exchange processes. The model describes the exchanges in terms of adsorption to leaf cuticles and bi-directional transport through leaf stomata and soil. The results of the model are compared with the flux measurements over grassland during the GRAMINAE Integrated Experiment at Braunschweig, Germany. The dataset of GRAMINAE allows the model to be tested in various meteorological and agronomic conditions: prior to cutting, after cutting and then after the application of mineral fertilizer. The whole comparison shows close agreement between model and measurements for energy budget and ammonia fluxes. The major controls on the ground and plant emission potential are the physicochemical parameters for liquid-gas exchanges which are integrated in the compensation points for live leaves, litter and the soil surface. Modelled fluxes are highly sensitive to soil and plant surface temperatures, highlighting the importance of accurate estimates of these terms. The model suggests that the net flux depends not only on the foliar (stomatal compensation point but also that of leaf litter. SURFATM-NH3 represents a comprehensive approach to studying pollutant exchanges and its link with plant and soil functioning. It also provides a simplified generalised approach (SVAT model applicable for atmospheric transport models.

  4. Ammonia Bearing Species on Ceres: Implication on Origin and Evolution

    Science.gov (United States)

    De Sanctis, M. C.; Ammannito, E.; Raponi, A.; Marchi, S.; Ciarniello, M.; McSween, H. Y., Jr.; McCord, T. B.; Capaccioni, F.; Capria, M. T.; Carrorro, F. G.; Longobardo, A.; Tosi, F.; Fonte, S.; Giardino, M.; Palomba, E.; Magni, G.; Zambon, F.; Pieters, C. M.; McFadden, L. A.; Raymond, C. A.

    2015-12-01

    The Visible and Infrared Mapping Spectrometer (VIR) on board the Dawn spacecraft observed Ceres' surface acquiring spectra since January 2015. Here we report the average Ceres spectrum, including the spectral range previously precluded from telescopic measurements due to telluric atmospheric absorptions. The data indicate that the surface is very dark: average albedo of 0.090 ±0.006 at 0.55 µm, consistent with HST data (Li et al., 2006). Ceres' average spectrum is characterized by a prominent absorption band at 2.7 micron. Weaker absorption bands are observed between 3.05-3.1, 3.3-3.4 and 3.9-4 micron; the visible and near-IR ranges lack prominent bands. We modelled the spectra of Ceres using Hapke theory. Results of the spectral modelling indicate that extensive water ice is not present in surface spectra acquired so far. The best fit is obtained with a mixture of ammoniated phyllosilicates mixed with other clays, Mg-carbonates, and dark material, like magnetite (De Sanctis et al. 2015, submitted). The presence of ammonia bearing materials across the surface has implications for the origin of Ceres and its internal structure and evolution. Higher spatial resolution spectra are being acquired to address the small scale mineralogy across this dwarf planet. References: Li, et al., Photometric analysis of 1 Ceres and surface mapping from HST observations. Icarus 182, 143-160 (2006). De Sanctis et al., Ammoniated phyllosilicates on dwarf planet Ceres reveal an outer solar system origin, Nature submitted, (2015). This work is supported the Italian Space Agencies, NASA, and from the German Space Agency. Support of the Dawn Instrument, Operations, and Science Teams is acknowledged.

  5. Benthic flux of nutrients and trace metals in the northern component of San Francisco Bay, California

    Science.gov (United States)

    Kuwabara, James S.; Topping, Brent R.; Parcheso, Francis; Engelstad, Anita C.; Greene, Valerie E.

