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Sample records for oxygen loss gas

  1. Inhaled hydrogen gas therapy for prevention of noise-induced hearing loss through reducing reactive oxygen species.

    PubMed

    Kurioka, Takaomi; Matsunobu, Takeshi; Satoh, Yasushi; Niwa, Katsuki; Shiotani, Akihiro

    2014-12-01

    Reactive oxygen species (ROS) that form in the inner ear play an important role in noise-induced hearing loss (NIHL). Recent studies have revealed that molecular hydrogen (H2) has great potential for reducing ROS. In this study, we examined the potential of hydrogen gas to protect against NIHL. We tested this hypothesis in guinea pigs with 0.5%, 1.0% and 1.5% H2 inhalation in air for 5h a day after noise exposure, for five consecutive days. All animals underwent measurements for auditory brainstem response after the noise exposure; the results revealed that there was a better improvement in the threshold shift for the 1.0% and 1.5% H2-treated groups than the non-treated group. Furthermore, outer hair cell (OHC) loss was examined 7 days after noise exposure. A significantly higher survival rate of OHCs was observed in the 1.0% and 1.5% H2-treated group as compared to that of the non-treated group in the basal turn. Immunohistochemical analyses for 8-hydroxy-2'-deoxyguanosine (8-OHdG) were performed to examine the amount of oxidative DNA damage. While strong immunoreactivities against 8-OHdG were observed of the non-treated group, the H2-treated group showed decreased immunoreactivity for 8-OHdG. These findings strongly suggest that inhaled hydrogen gas protects against NIHL. PMID:25196919

  2. Oxygen loss in biosphere 2

    NASA Astrophysics Data System (ADS)

    Severinghaus, Jeffrey P.; Broecker, Wallace S.; Dempster, William F.; MacCallum, Taber; Wahlen, Martin

    Oxygen concentrations have dropped sharply in the air of “Biosphere 2,” an enclosed experimental ecosystem located in southern Arizona. Biosphere 2 is a 3.15-acre airtight structure roofed in glass and underlain by an impermeable liner. It houses an artificial ecosystem containing soil, air, water, flora, and fauna and was built primarily as an apparatus for the experimental investigation of biogeochemical cycles, whole ecosystems, and life-support systems for space habitation [see Nelson et al., 1993].O2 in Biosphere 2 decreased during the first 16 months of closure from the ambient 21% to 14%, enough to cause health problems in the human occupants. We present evidence that the O2 loss is caused by microbial respiration of the excessive amount of organic matter incorporated into the experiment's soils and furthermore, that the respired CO2 is reacting with the structure's concrete to form calcium carbonate.

  3. Oxygen atom loss coefficient of carbon nanowalls

    NASA Astrophysics Data System (ADS)

    Mozetic, Miran; Vesel, Alenka; Stoica, Silviu Daniel; Vizireanu, Sorin; Dinescu, Gheorghe; Zaplotnik, Rok

    2015-04-01

    Extremely high values of atomic oxygen loss coefficient on carbon nanowall (CNW) surface are reported. CNW layers consisting of interconnected individual nanostructures with average length of 1.1 μm, average thickness of 66 nm and surface density of 3 CNW/μm2 were prepared by plasma jet enhanced chemical-vapor deposition using C2H2/H2/Ar gas mixtures. The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectrometry (RS) as well as X-ray photoelectron spectroscopy (XPS). The surface loss coefficient was measured at room temperature in a flowing afterglow at different densities of oxygen atoms supplied from inductively coupled radiofrequency O2 plasma. The RF generator operated at 13.56 MHz and different nominal powers up to 900 W corresponding to different O-atom density in the afterglow up to 1.3 × 1021 m-3. CNW and several different samples of known coefficients for heterogeneous surface recombination of neutral oxygen atoms have been placed separately in the afterglow chamber and the O-atom density in their vicinity was measured with calibrated catalytic probes. Comparison of measured results allowed for determination of the loss coefficient for CNWs and the obtained value of 0.59 ± 0.03 makes this material an extremely effective sink for O-atoms.

  4. Oxygenates vs. synthesis gas

    SciTech Connect

    Kamil Klier; Richard G. Herman; Alessandra Beretta; Maria A. Burcham; Qun Sun; Yeping Cai; Biswanath Roy

    1999-04-01

    Methanol synthesis from H{sub 2}/CO has been carried out at 7.6 MPa over zirconia-supported copper catalysts. Catalysts with nominal compositions of 10/90 mol% and 30/70 mol% Cu/ZrO{sub 2} were used in this study. Additionally, a 3 mol% cesium-doped 10/90 catalyst was prepared to study the effect of doping with heavy alkali, and this promoter greatly increased the methanol productivity. The effects of CO{sub 2} addition, water injection, reaction temperature, and H{sub 2}/C0 ratio have been investigated. Both CO{sub 2} addition to the synthesis gas and cesium doping of the catalyst promoted methanol synthesis, while inhibiting the synthesis of dimethyl ether. Injection of water, however, was found to slightly suppress methanol and dimethyl ether formation while being converted to CO{sub 2} via the water gas shift reaction over these catalysts. There was no clear correlation between copper surface area and catalyst activity. Surface analysis of the tested samples revealed that copper tended to migrate and enrich the catalyst surface. The concept of employing a double-bed reactor with a pronounced temperature gradient to enhance higher alcohol synthesis was explored, and it was found that utilization of a Cs-promoted Cu/ZnO/Cr{sub 2}O{sub 3} catalyst as a first lower temperature bed and a Cs-promoted ZnO/Cr{sub 2}O{sub 3} catalyst as a second high-temperature bed significantly promoted the productivity of 2-methyl-1-propanol (isobutanol) from H{sub 2}/CO synthesis gas mixtures. While the conversion of CO to C{sub 2+} oxygenates over the double-bed configuration was comparable to that observed over the single Cu-based catalyst, major changes in the product distribution occurred by the coupling to the zinc chromite catalyst; that is, the productivity of the C{sub 1}-C{sub 3} alcohols decreased dramatically, and 2-methyl branched alcohols were selectively formed. The desirable methanol/2-methyl oxygenate molar ratios close to 1 were obtained in the present double

  5. Loss of atomic oxygen in mass spectrometer ion sources.

    NASA Technical Reports Server (NTRS)

    Lake, L. R.; Nier, A. O.

    1973-01-01

    A gas beam consisting of a mixture of atomic and molecular oxygen has been directed at the ion source of a mass spectrometer like those used in sounding rockets for determining the neutral composition of the lower thermosphere. The loss of atomic oxygen on mass spectrometer surfaces was evaluated by flagging the beam in several ways and comparing the experimental results with predicted values. The results obtained suggest that in rocket flights using similar instruments the atomic oxygen densities computed assuming no-loss conditions may be low by a factor of 2.5. Studies made using a beam containing tracer O-18 indicate that carbon dioxide observed when atomic oxygen enters the source is formed in a reaction involving atomic oxygen from the beam and carbon monoxide from the surfaces bombarded.

  6. Oxygen liquefaction and zero-loss storage system

    NASA Technical Reports Server (NTRS)

    Lin, F. N.; Bollo, T. R.; Peterson, D. M.

    1997-01-01

    This paper presents an alternative concept that employs existing technologies and off-the-shelf components to liquefy gaseous oxygen from an in-situ propellant production (ISPP) unit and to store the liquid oxygen without boil-off loss. A primary goal is to minimize active components with a secondary goal of designing the active component in a protected or failure-free environment. The resulting design requires only one active component, a compressor operating in a closed and consequently more protected system. The design avoids pumps as active components by employing cryopumping for gaseous oxygen (GOX) and gravity transfer for liquid oxygen (LOX).

  7. 21 CFR 868.1720 - Oxygen gas analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oxygen gas analyzer. 868.1720 Section 868.1720...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1720 Oxygen gas analyzer. (a) Identification. An oxygen gas analyzer is a device intended to measure the concentration of oxygen in...

  8. 21 CFR 868.1720 - Oxygen gas analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen gas analyzer. 868.1720 Section 868.1720...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1720 Oxygen gas analyzer. (a) Identification. An oxygen gas analyzer is a device intended to measure the concentration of oxygen in...

  9. 21 CFR 868.1720 - Oxygen gas analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oxygen gas analyzer. 868.1720 Section 868.1720...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1720 Oxygen gas analyzer. (a) Identification. An oxygen gas analyzer is a device intended to measure the concentration of oxygen in...

  10. 21 CFR 868.1720 - Oxygen gas analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oxygen gas analyzer. 868.1720 Section 868.1720...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1720 Oxygen gas analyzer. (a) Identification. An oxygen gas analyzer is a device intended to measure the concentration of oxygen in...

  11. 21 CFR 868.1720 - Oxygen gas analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oxygen gas analyzer. 868.1720 Section 868.1720...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1720 Oxygen gas analyzer. (a) Identification. An oxygen gas analyzer is a device intended to measure the concentration of oxygen in...

  12. Reactive Oxygen Species, Apoptosis, and Mitochondrial Dysfunction in Hearing Loss

    PubMed Central

    Fujimoto, Chisato

    2015-01-01

    Reactive oxygen species (ROS) production is involved in several apoptotic and necrotic cell death pathways in auditory tissues. These pathways are the major causes of most types of sensorineural hearing loss, including age-related hearing loss, hereditary hearing loss, ototoxic drug-induced hearing loss, and noise-induced hearing loss. ROS production can be triggered by dysfunctional mitochondrial oxidative phosphorylation and increases or decreases in ROS-related enzymes. Although apoptotic cell death pathways are mostly activated by ROS production, there are other pathways involved in hearing loss that do not depend on ROS production. Further studies of other pathways, such as endoplasmic reticulum stress and necrotic cell death, are required. PMID:25874222

  13. Singlet oxygen generation in gas discharge for oxygen-iodine laser pumping

    NASA Astrophysics Data System (ADS)

    Lopaev, D. V.; Braginsky, O. V.; Klopovsky, K. S.; Kovalev, A. S.; Mankelevich, Yu. A.; Popov, N. A.; Rakhimov, A. T.; Rakhimova, T. V.; Vasilieva, A. N.

    2004-09-01

    The possibility of development of effective discharged singlet oxygen (SO) generator (DSOG) for oxygen-iodine laser (OIL) is studied in detail. Researches of kinetics of oxygen atoms and oxygen molecules in the lowest metastable singlet states have been carried out in the different discharges and its afterglow (DC discharges, E-beam controlled discharge and RF discharges) in both CW and pulsed mode in a wide range of conditions (pressures, gas mixtures, energy deposits etc.). The models developed for all the discharges have allowed us to analyze SO generation and loss mechanisms and to find out the key-parameters controlling the highest SO yield. It is shown that in addition to spatial plasma uniformity at low E/N and high specific energy deposit per oxygen molecule, DSOG must be oxygen atom free to avoid fast three-body quenching of SO by atomic oxygen with increasing pressure and thereby to provide pressure scaling (in tens Torrs) for applying to real OIL systems.

  14. Bimodular high temperature planar oxygen gas sensor.

    PubMed

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  15. Bimodular high temperature planar oxygen gas sensor

    PubMed Central

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  16. Marine Nitrogen loss in Oxygen minimum zones: a modeling approach

    NASA Astrophysics Data System (ADS)

    Six, Katharina; Hense, Inga; Ilyina, Tatiana

    2015-04-01

    In the oxygen minimum zones (OMZ) of the global ocean fixed nitrogen is lost by two pathways: heterotrophic denitrification and anaerobic ammonium oxidation (anammox). Lab experiments show that denitrification and anammox occur at a ratio of about 70:30 depending on the amount and the C:N ratio of the available organic matter. However, observations in the OMZ are sparse and, thus, the contribution of anammox to the global loss of fixed nitrogen is still under debate. In addition, it is projected that the OMZ expand in the future due to global warming. This compels an urgent need to understand the controlling mechanisms of nitrogen loss in OMZ. Global biogeochemical ocean models assessed in the last IPCC have a rather poor representation of nitrogen related processes, primarily focusing on nitrate. These models do not include the nitrogen loss by anammox as they lack a representation of ammonium and nitrite. Here we present results of a more comprehensive marine nitrogen cycle including interactions between nitrate, nitrite, ammonium and organic matter in the water column and the sediments in the framework of HAMOCC, the global biogeochemical ocean model of the Max Planck Institute for Meteorology. The representation of a stepwise dissimilatory nitrate reduction to nitrite and ammonium captures observed features like the secondary nitrite maximum. We set up a global marine nitrogen budget and discuss changes in the subsurface oxygen distributions.

  17. Minimizing EVA Airlock Time and Depress Gas Losses

    NASA Technical Reports Server (NTRS)

    Trevino, Luis A.; Lafuse, Sharon A.

    2008-01-01

    This paper describes the need and solution for minimizing EVA airlock time and depress gas losses using a new method that minimizes EVA out-the-door time for a suited astronaut and reclaims most of the airlock depress gas. This method consists of one or more related concepts that use an evacuated reservoir tank to store and reclaim the airlock depress gas. The evacuated tank can be an inflatable tank, a spent fuel tank from a lunar lander descent stage, or a backup airlock. During EVA airlock operations, the airlock and reservoir would be equalized at some low pressure, and through proper selection of reservoir size, most of the depress gas would be stored in the reservoir for later reclamation. The benefit of this method is directly applicable to long duration lunar and Mars missions that require multiple EVA missions (up to 100, two-person lunar EVAs) and conservation of consumables, including depress pump power and depress gas. The current ISS airlock gas reclamation method requires approximately 45 minutes of the astronaut s time in the airlock and 1 KW in electrical power. The proposed method would decrease the astronaut s time in the airlock because the depress gas is being temporarily stored in a reservoir tank for later recovery. Once the EVA crew is conducting the EVA, the volume in the reservoir would be pumped back to the cabin at a slow rate. Various trades were conducted to optimize this method, which include time to equalize the airlock with the evacuated reservoir versus reservoir size, pump power to reclaim depress gas versus time allotted, inflatable reservoir pros and cons (weight, volume, complexity), and feasibility of spent lunar nitrogen and oxygen tanks as reservoirs.

  18. INVENTORY OF METHANE LOSSES FROM THE NATURAL GAS INDUSTRY

    EPA Science Inventory

    The paper gives the second year's results of an ongoing 4-year program undertaken jointly by the Gas Research Institute and the U.S. EPA to assess the methane (CH4) losses from the U.S. natural gas industry. he program's objective is to assess the acceptability of natural gas as ...

  19. Looking east at the basic oxygen furnace building with gas ...

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

    Looking east at the basic oxygen furnace building with gas cleaning plants in foreground on the left and the right side of the furnace building. - U.S. Steel Edgar Thomson Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Braddock, Allegheny County, PA

  20. Resistive Oxygen Gas Sensors for Harsh Environments

    PubMed Central

    Moos, Ralf; Izu, Noriya; Rettig, Frank; Reiß, Sebastian; Shin, Woosuck; Matsubara, Ichiro

    2011-01-01

    Resistive oxygen sensors are an inexpensive alternative to the classical potentiometric zirconia oxygen sensor, especially for use in harsh environments and at temperatures of several hundred °C or even higher. This device-oriented paper gives a historical overview on the development of these sensor materials. It focuses especially on approaches to obtain a temperature independent behavior. It is shown that although in the past 40 years there have always been several research groups working concurrently with resistive oxygen sensors, novel ideas continue to emerge today with respect to improvements of the sensor response time, the temperature dependence, the long-term stability or the manufacture of the devices themselves using novel techniques for the sensitive films. Materials that are the focus of this review are metal oxides; especially titania, titanates, and ceria-based formulations. PMID:22163805

  1. Oxygen consumption and evaporative water loss in infants with congenital heart disease.

    PubMed Central

    Kennaird, D L

    1976-01-01

    The relation between environmental temperature, heat production, oxygen consumption, and evaporative water loss was studied in 67 infants with congenital heart disease. The majority of the cyanosed infants had a low minimum oxygen consumption, a low evaporative water loss, and a diminished metabolic response to cold stress. Minimum oxygen consumption and evaporative water loss rose in 6 of these infants after the construction of a surgical shunt. Many of the ill acyanotic infants had an abnormally high minimum oxygen consumption, and those in cardiac failure often continued to sweat in an environment below the thermoneutral temperature zone. PMID:942228

  2. On atmospheric loss of oxygen ions from earth through magnetospheric processes.

    PubMed

    Seki, K; Elphic, R C; Hirahara, M; Terasawa, T; Mukai, T

    2001-03-01

    In Earth's environment, the observed polar outflow rate for O(+) ions, the main source of oxygen above gravitational escape energy, corresponds to the loss of approximately 18% of the present-day atmospheric oxygen over 3 billion years. However, part of this apparent loss can actually be returned to the atmosphere. Examining loss rates of four escape routes with high-altitude spacecraft observations, we show that the total oxygen loss rate inferred from current knowledge is about one order of magnitude smaller than the polar O(+) outflow rate. This disagreement suggests that there may be a substantial return flux from the magnetosphere to the low-latitude ionosphere. Then the net oxygen loss over 3 billion years drops to approximately 2% of the current atmospheric oxygen content. PMID:11239148

  3. Oxygen-permeable ceramic membranes for gas separation

    SciTech Connect

    Balachandran, U.; Ma, B.; Maiya, P.S.; Dusek, J.T.; Mieville, R.L.; Picciolo, J.J.

    1998-02-01

    Mixed-conducting oxides have a wide range of applications, including fuel cells, gas separation systems, sensors, and electrocatalytic equipment. Dense ceramic membranes made of mixed-conducting oxides are particularly attractive for gas separation and methane conversion processes. Membranes made of Sr-Fe-Co oxide, which exhibits high combined electronic and oxygen ionic conductivities, can be used to selectively transport oxygen during the partial oxidation of methane to synthesis gas (syngas, i.e., CO + H{sub 2}). The authors have fabricated tubular Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes and tested them (some for more than 1,000 h) in a methane conversion reactor that was operating at 850--950 C. An oxygen permeation flux of {approx} 10 scc/cm{sup 2} {center_dot} min was obtained at 900 C in a tubular membrane with a wall thickness of 0.75 mm. Using a gas-tight electrochemical cell, the authors have also measured the steady-state oxygen permeability of flat Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes as a function of temperature and oxygen partial pressure(pO{sub 2}). Steady-state oxygen permeability increases with increasing temperature and with the difference in pO{sub 2} on the two sides of the membrane. At 900 C, an oxygen permeability of {approx} 2.5 scc/cm{sup 2} {center_dot} min was obtained in a 2.9-mm-thick membrane. This value agrees with that obtained in methane conversion reactor experiments. Current-voltage (I-V) characteristics determined in the gas-tight cell indicate that bulk effect, rather than surface exchange effect, is the main limiting factor for oxygen permeation of {approx} 1-mm-thick Sr{sub 2}Fe{sub 2}CoO{sub 6+{delta}} membranes at elevated temperatures (> 650 C).

  4. Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 2; Gas Separation Technology--State of the Art

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas L.; Eklund, Thor I.; Haack, Gregory A.

    2001-01-01

    This purpose of this contract study task was to investigate the State of the Art in Gas Separation Technologies utilized for separating air into both nitrogen and oxygen gases for potential applications on commercial aircraft. The intended applications included: nitrogen gas for fuel tank inerting, cargo compartment fire protection, and emergency oxygen for passenger and crew use in the event of loss of cabin pressure. The approach was to investigate three principle methods of gas separation: Hollow Fiber Membrane (HFM), Ceramic Membrane (CM), and liquefaction: Total Atmospheric Liquefaction of Oxygen and Nitrogen (TALON). Additional data on the performance of molecular sieve pressure swing adsorption (PSA) systems was also collected and discussed. Performance comparisons of these technologies are contained in the body of the report.

  5. BIOVENTING - Groundwater Aeration by Discontinuous Oxygen Gas Pulse Injections

    NASA Astrophysics Data System (ADS)

    Schirmer, M.

    2003-12-01

    Groundwater aeration by discontinuous oxygen gas pulse injections appears to be a promising concept for enhanced natural attenuation of dissolved contaminants that are susceptible for oxygenase enzyme attacks. Oxygen amendments facilitate indigenous microbiota to catabolize groundwater pollutants, such as aromatics, that are considered to be recalcitrant in absence of dissolved oxygen. As a rule, natural attenuation of many pollutants under aerobic conditions is considerably faster than under anaerobic conditions. Thus, enhancing the dissolved oxygen level appears to be worthwhile. In situ aeration of groundwater has been accomplished by air sparging, H2O2-supply, or by utilization of oxygen release compounds. However, continuous aeration of previously anaerobic groundwater is not desirable for several reasons: (a) economic efforts too high, (b) pollutant dislocation towards surface (desired only in air sparging), (c) risk of aquifer clogging (gas clogging, oxidation of ferrous iron, formation of bioslimes). In contrast, discontinuous oxygen gas sparging provides only for periodical groundwater aeration which is followed by microaerobic and suboxic conditions. Microaerobic conditions can prevail spatially (e.g., at plume fringes or within biofilms) or temporarily (e.g., at discontinuous bioventing). They still allow adapted bacteria to transform environmental pollutants to less toxic compounds, e.g., aromatic ring cleavage after dioxygenasis attack. Ring cleavage products, on the other hand, may be degraded more easily by anaerobic consortia than the initial aromatic compounds, making oxygen depletion periods highly intriguing in regard to an initiation of natural attenuation processes at plume fringes. In our work we outline the effect of oxygen depletion conditions on biodegradation of monchlorobenzene (MCB) as they occur subsequently to temporary aeration periods. For microaerobic conditions, relative to the oxygen supply, a stoichiometric transformation of MCB

  6. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, Roswell J.; Basel, Richard A.

    1996-01-01

    A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

  7. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, R.J.; Basel, R.A.

    1996-03-12

    A gas sensor measures O{sub 2} content of a reformable monitored gas containing hydrocarbons, H{sub 2}O and/or CO{sub 2}, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system. 4 figs.

  8. Oxygen fugacity of basaltic magmas and the role of gas-forming elements

    NASA Technical Reports Server (NTRS)

    Sato, M.

    1978-01-01

    It is suggested that major variations in the relative oxygen fugacity of a basaltic magma are caused primarily by gas-forming elements, especially carbon and hydrogen. According to this theory, carbon, present in the source region of a basaltic magma, reduces the host magma during ascent, as isothermally carbon becomes more reducing with decreasing pressure. For an anhydrous magma such as lunar basalts, this reduction continues through the extrusive phase and the relative oxygen fugacity decreases rapidly until buffered by the precipitation of a metallic phase. For hydrous magmas such as terrestrial basalts, reduction by carbon is eventually superceded by oxidation due to loss of H2 generated by the reaction of C with H2O and by thermal dissociation of H2O. The relative oxygen fugacity of a hydrous magma initially decreases as a magma ascends from the source region and then increases until magnetite crystallization curbs the rising trend of the relative oxygen fugacity.

  9. The study of excited oxygen molecule gas species production and quenching on thermal protection system materials

    NASA Technical Reports Server (NTRS)

    Nordine, Paul C.; Fujimoto, Gordon T.; Greene, Frank T.

    1987-01-01

    The detection of excited oxygen and ozone molecules formed by surface catalyzed oxygen atom recombination and reaction was investigated by laser induced fluorescence (LIF), molecular beam mass spectrometric (MBMS), and field ionization (FI) techniques. The experiment used partially dissociated oxygen flows from a microwave discharge at pressures in the range from 60 to 400 Pa or from an inductively coupled RF discharge at atmospheric pressure. The catalyst materials investigated were nickel and the reaction cured glass coating used for Space Shuttle reusable surface insulation tiles. Nonradiative loss processes for the laser excited states makes LIF detection of O2 difficult such that formation of excited oxygen molecules could not be detected in the flow from the microwave discharge or in the gaseous products of atom loss on nickel. MBMS experiments showed that ozone was a product of heterogeneous O atom loss on nickel and tile surfaces at low temperatures and that ozone is lost on these materials at elevated temperatures. FI was separately investigated as a method by which excited oxygen molecules may be conveniently detected. Partial O2 dissociation decreases the current produced by FI of the gas.

  10. Diffusive Gas Loss from Silica Glass Ampoules at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Palosz, W.

    1998-01-01

    Changes in the pressure of hydrogen, helium and neon due to diffusion through the wall of silica crystal growth ampoules at elevated temperatures were determined experimentally. We show that, while both He- and Ne-losses closely follow conventional model of diffusive gas permeation through the wall, hydrogen losses, in particular at low fill pressures, can be much larger. This is interpreted in terms of the high solubility of hydrogen in silica glasses.

  11. Hyperbaric oxygen therapy in sudden sensorineural hearing loss following spinal anesthesia: case reports.

    PubMed

    Carneiro, Sandra N; Guerreiro, Ditza V; Cunha, Anita M; Camacho, Óscar F; Aguiar, Isabel C

    2016-01-01

    The management of sudden sensorineural hearing loss following spinal anesthesia is currently an open problem. Several strategies have been used with variable results and, to the best of our knowledge, there are no prior accounts in the literature on the use of hyperbaric oxygen therapy in the treatment of this complication. We report two cases of acute onset of unilateral hearing loss after spinal anesthesia, with significantly improved results after hyperbaric oxygen therapy. A hypothesis on the possible mechanism behind this complication is discussed. A relation is established between hyperbaric oxygen therapy and this hypothetical mechanism, in order to explain successful results in the reported cases. PMID:27265992

  12. Gas and aerosol wall losses in Teflon film smog chambers

    SciTech Connect

    McMurry, P.H.; Grosjean, D.

    1985-12-01

    Large smog chambers (approx.60 m/sup 3/) constructed of FEP Teflon film are frequently used to study photochemistry and aerosol formation in model chemical systems. In a previous paper a theory for aerosol wall loss rates in Teflon film smog chambers was developed; predicted particle loss rates were in good agreement with measured rates. In the present paper, measurements of wall deposition rates and the effects of wall losses on measurements of gas-to-particle conversion in smog chambers are discussed. Calculations indicate that a large fraction of the aerosol formed in several smog chamber experiments was on the chamber walls at the end of the experiment. Estimated values for particulate organic carbon yield for several precursor hydrocarbons increased by factors of 1.3-6.0 when wall deposition was taken into account. The theory is also extended to loss rates of gaseous species. Such loss rates are either limited by diffusion through a concentration boundary layer near the surface or by uptake at the surface. It is shown that for a typical 60-m/sup 3/ Teflon film smog chamber, gas loss rates are limited by surface reaction rates if mass accommodation coefficients are less than 6 x 10/sup -6/. It follows that previously reported loss rates of several gases in a chamber of this type were limited by surface reactions.

  13. Hyperbaric oxygen treatment for air or gas embolism.

    PubMed

    Moon, R E

    2014-01-01

    Gas can enter arteries (arterial gas embolism) due to alveolar-capillary disruption (caused by pulmonary overpressurization, e.g., breath-hold ascent by divers) or veins (venous gas embolism, VGE) as a result of tissue bubble formation due to decompression (diving, altitude exposure) or during certain surgical procedures where capillary hydrostatic pressure at the incision site is sub-atmospheric. Both AGE and VGE can be caused by iatrogenic gas injection. AGE usually produces strokelike manifestations, such as impaired consciousness, confusion, seizures and focal neurological deficits. Small amounts of VGE are often tolerated due to filtration by pulmonary capillaries. However, VGE can cause pulmonary edema, cardiac "vapor lock" and AGE due to transpulmonary passage or right-to-left shunt through a patent foramen ovale. Intravascular gas can cause arterial obstruction or endothelial damage and secondary vasospasm and capillary leak. Vascular gas is frequently not visible with radiographic imaging, which should not be used to exclude the diagnosis of AGE. Isolated VGE usually requires no treatment; AGE treatment is similar to decompression sickness (DCS), with first aid oxygen then hyperbaric oxygen. Although cerebral AGE (CAGE) often causes intracranial hypertension, animal studies have failed to demonstrate a benefit of induced hypocapnia. An evidence-based review of adjunctive therapies is presented. PMID:24851554

  14. Fetal loss and contraceptive acceptance among the Bhopal gas victims.

    PubMed

    Kapoor, R

    1991-01-01

    The rates of fetal loss and family planning acceptance among Bhopal gas victims from 1984 to 1989 were compared to those of a control group. In all, 136 eligible women in the affected area and 139 women in the control area were interviewed. Care was taken to ensure that these women had conceived at least once during the previous five years. The The fetal loss rate among the gas-affected women was abnormally high (26.3 per cent) compared to that of women in the control area (7.8 per cent). Family planning acceptance in both areas was similar, with most women using permanent methods. In the case of temporary methods, the percentage of use was higher in the gas-affected area. PMID:1801204

  15. Evolved Gas from Insulating Oil Heating under Oxygen Existence

    NASA Astrophysics Data System (ADS)

    Miyajima, Kiwamu; Sawatsu, Takahiro

    In recent years, the superannuated transformers have been increasing. This causes such problems as requiring the maintenance of diagnosing internal abnormalities of a transformer and carrying out condition assessment. One of the ways to assess the internal condition is a gas analysis of the insulating oil. In this analysis, low-temperature overheating, the pre-phenomenon of the abnormal heating in the transformer, can be detected. Finding and dealing with this abnormality at the early stages reduce the risk of transformer failure. However, evolved gas of this analysis shows different patterns depending on the existence or non-existence of oxygen.

  16. Hydrogen and Oxygen Gas Production in the UT TRIGA Reflector

    SciTech Connect

    D. S. O'Kelly

    2000-11-12

    In December 1999, The University of Texas at Austin (UT) reported an unusual condition associated with the annular graphite reflector surrounding the Nuclear Engineering Teaching Laboratory (NETL) TRIGA reactor. The aluminum container encapsulating the graphite showed signs of bulging or swelling. Further, during an investigation of this occurrence, bubbles were detected coming from a weld in the aluminum. The gas composition was approximately 2:1 hydrogen to oxygen. After safety review and equipment fabrication, the reflector was successfully vented and flooded. The ratio of the gases produced is unusual, and the gas production mechanism has not yet been explained.

  17. Corrosion by oxygen in oil and gas well casings

    SciTech Connect

    Martucci, S.; Dinon, M. )

    1993-10-01

    In September 1987, the Della 1 gas well in the Cooper Basin in South Australia blew out to surface. Originally, it was believed that sulfate-reducing bacteria (SRB) had perforated the casings, but numerous workovers on other wells and subsequent investigations indicated that SRB were not the major problem but that corrosion was simply occurring by an oxygen-reduction cathode process. The paper describes the failures and investigates the mechanism of corrosion.

  18. Hydrogen and Oxygen Gas Monitoring System Design and Operation

    SciTech Connect

    Lee C. Cadwallader; Kevin G. DeWall; J. Stephen Herring

    2007-06-01

    This paper describes pertinent design practices of selecting types of monitors, monitor unit placement, setpoint selection, and maintenance considerations for gas monitors. While hydrogen gas monitors and enriched oxygen atmosphere monitors as they would be needed for hydrogen production experiments are the primary focus of this paper, monitors for carbon monoxide and carbon dioxide are also discussed. The experiences of designing, installing, and calibrating gas monitors for a laboratory where experiments in support of the DOE Nuclear Hydrogen Initiative (NHI) are described along with codes, standards, and regulations for these monitors. Information from the literature about best operating practices is also presented. The NHI program has two types of activities. The first, near-term activity is laboratory and pilot-plant experimentation with different processes in the kilogram per day scale to select the most promising types of processes for future applications of hydrogen production. Prudent design calls for indoor gas monitors to sense any hydrogen leaks within these laboratory rooms. The second, longer-term activity is the prototype, or large-scale plants to produce tons of hydrogen per day. These large, outdoor production plants will require area (or “fencepost”) monitoring of hydrogen gas leaks. Some processes will have oxygen production with hydrogen production, and any oxygen releases are also safety concerns since oxygen gas is the strongest oxidizer. Monitoring of these gases is important for personnel safety of both indoor and outdoor experiments. There is some guidance available about proper placement of monitors. The fixed point, stationary monitor can only function if the intruding gas contacts the monitor. Therefore, monitor placement is vital to proper monitoring of the room or area. Factors in sensor location selection include: indoor or outdoor site, the location and nature of potential vapor/gas sources, chemical and physical data of the

  19. Bulk manufacture of concentrated oxygen gas-filled microparticles for intravenous oxygen delivery.

    PubMed

    Kheir, John N; Polizzotti, Brian D; Thomson, Lindsay M; O'Connell, Daniel W; Black, Katherine J; Lee, Robert W; Wilking, James N; Graham, Adam C; Bell, David C; McGowan, Francis X

    2013-08-01

    Self-assembling, concentrated, lipid-based oxygen microparticles (LOMs) have been developed to administer oxygen gas when injected intravenously, preventing organ injury and death from systemic hypoxemia in animal models. Distinct from blood substitutes, LOMs are a one-way oxygen carrier designed to rescue patients who experience life-threatening hypoxemia, as caused by airway obstruction or severe lung injury. Here, we describe methods to manufacture large quantities of LOMs using an in-line, recycling, high-shear homogenizer, which can create up to 4 liters of microparticle emulsion in 10 minutes, with particles containing a median diameter of 0.93 microns and 60 volume% of gas phase. Using this process, we screen 30 combinations of commonly used excipients for their ability to form stable LOMs. LOMs composed of DSPC and cholesterol in a 1:1 molar ratio are stable for a 100 day observation period, and the number of particles exceeding 10 microns in diameter does not increase over time. When mixed with blood in vitro, LOMs fully oxygenate blood within 3.95 seconds of contact, and do not cause hemolysis or complement activation. LOMs can be manufactured in bulk by high shear homogenization, and appear to have a stability and size profile which merit further testing. PMID:23471884

  20. Universal Loss Dynamics in a Unitary Bose Gas

    NASA Astrophysics Data System (ADS)

    Eismann, Ulrich; Khaykovich, Lev; Laurent, Sébastien; Ferrier-Barbut, Igor; Rem, Benno S.; Grier, Andrew T.; Delehaye, Marion; Chevy, Frédéric; Salomon, Christophe; Ha, Li-Chung; Chin, Cheng

    2016-04-01

    The low-temperature unitary Bose gas is a fundamental paradigm in few-body and many-body physics, attracting wide theoretical and experimental interest. Here, we present experiments performed with unitary 133Cs and 7Li atoms in two different setups, which enable quantitative comparison of the three-body recombination rate in the low-temperature domain. We develop a theoretical model that describes the dynamic competition between two-body evaporation and three-body recombination in a harmonically trapped unitary atomic gas above the condensation temperature. We identify a universal "magic" trap depth where, within some parameter range, evaporative cooling is balanced by recombination heating and the gas temperature stays constant. Our model is developed for the usual three-dimensional evaporation regime as well as the two-dimensional evaporation case, and it fully supports our experimental findings. Combined 133Cs and 7Li experimental data allow investigations of loss dynamics over 2 orders of magnitude in temperature and 4 orders of magnitude in three-body loss rate. We confirm the 1 /T2 temperature universality law. In particular, we measure, for the first time, the Efimov inelasticity parameter η*=0.098 (7 ) for the 47.8-G d -wave Feshbach resonance in 133Cs. Our result supports the universal loss dynamics of trapped unitary Bose gases up to a single parameter η*.

  1. Breathing 100% oxygen compared with 50% oxygen: 50% nitrogen reduces altitude-induced venous gas emboli

    NASA Technical Reports Server (NTRS)

    Webb, J. T.; Pilmanis, A. A.

    1993-01-01

    The risk of venous gas emboli (VGE) and decompression sickness (DCS) must be determined before selection of the lowest pressure for an extravehicular activity (EVA) pressure suit which eliminates the requirement for prebreathing. In earlier studies, use of a 50% oxygen:50% nitrogen breathing mixture (50:50 mix) during 139 zero-prebreathe decompressions of male subjects to 8.3-7.8 psia resulted in 51 instances of severe VGE and one case of DCS. Our current study investigated effects of 40 zero-prebreathe decompressions of male subjects to 8.3-6.8 psia for 6 h while breathing 100% oxygen and performing moderate exercise. No DCS symptoms were observed. Severe VGE were not detected at 8.3 psia, but were present during 10%, 20%, and 40% of the exposures at 7.8, 7.3, and 6.8 psia, respectively. Zero-prebreathe decompression while breathing 100% oxygen results in significantly lower VGE and DCS risk levels than while breathing a 50:50 mix. Our results show that 7.3 psia EVA pressure suits with 100% oxygen should be safer than 8.3 psia suits with a 50:50 mix.

  2. Properties of turbulence in natural gas-oxygen diffusion flames

    SciTech Connect

    Sautet, J.C.; Ditaranto, M. ); Samaniego, J.M.; Charon, O. )

    1999-07-01

    Measurements of turbulent flow field velocities, including first and second order velocity moments and the shear stress are carried out by laser Doppler velocimetry in five different, 25 kW, turbulent natural gas-oxygen diffusion flames. The mean flow behavior is described including the velocity half value radius as well as centerline velocity. Mean radial velocity profiles are fitted by a Gaussian function. According to the initial momentum ratio, different jet dynamic behaviors are pointed out by the description of the fluctuating velocity field.

  3. Oxygen compatibility of pressure regulators for gas cylinders

    NASA Astrophysics Data System (ADS)

    Barthelemy, Herve; Delode, Georges; Vagnard, Gerard

    Violent ignitions which have been reported in oxygen pressure regulators upon opening of gas cylinder valves may be attributed to oil contamination, particle impact, or adiabatic compression. Attention is presently given to adiabatic compression, whose conditions have been investigated in laboratory tests with a view to the influence of the metallic and nonmetallic materials used. The influence of material type is noted to be strongly affected by the internal design of the pressure regulator. Also discussed are the test methods thus far formulated for this phenomenon by European and international standards authorities.

