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Sample records for air nitrogen argon

  1. Decay of femtosecond laser-induced plasma filaments in air, nitrogen, and argon for atmospheric and subatmospheric pressures

    NASA Astrophysics Data System (ADS)

    Aleksandrov, N. L.; Bodrov, S. B.; Tsarev, M. V.; Murzanev, A. A.; Sergeev, Yu. A.; Malkov, Yu. A.; Stepanov, A. N.

    2016-07-01

    The temporal evolution of a plasma channel at the trail of a self-guided femtosecond laser pulse was studied experimentally and theoretically in air, nitrogen (with an admixture of ˜3% O2), and argon in a wide range of gas pressures (from 2 to 760 Torr). Measurements by means of transverse optical interferometry and pulsed terahertz scattering techniques showed that plasma density in air and nitrogen at atmospheric pressure reduces by an order of magnitude within 3-4 ns and that the decay rate decreases with decreasing pressure. The argon plasma did not decay within several nanoseconds for pressures of 50-760 Torr. We extended our theoretical model previously applied for atmospheric pressure air plasma to explain the plasma decay in the gases under study and to show that allowance for plasma channel expansion affects plasma decay at low pressures.

  2. Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region

    NASA Technical Reports Server (NTRS)

    Grossmann, Benoist E.; Browell, Edward V.

    1989-01-01

    High-resolution spectroscopic measurements of H2O vapor in the 720-nm wavelength region were conducted to investigate the broadening and shifting of H2O lines by air, nitrogen, oxygen, and argon over a wide range of pressures and temperatures. For each of the buffer gases under study, a linear relationship was found between the widths and the shifts, with the broader lines having the smaller pressure shifts. The pressure shifts measured compared favorably with theoretical values reported by Bykov et al. (1988). The temperature-dependence exponents for air-broadening were found to be J-dependent, with the lower-J lines having the higher exponents.

  3. Large-volume excitation of air, argon, nitrogen and combustible mixtures by thermal jets produced by nanosecond spark discharges

    NASA Astrophysics Data System (ADS)

    Stepanyan, Sergey; Hayashi, Jun; Salmon, Arthur; Stancu, Gabi D.; Laux, Christophe O.

    2017-04-01

    This work presents experimental observations of strong expanding thermal jets following the application of nanosecond spark discharges. These jets propagate in a toroidal shape perpendicular to the interelectrode axis, with high velocities of up to 30 m s‑1 and over distances of the order of a cm. Their propagation length is much larger than the thermal expansion region produced by the conventional millisecond sparks used in car engine ignition, thus greatly improving the volumetric excitation of gas mixtures. The shape and velocity of the jets is found to be fairly insensitive to the shape of the electrodes. In addition, their spatial extent is found to increase with the number of nanosecond sparks and with the discharge voltage, and to decrease slightly with the pressure between 1 and 7 atm at constant applied voltage. Finally, this thermal jet phenomenon is observed in experiments conducted with many types of gas mixtures, including air, nitrogen, argon, and combustible CH4/air mixtures. This makes nanosecond repetitively pulsed discharges particularly attractive for aerodynamic flow control or plasma-assisted combustion because of their ability to excite large volumes of gas, typically about 100 times the volume of the discharge.

  4. 46 CFR 151.50-36 - Argon or nitrogen.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable working pressure of 172 kPa...

  5. 46 CFR 151.50-36 - Argon or nitrogen.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable working pressure of 172 kPa...

  6. 46 CFR 151.50-36 - Argon or nitrogen.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable working pressure of 172 kPa...

  7. 46 CFR 151.50-36 - Argon or nitrogen.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable working pressure of 172 kPa...

  8. 46 CFR 151.50-36 - Argon or nitrogen.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable working pressure of 172 kPa...

  9. Study of argon flowing afterglow with nitrogen injection

    SciTech Connect

    Mazánková, V.; Krčma, F.; Trunec, D.

    2013-10-28

    In this work, the reaction kinetics in argon flowing afterglow with nitrogen addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure argon was created in quartz tube at the total gas pressure of 1000 Pa and discharge power of 60 W. The nitrogen was added into the afterglow at the distance of 9 cm behind the active discharge. The optical emission spectra were measured along the flow tube. The argon spectral lines and after nitrogen addition also nitrogen second positive system (SPS) were identified in the spectra. The measurement of spatial dependence of SPS intensity showed a very slow decay of the intensity and the decay rate did not depend on the nitrogen concentration. In order to explain this behavior a kinetic model for reaction in afterglow was developed. This model showed that C {sup 3}Π{sub u} state of molecular nitrogen, which is the upper state of SPS emission, is produced by excitation transfer from argon metastables to nitrogen molecules. However, the argon metastables are also produced at Ar{sub 2}{sup +} ion recombination with electrons and this limits the decay of argon metastable concentration and it results in very slow decay of SPS intensity.

  10. Experimental thermal conductivity, thermal diffusivity, and specific heat values for mixtures of nitrogen, oxygen, and argon

    NASA Technical Reports Server (NTRS)

    Perkins, R. A.; Cieszkiewicz, M. T.

    1991-01-01

    Experimental measurements of thermal conductivity and thermal diffusivity obtained with a transient hot-wire apparatus are reported for three mixtures of nitrogen, oxygen, and argon. Values of the specific heat, Cp, are calculated from these measured values and the density calculated with an equation of state. The measurements were made at temperatures between 65 and 303 K with pressures between 0.1 and 70 MPa. The data cover the vapor, liquid, and supercritical gas phases for the three mixtures. The total reported points are 1066 for the air mixture (78.11 percent nitrogen, 20.97 percent oxygen, and 0.92 percent argon), 1058 for the 50 percent nitrogen, 50 percent oxygen mixture, and 864 for the 25 percent nitrogen, 75 oxygen mixture. Empirical thermal conductivity correlations are provided for the three mixtures.

  11. Infrared spectrum of the complex of formaldehyde with carbon dioxide in argon and nitrogen matrices

    NASA Technical Reports Server (NTRS)

    Van Der Zwet, G. P.; Allamandola, Louis J.; Baas, F.; Greenberg, J. M.

    1989-01-01

    The complex of formaldehyde with carbon dioxide has been studied by infrared spectroscopy in argon and nitrogen matrices. The shifts relative to the free species show that the complex is weak and similar in argon and nitrogen. The results give evidence for T-shaped complexes, which are isolated in several configurations. Some evidence is also presented which indicates that, in addition to the two well-known sites in argon, carbon dioxide can be trapped in a third site.

  12. Analysis of Laser Pumping by Capillary Pinching Discharge in Argon and Nitrogen

    NASA Astrophysics Data System (ADS)

    Vrba, P.; Vrbová, M.; Jančárek, A.; Pína, L.; Tamáš, M.; Havlíková, R.; Palínek, S.; Tomassetti, G.; Ritucci, A.

    A comparative study of the capillary pinching discharges in argon and nitrogen is presented. Requirements on plasma parameters needed for laser collision and recombination pumping are stated. The results of the computer modelling are compared with previously published experimental results for argon laser and with recent experiments done with the same capillary filled by nitrogen.

  13. Pulsed electron beam propagation in argon and nitrogen gas mixture

    SciTech Connect

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Zhirkov, I. S.

    2015-10-15

    The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N{sub 2}). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively.

  14. Characterization of sputtered zirconium nitride films deposited at various argon:nitrogen ratio

    NASA Astrophysics Data System (ADS)

    Patel, Nicky P.; Chauhan, Kamlesh V.; Kapopara, Jaydeep M.; Jariwala, Nayan N.; Rawal, Sushant K.

    2016-09-01

    Zirconium nitride films were deposited by reactive magnetron sputtering using argon as inert gas and nitrogen as reactive gas. The nitrogen flow rate in argon:nitrogen ratio was increased from 4sccm to 20sccm by an increment of 4sccm. The effect of increment in nitrogen flow rate on various properties of deposited zirconium nitride films are reported in this paper. The structural characterization was done by X-Ray diffraction which confirms (011) peak of Zr3N4 and a very low intensity (111) peak of Zr3N4. Optical properties was investigated by Uv-Vis-NIR spectrophotometer which showed that the films were transparent and maximum transmittance observed was around 82%. The wettability properties was investigated by contact angle goniometer which showed the films were hydrophobic and maximum contact angle achieved was 99.50.

  15. Characterization of an atmospheric double arc argon-nitrogen plasma source

    SciTech Connect

    Tu, X.; Cheron, B. G.; Yan, J. H.; Yu, L.; Cen, K. F.

    2008-05-15

    In the framework of studies devoted to hazardous waste destruction, an original dc double anode plasma torch has been designed and tested, which produces an elongated, weak fluctuation and reproducible plasma jet at atmospheric pressure. The arc instabilities and dynamic behavior of the double arc argon-nitrogen plasma jet are investigated through the oscillations of electrical signals by combined means of fast Fourier transform and Wigner distribution. In our experiment, the restrike mode is identified as the typical fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra and Wigner distributions exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which reveals that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the undulation of the power supply and both arc roots motion on the anode channels. In addition, the microscopic properties of the plasma jet inside and outside the arc chamber are investigated by means of optical emission spectroscopy, which yields excitation, electronic, rotational, and vibrational temperatures, as well as the electron number density. The results allow us to examine the validity criteria of a local thermodynamic equilibrium (LTE) state in the plasma arc. The measured electron densities are in good agreement with those calculated from the LTE model, which indicates that the atmospheric double arc argon-nitrogen plasma in the core region is close to the LTE state under our experimental conditions.

  16. ECR Plasma Sterilisation, Argon and Nitrogen Treated Plasma

    NASA Astrophysics Data System (ADS)

    Helhel, Selcuk; Oksuz, Lutfi; Cerezci, Osman; Rad, Abbas Y.

    2004-09-01

    ECR type plasma system was built to produce plasma in axial direction. Plasma was initiated in a specially designed Nickel - Chrome cylindrical vacuum tube which is being driven through dielectric window by 2.45GHz commercial magnetron source. Tube is also surrounded by a coil driving 150ADC to generate approximately 875Gauss magnetic field at the center. Langmuir probe and ICCD for optical spectrometry were used to characterize internal parameters like electron density, electron temperature and different characteristics of the plasma. Bacillus Subtilis var nigar, bacillus Stearothermophilus, bacillus pumilus E601, Escherichia coli and staphylococcus aureus type bacteria were selected as a reference. Each is resistant for different actions while the Bacilus cereus is the most resistant bacteria for microwave interaction. This study presents the effect of system on used bacteria. Those are gram positive and gram negative bacteria that refers to structure of cell wall. The sterilization efficacy of Argon type ECR plasma was found to be over 99, 5% in Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis (vegetative cell), Bacillus cereus (vegetative cell), Bacillus pumilus and Escherichia coli. System response type is less than 2 minutes.

  17. Development of a diffuse air-argon plasma source using a dielectric-barrier discharge at atmospheric pressure

    SciTech Connect

    Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing; Duan Yixiang

    2013-01-21

    A stable diffuse large-volume air plasma source was developed by using argon-induced dielectric-barrier discharges at atmospheric pressure. This plasma source can be operated in a filamentary discharge with the average areal power density of 0.27 W/cm{sup 2} and the gas temperature of 315{+-}3 K. Spatial measurement of emission spectrum and temperature indicates that this plasma is uniform in the central region along the transverse direction. It is also found that the formation of diffuse air plasma mainly lies in the creation of sufficient seed electrons by the Penning effect through collisions between two argon or nitrogen metastables at low electric fields.

  18. Air separation process using packed columns for oxygen and argon recovery

    SciTech Connect

    Thorogood, R.M.; Bennett, D.L.; Allam, R.J.; Prentice, A.L.; Dawson, B.K.

    1989-10-03

    This patent describes an improvement in a process for the separation of mixtures, which comprise oxygen, nitrogen, and argon, by cryogenic distillation in an integrated multi-column distillation system of at least three distillation columns, having a higher pressure column, low pressure column and an argon sidearm column. Wherein the argon sidearm column integrally communicates with the low pressure column. Wherein each column of the integrated distillation system, a liquid phase stream and a vapor phase stream are intimately contacted thereby allowing mass transfer. The improvement involves increasing argon recovery. It comprises effectuating the intimate contact of the liquid and vapor phase streams in the low pressure column and the argon sidearm column by utilizing a structured packing.

  19. Neutral gas temperature estimates and metastable resonance energy transfer for argon-nitrogen discharges

    SciTech Connect

    Greig, A. Charles, C.; Boswell, R. W.

    2016-01-15

    Rovibrational spectroscopy band fitting of the nitrogen (N{sub 2}) second positive system is a technique used to estimate the neutral gas temperature of N{sub 2} discharges, or atomic discharges with trace amounts of a N{sub 2} added. For mixtures involving argon and N{sub 2}, resonant energy transfer between argon metastable atoms (Ar*) and N{sub 2} molecules may affect gas temperature estimates made using the second positive system. The effect of Ar* resonance energy transfer is investigated here by analyzing neutral gas temperatures of argon-N{sub 2} mixtures, for N{sub 2} percentages from 1% to 100%. Neutral gas temperature estimates are higher than expected for mixtures involving greater than 5% N{sub 2} addition, but are reasonable for argon with less than 5% N{sub 2} addition when compared with an analytic model for ion-neutral charge exchange collisional heating. Additional spatiotemporal investigations into neutral gas temperature estimates with 10% N{sub 2} addition demonstrate that although absolute temperature values may be affected by Ar* resonant energy transfer, spatiotemporal trends may still be used to accurately diagnose the discharge.

  20. Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen

    NASA Astrophysics Data System (ADS)

    Bondar, A.; Buzulutskov, A.; Dolgov, A.; Nosov, V.; Shekhtman, L.; Shemyakina, E.; Sokolov, A.

    2017-02-01

    A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49±7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N2 content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.

  1. [The Status of Hemostasis System in Hypoxic Nitrogen-Oxygen and Argon-Oxygen Diving Gases].

    PubMed

    Kuzichkin, D S; Markin, A A; Juravlyova, O A; Morukov, B V; Zabolotskaya, I V; Vostrikova, L V

    2015-01-01

    In this study the effect of factors of hermetic chamber with modified gas medium on the hemostasis system is analyzed in order to estimate and to compare different diving breathing gases. The parameters characterizing pro-, anticoagulant as well as fibrinolytic components of hemostasis were determined using clotting, chromogenic and immunological methods. The applied exposure did not affect the activity and regulatory potential of hemostasis significantly; however, the nitrogen-oxygen and argon-oxygen diving gases have a different effect on the hemostasis functioning, especially in the recovery period.

  2. Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.

    PubMed

    Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

    2013-09-01

    The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements.

  3. A gas scintillation monitor for tritium gas in argon or in nitrogen.

    PubMed

    Campi, F; Mascherpa, C; Sterlini, C; Pacenti, P; Terrani, S

    1996-09-01

    For civilian purposes tritium is presently used in quantities of tens of PBq (MCi) in laboratories for the studies of tritium technology, at the Joint European Torus plant (Abingdon, Oxon, OX143A, UK) as fuel for the process of nuclear fusion, and in the manufacture of radio-luminescent items. Given the extreme mobility of tritium in most materials, it is necessary to use systems for double containment, such as glove boxes or spaces between primary and secondary containers, in which inert gas like argon or nitrogen flows. With these systems it is possible to recover tritium that escapes from the primary containment. Presently the gas flow is monitored continuously by means of ionization chambers which may present problems in particular applications ("memory effect" with high activity, strong dependence of the response on the presence of impurity, etc.). The aim of the work here presented is to determine the prospects for the realization of a new type of monitor mainly dedicated to the measurement of gas activity in isolation space of the containing systems of the high activity tritium plants. This monitor should have sufficient sensitivity, quick response, and should be easily decontaminated. As a detection technique we chose the scintillation produced in the inert gas by radioactive decay. With the first prototype, designed in cylindrical form, it was possible to observe gaseous scintillation events in mixture of tritium and argon or nitrogen. Following that, a spherical prototype was designed, of which we studied the performances and the dependence of the response varying the pressure, the concentration of tritium, the percentage of the impurity, and the gas flow rate. The results are satisfactory and suggest that the monitor could be used in glove boxes and double containment systems. The future research program will include tests involving large quantities of tritium and a study of the ideal dimensions and geometry of the detection chamber in order to optimize

  4. Cryogenic and Simulated Fuel Jet Breakup in Argon, Helium and Nitrogen Gas Flows

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1995-01-01

    Two-phase flow atomization of liquid nitrogen jets was experimentally investigated. They were co-axially injected into high-velocity gas flows of helium, nitrogen and argon, respectively, and atomized internally inside a two-fluid fuel nozzle. Cryogenic sprays with relatively high specific surface areas were produced, i.e., ratios of surface area to volume were fairly high. This was indicated by values of reciprocal Sauter mean diameters, RSMD's, as measured with a scattered- light scanning instrument developed at NASA Lewis Research Center. Correlating expressions were derived for the three atomizing gases over a gas temperature range of 111 to 422 K. Also, the correlation was extended to include waterjet breakup data that had been previously obtained in simulating fuel jet breakup in sonic velocity gas flow. The final correlating expression included a new dimensionless molecular-scale acceleration group. It was needed to correlate RSMD data, for LN2 and H2O sprays, with the fluid properties of the liquid jets and atomizing gases used in this investigation.

  5. Infrared spectra and electronic structure calculations for NN complexes with U, UN, and NUN in solid argon, neon, and nitrogen.

    PubMed

    Andrews, Lester; Wang, Xuefeng; Gong, Yu; Kushto, Gary P; Vlaisavljevich, Bess; Gagliardi, Laura

    2014-07-17

    Reactions of laser-ablated U atoms with N2 molecules upon codeposition in excess argon or neon at 4 K gave intense NUN and weak UN absorptions. Annealing produced progressions of new absorptions for the UN2(N2)1,2,3,4,5 and UN(N2)1,2,3,4,5,6 complexes. The neon-to-argon matrix shift decreases with increasing NN ligation and therefore the number of noble gas atoms left in the primary coordination sphere around the NUN molecule. Small matrix shifts are observed when the secondary coordination layers around the primary UN2(N2)1,2,3,4,5 and UN(N2)1,2,3,4,5,6 complexes are changed from neon-to-argon to nitrogen. Electronic structure, energy, and frequency calculations provide support for the identification of these complexes and the characterization of the N≡U≡N and U≡N core molecules as terminal uranium nitrides. Codeposition of U with pure nitrogen produced the saturated U(NN)7 complex, which UV irradiation converted to the NUN(NN)5 complex with slightly lower frequencies than found in solid argon.

  6. Global rate coefficients for ionization and recombination of carbon, nitrogen, oxygen, and argon

    NASA Astrophysics Data System (ADS)

    Annaloro, Julien; Morel, Vincent; Bultel, Arnaud; Omaly, Pierre

    2012-07-01

    The flow field modeling of planetary entry plasmas, laser-induced plasmas, inductively coupled plasmas, arcjets, etc., requires to use Navier-Stokes codes. The kinetic mechanisms implemented in these codes involve global (effective) rate coefficients. These rate coefficients result from the excited states coupling during a quasi-steady state. In order to obtain these global rate coefficients over a wide electron temperature (Te) range for ionization and recombination of carbon, nitrogen, oxygen, and argon, the behavior of their excited states is investigated using a zero-dimensional (time-dependent) code. The population number densities of these electronic states are considered as independent species. Their relaxation is studied within the range 3000 K ≤Te≤20 000 K and leads to the determination of the ionization (ki) and recombination (kr) global rate coefficients. Comparisons with existing data are performed. Finally, the ratio ki/kr is compared with the Saha equilibrium constant. This ratio increases more rapidly than the equilibrium constant for Te>15 000 K.

  7. Cryogenic spray vaporization in high-velocity helium, argon and nitrogen gasflows

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1993-01-01

    Effects of gas properties on cryogenic liquid-jet atomization in high-velocity helium, nitrogen, and argon gas flows were investigated. Volume median diameter, D(sub v.5e), data were obtained with a scattered-light scanning instrument. By calculating the change in spray drop size, -Delta D(sub v.5)(exp 2), due to droplet vaporization, it was possible to calculate D(sub v.5C). D(sub v.5C) is the unvaporized characteristic drop size formed at the fuel-nozzle orifice. This drop size was normalized with respect to liquid-jet diameter, D(sub O). It was then correlated with several dimensionless groups to give an expression for the volume median diameter of cryogenic LN2 sprays. This expression correlates drop size D(sub v.5c) with aerodynamic and liquid-surface forces so that it can be readily determined in the design of multiphase-flow propellant injectors for rocket combustors.

  8. Global rate coefficients for ionization and recombination of carbon, nitrogen, oxygen, and argon

    SciTech Connect

    Annaloro, Julien; Morel, Vincent; Bultel, Arnaud; Omaly, Pierre

    2012-07-15

    The flow field modeling of planetary entry plasmas, laser-induced plasmas, inductively coupled plasmas, arcjets, etc., requires to use Navier-Stokes codes. The kinetic mechanisms implemented in these codes involve global (effective) rate coefficients. These rate coefficients result from the excited states coupling during a quasi-steady state. In order to obtain these global rate coefficients over a wide electron temperature (T{sub e}) range for ionization and recombination of carbon, nitrogen, oxygen, and argon, the behavior of their excited states is investigated using a zero-dimensional (time-dependent) code. The population number densities of these electronic states are considered as independent species. Their relaxation is studied within the range 3000 K{<=}T{sub e}{<=}20 000 K and leads to the determination of the ionization (k{sub i}) and recombination (k{sub r}) global rate coefficients. Comparisons with existing data are performed. Finally, the ratio k{sub i}/k{sub r} is compared with the Saha equilibrium constant. This ratio increases more rapidly than the equilibrium constant for T{sub e}>15 000 K.

  9. A Supersonic Argon/Air Coaxial Jet Experiment for Computational Fluid Dynamics Code Validation

    NASA Technical Reports Server (NTRS)

    Clifton, Chandler W.; Cutler, Andrew D.

    2007-01-01

    A non-reacting experiment is described in which data has been acquired for the validation of CFD codes used to design high-speed air-breathing engines. A coaxial jet-nozzle has been designed to produce pressure-matched exit flows of Mach 1.8 at 1 atm in both a center jet of argon and a coflow jet of air, creating a supersonic, incompressible mixing layer. The flowfield was surveyed using total temperature, gas composition, and Pitot probes. The data set was compared to CFD code predictions made using Vulcan, a structured grid Navier-Stokes code, as well as to data from a previous experiment in which a He-O2 mixture was used instead of argon in the center jet of the same coaxial jet assembly. Comparison of experimental data from the argon flowfield and its computational prediction shows that the CFD produces an accurate solution for most of the measured flowfield. However, the CFD prediction deviates from the experimental data in the region downstream of x/D = 4, underpredicting the mixing-layer growth rate.

  10. Laboratory Infrared Spectra of Polycyclic Aromatic Nitrogen Heterocycles: Quinoline, and Phenanthridine in Solid Argon and H2O

    NASA Technical Reports Server (NTRS)

    Bernstein, M. P.; Mattioda, A. L.; Sandford, S. A.; Hudgins, D. M.

    2004-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are common throughout the universe. Their detection and identification are based on telescopic infrared (IR) spectra compared with laboratory data. Polycyclic Aromatic Nitrogen Heterocycles (PANHs) are heterocyclic aromatics i.e., PAHs with carbon atoms replaced by a nitrogen atom. These molecules should be present in the interstellar medium, but have received relatively little attention. We present mid-IR spectra of two PANHs, quinoline (C9H7N), and phenanthridine (C13H9N) isolated in solid argon and frozen in solid H2O at 12 K, conditions yielding data directly comparable to astronomical observations. In contrast to simple PAHs, that do not interact strongly with solid H2O, the nitrogen atoms in PANHs are potentially capable of hydrogen bonding with H2O. Whereas the IR spectrum of phenanthridine in H2O is similar to that of the same compound isolated in an argon matrix, quinoline absorptions shift up to 16 cm(sup -1) (0.072 mm) between argon and H2O. Thus, astronomers will not always be able to rely on IR band positions of matrix isolated PANHs to correctly interpret the absorptions of PANHs frozen in H2O ice grains. Furthermore, our data suggest that relative band areas also vary, so determining column densities to better than a factor of 3 will require knowledge of the matrix in which the PANH is embedded and laboratory studies of relevant samples.

  11. Increased Efficiency in SI Engine with Air Replaced by Oxygen in Argon Mixture

    SciTech Connect

    Killingsworth, N J; Rapp, V H; Flowers, D L; Aceves, S M; Chen, J; Dibble, R

    2010-01-13

    Basic engine thermodynamics predicts that spark ignited engine efficiency is a function of both the compression ratio of the engine and the specific heat ratio of the working fluid. In practice the compression ratio of the engine is often limited due to knock. Both higher specific heat ratio and higher compression ratio lead to higher end gas temperatures and increase the likelihood of knock. In actual engine cycles, heat transfer losses increase at higher compression ratios and limit efficiency even when the knock limit is not reached. In this paper we investigate the role of both the compression ratio and the specific heat ratio on engine efficiency by conducting experiments comparing operation of a single-cylinder variable-compression-ratio engine with both hydrogen-air and hydrogen-oxygen-argon mixtures. For low load operation it is found that the hydrogen-oxygen-argon mixtures result in higher indicated thermal efficiencies. Peak efficiency for the hydrogen-oxygen-argon mixtures is found at compression ratio 5.5 whereas for the hydrogen-air mixture with an equivalence ratio of 0.24 the peak efficiency is found at compression ratio 13. We apply a three-zone model to help explain the effects of specific heat ratio and compression ratio on efficiency. Operation with hydrogen-oxygen-argon mixtures at low loads is more efficient because the lower compression ratio results in a substantially larger portion of the gas to reside in the adiabatic core rather than in the boundary layer and in the crevices, leading to less heat transfer and more complete combustion.

  12. Nitrogen fluorescence in air for observing extensive air showers

    NASA Astrophysics Data System (ADS)

    Keilhauer, B.; Bohacova, M.; Fraga, M.; Matthews, J.; Sakaki, N.; Tameda, Y.; Tsunesada, Y.; Ulrich, A.

    2013-06-01

    Extensive air showers initiate the fluorescence emissions from nitrogen molecules in air. The UV-light is emitted isotropically and can be used for observing the longitudinal development of extensive air showers in the atmosphere over tenth of kilometers. This measurement technique is well-established since it is exploited for many decades by several cosmic ray experiments. However, a fundamental aspect of the air shower analyses is the description of the fluorescence emission in dependence on varying atmospheric conditions. Different fluorescence yields affect directly the energy scaling of air shower reconstruction. In order to explore the various details of the nitrogen fluorescence emission in air, a few experimental groups have been performing dedicated measurements over the last decade. Most of the measurements are now finished. These experimental groups have been discussing their techniques and results in a series of Air Fluorescence Workshops commenced in 2002. At the 8th Air Fluorescence Workshop 2011, it was suggested to develop a common way of describing the nitrogen fluorescence for application to air shower observations. Here, first analyses for a common treatment of the major dependences of the emission procedure are presented. Aspects like the contributions at different wavelengths, the dependence on pressure as it is decreasing with increasing altitude in the atmosphere, the temperature dependence, in particular that of the collisional cross sections between molecules involved, and the collisional de-excitation by water vapor are discussed.

  13. Radiative properties of argon-helium-nitrogen-carbon-cobalt-nickel plasmas used in CNT synthesis

    NASA Astrophysics Data System (ADS)

    Salem, D.; Hannachi, R.; Cressault, Y.; Teulet, Ph; Béji, L.

    2015-02-01

    This work presents the radiative properties of argon-helium-nitrogen-carbon-nickel-cobalt thermal plasmas by the computation of net emission coefficients (NECs) under the assumption of a local thermodynamic equilibrium and at temperature range 1000-20 000 K. These mixtures were often used in the study of carbon nanotubes (CNTs) synthesis with arc plasma which becomes one of the most useful techniques in terms of flexibility of carbon nanostructures produced with fewer defects. The values of NEC allow estimation of total radiation losses in plasmas, by taking into account the emission radiation resulting from the atomic continuum, the molecular continuum, the atomic lines and some molecular bands. Free-free transitions (Bremsstrahlung) and free-bound (electron-ion recombination), have been considered for the calculation of atomic continuum. For bound-bound transitions, natural, resonance, Van der Waals, Stark and Doppler effects have been taken into account in the calculation of the lines broadenings while the self-absorption of the resonance lines has been treated using their escape factors. Molecular continuum has been only considered for N2, C2 and CN molecules whereas we have only taken into account diatomic systems N2, \\text{N}2+ , CN and C2 for the emission of the molecular bands. The results obtained show that even for low concentrations of Ni and Co in the plasma, the NECs are modified and considerably increase only at a low temperature (T < 8000 K) and the major contribution in the total radiation arises from the lines emission. However, the effect of the thickness of the plasma on plasma radiation has been analysed based on the self absorption phenomenon of resonance lines.

  14. Radiative properties of molecular nitrogen ions produced by helium Penning ionization and argon effects

    NASA Technical Reports Server (NTRS)

    Miller, George, III; Song, Kyo-Dong

    1994-01-01

    The development of hypersonic aerospace vehicles requires a better understanding on the thermal and chemical nonequilibrium kinetics of participating species in shock layers. The computational fluid dynamic (CFD) codes developed for such flowfields overestimate the radiation in the spectral region of 300 - 600 nm. A speculation for this overestimation is that inclusion of Ar, CO2, and H2O at the upper atmosphere flight region makes a significant impact on radiative kinetics of molecular nitrogen ions. To define the effects of minority species on the radiative kinetics of N2(+), an experimental setup was made by using the helium Penning ionization. The vibrational and rotational temperature were measured by mapping the vibrational and rotational distributions of N2(+) emission with high spectroscopic resolution and absolute intensity measurements. Measured vibrational temperatures were in the range from 18,000 to 36,000 K, and rotational temperatures were in the range from 300 to 370 K. The irradiance of 391.44 nm line and rotational and vibrational temperatures were analyzed to define argon and CO2 effects on the N2(+) emission. When Ar or CO2 is injected with N2, the rotational temperature did not change. The irradiances were reduced by 34 percent and 78 percent for the 50 percent of mixture of Ar and CO2, respectively. The vibrational temperatures were increased by 24.1 percent and 82.9 percent for the 50 percent of mixture of Ar and CO2, respectively. It appears that there are no significant effects from small concentrations of Ar and CO2 at the upper atmosphere flight region.

  15. Nitrogen Uptake During Air Diving

    DTIC Science & Technology

    1994-03-10

    depth. The measurement system was attached to a syringe pump and air was added to the closed-circuit system during compression. Gas was circulated...with the syringe pump until pre-dive temperatures and oxygen sensor output stabilized (oxygen sensor output varied with temperature). This equilibration...provided voltage output to the computer. The spirometer was calibrated with a 3 liter syringe (Collins, Model M-20). A temperature probe (YSI, Model

  16. Kinetic modelling for an atmospheric pressure argon plasma jet in humid air

    NASA Astrophysics Data System (ADS)

    Van Gaens, W.; Bogaerts, A.

    2013-07-01

    A zero-dimensional, semi-empirical model is used to describe the plasma chemistry in an argon plasma jet flowing into humid air, mimicking the experimental conditions of a setup from the Eindhoven University of Technology. The model provides species density profiles as a function of the position in the plasma jet device and effluent. A reaction chemistry set for an argon/humid air mixture is developed, which considers 84 different species and 1880 reactions. Additionally, we present a reduced chemistry set, useful for higher level computational models. Calculated species density profiles along the plasma jet are shown and the chemical pathways are explained in detail. It is demonstrated that chemically reactive H, N, O and OH radicals are formed in large quantities after the nozzle exit and H2, O2(1Δg), O3, H2O2, NO2, N2O, HNO2 and HNO3 are predominantly formed as ‘long living’ species. The simulations show that water clustering of positive ions is very important under these conditions. The influence of vibrational excitation on the calculated electron temperature is studied. Finally, the effect of varying gas temperature, flow speed, power density and air humidity on the chemistry is investigated.

  17. Honeycomb superlattice pattern in a dielectric barrier discharge in argon/air

    SciTech Connect

    Zhu, Ping; Dong, Lifang Yang, Jing; Gao, Yenan; Wang, Yongjie; Li, Ben

    2015-02-15

    We report on a honeycomb superlattice pattern in a dielectric barrier discharge in argon/air for the first time. It consists of hexagon lattice and honeycomb framework and bifurcates from a hexagon pattern as the applied voltage increases. A phase diagram of the pattern as a function of the gas component and gas pressure is presented. The instantaneous images show that the hexagon lattice and honeycomb framework are ignited in turn in each half voltage cycle. The honeycomb framework is composed of filaments ignited randomly. The spatiotemporal dynamics of honeycomb superlattice pattern is discussed by wall charges.

  18. High enthalpy, hypervelocity flows of air and argon in an expansion tube

    NASA Technical Reports Server (NTRS)

    Neely, A. J; Stalker, R. J.; Paull, A.

    1991-01-01

    An expansion tube with a free piston driver has been used to generate quasi-steady hypersonic flows in argon and air at flow velocities in excess of 9 km/s. Irregular test flow unsteadiness has limited the performance of previous expansion tubes, and it has been found that this can be avoided by attention to the interaction between the test gas accelerating expansion and the contact surface in the primary shock tube. Test section measurements of pitot pressure, static pressure and flat plate heat transfer are reported. An approximate analytical theory has been developed for predicting the velocities achieved in the unsteady expansion of the ionizing or dissociating test gas.

  19. Influence of nitrogen admixture to argon on the ion energy distribution in reactive high power pulsed magnetron sputtering of chromium

    NASA Astrophysics Data System (ADS)

    Breilmann, W.; Maszl, C.; Hecimovic, A.; von Keudell, A.

    2017-04-01

    Reactive high power impulse magnetron sputtering (HiPIMS) of metals is of paramount importance for the deposition of various oxides, nitrides and carbides. The addition of a reactive gas such as nitrogen to an argon HiPIMS plasma with a metal target allows the formation of the corresponding metal nitride on the substrate. The addition of a reactive gas introduces new dynamics into the plasma process, such as hysteresis, target poisoning and the rarefaction of two different plasma gases. We investigate the dynamics for the deposition of chromium nitride by a reactive HiPIMS plasma using energy- and time-resolved ion mass spectrometry, fast camera measurements and temporal and spatially resolved optical emission spectroscopy. It is shown that the addition of nitrogen to the argon plasma gas significantly changes the appearance of the localized ionization zones, the so-called spokes, in HiPIMS plasmas. In addition, a very strong modulation of the metal ion flux within each HiPIMS pulse is observed, with the metal ion flux being strongly suppressed and the nitrogen molecular ion flux being strongly enhanced in the high current phase of the pulse. This behavior is explained by a stronger return effect of the sputtered metal ions in the dense plasma above the racetrack. This is best observed in a pure nitrogen plasma, because the ionization zones are mostly confined, implying a very high local plasma density and consequently also an efficient scattering process.

  20. Bustling argon: biological effect

    PubMed Central

    2013-01-01

    Argon is a noble gas in group 18 of the periodic table. Certificated to exist in air atmosphere merely one century ago, discovery of argon shows interesting stories of researching and exploring. It was assumed to have no chemical activity. However, argon indeed present its biological effect on mammals. Narcotic effect of argon in diving operation and neur-protective function of argon in cerebral injury demonstrate that argon has crucial effect and be concentrated on is necessary. Furthermore, consider to be harmless to human, argon clinical application in therapy would be another option. PMID:24088583

  1. Ambient air particle transport into the effluent of a cold atmospheric-pressure argon plasma jet investigated by molecular beam mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dünnbier, M.; Schmidt-Bleker, A.; Winter, J.; Wolfram, M.; Hippler, R.; Weltmann, K.-D.; Reuter, S.

    2013-10-01

    Ambient air species, which are transported into the active effluent of an atmospheric-pressure plasma jet result in highly reactive oxygen and nitrogen species (RONS). Especially for the envisaged application field of plasma medicine, these RONS are responsible for strong biological responses. In this work, the effect of ambient air transport into the effluent of an atmospheric-pressure plasma argon jet on the on-axis densities of nitrogen, oxygen and argon was investigated by means of absolutely calibrated molecular beam mass spectrometry (MBMS). According to biomedical experiments a (bottomless) Petri dish was installed in front of the MBMS. In the following, the near flow field is referring to the region close to the nozzle exit and the far flow field is referring to the region beyond that. The absolute on-axis densities were obtained by three different methods, for the near flow field with VUV-absorption technique, for the far flow field with the MBMS and the total flow field was calculated with a computational fluid dynamics (CFD) simulation. The results of the ambient air particle densities of all independent methods were compared and showed an excellent agreement. Therefore the transport processes of ambient air species can be measured for the whole effluent of an atmospheric-pressure plasma jet. Additionally, with the validation of the simulation it is possible in future to calculate the ambient species transport for various gas fluxes in the same turbulent flow regime. Comparing the on-axis densities obtained with an ignited and with a non-ignited plasma jet shows that for the investigated parameters, the main influence on the ambient air species transport is due to the increased temperature in the case when the jet is switched on. Moreover, the presence of positive ions (e.g. ArN_{2}^{+} ) formed due to the interaction of plasma-produced particles and ambient air species, which are transported into the effluent, is shown.

  2. Morphology and characteristics of laser-induced aluminum plasma in argon and in air: A comparative study

    NASA Astrophysics Data System (ADS)

    Bai, Xueshi; Cao, Fan; Motto-Ros, Vincent; Ma, Qianli; Chen, Yanping; Yu, Jin

    2015-11-01

    In laser-induced breakdown spectroscopy (LIBS), ablation takes place in general in an ambient gas of the atmospheric pressure, often in air but also in noble gas such as argon or helium. The use of noble gas is known to significantly improve the performance of the technique. We investigate in this work the morphology and the characteristics of induced plasma in argon and in air. The purpose is to understand the mechanism of the analytical performance improvement by the use of argon ambient with respective to air ambient and the dependence on the other experimental parameters such as the laser fluence. The observation of plasma morphology in different ambient gases provides also information for better design of the detection system which optimizes the signal collection according to the used ambient gases. More specifically, the expansion of the plasma induced on an aluminum target with nanosecond infrared (1064 nm) laser pulse in two ambient gases, argon and the atmospheric air, has been studied with spectroscopic imaging at short delays and with emission spectroscopy at longer delays. With relatively low ablation laser fluence (65 J/cm2), similar morphologies have been observed in argon and in air over the early stage of plasma expansion, while diagnostics at longer delay shows stronger emission, higher electron density and temperature for plasma induced in argon. With higher ablation laser fluence (160 J/cm2) however, different expansion behaviors have been observed, with a stagnating aluminum vapor near the target surface in air while a propagating plume away from the target in argon. The craters left on the target surface show as well corresponding difference: in air, the crater is very shallow with a target surface chaotically affected by the laser pulse, indicating an effective re-deposition of the ablated material back to the crater; while in Ar a deeper crater is observed, indicating an efficient mass removal by laser ablation. At longer delays, a brighter

  3. An argon-nitrogen-hydrogen mixed-gas plasma as a robust ionization source for inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Makonnen, Yoseif; Beauchemin, Diane

    2014-09-01

    Multivariate optimization of an argon-nitrogen-hydrogen mixed-gas plasma for minimum matrix effects, while maintaining analyte sensitivity as much as possible, was carried out in inductively coupled plasma mass spectrometry. In the presence of 0.1 M Na, the 33.9 ± 3.9% (n = 13 elements) analyte signal suppression on average observed in an all-argon plasma was alleviated with the optimized mixed-gas plasma, the average being - 4.0 ± 8.8%, with enhancement in several cases. An addition of 2.3% v/v N2 in the outer plasma gas, and 0.50% v/v H2 to the central channel, as a sheath around the nebulizer gas flow, was sufficient for this drastic increase in robustness. It also reduced the background from ArO+ and Ar2+ as well as oxide levels by over an order of magnitude. On the other hand, the background from NO+ and ArN+ increased by up to an order of magnitude while the levels of doubly-charged ions increased to 7% (versus 2.7% in an argon plasma optimized for sensitivity). Furthermore, detection limits were generally degraded by 5 to 15 fold when using the mixed-gas plasma versus the argon plasma for matrix-free solution (although they were better for several elements in 0.1 M Na). Nonetheless, the drastically increased robustness allowed the direct quantitative multielement analysis of certified ore reference materials, as well as the determination of Mo and Cd in seawater, without using any matrix-matching or internal standardization.

  4. Reactions of pulsed laser produced boron and nitrogen atoms in a condensing argon stream

    NASA Astrophysics Data System (ADS)

    Andrews, Lester; Hassanzadeh, Parviz; Burkholder, Thomas R.; Martin, J. M. L.

    1993-01-01

    Reactions of pulsed laser produced B and N atoms at high dilution in argon favored diboron species. At low laser power with minimum radiation, the dominant reaction with N2 gave BBNN (3Π). At higher laser power, reactions of N atoms contributed the B2N (2B2), BNB (2Σu+), NNBN (1Σ+), and BNBN (3Π) species. These new transient molecules were identified from mixed isotopic patterns, isotopic shifts, and ab initio calculations of isotopic spectra.

  5. A new air-cooled argon/helium-compatible inductively coupled plasma torch.

    PubMed

    Miyahara, Hidekazu; Iwai, Takahiro; Kaburaki, Yuki; Kozuma, Tomokazu; Shigeta, Kaori; Okino, Akitoshi

    2014-01-01

    A new inductively coupled plasma (ICP) torch with an air-cooling system has been designed and developed for both argon and helium plasma. The same torch and impedance-matching network could be used to generate stable Ar- and He-ICP. The torch consists of three concentric quartz tubes. The carrier gas, plasma gas, and cooling gas flow through the intervals between each tube. In an experiment, it was found that Ar-ICP could form a stable plasma under the following conditions: RF power of 1 kW, plasma gas flow rate of 11 L min(-1), and cooling gas flow rate of 20 L min(-1). For He-ICP, an input RF power of 2 kW, which is two-times higher than that of a conventional He-ICP, could be constantly applied to the plasma with plasma gas and cooling gas flow rates of 15 and 20 L min(-1), respectively. Using this torch, it is possible to realize lower plasma gas consumption for Ar- and He-ICP and a high-power drive for He-ICP. It has been found that the air-cooling gas stabilizes the shape of the plasma due to the pressure difference between the cooling gas and the plasma gas.

  6. Effect of hydrogen addition on the deposition of titanium nitride thin films in nitrogen added argon magnetron plasma

    NASA Astrophysics Data System (ADS)

    Saikia, P.; Bhuyan, H.; Diaz-Droguett, D. E.; Guzman, F.; Mändl, S.; Saikia, B. K.; Favre, M.; Maze, J. R.; Wyndham, E.

    2016-06-01

    The properties and performance of thin films deposited by plasma assisted processes are closely related to their manufacturing techniques and processes. The objective of the current study is to investigate the modification of plasma parameters occurring during hydrogen addition in N2  +  Ar magnetron plasma used for titanium nitride thin film deposition, and to correlate the measured properties of the deposited thin film with the bulk plasma parameters of the magnetron discharge. From the Langmuir probe measurements, it was observed that the addition of hydrogen led to a decrease of electron density from 8.6 to 6.2  ×  (1014 m-3) and a corresponding increase of electron temperature from 6.30 to 6.74 eV. The optical emission spectroscopy study reveals that with addition of hydrogen, the density of argon ions decreases. The various positive ion species involving hydrogen are found to increase with increase of hydrogen partial pressure in the chamber. The thin films deposited were characterized using standard surface diagnostic tools such as x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), x-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Although it was possible to deposit thin films of titanium nitride with hydrogen addition in nitrogen added argon magnetron plasma, the quality of the thin films deteriorates with higher hydrogen partial pressures.

  7. Comparison of argon-based and nitrogen-based modified atmosphere packaging on bacterial growth and product quality of chicken breast fillets.

    PubMed

    Herbert, Ulrike; Rossaint, Sonja; Khanna, Meik-Ankush; Kreyenschmidt, Judith

    2013-05-01

    Poultry fillets were packaged under 6 different gas atmospheres (A: 15% Ar, 60% O2, 25% CO2; B: 15% N2, 60% O2, 25% CO2; C: 25% Ar, 45% O2, 30% CO2; D: 25% N2, 45% O2, 30% CO2; E: 82% Ar; 18% CO2; F: 82% N2, 18% CO2) and stored at 4°C. During storage, the growth of typical spoilage organisms (Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and Lactobacilli spp.) and total viable count were analyzed and modeled using the Gompertz function. Sensory analyses of the poultry samples were carried out by trained sensory panelists for color, odor, texture, drip loss, and general appearance. No significant difference in microbiological growth parameters was observed for fresh poultry stored under an argon-enriched atmosphere in comparison with nitrogen, except the B. thermosphacta stored under 82% argon. The sensory evaluation showed a significant effect of an argon-enriched atmosphere, particularly on color of meat stored under 15% argon (P < 0.05). In contrast, 25 and 82% argon concentrations in place of nitrogen showed no beneficial effect on sensory parameters.

  8. Thermomechanical fatigue behavior of SiC/Ti-24Al-11Nb in air and argon environments

    NASA Technical Reports Server (NTRS)

    Bartolotta, Paul A.; Verrilli, Michael J.

    1992-01-01

    A series of tension-tension, load-controlled thermomechanical fatigue (TMF) tests were conducted on a titanium aluminide composite in both laboratory air and a flowing argon environment. Results from these tests show that the environment plays an increasingly important role as applied stress levels are decreased. Differences in damage mechanisms between the two environments were observed which corresponds to observed variations in TMF lives.

  9. Nitrogen Dioxide's Impact on Indoor Air Quality

    EPA Pesticide Factsheets

    The two most prevalent oxides of nitrogen are nitrogen dioxide (NO2) and nitric oxide (NO). Both are toxic gases with NO2 being a highly reactive oxidant and corrosive. The primary sources indoors are combustion processes.

  10. GASP - THERMODYNAMIC AND TRANSPORT PROPERTIES OF HELIUM, METHANE, NEON, NITROGEN, CARBON MONOXIDE, CARBON DIOXIDE, OXYGEN, AND ARGON

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.

    1994-01-01

    A computer program, GASP, has been written to calculate the thermodynamic and transport properties of argon, carbon dioxide, carbon monoxide, fluorine, methane, neon, nitrogen, and oxygen. GASP accepts any two of pressure, temperature, or density as input. In addition, entropy and enthalpy are possible inputs. Outputs are temperature, density, pressure, entropy, enthalpy, specific heats, expansion coefficient, sonic velocity, viscosity, thermal conductivity, and surface tension. A special technique is provided to estimate the thermal conductivity near the thermodynamic critical point. GASP is a group of FORTRAN subroutines. The user typically would write a main program that invoked GASP to provide only the described outputs. Subroutines are structured so that the user may call only those subroutines needed for his particular calculations. Allowable pressures range from 0.l atmosphere to 100 to l,000 atmospheres, depending on the fluid. Similarly, allowable pressures range from the triple point of each substance to 300 degrees K to 2000 degrees K, depending on the substance. The GASP package was developed to be used with heat transfer and fluid flow applications. It is particularly useful in applications of cryogenic fluids. Some problems associated with the liquefication, storage, and gasification of liquefied natural gas and liquefied petroleum gas can also be studied using GASP. This program is written in FORTRAN IV for batch execution and is available for implementation on IBM 7000 series computers. GASP was developed in 1971.

  11. Experimental and Theoretical Estimation of Excited Species Generation in Pulsed Electron Beam-Generated Plasmas Produced in Pure Argon, Nitrogen, Oxygen, and Their Mixtures

    DTIC Science & Technology

    2011-05-13

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--11-9333 Experimental and Theoretical Estimation of Excited Species Generation in ...Pulsed Electron Beam–Generated Plasmas Produced in Pure Argon, Nitrogen, Oxygen, and Their Mixtures May 13, 2011 Approved for public release...PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Experimental and Theoretical Estimation of Excited Species Generation in Pulsed Electron Beam

  12. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Joshi, Ujjwal Man; Subedi, Deepak Prasad

    2015-07-01

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  13. Improved installation prototype for measurement of low argon-37 activity

    NASA Astrophysics Data System (ADS)

    Pakhomov, Sergei; Dubasov, Yuri

    2015-04-01

    On-site Inspection (OSI) is a key element of verification of State Parties' compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). An on-site inspection is launched to establish whether or not a nuclear explosion has been carried out. One of the most significant evidence of n underground nuclear explosion (UNE) is detection above background concentrations of argon-37 in near surface air. Argon-37 is formed in large amounts at interaction of neutrons of UNE with the potassium which is a part of the majority of rocks. Its estimated contents for the 100th days after explosion with a energy of 1000 t of TNT near a surface can vary from 1 to 1000 mBq/m3. The background concentrations of argon-37 in subsoil air vary 1 do100 mBq/m3. Traditionally, for argon-37 activity measurement the gas-proportional counters are used. But at Khlopin Radium institute the developments of the new type of highly sensitive and low-background installation capable to provide the required range of measurements of the argon-37 concentration are conducted. The liquid scintillation method of the registration of the low-energetic argon-37 electrons is the basic installation principle and as scintillator, the itself condensed air argon sample is used. Registration of scintillations of liquid argon is made by means of system from 3 PMT which cathodes are cooled near to the temperature of liquid nitrogen together with the measuring chamber in which placed the quartz glass ampule, containing the measured sample of the liquefied argon. For converse the short wavelength photons (λ = 127 nm) of liquid argon scintillations to more long-wave, corresponding to the range of PMT sensitivity, the polymer film with tetra-phenyl-butadiene (TPB) is provided. Even the insignificant impurities of nitrogen, oxygen and others gaseous in the liquid argon samples can to cause the quenching of scintillation, especially their slow components. To account this effect and it influence on change of registration

  14. 19. INTERIOR VIEW INSIDE BUNKER SHOWING NITROGEN TANKS, 'MOBILE AIR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. INTERIOR VIEW INSIDE BUNKER SHOWING NITROGEN TANKS, 'MOBILE AIR MONITOR' EQUIPMENT, MAN. INEL PHOTO NUMBER 65-6183, TAKEN NOVEMBER 10, 1965. - Idaho National Engineering Laboratory, Advanced Reentry Vehicle Fusing System, Scoville, Butte County, ID

  15. The Oxides of Nitrogen in Air Pollution.

    ERIC Educational Resources Information Center

    California State Air Resources Board, Sacramento.

    Research on the health effects of oxides of nitrogen and on the role of oxides of nitrogen in producing photochemical smog effects is presented in this report. Prepared by the California State Department of Public Health at the request of the State Legislature, it gives a comprehensive review of available information, as well as the need for air…

  16. A Method to Exchange Air Nitrogen Emission Reductions for Watershed Nitrogen Load Reductions

    EPA Science Inventory

    Presentation of the method developed for the Chesapeake Bay Program to estimate changes in nitrogen loading to Chesapeake due to changes in Bay State state-level nitrogen oxide emissions to support air-water trading by the Bay States. Type for SticsUnder AMAD Application QAPP, QA...

  17. Type of wear for the pair Ti6Al4V/PCTFE in ambient air and in liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Bozet, J.-L.

    1993-04-01

    The pair Ti6Al4V/polychlorotrifluoroethylene (PCTFE) on a pin-on-disk tribometer in ambient air and liquid nitrogen with the contact pressure and sliding speed ranging from 3 to 9 MPa and 0.03 to 0.05 m/s, respectively, is evaluated within the framework of a high pressure valves for cryogenic rocket engines project. Results show that an abrasion wear process, which is closely connected with a tribochemical wear process producing fluorides and an abrasive form of carbon, exists when PCTFE is continuously rubbed against Ti6Al4V in ambient air, liquid nitrogen, and gaseous argon. Degradations detected on the Ti6Al4V surface are found to be unacceptable in most cases, but in the real cryotechnic valves this type of wear was not observed. The latter is attributed to the great dwell time between actuations and the low speed of the reciprocating movements which considerably limit the heating.

  18. Neutral gas temperature maps of the pin-to-plate argon micro discharge into the ambient air

    SciTech Connect

    Xu, S. F.; Zhong, X. X.; Majeed, Asif

    2015-03-15

    This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device. The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.

  19. Air Pollution Impacts on Global Crop Productivity and Nitrogen Depositio

    NASA Astrophysics Data System (ADS)

    Heald, C. L.; Tai, A. P. K.; Val Martin, M.

    2014-12-01

    The biosphere is undeniably transformed by air pollution. Emissions, climate change, and land use change are all expected to substantially alter future air quality. In this presentation, we discuss near-term projections (2050) of air quality impacts on both crop productivity and nitrogen deposition. First, we contrast the relative impacts of ozone air pollution and a warming climate on global crop yields. To do so, we define statistical crop yield functions to a warming climate based on the historical record. We combine these relationships with ozone-damage estimates and apply these to future air quality and climate projections from a global coupled chemistry-climate model (CESM). We find substantial variability in the response, with certain regions or crops more sensitive to ozone pollution and others more sensitive to warming. This work demonstrates that air quality management is a key element to ensuring global food security. Second, we examine the relative impacts of anthropogenic emissions, climate change, and land use change on global nitrogen deposition. Nitrogen deposition has rapidly increased over the Anthropocene. Excess deposition of nitrogen to ecosystems can lead to eutrophication of waters, and a decrease in biodiversity. We use the CESM to investigate two scenarios (RCP 4.5 and RCP8.5) and focus our analysis on the impacts on diverse ecoregions in North America, Europe, and Asia.

  20. Special Equations of State for Methane, Argon, and Nitrogen for the Temperature Range from 270 to 350 K at Pressures up to 30 MPa

    NASA Astrophysics Data System (ADS)

    Wagner, W.; Span, R.

    1993-07-01

    In order to describe the thermodynamic behavior of methane, argon, and nitrogen in the so-called “natural-gas region,” namely, from 270 to 350 K at pressures up to 30 MPa as accurate as possible with equations of a very simple form, new equations of state for these three substances have been developed. These equations are in the form of a fundamental equation in the dimensionless Helmholtz energy; for calculating the pressure or the density, the corresponding equations explicit in pressure are also given. The residual parts of the Helmholtz function representing the behavior of the real gas contain 12 fitted coefficients for methane, 8 for argon, and 7 for nitrogen. The thermodynamic relations between the Helmholtz energy and the most important thermodynamic properties and the needed derivatives of the equations are explicitly given; to assist the user there is also a table with values for computer-program verification. The uncertainties when calculating the density ρ, the speed of sound w, the isobaric specific heat capacity c p, and the isochoric specific heat capacity c v are estimated as follows. For all three substances it is Δρ/ρ≤±0.02 % for p≤ 12 MPa and Δρ/ρ ≤ ±0.05% for higher pressures. For methane it is Δw/w≤±0.02% for p≤10 MPa and Δw/w≤+-0.1% for higher pressures; for argon it is Δw/w≲-0.1 % for p≤ 7 MPa, Δw/w≤±0.3 % for 7 < p≤30 MPa; and for nitrogen it is Δw/w≤±0.1% for p≤1.5 MPa and Δw/w±0.5% for higher pressures. For all three substances it is Δc p/ c p≤±1 % and ΔC v/ C v≤±1 % in the entire range.

  1. The Solubility of Nitrogen and Air in Liquids

    NASA Astrophysics Data System (ADS)

    Battino, Rubin; Rettich, Timothy R.; Tominaga, Toshihiro

    1984-04-01

    This review covers the solubility of nitrogen and air in liquids as a function of temperature and pressure. Solubility data for individual systems were critically evaluated. Recommended or tentative values are presented as smoothing equations and/or in tabular form. Trends in homologous series or related solvents are discussed. Data for the n-alkanes were smoothed with respect to temperature, pressure, and carbon number. Liquids include: water; heavy water; seawater; aqueous salt solutions; mixed solvents; hydrocarbons; organic compounds containing oxygen, halogen, sulfur, nitrogen, or silicon; olive oil; various biological fluids; H2S; SO2; NH3; CO2; nitrogen oxides; and several halogen and boron containing inorganic solvents.

  2. Variable oxygen/nitrogen enriched intake air system for internal combustion engine applications

    DOEpatents

    Poola, Ramesh B.; Sekar, Ramanujam R.; Cole, Roger L.

    1997-01-01

    An air supply control system for selectively supplying ambient air, oxygen enriched air and nitrogen enriched air to an intake of an internal combustion engine includes an air mixing chamber that is in fluid communication with the air intake. At least a portion of the ambient air flowing to the mixing chamber is selectively diverted through a secondary path that includes a selectively permeable air separating membrane device due a differential pressure established across the air separating membrane. The permeable membrane device separates a portion of the nitrogen in the ambient air so that oxygen enriched air (permeate) and nitrogen enriched air (retentate) are produced. The oxygen enriched air and the nitrogen enriched air can be selectively supplied to the mixing chamber or expelled to atmosphere. Alternatively, a portion of the nitrogen enriched air can be supplied through another control valve to a monatomic-nitrogen plasma generator device so that atomic nitrogen produced from the nitrogen enriched air can be then injected into the exhaust of the engine. The oxygen enriched air or the nitrogen enriched air becomes mixed with the ambient air in the mixing chamber and then the mixed air is supplied to the intake of the engine. As a result, the air being supplied to the intake of the engine can be regulated with respect to the concentration of oxygen and/or nitrogen.

  3. Characterization of argon direct-current glow discharge with a longitudinal electric field applied at ambient air

    PubMed Central

    Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang

    2014-01-01

    A direct-current-driven plasma jet is developed by applying a longitudinal electric field on the flowing argon at ambient air. This plasma shows a torch shape with its cross-section increased from the anode to the cathode. Comparison with its counterparts indicates that the gas flow plays a key role in variation of the plasma structure and contributes much to enlarging the plasma volume. It is also found that the circular hollow metal base promotes generation of plasma with a high-power volume density in a limited space. The optical emission spectroscopy (OES) diagnosis indicates that the plasma comprises many reactive species, such as OH, O, excited N2, and Ar metastables. Examination of the rotational and vibrational temperature indicates that the plasma is under nonequilibrium condition and the excited species OH(A 2Σ+), O(5P), and N2(C 3Πu) are partly generated by energy transfer from argon metastables. The spatially resolved OES of plasma reveals that the negative glow, Faraday dark space, and positive column are distributed across the gas gap. The absence of the anode glow is attributed to the fact that many electrons in the vicinity of the anode follow ions into the positive column due to the ambipolar diffusion in the flowing gas. PMID:25205176

  4. Anomalous high-velocity outbursts ejected from the surface of tungsten microdroplets in a flow of argon-air plasma

    NASA Astrophysics Data System (ADS)

    Gulyaev, I. P.; Dolmatov, A. V.; Gulyaev, P. Yu; Iordan, V. I.; Kharlamov, M. Yu; Krivtsun, I. V.