    2009-01-01

    ), except for one site with statistically insignificant nitrate fluxes (Site 409 within Suisun Bay). The most negative nitrate flux (-7.3?0.1 mmole m-2d-1) was observed within Grizzly Bay (Site 416). Observed nitrate fluxes bracketed the estimated summer fluvial flux of nitrate (3,500 to 5,000 kg-N d-1). With the exception of the two Grizzly Bay sites (416 and 417), the consistently positive benthic flux of ammonia generally counteracted the negative flux of nitrate to yield a net balance of dissolved inorganic nitrogen. Ammonia benthic fluxes extrapolated for Suisun Bay ranged from 320 kg-N d-1 (Site SSB009 near the entrance to Honker Bay) to 1,900 kg-N d-1 (Montezuma Island). These values represent a significant ammonia source to the water column relative to summer riverine inputs (approximately 400 to 600 kg-N d-1). Dissolved silica also displayed a consistently positive benthic flux, except for Site 409 within Suisun Bay, which showed insignificant fluxes (also insignificant for nitrate and SRP). As with the nitrate fluxes, Grizzly Bay and Browns Island sites yielded the highest dissolved silica fluxes (1.3?1.2 to 2.5?0.6 mmole m-2d-1, respectively). These initial diffusive-flux estimates are greater than those measured in the South Bay using core-incubation experiments, which include bioturbation and bioirrigation effects, but they are nevertheless probably one to t

  6. Development and Comparison of Numerical Fluxes for LWDG Methods

    Institute of Scientific and Technical Information of China (English)

    Jianxian Qiu

    2008-01-01

    The discontinuous Galerkin (DG) or local discontinuous Galerkin (LDG) method is a spatial discretization procedure for convection-diffusion equations, which employs useful features from high resolution finite volume schemes, such as the exact or approximate Riemann solvers serving as numerical fluxes and limiters. The Lax-Wendroff time discretization procedure is an alternative method for time discretization to the popular total variation diminishing (TVD) Runge-Kutta time discretizations. In this paper, we develop fluxes for the method of DG with Lax-Wendroff time discretization procedure (LWDG) based on different numerical fluxes for finite volume or finite difference schemes, including the first-order monotone fluxes such as the Lax-Friedrichs flux, Godunov flux, the Engquist-Osher flux etc. And the second-order TVD fluxes. We systematically investigate the performance of the LWDG methods based on these differ-ent numerical fluxes for convection terms with the objective of obtaining better perfor-mance by choosing suitable numerical fluxes. The detailed numerical study is mainly performed for the one-dimensional system case, addressing the issues of CPU cost, ac-curacy, non-oscillatory property, and resolution of discontinuities. Numerical tests are also performed for two dimensional systems.

  7. Design Ammonia Gas Detection System by Using Optical Fiber Sensor

    Directory of Open Access Journals (Sweden)

    Dr. Bushra. R. Mhdi

    2013-07-01

    Full Text Available Design study and construction of Ammonia gas detection using a fiber as a sensor to based on evanescent wave sensing technique was investigated. Multi-mode fiber type (PCS with core diameter (600μm and (50cm length used where plastic clad was removed by chemical etching for effective sensing area which coated with sol-gel film to enhance its absorption characteristics to evanescent wave around the optical spectrum emitted from halogen lamp measurements through different temperature rang (25-60oc with and without air using as a carrier to ammonia molecules are investigated. Finally sensing efficiency are monitored to ammonia gas it affected to different temperature and environmental condition are studied and our result are compatible to scientific publishes

  8. Interactions in the ammonia-deuterium system under pressure

    International Nuclear Information System (INIS)

    We have investigated the NH3-D2 mixture to 50 GPa using micro-Raman spectroscopy. Proton exchange was observed in the mixture, resulting in the formation of deuterated isotopes of ammonia and the formation of HD and H2. We report the changes in the vibrational spectra of the various components of the mixture, which include blueshifts and splitting in the vibration modes of hydrogen. These frequency shifts in the mixture are compared to frequency shifts in mixtures composed of the hydrogen isotopes. The changes not accounted for by interactions between the hydrogen molecules suggest repulsive interactions between the hydrogen and ammonia. The bond length of the hydrogen molecules is calculated using a Morse potential, revealing a bond length shorter than in pure hydrogen. Additionally, a change in slope of the bond length as a function of pressure was observed around ∼10-18 GPa, which is attributed to the reordering Phase IV to V transition in ammonia.