  4. Integrated production of fuel gas and oxygenated organic compounds from synthesis gas

    DOEpatents

    Moore, Robert B.; Hegarty, William P.; Studer, David W.; Tirados, Edward J.

    1995-01-01

    An oxygenated organic liquid product and a fuel gas are produced from a portion of synthesis gas comprising hydrogen, carbon monoxide, carbon dioxide, and sulfur-containing compounds in a integrated feed treatment and catalytic reaction system. To prevent catalyst poisoning, the sulfur-containing compounds in the reactor feed are absorbed in a liquid comprising the reactor product, and the resulting sulfur-containing liquid is regenerated by stripping with untreated synthesis gas from the reactor. Stripping offgas is combined with the remaining synthesis gas to provide a fuel gas product. A portion of the regenerated liquid is used as makeup to the absorber and the remainder is withdrawn as a liquid product. The method is particularly useful for integration with a combined cycle coal gasification system utilizing a gas turbine for electric power generation.

  5. Reactive oxygen species production and discontinuous gas exchange in insects

    PubMed Central

    Boardman, Leigh; Terblanche, John S.; Hetz, Stefan K.; Marais, Elrike; Chown, Steven L.

    2012-01-01

    While biochemical mechanisms are typically used by animals to reduce oxidative damage, insects are suspected to employ a higher organizational level, discontinuous gas exchange mechanism to do so. Using a combination of real-time, flow-through respirometry and live-cell fluorescence microscopy, we show that spiracular control associated with the discontinuous gas exchange cycle (DGC) in Samia cynthia pupae is related to reactive oxygen species (ROS). Hyperoxia fails to increase mean ROS production, although minima are elevated above normoxic levels. Furthermore, a negative relationship between mean and mean ROS production indicates that higher ROS production is generally associated with lower . Our results, therefore, suggest a possible signalling role for ROS in DGC, rather than supporting the idea that DGC acts to reduce oxidative damage by regulating ROS production. PMID:21865257

  6. Reactive oxygen species production and discontinuous gas exchange in insects.

    PubMed

    Boardman, Leigh; Terblanche, John S; Hetz, Stefan K; Marais, Elrike; Chown, Steven L

    2012-03-01

    While biochemical mechanisms are typically used by animals to reduce oxidative damage, insects are suspected to employ a higher organizational level, discontinuous gas exchange mechanism to do so. Using a combination of real-time, flow-through respirometry and live-cell fluorescence microscopy, we show that spiracular control associated with the discontinuous gas exchange cycle (DGC) in Samia cynthia pupae is related to reactive oxygen species (ROS). Hyperoxia fails to increase mean ROS production, although minima are elevated above normoxic levels. Furthermore, a negative relationship between mean and mean ROS production indicates that higher ROS production is generally associated with lower . Our results, therefore, suggest a possible signalling role for ROS in DGC, rather than supporting the idea that DGC acts to reduce oxidative damage by regulating ROS production. PMID:21865257

  7. Dissociation of temperature-gradient and evaporative heat loss during cold gas hyperventilation in cold-induced asthma.

    PubMed

    Ingenito, E; Solway, J; Lafleur, J; Lombardo, A; Drazen, J M; Pichurko, B

    1988-09-01

    We examined temperature-gradient and evaporative energy losses during cold gas inhalation challenges in patients with exercise-induced asthma by using gases with similar water-carrying capacities but significantly different volume heat capacities. Seven subjects were asked to hyperventilate mixtures of 80% helium/20% oxygen (HeO2) or 80% sulfur hexafluoride/20% oxygen (SF6O2) for 5 min at a fixed target minute ventilation of 20 x FEV1 and an inspired gas temperature of 0 degrees C. Each subject equilibrated his or her lungs with the appropriate gas mixture prior to testing: PETCO2 and FIO2 were monitored and maintained at constant values (CO2 = 0.05; O2 = 0.20) by CO2 scrubbing and addition of compressed gas to the system. Gas composition, inspired and expired flow rates, and gas temperatures at the airway opening were recorded in real time using a computer-based data collection system that calculated respiratory heat loss on a per breath basis. Bronchoconstriction was quantitated using specific airway conductance measured before and serially after each challenge. The degree of bronchoconstriction correlated closely with evaporative respiratory heat loss (r = 0.658 p less than 0.05), but poorly with both temperature-gradient (r = 0.114, p greater than 0.20) and total (r = 0.268, p greater than 0.15) heat loss. These findings suggest that total respiratory heat loss is not the primary stimulus in exercise-induced asthma, and further suggest that total water loss, or focal heat/water loss, may be important in inducing bronchospasm in this subset of asthmatics. PMID:3202410

  8. Commercialization Development of Oxygen Fired CFB for Greenhouse Gas Control

    SciTech Connect

    Nsakala ya Nsakala; Gregory N. Liljedahl; David G. Turek

    2007-03-31

    Given that fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic (i.e., man-made) CO{sub 2} emissions. In 2001, ALSTOM Power Inc. (ALSTOM) began a two-phase program to investigate the feasibility of various carbon capture technologies. This program was sponsored under a Cooperative Agreement from the US Department of Energy's National Energy Technology Laboratory (DOE). The first phase entailed a comprehensive study evaluating the technical feasibility and economics of alternate CO{sub 2} capture technologies applied to Greenfield US coal-fired electric generation power plants. Thirteen cases, representing various levels of technology development, were evaluated. Seven cases represented coal combustion in CFB type equipment. Four cases represented Integrated Gasification Combined Cycle (IGCC) systems. Two cases represented advanced Chemical Looping Combined Cycle systems. Marion, et al. reported the details of this work in 2003. One of the thirteen cases studied utilized an oxygen-fired circulating fluidized bed (CFB) boiler. In this concept, the fuel is fired with a mixture of oxygen and recirculated flue gas (mainly CO{sub 2}). This combustion process yields a flue gas containing over 80 percent (by volume) CO{sub 2}. This flue gas can be processed relatively easily to enrich the CO{sub 2} content to over 96 percent for use in enhanced oil or gas recovery (EOR or EGR) or simply dried for sequestration. The Phase I study identified the O{sub 2}-fired CFB as having a near term development potential, because it uses conventional commercial CFB technology and commercially available CO{sub 2} capture enabling technologies such as cryogenic air separation and simple rectification or distillation gas processing systems. In the long term, air separation technology

  9. Effects of oxygen cover gas and NaOH dilution on gas generation in tank 241-SY-101 waste

    SciTech Connect

    Person, J.C.

    1996-05-30

    Laboratory studies are reported of gas generation in heated waste from tank 241-SY-101. The rates of gas generation and the compositions of product gas were measured. Three types of tests are compared. The tests use: undiluted waste, waste diluted by a 54% addition of 2.5 M NaOH, and undiluted waste with a reactive cover gas of 30% Oxygen in He. The gas generation rate is reduced by dilution, increased by higher temperatures (which determines activation energies), and increased by reactions of Oxygen (these primarily produce H{sub 2}). Gases are generated as reduction products oxidation of organic carbon species by nitrite and oxygen.

  10. Estimating IC engine exhaust gas lambda and oxygen from the response of a universal exhaust gas oxygen sensor

    NASA Astrophysics Data System (ADS)

    Collings, N.; Harris, J. A.; Glover, K.

    2013-09-01

    Universal exhaust gas oxygen sensors (UEGOs) are in widespread use in internal combustion engines where they are used to measure lambda (the non-dimensional air-fuel ratio) and oxygen concentration (X_{O_2 }). The sensors are used on production engines and for research and development. In a previous paper, a model of the UEGO sensor was presented, based on a solution of the Stefan-Maxwell equations for an axisymmetric geometry, and it was shown that for a known gas composition, predictions of the sensor response agreed well with experiment. In the present paper, the more ‘practical’ problem is addressed: how well can such a model predict λ and X_{O_2 } based on the sensor response? For IC engine applications, a chemistry model is required in order to predict λ, and such a model is also desirable for an accurate prediction of X_{O_2 }. A fast (matrix exponential) method of solving the Stefan-Maxwell equations is also introduced, which offers the possibility of a near real-time computation of λ and X_{O_2 }, with application, for example, to bench instruments. Extensive results are presented showing how the interpretation of the UEGO response may be compromised by uncertainties. These uncertainties may relate not only to the sensor itself, such as temperature, pressure and mean pore diameter, but also the chemistry model.

  11. Anomalous Oxygen and Krypton Abundances in Interstellar Gas

    NASA Technical Reports Server (NTRS)

    Meyer, David M.

    2004-01-01

    The primary objective of this program was to obtain FUSE observations of the interstellar H2 absorption toward a sample of stars observed with the HST STIS spectrograph as part of the ISM SNAP Survey. This Survey was designed to produce a database of high quality, high resolution W spectra from which interstellar gas-phase elemental abundances could be derived for large portions of the Galaxy. In particular, oxygen and krypton were chosen as excellent tracers for measuring the homogeneity of the interstellar gas due to their weak depletion into dust grains. The gas-phase 0 and Kr abundances relative to total hydrogen column density had previously been shown with HST GHRS measurements to be essentially constant in the local Milky Way. One of the main motivations of the ISM SNAP Survey was to determine if this constancy held at greater distances and in denser sightlines (where depletion into dust could be a possibility). The initial ISM SNAP STIS observations indicated a number of sightlines with unusual 0 and Kr abundances relative to the measured H I column densities. Since the appropriate benchmark for accurate abundance comparisons is the total hydrogen column density (H I plus H2), FUSE observations of interstellar H2 were carried out in these sightlines in order to determine if they represent cases of true abundance anomalies.

  12. Mass loss and dust formation around oxygen-rich evolved stars

    NASA Astrophysics Data System (ADS)

    Kemper, F.

    2002-09-01

    This work is a study of the formation of dust around oxygen-rich evolved stars, in correlation with the physical conditions in this environment. ISO SWS and LWS spectroscopy has been analysed, and several mineral and molecular species are identified. For two evolved stars: OH/IR star OH 127.8+0.0 and planetary nebula NGC 6302, the spectral energy distribution has been fitted. Metallic iron and carbonates are identified as new dust components. In addition, the degree of crystallinity of silicates has been studied as a function of mass-loss rate. Finally, submm observations of rotational transitions of CO have been analysed to study the mass-loss history of oxygen-rich AGB stars.

  13. Oxygen tension measurement using an automatic blood gas analyser1

    PubMed Central

    Becket, J; Chakrabarti, M K; Gillies, I D S; Orchard, C; Hall, G M; Bourdillon, P J

    1981-01-01

    Two different methods of assessing the reliability of the oxygen electrode of one model of an automatic blood gas analyser (BGA) have been studied. In the first, a single automatic BGA was assessed by using outdated bank blood which was pumped around a small extracorporeal circuit into which known gas mixtures were passed. Oxygen tension was varied between 2 and 16 kPa. In the second, fresh heparinized blood was tonometered with calibrated gases and submitted to the automatic BGA used in the first part of the study and also to three other identical machines. Each of the machines was between 3 and 4 years old. Eighteen different units of blood were used in the first part of the study. The correlation coefficient between the automatic BGA and the Po2 in the extracorporeal circuit varied between 0.29 and 0.99. 31% of the total of 209 measurements made by the automatic BGA were more than 1.2 kPa from the reference value, 25% of them being between 1.2 and 4.0 kPa from the reference value. In the second part of the study, the correlation coefficient between this automatic BGA and the tonometered blood was 0.96. The correlation coefficients for the 3 other identical BGAs were 0.84, 0.97 and 0.88, indicating that the BGA used in the first part of the study was no worse than any of the others. It is suggested that although clinicians are likely to ignore readings of an automatic BGA that are more than 4.0 kPa from the true value and are likely to repeat the investigation, readings between 1.2 and 4.0 kPa from the true value may adversely affect patient management. PMID:7288796

  14. Oxygen tension measurement using an automatic blood gas analyser.

    PubMed

    Becket, J; Orchard, C; Chakrabarti, M K; Hall, G M; Gillies, I D; Bourdillon, P J

    1981-08-01

    Two different methods of assessing the reliability of the oxygen electrode of one model of an automatic blood gas analyser (BGA) have been studied. In the first, a single automatic BGA was assessed by using outdated bank blood which was pumped around a small extracorporeal circuit into which known gas mixtures were passed. Oxygen tension was varied between 2 and 16 kPa. In the second, fresh heparinized blood was tonometered with calibrated gases and submitted to the automatic BGA used in the first part of the study and also to three other identical machines. Each of the machines was between 3 and 4 years old.Eighteen different units of blood were used in the first part of the study. The correlation coefficient between the automatic BGA and the Po(2) in the extracorporeal circuit varied between 0.29 and 0.99. 31% of the total of 209 measurements made by the automatic BGA were more than 1.2 kPa from the reference value, 25% of them being between 1.2 and 4.0 kPa from the reference value. In the second part of the study, the correlation coefficient between this automatic BGA and the tonometered blood was 0.96. The correlation coefficients for the 3 other identical BGAs were 0.84, 0.97 and 0.88, indicating that the BGA used in the first part of the study was no worse than any of the others.It is suggested that although clinicians are likely to ignore readings of an automatic BGA that are more than 4.0 kPa from the true value and are likely to repeat the investigation, readings between 1.2 and 4.0 kPa from the true value may adversely affect patient management. PMID:7288796

  15. The influence of woody encroachment on the nitrogen cycle: fixation, storage and gas loss

    NASA Astrophysics Data System (ADS)

    Soper, F.; Sparks, J. P.

    2015-12-01

    Woody encroachment is a pervasive land cover change throughout the tropics and subtropics. Encroachment is frequently catalyzed by nitrogen (N)-fixing trees and the resulting N inputs potentially alter whole-ecosystem N cycling, accumulation and loss. In the southern US, widespread encroachment by legume Prosopis glandulosa is associated with increased soil total N storage, inorganic N concentrations, and net mineralization and nitrification rates. To better understand the effects of this process on ecosystem N cycling, we investigated patterns of symbiotic N fixation, N accrual and soil N trace gas and N2 emissions during Prosopis encroachment into the southern Rio Grande Plains. Analyses of d15N in foliage, xylem sap and plant-available soil N suggested that N fixation rates increase with tree age and are influenced by abiotic conditions. A model of soil N accrual around individual trees, accounting for atmospheric inputs and gas losses, generates lifetimes N fixation estimates of up to 9 kg for a 100-year-old tree and current rates of 7 kg N ha-1 yr-1. However, these N inputs and increased soil cycling rates do not translate into increased N gas losses. Two years of field measurements of a complete suite of N trace gases (ammonia, nitrous oxide, nitric oxide and other oxidized N compounds) found no difference in flux between upland Prosopis groves and adjacent unencroached grasslands. Total emissions for both land cover types average 0.56-0.65 kg N ha-1 yr-1, comparable to other southern US grasslands. Additional lab experiments suggested that N2 losses are low and that field oxygen conditions are not usually conducive to denitrification. Taken together, results suggest that this ecosystem is currently experiencing a period of net N accrual under ongoing encroachment.

  16. Effect of oxygen on the internal corrosion of natural gas pipelines

    SciTech Connect

    Durr, C.L.; Beavers, J.A.

    1996-08-01

    Internal corrosion is a problem in wet natural gas gathering lines. Literature on the subject suggests that dissolved oxygen (O{sub 2}) is one of the more corrosive contaminants in natural gas. Immersion tests, funded by a major gas transmission company, were performed on C1018 (UNS G10180) specimens to assess the influence of O{sub 2} concentration on the internal corrosion of the wet gathering system in their storage field. Twenty-eight day tests were performed in a flow-through (gas phase only) autoclave at 70 F (21 C) and 1,200 psi (8,274 kPa) with simulated natural gas mixtures containing 10, 100, 500 and 1,000 ppm (by volume) O{sub 2}. Specimens were exposed to the vapor, vapor/liquid (V/L) interface, and liquid phases of pure water and saltwater in these tests. The highest corrosion rate, based on groove depth, was measured for the V/L specimens in pure water with 1,000 ppm O{sub 2}. Corrosion rates, based on weight loss, generally maximized at an O{sub 2} concentration of 100 ppm.

  17. Energy Balance Around Gas Injection into Oxygen Steelmaking

    NASA Astrophysics Data System (ADS)

    Sabah, Shabnam; Brooks, Geoffrey

    2016-02-01

    In the present work, a simplified approach of energy balance around gas injection into oxygen steelmaking has been carried out in a cold model. The aim is to provide an estimation of the amount of energy consumed by the different parts of the injection process such as dissipation, stirring of the bath, cavity formation, and splashing. Calculation of jet power used by different processes has been carried for various operating conditions and cavity modes ( i.e., splashing and penetrating). Calculations showed that dissipation and splashing are the dominant processes where most of the power of the jet is used, whereas cavity formation consumes the least amount. In the splashing mode, the percentage of total input power going into dissipation was about 59 to 63 pct, whereas it was found to be 2.6 to 50 pct in the penetrating mode. In splashing mode, about 30 pct power from the nozzle was used to create splash which is proved to be an efficient mode for droplet generation as less power is required to create droplets. At a certain lance height, the percentages of total input power used for splashing and dissipation were found equal. Below this lance height, all the cavities were found to be in penetrating mode. This simplified approach provides an improved understanding of the gas injection process and may be used for developing models of the injection process of steelmaking.

  18. Oxidation of diamond films by atomic oxygen: High resolution electron energy loss spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Shpilman, Z.; Gouzman, I.; Grossman, E.; Akhvlediani, R.; Hoffman, A.

    2007-12-01

    Diamond surface oxidation by atomic oxygen, annealing up to ˜700°C, and in situ exposure to thermally activated hydrogen were studied by high resolution electron energy loss spectroscopy (HREELS). After atomic oxygen (AO) exposure, HREELS revealed peaks associated with CHx groups, carbonyl, ether, and peroxide-type species and strong quenching of the diamond optical phonon and its overtones. Upon annealing of the oxidized surfaces, the diamond optical phonon overtones at 300 and 450meV emerge and carbonyl and peroxide species gradually desorb. The diamond surface was not completely regenerated after annealing to ˜700°C and in situ exposure to thermally activated hydrogen, probably due to the irreversible deterioration of the surface by AO.

  19. Health safe alarm evaluation. Final report. [Combustible gas/oxygen deficiency

    SciTech Connect

    Hossain, M.A.; Bishop, E.C.

    1981-12-01

    The USAF Occupational and Environmental Health Laboratory (USAF OEHL) conducted an evaluation of the National Mine Service Company, Model MX 241, Combination Combustible Gas/Oxygen Deficiency Alarm. The evaluation included determination of linearity of response to a calibration gas (hexane) and the instrument's ability to set the %LEL alarm at or below 5% LEL and oxygen alarm at or below 19.5% oxygen. Recommendation of the MX 241 for specific application was made based upon the evaluation results.

  20. A system using solid ceramic oxygen electrolyte cells to measure oxygen fugacities in gas-mixing systems

    NASA Technical Reports Server (NTRS)

    Williams, R. J.; Mullins, O.

    1976-01-01

    Details are given for the construction and operation of a 101.3 kN/sq m (1 atmosphere) redox control system. A solid ceramic oxygen electrolyte cell is used to monitor the oxygen fugacity in the furnace. The system consists of a vertical quench, gas mixing furnace with heads designed for mounting the electrolyte cell and with facilities for inserting and removing the samples. The system also contains the high input impedance electronics necessary for measurements, a simplified version of a gas mixing apparatus, and devices for experiments under controlled rates of change relative to temperature and redox state. The calibration and maintenance of the system are discussed.

  1. JSC systems using solid ceramic oxygen electrolyte cells to measure oxygen fugacites in gas-mixing systems

    NASA Technical Reports Server (NTRS)

    Williams, R. J.; Mullins, O.

    1981-01-01

    Details are given for the construction and operation of a 101.3 KN/sq meter (1 atmosphere) redox control system. A solid ceramic oxygen electrolyte cell is used to monitor the oxygen fugacity in the furnace. The system consists of a vertical quench gas mixing furnace with heads designed for mounting the electrolyte cell and with facilities for inserting and removing the samples, a simplified version of a gas mixing apparatus, and devices for experiments under controlled rates of change of temperature. A thermogravimetric analysis system employing these techniques of redox control and measurement is also described. The calibration and maintenance of the system are discussed.

  2. Oxygen Isotopic Fractionation During Evaporation of SiO2 in Vacuum and in H Gas

    NASA Astrophysics Data System (ADS)

    Nagahara, H.; Young, E. D.; Hoering, T. C.; Mysen, B. O.

    1993-07-01

    isotope measurements, including ^17O and silicon isotope measurements, are now in progress, and some of the results are shown in this paper. Oxygen isotopic compositions of residues in vacuum and in hydrogen gas of total pressure of 2.6 x 10^-5 bar, which approximates the pressure of the solar nebula at the midplane at 2-3 AU, are shown in comparison with evaporation rate (Figs. 1 and 2). Oxygen isotopic fractionation is remarkable in a constant evacuation, but is negligible in hydrogen gas of 2.6 x 10^-5 bar total pressure. In vacuum, delta ^18O of solid residue increases with increasing degree of evaporation. The curve is best fit to delta ^18O = 0.00094x^2 + 0.00173x + 19.606 (r = 0.997), where x is the degree of evaporation in weight percent. The curve is fit to the Rayleigh fractionation curve with a constant fractionation factor (alpha(sub)vap-sol) of 0.9970. Figures 1 and 2 show that evaporation is significant but oxygen isotopic fractionation is insignificant in hydrogen gas in the approximate solar nebular condition. The high evaporation rate in hydrogen gas is due to the fact that evaporation is a decomposition reaction of an oxide, which should be accelerated in reducing condition. The rate, however, can be explained by an unknown diffusion process that is possible when hydrogen is reactive with silica [2]. In a fairly high hydrogen pressure, isotopic fractionation is suppressed. On the other hand, in vacuum, the evaporation rate is small but the degree of isotopic fractionation is significant. The results suggest that chondrules and CAIs without isotopic mass fractionation could have been formed in the solar nebula, but that mass loss during heating should have been significant. The CAIs with significant mass fractionation such as HAL could have been formed in vacuum. References: [1] Davis A. et al. (1990) Nature, 347, 655-658. [2] Nagahara H. (1993) LPS XXIV, 1045-1046. Fig. 1, which appears here in the hard copy, shows the evaporation rate of SiO2 heated at

  3. Mass loss of shuttle space suit orthofabric under simulated ionospheric atomic oxygen bombardment

    NASA Technical Reports Server (NTRS)

    Miller, W. L.

    1985-01-01

    Many polymeric materials used for thermal protection and insulation on spacecraft degrade significantly under prolonged bombardment by ionospheric atomic oxygen. The covering fabric of the multilayered shuttle space suit is composed of a loose weave of GORE-TEX fibers, Nomex and Kevlar-29, which are all polymeric materials. The complete evaluation of suit fabric degradation from ionospheric atomic oxygen is of importance in reevaluating suit lifetime and inspection procedures. The mass loss and visible physical changes of each test sample was determined. Kapton control samples and data from previous asher and flight tests were used to scale the results to reflect ionospheric conditions at about 220 km altitude. It is predicted that the orthofabric loses mass in the ionosphere at a rate of about 66% of the original orthofabric mass/yr. The outer layer of the two-layer orthofabric test samples shows few easily visible signs of degradation, even when observed at 440X. It is concluded that the orthofabric could suffer significant loss of performance after much less than a year of total exposure time, while the degradation might be undetectable in post flight visual examinations of space suits.

  4. Influence of oxygen concentration in sputtering gas on piezoelectric response of aluminum nitride thin films

    SciTech Connect

    Akiyama, Morito; Kamohara, Toshihiro; Kano, Kazuhiko; Teshigahara, Akihiko; Kawahara, Nobuaki

    2008-07-14

    The authors have investigated the influence of oxygen concentration in sputtering gas on the piezoelectric response of aluminum nitride (AlN) thin films prepared on silicon substrates. The piezoelectric response strongly depends on the oxygen concentration, and changes from +6.8 to -7.0 pC/N with increasing oxygen concentration from 0% to 1.2%. The polar direction drastically inverts from the Al polarity to N polarity. When the oxygen concentration in sputtering gas was 1.2%, the oxygen concentration in the AlN films was 7 at. %. Furthermore, the growth rate of the AlN films gradually decreases with increasing oxygen concentration in sputtering gas.

  5. Water loss and gas exchange by eggs of Manduca sexta: trading off costs and benefits.

    PubMed

    Woods, H Arthur

    2010-05-01

    Like all terrestrial organisms, insect eggs face a tradeoff between exchanging metabolic gases (O(2) and CO(2)) and conserving water. Here I summarize the physiology underlying this tradeoff and the ecological contexts in which it may be important. The ideas are illustrated primarily by work from my laboratory on eggs of the sphingid moth Manduca sexta. In particular, I discuss: (1) dynamic changes in metabolic demand and water loss during development; and (2) how the eggshell layers and embryonic tracheal system control the traffic of gases between the embryo and its environment. Subsequently, I identify three areas with interesting but unresolved issues: (1) what eggs actually experience in their microclimates, focusing particularly on the leaf microclimates relevant to eggs of M. sexta; (2) how egg experience influences whether or not hatchling larvae succeed in establishing feeding sites on host plants; and (3) whether Hetz and Bradley's [Hetz, S.K., Bradley, T.J., 2005. Insects breathe discontinuously to avoid oxygen toxicity. Nature 433, 516-519] oxygen toxicity hypothesis for discontinuous gas-exchange cycles applies to insect eggs. PMID:19573530

  6. Numerical Study of Transmission Loss Through a Slow Gas Layer Adjacent to a Plate

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Beck, Benjamin S.; Slagle, Adam C.

    2013-01-01

    This paper describes a systematic numerical investigation of the sound transmission loss through a multilayer system consisting of a bagged gas and lightweight panel. The goal of the study is to better understand the effect of the gas on transmission loss and determine whether a gas with a slow speed of sound is beneficial for noise control applications. As part of the study, the density and speed of sound of the gas are varied independently to assess the impact of each on transmission loss. Results show that near grazing incidence the plane wave transmission loss through the multilayer system is more sensitive to the speed of sound than the density of the gas. In addition, it was found that a slow wave speed in the bagged gas provides more low-frequency transmission loss benefit than a fast wave speed. At low angles of incidence, close to the plate normal, the benefit is due to the reduction of the characteristic impedance of the gas. At high angles of incidence, the benefit is attributed to the fact that the incident waves at the air/gas interface are bent towards the surface normal. Since transmission loss is angle dependent, refraction in the slow gas layer results in a significant improvement in the transmission loss at high angles of incidence.

  7. Fate of oxygen losses from Typha domingensis (Typhaceae) and Cladium jamaicense (Cyperaceae) and consequences for root metabolism

    USGS Publications Warehouse

    Chabbi, A.; McKee, K.L.; Mendelssohn, I.A.

    2000-01-01

    The objective of this work was to determine whether radial oxygen loss (ROL) from roots of Typha domingensis and Cladium jamaicense creates an internal oxygen deficiency or, conversely, indicates adequate internal aeration and leakage of excess oxygen to the rhizosphere. Methylene blue in agar was used to quantify oxygen leakage. Typha's roots had a higher porosity than Cladium's and responded to flooding treatment by increasing cortical air space, particularly near the root tips. A greater oxygen release, which occurred along the subapical root axis, and an increase in rhizosphere redox potential (Eh) over time were associated with the well-developed aerenchyma system in Typha. Typha roots, regardless of oxygen release pattern, showed low or undetectable alcohol dehydrogenage (ADH) activity or ethanol concentrations, indicating that ROL did not cause internal deficiencies. Cladium roots also releases oxygen, but this loss primarily occurred at the root tips and was accompanied by increased root ADH activity and ethanol concentrations. These results support the hypothesis that oxygen release by Cladium is accompanied by internal deficiencies of oxygen sufficient to stimulate alcoholic fermentation and helps explain Cladium's lesser flood tolerance in comparison with Typha.

  8. Effect of weight loss on operational lung volumes and oxygen cost of breathing in obese women

    PubMed Central

    Bhammar, Dharini M.; Stickford, Jonathon L.; Bernhardt, Vipa; Babb, Tony G.

    2015-01-01

    Background The effect of moderate weight loss on operational lung volumes during exercise and the oxygen (O2) cost of breathing are unknown in obese women but could have important implications regarding exercise endurance. Methods In twenty-nine obese women (33 ± 8yr, 97 ± 14kg, BMI: 36 ± 4, body fat: 45.6 ± 4.5%; means ± SD), body composition, fat distribution (by MRI), pulmonary function, operational lung volumes during exercise, and the O2 cost of breathing during eucapnic voluntary hyperpnea ( V˙O2 vs. V˙E slope) were studied before and after a 12-week diet and resistance exercise weight loss program. Results Participants lost 7.5 ± 3.1kg or ≈8% of body weight (p < 0.001), but fat distribution remained unchanged. After weight loss, lung volume subdivisions at rest were increased (p < 0.05) and were moderately associated (p < 0.05) with changes in weight. End-expiratory lung volume (%Total Lung Capacity) increased at rest and during constant load exercise (p < 0.05). O2 cost of breathing was reduced by 16% (2.52 ± 1.02 to 2.11 ± 0.72ml/L; P=0.003). As a result, O2 uptake of the respiratory muscles (V˙O2Resp), estimated as the product of O2 cost of breathing and exercise V˙E during cycling at 60W, was significantly reduced by 27 ± 31ml (P<0.001), accounting for 46% of the reduction in total body V˙O2 during cycling at 60W. Conclusions Moderate weight loss yields important improvements in respiratory function at rest and during submaximal exercise in otherwise healthy obese women. These changes in breathing load could have positive effects on the exercise endurance and adherence to physical activity. PMID:26869243

  9. Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield

    SciTech Connect

    Vagin, Nikolai P; Ionin, Andrei A; Klimachev, Yu M; Kotkov, A A; Podmar'kov, Yu P; Seleznev, L V; Sinitsyn, D V; Frolov, M P; Yuryshev, Nikolai N; Kochetov, Igor' V; Napartovich, A P; Hager, G D

    2004-09-30

    The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume ({approx}18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts ({approx}1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving {approx}6.5 kJ L{sup -1} atm{sup -1} per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O{sub 2} : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O{sub 2}(a{sup 1{Delta}}{sub g}) and O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O{sub 2}(a{sup 1{Delta}}{sub g}) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value {approx}3% for W {approx} 1.0 kJ L{sup -1} atm{sup -1} is in agreement with the theoretical estimate. Theoretical calculations performed for W {approx} 6.5 kJ L{sup -1} atm{sup -1} at a fixed temperature show that the singlet-oxygen yield may be {approx}20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)

  10. Hyperbaric oxygen therapy as salvage treatment for sudden sensorineural hearing loss: a prospective controlled study.

    PubMed

    Pezzoli, M; Magnano, M; Maffi, L; Pezzoli, L; Marcato, P; Orione, M; Cupi, D; Bongioannini, G

    2015-07-01

    The most commonly used treatment for sensorineural sudden hearing loss (SSHL) in clinical practice is the administration of steroids; however, a favorable result is not always obtained. We studied 58 patients who failed to recover after primary treatment with IV steroids, 44 of these met our inclusion criteria (mean age 50.7, 27 males, range 30-74). We treated 23 patients (mean age 47.3, 16 males, age range 22-74) with hyperbaric oxygen therapy (HBO) (2.5 ATA for 60 min for 15 treatments), while 21 (mean age 54.5, 11 males, age range 22-71) patients refused to be treated and served as a non-randomized control group. Patients treated with HBO had a mean improvement of 15.6 dB (SD ± 15.3), with 1 of them completely healed, 5 with a good recovery, 10 with a fair recovery and 7 unchanged. Patients who were not treated had a spontaneous mean improvement of 5.0 dB (SD ± 11.4) with 3 patients with a good recovery, 1 patient with a fair recovery and 17 patients unchanged. Mean improvement was significantly better in patients treated with HBO compared to controls (p = 0.0133). Patients with worst hearing had the greater degree of improvement whether or not they were treated in the first 10 days after the onset of the hearing loss or between 11 and 30 days. In conclusion, hyperbaric oxygen therapy can lead to significant improvement of pure tone hearing thresholds in patients with SSHL who failed primary corticosteroid treatment and are within 4 weeks of the onset of deafness. PMID:25318685

  11. Quantitative imaging of radial oxygen loss from Valisneria spiralis roots with a fluorescent planar optode.

    PubMed

    Han, Chao; Ren, Jinghua; Tang, Hao; Xu, Di; Xie, Xianchuan

    2016-11-01

    Oxygen (O2) availability within the sediment-root interface is critical to the survival of macrophytes in O2-deficient sediment; however, our knowledge of the fine-scale impact of macrophyte roots upon the spatiotemporal dynamics of O2 is relatively limited. In this study, a non-invasive imaging technology was utilized to map O2 micro-distribution around Vallisneria spiralis. Long-term imaging results gathered during a 36day-period revealed an abundance of O2 spatiotemporal patterns ranging from 0 to 250μmolL(-1). The root-induced O2 leakage and consequent oxygenated area were stronger in the vicinity of the basal root compared to that found in the root tip. The O2 images revealed V. spiralis exhibited radial O2 loss (ROL) along the entire root, and the O2 distribution along the root length showed a high degree of small-scale spatial heterogeneity decreasing from 80% at the basal root surface to 10% at the root tip. The oxygenated zone area around the roots increased as O2 levels increased with root growth and irradiance intensities ranging from 0 to 216μmol photons m(-2)s(-1). A weak ROL measuring <20% air saturation around the basal root surface was maintained in darkness, which was presumably attributed to the O2 supply from overlying water via plant aerenchyma. The estimated total O2 release to the rhizosphere of V. spiralis was determined to range from 8.80±7.32 to 30.34±17.71nmolm(-2)s(-1), which is much higher than many other macrophyte species. This O2 release may be an important contribution to the high-capacity of V. spiralis for quickly colonizing anaerobic sediment. PMID:27387799

  12. Control of oxygen vacancies and their kinetic behaviours via reversible oxygen loss in BiFeO3 ceramics

    NASA Astrophysics Data System (ADS)

    Min, Kangli; Huang, Fengzhen; Jin, Yaming; Lu, Xiaomei; Wu, Huarui; Zhu, Jinsong

    2015-11-01

    Oxygen vacancies and their kinetic behaviours were systematically investigated in quenched BiFeO3 ceramics. Complex relaxation processes were observed and discussed based on the migration of V\\text{o}+ , V\\text{o}2+ and the transition in between them, where V\\text{o}+ , V\\text{o}2+ represent the oxygen vacancies with single and two positive charges, respectively. It is found that an oxygen-deficient environment promotes the transformation from V\\text{o}+ to V\\text{o}2+ , while oxygen treatment can reverse such a transformation. This work provides a feasible alternative method to modulate oxygen vacancies and their migration in favour of the applications of BiFeO3.

  13. Severe blood loss anemia in a Jehovah's Witness treated with adjunctive hyperbaric oxygen therapy.

    PubMed

    Graffeo, Charles; Dishong, William

    2013-04-01

    We describe the case of a 39-year-old African-American woman who developed sudden onset, near-term placental abruption with severe blood loss anemia whose religious beliefs precluded her from receiving any blood products. The patient had lost most of her blood volume, with a reported hemoglobin level of 1.9 g/dL, developed multisystem failure, and disseminated intravascular coagulation with bilateral deep venous thrombosis. Adjunctive hyperbaric oxygenation (HBO) therapy was considered, and the patient was referred for treatment. The patient required ventilatory support as well as vasopressors and hemodialysis. HBO therapy occured in a monoplace chamber setting at 2.0 atmospheres absolute for 90 minutes per treatment up to twice daily depending on patients clinical status. The patient underwent a total of 30 HBO treatments and had sustained improvement in all hemodynamic parameters, red blood cell volume, renal and respiratory function. She was discharged to a rehabilitation facility on hospital day 29 and then to home, soon thereafter. The patient had no evidence of sustained physical or cognitive impairment at time of discharge, and there were no reported complications associated with HBO therapy. Adjunctive HBO therapy should be considered in the management of patients with exceptional severe blood loss anemia who refuse the use of blood products. PMID:23380087

  14. Gas loss in simulated galaxies as they fall into clusters

    PubMed Central

    Cen, Renyue; Pop, Ana Roxana; Bahcall, Neta A.

    2014-01-01

    We use high-resolution cosmological hydrodynamic galaxy formation simulations to gain insights into how galaxies lose their cold gas at low redshift as they migrate from the field to the high-density regions of clusters of galaxies. We find that beyond three cluster virial radii, the fraction of gas-rich galaxies is constant, representing the field. Within three cluster-centric radii, the fraction of gas-rich galaxies declines steadily with decreasing radius, reaching <10% near the cluster center. Our results suggest galaxies start to feel the effect of the cluster environment on their gas content well beyond the cluster virial radius. We show that almost all gas-rich galaxies at the cluster virial radius are falling in for the first time at nearly radial orbits. Furthermore, we find that almost no galaxy moving outward at the cluster virial radius is gas-rich (with a gas-to-baryon ratio greater than 1%). These results suggest that galaxies that fall into clusters lose their cold gas within a single radial round-trip. PMID:24843167

  15. Gas loss in simulated galaxies as they fall into clusters.

    PubMed

    Cen, Renyue; Pop, Ana Roxana; Bahcall, Neta A

    2014-06-01

    We use high-resolution cosmological hydrodynamic galaxy formation simulations to gain insights into how galaxies lose their cold gas at low redshift as they migrate from the field to the high-density regions of clusters of galaxies. We find that beyond three cluster virial radii, the fraction of gas-rich galaxies is constant, representing the field. Within three cluster-centric radii, the fraction of gas-rich galaxies declines steadily with decreasing radius, reaching <10% near the cluster center. Our results suggest galaxies start to feel the effect of the cluster environment on their gas content well beyond the cluster virial radius. We show that almost all gas-rich galaxies at the cluster virial radius are falling in for the first time at nearly radial orbits. Furthermore, we find that almost no galaxy moving outward at the cluster virial radius is gas-rich (with a gas-to-baryon ratio greater than 1%). These results suggest that galaxies that fall into clusters lose their cold gas within a single radial round-trip. PMID:24843167

  16. Nitrogen Loss Processes and Nitrous Oxide Turnover in Oceanic Oxygen Minimum Zones

    NASA Astrophysics Data System (ADS)

    Ward, B. B.