    2016-02-01

    For the first time, a phenomenon of high-velocity outbursts ejected from the surface of liquid tungsten microparticles in a flow of argon-air plasma under atmospheric pressure was observed. As tungsten particles sized 50 to 200 μm moved in a plasma flow, stratified radiating spheres up to 9 mm in diameter formed around such particles. The spheres were sources of high-velocity outbursts whose ejection direction coincided with the direction of the plasma flow. The velocity of the anomalous outbursts amounted to 3-20 km/s. In the outburst images, the distribution of glow intensity along outburst tracks exhibited a wavy decaying behavior with a wavelength of 5-15 mm. Possible physical factors that could be the cause of the phenomenon are discussed.

  5. Scanning drift tube measurements of electron transport parameters in different gases: argon, synthetic air, methane and deuterium

    NASA Astrophysics Data System (ADS)

    Korolov, I.; Vass, M.; Donkó, Z.

    2016-10-01

    Measurements of transport coefficients of electrons in a scanning drift tube apparatus are reported for different gases: argon, synthetic air, methane and deuterium. The experimental system allows the spatio-temporal development of the electron swarms (‘swarm maps’) to be recorded and this information, when compared with the profiles predicted by theory, makes it possible to determine the ‘time-of-flight’ transport coefficients: the bulk drift velocity, the longitudinal diffusion coefficient and the effective ionization coefficient, in a well-defined way. From these data, the effective Townsend ionization coefficient is determined as well. The swarm maps provide, additionally, direct, unambiguous information about the hydrodynamic/non-hydrodynamic regimes of the swarms, aiding the selection of the proper regions applicable for the determination of the transport coefficients.

  6. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    SciTech Connect

    Joshi, Ujjwal Man Subedi, Deepak Prasad

    2015-07-31

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H{sub 2}O), glycerol (C{sub 3}H{sub 8}O{sub 3}) and diiodomethane (CH{sub 2}I{sub 2}) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  7. Tissue gas and blood analyses of human subjects breathing 80% argon and 20% oxygen

    NASA Technical Reports Server (NTRS)

    Horrigan, D. J.; Wells, C. H.; Guest, M. M.; Hart, G. B.; Goodpasture, J. E.

    1979-01-01

    Eight human volunteers, individually studied in a hyperbaric chamber, breathed: (1) air at 1 ATA; (2) 80% argon and 20% oxygen at 1 ATA for 30 min; (3) air at 1 ATA for 30 min; (4) 100% O2 at 1 ATA for 30 min; (5) air at 1 ATA for 30 min; (6) 100% O2 at 2 ATA for 60 min; and (7) 80% argon and 20% oxygen at 1 ATA for 30 min. Oxygen, carbon dioxide, nitrogen, and argon tensions were measured in muscle and subcutaneous tissue by mass spectroscopic analyses. Venous blood obtained at regular intervals was analyzed for coagulation and fibrinolytic factors. Inert gas narcosis was not observed. After breathing argon for 30 min, muscle argon tensions were almost three times the subcutaneous tensions. Argon wash-in mirrored nitrogen wash-out. Argon wash-in and wash-out had no effect on tissue PO2 or PCO2. Coagulation and fibrinolytic changes usually associated with vascular bubbles were absent.

  8. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  9. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  10. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  11. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... National Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) 1. General (a) This... national ambient air quality standards for oxides of nitrogen as measured by nitrogen dioxide (“NO2...

  12. Multi-stage combustion using nitrogen-enriched air

    DOEpatents

    Fischer, Larry E.; Anderson, Brian L.

    2004-09-14

    Multi-stage combustion technology combined with nitrogen-enriched air technology for controlling the combustion temperature and products to extend the maintenance and lifetime cycles of materials in contact with combustion products and to reduce pollutants while maintaining relatively high combustion and thermal cycle efficiencies. The first stage of combustion operates fuel rich where most of the heat of combustion is released by burning it with nitrogen-enriched air. Part of the energy in the combustion gases is used to perform work or to provide heat. The cooled combustion gases are reheated by additional stages of combustion until the last stage is at or near stoichiometric conditions. Additional energy is extracted from each stage to result in relatively high thermal cycle efficiency. The air is enriched with nitrogen using air separation technologies such as diffusion, permeable membrane, absorption, and cryogenics. The combustion method is applicable to many types of combustion equipment, including: boilers, burners, turbines, internal combustion engines, and many types of fuel including hydrogen and carbon-based fuels including methane and coal.

  13. 75 FR 6473 - Primary National Ambient Air Quality Standards for Nitrogen Dioxide

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-09

    ... Protection Agency 40 CFR Parts 50 and 58 Primary National Ambient Air Quality Standards for Nitrogen Dioxide... Ambient Air Quality Standards for Nitrogen Dioxide AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: Based on its review of the air quality criteria for oxides of nitrogen and...

  14. Synthesis and Characterization of Nitrogen-Doped Graphene

    DTIC Science & Technology

    2012-09-01

    samples from GO under argon and nitrogen atmospheres. Graphene samples were characterized by X-Ray Diffraction, Transmission Electron Microscopy...was closed and air was removed from inside the furnace using an attached vacuum pump. When the vacuum reached 97%, the furnace was filled with argon ...precursor materials. For comparison, an Atmospheric Microwave Plasma Torch system (ATP) was used to produce graphene samples under argon and

  15. Thermal degradation of cereal straws in air and nitrogen

    SciTech Connect

    Ghaly, A.E.; Ergundenler, A.

    1991-12-31

    The termogravimetric behavior of four cereal straws (wheat, barley, oats, and rye) was examined at three heating rates (10, 20, and 50{degrees}C/min) in air and nitrogen atmospheres. The thermal degradation rate in active and passive pyrolysis zones, the initial degradation temperature, and the residual weight at 600{degrees}C were determined for these straws in both atmospheres. Increasing the heating rate increased the thermal degradation rate, and decreased both the initial degradation temperature and the residual weight at 600{degrees}C. The higher the cellulosic content of the straw, the higher the thermal degradation rate and the initial degradation temperature. Also, higher ash content in the straw resulted in higher residual weight at 600{degrees}C. The thermal degradation rate in active pyrolysis zone was lower in air atmosphere than in nitrogen atmosphere, whereas the thermal degradation rate in passive pyrolysis zone and the residual weight at 600{degrees}C were higher in nitrogen atmosphere than in air atmosphere.

  16. Incident shock-wave characteristics in air, argon, carbon dioxide, and helium in a shock tube with unheated helium driver

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Jones, J. J.

    1975-01-01

    Incident shock-wave velocities were measured in the Langley 6-inch expansion tube, operated as a shock tube, with air, argon, carbon dioxide, and helium as test gases. Unheated helium was used as the driver gas and most data were obtained at pressures of approximately 34 and 54 MN/sq m. A range of pressure ratio across the diaphragm was obtained by varying the quiescent test-gas pressure, for a given driver pressure, from 0.0276 to 34.5 kN/sq m. Single- and double-diaphragm modes of operation were employed and diaphragms of various materials tested. Shock velocity was determined from microwave interferometer measurements, response of pressure transducers positioned along interferometer measurements, response of pressure transducers positioned along the driven section (time-of-arrival gages), and to a lesser extent, measured tube-wall pressure. Velocities obtained from these methods are compared and limitations of the methods discussed. The present results are compared with theory and the effects of diaphragm mode (single or double diaphragm), diaphragm material, heating of the driver gas upon pressurization of the driver section, diaphragm opening time, interface mixing, and two-dimensional (nonplanar) flow are discussed.

  17. Study on structural, morphological and thermal properties of surface modified polyvinylchloride (PVC) film under air, argon and oxygen discharge plasma

    NASA Astrophysics Data System (ADS)

    Suganya, Arjunan; Shanmugavelayutham, Gurusamy; Serra Rodríguez, Carmen

    2016-09-01

    The effect of air, argon, oxygen DC glow discharge plasma on the polyvinylchloride (PVC) film synthesized by solution casting technique, were evaluated via changes in physio-chemical properties such as structural, morphological, crystalline, thermal properties. The PVC film was plasma treated as a function of exposure time and different plasma forming gases, while other operating parameters such as power and pressure remained constant at 100 W and 2 Pa respectively. The plasma treated PVC were characterized by static contact angle, ATR-FTIR, XPS, AFM and T-peel analysis. It was found that various gaseous plasma treatments have improved the polar components, surface roughness on the surface of PVC which was confirmed by XPS, AFM, resulting in highly enhanced wettability and adhesion. X-ray diffraction study showed that plasma treatment does not persuade considerable change, even though it vaguely induces the crystallinity. The thermal properties of plasma treated PVC were evaluated by Differential Scanning Calorimetry and it was observed that O2 plasma treatment gives higher glass transition temperature of 87.21 °C compared with the untreated one. The glass transition temperature slightly increased for Oxygen plasma treated material due to the presence of higher concentration of the polar functional groups on the PVC surface due to strong intramolecular bonding.

  18. 76 FR 46083 - Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Sulfur

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-01

    ... Quality Standards for Oxides of Nitrogen and Sulfur; Proposed Rule #0;#0;Federal Register / Vol. 76 , No... RIN 2060-AO72 Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Sulfur... nitrogen and oxides of sulfur. Based on its review, EPA proposes to retain the current nitrogen dioxide...

  19. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres.

    PubMed

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-25

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al(+) regardless of the background gas species, whereas Cr(2+) ions were dominating in Ar and N2 and Cr(+) in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.

  20. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    PubMed Central

    Franz, Robert; Polcik, Peter; Anders, André

    2015-01-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings. PMID:26120236

  1. 76 FR 68698 - Approval and Promulgation of Air Quality Implementation Plans; Virginia; Revision to Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ...- 9487-7] Approval and Promulgation of Air Quality Implementation Plans; Virginia; Revision to Nitrogen... Commonwealth of Virginia that revises regulatory language that inadvertently ended its nitrogen oxides (NO...

  2. Comparative study on contribution of charge-transfer collision to excitations of iron ion between argon radio-frequency inductively-coupled plasma and nitrogen microwave induced plasma

    NASA Astrophysics Data System (ADS)

    Satoh, Kozue; Wagatsuma, Kazuaki

    2015-06-01

    This paper describes an ionization/excitation phenomenon of singly-ionized iron occurring in an Okamoto-cavity microwave induced plasma (MIP) as well as an argon radio-frequency inductively-coupled plasma (ICP), by comparing the Boltzmann distribution among iron ionic lines (Fe II) having a wide range of the excitation energy from 4.76 to 9.01 eV. It indicated in both the plasmas that plots of Fe II lines having lower excitation energies (4.76 to 5.88 eV) were fitted on each linear relationship, implying that their excitations were caused by a dominant thermal process such as collision with energetic electron. However, Fe II lines having higher excitation energies (more than 7.55 eV) had a different behavior from each other. In the ICP, Boltzmann plots of Fe II lines assigned to the higher excited levels also followed the normal Boltzmann relationship among the low-lying excited levels, even including a deviation from it in particular excited levels having an excitation energy of ca. 7.8 eV. This deviation can be attributed to a charge-transfer collision with argon ion, which results in the overpopulation of these excited levels, but the contribution is small. On the other hand, the distribution of the high-lying excited levels was non-thermal in the Okamoto-cavity MIP, which did not follow the normal Boltzmann relationship among the low-lying excited levels. A probable reason for the non-thermal characteristics in the MIP is that a charge-transfer collision with nitrogen molecule ion having many vibrational/rotational levels could work for populating the 3d64p (3d54s4p) excited levels of iron ion broadly over an energy range of 7.6-9.0 eV, while collisional excitation by energetic electron would occur insufficiently to excite these high-energy levels.

  3. Titanium Dioxide Coatings Sprayed by a Water-Stabilized Plasma Gun (WSP) with Argon and Nitrogen as the Powder Feeding Gas: Differences in Structural, Mechanical and Photocatalytic Behavior

    NASA Astrophysics Data System (ADS)

    Ctibor, P.; Pala, Z.; Sedláček, J.; Štengl, V.; Píš, I.; Zahoranová, T.; Nehasil, V.

    2012-06-01

    Titanium dioxide coatings were sprayed by a water-stabilized plasma gun to form robust self-supporting bodies with a photocatalytically active surface. Agglomerated nanometric powder was used as a feedstock. In one case argon was used as a powder-feeding as well as coating-cooling gas whereas in the other case nitrogen was used. Stainless steel was used as a substrate and the coatings were released after the cooling. Over one millimeter thick self-supporting bodies were studied by XRD, HR-TEM, XPS, Raman spectroscopy, UV-VIS spectrophotometry and photocatalytic tests. Selected tests were done at the surface as well as at the bottom side representing the contact surface with the substrate during the spray process. Porosity was studied by image analysis on polished cross sections where also microhardness was measured. The dominant phase present in the sprayed samples was rutile, whereas anatase was only a minor component. The hydrogen content in the nitrogen-assisted coating was higher, but the character of the optical absorption edge remained the same for both samples. Photoelectron spectroscopy revealed differences in the character of the O1s peak between both samples. The photocatalytic activity was tested by decomposition of acetone at UV illumination, whereas also the end products—CO and CO2—were monitored. The nitrogen-assisted coating was revealed as a more efficient photocatalyst. Certain aspects of a thermal post-treatment on the coatings are discussed as well. Color and electrical conductivity are markedly changed at annealing at 760 °C, whereas only very small changes of the as-sprayed coating character correspond to annealing at 500 °C.

  4. Defining Nitrogen Kinetics for Air Break in Prebreathe

    NASA Technical Reports Server (NTRS)

    Conkin, Johnny

    2009-01-01

    Actual tissue nitrogen (N2) kinetics are complex; the uptake and elimination is often approximated with a single half-time compartment in statistical descriptions of denitrogenation [prebreathe (PB)] protocols. Air breaks during PB complicate N2 kinetics. A comparison of symmetrical versus asymmetrical N2 kinetics was performed using the time to onset of hypobaric decompression sickness (DCS) as a surrogate for actual venous N2 tension. Published results of 12 tests involving 179 hypobaric exposures in altitude chambers after PB, with and without air breaks, provide the complex protocols from which to model N2 kinetics. DCS survival time for combined control and air breaks were described with an accelerated log logistic model where N2 uptake and elimination before, during, and after the air break was computed with a simple exponential function or a function that changed half-time depending on ambient N2 partial pressure. P1N2-P2 = delta P defined DCS dose for each altitude exposure, where P2 was the test altitude and P1N2 was computed N2 pressure at the beginning of the altitude exposure. The log likelihood (LL) without DCS dose (null model) was -155.6, and improved (best-fit) to -97.2 when dose was defined with a 240 min half-time for both N2 elimination and uptake during the PB. The description of DCS survival time was less precise with asymmetrical N2 kinetics, for example, LL was -98.9 with 240 min half-time elimination and 120 min half-time uptake. The statistical regression described survival time mechanistically linked to symmetrical N2 kinetics during PBs that also included air breaks. The results are data-specific, and additional data may change the conclusion. The regression is useful to compute additional PB time to compensate for an air break in PB within the narrow range of tested conditions.

  5. Energy balance in nanosecond pulse discharges in nitrogen and air

    NASA Astrophysics Data System (ADS)

    Shkurenkov, Ivan; Adamovich, Igor V.

    2016-02-01

    Kinetic modeling is used to analyze energy partition and energy transfer in nanosecond pulse discharges sustained between two spherical electrodes in nitrogen and air. The modeling predictions are compared with previous time-resolved temperature and {{\\text{N}}2}≤ft(X {}1Σ\\text{g}+,v=0-9\\right) vibrational population measurements by picosecond broadband coherent anti-Stokes Raman spectroscopy (CARS) and phase-locked Schlieren imaging. The model shows good agreement with experimental data, reproducing experimental discharge current pulse waveforms, as well as dominant processes of energy transfer in the discharge and the afterglow. Specifically, the results demonstrate that the temperature rise in the plasma occurs in two stages, (i) ‘rapid’ heating on sub-acoustic time scale, dominated by {{\\text{N}}2}≤ft(A {}3Σ\\text{u}+\\right) energy pooling processes, N2(B 3Πg) and N(2P,2D) quenching (in nitrogen), and by quenching of excited electronic states of N2 molecules by O2 (in air), and (ii) ‘slow’ heating due to N2 vibrational relaxation by O atoms (in air), nearly completely missing in nitrogen. Comparison of the model predictions with N2 vibrational level populations confirms that the N2 vibrational temperature rises after the discharge pulse is caused by the ‘downward’ vibrational-vibrational exchange depopulating higher vibrational levels and populating vibrational level v  =  1. The model reproduces temporal dynamics of vibrational level populations and temperature in the discharge and the afterglow, indicating that energy partition among different modes (vibrational, electronic, dissociation, and ionization) is predicted accurately. At the present conditions, energy fraction coupled to the positive column of the discharge filament in air is approximately 50%, with the rest coupled to the cathode layer. Nearly 10% of the total pulse energy is spent on O atom generation, and about 10% is thermalized on a sub-acoustic time scale

  6. Use of a nitrogen-argon plasma to improve adherence of sputtered titanium carbide coatings on steel

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    Friction and wear experiments on 440-C steel surfaces that had been RF-sputtered with titanium carbide when a small percentage of nitrogen was added to the plasma were conducted. X-ray photoelectron spectroscopy and X-ray diffraction were used to analyze the resultant coatings. Results indicate that a small partial pressure of nitrogen (about 0.5%) markedly improves the adherence, friction, and wear properties when compared with coatings applied on sputter-etched oxidized surfaces or in the presence of a small oxygen partial pressure. The improvements are related to the formation of an interface containing a mixture of the nitrides of titanium and iron, which are harder than their corresponding oxides.

  7. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

    PubMed Central

    Karthikeya Sharma, T.

    2014-01-01

    Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied. PMID:26644918

  8. Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

    PubMed

    Karthikeya Sharma, T

    2015-11-01

    Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

  9. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  10. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  11. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  12. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  13. 40 CFR 50.11 - National primary and secondary ambient air quality standards for oxides of nitrogen (with...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). 50.11 Section... quality standards for oxides of nitrogen (with nitrogen dioxide as the indicator). (a) The level of the national primary annual ambient air quality standard for oxides of nitrogen is 53 parts per billion...

  14. Table of Historical Nitrogen Dioxide National Ambient Air Quality Standards (NAAQS)

    EPA Pesticide Factsheets

    See the history of limits to the level of nitrogen dioxide (NO2) in ambient air, set through the NAAQS review and rulemaking process under the Clean Air Act. This includes both primary and secondary standards.

  15. Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Gao, Wei; Xu, Bo; Li, Ying-Ai; Li, Hong-Dong; Gu, Guang-Rui; Yin, Hong

    2016-10-01

    The excellent physical and chemical properties of cubic boron nitride (c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon (100) substrates by radio frequency (RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of H2 gas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51572105, 61504046, and 51272224), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Development and Reform Commission of Jilin Province, China (Grant No. 2015Y050), and the Scientific Research Foundation for the Returned Overseas of Jilin Province, China.

  16. Electrical properties of InGaN thin films grown by RF sputtering at different temperatures, varying nitrogen and argon partial pressure ratios

    NASA Astrophysics Data System (ADS)

    Jakkala, Pratheesh; Kordesch, Martin E.

    2016-10-01

    Indium gallium nitride (InGaN) thin films of varying indium (In) and gallium (Ga) compositions have been fabricated on aluminosilicate glass and silicon (111) substrates using RF magnetron sputtering method at different growth temperatures, varied from 35 °C to 450 °C. Argon (Ar) and nitrogen (N2) are used as Inert and reactive gases respectively. Keeping the total pressure of gas mixture constant, partial pressures of N2 and Ar gases are varied. Ratio of Ar partial pressure to total pressure in the gas mixture is varied from 0 to 0.75. In this study, we present electrical properties of these InGaN thin films. Resistivity values of 2.6 × 10-5 to 1.68 × 10-2 Ω.cm, mobility values of 0.119 to 45.2 cm2/V.s, conductivity values of 0.595 × 103 to 37.3 × 103 mho/cm and bulk carrier concentration values -1020 to -1022/m3 are recorded that are measured through Hall-effect measurement technique.

  17. Effects of nitrogen on the apoptosis of and changes in gene expression in human lymphoma U937 cells exposed to argon-based cold atmospheric pressure plasma.

    PubMed

    Tabuchi, Yoshiaki; Uchiyama, Hidefumi; Zhao, Qing-Li; Yunoki, Tatsuya; Andocs, Gabor; Nojima, Nobuyuki; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Kondo, Takashi

    2016-06-01

    Cold atmospheric pressure plasma (CAP) is known as a source of biologically active agents, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). In the present study, we examined the effects of nitrogen (N2) on the apoptosis of and changes in gene expression in human lymphoma U937 cells exposed to argon (Ar)-CAP. Enormous amounts of hydroxyl (·OH) radicals in aqueous solution were produced using Ar‑CAP generated using a 20 kHz low frequency at 18 kV with a flow rate of 2 l/min. The increase in the levels of ·OH radicals was significantly attenuated by the addition of N2 to Ar gas. On the other hand, the level of total nitrate/nitrite in the supernatant was significantly elevated in the Ar + N2-CAP‑exposed U937 cells. When the cells were exposed to Ar‑CAP, a significant increase in apoptosis was observed, whereas apoptosis was markedly decreased in the cells exposed to Ar + N2-CAP. Microarray and pathway analyses revealed that a newly identified gene network containing a number of heat shock proteins (HSPs), anti-apoptotic genes, was mainly associated with the biological function of the prevention of apoptosis. Quantitative PCR revealed that the expression levels of HSPs were significantly elevated in the cells exposed to Ar + N2-CAP than those exposed to Ar‑CAP. These results indicate that N2 gas in Ar‑CAP modifies the ratio of ROS to RNS, and suppresses the apoptosis induced by Ar‑CAP. The modulation of gaseous conditions in CAP may thus prove to be useful for future clinical applications, such as for switching from a sterilizing mode to cytocidal effect for cancer cells.

  18. Shockwave Interactions with Argon Glow Discharges

    DTIC Science & Technology

    2006-03-01

    SHOCKWAVE INTERACTIONS WITH ARGON GLOW DISCHARGES THESIS Nicholas S. Siefert, Lieutenant, USAF AFIT/GAP/ENP/06-18 DEPARTMENT OF THE AIR FORCE AIR...the United States Government. AFIT/GAP/ENP/06-18 SHOCKWAVE INTERACTIONS WITH ARGON GLOW DISCHARGES THESIS Presented to the Faculty Department of...APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GAP/ENP/06-18 SHOCKWAVE INTERACTIONS WITH ARGON GLOW DISCHARGES Nicholas S. Siefert, BS

  19. Impact of Clean Air Regulations on Nitrogen Fate and Transport in Neuse River Basin

    EPA Science Inventory

    We investigated impacts of Clean Air Act (CAA) nitrogen emissions regulations on the fate and transport of nitrogen for two watersheds in the Neuse River Basin. The Soil and Water Assessment Tool (SWAT) and the Community Multi-Scale Air Quality (CMAQ) models were used. Two scenar...

  20. A parametric experimental investigation of a scramjet nozzle at Mach 6 with Freon and argon or air used for exhaust simulation

    NASA Technical Reports Server (NTRS)

    Cubbage, James M.; Monta, William J.

    1991-01-01

    A parametric experimental investigation of a scramjet nozzle was conducted with a gas mixture used to simulate the scramjet engine exhaust flow at a free-stream Reynolds number of approximately 6.5 x 10(exp 6) per foot. External nozzle surface angles of 16, 20, and 24 deg were tested with a fixed-length ramp and for cowl internal surface angles of 6 and 12 deg. Pressure data on the external nozzle surface were obtained for mixtures of Freon and argon gases with a ratio of specific heats of about 1.23, which matches that of a scramjet exhaust. Forces and moments were determined by integration of the pressure data. Two nozzle configurations were also tested with air used to simulate the exhaust flow. On the external nozzle surface, lift and thrust forces for air exhaust simulation were approximately half of those for Freon-argon exhaust simulation and the pitching moment was approximately a third. These differences were primarily due to the difference in the ratios of specific heats between the two exhaust simulation gases. A 20 deg external surface angle produced the greatest thrust for a 6 deg cowl internal surface angle. A flow fence significantly increased lift and thrust forces over those for the nozzle without a flow fence.

  1. Nitrogen-Helium-Argon and Nitrogen Isotope Relationships in Geothermal Fluids from the Central American Volcanic Arc: Mapping Subducted and Crustal Contributions to Volatile Output

    NASA Astrophysics Data System (ADS)

    Fischer, T.; Sharp, Z.; Hilton, D. R.

    2001-12-01

    Volcanic arcs are locations where elements are recycled from the subducted slab, the mantle wedge and the overlying arc crust to the atmosphere and hydrosphere. A fundamental aim of arc-related studies and the MARGINS initiative is to quantify this flux and compare it with subduction zone parameters, such as sediment compositions and subduction rates. As part of the Central American arc study, we report N2, He, and Ar abundance relationships and N-isotope ratios for 7 volcanic centers in Guatemala to complement on-going studies in Costa Rica (see previous abstract). In Guatemala, the arc crust is thicker and older than in Costa Rica and the entire sedimentary sequence on the down-going plate is likely to contribute to the slab flux. The Guatemalan volcanic centers of Amatitlan-Pacaya, Fuego, Moyuta, Tecuamburro, Amatitlan, Zunil and San Marcos have N2/He ratios ranging from 2200 to 8100, typical for arc-related fluids. N2/Ar ratios (40 - 500) and the high N2/He indicate addition of N2 from subducted sediments or arc crust to a mantle derived component (N2/He < 200). The high N2/He ratios of Guatemala, are in contrast to the mantle-derived N2/He ratios measured at Poas, Costa Rica. Nitrogen isotope ratios for the Guatemalan volcanic centers range from δ 15N = +1.0‰ for San Marcos to +5.8‰ for Fuego (δ 15Nair = 0.0‰ ), indicating a sedimentary nitrogen signature. The mantle-derived N2/He ratio for Poas is consistent with a more mantle-like δ 15N of - 1.0‰ . In Guatemala, the highest 3He/4He ratios (7.6 for Pacaya and 7.3 RA for Fuego) correlate with the lowest N2/He ratios (1500 and 2100) and high δ 15N values (+3.8‰ and +5.8‰ ). Lower 3He/4He ratios for Zunil (4.7 RA) and San Marcos (2.2 RA) correlate with N2/He of 5000 and 6600, and lower δ 15N values of +2.3‰ and +1.0‰ , respectively. These N-He relationships suggest that the nitrogen at Pacaya and Fuego is primarily of subducted organic sedimentary origin, with only minor crustal

  2. Electron Attachment to Pentafluorobenzene, to Oxygen in a Mixture of 90% Argon and 10% Methane, and to Oxygen in Various Polar/nitrogen Mixtures.

    NASA Astrophysics Data System (ADS)

    Metcalfe, Clive, III

    By means of electron swarm experiments, electron attachment to pentafluorobenzene (C(,6)HF(,5)) in nitrogen (N(,2)) and to oxygen (O(,2)) in various gas mixtures has been studied. The variation of the electron attachment rate for C(,6)HF(,5) in N(,2) with the gas pressure and with the mean electron energy was determined. The lifetime of the species C(,6)HF(,5)('-*) against autoionization was deduced and the electron attachment cross section for C(,6)HF(,5) was calculated. The influence of the permanent electric dipole of C(,6)HF(,5) upon the electron attachment process is discussed. Electron attachment to O(,2) in P-10 (90% argon + 10% methane) and in mixtures of various polar molecules with N(,2) was investigated. As a preliminary to these studies electron drift velocities in P-10 and in the various mixtures of polar species with N(,2) were determined. These drift velocities are reported and discussed. The variation of the electron attachment rate for O(,2) in P-10 with the P-10 pressure and the mean electron energy was determined. The attachment rate as a function of mean electron energy was found to possess distinct structure. Models which account for this structure and for the variation of the attachment rate with the P-10 pressure are advanced and the corresponding reaction rate constants are presented. The electron attachment rates for O(,2) in mixtures of N(,2) with 1-butene, dimethyl amine, ammonia, trifluoromethane, and acetaldehyde were measured. Models of the variation of the attachment rate with the concentration of the polar species are advanced and the corresponding reaction rate constants are presented.

  3. 77 FR 9532 - Air Quality Designations for the 2010 Primary Nitrogen Dioxide (NO2

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-17

    ... AGENCY 40 CFR Part 81 RIN-2060-AR06 Air Quality Designations for the 2010 Primary Nitrogen Dioxide (NO 2 ) National Ambient Air Quality Standards AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: This rule establishes air quality designations for all areas in the United States for the...

  4. Pitot survey of exhaust flow field of a 2-D scramjet nozzle at Mach 6 with air or freon and argon used for exhaust simulation

    NASA Technical Reports Server (NTRS)

    Monta, William J.

    1992-01-01

    A pitot-rake survey of the simulated exhaust of a half-span scramjet nozzle model was conducted in the Langley 20-Inch Mach 6 Tunnel to provide an additional data set for computational fluid dynamics (CFD) code comparisons. A wind-tunnel model was tested with a 26-tube pitot rake that could be manually positioned along the mid-semispan plane of the model. The model configuration had an external expansion surface of 20 degrees and an internal cowl expansion of 12 degrees; tests were also performed with a flow fence. Tests were conducted at a free-stream Reynolds number of approximately 6.5 x 10(exp 6) per foot and a model angle of attack of -0.75 degrees. The two exhaust gas mediums that were tested were air and a Freon 12-argon mixture. Each medium was tested at two jet total pressures at approximately 28 and 14 psia. This document presents the flow-field survey results in graphical as well as tabular form, and several observations concerning the results are discussed. The surveys reveal the major expected flow-field characteristics for each test configuration. For a 50-percent freon 12 and 50-percent argon mixture by volume (Fr-Ar), the exhaust jet pressures were slightly higher than those for air. The addition of a flow fence slightly raised the pitot pressure for the Fr-Ar mixture, but it produced little change for air. For the Fr-Ar exhaust, the plume was larger and the region between the shock wave and plume was smaller.

  5. Defining Nitrogen Kinetics for Air Break in Prebreath

    NASA Technical Reports Server (NTRS)

    Conkin, Johnny

    2010-01-01

    Actual tissue nitrogen (N2) kinetics are complex; the uptake and elimination is often approximated with a single half-time compartment in statistical descriptions of denitrogenation [prebreathe(PB)] protocols. Air breaks during PB complicate N2 kinetics. A comparison of symmetrical versus asymmetrical N2 kinetics was performed using the time to onset of hypobaric decompression sickness (DCS) as a surrogate for actual venous N2 tension. METHODS: Published results of 12 tests involving 179 hypobaric exposures in altitude chambers after PB, with and without airbreaks, provide the complex protocols from which to model N2 kinetics. DCS survival time for combined control and airbreaks were described with an accelerated log logistic model where N2 uptake and elimination before, during, and after the airbreak was computed with a simple exponential function or a function that changed half-time depending on ambient N2 partial pressure. P1N2-P2 = (Delta)P defined decompression dose for each altitude exposure, where P2 was the test altitude and P1N2 was computed N2 pressure at the beginning of the altitude exposure. RESULTS: The log likelihood (LL) without decompression dose (null model) was -155.6, and improved (best-fit) to -97.2 when dose was defined with a 240 min half-time for both N2 elimination and uptake during the PB. The description of DCS survival time was less precise with asymmetrical N2 kinetics, for example, LL was -98.9 with 240 min half-time elimination and 120 min half-time uptake. CONCLUSION: The statistical regression described survival time mechanistically linked to symmetrical N2 kinetics during PBs that also included airbreaks. The results are data-specific, and additional data may change the conclusion. The regression is useful to compute additional PB time to compensate for an airbreak in PB within the narrow range of tested conditions.

  6. 78 FR 47253 - Approval and Promulgation of Air Quality Implementation Plans; Maine; Oxides of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-05

    ... Nitrogen Exemption and Ozone Transport Region Restructuring AGENCY: Environmental Protection Agency (EPA... exemption from the nitrogen oxides (NO X ) emissions control requirements of the Clean Air Act (CAA or Act... from Stephen D. Page, Director, OAQPS, dated January 14, 2005, entitled ``Guidance on Limiting...

  7. Carbon dioxide, argon, nitrogen and methane clathrate hydrates: Thermodynamic modelling, investigation of their stability in Martian atmospheric conditions and variability of methane trapping

    NASA Astrophysics Data System (ADS)

    Herri, Jean-Michel; Chassefière, Eric

    2012-12-01

    This paper deals with the stability of clahtrate hydrates at low temperature and low pressure in the conditions prevailing in the atmosphere and at the surface of Mars. We fit the classical van der Waals model to compare deviation from experimental results published in the literature. It appears to be acceptable and allows to simulating a Martian gas, CO2 dominated (95.3%) plus nitrogen (2.7%) and argon (2%). The hydrate is a CO2-based hydrate which is unstable during Mars’ summer and stable during Mars’ winter. The proportion of methane in the hydrate is estimated and is found to be from one tenth to one third of the composition of the gas phase. The proportion depends on the crystallographic structure which is assumed to be formed. In fact, both the structure I and II appear to be stable in the conditions of Mars’ winter. The consequences of these results on our understanding of the atmospheric cycle of Martian methane are drawn and analyzed. We propose upper limits on (i) the seasonal variation of methane due to a hypothesized alternate formation of CO2/N2/Ar/CH4 hydrates on the seasonal polar caps, and (ii) on the lifetime of atmospheric methane with respect to an hypothesized continuous trapping under hydrate form on the south polar cap. We show that these mechanisms have only small effects, and cannot play a significant role in the dynamics of methane in present Mars’ atmosphere. Hypothesized clathrate hydrates trapped in the permanent south polar cap could include methane in relative proportions between 0.1 and 0.4 times the average global atmospheric ratio. Searching for the spectral signatures of clathrate hydrates on the caps and, if detectable, of inhomogeneities of the CH4 mixing ratio in possible local atmospheric plumes forming during the sublimation of polar hydrate pockets in spectroscopic data from existing (Mars Express, MRO) and future (TGO-Exomars) missions is an interesting challenge of Mars science and astrobiology.

  8. 76 FR 48073 - Public Hearing for Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-08

    ... for Oxides of Nitrogen and Sulfur AGENCY: Environmental Protection Agency (EPA). ACTION: Announcement... titled ``Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Sulfur'' which was... ``Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Sulfur'' proposed rule should...

  9. Impact of Clean Air Act Regulations on Nitrogen Fate and Transport in the Neuse River Basin

    NASA Astrophysics Data System (ADS)

    Gabriel, M. C.; Knightes, C. D.; Dennis, R. L.; Cooter, E. J.

    2012-12-01

    This study investigated impacts of Clean Air Act Amendment (CAAA) NOx emissions regulations on the fate and transport of nitrogen for two watersheds in the Neuse River Basin, North Carolina, USA from 1990 to 2020. The Soil and Water Assessment Tool (SWAT) and the Community Multi-scale Air Quality (CMAQ) modeling system were used. CMAQ simulated atmospheric chemical transport and nitrogen deposition. This data was entered into SWAT which simulated watershed hydrology and water quality. Two cases were investigated: one that incorporates CAAA regulatory emissions controls in CMAQ simulation (with) and a second case that does not (without). SWAT model results forecasted a 70% decrease in inorganic nitrogen discharge from the Little River watershed and a 50% decrease for the Nahunta watershed by 2020 under the emission control (with) scenario. Denitrification and plant nitrogen uptake played important roles in nitrogen discharge from each watershed. The nitrogen discharge response time following a change in atmospheric nitrogen deposition was 4 years for the Nahunta watershed and 2 years for the Little River watershed. The longer response time for Nahunta is primarily due to a higher percentage of soybean land cover (22.5% [Nahunta]; 1.6% [Little River]). Agricultural land covers had varied nitrogen response times to changes in atmospheric deposition, particularly for soybean, hay and corn. The studied watersheds retained >80% of all nitrogen delivered by agriculture fertilization, biological fixation and atmospheric deposition.

  10. Effects of Air/Nitrogen Cure on An Acetylene Terminated Quinoxaline Thermoset System

    DTIC Science & Technology

    1981-06-01

    AFWAL-TR-81-401 2 FILE Copy EFFECTS OF AIR/NITROGEN CURE ON AN ACETYLENE TERMINATED QUINOXALINE THERMOSET SYSTEM Polymer Branch Nonmetallic Materials...RECIPIENT’S CATALOG NUMBER AFWAL-TR- 81-4012 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED Effects of Air/Nitrogen Cure on an Acetylene ...81-4012 SECTION I INTRODUCTION The Air Force has an interest in the development of acetylene - terminated (AT) resins as a new technology to form high

  11. GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Baron, A. K.; Peller, I. C.

    1975-01-01

    A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

  12. Effect of fuel-air-ratio nonuniformity on emissions of nitrogen oxides

    NASA Technical Reports Server (NTRS)

    Lyons, V. J.

    1981-01-01

    The inlet fuel-air ratio nonuniformity is studied to deterine how nitrogen oxide (NOx) emissions are affected. An increase in NOx emissions with increased fuel-air ratio nonuniformity for average equivalence ratios less than 0.7 and a decrease in NOx emissions for average equivalence ratios near stoichiometric is predicted. The degree of uniformityy of fuel-air ratio profiles that is necessary to achieve NOx emissions goals for actual engines that use lean, premixed, prevaporized combustion systems is determined.

  13. 40 CFR Appendix S to Part 50 - Interpretation of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Ambient Air Quality Standards for Oxides of Nitrogen (Nitrogen Dioxide) S Appendix S to Part 50 Protection... SECONDARY AMBIENT AIR QUALITY STANDARDS Pt. 50, App. S Appendix S to Part 50—Interpretation of the Primary... be submitted to EPA's Air Quality System (AQS), or otherwise available to EPA, meeting...

  14. Technical note: Air compared to nitrogen as nebulizing and drying gases for electrospray ionization mass spectrometry.

    PubMed

    Mielczarek, P; Silberring, J; Smoluch, M

    2016-01-01

    In the present study we tested the application of compressed air instead of pure nitrogen as the nebulizing and drying gas, and its influence on the quality of electrospray ionization (ESI) mass spectra. The intensities of the signals corresponding to protonated molecules were significantly (twice) higher when air was used. Inspection of signal-to-noise (S/N) ratios revealed that, in both cases, sensitivity was comparable. A higher ion abundance after the application of compressed air was followed by a higher background. Another potential risk of using air in the ESI source is the possibility for sample oxidation due to the presence of oxygen. To test this, we selected five easily oxidizing compounds to verify their susceptibility to oxidation. In particular, the presence of methionine was of interest. For all the compounds studied, no oxidation was observed. Amodiaquine oxidizes spontaneously in water solutions and its oxidized form can be detected a few hours after preparation. Direct comparison of the spectra where nitrogen was used with the corresponding spectra obtained when air was applied did not show significant differences. The only distinction was slightly different patterns of adducts when air was used. The difference concerns acetonitrile, which forms higher signals when air is the nebulizing gas. It is also important that the replacement of nitrogen with air does not affect quantitative data. The prepared calibration curves also visualize an intensity twice as high (independent of concentration within tested range) of the signal where air was applied. We have used our system continuously for three months with air as the nebulizing and drying gas and have not noticed any unexpected signal deterioration caused by additional source contamination from the air. Moreover, compressed air is much cheaper and easily available using oil-free compressors or pumps.

  15. “Exchanges of Aggregate Air Nitrogen Emissions and Watershed Nitrogen Loads”

    EPA Science Inventory

    An approach has been developed to define transfer coefficients that can be used to convert changes in air emissions to changes in air deposition and subsequently to changes in loads delivered to the Bay. This approach uses a special CMAQ version that quantitatively attributes wa...

  16. Non-dispersive atomic-fluorescence spectrometry of trace amounts of bismuth by introduction of its gaseous hydride into a premixed argon (entrained air)-hydrogen flame.

    PubMed

    Kobayashi, S; Nakahara, T; Musha, S

    1979-10-01

    A method has been developed for the determination of bismuth by generation of its gaseous hydride and introduction of the hydride into a premixed argon (entrained air)-hydrogen flame, the atomic-fluorescence lines from which are all detected by use of a non-dispersive system. The detection limit is 5 pg/ml, or 0.1 ng of bismuth, but the reagent blank found in a 20-ml sample volume was approximately 2 ng of bismuth. Analytical working curves obtained by measuring peak-heights and integrated peak-areas of the signals are linear over a range of about four orders of magnitude from the detection limit. Perchloric, phosphoric and sulphuric acids up to 2.0M concentration give no interference, but nitric acid gives slight depression of the signal. The presence of silver, gold, nickel, palladium, platinum, selenium and tellurium in 1000-fold ratio to bismuth causes pronounced depression of the signal, whereas mercury and tin slightly enhance the atomic-fluorescence signal. The method has been applied to the determination of bismuth in aluminium-base alloys and sulphide ores with use of the standard additions method. The results are in good agreement with those obtained by flame atomic-absorption spectrometry and optical emission spectrometry with an inductively coupled plasma.

  17. Implications of Nitrogen-Climate Interactions for Ambient Air Pollution and Human Health

    NASA Astrophysics Data System (ADS)

    Haeuber, R.; Peel, J. L.; Garcia, V.; Neas, L.; Russell, A. G.

    2011-12-01

    Nitrogen oxides (NOX) are important components of ambient and indoor air pollution and are emitted from a range of combustion sources, including on-road mobile sources, electric power generators, and non-road mobile sources. While anthropogenic sources dominate, NOX is also formed by lightning and wildland fires and is emitted by soil. Reduced nitrogen (e.g., ammonia, NH3) is also emitted by various sources, including fertilizer application and animal waste decomposition. NOX, ozone and PM2.5 pollution related to atmospheric emissions of nitrogen and other pollutants can cause premature death and a variety of serious health effects. Climate change is expected to impact how nitrogen-related pollutants affect human health. For example, changes in temperature and precipitation patterns are projected to both lengthen the ozone season and intensify high ozone episodes in some areas. Other climate-related changes may increase the atmospheric release of nitrogen compounds through impacts on wildfire regimes, soil emissions, and biogenic emissions from terrestrial ecosystems. This session will examine the potential human health implications of climate change and nitrogen cycle interactions related to ambient air pollution.

  18. A Passive Sampler for Determination of Nitrogen Dioxide in Ambient Air

    ERIC Educational Resources Information Center

    Xiao, Dan; Lin, Lianzhi; Yuan, Hongyan; Choi, Martin M. F.; Chan, Winghong

    2005-01-01

    A passive sampler that provides a convenient, simple, and fast method for nitrogen dioxide determination is proposed. The experiment can be modified for determinations of other air pollutants like formaldehyde and sulfur dioxide for hands-on experience for students studying environmental pollution problems.

  19. 76 FR 52283 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-22

    ...; Control of Nitrogen Oxides Emissions From Glass Melting Furnaces AGENCY: Environmental Protection Agency... (NO X ) emissions from glass melting furnaces. EPA is approving these revisions to reduce NO X emissions from glass melting furnaces in accordance with the requirements of the Clean Air Act (CAA)....

  20. 76 FR 34021 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-10

    ...; Control of Nitrogen Oxides Emissions From Glass Melting Furnaces AGENCY: Environmental Protection Agency... oxide (NO X ) emissions from glass melting furnaces. This action is being taken under the Clean Air Act... revision to its State Implementation Plan for the control of NO X from glass melting furnaces....

  1. 76 FR 29180 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-20

    ...; Control of Nitrogen Oxides Emissions From Portland Cement Kilns AGENCY: Environmental Protection Agency... oxide (NO X ) emissions from Portland cement kilns. This action is being taken under the Clean Air Act... revision to its State Implementation Plan for the control of NO X from Portland cement kilns. I....

  2. 76 FR 42558 - Approval and Promulgation of Air Quality Implementation Plans; Pennsylvania; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-19

    ...; Control of Nitrogen Oxides Emissions from Portland Cement Kilns AGENCY: Environmental Protection Agency... (NO X ) emissions from Portland cement kilns. EPA is approving these revisions to reduce emissions from Portland cement kilns in accordance with the requirements of the Clean Air Act (CAA)....

  3. Impact of Clean Air Act Regulations on Nitrogen Fate and Transport in Neuse River Basin

    EPA Science Inventory

    This study investigated impacts of Clean Air Act Amendment (CAAA) NOx emissions regulations on the fate and transport of nitrogen for two watersheds in the Neuse River Basin, North Carolina, USA from 1990 to 2020. The Soil and Water Assessment Tool (SWAT) and the Community Multi-...

  4. 75 FR 32858 - Approval and Promulgation of Air Quality Implementation Plans; Delaware; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-10

    ... From the Federal Register Online via the Government Publishing Office ] ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 Approval and Promulgation of Air Quality Implementation Plans; Delaware; Control of Nitrogen Oxide Emissions From Industrial Boilers and Process Heaters at Petroleum Refineries Correction...

  5. Chapter 7: Impact of Nitrogen and Climate Change Interactions on Ambient Air Pollution and Human Health

    EPA Science Inventory

    Nitrogen oxides (NOX) are important components of ambient and indoor air pollution and are emitted from a range of combustion sources, including on-road mobile sources, electric power generators, and non-road mobile sources. While anthropogenic sources dominate, NOX is also forme...

  6. Observation of nuclear spin species conversion inside the 1593 cm -1 structure of H 2O trapped in argon matrices: Nitrogen impurities and the H 2O:N 2 complex

    NASA Astrophysics Data System (ADS)

    Pardanaud, Cédric; Vasserot, Anne-Marie; Michaut, Xavier; Abouaf-Marguin, L.

    2008-02-01

    We have investigated, at high resolution (0.03 cm -1), the 1593 cm -1 structure observed in the IR absorption spectrum of water trapped in solid argon doped with nitrogen. It exhibits a doublet at 1592.59 ± 0.05 and 1593.08 ± 0.05 cm -1 and a line centered at 1592.93 ± 0.05 cm -1. The central component, which increases irreversibly upon annealing and when the concentration is increased, is due to the proton acceptor submolecule of the H 2O dimer, as mentioned in the literature. The doublet is assigned to the H 2O:N 2 complex. After a fast cooling of the sample from 20 to 4 K, the low frequency line of the doublet decreases with time and the high frequency one increases, the total integrated absorption increasing slightly. The ratio of the integrated intensities between the low frequency component and the high frequency one reaches a constant limit of 0.5 ± 0.1 at infinite time. This time behavior, perfectly exponential with a time constant τ of about 680 min, is reproducible. As the nitrogen molecule cannot rotate in an argon substitutional site, and as the H 2O submolecule seems to preserve somewhat its identity, this is interpreted as nuclear spin species conversion between ortho and para states of the H 2O submolecule within the complex. The order of magnitude of the energy difference between the ortho and para lowest levels, about 5 cm -1, is too weak to imply any, even very hindered, rotational motion of H 2O, but it could be the energy range of a tunneling effect. When the temperature is increased, the two components coalesce at 25 K into a single symmetrical line pointing at 1593.3 cm -1 and the conversion time shortens dramatically. An Arrhenius plot leads to a weak activation energy of the conversion process (about 30 cm -1). A possible geometry of the complex in solid argon, different from the gas phase one, is proposed.

  7. Inorganic nitrogenous air pollutants, atmospheric nitrogen deposition and their potential ecological impacts in remote areas of western North America (Invited)

    NASA Astrophysics Data System (ADS)

    Bytnerowicz, A.; Fenn, M. E.; Fraczek, W.; Johnson, R.; Allen, E. B.

    2013-12-01

    Dry deposition of gaseous inorganic nitrogenous (N) air pollutants plays an important role in total atmospheric N deposition and its ecological effects in the arid and semi-arid ecosystems. Passive samplers and denuder/ filter pack systems have been used for determining ambient concentrations of ammonia (NH3), nitric oxide (NO), nitrogen dioxide (NO2), and nitric acid vapor (HNO3) in the topographically complex remote areas of the western United States and Canada. Concentrations of the measured pollutants varied significantly between the monitoring areas. Highest NH3, NO2 and HNO3 levels occurred in southern California areas downwind of the Los Angeles Basin and in the western Sierra Nevada impacted by emissions from the California Central Valley and the San Francisco Bay area. Strong spatial gradients of N pollutants were also present in southeastern Alaska due to cruise ship emissions and in the Athabasca Oil Sands Region in Canada affected by oil exploitation. Distribution of these pollutants has been depicted by maps generated by several geostatistical methodologies within the ArcGIS Geostatistical Analyst (ESRI, USA). Such maps help to understand spatial and temporal changes of air pollutants caused by various anthropogenic activities and locally-generated vs. long range-transported air pollutants. Pollution distribution maps for individual N species and gaseous inorganic reactive nitrogen (Nr) have been developed for the southern portion of the Sierra Nevada, Lake Tahoe Basin, San Bernardino Mountains, Joshua Tree National Park and the Athabasca Oil Sands Region. The N air pollution data have been utilized for estimates of dry and total N deposition by a GIS-based inferential method specifically developed for understanding potential ecological impacts in arid and semi-arid areas. The method is based on spatial and temporal distribution of concentrations of major drivers of N dry deposition, their surface deposition velocities and stomatal conductance values

  8. Ecological effects of nitrogen and sulfur air pollution in the US: what do we know?

    USGS Publications Warehouse

    Greaver, Tara L.; Sullivan, Timothy J.; Herrick, Jeffrey D.; Barber, Mary C.; Baron, Jill S.; Cosby, Bernard J.; Deerhake, Marion E.; Dennis, Robin L.; Dubois, Jean-Jacque B.; Goodale, Christine L.; Herlihy, Alan T.; Lawrence, Gregory B.; Liu, Lingli; Lynch, Jason A.; Novak, Kristopher J.

    2012-01-01

    Four decades after the passage of the US Clean Air Act, air-quality standards are set to protect ecosystems from damage caused by gas-phase nitrogen (N) and sulfur (S) compounds, but not from the deposition of these air pollutants to land and water. Here, we synthesize recent scientific literature on the ecological effects of N and S air pollution in the US. Deposition of N and S is the main driver of ecosystem acidification and contributes to nutrient enrichment in many natural systems. Although surface-water acidification has decreased in the US since 1990, it remains a problem in many regions. Perturbations to ecosystems caused by the nutrient effects of N deposition continue to emerge, although gas-phase concentrations are generally not high enough to cause phytotoxicity. In all, there is overwhelming evidence of a broad range of damaging effects to ecosystems in the US under current air quality conditions.

  9. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    PubMed Central

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  10. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region.

    PubMed

    Oikawa, P Y; Ge, C; Wang, J; Eberwein, J R; Liang, L L; Allsman, L A; Grantz, D A; Jenerette, G D

    2015-11-10

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  11. On the dependence of structural and sensing properties of sputtered MoO3 thin films on argon gas flow

    NASA Astrophysics Data System (ADS)

    Khojier, K.; Savaloni, H.; Zolghadr, S.

    2014-11-01

    Nitrogen and carbon oxides (CO, NO and NO2), released from combustion facilities and automobiles, are known to be extremely harmful to the human body and also are the main cause of air pollution. Therefore, effective methods to monitor and suppress the carbon and nitrogen oxides have been highly demanded for atmospheric environmental measurements and controls. It is known that molybdenum oxide (MoO3) can be a good semiconductor material for use as a gas sensor in monitoring CO, NO and NO2. In this paper we report the structural characteristics and sensing properties of the sputtered MoO3 thin films as a function of argon gas flow. MoO3 thin films were deposited by DC reactive magnetron sputtering technique on glass substrates at different argon gas flows in the range of 5-20 sccm. X-ray diffraction (XRD) analysis was used for studying crystallographic structure. XRD results showed that all of our films were of polycrystalline structure and of α-MoO3 stable orthorhombic phase. Results also showed that crystallite size increases while compressive nano-strain in the structure of the films decreases with increasing the argon gas flow. Atomic force microscope and the field emission scanning electron microscope studies showed granular structures for all samples, which increased in size consistent with the XRD results, with argon gas flow, while the surface roughness of the films also increased with argon gas flow. Chemical composition study showed optimum reaction between oxygen and molybdenum atoms for films produced at 15 sccm flow of argon gas. The electrical response of samples was measured in the vacuum and the CO environments in the temperature range of 150-350 K. All samples showed Ohmic behavior and the electrical resistances of the films measured in the CO environment were lower than those measured in vacuum. This study showed that the sensing ability of MoO3 for CO improves with increasing the argon gas flow.

  12. Determination of nitrogen dioxide in ambient air employing diffuse reflectance Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Verma, Santosh Kumar; Deb, Manas Kanti; Verma, Devsharan

    2008-10-01

    This paper presents the development of a simple and precise analytical method for the determination of nitrogen dioxide in ambient air. In this method nitrogen dioxide is determined in the form of nitrite. The determination of nitrogen dioxide needs no reagents except for a solution of sodium hydroxide mixed with sodium arsenite (NaOH-Na 2As 2O 3) which is used as an absorbing reagent for trapping the nitrogen dioxide from the atmosphere in the form of nitrite, i.e., a prior analysis step. The determination of submicrogram levels of nitrogen dioxide is based on the selection of a strong and sharp quantitative analytical peak at 1380 cm - 1 using diffuse reflectance infrared spectroscopy (DRS-FTIR). The limit of detection (LOD) and the limit of quantification of the method are found to be 0.008 μg g - 1 NO 2- and 0.05 μg g - 1 NO 2-, respectively. The precision in terms of standard deviation and relative standard deviation value at a level of 2 μg NO 2- / 0.1 g KBr for n = 10 is found to be 0.036 μg NO 2- and 1.8%, respectively. The relative standard deviation ( n = 10) for the determination of nitrogen dioxide in ambient air was observed to be in the range 2.6-3.8%. The method proposed is time-saving and eliminates the slow and cumbersome steps of pH maintenance of the reaction mixture and color formation of the EPA recommended spectrophotometric and other methods for quantitative determination of nitrogen dioxide.

  13. Nitrogen

    USGS Publications Warehouse

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  14. Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission

    SciTech Connect

    Weiland, N.T.; Chen, R.-H.; Strakey, P.A.

    2007-10-01

    Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine program’s goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.

  15. Effects of argon enriched low-oxygen atmospheres and of high-oxygen atmospheres on the kinetics of polyphenoloxidase (PPO).

    PubMed

    O'Beirne, David; Murphy, Eileen; Ni Eidhin, Deirdre

    2011-01-01

    The reported benefits of enrichment of air atmospheres with argon or oxygen for control of enzymatic browning were investigated by determining the effects of these atmospheres on PPO kinetics. Kinetics of purified apple PPO and a commercially available mushroom PPO were studied in an in vitro model system. Enrichment with argon produced greater inhibitory effects than the current industry practice of enrichment with nitrogen. Km(app) values (mM) for apple PPO in 3%O(2)/97%Ar, 3%O(2)/97%N(2), and air, were 133, 87, and 48, respectively. The data indicate that inhibition by both gases is competitive, and also support the hypothesis that the greater inhibitory effect of argon was proportional to the size of the Van der Waals radius of argon against nitrogen (1.91 Å against 1.54 Å). Much smaller inhibitory effects were observed in the presence of 80% O(2) (Km(app) 57 mM), and the nature of this inhibition was less clear. The results suggest that the benefits of argon enrichment may be relatively small, and may require critical enzyme, substrate, and gas levels to be successful. However, these benefits may be exploitable commercially in some fresh-cut products, and may allow less anoxic atmospheres to be used. Practical Application: Control of enzymatic browning without sulfites continues to be a challenge in some fresh-cut products. While sporadic benefits of these atmospheres in control of enzymatic browning have been reported, results have been inconsistent in commercial practice. The results suggest that the benefits of argon enrichment may be relatively small, and may require critical enzyme, substrate, and gas levels to be successful. However, these benefits may be exploitable commercially in some fresh-cut products, and allow less anoxic atmospheres to be used.

  16. Analysis of the 222Rn concentration in argon and a purification technique for gaseous and liquid argon.

    PubMed

    Simgen, H; Zuzel, G

    2009-05-01

    We present an investigation of the (222)Rn concentration in argon with ultra-low background proportional counters. Argon purification tests by means of cryo-adsorption of radon on activated carbon were performed. For gaseous argon the purification process was found to be very efficient. Also in liquid phase the (222)Rn concentration could be reduced significantly, however, the efficiency is lower than in the gas phase. We also have analyzed the initial (222)Rn concentrations in commercial liquid argon. It was found to be significantly higher than in liquid nitrogen.

  17. Evaluation of analytical methodology for hydrocarbons in high pressure air and nitrogen systems. [evaluation of methodology

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Samples of liquid oxygen, high pressure nitrogen, low pressure nitrogen, and missile grade air were studied to determine the hydrocarbon concentrations. Concentration of the samples was achieved by adsorption on a molecular sieve and activated charcoal. The trapped hydrocarbons were then desorbed and transferred to an analytical column in a gas chromatograph. The sensitivity of the method depends on the volume of gas passed through the adsorbent tubes. The value of the method was verified through recoverability and reproducibility studies. The use of this method enables LOX, GN2, and missile grade air systems to be routinely monitored to determine low level increases in specific hydrocarbon concentration that could lead to potentially hazardous conditions.

  18. Measurements of the total energy lost per electron-ion pair lost in low-pressure inductive argon, helium, oxygen and nitrogen discharge

    NASA Astrophysics Data System (ADS)

    Lee, Young-Kwang; Ku, Ju-Hwan; Chung, Chin-Wook

    2011-02-01

    Experimental measurements of the total energy lost per electron-ion pair lost, ɛT, were performed in a low-pressure inductive atomic gases (Ar, He) and molecular gases (O2, N2) discharge. The value of ɛT was determined from a power balance based on the electropositive global (volume-averaged) model. A floating harmonic method was employed to measure ion fluxes and electron temperatures at the discharge wall. In the pressure range 5-50 mTorr, it was found that the measured ɛT ranged from about 70 to 150 V for atomic gases, but from about 180 to 1300 V for molecular gases. This difference between atomic and molecular discharge is caused by additional collisional energy losses of molecular gases. For argon discharge, the stepwise ionization effect on ɛT was observed at relatively high pressures. For different gases, the measured ɛT was evaluated with respect to the electron temperature, and then compared with the calculation results, which were derived from collisional and kinetic energy loss. The measured ɛT and their calculations showed reasonable agreement.

  19. Linking agricultural crop management and air quality models for regional to national-scale nitrogen assessments

    NASA Astrophysics Data System (ADS)

    Cooter, E. J.; Bash, J. O.; Benson, V.; Ran, L.