  9. Determination of ammonia in ethylene using ion mobility spectrometry

    Science.gov (United States)

    Cross, J. H.; Limero, T. F.; Lane, J. L.; Wang, F.

    1997-01-01

    A simple procedure to analyze ammonia in ethylene by ion mobility spectrometry is described. The spectrometer is operated with a silane polymer membrane., 63Ni ion source, H+ (H2O)n reactant ion, and nitrogen drift and source gas. Ethylene containing parts per billion (ppb) (v/v) concentrations of ammonia is pulled across the membrane and diffuses into the spectrometer. Preconcentration or preseparation is unnecessary, because the ethylene in the spectrometer has no noticeable effect on the analytical results. Ethylene does not polymerize in the radioactive source. Ethylene's flammability is negated by the nitrogen inside the spectrometer. Response to ammonia concentrations between 200 ppb and 1.5 ppm is near linear, and a detection limit of 25 ppb is calculated.

  10. Novel Ru - K/Carbon Nanotubes Catalyst for Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel ammonia synthesis catalyst, potassium-promoted ruthenium supported on carbon nanotubes, was developed. It was found that the Ru-K/carbon nanotubes catalyst had higher activity for ammonia synthesis ( 20.85 ml NH 3 /h/g-cat ) than the Ru-K/fullerenes ( 13.3 ml NH 3 /h/g-cat ) at atmospheric ressure and 623 K. The catalyst had activity even at 473 K, and had the highest activity ( 23.46 ml NH 3 /h/g-cat ) at 643 K. It was suggested that the multi-walled structure favored the electron transfer, the hydrogen-storage and the hydrogen-spill which were favorable to ammonia synthesis.

  11. Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations.

    Science.gov (United States)

    Oishi, Ryu; Tada, Chika; Asano, Ryoki; Yamamoto, Nozomi; Suyama, Yoshihisa; Nakai, Yutaka

    2012-05-01

    A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10 mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10 mM NH (4) (+) -N, whereas AOA grew at 46°C and 10 mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.

  12. Ammonia-oxidizing archaea have better adaptability in oxygenated/hypoxic alternant conditions compared to ammonia-oxidizing bacteria.

    Science.gov (United States)

    Liu, Shuai; Hu, Baolan; He, Zhanfei; Zhang, Bin; Tian, Guangming; Zheng, Ping; Fang, Fang

    2015-10-01

    Ammonia oxidation is performed by both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Few studies compared the adaptability of AOA and AOB for oxygenated/hypoxic alternant conditions in water-level-fluctuating zones. Here, using qPCR and 454 high-throughput sequencing of functional amoA genes of AOA and AOB, we examined the changes of abundances, diversities, and community structures of AOA and AOB in periodically flooded soils compared to the non-flooded soils in Three Gorges Reservoir. The increased AOA operational taxonomic unit (OTU) numbers and the higher ratios of abundance (AOA:AOB) in the periodically flooded soils suggested AOA have better adaptability for oxygenated/hypoxic alternant conditions in the water-level-fluctuating zones in the Three Gorges Reservoir and probably responsible for the ammonia oxidation there. Canonical correspondence analysis (CCA) showed that oxidation-reduction potential (ORP) had the most significant effect on the community distribution of AOA (p ammonia-oxidizing microbes. ORP was significantly negatively correlated with AOA OTU numbers (p < 0.05), ratio of OTU numbers (AOA:AOB) (p < 0.01), and ratio of amoA gene abundances (AOA:AOB) (p < 0.05). ORP was also significantly positively correlated with AOB abundance (p < 0.05).

  13. Isolation of ‘Candidatus Nitrosocosmicus franklandus’, a novel ureolytic soil archaeal ammonia oxidiser with tolerance to high ammonia concentration

    Science.gov (United States)

    Lehtovirta-Morley, Laura E.; Ross, Jenna; Hink, Linda; Weber, Eva B.; Gubry-Rangin, Cécile; Thion, Cécile; Prosser, James I.; Nicol, Graeme W.