    2014-12-01

    Nitrogen is an essential element for life and the maintenance of all ecosystems. For many ecosystems, both aquatic and terrestrial, nitrogen is the element most likely to limit the amount and rate of production. But just as ecosystems can suffer from too little nitrogen, they are also sensitive to too much nitrogen, which leads to eutrophication and structural changes in food webs. Thus the processes by which nitrogen is removed are as critical to our understanding of ecosystem function as are those by which it is added. Nitrogen loss processes in the open ocean have been the focus of research and discovery in recent years. Long thought to be dominated by the bacterial respiratory process of denitrification, N loss is now also known to occur by anaerobic ammonium oxidation (anammox). We now understand that the ratio of the two processes is controlled by the quality and quantity of organic matter supplied to the anoxic waters of the ocean's major oxygen deficient zones. Coastal environments are also major sites of N loss but excess N loading from land often ameliorates the direct dependence of anammox and denitrification on organic matter composition. The ratio is important partly because of side products: Denitrification is a significant source and sink for nitrous oxide (N2O), while anammox has no significant contribution to N2O biogeochemistry. With the anthropogenic flux of CFCs at least mostly under control, N2O emissions to the atmosphere are the greatest contribution to ozone destruction, and they also contribute to greenhouse warming. Both anthropogenic and natural sources contribute to N2O emissions, and natural sources are sensitive to anthropogenic forcing. Our direct measurements of N2O production and consumption in the ocean agree with modeling results that have implicated multiple microbial processes and complex physical and biological control of N2O fluxes in the ocean.

  17. Breathing 100 percent oxygen compared with 50 percent oxygen:50 percent nitrogen reduces altitude-induced venous gas emboli

    NASA Technical Reports Server (NTRS)

    Webb, James T.; Pilmanis, Andrew A.

    1993-01-01

    The study investigates effects of 40 zero-prebreathe decompressions of male subjects to 8.3-6.8 psia for 6 h while they were breathing 100 percent oxygen and performing moderate exercise. No decompression sickness (DCS) symptoms were observed. Severe venous gas emboli (VGE) were not detected at 8.3 psia, but were present during 10, 20, and 40 percent of the exposures at 7.8, 7.3, and 6.8 psia, respectively. Zero-prebreathe decompression while breathing 100 percent oxygen results in significantly lower VGE and DCS risk levels than while breathing a 50:50 mix. It is shown that 7.3 psia EVA pressure suits with 100 percent oxygen should be safer than 8.3 psia suits with a 50:50 mix.

  18. Performance of a Small Gas Generator Using Liquid Hydrogen and Liquid Oxygen

    NASA Technical Reports Server (NTRS)

    Acker, Loren W.; Fenn, David B.; Dietrich, Marshall W.

    1961-01-01

    The performance and operating problems of a small hot-gas generator burning liquid hydrogen with liquid oxygen are presented. Two methods of ignition are discussed. Injector and combustion chamber design details based on rocket design criteria are also given. A carefully fabricated showerhead injector of simple design provided a gas generator that yielded combustion efficiencies of 93 and 96 percent.

  19. GAS PHASE SELECTIVE PHOTOXIDATION OF ALCOHOLS USING LIGHT-ACTIVATED TITANIUM DIOXIDE AND MOLECULAR OXYGEN

    EPA Science Inventory

    Gas Phase Selective Oxidation of Alcohols Using Light-Activated Titanium Dioxide and Molecular Oxygen

    Gas phase selective oxidations of various primary and secondary alcohols are studied in an indigenously built stainless steel up-flow photochemical reactor using ultravi...

  20. Dependence of the boiler flue gas losses on humidity of wood biomass

    NASA Astrophysics Data System (ADS)

    Dzurenda, Ladislav; Banski, Adrián

    2015-12-01

    The paper analyzes the influence of humidity of combusted wood biomass on the flue gas losses. A mathematical relation between flue gas losses of the boiler on wood biomass humidity is presented as well as temperature of flue gas emitted from the boiler into the atmosphere. The limits of model application for the humidity of wood biomass falls into the interval 10-60% whereas the range of temperatures of flue gases emitted from the boiler to the atmosphere is 120-200 °C. The influence of the humidity of wood biomass has an adverse effect on increasing the extent of the boiler flue gas losses and thus inefficiency of the heat production. The increase of the wood biomass humidity from the value of 10% to 60% with the outlet temperature of flue gases from the boiler 120 °C causes an increase in flue gas loss of the boiler from the value 8.37% to 12.43%, similarly the increase of flue gas loss by 200 °C from 15.19% to 22.55%, or the increase of the flue gas loss by 7.36%.

  1. Abiotic gas formation drives nitrogen loss from a desert ecosystem.

    PubMed

    McCalley, Carmody K; Sparks, Jed P

    2009-11-01

    In arid environments such as deserts, nitrogen is often the most limiting nutrient for biological activity. The majority of the ecosystem nitrogen flux is typically thought to be driven by production and loss of reactive nitrogen species by microorganisms in the soil. We found that high soil-surface temperatures (greater than 50 degrees C), driven by solar radiation, are the primary cause of nitrogen loss in Mojave Desert soils. This abiotic pathway not only enables the balancing of arid ecosystem nitrogen budgets, but also changes our view of global nitrogen cycling and the predicted impact of climate change and increased temperatures on nitrogen bioavailability. PMID:19892980

  2. New instrumentation for optical measuring of oxygen in gas or dissolved in liquids

    NASA Astrophysics Data System (ADS)

    Trettnak, W.; Gruber, W.; Reininger, F.; O'Leary, P.; Klimant, I.

    The optical oxygen sensor is a novel device for the determination of oxygen in gases or dissolved in liquids. It is based on the measurement principle of fluorescence quenching, which is completely different from that of polarographic oxygen sensors (today the most widespread devices for oxygen detection). The new instrument offers features and advantages, which render it not only a realistic alternative, but, for specific applications, make it superior to existing electrochemical methods. The system is based on low-cost semiconductor devices (light-emitting diodes, photodiodes, low-cost analogue and digital components) and new LED-compatible oxygen-sensitive membranes. The flow cell of the instrument may be thermostatted and the sensor can be calibrated by a simple two-point calibration procedure. The optical oxygen sensor is particularly suitable for measuring dissolved oxygen in respirometry, since no oxygen is consumed by the device and the signal is independent of sample flowrate or stirring speed. Typical fields of application are monitoring of oxygen in ground and drinking water, in process controll in bioreactors and in breath gas and blood gas analysis.

  3. Singlet Oxygen Generation on Porous Superhydrophobic Surfaces: Effect of Gas Flow and Sensitizer Wetting on Trapping Efficiency

    PubMed Central

    2015-01-01

    We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon–phthalocyanine (Pc) particles are immobilized. Singlet oxygen (1O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV–vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid–gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices. PMID:24885074

  4. Do arbuscular mycorrhizal fungi affect arsenic accumulation and speciation in rice with different radial oxygen loss?

    PubMed

    Li, H; Man, Y B; Ye, Z H; Wu, C; Wu, S C; Wong, M H

    2013-11-15

    The effects of arbuscular mycorrhizal fungi (AMF) on the temporal variation of arsenic (As) speciation and accumulation in two paddy rice cultivars (TD 71 and Xiushui 11) with different degrees of radial oxygen loss (ROL) at three growth periods (day 7, day 35, day 63 after flooding the soil) were investigated in soil, spiked with and without 30 mg As kg(-1). The results showed that TD 71 with high ROL colonized by Glomus intraradices led to higher root colonization rates than Xiushui 11 at three growth periods, both in soil with or without 30 mg As kg(-1) (p<0.05). Mycorrhizal inoculation led to elevated (p<0.05) root ratios of arsenite (As(III)) conc./arsenate (As(V)) conc. (concentration) in TD 71 with high ROL at three growth periods in As contaminated flooding soils. Furthermore, the ratios of As(III) conc./As(V) conc. in roots of TD71 were significantly more than Xiushui 11 when colonized by AMF at three growth periods in 30 mg As kg(-1) soil (p<0.05). Therefore, rice with high ROL can favor AM fungal infection and enhance root ratio of As(III) conc./As(V) conc. in the presence of AMF. PMID:22673057

  5. Concurrent hyperbaric oxygen therapy and intratympanic steroid application as salvage therapy after severe sudden sensorineural hearing loss.

    PubMed

    Lamm, Hans; Müller-Kortkamp, Claus; Warnecke, Athanasia; Pohl, Friederike; Paasche, Gerrit; Lenarz, Thomas; Stolle, Stefan R O

    2016-03-01

    Concurrent hyperbaric oxygen therapy (HBOT) and intratympanic steroid application (ITS) are beneficial as salvage therapy for therapy-refractory sudden sensorineural hearing loss (SSNHL). The findings encourage further research on the treatment of noise-induced and idiopathic SSNHL with concurrent use of HBOT and ITS respecting also patients with long-term or therapy-refractory SSNHL. PMID:27014454

  6. Comparison of two different steroid treatments with hyperbaric oxygen for idiopathic sudden sensorineural hearing loss.

    PubMed

    Sevil, Ergun; Bercin, Sami; Muderris, Togay; Gul, Fatih; Kiris, Muzaffer

    2016-09-01

    The purpose of the study was to assess the efficacy of the association of intratympanic (IT) steroid and hyperbaric oxygen (HBO) therapy in patients presenting with idiopathic sudden sensorineural hearing loss (ISSNHL), and to compare this protocol with another consisting of intravenous (IV) steroid administration and HBO therapy. A total of 80 patients diagnosed with ISSNHL were included in this prospective trial. Patients were divided into three categories: a mild-to-moderate ISSNHL group with a pure-tone average (PTA) ≤60 decibels (dB), a severe ISSNHL group with a PTA of 60-80 dB, and a profound ISSNHL group with a PTA ≥81 dB. The first protocol consisted of 20 sessions of HBO therapy together with IV methylprednisolone 1 mg/kg body weight and a 10 mg taper every 3 days for 10 days. The second protocol consisted of HBO therapy for 20 sessions, together with an IT injection of dexamethasone at a dose of 4 mg/mL, 0.5-0.7 mL once a day for 7 consecutive days, performed 3 h before the HBO therapy. In the mild-to-moderate ISSNHL patients, the mean hearing gain and successful treatment rate was 19 (0-27) dB and 78.9 %, respectively in the IT + HBO treatment group, and 18 (3-44) dB and 70.5 % in the IV + HBO therapy group. In the severe ISSNHL patients, the mean hearing gain and successful treatment rate was 33 (1-54) dB and 81.8 %, respectively in the IT + HBO treatment group and 33.5 (7-57) dB and 58.2 % in the IV + HBO group. In the profound ISSNHL patients, the mean hearing gain and successful treatment rate was 36 (4-69) dB and 40 %, respectively in the IT + HBO therapy group, and 39.5 (0-92) dB and 72.7 % in the IV + HBO treatment group. The results demonstrated that patients with severe hearing loss success rate was superior in the group submitted to IT + HBO treatment, conversely IV + HBO therapy may be benefit for patients with profound hearing loss. Nevertheless, these clinical results were not statistically significant

  7. Investigation on the reaction mechanisms of generation and loss of oxygen-related species in atmospheric-pressure pulsed dielectric barrier discharge in argon/oxygen mixture

    NASA Astrophysics Data System (ADS)

    Pan, Jie; Tan, Zhenyu; Pan, Guangsheng; Shan, Chunhong; Wang, Xiaolong; Liu, Yadi; Jiang, Jixiang

    2016-07-01

    This work presents a numerical investigation, using a 1-D fluid model, on the generation and loss of oxygen-related species and the spatial-temporal evolutions of the species densities in the atmospheric-pressure pulsed dielectric barrier discharge in the argon/oxygen mixture. The reaction pathways as well as their contributions to the generation and loss of oxygen-related species are given. The considered oxygen-related species include O, O(1D), O2(1Δg), O3, O+, O2+, O-, O2-, and O3-. The following significant results are obtained. O, O(1D), O2(1Δg), and O- are produced mainly via the electron impact with O2. Ar+ plays an essential role in the generation of O+ and O2+. Almost all of O3 derives from the reaction O2 + O2 + O → O3 + O2. The O3-related reactions produce an essential proportion of O2- and O3-. The substantial loss of O-, O2-, and O3- is induced by their reactions with O2+. Loss of O+, O, and O(1D) is mainly due to their reactions with O2, loss of O2(1Δg) due to O2(1Δg) impacts with O3 as well as the de-excitation reactions between O2(1Δg) and e, O2, and O, and loss of O3 due to the reactions between O3 and other neutral species. In addition, the densities of O+ and O(1D) present two obvious peaks at the pulse duration, but the densities of O2+, O, O2(1Δg), and O3 are almost unchanged. The densities of negative oxygen ions increase at the pulse duration and then decline. O- density is obviously large nearby the dielectric surfaces and the densities of O2- and O3- present generally uniform distributions.

  8. Method to prevent recession loss of silica and silicon-containing materials in combustion gas environments

    DOEpatents

    Brun, Milivoj Konstantin; Luthra, Krishan Lal

    2003-01-01

    While silicon-containing ceramics or ceramic composites are prone to material loss in combustion gas environments, this invention introduces a method to prevent or greatly reduce the thickness loss by injecting directly an effective amount, generally in the part per million level, of silicon or silicon-containing compounds into the combustion gases.

  9. Investigation on Carbon-Deposition Behavior from Heating Cycle Gas in Oxygen Blast Furnace Process

    NASA Astrophysics Data System (ADS)

    Liu, Jinzhou; Wang, Jingsong; She, Xuefeng; Zhang, Shiyang; Xue, Qingguo

    2015-02-01

    Among the different ways to study carbon deposition in the ironmaking process, not much attention was paid to that of heating the gas mixture, especially cycle gas in an oxygen blast furnace. In this work, the carbon-deposition characteristics of heating 100 pct CO, CO-H2 gas mixture, and cycle gas in the oxygen blast furnace process were, respectively, experimentally and theoretically investigated. First, the thermodynamics on carbon-deposition reactions were calculated. Then, the impacts of discharging operation temperature, the proportion of CO/H2 in heating the CO-H2 gas mixture, and the CO2 concentration in heating the cycle gas of an oxygen blast furnace on the carbon deposition were tested and investigated. Furthermore, the carbon-deposition behaviors in heating the CO-H2 gas mixture were compared with the thermodynamic calculation results for discussing the role of H2. In addition, carbon deposition in heating cycle gas includes CO decomposition and a carbon-deposition reaction by hybrid of CO and H2; the possible roles of each were analyzed by comparing thermodynamic calculation and experimental results. The deposited carbon was characterized by scanning electron microscope (SEM) to analyze the deposited carbon microstructure.

  10. Ta and Ti Anti-passivation Interlayers for Oxygen-Evolving Anodes Produced by Cold Gas Spray

    NASA Astrophysics Data System (ADS)

    Piercy, B.; Allen, C.; Gullá, A. F.

    2015-04-01

    Conventional electrodes for electrochemical oxygen evolution (OER) comprise titanium substrate, an anti-passivation interlayer, and a mixed metal oxide catalyst layer. We report the use of cold gas spray to deposit titanium and tantalum anti-passivation interlayers, directly on titanium, for OER applications. Accelerated electrochemical life tests show that 100% tantalum interlayers exceeded the performance of commercial state-of-the-art electrodes. Microscopy reveals that electrode failure, in the case of 100% tantalum interlayers, is primarily due to catalyst loss; in contrast, the typical failure mode for conventional electrodes of this type is passivation of the titanium substrate. These results highlight the effectiveness of cold gas spray tantalum for extending electrode lifetimes while maximizing catalyst utilization.

  11. Direct method gas-phase oxygen abundances of four Lyman break analogs

    SciTech Connect

    Brown, Jonathan S.; Croxall, Kevin V.; Pogge, Richard W.

    2014-09-10

    We measure the gas-phase oxygen abundances in four Lyman break analogs using auroral emission lines to derive direct abundances. The direct method oxygen abundances of these objects are generally consistent with the empirically derived strong-line method values, confirming that these objects are low oxygen abundance outliers from the mass-metallicity (MZ) relation defined by star forming Sloan Digital Sky Survey galaxies. We find slightly anomalous excitation conditions (Wolf-Rayet features) that could potentially bias the empirical estimates toward high values if caution is not exercised in the selection of the strong-line calibration. The high rate of star formation and low oxygen abundance of these objects is consistent with the predictions of the fundamental metallicity relation, in which the infall of relatively unenriched gas simultaneously triggers an episode of star formation and dilutes the interstellar medium of the host galaxy.

  12. Intradiscal injection of oxygen-ozone gas mixture for the treatment of cervical disc herniations.

    PubMed

    Alexandre, A; Corò, L; Azuelos, A; Buric, J; Salgado, H; Murga, M; Marin, F; Giocoli, H

    2005-01-01

    For disc herniations the use of open surgical approaches is reduced since new percutaneous methods allowing shrinkage of the disc and improvement of the radicular function are gaining interest. Studies on the spontaneous disappearance of disc fragments have demonstrated autoimmune responses with a chronic inflammatory reaction. Also radicular pain has been shown to be mostly due to biochemical mechanisms. Researchers in different fields surprisingly noticed that a brief, calculated, oxidative stress by ozone administration may correct a persistent imbalance due to excessive, chronic oxidative injury. Oxygen-ozone gas injection in painful patients has a dramatic effect on clinical symptoms. On these bases the intradiscal injection of oxygen-ozone gas has been conceived. We report the treatment on a series of patients affected by cervical disc pathology, treated by intradiscal injection of oxygen-ozone gas mixture. The effects both on pain and on radicular dysfunction are impressive. The morphological effect of the treatment was also evaluated by pathological examination. PMID:15830973

  13. Effects of headspace and oxygen level on off-gas emissions from wood pellets in storage.

    PubMed

    Kuang, Xingya; Shankar, Tumuluru Jaya; Sokhansanj, Shahab; Lim, C Jim; Bi, Xiaotao T; Melin, Staffan

    2009-11-01

    Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO(2), CO, and CH(4) from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO(2), CO, and CH(4) in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO(2) and CO were generated at room temperature under lower oxygen levels, whereas CH(4) emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets. PMID:19805393

  14. Effects of Headspace and Oxygen Level on Off-gas Emissions from Wood Pellets in Storage

    SciTech Connect

    Sokhansanj, Shahabaddine; Kuang, Xingya; Shankar, T.S.; Lim, C. Jim; Bi, X.T.; Melin, Staffan

    2009-10-01

    Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO2, CO, and CH4 from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO2, CO, and CH4 in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO2 and CO were generated at room temperature under lower oxygen levels, whereas CH4 emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets.

  15. Analysis of catalytic gas products using electron energy-loss spectroscopy and residual gas analysis for operando transmission electron microscopy.

    PubMed

    Miller, Benjamin K; Crozier, Peter A

    2014-06-01

    Operando transmission electron microscopy (TEM) of catalytic reactions requires that the gas composition inside the TEM be known during the in situ reaction. Two techniques for measuring gas composition inside the environmental TEM are described and compared here. First, electron energy-loss spectroscopy, both in the low-loss and core-loss regions of the spectrum was utilized. The data were quantified using a linear combination of reference spectra from individual gasses to fit a mixture spectrum. Mass spectrometry using a residual gas analyzer was also used to quantify the gas inside the environmental cell. Both electron energy-loss spectroscopy and residual gas analysis were applied simultaneously to a known 50/50 mixture of CO and CO2, so the results from the two techniques could be compared and evaluated. An operando TEM experiment was performed using a Ru catalyst supported on silica spheres and loaded into the TEM on a specially developed porous pellet TEM sample. Both techniques were used to monitor the conversion of CO to CO2 over the catalyst, while simultaneous atomic resolution imaging of the catalyst was performed. PMID:24815065

  16. Effect of three-body loss on itinerant ferromagnetism in an atomic Fermi gas

    SciTech Connect

    Conduit, G. J.; Altman, E.

    2011-04-15

    A recent experiment has provided tentative evidence for itinerant ferromagnetism in an ultracold atomic gas. However, the interpretation of the results is complicated by significant atom losses. We argue that during the loss process the system gradually heats up but remains in local equilibrium.To quantify the consequences of atom loss on the putative ferromagnetic transition we adopt an extended Hertz-Millis theory. The losses damp quantum fluctuations, thus increasing the critical interaction strength needed to induce ferromagnetism and revert the transition from being first order to second order. This effect may resolve a discrepancy between the experiment and previous theoretical predictions. We further illuminate the impact of loss by studying the collective spin excitations in the ferromagnet. Even in the fully polarized state, where loss is completely suppressed, spin waves acquire a decay rate proportional to the three-body loss coefficient.

  17. Polymer growth rate in a wire chamber with oxygen, water, or alcohol gas additives

    NASA Astrophysics Data System (ADS)

    Boyarski, Adam M.

    2009-06-01

    The rate of polymer growth on wires was measured in a wire chamber while the chamber was aged initially with helium:isobutane (80:20) gas, and then with either oxygen, water, or alcohol added to the gas. At the completion of the aging process for each gas mixture, the carbon content on the wires was measured in a scanning electron microscope/energy dispersive X-ray (SEM/EDX) instrument. The same physical wires were used in all the gas mixtures, allowing measurement of polymer build-up or polymer depletion by each gas additive. It is found that the rate of polymer growth is not changed by the presence of oxygen, water, or alcohol. Conjecture that oxygen reduces breakdown by removing polymer deposits on field wires is negated by these measurements. Instead, it appears that the reduced breakdown is due to lower resistance in the polymer from oxygen ions being transported into the polymer. It is also observed that field wires bombarded by the electrons in the SEM and then placed back into the chamber show an abundance of single electrons being emitted, indicating that electron charge is trapped in the polymer layer and that a high electric field is necessary to remove the charge.

  18. Polymer Growth Rate in a Wire Chamber with Oxygen,Water, or Alcohol Gas Additives

    SciTech Connect

    Boyarski, Adam; /SLAC

    2008-07-02

    The rate of polymer growth on wires was measured in a wire chamber while the chamber was aged initially with helium-isobutane (80:20) gas, and then with either oxygen, water, or alcohol added to the gas. At the completion of the aging process for each gas mixture, the carbon content on the wires was measured in a SEM/EDX instrument. The same physical wires were used in all the gas mixtures, allowing measurement of polymer build up or polymer depletion by each gas additive. It is found that the rate of polymer growth is not changed by the presence of oxygen, water or alcohol. Conjecture that oxygen reduces breakdown by removing polymer deposits on field wires is negated by these measurements. Instead, it appears that the reduced breakdown is due to lower resistance in the polymer from oxygen ions being transported into the polymer. It is also observed that field wires bombarded by the electrons in the SEM and then placed back into the chamber show an abundance of single electrons being emitted, indicating that electron charge is stored in the polymer layer and that a high electric field is necessary to remove the charge.

  19. IGFBP3 suppresses retinopathy through suppression of oxygen-induced vessel loss and promotion of vascular regrowth

    PubMed Central

    Lofqvist, Chatarina; Chen, Jing; Connor, Kip M.; Smith, Alexandra C. H.; Aderman, Christopher M.; Liu, Nan; Pintar, John E.; Ludwig, Thomas; Hellstrom, Ann; Smith, Lois E. H.

    2007-01-01

    Vessel loss precipitates many diseases. In particular, vessel loss resulting in hypoxia induces retinal neovascularization in diabetic retinopathy and in retinopathy of prematurity (ROP), major causes of blindness. Here we define insulin-like growth factor binding protein-3 (IGFBP3) as a new modulator of vascular survival and regrowth in oxygen-induced retinopathy. In IGFBP3-deficient mice, there was a dose-dependent increase in oxygen-induced retinal vessel loss. Subsequent to oxygen-induced retinal vessel loss, Igfbp3−/− mice had a 31% decrease in retinal vessel regrowth versus controls after returning to room air. No difference in serum insulin-like growth factor 1 (IGF1) levels was observed among groups. Wild-type mice treated with exogenous IGFBP3 had a significant increase in vessel regrowth. This correlated with a 30% increase in endothelial progenitor cells in the retina at postnatal day 15, indicating that IGFBP3 could be serving as a progenitor cell chemoattractant. In a prospective clinical study, we measured IGFBP3 (and IGF1) plasma levels weekly and examined retinas in all premature infants born at gestational ages <32 weeks at high risk for ROP. The mean level of IGFBP3 at 30–35 weeks postmenstrual age (PMA) for infants with proliferative ROP (ROP stages 3>, n = 13) was 802 μg/liter, and for infants with no ROP (ROP stage 0, n = 38) the mean level was 974 μg/liter (P < 0.03). These results suggest that IGFBP3, acting independently of IGF1, helps to prevent oxygen-induced vessel loss and to promote vascular regrowth after vascular destruction in vivo in a dose-dependent manner, resulting in less retinal neovascularization. PMID:17567756

  20. Entropy Generation/Availability Energy Loss Analysis Inside MIT Gas Spring and "Two Space" Test Rigs

    NASA Technical Reports Server (NTRS)

    Ebiana, Asuquo B.; Savadekar, Rupesh T.; Patel, Kaushal V.

    2006-01-01

    The results of the entropy generation and availability energy loss analysis under conditions of oscillating pressure and oscillating helium gas flow in two Massachusetts Institute of Technology (MIT) test rigs piston-cylinder and piston-cylinder-heat exchanger are presented. Two solution domains, the gas spring (single-space) in the piston-cylinder test rig and the gas spring + heat exchanger (two-space) in the piston-cylinder-heat exchanger test rig are of interest. Sage and CFD-ACE+ commercial numerical codes are used to obtain 1-D and 2-D computer models, respectively, of each of the two solution domains and to simulate the oscillating gas flow and heat transfer effects in these domains. Second law analysis is used to characterize the entropy generation and availability energy losses inside the two solution domains. Internal and external entropy generation and availability energy loss results predicted by Sage and CFD-ACE+ are compared. Thermodynamic loss analysis of simple systems such as the MIT test rigs are often useful to understand some important features of complex pattern forming processes in more complex systems like the Stirling engine. This study is aimed at improving numerical codes for the prediction of thermodynamic losses via the development of a loss post-processor. The incorporation of loss post-processors in Stirling engine numerical codes will facilitate Stirling engine performance optimization. Loss analysis using entropy-generation rates due to heat and fluid flow is a relatively new technique for assessing component performance. It offers a deep insight into the flow phenomena, allows a more exact calculation of losses than is possible with traditional means involving the application of loss correlations and provides an effective tool for improving component and overall system performance.

  1. Nonlinear effects in the energy loss of a slow dipole in a free-electron gas

    SciTech Connect

    Alducin, M.; Juaristi, J.I.

    2002-11-01

    We analyze beyond linear-response theory the energy loss of a slow dipole moving inside a free-electron gas. The energy loss is obtained from a nonlinear treatment of the scattering of electrons at the dipole-induced potential. This potential and the total electronic density are calculated with density-functional theory. We focus on the interference effects, i.e., the difference between the energy loss of a dipole and that of the isolated charges forming it. Comparison of our results to those obtained in linear-response theory shows that a nonlinear treatment of the screening is required to accurately describe the energy loss of slow dipoles.

  2. Implementation of empirical total pressure loss data into the DUCTFLO and TOPAZ gas transfer codes

    SciTech Connect

    Winters, W.S.; Kanouff, M.P.

    1984-11-01

    Sandia presently has two computer codes capable of modeling local pressure and enthalpy losses in lines connecting gas reservoirs and receivers. Each code conserves flow continuity, momentum, and energy as a function of position along the flow path. The first of these codes, DUCTFLO, models gas flow by solving a set of coupled algebraic equations. The DUCTFLO code has been formulated to make direct use of laboratory total pressure and enthalpy loss data. The second code, TOPAZ, models gas flow by solving a set of coupled ordinary differential equations using a conventional finite difference technique. The TOPAZ finite difference equations must be altered slightly in order to make use of laboratory total pressure and enthalpy loss data. In this report, methods for implementing empirical loss data in the two codes are discussed. In quasi-steady flow situations, it is shown that the two codes predict the same gas transfer for a given set of empirical loss data. This is demonstrated in an example problem consisting of a reservoir and receiver connected by a series of seven flow components each having unique loss characteristics. 11 references, 6 figures, 2 tables.

  3. The production of low mass carbon stars - Carbon-rich dredge up or oxygen-rich mass loss?

    NASA Technical Reports Server (NTRS)

    Stencel, R. E.; Pesce, J. E.; Macgregor, K. M.

    1989-01-01

    Conventional theory explains the origin of carbon stars as due to dredge up of carbon enriched material from the stellar core during helium flash events late in the life of solar mass AGB stars. This relatively efficient process, however, seems to produce a larger C/O ratio than observed (Lambert et al., 1987). A secondary effect which could contribute to the appearance of carbon stars, is the selective removal of oxygen from the atmosphere by radiative force expulsion of oxygen-rich dust grains. Calculations for this scenario are presented, which evaluate the degree of momentum coupling between the grains and gas under the thermodynamical conditions of AGB star atmospheres.

  4. Application of the gas tracer method for measuring oxygen transfer rates in subsurface flow constructed wetlands.

    PubMed

    Tyroller, Lina; Rousseau, Diederik P L; Santa, Santa; García, Joan

    2010-07-01

    The oxygen transfer rate (OTR) has a significant impact on the design, optimal operation and modelling of constructed wetlands treating wastewater. Oxygen consumption is very fast in wetlands and the OTR cannot be determined using an oxygen mass balance. This problem is circumvented in this study by applying the gas tracer method. Experiments were conducted in an unplanted gravel bed (dimensions L x W x d 125 x 50 x 35 cm filled with a 30-cm layer of 10-11-mm gravel) and a planted horizontal subsurface flow constructed wetland (HSSFCW) (L x W x d 110 x 70 x 38 cm filled with a 30-cm layer of 3.5-mm gravel with Phragmites australis). Tap water saturated with propane as gas tracer (pure or commercial cooking gas, depending on the test) was used. The mass transfer ratio between oxygen and commercial propane gas was quite constant and averaged R = 1.03, which is slightly lower than the value of R = 1.39 that is usually reported for pure propane. The OTR ranged from 0.31 to 5.04 g O(2) m(-2) d(-1) in the unplanted gravel bed and from 0.3 to 3.2 g O(2) m(-2) d(-1) in the HSSFCW, depending on the hydraulic retention time (HRT). The results of this study suggest that the OTR in HSSFCW is very low for the oxygen demand of standard wastewater and the OTR calculations based on mass balances and theoretical stoichiometric considerations overestimate OTR values by a factor that ranges from 10 to 100. The gas tracer method is a promising tool for determining OTR in constructed wetlands, with commercial gas proving to be a viable low-cost alternative for determining OTR. PMID:20542312

  5. Gas sensing in microplates with optodes: influence of oxygen exchange between sample, air, and plate material.

    PubMed

    Arain, Sarina; Weiss, Svenja; Heinzle, Elmar; John, Gernot T; Krause, Christian; Klimant, Ingo

    2005-05-01

    Microplates with integrated optical oxygen sensors are a new tool to study metabolic rates and enzyme activities. Precise measurements are possible only if oxygen exchange between the sample and the environment is known. In this study we quantify gas exchange in plastic microplates. Dissolved oxygen was detected using either an oxygen-sensitive film fixed at the bottom of each well or a needle-type sensor. The diffusion of oxygen into wells sealed with different foils, paraffin oil, and paraffin wax, respectively, was quantified. Although foil covers showed the lowest oxygen permeability, they include an inevitable gas phase between sample and sealing and are difficult to manage. The use of oil was found to be critical due to the extensive shaking caused by movement of the plates during measurements in microplate readers. Thus, paraffin wax was the choice material because it avoids convection of the sample and is easy to handle. Furthermore, without shaking, significant gradients in pO2 levels within a single well of a polystyrene microplate covered with paraffin oil were detected with the needle-type sensor. Higher pO2 levels were obtained near the surface of the sample as well as near the wall of the well. A significant diffusion of oxygen through the plastic plate material was found using plates based on polystyrene. Thus, the location of a sensor element within the well has an effect on the measured pO2 level. Using a sensor film fixed on the bottom of a well or using a dissolved pO2-sensitive indicator results in pO2 offset and in apparently lower respiration rates or enzyme activities. Oxygen diffusion through a polystyrene microplate was simulated for measurements without convection--that is, for samples without oxygen diffusion through the cover and for unshaken measurements using permeable sealings. This mathematical model allows for calculation of the correct kinetic parameters. PMID:15772950

  6. Development of a compact multipass oxygen sensor used for gas diffusion studies in opaque media.

    PubMed

    Larsson, Jim; Mei, Liang; Lundin, Patrik; Bood, Joakim; Svanberg, Sune

    2015-11-20

    A highly scattering porous ceramic sample is employed as a miniature random-scattering multipass gas cell for monitoring of oxygen content in opaque media, that is, wood materials in the present work. Gas in scattering media absorption spectroscopy is used by employing a 760 nm near-infrared laser diode to probe the absorption of molecular oxygen enclosed in the pores of the ceramic material working as the multipass gas cell, with a porosity of 75%. A path length enhancement of approximately 26 times and a signal-to-noise ratio of about 60 were obtained for the ceramic sample used in this work. The gas sensor was then used in a case study of the gas diffusion in wood materials, namely, oak, spruce, and mahogany samples. Differences depending on whether gas diffusion was studied longitudinal or radial to the tree annual rings are demonstrated, with very little gas diffusing in the radial direction. We can also observe that the gas diffusion for the densest material-oak-had the fastest diffusion time, and mahogany, which had the lowest density, showed the slowest diffusion time. PMID:26836536

  7. Oxygen Therapy

    MedlinePlus

    Oxygen therapy is a treatment that provides you with extra oxygen. Oxygen is a gas that your body needs to function. Normally, your lungs absorb oxygen from the air you breathe. But some conditions ...

  8. Oxygen diffusion from anodic surface oxide films on titanium subhydride studied by auger electron spectroscopy and electron energy loss spectroscopy

    SciTech Connect

    Wang, P.S.; Wittberg, T.N.; Wolf, J.D.; Keil, R.G.

    1984-01-01

    In the present study, TiH/sub x/ (0.5 < x < 1.7) samples were prepared from titanium foil in order to study the diffusion of oxygen in the titanium subhydride. An anodic oxide, 1000A thick, was grown on the titanium subhydride foils in an aqueous saturated solution of ammonium tetraborate. These anodized samples were then heat treated at temperatures between 500 and 600/sup 0/C and changes in the profile of oxygen concentration as a function of depth were monitored using AES. From this data then it was possible to calculate the diffusivity of oxygen in the titanium subhydride. It was also found that electron energy loss spectroscopy (EELS) could be used to determine the titanium subhydride stoichiometry in the near-surface region. This was done by measuring the energy of the bulk plasmon loss peak, which for TiH/sub x/, varies linearly with hydrogen content. The amount of dehydriding which had occurred following a given heat treatment could be determined from profiles of the plasmon loss energy as a function of depth. A sample of anodized TiH/sub 0/ /sub 87/ was studied in some detail. Significant dehydriding of this sample for heat treatment times of less than one hour, only occurred at temperatures above 550/sup 0/C. Likewise, oxide dissolution was only significant at temperatures greater than 550/sup 0/C. In general, for the heat treatment parameters which were chosen, the diffusivity of oxygen in TiH/sub 0/ /sub 87/ was about an order of magnitude lower than that for oxygen in titanium.

  9. Comparison of simultaneous systemic steroid and hyperbaric oxygen treatment versus only steroid in idiopathic sudden sensorineural hearing loss

    PubMed Central

    Ersoy Callioglu, Elif; Tuzuner, Arzu; Demirci, Sule; Cengiz, Ceyhun; Caylan, Refik

    2015-01-01

    A retrospective chart review to assess the effectiveness of hyperbaric oxygen treatment in sudden sensorineural hearing loss. 44 patients aged between 17-67 years diagnosed with idiopathic sensorineural hearing loss less than 30 days were admitted to our clinic Patients were treated with systemic steroid alone or systemic steroid plus hyperbaric oxygen therapy. In the comparison of two groups, there was no statistically significant difference of audiometric evaluation (P>0.0028) found in hearing improvement for each frequency on 5th day of the treatment and post treatment. Age (≤45 and >45) and initial hearing level (≤60 dB. And >60 dB.) does not seem to be an influential factor according to the results of the study (P>0.0007). The present study did not show more superior healing effect of hyperbaric oxygen therapy added to systemic steroid therapy than steroid infusion alone. The results are consistent with those of some papers. However there are also conflicting data that support significant effect of hyperbaric oxygen therapy. Routine administration of this therapy seems to be unnecessary in view of these results. PMID:26309671

  10. Investigation of Copper Losses to Synthetic Slag at Different Oxygen Partial Pressures in the Presence of Colemanite

    NASA Astrophysics Data System (ADS)

    Rusen, Aydın; Derin, Bora; Geveci, Ahmet; Topkaya, Yavuz Ali

    2016-05-01

    Copper losses to slag are crucial for copper matte smelting and converting stages. One factor affecting the copper losses to slag during these processes is partial pressure of oxygen. In this study, theoretical and experimental investigations of oxygen partial pressure effect on copper losses to fayalite type slag in the presence of colemanite were investigated. Theoretical considerations include liquidus temperatures and phase diagrams of the fayalite type slag calculated by the FactSage software program. In the experiments, a synthetic matte-slag (SM-SS) was produced by melting certain amounts of reagent grade Fe2O3-SiO2 and metallic Fe as starting materials. Experiments were carried out with SM-SS pair by the addition of calcined colemanite (from 0% to 6%) under various partial pressures of oxygen (10-7, 10-9, 10-11 atm) at 1250°C for 2 h. From the experimental results, it was found that the amount of copper in slag decreased slowly when colemanite was increased under all oxidizing atmospheres. The lowest copper content in synthetic slag was obtained as 0.38% after 6% colemanite addition.