    2012-05-01

    While nitrogen (N) is an essential element for life, human population growth and demands for energy, transportation and food can lead to excess nitrogen in the environment. A modeling framework is described and implemented, to promote a more integrated, process-based and system-level approach to the estimation of ammonia (NH3) emissions resulting from the application of inorganic nitrogen fertilizers to agricultural soils in the United States. The United States Department of Agriculture (USDA) Environmental Policy Integrated Climate (EPIC) model is used to simulate plant demand-driven fertilizer applications to commercial cropland throughout the continental US. This information is coupled with a process-based air quality model to produce continental-scale NH3 emission estimates. Regional cropland NH3 emissions are driven by the timing and amount of fertilizer applied, local meteorology, and ambient air concentrations. An evaluation of EPIC-simulated crop management activities associated with fertilizer application at planting compared with similar USDA state-level event estimates shows temporally progressive spatial patterns that agree well with one another. EPIC annual inorganic fertilizer application amounts also agree well with reported spatial patterns produced by others, but domain-wide the EPIC values are biased about 6 % low. Preliminary application of the integrated fertilizer application and air quality modeling system produces a modified geospatial pattern of seasonal NH3 emissions that improves current simulations of observed atmospheric nitrate concentrations. This modeling framework provides a more dynamic, flexible, and spatially and temporally resolved estimate of NH3 emissions than previous factor-based NH3 inventories, and will facilitate evaluation of alternative nitrogen and air quality policy and adaptation strategies associated with future climate and land use changes.

  20. Linking agricultural crop management and air quality models for regional to national-scale nitrogen assessments

    NASA Astrophysics Data System (ADS)

    Cooter, E. J.; Bash, J. O.; Benson, V.; Ran, L.

    2012-10-01

    While nitrogen (N) is an essential element for life, human population growth and demands for energy, transportation and food can lead to excess nitrogen in the environment. A modeling framework is described and implemented to promote a more integrated, process-based and system-level approach to the estimation of ammonia (NH3) emissions which result from the application of inorganic nitrogen fertilizers to agricultural soils in the United States. The United States Department of Agriculture (USDA) Environmental Policy Integrated Climate (EPIC) model is used to simulate plant demand-driven fertilizer applications to commercial cropland throughout the continental US. This information is coupled with a process-based air quality model to produce continental-scale NH3 emission estimates. Regional cropland NH3 emissions are driven by the timing and amount of inorganic NH3 fertilizer applied, soil processes, local meteorology, and ambient air concentrations. Initial fertilizer application often occurs when crops are planted. A state-level evaluation of EPIC-simulated, cumulative planted area compares well with similar USDA reported estimates. EPIC-annual, inorganic fertilizer application amounts also agree well with reported spatial patterns produced by others, but domain-wide the EPIC values are biased about 6% low. Preliminary application of the integrated fertilizer application and air quality modeling system produces a modified geospatial pattern of seasonal NH3 emissions that improves current simulations of observed atmospheric particle nitrate concentrations. This modeling framework provides a more dynamic, flexible, and spatially and temporally resolved estimate of NH3 emissions than previous factor-based NH3 inventories, and will facilitate evaluation of alternative nitrogen and air quality policy and adaptation strategies associated with future climate and land use changes.

  1. Comparison of silver nanoparticles stored under air or argon with respect to the induction of intracellular free radicals and toxic effects toward keratinocytes.

    PubMed

    Ahlberg, Sebastian; Meinke, Martina C; Werner, Luise; Epple, Matthias; Diendorf, Joerg; Blume-Peytavi, Ulrike; Lademann, Juergen; Vogt, Annika; Rancan, Fiorenza

    2014-11-01

    Bacterial infections decreased considerably after the discovery of antibiotics. Nevertheless, because of the rising rate of infections caused by antibiotic-resistant bacteria strains, the search for new bactericidal agents has again become a crucial topic in clinical medicine. Silver nanoparticles (AgNP) have a huge potential in dermatology and wound care management because of their ability to release silver ions (Ag(+) ions) in a prolonged and sustained way. However, negative effects of silver on the patient's cells should not be underestimated. Furthermore, it has been controversially discussed whether AgNP are responsible for nanoparticle-specific outcomes or not. In this study, we investigated the effects of AgNP on human skin keratinocytes (HaCaT) in order to better understand the mechanisms of cytotoxicity and to improve the use of this highly reactive biocide in wound healing. We found that most of the cells with internalized AgNP displayed the typical morphological signs of apoptosis. The cell viability assay (XTT) showed concentration-dependent toxic effects of the AgNP toward HaCaT cells. The generation of reactive oxygen species (ROS) induced by AgNP was investigated in cell suspensions by means of electron paramagnetic resonance (EPR) spectroscopy. In order to distinguish between the effects of Ag(+) ions released during AgNP storage and those of Ag(+) ions released after nanoparticle application, we compared AgNP stored under air (O2) with AgNP stored under argon (Ar). Dispersions of AgNP stored under Ar have a low content of Ag(+) ions because of the absence of oxygen which is needed for oxidative dissolution. The results show that Ag(+) ions released during particle storage are responsible for most of the ROS produced during 1h incubation with the cells. AgNP (Ar) also induced intracellular ROS but to a much smaller extent compared to AgNP (O2). These findings highlight the complexity of experiments to assess the toxicity of AgNP and suggest the

  2. Performance analysis of small capacity liquid nitrogen generator based on Joule-Thomson refrigerator coupled with air separation membrane

    NASA Astrophysics Data System (ADS)

    Piotrowska-Hajnus, Agnieszka; Chorowski, Maciej

    2012-06-01

    Joule - Thomson small capacity refrigerators supplied with gas mixture are studied theoretically and experimentally for a variety of applications. They can be especially promising when coupled with membrane air separators. We present liquid nitrogen generation system based on Joule - Thomson cooler joined with air separation membrane. Hollow fiber membrane is used for nitrogen separation from compressed and purified atmospheric air. Joule-Thomson refrigerator operates with a dedicated nitrogen - hydrocarbons mixture and provides a cooling power used for the separated nitrogen liquefaction. Special attention has been paid to a heat exchanger coupling the Joule- Thomson refrigerator with the membrane air separator. This paper describes the system design, the procedure of its working parameters optimization and tests results.

  3. 75 FR 11877 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-12

    ... of Sulfur AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability of draft... Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: First External Review Draft... (welfare-based) NAAQS for oxides of nitrogen (NO X ) and oxides of sulfur (SO X ). Because NO X , SO...

  4. 75 FR 57463 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... of Sulfur AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability of draft... Ambient Air Quality Standards for Oxides of Nitrogen and Oxides of Sulfur: Second External Review Draft... for oxides of nitrogen (NO X ) and oxides of sulfur (SO X ). Because NO X , SO X , and...

  5. Passive dosimeters for nitrogen dioxide in personal/indoor air sampling: A review

    PubMed Central

    Yu, Chang Ho; Morandi, Maria T.; Weisel, Clifford P.

    2015-01-01

    Accurate measurement of nitrogen dioxide concentrations in both outdoor and indoor environments, including personal exposures, is a fundamental step for linking atmospheric nitrogen dioxide levels to potential health and ecological effects. The measurement has been conducted generally in two ways: active (pumped) sampling and passive (diffusive) sampling. Diffusion samplers, initially developed and used for workplace air monitoring, have been found to be useful and cost-effective alternatives to conventional pumped samplers for monitoring ambient, indoor and personal exposures at the lower concentrations found in environmental settings. Since the 1970s, passive samplers have been deployed for ambient air monitoring in urban and rural sites, and to determine personal and indoor exposure to NO2. This article reviews the development of NO2 passive samplers, the sampling characteristics of passive samplers currently available, and their application in ambient and indoor air monitoring and personal exposure studies. The limitations and advantages of the various passive sampler geometries (i.e., tube, badge, and radial type) are also discussed. This review provides researchers and risk assessors with practical information about NO2 passive samplers, especially useful when designing field sampling strategies for exposure and indoor/outdoor air sampling. PMID:18446185

  6. Decomposition of nitric oxide in a hot nitrogen stream to synthesize air for hypersonic wind tunnel combustion testing

    NASA Technical Reports Server (NTRS)

    Zumdieck, J. F.; Zlatarich, S. A.

    1974-01-01

    A clean source of high enthalpy air was obtained from the exothermic decomposition of nitric oxide in the presence of strongly heated nitrogen. A nitric oxide jet was introduced into a confined coaxial nitrogen stream. Measurements were made of the extent of mixing and reaction. Experimental results are compared with one- and two-dimensional chemical kinetics computations. Both analyses predict much lower reactivity than was observed experimentally. Inlet nitrogen temperatures above 2400 K were sufficient to produce experimentally a completely reacted gas stream of synthetic air.

  7. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, ammonia was produced by 15 companies at 26 plants in 16 states in the United States. Of the total ammonia production capacity, 55% was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas. US producers operated at 66% of their rated capacity. In descending order, Koch Nitrogen, Terra Industries, CF Industries, Agrium and PCS Nitrogen accounted for 81% of the US ammonia production capacity.

  8. Opposed jet diffusion flames of nitrogen-diluted hydrogen vs air - Axial LDA and CARS surveys; fuel/air rates at extinction

    SciTech Connect

    Pellett, G.L.; Northam, G.B.; Wilson, L.G.; Jarrett, O. Jr.; Antcliff, R.R.

    1989-01-01

    An experimental study of H-air counterflow diffusion flames (CFDFs) is reported. Coaxial tubular opposed jet burners were used to form dish-shaped CFDFs centered by opposing laminar jets of H2/N2 and air in an argon bath at 1 atm. Jet velocities for extinction and flame restoration limits are shown versus input H2 concentration. LDA velocity data and CARS temperature and absolute N2, O2 density data give detailed flame structure on the air side of the stagnation point. The results show that air jet velocity is a more fundamental and appropriate measure of H2-air CFDF extinction than input H2 mass flux or fuel jet velocity. It is proposed that the observed constancy of air jet velocity for fuel mixtures containing 80 to 100 percent H2 measure a maximum, kinetically controlled rate at which the CFDF can consume oxygen in air. Fuel velocity mainly measures the input jet momentum required to center an H2/N2 versus air CFDF. 42 refs.

  9. Opposed jet diffusion flames of nitrogen-diluted hydrogen vs air - Axial LDA and CARS surveys; fuel/air rates at extinction

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Northam, G. B.; Wilson, L. G.; Jarrett, Olin, Jr.; Antcliff, R. R.

    1989-01-01

    An experimental study of H-air counterflow diffusion flames (CFDFs) is reported. Coaxial tubular opposed jet burners were used to form dish-shaped CFDFs centered by opposing laminar jets of H2/N2 and air in an argon bath at 1 atm. Jet velocities for extinction and flame restoration limits are shown versus input H2 concentration. LDA velocity data and CARS temperature and absolute N2, O2 density data give detailed flame structure on the air side of the stagnation point. The results show that air jet velocity is a more fundamental and appropriate measure of H2-air CFDF extinction than input H2 mass flux or fuel jet velocity. It is proposed that the observed constancy of air jet velocity for fuel mixtures containing 80 to 100 percent H2 measure a maximum, kinetically controlled rate at which the CFDF can consume oxygen in air. Fuel velocity mainly measures the input jet momentum required to center an H2/N2 versus air CFDF.

  10. Noble Gas (Argon and Xenon)-Saturated Cold Storage Solutions Reduce Ischemia-Reperfusion Injury in a Rat Model of Renal Transplantation

    PubMed Central

    Irani, Y.; Pype, J.L.; Martin, A.R.; Chong, C.F.; Daniel, L.; Gaudart, J.; Ibrahim, Z.; Magalon, G.; Lemaire, M.; Hardwigsen, J.

    2011-01-01

    Background Following kidney transplantation, ischemia-reperfusion injury contributes to adverse outcomes. The purpose of this study was to determine whether a cold-storage solution saturated with noble gas (xenon or argon) could limit ischemia-reperfusion injury following cold ischemia. Methods Sixty Wistar rats were randomly allocated to 4 experimental groups. Kidneys were harvested and then stored for 6 h before transplantation in cold-storage solution (Celsior®) saturated with either air, nitrogen, xenon or argon. A syngenic orthotopic transplantation was performed. Renal function was determined on days 7 and 14 after transplantation. Transplanted kidneys were removed on day 14 for histological and immunohistochemical analyses. Results Creatinine clearance was significantly higher and urinary albumin significantly lower in the argon and xenon groups than in the other groups at days 7 and 14. These effects were considerably more pronounced for argon than for xenon. In addition, kidneys stored with argon, and to a lesser extent those stored with xenon, displayed preserved renal architecture as well as higher CD-10 and little active caspase-3 expression compared to other groups. Conclusion Argon- or xenon-satured cold-storage solution preserved renal architecture and function following transplantation by reducing ischemia-reperfusion injury. PMID:22470401

  11. Argon Collection And Purification For Proliferation Detection

    SciTech Connect

    Achey, R.; Hunter, D.

    2015-10-09

    In order to determine whether a seismic event was a declared/undeclared underground nuclear weapon test, environmental samples must be taken and analyzed for signatures that are unique to a nuclear explosion. These signatures are either particles or gases. Particle samples are routinely taken and analyzed under the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) verification regime as well as by individual countries. Gas samples are analyzed for signature gases, especially radioactive xenon. Underground nuclear tests also produce radioactive argon, but that signature is not well monitored. A radioactive argon signature, along with other signatures, can more conclusively determine whether an event was a nuclear test. This project has developed capabilities for collecting and purifying argon samples for ultra-low-background proportional counting. SRNL has developed a continuous gas enrichment system that produces an output stream containing 97% argon from whole air using adsorbent separation technology (the flow diagram for the system is shown in the figure). The vacuum swing adsorption (VSA) enrichment system is easily scalable to produce ten liters or more of 97% argon within twelve hours. A gas chromatographic separation using a column of modified hydrogen mordenite molecular sieve has been developed that can further purify the sample to better than 99% purity after separation from the helium carrier gas. The combination of these concentration and purification systems has the capability of being used for a field-deployable system for collecting argon samples suitable for ultra-low-background proportional counting for detecting nuclear detonations under the On-Site Inspection program of the CTBTO verification regime. The technology also has applications for the bulk argon separation from air for industrial purposes such as the semi-conductor industry.

  12. Change in strategy of solving psychological tests: evidence of nitrogen narcosis in shallow air-diving.

    PubMed

    Petri, N M

    2003-01-01

    The depths from 10 to 30 m are usually not considered narcotic in scuba air-diving, and evidence of psychomotor disturbances attributable to nitrogen narcosis at these depths is weak and contradictory. 15 experienced male divers were tested in a chamber at 1, 2, 3, and 4 bars over five consecutive days using a battery of computer generated psychological tests-Computerized Reactionmeter Drenovac (CRD-series). Total test solving time, minimal single task solving time, total "ballast" time, and total number of errors were recorded. Nitrogen narcosis effects were evident at all hyperbaric pressures with marked performance differences among subjects. MANOVA revealed significant effects of nitrogen partial pressure for groups of the same variables as follows: total test solving time (p < 0.001), total "ballast" time (p < 0.001), and total number of errors (p = 0.038), but not for minimal single task solving time. ANOVA showed significant effects of pressure only on tests of visual discrimination of signal location (total test solving time: p = 0.012, total "ballast" time: p < 0.001), simple convergent visual orientation (total test solving time: p = 0.012), and convergent thinking (total test solving time: p = 0.002, total number of errors: p = 0.049). The order of the pressure exposures had no influence on subject performance. Impaired psychomotor processing found during air exposures from 2 to 4 bars suggests that nitrogen narcosis at depths usually considered safe from its effects might be a problem in underwater operations that require accuracy, speed, limited time of performance, and complex psychomotor skills.

  13. Review of the Primary National Ambient Air Quality Standards for Nitrogen Dioxide: Risk and Exposure Assessment Planning Document

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) is conducting a review of the air quality criteria and the primary (health-based) national ambient air quality standards (NAAQS) for nitrogen dioxide (NO2). The major phases of the process for reviewing NAAQS include the following: (...

  14. Characteristics of nitrogen balance in open-air and greenhouse vegetable cropping systems of China.

    PubMed

    Ti, Chaopu; Luo, Yongxia; Yan, Xiaoyuan

    2015-12-01

    Nitrogen (N) loss from vegetable cropping systems has become a significant environmental issue in China. In this study, estimation of N balances in both open-air and greenhouse vegetable cropping systems in China was established. Results showed that the total N input in open-air and greenhouse vegetable cropping systems in 2010 was 5.44 and 2.60 Tg, respectively. Chemical fertilizer N input in the two cropping systems was 201 kg N ha(-1) per season (open-air) and 478 kg N ha(-1) per season (greenhouse). The N use efficiency (NUE) was 25.9 ± 13.3 and 19.7 ± 9.4% for open-air and greenhouse vegetable cropping systems, respectively, significantly lower than that of maize, wheat, and rice. Approximately 30.6% of total N input was accumulated in soils and 0.8% was lost by ammonia volatilization in greenhouse vegetable system, while N accumulation and ammonia volatilization accounted for 19.1 and 11.1%, respectively, of total N input in open-air vegetable systems.

  15. Revisiting the mechanism of nitrogen fluorescence emission induced by femtosecond filament in air

    NASA Astrophysics Data System (ADS)

    Li, Suyu; Jiang, Yuanfei; Chen, Anmin; He, Lanhai; Liu, Dunli; Jin, Mingxing

    2017-03-01

    The backward propagating and side emitted fluorescence during the femtosecond filamentation in air is experimentally investigated in this paper. By comparing the fluorescence emission in the circular and linear polarization states, we find that in the shorter focal length case, the direct ionization of N 2 greatly affects the fluorescence emission behaviors: the fluorescence from N2 + and N 2 is always stronger in the linear and circular polarization cases, respectively. Based on the observation, the emission mechanism of nitrogen fluorescence emission induced by a femtosecond filament is discussed.

  16. Antiapoptotic activity of argon and xenon.

    PubMed

    Spaggiari, Sabrina; Kepp, Oliver; Rello-Varona, Santiago; Chaba, Kariman; Adjemian, Sandy; Pype, Jan; Galluzzi, Lorenzo; Lemaire, Marc; Kroemer, Guido

    2013-08-15

    Although chemically non-reactive, inert noble gases may influence multiple physiological and pathological processes via hitherto uncharacterized physical effects. Here we report a cell-based detection system for assessing the effects of pre-defined gas mixtures on the induction of apoptotic cell death. In this setting, the conventional atmosphere for cell culture was substituted with gas combinations, including the same amount of oxygen (20%) and carbon dioxide (5%) but 75% helium, neon, argon, krypton, or xenon instead of nitrogen. The replacement of nitrogen with noble gases per se had no effects on the viability of cultured human osteosarcoma cells in vitro. Conversely, argon and xenon (but not helium, neon, and krypton) significantly limited cell loss induced by the broad-spectrum tyrosine kinase inhibitor staurosporine, the DNA-damaging agent mitoxantrone and several mitochondrial toxins. Such cytoprotective effects were coupled to the maintenance of mitochondrial integrity, as demonstrated by means of a mitochondrial transmembrane potential-sensitive dye and by assessing the release of cytochrome c into the cytosol. In line with this notion, argon and xenon inhibited the apoptotic activation of caspase-3, as determined by immunofluorescence microscopy coupled to automated image analysis. The antiapoptotic activity of argon and xenon may explain their clinically relevant cytoprotective effects.

  17. Potential Impact of Clean Air Act Regulations on Nitrogen Fate and Transport in the Neuse River Basin: a Modeling Investigation Using CMAQ and SWAT

    EPA Science Inventory

    There has been extensive analysis of Clean Air Act Amendment (CAAA) regulation impacts to changes in atmospheric nitrogen deposition; however, few studies have focused on watershed nitrogen transfer particularly regarding long-term predictions. In this study, we investigated impa...

  18. Nitrogen and argon signatures in 3.8 to 2.8 Ga metasediments: clues on the chemical state of the archean ocean and the deep biosphere

    NASA Astrophysics Data System (ADS)

    Pinti, Daniele L.; Hashizume, Ko; Matsuda, Jun-ichi

    2001-07-01

    N and Ar elemental and isotopic analyses were conducted on Archean metasediments of Isukasia, West Greenland and Pilbara Craton, Western Australia, in order to investigate the N isotopic evolution during the first half of Earth's history. The selected samples are deep-sea sediments and hydrothermal deposits having ages from 3.8 to 2.8 Ga and affected by different degrees of metamorphism. The release patterns of N and Ar obtained by high-resolution stepped combustion show the occurrence of at least two trapped components. The first is released at 600°C and it is likely contained in fluid inclusions. N is released together with primordial 36Ar and shows a δ 15N value of -1.3 ± 1.0‰, close to that of modern atmospheric N 2 (δ 15N = 0‰). This component is well preserved in hydrothermal-vent silica deposits of North Pole, Pilbara Craton, and nitrogen may represent ammonium salt dissolved in deep-sea hydrothermal fluids. The second N component, released at temperatures higher than 1000°C, is accompanied by radiogenic 40Ar∗, and shows a δ 15N value of -7.4 ± 1.0‰ in a kerogen-rich chert from North Pole, Pilbara Craton. This N is likely biogenic and negative 15N values may reflect a metabolic isotopic fractionation induced by chemosynthetic bacteria using inorganic NH 4+ contained in hydrothermal fluids. This 15N-depleted biogenic component may occur in Isukasia Banded Iron Formation (δ 15N ˜ -1.7‰), but further data are needed to confirm such a hypothesis. In all other samples, metamorphic-induced Rayleigh distillation has altered the pristine N isotopic signature.

  19. [Methodology of the description of atmospheric air pollution by nitrogen dioxide by land use regression method in Ekaterinburg].

    PubMed

    Antropov, K M; Varaksin, A N

    2013-01-01

    This paper provides the description of Land Use Regression (LUR) modeling and the result of its application in the study of nitrogen dioxide air pollution in Ekaterinburg. The paper describes the difficulties of the modeling for air pollution caused by motor vehicles exhaust, and the ways to address these challenges. To create LUR model of the NO2 air pollution in Ekaterinburg, concentrations of NO2 were measured, data on factors affecting air pollution were collected, a statistical analysis of the data were held. A statistical model of NO2 air pollution (coefficient of determination R2 = 0.70) and a map of pollution were created.

  20. Effect of inlet-air humidity on the formation of oxides of nitrogen in a gas-turbine combustor

    NASA Technical Reports Server (NTRS)

    Marchionna, N. R.

    1973-01-01

    Tests were conducted to determine the effect of inlet-air humidity on the formation of oxides of nitrogen from a gas-turbine combustor. Combustor inlet-air temperature ranged from 450 F to 1050 F. The tests were run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NO sub x emission index was found to decrease with increasing inlet-air humidity at a constant exponential rate of 19 percent per mass percent water vapor in the air. This decrease of NO sub x emission index with increasing humidity was found to be independent of inlet-air temperature.

  1. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    Ammonia was produced by 12 companies at 27 plants in 15 states in the United States during 2011. Sixty-one percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2011, U.S. producers operated at about 84 percent of their rated capacity (excluding plants that were idle for the entire year). Four companies — CF Industries Holdings Inc.; Koch Nitrogen Co.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 77 percent of the total U.S. ammonia production capacity.

  2. Lunar exospheric argon modeling

    NASA Astrophysics Data System (ADS)

    Grava, Cesare; Chaufray, J.-Y.; Retherford, K. D.; Gladstone, G. R.; Greathouse, T. K.; Hurley, D. M.; Hodges, R. R.; Bayless, A. J.; Cook, J. C.; Stern, S. A.

    2015-07-01

    Argon is one of the few known constituents of the lunar exosphere. The surface-based mass spectrometer Lunar Atmosphere Composition Experiment (LACE) deployed during the Apollo 17 mission first detected argon, and its study is among the subjects of the Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) and Lunar Atmospheric and Dust Environment Explorer (LADEE) mission investigations. We performed a detailed Monte Carlo simulation of neutral atomic argon that we use to better understand its transport and storage across the lunar surface. We took into account several loss processes: ionization by solar photons, charge-exchange with solar protons, and cold trapping as computed by recent LRO/Lunar Orbiter Laser Altimeter (LOLA) mapping of Permanently Shaded Regions (PSRs). Recycling of photo-ions and solar radiation acceleration are also considered. We report that (i) contrary to previous assumptions, charge exchange is a loss process as efficient as photo-ionization, (ii) the PSR cold-trapping flux is comparable to the ionization flux (photo-ionization and charge-exchange), and (iii) solar radiation pressure has negligible effect on the argon density, as expected. We determine that the release of 2.6 × 1028 atoms on top of a pre-existing argon exosphere is required to explain the maximum amount of argon measured by LACE. The total number of atoms (1.0 × 1029) corresponds to ∼6700 kg of argon, 30% of which (∼1900 kg) may be stored in the cold traps after 120 days in the absence of space weathering processes. The required population is consistent with the amount of argon that can be released during a High Frequency Teleseismic (HFT) Event, i.e. a big, rare and localized moonquake, although we show that LACE could not distinguish between a localized and a global event. The density of argon measured at the time of LACE appears to have originated from no less than four such episodic events. Finally, we show that the extent of the PSRs that trap

  3. Targeting cancer cells with reactive oxygen and nitrogen species generated by atmospheric-pressure air plasma.

    PubMed

    Ahn, Hak Jun; Kim, Kang Il; Hoan, Nguyen Ngoc; Kim, Churl Ho; Moon, Eunpyo; Choi, Kyeong Sook; Yang, Sang Sik; Lee, Jong-Soo

    2014-01-01

    The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH-, •O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells.

  4. Joule-Thomson cryocooler with neon and nitrogen mixture using commercial air-conditioning compressors

    NASA Astrophysics Data System (ADS)

    Lee, Jisung; Oh, Haejin; Baek, Seungwhan; Lee, Cheonkyu; Jeong, Sangkwon

    2014-01-01

    A 2-stage mixed refrigerant (MR) Joule-Thomson (JT) cryocooler was designed for cooling high temperature superconducting cable below 70 K. The low temperature cycle was to operate with neon-nitrogen mixture, and the required compression ratio was approximately 24 when the suction pressure was 100 kPa. The high compression ratio of 24, the low pressure of 100 kPa at compressor suction, and the working fluid with high heat of compression were challenging issues to existing typical compression systems. We developed an innovative compression system with commercial oil-lubricated air-conditioning compressors. They were 2-stage rotary compressors originally designed for R410Aand connected in series. The compressors were modified to accommodate effective intercooling at every stage to alleviate compressor overheating problem. Additionally, fine-grade three-stage oil filters, an adsorber, and driers were installed at the discharge line to avoid a potential clogging problem from oil mist and moisture at low temperature sections. The present compression system was specifically demonstrated with a neon-nitrogen MR JT cryocooler. The operating pressure ratio was able to meet the designed specifications, and the recorded no-load mini mum temperature was 63.5 K . Commercial air-conditioning compressors were successfully applied to the high-c ompression ratio MR JT cryocooler with adequate modification using off-the-shelf components.

  5. Spectrophotometric determination of nitrogen dioxide in air and nitrite in water and soil samples

    SciTech Connect

    Pandurangappa, M.; Balasubramanian, N.

    1995-02-01

    A sensitive spectrophotometric method for the determination of nitrogen dioxide in air and nitrite in water and soil samples is described. Nitrogen dioxide in air is fixed as nitrite ion in alkaline sodium arsenite or in triethanolamine absorber solutions. The method is based on the diazo coupling reaction between p-nitro aniline and 1-hydroxy-2-naphthoic acid. The azo dye formed under aqueous condition has an absorption maximum at 585nm and obeys Beer`s law over the range 0-25{mu}g of nitrite. The colour system is stable for 72h. The relative standard deviation is 2.7% for ten determinations at 15{mu}g of nitrite. The dye is extracted with 1:1 isoamyl alcohol-IBMK mixture and stabilisation with methanolic potassium hydroxide showed {lambda}{sub max} at 610nm. It obeys Beer`s law over the range 0-4{mu}g of nitrite. The colour system is stable for 40h in organic phase and the relative standard deviation is 2.5% for ten determinations at 3{mu}g of nitrite. The molar absorptivity of the colour system is 3.68 x 10{sup 4} Lmol{sup {minus}1} cm{sup {minus}1}. The effect of interfering gases and other ions on the determination of nitrite is described. The developed method has been applied for the determination of residual nitrogen dioxide gas present in the laboratory fume cupboard and automobile exhaust gases. In addition, the method has been applied for the determination of nitrite and nitrate in samples like water, soil and radiator coolants.

  6. Depleted Argon from Underground Sources

    SciTech Connect

    Back, H. O.; Galbiati, C.; Goretti, A.; Loer, B.; Montanari, D.; Mosteiro, P.; Alexander, T.; Alton, A.; Rogers, H.; Kendziora, C.; Pordes, S.

    2011-04-27

    Argon is a strong scintillator and an ideal target for Dark Matter detection; however {sup 39}Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in {sup 39}Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO{sub 2} well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO{sub 2}. We first concentrate the argon locally to 3% in an Ar, N{sub 2}, and He mixture, from the CO{sub 2} through chromatographic gas separation, and then the N{sub 2} and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO{sub 2} facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

  7. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Ammonia was produced by 15 companies at 25 plants in 16 states in the United States during 2006. Fifty-seven percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock. In 2006, U.S. producers operated at about 72 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies, Koch Nitrogen, Terra Industries, CF Industries, PCS Nitro-gen, and Agrium, in descending order, accounted for 79 percent U.S. ammonia production capacity. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  8. Diffuse discharge produced by repetitive nanosecond pulses in open air, nitrogen, and helium

    NASA Astrophysics Data System (ADS)

    Shao, Tao; Tarasenko, Victor F.; Zhang, Cheng; Baksht, Evgeni Kh.; Zhang, Dongdong; Erofeev, Mikhail V.; Ren, Chengyan; Shutko, Yuliya V.; Yan, Ping

    2013-03-01

    Atmospheric-pressure gas discharge driven by high voltage pulses with fast rise-time and short duration has attracted significant attention for various plasma applications. In this paper, discharges were generated in a highly non-uniform electric field by point-plane gaps in open air by four repetitive nanosecond-pulse generators with repetition rate up to 1 kHz. The rise time of generators was 25 (generator #1), 15 (generator #2), 3 (generator #3), and 0.2 ns (generator #4) and a full width at half maximum was 40, 30-40, 5, and 1 ns, respectively. The experimental results show that there were typical discharge fashions, i.e., corona, diffuse, spark, or arc modes. The variables affecting the discharge characteristics, including the gap spacing and applied pulse parameters, were investigated. Especially, the diffuse discharges were investigated and discussed. With generator #1 at voltage 70-120 kV, characteristics of measured x-rays on the discharge modes were studied, and it indicates that counts of x-rays in a diffuse discharge are up to a peak value under the experimental conditions. With amplitude of voltage pulses in incident wave up to 18 (generator #3) and 12.5 kV (generator #4), runaway electron beam in low pressure helium, nitrogen, and air in a pulse-periodic mode of discharge with repetition rate up to 1 kHz was obtained. Electron beam was registered behind a thin foil in a pressure range from several to tens of Torr. X-ray radiation was obtained in a wide range of pressures, as well as at atmospheric pressure of helium, nitrogen, and air. Voltage pulses of positive and negative polarities were used. Generation of runaway electrons with pulses of positive polarity appeared because of reflected voltage pulses of reverse polarity.

  9. Fast Conversion of Ionic Liquids and Poly(Ionic Liquid)s into Porous Nitrogen-Doped Carbons in Air.

    PubMed

    Men, Yongjun; Ambrogi, Martina; Han, Baohang; Yuan, Jiayin

    2016-04-08

    Ionic liquids and poly(ionic liquid)s have been successfully converted into nitrogen-doped porous carbons with tunable surface area up to 1200 m²/g at high temperatures in air. Compared to conventional carbonization process conducted under inert gas to produce nitrogen-doped carbons, the new production method was completed in a rather shorter time without noble gas protection.

  10. Fast Conversion of Ionic Liquids and Poly(Ionic Liquid)s into Porous Nitrogen-Doped Carbons in Air

    PubMed Central

    Men, Yongjun; Ambrogi, Martina; Han, Baohang; Yuan, Jiayin

    2016-01-01

    Ionic liquids and poly(ionic liquid)s have been successfully converted into nitrogen-doped porous carbons with tunable surface area up to 1200 m2/g at high temperatures in air. Compared to conventional carbonization process conducted under inert gas to produce nitrogen-doped carbons, the new production method was completed in a rather shorter time without noble gas protection. PMID:27070588

  11. Measurements of air-broadened and nitrogen-broadened half-widths and shifts of ozone lines near 9 microns

    NASA Technical Reports Server (NTRS)

    Smith, M. A. H.; Rinsland, C. P.; Devi, Malathy V.; Benner, D. Chris; Thakur, K. B.

    1988-01-01

    Air- and nitrogen-broadened half-widths and line shifts at room temperature for more than 60 individual vibration-rotation transitions in the nu1 fundamental band of (O-16)3 and several transitions in the nu3 band were determined from infrared absorption spectra. These spectra were recorded at 0.005/cm resolution with a Fourier-transform spectrometer. A tunable-diode-laser spectrometer operating in the 1090-1150/cm region was also used to record data on oxygen-, nitrogen-, and air-broadened half-widths for selected individual transitions. The nitrogen- and air-broadened half-widths determined by these two different measurement techniques are consistent to within 4 percent. The results are in good agreement with other published measurements and calculations.

  12. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2010-01-01

    Ammonia was produced by 13 companies at 23 plants in 16 states during 2009. Sixty percent of all U.S. ammonia production capacity was centered in Louisiana. Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2009, U.S. producers operated at about 83 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies — Koch Nitrogen Co.; Terra Industries Inc.; CF Industries Inc.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 80 percent of the total U.S. ammonia production capacity. U.S. production was estimated to be 7.7 Mt (8.5 million st) of nitrogen (N) content in 2009 compared with 7.85 Mt (8.65 million st) of N content in 2008. Apparent consumption was estimated to have decreased to 12.1 Mt (13.3 million st) of N, a 10-percent decrease from 2008. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  13. Perovskite-nitrogen-doped carbon nanotube composite as bifunctional catalysts for rechargeable lithium-air batteries.

    PubMed

    Park, Hey Woong; Lee, Dong Un; Park, Moon Gyu; Ahmed, Raihan; Seo, Min Ho; Nazar, Linda F; Chen, Zhongwei

    2015-03-01

    Developing an effective bifunctional catalyst is a significant issue, as rechargeable metal-air batteries are very attractive for future energy systems. In this study, a facile one-pot process is introduced to prepare an advanced bifunctional catalyst (op-LN) incorporating nitrogen-doped carbon nanotubes (NCNTs) into perovskite La0.5 Sr0.5 Co0.8 Fe0.2 O3 nanoparticles (LSCF-NPs). Confirmed by half-cell testing, op-LN exhibits synergistic effects of LSCF-NP and NCNT with excellent bifunctionality for both the oxygen reduction reaction and the oxygen evolution reaction. Furthermore, op-LN exhibits comparable performances in these reactions to Pt/C and Ir/C, respectively, which highlights its potential for use as a commercially viable bifunctional catalyst. Moreover, the results obtained by testing op-LN in a practical Li-air battery demonstrate improved and complementary charge/discharge performance compared to those of LSCF-NP and NCNT, and this confirms that simply prepared op-LN is a promising candidate as a highly effective bifunctional catalyst for rechargeable metal-air batteries.

  14. Roles of nitrogen, oxygen, and carbon dioxide in compressed-air narcosis.

    PubMed

    Hesser, C M; Fagraeus, L; Adolfson, J

    1978-12-01

    In an attempt to determine the roles of nitrogen, oxygen, and carbon dioxide in compressed-air narcosis, the effects on performance (mental function and manual dexterity) of adding CO2 in various concentrations to the inspired gas under three different conditions were studied in eight healthy male volunteers. The three conditions were: (1) air breathing at 1.3 ATA; (2) oxygen breathing at 1.7 ATA; and (3) air breathing at 8.0 ATA (same inspired O2 pressure as in (2)). By relating performance to the changes induced in end-tidal (alveolar) gas pressures, and comparing the data from the three conditions, we arrived at the following results and conclusions. A rise in O2 pressure to 1.65 ATA, or in N2 pressure to 6.3 ATA at a constant high PO2 level, caused a significant decrement of 10% in mental function but no consistent effect on psychomotor function. A rise in end-tidal PCO2 of 10 mmHg caused an impairment of approximately 10% in both mental and psychomotor functions. The results suggest that, at raised partial pressures, all three gases have narcotic properties, and that the mechanism of CO2 narcosis differs fundamentally from that of N2 and O2 narcosis.

  15. The NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling

    NASA Technical Reports Server (NTRS)

    Koshak, William; Peterson, Harold; Khan, Maudood; Biazar, Arastoo; Wang, Lihua

    2011-01-01

    Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark)(NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NO(x) (= NO + NO2). The latest LNOM estimates of lightning channel length distributions, lightning 1-m segment altitude distributions, and the vertical profile of lightning NO(x) are presented. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOx production due to: (1) hot core stepped and dart leaders, (2) stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NO(x) for an August 2006 run of CMAQ is discussed.

  16. Atmospheric air pollutants: CO in Nitrogen, 5 μmol/mol

    NASA Astrophysics Data System (ADS)

    Konopelko, L. A.; Pankratov, V. V.; Pankov, A. A.; Ivahnenko, B. V.; Efremova, O. V.; Bakovec, N. V.; Mironchik, A. M.; Aleksandrov, V. V.

    2017-01-01

    This article presents the report on the COOMET supplementary comparison "Atmospheric air pollutants: CO in Nitrogen, 5 μmol/mol". Carbon monoxide (CO) is present in atmosphere due to different natural and anthropogenic sources. CO is a toxic gas and in concentrations higher than (3-5) μmol/mol it is hazardous to human health. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  17. Pyrolysis and combustion of tobacco in a cigarette smoking simulator under air and nitrogen atmosphere.

    PubMed

    Busch, Christian; Streibel, Thorsten; Liu, Chuan; McAdam, Kevin G; Zimmermann, Ralf

    2012-04-01

    A coupling between a cigarette smoking simulator and a time-of-flight mass spectrometer was constructed to allow investigation of tobacco smoke formation under simulated burning conditions. The cigarette smoking simulator is designed to burn a sample in close approximation to the conditions experienced by a lit cigarette. The apparatus also permits conditions outside those of normal cigarette burning to be investigated for mechanistic understanding purposes. It allows control of parameters such as smouldering and puff temperatures, as well as combustion rate and puffing volume. In this study, the system enabled examination of the effects of "smoking" a cigarette under a nitrogen atmosphere. Time-of-flight mass spectrometry combined with a soft ionisation technique is expedient to analyse complex mixtures such as tobacco smoke with a high time resolution. The objective of the study was to separate pyrolysis from combustion processes to reveal the formation mechanism of several selected toxicants. A purposely designed adapter, with no measurable dead volume or memory effects, enables the analysis of pyrolysis and combustion gases from tobacco and tobacco products (e.g. 3R4F reference cigarette) with minimum aging. The combined system demonstrates clear distinctions between smoke composition found under air and nitrogen smoking atmospheres based on the corresponding mass spectra and visualisations using principal component analysis.

  18. 78 FR 54813 - Approval and Promulgation of Air Quality Implementation Plans; Maine; Oxides of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-06

    ... Nitrogen Exemption and Ozone Transport Region Restructuring AGENCY: Environmental Protection Agency (EPA...; Oxides of Nitrogen Exemption and Ozone Transport Region Restructuring (August 5, 2013). The EPA...

  19. Argon laser for otosclerosis

    NASA Astrophysics Data System (ADS)

    Michalski, Wojciech; Pospiech, Lucyna; Jankowska-Kuc, Malgorzata

    1995-03-01

    Up to now, among different kinds of lasers an argon laser is mostly used for otosclerosis. Exposure conditions at use of the laser beam are still not well defined. In order to achieve the optimum conditions a series of experiments has been made. Obtained results are presented in this paper.

  20. Thermophysical properties of argon

    SciTech Connect

    Jaques, A.

    1988-02-01

    The entire report consists of tables of thermodynamic properties (including sound velocity, thermal conductivity and diffusivity, Prandtl number, density) of argon at 86 to 400/degree/K, in the form of isobars over 0.9 to 100 bars. (DLC)

  1. Workshop in Support of the Secondary National Ambient Air Quality Standards for Nitrogen (NOx) and Sulfur Oxides (SOx)

    EPA Science Inventory

    EPA is announcing a workshop to discuss policy-relevant science to Inform EPA’s "Review of the Secondary National Ambient Air Quality Standards (NAAQS) for Oxides of Nitrogen and Sulfur" report. The workshop is being organized by EPA’s Office of Research and Development’s, Nation...

  2. The effects of argon in the bioenergetics of the hamster and the rat

    NASA Technical Reports Server (NTRS)

    Tempel, G. E.; Musacchia, X. J.

    1974-01-01

    Oxygen consumption was examined in hamsters and rats exposed to normoxic mixtures of argon at 1 atm. In fasted and nonfasted animals, no marked change in O2 utilization was detectable at 22 C. However, at 7 C a significant decrease in oxygen consumption was observed where the animals were exposed in argon. The data are interpreted in terms of the greater thermal conductivity of nitrogen. The study was prompted by conflicting reports on the metabolic effects of argon and helium.

  3. Determination of collisional quenching rate coefficients of metastable nitrogen molecules by air pollutants

    NASA Astrophysics Data System (ADS)

    Suzuki, Susumu; Itoh, Haruo

    2009-10-01

    It has already been investigated on the determination of the collisional quenching rate coefficients of the metastable nitrogen molecules N2(A^3σu^+ ) by some air pollutants [1] in our laboratory. In this report, we present the result on the collisional quenching rate coefficient of N2(A^3σu^+ ) by formaldehyde (CH2O) using a theoretical procedure that takes into account the reflection of metastables at the boundary. As far as we know, this report is the first result of the collisional quenching rate coefficients of N2(A^3σu^+ ) by CH2O. Formaldehyde is a colorless gas with the foul odor, and elements of the adhesive, paints, and preservative, etc. It is widely used for construction materials such as houses, because it is low cost. It is released from paint of construction materials in air, and, in that case, it is known as one of the causative agents of so-called ``Sick building syndrome'' to influence the human body harmfully even if it is a low concentration. The obtained collisional quenching rate coefficient of N2(A^3σu^+ ) by CH2O is (4.7±0.4) x 10-12 cm^3/s. Because the collisional quenching rate coefficient by CH2O is large, it is understood that CH2O receives energy easily from N2(A^3σu^+ ). In addition, we reports on the obtained collisional quenching rate coefficient of N2(A^3σu^+ ) by some air pollutants. [1] S. Suzuki, T.Suzuki and H.Itoh: Proc. of XXVIII ICPIG (Prague, Czech Republic), (2007) 1P01-40.

  4. Monitoring organic nitrogen species in the UT/LS - a new system for analysis of CARIBIC whole air samples

    NASA Astrophysics Data System (ADS)

    Sauvage, Carina; Thorenz, Ute; Baker, Angela; Brenninkmeijer, Carl; Williams, Jonathan

    2014-05-01

    The CARIBIC project is a unique program for long term and global scale monitoring of the atmosphere (http://www.caribic-atmospheric.com). An instrument container is installed monthly into a civil aircraft operated by Lufthansa (Airbus A 340-600) and makes atmospheric observations en route from Frankfurt, Germany to various destinations around the globe. In four to six long distance flights at a cruising altitude of 10 to 12 km online measurements of various atmospheric tracers are performed during the flight as well as whole air samples are taken with two different sampling units (116 samples in both glass and stainless steel canisters). These samples are routinely analyzed for greenhouse gases, non-methane hydrocarbons (NMHC) and halogenated compounds. Nitrogen containing compounds play various important roles in the atmosphere. Alkyl nitrates (RONO2) are products of the reaction of NMHC with OH and other oxidants in the presence of NO. They can provide information on the oxidative history of an air mass. Moreover they influence photolchemical ozone formation and act as a transport mechanism for reactive nitrogen. Less reactive nitrogen containing species such as HCN and acetonitrile are important markers for biomass burning, while organic amines are involved in gas to particle partitioning. Finally N2O is a long lived nitrogen containing gas important for the Earth's radiative budget. Regular measurements of such nitrogen compounds would therefore be a significant contribution to the CARIBIC data set. Especially for high altitude samples, in which the mixing ratios of many species are expected to be in the low ppt range, a highly sensitive method for analysis is required. Therefore a new system for measurement of nitrogen compounds has been built up, comprising a gas chromatograph (GC) using a nitrogen chemiluminescence detector (NCD). An important advantage of the NCD is that it is selective for nitrogen and equimolar. The nitrogen compounds are sequentially pre

  5. The interaction of an atmospheric pressure plasma jet using argon or argon plus hydrogen peroxide vapour addition with bacillus subtilis

    NASA Astrophysics Data System (ADS)

    Deng, San-Xi; Cheng, Cheng; Ni, Guo-Hua; Meng, Yue-Dong; Chen, Hua

    2010-10-01

    This paper reports that an atmospheric pressure dielectric barrier discharge plasma jet, which uses argon or argon + hydrogen peroxide vapour as the working gas, is designed to sterilize the bacillus subtilis. Compared with the pure argon plasma, the bacterial inactivation efficacy has a significant improvement when hydrogen peroxide vapour is added into the plasma jet. In order to determine which factors play the main role in inactivation, several methods are used, such as determination of optical emission spectra, high temperature dry air treatment, protein leakage quantification, and scanning electron microscope. These results indicate that the possible inactivation mechanisms are the synergistic actions of chemically active species and charged species.

  6. Nitrogen potential recovery and concentration of ammonia from swine manure using electrodialysis coupled with air stripping.

    PubMed

    Ippersiel, D; Mondor, M; Lamarche, F; Tremblay, F; Dubreuil, J; Masse, L

    2012-03-01

    The practice of intensive animal production in certain areas has resulted in excessive manure production for the available regional land base. Consequently, there is a need to develop treatment technologies to recover the valuable nutrients that manure contains so that the resulting product can be transported and used as fertilizer on agricultural land. The project presented here used electrodialysis in a dilution/concentration configuration to transfer the manure ammonia in the diluate solution by electromigration to an adjacent solution separated by an ion-exchange membrane under the driving force of an electrical potential. Then, air stripping from the electrodialysis-obtained concentrate solution without pH modification was used to isolate the ammonia in an acidic solution. An optimal process operating voltage of 17.5 V was first determined on the basis of current efficiency and total energy consumption. During the process, the swine manure pH varied from 8.5 to 8.2, values favourable for NH(4)(+) electromigration. Total ammonia nitrogen reached 21,352 mg/L in the concentrate solution, representing approximately seven times the concentration in the swine manure. Further increases in concentration were limited by water transfer from the diluate solution due to electroosmosis and osmosis. Applying vacuum to the concentrate reservoir was found to be more efficient than direct concentrate solution aeration for NH(3) recuperation in the acid trap, given that the ammonia recuperated under vacuum represented 14.5% of the theoretical value of the NH(3) present in the concentrate solution as compared to 6.2% for aeration. However, an excessively low concentrate solution pH (8.6-8.3) limited NH(3)volatilization toward the acid trap. These results suggest that the concentrate solution pH needs to be raised to promote the volatile NH(3) form of total ammonia nitrogen.

  7. Isentropic Compression of Argon

    SciTech Connect

    H. Oona; J.C. Solem; L.R. Veeser, C.A. Ekdahl; P.J. Rodriquez; S.M. Younger; W. Lewis; W.D. Turley

    1997-08-01

    We are studying the transition of argon from an insulator to a conductor by compressing the frozen gas isentropically to pressures at which neighboring atomic orbitals overlap sufficiently to allow some electron motion between atoms. Argon and the other rare gases have closed electron shells and therefore remain montomic, even when they solidify. Their simple structure makes it likely that any measured change in conductivity is due to changes in the atomic structure, not in molecular configuration. As the crystal is compressed the band gap closes, allowing increased conductivity. We have begun research to determine the conductivity at high pressures, and it is our intention to determine the compression at which the crystal becomes a metal.

  8. A synthesis of the ecological effects of air pollution from nitrogen and sulfur in the U.S

    USGS Publications Warehouse

    Greaver, T.L.; Sullivan, T.; Herrick, J.D.; Barber, M.; Baron, J.; Cosby, B.; Deerharke, M.; Dennis, R.; Dubois, J.J.D.; Goodale, C.; Herlihy, A.; Lawrence, G.; Liu, L.; Lynch, J.; Novak, K.

    2012-01-01

    Four decades after the passage of the US Clean Air Act, air-quality standards are set to protect ecosystems from damage caused by gas-phase nitrogen (N) and sulfur (S) compounds, but not from the deposition of these air pollutants to land and water. Here, we synthesize recent scientific literature on the ecological effects of N and S air pollution in the US. Deposition of N and S is the main driver of ecosystem acidification and contributes to nutrient enrichment in many natural systems. Although surface-water acidification has decreased in the US since 1990, it remains a problem in many regions. Perturbations to ecosystems caused by the nutrient effects of N deposition continue to emerge, although gas-phase concentrations are generally not high enough to cause phytotoxicity. In all, there is overwhelming evidence of a broad range of damaging effects to ecosystems in the US under current air quality conditions.

  9. Effect of dynamic diffusion of air, nitrogen, and helium gaseous media on the microhardness of ionic crystals with juvenile surfaces

    NASA Astrophysics Data System (ADS)

    Klyavin, O. V.; Fedorov, V. Yu.; Chernov, Yu. M.; Shpeizman, V. V.

    2015-09-01

    The load dependences of the microhardness of surface layers of NaCl and LiF ionic single crystals with juvenile surfaces and surfaces exposed to air for a long time measured in the air, nitrogen, and helium gaseous media have been investigated. It has been found that there is a change in the sign of the derivative of the microhardness as a function of the load for LiF crystals indented in helium and after their aging in air, as well as a weaker effect of the nitrogen and air gaseous media on the studied dependences as compared to NaCl crystals. It has also been found that, after the aging of the surface of NaCl crystals in air, there is a change in the sign of the derivative of the microhardness in the nitrogen and air gaseous media, as well as a pronounced change in the microhardness as a function of the time of aging the samples in air as compared to the weaker effect of the gaseous medium for LiF crystals. The obtained data have been analyzed in terms of the phenomenon of dislocation-dynamic diffusion of particles from the external medium into crystalline materials during their plastic deformation along the nucleating and moving dislocations. It has been shown that this phenomenon affects the microhardness through changes in the intensity of dislocation multiplication upon the formation of indentation rosettes in different gaseous media. The performed investigation of the microhardness of the juvenile surface of NaCl and LiF crystals in different gaseous media has revealed for the first time a different character of dislocation-dynamic diffusion of these media in a "pure" form.

  10. 76 FR 68638 - Approval and Promulgation of Air Quality Implementation Plans; Virginia; Revision to Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... Nitrogen Oxides Budget Trading Program AGENCY: Environmental Protection Agency (EPA). ACTION: Direct final... Implementation Plan (SIP). The revision pertains to regulatory language in its nitrogen oxides (NO X ) Budget..., Nitrogen dioxide, Ozone, Sulfur oxides. Dated: October 25, 2011. W.C. Early, Acting Regional...

  11. 76 FR 11082 - Approval and Promulgation of Air Quality Implementation Plans; Ohio; Oxides of Nitrogen Budget...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-01

    ... Nitrogen Budget Trading Program; Technical Amendment AGENCY: Environmental Protection Agency (EPA). ACTION..., 2009. This relates to Ohio rule revisions concerning 240 allowances under the Nitrogen Oxides Budget... oxides of nitrogen (NO X ) allowances from the State's 2005 new source allowance set aside under the NO...

  12. 75 FR 12168 - Approval and Promulgation of Air Quality Implementation Plans; Delaware; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-15

    ... Nitrogen Oxide Emissions From Industrial Boilers and Process Heaters at Petroleum Refineries AGENCY...--Control of Nitrogen Oxide Emissions from Industrial Boilers and Process Heaters at Petroleum Refineries to... Nitrogen Oxide Emissions from Industrial Boilers and Process Heaters at Petroleum Refineries....

  13. Comparison of two manual methods of nitrogen dioxide determination in ambient air.

    PubMed

    Goyal, S K

    2003-12-01

    Sodium arsenite (modified Jacobs and Hochheiser method; hereafter referred as SA), the most widely used manual monitoring method for determination of nitrogen dioxide (NO2) in ambient air, particularly in developing countries has been evaluated and compared with US EPA recommended equivalent method of TGS-ANSA (hereafter referred as ANSA). NO2 concentrations generated from laboratory test atmosphere were analyzed by these two methods and were compared statistically. Laboratory evaluations showed that SA method has high sensitivity to different sampling conditions, which normally vary during actual field monitoring. Hence, correction factors for absorption efficiency were estimated for SA and ANSA methods. Absorption efficiency of NO2 in SA method was found to be much lower (64%) as against the reported value of 82% at the method recommended sampling conditions, whereas for ANSA method, it was found 1.0 as against the reported value of 0.93. After applying derived correction factors, both the methods produced almost similar concentration values of NO2.

  14. Three air quality studies: Great Lakes ozone formation and nitrogen dry deposition; and Tucson aerosol chemical characterization

    NASA Astrophysics Data System (ADS)

    Foley, Theresa

    The Clean Air Act of 1970 was promulgated after thousands of lives were lost in four catastrophic air pollution events. It authorized the establishment of National Ambient Air Quality Standards or (NAAQS) for six pollutants that are harmful to human health and welfare: carbon monoxide, lead, nitrogen dioxide, particulate matter, ozone and sulfur dioxide. The Clean Air Act also led to the establishment of the United Stated Environmental Protection Agency (US EPA) to set and enforce regulations. The first paper in this dissertation studies ozone in the Lake Michigan region (Foley, T., Betterton, E.A., Jacko, R., Hillery, J., 2011. Lake Michigan air quality: The 1994-2003 LADCO Aircraft Project (LAP). Atmospheric Environment 45, 3192-3202.) The Chicago-Milwaukee-Gary metropolitan area has been unable to meet the ozone NAAQS since the Clean Air Act was implemented. The Lake Michigan Air Directors' Consortium (LADCO) hypothesized that land breezes transport ozone precursor compounds over the lake, where a large air/water temperature difference creates a shallow conduction layer, which is an efficient reaction chamber for ozone formation. In the afternoon, lake breezes and prevailing synoptic winds then transport ozone back over the land. To further evaluate this hypothesis, LADCO sponsored the 1994-2003 LADCO Aircraft Project (LAP) to measure the air quality over Lake Michigan and the surrounding areas. This study has found that the LAP data supports this hypothesis of ozone formation, which has strong implications for ozone control strategies in the Lake Michigan region. The second paper is this dissertation (Foley, T., Betterton, E.A., Wolf, A.M.A., 2012. Ambient PM10 and metal concentrations measured in the Sunnyside Unified School District, Tucson, Arizona. Journal of the Arizona-Nevada Academy of Science, 43, 67-76) evaluated the airborne concentrations of PM10 (particulate matter with an aerodynamic diameter of 10 microns or less) and eight metalloids and metals

  15. The Argon Geochronology Experiment (AGE)

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.; Bode, R.; Fennema, A.; Chutjian, A.; MacAskill, J. A.; Darrach, M. R.; Clegg, S. M.; Wiens, R. C.; Cremers, D.

    2006-01-01

    This viewgraph presentation reviews the Argon Geochronology Experiment (AGE). Potassium-Argon dating is shown along with cosmic ray dating exposure. The contents include a flow diagram of the Argon Geochronology Experiment, and schematic diagrams of the mass spectrometer vacuum system, sample manipulation mechanism, mineral heater oven, and the quadrupole ion trap mass spectrometer. The Laser-Induced Breakdown Spectroscopy (LIBS) Operation with elemental abundances is also described.

  16. Statistical summary of air quality data for metropolitian Cleveland, Ohio, 1967 - 1972: Total suspended particulates, nitrogen dioxide, and sulfur dioxide

    NASA Technical Reports Server (NTRS)

    King, R. B.; Neustadter, H. E.; Fordyce, J. S.; Burr, J. C., Jr.; Cornett, C. L.

    1974-01-01

    Air-quality data for metropolitan Cleveland, Ohio, from 1967 through 1972 were collated and statistically analyzed. Total suspended particulates (TSP) departed from lognormal distribution in 1972. Nitrogen dioxide and sulfur dioxide, departed significantly from lognormal distributions in 1972. In Cleveland the Ohio standards were not met. However, the data indicate a general improvement in air quality. Unusually high precipitation (43% above the average in 1972) may be responsible in lowering these values from the 1971 levels. The mean values of TSP, NO2, and SO2 are 104, 191, and 83 microgram/cu m respectively.

  17. Isentropic compression of argon

    SciTech Connect

    Veeser, L.R.; Ekdahl, C.A.; Oona, H.

    1997-06-01

    The compression was done in an MC-1 flux compression (explosive) generator, in order to study the transition from an insulator to a conductor. Since conductivity signals were observed in all the experiments (except when the probe is removed), both the Teflon and the argon are becoming conductive. The conductivity could not be determined (Teflon insulation properties unknown), but it could be bounded as being {sigma}=1/{rho}{le}8({Omega}cm){sub -1}, because when the Teflon breaks down, the dielectric constant is reduced. The Teflon insulator problem remains, and other ways to better insulate the probe or to measure the conductivity without a probe is being sought.

  18. The authors reply to "The Joys of Liquid Nitrogen"

    NASA Astrophysics Data System (ADS)

    Nolan, William T.; Gish, Thaddeus J.

    1997-06-01

    We thank Ronald C. Blatchley for his interpretation of experiment 3, "The Mysterious Liquid Drop", and for pointing out that the drop is a mixture containing nitrogen as well as oxygen. The liquid drop that forms at the bottom of the tube has a temperature of about -196 °C, the temperature of the boiling liquid nitrogen used to cool the tube. The air in the tube above the drop is very cold, and contains a large number of gaseous nitrogen and oxygen molecules having low kinetic energies and low molecular speeds. In addition, the density of the air above the drop is high relative to the warmer air outside of the tube, and the frequency of collision of gaseous nitrogen molecules with the drop's surface is high. Therefore, a significant number of gaseous nitrogen molecules would be expected to condense at the surface of the drop and be retained by dispersion forces. In addition to nitrogen and oxygen, we would expect the drop to contain other condensed substances such as argon and traces of higher-boiling noble gases. Argon would boil at -183 °C, prior to the oxygen boiling at -183 °C, as the tube is allowed to warm. The chemical behavior of the burning wood splint described in Blatchley's experiment is precisely what we observe when experiment 4, "A Familiar Chemical Change", is performed. Timing is indeed important. The glowing splint is extinguished if the test tube containing the drop is not allowed to warm in air for a short time. However, if we first warm the tube in the air for a few seconds and then insert the splint, the splint bursts into flame. His interpretation nicely explains these observations.

  19. Analysis of effect of flameholder characteristics on lean, premixed, partially vaporized fuel-air mixtures quality and nitrogen oxides emissions

    NASA Technical Reports Server (NTRS)

    Cooper, L. P.

    1981-01-01

    An analysis was conducted of the effect of flameholding devices on the precombustion fuel-air characteristics and on oxides of nitrogen (NOx) emissions for combustion of premixed partially vaporized mixtures. The analysis includes the interrelationships of flameholder droplet collection efficiency, reatomization efficiency and blockage, and the initial droplet size distribution and accounts for the contribution of droplet combustion in partially vaporized mixtures to NOx emissions. Application of the analytical procedures is illustrated and parametric predictions of NOx emissions are presented.