    2016-01-01

    Studies of the distribution of ammonia oxidising archaea (AOA) and bacteria (AOB) suggest distinct ecological niches characterised by ammonia concentration and pH, arising through differences in substrate affinity and ammonia tolerance. AOA form five distinct phylogenetic clades, one of which, the ‘Nitrososphaera sister cluster’, has no cultivated isolate. A representative of this cluster, named ‘Candidatus Nitrosocosmicus franklandus’, was isolated from a pH 7.5 arable soil and we propose a new cluster name: ‘Nitrosocosmicus’. While phylogenetic analysis of amoA genes indicates its association with the Nitrososphaera sister cluster, analysis of 16S rRNA genes provided no support for a relative branching that is consistent with a ‘sister cluster’, indicating placement within a lineage of the order Nitrososphaerales. ‘Ca. N. franklandus’ is capable of ureolytic growth and its tolerances to nitrite and ammonia are higher than in other AOA and similar to those of typical soil AOB. Similarity of other growth characteristics of ‘Ca. N. franklandus’ with those of typical soil AOB isolates reduces support for niche differentiation between soil AOA and AOB and suggests that AOA have a wider physiological diversity than previously suspected. In particular, the high ammonia tolerance of ‘Ca. N. franklandus’ suggests potential contributions to nitrification in fertilised soils. PMID:26976843

  14. Isolation of 'Candidatus Nitrosocosmicus franklandus', a novel ureolytic soil archaeal ammonia oxidiser with tolerance to high ammonia concentration.

    Science.gov (United States)

    Lehtovirta-Morley, Laura E; Ross, Jenna; Hink, Linda; Weber, Eva B; Gubry-Rangin, Cécile; Thion, Cécile; Prosser, James I; Nicol, Graeme W

    2016-05-01

    Studies of the distribution of ammonia oxidising archaea (AOA) and bacteria (AOB) suggest distinct ecological niches characterised by ammonia concentration and pH, arising through differences in substrate affinity and ammonia tolerance. AOA form five distinct phylogenetic clades, one of which, the 'Nitrososphaera sister cluster', has no cultivated isolate. A representative of this cluster, named 'Candidatus Nitrosocosmicus franklandus', was isolated from a pH 7.5 arable soil and we propose a new cluster name:'Nitrosocosmicus' While phylogenetic analysis of amoA genes indicates its association with the Nitrososphaera sister cluster, analysis of 16S rRNA genes provided no support for a relative branching that is consistent with a 'sister cluster', indicating placement within a lineage of the order Nitrososphaerales 'Ca.N. franklandus' is capable of ureolytic growth and its tolerances to nitrite and ammonia are higher than in other AOA and similar to those of typical soil AOB. Similarity of other growth characteristics of 'Ca.N. franklandus' with those of typical soil AOB isolates reduces support for niche differentiation between soil AOA and AOB and suggests that AOA have a wider physiological diversity than previously suspected. In particular, the high ammonia tolerance of 'Ca.N. franklandus' suggests potential contributions to nitrification in fertilised soils. PMID:26976843

  15. Effects of gaseous ammonia direct injection on performance characteristics of a spark-ignition engine

    International Nuclear Information System (INIS)