  11. Oxygen diffusion from anodic surface oxide films on titanium subhydride studies by auger electron spectroscopy and electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, P. S.; Wittberg, T. N.; Wolf, J. D.; Keil, R. G.

    TiH sub x (0.5 less than x less than 1.7) samples were prepared from titanium foil in order to study the diffusion of oxygen in the titanium subhydride. An anodic oxide, 1000A thick, was grown on the titanium subhydride foils in an agueous saturated solution of ammonium tetraborate. These anodized samples were then heat treated at temperatures between 500 and 600(0)C and changes in the profile of oxygen concentration as a function of depth were monitored using auger electron spectroscopy. From this data then it was possible to calculate the diffusivity of oxygen in the titanium subhydride. It was also found that electron energy loss spectroscopy could be used to determine the titanium subhydride stoichiometry in the near-surface region. This was done by measuring the energy of the bulk plasmon loss peak, which for TiH sub x, varies linearly with hydrogen content. The amount of dehydriding which occurred following a given heat treatment could be determined from profiles of the plasmon loss energy as a function of depth. A sample of anodized TiH0 87 was studied in some detail. Significant dehydriding of this sample for heat treatment times of less than one hour only occured at temperatures above 550(0)C.

  12. A System for Controlling the Oxygen Content of a Gas Produced by Combustion

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Davis, W. T.; Puster, R. L. (Inventor)

    1984-01-01

    A mixture of air, CH4 and OH(2) is burned in a combustion chamber to produce a product gas in the test section. The OH(2) content of the product gas is compared with the OH(2) content of reference air in an OH(2) sensor. If there is a difference an error signal is produced at the output of a control circuit which by the means of a solenoid valve, regulates the flow of OH(2) into the combustion chamber to make the error signal zero. The product gas in the test section has the same oxygen content as air.

  13. Conversion of Mixed Oxygenates Generated from Synthesis Gas to Fuel Range Hydrocarbon

    SciTech Connect

    Ramasamy, Karthikeyan K.; Gerber, Mark A.; Lilga, Michael A.; Flake, Matthew D.

    2012-08-19

    The growing dependence in the U.S. on foreign crude oil supplies and increased concerns regarding greenhouse gas emission has generated considerable interest in research to develop renewable and environmentally friendly liquid hydrocarbon transportation fuels. One of the strategies for achieving this is to produce intermediate compounds such as alcohols and other simple oxygenates from biomass generated synthesis gas (mixture of carbon monoxide and hydrogen) and further convert them into liquid hydrocarbons. The focus of this research is to investigate the effects of mixed oxygenates intermediate product compositions on the conversion step to produce hydrocarbon liquids. A typical mixed oxygenate stream is expected to contain water (around 50%), alcohols, such as methanol and ethanol (around 35%), and smaller quantities of oxygenates such as acetaldehyde, acetic acid and ethyl acetate. However the ratio and the composition of the mixed oxygenate stream generated from synthesis gas vary significantly depending on the catalyst used and the process conditions. Zeolite catalyzed deoxygenation of methanol accompanied by chain growth is well understood under Methanol-to-Gasoline (MTG) like reaction conditions using an H-ZSM-5 zeolite as the catalyst6-8. Research has also been conducted to a limited extent in the past with higher alcohols, but not with other oxygenates present9-11. Also there has been little experimental investigation into mixtures containing substantial amounts of water. The latter is of particular interest because water separation from the hydrocarbon product would be less energy intensive than first removing it from the oxygenate intermediate stream prior to hydrocarbon synthesis, potentially reducing overall processing costs.

  14. Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 1; Aircraft System Requirements

    NASA Technical Reports Server (NTRS)

    Reynolds, Thomas L.; Bailey, Delbert B.; Lewinski, Daniel F.; Roseburg, Conrad M.; Palaszewski, Bryan (Technical Monitor)

    2001-01-01

    The purpose of this technology assessment is to define a multiphase research study program investigating Onboard Inert Gas Generation Systems (OBIGGS) and Onboard Oxygen Generation Systems (OBOGS) that would identify current airplane systems design and certification requirements (Subtask 1); explore state-of-the-art technology (Subtask 2); develop systems specifications (Subtask 3); and develop an initial system design (Subtask 4). If feasible, consideration may be given to the development of a prototype laboratory test system that could potentially be used in commercial transport aircraft (Subtask 5). These systems should be capable of providing inert nitrogen gas for improved fire cargo compartment fire suppression and fuel tank inerting and emergency oxygen for crew and passenger use. Subtask I of this research study, presented herein, defines current production aircraft certification requirements and design objectives necessary to meet mandatory FAA certification requirements and Boeing design and performance specifications. These requirements will be utilized for baseline comparisons for subsequent OBIGGS/OBOGS application evaluations and assessments.

  15. Study of the radiated energy loss during massive gas injection mitigated disruptions on EAST

    NASA Astrophysics Data System (ADS)

    Duan, Y. M.; Hao, Z. K.; Hu, L. Q.; Wang, L.; Xu, P.; Xu, L. Q.; Zhuang, H. D.

    2015-08-01

    The MGI mitigated disruption experiments were carried out on EAST with a new fast gas controlling valve in 2012. Different amounts of noble gas He or mixed gas of 99% He + 1% Ar are injected into plasma in current flat-top phase and current ramp-down phase separately. The initial results of MGI experiments are described. The MGI system and the radiation measurement system are briefly introduced. The characteristics of radiation distribution and radiation energy loss are analyzed. About 50% of the stored thermal energy Wdia is dissipated by radiation during the entire disruption process and the impurities of C and Li from the PFC play important roles to radiative energy loss. The amount of the gas can affect the pre-TQ phase. Strong poloidal asymmetry of radiation begins to appear in the CQ phase, which is possibly caused by the plasma configuration changes as a result of VDE. No toroidal radiation asymmetry is observed presently.

  16. Loss-of-coolant accident experiment at the AVR (Arbeitsgemeinschaft Versuchsreaktor) gas-cooled reactor

    SciTech Connect

    Krueger, K. ); Cleveland, J. )

    1989-11-01

    Loss of coolant is one of the most severe accidents for a nuclear power plant. To demonstrate inherent safety characteristics incorporated into modular gas-cooled reactor designs, loss-of-coolant accident (LOCA) simulation tests were conducted with the 15-MW(electric), 46-MW(thermal), pebble-bed, high-temperature Arbeitsgemeinschaft Versuchsreaktor (AVR) in the Federal Republic of Germany (FRG). This is the only nuclear power plant ever to have been intentionally subjected to LOCa conditions. Oak Ridge National Laboratory participation in the preparation and conduct of the tests was carried out within the U.S./FRG Agreement for Cooperation in Gas-Cooled Reactor Development.

  17. Online derivatization for hourly measurements of gas- and particle-phase semi-volatile oxygenated organic compounds by thermal desorption aerosol gas chromatography (SV-TAG)

    NASA Astrophysics Data System (ADS)

    Isaacman, G.; Kreisberg, N. M.; Yee, L. D.; Worton, D. R.; Chan, A. W. H.; Moss, J. A.; Hering, S. V.; Goldstein, A. H.

    2014-12-01

    Laboratory oxidation studies have identified a large number of oxygenated organic compounds that can be used as tracers to understand sources and oxidation chemistry of atmospheric particulate matter. Quantification of these compounds in ambient environments has traditionally relied on low-time-resolution collection of filter samples followed by offline sample treatment with a derivatizing agent to allow analysis by gas chromatography of otherwise non-elutable organic chemicals with hydroxyl groups. We present here an automated in situ instrument for the measurement of highly polar organic semi-volatile and low-volatility compounds in both the gas- and particle-phase with hourly quantification of mass concentrations and gas-particle partitioning. The dual-cell semi-volatile thermal desorption aerosol gas chromatograph (SV-TAG) with derivatization collects particle-only and combined particle-plus-vapor samples on two parallel sampling cells that are analyzed in series by thermal desorption into helium saturated with derivatizing agent. Introduction of MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide), a silylating agent, yields complete derivatization of all tested compounds, including alkanoic acids, polyols, diacids, sugars, and multifunctional compounds. In laboratory tests, derivatization is found to be highly reproducible (< 3% variability). During field deployment, a regularly injected internal standard is used to correct for variability in detector response, consumption of the derivatization agent, desorption efficiency, and transfer losses. Error in quantification from instrument fluctuations is found to be less than 10% for hydrocarbons and less than 15% for all oxygenates for which a functionally similar internal standard is available, with an uncertainty of 20-25% in measurements of particle fraction. After internal standard corrections, calibration curves are found to be linear for all compounds over the span of 1 month, with comparable response on

  18. Gas exchange patterns and water loss rates in the Table Mountain cockroach, Aptera fusca (Blattodea: Blaberidae).

    PubMed

    Groenewald, Berlizé; Bazelet, Corinna S; Potter, C Paige; Terblanche, John S

    2013-10-15

    The importance of metabolic rate and/or spiracle modulation for saving respiratory water is contentious. One major explanation for gas exchange pattern variation in terrestrial insects is to effect a respiratory water loss (RWL) saving. To test this, we measured the rates of CO2 and H2O release ( and , respectively) in a previously unstudied, mesic cockroach, Aptera fusca, and compared gas exchange and water loss parameters among the major gas exchange patterns (continuous, cyclic, discontinuous gas exchange) at a range of temperatures. Mean , and per unit did not differ among the gas exchange patterns at all temperatures (P>0.09). There was no significant association between temperature and gas exchange pattern type (P=0.63). Percentage of RWL (relative to total water loss) was typically low (9.79±1.84%) and did not differ significantly among gas exchange patterns at 15°C (P=0.26). The method of estimation had a large impact on the percentage of RWL, and of the three techniques investigated (traditional, regression and hyperoxic switch), the traditional method generally performed best. In many respects, A. fusca has typical gas exchange for what might be expected from other insects studied to date (e.g. , , RWL and cuticular water loss). However, we found for A. fusca that expressed as a function of metabolic rate was significantly higher than the expected consensus relationship for insects, suggesting it is under considerable pressure to save water. Despite this, we found no consistent evidence supporting the conclusion that transitions in pattern type yield reductions in RWL in this mesic cockroach. PMID:23821716

  19. Optical methods and systems for detecting a constituent in a gas containing oxygen in harsh environments

    DOEpatents

    Carpenter, Michael A.; Sirinakis, George

    2011-01-04

    A method for detecting a gas phase constituent such as carbon monoxide, nitrogen dioxide, hydrogen, or hydrocarbons in a gas comprising oxygen such as air, includes providing a sensing material or film having a metal embedded in a catalytically active matrix such as gold embedded in a yttria stabilized zirconia (YSZ) matrix. The method may include annealing the sensing material at about 900.degree. C., exposing the sensing material and gas to a temperature above 400.degree. C., projecting light onto the sensing material, and detecting a change in the absorption spectrum of the sensing material due to the exposure of the sensing material to the gas in air at the temperature which causes a chemical reaction in the sensing material compared to the absorption spectrum of the sensing material in the absence of the gas. Systems employing such a method are also disclosed.

  20. Investigation of personal and fixed head oxygen deficiency hazard monitor performance for helium gas

    SciTech Connect

    D. Arenius; D. Curry; A. Hutton; K. Mahoney; S. Prior; H. Robertson

    2002-05-10

    On May 14, 2001, the Thomas Jefferson National Accelerator Facility (JLAB) conducted a planned liquid helium release into its accelerator tunnel to study the effectiveness of the JLAB facility to vent the helium and therefore limit the oxygen deficiency hazard (ODH). During the test, it was discovered that a wide range of various oxygen deficiency monitors, of different manufacturers, were providing substantial conflicting measurements of the true oxygen level where health effects are of concern. Yet, when tested separately with nitrogen gas as the diluting gas into air, the same models performed very well. This problem, which is associated with helium displacement of air, was found for both personal oxygen monitors and fixed installation monitors from many different manufacturers. By informing other facilities of its findings, JLAB became aware this problem also exists among other national laboratories and facilities. Many manufacturers do not have data on the effects of helium displacing air for their devices. Some manufacturers have now duplicated the test results conducted at JLAB. Since both fixed installation and personal oxygen monitors have become standard safety device in many research facilities and industries in the United States and abroad, it is important that these facilities are aware of the problem and how it is being addressed at JLAB. This paper discusses the methods, procedures and materials used by JLAB to qualify its ODH sensors for helium. Data and graphs of JLAB's findings are provided.

  1. Habitat loss and modification due to gas development in the Fayetteville shale.

    PubMed

    Moran, Matthew D; Cox, A Brandon; Wells, Rachel L; Benichou, Chloe C; McClung, Maureen R

    2015-06-01

    Hydraulic fracturing and horizontal drilling have become major methods to extract new oil and gas deposits, many of which exist in shale formations in the temperate deciduous biome of the eastern United States. While these technologies have increased natural gas production to new highs, they can have substantial environmental effects. We measured the changes in land use within the maturing Fayetteville Shale gas development region in Arkansas between 2001/2002 and 2012. Our goal was to estimate the land use impact of these new technologies in natural gas drilling and predict future consequences for habitat loss and fragmentation. Loss of natural forest in the gas field was significantly higher compared to areas outside the gas field. The creation of edge habitat, roads, and developed areas was also greater in the gas field. The Fayetteville Shale gas field fully developed about 2% of the natural habitat within the region and increased edge habitat by 1,067 linear km. Our data indicate that without shale gas activities, forest cover would have increased slightly and edge habitat would have decreased slightly, similar to patterns seen recently in many areas of the southern U.S. On average, individual gas wells fully developed about 2.5 ha of land and modified an additional 0.5 ha of natural forest. Considering the large number of wells drilled in other parts of the eastern U.S. and projections for new wells in the future, shale gas development will likely have substantial negative effects on forested habitats and the organisms that depend upon them. PMID:25566834

  2. Habitat Loss and Modification Due to Gas Development in the Fayetteville Shale

    NASA Astrophysics Data System (ADS)

    Moran, Matthew D.; Cox, A. Brandon; Wells, Rachel L.; Benichou, Chloe C.; McClung, Maureen R.

    2015-06-01

    Hydraulic fracturing and horizontal drilling have become major methods to extract new oil and gas deposits, many of which exist in shale formations in the temperate deciduous biome of the eastern United States. While these technologies have increased natural gas production to new highs, they can have substantial environmental effects. We measured the changes in land use within the maturing Fayetteville Shale gas development region in Arkansas between 2001/2002 and 2012. Our goal was to estimate the land use impact of these new technologies in natural gas drilling and predict future consequences for habitat loss and fragmentation. Loss of natural forest in the gas field was significantly higher compared to areas outside the gas field. The creation of edge habitat, roads, and developed areas was also greater in the gas field. The Fayetteville Shale gas field fully developed about 2 % of the natural habitat within the region and increased edge habitat by 1,067 linear km. Our data indicate that without shale gas activities, forest cover would have increased slightly and edge habitat would have decreased slightly, similar to patterns seen recently in many areas of the southern U.S. On average, individual gas wells fully developed about 2.5 ha of land and modified an additional 0.5 ha of natural forest. Considering the large number of wells drilled in other parts of the eastern U.S. and projections for new wells in the future, shale gas development will likely have substantial negative effects on forested habitats and the organisms that depend upon them.

  3. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUIDIZED BED BOILERS

    SciTech Connect

    Nsakala ya Nsakala; Gregory N. Liljedahl

    2003-05-15

    Given that fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this study, ALSTOM Power Inc. (ALSTOM) has investigated several coal fired power plant configurations designed to capture CO{sub 2} from effluent gas streams for use or sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than in PC or Stoker firing, because recirculated gas flow can be reduced significantly. Oxygen-fired PC and Stoker units require large quantities of recirculated flue gas to maintain acceptable furnace temperatures. Oxygen-fired CFB units, on the other hand, can accomplish this by additional cooling of recirculated solids. The reduced recirculated gas flow with CFB units results in significant Boiler Island cost savings. Additionally, ALSTOM has identified several advanced/novel plant configurations, which improve the efficiency and cost of the CO{sub 2} product cleanup and compression process. These advanced/novel concepts require long development efforts. An economic analysis indicates that the proposed oxygen-firing technology in circulating fluidized boilers could be developed and deployed economically in the near future in enhanced oil recovery (EOR) applications or enhanced gas recovery (EGR), such as coal bed methane recovery. ALSTOM received a Cooperative Agreement from the US Department

  4. Fast vacancy-mediated oxygen ion incorporation across the ceria-gas electrochemical interface

    NASA Astrophysics Data System (ADS)

    Feng, Zhuoluo A.; El Gabaly, Farid; Ye, Xiaofei; Shen, Zhi-Xun; Chueh, William C.

    2014-07-01

    Electrochemical incorporation reactions are ubiquitous in energy storage and conversion devices based on mixed ionic and electronic conductors, such as lithium-ion batteries, solid-oxide fuel cells and water-splitting membranes. The two-way traffic of ions and electrons across the electrochemical interface, coupled with the bulk transport of mass and charge, has been challenging to understand. Here we report an investigation of the oxygen-ion incorporation pathway in CeO2-δ (ceria), one of the most recognized oxygen-deficient compounds, during hydrogen oxidation and water splitting. We probe the response of surface oxygen vacancies, electrons and adsorbates to the electrochemical polarization at the ceria-gas interface. We show that surface oxygen-ion transfer, mediated by oxygen vacancies, is fast. Furthermore, we infer that the electron transfer between cerium cations and hydroxyl ions is the rate-determining step. Our in operando observations reveal the precise roles of surface oxygen vacancy and electron defects in determining the rate of surface incorporation reactions.

  5. Discontinuous gas exchange, water loss, and metabolism in Protaetia cretica (Cetoniinae, Scarabaeidae).

    PubMed

    Matthews, Philip G D; White, Craig R

    2012-01-01

    Insects are at high risk of desiccation because of their small size, high surface-area-to-volume ratio, and air-filled tracheal system that ramifies throughout their bodies to transport O(2) and CO(2) to and from respiring cells. Although the tracheal system offers a high-conductance pathway for the movement of respiratory gases, it has the unintended consequence of allowing respiratory transpiration to the atmosphere. When resting, many species exchange respiratory gases discontinuously, and an early hypothesis for the origin of these discontinuous gas exchange cycles (DGCs) is that they serve to reduce respiratory water loss. In this study, we test this "hygric" hypothesis by comparing rates of CO(2) exchange and water loss among flower beetles Protaetia cretica (Cetoniinae, Scarabaeidae) breathing either continuously or discontinuously. We show that, consistent with the expectations of the hygric hypothesis, rates of total water loss are higher during continuous gas exchange than during discontinuous gas exchange and that the ratio of respiratory water loss to CO(2) exchange is lower during discontinuous gas exchange. This conclusion is in agreement with other studies of beetles and cockroaches that also support the hygric hypothesis. However, this result does not exclude other adaptive hypotheses supported by work on ants and moth pupae. This ambiguity may arise because there are multiple independent evolutionary origins of DGCs and no single adaptive function underlying their genesis. Alternatively, the observed reduction in water loss during DGCs may be a side effect of a nonadaptive gas exchange pattern that is elicited during periods of inactivity. PMID:22418709

  6. Dynamics of a laser-produced silver plume in an oxygen background gas

    NASA Astrophysics Data System (ADS)

    Schou, Jorgen; Toftmann, Bo; Amoruso, Salvatore

    2004-09-01

    The expansion of a plasma plume in a background gas is a key problem for film deposition and laser ablation studies. Combined diagnostic measurements of deposition rates and ion time-of-flight (TOF) signals have been used to study the dynamics of a laser ablation plume in an oxygen gas. This study is similar to our previous work on an argon background gas and shows essentially the same trend. At an enhanced gas pressure, the angular distribution of collected ablated atoms becomes comparatively broad, while the total collected yield decreases strongly. The total collected yield exhibits three separate regimes with increasing pressure, a vacuum-like regime, a transition regime with increasing plume broadening and splitting of the ion signal, and at the highest pressures a diffusion-like regime with a broad angular distribution. In the high pressure regime, the expansion can be described by a simple model based on diffusion from a confined plume.

  7. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

    USGS Publications Warehouse

    Amstrup, Steven C.; Deweaver, E.T.; Douglas, D.C.; Marcot, B.G.; Durner, G.M.; Bitz, C.M.; Bailey, D.A.

    2010-01-01

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the worlds polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

  8. Oxygen-induced changes in electron-energy-loss spectra for Al, Be and Ni. [Al; Be; Ni

    SciTech Connect

    Madden, H.H.; Landers, R.; Kleiman, G.G. , 13081-970 Campinas, Sao Paulo, Brasil); Zehner, D.M. )

    1999-09-01

    Electron-energy-loss spectroscopy (EELS) data are presented to illustrate line shape changes that occur as a result of oxygen interaction with metal surfaces. The metals were aluminum, beryllium and nickel. Core-level EELS data were taken for excitations from Al(2p), Be(1s), Ni(3p/3s) and O(1s) levels to the conduction band (CB) density of states (DOS) of the materials. The primary beam energies for the spectra were 300, 450, 300, and 1135 eV, respectively. The data are presented in both the (as measured) first-derivative and the integral forms. The integral spectra were corrected for coherent background losses and analyzed for CB DOS information. These spectra were found to be in qualitative agreement with published experimental and theoretical studies of these materials. One peak in the spectra for Al oxide is analyzed for its correlation with excitonic screening of the Al(2p) core hole. Similar evidence for exciton formation is found in the Ni(3p) spectra for Ni oxide. Data are also presented showing oxygen-induced changes in the lower-loss-energy EELS curves that, in the pure metal, are dominated by plasmon-loss and interband-transition signals. Single-scattering loss profiles in the integral form of the data were calculated using a procedure of Tougaard and Chorkendorff [S. Tougaard and I. Chorkendorff, Phys. Rev. B. [bold 35], 6570 (1987)]. For all three oxides these profiles are dominated by a feature with a loss energy of around 20[endash]25 eV. Although this feature has been ascribed by other researchers as due to bulk plasmon losses in the oxide, an alternative explanation is that the feature is simply due to O(2s)-to-CB-level excitations. An even stronger feature is found at 7 eV loss energy for Ni oxide. Speculation is given as to its source. The line shapes in both the core-level and noncore-level spectra can also be used simply as [open quotes]fingerprints[close quotes] of the surface chemistry of the materials. Our data were taken using commercially

  9. Pulmonary shunt: a comparison between oxygen and inert gas infusion methods.

    PubMed

    Hlastala, M P; Colley, P S; Cheney, F W

    1975-12-01

    Pulmonary shunt measurement was compared using the standard oxygen (Berggren) technique and a new multiple inert gas infusion (Wagner et al.) technique in 11 mongrel dogs with either regional atelectasis or diffuse pulmonary edema. Relative retentions of sulfur hexafluoride, ethane, cyclopropane, halothane, diethyl ether, and acetone were used to calculate intrapulmonary shunt. Relative dilution of oxygen (Berggren method) was used to calculate total right to left shunt. The two methods gave similar results in the range of 20-80%. At low shunts the oxygen method measured higher values. This is because of the greater relative importance of fixed extrapulmonary shunts at this level and, as well, error in the measurement of PO2. Both techniques are suitable for normal clinical use. PMID:175043

  10. Efficient generation in a chemical oxygen - iodine laser with a low buffer-gas flow rate

    SciTech Connect

    Azyazov, V N; Safonov, V S; Ufimtsev, N I

    2002-09-30

    The efficient generation in a chemical oxygen - iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M {<=} 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s{sup -1}, which corresponds to a chemical efficiency {eta}{sub ch} =23%. It is shown that the substitution of the buffer gas CO{sub 2} for N{sub 2} does not cause any significant variation in the dependence of the output power on the degree of dilution of the active medium. (lasers)

  11. Singlet-oxygen generation at gas-liquid interfaces: A significant artifact in the measurement of singlet-oxygen yields from ozone-biomolecule reactions

    SciTech Connect

    Kanofsky, J.R.; Sima, P.D. )

    1993-09-01

    Several ozone-biomolecule reactions have previously been shown to generate singlet oxygen in high yields. For some of these ozone-biomolecule reactions, we now show that the apparent singlet-oxygen yields determined from measurements of 1270 nm chemiluminescence were artifactually elevated by production of gas-phase singlet oxygen. The gas-phase singlet oxygen results from the reaction of gas-phase ozone with biomolecules near the surface of the solution. Through the use of a flow system that excludes air from the reaction chamber, accurate singlet-oxygen yields can be obtained. The revised singlet-oxygen yields (mol 1O2 per mol O3) for the reactions of ozone with cysteine, reduced glutathione, NADH, NADPH, human albumin, methionine, uric acid and oxidized glutathione are 0.23 +/- 0.02, 0.26 +/- 0.2, 0.48 +/- 0.04, 0.41 +/- 0.01, 0.53 +/- 0.06, 1.11 +/- 0.04, 0.73 +/- 0.05 and 0.75 +/- 0.01, respectively. These revised singlet-oxygen yields are still substantial.

  12. Oxygen-rich mass loss from carbon-rich stars - Some implications

    NASA Technical Reports Server (NTRS)

    Stencel, Robert E.; Pesce, Joseph E.

    1989-01-01

    The degree of dust-to-gas coupling in the atmospheres of red giant stars is evaluated, and nonzero drift velocities are found. Chemical fractionation of the stellar atmosphere on an evolutionary time scale is implied.

  13. The Decompression Sickness and Venous Gas Emboli Consequences of Air Breaks During 100% Oxygen Prebreathe

    NASA Technical Reports Server (NTRS)

    Conkin, Johnny; Gernhardt, Michael L.; Powell, Michael R.

    2005-01-01

    Not enough is known about the increased risk of hypobaric decompression sickness (DCS) and production of venous (VGE) and arterial (AGE) gas emboli following an air break in an otherwise normal 100% resting oxygen (O2) prebreathe (PB), and certainly a break in PB when exercise is used to accelerate nitrogen (N2) elimination from the tissues. Current Aeromedical Flight Rules at the Johnson Space Center about additional PB payback times are untested, possibly too conservative, and therefore not optimized for operational use.

  14. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    SciTech Connect

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-03-17

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase id dispersed.

  15. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    SciTech Connect

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-09-29

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase is dispersed.

  16. Kinetics of gas phase oxygen control system (OCS) for stagnant and flowing Pb-Bi Systems

    NASA Astrophysics Data System (ADS)

    Lefhalm, C. H.; Knebel, J. U.; Mack, K. J.

    2001-07-01

    Pb and Pb-Bi are known to be very corrosive to structural materials at elevated temperatures. In recent studies, the necessity of measurement and control of the oxygen concentration in the liquid metal in order to safely operate a liquid Pb or Pb-Bi loop has been shown. The dynamic behaviour of the gas phase oxygen control system (OCS), which was developed at Forschungszentrum Karlsruhe (FZK), is investigated with respect to diffusion as the limiting process of oxygen exchange between the gas phase and the liquid metal. In this paper the development of a physical model for this diffusion process is described and compared to experimental results of a stagnant liquid Pb-Bi system. The experimental findings are in very good agreement with the theoretical equations describing the thermodynamic and kinetic behaviour of such a system. Recent investigations in a Pb-Bi loop at the Karlsruhe Lead Laboratory (KALLA) indicate that this gas phase OCS is a promising candidate system for an accelerator-driven subcritical system (ADS).

  17. Control of discontinuous gas exchange in Samia cynthia: effects of atmospheric oxygen, carbon dioxide and moisture.

    PubMed

    Terblanche, John S; Marais, Elrike; Hetz, Stefan K; Chown, Steven L

    2008-10-01

    The evolution of discontinuous gas exchange (DGE) in insects is highly controversial. Adaptive hypotheses which have obtained experimental support include a water savings mechanism for living in dry environments (hygric hypothesis), a reduction in oxidative damage due to a high-performance oxygen delivery system (oxidative damage hypothesis), and the need for steep intratracheal partial pressure gradients to exchange gases under the hypercapnic and/or hypoxic conditions potentially encountered in subterranean environments (chthonic hypothesis). However, few experimental studies have simultaneously assessed multiple competing hypotheses within a strong inference framework. Here, we present such a study at the species level for a diapausing moth pupa, Samia cynthia. Switching gas conditions from controlled normoxic, normocapnic and intermediate humidity to either high or low oxygen, high or low moisture, elevated carbon dioxide, or some combination of these, revealed that DGE was abandoned under all conditions except high oxygen, and high or low gas moisture levels. Thus, support is found for the oxidative damage hypothesis when scored as maintenance of DGE. Modulation of DGE under either dry or hyperoxic conditions suggested strong support for the oxidative damage hypothesis and some limited support for the hygric hypothesis. Therefore, this study demonstrates that the DGE can be maintained and modulated in response to several environmental variables. Further investigation is required using a strong-inference, experimental approach across a range of species from different habitats to determine how widespread the support for the oxidative damage hypothesis might be. PMID:18840661

  18. Respiratory and cuticular water loss in insects with continuous gas exchange: comparison across five ant species.

    PubMed

    Schilman, Pablo E; Lighton, John R B; Holway, David A

    2005-12-01

    Respiratory water loss (RWL) in insects showing continuous emission of CO(2) is poorly studied because few methodologies can measure it. Comparisons of RWL between insects showing continuous and discontinuous gas exchange cycles (DGC) are therefore difficult. We used two recently developed methodologies (the hyperoxic switch and correlation between water-loss and CO(2) emission rates) to compare cuticular permeabilities and rates of RWL in five species of ants, the Argentine ant (Linepithema humile) and four common native ant competitors. Our results showed that RWL in groups of ants with moderate levels of activity and continuous gas exchange were similar across the two measurement methods, and were similar to published values on insects showing the DGC. Furthermore, ants exposed to anoxia increased their total water loss rates by 50-150%. These results suggest that spiracular control under continuous gas exchange can be as effective as the DGC in reducing RWL. Finally, the mesic-adapted Argentine ant showed significantly higher rates of water loss and cuticular permeability compared to four ant species native to dry environments. Physiological limitations may therefore be responsible for restricting the distribution of this invasive species in seasonally dry environments. PMID:16154585

  19. The mass-loss evolution of oxygen-rich AGB stars and its consequences for stellar evolution

    NASA Astrophysics Data System (ADS)

    van der Veen, W. E. C. J.

    1989-02-01

    A semiempirical mass loss equation (MLE) for Asymptotic Giant Branch (AGB) stars with oxygen-rich circumstellar shells is presented. The MLE is a function of stellar luminosity, expansion velocity of the circumstellar shell, and the ratio between the IRAS 25 and 12 micron flux densities. The results are compared with previously derived MLEs. The IRAS Point Source Catalog is used to find the mass loss as a function of time. The MLE is tested by estimating the total mass lost on the AGB. A simple expression is found relating the initial main sequence mass and the maximum AGB luminosity. The time-dependent properties of the MLE are tested using a sample of Miras and OH/IR stars. A relation between period, luminosity, and stellar envelope mass is found and compared with the observed period-luminosity relations for globular cluster Miras and Miras in the LMC. Good agreement is found.

  20. Complete recovery following hyperbaric oxygen therapy in idiopathic sudden sensorineural hearing loss--a report of two cases.

    PubMed

    Agrawal, Swati; Sharma, Nishi

    2016-01-01

    Idiopathic sudden sensorineural hearing loss (ISSHL), a common otologic emergency, presents mostly as an abrupt onset unilateral hearing loss, aural fullness, often with vertigo and tinnitus, usually upon awakening in the morning. Its etiopathogenesis is multifactorial, so a number of different therapeutic regimens are in practice, hyperbaric oxygen (HBO2) therapy being an effective yet underutilized one. Not all cases recover completely even after treatment. Here we describe two cases of ISSHL, diagnosed on the basis of clinical examination and pure-tone audiometry, who had a complete recovery following administration of HBO2 therapy in addition to medical treatment. These cases are reported to highlight the effectiveness of this modality in a physician's armamentarium. PMID:27265993

  1. A micro-thermoelectric gas sensor for detection of hydrogen and atomic oxygen.

    PubMed

    Park, Se-Chul; Yoon, Seung-Il; Lee, Chung-il; Kim, Yong-Jun; Song, Soonho

    2009-02-01

    This paper demonstrates the fabrication and performance of a micro-thermoelectric gas sensor for an effective and inexpensive gas analysis system. The proposed micro-thermoelectric gas sensor was fabricated by using a surface micromachining technique. The sensing mechanism, consisting of thermoelectric material and a novel metal catalyst, was fabricated on the highly thermally resistive layer for reduced heat transfer to the substrate allowing for a simple fabrication process. The micro-thermoelectric gas sensor detects target gas species by measuring the reaction heat of the catalytic reaction between the target gas and a novel metal catalyst using Cu-Bi thermopiles. The catalytic reaction occurs only on the hot junction of the sensing thermopile where the metal catalyst is deposited. In order to reduce the external thermal noise, a difference between the output voltage of the sensing and the reference thermopiles was measured by using a differential amplifier. The response of the fabricated sensor was linear to temperature difference. The fabricated sensor can be used to detect various concentrations of hydrogen and atomic oxygen, where the output voltage linearly increased with the gas concentration. PMID:19173043

  2. Oxygen gas-sheet beam profile monitor for the synchrotron and storage ring

    NASA Astrophysics Data System (ADS)

    Hashimoto, Y.; Fujisawa, T.; Morimoto, T.; Fujita, Y.; Honma, T.; Muto, S.; Noda, K.; Sato, Y.; Yamada, S.

    2004-07-01

    A fast, non-destructive beam-profile monitor was developed using an oxygen gas-sheet target in the Heavy Ion Medical Accelerator in Chiba synchrotron. The size of the gas-sheet target was 85 mm in width and 1.3 mm in thickness, of which the density was 1×10 -4 Pa. The base vacuum in the ring was not deteriorated by this gas-sheet target, and was on the order of 10 -8 Pa. In typical cases, carbon ion beams are accelerated from 6 to 290-430 MeV/n for cancer therapy, in which the intensity is 2.5×10 8 particles/bunch. For these beams, two-dimensional beam profiles were successfully measured within the time (˜100 ns) of the bunch separation. This article describes both the technical and physical aspects of the monitor together with some results.

  3. A Numerical Study on Gas Phase Dynamics of High-Velocity Oxygen Fuel Thermal Spray

    NASA Astrophysics Data System (ADS)

    Baik, Jae-Sang; Park, Sun-Kyu; Kim, Youn-Jea

    2008-08-01

    The high-velocity oxygen fuel (HVOF) thermal spray is used for a particulate deposition process in which micro-sized particles are propelled and heated in a supersonic combusting gas stream. It is characterized by high gas velocity and high density and is being used in an increasing variety of coating applications, such as ceramic and composite coatings, to improve wear and abrasion resistance. The particle temperature and velocity are two of the most important parameters in HVOF thermal spraying, which affect the quality of the coatings. To understand the particle dynamics, it is necessary to study, first, the thermal flow characteristics in the HVOF system. In this study, a numerical analysis is performed to predict the gas dynamic behaviors, and the effect of the geometrical parameter is studied to optimize the nozzle design.

  4. Multilayer Resist Profile Control in Oxygen Reactive Ion Etching Using Ethanol Gas Mixture

    NASA Astrophysics Data System (ADS)

    Kimura, Yasuki; Aoyama, Ryouichi; Suzuki, Seki

    1994-07-01

    By adding ethanol gas to oxygen-based chemistry, the controllability of resist profile and the overetch characteristic, under the condition with nearly no areas of material to be etched (etchable area), are improved. A model for resist profile control in which the resist profile is determined by the ratio of the sum of the isotropic etching component and the isotropic deposition component to the anisotropic etching component, is examined by evaluating the dependence of the resist profile and the etching rate on gas composition, the product of ion energy and ion current density (ion impact), and line and space (L & S) width. Both the gas composition and L & S width affect the sum of isotropic components. Ion impact affects the anisotropic etching component. When the isotropic components are balanced, resist profile is independent of ion impact and L & S width.

  5. NO gas loss from biologically crusted soils in Canyonlands National Park, Utah

    USGS Publications Warehouse

    Barger, N.N.; Belnap, J.; Ojima, D.S.; Mosier, A.