  20. Estimates of the atmospheric deposition of sulfur and nitrogen species: Clean Air Status and Trends Network 1990-2000.

    PubMed

    Baumgardner, Ralph E; Lavery, Thomas F; Rogers, Christopher M; Isil, Selma S

    2002-06-15

    The Clean Air Status and Trends Network (CASTNet) was established by the U.S. EPA in response to the requirements of the 1990 Clean Air Act Amendments. To satisfy these requirements CASTNet was designed to assess and report on geographic patterns and long-term, temporal trends in ambient air pollution and acid deposition in order to gauge the effectiveness of current and future mandated emission reductions. This paper presents an analysis of the spatial patterns of deposition of sulfur and nitrogen pollutants for the period 1990-2000. Estimates of deposition are provided for two 4-yr periods: 1990-1993 and 1997-2000. These two periods were selected to contrast deposition before and after the large decrease in SO2 emissions that occurred in 1995. Estimates of dry deposition were obtained from measurements at CASTNet sites combined with deposition velocities that were modeled using the multilayer model, a 20-layer model that simulates the various atmospheric processes that contribute to dry deposition. Estimates of wet deposition were obtained from measurements at sites operated bythe National Atmospheric Deposition Program. The estimates of dry and wet deposition were combined to calculate total deposition of atmospheric sulfur (dry SO2, dry and wet SO4(2-)) and nitrogen (dry HNO3, dry and wet NO3-, dry and wet NH4+). An analysis of the deposition estimates showed a significant decline in sulfur deposition and no change in nitrogen deposition. The highest rates of sulfur deposition were observed in the Ohio River Valley and downwind states. This region also observed the largest decline in sulfur deposition. The highest rates of nitrogen deposition were observed in the Midwest from Illinois to southern New York State. Sulfur and nitrogen deposition fluxes were significantly higher in the eastern United States as compared to the western sites. Dry deposition contributed approximately 38% of total sulfur deposition and 30% of total nitrogen deposition in the eastern

  1. On the Ratio of Sulfur Dioxide to Nitrogen Oxides as an Indicator of Air Pollution Sources.

    NASA Astrophysics Data System (ADS)

    Nirel, Ronit; Dayan, Uri

    2001-07-01

    The ratio of sulfur dioxide to nitrogen oxides (RSN = SO2/NOx) is one indicator of air pollution sources. The role of this ratio in source attribution is illustrated here for the Ashdod area, located in the southern coastal plain of Israel. The main sources of pollution in the area are the tall stacks of the Eshkol power plant, the stacks of oil refineries, and areal sources (stationary and mobile). The factors that affect RSN are studied using four regression models: a binary regression tree in original scale, a tree in logarithmic scale, a data partition produced by a combination of the two trees, and a linear regression model. All models have similar relative prediction error, with the combined partition best highlighting the sources of variability in RSN: (a) very low values (interquartile range of [0.12, 0.48]) are associated with traffic, (b) low values ([0.43, 1.00]) are attributed to the power plant and to daytime emissions of local industry, (c) medium values ([0.74, 1.90]) are associated with local industry emissions during cooler hours of the day and refinery emissions mainly on slow wind episodes, and (d) high values ([1.07, 4.30]) are attributed to refinery emissions during moderate to fast wind episodes. Analysis of the number of episodes of increased concentrations indicates that, during 1996 and 1997, about 42% of SO2 episodes are attributable to the power plant and 33% to the refineries. Increased-NOx episodes are mainly contributed by traffic (91%) and power plant (4.5%) emissions.

  2. Erratum to "Rayleigh scattering cross-section measurements of nitrogen, argon, oxygen and air" J Quant Spectrosc Radiat Transf 147 (2014) 171-177

    NASA Astrophysics Data System (ADS)

    Thalman, Ryan; Zarzana, Kyle J.; Tolbert, Margaret A.; Volkamer, Rainer

    2017-03-01

    Tables 1 and 2 of the published material [1] contain a series of typographical errors. In Table 1 the exponent of the B term for N2 was corrected to 1012 and ν for the two N2 cases should be ν2 for the King correction factor. In Table 2 the units are (cm2×1027), the N2 calculation at 660.0 nm is 2.21×10-27 cm2 and the O2 calculation at 532.2 nm is 4.66×10-27 cm2.

  3. Argon Welding Inside A Workpiece

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E.

    1988-01-01

    Canopies convert large hollow workpiece into inert-gas welding chamber. Large manifold serves welding chamber for attachment of liner parts in argon atmosphere. Every crevice, opening and passageway provided with argon-rich environment. Weld defects and oxidation dramatically reduced; also welding time reduced.

  4. Reactive nitrogen in Rocky Mountain National Park during the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ)

    NASA Astrophysics Data System (ADS)

    Prenni, A. J.; Benedict, K. B.; Evanoski-Cole, A. R.; Zhou, Y.; Sullivan, A.; Day, D.; Sive, B. C.; Zondlo, M. A.; Schichtel, B. A.; Vimont, J.; Collett, J. L., Jr.

    2014-12-01

    The Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) took place in July-August 2014. This collaborative study was aimed at characterizing those processes which control air quality along Colorado's Front Range. Although the study was largely focused on ozone, an additional goal of the study included characterizing contributions from Front Range sources and long-range transport to total reactive nitrogen in Rocky Mountain National Park (ROMO). Import of reactive nitrogen into ROMO and other pristine, high elevation areas has the potential to negatively impact terrestrial and aquatic ecosystems. We present measurements of reactive nitrogen species measured within ROMO during FRAPPÉ, and compare these data to measurements made in the surrounding areas. At our monitoring site in ROMO, co-located with IMPROVE and CASTNet monitoring, measurements of NO, NO2, NOx, NOy, NH3, and total reactive nitrogen (TNx) were made at high time resolution. Additional measurements of NH3, HNO3 and PM2.5 ions were made at hourly resolution using a MARGA and also at 24-hour time resolution using URG denuder-filter pack sampling. Precipitation samples also were collected to quantify wet deposition of ammonium, nitrate, and organic nitrogen. Finally, measurements of organic gases were made using online gas chromatography and proton transfer reaction-mass spectrometry. Preliminary results for ammonia show both a diel pattern, with concentrations increasing each morning, and a strong dependence on wind direction, implicating the importance of transport. Higher concentrations of NOx and NOy also were observed in the daytime, but in general these patterns differed from that of ammonia. Several upslope events were observed during the measurement period during which NOx, NH3, 2-propylnitrate, 2-butylnitrate, ethane, butane, and pentane were observed to increase in concentration along with ozone.

  5. Linking Agricultural Crop Management and Air Quality Models for Regional to National-Scale Nitrogen Assessments

    EPA Science Inventory

    While nitrogen (N) is an essential element for life, human population growth and demands for energy, transportation and food can lead to excess nitrogen in the environment. A modeling framework is described and implemented to promote a more integrated, process-based and system le...

  6. Teeming stream protection using an argon shroud during casting of steel ingots

    NASA Astrophysics Data System (ADS)

    Zhang, Chao-jie; Bao, Yan-ping; Wang, Min; Zhang, Le-chen

    2017-01-01

    Two kinds of argon shroud protection devices with two different basic structures were designed and investigated. Industrial experiments and numerical simulations were used to examine the protection effect, and the mechanism of air entrapment during the casting of steel ingots was analyzed. The influence of the structure of the argon shroud protection device on the protection effect was investigated. An argon shroud protection device mounted to the nozzle holder on the bottom of the ladle does not provide a good protection effect because air can easily flow into the teeming system and cause reoxidation of molten steel during teeming. By contrast, an argon shroud protection device seated on the top of the central trumpet provides an excellent protection effect, where air has little chance of flowing into the teeming system during casting. The feasibilities of the argon shroud protection devices are discussed.

  7. Sterilization of bacterial endospores by an atmospheric-pressure argon plasma jet

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Lim, Jin P.; Li, Shou Z.

    2007-06-01

    Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. However, the spore-killing efficiency of the atmospheric-pressure argon-oxygen jet depends very sensitively on the oxygen concentration in the argon gas.

  8. Sterilization of bacterial endospores by an atmospheric-pressure argon plasma jet

    SciTech Connect

    Uhm, Han S.; Lim, Jin P.; Li, Shou Z.

    2007-06-25

    Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. However, the spore-killing efficiency of the atmospheric-pressure argon-oxygen jet depends very sensitively on the oxygen concentration in the argon gas.

  9. Depleted argon from underground sources

    SciTech Connect

    Back, H.O.; Alton, A.; Calaprice, F.; Galbiati, C.; Goretti, A.; Kendziora, C.; Loer, B.; Montanari, D.; Mosteiro, P.; Pordes, S.; /Fermilab

    2011-09-01

    Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic {sup 39}Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in {sup 39}Ar. In Cortez Colorado a CO{sub 2} well has been discovered to contain approximately 500ppm of argon as a contamination in the CO{sub 2}. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N{sub 2}, and He mixture, from the CO{sub 2} through chromatographic gas separation. The N{sub 2} and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.

  10. Review of the US Consumer Product Safety Commission's health effects and exposure assessment documents on nitrogen dioxide. Report of the Clean Air Scientific Advisory Committee. Final report

    SciTech Connect

    Not Available

    1988-05-09

    At the request of the Consumer Product Safety Commission, the Clean Air Scientific Advisory Committee conducted a review on the potential health hazards associated with exposure to 0.1 to 1.0 ppm nitrogen dioxide generated by unvented indoor combustion sources. The committee concluded that: (1) repeated peak exposures at concentrations of 0.3 ppm of nitrogen dioxide may cause health effects in some individuals; (2) the population groups that appear most sensitive to nitrogen dioxide exposure include children, chronic bronchitics, asthmatics, and individuals with emphysema; and (3) the most direct evidence regarding lung damage associated with nitrogen dioxide is obtained from animal studies.

  11. Simulation study on nitrogen vibrational and translational temperature in air breakdown plasma generated by 110 GHz focused microwave pulse

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2017-01-01

    We report a simulation study on nitrogen vibrational and translational temperature in 3 μs pulse 110 GHz microwave air breakdown at pressure from 1 Torr to 100 Torr. The one-dimensional model is based on a self-consistent solution to Helmholtz equation for microwave field, electron density equation, and the average energy equation for electrons, nitrogen vibrational, and translational degrees. The breakdown threshold is calculated from the transmitted microwave profile, and it agrees well with that from experiment. The spatio-temporal characteristics of vibrational and translational temperature are shown, and the peak values at the end of pulse are compared to the results fitted from optical emission spectroscopy. The dependences of vibrational and translational temperature on normalized microwave fields and gas pressure are investigated, and the underlying mechanisms are unveiled.

  12. Cellular Attachment and Differentiation on Titania Nanotubes Exposed to Air- or Nitrogen-Based Non-Thermal Atmospheric Pressure Plasma

    PubMed Central

    Seo, Hye Yeon; Kwon, Jae-Sung; Choi, Yu-Ri; Kim, Kwang-Mahn; Choi, Eun Ha; Kim, Kyoung-Nam

    2014-01-01

    The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ), elicited from one of two different gas sources (nitrogen and air), to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in cellular activity

  13. Prediction of hydrodynamics and chemistry of confined turbulent methane-air flames with attention to formation of oxides of nitrogen

    NASA Technical Reports Server (NTRS)

    Elghobashi, S.; Spalding, D. B.; Srivatsa, S. K.

    1977-01-01

    A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a tubular combustor is presented. A numerical procedure for the solution of the governing differential equations is described, and models for chemical equilibrium and chemical kinetics calculations are presented. The chemical equilibrium model is used to characterize the hydrocarbon reactions. The chemical kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor consists of a cylindrical duct of varying cross sections with concentric streams of gaseous fuel and air entering the duct at one end. Four sample cases with specified inlet and boundary conditions are considered, and the results are discussed

  14. Simultaneous observation of rotational coherent Stokes Raman scattering and coherent anti-Stokes Raman scattering in air and nitrogen

    NASA Technical Reports Server (NTRS)

    Snow, J. B.; Chang, R. K.; Zheng, J. B.; Leipertz, A.

    1983-01-01

    Rotational coherent Stokes Raman scattering (CSRS) and coherent anti-Stokes Raman scattering (CARS) in air and in nitrogen were observed simultaneously by using broadband generation and detection. In the broadband technique used, the entire CARS and CSRS spectrum was generated in a single laser pulse; the CSRS and CARS signals were dispersed by a spectrograph and detected simultaneously by an optical multichannel analyzer. A three-dimensional phase-matching geometry was used to achieve spatial resolution of the CSRS and CARS beams from the input beams. Under resonant conditions, similar experiments may provide a means of investigating the possible interaction between the CSRS and CARS processes in driving the rotational levels.

  15. Tribological characteristics of nitrogen (N+) implanted iron

    NASA Technical Reports Server (NTRS)

    Jones, W. R.; Ferrante, J.

    1982-01-01

    The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed.

  16. Tribological characteristics of nitrogen (N+) implanted iron

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Ferrante, J.

    1983-01-01

    The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed. Previously announced in STAR as N82-24322

  17. The Liquid Argon Purity Demonstrator

    SciTech Connect

    Adamowski, M.; Carls, B.; Dvorak, E.; Hahn, A.; Jaskierny, W.; Johnson, C.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Stancari, M.; Tope, T.; Voirin, E.; Yang, T.

    2014-07-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  18. Proton Scattering on Liquid Argon

    NASA Astrophysics Data System (ADS)

    Bouabid, Ryan; LArIAT Collaboration

    2017-01-01

    LArIAT (Liquid Argon In A Test-beam) is a liquid argon time projection chamber (LArTPC) positioned in a charged particle beamline whose primary purpose is to study the response of LArTPC's to charged particle interactions. This previously unmeasured experimental data will allow for improvement of Monte Carlo simulations and development of identification techniques, important for future planned LArTPC neutrino experiments. LArIAT's beamline is instrumented to allow for the identification of specific particles as well as measurement of those particles' incoming momenta. Among the particles present in the beamline, the analysis presented here focuses on proton-Argon interactions. This study uses particle trajectories and calorimetric information to identify proton-Argon interaction candidates. We present preliminary data results on the measurement of the proton-Argon cross-section. Liquid Argon In A Test Beam. The work is my analysis made possible through the efforts of LArIAT detector, data, and software.

  19. Atmospheric argon contamination of ocean island basalt olivine phenocrysts

    NASA Astrophysics Data System (ADS)

    Parley, K. A.; Craig, H.

    1994-06-01

    40Ar/ 36Ar and helium and argon concentrations have been repeatedly measured on olivine phenocrysts in a single tholeiitic basalt (PIN-12) from the Juan Fernandez hotspot. Forty olivine splits were analyzed by crushing of bulk samples or laser fusion of single crystals. The measured 40Ar/ 36Ar ratios span a very large range (400-7700) and are consistent with binary mixing of two argon components. Unlike argon, helium in repeated measurements of this single basalt flow has a reproducible isotopic ratio, 17 times the air 3He/ 4He value. It is unlikely that such large variations in 40Ar/ 36Ar represent microscale mantle heterogeneity. Rather the results indicate highly variable mixing proportions of a mantle-derived radiogenic argon component ( 40Ar/ 36Ar ≫ 7700) and an isotopically air-like endmember that is almost certainly an atmospheric contaminant. This air-like constituent cannot be removed by physical and chemical treatments of the olivines. Analysis of individual crystals by laser fusion shows that both the radiogenic and the contaminant components are in fluid inclusions. Siting of the contaminant in inclusions requires the addition of airderived noble gases to hotspot magmas prior to or during emplacement, a process that may occur by assimilation of altered crust during crustal storage or, alternatively, by direct addition of air or seawater to the magma. In either case the olivines must continue to trap argon, presumably by fracture annealing and/or bubble enclosure, after the contaminating event. If atmospheric contamination is a general phenomenon, the 40Ar/ 36Ar composition of olivines (and possibly of basalt glasses as well) must be only a lower limit for the mantle source ratio. With the exception of helium, the other noble gases may be similarly compromised. Our results support contentions that lavas with near-atmospheric noble gas compositions reflect severe atmospheric contamination, rather than the air-like signature of an undegassed primitive

  20. Kinetics of excited states and radicals in a nanosecond pulse discharge and afterglow in nitrogen and air

    NASA Astrophysics Data System (ADS)

    Shkurenkov, Ivan; Burnette, David; Lempert, Walter R.; Adamovich, Igor V.

    2014-12-01

    The present kinetic modelling calculation results provide key new insights into the kinetics of vibrational excitation of nitrogen and plasma chemical reactions in nanosecond pulse, ‘diffuse filament’ discharges in nitrogen and dry air at a moderate energy loading per molecule, ˜0.1 eV per molecule. It is shown that it is very important to take into account Coulomb collisions between electrons because they change the electron energy distribution function and, as a result, strongly affect populations of excited states and radical concentrations in the discharge. The results demonstrate that the apparent transient rise of N2 ‘first level’ vibrational temperature after the discharge pulse, as detected in the experiments, is due to the net downward V-V energy transfer in N2-N2 collisions, which increases the N2(X 1Σ, v = 1) population. Finally, a comparison of the model's predictions with the experimental data shows that NO formation in the afterglow occurs via reactive quenching of multiple excited electronic levels of nitrogen molecule, N2\\ast , by O atoms. ) published in this volume, which focuses on the kinetic modelling of the experiments. This paper presents the results of the experiments.

  1. Performance evaluation of direct forced-air total solids and Kjeldahl total nitrogen methods: 1990 through 1995.

    PubMed

    Lynch, J M; Barbano, D M; Healy, P A; Fleming, J R

    1997-01-01

    Results from collaborative studies of the performance of the direct forced-air oven-drying method for determination of milk total solids content (AOAC Method 990.20) and the Kjeldahl total nitrogen method for determination of milk total nitrogen content (AOAC Method 991.20) were published in 1989 and 1990, respectively. Method performance was characterized by using the harmonized ISO/IU-PAC/AOAC guidelines for method validation, and the methods now have final action status. During 1990 through 1995, the split sample collaborative study format was used to monitor the performance of these methods as part of a multilaboratory quality assurance program. Seven blind duplicate milk materials were sent from a central laboratory once every 2 months to participating laboratories. Data were analyzed with the same statistical procedures used in the original collaborative studies. Compared with the original collaborative study, the repeatability and reproducibility of the oven-drying method improved over time. For the Kjeldahl total nitrogen method, within-laboratory repeatability improved slightly, whereas between-laboratory reproducibility was similar to but not always as good as in the original study. The results demonstrate that the statistical protocol for collaborative studies can be used effectively as the basis for a multilaboratory quality assurance program and that the method performance achieved in a collaborative study can be maintained and even improved with time.

  2. Agreement of land use regression models with personal exposure measurements of particulate matter and nitrogen oxides air pollution.

    PubMed

    Montagne, Denise; Hoek, Gerard; Nieuwenhuijsen, Mark; Lanki, Timo; Pennanen, Arto; Portella, Meritxell; Meliefste, Kees; Eeftens, Marloes; Yli-Tuomi, Tarja; Cirach, Marta; Brunekreef, Bert

    2013-08-06

    Land use regression (LUR) models are often used to predict long-term average concentrations of air pollutants. Little is known how well LUR models predict personal exposure. In this study, the agreement of LUR models with measured personal exposure was assessed. The measured components were particulate matter with a diameter smaller than 2.5 μm (PM2.5), soot (reflectance of PM2.5), nitrogen oxides (NOx), and nitrogen dioxide (NO2). In Helsinki, Utrecht, and Barcelona, 15 volunteers (from semiurban, urban background, and traffic sites) followed prescribed time activity patterns. Per participant, six 96 h outdoor, indoor, and personal measurements spread over three seasons were conducted. Soot LUR models were significantly correlated with measured average outdoor and personal soot concentrations. Soot LUR models explained 39%, 44%, and 20% of personal exposure variability (R(2)) in Helsinki, Utrecht, and Barcelona. NO2 LUR models significantly predicted outdoor concentrations and personal exposure in Utrecht and Helsinki, whereas NOx and PM2.5 LUR models did not predict personal exposure. PM2.5, NO2, and NOx models were correlated with personal soot, the component least affected by indoor sources. LUR modeled and measured outdoor, indoor, and personal concentrations were highly correlated for all pollutants when data from the three cities were combined. This study supports the use of intraurban LUR models for especially soot in air pollution epidemiology.

  3. Development of a low-cost atmospheric non-thermal plasma jet and its characteristics in air and nitrogen

    NASA Astrophysics Data System (ADS)

    Allam, Tarek M.; Ahmed, Kamal M.; Abouelatta, Mohamed A.; Ward, Sayed A.; Lashin, Ahmed A.; Soliman, Hanaa M.

    2016-10-01

    This paper deals with the development of a low-cost atmospheric non-thermal plasma jet (ANPJ) which was designed and operated previously in our laboratory. The purpose of the developed design with a small size less than 4% of the previous volume is to obtain a more portable device which holds promise for various fields of applications. The discharge is operated separately with compressed air and nitrogen gas with flow rates varied within the range of 3-18 L/min. The plasma plume length and thickness are measured as a function of the gas flow rate and input voltage Vinput within the range of 3-18 L/min and 2-6 kV respectively. The results showed that for nitrogen gas, the maximum values of the plume length and thickness are 20 mm and 1.3 mm respectively at a flow rate of 12 L/min and Vinput = 6 kV. Results of electrical characterization at Vinput = 6 kV such as discharge voltage, discharge current, the mean consumed power and energy showed that the maximum values of these parameters are obtained at a flow rate of 12 L/min. The developed design is found to be saving up to 65.47% and 68.54% of the consumed power compared to the previous design in the case of air and N2 respectively. The new proposed configuration for the developed ANPJ offers more suitable characteristics than the earlier designs, especially for nitrogen gas.

  4. Nitrogen-Doped Carbon as a Cathode Material for Lithium-air Batteries (Postprint)

    DTIC Science & Technology

    2010-04-01

    desorption isotherms has been conducted and all isotherms show adsorption hysteresis indicating the presence of mesopores . The Brunauer-Emmett...uptake above the relative pressure ratio of 0.80 has been observed in BET isotherm and is due to the condensation of nitrogen in a mesoporous carbon

  5. Addressing Air, Land & Water Nitrogen Issues under Changing Climate Trends & Variability

    EPA Science Inventory

    The climate of western U.S. dairy producing states is anticipated to change significantly over the next 50 to 75 years. A multimedia modeling system based upon the “nitrogen cascade” concept has been configured to address three aspects of sustainability (environmenta...

  6. 75 FR 31711 - Approval and Promulgation of Air Quality Implementation Plans; Delaware; Control of Nitrogen...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-04

    ... Heaters at Petroleum Refineries in order to require new and/or additional controls on industrial boilers and process heaters with heat input capacities of equal to or greater than 200 million British thermal... Nitrogen Oxide Emissions From Industrial Boilers and Process Heaters at Petroleum Refineries...

  7. Nitrogen Index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a need to improve the management of nitrogen inputs to agricultural systems because they increase the potential for losses of reactive nitrogen to the environment, resulting in negative impacts to water and air resources. There is a need to reduce nitrate leaching, emissions of N2O from agr...

  8. Changes in a surface of polycrystalline aluminum upon bombardment with argon ions

    NASA Astrophysics Data System (ADS)

    Ashkhotov, O. G.; Ashkhotova, I. B.; Bliev, A. P.; Magkoev, T. T.; Krymshokalova, D. A.

    2014-10-01

    The interaction between argon ions and a natural oxide layer of polycrystalline aluminum is studied via Auger electron (AE) and electron energy loss (EEL) spectroscopy. It is found that bombardment with argon ions whose energy is lower than the Al2O3 sputtering threshold results in the accumulation of bombarding ions in interstitial surface voids, thus forming a supersaturated solid solution of target atoms and bombarding ions of argon and nitrogen entrapped by the ion beam from the residual gas of the working chamber of the spectrometer.

  9. Characteristics of Knock in Hydrogen-Oxygen-Argon SI Engine

    SciTech Connect

    Killingsworth, N; Rapp, V; Flowers, D; Aceves, S; Chen, J; Dibble, R

    2010-02-23

    A promising approach for improving the efficiency of internal combustion engines is to employ a working fluid with a high specific heat ratio such as the noble gas argon. Moreover, all harmful emissions are eliminated when the intake charge is composed of oxygen, nonreactive argon, and hydrogen fuel. Previous research demonstrated indicated thermal efficiencies greater than 45% at 5.5 compression ratio in engines operating with hydrogen, oxygen, and argon. However, knock limits spark advance and increasing the efficiency further. Conditions under which knock occurs in such engines differs from typical gasoline fueled engines. In-cylinder temperatures using hydrogen-oxygen-argon are higher due to the high specific heat ratio and pressures are lower because of the low compression ratio. Better understanding of knock under these conditions can lead to operating strategies that inhibit knock and allow operation closer to the knock limit. In this work we compare knock with a hydrogen, oxygen, and argon mixture to that of air-gasoline mixtures in a variable compression ratio cooperative fuels research (CFR) engine. The focus is on stability of knocking phenomena, as well as, amplitude and frequency of the resulting pressure waves.

  10. Properties of Laser Produced TMAE Plasma Admixed with Air Constituents, Nitrogen and Noble Gases

    NASA Astrophysics Data System (ADS)

    Ding, Guowen; Scharer, John; Kelly, Kurt

    1999-10-01

    A high initial density (> 10^13 cm-3) and a large volume (hundreds of cm^3) plasma is created by a 193 nm laser ionization of an organic molecule, tetrakis(dimethyl-amino)ethylene(TMAE). The properties of this plasma mixed with nitrogen and noble gases are studied. Fast probe measurements which include a detailed considerations of probe structure, probe surface cleaning, shielding, probe perturbation, frequency response, temporal and spatial resolutions, dummy probe corrections and noise analysis will be described. Electron densities obtained by this method are independent on the ion species mixture. A plasma emission diagnostic is used to estimate plasma densities for the higher admixture pressures. Electron density and temperature vs. time for various TMAE, nitrogen and noble gas pressures and laser power will be presented. The role of super-excited and metastable states in the decay process will also be discussed.

  11. Air pollution and changes in forest nitrogen status: Fog and rain deposition and nitrogen losses from forested watersheds in the San Bernardino Mountains. Final report

    SciTech Connect

    Fenn, M.E.; Poth, M.A.

    1998-08-01

    The primary objective of this project was to examine the effects of N deposition on mixed conifer forests in southern California. Studies were conducted at selected sites an air pollution gradient in the San Bernardino Mountains (SBM). The main tasks were: (1) to measure N deposition to the forest in fog and throughfall, (2) to determine spatial and temporal patterns of nitrate export in stream water, and (3) to quantify trace gas fluxes from soil at sites with high and low N deposition. Fog was found to be an important N source at the western end of the SMB due to his high frequency and presence at elevated concentrations. N deposition from throughfall was found to be similar to levels in forests where adverse effects have occurred. Annual fluxes of N from soil were 18-times higher at the western end of the SBM than at the eastern end. The data provide evidence of forest nitrogen saturation caused by the deposition of anthropogenic pollutants over a multi-decade period in the SBM.

  12. Statistical summary and trend evaluation of air quality data for Cleveland, Ohio in 1967 to 1971: Total suspended particulate, nitrogen dioxide, and sulfur dioxide

    NASA Technical Reports Server (NTRS)

    Neustadter, H. E.; Sidik, S. M.; Burr, J. C., Jr.

    1972-01-01

    Air quality data for Cleveland, Ohio, for the period of 1967 to 1971 were collated and subjected to statistical analysis. The total suspended particulate component is lognormally distributed; while sulfur dioxide and nitrogen dioxide are reasonably approximated by lognormal distributions. Only sulfur dioxide, in some residential neighborhoods, meets Ohio air quality standards. Air quality has definitely improved in the industrial valley, while in the rest of the city, only sulfur dioxide has shown consistent improvement. A pollution index is introduced which displays directly the degree to which the environmental air conforms to mandated standards.

  13. Experimental Air Warming of a Stylosanthes capitata, Vogel Dominated Tropical Pasture Affects Soil Respiration and Nitrogen Dynamics

    PubMed Central

    Gonzalez-Meler, Miquel A.; Silva, Lais B. C.; Dias-De-Oliveira, Eduardo; Flower, Charles E.; Martinez, Carlos A.

    2017-01-01

    Warming due to global climate change is predicted to reach 2°C in tropical latitudes. There is an alarming paucity of information regarding the effects of air temperature on tropical agroecosystems, including foraging pastures. Here, we investigated the effects of a 2°C increase in air temperature over ambient for 30 days on an established tropical pasture (Ribeirão Preto, São Paulo, Brazil) dominated by the legume Stylosanthes capitata Vogel, using a T-FACE (temperature free-air controlled enhancement) system. We tested the effects of air warming on soil properties [carbon (C), nitrogen (N), and their stable isotopic levels (δ13C and δ15N), as well as soil respiration and soil enzymatic activity] and aboveground characteristics (foliar C, N, δ13C, δ15N, leaf area index, and aboveground biomass) under field conditions. Results show that experimental air warming moderately increased soil respiration rates compared to ambient temperature. Soil respiration was positively correlated with soil temperature and moisture during mid-day (when soil respiration was at its highest) but not at dusk. Foliar δ13C were not different between control and elevated temperature treatments, indicating that plants grown in warmed plots did not show the obvious signs of water stress often seen in warming experiments. The 15N isotopic composition of leaves from plants grown at elevated temperature was lower than in ambient plants, suggesting perhaps a higher proportion of N-fixation contributing to tissue N in warmed plants when compared to ambient ones. Soil microbial enzymatic activity decreased in response to the air warming treatment, suggesting a slower decomposition of organic matter under elevated air temperature conditions. Decreased soil enzyme capacity and increases in soil respiration and plant biomass in plots exposed to high temperature suggest that increased root activity may have caused the increase seen in soil respiration in this tropical pasture. This response

  14. Excretory nitrogen metabolism and defence against ammonia toxicity in air-breathing fishes.

    PubMed

    Chew, S F; Ip, Y K

    2014-03-01

    With the development of air-breathing capabilities, some fishes can emerge from water, make excursions onto land or even burrow into mud during droughts. Air-breathing fishes have modified gill morphology and morphometry and accessory breathing organs, which would tend to reduce branchial ammonia excretion. As ammonia is toxic, air-breathing fishes, especially amphibious ones, are equipped with various strategies to ameliorate ammonia toxicity during emersion or ammonia exposure. These strategies can be categorized into (1) enhancement of ammonia excretion and reduction of ammonia entry, (2) conversion of ammonia to a less toxic product for accumulation and subsequent excretion, (3) reduction of ammonia production and avoidance of ammonia accumulation and (4) tolerance of ammonia at cellular and tissue levels. Active ammonia excretion, operating in conjunction with lowering of ambient pH and reduction in branchial and cutaneous NH₃ permeability, is theoretically the most effective strategy to maintain low internal ammonia concentrations. NH₃ volatilization involves the alkalization of certain epithelial surfaces and requires mechanisms to prevent NH₃ back flux. Urea synthesis is an energy-intensive process and hence uncommon among air-breathing teleosts. Aestivating African lungfishes detoxify ammonia to urea and the accumulated urea is excreted following arousal. Reduction in ammonia production is achieved in some air-breathing fishes through suppression of amino acid catabolism and proteolysis, or through partial amino acid catabolism leading to alanine formation. Others can slow down ammonia accumulation through increased glutamine synthesis in the liver and muscle. Yet, some others develop high tolerance of ammonia at cellular and tissue levels, including tissues in the brain. In summary, the responses of air-breathing fishes to ameliorate ammonia toxicity are many and varied, determined by the behaviour of the species and the nature of the environment in

  15. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  16. Tree-Ring Nitrogen Isotopes As Environmental Monitoring Tools - Inferring Air Quality Changes And Climate Effects

    NASA Astrophysics Data System (ADS)

    Savard, M. M.; Begin, C.; Smirnoff, A.; Marion, J.

    2008-12-01

    Anthropogenic emissions of atmospheric nitrogen greatly increased over the last 150 years, however the monitoring of nitrous oxide concentration in North America started only recently, generally during the last 30 years. Could the geochemical characteristics of tree rings be used to infer past changes in nitrogen cycles of temperate regions? To address this question we use long-term series (125 years) of nitrogen stable isotopes (δ15N) obtained from rings of pine (Pinus strobus) and beech (Fagus grandifolia) trees in the Montreal region (western Quebec), and of beech specimens in the Georgian Bay Islands National Park (central Ontario). Reliability tests of N concentrations in wood treated for removal of soluble materials reveal that the reproducibility from tree to tree is poor, and that the concentrations in both Pine and Beech trees change in the heartwood-sapwood transition zones. We therefore reject N concentration as environmental indicator. Alternatively, the N stable isotopes pass all reliability tests. In Montreal, short-term δ15N fluctuations correlate directly with precipitation and inversely with temperature. A long-term decreasing isotope trend suggests progressive changes in soil chemistry after 1951. A pedochemical change is also inferred for the Georgian Bay site on the basis of a positive δ15N trend initiated after 1971. At both sites, the long-term δ15N series correlate with a proxy for NOx emissions, and the δ13C values of the same ring series suggest that all studied trees have been stressed by phytotoxic pollutants. We propose that the contrasted long-term δ15N changes of Montreal and Georgian Bay reflect deposition of NOx emissions from cars and coal-power plants, with higher proportions from coal burning in Georgian Bay. This interpretation is conceivable because recent monitoring indicates that coal-power plant NOx emissions play an important role in the annual N budget in Ontario, but they seem negligible on the Quebec side. This

  17. Can citizen science produce good science? Testing the OPAL Air Survey methodology, using lichens as indicators of nitrogenous pollution.

    PubMed

    Tregidgo, Daniel J; West, Sarah E; Ashmore, Mike R

    2013-11-01

    Citizen science is having increasing influence on environmental monitoring as its advantages are becoming recognised. However methodologies are often simplified to make them accessible to citizen scientists. We tested whether a recent citizen science survey (the OPAL Air Survey) could detect trends in lichen community composition over transects away from roads. We hypothesised that the abundance of nitrophilic lichens would decrease with distance from the road, while that of nitrophobic lichens would increase. The hypothesised changes were detected along strong pollution gradients, but not where the road source was relatively weak, or background pollution relatively high. We conclude that the simplified OPAL methodology can detect large contrasts in nitrogenous pollution, but it may not be able to detect more subtle changes in pollution exposure. Similar studies are needed in conjunction with the ever-growing body of citizen science work to ensure that the limitations of these methods are fully understood.

  18. Modelling deposition and air concentration of reduced nitrogen in Poland and sensitivity to variability in annual meteorology.

    PubMed

    Kryza, Maciej; Dore, Anthony J; Błaś, Marek; Sobik, Mieczysław

    2011-04-01

    The relative contribution of reduced nitrogen to acid and eutrophic deposition in Europe has increased recently as a result of European policies which have been successful in reducing SO(2) and NO(x) emissions but have had smaller impacts on ammonia (NH(3)) emissions. In this paper the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model was used to calculate the spatial patterns of annual average ammonia and ammonium (NH(4)(+)) air concentrations and reduced nitrogen (NH(x)) dry and wet deposition with a 5 km × 5 km grid for years 2002-2005. The modelled air concentrations of NH(3) and dry deposition of NH(x) show similar spatial patterns for all years considered. The largest year to year changes were found for wet deposition, which vary considerably with precipitation amount. The FRAME modelled air concentrations and wet deposition are in reasonable agreement with available measurements (Pearson's correlation coefficients above 0.6 for years 2002-2005), and with spatial patterns of concentrations and deposition of NH(x) reported with the EMEP results, but show larger spatial gradients. The error statistics show that the FRAME model results are in better agreement with measurements if compared with EMEP estimates. The differences in deposition budgets calculated with FRAME and EMEP do not exceed 17% for wet and 6% for dry deposition, with FRAME estimates higher than for EMEP wet deposition for modelled period and lower or equal for dry deposition. The FRAME estimates of wet deposition budget are lower than the measurement-based values reported by the Chief Inspectorate of Environmental Protection of Poland, with the differences by approximately 3%. Up to 93% of dry and 53% of wet deposition of NH(x) in Poland originates from national sources. Over the western part of Poland and mountainous areas in the south, transboundary transport can contribute over 80% of total (dry + wet) NH(x) deposition. The spatial pattern of the relative contribution of

  19. Comparison of inclined plate sedimentation and dissolved air flotation for the minimisation of subsequent nitrogenous disinfection by-product formation.

    PubMed

    Chu, Wen-Hai; Gao, Nai-Yun; Templeton, Michael R; Yin, Da-Qiang

    2011-04-01

    The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV(254) by coagulation-DAF-filtration was superior to coagulation-IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV(254) were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7μgL(-1), respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3μgL(-1). However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN.

  20. Atmospheric deposition of nitrogen emitted in the Metropolitan Area of Buenos Aires to coastal waters of de la Plata River

    NASA Astrophysics Data System (ADS)

    Pineda Rojas, Andrea L.; Venegas, Laura E.

    The Metropolitan Area of Buenos Aires (MABA) is the third mega-city in Latin America. Atmospheric N emitted in the area deposits to coastal waters of de la Plata River. This study describes the parameterizations included in DAUMOD-RD (v.3) model to evaluate concentrations of nitrogen compounds (nitrogen dioxide, gaseous nitric acid and nitrate aerosol) and their total (dry and wet) deposition to a water surface. This model is applied to area sources and CALPUFF model to point sources of NO x in the MABA. The models are run for 3 years of hourly meteorological data, with a spatial resolution of 1 km 2. Mean annual deposition is 69, 728 kg-N year -1 over 2 339 km 2 of river. Dry deposition contributions of N-NO 2, N-HNO 3 and N-NO 3- to this value are 44%, 22% and 20%, respectively. Wet deposition of N-HNO 3 and N-NO 3- represents 3% and 11% of total annual value, respectively. This very low contribution results from the rare occurrence of rainy hours with wind blowing from the city to the river. Monthly dry deposition flux estimated for coastal waters of MABA varies between 7 and 13 kg-N km -2 month -1. These results are comparable to values reported for other coastal zones in the world.

  1. Femtosecond filament initiated, microwave heated cavity-free nitrogen laser in air

    NASA Astrophysics Data System (ADS)

    Kartashov, Daniil; Shneider, Mikhail N.

    2017-03-01

    We present the results of numerical modeling of the igniter-heater concept for initiation of standoff, cavity free lasing action in the atmosphere when a femtosecond laser filament is used for plasma generation (igniter) and a microwave heater provides electron-collision pumping of electronic states in molecular nitrogen. By solving numerically the kinetic equation for the energy distribution function of electrons, generated in a femtosecond laser filament and heated by a microwave beam, we identify the conditions enabling single-pass, standoff UV-laser from molecular nitrogen in the atmosphere. The plasma density, the minimum amplitude of the microwave field, and the small-signal gain, necessary to achieve the lasing, are determined. We demonstrate that lasing build up time can be minimized and efficiency improved by using elliptically polarized laser pulses for filamentation. It is shown that realization of the filament-igniter, microwave-heater concept of the sky laser at low altitudes would require a microwave source of hundreds of kilowatt-megawatt power. The required microwave power can be reduced by several orders of magnitude when the igniter-heater scheme is used at the 10-30 km range of altitudes.

  2. Simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese from electrolytic manganese residue by air under calcium oxide assist.

    PubMed

    Chen, Hongliang; Liu, Renlong; Shu, Jiancheng; Li, Wensheng

    2015-01-01

    Leaching tests of electrolytic manganese residue (EMR) indicated that high contents of soluble manganese and ammonia-nitrogen posed a high environmental risk. This work reports the results of simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese by air under calcium oxide assist. The ammonia-nitrogen stripping rate increased with the dosage of CaO, the air flow rate and the temperature of EMR slurry. Stripped ammonia-nitrogen was absorbed by a solution of sulfuric acid and formed soluble (NH4)2SO4 and (NH4)3H(SO4)3. The major parameters that effected soluble manganese precipitation were the dosage of added CaO and the slurry temperature. Considering these two aspects, the efficient operation conditions should be conducted with 8 wt.% added CaO, 60°C, 800 mL min(-1) air flow rate and 60-min reaction time. Under these conditions 99.99% of the soluble manganese was precipitated as Mn3O4, which was confirmed by XRD and SEM-EDS analyses. In addition, the stripping rate of ammonia-nitrogen was 99.73%. Leaching tests showed the leached toxic substances concentrations of the treated EMR met the integrated wastewater discharge standard of China (GB8978-1996).

  3. Correction of NPL-2013 estimate of the Boltzmann constant for argon isotopic composition and thermal conductivity

    NASA Astrophysics Data System (ADS)

    de Podesta, Michael; Yang, Inseok; Mark, Darren F.; Underwood, Robin; Sutton, Gavin; Machin, Graham

    2015-10-01

    In 2013, a team from NPL, Cranfield University and SUERC published an estimate of the Boltzmann constant based on precision measurements of the speed of sound in argon. A key component of our results was an estimate of the molar mass of the argon gas used in our measurements. To achieve this we made precision comparison measurements of the isotope ratios found in our experimental argon against the ratios of argon isotopes found in atmospheric air. We then used a previous measurement of the atmospheric argon isotope ratios to calibrate the relative sensitivity of the mass spectrometer to different argon isotopes. The previous measurement of the atmospheric argon isotope ratios was carried out at KRISS using a mass spectrometer calibrated using argon samples of known isotopic composition, which had been prepared gravimetrically. We report here a new measurement made at KRISS in October 2014, which directly compared a sample of our experimental gas against the same gravimetrically-prepared argon samples. We consider that this direct comparison has to take precedence over our previous more indirect comparison. This measurement implies a molar mass which is 2.73(60) parts in 106 lighter than our 2013 estimate, a shift which is seven times our 2013 estimate of the uncertainty in the molar mass. In this paper we review the procedures used in our 2013 estimate of molar mass; describe the 2014 measurement; highlight some questions raised by the large change in our estimate of molar mass; and describe how we intend to address the inconsistencies between them. We also consider the effect of a new estimate of the low pressure thermal conductivity of argon at 273.16 K. Finally we report our new best estimate of the Boltzmann constant with revised uncertainty, taking account of the new estimates for the molar mass and the thermal conductivity of the argon.

  4. Gas chromatographic method for measuring nitrogen dioxide and peroxyacetyl nitrate in air without compressed gas cylinders

    SciTech Connect

    Burkhardt, M.R.; Maniga, N.I.; Stedman, D.H.; Paur, R.J.

    1988-04-15

    A gas chromatographic technique that measures atmospheric concentrations of peroxyacetyl nitrate (PAN) and NO/sub 2/ has been developed that uses luminol-based chemiluminescence for detection. The carrier gas is air that has been scrubbed by passing it over FeSO/sub 4/, which eliminates the need for any compressed gas cylinders. A novel gas sampling system and time enable variable sample volumes of contaminated air to be injected. Ambient PAN and NO/sub 2/ measurements can be made every 40 s with detection limits of 0.12 ppb for PAN and 0.2 ppb for NO/sub 2/. Seven other atmospheric species, including ozone, gave no interference. Linear response was observed for NO/sub 2/ from 0.2 to 170 ppb and for PAN from 1 to 70 ppb.

  5. Insights into discharge argon-mediated biofilm inactivation.

    PubMed

    Traba, Christian; Chen, Long; Liang, Danni; Azzam, Robin; Liang, Jun F

    2013-01-01

    Formation of bacterial biofilms at solid-liquid interfaces creates numerous problems in biomedical sciences. Conventional sterilization and decontamination methods are not suitable for new and more sophisticated biomaterials. In this paper, the efficiency and effectiveness of gas discharges in the inactivation and removal of biofilms on biomaterials were studied. It was found that although discharge oxygen, nitrogen and argon all demonstrated excellent antibacterial and antibiofilm activity, gases with distinct chemical/physical properties underwent different mechanisms of action. Discharge oxygen- and nitrogen-mediated decontamination was associated with strong etching effects, which can cause live bacteria to relocate thus spreading contamination. On the contrary, although discharge argon at low powers maintained excellent antibacterial ability, it had negligible etching effects. Based on these results, an effective decontamination approach using discharge argon was established in which bacteria and biofilms were killed in situ and then removed from the contaminated biomaterials. This novel procedure is applicable for a wide range of biomaterials and biomedical devices in an in vivo and clinical setting.

  6. Influences of flame-vortex interactions on formation of oxides of nitrogen in curved methane-air diffusion flamelets

    SciTech Connect

    Card, J.M.; Ryden, R.; Williams, F.A.

    1996-05-01

    Previous work has identified a parabolic flamelet in a uniform flow as a useful model for studying flame-vortex interactions and has presented an asymptotic analysis of this flamelet structure for two-step reduced chemistry of the methane-air system. The present paper addresses production rates of oxides of nitrogen in this flamelet by one-step reduced-chemistry descriptions of both thermal and prompt mechanisms, for both two-step and three-step methane-air reduced chemistry, and also reports some results of calculations of production rates with a full-chemistry description of planar counterflow flames, for purposes of comparison. The comparisons suggest that the asymptotic approximations significantly overestimate production rates and fail as extinction is approached but give qualitatively correct trends away from extinction. These trends show that increasing the tip curvature of the flamelet increases the prompt contribution while decreasing the thermal contribution. It is concluded that more research is needed on both elementary rates and asymptotic descriptions, especially for the prompt mechanism.

  7. Analysis of Mexico City urban air pollution using nitrogen dioxide column density measurements from UV/Visible spectroscopy

    NASA Astrophysics Data System (ADS)

    Garcia Payne, D. G.; Grutter, M.; Melamed, M. L.

    2010-12-01

    The differential optical absorption spectroscopy method (DOAS) was used to get column densities of nitrogen dioxide (NO2) from the analysis of zenith sky UV/visible spectra. Since the optical path length provides critical information in interpreting NO2 column densities, in conjunction with NO2 column densities, the oxygen dimer (O4) column density was retrieved to give insight into the optical path length. We report observations of year round NO2 and O4 column densities (from august 2009 to september 2010) from which the mean seasonal levels and the daily evolution, as well as the occurrence of elevated pollution episodes are examined. Surface nitric oxide (NO) and NO2 from the local monitoring network, as well as wind data and the vertical aerosol density from continuous Lidar measurements are used in the analysis to investigate specific events in the context of local emissions from vehicular traffic, photochemical production and transport from industrial emissions. The NO2 column density measurements will enhance the understanding Mexico City urban air pollution. Recent research has begun to unravel the complexity of the air pollution problem in Mexico City and its effects not only locally but on a regional and global scale as well.

  8. Raman spectra of single walled carbon nanotubes at high temperatures: pretreating samples in a nitrogen atmosphere improves their thermal stability in air.

    PubMed

    Molina-Duarte, J; Espinosa-Vega, L I; Rodríguez, A G; Guirado-López, R A

    2017-03-08

    We present a combined experimental and theoretical study dedicated to analyzing the structural stability and chemical reactivity of single walled carbon nanotubes (SWCNTs) in the presence of air and nitrogen atmospheres in the temperature interval of 300-1000 K. The temperature dependence of the radial breathing mode (RBM) region of the Raman spectra is irreversible in the presence of air, but it is reversible up to 1000 K in a nitrogen atmosphere. Our density functional theory (DFT) calculations reveal that irreversibility is due to partial degradation of SWCNTs produced by dissociative chemical adsorption of molecular oxygen on intrinsic defects of the nanotube surface. Oxygen partially opens the nanotubes forming semi-tubes with a non-uniform diameter distribution observed by Raman scattering. In contrast, heating CNTs in a nitrogen atmosphere seems to lead to the formation of nitrogen-doped SWCNTs. Our DFT calculations indicate that in general the most common types of nitrogen doping (e.g., pyridinic, pyrrolic, and substitutional) modify the location of the RBM frequency, leading also to frequency shifts and intensity changes of the surrounding modes. However, by performing a systematic comparison between calculated and measured spectra we have been able to infer the possible adsorbed configurations adopted by N species on the nanotube surface. Interestingly, by allowing previously nitrogen-exposed SWCNTs to interact with air at different temperatures (up to 1000 K) we note that the RBM region remains nearly unperturbed, defining thus our nitrogen-pretreated SWCNTs as more appropriate carbon nanostructures for high temperature applications in realistic environments. We believe that we have implemented a post-growth heat-treatment process that improves the stability of carbon nanotubes preserving their diameter and inducing a defect-healing process of the carbon wall.

  9. Nitrogen responses in groundwater, surface water and air following nitrate action plans in the Netherlands and Denmark

    NASA Astrophysics Data System (ADS)

    Broers, H.; Rozemeijer, J.; Visser, A.; Kronvang, B.; Erisman, J. W.; Refsgaard, J.; Thorling, L.; Slomp, C. P.; Prommer, H.

    2012-12-01

    The emissions of nutrients to air and water tend to increase worldwide. Both The Netherlands and Denmark are notorious for large inputs of nutrients in intensive agricultural practice in the previous 60 years. However, both countries have established legislation and action programs to reduce the supply and impacts of nutrients to air, groundwater and surface waters since 1985. This presentation analyses the response of nitrogen in air, surface water and groundwater following these action programs over the period 1985-2010. Responses of agriculturally derived N in air show a significant and rapid decrease since the beginning of these programs. Responses of N concentrations in many Dutch and Danish agriculturally dominated watersheds are also rapid. A clear response of nitrate-N in groundwater was revealed by age dating the water and simulations show that this also leads to a quick response of N outflow to surface waters. The rapid response of surface water is contra dictionary to the generally accepted idea that the slow transport of the groundwater N pool tends to lengthen the time scales necessary for the full recovery of N concentrations in surface waters. We stipulate that the young and shallow component of groundwater flow can discharge previously applied N effectively which causes the improvement of shallow groundwater quality to be reflected in the quick surface water response. While delay of N discharge may be true for areas with thick unsaturated zones and very limited agricultural use close to water courses, this is clearly not the case for areas with pronounced groundwater-surface water interaction such as the Netherlands delta setting or the Danish estuarine setting. The Dutch and Danish results show that N fluxes towards air and water can be managed and effectively monitored, which may help to counteract the increasing nutrient emissions in other densely populated and intensively used parts of the world. In order to predict time scales for recovery, it

  10. Titanium-nitrogen reaction investigated for application to gettering systems

    NASA Technical Reports Server (NTRS)

    Arntzen, J. D.; Coleman, L. F.; Kyle, M. L.; Pierce, R. D.

    1968-01-01

    Titanium is one of several gettering materials available for removing nitrogen from inert gases. The reaction rate of titanium-metal sponge and nitrogen in argon-nitrogen mixtures was studied at 900 degrees C. The rate was found to depend upon the partial pressure of nitrogen in the gas phase. Mathematical relationships simulate titanium systems.

  11. Oxidative Nitration of Styrenes for the Recycling of Low-Concentrated Nitrogen Dioxide in Air.

    PubMed

    Hofmann, Dagmar; de Salas, Cristina; Heinrich, Markus R

    2015-09-21

    The oxidative nitration of styrenes in ethyl acetate represents a metal-free, environmentally friendly, and sustainable technique to recover even low concentrations of NO2 in air. Favorable features are that the product mixture comprising nitroalcohols, nitroketones, and nitro nitrates simplifies at lower concentrations of NO2 . Experiments in a miniplant-type 10 L wet scrubber demonstrated that the recycling technique is well applicable on larger scales at which initial NO2 concentrations of >10 000 ppm were reliably reduced to less than 40 ppm.

  12. Heterogeneous photochemical reactions of a propylene-nitrogen dioxide-metal oxide-dry air system

    NASA Astrophysics Data System (ADS)

    Takeuchi, Koji; Ibusuki, Takashi

    Photochemical reactions of a C 3H 6-NO 2-air system in the presence of metal oxide were investigated. The metal oxides showing strong photooxidation activity were found to be n-type semiconductor oxides with the energy band gap around 3 eV. Formation of cyano-compounds (HCN and CH 3CN) was also observed and the activity can be explained in terms of the adsorptivity of NO onto metal oxides. Coalfired fly ash as a model of mixed metal oxides was also examined and their photocatalytic action was discussed.

  13. Attainable superheat of argon-helium, argon-neon solutions.

    PubMed

    Baidakov, Vladimir G; Kaverin, Aleksey M; Andbaeva, Valentina N

    2008-10-16

    The method of lifetime measurement has been used to investigate the kinetics of spontaneous boiling-up of superheated argon-helium and argon-neon solutions. Experiments were made at a pressure of p = 1.5 MPa and concentrations up to 0.33 mol% in the range of nucleation rates from 10 (4) to 10 (8) s (-1) m (-3). The homogeneous nucleation regime has been distinguished. With good agreement between experimental data and homogeneous nucleation theory in temperature and concentration dependences of the nucleation rate, a systematic underestimation by 0.25-0.34 K has been revealed in superheat temperatures over the saturated line attained by experiment as compared with theoretical values calculated in a macroscopic approximation. The revealed disagreement between theory and experiment is connected with the dependence of the properties of new-phase nuclei on their size.

  14. Experimental investigations of argon and xenon ion sources

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1975-01-01

    The multipole thruster was used to investigate the use of argon and xenon propellants as possible alternatives to the electric thruster propellants of mercury and cesium. The multipole approach was used because of its general high performance level. The design employed, using flat and cylindrical rolled sections of sheet metal, was selected for ease of fabrication, design, assembly, and modification. All testing was conducted in a vacuum facility and the pumping was accomplished by a 0.8 m diffusion pump together with liquid nitrogen cooled liner. Minimum discharge losses were in the 200-250 ev. ion range for both argon and xenon. Flatness parameters were typically in the 0.70-0.75 range.

  15. Argon metastable dynamics and lifetimes in a direct current microdischarge

    SciTech Connect

    Stefanović, Ilija; Kuschel, Thomas; Schröter, Sandra; Böke, Marc

    2014-09-21

    In this paper we study the properties of a pulsed dc microdischarge with the continuous flow of argon. Argon metastable lifetimes are measured by tunable diode laser absorption spectroscopy (TDLAS) and are compared with calculated values which yield information about excitation and de-excitation processes. By increasing the gas flow-rate about 5 times from 10 to 50 sccm, the Ar{sup m} lifetime increases from 1 to 5 μs due to the reduction of metastable quenching with gas impurities. Optical emission spectroscopy reveals nitrogen and water molecules as the main gas impurities. The estimated N₂ density [N₂]=0.1% is too low to explain the measured metastable lifetimes. Water impurity was found to be the main de-excitation source of argon metastable atoms due to high quenching coefficients. The water impurity level of [H₂O]=0.15% to 1% is sufficient to bring calculated metastable lifetimes in line with experiments. The maximum value of water content in the discharge compared to the argon atoms is estimated to approximately 6%, due to the large surface to volume ratio of the microdischarge. The current pulse releases the water molecules from the electrode surface and they are either re-adsorbed in the time between 0.4 ms for [H₂O]=1% and 2.6 ms for [H₂O]=0.15% or pumped out of the discharge with the speed equal to the gas flow-rate. Depending on its partial pressure, the water impurity re-adsorption time is of the order of magnitude or less then the argon gas residence time.

  16. [Oxygen metabolism in the body during substitution of nitrogen by helium in the air].

    PubMed

    Troshikhin, G V; Isaakian, L A; Bekirova, G G

    1975-01-01

    The total gas exchange, body temperature, content of free oxygen in the quadriceps muscle and its changes upon oxygen inhalation of a known dosage (oxygen test) were measured in the Wistar rats during their one-hour exposure to a helium-oxygen atmosphere (21%) at 25 degrees C. In this atmosphere the animals displayed a 1.8 degrees decline in the body temperature, a 20.5% increase in the gas exchange and a 26% decrease of oxygen in the muscular tissue as compared with the respective parameters in the air. After the experiment during the first 20 min exposure to the normal atmosphere oxygen tests were 10-15% lower than before the experiment. These findings give evidence for an increase of oxygen exchange in the muscles of animals exposed to the helium-oxygen atmosphere at a temperature below the comfortable level.

  17. Investigation of hydrogen-air ignition sensitized by nitric oxide and by nitrogen dioxide

    NASA Technical Reports Server (NTRS)

    Slack, M.; Grillo, A.

    1977-01-01

    The sensitization of stoichiometric hydrogen-air ignition by NO, NO2 and a mixture of NO and NO2 was investigated behind reflected shock waves in a shock tube. Induction times were measured in pressure range 0.27 to 2.0 atm, temperature range 800 to 1500 K, and for NO or NO2 mole percent between 0.0 and 4.5. Addition of both NO and NO2 reduced the measured induction times. The experimental data are interpreted in terms of H2-O2-NO(x) oxidation reaction mechanisms. The influence of NO(x) upon a supersonic combustion ramjet combustor test, conducted in an arc-heated facility, is assessed.

  18. Carbon and nitrogen removal from glucose-glycine melanoidins solution as a model of distillery wastewater by catalytic wet air oxidation.

    PubMed

    Phuong Thu, Le; Michèle, Besson

    2016-06-05

    Sugarcane molasses distillery wastewater contains melanoidins, which are dark brown recalcitrant nitrogenous polymer compounds. Studies were carried out in batch mode to evaluate Pt and Ru supported catalysts in the Catalytic Wet Air Oxidation (CWAO) process of a synthetic melanoidins solution, prepared by stoichiometric reaction of glucose with glycine. The addition of a catalyst slightly improved TOC removal compared with the non-catalytic reaction, and especially promoted the conversion of ammonium produced from organically-bound nitrogen in melanoidins to molecular nitrogen and nitrate. The selectivity to N2 attained 89% in the presence of the Pt catalysts in the reaction conditions used (TOC=2200mgL(-1), TN=280mgL(-1), 0.5g catalyst loaded with 3% metal, 210°C, 70bar total air pressure). To avoid leaching of the active metal by organically-bound nitrogen, the reaction was very efficiently performed in a two-step reaction consisting in WAO to convert nitrogen into ammonium, before the introduction of a catalyst.

  19. Trends of nitrogen oxides in ambient air in nine European cities between 1999 and 2010

    NASA Astrophysics Data System (ADS)

    Henschel, Susann; Le Tertre, Alain; Atkinson, Richard W.; Querol, Xavier; Pandolfi, Marco; Zeka, Ariana; Haluza, Daniela; Analitis, Antonis; Katsouyanni, Klea; Bouland, Catherine; Pascal, Mathilde; Medina, Sylvia; Goodman, Patrick G.