    Highlights: • This is the very first study in utilizing direct injection of gaseous ammonia in an SI engine. • Engine combustion using direct injection of gaseous ammonia is proven feasible. • Energy efficiency using ammonia is comparable to that using gasoline. • CO emissions are decreased but emissions of NOx and HC are increased when ammonia is used. - Abstract: The effects of direct injection of gaseous ammonia on the combustion characteristics and exhaust emissions of a spark-ignition engine were investigated. Port-injection gasoline was used to enhance the burning of ammonia that was directly injected into the engine cylinder. Appropriate direct injection strategies were developed to allow ammonia to be used in spark-ignition engines without sacrifice of volumetric efficiency. Experimental results show that with gasoline providing the baseline power of 0.6 kW, total engine power could increase to 2.7 kW when the injection timing of ammonia was advanced to 370 BTDC with injection duration of 22 ms. Engine performance with use of gasoline–ammonia was compared to that with gasoline alone. For operations using gasoline–ammonia, with baseline power from gasoline at 0.6 kW the appropriate ammonia injection timing was found to range from 320 to 370 BTDC for producing 1.5–2.7 kW. The peak pressures were slightly lower than those using gasoline alone because of the lower flame of ammonia, resulting in reduction of cylinder pressure. The brake specific energy consumption (BSEC) with gasoline–ammonia was very similar to that with gasoline alone. Ammonia direct injection caused slight reductions of BSCO for all the loads studied but significantly increased BSHC because of the reduced combustion temperature of ammonia combustion. The use of ammonia resulted in increased NOx emissions because of formation of fuel NOx. Ammonia slip was also detected in the engine exhaust because of incomplete combustion

  16. Truncated States Obtained by Iteration

    Institute of Scientific and Technical Information of China (English)

    W.B.Cardoso; N.G.de Almeida

    2008-01-01

    We introduce the concept of truncated states obtained via iterative processes(TSI)and study its statistical features,making an analogy with dynamical systems theory(DST).As a specific example,we have studied TSI for the doubring and the logistic functions,which are standard functions in studying chaos.TSI for both the doubling and logistic functions exhibit certain similar patterns when their statistical features are compared from the point of view of DST.

  17. Effect of chamber enclosure time on soil respiration flux: A comparison of linear and non-linear flux calculation methods

    DEFF Research Database (Denmark)

    Kandel, Tanka P; Lærke, Poul Erik; Elsgaard, Lars

    2016-01-01

    One of the shortcomings of closed chamber methods for soil respiration (SR) measurements is the decreased CO2 diffusion rate from soil to chamber headspace that may occur due to increased chamber CO2 concentrations. This feedback on diffusion rate may lead to underestimation of pre...... the effect of increasing chamber enclosure time on SR flux rates calculated using a linear, an exponential and a revised Hutchinson and Mosier model (HMR). Soil respiration rates were measured with a closed chamber in combination with an infrared gas analyzer. During SR flux measurements the chamber......) to obtain a range of fluxes with different shapes of flux curves. The linear method provided more stable flux results during short enclosure times (few min) but underestimated initial fluxes by 15–300% after 45 min deployment time. Non-linear models reduced the underestimation as average underestimation...

  18. Synthesis of hydrides by interaction of intermetallic compounds with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, Boris P., E-mail: tarasov@icp.ac.ru [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Fokin, Valentin N.; Fokina, Evelina E. [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Yartys, Volodymyr A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, Kjeller NO 2027 (Norway); Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim NO 7491 (Norway)

    2015-10-05

    Highlights: • Interaction of the intermetallics A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} with NH{sub 3} was studied. • The mechanism of interaction of the alloys with ammonia is temperature-dependent. • Hydrides, hydridonitrides, disproportionation products or metal–N–H compounds are formed. • NH{sub 4}Cl was used as an activator of the reaction between ammonia and intermetallics. • Interaction with ammonia results in the synthesis of the nanopowders. - Abstract: Interaction of intermetallic compounds with ammonia was studied as a processing route to synthesize hydrides and hydridonitrides of intermetallic compounds having various stoichiometries and types of crystal structures, including A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} (A = Mg, Ti, Zr, Sc, Nd, Sm; B = transition metals, including Fe, Co, Ni, Ti and nontransition elements, Al and B). In presence of NH{sub 4}Cl used as an activator of the reaction between ammonia and intermetallic alloys, their interaction proceeds at rather mild P–T conditions, at temperatures 100–200 °C and at pressures of 0.6–0.8 MPa. The mechanism of interaction of the alloys with ammonia appears to be temperature-dependent and, following a rise of the interaction temperature, it leads to the formation of interstitial hydrides; interstitial hydridonitrides; disproportionation products (binary hydride; new intermetallic hydrides and binary nitrides) or new metal–nitrogen–hydrogen compounds like magnesium amide Mg(NH{sub 2}){sub 2}. The interaction results in the synthesis of the nanopowders where hydrogen and nitrogen atoms become incorporated into the crystal lattices of the intermetallic alloys. The nitrogenated materials have the smallest particle size, down to 40 nm, and a specific surface area close to 20 m{sup 2}/g.