    2005-01-01

    In this study, we examined N gas loss as nitric oxide (NO) from N-fixing biologically crusted soils in Canyonlands National Park, Utah. We hypothesized that NO gas loss would increase with increasing N fixation potential of the biologically crusted soil. NO fluxes were measured from biologically crusted soils with three levels of N fixation potential (Scytonema-Nostoc-Collema spp. (dark)>Scytonema-Nostoc-Microcoleus spp. (medium)>Microcoleus spp. (light)) from soil cores and field chambers. In both cores and field chambers there was a significant effect of crust type on NO fluxes, but this was highly dependent on season. NO fluxes from field chambers increased with increasing N fixation potential of the biologically crusted soils (dark>medium>light) in the summer months, with no differences in the spring and autumn. Soil chlorophyllasis Type a content (an index of N fixation potential), percent N, and temperature explained 40% of the variability in NO fluxes from our field sites. Estimates of annual NO loss from dark and light crusts was 0.04-0.16 and 0.02-0.11-N/ha/year. Overall, NO gas loss accounts for approximately 3-7% of the N inputs via N fixation in dark and light biologically crusted soils. Land use practices have drastically altered biological soil crusts communities over the past century. Livestock grazing and intensive recreational use of public lands has resulted in a large scale conversion of dark cyanolichen crusts to light cyanobacterial crusts. As a result, changes in biologically crusted soils in arid and semi-arid regions of the western US may subsequently impact regional NO loss. ?? Springer 2005.

  6. Oxygen speciation in upgraded fast pyrolysis bio-oils by comprehensive two-dimensional gas chromatography.

    PubMed

    Omais, Badaoui; Crepier, Julien; Charon, Nadège; Courtiade, Marion; Quignard, Alain; Thiébaut, Didier

    2013-04-21

    Biomass fast pyrolysis is considered as a promising route to produce liquid for the transportation field from a renewable resource. However, the derived bio-oils are mainly oxygenated (45-50%w/w O on a wet basis) and contain almost no hydrocarbons. Therefore, upgrading is necessary to obtain a liquid with lower oxygen content and characterization of oxygenated compounds in these products is essential to assist conversion reactions. For this purpose, comprehensive two-dimensional gas chromatography (GC × GC) can be investigated. Oxygen speciation in such matrices is hampered by the large diversity of oxygenated families and the complexity of the hydrocarbon matrix. Moreover, response factors must be taken into account for oxygenate quantification as the Flame Ionisation Detector (FID) response varies when a molecule contains heteroatoms. To conclude, no distillation cuts were accessible and the analysis had to cover a large range of boiling points (30-630 °C). To take up this analytical challenge, a thorough optimization approach was developed. In fact, four GC × GC column sets were investigated to separate oxygenated compounds from the hydrocarbon matrix. Both model mixtures and the upgraded biomass flash pyrolysis oil were injected using GC × GC-FID to reach a suitable chromatographic separation. The advantages and drawbacks of each column combination for oxygen speciation in upgraded bio-oils are highlighted in this study. Among the four sets, an original polar × semi-polar column combination was selected and enabled the identification by GC × GC-ToF/MS of more than 40 compounds belonging to eight chemical families: ketones, furans, alcohols, phenols, carboxylic acids, guaiacols, anisols, and esters. For quantification purpose, the GC × GC-FID chromatogram was divided into more than 60 blobs corresponding to the previously identified analyte and hydrocarbon zones. A database associating each blob to a molecule and its specific response factor (determined

  7. Generating singlet oxygen bubbles: a new mechanism for gas-liquid oxidations in water.

    PubMed

    Bartusik, Dorota; Aebisher, David; Ghafari, BiBi; Lyons, Alan M; Greer, Alexander

    2012-02-01

    Laser-coupled microphotoreactors were developed to bubble singlet oxygen [(1)O(2) ((1)Δ(g))] into an aqueous solution containing an oxidizable compound. The reactors consisted of custom-modified SMA fiberoptic receptacles loaded with 150 μm silicon phthalocyanine glass sensitizer particles, where the particles were isolated from direct contact with water by a membrane adhesively bonded to the bottom of each device. A tube fed O(2) gas to the reactor chambers. In the presence of O(2), singlet oxygen was generated by illuminating the sensitizer particles with 669 nm light from an optical fiber coupled to the top of the reactor. The generated (1)O(2) was transported through the membrane by the O(2) stream and formed bubbles in solution. In solution, singlet oxygen reacted with probe compounds (9,10-anthracene dipropionate dianion, trans-2-methyl-2-pentanoate anion, N-benzoyl-D,L-methionine, or N-acetyl-D,L-methionine) to give oxidized products in two stages. The early stage was rapid and showed that (1)O(2) transfer occurred via bubbles mainly in the bulk water solution. The later stage was slow; it arose only from (1)O(2)-probe molecule contact at the gas/liquid interface. A mechanism is proposed that involves (1)O(2) mass transfer and solvation, where smaller bubbles provide better penetration of (1)O(2) into the flowing stream due to higher surface-to-volume contact between the probe molecules and (1)O(2). PMID:22260325

  8. Hydrogen production from simulated hot coke oven gas by using oxygen-permeable ceramics

    SciTech Connect

    Hongwei Cheng; Yuwen Zhang; Xionggang Lu; Weizhong Ding; Qian Li

    2009-01-15

    Hydrogen production from simulated hot coke oven gas (HCOG) was investigated in a BaCo{sub 0.7}Fe{sub 0.2}Nb{sub 0.1}O{sub 3-{delta}} (BCFNO) membrane reactor combined with a Ni/Mg(Al)O catalyst by the partial oxidation with toluene as a model tar compound under atmospheric pressure. The reaction results indicated that toluene was completely converted to H{sub 2} and CO in the catalytic reforming of the simulated HCOG in the temperature range from 825 to 875{sup o}C. Both thermodynamically predicated values and experimental data showed that the selective oxidation of toluene took precedence over that of CH{sub 4} in the reforming reaction. At optimized reaction conditions, the dense oxygen-permeable membrane has an oxygen permeation flux around 12.3 mL cm{sup -2} min{sup -1}, and a CH{sub 4} conversion of 86%, a CO{sub 2} conversion of 99%, a H{sub 2} yield of 88%, and a CO yield of 87% have been achieved. When the toluene and methane were reformed, the amount of H{sub 2} in the reaction effluent gas was about 2 times more than that of original H{sub 2} in simulated HCOG. The results reveal that it is feasible for hydrogen production from HCOG by reforming hydrocarbon compounds in a ceramic oxygen-permeable membrane reactor. 27 refs., 10 figs., 3 abs.

  9. Evaluation of a subsurface oxygenation technique using colloidal gas aphron injections into packed column reactors

    SciTech Connect

    Wills, R.A.; Coles, P.

    1991-11-01

    Bioremediation may be a remedial technology capable of decontaminating subsurface environments. The objective of this research was to evaluate the use of colloidal gas aphron (CGA) injection, which is the injection of micrometer-size air bubbles in an aqueous surfactant solution, as a subsurface oxygenation technique to create optimal growth conditions for aerobic bacteria. Along with this, the capability of CGAs to act as a soil-washing agent and free organic components from a coal tar-contaminated matrix was examined. Injection of CGAs may be useful for remediation of underground coal gasification (UCG) sites. Because of this, bacteria and solid material from a UCG site located in northeastern Wyoming were used in this research. Colloidal gas aphrons were generated and pumped through packed column reactors (PCRS) containing post-burn core materials. For comparison, PCRs containing sand were also studied. Bacteria from this site were tested for their capability to degrade phenol, a major contaminant at the UCG site, and were also used to bioaugment the PCR systems. In this study we examined: (1) the effect of CGA injection on dissolved oxygen concentrations in the PCR effluents, (2) the effect of CGA, H[sub 2]O[sub 2], and phenol injections on bacterial populations, (3) the stability and transport of CGAs over distance, and (4) CGA injection versus H[sub 2]O[sub 2] injection as an oxygenation technique.

  10. Evaluation of a subsurface oxygenation technique using colloidal gas aphron injections into packed column reactors

    SciTech Connect

    Wills, R.A.; Coles, P.

    1991-11-01

    Bioremediation may be a remedial technology capable of decontaminating subsurface environments. The objective of this research was to evaluate the use of colloidal gas aphron (CGA) injection, which is the injection of micrometer-size air bubbles in an aqueous surfactant solution, as a subsurface oxygenation technique to create optimal growth conditions for aerobic bacteria. Along with this, the capability of CGAs to act as a soil-washing agent and free organic components from a coal tar-contaminated matrix was examined. Injection of CGAs may be useful for remediation of underground coal gasification (UCG) sites. Because of this, bacteria and solid material from a UCG site located in northeastern Wyoming were used in this research. Colloidal gas aphrons were generated and pumped through packed column reactors (PCRS) containing post-burn core materials. For comparison, PCRs containing sand were also studied. Bacteria from this site were tested for their capability to degrade phenol, a major contaminant at the UCG site, and were also used to bioaugment the PCR systems. In this study we examined: (1) the effect of CGA injection on dissolved oxygen concentrations in the PCR effluents, (2) the effect of CGA, H{sub 2}O{sub 2}, and phenol injections on bacterial populations, (3) the stability and transport of CGAs over distance, and (4) CGA injection versus H{sub 2}O{sub 2} injection as an oxygenation technique.

  11. A biological loss of endosulfan and related chlorinated organic compounds from aqueous systems in the presence and absence of oxygen.

    PubMed

    Guerin, T F

    2001-01-01

    Endosulfan is a cyclodiene organochlorine currently widely used as an insecticide throughout the world. This study reports that the endosulfan isomers can be readily dissipated from aqueous systems at neutral pH in the absence of biological material or chemical catalysts, in the presence or absence of oxygen. The study showed that aldrin, dieldrin, and endosulfan exhibit bi-phasic loss from water in unsealed and butyl rubber sealed vessels. Half-lives are substantially increased for endosulfan I when oxygen is removed from the incubation vessel. The study conditions, where PTFE was used, were such that loss due to volatilization and alkaline chemical hydrolysis was eliminated. Half-lives determined from these data indicate that the parent isomers are much less persistent than the related cyclodienes, aldrin and dieldrin, confirming the findings of previous studies. The major oxidation product of endosulfans I and II, endosulfan sulfate, is less volatile and can persist longer than either of the parent isomers. Endosulfan sulfate was not formed in any of the treatments suggesting that it would not be formed in aerated waters in the absence of microbial activity or strong chemical oxidants. Since endosulfan sulfate is formed in many environments through biological oxidation, and is only slowly degraded (both chemically in sterile media and biologically), it represents a predominant residue of technical grade endosulfan, which finds its way into aerobic and anaerobic aquatic environments. The data obtained contributes to and confirms the existing body of half-life data on endosulfan I and II and its major oxidation product, endosulfan sulfate. The half-life data generated from the current study can be used in models for predicting the loss of chlorinated cyclodiene compounds from aqueous systems. The findings also highlight the importance of critically reviewing half-life data, to determine what the predominant processes are that are acting on the compounds under

  12. Role of gas exchange in the inorganic carbon, oxygen, and /sup 222/Rn budgets of the Amazon River

    SciTech Connect

    Devol, A.H.; Quay, P.D.; Richey, J.E.; Martinelli, L.A.

    1987-01-01

    Dissolved oxygen, /sup 222/Rn, pCO/sub 2/, alkalinity, respiration rate, and discharge have been measured at eight mainstem and seven tributary stations during February-March 1984 in a 1700-km stretch of the Amazon River between Vargem Grande and Obidos in Brazil. Air-water gas exchange rates were estimated two ways: measurements of the flux of /sup 222/Rn int floating domes yielded an average boundary layer thickness of 78..mu..m, and oxygen mass balance calculations resulted in an average of 38..mu..m. Given a boundary layer thickness on the order of 50..mu..m, CO/sub 2/ loss to the atmosphere in the entire reach would have been 37.4 kmol s/sup -1/, which is about equal to the total tributary dissolved inorganic carbon (DIC) input and is about half of the total fluvial DIC input to the section. Thus, CO/sub 2/ evasion is a major component of Amazon River DIC balance. Because gas exchange within the section was rapid relative to water travel time through the section, a quasi-steady state was maintained between respiratory input and evasion of CO/sub 2/. Dissolved /sup 222/Rn activities in the mainstem varied from 3.5 to 8.3 dpm liter/sup -1/ and were always highly supersaturated with respect to the atmosphere. Dissolved radon was also not supported by decay of /sup 222/Ra in the mainstem. A /sup 222/Rn mass balance indicated that direct groundwater input into this stretch of the Amazon mainstem probably accounted for no more than 1% of water discharge.

  13. Oxygen Loss from Venus and the Influence of Extreme Solar Wind Conditions

    NASA Astrophysics Data System (ADS)

    McEnulty, Tess Rose

    2012-06-01

    The purpose of this dissertation is to expand our understanding of oxygen ion escape to space from Venus and its dependence on extreme solar wind conditions found during interplanetary coronal mass ejections (ICMEs). The solar wind dynamic pressure outside of the Venus bow shock did not exceed ˜12 nPa, during 2006-2009, while the solar wind dynamic pressure was higher than this for ˜10% of the time during the PVO mission. Oxygen ions escape Venus through multiple regions near the planet. One of these regions is the magnetosheath, where high energy pick-up ions are accelerated by the solar wind convection electric field. High energy (>1 keV) O+ pick-up ions within the Venus magnetosheath reached higher energy at lower altitude when the solar wind was disturbed by ICMEs compared to pick-up ions when the external solar wind was not disturbed, between 2006-2007. However, the count rate of O+ was not obviously affected by the ICMEs during this time period. In addition to high energy pick-up ions, VEX also detects low energy (˜10-100 eV) O+ within the ionosphere and wake of Venus. These low energy oxygen ions are difficult to interpret, because the spacecraft's relative velocity and potential can significantly affect the measured energy. If VEX ion data is not corrected for the spacecraft's relative velocity and potential, gravitationally bound O+ could be misinterpreted as escaping. These gravitationally bound oxygen ions can extend on the nightside to ˜-2 Venus radii and may even return to the planet after reaching high altitudes in the wake. Gravitationally bound ions will lower the total O+ escape estimated from Venus if total escape is calculated including these ions. However, if the return flux is low compared to the total escaping outflow, this effect is not significant. An ICME with a dynamic pressure of 17.6 nPa impacted Venus on November 11, 2011. During this ICME, the high energy pick-up O+ and the low energy O+ ions were affected. Oxygen ions in the

  14. Oxygen Effects on Thermophilic Microbial Populations in Biofilters Treating Nitric Oxide Containing Off-Gas Streams

    SciTech Connect

    Lee, Brady Douglas; Apel, William Arnold; Smith, William Aaron

    2004-04-01

    Electricity generation from coal has increased by an average of 51 billion kWh per year over the past 3 years. For this reason cost-effective strategies to control nitrogen oxides (NOx) from coal-fired power plant combustion gases must be developed. Compost biofilters operated at 55°C at an empty bed contact time (EBCT) of 13 seconds were shown to be feasible for removal of nitric oxide (NO) from synthetic flue gas. Denitrifying microbial populations in these biofilters were shown to reduce influent NO feeds by 90 to 95% at inlet NO concentrations of 500 ppmv. Oxygen was shown to have a significant effect on the NO removal efficiency demonstrated by these biofilters. Two biofilters were set up under identical conditions for the purpose of monitoring NO removal as well as changes in the microbial population in the bed medium under anaerobic and aerobic conditions. Changes in the microbial population were monitored to determine the maximum oxygen tolerance of a denitrifying biofilter as well as methods of optimizing microbial populations capable of denitrification in the presence of low oxygen concentrations. Nitric oxide removal dropped to between 10 and 20% when oxygen was present in the influent stream. The inactive compost used to pack the biofilters may have also caused the decreased NO removal efficiency compared to previous biofiltration experiments. Analysis of the bed medium microbial population using environmental scanning electron microscopy indicated significant increases in biomass populating the surface of the compost when compared to unacclimated compost.

  15. Angular momentum loss of primordial gas in Lyα radiation field

    NASA Astrophysics Data System (ADS)

    Yajima, Hidenobu; Khochfar, Sadegh

    2014-06-01

    We present results on the radiation drag exerted by an isotropic and homogeneous background of Lyα photons on neutral gas clouds orbiting within H II regions around Population III stars of different masses. The Doppler shift causes a frequency difference between photons moving in the direction of the cloud and opposite to it resulting in a net momentum loss of the cloud in the direction of motion. We find that half of the angular momentum of gas with vθ ≲ 20 km s-1 near (r ≲ 3 kpc) a Population III star of 120 M⊙ at z = 20 is lost within ˜106 yr. The radiation drag is a strong function of cloud velocity that peaks at v ˜ 20 km s-1 reflecting the frequency dependence of the photon cross-section. Clouds moving with velocities larger than ˜100 km s-1 lose their angular momentum on time-scales of ˜108 yr. At lower redshifts radiation drag becomes inefficient as the Lyα photon density in H II regions decreases by a factor (1 + z)3 and angular momentum is lost on time-scales ≳ 108 yr even for low-velocity clouds. Our results suggest that a sweet spot exists for the loss of angular momentum by radiation drag for gas clouds at z > 10 and with v ˜ 20 km s-1. Comparison to dynamical friction forces acting on typical gas clouds suggest that radiation drag is the dominant effect impacting the orbit. We propose that this effect can suppress the formation of extended gas discs in the first galaxies and help gas accretion near galactic centres and central black holes.

  16. The effects of oxygen induced pulmonary vasoconstriction on bedside measurement of pulmonary gas exchange.

    PubMed

    Weinreich, Ulla M; Thomsen, Lars P; Rees, Stephen E; Rasmussen, Bodil S

    2016-04-01

    In patients with respiratory failure measurements of pulmonary gas exchange are of importance. The bedside automatic lung parameter estimator (ALPE) of pulmonary gas exchange is based on changes in inspired oxygen (FiO2) assuming that these changes do not affect pulmonary circulation. This assumption is investigated in this study. Forty-two out of 65 patients undergoing coronary artery bypass grafting (CABG) had measurements of mean pulmonary arterial pressure (MPAP), cardiac output and pulmonary capillary wedge pressure thus enabling the calculation of pulmonary vascular resistance (PVR) at each FiO2 level. The research version of ALPE was used and FiO2 was step-wise reduced a median of 0.20 and ultimately returned towards baseline values, allowing 6-8 min' steady state period at each of 4-6 levels before recording the oxygen saturation (SpO2). FiO2 reduction led to median decrease in SpO2 from 99 to 92 %, an increase in MPAP of 4 mmHg and an increase in PVR of 36 dyn s cm(-5). Changes were immediately reversed on returning FiO2 towards baseline. In this study changes in MPAP and PVR are small and immediately reversible consistent with small changes in pulmonary gas exchange. This indicates that mild deoxygenation induced pulmonary vasoconstriction does not have significant influences on the ALPE parameters in patients after CABG. PMID:25962614

  17. Gas Transport Resistance in Polymer Electrolyte Thin Films on Oxygen Reduction Reaction Catalysts.

    PubMed

    Liu, Hang; Epting, William K; Litster, Shawn

    2015-09-15

    Significant reductions in expensive platinum catalyst loading for the oxygen reduction reaction are needed for commercially viable fuel cell electric vehicles as well as other important applications. In reducing loading, a resistance at the Pt surface in the presence of thin perfluorosulfonic acid (PFSA) electrolyte film, on the order of 10 nm thick, becomes a significant barrier to adequate performance. However, the resistance mechanism is unresolved and could be due to gas dissolution kinetics, increased diffusion resistance in thin films, or electrolyte anion interactions. A common hypothesis for the origin of the resistance is a highly reduced oxygen permeability in the thin polymer electrolyte films that coat the catalyst relative to bulk permeability that is caused by nanoscale confinement effects. Unfortunately, the prior work has not separated the thin-film gas transport resistance from that associated with PFSA interactions with a polarized catalyst surface. Here, we present the first characterization of the thin-film O2 transport resistance in the absence of a polarized catalyst, using a nanoporous substrate that geometrically mimics the active catalyst particles. Through a parametric study of varying PFSA film thickness, as thin as 50 nm, we observe no enhanced gas transport resistance in thin films as a result of either interfacial effects or structural changes in the PFSA. Our results suggest that other effects, such as anion poisoning at the Pt catalyst, could be the source of the additional resistance observed at low Pt loading. PMID:26299282

  18. EDTA-Decorated Nanostructured ZnO/CdS Thin Films for Oxygen Gas Sensing Applications

    NASA Astrophysics Data System (ADS)

    Arunraja, L.; Thirumoorthy, P.; Karthik, A.; Rajendran, V.; Edwinpaul, L.

    2016-08-01

    ZnO/CdS and ZnO/CdS-EDTA nanostructured thin films were prepared on a glass substrate using spin-coating and used for oxygen gas sensor applications. The structural properties of both ZnO/CdS and ZnO/CdS-EDTA nanostructured composites were comparatively characterized. The nanostructure thin film was found in a hexagonal structure with an average crystallite size reduced from 77 nm to 29 nm due to the influence of the EDTA. The optical absorption, photo luminescence, functional groups and surface morphology of the nanostructured thin films were comprehensively investigated. Oxygen was suitably tailored to verify the sensor response over a concentration range of 10-50 ppm at room temperature. Thus, the sensor studies reveal that the performance, response, and recovery time were enhanced in ZnO/CdS-EDTA nanostructured thin film compared with ZnO/CdS.

  19. Numerical investigation of oxygen impurity distribution during multicrystalline silicon crystal growth using a gas flow guidance device

    NASA Astrophysics Data System (ADS)

    Teng, Ying-Yang; Chen, Jyh-Chen; Lu, Chung-Wei; Chen, Chi-Yung

    2012-12-01

    Oxygen is one of the most important types of impurities that can cause thermal donor or light-induced degradation in mc-Si solar cells. The objective of this study is to investigate the effect that installing a gas flow guidance device in a mc-Si crystal-growth furnace would have on the oxygen impurity distribution in the melt during the growth process. The installation of such a gas flow guidance device can enhance the gas flow near the free surface, which would allow the argon to carry a greater amount of evaporated SiO gas outside the furnace. Furthermore, the enhanced motion of the gas flow also improves heat transfer near the free surface, which would make the melt vortex separate more easily. The separated melt vortex, which is located near the central region of the melt-crystal interface, directs any oxygen impurity towards the central region of the melt-crystal interface. This is why the oxygen concentration can be reduced by installing the gas flow guidance device. The effectiveness of the gas flow guidance device depends on the vertical distance between it and the free surface (h) as well as the gap between the crucible sidewall and the tip of the device (d). The effect on the oxygen concentration in the melt is significant when smaller values for h and d are adopted.

  20. Expiratory flow limitation and the response to breathing a helium-oxygen gas mixture in a canine model of pulmonary emphysema.

    PubMed Central

    Mink, S N

    1984-01-01

    The pathophysiology of reduced maximum expiratory flow in a canine model of pulmonary emphysema was studied, and the results interpreted in terms of the wave-speed theory of flow limitation. According to this theory, maximum expiratory flow is related both to the cross-sectional area and compliance at an airway site where a critical gas velocity is first reached ("choke-point") and to gas density. Pulmonary emphysema was produced by the repeated instillations of the enzyme papain into the airways of six dogs. In five control dogs, a saline solution was instilled. During forced vital capacity deflation, in an open-chest preparation, maximum expiratory flow, choke-point locations, and the response to breathing an 80:20 helium/oxygen gas mixture were determined at multiple lung volumes. To locate choke-points, a pressure measuring device was positioned in the airway to measure lateral and end-on intrabronchial pressures, from which the relevant wave-speed parameters were obtained. In general, the reduced maximum expiratory flow in emphysema can be explained by diminished lung elastic recoil pressure and by altered bronchial pressure-area behavior, which results in a more peripheral location of choke-points that have smaller cross-sectional areas than controls. With respect to the density dependence of maximum expiratory flow, this response did not differ from control values in four dogs with emphysema in which frictional pressure losses upstream from choke-points did not differ on the two gas mixtures. In two dogs with emphysema, however, upstream frictional pressure losses were greater on helium/oxygen than on air, which resulted in a smaller cross-sectional area on helium/oxygen; hence density dependence decreased. PMID:6715539

  1. Oxygen-induced plasticity in tracheal morphology and discontinuous gas exchange cycles in cockroaches Nauphoeta cinerea.

    PubMed

    Bartrim, Hamish; Matthews, Philip G D; Lemon, Sussan; White, Craig R

    2014-12-01

    The function and mechanism underlying discontinuous gas exchange in terrestrial arthropods continues to be debated. Three adaptive hypotheses have been proposed to explain the evolutionary origin or maintenance of discontinuous gas exchange cycles (DGCs), which may have evolved to reduce respiratory water loss, facilitate gas exchange in high CO2 and low O2 micro-environments, or to ameliorate potential damage as a result of oversupply of O2. None of these hypotheses have unequivocal support, and several non-adaptive hypotheses have also been proposed. In the present study, we reared cockroaches Nauphoeta cinerea in selected levels of O2 throughout development, and examined how this affected growth rate, tracheal morphology and patterns of gas exchange. O2 level in the rearing environment caused significant changes in tracheal morphology and the exhibition of DGCs, but the direction of these effects was inconsistent with all three adaptive hypotheses: water loss was not associated with DGC length, cockroaches grew fastest in hyperoxia, and DGCs exhibited by cockroaches reared in normoxia were shorter than those exhibited by cockroaches reared in hypoxia or hyperoxia. PMID:25378216

  2. Numerical simulation of operation processes in the combustion chamber and gas generator of oxygen-methane liquid rocket engine

    NASA Astrophysics Data System (ADS)

    Kalmykov, G. P.; Larionov, A. A.; Sidlerov, D. A.; Yanchilin, L. A.

    2009-09-01

    The results of numerical simulations of processes in gas generators and combustion chambers operating on oxygen and methane are presented. Specific features of mixing, evaporation, and combustion of propellants have been investigated. The degree of combustion completeness in chambers with three types of injectors - coaxial-jet gas-liquid, liquid-liquid monopropellant, and bipropellant impinging-jets injectors - has been estimated.

  3. Gas-potentiometric method with solid electrolyte oxygen sensors for the investigation of combustion.

    PubMed

    Lorenz, H; Tittmann, K; Sitzki, L; Trippler, S; Rau, H

    1996-09-01

    Gas-potentiometric analysis using oxide-ion-conducting solid electrolytes as stabilized zirconia is a worthwhile method for the investigation of combustion processes. In the case of gas and oil flames specific parameters like the flame contour, the degree of burn-out and mixing can be determined and information about flame turbulence and reaction density can be gained from the temporal resolution of the sensor signal. Measurements carried out with solid electrolyte oxygen sensors in a fluidized bed show that combustion processes of solid fuels are also analyzable. This analysis results in fuel specific burn-out curves finally leading to burn-out times and to parameters of a macrokinetics of the combustion process as well as to ideas about the burn-out mechanism. From the resulting constants of the effective reaction rate a reactivity relative to bituminous coal coke can be given for any solid fuel. PMID:15048356

  4. Effect of plant harvesting on the performance of constructed wetlands during winter: radial oxygen loss and microbial characteristics.

    PubMed

    Wang, Qian; Xie, Huijun; Zhang, Jian; Liang, Shuang; Ngo, Huu Hao; Guo, Wenshan; Liu, Chen; Zhao, Congcong; Li, Hao

    2015-05-01

    The aboveground tissue of plants is important for providing roots with constant photosynthetic resources. However, the aboveground biomass is usually harvested before winter to maintain the permanent removal of nutrients. In this work, the effects of harvest on plants' involvement in oxygen input as well as in microbial abundance and activity were investigated in detail. Three series of constructed wetlands with integrated plants ("unharvested"), harvested plants ("harvested"), and fully cleared plants ("cleared") were set up. Better performance was found in the unharvested units, with the radial oxygen loss (ROL) rates ranging from 0.05 to 0.59 μmol O₂/h/plant, followed by the harvested units that had relatively lower ROL rates (0.01 to 0.52 μmol O₂/h/plant). The cleared units had the lowest removal efficiency, which had no rhizome resources from the plants. The microbial population and activity were highest in the unharvested units, followed by the harvested and cleared units. Results showed that bacterial abundances and enhanced microbial activity were ten times higher on root surfaces compared with sands. These results indicate that late autumn harvesting of the aboveground biomass exhibited negative effects on plant ROL as well as on the microbial population and activity during the following winter. PMID:25520204

  5. Gas Loss by Ram Pressure Stripping and Internal Feedback from Low-mass Milky Way Satellites

    NASA Astrophysics Data System (ADS)

    Emerick, Andrew; Mac Low, Mordecai-Mark; Grcevich, Jana; Gatto, Andrea

    2016-08-01

    The evolution of dwarf satellites in the Milky Way (MW) is affected by a combination of ram pressure stripping (RPS), tidal stripping, and internal feedback from massive stars. We investigate gas loss processes in the smallest satellites of the MW using three-dimensional, high-resolution, idealized wind tunnel simulations, accounting for gas loss through both ram pressure stripping and expulsion by supernova feedback. Using initial conditions appropriate for a dwarf galaxy like Leo T, we investigate whether or not environmental gas stripping and internal feedback can quench these low-mass galaxies on the expected timescales, shorter than 2 Gyr. We find that supernova feedback contributes negligibly to the stripping rate for these low star formation rate galaxies. However, we also find that RPS is less efficient than expected in the stripping scenarios we consider. Our work suggests that although RPS can eventually completely strip these galaxies, other physics is likely at play to reconcile our computed stripping times with the rapid quenching timescales deduced from observations of low-mass MW dwarf galaxies. We discuss the roles additional physics may play in this scenario, including host-satellite tidal interactions, cored versus cuspy dark matter profiles, reionization, and satellite preprocessing. We conclude that a proper accounting of these physics together is necessary to understand the quenching of low-mass MW satellites.

  6. Methane, oxygen and nitrate fluxes in sediments hosting shallow gas hydrates at Hydrate Ridge

    NASA Astrophysics Data System (ADS)

    Sommer, S.; Pfannkuche, O.; Linke, P.; Gubsch, S.; Gust, G.; Greinert, J.; Drews, M.

    2003-04-01

    It is generally recognised that destabilisation of gas hydrates (GH) and the resulting release of methane may be one of the most powerful trigger mechanism on past abrupt climatic changes of the earth. However, information about turnover and fluxes of methane derived from marine hydrate deposits is still fragmentary. We employed a novel observatory to determine methane, oxygen and nitrate fluxes situ in water depths of 605 - 883 m at Hydrate Ridge, Cascadia convergent margin. Widespread bacterial mats of Beggiatoa sp. indicate presence of shallow GH located only a few centimetres below the sediment surface. When GH became buried deeper in the sediment, bivalve molluscs of the genus Calyptogena sp. form dense clam fields. Background measurements were conducted at sites not affected by shallow GH a few hundreds of meters away from the microbial mats and clam fields. During the employments, which lasted up to 36 h, measurements were conducted simultaneously in two benthic chambers. To avoid anoxia within one of the chambers, hitherto referred to as exchange chamber, total oxygen uptake (TOU) of the enclosed sediment community was artificially compensated. In the second chamber termed control chamber no oxygen supply took place. To account for effects of water flow on interfacial fluxes ambient water flow was replicated inside either chamber. At reference sites no injection of methane from the sediment into the water column was detected. TOU was low (1.5 mmol/m^2/d). At microbial mat sites TOU was extremely fast. In the control chambers oxygen was used up within less than 20 min, thus reliable calculations of TOU were not possible. Nitrate became almost depleted within 24 h. In the exchange chamber oxygen content was kept at the outside level, TOU of up to 53.4 mmol/m^2/d were measured. Methane efflux in the exchange chamber ranged from 0.5 to 0.8 mmol/m^2/d compared to methane fluxes of 1.9 to 10.1 mmol/m^2/d determined in control chambers. In an exchange chamber

  7. Diffusion of oxygen tracer into deuterium-gas-baked IrO{sub x}/Pb(Zr,TiO{sub 3})Pt capacitors and Pb(Zr,Ti)O{sub 3}Pt films

    SciTech Connect

    Cross, J.S.; Kurihara, K.; Haneda, H.

    2005-11-01

    Deuterium gas (D{sub 2}) ambient heat treatment of ferroelectric Pb(Zr,Ti)O{sub 3} (PZT) thin-film capacitors with a top electrode of iridium oxide and a bottom electrode of platinum showed significant polarization loss when baked at 200 deg. C at a pressure of 5 Torr. The D{sub 2} gas treatment of the capacitors partially reduced the iridium oxide (IrO{sub x}, where x is 1oxygen ({sup 16}O{sub 2}) and oxygen tracer ({sup 18}O{sub 2}) gases which recovered the ferroelectric properties and the D concentration in the PZT decreased to the detection level of 10{sup 17} at./cm{sup 3}. The oxygen tracer concentration was highest in the IrO{sub x} film and much lower in the PZT. Comparison of the oxygen tracer SIMS profiles of the PZT annealed in tracer oxygen or preannealed in oxygen followed by oxygen tracer annealing showed little difference in the calculated PZT oxygen tracer diffusion coefficient of 5x10{sup -15} cm{sup 2}/s. If the PZT was reduced by the D{sub 2} gas, an increase in the oxygen diffusion coefficient would be expected as has been proposed in the literature, but this was not observed experimentally. These results indicate that the loss of polarization in the PZT capacitor is primarily due to the inhibition of ferroelectric domain switching by possible formation of [OD{sup -}].

  8. 40 CFR 62.15200 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 62.15200 Section 62.15200 Protection of Environment... I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your...

  9. 40 CFR 60.1255 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1255 Section 60.1255 Protection of Environment... Continuous Emission Monitoring § 60.1255 What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during...

  10. 40 CFR 60.1255 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1255 Section 60.1255 Protection of Environment... Continuous Emission Monitoring § 60.1255 What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during...

  11. 40 CFR 60.1745 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1745 Section 60.1745 Protection of Environment... choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your continuous emission...

  12. 40 CFR 60.1745 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1745 Section 60.1745 Protection of Environment... choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your continuous emission...

  13. 40 CFR 60.1255 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1255 Section 60.1255 Protection of Environment... Continuous Emission Monitoring § 60.1255 What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during...

  14. 40 CFR 60.1745 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1745 Section 60.1745 Protection of Environment... choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your continuous emission...

  15. 40 CFR 62.15200 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 62.15200 Section 62.15200 Protection of Environment... I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your...

  16. 40 CFR 62.15200 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 62.15200 Section 62.15200 Protection of Environment... I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your...

  17. 40 CFR 62.15200 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 62.15200 Section 62.15200 Protection of Environment... I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your...

  18. 40 CFR 60.1255 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1255 Section 60.1255 Protection of Environment... Continuous Emission Monitoring § 60.1255 What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during...

  19. 40 CFR 62.15200 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 62.15200 Section 62.15200 Protection of Environment... I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your...

  20. 40 CFR 60.1255 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1255 Section 60.1255 Protection of Environment... Continuous Emission Monitoring § 60.1255 What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during...

  1. 40 CFR 60.1745 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1745 Section 60.1745 Protection of Environment... choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your continuous emission...

  2. 40 CFR 60.1745 - What must I do if I choose to monitor carbon dioxide instead of oxygen as a diluent gas?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... carbon dioxide instead of oxygen as a diluent gas? 60.1745 Section 60.1745 Protection of Environment... choose to monitor carbon dioxide instead of oxygen as a diluent gas? You must establish the relationship between oxygen and carbon dioxide during the initial evaluation of your continuous emission...

  3. BLOOD SUBSTITUTES: EVOLUTION FROM NON-CARRYING TO OXYGEN AND GAS CARRYING FLUIDS

    PubMed Central

    Cabrales, Pedro; Intaglietta, Marcos

    2013-01-01

    The development of oxygen (O2) carrying blood substitutes has evolved from the goal of replicating blood O2 transports properties to that of preserving microvascular and organ function, reducing the inherent or potential toxicity of the material used to carry O2, and treating pathologies initiated by anemia and hypoxia. Furthermore, the emphasis has shifted from blood replacement fluid to “O2 therapeutics” that restore tissue oxygenation to specific tissues regions. This review covers the different alternatives, potential and limitations of hemoglobin based O2 carriers (HBOCs) and perfluorocarbon based O2 carriers (PFCOCs), with emphasis on the physiological conditions disturbed in the situation that they will be used. It describes how concepts learned from plasma expanders without O2 carrying capacity can be applied to maintain O2 delivery and summarizes the microvascular responses due to HBOCs and PFCOCs. This review also presents alternative applications of HBOCs and PFCOCs namely: 1) How HBOC O2 affinity can be engineered to target O2 delivery to hypoxic tissues; and 2) How the high gas solubility of PFCOCs provides new opportunities for carrying, dissolving and delivering gases with biological activity. It is concluded that current blood substitutes development has amplified their applications horizon by devising therapeutic functions for oxygen carriers requiring limited O2 delivery capacity restoration. Conversely, full, blood-like O2 carrying capacity re-establishment awaits control of O2 carrier toxicity. PMID:23820271

  4. 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.

  5. Optical Absorptions of Oxygenated Carbon Chain Cations in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Hardy, F.-X.; Rice, C. A.; Chakraborty, A.; Fulara, J.; Maier, J. P.

    2016-06-01

    The gas-phase electronic spectra of linear OC4O+ and a planar C6H2O+ isomer were obtained at a rotational temperature of ≈10 K. Absorption measurements in a 6 K neon matrix were followed by gas-phase observations in a cryogenic radiofrequency ion trap. The origin bands of the 1{}2{{{\\Pi }}}u ≤ftarrow X{}2{{{\\Pi }}}g transition of OC4O+ and the 1{}2A{}2 ≤ftarrow X{}2B1 of HCCC(CO)CCH+ lie at 417.31 ± 0.01 nm and 523.49 ± 0.01 nm, respectively. These constitute the first electronic spectra of oxygenated carbon chain cations studied under conditions that are relevant to the diffuse interstellar bands (DIBs), as both have a visible transition. The recent analysis of the 579.5 nm DIB indicates that small carriers, five to seven heavy atoms, continue to be possible candidates (Huang & Oka 2015). Astronomical implications are discussed regarding this kind of oxygenated molecules.