    2015-09-01

    Legislation controlling vehicle emissions has been credited with a general downward trend in NOx (NO2+NO) concentrations in Europe since the 1990's. However, recent studies suggest that traffic (roadside) (TR) NO2 concentrations have not decreased as expected, and in some cases increased, most likely due to the use of oxidation catalysts and particle filters in diesel vehicles (EURO III, IV, V, VI). In this study we describe the time trends in NOx, NO2 and NO concentrations in 9 European cities comparing TR and urban background (UB) monitoring locations. In each city, we collected hourly city-specific NOx, NO, and NO2 data from one TR and one UB monitoring site for each year. We describe hourly, weekly, seasonal and inter-annual patterns for periods corresponding to the implementation dates of various EURO vehicle emission standards regulating NOx emissions. The diurnal patterns in all 9 cities strongly reflected morning and evening traffic. In addition, lower weekend concentrations were observed. The NOx concentrations from the TR sites remain unchanged in the majority of the cities over the study period. When stratified by 3 time periods according to the implementation of the EURO standards, an increasing NO2/NOx ratio in 7/9 cities with time was noted. However, over the same time period the NO/NO2 ratio decreased in 8/9 cities. A permanent inversion of the NO/NO2 ratio was observed to occur in 2003 in 5/9 cities. Our analyses of temporal and diurnal patterns of NOx in European cities show reductions in concentrations consistent with reductions in primary emissions likely arising from the implementation of successive EURO standards. The generally constant or increasing NO2 concentrations in the majority of the cities assessed over the study period underline the need of further regulative measures to meet the air quality standards and consequently to minimise adverse effects on human health. The ongoing collection and analysis of pollution concentrations across

  20. [TESTING THE PROTECTIVE PROPERTIES OF ARGON DURING SUBACUTE EXPOSURE TO HYPOXIC HYPOXIA].

    PubMed

    Soldatov, P E; Dadasheva, O A; Gurieva, T S; Markin, A A; Tatarkin, S V; Nosovskii, A M; Smirnov, I A; Tiurin-Kuzmin, A Iu; Shulagin, Yu A; Smolenskaia, T S; Grishin, V I

    2015-01-01

    Previously it has been shown that argon has a stimulating effect on biological processes including, specifically, strong protective properties during exposure to acute (1-4 hrs.) hypoxic hypoxia. Experiments with animals under hypoxia gradually growing over 3 to 7 days may give insight into mechanisms of the argon protective action. Purpose of the work was to explore character and severity of developing disorders, to attempt their prognosis and to test potentiality of argon as a protector from the effects of subacute hypoxic exposure. In two series of experiments Wistar male rats were housed in pressure chambers with different rates of O2 reduction without argon and with argon in concentration of 32-38%. Oxygen reduction from 20.9 to 9.0% in 3 days led to the death of 50% animals. Oxygen reduction to 12.0% in 7 days and one day in low-oxygen atmosphere was harmless for animals. Argon in air makes the response to hypoxia almost twice as sharp on virtually every level (red blood system, physiological, morphological and biochemical shifts) validating the concept that argon acts as a stimulator. In context of the most critical processes of adaptation to hypoxia--activation of blood formation and lipid metabolism--this sharpening of the response results in depletion of body resources and instigates irreversible shifts.

  1. Porous nitrogen-doped carbon nanosheet on graphene as metal-free catalyst for oxygen reduction reaction in air-cathode microbial fuel cells.

    PubMed

    Wen, Qing; Wang, Shaoyun; Yan, Jun; Cong, Lijie; Chen, Ye; Xi, Hongyuan

    2014-02-01

    Porous nitrogen-doped carbon nanosheet on graphene (PNCN) was used as an alternative cathode catalyst for oxygen reduction reaction (ORR) in air-cathode microbial fuel cells (MFCs). Here we report a novel, low-cost, scalable, synthetic method for preparation of PNCN via the carbonization of graphite oxide-polyaniline hybrid (GO-PANI), subsequently followed by KOH activation treatment. Due to its high concentration of nitrogen and high specific surface area, PNCN exhibited an excellent catalytic activity for ORR. As a result, the maximum power density of 1159.34mWm(-2) obtained with PNCN catalyst was higher than that of Pt/C catalyst (858.49mWm(-2)) in a MFC. Therefore, porous nitrogen-doped carbon nanosheet could be a good alternative to Pt catalyst in MFCs.

  2. Determination of chlorpyrifos in air, leaves and soil from a greenhouse by gas-chromatography with nitrogen-phosphorus detection, high-performance liquid chromatography and capillary electrophoresis.

    PubMed

    Guardino, X; Obiols, J; Rosell, M G; Farran, A; Serra, C

    1998-10-09

    Chlorpyrifos was determined in air, leaves and soil in a greenhouse in order to establish performance differences between gas-chromatography with nitrogen-phosphorus detection (GC-NPD) and high-performance liquid chromatographic and capillary electrophoretic methods and to assess the farm workers' risk of overexposure due to air exposure and/or skin contact with this compound. Results obtained indicate that the three analytical techniques, with the specific procedures described, can be used, although only GC-NPD provides an operative limit of detection in air. Chlorpyrifos levels in air are dependent on time and greenhouse ventilation, whereas it remains for a long time on leaf surfaces and soil. As a consequence, specific instructions can be established for farm workers in order to avoid skin and respiratory exposure to chlorpyrifos.

  3. Effect of inlet-air humidity, temperature, pressure, and reference Mach number on the formation of oxides of nitrogen in a gas turbine combustor

    NASA Technical Reports Server (NTRS)

    Marchionna, N. R.; Diehl, L. A.; Trout, A. M.

    1973-01-01

    Tests were conducted to determine the effect of inlet air humidity on the formation of oxides of nitrogen (NOx) from a gas turbine combustor. Combustor inlet air temperature ranged from 506 K (450 F) to 838 K (1050 F). The tests were primarily run at a constant pressure of 6 atmospheres and reference Mach number of 0.065. The NOx emission index was found to decrease with increasing inlet air humidity at a constant exponential rate: NOx = NOx0e-19H (where H is the humidity and the subscript 0 denotes the value at zero humidity). the emission index increased exponentially with increasing normalized inlet air temperature to the 1.14 power. Additional tests made to determine the effect of pressure and reference Mach number on NOx showed that the NOx emission index varies directly with pressure to the 0.5 power and inversely with reference Mach number.

  4. An experimental and numerical study of nitrogen oxide formation mechanisms in ammonia-hydrogen-air flames

    NASA Astrophysics Data System (ADS)

    Kumar, Praveen

    quantitatively. The NOx predictions by all the three chemical mechanisms are observed to be in fairly good agreement with the measured NOx, qualitatively, however predictions are found to be 3 to 4 times higher than the measurements for both lean and rich H 2/NH3 premixed flames. For laminar H2/NH3 diffusion flames, detailed 2-D comparisons of in-situ NO measurements with the 2-D simulated NO using the Tian, GRI-Mech3.0 and modified GRI-Mech chemical mechanisms are performed and found to differ from the measured NO by approximately an order of magnitude. For NH3 seeded H2/air diffusion flames, GRI-Mech3.0 seemed to overpredict NO by more than an order of magnitude and failed to capture the fundamental flame characteristics, such as the flame length variation with increasing NH3 in the fuel mixture. On the other hand, the predicted NO profiles by the Tian mechanism were not only found to be in better agreement with the measured NO, but they also captured the in-flame NO distribution as well, both qualitatively and quantitatively. Overall, the Tian mechanism is found to be the superior chemical mechanism to capture the NOx formation chemistry in NH3 seeded flames.

  5. Prospects for photosensitive dopants in liquid argon

    SciTech Connect

    Anderson, D.F.

    1990-12-01

    Evidence is presented that the addition of a few ppM of a photosensitive dopant to a U/liquid argon or Pb/liquid argon calorimeter will make a substantial reduction in the e/{pi} ratio. Previous results indicating high voltage problems and no change in the e/{pi} ratio in tests of photosensitive dopants with the Fermilab D0 experiment's U/liquid argon tests calorimeter are also explained. 13 refs., 3 figs.

  6. Liquid Argon Calorimetry for ATLAS

    NASA Astrophysics Data System (ADS)

    Robinson, Alan

    2008-05-01

    This summer, the largest collaborative physics project since the Manhattan project will go online. One of four experiments for the Large Hadron Collider at CERN in Geneva, ATLAS, employs over 2000 people. Canadians have helped design, construct, and calibrate the liquid argon calorimeters for ATLAS to capture the products of the high energy collisions produced by the LHC. From an undergraduate's perspective, explore how these calorimeters are made to handle their harsh requirement. From nearly a billion proton-proton collisions a second, physicists hope to discover the Higgs boson and other new fundamental particles.

  7. Breakdown voltage of metal-oxide resistors in liquid argon

    SciTech Connect

    Bagby, L. F.; Gollapinni, S.; James, C. C.; Jones, B. J.P.; Jostlein, H.; Lockwitz, S.; Naples, D.; Raaf, J. L.; Rameika, R.; Schukraft, A.; Strauss, T.; Weber, M. S.; Wolbers, S. A.

    2014-11-07

    We characterized a sample of metal-oxide resistors and measured their breakdown voltage in liquid argon by applying high voltage (HV) pulses over a 3 second period. This test mimics the situation in a HV-divider chain when a breakdown occurs and the voltage across resistors rapidly rise from the static value to much higher values. All resistors had higher breakdown voltages in liquid argon than their vendor ratings in air at room temperature. Failure modes range from full destruction to coating damage. In cases where breakdown was not catastrophic, subsequent breakdown voltages were lower in subsequent measuring runs. One resistor type withstands 131 kV pulses, the limit of the test setup.

  8. Enhancement of the EUV emission of a metallic capillary discharge operated with argon ambient gas

    SciTech Connect

    Chan, L. S. Tan, D. Saboohi, S. Yap, S. L. Wong, C. S.

    2014-03-05

    In this work, the metallic capillary discharge is operated with two different ambients: air and argon. In the experiments reported here, the chamber is first evacuated to 10{sup −5} mbar. The discharge is initiated by the transient hollow cathode effect generated electron beam, with either air ambient or argon ambient at 10{sup −4} mbar. The bombardment of electron beam at the tip of the stainless steel anode gives rise to a metallic vapor, which is injected into the capillary and initiates the main discharge through the capillary. The EUV emission is measured for different discharge voltages for both conditions and compared. It is found that the metallic capillary discharge with argon ambientis able to produce higher EUV energy compared to that with air ambient.

  9. The photosynthetic and stomatal response of Medicago sativa cv. saranac to free-air CO{sub 2} enrichment (F.A.C.E.) and nitrogen

    SciTech Connect

    Bridson, N.P.

    1996-08-01

    Plots of Medicago sativa cv. saranac were grown in the field at ambient (355 {mu}mol CO{sub 2} mol{sup -1} air) or elevated (600{mu}mol CO{sub 2} mol{sup -1} air) CO{sub 2} concentrations. High (200kg yr{sup -1}) or low (20kg yr{sup -1}) nitrogen levels were applied to two isogeneic lines, one able and one unable to use nitrogen fixing bacteria. Plants were in the second year of field growth. Exposure to elevated CO{sub 2} was via a Free-Air CO{sub 2} Enrichment System (FACE). Elevated CO{sub 2} increased diurnal assimilation by between 12% and 92%. Analysis of A/C{sub i} responses showed that effective nitrogen fertilisation was more important to rubisCO and RuBP activity than elevated CO{sub 2}. No acclimation was consistently observed. Leaves lower down the canopy were found to have lower Vc{sub max} and J{sub max} values, though age may be the cause of the latter effect. FACE conditions have only a small effect on these responses. There was some evidence found for the down-regulation of photosynthesis in the late afternoon. The FACE conditions had no affect on stomatal density but did increase epidermal cell density.

  10. Application of nitrogen-doped carbon powders as low-cost and durable cathodic catalyst to air-cathode microbial fuel cells.

    PubMed

    Shi, Xinxin; Feng, Yujie; Wang, Xin; Lee, He; Liu, Jia; Qu, Youpeng; He, Weihua; Kumar, S M Senthil; Ren, Nanqi

    2012-03-01

    Given few in-depth studies available on the application of nitrogen-doped carbon powders (NDCP) to air-cathode microbial fuel cells (ACMFCs), a low-cost and durable catalyst of NDCP was prepared and used as cathodic catalyst of ACMFCs. Compared to the untreated carbon powders, the N-doped treatment significantly increased the maximum power density (MPD) of ACMFC. A two-step pretreatment of heat treatment and hydrochloric acid immersion can further obviously increase the MPD. With a reasonably large loading of catalyst, the MPD of NDCP based ACMFC was comparable to that of carbon-supported platinum (Pt/C) based ACMFC, while the cost was dramatically reduced. The pretreatment increased the key nitrogen functional groups, pyridinic-like and pyrrolic-like nitrogen. A third new key nitrogen functional group, nitrogen oxide, was discovered and the mechanism of its contribution was explained. Compared to the inherent deterioration problem of Pt/C, NDCP exhibited high stability and was superior for long-term operation of ACMFCs.

  11. Influences of flame-vortex interactions on formation of oxides of nitrogen in curved methane-air diffusion flamelets

    SciTech Connect

    Card, J.M.; Ryden, R.; Williams, F.A.

    1994-01-01

    To improve knowledge of production rates of nitrogen oxides in turbulent diffusion flames in reaction-sheet regimes, an analytical investigation is made of the structure of a parabolic flamelet. The mixture-fraction field, scalar dissipation rate and gas velocity relative to the flamelet in the vortex are related to flame curvature at the parabolic tip. Flame structure for major species and temperature is described by rate-ratio asymptotics based on two-step and three-step reduced chemical-kinetic mechanisms. Production rates by prompt, thermal and nitrous-oxide mechanisms are obtained from one-step reduced-chemistry approximations that employ steady states for all reaction intermediaries. For sufficiently large streamwise separation distances between isoscalar surfaces, it is found that equilibrium conditions are closely approached near the flame tip, and the thermal mechanism dominates there, but the prompt mechanism always dominates in the wings, away from the tip, where the highest rates of scalar dissipation occur. Increasing the tip curvature increases the Peclet number and the prompt contribution while decreasing the thermal contribution. At 1 atm and ambient temperatures of 300 K, the prompt mechanism always dominates the total production rate in the parabolic flamelet, and, perhaps surprisingly, the rate of the nitrous-oxide mechanism is faster than that of the thermal mechanism and varies with the tip curvature and with scalar dissipation in the same manner as that of the prompt mechanism, different from that of the thermal mechanism. Conclusion reached is that Zel`dovich NO is relatively insignificant in hydrocarbon-air mixtures in reaction-sheet regimes.

  12. The statistical evaluation and comparison of ADMS-Urban model for the prediction of nitrogen dioxide with air quality monitoring network.

    PubMed

    Dėdelė, Audrius; Miškinytė, Auksė

    2015-09-01

    In many countries, road traffic is one of the main sources of air pollution associated with adverse effects on human health and environment. Nitrogen dioxide (NO2) is considered to be a measure of traffic-related air pollution, with concentrations tending to be higher near highways, along busy roads, and in the city centers, and the exceedances are mainly observed at measurement stations located close to traffic. In order to assess the air quality in the city and the air pollution impact on public health, air quality models are used. However, firstly, before the model can be used for these purposes, it is important to evaluate the accuracy of the dispersion modelling as one of the most widely used method. The monitoring and dispersion modelling are two components of air quality monitoring system (AQMS), in which statistical comparison was made in this research. The evaluation of the Atmospheric Dispersion Modelling System (ADMS-Urban) was made by comparing monthly modelled NO2 concentrations with the data of continuous air quality monitoring stations in Kaunas city. The statistical measures of model performance were calculated for annual and monthly concentrations of NO2 for each monitoring station site. The spatial analysis was made using geographic information systems (GIS). The calculation of statistical parameters indicated a good ADMS-Urban model performance for the prediction of NO2. The results of this study showed that the agreement of modelled values and observations was better for traffic monitoring stations compared to the background and residential stations.

  13. Surface-Tuned Co3O4 Nanoparticles Dispersed on Nitrogen-Doped Graphene as an Efficient Cathode Electrocatalyst for Mechanical Rechargeable Zinc-Air Battery Application.

    PubMed

    Singh, Santosh K; Dhavale, Vishal M; Kurungot, Sreekumar

    2015-09-30

    The most vital component of the fuel cells and metal-air batteries is the electrocatalyst, which can facilitate the oxygen reduction reaction (ORR) at a significantly reduced overpotential. The present work deals with the development of surface-tuned cobalt oxide (Co3O4) nanoparticles dispersed on nitrogen-doped graphene as a potential ORR electrocatalyst possessing some unique advantages. The thermally reduced nitrogen-doped graphene (NGr) was decorated with three different morphologies of Co3O4 nanoparticles, viz., cubic, blunt edged cubic, and spherical, by using a simple hydrothermal method. We found that the spherical Co3O4 nanoparticle supported NGr catalyst (Co3O4-SP/NGr-24h) has acquired a significant activity makeover to display the ORR activity closely matching with the state-of-the-art Pt supported carbon (PtC) catalyst in alkaline medium. Subsequently, the Co3O4-SP/NGr-24h catalyst has been utilized as the air electrode in a Zn-air battery, which was found to show comparable performance to the system derived from PtC. Co3O4-SP/NGr-24h catalyst has shown several hours of flat discharge profile at the discharge rates of 10, 20, and 50 mA/cm(2) with a specific capacity and energy density of ~590 mAh/g-Zn and ~840 Wh/kg-Zn, respectively, in the primary Zn-air battery system. In conjunction, Co3O4-SP/NGr-24h has outperformed as an air electrode in mechanical rechargeable Zn-air battery as well, which has shown consistent flat discharge profile with minimal voltage loss at a discharge rate of 50 mA/cm(2). The present results, thus demonstrate that the proper combination of the tuned morphology of Co3O4 with NGr will be a promising and inexpensive material for efficient and ecofriendly cathodes for Zn-air batteries.

  14. Dynamics of ionization processes in high-pressure nitrogen, air, and SF{sub 6} during a subnanosecond breakdown initiated by runaway electrons

    SciTech Connect

    Tarasenko, V. F. Beloplotov, D. V.; Lomaev, M. I.

    2015-10-15

    The dynamics of ionization processes in high-pressure nitrogen, air, and SF{sub 6} during breakdown of a gap with a nonuniform distribution of the electric field by nanosecond high-voltage pulses was studied experimentally. Measurements of the amplitude and temporal characteristics of a diffuse discharge and its radiation with a subnanosecond time resolution have shown that, at any polarity of the electrode with a small curvature radius, breakdown of the gap occurs via two ionization waves, the first of which is initiated by runaway electrons. For a voltage pulse with an ∼500-ps front, UV radiation from different zones of a diffuse discharge is measured with a subnanosecond time resolution. It is shown that the propagation velocity of the first ionization wave increases after its front has passed one-half of the gap, as well as when the pressure in the discharge chamber is reduced and/or when SF{sub 6} is replaced with air or nitrogen. It is found that, at nitrogen pressures of 0.4 and 0.7 MPa and the positive polarity of the high-voltage electrode with a small curvature radius, the ionization wave forms with a larger (∼30 ps) time delay with respect to applying the voltage pulse to the gap than at the negative polarity. The velocity of the second ionization wave propagating from the plane electrode is measured. In a discharge in nitrogen at a pressure of 0.7 MPa, this velocity is found to be ∼10 cm/ns. It is shown that, as the nitrogen pressure increases to 0.7 MPa, the propagation velocity of the front of the first ionization wave at the positive polarity of the electrode with a small curvature radius becomes lower than that at the negative polarity.

  15. Dynamics of ionization processes in high-pressure nitrogen, air, and SF6 during a subnanosecond breakdown initiated by runaway electrons

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Beloplotov, D. V.; Lomaev, M. I.

    2015-10-01

    The dynamics of ionization processes in high-pressure nitrogen, air, and SF6 during breakdown of a gap with a nonuniform distribution of the electric field by nanosecond high-voltage pulses was studied experimentally. Measurements of the amplitude and temporal characteristics of a diffuse discharge and its radiation with a subnanosecond time resolution have shown that, at any polarity of the electrode with a small curvature radius, breakdown of the gap occurs via two ionization waves, the first of which is initiated by runaway electrons. For a voltage pulse with an ˜500-ps front, UV radiation from different zones of a diffuse discharge is measured with a subnanosecond time resolution. It is shown that the propagation velocity of the first ionization wave increases after its front has passed one-half of the gap, as well as when the pressure in the discharge chamber is reduced and/or when SF6 is replaced with air or nitrogen. It is found that, at nitrogen pressures of 0.4 and 0.7 MPa and the positive polarity of the high-voltage electrode with a small curvature radius, the ionization wave forms with a larger (˜30 ps) time delay with respect to applying the voltage pulse to the gap than at the negative polarity. The velocity of the second ionization wave propagating from the plane electrode is measured. In a discharge in nitrogen at a pressure of 0.7 MPa, this velocity is found to be ˜10 cm/ns. It is shown that, as the nitrogen pressure increases to 0.7 MPa, the propagation velocity of the front of the first ionization wave at the positive polarity of the electrode with a small curvature radius becomes lower than that at the negative polarity.

  16. ATLAS liquid argon calorimeter front end electronics

    NASA Astrophysics Data System (ADS)

    Buchanan, N. J.; Chen, L.; Gingrich, D. M.; Liu, S.; Chen, H.; Damazio, D.; Densing, F.; Duffin, S.; Farrell, J.; Kandasamy, S.; Kierstead, J.; Lanni, F.; Lissauer, D.; Ma, H.; Makowiecki, D.; Muller, T.; Radeka, V.; Rescia, S.; Ruggiero, R.; Takai, H.; Wolniewicz, K.; Ghazlane, H.; Hoummada, A.; Hervas, L.; Hott, T.; Wilkens, H. G.; Ban, J.; Boettcher, S.; Brooijmans, G.; Chi, C.-Y.; Caughron, S.; Cooke, M.; Copic, K.; Dannheim, D.; Gara, A.; Haas, A.; Katsanos, I.; Parsons, J. A.; Simion, S.; Sippach, W.; Zhang, L.; Zhou, N.; Eckstein, P.; Kobel, M.; Ladygin, E.; Auge, E.; Bernier, R.; Bouchel, M.; Bozzone, A.; Breton, D.; de la Taille, C.; Falleau, I.; Fournier, D.; Imbert, P.; Martin-Chassard, G.; Perus, A.; Richer, J. P.; Seguin Moreau, N.; Serin, L.; Tocut, V.; Veillet, J.-J.; Zerwas, D.; Colas, J.; Dumont-Dayot, N.; Massol, N.; Perrodo, P.; Perrot, G.; Wingerter-Seez, I.; Escalier, M.; Hubaut, F.; Laforge, B.; LeDortz, O.; Schwemling, Ph; Collot, J.; Dzahini, D.; Gallin-Martel, M.-L.; Martin, P.; Cwienk, W. D.; Fent, J.; Kurchaninov, L.; Citterio, M.; Mazzanti, M.; Tartarelli, F.; Bansal, V.; Boulahouache, C.; Cleland, W.; Liu, B.; McDonald, J.; Paolone, V.; Rabel, J.; Savinov, V.; Zuk, G.; Benslama, K.; Borgeaud, P.; de la Broïse, X.; Delagnes, E.; LeCoguie, A.; Mansoulié, B.; Pascual, J.; Teiger, J.; Dinkespiler, B.; Liu, T.; Stroynowski, R.; Ye, J.; Zarzhitsky, P.; Grahn, K.-J.; Hansson, P.; Lund-Jensen, B.; Chu, M. L.; Lee, S.-C.; Su, D. S.; Teng, P. K.; Braun, H. M.

    2008-09-01

    The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. This paper describes the architecture and implementation of the system of custom front end electronics developed for the readout of the ATLAS liquid argon calorimeters.

  17. Argon purge gas cooled by chill box

    NASA Technical Reports Server (NTRS)

    Spiro, L. W.

    1966-01-01

    Cooling argon purge gas by routing it through a shop-fabricated chill box reduces charring of tungsten inert gas torch head components. The argon gas is in a cooled state as it enters the torch and prevents buildup of char caused by the high concentrations of heat in the weld area during welding operations.

  18. New photosensitive dopants for liquid argon

    NASA Astrophysics Data System (ADS)

    Anderson, D. F.

    1986-05-01

    Thirteen photosensitive dopants for liquid argon are presented, and the criteria for selecting prospective new dopants are discussed. A substantial improvement in energy resolution for 5.5 MeV alpha particles is measured in liquid argon when a photosensitive dopant is added.

  19. Argon Triple-Point Device for Calibration of SPRTs

    NASA Astrophysics Data System (ADS)

    Kołodziej, B.; Manuszkiewicz, H.; Szmyrka-Grzebyk, A.; Lipiński, L.; Kowal, A.; Steur, P. P. M.; Pavese, F.

    2015-03-01

    This paper presents an apparatus for the calibration of long-stem platinum resistance thermometers at the argon triple point , designed at the Institute of Low Temperature and Structural Research, Poland (INTiBS). A hermetically sealed cell filled at the Istituto Nazionale di Ricerca Metrologica, Italy with high purity gas (6N) is the main element of this apparatus. The cell is placed in a cryostat fully immersed in liquid nitrogen. A temperature-controlled shield ensures the quasi-adiabatic condition needed for proper realization of the phase transition. A system for correcting the temperature distribution along the thermometer well is also implemented. The cell cooling and argon solidification is carried out by filling the thermometer well with liquid nitrogen. A LabVIEW computer program written at INTiBS automatically controls the triple-point realization process. The duration of a melting plateau in the apparatus lasts for about 24 h. The melting width for between 20 % and 80 % was mK. The reproducibility of the plateau temperature is better than.

  20. 75 FR 61486 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... of Sulfur AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of availability of... Standards for Oxides of Nitrogen and Oxides of Sulfur: Second External Review Draft (75 FR 57463, September... (summary of options for elements of the nitrogen oxides (NO X ) and sulfur oxides (SO X ) standard)....

  1. 75 FR 70258 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-17

    ... of Sulfur AGENCY: Environmental Protection Agency (EPA). ACTION: Extension of comment period. SUMMARY... Nitrogen and Oxides of Sulfur: Second External Review Draft (75 FR 57463, September 21, 2010). The EPA... additional table for Chapter 9 (summary of options for elements of the nitrogen oxides (NO X ) and...

  2. 75 FR 20595 - Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen and Oxides...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... of Sulfur AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of extension of comment... for Oxides of Nitrogen and Oxides of Sulfur: First External Review Draft (75 FR 11877; March 12, 2010... a proposal addressing the nitrogen oxides (NO X ) and sulfur oxides (SO X ) secondary...

  3. Evaluation of the first phase of sulfur dioxide and nitrogen oxides provisions of the 1990 Clean Air Act: a plant-based approach.

    PubMed

    Freedman, Martin; Jaggi, Bikki

    2002-03-01

    Electric power generating plants that use coal were among the key targets of Title IV of the 1990 Clean Air Act. Under the first phase of the act, 110 coal-fired electric power plants were required to reduce their sulfur dioxide emissions by 1995 and nitrogen oxide emissions by 1996. Phase 2 of the act requires even greater reduction of sulfur dioxide emissions by 2000 and nitrogen oxide emissions by 2008. This study examines whether the 107 targeted plants (three plants went off-line) have achieved the desired sulfur dioxide and nitrogen oxide emission levels. The analysis of sulfur dioxide is based on data from 1990, 1995, and 1999. The findings show that although sulfur oxide increased by 3% from 1995 to 1999, it decreased by 45% over the 1990-1999 period at the firm level for the targeted firms. The findings also indicate that the overall reduction in sulfur dioxide was achieved by utilizing low sulfur coal and by purchasing emission allowances. So far as nitrogen oxides are concerned, there has been a reduction of 14% over the 1990-1999 period, of which 7% was achieved during the 1995-1999 period. An evaluation of emissions at the plant level indicates that several plants do not meet the emissions level for sulfur dioxide or nitrogen oxides. These results provide a mixed scorecard for reduction in emissions both for sulfur dioxide and nitrogen oxides. Even though there is reduction in the emissions on an overall basis at the firm level, several plants that have not been able to reduce emissions deserve special attention to meet the goals of the act in reducing emissions.

  4. Porous nitrogen doped carbon fiber with churros morphology derived from electrospun bicomponent polymer as highly efficient electrocatalyst for Zn-air batteries

    NASA Astrophysics Data System (ADS)

    Park, Gi Su; Lee, Jang-Soo; Kim, Sun Tai; Park, Soojin; Cho, Jaephil

    2013-12-01

    Highly porous nitrogen doped carbon fibers like churros morphology are prepared from a simple and cost-effective fabrication process, electrospinning with bicomponent polymer consisting of polystyrene (PS) and polyacrylonitrile (PAN). From appropriate ratio of two polymer and pyrolysis at 1100 °C, newly churros morphology with extremely high surface area (1271 m2 g-1) is prepared. During carbonization, more unstable PS than PAN plays a critical role in forming such morphology by acting as sacrifice materials, thus providing additional formation of inner pores and outer etched surfaces. Furthermore, it demonstrates excellent electrocatalytic activity toward ORR, which is attributed to highly meso- and macro porous nitrogen-doped large surface area and enhanced graphitic-nitrogen groups of carbon fibers. For example, the performance of a Zn-air cell based on the nitrogen-doped porous carbon nanofibers exhibits a peak power density of 194 mW cm-2, comparable to that based on a commercial Pt/C catalyst (192 mW cm-2). Further, the generation of hydrogen peroxide ions (<20%) in a half cell is similar to that on the commercial Pt/C catalyst.

  5. A study of dielectric breakdown along insulators surrounding conductors in liquid argon

    SciTech Connect

    Lockwitz, Sarah; Jostlein, Hans

    2016-03-22

    High voltage breakdown in liquid argon is an important concern in the design of liquid argon time projection chambers, which are often used as neutrino and dark matter detectors. We have made systematic measurements of breakdown voltages in liquid argon along insulators surrounding negative rod electrodes where the breakdown is initiated at the anode. The measurements were performed in an open cryostat filled with commercial grade liquid argon exposed to air, and not the ultra-pure argon required for electron drift. While not addressing all high voltage concerns in liquid argon, these measurements have direct relevance to the design of high voltage feedthroughs especially for averting the common problem of flash-over breakdown. The purpose of these tests is to understand the effects of materials, of breakdown path length, and of surface topology for this geometry and setup. We have found that the only material-specific effects are those due to their permittivity. We have found that the breakdown voltage has no dependence on the length of the exposed insulator. Lastly, a model for the breakdown mechanism is presented that can help inform future designs.

  6. A study of dielectric breakdown along insulators surrounding conductors in liquid argon

    DOE PAGES

    Lockwitz, Sarah; Jostlein, Hans

    2016-03-22

    High voltage breakdown in liquid argon is an important concern in the design of liquid argon time projection chambers, which are often used as neutrino and dark matter detectors. We have made systematic measurements of breakdown voltages in liquid argon along insulators surrounding negative rod electrodes where the breakdown is initiated at the anode. The measurements were performed in an open cryostat filled with commercial grade liquid argon exposed to air, and not the ultra-pure argon required for electron drift. While not addressing all high voltage concerns in liquid argon, these measurements have direct relevance to the design of highmore » voltage feedthroughs especially for averting the common problem of flash-over breakdown. The purpose of these tests is to understand the effects of materials, of breakdown path length, and of surface topology for this geometry and setup. We have found that the only material-specific effects are those due to their permittivity. We have found that the breakdown voltage has no dependence on the length of the exposed insulator. Lastly, a model for the breakdown mechanism is presented that can help inform future designs.« less

  7. Nitrogen spark denoxer

    DOEpatents

    Ng, Henry K.; Novick, Vincent J.; Sekar, Ramanujam R.

    1997-01-01

    A NO.sub.X control system for an internal combustion engine includes an oxygen enrichment device that produces oxygen and nitrogen enriched air. The nitrogen enriched air contains molecular nitrogen that is provided to a spark plug that is mounted in an exhaust outlet of an internal combustion engine. As the nitrogen enriched air is expelled at the spark gap of the spark plug, the nitrogen enriched air is exposed to a pulsating spark that is generated across the spark gap of the spark plug. The spark gap is elongated so that a sufficient amount of atomic nitrogen is produced and is injected into the exhaust of the internal combustion engine. The injection of the atomic nitrogen into the exhaust of the internal combustion engine causes the oxides of nitrogen to be reduced into nitrogen and oxygen such that the emissions from the engine will have acceptable levels of NO.sub.X. The oxygen enrichment device that produces both the oxygen and nitrogen enriched air can include a selectively permeable membrane.

  8. Experimental Comparison of Capillary Pinching Discharge in Argon and Nitrogen

    NASA Astrophysics Data System (ADS)

    Jancarek, A.; Pina, L.; Vrbova, M.; Tamas, M.; Havlikova, R.; Palinek, S.; Vrba, P.; Kolacek, K.; Schmidt, J.; Strauss, J.

    Experiments with CAPEX-U apparatus were done to more understand the differences between Ar and N active media created during the pinch compression, respectively. Capillary discharge current, X-ray narrow band radiation and EUV spectrum temporal behavior were measured. Results of laboratory experiments for both gas fillings under various currents and initial pressures are shown. Computer simulations show that current quasi-period shortening and higher amplitude is needed.

  9. Optical and electrical characteristics of a single surface DBD micro-discharge produced in atmospheric-pressure nitrogen and synthetic air

    NASA Astrophysics Data System (ADS)

    Šimek, M.; Prukner, V.; Schmidt, J.

    2011-05-01

    Basic opto-electrical characteristics of a single micro-discharge generated in a surface DBD reactor with a coplanar electrode arrangement were studied with nanosecond time resolution. The discharge electrode geometry based on machinable glass-ceramic was optimized in order to get a system free of the circulating dielectric liquids that are frequently used to insulate and cool metallic electrodes. The build-up and decay of UV-vis-NIR emission by a single micro-discharge unaffected by concurrent or preceding discharge events was inspected during the first 10 µs of the micro-discharge evolution in nitrogen and in synthetic air. Obtained emission waveforms show a great similarity between the surface and volume streamers. The streamer volume-averaged N2(A) concentrations of ~8 × 1014 cm-3 were estimated at t = 1 µs decay time and concentrations of ~(2-4) × 1015 cm-3 were estimated during the streamer propagation phase in nitrogen.

  10. Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT): Overview of a wintertime air chemistry field study in the front range urban corridor of Colorado

    NASA Astrophysics Data System (ADS)

    Brown, Steven S.; Thornton, Joel A.; Keene, William C.; Pszenny, Alexander A. P.; Sive, Barkley C.; Dubé, William P.; Wagner, Nicholas L.; Young, Cora J.; Riedel, Theran P.; Roberts, James M.; Vandenboer, Trevor C.; Bahreini, Roya; Öztürk, Fatma; Middlebrook, Ann M.; Kim, Saewung; Hübler, Gerhard; Wolfe, Daniel E.

    2013-07-01

    The Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) field experiment took place during late winter, 2011, at a site 33 km north of Denver, Colorado. The study included fixed-height measurements of aerosols, soluble trace gases, and volatile organic compounds near surface level, as well as vertically resolved measurements of nitrogen oxides, aerosol composition, soluble gas-phase acids, and halogen species from 3 to 270 m above ground level. There were 1928 individual profiles during the three-week campaign to characterize trace gas and aerosol distributions in the lower levels of the boundary layer. Nitrate and ammonium dominated the ionic composition of aerosols and originated primarily from local or regional sources. Sulfate and organic matter were also significant and were associated primarily with longer-range transport to the region. Aerosol chloride was associated primarily with supermicron size fractions and was always present in excess of gas-phase chlorine compounds. The nighttime radical reservoirs, nitryl chloride, ClNO2, and nitrous acid, HONO, were both consistently present in nighttime urban air. Nitryl chloride was especially pronounced in plumes from large point sources sampled aloft at night. Nitrous acid was typically most concentrated near the ground surface and was the dominant contributor (80%) to diurnally averaged primary OH radical production in near-surface air. Large observed mixing ratios of light alkanes, both in near-surface air and aloft, were attributable to local emissions from oil and gas activities.

  11. Effects of initial climatic conditions on growth and accumulation of fluoride and nitrogen in leaves of two tropical tree species exposed to industrial air pollution.

    PubMed

    Furlan, Cláudia Maria; Domingos, Marisa; Salatino, Antonio

    2007-03-15

    Saplings of Tibouchina pulchra and Psidium guajava, cultivated under standardized soil conditions, were placed in two sites at Cubatão (state of São Paulo, southeast Brazil) to study the effects of air pollution on growth, biomass allocation and foliar nitrogen and fluoride concentrations. Thirty-six potted plants were maintained over two periods of one year (Jul/00 to Jun/01; Dec/00 to Nov/01) at each of two experimental sites with distinct levels of air pollution: Pilões River Valley (PV) with vegetation virtually unaffected by air pollution; and Mogi River Valley (MV) severely affected by pollutants released mainly by chemical, fertilizer, iron and steel industries. For both species, saplings growing at MV showed alterations of growth and biomass allocation, as well as increased leaf concentrations of nitrogen and fluoride. Comparing both experimental periods, the one starting in winter (the driest season in Southeastern Brazil) seemed to affect the saplings more severely, the differences of the measured parameters between MV and PV being higher than in the second period. Multivariate analysis revealed two groups of data: one representing the MV and the other the PV saplings. For both species, saplings growing at MV showed differences in chemical composition, growth and biomass allocation, compared with the PV saplings. The results suggested that seasonal conditions of the first months of sapling exposure (summer or winter) modulate the intensity of responses to pollution stress.

  12. 40Ar/39Ar systematics and argon diffusion in amber: implications for ancient earth atmospheres

    USGS Publications Warehouse

    Landis, G.P.; Snee, L.W.

    1991-01-01

    Argon isotope data indicate retained argon in bulk amber (matrix gas) is radiogenic [40Ar/39Ar ???32o] than the much more abundant surface absorbed argon [40Ar/39Ar ???295.5]. Neutron-induced 39Ar is retained in amber during heating experiments to 150?? -250??C, with no evidence of recoiled 39Ar found after irradiation. A maximum permissible volume diffusion coefficient of argon in amber (at ambient temperature) D???1.5 x 10-17 cm2S-1 is calculated from 39Ar retention. 40Ar/39Ar age calculations indicate Dominican Republic amber is ??? 45 Ma and North Dakota amber is ??? 89 Ma, both at least reasonable ages for the amber based upon stratigraphic and paleontological constraints and upon the small amount of radiogenic 40Ar. To date, over 300 gas analyses of ambers and resins of Cretaceous to Recent age that are geographically distributed among fifteen noted world locations identify mixtures of gases in different sites within amber (Berner and Landis, 1988). The presence of multiple mixing trends between compositionally distinct end-members gases within the same sample and evidence for retained radiogenic argon within the amber argue persuasivley against rapid exchange by diffusion of amber-contained gases with moder air. Only gas in primary bubbles entrapped between successive flows of tree resin has been interpreted as original "ancient air", which is an O2-rich end-member gas with air-like N2/Ar ratios. Gas analyses of these primary bubbles indicate atmospheric O2 levels in the Late Cretaceous of ??? 35%, and that atmospheric O2 dropped by early Tertiary time to near a present atmospheric level of 21% O2. A very low argon diffusion coefficient in amber persuasively argues for a gas in primary bubbles trapped in amber being ancient air (possibly modified only by O2 reaction with amber). ?? 1991.

  13. Kinetics of the formation of ozone and nitrogen oxides due to a pulsed microwave discharge in air

    NASA Astrophysics Data System (ADS)

    Larin, V. F.; Rumiantsev, S. A.

    1989-03-01

    The paper presents results of a numerical simulation of the kinetics of plasma-chemical processes induced by a single microwave pulse in the stratosphere. It is shown that the gas temperature is one of the main factors influencing the concentration ratio of ozone and nitrogen oxides formed under the effect of a microwave pulse. Long pulses, producing considerable gas heating, favor the formation of nitrogen oxides.

  14. Luminosity limits for liquid argon calorimetry

    NASA Astrophysics Data System (ADS)

    J, Rutherfoord; B, Walker R.

    2012-12-01

    We have irradiated liquid argon ionization chambers with betas using high-activity Strontium-90 sources. The radiation environment is comparable to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider. We measure the ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. We can operate these chambers either in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. From the transition point we indirectly extract the positive argon ion mobility.

  15. Assessing the air quality impact of nitrogen oxides and benzene from road traffic and domestic heating and the associated cancer risk in an urban area of Verona (Italy)

    NASA Astrophysics Data System (ADS)

    Schiavon, Marco; Redivo, Martina; Antonacci, Gianluca; Rada, Elena Cristina; Ragazzi, Marco; Zardi, Dino; Giovannini, Lorenzo

    2015-11-01

    Simulations of emission and dispersion of nitrogen oxides (NOx) are performed in an urban area of Verona (Italy), characterized by street canyons and typical sources of urban pollutants. Two dominant source categories are considered: road traffic and, as an element of novelty, domestic heaters. Also, to assess the impact of urban air pollution on human health and, in particular, the cancer risk, simulations of emission and dispersion of benzene are carried out. Emissions from road traffic are estimated by the COPERT 4 algorithm, whilst NOx emission factors from domestic heaters are retrieved by means of criteria provided in the technical literature. Then maps of the annual mean concentrations of NOx and benzene are calculated using the AUSTAL2000 dispersion model, considering both scenarios representing the current situation, and scenarios simulating the introduction of environmental strategies for air pollution mitigation. The simulations highlight potentially critical situations of human exposure that may not be detected by the conventional network of air quality monitoring stations. The proposed methodology provides a support for air quality policies, such as planning targeted measurement campaigns, re-locating monitoring stations and adopting measures in favour of better air quality in urban planning. In particular, the estimation of the induced cancer risk is an important starting point to conduct zoning analyses and to detect the areas where population is more directly exposed to potential risks for health.

  16. A controlling role for the air-sea interface in the chemical processing of reactive nitrogen in the coastal marine boundary layer.

    PubMed

    Kim, Michelle J; Farmer, Delphine K; Bertram, Timothy H

    2014-03-18

    The lifetime of reactive nitrogen and the production rate of reactive halogens in the marine boundary layer are strongly impacted by reactions occurring at aqueous interfaces. Despite the potential importance of the air-sea interface in serving as a reactive surface, few direct field observations are available to assess its impact on reactive nitrogen deposition and halogen activation. Here, we present direct measurements of the vertical fluxes of the reactant-product pair N2O5 and ClNO2 to assess the role of the ocean surface in the exchange of reactive nitrogen and halogens. We measure nocturnal N2O5 exchange velocities (Vex = -1.66 ± 0.60 cm s(-1)) that are limited by atmospheric transport of N2O5 to the air-sea interface. Surprisingly, vertical fluxes of ClNO2, the product of N2O5 reactive uptake to concentrated chloride containing surfaces, display net deposition, suggesting that elevated ClNO2 mixing ratios found in the marine boundary layer are sustained primarily by N2O5 reactions with aerosol particles. Comparison of measured deposition rates and in situ observations of N2O5 reactive uptake to aerosol particles indicates that N2O5 deposition to the ocean surface accounts for between 26% and 42% of the total loss rate. The combination of large Vex, N2O5 and net deposition of ClNO2 acts to limit NOx recycling rates and the production of Cl atoms by shortening the nocturnal lifetime of N2O5. These results indicate that air-sea exchange processes account for as much as 15% of nocturnal NOx removal in polluted coastal regions and can serve to reduce ClNO2 concentrations at sunrise by over 20%.

  17. 21 CFR 868.1075 - Argon gas analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Argon gas analyzer. 868.1075 Section 868.1075 Food... DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to measure the concentration of argon in a gas mixture to aid...

  18. 21 CFR 868.1075 - Argon gas analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Argon gas analyzer. 868.1075 Section 868.1075 Food... DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to measure the concentration of argon in a gas mixture to aid...

  19. 21 CFR 868.1075 - Argon gas analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Argon gas analyzer. 868.1075 Section 868.1075 Food... DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to measure the concentration of argon in a gas mixture to aid...

  20. 21 CFR 868.1075 - Argon gas analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Argon gas analyzer. 868.1075 Section 868.1075 Food... DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to measure the concentration of argon in a gas mixture to aid...

  1. 21 CFR 868.1075 - Argon gas analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Argon gas analyzer. 868.1075 Section 868.1075 Food... DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1075 Argon gas analyzer. (a) Identification. An argon gas analyzer is a device intended to measure the concentration of argon in a gas mixture to aid...

  2. Argon Diffusion in Pyroxene and Albite

    NASA Astrophysics Data System (ADS)

    Weirich, J. R.; Isachsen, C. E.; Johnson, J. R.; Swindle, T. D.

    2010-03-01

    Shock greatly raises the diffusivity of albite, and also explains why meteorites often have low activation energies. Unshocked pyroxene cannot explain the high temperature release of argon in meteorites, though shocked pyroxene is a possibility.

  3. Clinical periodontics with the argon laser

    NASA Astrophysics Data System (ADS)

    Finkbeiner, R. L.

    1995-04-01

    The argon laser has proven to be a valuable tool for the thermodynamic debridement of the periodontal lesion, incisions and tissue fusion. Illustrations of clinical applications and discussion of laser parameters will be provided.

  4. Iron-nitrogen-activated carbon as cathode catalyst to improve the power generation of single-chamber air-cathode microbial fuel cells.

    PubMed

    Pan, Yajun; Mo, Xiaoping; Li, Kexun; Pu, Liangtao; Liu, Di; Yang, Tingting

    2016-04-01

    In order to improve the performance of microbial fuel cell (MFC), iron-nitrogen-activated carbon (Fe-N-C) as an excellent oxygen reduction reaction (ORR) catalyst was prepared here using commercial activated carbon (AC) as matrix and employed in single chamber MFC. In MFC, the maximum power density increased to 2437±55 mW m(-2), which was 2 times of that with AC. The open circuit potential (OCP) of Fe-N-C cathode (0.47) was much higher than that of AC cathode (0.21 V). The R0 of Fe-N-C decreased by 47% from 14.36 Ω (AC) to 7.6 Ω (Fe-N-C). From X-ray photoelectron spectroscopy (XPS), pyridinic nitrogen, quaternary nitrogen and iron species were present, which played an important role in the ORR performance of Fe-N-C. These results demonstrated that the as-prepared Fe-N-C material provided a potential alternative to Pt in AC air cathode MFC for relatively desirable energy generation and wastewater treatment.

  5. Gas chromatograph analysis on closed air and nitrogen oxide storage atmospheres of recalcitrant seeds of Quercus Alba

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Storage of recalcitrant seeds remains an unsolved problem. This study investigated the quantitative gas analysis of nitrous oxide (N2O) and air atmospheres on the recalcitrant seeds of Quercus alba by using gas chromatograph. Ten seeds were placed in each sealed atmospheric system of air and 98/2% N...

  6. The distribution of odd nitrogen in the lower stratosphere and possible perturbations caused by stratospheric air transport

    NASA Technical Reports Server (NTRS)

    Isaksen, I. S. A.; Hesstvedt, E.

    1973-01-01

    In the lower stratosphere a significant production of odd nitrogen results from the reaction N2O + O(D-1) yields 2NO. Since the transport is relatively slow, odd nitrogen builds up with a maximum mixing ratio of 2 x 10 to the minus 8th power at 30 Km. Profiles of odd nitrogen, for different latitudes, winter and summer, are computed from one-dimensional transport models. Variations with latitude are small. Horizontal transport is therefore not believed to alter our results significantly. In order to evaluate the effect of odd nitrogen upon the ozone layer, NO(x) profiles are calculated. OH is here a key component, since it converts NO2 to HNO3. In the region where ozone is determined by chemistry rather than by transport (above 25 km), NO2 is found to be relatively abundant. The effect of stratospheric transport on the NO(x) distribution is shown to depend critically upon the height of emission. The effect increases by a factor of 5 or more for a change of flight level from 18 km to 23 km. This strong dependence should be duely considered when future stratospheric transport is discussed.

  7. Corrosion resistance and microstructure of nitrogen plasma source ion implanted bearing steel

    SciTech Connect

    Mente, K.; Baum, C.; Wang, W.; Zhang, L.; Booske, J.; Shohet, J.L.; Jacobs, J.; Freeman, D.; Perez-Albuerne, E.A.

    1996-12-31

    Feasibility of plasma source ion implantation (PSII) treatments for metal corrosion protection of bearing steel in humid environments has been investigated, following successful results with aluminum alloy. The bearing steel coupons have been treated by nitrogen PSII with a statistically designed range of processing conditions, including stage bias implant voltage, and dose. Corrosion properties of the implanted samples were tested using aerated distilled water (72, 168, and 720 hours), 90 F, 90% RH air (24, 120, 816, and 1,464 hours), and a nitric acid soak. The results are compared favorably with 400 C stainless steel, and 52100 steel with nitrogen and argon recoil-implanted chromium. Evidence is seen for an optimal process contour (low voltage-high dose; high voltage-low dose). Results from microstructure analysis will also be presented.

  8. New Measurement of ^39Ar in Underground Argon with a Low Background Liquid Argon Detector

    NASA Astrophysics Data System (ADS)

    Xu, Jingke

    2012-03-01

    A low background liquid argon detector has been developed for sensitive measurements of the beta radioactive ^39Ar in argon from underground sources. The measurement is motivated by the need to improve on earlier studies that showed no sign of ^39Ar in certain sources of underground argon, but with a limited sensitivity of ˜ 5% relative to ^39Ar in atmospheric argon[1]. We will report preliminary measurements taken with the low background detector that was commissioned and operated at the Kimballton Underground Research Facility (KURF) in Virginia. A combination of passive and active background reduction techniques resulted in a very low background and a null result with sensitivity to ^39Ar less than 1% of atmospheric. The results confirm that underground argon is well suited for direct detection of dark matter WIMPs. [4pt] [1] D. Acosta-Kane et al., Nucl. Instr. Meth. A 587:46 (2008)

  9. Accumulation of air in polymeric materials investigated by laser-induced breakdown spectroscopy

    SciTech Connect

    Yip, W. L.; Hermann, J.; Mothe, E.; Beldjilali, S.

    2012-03-15

    We report on spectroscopic analyses of plasmas produced by laser irradiation of nitrogen-free and nitrogen-containing polymer materials. Ultraviolet laser pulses of 5 ns duration and 4 mJ energy were focused onto the samples with a fluence of about 20 Jcm{sup -2}. The plasma emission was analyzed with an Echelle spectrometer equipped with a gated detector. Comparing the spectra recorded during ablation in air and argon, it is shown that the spectral line emission of atomic nitrogen originates from the excitation of the ambient air, whereas the CN molecular bands are essentially emitted from the ablation plume. Furthermore, the measurements demonstrate an additional contribution of nitrogen emission from the air molecules accumulated in the polymer. Storage under vacuum over a duration of the order of one day leads to the release of the absorbed air. As a consequence of the air absorption, the measurement of elemental composition of polymers via laser-induced breakdown spectroscopy is particularly difficult. Here, we quantify the atmospheric contribution to the plume emission during polymer analysis.

  10. Effects of oxygen concentration on atmospheric pressure dielectric barrier discharge in Argon-Oxygen Mixture

    NASA Astrophysics Data System (ADS)

    Li, Xuechun; Li, Dian; Wang, Younian

    2016-09-01

    A dielectric barrier discharge (DBD) can generate a low-temperature plasma easily at atmospheric pressure and has been investigated for applications in trials in cancer therapy, sterilization, air pollution control, etc. It has been confirmed that reactive oxygen species (ROS) play a key role in the processes. In this work, we use a fluid model to simulate the plasma characteristics for DBD in argon-oxygen mixture. The effects of oxygen concentration on the plasma characteristics have been discussed. The evolution mechanism of ROS has been systematically analyzed. It was found that the ground state oxygen atoms and oxygen molecular ions are the dominated oxygen species under the considered oxygen concentrations. With the oxygen concentration increasing, the densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. Increasing the oxygen concentration, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode. Project supported by the National Natural Science Foundation of China (Grant No. 11175034).

  11. Case report of fatal complication in prostatic cryotherapy. First reported death due to argon gas emboli.

    PubMed

    Sandomirsky, Marianna; Crifasi, Joseph A; Long, Christopher; Mitchell, Erik K

    2012-03-01

    We present the first reported fatality from argon gas emboli during prostate cryosurgery. The decedent underwent cryotherapy for prostate carcinoma using cryoablation probes which were cooled with argon and nitrous oxide and warmed with helium. Minutes into the procedure he experienced sudden cardiovascular collapse and could not be resuscitated. Postmortem examination was performed at the request of family and healthcare providers. Collection of tissues and blood samples had to be conducted carefully to capture suspected noble gases,argon, and helium. Specimens were submitted to Saint Louis University Forensic Toxicology Laboratory for toxicological examination and for evaluation of the composition of the gas retrieved from the vascular system.Gas chromatography mass spectrometric analyses confirmed argon in blood, brain, liver, and gas retrieved from the aorta. These samples had significant argon compared with room air also sent for comparison. The manner of death was accident. To date, there have been no intraoperative surgical fatalities reported from prostatic cryotherapy. We report such an unfortunate death to raise awareness in the medical community. We also describe how to collect and handle blood and tissue samples to submit for toxicological analysis in cases of volatile gas emboli.

  12. Participant-based monitoring of indoor and outdoor nitrogen dioxide, volatile organic compounds, and polycyclic aromatic hydrocarbons among MICA-Air households

    NASA Astrophysics Data System (ADS)

    Johnson, Markey M.; Williams, Ron; Fan, Zhihua; Lin, Lin; Hudgens, Edward; Gallagher, Jane; Vette, Alan; Neas, Lucas; Özkaynak, Halûk

    2010-12-01

    The Mechanistic Indicators of Childhood Asthma (MICA) study in Detroit, Michigan introduced a participant-based approach to reduce the resource burden associated with collection of indoor and outdoor residential air sampling data. A subset of participants designated as MICA-Air conducted indoor and outdoor residential sampling of nitrogen dioxide (NO 2), volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). This participant-based methodology was subsequently adapted for use in the Vanguard phase of the U.S. National Children's Study. The current paper examines residential indoor and outdoor concentrations of these pollutant species among health study participants in Detroit, Michigan. Pollutants measured under MICA-Air agreed well with other studies and continuous monitoring data collected in Detroit. For example, NO 2 and BTEX concentrations reported for other Detroit area monitoring were generally within 10-15% of indoor and outdoor concentrations measured in MICA-Air households. Outdoor NO 2 concentrations were typically higher than indoor NO 2 concentration among MICA-Air homes, with a median indoor/outdoor (I/O) ratio of 0.6 in homes that were not impacted by environmental tobacco smoke (ETS) during air sampling. Indoor concentrations generally exceeded outdoor concentrations for VOC and PAH species measured among non-ETS homes in the study. I/O ratios for BTEX species (benzene, toluene, ethylbenzene, and m/p- and o-xylene) ranged from 1.2 for benzene to 3.1 for toluene. Outdoor NO 2 concentrations were approximately 4.5 ppb higher on weekdays versus weekends. As expected, I/O ratios pollutants were generally higher for homes impacted by ETS. These findings suggest that participant-based air sampling can provide a cost-effective alternative to technician-based approaches for assessing indoor and outdoor residential air pollution in community health studies. We also introduced a technique for estimating daily concentrations at each

  13. Emissions of Nitrogen Oxides from the Testing of F404-GE-400 Engines at Naval Air Station, Lemoore, California

    DTIC Science & Technology

    1985-07-01

    Tables IV and V, NAPC-LR-81-10 F404-GE-400 Run Sheets, 8 March to 26 April 1985 APPENDIX B The Use of a Small Programmable Calculator for Estimation of...small programmable calculator to establish emission indexes and to estimate the amounts of nitrogen oxides produced during engine testing. 2. EMISSION...preparing this report, we used an HP-41CV programmable calculator . Appendix B explains how to use this calculator and gives the programs used to make

  14. Argon isotopic zoning in mantle phlogopite

    SciTech Connect

    Phillips, D.; Onstott, T.C.

    1988-06-01

    Incremental-heating and laser-probe /sup 40/Ar//sup 39/Ar analyses were performed on phlogopite extracted from a garnet-lherzolite mantle nodule entrained by the Precambrian (1200 Ma) Premier kimberlite, South Africa. The spatial resolution of the laser probe has enabled the characterization of argon isotopic zoning in a single phlogopite grain. An apparent age contour map records lower ages (1.2 Ga) along grain margins and high apparent ages (up to 2.4 Ga) at the core. The latter ages are caused by excess argon contamination and subsequent partial diffusive loss, and have no age significance. Comparison with step-heating results indicates that argon spatial distributions inferred from in-vacuo step-heating experiments are, at best, grossly approximate. Variations in the laser-probe apparent ages were observed only laterally across the phlogopite cleavage surface, indicating that argon transport occurs preferentially along phlogopite cleavage planes. Age profiles, when modeled using one-dimensional radial geometry (cylindrical coordinates), do not conform to classical Fick's law diffusion, suggesting that the characteristic dimension of diffusion for argon in phlogopite may be highly variable within individual grains.

  15. Albert Behnke: nitrogen narcosis.

    PubMed

    Grover, Casey A; Grover, David H

    2014-02-01

    As early as 1826, divers diving to great depths noted that descent often resulted in a phenomenon of intoxication and euphoria. In 1935, Albert Behnke discovered nitrogen as the cause of this clinical syndrome, a condition now known as nitrogen narcosis. Nitrogen narcosis consists of the development of euphoria, a false sense of security, and impaired judgment upon underwater descent using compressed air below 3-4 atmospheres (99 to 132 feet). At greater depths, symptoms can progress to loss of consciousness. The syndrome remains relatively unchanged in modern diving when compressed air is used. Behnke's use of non-nitrogen-containing gas mixtures subsequent to his discovery during the 1939 rescue of the wrecked submarine USS Squalus pioneered the use of non-nitrogen-containing gas mixtures, which are used by modern divers when working at great depth to avoid the effects of nitrogen narcosis.

  16. Hybrid membrane--PSA system for separating oxygen from air

    DOEpatents

    Staiger, Chad L [Albuquerque, NM; Vaughn, Mark R [Albuquerque, NM; Miller, A Keith [Albuquerque, NM; Cornelius, Christopher J [Blackburg, VA

    2011-01-25

    A portable, non-cryogenic, oxygen generation system capable of delivering oxygen gas at purities greater than 98% and flow rates of 15 L/min or more is described. The system consists of two major components. The first component is a high efficiency membrane capable of separating argon and a portion of the nitrogen content from air, yielding an oxygen-enriched permeate flow. This is then fed to the second component, a pressure swing adsorption (PSA) unit utilizing a commercially available, but specifically formulated zeolite compound to remove the remainder of the nitrogen from the flow. The system is a unique gas separation system that can operate at ambient temperatures, for producing high purity oxygen for various applications (medical, refining, chemical production, enhanced combustion, fuel cells, etc . . . ) and represents a significant advance compared to current technologies.

  17. Trapping cold ground state argon atoms.

    PubMed

    Edmunds, P D; Barker, P F

    2014-10-31

    We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)  C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)  cm(3) s(-1).