  19. First detection of ammonia (NH3) in the upper troposphere

    Science.gov (United States)

    Höpfner, Michael; Volkamer, Rainer; Grabowski, Udo; Grutter de la Mora, Michel; Orphal, Johannes; Stiller, Gabriele; von Clarmann, Thomas

    2016-04-01

    Ammonia (NH3) is the major alkaline trace gas in the troposphere. Neutralization of atmospheric acids, like HNO3 and H2SO4, leads to formation of ammonium nitrate and ammonium sulfate aerosols. Further, there are indications that NH3 may enhance nucleation of sulfuric acid aerosols by stabilization of sulfuric acid clusters. By far the largest source of ammonia is agricultural food production. Major global emissions are located in S-E Asia as e.g. shown by satellite nadir observations. Besides its importance with respect to air quality issues, an increase of ammonia emissions in the 21st century might lead to a significant climate radiative impact through aerosol formation. In spite of its significance, there is a lack of observational information on the global distribution of NH3 in the mid- and upper troposphere. Observational evidence, however, would be important for testing e.g. model results on the fate of ammonia from its source regions on ground to altitudes up to the tropopause. In this contribution we will show, to our knowledge, the first unequivocal detection of ammonia in the upper troposphere. This result has been achieved through analysis of infrared limb-emission observations performed with the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument on board the Envisat satellite from 2002-2012. On a global scale, enhanced values of ammonia have been measured in the upper tropospheric region influenced by the Asian monsoon. We will present a quantitative analysis of the retrieved concentrations of NH3 including an error assessment and further retrieval diagnostics. The results will be discussed with respect to the variability of NH3 locally within the Asian monsoon region's upper troposphere and at different years. Further, we will show comparisons between global distributions of NH3 from published model simulations and our observational dataset from MIPAS.

  20. Ammonia-oxidising archaea--physiology, ecology and evolution.

    Science.gov (United States)

    Schleper, Christa; Nicol, Graeme W

    2010-01-01

    Nitrification is a microbially mediated process that plays a central role in the global cycling of nitrogen and is also of economic importance in agriculture and wastewater treatment. The first step in nitrification is performed by ammonia-oxidising microorganisms, which convert ammonia into nitrite ions. Ammonia-oxidising bacteria (AOB) have been known for more than 100 years. However, metagenomic studies and subsequent cultivation efforts have recently demonstrated that microorganisms of the domain archaea are also capable of performing this process. Astonishingly, members of this group of ammonia-oxidising archaea (AOA), which was overlooked for so long, are present in almost every environment on Earth and typically outnumber the known bacterial ammonia oxidisers by orders of magnitudes in common environments such as the marine plankton, soils, sediments and estuaries. Molecular studies indicate that AOA are amongst the most abundant organisms on this planet, adapted to the most common environments, but are also present in those considered extreme, such as hot springs. The ecological distribution and community dynamics of these archaea are currently the subject of intensive study by many research groups who are attempting to understand the physiological diversity and the ecosystem function of these organisms. The cultivation of a single marine isolate and two enrichments from hot terrestrial environments has demonstrated a chemolithoautotrophic mode of growth. Both pure culture-based and environmental studies indicate that at least some AOA have a high substrate affinity for ammonia and are able to grow under extremely oligotrophic conditions. Information from the first available genomes of AOA indicate that their metabolism is fundamentally different from that of their bacterial counterparts, involving a highly copper-dependent system for ammonia oxidation and electron transport, as well as a novel carbon fixation pathway that has recently been discovered in