  6. Oxygen convective uptakes in gas exchange cycles in early diapause pupae of Pieris brassicae.

    PubMed

    Jõgar, Katrin; Kuusik, Aare; Ploomi, Angela; Metspalu, Luule; Williams, Ingrid; Hiiesaar, Külli; Kivimägi, Irja; Mänd, Marika; Tasa, Tea; Luik, Anne

    2011-09-01

    Oxygen convective uptakes in gas exchange cycles were directly recorded in early diapause pupae of Pieris brassicae L. (Lepidoptera; Pieridae) by means of O2 coulometric respirometry. This method was combined with flow-through CO2 respirometry, the two systems being switchable one to the other. During recording with both systems, measurements were also taken with infrared actography. The pupae displayed short discontinuous gas exchange cycles lasting 40-70 min. No true C phase was found by flow-through measurements; instead, flutter opening of the spiracles with discrete convective O2 uptakes began shortly after the O phase whereas CO2 release was suppressed by the inward directed passive suction ventilation. The F phase was characterized by a series of small CO2 bursts (flutter events). Between these bursts, novel sub-phase `miniflutter' was observed, which consisted of six to 10 miniature inspirations without any CO2 emission. During the flow-through measurements, oxygen convective uptakes were indirectly recorded by the infrared actograph as sudden extensions (lengthening) of the abdominal segments at each spiracular microopening. PMID:21832124

  7. Experimentally-determined external heat loss of automotive gas turbine engine

    NASA Technical Reports Server (NTRS)

    Meng, P. R.; Wulf, R. F.

    1975-01-01

    An external heat balance was conducted on a 150 HP two-shaft automotive gas turbine engine. The engine was enclosed in a calorimeter box and the temperature change of cooling air passing through the box was measured. Cooling airflow ranges of 1.6 to 2.1 lb-per-second and 0.8 to 1.1 lb-per-second were used. The engine housing heat loss increased as the cooling airflow through the calorimeter box was increased, as would be the case in a moving automobile. The heat balance between the total energy input and the sum of shaft power output and various losses compared within 30 percent at engine idle speeds and within 7 percent at full power.

  8. An improved computer model for prediction of axial gas turbine performance losses

    NASA Technical Reports Server (NTRS)

    Jenkins, R. M.

    1984-01-01

    The calculation model performs a rapid preliminary pitchline optimization of axial gas turbine annular flowpath geometry, as well as an initial estimate of blade profile shapes, given only a minimum of thermodynamic cycle requirements. No geometric parameters need be specified. The following preliminary design data are determined: (1) the optimum flowpath geometry, within mechanical stress limits; (2) initial estimates of cascade blade shapes; and (3) predictions of expected turbine performance. The model uses an inverse calculation technique whereby blade profiles are generated by designing channels to yield a specified velocity distribution on the two walls. Velocity distributions are then used to calculate the cascade loss parameters. Calculated blade shapes are used primarily to determine whether the assumed velocity loadings are physically realistic. Model verification is accomplished by comparison of predicted turbine geometry and performance with an array of seven NASA single-stage axial gas turbine configurations.

  9. Blade loss transient dynamics analysis, volume 1. Task 1: Survey and perspective. [aircraft gas turbine engines

    NASA Technical Reports Server (NTRS)

    Gallardo, V. C.; Gaffney, E. F.; Bach, L. J.; Stallone, M. J.

    1981-01-01

    An analytical technique was developed to predict the behavior of a rotor system subjected to sudden unbalance. The technique is implemented in the Turbine Engine Transient Rotor Analysis (TETRA) computer program using the component element method. The analysis was particularly aimed toward blade-loss phenomena in gas turbine engines. A dual-rotor, casing, and pylon structure can be modeled by the computer program. Blade tip rubs, Coriolis forces, and mechanical clearances are included. The analytical system was verified by modeling and simulating actual test conditions for a rig test as well as a full-engine, blade-release demonstration.

  10. Generating Singlet Oxygen Bubbles: A New Mechanism for Gas-Liquid Oxidations in Water

    PubMed Central

    Bartusik, Dorota; Aebisher, David; Ghafari, BiBi

    2012-01-01

    Laser-coupled microphotoreactors were developed to bubble singlet oxygen [1O2 (1Δg)] into an aqueous solution containing an oxidizable compound. The reactors consisted of custom-modified SMA fiber-optic receptacles loaded with 150-μm silicon phthalocyanine glass sensitizer particles, where the particles were isolated from direct contact with water by a membrane adhesively bonded to the bottom of each device. A tube fed O2 gas to the reactor chambers. In the presence of O2, singlet oxygen was generated by illuminating the sensitizer particles with 669-nm light from an optical fiber coupled to the top of the reactor. The generated 1O2 was transported through the membrane by the O2 stream and formed bubbles in solution. In solution, singlet oxygen reacted with probe compounds (either 9,10-anthracene dipropionate dianion, trans-2-methyl-2-pentanoate anion, N-benzoyl-D,L-methionine, and N-acetyl-D,L-methionine) to give oxidized products in two stages. The early stage was rapid and showed that 1O2 transfer occurred via bubbles mainly in the bulk water solution. The later stage was slow, it arose only from 1O2-probe molecule contact at the gas/liquid interface. A mechanism is proposed that involves 1O2 mass transfer and solvation, where smaller bubbles provide better penetration of 1O2 into the flowing stream due to higher surface-to-volume contact between the probe molecules and 1O2. PMID:22260325

  11. Three-dimensional Hydrodynamical Simulations of the Supernovae-driven Gas Loss in the Dwarf Spheroidal Galaxy Ursa Minor

    NASA Astrophysics Data System (ADS)

    Caproni, A.; Lanfranchi, G. A.; da Silva, A. Luiz; Falceta-Gonçalves, D.

    2015-06-01

    As is usual in dwarf spheroidal galaxies, today the Local Group galaxy Ursa Minor is depleted of its gas content. How this galaxy lost its gas is still a matter of debate. To study the history of gas loss in Ursa Minor, we conducted the first three-dimensional hydrodynamical simulations of this object, assuming that the gas loss was driven by galactic winds powered only by type II supernovae (SNe II). The initial gas setup and supernova (SN) rates used in our simulations are mainly constrained by the inferred star formation history and the observed velocity dispersion of Ursa Minor. After 3 Gyr of evolution, we found that the gas removal efficiency is higher when the SN rate is increased, and also when the initial mean gas density is lowered. The derived mass-loss rates are systematically higher in the central regions (\\lt 300 pc), even though such a relationship has not been strictly linear in time and in terms of the galactic radius. The filamentary structures induced by Rayleigh-Taylor instabilities and the concentric shells related to the acoustic waves driven by SNe can account for the inferred mass losses from the simulations. Our results suggest that SNe II are able to transfer most of the gas from the central region outward to the galactic halo. However, other physical mechanisms must be considered in order to completely remove the gas at larger radii.

  12. THE MASS-LOSS RETURN FROM EVOLVED STARS TO THE LARGE MAGELLANIC CLOUD. II. DUST PROPERTIES FOR OXYGEN-RICH ASYMPTOTIC GIANT BRANCH STARS

    SciTech Connect

    Sargent, Benjamin A.; Meixner, M.; Gordon, Karl D.; Srinivasan, S.; Kemper, F.; Woods, Paul M.; Tielens, A. G. G. M.; Speck, A. K.; Matsuura, M.; Bernard, J.-Ph.; Hony, S.; Marengo, M.; Sloan, G. C.

    2010-06-10

    We model multi-wavelength broadband UBVIJHK{sub s} and Spitzer IRAC and MIPS photometry and Infrared Spectrograph spectra from the SAGE and SAGE-Spectroscopy observing programs of two oxygen-rich asymptotic giant branch (O-rich AGB) stars in the Large Magellanic Cloud (LMC) using radiative transfer (RT) models of dust shells around stars. We chose a star from each of the bright and faint O-rich AGB populations found by earlier studies of the SAGE sample in order to derive a baseline set of dust properties to be used in the construction of an extensive grid of RT models of the O-rich AGB stars found in the SAGE surveys. From the bright O-rich AGB population, we chose HV 5715, and from the faint O-rich AGB population we chose SSTISAGE1C J052206.92-715017.6 (SSTSAGE052206). We found the complex indices of refraction of oxygen-deficient silicates from Ossenkopf et al. and a power law with exponential decay grain size distribution like what Kim et al. used but with {gamma} of -3.5, a {sub min} of 0.01 {mu}m, and a {sub 0} of 0.1 {mu}m to be reasonable dust properties for these models. There is a slight indication that the dust around the faint O-rich AGB may be more silica-rich than that around the bright O-rich AGB. Simple models of gas emission suggest a relatively extended gas envelope for the faint O-rich AGB star modeled, consistent with the relatively large dust shell inner radius for the same model. Our models of the data require the luminosity of SSTSAGE052206 and HV 5715 to be {approx}5100 L {sub sun} and {approx}36,000 L {sub sun}, respectively. This, combined with the stellar effective temperatures of 3700 K and 3500 K, respectively, that we find best fit the optical and near-infrared data, suggests stellar masses of {approx}3 M {sub sun} and {approx}7 M {sub sun}. This, in turn, suggests that HV 5715 is undergoing hot-bottom burning and that SSTSAGE052206 is not. Our models of SSTSAGE052206 and HV 5715 require dust shells of inner radius {approx}17 and

  13. Interaction of iron-copper mixed metal oxide oxygen carriers with simulated synthesis gas derived from steam gasification of coal

    SciTech Connect

    Siriwardane, Ranjani V.; Ksepko, Ewelina; Tian, Hanging

    2013-01-01

    The objective of this work was to prepare supported bimetallic Fe–Cu oxygen carriers and to evaluate their performance for the chemical-looping combustion (CLC) process with simulated synthesis gas derived from steam gasification of coal/air. Ten-cycle CLC tests were conducted with Fe–Cu oxygen carriers in an atmospheric thermogravimetric analyzer utilizing simulated synthesis gas derived from the steam gasification of Polish Janina coal and Illinois #6 coal as fuel. The effect of temperature on reaction rates, chemical stability, and oxygen transport capacity were determined. Fractional reduction, fractional oxidation, and global rates of reactions were calculated from the thermogravimetric analysis (TGA) data. The supports greatly affected reaction performance. Data showed that reaction rates and oxygen capacities were stable during the 10-cycle TGA tests for most Fe–Cu/support oxygen carriers. Bimetallic Fe–Cu/support oxygen carriers showed higher reduction rates than Fe-support oxygen carriers. The carriers containing higher Cu content showed better stabilities and better reduction rates. An increase in temperature from 800 °C to 900 °C did not have a significant effect on either the oxygen capacity or the reduction rates with synthesis gas derived from Janina coal. Oxidation reaction was significantly faster than reduction reaction for all supported Fe–Cu oxygen carriers. Carriers with higher Cu content had lower oxidation rates. Ten-cycle TGA data indicated that these oxygen carriers had stable performances at 800–900 °C and might be successfully used up to 900 °C for coal CLC reaction in the presence of steam.

  14. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet.

    PubMed

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T H; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  15. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-10-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment.

  16. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    PubMed Central

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  17. Performance of a Line Loss Correction Method for Gas Turbine Emission Measurements

    NASA Astrophysics Data System (ADS)

    Hagen, D. E.; Whitefield, P. D.; Lobo, P.

    2015-12-01

    International concern for the environmental impact of jet engine exhaust emissions in the atmosphere has led to increased attention on gas turbine engine emission testing. The Society of Automotive Engineers Aircraft Exhaust Emissions Measurement Committee (E-31) has published an Aerospace Information Report (AIR) 6241 detailing the sampling system for the measurement of non-volatile particulate matter from aircraft engines, and is developing an Aerospace Recommended Practice (ARP) for methodology and system specification. The Missouri University of Science and Technology (MST) Center for Excellence for Aerospace Particulate Emissions Reduction Research has led numerous jet engine exhaust sampling campaigns to characterize emissions at different locations in the expanding exhaust plume. Particle loss, due to various mechanisms, occurs in the sampling train that transports the exhaust sample from the engine exit plane to the measurement instruments. To account for the losses, both the size dependent penetration functions and the size distribution of the emitted particles need to be known. However in the proposed ARP, particle number and mass are measured, but size is not. Here we present a methodology to generate number and mass correction factors for line loss, without using direct size measurement. A lognormal size distribution is used to represent the exhaust aerosol at the engine exit plane and is defined by the measured number and mass at the downstream end of the sample train. The performance of this line loss correction is compared to corrections based on direct size measurements using data taken by MST during numerous engine test campaigns. The experimental uncertainty in these correction factors is estimated. Average differences between the line loss correction method and size based corrections are found to be on the order of 10% for number and 2.5% for mass.

  18. The role of metals and influence of oxygen on ceria supported copper-palladium bimetallic catalysts for the oxygen-assisted water-gas shift reaction

    NASA Astrophysics Data System (ADS)

    Fox, Elise Bickford

    This study was focused to investigate the roles of Cu and Pd in CuPd/CeO 2 bimetallic catalysts containing 30 wt% Cu and 1 wt% Pd used in the oxygen-assisted water-gas shift (OWGS) reaction employing combined bulk and surface characterization techniques such as X-ray diffraction (XRD), temperature programmed reduction (TPR), CO chemisorption, and in-situ X-ray photoelectron spectroscopy (XPS). The role of oxygen in aiding the water-gas shift reaction was also studied to determine an overall mechanism for the water-gas shift reaction. The catalytic activity for CO conversion and the stability of catalyst during on-stream operation increased upon adding Pd to Cu/CeO2 monometallic catalysts, especially when the OWLS reaction was performed under low temperatures. In-situ XPS studies of reduced catalysts showed the existence of Cu and Pd in their metallic states. The spectra also showed a shift in Cu 2p peaks toward lower binding energy with concommitant shift in the Pd 3d peaks toward higher BE. Addition of Pd decreased the surface Cu concentration while the concentration of Pd remained unaltered. The improved catalytic activity and stability of CuPd/CeO2 bimetallic catalyst was attributed to the Cu-Pd interaction. When the catalyst series was reduced in-situ under UHV conditions in the XPS chamber in order to better understand the metal-support interactions, it was found that the addition of 1%Pd to the Cu/CeO2 catalyst would greatly improve the reduction properties of the Cu and Ce under UHV conditions. When compared with results from the oxygen-assisted water-gas-shift reaction, it was found that the increased reduction from the addition of Pd aided in the reaction. When reaction kinetics of the water-gas shift and the oxygen-assisted water-gas shift reaction were examined, it was found that the addition of a small amount of air improved the overall reaction kinetics. In general, the activation energies decreased for the catalyst series when air was added to the

  19. Methane Emissions from Leak and Loss Audits of Natural Gas Compressor Stations and Storage Facilities.

    PubMed

    Johnson, Derek R; Covington, April N; Clark, Nigel N

    2015-07-01

    As part of the Environmental Defense Fund's Barnett Coordinated Campaign, researchers completed leak and loss audits for methane emissions at three natural gas compressor stations and two natural gas storage facilities. Researchers employed microdilution high-volume sampling systems in conjunction with in situ methane analyzers, bag samples, and Fourier transform infrared analyzers for emissions rate quantification. All sites had a combined total methane emissions rate of 94.2 kg/h, yet only 12% of the emissions total resulted from leaks. Methane slip from exhausts represented 44% of the total emissions. Remaining methane emissions were attributed to losses from pneumatic actuators and controls, engine crankcases, compressor packing vents, wet seal vents, and slop tanks. Measured values were compared with those reported in literature. Exhaust methane emissions were lower than emissions factor estimates for engine exhausts, but when combined with crankcase emissions, measured values were 11.4% lower than predicted by AP-42 as applicable to emissions factors for four-stroke, lean-burn engines. Average measured wet seal emissions were 3.5 times higher than GRI values but 14 times lower than those reported by Allen et al. Reciprocating compressor packing vent emissions were 39 times higher than values reported by GRI, but about half of values reported by Allen et al. Though the data set was small, researchers have suggested a method to estimate site-wide emissions factors for those powered by four-stroke, lean-burn engines based on fuel consumption and site throughput. PMID:26148551

  20. Loss-of-coolant accident experiment at the AVR gas-cooled reactor

    SciTech Connect

    Krueger, K. ); Cleveland, J. )

    1990-01-01

    A landmark safety test has been conducted at the AVR-reactor, a high-temperature gas-cooled reactor (HTGR) in the Federal Republic of Germany owned by the Arbeitsgemeinschaft Versuchsreaktor, AVR in Juelich. The 46-MW(t), 15-MW(e) AVR reactor was subjected to a simulated loss-of-coolant accident (LOCA), a very severe occurrence in which the coolant escapes from the reactor core and no emergency system provides coolant flow to the core. The test, which demonstrated the inherently safe response of this reactor to a LOCA, marked the first time ever that a reactor has been intentionally subjected to loss-of-coolant conditions without emergency cooling. Oak Ridge National Laboratory (ORNL) and General Atomics participated in the test by working with AVR staff by jointly performing the analyses needed to obtain the license to conduct the test and by performing post test analyses. This participation was carried out under the cooperative AVR Subprogram which is conducted within the US/FRG Agreement for Cooperation in Gas-Cooled Reactor Development. 7 figs.

  1. [Gas gangrene and hyperbaric oxygenation--a lesson forgotten or never learned?].

    PubMed

    Petri, Nadan M; Andrić, Dejan; Kovacević, Hasan; Vranjković-Petri, Lena; Racić, Goran; Mulić, Rosanda; Ropac, Darko

    2002-05-01

    Gas gangrene develops in devitalized hypoxic tissue. It spreads rapidly under strong influence of enzymes produced by the causing bacteria and often results in fatal outcome. It is of utmost importance to stop toxin production as soon as possible, which is most effectively achieved by early application of hyperbaric oxygenation (HBO2), as the first measure in a "trident" (HBO2, antibiotics, surgical measures). The paper reviews the most important data from microbiology, pathophysiology and epidemiology of gas gangrene, current clinical practice, scientific basis for application of HBO2 in the treatment of this disease, and data from the archives of the Naval Medical Institute of the Croatian Navy in Split (NMI). At the NMI, in the period from 1982 to 2000, HBO2 was administered in the treatment of 21 patients with gas gangrene, of average age 41.6 +/- 16.3 years. The average treatment consisted of 6.8 +/- 3.8 sessions. 13 (76%) patients were cured. PMID:12152414

  2. Drp1 loss-of-function reduces cardiomyocyte oxygen dependence protecting the heart from ischemia-reperfusion injury.

    PubMed

    Zepeda, Ramiro; Kuzmicic, Jovan; Parra, Valentina; Troncoso, Rodrigo; Pennanen, Christian; Riquelme, Jaime A; Pedrozo, Zully; Chiong, Mario; Sánchez, Gina; Lavandero, Sergio

    2014-06-01

    Mitochondria are key organelles for ATP production in cardiomyocytes, which is regulated by processes of fission and fusion. We hypothesized that the mitochondria fusion protein dynamin-related protein 1 (Drp1) inhibition, attenuates ischemia-reperfusion (I/R) injury through modifications in mitochondrial metabolism. Rats were subjected to I/R through coronary artery ligation, and isolated cardiomyocytes were treated with an ischemia-mimicking solution. In vivo, cardiac function, myocardial infarction area, and mitochondrial morphology were determined, whereas in vitro, viability, mitochondrial membrane potential, intracellular ATP levels, and oxygen consumption rate (OCR) were assessed. In both models, an adenovirus expressing Drp1 dominant-negative K38A (Drp1K38A) was used to induce Drp1 loss-of-function. Our results showed that I/R stimulated mitochondrial fission. Myocardial infarction size and cell death induced by I/R were significantly reduced, whereas cardiac function after I/R was improved in Drp1K38A-treated rats compared with controls. Drp1K38A-transduced cardiomyocytes showed lower OCR with no decrease in intracellular ATP levels, and on I/R, a larger decrease in OCR with a smaller reduction in intracellular ATP level was observed. However, proton leak-associated oxygen consumption was comparatively higher in Drp1K38A-treated cardiomyocytes, suggesting a protective mitochondrial uncoupling effect against I/R. Collectively, our results show that Drp1 inhibition triggers cardioprotection by reducing mitochondrial metabolism during I/R. PMID:24477044

  3. Composition surveys of test gas produced by a hydrogen-oxygen-air burner. [for supersonic ramjet engine

    NASA Technical Reports Server (NTRS)

    Eggers, J. M.

    1974-01-01

    As a result of the need for a uniform hot gas test stream for fuel injector development for hydrogen fueled supersonic combustion ramjet engines, an experimental study of injector configuration effect on exit flow uniformity of a hydrogen fueled oxygen replenished, combustion burner was made. Measurements used to investigate the burner nozzle exit profiles were pitot and gas sample measurements. Gas composition and associated temperature profiles were reduced to an acceptable level by burner injector modifications. The effect of the injector modifications was to redistribute the hydrogen fuel, increase the air pressure drop, promote premixing of the oxygen and air, and establish a uniform flow pattern where the oxygen-air mixture comes into contact with the hydrogen fuel. The most sensitive phenomenon which affected the composition profiles was the uniformity of the air distribution supplied to the combustion chamber.

  4. Reduction on synthesis gas costs by decrease of steam/carbon and oxygen/carbon ratios in the feedstock

    SciTech Connect

    Basini, L.; Piovesan, L.

    1998-01-01

    The costs for syngas production at low steam/carbon and oxygen/carbon ratios have been analyzed for simplified process schemes of the main syngas production technologies (steam-CO{sub 2} reforming, autothermal reforming, and combined reforming) and different synthesis gas compositions. The broad analysis arises from experimental indication on the possibility of preventing carbon formation at low steam/carbon and oxygen/carbon ratios in the feedstock by choosing an appropriate catalyst or by introducing small amounts of sulfur compounds in the reactant feed. The analysis is limited to the synthesis gas production step and does not include its downstream processes. The results indicate that technologies at low steam/carbon and oxygen/carbon ratios would have a significant positive impact on synthesis gas costs.

  5. High-Resolution Electron Energy Loss Studies of Oxygen, Hydrogen, Nitrogen, Nitric Oxide, and Nitrous Oxide Adsorption on Germanium Surfaces.

    NASA Astrophysics Data System (ADS)

    Entringer, Anthony G.

    The first high resolution electron energy loss spectroscopy (HREELS) studies of the oxidation and nitridation of germanium surfaces are reported. Both single crystal Ge(111) and disordered surfaces were studied. Surfaces were exposed to H, O_2, NO, N _2O, and N, after cleaning in ultra-high vacuum. The Ge surfaces were found to be non-reactive to molecular hydrogen (H_2) at room temperature. Exposure to atomic hydrogen (H) resulted hydrogen adsorption as demonstrated by the presence of Ge-H vibrational modes. The HREEL spectrum of the native oxide of Ge characteristic of nu -GeO_2 was obtained by heating the oxide to 200^circC. Three peaks were observed at 33, 62, and 106 meV for molecular oxygen (O_2) adsorbed on clean Ge(111) at room temperature. These peaks are indicative of dissociative bonding and a dominant Ge-O-Ge bridge structure. Subsequent hydrogen exposure resulted in a shift of the Ge-H stretch from its isolated value of 247 meV to 267 meV, indicative of a dominant +3 oxidation state. A high density of dangling bonds and defects and deeper oxygen penetration at the amorphous Ge surface result in a dilute bridge structure with a predominant +1 oxidation state for similar exposures. Molecules of N_2O decompose at the surfaces to desorbed N_2 molecules and chemisorbed oxygen atoms. In contrast, both oxygen and nitrogen are detected at the surfaces following exposure to NO molecules. Both NO and N_2O appear to dissociate and bond at the top surface layer. Molecular nitrogen (N_2) does not react with the Ge surfaces, however, a precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Removal of oxygen by heating of the NO-exposed surface to 550^circC enabled the identification of the Ge-N vibrational modes. These modes show a structure similar to that of germanium nitride. This spectrum is also identical to that of the N-exposed surface heated to 550^circC. Surface phonon modes of the narrow-gap semiconducting

  6. The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh vacuum study

    NASA Astrophysics Data System (ADS)

    Kahng, Yung Ho; Lu, Wei; Tobin, R. G.; Loloee, Reza; Ghosh, Ruby N.

    2009-03-01

    We report several experiments under ultrahigh vacuum conditions that elucidate the role of oxygen in the functioning of silicon carbide field-effect gas sensors with nonporous platinum gates. The devices studied are shown to be sensitive both to hydrogen and to propene. All of the results are consistent with oxygen acting through its surface reactions with hydrogen. Three specific aspects are highlighted: the need, under some conditions, for oxygen to reset the device to a fully hydrogen-depleted state; competition between hydrogen oxidation and hydrogen diffusion to metal/oxide interface sites, leading to steplike behavior as a function of the oxygen:hydrogen ratio (λ-sensing); and the removal of sulfur contamination by oxygen.

  7. Ionized gas (plasma) delivery of reactive oxygen species (ROS) into artificial cells

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Ha; Szili, Endre J.; Jenkins, A. Toby A.; Short, Robert D.

    2014-09-01

    This study was designed to enhance our understanding of how reactive oxygen species (ROS), generated ex situ by ionized gas (plasma), can affect the regulation of signalling processes within cells. A model system, comprising of a suspension of phospholipid vesicles (cell mimics) encapsulating a ROS reporter, was developed to study the plasma delivery of ROS into cells. For the first time it was shown that plasma unequivocally delivers ROS into cells over a sustained period and without compromising cell membrane integrity. An important consideration in cell and biological assays is the presence of serum, which significantly reduced the transfer efficiency of ROS into the vesicles. These results are key to understanding how plasma treatments can be tailored for specific medical or biotechnology applications. Further, the phospholipid vesicle ROS reporter system may find use in other studies involving the application of free radicals in biology and medicine.

  8. A Novel Teflon-membrane Gas Tension Device for Denitrification-studies in Oxygen Minimum Zones

    NASA Astrophysics Data System (ADS)

    Reed, A. C.; McNeil, C. L.; D'Asaro, E. A.; Altabet, M. A.; Johnson, B.; Bourbonnais, A.

    2014-12-01

    Oxygen Minimum Zones (OMZs) are global hotspots for the biogeochemical transformation of biologically-available forms of nitrogen to unusable nitrogen-gas. We present a new Teflon-membrane based Gas Tension Device (GTD) for measuring the excess N2 signal generated by denitrification and anammox in OMZs, with a hydrostatic pressure-independent response and a depth range from 0 - 550 m, a significant advancement from previous GTD models. The GTD consists of a 4/1000" thick by 2" diameter Teflon-membrane with a water-side plenum connected to SeaBird 5T pump. Dissolved gases in the water equilibrate across the membrane with a low-dead-volume housing connected to a high-precision quart pressure sensor. Laboratory data characterizing the GTD will be presented. The e-folding (response) time ranges from 14 min at continuous (100%) pumping to 28 min at pulse (10%) pumping. We also demonstrate the pressure dependence of the partial pressures from Henry's Law in the laboratory for pure nitrogen, pure oxygen, and standard atmospheric ratios of gases. GTD's were field tested on two floats deployed in the Eastern Tropical North Pacific (ETNP) OMZ for 15 days that targeted a productive mesoscale surface eddy originating from the Mexican coast. We anticipated that high organic carbon export should stimulate denitrification within the OMZ below. The floats profiled between the surface and 400 m depth and concurrently measured T, S, PAR, O2 (SBE 43 and Optode), and nitrate (SUNA). The N2-profiles from the GTDs are validated against independently measured N2/Ar ratio data collected during the deployment.

  9. Evaluation of a portable oxygen concentrator to provide fresh gas flow to dogs undergoing anesthesia.

    PubMed

    Burn, Jessica; Caulkett, Nigel A; Gunn, Marta; Cooney, Claire; Kutz, Susan J; Boysen, Søren R

    2016-06-01

    This study evaluated the ability of a portable oxygen concentrator (POC) to provide fresh gas to an anesthetic machine via an Ayre's T-piece or a Bain circuit. Fraction of inspired oxygen (FiO2) was compared at flows of 0.5 to 3.0 L/min. Measured FiO2 was 96% at flow rates ≥ 1 L/min. Mean battery life at 1.0, 2.0, and 3.0 L/min was 4.21 ± 0.45, 2.62 ± 0.37 and 1.5 ± 0.07 hours, respectively. The POC proved to be useful and effective during 2 power outages. The POC was sufficient to prevent rebreathing in 70% of dogs using a T-piece circuit and 20% of dogs with a Bain circuit. A significant negative correlation between inspired CO2 and O2 flow rates was noted. A significant positive correlation between inspired CO2 and ETCO2 was documented. The occurrence of hypercarbia was associated with low O2 flow. Battery back-up was essential during power outages. The POC can be effectively used for delivery of anesthesia. PMID:27247461

  10. The hygric hypothesis does not hold water: abolition of discontinuous gas exchange cycles does not affect water loss in the ant Camponotus vicinus.

    PubMed

    Lighton, John R B; Turner, Robbin J

    2008-02-01

    The discontinuous gas exchange cycle (DGC) of insects and other tracheate arthropods temporally decouples oxygen uptake and carbon dioxide emission and generates powerful concentration gradients for both gas species between the outside world and the tracheal system. Although the DGC is considered an adaptation to reduce respiratory water loss (RWL) - the "hygric hypothesis" - it is absent from many taxa, including xeric ones. The "chthonic hypothesis" states that the DGC originated as an adaptation to gas exchange in hypoxic and hypercapnic, i.e. underground, environments. If that is the case then the DGC is not the ancestral condition, and its expression is not necessarily a requirement for reducing RWL. Here we report a study of water loss rate in the ant Camponotus vicinus, measured while its DGC was slowly eliminated by gradual hypoxia (hypoxic ramp de-DGCing). Metabolic rate remained constant. The DGC ceased at a mean P(O2) of 8.4 kPa. RWL in the absence of DGCs was not affected until P(O2) declined below 3.9 kPa. Below that value, non-DGC spiracular regulation failed, accompanied by a large increase in RWL. Thus, the spiracular control strategy of the DGC is not required for low RWL, even in animals that normally express the DGC. PMID:18245633

  11. Influence of oxygen addition to the carrier gas on laser-induced breakdown spectroscopy measurements on aerosols

    NASA Astrophysics Data System (ADS)

    Palazzo, N.; Migliorini, F.; Dondè, R.; Maffi, S.; De Iuliis, S.

    2016-01-01

    In this work, laser-induced breakdown spectrosopy is implemented on aerosol particles for absolute concentration analysis. The aim of this work is the investigation of the effect of the bath gas used for nebulizing the aerosol. Nitrogen, air, and 50% O2 in N2 mixture have been chosen as carrier gasses in order to analyze the effect of oxygen addition to the gas. LIBS measurements have been carried out on aerosol particles produced from CuCl2 2H2O solutions, and the 324.7 nm Cu line is considered. As a first analysis, plasma parameters, such as temperature and electron density, have been evaluated changing the carrier gas. Measurements to derive the LIBS calibration curve of the 324.7 nm Cu line are carried out in air and in N2. The significant difference in the slope of the resulting calibration curves has to be attributed to the oxygen addition to the bath gas. To explore such behavior, time-resolved measurements of the Cu line and peak/base ratio have been performed. The presence of two competitive effects have been observed that becomes significant increasing the amount of oxygen in the carrier gas. One is the oxygen-quenching effect, already observed in the literature, and the other one is the enhancement of the Cu LIBS signal, expecially at short delay times. These effects have been observed also at other Cu lines and changing the analyte source. The results are presented and widely discussed.

  12. Response of electrochemical oxygen sensors to inert gas-air and carbon dioxide-air mixtures: measurements and mathematical modelling.

    PubMed

    Walsh, P T; Gant, S E; Dowker, K P; Batt, R

    2011-02-15

    Electrochemical oxygen gas sensors are widely used for monitoring the state of inertisation of flammable atmospheres and to warn of asphyxiation risks. It is well established but not widely known by users of such oxygen sensors that the response of the sensor is affected by the nature of the diluent gas responsible for the decrease in ambient oxygen concentration. The present work investigates the response of electrochemical sensors, with either acid or alkaline electrolytes, to gas mixtures comprising air with enhanced levels of nitrogen, carbon dioxide, argon or helium. The measurements indicate that both types of sensors over-read the oxygen concentrations when atmospheres contain high levels of helium. Sensors with alkaline electrolytes are also shown to underestimate the severity of the hazard in atmospheres containing high levels of carbon dioxide. This deviation is greater for alkaline electrolyte sensors compared to acid electrolyte sensors. A Computational Fluid Dynamics (CFD) model is developed to predict the response of an alkaline electrolyte, electrochemical gas sensor. Differences between predicted and measured sensor responses are less than 10% in relative terms for nearly all of the gas mixtures tested, and in many cases less than 5%. Extending the model to simulate responses of sensors with acid electrolytes would be straightforward. PMID:21112151

  13. The effect of silicon on iron plaque formation and arsenic accumulation in rice genotypes with different radial oxygen loss (ROL).

    PubMed

    Wu, Chuan; Zou, Qi; Xue, Sheng-Guo; Pan, Wei-Song; Huang, Liu; Hartley, William; Mo, Jing-Yu; Wong, Ming-Hung

    2016-05-01

    Rice is one of the major pathways of arsenic (As) exposure in human food chain, threatening over half of the global population. Greenhouse pot experiments were conducted to examine the effects of Si application on iron (Fe) plaque formation, As uptake and rice grain As speciation in indica and hybrid rice genotypes with different radial oxygen loss (ROL) ability. The results demonstrated that Si significantly increased root and grain biomass. Indica genotypes with higher ROL induced greater Fe plaque formation, compared to hybrid genotypes and sequestered more As in Fe plaque. Silicon applications significantly increased Fe concentrations in iron plaque of different genotypes, but it decreased As concentrations in the roots, straws and husks by 28-35%, 15-35% and 32-57% respectively. In addition, it significantly reduced DMA accumulation in rice grains but not inorganic As accumulation. Rice of indica genotypes with higher ROL accumulated lower concentrations of inorganic As in grains than hybrid genotypes with lower ROL. PMID:26840513

  14. Do radial oxygen loss and external aeration affect iron plaque formation and arsenic accumulation and speciation in rice?

    PubMed Central

    Wu, Chuan; Ye, Zhihong; Li, Hui; Wu, Shengchun; Deng, Dan; Zhu, Yongguan; Wong, Minghung

    2012-01-01

    Hydroponic experiments were conducted to investigate the effect of radial oxygen loss (ROL) and external aeration on iron (Fe) plaque formation, and arsenic (As) accumulation and speciation in rice (Oryza sativa L.). The data showed that there were significant correlations between ROL and Fe concentrations in Fe plaque produced on different genotypes of rice. There were also significant differences in the amounts of Fe plaque formed between different genotypes in different positions of roots and under different aeration conditions (aerated, normal, and stagnant treatments). In aerated treatments, rice tended to have a higher Fe plaque formation than in a stagnant solution, with the greatest formation at the root tip decreasing with increasing distances away, in accordance with a trend of spatial ROL. Genotypes with higher rates of ROL induced higher degrees of Fe plaque formation. Plaques sequestered As on rice roots, with arsenate almost double that with arsenite, leading to decreased As accumulation in both roots and shoots. The major As species detected in roots and shoots was arsenite, ranging from 34 to 78% of the total As in the different treatments and genotypes. These results contribute to our understanding of genotypic differences in As uptake by rice and the mechanisms causing rice genotypes with higher ROL to show lower overall As accumulation. PMID:22345639

  15. The oxygen status algorithm: a computer program for calculating and displaying pH and blood gas data.

    PubMed

    Siggaard-Andersen, O; Siggaard-Andersen, M

    1990-01-01

    Input parameters for the program are the arterial pH, pCO2, and pO2 (measured by a blood gas analyzer), oxygen saturation, carboxy-, met-, and total hemoglobin (measured by a multi-wavelength spectrometer), supplemented by patient age, sex, temperature, inspired oxygen fraction, fraction of fetal hemoglobin, and ambient pressure. Output parameters are the inspired and alveolar oxygen partial pressures, pH,pCO2 and pO2 referring to the actual patient temperature, estimated shunt fraction, half-saturation tension, estimated 2,3-diphosphoglycerate concentration, oxygen content and oxygen capacity, extracellular base excess, and plasma bicarbonate concentration. Three parameters related to the blood oxygen availability are calculated: the oxygen extraction tension, concentration of extractable oxygen, and oxygen compensation factor. Calculations of the 'reverse' type may also be performed so that the effect of therapeutic measures on the oxygen status or the acid-base status can be predicted. The user may choose among several different units of measurement and two different conventions for symbols. The results are presented in a data display screen comprising all quantities together with age, sex, and temperature adjusted reference values. The program generates a 'laboratory diagnosis' of the oxygen status and the acid-base status and three graphs illustrating the oxygen status and the acid-base status of the patient: the oxygen graph, the acid-base chart and the blood gas map. A printed summary in one A4 page including a graphical display can be produced with an Epson or HP Laser compatible printer. The program is primarily intended for routine laboratories with a blood gas analyzer combined with a multi-wavelength spectrometer. Calculating the derived quantities may enhance the usefulness of the analyzers and improve patient care. The program may also be used as a teaching aid in acid-base and respiratory physiology. The program requires an IBM PC, XT, AT or similar

  16. a Comparative Study of Oxygen Loss on in Situ Heating in PrMnO3 and BaMnO3

    NASA Astrophysics Data System (ADS)

    Garg, K. B.; Heinonen, M.; Nordblad, P.; Dalela, S. D.; Panwar, N.; Sen, V.; Agarwal, S. K.; Sharma, Neha

    We have thoroughly investigated the oxygen loss in PrMnO3 and BaMnO3, the end members of the AMnO3 system, on in situ heating in a reducing atmosphere. This was done to drive some oxygen out from them and thus possibly alter the valence of the Mn cation. Sample characterization was done through X-ray diffraction and SEM measurements. The core-level photoemission point to oxygen loss from only BaMnO3 changing some of Mn4+ to Mn3+ in it, transfer of some spectral weight to the highly localized Fehrenbacher-Rice states and an increased Mn 3d-O 2p hybridization. Magnetization measurements show that at low temperatures, the samples depict a canted antiferromagnetic ordering.