  18. The CAPTAIN Liquid Argon Neutrino Experiment

    NASA Astrophysics Data System (ADS)

    Liu, Qiuguang

    The CAPTAIN liquid argon experiment is designed to make measurements of scientific importance to long-baseline neutrino physics and physics topics that will be explored by large underground detectors. The experiment employs two detectors - a primary detector with approximately 10-ton of liquid argon that will be deployed at different facilities for physics measurements and a prototype detector with 2-ton of liquid argon for configuration testing. The physics programs for CAPTAIN include measuring neutron interactions at Los Alamos Neutron Science Center, measuring neutrino interactions in medium energy regime (1.5-5 GeV) at Fermilab's NuMI beam, and measuring neutrino interactions in low energy regime (< 50 MeV) at stopped pion sources for supernova neutrino studies.

  19. The CAPTAIN liquid argon neutrino experiment

    SciTech Connect

    Liu, Qiuguang

    2015-01-01

    The CAPTAIN liquid argon experiment is designed to make measurements of scientific importance to long-baseline neutrino physics and physics topics that will be explored by large underground detectors. The experiment employs two detectors – a primary detector with approximately 10-ton of liquid argon that will be deployed at different facilities for physics measurements and a prototype detector with 2-ton of liquid argon for configuration testing. The physics programs for CAPTAIN include measuring neutron interactions at Los Alamos Neutron Science Center, measuring neutrino interactions in medium energy regime (1.5–5 GeV) at Fermilab's NuMI beam, and measuring neutrino interactions in low energy regime (< 50 MeV) at stopped pion sources for supernova neutrino studies.

  20. The CAPTAIN liquid argon neutrino experiment

    DOE PAGES

    Liu, Qiuguang

    2015-01-01

    The CAPTAIN liquid argon experiment is designed to make measurements of scientific importance to long-baseline neutrino physics and physics topics that will be explored by large underground detectors. The experiment employs two detectors – a primary detector with approximately 10-ton of liquid argon that will be deployed at different facilities for physics measurements and a prototype detector with 2-ton of liquid argon for configuration testing. The physics programs for CAPTAIN include measuring neutron interactions at Los Alamos Neutron Science Center, measuring neutrino interactions in medium energy regime (1.5–5 GeV) at Fermilab's NuMI beam, and measuring neutrino interactions in low energymore » regime (< 50 MeV) at stopped pion sources for supernova neutrino studies.« less

  1. Modeling Atmospheric Reactive Nitrogen

    EPA Science Inventory

    Nitrogen is an essential building block of all proteins and thus an essential nutrient for all life. Reactive nitrogen, which is naturally produced via enzymatic reactions, forest fires and lightning, is continually recycled and cascades through air, water, and soil media. Human ...

  2. Argon used as dry suit insulation gas for cold-water diving

    PubMed Central

    2013-01-01

    Background Cold-water diving requires good thermal insulation because hypothermia is a serious risk. Water conducts heat more efficiently compared to air. To stay warm during a dive, the choice of thermal protection should be based on physical activity, the temperature of the water, and the duration of exposure. A dry suit, a diving suit filled with gas, is the most common diving suit in cold water. Air is the traditional dry suit inflation gas, whereas the thermal conductivity of argon is approximately 32% lower compared to that of air. This study evaluates the benefits of argon, compared to air, as a thermal insulation gas for a dry suit during a 1-h cold-water dive by divers of the Royal Netherlands Navy. Methods Seven male Special Forces divers made (in total) 19 dives in a diving basin with water at 13°C at a depth of 3 m for 1 h in upright position. A rubber dry suit and woollen undergarment were used with either argon (n = 13) or air (n = 6) (blinded to the divers) as suit inflation gas. Core temperature was measured with a radio pill during the dive. Before, halfway, and after the dive, subjective thermal comfort was recorded using a thermal comfort score. Results No diver had to abort the test due to cold. No differences in core temperature and thermal comfort score were found between the two groups. Core temperature remained unchanged during the dives. Thermal comfort score showed a significant decrease in both groups after a 60-min dive compared to baseline. Conclusions In these tests the combination of the dry suit and undergarment was sufficient to maintain core temperature and thermal comfort for a dive of 1 h in water at 13°C. The use of argon as a suit inflation gas had no added value for thermal insulation compared to air for these dives. PMID:24438580

  3. Atmospheric Nitrogen Fluorescence Yield

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Christl, M. J.; Fountain, W. F.; Gregory, J. C.; Martens, K. U.; Sokolsky, Pierre; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Several existing and planned experiments estimate the energies of ultra-high energy cosmic rays from air showers using the atmospheric nitrogen fluorescence. The nitrogen fluorescence yield from air shower electrons depends on the atmospheric composition. We will discuss the uncertainties in the fluorescence yield form electrons in the real atmosphere and describe a concept for a small balloon payload to measure the atmospheric fluorescence yield as a function of attitude.

  4. Solid-liquid phase transition in argon

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Tang, H. T.

    1978-01-01

    Starting from the Lennard-Jones interatomic potential, a modified cell theory has been used to describe the solid-liquid phase transition in argon. The cell-size variations may be evaluated by a self-consistent condition. With the inclusion of cell-size variations, the transition temperature, the solid and liquid densities, and the liquid-phase radial-distribution functions have been calculated. These ab initio results are in satisfactory agreement with molecular-dynamics calculations as well as experimental data on argon.

  5. Argon isotopes as recorders of magmatic processes

    NASA Astrophysics Data System (ADS)

    Layer, P. W.; Gardner, J. E.; Mora Chaparro, J. C.; Arce, J. L.

    2003-12-01

    Argon isotopic ratios vary enough between different reservoirs (atmosphere, crust, mantle) and diffuse fast enough through most minerals at magmatic temperatures (700-1200 C) to make them ideal for looking at magma chamber dynamics. Indeed, diffusion is sufficiently fast to allow short time scales to be deciphered, setting argon apart from many other isotopic methods. A mineral's ability to retain "excess" argon (40Ar/36Ar ratios greater than the atmospheric value and apparent ages older than the known eruption age) during post-eruption cooling is key to Ar studies. Previous work shows that both phenocrysts (crystallizing in the magma chamber; e.g. Mt St. Helens; Layer and Gardner, 2001) and xenocrysts (introduced into the magma chamber; e.g Toba; Gardner et al., 2002) preserve excess argon, which enables magma chamber processes to be deciphered through the variable diffusion rates between crystal phases. Single crystal 40Ar/39Ar step-heating of biotite from the 10.5 ka eruption of Nevado de Toluca volcano, Mexico indicates that they are xenocrystic and resided for only a short (< 1 year) time in the magma before it erupted. The biotite has reaction rims of hornblende, orthopyroxene and plagioclase, and failed to grow experimentally at pressure-temperature conditions of the magma, confirming the xenocrystic nature of this phase. Single-step fusion of plagioclase phenocrysts from eruptions of El Chichon volcano, Mexico, shows evidence of excess (mantle) argon, whereas hornblende from the same eruptions contains little or none. In this case, faster diffusion of Ar in plagioclase than in hornblende allow plagioclase to incorporate excess argon during magma recharge; hornblende does not. Combining such results with other isotopic systems may in fact better determine magma chamber processes. At El Chichon, Sr isotopes suggest magma recharges ocurred (Tepley et al., 2000), whereas the argon isotopes suggest such pulses occurred just before each eruption. The fast and

  6. Strain-cycling fatigue behavior of ten structural metals tested in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K)

    NASA Technical Reports Server (NTRS)

    Nachtigall, A. J.

    1974-01-01

    Strain-cycling fatigue behavior of 10 different structural alloys and metals was investigated in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K). At high cyclic lives, fatigue resistance increased with decreasing temperature for all the materials investigated. At low cyclic lives, fatigue resistance generally decreased with decreasing temperature for the materials investigated. Only for Inconel 718 did fatigue resistance increase with decreasing temperature over the entire life range investigated. Comparison of the experimental fatigue behavior with that predicted by the Manson method of universal slopes showed that the fatigue behavior of these materials can be predicted for cryogenic temperatures by using material tensile properties obtained at those same temperatures.

  7. Nitrogen-Doped Co3 O4 Mesoporous Nanowire Arrays as an Additive-Free Air-Cathode for Flexible Solid-State Zinc-Air Batteries.

    PubMed

    Yu, Minghao; Wang, Zhengke; Hou, Cheng; Wang, Zilong; Liang, Chaolun; Zhao, Cunyuan; Tong, Yexiang; Lu, Xihong; Yang, Shihe

    2017-04-01

    The kinetically sluggish rate of oxygen reduction reaction (ORR) on the cathode side is one of the main bottlenecks of zinc-air batteries (ZABs), and thus the search for an efficient and cost-effective catalyst for ORR is highly pursued. Co3 O4 has received ever-growing interest as a promising ORR catalyst due to the unique advantages of low-cost, earth abundance and decent catalytic activity. However, owing to the poor conductivity as a result of its semiconducting nature, the ORR activity of the Co3 O4 catalyst is still far below the expectation. Herein, we report a controllable N-doping strategy to significantly improve the catalytic activity of Co3 O4 for ORR and demonstrate these N doped Co3 O4 nanowires as an additive-free air-cathode for flexible solid-state zinc-air batteries. The results of experiments and DFT calculations reveal that the catalytic activity is promoted by the N dopant through a combined set of factors, including enhanced electronic conductivity, increased O2 adsorption strength and improved reaction kinetics. Finally, the assembly of all-solid-state ZABs based on the optimized cathode exhibit a high volumetric capacity of 98.1 mAh cm(-3) and outstanding flexibility. The demonstration of such flexible ZABs provides valuable insights that point the way to the redesign of emerging portable electronics.

  8. Scintillation efficiency of liquid argon in low energy neutron-argon scattering

    NASA Astrophysics Data System (ADS)

    Creus, W.; Allkofer, Y.; Amsler, C.; Ferella, A. D.; Rochet, J.; Scotto-Lavina, L.; Walter, M.

    2015-08-01

    Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field.

  9. Impact of Aircraft Emissions on Air Quality in the Vicinity of Airports. Volume 4. Nitrogen Dioxide and Hydrocarbons.

    DTIC Science & Technology

    1984-04-01

    Measurement History ........... 3 2.1.2 System Characterization..* ......... o ...................... 14 2.2 Data Analysis and Results...2.2 Field-Program Measurement History .................................. 8 4 2.3 Julian Date/Calendar Date Correspondence...aircraft on air quality have been the subject of a variety of research programs Involvitng both field- measurement programs and computer model

  10. International comparison CCQM-K101: oxygen in nitrogen—a track B comparison and that the matrix contains argon

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Han, Q.; Wang, D.; Macé, T.; Kipphardt, H.; Maiwald, M.; Tuma, D.; Uehara, S.; Akima, D.; Shimosaka, T.; Jung, J.; Oh, S.-H.; van der Veen, A.; van Wijk, J. I. T.; Ziel, P. R.; Konopelko, L.; Valkova, M.; Mogale, David M.; Botha, A.; Brewer, P.; Murugan, A.; Doval Minnaro, M.; Miller, M.; Guenther, F.; Kelly, M. E.

    2016-01-01

    This key comparison aims to assess the capabilities of the participants to determine the amount-of-substance fraction oxygen in nitrogen. The GAWG has classified this as a track B comparison, due to the unexpected 50 μmol/mol argon mole fraction content of the transfer standards, which effects the achievable performance of some measurement techniques such a GC-TCD. The separation of oxygen and argon is challenging, and not all systems in use are equally well designed for it. As this analytical challenge due to a substantial fraction of argon in the transfer standards became a reality, the Gas Analysis Working Group (GAWG) decided to qualify this key comparison as a regular key comparison and not as a core comparison, which may be used to support calibration and measurement capabilities (CMCs) for oxygen in nitrogen, or for oxygen in nitrogen mixtures containing argon only (see also the section on support to CMCs). Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Air quality at Santiago, Chile: a box modeling approach—I. Carbon monoxide, nitrogen oxides and sulfur dioxide

    NASA Astrophysics Data System (ADS)

    Jorquera, Héctor

    Ambient monitored data at Santiago, Chile, are analyzed using box models with the goal of assessing contributions of different economic activities to air pollution levels. The period analyzed is 1990-2000, characterized by the introduction of air pollution emissions standards, shift to unleaded gasoline and compressed natural gas, and steady growth of the private and public fleet and the associated fuel consumption growth. The box models explicitly include the seasonal behavior of meteorological variables; the results show that dispersion conditions in fall and winter seasons are 20-30% of the summertime values. This result explains the poor air quality in those seasons and shows that significant emissions reductions are required in order to improve air quality in wintertime. Emissions of CO, NO x and SO 2 are estimated from data on fuel consumption in the city; the estimated parameters are thus fleet-average or industry-average emission factors. In terms of contributions to ambient concentrations, older cars and diesel vehicles are the major contributors to CO and NO x impacts, with more than 60% and 50%, respectively. Ambient concentrations of SO 2 are largely dominated by stationary sources, although long range contributions are not negligible. By contrast, CO and NO x pollution is dominated by local sources within the city boundaries. The box models can be used for forecasting purposes, and they can predict annual average concentrations within 20% of the observed values. The methodology requires data on ambient air quality measurements and fuel consumption statistics, and produces quantitative results, which can be combined with economic models to analyze environmental regulation and public policies.

  12. Argon bubble behavior in slide-gate tundish nozzles during continuous casting of steel slabs

    NASA Astrophysics Data System (ADS)

    Bai, Hua

    2000-10-01

    Argon injection into a tundish nozzle is an efficient and widely employed method to reduce nozzle clogging in the continuous casting process. It also affects casting operation and product quality by changing the flow pattern in the nozzle and mold. The current work combines mathematical modeling and experiments to investigate the argon bubble behavior in slide-gate nozzles and to analyze phenomena related to product defects and operational problems during the continuous casting of steel slabs. Water model experiments are performed to study bubble formation behavior, including bubble size, frequency, mode and effects of variables such as liquid velocity, gas injection flow rate, gas injection hole size and gas density. An analytical model is developed to predict the average bubble size. Argon gas bubbles are predicted to be 1--5mm. This is larger than air bubbles in water, especially at low speed. A three-dimensional finite difference model is developed to study the turbulent flow of liquid steel and argon bubble in the slide-gate nozzles. Experiments are performed on a 0.4-scale "water caster" to verify the model by comparing the model prediction with the measurements using PIV (Particle Image Velocimetry) technology. A weighted average scheme for the overall outflow is developed to quantify jet characteristics such as jet angle, jet speed, back flow zone fraction, turbulence and biased mass flow. Swirl is generated at nozzle ports. The validated model is employed to perform extensive parametric studies to investigate the effects of casting operation conditions such as gas injection, slide-gate orientation, casting speed, gate opening and bubble size and nozzle port design including port angle and port shape. The interrelated effects of nozzle clogging, argon injection, tundish bath depth, slide gate opening and nozzle bore diameter on the flow rate and pressure in tundish nozzles are quantified using an inverse model, based on interpolation of the numerical

  13. Post-flight Analysis of the Argon Filled Ion Chamber

    NASA Technical Reports Server (NTRS)

    Tai, H.; Goldhagen, P.; Jones, I. W.; Wilson, J. W.; Maiden, D. L.; Shinn, J. L.

    2003-01-01

    Atmospheric ionizing radiation is a complex mixture of primary galactic and solar cosmic rays and a multitude of secondary particles produced in collision with air nuclei. The first series of Atmospheric Ionizing Radiation (AIR) measurement flights on the NASA research aircraft ER-2 took place in June 1997. The ER-2 flight package consisted of fifteen instruments from six countries and were chosen to provide varying sensitivity to specific components. These AIR ER-2 flight measurements are to characterize the AIR environment during solar minimum to allow the continued development of environmental models of this complex mixture of ionizing radiation. This will enable scientists to study the ionizing radiation health hazard associated with the high-altitude operation of a commercial supersonic transport and to allow estimates of single event upsets for advanced avionics systems design. The argon filled ion chamber representing about 40 percent of the contributions to radiation risks are analyzed herein and model discrepancies for solar minimum environment are on the order of 5 percent and less. Other biologically significant components remain to be analyzed.

  14. METHOD OF FIXING NITROGEN FOR PRODUCING OXIDES OF NITROGEN

    DOEpatents

    Harteck, P.; Dondes, S.

    1959-08-01

    A method is described for fixing nitrogen from air by compressing the air, irradiating the compressed air in a nuclear reactor, cooling to remove NO/ sub 2/, compressing the cooled gas, further cooling to remove N/sub 2/O and recirculating the cooled compressed air to the reactor.

  15. Thermal evolution of Venus with argon degassing

    NASA Astrophysics Data System (ADS)

    O'Rourke, Joseph G.; Korenaga, Jun

    2015-11-01

    Decades-old measurements of atmospheric and elemental surface composition constrain the history of Venus. In this study, we search for a model featuring continuous evolution in the stagnant-lid regime that predicts the present-day atmospheric mass of radiogenic argon and satisfies the other available constraints. For comparison, we also consider the end-member scenario of a single catastrophic resurfacing event. Thermal evolution simulations are performed that track the mass transport of argon and potassium and include a simple model of upwelling mantle plumes. Sensitivity analyses and linear regression are used to quantify the range of initial conditions that will produce desired values for key model output parameters. Decompression melting of passively upwelling mantle causes considerable mantle processing and crustal growth during the early evolution of Venus. Mantle plumes have negligible effects on recent crustal production, but may be important to local surface features. For a wide range of initial conditions, continuous evolution in the stagnant-lid regime predicts the correct amount of argon degassing, along with the absence of a global magnetic field, crustal and lithosphere thicknesses matching modern estimates, and volcanism consistent with the cratering record. Argon degassing does not uniquely constrain mantle dynamics, but the success of simple stagnant-lid models diminishes the need to invoke dramatic changes like catastrophic resurfacing.

  16. Argon frost continuous cryopump for fusion applications

    SciTech Connect

    Foster, C.A.; McCurdy, H.C.

    1993-12-01

    A cryopumping system based on the snail continuous cryopump concept is being developed for fusion applications under a DOE SBIR grant. The primary pump is a liquid helium cooled compound pump designed to continuously pump and fractionate deuterium/tritium and helium. The D/T pumping stage is a 500 mm bore cryocondensation pump with a nominal pumping speed of 45,000 L/s. It will be continuously regenerated by a snail regeneration by head every 12 minutes. Continuous regeneration will dramatically reduce the vulnerable tritium inventory in a fusion reactor. Operating at an inlet pressure of 1 millitorr, eight of these pumps could pump the projected D/T flow in the ITER CDA design while reducing the inventory of tritium in the pumping system from 630 to 43 grams. The helium fraction will be pumped in a compound argon frost stage. This stage will also operate continuously with a snail regeneration head. In addition the argon spray head will be enclosed inside the snail, thereby removing gaseous argon from the process chamber. Since the cryocondensation stage will intercept over 90% of the D/T/H steam, a purified stream from this stage could be directly reinjected into the plasma as gas or pellets, thereby bypassing the isotope separation system and further simplifying the fuel cycle. Experiments were undertaken in Phase I which demonstrated continuous cryosorption pumping of hydrogen on CO{sub 2} and argon frosts. The pumping system and its relevance to fusion reactor pumping will be discussed.

  17. Commissioning of the ATLAS Liquid Argon Calorimeters

    SciTech Connect

    Cooke, Mark S.

    2009-12-17

    A selection of ATLAS liquid argon (LAr) calorimeter commissioning studies is presented. It includes a coherent noise study, a measurement of the quality of the ionization pulse shape prediction, and energy and time reconstruction analyses with cosmic and single beam signals.

  18. Diamond film growth argon-carbon plasmas

    DOEpatents

    Gruen, Dieter M.; Krauss, Alan R.; Liu, Shengzhong; Pan, Xianzheng; Zuiker, Christopher D.

    1998-01-01

    A method and system for manufacturing diamond film. The method involves forming a carbonaceous vapor, providing a gas stream of argon, hydrogen and hydrocarbon and combining the gas with the carbonaceous vapor, passing the combined carbonaceous vapor and gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the carbonaceous and deposition of a diamond film on a substrate.

  19. Hydrodynamic Simulations of Gaseous Argon Shock Experiments

    NASA Astrophysics Data System (ADS)

    Garcia, Daniel; Dattelbaum, Dana; Goodwin, Peter; Morris, John; Sheffield, Stephen; Burkett, Michael

    2015-06-01

    The lack of published Argon gas shock data motivated an evaluation of the Argon Equation of State (EOS) in gas phase initial density regimes never before reached. In particular, these regimes include initial pressures in the range of 200-500 psi (0.025 - 0.056 g/cc) and initial shock velocities around 0.2 cm/ μs. The objective of the numerical evaluation was to develop a physical understanding of the EOS behavior of shocked and subsequently multiply re-shocked Argon gas initially pressurized to 200-500 psi through Pagosa numerical hydrodynamic simulations utilizing the SESAME equation of state. Pagosa is a Los Alamos National Laboratory 2-D and 3-D Eulerian hydrocode capable of modeling high velocity compressible flow with multiple materials. The approach involved the use of gas gun experiments to evaluate the shock and multiple re-shock behavior of pressurized Argon gas to validate Pagosa simulations and the SESAME EOS. Additionally, the diagnostic capability within the experiments allowed for the EOS to be fully constrained with measured shock velocity, particle velocity and temperature. The simulations demonstrate excellent agreement with the experiments in the shock velocity/particle velocity space, but note unanticipated differences in the ionization front temperatures.

  20. SLD liquid argon calorimeter prototype test results

    SciTech Connect

    Dubois, R.; Eigen, G.; Au, Y.; Sleeman, J.; Breidenbach, M.; Brau, J.; Ludgate, G.A.; Oram, C.J.; Cook, V.; Johnson, J.

    1985-10-01

    The results of the SLD test beam program for the selection of a calorimeter radiator composition within a liquid argon system are described, with emphasis on the study of the use of uranium to obtain equalization of pion and electron responses.

  1. Vibrational and Rotational CARS Measurements of Nitrogen in Afterglow of Streamer Discharge in Atmospheric Pressure Fuel/Air Mixtures

    DTIC Science & Technology

    2012-01-01

    distribution unlimited 13. SUPPLEMENTARY NOTES J. Phys. D: Appl. Phys. 45 (2012) 495401 (8pp) 14. ABSTRACT The use of nonequilibrium plasma generated by...nanosecond discharges to ignite fuel/air mixtures, known as transient plasma ignition (TPI), has been shown to effectively reduce ignition delay and...improve engine performance relative to spark ignition for combustion engines. While this method is potentially useful for many engine applications, at

  2. Twenty years of ambient observations of nitrogen oxides and specified hydrocarbons in air masses dominated by traffic emissions in Germany.

    PubMed

    Ehlers, Christian; Klemp, Dieter; Rohrer, Franz; Mihelcic, Djuro; Wegener, Robert; Kiendler-Scharr, Astrid; Wahner, Andreas

    2016-07-18

    The analysis of the individual composition of hydrocarbon (VOC) mixtures enables us to transform observed VOC-concentrations into their respective total VOC-reactivity versus OH radicals (RVOC = Σ(kOH+VOCi × [VOCi])). This is particularly useful because local ozone production essentially depends on this single parameter rather than on the details of the underlying hydrocarbon mixture (Klemp et al., Schriften des Forschungszentrums Jülich, Energy & Environment, 2012, 21). The VOC composition also enables us to pin down the major emission source of hydrocarbons in urban areas to be petrol cars with temporarily reduced catalyst efficiency (the so-called cold-start situation) whereas the source of nitrogen oxides (NOx = NO + NO2) is expected to be nowadays dominated by diesel cars. The observations in the vicinity of main roads in German cities show a decrease in the ratio of OH reactivities of VOC and NO2 (RVOC/RNO2) by a factor of 7.5 over the time period 1994-2014. This is larger than the expected decrease of a factor of 2.9 taking estimated trends of VOC and NOx traffic emissions in Germany (Umweltbundesamt Deutschland, National Trend Tables for the German Atmospheric Emission Reporting, 2015), during this time period. The observed reduction in the RVOC/RNO2 ratio leads to a drastic decrease in local ozone production driven by the reduction in hydrocarbons. The analysis reveals that the overall reduction of ozone production benefits from the low decrease of NOx emissions from road traffic which is a consequence of the eventual absence of catalytic converters for nitrogen oxide removal in diesel cars up to now.

  3. Performance of the 0.3-meter transonic cryogenic tunnel with air, nitrogen, and sulfur hexafluoride media under closed loop automatic control

    NASA Technical Reports Server (NTRS)

    Balakrishna, S.; Kilgore, W. Allen

    1995-01-01

    The NASA Langley 0.3-m Transonic Cryogenic Tunnel was modified in 1994, to operate with any one of the three test gas media viz., air, cryogenic nitrogen gas, or sulfur hexafluoride gas. This document provides the initial test results with respect to the tunnel performance and tunnel control, as a part of the commissioning activities on the microcomputer based controller. The tunnel can provide precise and stable control of temperature to less than or equal to +/- 0.3 K in the range 80-320 K in cyro mode or 300-320 K in air/SF6 mode, pressure to +/- 0.01 psia in the range 15-88 psia and Mach number to +/- O.0015 in the range 0.150 to transonic Mach numbers up to 1.000. A new heat exchanger has been included in the tunnel circuit and is performing adequately. The tunnel airfoil testing benefits considerably by precise control of tunnel states and helps in generating high quality aerodynamic test data from the 0.3-m TCT.

  4. Simplified Two-Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydorgen/Oxygen

    NASA Technical Reports Server (NTRS)

    Molnar, Melissa; Marek, C. John

    2005-01-01

    A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two-time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (> 1 x 10(exp -20) moles/cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T4). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/air fuel and for the H2/O2. A similar correlation is also developed using data from NASA s Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T4) as a function of overall fuel/air ratio, pressure and initial temperature (T3). High values of the regression coefficient R2 are obtained.

  5. Summary of Simplified Two Time Step Method for Calculating Combustion Rates and Nitrogen Oxide Emissions for Hydrogen/Air and Hydrogen/Oxygen

    NASA Technical Reports Server (NTRS)

    Marek, C. John; Molnar, Melissa

    2005-01-01

    A simplified single rate expression for hydrogen combustion and nitrogen oxide production was developed. Detailed kinetics are predicted for the chemical kinetic times using the complete chemical mechanism over the entire operating space. These times are then correlated to the reactor conditions using an exponential fit. Simple first order reaction expressions are then used to find the conversion in the reactor. The method uses a two time step kinetic scheme. The first time averaged step is used at the initial times with smaller water concentrations. This gives the average chemical kinetic time as a function of initial overall fuel air ratio, temperature, and pressure. The second instantaneous step is used at higher water concentrations (greater than l x 10(exp -20)) moles per cc) in the mixture which gives the chemical kinetic time as a function of the instantaneous fuel and water mole concentrations, pressure and temperature (T(sub 4)). The simple correlations are then compared to the turbulent mixing times to determine the limiting properties of the reaction. The NASA Glenn GLSENS kinetics code calculates the reaction rates and rate constants for each species in a kinetic scheme for finite kinetic rates. These reaction rates are used to calculate the necessary chemical kinetic times. This time is regressed over the complete initial conditions using the Excel regression routine. Chemical kinetic time equations for H2 and NOx are obtained for H2/Air fuel and for H2/O2. A similar correlation is also developed using data from NASA's Chemical Equilibrium Applications (CEA) code to determine the equilibrium temperature (T(sub 4)) as a function of overall fuel/air ratio, pressure and initial temperature (T(sub 3)). High values of the regression coefficient R squared are obtained.

  6. Upper ocean bubble measurements from the NE Pacific and estimates of their role in air-sea gas transfer of the weakly soluble gases nitrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Vagle, Svein; McNeil, Craig; Steiner, Nadja

    2010-12-01

    Simultaneous observations of upper-ocean bubble clouds, and dissolved gaseous nitrogen (N2) and oxygen (O2) from three winter storms are presented and analyzed. The data were collected on the Canadian Surface Ocean Lower Atmosphere Study (C-SOLAS) mooring located near Ocean Station Papa (OSP) at 50°N, 145°W in the NE Pacific during winter of 2003/2004. The bubble field was measured using an upward looking 200 kHz echosounder. Direct estimates of bubble mediated gas fluxes were made using assumed bubble size spectra and the upward looking echosounder data. A one-dimensional biogeochemical model was used to help compare data and various existing models of bubble mediated air-sea gas exchange. The direct bubble flux calculations show an approximate quadratic/cubic dependence on mean bubble penetration depth. After scaling from N2/O2 to carbon dioxide, near surface, nonsupersaturating, air-sea transfer rates, KT, for U10 > 12 m s-1 fall between quadratic and cubic relationships. Estimates of the subsurface bubble induced air injection flux, VT, show an approximate quadratic/cubic dependence on mean bubble penetration depth. Both KT and VT are much higher than those measured during Hurricane Frances over the wind speed range 12 < U10 < 23 m s-1. This result implies that over the open ocean and this wind speed range, older and more developed seas which occur during winter storms are more effective in exchanging gases between the atmosphere and ocean than younger less developed seas which occur during the rapid passage of a hurricane.

  7. Preferential site occupancy observed in coexpanded argon-krypton clusters

    SciTech Connect

    Lundwall, M.; Bergersen, H.; Lindblad, A.; Oehrwall, G.; Svensson, S.; Bjoerneholm, O.; Tchaplyguine, M.

    2006-10-15

    Free heterogeneous argon-krypton clusters have been produced by coexpansion and investigated by means of x-ray photoelectron spectroscopy. By examining cluster surface and bulk binding energy shifts, relative intensities, and peak widths, we show that in the mixed argon-krypton clusters the krypton atoms favor the bulk and argon atoms are pushed to the surface. Furthermore, we show that krypton atoms in the surface layer occupy high-coordination sites and that heterogeneous argon-krypton clusters produced by coexpansion show the same surface structure as argon host clusters doped with krypton. These observations are supported by site-dependent calculations of chemical shifts.

  8. Cryogenic digital data links for the liquid argon time projection chamber

    NASA Astrophysics Data System (ADS)

    Liu, T.; Gong, D.; Hou, S.; Liu, C.; Su, D.-S.; Teng, P.-K.; Xiang, A. C.; Ye, J.

    2012-01-01

    In this paper we present the cryogenic functionality of the components of data links for the Liquid Argon Time Projection Chamber (LArTPC), a potential far site detector technology of the Long-Baseline Neutrino Experiment (LBNE). We have confirmed that an LVDS driver can drive a 20-meter CAT5E twisted pair up to 1 gigabit per second at the liquid nitrogen temperature (77 K). We have verified that a commercial-off-the-shelf (COTS) serializer, a laser diode driver, laser diodes, optical fibers and connectors, and field-programming gate arrays (FPGA`s) continue to function at 77 K. A variety of COTS resistors and capacitors have been tested at 77 K. All tests we have conducted show that the cryogenic digital data links for the liquid argon time projection chamber are promising.

  9. Effects of metastable species in helium and argon atmospheric pressure plasma jets (APPJs) on inactivation of periodontopathogenic bacteria

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-Young; Kim, Kyoung-Hwa; Seol, Yang-Jo; Kim, Su-Jeong; Bae, Byeongjun; Huh, Sung-Ryul; Kim, Gon-Ho

    2016-05-01

    The helium and argon have been widely used as discharge gases in atmospheric pressure plasma jets (APPJs) for bacteria inactivation. The APPJs show apparent different in bullet propagation speed and bacteria inactivation rate apparently vary with discharge gas species. This work shows that these two distinctive features of APPJs can be linked through one factor, the metastable energy level. The effects of helium and argon metastable species on APPJ discharge mechanism for reactive oxygen nitrogen species (RONS) generation in APPJs are investigated by experiments and numerical estimation. The discharge mechanism is investigated by using the bullet velocity from the electric field which is obtained with laser induced fluorescence (LIF) measurement. The measured electric field also applied on the estimation of RONS generation, as electron energy source term in numerical particle reaction. The estimated RONS number is verified by comparing NO and OH densities to the inactivation rate of periodontitis bacteria. The characteristic time for bacteria inactivation of the helium-APPJ was found to be 1.63 min., which is significantly less than that of the argon-APPJ, 12.1 min. In argon-APPJ, the argon metastable preserve the energy due to the lack of the Penning ionization. Thus the surface temperature increase is significantly higher than helium-APPJ case. It implies that the metastable energy plays important role in both of APPJ bullet propagation and bacteria inactivation mechanism.

  10. Short-Term Effects of Nitrogen Dioxide on Mortality and Susceptibility Factors in 10 Italian Cities: The EpiAir Study

    PubMed Central

    Chiusolo, Monica; Cadum, Ennio; Stafoggia, Massimo; Galassi, Claudia; Faustini, Annunziata; Bisanti, Luigi; Vigotti, Maria Angela; Dessì, Maria Patrizia; Cernigliaro, Achille; Mallone, Sandra; Pacelli, Barbara; Minerba, Sante; Simonato, Lorenzo; Forastiere, Francesco

    2011-01-01

    Background: Several studies have shown an association between nitrogen dioxide (NO2) and mortality. In Italy, the EpiAir multicentric study, “Air Pollution and Health: Epidemiological Surveillance and Primary Prevention,” investigated short-term health effects of air pollution, including NO2. Objectives: To study the individual susceptibility, we evaluated the association between NO2 and cause-specific mortality, investigating individual sociodemographic features and chronic/acute medical conditions as potential effect modifiers. Methods: We considered 276,205 natural deaths of persons > 35 years of age, resident in 10 Italian cities, and deceased between 2001 and 2005. We chose a time-stratified case-crossover analysis to evaluate the short-term effects of NO2 on natural, cardiac, cerebrovascular, and respiratory mortality. For each subject, we collected information on sociodemographic features and hospital admissions in the previous 2 years. Fixed monitors provided daily concentrations of NO2, particulate matter ≤ 10 μm in aerodynamic diameter (PM10) and ozone (O3). Results: We found statistically significant associations with a 10-μg/m3 increase of NO2 for natural mortality [2.09% for lag 0–5; 95% confidence interval (CI), 0.96–3.24], for cardiac mortality (2.63% for lag 0–5; 95% CI, 1.53–3.75), and for respiratory mortality (3.48% for lag 1–5; 95% CI, 0.75–6.29). These associations were independent from those of PM10 and O3. Stronger associations were estimated for subjects with at least one hospital admission in the 2 previous years and for subjects with three or more specific chronic conditions. Some cardiovascular conditions (i.e., ischemic heart disease, pulmonary circulation impairment, heart conduction disorders, heart failure) and diabetes appeared to confer a strong susceptibility to air pollution. Conclusions: Our results suggest significant and likely independent effects of NO2 on natural, cardiac, and respiratory mortality

  11. The long term observed effect of air and water injection into a fracture hydrothermal system

    SciTech Connect

    Mario Cesar Suarez Arriaga; Mirna Tello Lopez; Luis de Rio; Hector Gutierrez Puente

    1992-01-01

    Injection of atmospheric air mixed with waste reinjection liquid, has been occurring since 1982 at the Los Azufres, Mexico volcanic hydrothermal system. Several chemical and thermodynamical evidences show that air injection into this fractured geothermal field, could be considered as a long term natural tracer test. Nitrogen and Argon separated from the air mixture migrate from reinjection wells to production zones following preferential paths closely related to high permeability conduits. These paths can be detected, looking into the N2 solubility evolution of production wells. The anisotropic nature of the fractured volcanic rock, would demand considerably amounts of artificial tracer in order to be detected at the producing wells, specially when fluid extraction is low. This explains the unsuccessful recovery of the artificial tracer tests performed in past years at Tejamaniles, the southern field's sector. On the other hand, chloride concentrations and other salts, are increasing in the liquid produced by the oldest wells of the sector.

  12. The use of air as a natural tracer infractured hydrothermal systems, Los Azufres, Mexico, case study

    SciTech Connect

    Mario Cesar Sudrez Arriaga; Hector Gutierrez Puente, Josefina Moreno Ochoa

    1991-01-01

    Injection of atmospheric air mixed with cold water has been occurring since 1982 at the Los Azufres geothermal field. Several chemical and thermodynamical evidences show that air injection into this fractured hydrothermal system could be considered as a long term natural tracer test. Nitrogen and Argon separated from the air mixture migrate, under the action of the induced injection-extraction gradient, from reinjection sectors to production zones following preferential paths closely related to high permeability conduits. A coarse numerical estimation of the average permeability tensor existing at Tejamaniles, the southern sector, explains the unsuccessful recovery of the artificial tracer tests performed in past years: the anisotropic nature of the fractured volcanic rock would demand considerably quantities of tracer in order to be detected at the producing wells, especially when fluid extraction was low. At the same time concentrations of calcium, cesium, chloride, potassium, rubidium and sodium, are increasing in the liquid produced by the oldest wells of this field's sector.

  13. Abnormal epidermal changes after argon laser treatment

    SciTech Connect

    Neumann, R.A.; Knobler, R.M.; Aberer, E.; Klein, W.; Kocsis, F.; Ott, E. )

    1991-02-01

    A 26-year-old woman with a congenital port-wine stain on the forehead was treated three times at 2-month intervals with an argon laser. Six months after the last treatment, moderate blanching and mild scaling confined to the treated area was observed. A biopsy specimen of the treated area revealed a significant decrease in ectatic vessels. However, epidermal changes similar to those of actinic keratosis with disorganized cell layers and marked cytologic abnormalities were seen. Analysis of peripheral blood lymphocytes for a defect in DNA repair was negative. Multiple, argon laser-induced photothermal effects may be responsible for the changes observed in our case and may lead to premalignant epidermal transformation.

  14. Argon ion pollution of the magnetosphere

    NASA Technical Reports Server (NTRS)

    Lopez, R. E.

    1985-01-01

    Construction of a Solar Power Satellite (SPS) would require the injection of large quantities of propellant to transport material from Low Earth Orbit (LEO) to the construction site at Geostationary Earth Orbit (GEO). This injection, in the form of approx 10 to the 32nd power, 2 KeV argon ions (and associated electrons) per SPS, is comparable to the content of the plasmasphere (approx 10 to the 31st power ions). In addition to the mass deposited, this represents a considerable injection of energy. The injection is examined in terms of a simple model for the expansion of the beam plasma. General features of the subsequent magnetospheric convection of the argon are also examined.

  15. Multishock Compression Properties of Warm Dense Argon

    PubMed Central

    Zheng, Jun; Chen, Qifeng; Yunjun, Gu; Li, Zhiguo; Shen, Zhijun

    2015-01-01

    Warm dense argon was generated by a shock reverberation technique. The diagnostics of warm dense argon were performed by a multichannel optical pyrometer and a velocity interferometer system. The equations of state in the pressure-density range of 20–150 GPa and 1.9–5.3 g/cm3 from the first- to fourth-shock compression were presented. The single-shock temperatures in the range of 17.2–23.4 kK were obtained from the spectral radiance. Experimental results indicates that multiple shock-compression ratio (ηi = ρi/ρ0) is greatly enhanced from 3.3 to 8.8, where ρ0 is the initial density of argon and ρi (i = 1, 2, 3, 4) is the compressed density from first to fourth shock, respectively. For the relative compression ratio (ηi’ = ρi/ρi-1), an interesting finding is that a turning point occurs at the second shocked states under the conditions of different experiments, and ηi’ increases with pressure in lower density regime and reversely decreases with pressure in higher density regime. The evolution of the compression ratio is controlled by the excitation of internal degrees of freedom, which increase the compression, and by the interaction effects between particles that reduce it. A temperature-density plot shows that current multishock compression states of argon have distributed into warm dense regime. PMID:26515505

  16. Diamond film growth argon-carbon plasmas

    DOEpatents

    Gruen, D.M.; Krauss, A.R.; Liu, S.Z.; Pan, X.Z.; Zuiker, C.D.

    1998-12-15

    A method and system are disclosed for manufacturing diamond film. The method involves forming a carbonaceous vapor, providing a gas stream of argon, hydrogen and hydrocarbon and combining the gas with the carbonaceous vapor, passing the combined carbonaceous vapor and gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the carbonaceous and deposition of a diamond film on a substrate. 29 figs.

  17. An impact hypothesis for Venus argon anomalies

    NASA Astrophysics Data System (ADS)

    Kaula, W. M.; Newman, W. I.

    1997-03-01

    The Ar-36+38 argon-excess anomally of Venus has been hypothesized to have its origin in the impact of an outer solar system body of about 100-km diameter. A critical evaluation is made of this hypothesis and its competitors; it is judged that its status must for the time being remain one of 'Sherlock Holmes' type, in that something so improbable must be accepted when all alternatives are eliminated.

  18. Current and future liquid argon neutrino experiments

    SciTech Connect

    Karagiorgi, Georgia S.

    2015-05-15

    The liquid argon time projection chamber (LArTPC) detector technology provides an opportunity for precision neutrino oscillation measurements, neutrino cross section measurements, and searches for rare processes, such as SuperNova neutrino detection. These proceedings review current and future LArTPC neutrino experiments. Particular focus is paid to the ICARUS, MicroBooNE, LAr1, 2-LArTPC at CERN-SPS, LBNE, and 100 kton at Okinoshima experiments.

  19. Spherical nitrogen-doped hollow mesoporous carbon as an efficient bifunctional electrocatalyst for Zn-air batteries

    NASA Astrophysics Data System (ADS)

    Hadidi, Lida; Davari, Elaheh; Iqbal, Muhammad; Purkait, Tapas K.; Ivey, Douglas G.; Veinot, Jonathan G. C.

    2015-12-01

    Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO2 template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling.Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO2 template that is removed upon hydrofluoric acid etching. The morphology and structural

  20. Distribution and Abundance of Mars' Atmospheric Argon

    NASA Technical Reports Server (NTRS)

    Sprague, A. L.; Boynton, W. V.; Kerry, K. E.; Nelli, Steven; Murphy, Jim; Reedy, R. C.; Metzger, A. E.; Hunten, D. M.; Janes, K. D.; Crombie, M. K.

    2005-01-01

    One and one half Mars years (MY 26 and 27) of atmospheric Argon measurements are described and studied in the context of understanding how Argon, a minor constituent of Mars atmosphere that does not condense at Mars temperatures, can be used to study martian circulation and dynamics. Argon data are from the 2001 Mars Odyssey Gamma Subsystem (GS) of the suite of three instruments comprising the Gamma Ray Spectrometer (GRS). A comprehensive data analysis including gamma-ray production and attenuation by the atmosphere is included. Of particular interest is the enhanced abundance of Ar over the observed Ar abundance at lower latitudes at south (up to a factor of 10) and north (up to a factor of 4) polar regions during winter. Calibration of the measurements to actual Ar abundance is possible because GS measurements cover the same latitude and season as measurements made by the gas chromatograph mass spectrometer (GCMS) on Viking Landers 1 and 2 (VL1 and VL2). [2].

  1. Heavy-duty diesel engine NO{sub x} reduction with nitrogen-enriched combustion air. Final CRADA report.

    SciTech Connect

    McConnell, S.; Energy Systems

    2010-07-28

    The concept of engine emissions control by modifying intake combustion gas composition from that of ambient air using gas separation membranes has been developed during several programs undertaken at Argonne. These have led to the current program which is targeted at heavy-duty diesel truck engines. The specific objective is reduction of NO{sub x} emissions by the target engine to meet anticipated 2007 standards while extracting a maximum of 5 percent power loss and allowing implementation within commercial constraints of size, weight, and cost. This report includes a brief review of related past programs, describes work completed to date during the current program, and presents interim conclusions. Following a work schedule adjustment in August 2002 to accommodate problems in module procurement and data analysis, activities are now on schedule and planned work is expected to be completed in September, 2004. Currently, we believe that the stated program requirements for the target engine can be met, based upon extrapolation of the work completed. Planned project work is designed to experimentally confirm these projections and result in a specification for a module package that will meet program objectives.

  2. Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies.

    PubMed

    Zaehle, Sönke; Medlyn, Belinda E; De Kauwe, Martin G; Walker, Anthony P; Dietze, Michael C; Hickler, Thomas; Luo, Yiqi; Wang, Ying-Ping; El-Masri, Bassil; Thornton, Peter; Jain, Atul; Wang, Shusen; Warlind, David; Weng, Ensheng; Parton, William; Iversen, Colleen M; Gallet-Budynek, Anne; McCarthy, Heather; Finzi, Adrien; Hanson, Paul J; Prentice, I Colin; Oren, Ram; Norby, Richard J

    2014-05-01

    We analysed the responses of 11 ecosystem models to elevated atmospheric [CO2 ] (eCO2 ) at two temperate forest ecosystems (Duke and Oak Ridge National Laboratory (ORNL) Free-Air CO2 Enrichment (FACE) experiments) to test alternative representations of carbon (C)-nitrogen (N) cycle processes. We decomposed the model responses into component processes affecting the response to eCO2 and confronted these with observations from the FACE experiments. Most of the models reproduced the observed initial enhancement of net primary production (NPP) at both sites, but none was able to simulate both the sustained 10-yr enhancement at Duke and the declining response at ORNL: models generally showed signs of progressive N limitation as a result of lower than observed plant N uptake. Nonetheless, many models showed qualitative agreement with observed component processes. The results suggest that improved representation of above-ground-below-ground interactions and better constraints on plant stoichiometry are important for a predictive understanding of eCO2 effects. Improved accuracy of soil organic matter inventories is pivotal to reduce uncertainty in the observed C-N budgets. The two FACE experiments are insufficient to fully constrain terrestrial responses to eCO2 , given the complexity of factors leading to the observed diverging trends, and the consequential inability of the models to explain these trends. Nevertheless, the ecosystem models were able to capture important features of the experiments, lending some support to their projections.

  3. Comparing universal kriging and land-use regression for predicting concentrations of gaseous oxides of nitrogen (NOx) for the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air).

    PubMed

    Mercer, Laina D; Szpiro, Adam A; Sheppard, Lianne; Lindström, Johan; Adar, Sara D; Allen, Ryan W; Avol, Edward L; Oron, Assaf P; Larson, Timothy; Liu, L-J Sally; Kaufman, Joel D

    2011-08-01

    BACKGROUND: Epidemiological studies that assess the health effects of long-term exposure to ambient air pollution are used to inform public policy. These studies rely on exposure models that use data collected from pollution monitoring sites to predict exposures at subject locations. Land use regression (LUR) and universal kriging (UK) have been suggested as potential prediction methods. We evaluate these approaches on a dataset including measurements from three seasons in Los Angeles, CA. METHODS: The measurements of gaseous oxides of nitrogen (NOx) used in this study are from a "snapshot" sampling campaign that is part of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air). The measurements in Los Angeles were collected during three two-week periods in the summer, autumn, and winter, each with about 150 sites. The design included clusters of monitors on either side of busy roads to capture near-field gradients of traffic-related pollution. LUR and UK prediction models were created using geographic information system (GIS)-based covariates. Selection of covariates was based on 10-fold cross-validated (CV) R(2) and root mean square error (RMSE). Since UK requires specialized software, a computationally simpler two-step procedure was also employed to approximate fitting the UK model using readily available regression and GIS software. RESULTS: UK models consistently performed as well as or better than the analogous LUR models. The best CV R(2) values for season-specific UK models predicting log(NOx) were 0.75, 0.72, and 0.74 (CV RMSE 0.20, 0.17, and 0.15) for summer, autumn, and winter, respectively. The best CV R(2) values for season-specific LUR models predicting log(NOx) were 0.74, 0.60, and 0.67 (CV RMSE 0.20, 0.20, and 0.17). The two-stage approximation to UK also performed better than LUR and nearly as well as the full UK model with CV R(2) values 0.75, 0.70, and 0.70 (CV RMSE 0.20, 0.17, and 0.17) for summer, autumn, and winter

  4. Comparing universal kriging and land-use regression for predicting concentrations of gaseous oxides of nitrogen (NOx) for the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air)

    PubMed Central

    Mercer, Laina D; Szpiro, Adam A; Sheppard, Lianne; Lindström, Johan; Adar, Sara D; Allen, Ryan W; Avol, Edward L; Oron, Assaf P; Larson, Timothy; Liu, L-J Sally; Kaufman, Joel D

    2011-01-01

    Background Epidemiological studies that assess the health effects of long-term exposure to ambient air pollution are used to inform public policy. These studies rely on exposure models that use data collected from pollution monitoring sites to predict exposures at subject locations. Land use regression (LUR) and universal kriging (UK) have been suggested as potential prediction methods. We evaluate these approaches on a dataset including measurements from three seasons in Los Angeles, CA. Methods The measurements of gaseous oxides of nitrogen (NOx) used in this study are from a “snapshot” sampling campaign that is part of the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air). The measurements in Los Angeles were collected during three two-week periods in the summer, autumn, and winter, each with about 150 sites. The design included clusters of monitors on either side of busy roads to capture near-field gradients of traffic-related pollution. LUR and UK prediction models were created using geographic information system (GIS)-based covariates. Selection of covariates was based on 10-fold cross-validated (CV) R2 and root mean square error (RMSE). Since UK requires specialized software, a computationally simpler two-step procedure was also employed to approximate fitting the UK model using readily available regression and GIS software. Results UK models consistently performed as well as or better than the analogous LUR models. The best CV R2 values for season-specific UK models predicting log(NOx) were 0.75, 0.72, and 0.74 (CV RMSE 0.20, 0.17, and 0.15) for summer, autumn, and winter, respectively. The best CV R2 values for season-specific LUR models predicting log(NOx) were 0.74, 0.60, and 0.67 (CV RMSE 0.20, 0.20, and 0.17). The two-stage approximation to UK also performed better than LUR and nearly as well as the full UK model with CV R2 values 0.75, 0.70, and 0.70 (CV RMSE 0.20, 0.17, and 0.17) for summer, autumn, and winter, respectively

  5. Exposure assessment of air pollutants: a review on spatial heterogeneity and indoor/outdoor/personal exposure to suspended particulate matter, nitrogen dioxide and ozone

    NASA Astrophysics Data System (ADS)

    Monn, Christian

    This review describes databases of small-scale spatial variations and indoor, outdoor and personal measurements of air pollutants with the main focus on suspended particulate matter, and to a lesser extent, nitrogen dioxide and photochemical pollutants. The basic definitions and concepts of an exposure measurement are introduced as well as some study design considerations and implications of imprecise exposure measurements. Suspended particulate matter is complex with respect to particle size distributions, the chemical composition and its sources. With respect to small-scale spatial variations in urban areas, largest variations occur in the ultrafine (<0.1 μm) and the coarse mode (PM 10-2.5, resuspended dust). Secondary aerosols which contribute to the accumulation mode (0.1-2 μm) show quite homogenous spatial distribution. In general, small-scale spatial variations of PM 2.5 were described to be smaller than the spatial variations of PM 10. Recent studies in outdoor air show that ultrafine particle number counts have large spatial variations and that they are not well correlated to mass data. Sources of indoor particles are from outdoors and some specific indoor sources such as smoking and cooking for fine particles or moving of people (resuspension of dust) for coarse particles. The relationships between indoor, outdoor and personal levels are complex. The finer the particle size, the better becomes the correlation between indoor, outdoor and personal levels. Furthermore, correlations between these parameters are better in longitudinal analyses than in cross-sectional analyses. For NO 2 and O 3, the air chemistry is important. Both have considerable small-scale spatial variations within urban areas. In the absence of indoor sources such as gas appliances, NO 2 indoor/outdoor relationships are strong. For ozone, indoor levels are quite small. The study hypothesis largely determines the choice of a specific concept in exposure assessment, i.e. whether personal

  6. Nonlinearity of Argon Isotope Measurements for Samples of Different Sizes

    NASA Astrophysics Data System (ADS)

    Cox, S. E.; Hemming, S. R.; Turrin, B. D.; Swisher, C. C.

    2010-12-01

    Uncertainty in isotope ratio linearity is not propagated into the final uncertainty of high-precision Ar-Ar analyses. Nonlinearity is assumed to be negligible compared to other sources of error, so mass discrimination is calculated using air pipettes of a single size similar to typical unknowns. The calculated discrimination factor is applied to all measured isotopes regardless of the difference in relative isotope abundance or the difference in gas pressure between the sample and the air pipette. We measured 40Ar/36Ar ratios of different size air samples created using up to twenty pipette shots on two different mass spectrometers with automated air pipette systems (a VG5400 and an MAP 215-50) in order to test the assumption that the measured isotope ratios are consistent at different gas pressures. We typically obtain reproducibility < 0.5% on the 40Ar/36Ar of similar size air standards, but we measured 40Ar/36Ar ratios for aliquots 0.5 to 20 times the typical volume from the same reservoir that varied by as much as 10% (Figure 1). In sets VG1, VG2, and MAP, 40Ar/36Ar ratios increased with gas pressure (expressed as number of air pipette shots; R2 > 0.9). Several months later, we performed the same measurements on the VG5400 with a new filament and different tuning parameters and obtained a different result (Set VG3). In this case, the 40Ar/36Ar ratios still varied with gas pressure, but less drastically (R2 > 0.3), and the slope was reversed--40Ar/36Ar ratios decreased with gas pressure. We conclude that isotope ratio nonlinearity is a common phenomenon that has the potential to affect monitor standard and timescale age calculations at the 0.1% level of significance defined by EARTHTIME. We propose that argon labs incorporate air pipettes of varying size and isotopic compositions to allow for routine calibration of isotope ratio nonlinearity in the course of high-precision analyses. Figure 1: Measured 40Ar/36Ar vs. number of air pipettes. Sets VG1, VG2, and MAP

  7. KEY COMPARISON: Final report on the CIPM key comparisons for compressed air and nitrogen conducted in November 2004/June 2005: CCM.FF-5.b

    NASA Astrophysics Data System (ADS)

    Dopheide, Dietrich

    2006-01-01

    The calibration of gas meters for flow rate measurements of natural gas at high pressure is of critical importance for gas importers, gas distributors and international trade. It is recommended to calibrate gas meters actually with natural gas at high pressure; however, some countries apply compressed air or nitrogen as a surrogate fluid. Key comparisons (KCs) have been organized among all national metrology organizations (NMIs) worldwide that maintain national standards and take care of compressed air/nitrogen flow metrology. It turned out that, for the time being, only four NMIs were ready to participate, as no other NMIs or countries maintain national standards. These four NMIs are LNE in Paris, NEL in Great Britain, CMS/ITRI in Chinese Taipei, and KRISS in Korea. PTB-pigsar in Germany has been used as the pilot lab for the initial calibration of the transfer standard. All existing facilities in the world were invited to participate, but they all refrained from participation, as they are not yet ready, e.g. CEESI, SwRI, NIST. Russia does not maintain a calibration facility for this type of fluid flow so far. For more details we refer to the full report. The KC for compressed air was conducted during November 2004/June 2005 successfully at flow rates over a wide overlapping range of flow rate and pressure using a set of turbine meters. The transfer package comprises of two turbine meters put in series. Flow rates between 65 m3/h and 1000 m3/h and pressures between 5 bar and 40 bar have been applied. It shall be mentioned here that the weighted average for the KCRV according to a BIPM recommendation for KCs has been used as the first choice. The final report presents the degree of equivalence among the participants as well as the degree of equivalence to the KCRV and confirms all claimed uncertainties of the national calibration facilities of France, Great Britain, Korea and Chinese Taipei. In addition, a link to CCM.FF-K5a for natural gas can be made

  8. The Physics Analysis of a Gas Attenuator with Argon as a Working Gas

    SciTech Connect

    Ryutov,, D.D.

    2010-12-07

    A gas attenuator is an important element of the LCLS facility. The attenuator must operate in a broad range of x-ray energies, provide attenuation coefficient between 1 and 10{sup 4} with the accuracy of 1% and, at the same time, be reliable and allow for many months of un-interrupted operation. S. Shen has recently carried out a detailed design study of the attenuator based on the use of nitrogen as a working gas. In this note we assess the features of the attenuator based on the use of argon. We concentrate on the physics issues, not the design features.

  9. Using History To Teach Scientific Method: The Case of Argon

    NASA Astrophysics Data System (ADS)

    Giunta, Carmen J.

    1998-10-01

    The history of science is full of stories that exhibit scientific methodology to an exemplary degree. Such stories can be vehicles for the teaching of scientific thought to non-science majors in general-education science courses, particularly if they do not involve much technical background and are told in ordinary language. This paper illustrates the kind of lessons that can be gleaned from such stories by examining the discovery of argon, an episode replete with examples of how scientists pursue knowledge. Lord Rayleigh's use of multiple methods to determine the density of nitrogen; his persistent tracking down of a small but real anomaly in those measurements; his and William Ramsay's eventual realization that the anomaly was due to a previously unknown but relatively plentiful component of the atmosphere, an inert, monatomic gas; and Ramsay's subsequent successful search for other members of the inert gas family all illustrate the scientific approach to knowledge. This story can be presented to students in Rayleigh's words, annotated to supply background material and to pose questions.

  10. Argon, xenon, hydrogen, and the oxygen consumption and glycolysis of mouse tissue slices.

    PubMed

    SOUTH, F E; COOK, S F

    1954-01-20

    The effects of xenon, argon, and hydrogen on the aerobic and anaerobic metabolism of mouse liver, brain, and sarcoma slices have been investigated. Xenon was found to alter the rates of metabolism of these tissues in a manner almost identical with helium. The gas increased the rate of oxygen consumption in all three tissues and significantly depressed that of anaerobic glycolysis in brain and liver. The depression of glycolysis in sarcoma was less pronounced and not highly significant. Although both the magnitude and statistical significance of the effects observed with argon were much smaller, there was a seeming adherence to the general pattern established by xenon and helium. Hydrogen while remaining essentially ineffective insofar as oxygen uptake was concerned, depressed glycolysis in both liver and brain slices but did not significantly affect sarcoma slices. The following points are stressed in the Discussion: (1) the magnitude and direction of effects exerted by helium, argon, xenon, hydrogen, and nitrogen do not conform with the relative values of molecular weight, density, and solubility of these gases; (2) the effect of these gases on tissue metabolism does not necessarily parallel that exerted upon the whole organism.

  11. Study of argon-oxygen flowing afterglow

    NASA Astrophysics Data System (ADS)

    Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

    2016-06-01

    The reaction kinetics in argon-oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon-oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

  12. Femtosecond laser flow tagging in non-air flows

    NASA Astrophysics Data System (ADS)

    Zhang, Yibin; Calvert, Nathan

    2015-11-01

    The Femtosecond Laser Electronic Excitation Tagging (FLEET) [Michael, J. B. et al., Applied optics, 50(26), 2011] method is studied in nitrogen-containing gaseous flows. The underlying mechanism behind the FLEET process is the dissociation of molecular nitrogen into atomic nitrogen, which produces long-lived florescence as the nitrogen atoms recombine. Spectra and images of the resulting tagged line provide insight into the effects of different atmospheric gases on the FLEET process. The ionization cross-section, conductivity and energy states of the gaseous particles are each brought into consideration. These experiments demonstrate the feasibility for long-lived flow tagging on the order of hundreds of microseconds in non-air environments. Of particular interest are the enhancement of the FLEET signal with the addition of argon gas, and the non-monotonic quenching effect of oxygen on the length, duration and intensity of the resulting signal and spectra. FLEET is characterized in number of different atmospheric gases, including that simulating Mar's atmospheric composition.