  17. Lime and Soil Moisture Effects on Nitrogen gas Loss Following Fertilizer Application

    NASA Astrophysics Data System (ADS)

    Gu, C.; Maggi, F.; Riley, W.; Oldenburg, C.

    2007-12-01

    The loss of nitrogen from fertilizer application through ammonia volatilization and nitrous oxide emissions are of major environmental concern. Liming has been regarded as a mitigation option for lowering soil nitrogen gas emissions following the addition of fertilizers. A mechanistic nitrogen-cycle model (TOUGHREACT-N) has been developed to simulate the interaction of water saturation variation with biogeochemical processes, and the balance between liming and soil buffering capacity. The model was tested with data from a laboratory soil incubation following the addition of synthetic urine (500 kg N ha-1). Simulation results agreed well with measured N2O emissions and soil inorganic-N concentrations. The study indicated that liming significantly increase NH3 volatilization, while the reduction in cumulative N2O emissions depended strongly on water regime. The cumulative N2O emissions under relatively dry conditions were reduced by up to 243% with liming. However, the cumulative N2O and N2 emissions were predicted to increase by up to 346% following liming because the resulting NO3--N pools (from enhanced nitrification) were susceptible to enhanced N2O and N2 losses during subsequent water application. Consequently, short-term (i.e., days ¡§C weeks) gains made in reducing soil N2O emissions by liming can be offset, and potentially reversed, by emissions later in the growing season. We describe an approach using the modeling framework to optimize N gas reductions using liming under various edaphic, crop type, fertilizer and irrigation application rates, and climate conditions.

  18. Improvement of oxygen diffusion characteristic in gas diffusion layer with planar-distributed wettability for polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Koresawa, Ryo; Utaka, Yoshio

    2014-12-01

    Mass transfer characteristics of gas diffusion layer (GDL) are closely related to performance of polymer electrolyte fuel cells. Therefore, it is necessary to clarify the characteristics of water distribution relating to the microscopic conformation and oxygen diffusivity of GDL. A hybrid type carbon paper GDL with planar-distributed wettability is investigated for control of liquid water movement and distribution due to hydrophobic to hydrophilic areas that provide wettability differences in GDL and to achieve enhancement of both oxygen diffusion and moisture retention. Hybrid GDLs with different PTFE content were fabricated in an attempt to improve the oxygen diffusion characteristics. The effects of different PTFE contents on the oxygen diffusivity and water distribution were simultaneously measured and observed using galvanic cell oxygen absorber and X-ray radiography. The PTFE distribution was observed using scanning electron microscopy. The formation of oxygen diffusion paths was confirmed by X-ray radiography, where voids in the hybrid GDL were first formed in the hydrophobic regions and then spread to the untreated wetting region. Thus, the formation of oxygen diffusion paths enhanced the oxygen diffusion. In addition, the effects of local PTFE content in the hydrophobic region and the optimal amount of PTFE for hybrid GDL were elucidated.

  19. Loss-of-coolant accident experiment at the AVR gas-cooled reactor

    SciTech Connect

    Cleveland, J.; Krueger, K.; Kernforschungsanlage Juelich G.m.b.H. . Arbeitsgemeinschaft Versuchsreaktor)

    1989-01-01

    Loss-of-coolant is one of the most severe accidents for a nuclear power plant. To demonstrate inherent safety characteristics incorporated into small High-Temperature Gas Cooled Reactor (HTGR) designs, loss-of-coolant accident (LOCA) simulation tests have been conducted with the German pebble-bed High-Temperature Reactor AVR. The AVR is the only nuclear power plant ever to have been intentionally subjected to LOCA conditions. The LOCA test was planned to create conditions that would exist if a rapid LOCA occurred with the reactor operating at full power. The tests demonstrated this reactor's safe response to an accident in which the coolant escapes from the reactor core and no emergency system is available to provide coolant flow to the core. The test is of special interest because it demonstrates the inherent safety features incorporated into modular HTGR designs. The main LOCA test lasted for 5 d. After the test began, core temperatures increased for {approximately}13 h and then gradually and continually decreased as the rate of heat dissipation from the core exceeded accident levels of decay power. Throughout the test, temperatures remained below limiting values for the core and other reactor components. 3 refs., 9 figs., 1 tab.

  20. Microwave-assisted synthesis of SnO2 nanorods for oxygen gas sensing at room temperature

    PubMed Central

    Azam, Ameer; Habib, Sami S; Salah, Numan A; Ahmed, Faheem

    2013-01-01

    High-quality single-crystalline SnO2 nanorods were synthesized using a microwave-assisted solution method. The nanorods were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible and Raman spectroscopy, Brunauer–Emmett–Teller (BET), and electrical resistance measurements. The XRD pattern indicated the formation of single-phase SnO2 nanorods with rutile structure. FE-SEM and TEM images revealed tetragonal nanorods of about 450–500 nm in length and 60–80 nm in diameter. The nanorods showed a higher BET surface area of 288 m2/g, much higher than that of previously reported work. The Raman scattering spectra indicated a typical rutile phase of the SnO2. The absorption spectrum showed an absorption peak centered at 340 nm, and the band-gap value was found to be 3.64 eV. The gas-sensing properties of the SnO2 nanorods for oxygen gas with different concentrations were measured at room temperature. It was found that the value of resistance increased with the increase in oxygen gas concentration in the test chamber. The SnO2 nanorods exhibited high sensitivity and rapid response-recovery characteristics to oxygen gas, and could detect oxygen concentration as low as 1, 3, 5, and 10 ppm. PMID:24143091

  1. The effect on the transmission loss of a double wall panel of using helium gas in the gap

    NASA Technical Reports Server (NTRS)

    Atwal, M. S.; Crocker, M. J.

    1985-01-01

    The possibility of increasing the sound-power transmission loss of a double panel by using helium gas in the gap is investigated. The transmission loss of a panel is defined as ten times the common logarithm of the ratio of the sound power incident on the panel to the sound power transmitted to the space on the other side of the panel. The work is associated with extensive research being done to develop new techniques for predicting the interior noise levels on board high-speed advanced turboprop aircraft and reducing the noise levels with a minimum weight penalty. Helium gas was chosen for its inert properties and its low impedance compared with air. With helium in the gap, the impedance mismatch experienced by the sound wave will be greater than that with air in the gap. It is seen that helium gas in the gap increases the transmission loss of the double panel over a wide range of frequencies.

  2. Alveolar gas exchange and tissue oxygenation during incremental treadmill exercise, and their associations with blood O2 carrying capacity

    PubMed Central

    Rissanen, Antti-Pekka E.; Tikkanen, Heikki O.; Koponen, Anne S.; Aho, Jyrki M.; Hägglund, Harriet; Lindholm, Harri; Peltonen, Juha E.

    2012-01-01

    The magnitude and timing of oxygenation responses in highly active leg muscle, less active arm muscle, and cerebral tissue, have not been studied with simultaneous alveolar gas exchange measurement during incremental treadmill exercise. Nor is it known, if blood O2 carrying capacity affects the tissue-specific oxygenation responses. Thus, we investigated alveolar gas exchange and tissue (m. vastus lateralis, m. biceps brachii, cerebral cortex) oxygenation during incremental treadmill exercise until volitional fatigue, and their associations with blood O2 carrying capacity in 22 healthy men. Alveolar gas exchange was measured, and near-infrared spectroscopy (NIRS) was used to monitor relative concentration changes in oxy- (Δ[O2Hb]), deoxy- (Δ[HHb]) and total hemoglobin (Δ[tHb]), and tissue saturation index (TSI). NIRS inflection points (NIP), reflecting changes in tissue-specific oxygenation, were determined and their coincidence with ventilatory thresholds [anaerobic threshold (AT), respiratory compensation point (RC); V-slope method] was examined. Blood O2 carrying capacity [total hemoglobin mass (tHb-mass)] was determined with the CO-rebreathing method. In all tissues, NIPs coincided with AT, whereas RC was followed by NIPs. High tHb-mass associated with leg muscle deoxygenation at peak exercise (e.g., Δ[HHb] from baseline walking to peak exercise vs. tHb-mass: r = 0.64, p < 0.01), but not with arm muscle- or cerebral deoxygenation. In conclusion, regional tissue oxygenation was characterized by inflection points, and tissue oxygenation in relation to alveolar gas exchange during incremental treadmill exercise resembled previous findings made during incremental cycling. It was also found out, that O2 delivery to less active m. biceps brachii may be limited by an accelerated increase in ventilation at high running intensities. In addition, high capacity for blood O2 carrying was associated with a high level of m. vastus lateralis deoxygenation at peak exercise

  3. Dynamic Measurements of Greenhouse Gas Respirations Caused by Changing Oxygen Levels

    NASA Astrophysics Data System (ADS)

    Fleck, D.; Saad, N.

    2015-12-01

    The necessity for constant monitoring of greenhouse gases (GHGs) is clearly evident now more than ever. Moreover, interpreting and understanding the processes that dictate the production and consumption of these gases will allow for proper management of GHGs in order to mitigate its detrimental climate effects. Presence of oxygen, or lack of it, is the driving force for determining pathways within biochemical redox reactions. Experiments to find correlations between oxygen and greenhouse gases have helped us understand photosynthesis, denitrification and beyond. Within the past few years measurements of O2 and nitrous oxide have been used over a wide ranging array of disciplines; from studying avenues for redox chemistry to characterizing gas profiles in sputum of cystic fibrosis patients. We present a full analysis solution, based on cavity ring-down spectroscopy, for simultaneous measurements of N2O, CO2, CH4, H2O, NH3, and O2 concentrations in soil flux, in order to better understand dynamics of ecological and biogeochemical processes. The stability and high temporal resolution of the five-species CRDS analyzer, coupled with a continuous high-precision O2 measurement (1-σ <200ppm) produces a complete picture of biogeochemical processes, for which a multitude of additional research experiments can be conceived. Adding another dimension to explore to help determine the rate at which these greenhouse gases are produced or consumed, allows scientists to further address fundamental scientific questions. Data is presented showing precision, drift and limitations of the O2 sensor measurement as well as the validity of spectroscopic corrections with the CRDS analyzer caused by changing O2. Experimental data is also presented to explore correlations of soil respiration rates of N2O, CO2 and CH4 due to differing soil O2 contents at varying timescales from minutes to days.

  4. Development of an automated sampling-analysis system for simultaneous measurement of reactive oxygen species (ROS) in gas and particle phases: GAC-ROS

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Zhang, Yuanxun; Zhang, Yang; Zeng, Limin; Dong, Huabin; Huo, Peng; Fang, Dongqing; Schauer, James J.

    2016-06-01

    A novel online system, GAC-ROS, for simultaneous measurement of reactive oxygen species (ROS) in both gas and particle phases was developed based on 2‧,7‧-dichlorofluorescin (DCFH) assay to provide fast sampling and analysis of atmospheric ROS. The GAC-ROS, composed of a Gas and Aerosol Collector (GAC), a series of reaction and transportation systems, and a fluorescence detector, was tested for instrumental performance in laboratory. Results showed good performance with a favorable R2 value for the calibration curve (above 0.998), high penetration efficiencies of ROS (above 99.5%), and low detection limits (gas-phase ROS: 0.16 nmol H2O2 m-3; particle-phase ROS: 0.12 nmol H2O2 m-3). Laboratorial comparison between online and offline methods for particle-bound ROS showed significant loss of ROS due to the relatively long time off-line treatment. Field observations in Beijing found that concentrations of ROS in winter time were significantly higher than those observed in spring. Only a few weak positive correlations were found between ROS and some air pollutants, which reflects the complexities of ROS generation and transformation in atmosphere. This study was the first to simultaneously obtain concentrations of gas and particle-phase ROS using an online method. Consequently, it provides a powerful tool to characterize the oxidizing capacity of the atmosphere and the sources of the oxidizing capacity.

  5. Role of the bound-state wave function in capture-loss rates: Slow proton in an electron gas

    SciTech Connect

    Alducin, M.; Nagy, I.

    2003-07-01

    Capture and loss rates for protons moving in an electron gas are calculated using many-body perturbation theory. The role of the form of the bound-state wave function for weakly bound states around the proton is analyzed. We find significant differences (up to a factor of 2 higher) in the values of Auger capture and loss rates when using Hulthen-type instead of hydrogenic wave functions. Its relevance in stopping power is briefly discussed.

  6. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    NASA Astrophysics Data System (ADS)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  7. Chemical-looping combustion of coal-derived synthesis gas over copper oxide oxygen carriers

    SciTech Connect

    Hanjing Tian; Karuna Chaudhari; Thomas Simonyi; James Poston; Tengfei Liu; Tom Sanders; Goetz Veser; Ranjani Siriwardane

    2008-11-15

    CuO/bentonite and CuO-BHA nanocomposites were studied as oxygen carriers in chemical-looping combustion (CLC) of simulated synthesis gas. Global reaction rates of reduction and oxidation, as the function of reaction conversion, were calculated from 10-cycle oxidation/reduction tests utilizing thermogravimetric analysis at atmospheric pressure between 700 and 900{degree}C. It was found that the reduction reactions are always faster than oxidation reactions; reaction temperature and particle size do not significantly affect the reaction performance of CuO/bentonite. Multicycle CLC tests conducted in a high-pressure flow reactor showed stable reactivity for production of CO{sub 2} from fuel gas at 800 and 900{degree}C and full consumption of hydrogen during the reaction. Results of the tapered element oscillating microbalance showed a negative effect of pressure on the global rates of reduction-oxidation reactions at higher fractional conversions. X-ray diffraction patterns confirmed the presence of CuO in the bulk phase of the oxidized sample. Electron microanalysis showed significant morphology changes of reacted CuO/bentonite samples after the 10 oxidation-reduction cycles above 700{degree}C in an atmospheric thermogravimetric analyzer. The nanostructured CuO-BHA carrier also showed excellent stability and, in comparison to the CuO/bentonite system, slightly accelerated redox kinetics albeit at the expense of significantly increased complexity of manufacturing. Overall, both types of CuO carriers exhibited excellent reaction performance and thermal stability for the CLC process at 700-900{degree}C. 48 refs., 12 figs., 8 tabs.

  8. Experimental investigation of engine emissions with marine gas oil-oxygenate blends.

    PubMed

    Nabi, Md Nurun; Hustad, Johan Einar

    2010-07-15

    This paper investigates the diesel engine performance and exhaust emissions with marine gas oil-alternative fuel additive. Marine gas oil (MGO) was selected as base fuel for the engine experiments. An oxygenate, diethylene glycol dimethyl ether (DGM), and a biodiesel (BD) jatropha oil methyl ester (JOME) with a volume of 10% were blended with the MGO fuel. JOME was derived from inedible jatropha oil. Lower emissions with diesel-BD blends (soybean methyl ester, rapeseed methyl ester etc.) have been established so far, but the effect of MGO-BD (JOME) blends on engine performance and emissions has been a growing interest as JOME (BD) is derived from inedible oil and MGO is frequently used in maritime transports. No phase separation between MGO-DGM and MGO-JOME blends was found. The neat MGO, MGO-DGM and MGO-JOME blends are termed as MGO, Ox10 and B10 respectively. The experiments were conducted with a six-cylinder, four-stroke, turbocharged, direct-injection Scania DC 1102 (DI) diesel engine. The experimental results showed significant reductions in fine particle number and mass emissions, PM and smoke emissions with Ox10 and B10 fuels compared to the MGO fuel. Other emissions including total unburned hydrocarbon (THC), carbon monoxide (CO) and engine noise were also reduced with the Ox10 and B10 fuels, while maintaining similar brake specific fuel consumption (BSFC) and thermal efficiency with MGO fuel. Oxides of nitrogen (NOx) emissions, on the other hand, were slightly higher with the Ox10 and B10 fuels at high engine load conditions. PMID:20452651

  9. An assessment of oxygen transfer efficiency in a gas permeable hollow fibre membrane biological reactor.

    PubMed

    Soreanu, G; Lishman, L; Dunlop, S; Behmann, H; Seto, P

    2010-01-01

    The clean water oxygen transfer efficiency (OTE) of a full scale non-porous hollow fibre gas permeable (GP) membrane (surface area of 500 m(2)) was evaluated at inlet air pressures of 1.2, 1.4, and 1.8 atm using two established testing methods. To form a basis of comparison with traditional aeration technologies, additional testing was done with conventional aerators (fine bubble and coarse bubble diffusers) replacing the GP membrane. OTE can be established based on the re-aeration of deoxygenated water or by monitoring the catalytic oxidation of a sodium sulphite (Na(2)SO(3)) solution. In this study, OTE values determined by sulphite oxidation (SOTE(S)) were consistently higher than those established during re-aeration (SOTE(R)) suggesting that the chemical reaction was enhancing the mass transfer. The chemical reaction was sufficiently fast in the case of the GP membrane, that the gas phase limited the mass transfer. The GP membrane operating at 1.2 atm had a SOTE(S) of 70.6% and a SOTER of 52.2%. SOTE(R) for the coarse bubble and fine bubble diffusers were 3.8% and 23.6%, respectively. This is comparable to the manufacturer's values, corrected for depth of 3.4% and 18.3%, respectively. Particularly, the derived OTE values were used to evaluate differences in energy consumption for a conventional treatment plant achieving carbon removal and nitrification. This analysis highlights the potential energy efficiency of GP membranes, which could be considered for the design of the membrane modules. PMID:20220238

  10. Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Qiu, Bao; Zhang, Minghao; Wu, Lijun; Wang, Jun; Xia, Yonggao; Qian, Danna; Liu, Haodong; Hy, Sunny; Chen, Yan; An, Ke; Zhu, Yimei; Liu, Zhaoping; Meng, Ying Shirley

    2016-07-01

    Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas-solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g-1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g-1 still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

  11. Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries.

    PubMed

    Qiu, Bao; Zhang, Minghao; Wu, Lijun; Wang, Jun; Xia, Yonggao; Qian, Danna; Liu, Haodong; Hy, Sunny; Chen, Yan; An, Ke; Zhu, Yimei; Liu, Zhaoping; Meng, Ying Shirley

    2016-01-01

    Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas-solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g(-1) with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g(-1) still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries. PMID:27363944

  12. Using eddy covariance to estimate air–sea gas transfer velocity for oxygen

    NASA Astrophysics Data System (ADS)

    Andersson, Andreas; Rutgersson, Anna; Sahlée, Erik

    2016-07-01

    Air-sea gas transfer velocity for O2 is calculated using directly measured fluxes with the eddy covariance technique. It is a direct method and is frequently used to determine fluxes of heat, humidity, and CO2, but has not previously been used to estimate transfer velocities for O2, using atmospheric eddy covariance data. The measured O2 fluxes are upward directed, in agreement with the measured air-sea gradient of the O2 concentration, and opposite to the direction of the simultaneously measured CO2 fluxes. The transfer velocities estimated from measurements are compared with prominent wind speed parameterizations of the transfer velocity for CO2 and O2, previously established from various measurement techniques. Our result indicates stronger wind speed dependence for the transfer velocity of O2 compared to CO2 starting at intermediate wind speeds. This stronger wind speed dependence appears to coincide with the onset of whitecap formation in the flux footprint and the strong curvature of a cubic wind-dependent function for the transfer velocity provides the best fit to the data. Additional data using the measured O2 flux and an indirect method (based on the Photosynthetic Quotient) to estimate oxygen concentration in water, support the stronger wind dependence for the transfer velocity of O2 compared to CO2.

  13. [Analysis of oxygenates from fischer-Tropsch synthesis oil using column liquid chromatography and gas chromatography-mass spectrography].

    PubMed

    Fan, Gaixian; Xu, Yuanyuan; Li, Ying; Li, Ying; Xiang, Hongwei; Li, Yongwang

    2007-11-01

    A liquid chromatographic column filled with silica gel of 100 - 200 mesh was used to separate cold trap oil from Fischer-Tropsch synthesis with dimethylsulfoxide (DMSO) as eluent. With this pretreatment method, the cold trap oil was separated into two major classes, namely, hydrocarbons and oxygenates. Minor components were also enriched and determined, and small peaks adjacent to big peaks and tailings were also well solved. The oxygenates were then analyzed with gas chromatography-mass spectrometry (GC-MS), and 139 components were identified. PMID:18257312

  14. A statistical review of the oxygen data from the gas generation tests supporting the revision of the 9975 SARP

    SciTech Connect

    Edwards, T.B.

    2000-01-20

    The Chemical and Hydrogen Technology Section (CHT) of the Savannah River Technology Center (SRTC) has conducted a series of gas generation tests in support of the revision of the safety analysis report for packaging (SARP) for the 9975 container, developed at the Savannah River Site (SRS). The Packaging and Transportation Group of SRTC is coordinating the revision to this SARP. A Task Technical and Quality Assurance Plan directing this work was issued by CHT in February 1999. Initially, the primary interest in this testing was hydrogen generation. From these ``gas generation tests can be tracked in real-time by measuring the pressure of a sealed container of the materials being studied. Because multiple gas phase reactions are produced in the radiation field of the sample, material pressure measurements do not necessarily define the quantity of H{sub 2} generated. However, the change in total molecules of gas can be calculated using the ideal gas law from the pressure measurement, known container volume and sample temperature. A measurement of the actual headspace gases must be completed to calculate the H{sub 2} generation rate for a particular sample.'' As the results from these tests were reviewed, however, questions arose regarding the oxygen in the headspace gases. Specifically, do the data from some tests indicate that oxygen was generated for those tests? And do the data for other tests indicate that the oxygen was depleted for them? A statistical analysis of the oxygen data derived from these tests is provided in this report to help answer these questions.

  15. In-situ ambient quantification of monoterpenes, sesquiterpenes, and related oxygenated compounds during BEARPEX 2007: implications for gas- and particle-phase chemistry

    NASA Astrophysics Data System (ADS)

    Bouvier-Brown, N. C.; Goldstein, A. H.; Gilman, J. B.; Kuster, W. C.; de Gouw, J. A.

    2009-08-01

    We quantified ambient mixing ratios of 9 monoterpenes, 6 sesquiterpenes, methyl chavicol, the oxygenated terpene linalool, and nopinone using an in-situ gas chromatograph with a quadrupole mass spectrometer (GC-MS). These measurements were a part of the 2007 Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX) at Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. To our knowledge, these observations represent the first direct in-situ ambient quantification of the sesquiterpenes α-bergamotene, longifolene, α-farnesene, and β-farnesene. From average diurnal mixing ratio profiles, we show that α-farnesene emissions are dependent mainly on temperature whereas α-bergamotene and β-farnesene emissions are temperature- and light-dependent. The amount of sesquiterpene mass quantified above the canopy was small (averaging a total of 3.3 ppt during the day), but nevertheless these compounds contributed 7.6% to the overall ozone-olefin loss rate above the canopy. Assuming that the monoterpene-to-sesquiterpene emission rate in the canopy is similar to that observed in branch enclosure studies at the site during comparable weather conditions, and the average yield of aerosol mass from these sesquiterpenes is 10-50%, the amount of sesquiterpene mass reacted within the Blodgett Forest canopy alone accounts for 6-32% of the total organic aerosol mass measured during BEARPEX. The oxygenated monoterpene linalool was also quantified for the first time at Blodgett Forest. The linalool mass contribution was small (9.9 ppt and 0.74 ppt within and above the canopy, respectively), but it contributed 1.1% to the total ozone-olefin loss rate above the canopy. Reactive and semi-volatile compounds, especially sesquiterpenes, significantly impact the gas- and particle-phase chemistry of the atmosphere at Blodgett Forest and should be included in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  16. Effect of chemistry and turbulence on NO formation in oxygen-natural gas flames

    NASA Technical Reports Server (NTRS)

    Samaniego, J. -M.; Egolfopoulos, F. N.; Bowman, C. T.

    1996-01-01

    The effects of chemistry and turbulence on NO formation in oxygen-natural turbulent diffusion flames gas flames have been investigated. The chemistry of nitric oxides has been studied numerically in the counterflow configuration. Systematic calculations with the GRI 2.11 mechanism for combustion of methane and NO chemistry were conducted to provide a base case. It was shown that the 'simple' Zeldovich mechanism accounts for more than 75% of N2 consumption in the flame in a range of strain-rates varying between 10 and 1000 s-l. The main shortcomings of this mechanism are: 1) overestimation (15%) of the NO production rate at low strain-rates because it does not capture the reburn due to the hydrocarbon chemistry, and 2) underestimation (25%) of the NO production rate at high strainrates because it ignores NO production through the prompt mechanism. Reburn through the Zeldovich mechanism alone proves to be significant at low strain-rates. A one-step model based on the Zeldovich mechanism and including reburn has been developed. It shows good agreement with the GRI mechanism at low strain-rates but underestimates significantly N2 consumption (about 50%) at high strain-rates. The role of turbulence has been assessed by using an existing 3-D DNS data base of a diffusion flame in decaying turbulence. Two PDF closure models used in practical industrial codes for turbulent NO formation have been tested. A simpler version of the global one-step chemical scheme for NO compared to that developed in this study was used to test the closure assumptions of the PDF models, because the data base could not provide all the necessary ingredients. Despite this simplification, it was possible to demonstrate that the current PDF models for NO overestimate significantly the NO production rate due to the fact that they neglect the correlations between the fluctuations in oxygen concentration and temperature. A single scalar PDF model for temperature that accounts for such correlations based

  17. Effects of temperature on the removal of urea as ammonia by enzymatic conversion and by gas absorption using an oxygenator.

    PubMed

    Pişkin, E; Chang, T M

    1981-01-01

    Urea in dialysate solution was converted by urease into ammonium and bicarbonate. Ammonium and bicarbonate can be removed using a gas absorption unit (e.g. oxygenator) to remove ammonia gas and carbon dioxide. The times for the total ammonium levels in the dialysate to be lowered by 50% were 95 minutes at 25 degree C and 15 minutes at 60 degree C. Increasing the dialysate temperature alone was effective in increasing the removal of ammonium, without the need to add NaOH. PMID:7216533

  18. Using soil oxygen sensors to inform understanding of soil greenhouse gas dynamics

    NASA Astrophysics Data System (ADS)

    Jarecke, K. M.; Loecke, T.; Burgin, A. J.; Franz, T. E.; Rubol, S.

    2015-12-01

    Hot spots and hot moments of greenhouse gas (GHG) fluxes can contribute significantly to overall GHG budgets. Hot spots and hot moments occur when dynamic soil hydrology triggers important shifts in soil biogeochemical and physical processes that control GHG emissions. Soil oxygen (O2), a direct control on biogenic GHG production (i.e., nitrous oxide-N2O, carbon dioxide-CO2 and methane-CH4), may serve as both an important proxy for determining sudden shifts in subsurface biogenic GHG production, as well as the physical transport of soil GHG to the atmosphere. Recent technological advancements offer opportunities to link in-situ, near-continuous measurements of soil O2 concentration to soil biogeochemical processes and soil gas transport. Using high frequency data, this study asked: Do soil O2 dynamics correspond to changes in soil GHG concentrations and GHG surface fluxes? We addressed this question using precipitation event-based and weekly sampling (19 months in duration) data sets from a restored riparian wetland in Ohio, USA. During and after precipitation events, changes in subsurface (10 and 20 cm) CO2 and N2O concentrations were inversely related to short-term (< 48 h) changes in soil O2 concentrations. Subsurface CH4 concentrations changes during precipitation events, however, did not change in response to soil O2 dynamics. Changing subsurface GHG concentrations did not necessarily translate into altered surface (soil to atmosphere) GHG fluxes; soil O2 dynamics at 10 cm did not correspond with changes in surface N2O and CH4 fluxes. However, changes in soil O2 concentration at 10 cm had a significant positive linear relationship with change in surface CO2­ flux. We used a random forest approach to identify the soil sensor data (O2, temperature, moisture) which contribute the most to predicting weekly GHG fluxes. Our study suggests that monitoring near-continuous soil O2 concentration under dynamic soil hydrology may lead to greater understanding of GHG

  19. The Decompression Sickness and Venous Gas Emboli Consequences of Air Breaks During 100% Oxygen Prebreathe

    NASA Technical Reports Server (NTRS)

    Conkin, J.; Gernhardt, M. L.; Powell, M. R.

    2004-01-01

    Not enough is known about the increased risk of hypobaric decompression sickness (DCS) and production of venous (VGE) and arterial (AGE) gas emboli following an air break in an otherwise normal 100% resting oxygen (O2) prebreathe (PB), and certainly a break in PB when exercise is used to accelerate nitrogen (N2) elimination from the tissues. Current Aeromedical Flight Rules at the Johnson Space Center about additional PB payback times are untested, possibly too conservative, and therefore not optimized for operational use. A 10 min air break at 90 min into a 120 min PB that includes initial dual-cycle ergometry for 10 min will show a measurable increase in the risk of DCS and VGE after ascent to 4.3 psia compared to a 10 min break at 15 min into the PB, or when there is no break in PB. Data collection with humans begins in 2005, but here we first evaluate the hypothesis using three models of tissue N2 kinetics: Model I is a simple single half-time compartment exponential model, Model II is a three compartment half-time exponential model, and Model III is a variable half-time compartment model where the percentage of maximum O2 consumption for the subject during dual-cycle ergometry exercise defines the half-time compartment. Model I with large rate constants to simulate an exercise effect always showed a late break in PB had the greatest consequence. Model II showed an early break had the greatest consequence. Model III showed there was no difference between early or late break in exercise PB. Only one of these outcomes will be observed when humans are tested. Our results will favor one of these models, and so advance our understanding of tissue N2 kinetics, and of altitude DCS after an air break in PB.

  20. Electron Capture and Loss Processes in the Interaction of Hydrogen, Oxygen, and Fluorine Atoms and Negative Ions with a MgO(100) Surface

    SciTech Connect

    Ustaze, S.; Verucchi, R.; Lacombe, S.; Guillemot, L.; Esaulov, V.A.

    1997-11-01

    A study of electron capture and loss processes during the scattering of H, O, and F atoms and anions on a MgO(100) surface is described. Large fractions of anions in the scattering of atoms are observed, indicating the existence of an efficient electron capture process. This is ascribed to a nonresonant, localized charge exchange mechanism between an atom and a MgO lattice oxygen anion. This charge transfer becomes possible because of anion level shifts in the Madelung field. The existence of an electron loss channel is demonstrated using incident anions and is ascribed to loss to the conduction band or Mg cations. {copyright} {ital 1997} {ital The American Physical Society}

  1. Does the addition of a second daily session of hyperbaric oxygen therapy to intratympanic steroid influence the outcomes of sudden hearing loss?

    PubMed

    Attanasio, G; Covelli, E; Cagnoni, L; Masci, E; Ferraro, D; Mancini, P; Alessandri, E; Cartocci, G; Filipo, R; Rocco, M

    2015-10-01

    The aim of this study is to investigate whether, in addition to intratympanic steroid therapy, additional hyperbaric oxygen therapy (HBOT) sessions per day (twice a day for 5 days) is more useful than one session per day for 10 days in patients affected by severe and profound idiopathic sudden sensorineural hearing loss (ISSNHL). A total of 55 patients affected by unilateral severe and profound ISSNHL were recruited. Two protocols were adopted. In the first, 27 patients (13 with profound and 14 with severe hearing loss) underwent one session of HBOT per day for 10 days, 6 days a week. An HBOT session comprised a period of 14 minutes air compression followed by 90 min at 2.4 atm absolute (ATA) followed by a decompression period of 15 min in oxygen. Patients breathed 100% oxygen through an appropriate mask checked for leaks. Patients were given 0.4 ml of 62.5 mg/ml of intratympanic prednisolone during the first three days of the protocol. In the second protocol, 28 patients (10 with profound and 18 with severe hearing loss) received 10 sessions of HBOT, twice a day for five days, 2.4 ATA 90 min 100% oxygen. The intratympanic injections of prednisolone were given between the two sessions of HBOT during the first three days of the protocol. Since there were no significant differences in hearing outcomes between the two protocols, the present study shows that the protocol of two sessions of HBOT per day is a valid treatment and equally effective as the one HBOT session per day, but with shorter treatment time. PMID:26824214

  2. Dependence of Ozone Generation on Gas Temperature Distribution in AC Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

    NASA Astrophysics Data System (ADS)

    Takahashi, Go; Akashi, Haruaki

    AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.

  3. Effect of reactive gas (oxygen/chlorine/fluorine) etching on the magnetic flux of a high moment write pole material

    SciTech Connect

    Zhang Jinqiu; Liu Feng; Chen Lifan; Miloslavsky, Lena

    2010-05-15

    Effect of reactive gas (oxygen/chlorine/fluorine) etching on NiFe magnetic properties was investigated. Experimental data showed 40% magnetic property degradation for F-containing gas etching, 10% degradation for O-containing gas etching, and 5% degradation for Cl-containing gas etching processes. X-ray diffraction analysis indicated that the crystallographic orientation remained the same upon the reactive gas etching, which is due to the low ion energy in plasma etching process as opposed to ion milling process with high input energy. It is proposed that the reported magnetic property degradation was mainly caused by the nonmagnetic dead layer formation, rather than the changes in the crystallographic orientation. The dead layer was determined by the NiFe thickness dependence of remnant magnetic flux variations between pre-etched and postetched samples. The dead layer remained nearly constant for O-containing gas etching process with increasing plasma processing time. The nonmagnetic dead layer of {approx}40-50 A formed in O-containing etching gas was observed in transmission electron microscopy cross-sectional image and was in very good agreement with the calculated value based on magnetic flux measurements. Combined magnetic and physical characterizations suggest that the dead layer thickness saturates at the initial stage of the plasma etching and magnetic property remained unchanged with increasing etching duration upon formation of the dead layer.

  4. Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries

    DOE PAGESBeta

    Qiu, Bao; Zhang, Minghao; Wu, Lijun; Wang, Jun; Xia, Yonggao; Qian, Danna; Liu, Haodong; Chen, Yan; An, Ke; Zhu, Yimei; et al

    2016-07-01

    Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high asmore » 301 mAh g–1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g–1 still remains without any obvious decay in voltage. Lastly, this study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.« less

  5. Impact of the renewable oxygenate standard for reformulated gasoline on ethanol demand, energy use, and greenhouse gas emissions

    SciTech Connect

    Stork, K.C.; Singh, M.K.

    1995-04-01

    To assure a place for renewable oxygenates in the national reformulated gasoline (RFG) program, the US Environmental Protection Agency has promulgated the renewable oxygenate standard (ROS) for RFG. It is assumed that ethanol derived from corn will be the only broadly available renewable oxygenate during Phase I of the RFG program. This report analyzes the impact that the ROS could have on the supply of ethanol, its transported volume, and its displacement from existing markets. It also considers the energy and crude oil consumption and greenhouse gas (GHG) emissions that could result from the production and use of various RFGs that could meet the ROS requirements. The report concludes that on the basis of current and projected near-term ethanol capacity, if ethanol is the only available renewable oxygenate used to meet the requirements of the ROS, diversion of ethanol from existing use as a fuel is likely to be necessary. Year-round use of ethanol and ETBE would eliminate the need for diversion by reducing winter demand for ethanol. On an RFG-program-wide basis, using ethanol and ETBE to satisfy the ROS can be expected to slightly reduce fossil energy use, increase crude oil use, and have essentially no effect on GHG emissions or total energy use relative to using RFG oxygenated only with MTBE.

  6. Beam loss and backgrounds in the CDF and D0 detectors due to nuclear elastic beam-gas scattering

    SciTech Connect

    Alexandr I. Drozhdin; Valery A. Lebedev; Nikolai V. Mokhov

    2003-05-27

    Detailed simulations were performed on beam loss rates in the vicinity of the Tevatron Collider detectors due to beam-gas nuclear elastic interactions. It turns out that this component can drive the accelerator-related background rates in the CDF and D0 detectors, exceeding those due to outscattering from collimation system, inelastic beam-gas interactions and other processes [1, 2]. Results of realistic simulations with the STRUCT and MARS codes are presented for the interaction region components and the CDF and D0 detectors. It is shown that a steel mask placed upstream of the detectors can reduce the background rates by almost an order of magnitude.