  13. Argon isotope fractionation induced by stepwise heating

    NASA Astrophysics Data System (ADS)

    Trieloff, Mario; Falter, Martina; Buikin, Alexei I.; Korochantseva, Ekaterina V.; Jessberger, Elmar K.; Altherr, Rainer

    2005-03-01

    Noble gas isotopes are widely used to elucidate the history of the rocks in which they have been trapped, either from distinct reservoirs or by accumulation following radioactive decay. To extract noble gases from their host rocks, stepwise heating is the most commonly used technique to deconvolve isotopically different components, e.g., atmospheric, in situ radiogenic, or excess radiogenic from mantle or crustal reservoirs. The accurate determination of the isotopic composition of these different components is of crucial importance, e.g., for ages obtained by 40Ar- 39Ar stepheating plateaus. However, diffusion theory-based model calculations predict that the stepwise thermal extraction process from mineral phases induces isotope fractionation and, hence, adulterates the original composition. Such effects are largely unconsidered, as they are small and a compelling experimental observation is lacking. We report the first unequivocal evidence for significant mass fractionation of argon isotopes during thermal extraction, observed on shungite, a carbon-rich Precambrian sedimentary rock. The degree of fractionation, as monitored by 38Ar/ 36Ar and 40Ar/ 36Ar ratios, very well agrees with theoretical predictions assuming an inverse square root dependence of diffusion coefficient and atomic mass, resulting in easier extraction of lighter isotopes. Hence, subatmospheric 40Ar/ 36Ar ratios obtained for argon extracted at low temperatures may not represent paleoatmospheric argon. Shungite argon resembles modern atmospheric composition, but constraints on the timing of trapping appear difficult to obtain, as shungites are multicomponent systems. In 40Ar- 39Ar stepwise heating, the isotope fractionation effect could cause systematic underestimations of plateau ages, between 0.15 and 0.4% depending on age, or considerably higher if samples contain appreciable atmospheric Ar. The magnitude of this effect is similar to the presently achieved uncertainties of this increasingly

  14. Dendritic microstructure in argon atomized superalloy powders

    NASA Technical Reports Server (NTRS)

    Tewari, S. N.; Kumar, Mahundra

    1986-01-01

    The dendritic microstructure of atomized nickel base superalloy powders (Ni-20 pct Cr, NIMONIC-80A, ASTROALOY, and ZHS6-K) was studied. Prealloyed vacuum induction melted ingots were argon-atomized, the powders were cooled to room temperature, and various powder-size fractions were examined by optical metallography. Linear correlations were obtained for the powder size dependence of the secondary dendrite arm spacing, following the expected d-alpha (R) to the m power dependence on the particle size for all four superalloy compositions. However, the Ni-20 pct Cr alloy, which had much coarser arm spacing as compared to the other three alloys, had a much larger value of m.

  15. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  16. Near-infrared scintillation of liquid argon

    SciTech Connect

    Alexander, T.; Escobar, C. O.; Lippincott, W. H.; Rubinov, P.

    2016-03-03

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  17. The effect of free air carbon dioxide enrichment and nitrogen fertilisation on the chemical composition and nutritional value of wheat and barley grain.

    PubMed

    Wroblewitz, Stefanie; Hüther, Liane; Manderscheid, Remy; Weigel, Hans-Joachim; Wätzig, Hermann; Dänicke, Sven

    2013-08-01

    A rising atmospheric CO2 concentration might influence the nutrient composition of feedstuffs and consequently the nutritional value for livestock. The present study investigates the effects of atmospheric CO2 enrichment on the chemical composition and nutritional value of winter wheat cv. "Batis" and winter barley cv. "Theresa". Both cereals were grown at two different atmospheric CO2 concentrations (ambient CO2 [AMBI]: 380 ppm and enriched CO2 [free air carbon dioxide enrichment, FACE]: 550 ppm) for two growing seasons. The influence of two different nitrogen (N) fertilisation levels (adequate N supply [N100] and nearly 50% of adequate N supply [N50]) were studied as well. A significant effect was observed for the crude protein content, which declined at FACE condition in a range of 8-16 g kg(-1) in wheat and of 10-20 g kg(-1) in barley. A reduced N fertilisation level resulted in a strong reduction of crude protein concentration in both cereal species. In wheat, a decrease in N supply significantly enhanced the concentration of starch and crude fibre. In barley, only the concentration of fructose increased under FACE condition and reduced N fertilisation. The FACE did not have major effects on the concentrations of minerals, while the influence of N fertilisation was different for both cereals. Whereas no effects could be observed for barley, a reduced N supply caused a significant reduction in concentrations of zinc, manganese and iron in wheat. Furthermore, an undirected effect of atmospheric CO2 and N fertilisation levels were found for the amino acid concentrations. Based on these results, future scenarios of climate change would have an impact on the nutritional value of cereal grains.

  18. Successful production of piglets derived from expanded blastocysts vitrified using a micro volume air cooling method without direct exposure to liquid nitrogen.

    PubMed

    Misumi, Koji; Hirayama, Yuri; Egawa, Sachiko; Yamashita, Shoko; Hoshi, Hiroyoshi; Imai, Kei

    2013-12-17

    This study was conducted to clarify the feasibility of newly developed vitrification techniques for porcine embryos using the micro volume air cooling (MVAC) method without direct contact with liquid nitrogen (LN₂). Expanded blastocysts were vitrified in a solution containing 6 M ethylene glycol, 0.6 M trehalose and 2% (wt/vol) polyethylene glycol in 10% HEPES-buffered PZM-5. The blastocysts were collected from gilts and vitrified using the new device (MVAC) or a Cryotop (CT). Blastocysts were stored in LN₂ for at least 1 month. After warming, cryoprotective agents were removed using a single step. Survival of the embryos was assessed by in vitro culture (Experiment 1) and by embryo transfer to recipients (Experiment 2). In Experiment 1, the embryos vitrified by the MVAC or CT and fresh embryos without vitrification (Control) were used. The survival rates of embryos in the MVAC, CT and Control groups were 88.9% (32/36), 91.7% (33/36) and 100% (34/34), respectively, after 48 h culture, and the hatching rates of embryos after 48 h incubation were 69.4% (25/36), 63.9% (23/36) and 94.1% (32/34), respectively. In Experiment 2, 64 vitrified embryos were transferred to 5 recipient gilts, and 8 healthy piglets were produced from 3 recipients in the MVAC group. Similarly, 66 vitrified embryos were transferred to 5 recipient gilts, and 9 healthy piglets were produced from 2 recipients in the CT group. These results indicated that porcine expanded blastocysts can be cryopreserved using the MVAC method without potential pathogen contamination from LN₂.

  19. Successful Production of Piglets Derived from Expanded Blastocysts Vitrified Using a Micro Volume Air Cooling Method without Direct Exposure to Liquid Nitrogen

    PubMed Central

    MISUMI, Koji; HIRAYAMA, Yuri; EGAWA, Sachiko; YAMASHITA, Shoko; HOSHI, Hiroyoshi; IMAI, Kei

    2013-01-01

    Abstract This study was conducted to clarify the feasibility of newly developed vitrification techniques for porcine embryos using the micro volume air cooling (MVAC) method without direct contact with liquid nitrogen (LN2). Expanded blastocysts were vitrified in a solution containing 6 M ethylene glycol, 0.6 M trehalose and 2% (wt/vol) polyethylene glycol in 10% HEPES-buffered PZM-5. The blastocysts were collected from gilts and vitrified using the new device (MVAC) or a Cryotop (CT). Blastocysts were stored in LN2 for at least 1 month. After warming, cryoprotective agents were removed using a single step. Survival of the embryos was assessed by in vitro culture (Experiment 1) and by embryo transfer to recipients (Experiment 2). In Experiment 1, the embryos vitrified by the MVAC or CT and fresh embryos without vitrification (Control) were used. The survival rates of embryos in the MVAC, CT and Control groups were 88.9% (32/36), 91.7% (33/36) and 100% (34/34), respectively, after 48 h culture, and the hatching rates of embryos after 48 h incubation were 69.4% (25/36), 63.9% (23/36) and 94.1% (32/34), respectively. In Experiment 2, 64 vitrified embryos were transferred to 5 recipient gilts, and 8 healthy piglets were produced from 3 recipients in the MVAC group. Similarly, 66 vitrified embryos were transferred to 5 recipient gilts, and 9 healthy piglets were produced from 2 recipients in the CT group. These results indicated that porcine expanded blastocysts can be cryopreserved using the MVAC method without potential pathogen contamination from LN2. PMID:23955236

  20. Using air quality modeling to study source-receptor relationships between nitrogen oxides emissions and ozone exposures over the United States.

    PubMed

    Tong, Daniel Q; Muller, Nicholas Z; Kan, Haidong; Mendelsohn, Robert O

    2009-11-01

    Human exposure to ambient ozone (O(3)) has been linked to a variety of adverse health effects. The ozone level at a location is contributed by local production, regional transport, and background ozone. This study combines detailed emission inventory, air quality modeling, and census data to investigate the source-receptor relationships between nitrogen oxides (NO(x)) emissions and population exposure to ambient O(3) in 48 states over the continental United States. By removing NO(x) emissions from each state one at a time, we calculate the change in O(3) exposures by examining the difference between the base and the sensitivity simulations. Based on the 49 simulations, we construct state-level and census region-level source-receptor matrices describing the relationships among these states/regions. We find that, for 43 receptor states, cumulative NO(x) emissions from upwind states contribute more to O(3) exposures than the state's own emissions. In-state emissions are responsible for less than 15% of O(3) exposures in 90% of U.S. states. A state's NO(x) emissions can influence 2 to 40 downwind states by at least a 0.1 ppbv change in population-averaged O(3) exposure. The results suggest that the U.S. generally needs a regional strategy to effectively reduce O(3) exposures. But the current regional emission control program in the U.S. is a cap-and-trade program that assumes the marginal damage of every ton of NO(x) is equal. In this study, the average O(3) exposures caused by one ton of NO(x) emissions ranges from -2.0 to 2.3 ppm-people-hours depending on the state. The actual damage caused by one ton of NO(x) emissions varies considerably over space.

  1. The effects of free-air CO2 enrichment (FACE) on carbon and nitrogen accumulation in grains of rice (Oryza sativa L.)

    PubMed Central

    Zhu, Chunwu; Hasegawa, Toshihiro

    2013-01-01

    Rising atmospheric CO2 concentrations will probably increase rice (Oryza sativa L.) yield but decrease grain nitrogen (GN) concentration. Grains attached to different positions in the panicles differ greatly in weight and quality, but their responses to elevated CO2 (e[CO2]) are poorly understood, which limits our understanding of the mechanisms of yield enhancement and quality degradation. Thus a free-air CO2 enrichment experiment was conducted to examine the effects of e[CO2] on grain mass (GM), grain carbon (GC), and GN accumulation in the spikelets attached to the upper primary rachis branch (superior spikelets; SS) and those attached to the lower secondary rachis (inferior spikelets; IS). e[CO2] stimulated the rice yield by 13% but decreased the N concentration in the panicle by 7% when averaged over two levels of N fertilizations (P < 0.01). The responses of SS and IS to e[CO2] were different particularly under higher N supply. For SS, e[CO2] decreased GN by 24% (P < 0.01) but did not affect GM. For IS, e[CO2] increased GM by 13% (P < 0.05) but GN was not affected. The reduction of GN due to e[CO2] started to appear at the beginning of grain filling. These results suggest that future [CO2] levels probably stimulate the grain growth of IS, most of which are not marketable due to limited size, at the expense of GN reduction in SS. Translocation of N from SS to IS may be a possible mechanism for reduction in GN of SS. This may degrade the grain quality of marketable rice under e[CO2]. PMID:23918962

  2. Associations between short-term exposure to nitrogen dioxide and mortality in 17 Chinese cities: the China Air Pollution and Health Effects Study (CAPES).

    PubMed

    Chen, Renjie; Samoli, Evangelia; Wong, Chit-Ming; Huang, Wei; Wang, Zongshuang; Chen, Bingheng; Kan, Haidong

    2012-09-15

    Few multi-city studies in Asian developing countries have examined the acute health effects of ambient nitrogen dioxide (NO(2)). In the China Air Pollution and Health Effects Study (CAPES), we investigated the short-term association between NO(2) and mortality in 17 Chinese cities. We applied two-stage Bayesian hierarchical models to obtain city-specific and national average estimates for NO(2). In each city, we used Poisson regression models incorporating natural spline smoothing functions to adjust for long-term and seasonal trend of mortality, as well as other time-varying covariates. We examined the associations by age, gender and education status. We combined the individual-city estimates of the concentration-response curves to get an overall NO(2)-mortality association in China. The averaged daily concentrations of NO(2) in the 17 Chinese cities ranged from 26 μg/m(3) to 67 μg/m(3). In the combined analysis, a 10-μg/m(3) increase in two-day moving averaged NO(2) was associated with a 1.63% [95% posterior interval (PI), 1.09 to 2.17], 1.80% (95% PI, 1.00 to 2.59) and 2.52% (95% PI, 1.44 to 3.59) increase of total, cardiovascular, and respiratory mortality, respectively. These associations remained significant after adjustment for ambient particles or sulfur dioxide (SO(2)). Older people appeared to be more vulnerable to NO(2) exposure. The combined concentration-response curves indicated a linear association. Conclusively, this largest epidemiologic study of NO(2) in Asian developing countries to date suggests that short-term exposure to NO(2) is associated with increased mortality risk.

  3. Low-temperature growth of nitrogen-doped carbon nanofibers by acetonitrile catalytic CVD using Ni-based catalysts

    NASA Astrophysics Data System (ADS)

    Iwasaki, Tomohiro; Makino, Yuri; Fukukawa, Makoto; Nakamura, Hideya; Watano, Satoru

    2016-11-01

    To synthesize nitrogen-doped carbon nanofibers (N-CNFs) at high growth rates and low temperatures less than 673 K, nickel species (metallic nickel and nickel oxide) supported on alumina particles were used as the catalysts for an acetonitrile catalytic chemical vapor deposition (CVD) process. The nickel:alumina mass ratio in the catalysts was fixed at 0.05:1. The catalyst precursors were prepared from various nickel salts (nitrate, chloride, sulfate, acetate, and lactate) and then calcined at 1073 K for 1 h in oxidative (air), reductive (hydrogen-containing argon), or inert (pure argon) atmospheres to activate the nickel-based catalysts. The effects of precursors and calcination atmosphere on the catalyst activity at low temperatures were studied. We found that the catalysts derived from nickel nitrate had relatively small crystallite sizes of nickel species and provided N-CNFs at high growth rates of 57 ± 4 g-CNF/g-Ni/h at 673 K in the CVD process using 10 vol% hydrogen-containing argon as the carrier gas of acetonitrile vapor, which were approximately 4 times larger than that of a conventional CVD process. The obtained results reveal that nitrate ions in the catalyst precursor and hydrogen in the carrier gas can contribute effectively to the activation of catalysts in low-temperature CVD. The fiber diameter and nitrogen content of N-CNFs synthesized at high growth rates were several tens of nanometers and 3.5 ± 0.3 at.%, respectively. Our catalysts and CVD process may lead to cost reductions in the production of N-CNFs.

  4. Electron scattering and transport in liquid argon

    SciTech Connect

    Boyle, G. J.; Cocks, D. G.; White, R. D.; McEachran, R. P.

    2015-04-21

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies.

  5. 78 FR 63877 - Approval and Promulgation of Air Quality Implementation Plans; Delaware; Infrastructure...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-25

    ...; Infrastructure Requirements for the 2010 Nitrogen Dioxide National Ambient Air Quality Standards AGENCY... elements of the Clean Air Act (CAA), necessary to implement, maintain, and enforce the 2010 nitrogen... Environmental protection, Air pollution control, Incorporation by reference, Nitrogen dioxide, Reporting...

  6. Argon gas: a potential neuroprotectant and promising medical therapy

    PubMed Central

    2014-01-01

    Argon is a noble gas element that has demonstrated narcotic and protective abilities that may prove useful in the medical field. The earliest records of argon gas have exposed its ability to exhibit narcotic symptoms at hyperbaric pressures greater than 10 atmospheres with more recent evidence seeking to display argon as a potential neuroprotective agent. The high availability and low cost of argon provide a distinct advantage over using similarly acting treatments such as xenon gas. Argon gas treatments in models of brain injury such as in vitro Oxygen-Glucose-Deprivation (OGD) and Traumatic Brain Injury (TBI), as well as in vivo Middle Cerebral Artery Occlusion (MCAO) have largely demonstrated positive neuroprotective behavior. On the other hand, some warning has been made to potential negative effects of argon treatments in cases of ischemic brain injury, where increases of damage in the sub-cortical region of the brain have been uncovered. Further support for argon use in the medical field has been demonstrated in its use in combination with tPA, its ability as an organoprotectant, and its surgical applications. This review seeks to summarize the history and development of argon gas use in medical research as mainly a neuroprotective agent, to summarize the mechanisms associated with its biological effects, and to elucidate its future potential. PMID:24533741

  7. Design and implementation of a dedicated calorimeter for long stem SPRTs calibrations at the argon and oxygen triple points

    NASA Astrophysics Data System (ADS)

    Didi-Alaoui, I.; Fiorillo, D.; Vergé, A.; Sparasci, F.; Jouin, D.; Hermier, Y.

    2013-09-01

    Most of the thermometers used for the dissemination of the International Temperature Scale of 1990 (ITS-90) to the industry are long-stem Standard Platinum Resistance Thermometers (SPRTs). In the low temperature range, they are generally used from the triple point of water (273.16 K) down to the triple point of argon (83.805 8 K). The lack of equipment for routinely calibrating thermometers below 83 K (except comparisons at the nitrogen boiling point) limits their use at lower temperatures. The LNE-Cnam has recently developed an innovative calorimeter to improve the calibration of long-stem SPRTs at the triple point of argon and to extend the calibration range down to the oxygen triple point (54.358 4 K). Results show that at the argon triple point further investigations are needed to ascertain a reduction of the calibration uncertainty, with respect to the previous system developed by the laboratory. At the oxygen triple point, uncertainties are below the millikelvin level. With this device, the LNE-Cnam acquires the possibility to improve its calibration uncertainties for long-stem SPRTs at the argon triple point, and extends its calibration capabilities down to the triple point of oxygen.

  8. Resonant- and avalanche-ionization amplification of laser-induced plasma in air

    SciTech Connect

    Wu, Yue; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2014-10-14

    Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O₂/N₂ and O₂/Ar gas mixtures are provided to show relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O₂ 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.

  9. Effect of Emergency Argon on FCF Operational Incidents

    SciTech Connect

    Charles Solbrig

    2011-12-01

    The following report presents analyses of operational incidents which are considered in the safety analysis of the FCF argon cell and the effect that the operability of the emergency argon system has on the course of these incidents. The purpose of this study is to determine if the emergency argon system makes a significant difference in ameliorating the course of these incidents. Six incidents were considered. The following three incidents were analyzed. These are: 1. Cooling failing on 2. Vacuum Pump Failing on 3. Argon Supplies Failing on. In the remaining three incidents, the emergency argon supply would have no effect on the course of these transients since it would not come on during these incidents. The transients are 1. Loss of Cooling 2. Loss of power (Differs from above by startup delay till the Diesel Generators come on.) 3. Cell rupture due to an earthquake or other cause. The analyses of the first three incidents are reported on in the next three sections. This report is issued realizing the control parameters used may not be optimum, and additional modeling must be done to model the inertia of refrigeration system, but the major conclusion concerning the need for the emergency argon system is still valid. The timing of some events may change with a more accurate model but the differences between the transients with and without emergency argon will remain the same. Some of the parameters assumed in the analyses are Makeup argon supply, 18 cfm, initiates when pressure is = -6 iwg., shuts off when pressure is = -3.1 iwg. 170,000 ft3 supply. Min 1/7th always available, can be cross connected to HFEF argon supply dewar. Emergency argon supply, 900 cfm, initiates when pressure is = -8 iwg. shuts off when pressure is =-4 iwg. reservoir 220 ft3, refilled when tank farm pressure reduces to 1050 psi which is about 110 ft3.

  10. Charge-changing collisions of argon ions on argon gas. One-electron capture

    SciTech Connect

    Aubert, J.; Bliman, S.; Geller, R.; Jacquot, B.; Van Houtte, D.

    1980-12-01

    Single-electron-capture cross sections have been measured for argon ions with initial charges 2< or =q< or =12 incident on an argon-gas target. The cross sections show little dependence on the incident ion energy in the range 1q--10q keV. A remarkable oscillating feature is seen for cross sections sigma/sub q/,q-1 when q> or =7. Particularly, sigma/sub 8,7/ is smaller than sigma/sub 7,6/ and sigma/sub 9,8/, the Ar/sup 8 +/ electronic structure being Ne-like. Variation of the cross section is shown as function of the initial charge at constant energy.

  11. Attosecond Time-Resolved Autoionization of Argon

    SciTech Connect

    Wang He; Chini, Michael; Chen Shouyuan; Zhang Changhua; Cheng Yan; Wu Yi; Thumm, Uwe; He Feng; Chang Zenghu

    2010-10-01

    Autoionization of argon atoms was studied experimentally by transient absorption spectroscopy with isolated attosecond pulses. The peak position, intensity, linewidth, and shape of the 3s3p{sup 6}np {sup 1}P Fano resonance series (26.6-29.2 eV) were modified by intense few-cycle near infrared laser pulses, while the delay between the attosecond pulse and the laser pulse was changed by a few femtoseconds. Numerical simulations revealed that the experimentally observed splitting of the 3s3p{sup 6}4p {sup 1}P line is caused by the coupling between two short-lived highly excited states in the strong laser field.

  12. Merging of high speed argon plasma jets

    SciTech Connect

    Case, A.; Messer, S.; Brockington, S.; Wu, L.; Witherspoon, F. D.; Elton, R.

    2013-01-15

    Formation of an imploding plasma liner for the plasma liner experiment (PLX) requires individual plasma jets to merge into a quasi-spherical shell of plasma converging on the origin. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present results from the study of the merging of three plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. 1 cm Minirailguns with a preionized argon plasma armature. The vacuum chamber partially reproduces the port geometry of the PLX chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

  13. Vibrational relaxation of chloroiodomethane in cold argon

    NASA Astrophysics Data System (ADS)

    Jain, Amber; Sibert, Edwin L.

    2013-10-01

    Electronically exciting the C-I stretch in the molecule chloroiodomethane CH2ClI embedded in a matrix of argon at 12 K can lead to an isomer, iso-chloroiodomethane CH2Cl-I, that features a chlorine iodine bond. By temporally probing the isomer at two different frequencies of 435 nm and 485 nm, multiple timescales for isomerization and vibrational energy relaxation were inferred [T. J. Preston, et al., J. Chem. Phys. 135, 114503 (2011)]. This relaxation is studied theoretically using molecular dynamics by considering 2 and 3 dimensional models. Multiple decay rate constants of the same order of magnitude as the experiment are observed. These decay rate constants are interpreted within the context of the Landau-Teller theory. Sensitivity of the decay rate constants on the bath and system parameters shed more light into the mechanism of vibrational energy relaxation.

  14. Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

    NASA Astrophysics Data System (ADS)

    Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

    2007-09-01

    A nonequilibrium Ar /O2 plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar /O2 plasma jet at an exposure distance of 0.5-1.5cm ranges from 5 to 57s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

  15. Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

    SciTech Connect

    Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

    2007-09-15

    A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

  16. Alloy dissolution in argon stirred steel

    NASA Astrophysics Data System (ADS)

    Webber, Darryl Scott

    Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I low carbon ferromanganese, nickel and tin (as a surrogate for low melting alloys) and Class II ferroniobium. The alloys ranged in size and form from granular to 30 mm diameter lumps. Experimental results were evaluated using a theoretically based numerical model for the steel shell period, alloy mixing (Class I) and alloy dissolution (Class II). A CFD model of the experimental ladle was used to understand steel motion in the ladle and to provide steel velocity magnitudes for the numerical steel shell model. Experiments and modeling confirmed that smaller sized alloys have shorter steel shell periods and homogenize faster than larger particles. Increasing the argon flow rate shortened mixing times and reduced the delay between alloy addition and the first appearance of alloy in the melt. In addition, for every five degree increase in steel bath temperature the steel shell period was shortened by approximately four percent. Class II ferroniobium alloy dissolution was an order of magnitude slower than Class I alloy mixing.

  17. The Liquid Nitrogen Fountain

    NASA Astrophysics Data System (ADS)

    McRae, Robin; Rahn, Jeffrey A.; Beamer, Timothy W.; Lebret, Norm

    2002-10-01

    Details of a demonstration using liquid nitrogen are presented. The demonstration is based on a 500-mL transparent polyethylene soft-drink bottle with a screw-on pop-up drink top. Prior to the demonstration, a balloon is placed over the popped-up spout of the bottle top. The bottle is filled with liquid nitrogen and the top, with the balloon affixed, is quickly put in place and screwed on tightly. As the liquid nitrogen in the bottle boils, the balloon inflates. When the balloon bursts the noise produced is far greater than would ordinarily be expected, and a fountain of liquid nitrogen and condensing water vapor shoots into the air above the bottle.

  18. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

    2013-11-01

    An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of ˜2 × 1013 cm-3, argon metastable densities ˜1014 cm-3 and a reduced electric field about 10 Td are determined.

  19. Elevated CO{sub 2} in a prototype free-air CO{sub 2} enrichment facility affects photosynthetic nitrogen relations in a maturing pine forest

    SciTech Connect

    Ellsworth, D.S.; LaRoche, J.; Hendrey, G.R.

    1998-03-01

    A maturing loblolly pine (Pinus taeda L.) forest was exposed to elevated CO{sub 2} in the natural environment in a perturbation study conducted over three seasons using the free-air CO{sub 2} enrichment (FACE) technique. At the time measurements were begun in this study, the pine canopy was comprised entirely of foliage which had developed under elevated CO{sub 2} conditions (atmospheric CO{sub 2} {approx} 550 {micro}mol/mol{sup {minus}1}). Measurements of leaf photosynthetic responses to CO{sub 2} were taken to examine the effects of elevated CO{sub 2} on photosynthetic N nutrition in a pine canopy under elevated CO{sub 2}. Photosynthetic CO{sub 2} response curves (A-c{sub i} curves) were similar in FACE trees under elevated CO{sub 2} compared with counterpart trees in ambient plots for the first foliage cohort produced in the second season of CO{sub 2} exposure, with changes in curve form detected in the foliage cohorts subsequently produced under elevated CO{sub 2}. Differences in the functional relationship between carboxylation rate and N{sub a} suggest that for a given N{sub a} allocated among successive cohorts of foliage in the upper canopy, V{sub c max} was 17% lower in FACE versus Ambient trees. The authors also found that foliar Rubisco content per unit total protein derived from Western blot analysis was lower in late-season foliage in FACE foliage compared with ambient-grown foliage. The results illustrate a potentially important mode of physiological adjustment to growth conditions that may operate in forest canopies. Findings suggest that mature loblolly pine trees growing in the field may have the capacity for shifts in intrinsic nitrogen utilization for photosynthesis under elevated CO{sub 2} that are not dependent on changes in leaf N. Findings suggest a need for continued examination of internal feedbacks at the whole-tree and ecosystem level in forests that may influence long-term photosynthetic responses to elevated CO{sub 2}.

  20. ELEVATED CO{sub 2} IN A PROTOTYPE FREE-AIR CO{sub 2} ENRICHMENT FACILITY AFFECTS PHOTOSYNTHETIC NITROGEN RELATIONS IN A MATURING PINE FOREST

    SciTech Connect

    ELLSWORTH,D.S.; LA ROCHE,J.; HENDREY,G.R.

    1998-03-01

    A maturing loblolly pine (Pinus taeda L.) forest was exposed to elevated CO{sub 2} in the natural environment in a perturbation study conducted over three seasons using the free-air CO{sub 2} enrichment (FACE) technique. At the time measurements were begun in this study, the pine canopy was comprised entirely of foliage which had developed under elevated CO{sub 2} conditions (atmospheric [CO{sub 2}] {approx} 550 {micro}mol mol{sup {minus}1}). Measurements of leaf photosynthetic responses to CO{sub 2} were taken to examine the effects of elevated CO{sub 2} on photosynthetic N nutrition in a pine canopy under elevated CO{sub 2}. Photosynthetic CO{sub 2} response curves (A-c{sub i} curves) were similar in FACE trees under elevated CO{sub 2} compared with counterpart trees in ambient plots for the first foliage cohort produced in the second season of CO{sub 2} exposure, with changes in curve form detected in the foliage cohorts subsequently produced under elevated CO{sub 2}. Differences in the functional relationship between carboxylation rate and N{sub a} suggest that for a given N{sub a} allocated among successive cohorts of foliage in the upper canopy, V{sub c max} was 17% lower in FACE versus Ambient trees. The authors also found that foliar Rubisco content per unit total protein derived from Western blot analysis was lower in late-season foliage in FACE foliage compared with ambient-grown foliage. The results illustrate a potentially important mode of physiological adjustment to growth conditions that may operate in forest canopies. Their findings suggest that mature loblolly pine trees growing in the field may have the capacity for shifts in intrinsic nitrogen utilization for photosynthesis under elevated CO{sub 2} that are not dependent on changes in leaf N. While carboxylation efficiency per unit N apparently decreased under elevated CO{sub 2}, photosynthetic rates in trees at elevated CO{sub 2} concentrations {approx} 550 pmol mol{sub {minus}1} are still

  1. The study of gas species on THz generation from laser-induced air plasma

    NASA Astrophysics Data System (ADS)

    Zhao, Ji; Zhang, LiangLiang; Wu, YiJian; Wu, Tong; Yuan, Hui; Zhang, CunLin; Zhao, YueJin

    2015-08-01

    Intense Terahertz waves generated from air-induced plasma and serving as broadband THz source provide a promising broadband source for innovative technology. Terahertz generation in selected gases has attracted more and more researchers' interests in recent years. In this research, the THz emission from different atoms is described, such as nitrogen, argon and helium in Michelson. The THz radiation is detected by a Golay Cell equipped with a 6-mm-diameter diamond-inputting window. It can be seen in the first time that when the pump power lies at a stable level, the THz generation created by the femtosecond laser focusing on the nitrogen is higher than which focusing on the helium, and lower than that produced in the argon gas environment. We believe that the THz intensity is Ar > N > Ne because of its atomic mass, which is Ar > N > Ne as well. It is clear that the Gas molecular decides the release of free electrons ionized from ultra short femtosecond laser through the electronic dynamic analysis. The higher the gas mass is, the stronger the terahertz emission will be. We further explore the THz emission at the different laser power levels, and the experimental results can be commendably quadratic fitted. It can be inferred that THz emission under different gas medium environment still complies with the law of four-wave mixing (FWM) process and has nothing to do with the gas environment: the radiation energy is proportional to the quadratic of incident laser power.

  2. Indicators: Nitrogen

    EPA Pesticide Factsheets

    Nitrogen, like phosphorus, is a critical nutrient required for all life. Nitrogen can occur in rivers and streams, lakes, and coastal waters in several forms including ammonia (NH3), nitrates (NO3), and nitrites (NO2).

  3. Soil carbon storage and N{sub 2}O emissions from wheat agroecosystems as affected by free-air CO{sub 2} enrichment (FACE) and nitrogen treatments. Final Report - February 12, 1999

    SciTech Connect

    S. W. Leavitt; A. D. Matthias; T. L. Thompson; R. A. Rauschkolb

    1999-02-17

    Rising atmospheric CO{sub 2} concentrations have prompted concern about response of plants and crops to future elevated CO{sub 2} levels, and particularly the extent to which ecosystems will sequester carbon and thus impact the rate of rise of CO{sub 2} concentrations. Free-air CO{sub 2} enrichment (FACE) experimentation was used with wheat agroecosystems for two growing seasons to assess effects of CO{sub 2} and soil nitrogen. Over 20 researchers on this experiment variously examined plant production and grain yield, phenology, length of growing season, water-use efficiency ecosystem production, below ground processes (eg, root and microbial activity, carbon and nitrogen cycling), etc.

  4. Electrochemical sensors for volatile nitrogen compounds in air. Final report to J&N Associates, Inc. from Illinois Institute of Technology, Re: Department of Energy Phase I STTR Project DOE No. DE-FG02-99ER86090

    SciTech Connect

    Stetter, Joseph R.; Penrose, William R.; Roh, Sae-Won

    2000-09-07

    Air pollutant gases such as nitric oxide, nitrogen dioxide, nitrous acid, and peroxyacetyl nitrate are commonly encountered in urban atmospheres. They constitute a nuisance to some, and a positive danger to others with such respiratory conditions as asthma and emphysema. It is known that exposure to these gases is a function of microenvironment, but monitoring of microenvironments is presently too uneconomical to be used except in rare cases, such as ''sick buildings''. Gas sensors that are small, sensitive, selective, and inexpensive are needed to make such monitoring practical. Many sensor types have apparently reached their technological development limit, but porous-electrode amperometric gas sensors have not been thoroughly explored for low-concentration applications. We have explored amperometric gas sensors of several types for lower detection limits to a series of nitrogen gases. Evidence gathered in this study indicates that greater sensitivity will be achieved by reducing the noise level of the working electrode, rather than increasing the output signal.

  5. Field Comparison of Passive Air Samplers with Reference Monitors for Ambient Volatile Organic Compounds and Nitrogen Dioxide Under Week-Long Integrals

    EPA Science Inventory

    This study evaluates performance of nitrogen dioxide NO2 and volatile organic compounds (VOC) passive samplers with corresponding reference monitors at two sites in the Detroit, Michigan area during the summer of 2005.

  6. Fact Sheets and Additional Information Regarding the 2010 Revision to the Primary National Ambient Air Quality Standards (NAAQS) for Nitrogen Dioxide (NO2)

    EPA Pesticide Factsheets

    Find tools for primary standards for Nitrogen Dioxide, maps of monitoring areas, an overview of the proposal, monitor requirements, design values for counties, and a presentation on the 2010 NO2 primary NAAQS revision.

  7. Measurement of air-surface exchange of speciated nitrogen and sulfur compounds using a modified MARGA 2S: ? Concentrations and fluxes above a grass field

    EPA Science Inventory

    Improved measurement methods are needed to characterize dry deposition of sulfur and nitrogen compounds to assess ecosystem exposure to nutrients and acidifying compounds and to develop atmospheric deposition budgets in support of critical loads assessments. The purpose of this s...

  8. Measurement of air-surface exchange of speciated nitrogen and sulfur compounds using a modified MARGA 2S: Assessment and control of data quality

    EPA Science Inventory

    Improved measurement methods are needed to characterize dry deposition of sulfur and nitrogen compounds to assess ecosystem exposure to nutrients and acidifying compounds and to develop atmospheric deposition budgets in support of critical loads assessments. The purpose of this ...

  9. Extreme argon purity in a large, non-evacuated cryostat

    SciTech Connect

    Tope, Terry; Adamowski, Mark; Carls, B.; Hahn, A.; Jaskierny, W.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Skup, E.; Stancari, M.; Yang, T.

    2014-01-29

    Liquid Argon Time Projection Chambers (LArTPCs) show promise as scalable devices for the large detectors needed for long-baseline neutrino oscillation physics. Over the last several years at Fermilab a staged approach to developing the technology for large detectors has been developed. The TPC detectors require ultra-pure liquid argon with respect to electronegative contaminants such as oxygen and water. The tolerable electronegative contamination level may be as pure as 60 parts per trillion of oxygen. Three liquid argon cryostats operated at Fermilab have achieved the extreme purity required by TPCs. These three cryostats used evacuation to remove atmospheric contaminants as the first purification step prior to filling with liquid argon. Future physics experiments may require very large detectors with tens of kilotonnes of liquid argon mass. The capability to evacuate such large cryostats adds significant cost to the cryostat itself in addition to the cost of a large scale vacuum pumping system. This paper describes a 30 ton liquid argon cryostat at Fermilab which uses purging to remove atmospheric contaminants instead of evacuation as the first purification step. This cryostat has achieved electronegative contamination levels better than 60 parts per trillion of oxygen equivalent. The results of this liquid argon purity demonstration will strongly influence the design of future TPC cryostats.

  10. AIR INFILTRATION MEASUREMENTS USING TRACER GASES: A LITERATURE REVIEW

    EPA Science Inventory

    The report gives results of a literature review of air filtration measurements using tracer gases, including sulfur hexafluoride, hydrogen, carbon monoxide, carbon dioxide, nitrous oxide, and radioactive argon and krypton. Sulfur hexafluoride is the commonest tracer gas of choice...

  11. Nitrogen Species in Soil, Sediment, and Ground Water at a Former Sewage-Treatment Wastewater Lagoon: Naval Air Station Whidbey Island, Island County, Washington

    USGS Publications Warehouse

    Cox, S.E.; Dinicola, R.S.; Huffman, R.L.

    2007-01-01

    The potential for contamination of ground water from remnant sewage sludge in re-graded sediments of a deconstructed sewage-treatment lagoon was evaluated. Ground-water levels were measured in temporary drive-point wells, and ground-water samples were collected and analyzed for nutrients and other water-quality characteristics. Composite soil and sediment samples were collected and analyzed for organic carbon and nitrogen species. Multiple lines of evidence, including lack of appreciable organic matter in sediments of the former lagoon, agronomic analysis of nitrogen, the sequestration of nitrogen in the developing soils at the former lagoon, and likely occurrence of peat deposits within the aquifer material, suggest that the potential for substantial additions of nitrogen to ground water beneath the former sewage lagoon resulting from remnant sewage sludge not removed from the former lagoon are small. Concentrations of nitrogen species measured in ground-water samples were small and did not exceed the established U.S. Environmental Protection Agency's maximum contaminant levels for nitrate (10 milligrams per liter). Concentrations of nitrate in ground-water samples were less than the laboratory reporting limit of 0.06 milligram per liter. Seventy to 90 percent of the total nitrogen present in ground water was in the ammonia form with a maximum concentration of 7.67 milligrams per liter. Concentrations of total nitrogen in ground water beneath the site, which is the sum of all forms of nitrogen including nitrate, nitrite, ammonia, and organic nitrogen, ranged from 1.15 to 8.44 milligrams per liter. Thus, even if all forms of nitrogen measured in ground water were converted to nitrate, the combined mass would be less than the maximum contaminant level. Oxidation-reduction conditions in ground water beneath the former sewage lagoon were reducing. Given the abundant supply of ambient organic carbon in the subsurface and in ground water at the former lagoon, any

  12. The argon-induced decline in nitrogenase activity commences before the beginning of a decline in nodule oxygen uptake.

    PubMed

    Fischinger, Stephanie A; Schulze, Joachim

    2010-09-01

    Replacement of N(2) by argon in the air around nodules directs nitrogenase electron flow in its total onto H(+) resulting in increased nodule H(2) evolution (total nitrogenase activity (TNA)). However, argon application induces a so-called argon-induced decline in nitrogenase activity (Ar-ID) connected with decreased nodule oxygen permeability. Consequently, TNA measurements tend to underestimate total nitrogenase activity. It is unclear whether the decline in oxygen diffusion into nodules induces the Ar-ID, or whether a decline in nitrogenase activity is followed by lower nodule O(2) uptake. The objective of the present work was to examine the time sequence of the decline in nodule H(2) evolution and O(2) uptake after argon application. In addition, the reliability of TNA values, taken as quickly as possible after the switch to Ar/O(2), was tested through comparative measurement of (15)N(2) uptake of the same plants. Short-term TNA measurements in an optimized gas exchange measurement system yielded reliable results, verified by parallel determination of (15)N(2) uptake. A five min application of Ar/O(2) was without effect on the subsequent H(2) evolution in ambient air. A parallel experiment on control plants revealed that a decrease in nodule oxygen uptake began several minutes after the onset of the decline in H(2) evolution. We conclude that the primary effect of the replacement of N(2) by argon differs from oxygen diffusion control. A gas exchange system allowing an immediate taking of TNA yields reliable results and does not disturb nodule activity. Gas exchange measurements provide a powerful tool for studying nodule physiology and should be combined with material from molecular studies.

  13. Modeling Electronegative Impurity Concentrations in Liquid Argon Detectors

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Li, Yichen; Thorn, Craig; Qian, Xin

    2017-01-01

    Achieving long electron lifetime is crucial to reach the high performance of large Liquid Argon Time Projection Chamber (LArTPC) envisioned for next generation neutrino experiments. We have built up a quantitative model to describe the impurity distribution and transportation in a cryostat. Henrys constants of Oxygen and water, which describe the partition of impurities between gas argon and liquid argon, have been deduced through this model with the measurements in BNL 20-L LAr test stand. These results indicate the importance of the gas purification system and prospects on large LArTPC detectors will be discussed.

  14. Practical reactor production of 41Ar from argon clathrate.

    PubMed

    Mercer, J R; Duke, M J; McQuarrie, S A

    2000-06-01

    The radionuclide 41Ar has many ideal properties as a gas flow tracer. However, the modest cross-section of 40Ar for thermal neutron activation makes preparation of suitable activities of 41Ar technically difficult particularly for low flux reactors. Argon can however be trapped in a molecular complex called a clathrate that can then be irradiated. We prepared argon clathrate and explored its irradiation and stability characteristics. Argon clathrate can be used to provide gigabecquerel quantities of 41Ar even with low power reactors.

  15. Seasonal variation of Argon in the martian atmosphere as measured by Spirit and Opportunity MER rovers

    NASA Astrophysics Data System (ADS)

    Economou, Thanasis

    Although there were no meteorological devices on any of the 2 rovers of the MER mission, by using the excellent ability of the Alpha Particle X-ray Spectrometer (APXS) to detect even a small amount of the Ar gas in a predominantly CO2 martian atmosphere, we were able to obtain detailed information on the variability of the atmospheric Ar as a function of seasonal changes. The technique is simple and straightforward. In order to increase the accuracy of the technique by eliminating any interference from target elements and minimizing the background from the backscattered Pu-L X-ray lines, dedicated APXS atmospheric Ar measurements were performed over a period of almost 4 martian years. In that mode the only visible peak in the x-ray spectra is the Ar Kα x-ray line at energy Eα=2.96 keV. Polar condensation of CO2 during winter periods, when the temperature falls below the freezing point of CO2, causes massive movement of air masses from the equatorial regions towards the poles. As the CO2 freezes, the remaining air there is enriched in argon (and nitrogen). The GRS experiment on the Odyssey orbiter around Mars has observed a six-fold in the Ar/CO2 mixing ratio in the southern polar region during the winter period. During the summer season, the opposite occurs: sublimating CO2 increases the atmospheric pressure and creates an atmospheric high that pushes the air mass with an enriched Ar fraction towards the equatorial regions where when arrives it is detected by the APXS on the Opportunity and Spirit landing sites. Our results indicate that the variation of the Ar in the martian atmosphere at both landing sites follows generally the variation of the atmospheric pressure, but it is not in phase with it: there is a phase shift of almost one martian season. The measurement of the Ar mixing ratio at the Spirit and Opportunity landing sites is thus a direct probe of the global circulation between the polar CO2 resource/sink and the equatorial regions. This information is

  16. Study of nuclear recoils in liquid argon with monoenergetic neutrons

    NASA Astrophysics Data System (ADS)

    Regenfus, C.; Allkofer, Y.; Amsler, C.; Creus, W.; Ferella, A.; Rochet, J.; Walter, M.

    2012-07-01

    In the framework of developments for liquid argon dark matter detectors we assembled a laboratory setup to scatter neutrons on a small liquid argon target. The neutrons are produced mono-energetically (Ekin = 2.45 MeV) by nuclear fusion in a deuterium plasma and are collimated onto a 3" liquid argon cell operating in single-phase mode (zero electric field). Organic liquid scintillators are used to tag scattered neutrons and to provide a time-of-flight measurement. The setup is designed to study light pulse shapes and scintillation yields from nuclear and electronic recoils as well as from alpha particles at working points relevant for dark matter searches. Liquid argon offers the possibility to scrutinise scintillation yields in noble liquids with respect to the population strength of the two fundamental excimer states. Here we present experimental methods and first results from recent data towards such studies.

  17. Mars Atmosphere Argon Density Measurement on MER Mission

    NASA Astrophysics Data System (ADS)

    Economou, T. E.

    2008-11-01

    Using the Alpha Particle X-ray Spectrometer (APXS) on board Spirit and Opportunity rovers on MER mission, we were able to measure the argon density variation in the martian atmosphere as a function of seasonal changes.

  18. Cryogenic CMOS cameras for high voltage monitoring in liquid argon

    NASA Astrophysics Data System (ADS)

    McConkey, N.; Spooner, N.; Thiesse, M.; Wallbank, M.; Warburton, T. K.

    2017-03-01

    The prevalent use of large volume liquid argon detectors strongly motivates the development of novel readout and monitoring technology which functions at cryogenic temperatures. This paper presents the development of a cryogenic CMOS camera system suitable for use inside a large volume liquid argon detector for online monitoring purposes. The characterisation of the system is described in detail. The reliability of such a camera system has been demonstrated over several months, and recent data from operation within the liquid argon region of the DUNE 35 t cryostat is presented. The cameras were used to monitor for high voltage breakdown inside the cryostat, with capability to observe breakdown of a liquid argon time projection chamber in situ. They were also used for detector monitoring, especially of components during cooldown.

  19. Electron avalanches in liquid argon mixtures

    SciTech Connect

    Kim, J.G.; Dardin, S.M.; Kadel, R.W.; Kadyk, J.A.; Wenzel, W.B.; Peskov, V.

    2004-03-19

    We have observed stable avalanche gain in liquid argon when mixed with small amounts of xenon in the high electric field (>7 MV/cm) near the point of a chemically etched needle in a point-plane geometry. We identify two gain mechanisms, one pressure dependent, and the other independent of the applied pressure. We conclude that the pressure dependent signals are from avalanche gain in gas bubbles at the tip of the needle, while the pressure independent pulses are from avalanche gain in liquid. We measure the decay time spectra of photons from both types of avalanches. The decay times from the pressure dependent pulses decrease (increase) with the applied pressure (high voltage), while the decay times from the pressure independent pulses are approximately independent of pressure or high voltage. For our operating conditions, the collected charge distribution from avalanches is similar for 60 keV or 122 keV photon sources. With krypton additives, instead of Xe, we measure behavior consistent with only the pressure dependent pulses. Neon and TMS were also investigated as additives, and designs for practical detectors were tested.

  20. Mars MITgcm and Argon in the Martian Atmosphere

    NASA Astrophysics Data System (ADS)

    Lian, Yuan; Richardson, M.; Newman, C.; Lee, C. M.; Toigo, A.; Mischna, M.; Campin, J.

    2010-10-01

    Mars Odyssey observed that Argon abundance was greatly enhanced during winter solstice at southern pole in Martian atmosphere. The Argon enrichment factor can reach as high as 6-7. Several studies have examined the mechanisms that cause such enrichment. Current Mars GCMs can produce the seasonal variation of Argon enhancement to some degree. However, they only reproduce aspects of the trend and generally predict an enhancement factor of about 2-3 times smaller than observed. To address the problem of Argon transport, we have developed a new Mars GCM based on the MITgcm, a state-of-art global circulation model, and the Mars atmospheric physics as implemented in PlanetWRF. The Mars MITgcm uses cube-sphere grid finite volume numerics and has several options for the tracer advection scheme. The Mars MITgcm includes topography, a subsurface scheme, a planetary boundary layer, atmospheric dust distribution, radiative transfer and a CO2 cycle. Our model results show close agreement with the annual variability of pressure measured at the Viking Lander sites, as well as matches to MCS temperature profiles. For Argon, unlike prior studies, we tested various tracer advection schemes and found significant variations depending on the quality of the schemes used. We suggest that much of the variations between different prior modeling studies is plausibly related to differences in the advection schemes used. We found that, at 2.5-degree grid resolution, advection schemes with flux limiters provide good match to the Argon enhancement factor for observations for 75 degree poleward in southern winter. Preliminary diagnoses of model results suggest that the polar Argon enhancement during summer solstice results from: first, Argon is transported poleward and trapped by polar vortex; second, the enhancement factor gets larger when more CO2 is condensed. Our work thus far suggests that the Mars MITgcm is ready for solving future scientific questions.

  1. Common Blepharitis Related to Phthiriasis Palpebrarum: Argon Laser Phototherapy.

    PubMed

    Sundu, Cem; Dinç, Erdem; Kurtuluş, Umut Can; Yıldırım, Özlem

    2015-09-01

    A 42-year-old woman was admitted to Mersin University, Department of Ophthalmology Clinic with itching and burning sensation of the right eye for 3 weeks. In her slit-lamp examination, nits and lice, attached to the upper and lower eyelashes of her right eye, were observed. Lice and nits were destroyed by argon laser phototherapy and were removed with the help of a fine forceps thereafter. Argon laser phototherapy is a quick, effective, and safe treatment modality for phthiriasis palpebrarum.

  2. Radiant properties of strong shock waves in argon.

    PubMed

    Taylor, W H; Kane, J W

    1967-09-01

    Measurements of the visible radiation emitted by one dimensional, explosively generated, shock waves in argon initially at 1 atm are reported. A time-resolved spectrograph and calibrated photodetectors were used to measure the intensity of the source at 5450 A and 4050 A. The results show that explosive induced shock waves in argon having shock velocities in the range 8-9 mm/microusec radiate at these wavelengths like a blackbody having a temperature of approximately 23,000 degrees K.

  3. METHANE AND NITROGEN ABUNDANCES ON PLUTO AND ERIS

    SciTech Connect

    Tegler, S. C.; Cornelison, D. M.; Abernathy, M. R.; Bovyn, M. J.; Burt, J. A.; Evans, D. E.; Maleszewski, C. K.; Thompson, Z.; Grundy, W. M.; Romanishin, W.; Vilas, F. E-mail: David.Cornelison@nau.ed E-mail: wjr@nhn.ou.ed

    2010-12-10

    We present spectra of Eris from the MMT 6.5 m Telescope and Red Channel Spectrograph (5700-9800 A, 5 A pixel{sup -1}) on Mt. Hopkins, AZ, and of Pluto from the Steward Observatory 2.3 m Telescope and Boller and Chivens Spectrograph (7100-9400 A, 2 A pixel{sup -1}) on Kitt Peak, AZ. In addition, we present laboratory transmission spectra of methane-nitrogen and methane-argon ice mixtures. By anchoring our analysis in methane and nitrogen solubilities in one another as expressed in the phase diagram of Prokhvatilov and Yantsevich, and comparing methane bands in our Eris and Pluto spectra and methane bands in our laboratory spectra of methane and nitrogen ice mixtures, we find Eris' bulk methane and nitrogen abundances are {approx}10% and {approx}90% and Pluto's bulk methane and nitrogen abundances are {approx}3% and {approx}97%. Such abundances for Pluto are consistent with values reported in the literature. It appears that the bulk volatile composition of Eris is similar to the bulk volatile composition of Pluto. Both objects appear to be dominated by nitrogen ice. Our analysis also suggests, unlike previous work reported in the literature, that the methane and nitrogen stoichiometry is constant with depth into the surface of Eris. Finally, we point out that our Eris spectrum is also consistent with a laboratory ice mixture consisting of 40% methane and 60% argon. Although we cannot rule out an argon-rich surface, it seems more likely that nitrogen is the dominant species on Eris because the nitrogen ice 2.15 {mu}m band is seen in spectra of Pluto and Triton.

  4. Effects of argon gas flow rate on laser-welding.

    PubMed

    Takayama, Yasuko; Nomoto, Rie; Nakajima, Hiroyuki; Ohkubo, Chikahiro

    2012-01-01

    The purpose of this study was to evaluate the effects of the rate of argon gas flow on joint strength in the laser-welding of cast metal plates and to measure the porosity. Two cast plates (Ti and Co-Cr alloy) of the same metal were abutted and welded together. The rates of argon gas flow were 0, 5 and 10 L/min for the Co-Cr alloy, and 5 and 10 L/min for the Ti. There was a significant difference in the ratio of porosity according to the rate of argon gas flow in the welded area. Argon shielding had no significant effect on the tensile strength of Co-Cr alloy. The 5 L/min specimens showed greater tensile strength than the 10 L/min specimens for Ti. Laser welding of the Co-Cr alloy was influenced very little by argon shielding. When the rate of argon gas flow was high, joint strength decreased for Ti.

  5. MODELING ASSESSMENT OF THE IMPACT OF NITROGEN OXIDES EMISSION REDUCTIONS ON OZONE AIR QUALITY IN THE EASTERN UNITED STATES: OFFSETTING INCREASES IN ENERGY USE

    EPA Science Inventory

    The objective of this study is to examine changes in ambient ozone concentrations estimated by a photochemical air quality model in response to the NOx emission reductions imposed on the utility sector. To accomplish this task, CMAQ air quality model simulations were performe...

  6. Participant-Based Monitoring of Indoor and Outdoor Nitrogen Dioxide, Volatile Organic Compounds, and Polycyclic Aromatic Hydrocarbons among MICA-Air Households

    EPA Science Inventory

    The Mechanistic Indicators of Childhood Asthma (MICA) study in Detroit, Michigan introduced a participant-based approach to reduce the resource burden associated with collection of indoor and outdoor residential air sampling data. A subset of participants designated as MICA-Air c...

  7. A Mach 6 external nozzle experiment with Argon-Freon exhaust simulation

    NASA Technical Reports Server (NTRS)

    Pittman, James L.

    1989-01-01

    A scramjet exhaust simulation technique for hypersonic wind tunnel testing has been developed. Mixtures of Argon and Freon correctly match the inviscid simulation parameters of Mach number, static-pressure ratio, and the ratio of specific heats at the combustor exit location; this simulation is accomplished at significantly reduced temperatures and without combustion. An investigation of nozzle parametrics in a Mach 6 freestream showed that the external nozzle ramp angle, the cowl trailing-edge angle, an external nozzle flow fence and the nozzle static-pressure ratio significantly affected the external nozzle thrust and pitching moment as measured by the integration of surface-pressure data. A comparison of Argon-Freon and air exhaust simulation showed that the external nozzle thrust and pitching moment were in error by roughly a factor of 2 using air due to the incorrect match of the ratio of specific heats. An assessment of two-dimensional Euler and Navier-Stokes codes for predicting external nozzle aerodynamic characteristics was made by comparing computed and experimental results.

  8. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    SciTech Connect

    Stöber, Laura Patocka, Florian Schneider, Michael Schmid, Ulrich; Konrath, Jens Peter Haberl, Verena

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  9. Concerning Apparent Similarity of Structures of Fluoropolymer Surfaces Exposed to an Argon Plasma or Argon Ion Beam

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Covington, M. Alan (Technical Monitor)

    1995-01-01

    X-ray photoelectron spectroscopy (XPS) C(sub 1s) spectra of fluoropolymers exposed to either an argon plasma or argon ion beam show remarkable similarity, implying that the surface-modification reactions for these two processes likely proceed through comparable mechanisms, revolving predominantly ion-surface interactions. The importance of working with a monochromatized x-ray source for XPS analysis of the surface-modified fluoropolymers is once again emphasized.

  10. Chemical effect of inert argon beam on nitride nanolayer formed by ion implantation into GaAs surface

    NASA Astrophysics Data System (ADS)

    Mikoushkin, V. M.

    2010-12-01

    The composition of a nitride nanolayer formed on a GaAs(100) surface by the implantation of ions with an energy of E i = 2.5 keV and the chemical state of nitrogen in this layer have been studied by the method of Auger electron spectroscopy. It is established that, in addition to GaN, a GaAsN solid solution phase is formed in the ion-implanted layer. The energies of N KVV Auger electron transitions in these phases are determined as E A (GaN) = 379.8 ± 0.2 eV and E A (GaAsN) = 382.8 ± 0.2 eV (relative to the Fermi level), which allowed the distribution of nitrogen between these phases to be evaluated as [N(GaN)] = 70% and [N(GaAsN)] = 30%. It is established that an argon ion beam produces a chemical effect on the nitride layer, which is related to a cascade mixing of the material. Under the action of the argon ion bombardment, the distribution of nitrogen in the indicated phases changes to opposite. As a result a nitride nanolayer is formed in which the narrow-bandgap semiconductor (GaAsN) predominates rather than the wide-bandgap component (GaN).

  11. OBSERVATION-BASED ASSESSMENT OF THE IMPACT OF NITROGEN OXIDES EMISSIONS REDUCTIONS ON OZONE AIR QUALITY OVER THE EASTERN UNITED STATES

    EPA Science Inventory

    Ozone is produced by chemical interactions involving nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs) in the presence of sunlight. At high concentrations, ground-level ozone has been shown to be harmful to human health and the environment. It has been reco...

  12. Wear and Tribological Properties of Silicon-Containing Diamond-Like Carbon (Si-DLC) Coatings Synthesized with Nitrogen, Argon Plus Nitrogen, and Argon Ion Beams

    DTIC Science & Technology

    1998-06-01

    polymers on our Si-DLC coatings, we may attribute the improvements in properties to a consequence of cross-linking of the precursor material caused by the... ENGEN THAYERHALL WEST POINT NY 10996-1786 1 DIRECTOR US ARMY RESEARCH LAB AMSRLCSALTP 2800 POWDER MILL RD ADELPHI MD 20783-1145 1

  13. Communication: Trapping a proton in argon: Spectroscopy and theory of the proton-bound argon dimer and its solvation

    NASA Astrophysics Data System (ADS)

    McDonald, D. C.; Mauney, D. T.; Leicht, D.; Marks, J. H.; Tan, J. A.; Kuo, J.-L.; Duncan, M. A.

    2016-12-01

    Ion-molecule complexes of the form H+Arn are produced in pulsed-discharge supersonic expansions containing hydrogen and argon. These ions are analyzed and mass-selected in a reflectron spectrometer and studied with infrared laser photodissociation spectroscopy. Infrared spectra for the n = 3-7 complexes are characterized by a series of strong bands in the 900-2200 cm-1 region. Computational studies at the MP2/aug-cc-pVTZ level examine the structures, binding energies, and infrared spectra for these systems. The core ion responsible for the infrared bands is the proton-bound argon dimer, Ar-H+-Ar, which is progressively solvated by the excess argon. Anharmonic vibrational theory is able to reproduce the vibrational structure, identifying it as arising from the asymmetric proton stretch in combination with multiple quanta of the symmetric argon stretch. Successive addition of argon shifts the proton vibration to lower frequencies, as the charge is delocalized over more ligands. The Ar-H+-Ar core ion has a first solvation sphere of five argons.

  14. Behavior of Excited Argon Atoms in Inductively Driven Plasmas

    SciTech Connect

    HEBNER,GREGORY A.; MILLER,PAUL A.

    1999-12-07

    Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s{sub 5} and 1s{sub 4}, in inductively driven plasmas containing argon, chlorine and boron trichloride. The behavior of the two energy levels with plasma conditions was significantly different, probably because the 1s{sub 5} level is metastable and the 1s{sub 4} level is radiatively coupled to the ground state but is radiation trapped. The argon data is compared with a global model to identify the relative importance of processes such as electron collisional mixing and radiation trapping. The trends in the data suggest that both processes play a major role in determining the excited state density. At lower rfpower and pressure, excited state spatial distributions in pure argon were peaked in the center of the discharge, with an approximately Gaussian profile. However, for the highest rfpowers and pressures investigated, the spatial distributions tended to flatten in the center of the discharge while the density at the edge of the discharge was unaffected. The spatially resolved excited state density measurements were combined with previous line integrated measurements in the same discharge geometry to derive spatially resolved, absolute densities of the 1s{sub 5} and 1s{sub 4} argon excited states and gas temperature spatial distributions. Fluorescence lifetime was a strong fi.mction of the rf power, pressure, argon fraction and spatial location. Increasing the power or pressure resulted in a factor of two decrease in the fluorescence lifetime while adding Cl{sub 2} or BCl{sub 3} increased the fluorescence lifetime. Excited state quenching rates are derived from the data. When Cl{sub 2} or BCl{sub 3} was added to the plasma, the maximum argon metastable density depended on the gas and ratio. When chlorine was added to the argon plasma, the spatial density profiles were independent of chlorine fraction. While it is energetically possible for

  15. The Cryogenic Performances of Specific Optical and Electrical Components for a Liquid Argon Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Gong, Datao; Hou, Suen; Liu, Chonghan; Liu, Tiankuan; Su, Da-shung; Teng, Ping-kun; Xiang, Annie C.; Ye, Jingbo; LBNE Collaboration

    In this paper we present a cryogenic performance study of specific optical and electrical components for the Liquid Argon Time Projection Chamber (LArTPC), a potential far site detector technology of the long baseline neutrino experiment (LBNE). We have confirmed that an LVDS driver can drive a 20-meter CAT5E twisted pair up to 1 gigabit per second at liquid nitrogen temperature (77 K). We have verified that a 16:1 serializer Application Specific Integrated Circuit (ASIC), three types of laser diodes, optical fibers and connectors, and field-programming gate arrays (FPGAs) continue to function at 77 K. A variety of commercial resistors and capacitors have been tested at 77 K. All tests we have conducted show that the cold front-end electronics is promising.

  16. Performance of VUV-sensitive MPPC for liquid argon scintillation light

    NASA Astrophysics Data System (ADS)

    Igarashi, T.; Tanaka, M.; Washimi, T.; Yorita, K.

    2016-10-01

    A new multi-pixel photon counter (MPPC) sensitive to vacuum ultra-violet (VUV) light (wavelength λ < 150 nm) has recently been developed and produced by Hamamatsu Photonics K.K. In this study, the basic properties of the new MPPC are measured at the cryogenic facility of the Waseda University using liquid nitrogen. The temperature dependence of the breakdown voltage, capacitance, and dark count rate of the MPPCs are also evaluated. Using an 241Am α-ray source, the absolute photon detection efficiency (PDE) of the liquid argon (LAr) scintillation light (λ=128 nm) for the latest MPPC model is estimated to be 13%. Based on these basic measurements a possible application of the new MPPC to LAr detectors in dark matter search is suggested.

  17. Air quality aerometric data for the city of Cleveland from 1967 to 1970 for sulphur dioxide, suspended particulates, and nitrogen dioxide

    NASA Technical Reports Server (NTRS)

    Neustadter, H. E.; King, R. B.; Fordyce, J. S.; Burr, J. C., Jr.

    1972-01-01

    The NASA Lewis Research Center is assisting the City of Cleveland, Ohio, in its effort to monitor its air pollution. This report describes the Cleveland program of the past 4 years and the supportive Lewis program currently being developed. The data accumulated by Cleveland over the past 4 years are presented together with some preliminary statistical analyses indicating in a semiquantitive manner the degree of air pollution existing within the boundaries of Cleveland.

  18. Effects of high pressure nitrogen on the thermal stability of SiC fibers

    NASA Technical Reports Server (NTRS)

    Jaskowiak, Martha H.

    1991-01-01

    Polymer-derived SiC fibers were exposed to nitrogen gas pressures of 7 and 50 atm at temperatures up to 1800 C. The fiber weight loss, chemical composition, and tensile strength were then measured at room temperature in order to understand the effects of nitrogen exposure on fiber stability. High pressure nitrogen treatments limited weight loss to 3 percent or less for temperatures up to 1800 C. The bulk Si-C-O chemical composition of the fiber remained relatively constant up to 1800 C with only a slight increase in nitrogen content after treatment at 50 atm; however, fiber strength retention was significantly improved. To further understand the effects of the nitrogen atmosphere on the fiber stability, the results of previous high pressure argon treatments were compared to those of the high pressure nitrogen treatments. High pressure inert gas can temporarily maintain fiber strength by physically inhibiting the evolution of gaseous species which result from internal reactions. In addition to this physical effect, it would appear that high pressure nitrogen further improved fiber temperature capability by chemically reacting with the fiber surface, thereby reducing the rate of gas evolution. Subsequent low pressure argon treatments following the initial nitrogen treatments resulted in stronger fibers than after argon treatment alone, further supporting the chemical reaction mechanism and its beneficial effects on fiber strength.

  19. Assessment of the roles of various inactivation agents in an argon-based direct current atmospheric pressure cold plasma jet

    SciTech Connect

    Zhang Qian; Wang Ruixue; Sun Peng; Feng Hongqing; Liang Yongdong; Zhu Weidong; Becker, Kurt H.; Zhang Jue; Fang Jing

    2012-06-15

    Three types of gases, pure argon (99.999%), argon with 2% oxygen, and argon with 2% oxygen and 10% nitrogen were used as operating gases of a direct current atmospheric pressure cold plasma jet to inactivate Staphylococcus aureus (S. aureus) suspended in a liquid. The inactivation efficacies for the plasma jets operating in the three gases decrease from Ar/O{sub 2}(2%) to Ar/O{sub 2}(2%)/N{sub 2}(10%) to pure Ar. Optical emission spectroscopy, electron spin resonance spectroscopy, high performance liquid chromatography, and atomic absorption spectrophotometry were employed to identify and monitor the reactive species in the plasma-liquid system for the three operating gases and revealed the presence of O, {sup 1}O{sub 2}, OH, NO, H{sub 2}O{sub 2}, O{sub 3}, and NO{sub 3}{sup -}/NO{sub 2}{sup -} as well as Cu{sup +}/Cu{sup 2+}. The S. aureus inactivation results indicate that atomic oxygen (O) is the key inactivation agent, while other species play a lesser role in the inactivation progress studied here.

  20. The Global Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Galloway, J. N.

    2003-12-01

    transfer depended on the reactivity of the emitted material. At the lower extreme of reactivity are the noble gases, neon and argon. Most neon and argon emitted during the degassing of the newly formed Earth is still in the atmosphere, and essentially none has been transferred to the hydrosphere or crust. At the other extreme are carbon and sulfur. Over 99% of the carbon and sulfur emitted during degassing are no longer in the atmosphere, but reside in the hydrosphere or the crust. Nitrogen is intermediate. Of the ˜6×106 TgN in the atmosphere, hydrosphere, and crust, ˜2/3 is in the atmosphere as N2 with most of the remainder in the crust. The atmosphere is a large nitrogen reservoir primarily, because the triple bond of the N2 molecule requires a significant amount of energy to break. In the early atmosphere, the only sources of such energy were solar radiation and electrical discharges.At this point we had an earth with mostly N2 and devoid of life. How did we get to an earth with mostly N2 and teeming with life? First, N2 had to be converted into reactive N (Nr). (The term reactive nitrogen (Nr) includes all biologically active, photochemically reactive, and radiatively active nitrogen compounds in the atmosphere and biosphere of the Earth. Thus, Nr includes inorganic reduced forms of nitrogen (e.g., NH3 and NH4+), inorganic oxidized forms (e.g., NOx, HNO3, N2O, and NO3-), and organic compounds (e.g., urea, amines, and proteins).) The early atmosphere was reducing and had limited NH3. However, NH3 was a necessary ingredient in forming early organic matter. One possibility for NH3 generation was the cycling of seawater through volcanics (Holland, 1984). Under such a process, NH3 could then be released to the atmosphere where, when combined with CH4, H2, H2O, and electrical energy, organic molecules including amino acids could be formed (Miller, 1953). In essence, electrical discharges and UV radiation can convert mixtures of reduced gases into mixtures of organic

  1. SHAD-Nisat: A Composite Study of Shallow Saturation Diving Incorporating Long Duration Air Saturation with Excursions, Deep Nitrox Saturation, and Switch from Nitrogen to Helium

    DTIC Science & Technology

    1982-08-01

    which is targeted to the gram negatives). Debris built up in both canals necessitating wire loop removal. Ear powder containing a sulfa drug and...restriction in the A-V valve. The PR and QRS intervals are indicators of changes in ionic balance or drugs . A look at Table IV-1 shows no remarkable...and is has been seen in experiments using nitrous oxide to mimic nitrogen narcosis (Hamilton, 1973). It is caused also by other "narcotic" drugs

  2. 138. LIQUID NITROGEN INSTRUMENT PANEL ON EAST WALL OF LIQUID ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    138. LIQUID NITROGEN INSTRUMENT PANEL ON EAST WALL OF LIQUID NITROGEN CONTROL ROOM (115), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  3. 74. LIQUID NITROGEN TANK, REGULATOR VALVES, AND PRESSURE GAUGES FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    74. LIQUID NITROGEN TANK, REGULATOR VALVES, AND PRESSURE GAUGES FOR LIQUID NITROGEN PUMPING STATION - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  4. Influence of Thermal Annealings in Argon on the Structural and Thermochromic Properties of MoO3 Thin Films

    NASA Astrophysics Data System (ADS)

    Arvizu, M. A.; Morales-Luna, M.; Pérez-González, M.; Campos-Gonzalez, E.; Zelaya-Angel, O.; Tomás, S. A.

    2017-04-01

    The effect of thermal annealing in an inert atmosphere (argon) on the structural and thermochromic properties of MoO3 thin films was investigated. MoO3 thin films were deposited by thermal evaporation in vacuum of MoO3 powders. X-ray diffraction patterns of the films showed the presence of the monoclinic Magneli phase Mo9O_{26} for annealing temperatures above 250°C. Absorbance spectra of the films annealed in argon indicated that their thermochromic response increases with the annealing temperature in the analyzed range (23°C -300°C), a result opposite to the case of thermal annealings in air, for which case the thermochromic response shows a maximum value around 200°C -225°C and decreases for higher temperatures. These results are explained in terms of a higher density of oxygen vacancies formed upon thermal treatments in inert atmospheres.

  5. Argon Spill Trough Bellows - Leak Test

    SciTech Connect

    Jaques, A.; /Fermilab

    1990-04-30

    The four argon spill trough bellows were leak tested with helium during the week of March 12, 1990. Three passed without incident, but the fourth was found to have a leak in the weld at one of the ring/clamps. The hole was approximately 1/32-inch in diameter (a likely result of a welding burn through) and located on an inflexible portion of the bellows, the ring/clamp. Frank Juravic, who conducted the tests, suggested using grey structural epoxy to plug the leak. The epoxy is metallic with some inherent flexibility. The epoxy was applied and the bellows retested in the same manner as before. The repair was a success as the bellows proved to be leaktight. The bellows were then put in their original shipping crates and placed in storage at Lab C. Included in this report is the manufacturer's spec sheets on the bellows, a copy of the Quality Control Report form and a sketch of the test setup with an explanation of the procedure. On the bellows data sheet entitled 'Analysis of Stress in Bellows', the analysis output is obtained through a theoretical bellows program that uses quadratic equations to approximate characteristic curves for such data as axial, lateral and angular movement and spring rates. The program is best suited for bellows with a wall thickness of at least 0.015-inch and an operating pressure significantly above atmospheric. Thus EJS Inc. warned that the output data would not be very accurate in some instances. The data given on the EJS Inc. sketch sheet should be taken as accurate, though, for it was taken from the actual bellows delivered. The 72-inch length includes the 64.64-inch of bellows section, the (3) 1/2-inch ring/clamps and the (2) 1-1/2-inch end bands. The remainder of the discrepancy is accounted for by a 2.75-inch factory elongation of the bellows from the original free length. The 40-inch compression capability includes the 2.75-inch of factory elongation, the program determined 31.9-inch of compression from free length and 5.35-inch of

  6. The Molecular Pathway of Argon-Mediated Neuroprotection

    PubMed Central

    Ulbrich, Felix; Goebel, Ulrich

    2016-01-01

    The noble gas argon has attracted increasing attention in recent years, especially because of its neuroprotective properties. In a variety of models, ranging from oxygen-glucose deprivation in cell culture to complex models of mid-cerebral artery occlusion, subarachnoid hemorrhage or retinal ischemia-reperfusion injury in animals, argon administration after individual injury demonstrated favorable effects, particularly increased cell survival and even improved neuronal function. As an inert molecule, argon did not show signs of adverse effects in the in vitro and in vivo model used, while being comparably cheap and easy to apply. However, the molecular mechanism by which argon is able to exert its protective and beneficial characteristics remains unclear. Although there are many pieces missing to complete the signaling pathway throughout the cell, it is the aim of this review to summarize the known parts of the molecular pathways and to combine them to provide a clear insight into the cellular pathway, starting with the receptors that may be involved in mediating argons effects and ending with the translational response. PMID:27809248

  7. The Molecular Pathway of Argon-Mediated Neuroprotection.

    PubMed

    Ulbrich, Felix; Goebel, Ulrich

    2016-10-31

    The noble gas argon has attracted increasing attention in recent years, especially because of its neuroprotective properties. In a variety of models, ranging from oxygen-glucose deprivation in cell culture to complex models of mid-cerebral artery occlusion, subarachnoid hemorrhage or retinal ischemia-reperfusion injury in animals, argon administration after individual injury demonstrated favorable effects, particularly increased cell survival and even improved neuronal function. As an inert molecule, argon did not show signs of adverse effects in the in vitro and in vivo model used, while being comparably cheap and easy to apply. However, the molecular mechanism by which argon is able to exert its protective and beneficial characteristics remains unclear. Although there are many pieces missing to complete the signaling pathway throughout the cell, it is the aim of this review to summarize the known parts of the molecular pathways and to combine them to provide a clear insight into the cellular pathway, starting with the receptors that may be involved in mediating argons effects and ending with the translational response.

  8. Measured density of copper atoms in the ground and metastable states in argon magnetron discharge correlated with the deposition rate

    NASA Astrophysics Data System (ADS)

    Naghshara, H.; Sobhanian, S.; Khorram, S.; Sadeghi, N.

    2011-01-01

    In a dc-magnetron discharge with argon feed gas, densities of copper atoms in the ground state Cu(2S1/2) and metastable state Cu*(2D5/2) were measured by the resonance absorption technique, using a commercial hollow cathode lamp as light source. The operating conditions were 0.3-14 µbar argon pressure and 10-200 W magnetron discharge power. The deposition rate of copper in a substrate positioned at 18 cm from the target was also measured with a quartz microbalance. The gas temperature, in the range 300-380 K, was deduced from the emission spectral profile of N2(C 3Πu - B 3Πg) 0-0 band at 337 nm when trace of nitrogen was added to the argon feed gas. The isotope-shifts and hyperfine structures of electronic states of Cu have been taken into account to deduce the emission and absorption line profiles, and hence for the determination of atoms' densities from the measured absorption rates. To prevent error in the evaluation of Cu density, attributed to the line profile distortion by auto-absorption inside the lamp, the lamp current was limited to 5 mA. Density of Cu(2S1/2) atoms and deposition rate both increased with the enhanced magnetron discharge power. But at fixed power, the copper density augmented with argon pressure whereas the deposition rate followed the opposite trend. Whatever the gas pressure, the density of Cu*(2D5/2) metastable atoms remained below the detection limit of 1 × 1010 cm-3 for magnetron discharge powers below 50 W and hence increased much more rapidly than the density of Cu(2S1/2) atoms, over passing this later at some discharge power, whose value decreases with increasing argon pressure. This behaviour is believed to result from the enhancement of plasma density with increasing discharge power and argon pressure, which would increase the excitation rate of copper into metastable states. At fixed pressure, the deposition rate followed the same trend as the total density of copper atoms in the ground and metastable states. Two important

  9. Argon-40: excess in submarine pillow basalts from kilauea volcano, hawaii.

    PubMed

    Dalrymple, G B; Moore, J G

    1968-09-13

    Submarine pillow basalts from Kilauea Volcano contain excess radiogenic argon-40 and give anomalously high potassium-argon ages. Glassy rims of pillows show a systematic increase in radiogenic argon-40 with depth, and a pillow from a depth of 2590 meters shows a decrease in radiogenic argon40 inward from the pillow rim. The data indicate that the amount of excess radiogenic argon-40 is a direct function of both hydrostatic pressure and rate of cooling, and that many submarine basalts are not suitable for potassium-argon dating.

  10. Early Clinical Experience With Argon Ion Laser Endarterectomy

    NASA Astrophysics Data System (ADS)

    Eugene, John; Baribeau, Yvon; Ott, Richard A.; McColgan, Stephen J.; Berns, Michael W.

    1989-09-01

    This report describes our progress in the development of argon ion laser endarterectomy for arteriosclerotic cardiovascular disease. Nine patients underwent 10 vascular reconstructions for claudication (6), rest pain (1), and gangrene (2). There was 1 aortoiliac endarterectomy, 6 superficial femoral artery endarterectomies, 1 profunda femoris endarterectomy and 2 popliteal endarterectomies. The reconstructions were 6 cm to 60 cm in length. The operations were performed using low power argon ion laser radiation, 1.0 W. All patients experienced symptomatic relief and had palpable pulses postoperatively. There were no perforations and there were no injuries to surrounding tissues from laser radiation. Surgical complications occurred and these were technical problems that should be eliminated from the operation with further developments. The early clinical results show that laser endarterectomy can be performed for peripheral vascular reconstruction using low power argon ion laser radiation.

  11. The DarkSide-50 liquid argon dark matter search

    NASA Astrophysics Data System (ADS)

    Johnson, Tessa; DarkSide-50 Collaboration

    2017-01-01

    The DarkSide-50 experiment uses three nested detectors to directly search for WIMP dark matter, with the innermost detector a time projection chamber filled with a target of liquid argon (LAr). The unique difference in pulse shape between electron recoils and nuclear recoils in LAr allows for exceptional discrimination of beta and gamma backgrounds. Event discrimination due to pulse shape coupled with the neutron discrimination power of the outer detectors is used to create a background-free environment for the DarkSide-50 WIMP search. Atmospheric argon, including the radioactive 39Ar isotope, was first used to search for WIMPs in a 50-day campaign, and later a search with 70.9 days of livetime was performed with argon extracted from underground wells, reducing the 39Ar isotope by a factor of 1 . 4 ×103 . The status of the experiment will be discussed.

  12. Equation of state of partially ionized argon plasma

    SciTech Connect

    Chen, Q. F.; Zheng, J.; Gu, Y. J.; Chen, Y. L.; Cai, L. C.

    2011-11-15

    The ionization degree, Hugoniots, and equation of state of partially ionized argon plasma were calculated by using self-consistent fluid variational theory for temperature of 6-50 kK and density of 0.05-4.0 g/cm{sup 3}. The corrections of lowering of ionization energy of fluid argon caused by the interactions among all particles of Ar, Ar{sup +}, Ar{sup 2+}, and e have been taken into consideration in terms of the correlation contributions to the chemical potential which is determined self-consistently by the free energy function. The initial density effects of gas argon under shock compression have been discussed. Comparison is performed with available shock-wave experiments and other theoretical calculations.

  13. Summary of potassium/argon dating, 1981. Topical report

    SciTech Connect

    Evans, S.H. Jr.; Brown, F.H.

    1981-09-01

    The analytical results for the last fiscal year effort in potassium/argon dating in support of US Department of Energy programs are summarized. Nearly 100 new dates have been generated. Recalibration of the argon extraction tables resulted in refinement of values for tracer ratios and depletion constants for our two extraction lines. Tracer ratios are ({sup 36}Ar/{sup 38}Ar){sub T} = 0.0308 and 0.0000449; ({sup 40}Ar/{sup 38}Ar){sub T} = 0.0501 and 0.0014 for extraction tables 1 and 2, respectively. Tracer depletion constants are -0.0002250 and -0.0005501 for tables 1 and 2, respectively. Initial values for the argon tracer pipettes are 3.2522 x 10{sup -11} moles and 3.9329 x 10{sup -11} moles for tables 1 and 2, respectively.

  14. On the electric breakdown in liquid argon at centimeter scale

    NASA Astrophysics Data System (ADS)

    Auger, M.; Blatter, A.; Ereditato, A.; Goeldi, D.; Janos, S.; Kreslo, I.; Luethi, M.; von Rohr, C. Rudolf; Strauss, T.; Weber, M. S.

    2016-03-01

    We present a study on the dependence of electric breakdown discharge properties on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  15. New statistical boundary conditions for argon-tungsten interactions.

    PubMed

    Ozhgibesov, M S; Leu, T S; Cheng, C H; Utkin, A V

    2012-09-01

    In this study, scattering processes of argon beam impinging on tungsten surface are investigated numerically by applying molecular dynamics (MD) simulations. Energy transfer, momentum change, and scattering processes of argon gas atoms from W(110) surface are discussed. A new model of argon-tungsten (Ar-W) interaction is proposed. Based on the new proposed model, one can simplify the boundary conditions of this problem. The new boundary conditions are proved to be in line with previous experimental and theoretical results. This paper demonstrates how to proceed normalization and further conversion of the MD simulation results into boundary conditions. Application of the new proposed boundary conditions for Ar-W interactions provides a significant speedup of computations.

  16. Developing Detectors for Scintillation Light in Liquid Argon for DUNE

    SciTech Connect

    Howard, Bruce

    2016-12-22

    The Deep Underground Neutrino experiment will conduct a broad program of physics research by studying a beam of neutrinos from Fermilab, atmospheric neutrinos, neutrinos from potential supernovae, and potential nucleon decay events. In pursuit of these studies, the experiment will deploy four 10kt fiducial mass liquid argon time projection chambers underground in Lead, South Dakota. Liquid argon time projection chambers allow high-resolution tracking and energy measurements. A precise timing signal is needed to provide the necessary time stamp to localize events in the drift direction. As liquid argon is a natural scintillator, a photon detection system will be deployed to provide such a signal, especially for non-beam events. In the baseline design for the single-phase time projection chamber, the detectors are contained within the anode plane assemblies. The design of two prototypes utilizing wavelength shifters and light guides are presented, and aspects of the research and development program are discussed.

  17. Microwave Spectrum and Molecular Structure of the ARGON-(E)-1-CHLORO-1,2-DIFLUOROETHYLENE Complex

    NASA Astrophysics Data System (ADS)

    Marshall, Mark D.; Leung, Helen O.; Tandon, Hannah K.; Messinger, Joseph P.; Mlaver, Eli

    2014-06-01

    Previous studies of argon complexes with fluoroethylenes have revealed a preference for a geometry that maximizes the contact of the argon atom with heavy atoms on the fluoroethylene. We have observed a continuation of this trend when one of the fluorine atoms is replaced by chlorine. The argon-(E)-1-chloro-1,2-difluoroethylene complex provides two competing heavy atom cavities, FCCF and FCCl, and the opportunity to examine whether the number of heavy atoms or the associated increase in polarizability is determinative of structure. The 5.6 -- 18.1 GHz chirped-pulse Fourier transform microwave spectrum of this species provides initial assignments and predictions for spectra obtained in a more sensitive and higher precision Balle-Flygare instrument. Transitions for both the 35Cl and 37Cl isotopologues are observed and analyzed to provide geometric parameters for this non-planar complex. The spectrum is consistent with the argon atom located in the FCCl cavity, and the structure agrees well with ab initio predictions. Comparisons are made with Ar-1-chloro-1-fluoroethylene, (Z)-1-chloro-2-fluoroethylene, and Ar-vinyl chloride. Z. Kisiel, P.W. Fowler, and A.C. Legon, J. Chem. Phys. 95, 2283 (1991).

  18. Liquid nitrogen energy storage unit

    NASA Astrophysics Data System (ADS)

    Afonso, J.; Catarino, I.; Patrício, R.; Rocaboy, A.; Linder, M.; Bonfait, G.

    2011-11-01

    An energy storage unit is a device able to store thermal energy with a limited temperature drift. After precooling such unit with a cryocooler it can be used as a temporary cold source if the cryocooler is stopped or as a thermal buffer to attenuate temperature fluctuations due to heat bursts. In this article, after a brief study of the possible solutions for such devices, we show that a low temperature cell filled with liquid nitrogen and coupled to a room temperature expansion volume offers the most compact and light solution in the temperature range 60-80 K. For instance, a low temperature cell as small as 23 cm 3 allows the storage of 3.7 kJ between 76 K and 81 K. Experimental results were obtained varying the expansion volume size, the filling pressure and the temperature range. These results agree with our simple model based on thermodynamical properties of nitrogen. A cell filled with porous material was tested to confine the liquid in the cell independently of the gravity. This material enhances the thermal exchange for high liquid filling ratio whereas below ≈16% a solution must be found to improve the heat exchange coefficient between the fluid and the cell walls. Our calculations are extended to the 80-120 K temperature range for nitrogen and argon in order to clarify the various parameters to take into account for an energy storage unit dimensioning.

  19. AIR POLLUTION CONTROL TECHNOLOGIES

    EPA Science Inventory

    This is a chapter for John Wiley & Son's Mechanical Engineers' Handbook, and covers issues involving air pollution control. Various technologies for controlling sulfur oxides is considered including fuel desulfurization. It also considers control of nitrogen oxides including post...

  20. State Air Quality Standards.

    ERIC Educational Resources Information Center

    Pollution Engineering, 1978

    1978-01-01

    This article presents in tabular form the air quality standards for sulfur dioxide, carbon monoxide, nitrogen dioxide, photochemicals, non-methane hydrocarbons and particulates for each of the 50 states and the District of Columbia. (CS)

  1. Innovative Clean Coal Technology (ICCT): 500 MW demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NO{sub x}) emissions from coal-fired boilers. Phase 2, Overfire air tests

    SciTech Connect

    Smith, L.L.; Hooper, M.P.

    1992-07-13

    This Phase 2 Test Report summarizes the testing activities and results for the second testing phase of an Innovative Clean Coal Technology (ICCT) demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NO{sub x}) emissions from coal-fired boilers. The second phase demonstrates the Advanced Overfire Air (AOFA) retrofit with existing Foster Wheeler (FWEC) burners. The project is being conducted at Georgia Power Company`s Plant Hammond Unit 4 located near Rome, Georgia. The primary goal of this project is the characterization of the low NO{sub x} combustion equipment through the collection and analysis of long-term emissions data supported by short-term characterization data. Ultimately a fifty percent NO{sub x} reduction target using combinations of combustion modifications has been established for this project.

  2. Properties of radio-frequency heated argon confined uranium plasmas

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Pure uranium hexafluoride (UF6) was injected into an argon confined, steady state, rf-heated plasma within a fused silica peripheral wall test chamber. Exploratory tests conducted using an 80 kW rf facility and different test chamber flow configurations permitted selection of the configuration demonstrating the best confinement characteristics and minimum uranium compound wall coating. The overall test results demonstrated applicable flow schemes and associated diagnostic techniques were developed for the fluid mechanical confinement and characterization of uranium within an rf plasma discharge when pure UF6 is injected for long test times into an argon-confined, high-temperature, high-pressure, rf-heated plasma.

  3. Filamentation of ultrashort laser pulses of different wavelengths in argon

    NASA Astrophysics Data System (ADS)

    Qi, Xiexing; Lin, Wenbin

    2017-02-01

    We investigate the filaments formed by the ultrashort laser pulses with different wavelengths of 400 nm, 586 nm and 800 nm propagating in argon. Numerical results show that, when the input power or the ratio of the input power to the critical power is given, the pulse with 400 nm wavelength has the largest on-axis intensity, as well as the narrowest filament and the most stable beam radius. These results indicate that the pulse with shorter wavelength is more suitable for the long-range propagation in argon.

  4. Counterflow diffusion flames of hydrogen, and hydrogen plus methane, ethylene, propane, and silane vs. air - Strain rates at extinction

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Northam, G. Burton; Wilson, L. G.

    1991-01-01

    Five coaxial tubular opposed jet burners (OJBs) with tube diameter D(T) of 1.8-10 mm and 5 mm conical nozzles were used to form dish-shaped counterflow diffusion flames centered by opposing laminar jets of nitrogen and hydrocarbon-diluted H2 versus air in an argon-purged chamber at 1 atm. Area-averaged air jet velocities at blowoff of the central flame, U(air), characterized extinction of the airside flame as functions of input H2 concentration on the fuelside. A master plot of extensive U(air) data at blowoff versus D(T) shows that U(air) varies linearly with D(T). This and other data sets are used to find that nozzle OJB results for U(air)/diameter average 4.24 + or - 0.28 times larger than tubular OJB results for the same fuel compositions. Critical radial velocity gradients consistent with one-dimensional stagnation point boundary theory and with plug flow inputs are estimated. The results compare favorably with published numerical results based only on potential flow.

  5. Measurements of argon broadened Lorentz width and pressure-induced line shift coefficients in the nu4 band of (C-12)H4

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Smith, Mary Ann H.; Devi, V. Malathy; Benner, D. Chris

    1989-01-01

    Room temperature argon broadened halfwidth and pressure-induced line shift coefficients have been determined for 118 transitions in the nu4 band of (C-12)H4 from analysis of high resolution laboratory absorption spectra recorded with the McMath Fourier transform spectrometer operated on Kitt Peak by the National Solar Observatory. Transitions up to J-double-prime = 12 have been measured using a nonlinear least-squares spectral fitting procedure. The variation of the measured halfwidth coefficients with symmetry type and rotational quantum number is very similar to that measured previously for N2 and air broadening, but the absolute values of the argon broadening coefficients are all smaller. On average, the ratio of the argon broadened halfwidth coefficient to the corresponding N2 broadened halfwidth coefficient is 0.877 + or - 0.017 (2 Sigma). More than 95 percent of the pressure-induced shifts are negative with values ranging from -0.0081 to +0.0055/cm atm. The pressure shifts in argon are nearly equal to corresponding values measured previously in N2 and air.

  6. Development of a nitrogen generation system

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Marshall, R. D.; Powell, J. D., III; Schubert, F. H.

    1980-01-01

    An eight-stage nitrogen generation module was developed. The design integrated a hydrazine catalytic dissociator, three ammonia dissociation stages and four palladium/silver hydrogen separator stages. Alternating ammonia dissociation and hydrogen separation stages are used to remove hydrogen and ammonia formed in the dissociation of hydrazine which results in negligible ammonia and hydrogen concentrations in the product nitrogen stream. An engineering breadboard nitrogen supply subsystem was also developed. It was developed as an integratable subsystem for a central spacecraft air revitalization system. The subsystem consists of the hydrazine storage and feed mechanism, the nitrogen generation module, the peripheral mechanical and electrical components required to control and monitor subsystem performance, and the instrumentation required to interface with other subsystems of an air revitalization system. The breadboard nitrogen supply subsystem was integrated and tested with a one-person capacity experimental air revitalization system. The integration, checkout and testing was successfully accomplished.

  7. 49 CFR 173.316 - Cryogenic liquids in cylinders.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... °F.). (2) The cryogenic liquids of argon, nitrogen, oxygen, helium and neon must be loaded and... pressure psig) Maximum permitted filling density (percent by weight) Air Argon Nitrogen Oxygen Helium...

  8. 49 CFR 173.316 - Cryogenic liquids in cylinders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... °F.). (2) The cryogenic liquids of argon, nitrogen, oxygen, helium and neon must be loaded and... pressure psig) Maximum permitted filling density (percent by weight) Air Argon Nitrogen Oxygen Helium...

  9. 49 CFR 173.316 - Cryogenic liquids in cylinders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... °F.). (2) The cryogenic liquids of argon, nitrogen, oxygen, helium and neon must be loaded and... pressure psig) Maximum permitted filling density (percent by weight) Air Argon Nitrogen Oxygen Helium...

  10. Reactive Nitrogen in Atmospheric Emission Inventories

    EPA Science Inventory

    Excess reactive Nitrogen (NT) has become one of the most pressing environmental problems leading to air pollution, acidification and eutrophication of ecosystems, biodiversity impacts, leaching of nitrates into groundwater and global warming. This paper investigates how current i...

  11. Cryogenic Tests of the ATLAS Liquid Argon Calorimeter

    NASA Astrophysics Data System (ADS)

    Bremer, J.; Chalifour, M.; Fabre, C.; Gonidec, A.; Passardi, G.

    2006-04-01

    The ATLAS liquid argon calorimeter consists of the barrel and two end-cap detectors housed in three independent cryostats filled with a total volume of 78 m3 of liquid argon. During cool-down the temperature differences in the composite structure of the detectors must be kept within strict limits to avoid excessive mechanical stresses and relative displacements. During normal operation the formation of gas bubbles, which are detrimental to the functioning of the detector, must be prevented and temperature gradients of less than 0.7 K across the argon bath are mandatory due to the temperature dependence of the energy measurements. Between April 2004 and May 2005 the barrel (120 t) and one end-cap (219 t) underwent qualification tests at the operating temperature of 87.3 K using a dedicated test facility at ground level. These tests provided a validation of the cooling methods to be adopted in the final underground configuration. In total 6.9 GJ and 15.7 GJ were extracted from the calorimeters and a temperature uniformity of the argon bath of less than 0.4 K was achieved.

  12. Pion Charge Exchange Cross Section on Liquid Argon

    NASA Astrophysics Data System (ADS)

    Nelson, Kevin; LArIAT (FNAL T-1034) Collaboration

    2017-01-01

    The observation of neutrino oscillations allows charge parity violation to be probed in the neutrino sector. Detectors with high calorimetric energy resolution and high spatial resolution will provide precise measurements of neutrino oscillations. By measuring small π+/- cross sections for individual interaction channels, specifically charge exchange, we will make a measurement in the first of its kind on liquid Argon and demonstrate the physics capabilities of a relatively new detector technology: the Liquid Argon Time Projection Chamber (LAr TPC). This analysis will report on the thin slab cross section measurement technique and the Monte Carlo cross section measurements in the energy range of 0.2 - 1.0 GeV. This analysis is the first iteration in classifying charge exchange events from a sample of incident pions, and it aims to identify events in which a π0 was produced without any charged pions leaving the interaction vertex. We will also report on the methodology and efficiency of this algorithm in identifying particles and their interactions in liquid argon. This analysis will inform a future measurement of the π+/- charge exchange cross section on liquid argon. This work was supported in part by the National Science Foundation under Grant No. PHY-1359364.

  13. Experimental and numerical study of high intensity argon cluster beams

    SciTech Connect

    Korobeishchikov, N. G.; Kalyada, V. V.; Shmakov, A. A.; Zarvin, A. E.; Skovorodko, P. A.

    2014-12-09

    Experimental and numerical investigations of expansion of argon with homogeneous condensation in supersonic conical nozzle and in free jet behind it were carried out. Optimal parameters (stagnation pressure, nozzle-skimmer distance) for the formation of cluster beam with maximum intensity were determined. Two available models for nonequilibrium nucleation were tested. The numerical results are in satisfactory agreement with the measured data.

  14. Thermophysical properties of multi-shock compressed dense argon

    SciTech Connect

    Chen, Q. F. Zheng, J.; Gu, Y. J.; Chen, Y. L.; Cai, L. C.; Shen, Z. J.

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models.

  15. Supersonic Argon Flow In An Arc Plasma Source

    SciTech Connect

    Izrar, B.; Dudeck, M.; Andre, P.; Elchinger, M. F.; Aubreton, J.

    2006-01-15

    The plasma properties inside a D.C. arc-jet operating with argon is analysed by means of a continuum description taking into account non equilibrium ionization processes and dissipative effects. The relaxation of the different physical processes inside the nozzle and the evolution of the Mach number are aanalysed.

  16. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    NASA Astrophysics Data System (ADS)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  17. Differences in creep performance of a HIPed silicon nitride in ambient air and inert environments

    SciTech Connect

    Wereszczak, A.A.; Kirkland, T.P.; Ferber, M.K.

    1995-04-01

    High temperature tensile creep studies of a commercially available hot isostatically pressed (HIPed) silicon nitride were conducted in ambient air and argon environments. The creep performance of this HIPed silicon nitride was found to be different in these environments. The material crept faster (and had a consequential shorter lifetime) in argon than in ambient air at 1370{degrees}C at tensile stresses between 110-140 MPa. The stress dependence of the minimum creep rate was found to be {approx} 6 in argon and {approx} 3.5 in air, while the minimum creep rates were almost an order of magnitude faster in argon than in air at equivalent tensile stresses. Differences in the creep performance are explained with reference to the presence or absence of oxygen in the two environments.

  18. Quantitative analysis of oxide materials by laser-induced breakdown spectroscopy with argon as an internal standard

    NASA Astrophysics Data System (ADS)

    Lasheras, R. J.; Bello-Gálvez, C.; Anzano, J. M.

    2013-04-01

    Laser-induced breakdown spectroscopy (LIBS) is demonstrated as a quantitative technique for geochemical analysis. This study demonstrates the applicability of LIBS to multielemental analysis of minerals using argon as an internal standard. Laser-induced breakdown spectroscopy has been applied to measure elements in oxide form. In the present study, the contents of several oxides, such as Fe2O3, CaO and MgO, in geological samples from the Tierga Mine (Zaragoza, Spain) were analyzed by LIBS. An argon environment was used to eliminate interference from air at atmospheric pressure. Furthermore, argon was used as an internal standard. The result was enhanced signal and enhanced linearity of the calibration curves. The Fe2O3, CaO and MgO concentrations determined by LIBS were compared with the results obtained using another analytical technique, inductively coupled plasma optical emission spectrometry (ICP-OES). The concentrations found using LIBS were in good agreement with the values obtained by ICP-OES.

  19. Pulsed microwave-driven argon plasma jet with distinctive plume patterns resonantly excited by surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Chen, Zhao-Quan; Yin, Zhi-Xiang; Xia, Guang-Qing; Hong, Ling-Li; Hu, Ye-Lin; Liu, Ming-Hai; Hu, Xi-Wei; A. Kudryavtsev, A.

    2015-02-01

    Atmospheric lower-power pulsed microwave argon cold plasma jets are obtained by using coaxial transmission line resonators in ambient air. The plasma jet plumes are generated at the end of a metal wire placed in the middle of the dielectric tubes. The electromagnetic model analyses and simulation results suggest that the discharges are excited resonantly by the enhanced electric field of surface plasmon polaritons. Moreover, for conquering the defect of atmospheric argon filamentation discharges excited by 2.45-GHz of continued microwave, the distinctive patterns of the plasma jet plumes can be maintained by applying different gas flow rates of argon gas, frequencies of pulsed modulator, duty cycles of pulsed microwave, peak values of input microwave power, and even by using different materials of dielectric tubes. In addition, the emission spectrum, the plume temperature, and other plasma parameters are measured, which shows that the proposed pulsed microwave plasma jets can be adjusted for plasma biomedical applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 11105002 and 61170172), the Natural Science Foundation of Anhui Province, China (Grant Nos. 1408085QA16 and 1408085ME101), the China Postdoctoral Science Foundation (Grant No. 2014M551788), and the Open-end Fund of State Key Laboratory of Advanced Electromagnetic Engineering and Technology (HUST), China (Grant No. GZ1301).

  20. Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

    NASA Astrophysics Data System (ADS)

    M, N. Stankov; A, P. Jovanović; V, Lj Marković; S, N. Stamenković

    2016-01-01

    The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approximate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by ions, produced by atomic-to-molecular conversion of Ar+ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as conversion maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional (1D) model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional (2D) model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes. Project supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. ON171025).

  1. Attachment cooling of electrons in oxygen-argon and SF6-argon mixtures

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia; Kim, Sung Jin; Park, Gan Young; Lee, Jae Koo

    2004-09-01

    In e-beam sustained plasma different electron temperature can be obtained. Thus, in plasma of capacitive RF discharges in inert gases typical electron temperature is of the order of 2-3 eV. At certain conditions, in plasma of electronegative gases electron temperature can approach ion/neutral temperature. We consider e-beam sustained plasma of electronegative gases and their mixtures with argon where the main mechanism of plasma neutralization is connected with electron-molecule attachment. In such plasma, due to retardation of fast electrons of e-beam secondary electrons are created which loose their energy due to attachment. It is shown, that at certain conditions (in dependence of the e-beam intensity and spectrum of secondary electrons) electron temperature can obtain the values comparable or even less than temperature of neutral component. The effect can be explained by the increase of attachment rate coefficient with the increase of electron temperature (mean electron energy). Such a dependence leads to attachment of the fastest plasma electrons and selective loss of electrons whose energy exceeds the mean electron energy and, as a result, to effective electron cooling. The theoretical and numerical analysis of the problem has been conducted. The numerical results obtained using ELENDIF code are compared with Particle-in-cell/Monte Carlo simulations under similar conditions.

  2. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  3. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  4. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  5. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  6. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  7. Measurement of Mars Atmosphere Argon Density with the APXS on the Opportunity site

    NASA Astrophysics Data System (ADS)

    Economou, T. E.; Citron, R. I.; Pierrehumbert, R. T.

    2008-12-01

    Using the APXS on board the Opportunity rover on MER mission, we were able to measure the argon density variation in the martian atmosphere as a function of seasons. The freezing and melting of the CO2 in the martian atmosphere at the poles creates local atmospheric lows/highs that moves the air mass. The argon, however, never freezes and stays in the air. An enhancement of Ar/CO2 mixing ratio by a factor of six at the martian South pole during the winter has been observed by the GRS onboard the Odyssey orbiter. In order to study this effect from the ground at the Opportunity site on MER mission, we have been making dedicated APXS measurements of the Ar in the atmosphere. In this case, the only real peak in the X-ray spectrum is the Ar line. To a good approximation, the APXS count rate is proportional to the number of argon atoms in the sensing volume, and hence measures the atmospheric density of argon, ρAr. If the atmosphere were perfectly mixed, the argon partial pressure would be constant. If we define the Local Mix- ing Ratio (MRlocal) as equal to the ratio of the local Ar partial pressure to the global average, then the measurement PAr/T is proportional to the local mixing ratio. The APXS Ar experiment thus gives a direct measurement of the local mixing ratio at the MER landing sites and it is a direct probe of the global circulation between the polar CO2 resource/sink and the equatorial regions. We have found that the Ar amount in the martian atmosphere at the Opportunity landing site is not constant and it is changing with the changing seasons. The change of the Ar in the atmos-phere follows the overall change in the atmospheric pressure but it is not in phase with it. There is a delay of many months between the maximum in Ar/CO2 mixing ratio and the pressure maximum. In addition, we have even seen the asymmetry between the south and north martian poles due to a different degree of CO2 contribution from both poles during the martian year. The actual Ar

  8. The determination of nitrogen dioxide in ambient air with free hanging filters as passive samplers, and a new calibration method using fritted bubblers.

    PubMed

    Heeres, Paul; Setiawan, Rineksa; Krol, Maarten Cornelis; Adema, Eduard Hilbrand

    2009-12-01

    This paper describes two new methods for the determination of NO(2) in the ambient air. The first method consists of free hanging filters with a diameter of 2.5 cm as passive samplers. The filters are impregnated with triethanolamine to bind NO(2). With standard colorimetrical analysis, the amount of NO(2) on the filters is determined. The second method is performed with fritted bubblers filled with Saltzman reagent, where, with a special procedure the absorption efficiencies of the bubblers are determined using ambient air, without the use of standard gases and electronic analytical instruments. The results of the bubblers are used to calibrate the free hanging filters. The two methods were applied simultaneously in the city of Yogyakarta, Indonesia. The methods are inexpensive and very well suited for use in low-budget situations. A characteristic of the free filter is the Sampling Volume, SV. This is the ratio of the amount of NO(2) on the filter and the ambient concentration. With the filter used in this study, the amount of triethanolamine and exposure time, the SV is 0.0166 m(3). The sampling rate (SR) of the filter, 4.6 cm(3)/s, is high. Hourly averaged measurements are performed for 15 hours per day in four busy streets. The measured amounts of NO(2) on the filters varied between 0.57 and 2.02 microg NO(2), at ambient air concentrations of 32 to 141 microg/m(3) NO(2). During the experiments the wind velocity was between 0.2 and 2.0 m/s, the relative humidity between 24 and 83 % and the temperature between 295 K and 311 K. These variations in weather conditions have no influence on the uptake of NO(2).

  9. ATLAS Liquid Argon Endcap Calorimeter R&D for sLHC

    NASA Astrophysics Data System (ADS)

    Schacht, P.

    2010-04-01

    The performance of the ATLAS liquid argon endcap has been studied for luminosities as expected for the operation at sLHC. The increase of integrated luminosity by a factor of ten has serious consequences for the signal reconstruction, radiation hardness requirements and operations of the forward liquid argon calorimeters. The response has been studied with small modules of the type as built for ATLAS in a very high intensity beam at IHEP/Protvino. The highest intensity obtained was well above the level of energy impact expected for ATLAS at sLHC. The signal processing of the ATLAS Hadronic Endcap Calorimeter employs the concept of 'active pads' which keep the detector capacities at the input of the amplifiers small and thereby achieves a fast rise time of the signal. This concept is realized using highly integrated amplifier and summing chips in GaAs technology. With an increase of luminosity by a factor of ten the safety factor for the radiation hardness is essentially eliminated. Therefore new, more radiation hard technologies have been studied: SiGe bipolar, Si CMOS FET and GaAs FET transistors have been irradiated with neutrons up to an integrated fluence of 2.2 × 1016n/cm2. All technologies exceed the limit required for the radiation hardness for the operation at sLHC of 2 × 1015n/cm2. The temperature dependence of the gain has been studied as well. Here the bipolar technologies - in contrast to CMOS - need an adjustment of the operation point when going from room temperature to liquid nitrogen temperature.

  10. Investigating the Mutagenicity of a Cold Argon-Plasma Jet in an HET-MN Model

    PubMed Central

    Bender, Claudia; Benkhai, Hicham; Sckell, Axel; Below, Harald; Stope, Matthias B.; Kramer, Axel

    2016-01-01

    Objective So-called cold physical plasmas for biomedical applications generate reactive oxygen and nitrogen species and the latter can trigger DNA damage at high concentrations. Therefore, the mutagenic risks of a certified atmospheric pressure argon plasma jet (kINPen MED) and its predecessor model (kINPen 09) were assessed. Methods Inner egg membranes of fertilized chicken eggs received a single treatment with either the kINPen 09 (1.5, 2.0, or 2.5 min) or the kINPen MED (3, 4, 5, or 10 min). After three days of incubation, blood smears (panoptic May-Grünwald-Giemsa stain) were performed, and 1000 erythrocytes per egg were evaluated for the presence of polychromatic and normochromic nuclear staining as well as nuclear aberrations and binucleated cells (hen’s egg test for micronuclei induction, HET-MN). At the same time, the embryo mortality was documented. For each experiment, positive controls (cyclophosphamide and methotrexate) and negative controls (NaCl-solution, argon gas) were included. Additionally, the antioxidant potential of the blood plasma was assessed by ascorbic acid oxidation assay after treatment. Results For both plasma sources, there was no evidence of genotoxicity, although at the longest plasma exposure time of 10 min the mortality of the embryos exceeded 40%. The antioxidant potential in the egg’s blood plasma was not significantly reduced immediately (p = 0.32) or 1 h (p = 0.19) post exposure to cold plasma. Conclusion The longest plasma treatment time with the kINPen MED was 5–10 fold above the recommended limit for treatment of chronic wounds in clinics. We did not find mutagenic effects for any plasma treatment time using the either kINPen 09 or kINPen MED. The data provided with the current study seem to confirm the lack of a genotoxic potential suggesting that a veterinary or clinical application of these argon plasma jets does not pose mutagenic risks. PMID:27584003

  11. Preliminary measurements of summer nitric acid and ammonia concentrations in the Lake Tahoe Basin air-shed: implications for dry deposition of atmospheric nitrogen.

    PubMed

    Tarnay, L; Gertler, A W; Blank, R R; Taylor, G E

    2001-01-01

    Over the past 50 years, Lake Tahoe, an alpine lake located in the Sierra Nevada mountains on the border between California and Nevada, has seen a decline in water clarity. With significant urbanization within its borders and major urban areas 130 km upwind of the prevailing synoptic airflow, it is believed the Lake Tahoe Basin is receiving substantial nitrogen (N) input via atmospheric deposition during summer and fall. We present preliminary inferential flux estimates to both lake surface and forest canopy based on empirical measurements of ambient nitric acid (HNO3), ammonia (NH3), and ammonium nitrate (NH4NO3) concentrations, in an effort to identify the major contributors to and ranges of atmospheric dry N deposition to the Lake Tahoe Basin. Total flux from dry deposition ranges from 1.2 to 8.6 kg N ha-1 for the summer and fall dry season and is significantly higher than wet deposition, which ranges from 1.7 to 2.9 kg N ha-1 year-1. These preliminary results suggest that dry deposition of HNO3 is the major source of atmospheric N deposition for the Lake Tahoe Basin, and that overall N deposition is similar in magnitude to deposition reported for sites exposed to moderate N pollution in the southern California mountains.

  12. Ambient air levels of volatile organic compounds (VOC) and nitrogen dioxide (NO2) in a medium size city in Northern Spain.

    PubMed

    Parra, M A; Elustondo, D; Bermejo, R; Santamaría, J M

    2009-01-15

    Ambient concentrations of volatile organic compounds (VOC) and nitrogen dioxide (NO2) were measured by means of passive sampling at 40 sampling points in a medium-size city in Northern Spain, from June 2006 to June 2007. VOC and NO2 samplers were analysed by thermal desorption followed by gas chromatography/mass-selective detector and by visible spectrophotometry, respectively. Mean concentrations of benzene, toluene, ethylbenzene, xylenes, propylbenzene, trimethylbenzenes, and NO(2) were 2.84, 13.26, 2.15, 6.01, 0.59, 1.32 and 23.17 microg m(-3) respectively, and found to be highly correlated. Their spatial distribution showed high differences in small distances and pointed to traffic as the main emission source of these compounds. The lowest levels of VOC and NO2 occurred during summer, owing to the increase in solar radiation and to lower traffic densities. Mean concentrations of benzene and NO2 exceeded the European limits at some of the monitored points.

  13. Nitrogen dioxide

    Integrated Risk Information System (IRIS)

    Nitrogen dioxide ; CASRN 10102 - 44 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

  14. An experimental study of low-pressure premixed pyrrole/oxygen/argon flames with tunable synchrotron photoionization

    SciTech Connect

    Tian, Zhenyu; Li, Yuyang; Zhang, Taichang; Qi, Fei; Zhu, Aiguo; Cui, Zhifeng

    2007-10-15

    Two premixed laminar pyrrole/oxygen/argon flames at 3.33 kPa (25 Torr) with equivalence ratios of 0.55 (C/O/N = 1:5.19:0.25) and 1.84 (C/O/N = 1:1.56:0.25) have been investigated using tunable synchrotron photoionization and molecular-beam mass spectrometry techniques. All observed flame species, including some nitrogen-containing intermediates, have been identified by measurements of photoionization efficiency spectra. Mole fraction profiles of species including reactants, intermediates, and products have been determined by scanning burner position at some selected photon energies near ionization thresholds, and flame temperature has been measured by a Pt/Pt-13% Rh thermocouple. The results indicate that N{sub 2}, NO, and NO{sub 2} are the major nitrogenous products, while hydrogen cyanide, isocyanic acid, and 2-propenenitrile are the most important nitrogen-containing intermediates in pyrrole flames. Radicals such as methyl, propargyl, allyl, cyanomethyl, n-propyl, isobutyl, cyclopentadienyl, phenyl, cyclohexyl, phenoxy, and 4-methylbenzyl are observed as well. Moreover, ethenol and methylacrylonitrile are also detected. Reaction pathways involving the major species are proposed. The new results will be useful in developing a kinetic model of nitrogenous compound combustion. (author)

  15. Nitrogen fluxes through unsaturated zones in five agricultural settings across the United States

    USGS Publications Warehouse

    Green, C.T.; Fisher, L.H.; Bekins, B.A.

    2008-01-01

    The main physical and chemical controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Indiana, Maryland, Nebraska, and Washington from 2004 to 2005. Sites included irrigated and nonirrigated fields; soil textures ranging from clay to sand; crops including corn, soybeans, almonds, and pasture; and unsaturated zone thicknesses ranging from 1 to 22 m. Chemical analyses of water from lysimeters and shallow wells indicate that advective transport of nitrate is the dominant process affecting the flux of N below the root zone. Vertical profiles of (i) nitrogen species, (ii) stable isotopes of nitrogen and oxygen, and (iii) oxygen, N, and argon in unsaturated zone air and correlations between N and other agricultural chemicals indicate that reactions do not greatly affect N concentrations between the root zone and the capillary fringe. As a result, physical factors, such as N application rate, water inputs, and evapotranspiration, control the differences in concentrations among the sites. Concentrations of N in shallow lysimeters exhibit seasonal variation, whereas concentrations in lysimeters deeper than a few meters are relatively stable. Based on concentration and recharge estimates, fluxes of N through the deep unsaturated zone range from 7 to 99 kg ha-1 yr-1. Vertical fluxes of N in ground water are lower due to spatial and historical changes in N inputs. High N fluxes are associated with coarse sediments and high N application rates. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  16. Evidence for Argon Content in Pure Oxygen from Thermal Data

    NASA Astrophysics Data System (ADS)

    Steur, Peter P. M.; Yang, Inseok; Pavese, Franco

    2017-02-01

    Since many years it is known that argon impurities in oxygen change the temperature of the oxygen triple point by +12 K{\\cdot }mol^{-1} (positive, while most impurities decrease the temperature) without any effect on the melting range of this transition, for the impurity concentrations usually encountered in nominally pure gases. It has been hypothesized that thermal measurements on the α -β solid-to-solid transition at 23.8 K or the β -γ solid-to-solid transition at 43.8 K may give reliable evidence regarding the argon content. However, such measurements require very long times for full completion of each transition (with prohibitive costs if liquid helium is used) and for the α -β solid-to-solid transition the heat pulse method cannot be applied reliably. The availability of closed-cycle refrigerators permits the first obstacle to be surmounted. The automatic system earlier developed at INRIM during the EU Multicells project and used extensively for the project on the isotopic effect in neon is perfectly suited for such measurements. Thus, the uncertainties of the temperature measurements are similar to those obtained previously (of the order of 0.1 mK or less). Three argon-in-oxygen mixtures were prepared gravimetrically and certified at KRISS, just as was previously done for the work on the neon isotopic compositions. Results of continuous-current measurements on the α -β solid-to-solid transition, along with the triple-point data obtained with the heat pulse method, are presented for one cell with a known doped argon content, to be compared with similar data from a cell with oxygen of very high purity. In addition, some preliminary data for the β -γ solid-to-solid transition are given. The measurements on the mixture with the highest argon content, about 1002 μmol{\\cdot } mol^{-1}, imply a (linear) sensitivity of (116 ± 7) K{\\cdot }mol^{-1} for the α -β transition. This sensitivity may be different at much lower argon contents, and follow

  17. Spectral shifts of methane lines in collisions with hydrogen, helium, nitrogen, and argon

    NASA Technical Reports Server (NTRS)

    Fox, Kenneth; Jennings, Donald E.

    1989-01-01

    Pressure-induced shifts of rotational-vibrational lines in CH4 have been measured at very high spectral resolution in the R-branch of the 3nu(3) overtone. The colliding gases were H2, He, N2, and Ar. Results are presented as functions of rotational and tetrahedral quantum numbers. Mean values (in 0.001/cm per torr) for the R0-R6 multiplets are -0.01109 (CH4-H2), +0.00547 (opposite sense) (CH4-He), -0.01990 (CH4-N2), and -0.02126 (CH4-Ar).

  18. Dose effects on amorphous silicon sputtering by argon ions: A molecular dynamics simulation

    SciTech Connect

    Marques, L.A.; Rubio, J.E.; Jaraiz, M.; Bailon, L.A.; Barbolla, J.J.

    1997-02-01

    We have investigated, using molecular dynamics techniques, the sputtering yield enhancement of amorphous silicon produced by argon ion accumulation within the target. Several amorphous silicon samples, with different argon contents, were bombarded with 1 keV argon ions at normal incidence. To study the influence of the target structure, we considered samples with different argon arrangements, either uniformly distributed or within solid bubbles. We have observed that silicon sputtering yield increases linearly with dose until steady state conditions are reached. This enhancement is produced by the shallow argon atoms through the weakening of Si{endash}Si bonds. We have also observed that argon release takes place even long after the end of the collisional phase, and it is produced by ion-induced desorption and bubble destabilization. This enhanced argon yield determines the dose where target saturation and steady state conditions are reached. {copyright} {ital 1997 American Institute of Physics.}

  19. Acclimation response of spring wheat in a free-air CO(2) enrichment (FACE) atmosphere with variable soil nitrogen regimes. 3. Canopy architecture and gas exchange.

    PubMed

    Brooks, T J; Wall, G W; Pinter, P J; Kimball, B A; Lamorte, R L; Leavitt, S W; Matthias, A D; Adamsen, F J; Hunsaker, D J; Webber, A N

    2000-01-01

    The response of whole-canopy net CO(2) exchange rate (CER) and canopy architecture to CO(2) enrichment and N stress during 1996 and 1997 for open-field-grown wheat ecosystem (Triticum aestivum L. cv. Yecora Rojo) are described. Every Control (C) and FACE (F) CO(2) treatment (defined as ambient and ambient +200 mumol mol(-1), respectively) contained a Low- and High-N treatment. Low-N treatments constituted initial soil content amended with supplemental nitrogen applied at a rate of 70 kg N ha(-1) (1996) and 15 kg N ha(-1) (1997), whereas High-N treatments were supplemented with 350 kg N ha(-1) (1996 and 1997). Elevated CO(2) enhanced season-long carbon accumulation by 8% and 16% under Low-N and High-N, respectively. N-stress reduced season-long carbon accumulation 14% under ambient CO(2), but by as much as 22% under CO(2) enrichment. Averaging both years, green plant area index (GPAI) peaked approximately 76 days after planting at 7.13 for FH, 6.00 for CH, 3.89 for FL, and 3.89 for CL treatments. Leaf tip angle distribution (LTA) indicated that Low-N canopies were more erectophile than those of High-N canopies: 48 degrees for FH, 52 degrees for CH, and 58 degrees for both FL and CL treatments. Temporal trends in canopy greenness indicated a decrease in leaf chlorophyll content from the flag to flag-2 leaves of 25% for FH, 28% for CH, 17% for CL, and 33% for FL during 1997. These results indicate that significant modifications of canopy architecture occurs in response to both CO(2) and N-stress. Optimization of canopy architecture may serve as a mechanism to diminish CO(2) and N-stress effects on CER.

  20. Opacity measurements in shock-generated argon plasmas

    SciTech Connect

    Erskine, D.

    1993-07-01

    Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.