  7. Thermodynamic approach to oxygen delivery in vivo by natural and artificial oxygen carriers.

    PubMed

    Bucci, Enrico

    2009-06-01

    Oxygen is a toxic gas, still indispensable to aerobic life. This paper explores how normal physiology uses the physico-chemical and thermodynamic characteristics of oxygen for transforming a toxic gas into a non toxic indispensable metabolite. Plasma oxygen concentration is in the range of 10(-5) M, insufficient to sustain metabolism. Oxygen carriers, present in blood, release oxygen into plasma, thereby replacing consumed oxygen and buffering PO(2) near their P(50). They are the natural cell-bound carriers, like hemoglobin inside red cells, myoglobin inside myocytes, and artificial cell-free hemoglobin-based oxygen carriers (HBOC) dissolved in plasma. Metabolic oxygen replacement can be defined as cell-bound and cell-free delivery. Cell-bound delivery is retarded by the slow diffusion of oxygen in plasma and interstitial fluids. The 40% hematocrit of normal blood compensates for the delay, coping with the fast oxygen consumption by mitochondria. Facilitated oxygen diffusion by HBOCs corrects for the slow diffusion, making cell-free delivery relatively independent from P(50). At all oxygen affinities, HBOCs produce hyperoxygenations that are compensated by vasoconstrictions. There is a strict direct correlation between the rate of oxygen replacement and hemoglobin content of blood. The free energy loss of the gradient adds a relevant regulation of tissues oxygenation. Oxygen is retained intravascularly by the limited permeability to gases of vessel walls. PMID:19349106

  8. Background gas density and beam losses in NIO1 beam source.

    PubMed

    Sartori, E; Veltri, P; Cavenago, M; Serianni, G

    2016-02-01

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection. PMID:26932000

  9. Background gas density and beam losses in NIO1 beam source

    NASA Astrophysics Data System (ADS)

    Sartori, E.; Veltri, P.; Cavenago, M.; Serianni, G.

    2016-02-01

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

  10. Thermofluid analysis of the SSME preburner using a gas-gas diffusion model for oxygen and hydrogen combustion at supercritical pressures

    NASA Technical Reports Server (NTRS)

    Prakash, C.; Singhal, A. K.; Shafer, C.

    1986-01-01

    The paper discusses the thermofluid analysis of the Space Shuttle Main Engine (SSME) fuelside preburner. The governing equations have been solved numerically to predict flow, heat transfer, mixing, and combustion. A two-fluid approach is adopted in which oxygen is regarded as one fluid and hydrogen is regarded as the other fluid. The chemical kinetics is assumed to be very fast so that combustion is primarily controlled by the rate of mixing between oxygen and hydrogen. The preburner pressure is much greater than the critical pressures of oxygen and hydrogen; hence, a gas-gas diffusion model (rather than an evaporation model) has been developed to compute the rate of interphase mixing. Empirical correlations have been incorporated to account for the effect of slip on the interphase exchange. A sensitivity study has been performed with various model parameters. It is observed that the model can predict possibility of incomplete combustion and local regions of high temperatures under steady operating conditions. Some of these anomalies have been observed in actual tests, and the numerical model is useful for understanding possible causes and remedies. At least some measurements are needed for quantitative verification of the model.

  11. Energy loss and electron emission during grazing scattering of fast noble gas atoms from an Al(1 1 1) surface

    NASA Astrophysics Data System (ADS)

    Lederer, S.; Winter, H.; Winter, HP.

    2007-05-01

    Electron loss and electron emission for grazing impact of noble gas atoms with energies in the keV domain are investigated via time-of-flight spectra recorded in coincidence with the number of emitted electrons. The data is analyzed in terms of computer simulations concerning the interaction of the fast atoms with the electron gas in the selvedge of the Al(1 1 1) surface. The interaction is approximated by binary collisions of the fast atoms with Fermi electrons of the conduction band and differential cross sections obtained for electron scattering from free atoms. For an effective number of collisions of about 50 the energy loss spectra are fairly well reproduced by our calculations. We show that for our conditions the shift of the energy spectra for the emission of an additional electron from the surface is close to the work function of the target.

  12. Design of generic coal conversion facilities: Production of oxygenates from synthesis gas---A technology review

    SciTech Connect

    Not Available

    1991-10-01

    This report concentrates on the production of oxygenates from coal via gasification and indirect liquefaction. At the present the majority of oxygenate synthesis programs are at laboratory scale. Exceptions include commercial and demonstration scale plants for methanol and higher alcohols production, and ethers such as MTBE. Research and development work has concentrated on elucidating the fundamental transport and kinetic limitations governing various reactor configurations. But of equal or greater importance has been investigations into the optimal catalyst composition and process conditions for the production of various oxygenates.

  13. Quadratic energy-loss straggling and energy widths of the states of slow ions in an electron gas

    SciTech Connect

    Wang, N.

    1997-10-01

    The energy-loss straggling and energy width of states of slow ions interacting with a homogeneous electron gas are evaluated within a quadratic response theory and the random-phase approximation. These results are compared with corresponding results determined from a fully nonlinear scattering theory approach. The quadratic response theory is shown to be a good approximation for high electron densities and small ion charges. {copyright} {ital 1997} {ital The American Physical Society}

  14. Application of the methods of numerical modeling to evaluation of the total-pressure loss in gas turbines

    NASA Astrophysics Data System (ADS)

    Volkov, K. N.

    2007-09-01

    The total-pressure loss in gas turbines is evaluated. Reynolds-averaged Navier-Stokes equations are used for numerical calculations. The Spalart-Allmaras model, the k-ɛ model, and the two-layer model and their different modifications allowing for the rotation of the flow and the curvature of streamlines are used to close these equations. The role of different corrections to the turbulence models for the accuracy of calculated estimates is elucidated.

  15. Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

    NASA Technical Reports Server (NTRS)

    Henneberry, Hugh M.; Snyder, Christopher A.

    1993-01-01

    An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet engine and a mixed-flow turbofan engine (MFTF) are examined, and in pursuit of maximum thrust, both engines are fitted with afterburners. The results indicate that water injection alone can extend the performance envelope of both engine types by one and one-half Mach numbers at which point water-air ratios reach 17 or 18 percent and liquid specific impulse is reduced to some 390 to 470 seconds, a level about equal to the impulse of a high energy rocket engine. The envelope can be further extended, but only with increasing sacrifices in liquid specific impulse. Oxygen-airflow ratios as high as 15 percent were investigated for increasing thrust. Using 15 percent oxygen in combination with water injection at high supersonic Mach numbers resulted in thrust augmentation as high as 76 percent without any significant decrease in liquid specific impulse. The stoichiometric afterburner exit temperature increased with increasing oxygen flow, reaching 4822 deg R in the turbojet engine at a Mach number of 3.5. At the transonic Mach number of 0.95 where no water injection is needed, an oxygen-air ratio of 15 percent increased thrust by some 55 percent in both engines, along with a decrease in liquid specific impulse of 62 percent. Afterburner temperature was approximately 4700 deg R at this high thrust condition. Water and/or oxygen injection are simple and straightforward strategies to improve engine performance and they will add little to engine weight. However, if large Mach number and thrust increases are required, liquid flows become significant, so that operation at these conditions will necessarily be of short duration.

  16. Oxygen deficiency hazards associated with liquefied gas systems development of a program of controls

    SciTech Connect

    Miller, T.M.; Mazur, P.O.

    1983-01-01

    The use of liquefied gases in industry and research has become commonplace. Release into the atmosphere of these gases, whether intentional or not, will result in a displacement of air and a reduction in the oxygen concentration. Exposure to reduced levels of oxygen levels may cause reduced abilities, unconsciousness, or death. This paper describes the derivation of a novel program of controls for oxygen deficiency hazards. The key to this approach is a quantitative assessment of risk for each planned operation and the application of control measures to reduce that risk to an acceptable level. Five risk levels evolve which are based on the probability of fatality. Controls such as training, oxygen monitoring equipment, self-rescue respirators, and medical surveillance are required when the probability of fatality exceeds 10/sup -7/ per hour. The quantitative nature of this program ensures an appropriate level of control without undue burden or expense. 11 references, 5 figures, 3 tables.

  17. Oxygen-limited thermal tolerance is seen in a plastron-breathing insect and can be induced in a bimodal gas exchanger.

    PubMed

    Verberk, Wilco C E P; Bilton, David T

    2015-07-01

    Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in gas exchange mechanisms could reconcile the discrepancies found in previous studies. Here, we test this suggestion by comparing the behaviour of related insect taxa with different gas exchange mechanisms, with and without access to air. We demonstrate oxygen-limited thermal tolerance in air-breathing adults of the plastron-exchanging water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal gas exchanger, did not exhibit such oxygen-limited thermal tolerance and relied increasingly on aerial gas exchange with warming. Intriguingly, however, when denied access to air, oxygen-limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life-history stages in these insects, with nymphs employing the same gas exchange mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits. PMID:25964420

  18. Oxygen-limited thermal tolerance is seen in a plastron-breathing insect and can be induced in a bimodal gas exchanger

    PubMed Central

    Verberk, Wilco C. E. P.; Bilton, David T.

    2015-01-01

    ABSTRACT Thermal tolerance has been hypothesized to result from a mismatch between oxygen supply and demand. However, the generality of this hypothesis has been challenged by studies on various animal groups, including air-breathing adult insects. Recently, comparisons across taxa have suggested that differences in gas exchange mechanisms could reconcile the discrepancies found in previous studies. Here, we test this suggestion by comparing the behaviour of related insect taxa with different gas exchange mechanisms, with and without access to air. We demonstrate oxygen-limited thermal tolerance in air-breathing adults of the plastron-exchanging water bug Aphelocheirus aestivalis. Ilyocoris cimicoides, a related, bimodal gas exchanger, did not exhibit such oxygen-limited thermal tolerance and relied increasingly on aerial gas exchange with warming. Intriguingly, however, when denied access to air, oxygen-limited thermal tolerance could also be induced in this species. Patterns in oxygen-limited thermal tolerance were found to be consistent across life-history stages in these insects, with nymphs employing the same gas exchange mechanisms as adults. These results advance our understanding of oxygen limitation at high temperatures; differences in the degree of respiratory control appear to modulate the importance of oxygen in setting tolerance limits. PMID:25964420

  19. Gas hold-up and oxygen mass transfer in three pneumatic bioreactors operating with sugarcane bagasse suspensions.

    PubMed

    Esperança, M N; Cunha, F M; Cerri, M O; Zangirolami, T C; Farinas, C S; Badino, A C

    2014-05-01

    Sugarcane bagasse is a low-cost and abundant by-product generated by the bioethanol industry, and is a potential substrate for cellulolytic enzyme production. The aim of this work was to evaluate the effects of air flow rate (QAIR), solids loading (%S), sugarcane bagasse type, and particle size on the gas hold-up (εG) and volumetric oxygen transfer coefficient (kLa) in three different pneumatic bioreactors, using response surface methodology. Concentric tube airlift (CTA), split-cylinder airlift (SCA), and bubble column (BC) bioreactor types were tested. QAIR and %S affected oxygen mass transfer positively and negatively, respectively, while sugarcane bagasse type and particle size (within the range studied) did not influence kLa. Using large particles of untreated sugarcane bagasse, the loop-type bioreactors (CTA and SCA) exhibited higher mass transfer, compared to the BC reactor. At higher %S, SCA presented a higher kLa value (0.0448 s−1) than CTA, and the best operational conditions in terms of oxygen mass transfer were achieved for %S < 10.0 g L−1 and QAIR > 27.0 L min−1. These results demonstrated that pneumatic bioreactors can provide elevated oxygen transfer in the presence of vegetal biomass, making them an excellent option for use in three-phase systems for cellulolytic enzyme production by filamentous fungi. PMID:24078146

  20. Hyperbaric oxygen pretreatment according to the gas micronuclei denucleation hypothesis reduces neurologic deficit in decompression sickness in rats.

    PubMed

    Katsenelson, K; Arieli, R; Arieli, Y; Abramovich, A; Feinsod, M; Tal, D

    2009-08-01

    During sudden or too rapid decompression, gas is released within supersaturated tissues in the form of bubbles, the cause of decompression sickness. It is widely accepted that these bubbles originate in the tissue from preexisting gas micronuclei. Pretreatment with hyperbaric oxygen (HBO) has been hypothesized to shrink the gas micronuclei, thus reducing the number of emerging bubbles. The effectiveness of a new HBO pretreatment protocol on neurologic outcome was studied in rats. This protocol was found to carry the least danger of oxygen toxicity. Somatosensory evoked potentials (SSEPs) were chosen to serve as a measure of neurologic damage. SSEPs in rats given HBO pretreatment before a dive were compared with SSEPs from rats not given HBO pretreatment and SSEPs from non-dived rats. The incidence of abnormal SSEPs in the animals subjected to decompression without pretreatment (1,013 kPa for 32 min followed by decompression) was 78%. In the pretreatment group (HBO at 304 kPa for 20 min followed by exposure to 1,013 kPa for 33 min and decompression) this was significantly reduced to 44%. These results call for further study of the pretreatment protocol in higher animals. PMID:19470698

  1. Multi-dimensional gas chromatography with a planar microfluidic device for the characterization of volatile oxygenated organic compounds.

    PubMed

    Luong, J; Gras, R; Cortes, H; Shellie, R A

    2012-09-14

    Oxygenated compounds like methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetaldehyde, crotonaldehyde, ethylene oxide, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and 2-chloromethyl-1,3-dioxolane are commonly encountered in industrial manufacturing processes. Despite the availability of a variety of column stationary phases for chromatographic separation, it is difficult to separate these solutes from their respective matrices using single dimension gas chromatography. Implemented with a planar microfluidic device, conventional two-dimensional gas chromatography and the employment of chromatographic columns using dissimilar separation mechanisms like that of a selective wall-coated open tubular column and an ionic sorbent column have been successfully applied to resolve twelve industrially significant volatile oxygenated compounds in both gas and aqueous matrices. A Large Volume Gas Injection System (LVGIS) was also employed for sample introduction to enhance system automation and precision. By successfully integrating these concepts, in addition to having the capability to separate all twelve components in one single analysis, features associated with multi-dimensional gas chromatography like dual retention time capability, and the ability to quarantine undesired chromatographic contaminants or matrix components in the first dimension column to enhance overall system cleanliness were realized. With this technique, a complete separation for all the compounds mentioned can be carried out in less than 15 min. The compounds cited can be analyzed over a range of 250 ppm (v/v) to 100 ppm (v/v) with a relative standard deviation of less than 5% (n=20) with high degree of reliability. PMID:22410155

  2. A new method for the determination of biological oxygen demand in domestic wastewater by headspace gas chromatography.

    PubMed

    Gu, Juan-Juan; Hu, Hui-Chao; Chai, Xin-Sheng; Tian, Ying-Xin; Barnes, Donald G; Huang, Shaobin

    2013-09-20

    A headspace gas chromatographic method (HS-GC) has been developed for the determination of biological oxygen demand (BOD) in the water samples from domestic wastewater treatment plants. The method is based on measuring the remaining oxygen in the headspace of the sample (that has been seeded with microorganisms) in a closed container after a period of incubation. The relative standard deviation of the method in replicate testing was <4.9%. Further, the results differed by less than 6% when compared with the widely used reference method (the ISO standard) for determining BOD5. The limit of quantification in BODn testing was about 1.8 mg/L. The new method is simple and suitable for use in the batch sample testing for BODn measurement. PMID:23953613

  3. Oxygen/ozone as a medical gas mixture. A critical evaluation of the various methods clarifies positive and negative aspects

    PubMed Central

    2011-01-01

    Besides oxygen, several other gases such as NO, CO, H2, H2S, Xe and O3 have come to age over the past few years. With regards to O3, its mechanisms of action in medicine have been clarified during the last two decades so that now a comprehensive framework for understanding and recommending ozone therapy in various pathologies is available. O3 used within the determined therapeutic window is absolutely safe and more effective than golden standard medications in numerous pathologies, like vascular diseases. However, ozone therapy is mostly in practitioners' hands and some recent developments for increasing cost effectiveness and speed of treatment are neither standardized, nor evaluated toxicologically. Hence, the aim of this article is to emphasize the need to objectively assess the pros and cons of oxygen/ozone as a medical gas mixture in the hope that ozone therapy will be accepted by orthodox medicine in the near future. PMID:22146387

  4. Leptin Integrates Vertebrate Evolution: from Oxygen to the Blood-Gas Barrier

    PubMed Central

    Torday, J.S.; Powell, F.L.; Farmer, C.G.; Orgeig, S.; Nielsen, H.C.; Hall, A.J.

    2014-01-01

    The following are the proceedings of a symposium held at the Second International Congress for Respiratory Science in Bad Honnef, Germany. The goals of the symposium were to delineate the blood-gas barrier phenotype across vertebrate species; to delineate the interrelationship between the evolution of the blood-gas barrier, locomotion and metabolism; to introduce the selection pressures for the evolution of the surfactant system as a key to understanding the physiology of the blood-gas barrier; to introduce the lung lipofibroblast and its product, leptin, which coordinately regulates pulmonary surfactant, type IV collagen in the basement membrane and host defense, as the cell-molecular site of selection pressure for the blood-gas barrier; to drill down to the gene regulatory network(s) involved in leptin signaling and the blood-gas barrier phenotype; to extend the relationship between leptin and the blood-gas-barrier to diving mammals. PMID:20096383

  5. Oxygen analyzer

    DOEpatents

    Benner, William H.

    1986-01-01

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N.sub.2), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable oxygen obtained by decomposing the sample at 1135.degree. C., or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135.degree. C. as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N.sub.2, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  6. Usefulness of Decrease in Oxygen Uptake Efficiency to Identify Gas Exchange Abnormality in Patients with Idiopathic Pulmonary Arterial Hypertension

    PubMed Central

    Yang, Wenlan; Guo, Jian; Zhang, Yan; Sapkota, Rikesh; Kushwaha, Shailendra Prasad; Gong, Sugang; Sun, Xingguo; Liu, Jinming

    2014-01-01

    Background Decline in oxygen uptake efficiency (OUE), especially during exercise, is found in patients with chronic heart failure. In this study we aimed to test the validity and usefulness of OUE in evaluating gas exchange abnormality of patients with idiopathic pulmonary arterial hypertension (IPAH). Methods We retrospectively investigated the cardiopulmonary exercise test (CPET) with gas exchange measurements in 32 patients with confirmed IPAH. All patients also had resting hemodynamic measurements and pulmonary function test (PFT). Sixteen healthy subjects, matched by age, sex, and body size were used as controls, also had CPET and PFT measurements. Results In IPAH patients, the magnitude of absolute and percentage of predicted (%pred) oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP), as well as several other CPET parameters, were strikingly worse than healthy subjects (P<0.0001). Pattern of changes in OUE in patients is similar to that in controls, In IPAH patients, OUE values at rest, warming up, anaerobic threshold and peak exercise were all significantly lower than in normal (P<0.0001). OUEP%pred, better than OUES%pred, correlated significantly with New York Heart Association (NYHA) functional Class (r = −0.724, P<0.005), Total Pulmonary Vascular Resistance (TPVR) (r = −0.694, P<0.005), diffusing capacity for carbon monoxide (DLCO) (r = 0.577, P<0.05), and the lowest ventilation versus CO2 output ratio during exercise (LowestV˙E/V˙CO2) (r = −0.902, P<0.0001). In addition, the coefficient of variation (COV) of OUEP was lower (20.9%) markedly than OUES (34.3%) (P<0.0001). Conclusions In patients with IPAH, OUES and OUEP are both significantly lower than the healthy subjects. OUEP is a better physiological parameter than OUES in evaluating the gas exchange abnormality of patients with IPAH. PMID:24905576

  7. Control of a two-dimensional electron gas on SrTiO₃(111) by atomic oxygen.

    PubMed

    Walker, S McKeown; de la Torre, A; Bruno, F Y; Tamai, A; Kim, T K; Hoesch, M; Shi, M; Bahramy, M S; King, P D C; Baumberger, F

    2014-10-24

    We report on the formation of a two-dimensional electron gas (2DEG) at the bare surface of (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with a sixfold symmetric Fermi surface and strongly anisotropic effective masses. The electronic structure of the 2DEG is in good agreement with self-consistent tight-binding supercell calculations that incorporate a confinement potential due to surface band bending. We further demonstrate that alternate exposure of the surface to ultraviolet light and atomic oxygen allows tuning of the carrier density and the complete suppression of the 2DEG. PMID:25379937

  8. Control of a Two-Dimensional Electron Gas on SrTiO3(111) by Atomic Oxygen

    NASA Astrophysics Data System (ADS)

    McKeown Walker, S.; de la Torre, A.; Bruno, F. Y.; Tamai, A.; Kim, T. K.; Hoesch, M.; Shi, M.; Bahramy, M. S.; King, P. D. C.; Baumberger, F.

    2014-10-01

    We report on the formation of a two-dimensional electron gas (2DEG) at the bare surface of (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with a sixfold symmetric Fermi surface and strongly anisotropic effective masses. The electronic structure of the 2DEG is in good agreement with self-consistent tight-binding supercell calculations that incorporate a confinement potential due to surface band bending. We further demonstrate that alternate exposure of the surface to ultraviolet light and atomic oxygen allows tuning of the carrier density and the complete suppression of the 2DEG.

  9. An improved oxygen diffusion model to explain the effect of low-temperature baking on high field losses in niobium superconducting cavities

    SciTech Connect

    Ciovati, Gianluigi

    2006-07-01

    Radio-frequency (RF) superconducting cavities made of high purity niobium are widely used to accelerate charged particle beams in particle accelerators. The major limitation to achieve RF field values approaching the theoretical limit for niobium is represented by ''anomalous'' losses which degrade the quality factor of the cavities starting at peak surface magnetic fields of about 100 mT, in absence of field emission. These high field losses are often referred to as ''Q-drop''. It has been observed that the Q-drop is drastically reduced by baking the cavities at 120 C for about 48 h under ultrahigh vacuum. An improved oxygen diffusion model for the niobium-oxide system is proposed to explain the benefit of the low-temperature baking on the Q-drop in niobium superconducting rf cavities. The model shows that baking at 120 C for 48 h allows oxygen to diffuse away from the surface, and therefore increasing the lower critical field towards the value for pure niobium.

  10. Effects of silicon (Si) on arsenic (As) accumulation and speciation in rice (Oryza sativa L.) genotypes with different radial oxygen loss (ROL).

    PubMed

    Wu, Chuan; Zou, Qi; Xue, Shengguo; Mo, Jingyu; Pan, Weisong; Lou, Laiqing; Wong, Ming Hung

    2015-11-01

    Arsenic (As) contamination of paddy soils has adversely affected the health of millions of people those consuming rice for staple food. The present study was aimed at investigating the effects of silicon (Si) fertilization on As uptake, speciation in rice plants with different radial oxygen loss (ROL). Six genotypes were planted in pot soils under greenhouse conditions until late tillering state. The results showed that the rates of ROL were higher in hybrid rice genotypes varying from 19.76 to 27 μmol O2 g(-1) root dry weight h(-1) than that in conventional indica rice genotypes varying from 9.55 to 15.41 μmol O2 g(-1) root dry weight h(-1). Si addition significantly increased straw biomass (p<0.005), but with no significant effects on root biomass. Si fertilization significantly reduced shoot and root total As concentrations (p<0.001) in six genotypes grown in 40 mg As/kg soil. Si addition decreased the inorganic As in shoots of 'Xiangfengyou-9' with lower ROL and 'Xiangwanxian-12' with higher ROL by 31% and 25% respectively and had the tendency to increase DMA concentrations. It is potential to reduce As contamination of rice efficiently by combining Si fertilization and selecting genotypes with high radial oxygen loss. PMID:26171731

  11. An in-situ gas chromatography investigation into the suppression of oxygen gas evolution by coated amorphous cobalt-phosphate nanoparticles on oxide electrode

    PubMed Central

    Gim, Jihyeon; Song, Jinju; Kim, Sungjin; Jo, Jeonggeun; Kim, Seokhun; Yoon, Jaegu; Kim, Donghan; Hong, Suk-Gi; Park, Jin-Hwan; Mathew, Vinod; Han, Junhee; Song, Sun-Ju; Kim, Jaekook

    2016-01-01

    The real time detection of quantitative oxygen release from the cathode is performed by in-situ Gas Chromatography as a tool to not only determine the amount of oxygen release from a lithium-ion cell but also to address the safety concerns. This in-situ gas chromatography technique monitoring the gas evolution during electrochemical reaction presents opportunities to clearly understand the effect of surface modification and predict on the cathode stability. The oxide cathode, 0.5Li2MnO3∙0.5LiNi0.4Co0.2Mn0.4O2, surface modified by amorphous cobalt-phosphate nanoparticles (a-CoPO4) is prepared by a simple co-precipitation reaction followed by a mild heat treatment. The presence of a 40 nm thick a-CoPO4 coating layer wrapping the oxide powders is confirmed by electron microscopy. The electrochemical measurements reveal that the a-CoPO4 coated overlithiated layered oxide cathode shows better performances than the pristine counterpart. The enhanced performance of the surface modified oxide is attributed to the uniformly coated Co-P-O layer facilitating the suppression of O2 evolution and offering potential lithium host sites. Further, the formation of a stable SEI layer protecting electrolyte decomposition also contributes to enhanced stabilities with lesser voltage decay. The in-situ gas chromatography technique to study electrode safety offers opportunities to investigate the safety issues of a variety of nanostructured electrodes. PMID:27001370

  12. An in-situ gas chromatography investigation into the suppression of oxygen gas evolution by coated amorphous cobalt-phosphate nanoparticles on oxide electrode.

    PubMed

    Gim, Jihyeon; Song, Jinju; Kim, Sungjin; Jo, Jeonggeun; Kim, Seokhun; Yoon, Jaegu; Kim, Donghan; Hong, Suk-Gi; Park, Jin-Hwan; Mathew, Vinod; Han, Junhee; Song, Sun-Ju; Kim, Jaekook

    2016-01-01

    The real time detection of quantitative oxygen release from the cathode is performed by in-situ Gas Chromatography as a tool to not only determine the amount of oxygen release from a lithium-ion cell but also to address the safety concerns. This in-situ gas chromatography technique monitoring the gas evolution during electrochemical reaction presents opportunities to clearly understand the effect of surface modification and predict on the cathode stability. The oxide cathode, 0.5Li2MnO3∙0.5LiNi0.4Co0.2Mn0.4O2, surface modified by amorphous cobalt-phosphate nanoparticles (a-CoPO4) is prepared by a simple co-precipitation reaction followed by a mild heat treatment. The presence of a 40 nm thick a-CoPO4 coating layer wrapping the oxide powders is confirmed by electron microscopy. The electrochemical measurements reveal that the a-CoPO4 coated overlithiated layered oxide cathode shows better performances than the pristine counterpart. The enhanced performance of the surface modified oxide is attributed to the uniformly coated Co-P-O layer facilitating the suppression of O2 evolution and offering potential lithium host sites. Further, the formation of a stable SEI layer protecting electrolyte decomposition also contributes to enhanced stabilities with lesser voltage decay. The in-situ gas chromatography technique to study electrode safety offers opportunities to investigate the safety issues of a variety of nanostructured electrodes. PMID:27001370

  13. An in-situ gas chromatography investigation into the suppression of oxygen gas evolution by coated amorphous cobalt-phosphate nanoparticles on oxide electrode

    NASA Astrophysics Data System (ADS)

    Gim, Jihyeon; Song, Jinju; Kim, Sungjin; Jo, Jeonggeun; Kim, Seokhun; Yoon, Jaegu; Kim, Donghan; Hong, Suk-Gi; Park, Jin-Hwan; Mathew, Vinod; Han, Junhee; Song, Sun-Ju; Kim, Jaekook

    2016-03-01

    The real time detection of quantitative oxygen release from the cathode is performed by in-situ Gas Chromatography as a tool to not only determine the amount of oxygen release from a lithium-ion cell but also to address the safety concerns. This in-situ gas chromatography technique monitoring the gas evolution during electrochemical reaction presents opportunities to clearly understand the effect of surface modification and predict on the cathode stability. The oxide cathode, 0.5Li2MnO3•0.5LiNi0.4Co0.2Mn0.4O2, surface modified by amorphous cobalt-phosphate nanoparticles (a-CoPO4) is prepared by a simple co-precipitation reaction followed by a mild heat treatment. The presence of a 40 nm thick a-CoPO4 coating layer wrapping the oxide powders is confirmed by electron microscopy. The electrochemical measurements reveal that the a-CoPO4 coated overlithiated layered oxide cathode shows better performances than the pristine counterpart. The enhanced performance of the surface modified oxide is attributed to the uniformly coated Co-P-O layer facilitating the suppression of O2 evolution and offering potential lithium host sites. Further, the formation of a stable SEI layer protecting electrolyte decomposition also contributes to enhanced stabilities with lesser voltage decay. The in-situ gas chromatography technique to study electrode safety offers opportunities to investigate the safety issues of a variety of nanostructured electrodes.

  14. COMPONENT LOSS DURING EVAPORATION-RECONSTITUTION OF ORGANIC ENVIRONMENTAL SAMPLES FOR GAS CHROMATOGRAPHIC ANALYSIS

    EPA Science Inventory

    Standard and sample solutions stored in borosilicate sample vials were allowed to evaporate to dryness at room temperature. The solutions were analyzed by gas chromatography-flame ionization detection before evaporation and after reconstitution to the original volume to determine...

  15. Oxygen loss induced by swift heavy ions of low and high dE/dx in PMMA thin films

    NASA Astrophysics Data System (ADS)

    Thomaz, R.; Gutierres, L. I.; Morais, J.; Louette, P.; Severin, D.; Trautmann, C.; Pireaux, J. J.; Papaléo, R. M.

    2015-12-01

    Investigations on the chemical modifications induced by swift heavy ions in PMMA thin films were carried out using beams of high dE/dx (2.2 GeV Bi, 14,090 eV/nm) and low dE/dx (2 MeV H, 19 eV/nm). The induced chemical modifications were monitored by XPS for films with initial thickness of 50 and 100 nm. For both beams, the irradiation decreased the amount of carbon atoms bound to oxygen (Cdbnd O and Csbnd Osbnd C), with a larger decrease of the carboxyl moiety, as expected. However, the chemical changes induced by light and heavy ions were qualitatively different. For the same mean deposited energy density, proton irradiation induced a decrease of the relative intensity of the carbon-oxygen bonds up to ∼20% larger than the irradiation with Bi ions. This suggests a greater importance of particle ejection by unzipping of PMMA chains at high dE/dx, which tends to keep the O/C ratio closer to the pristine value.

  16. The Determination of the Percent of Oxygen in Air Using a Gas Pressure Sensor

    ERIC Educational Resources Information Center

    Gordon, James; Chancey, Katherine

    2005-01-01

    The experiment of determination of the percent of oxygen in air is performed in a general chemistry laboratory in which students compare the results calculated from the pressure measurements obtained with the calculator-based systems to those obtained in a water-measurement method. This experiment allows students to explore a fundamental reaction…

  17. Membrane oxygenator heat exchanger failure detected by unique blood gas findings.

    PubMed

    Hawkins, Justin L

    2014-03-01

    Failure of components integrated into the cardiopulmonary bypass circuit, although rare, can bring about catastrophic results. One of these components is the heat exchanger of the membrane oxygenator. In this compartment, unsterile water from the heater cooler device is separated from the sterile blood by stainless steel, aluminum, or by polyurethane. These areas are glued or welded to keep the two compartments separate, maintaining sterility of the blood. Although quality control testing is performed by the manufacturer at the factory level, transport presents the real possibility for damage. Because of this, each manufacturer has included in the instructions for use a testing procedure for testing the integrity of the heat exchanger component. Water is circulated through the heat exchanger before priming and a visible check is made of the oxygenator bundle to check for leaks. If none are apparent, then priming of the oxygenator is performed. In this particular case, this procedure was not useful in detecting communication between the water and blood chambers of the oxygenator. PMID:24779125

  18. Study of oxygen gas production phenomenon during stand and discharge in silver-zinc batteries

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Standard production procedures for manufacturing silver zinc batteries are evaluated and modified to reduce oxygen generation during open circuit stand and discharge. Production predictions of several variable combinations using analysis models are listed for minimum gassing, with emphasis on the concentration of potassium hydroxide in plate formation. A recommendation for work optimizing the variables involved in plate processing is included.

  19. Experimental load capacity and power loss of herringbone grooved gas lubricated journal bearings.

    NASA Technical Reports Server (NTRS)

    Cunningham, R. E.; Fleming, D. P.; Anderson, W. J.

    1971-01-01

    Load capacity, attitude angle, and power loss were determined for 1-1/2-in.-diam herringbone grooved journal bearings operating in air to speeds of 60,000 rpm. Results showed that groove-to-ridge-clearance ratios of 2.0 to 2.4 give a greater load capacity than do ratios outside this optimum range. Agreement with a small-eccentricity pressure perturbation theory was good for groove-to-ridge-clearance ratios in the optimum range. Power loss, relative to that calculated for a plain bearing of the same dimensions, did not vary widely for the range of geometric variables used. Relative power loss generally increased with speed and was generally comparable to that for a plain bearing.

  20. Identification of SEA coupling loss factors on a liquid rocket engine

    NASA Astrophysics Data System (ADS)

    Borello, G.; Alliot; Kernilis

    A test was performed on a full-scale model of the cryogenic engine of the VULCAIN in order to elucidate the power flow exchanges between the components and to quantify the losses at joints, and in effect to create a data base for coupling loss factors and damping loss factors. The relative damping loss factors of the different components are plotted. The most damped components are the oxygen turbopump and the hydrogen turbopump. The coupling loss factors of the oxygen turbopump with its connected components (nozzle, gas generator, and oxygen exhaust line) are shown.

  1. West Siberian gas accumulations - the origin of methane and losses to the atmosphere

    SciTech Connect

    Cramer, B.; Littke, R.; Braun, A. )

    1996-01-01

    West Siberia is the most prolific gas producing sedimentary basin of the world. Nevertheless the problem of the origin of these large gas accumulations has not yet been solved. Late thermogenic gas generation from Jurassic strata (usually 3500 m and deeper) and early thermogenic or bacterial gas generation from Cenomanian to Aptian strata (usually at 600 to 2500 m depth) are the processes currently in discussion. Organic-geochemical analyses of 150 core samples as well as compositional and isotopic data of about 120 gases provided the database of this study. The Cenomanian reservoirs contain almost pure methane (average 98.6% CH[sub 4]) with [delta][sup 13]C of methane as light as -55[per thousand], while the gases from Neocomian and Jurassic reservoirs show more positive values, which are typical for high maturity source rocks. A model of linear mixing between Cenomanian and Jurassic gases fits fairly well with the observed compositional trends. This model indicates that up to 90% of the Cenomanian methane was probably generated in the Cenomanian-Aptian sequence. The question of bacterial versus early thermogenic generation will be discussed. Wireline log interpretation allowed the detection of up to three layers of permafrost in this region, which might be effective seals to prevent upward gas migration. Surface geochemical measurements show no detectable amounts of methane diffusing from the reservoirs into the atmosphere.

  2. West Siberian gas accumulations - the origin of methane and losses to the atmosphere

    SciTech Connect

    Cramer, B.; Littke, R.; Braun, A.

    1996-12-31

    West Siberia is the most prolific gas producing sedimentary basin of the world. Nevertheless the problem of the origin of these large gas accumulations has not yet been solved. Late thermogenic gas generation from Jurassic strata (usually 3500 m and deeper) and early thermogenic or bacterial gas generation from Cenomanian to Aptian strata (usually at 600 to 2500 m depth) are the processes currently in discussion. Organic-geochemical analyses of 150 core samples as well as compositional and isotopic data of about 120 gases provided the database of this study. The Cenomanian reservoirs contain almost pure methane (average 98.6% CH{sub 4}) with {delta}{sup 13}C of methane as light as -55{per_thousand}, while the gases from Neocomian and Jurassic reservoirs show more positive values, which are typical for high maturity source rocks. A model of linear mixing between Cenomanian and Jurassic gases fits fairly well with the observed compositional trends. This model indicates that up to 90% of the Cenomanian methane was probably generated in the Cenomanian-Aptian sequence. The question of bacterial versus early thermogenic generation will be discussed. Wireline log interpretation allowed the detection of up to three layers of permafrost in this region, which might be effective seals to prevent upward gas migration. Surface geochemical measurements show no detectable amounts of methane diffusing from the reservoirs into the atmosphere.

  3. The gas conversion of methane with oxygen at atmospheric pressure using a cylindrical dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Martens, Tom; Petrovic, Dragana; de Bie, Christophe; Bogaerts, Annemie; Brok, Wouter; van Dijk, Jan

    2008-10-01

    The conversion of methane to useful chemicals and liquid fuels currently requires steam reforming, which requires great amounts of energy input. We are currently investigating the possibilities of using a plasma activated system for this gas conversion. Due to the pulsed nature and the low operating temperature capabilities, we have chosen the atmospheric pressure dielectric barrier discharge as a setup to investigate whether it can be used as a more efficient gas conversion reactor. For this purpose we have developed a CH4/O2 chemical reaction set and used it in a 2D fluid model of a cylindrical dielectric barrier discharge, in which we also incorporate the influence of the gas flow. In this way we investigate whether we can optimize the production of methanol or formaldehyde. The parameters under study are the CH4/O2 ratio, the applied voltage characteristics, the gap width and the gas flow rate.

  4. Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

    DOEpatents

    Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

    2003-09-23

    Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

  5. Quantum-size effects in the energy loss of charged particles interacting with a confined two-dimensional electron gas

    SciTech Connect

    Borisov, A. G.; Juaristi, J. I.

    2006-01-15

    Time-dependent density-functional theory is used to calculate quantum-size effects in the energy loss of antiprotons interacting with a confined two-dimensional electron gas. The antiprotons follow a trajectory normal to jellium circular clusters of variable size, crossing every cluster at its geometrical center. Analysis of the characteristic time scales that define the process is made. For high-enough velocities, the interaction time between the projectile and the target electrons is shorter than the time needed for the density excitation to travel along the cluster. The finite-size object then behaves as an infinite system, and no quantum-size effects appear in the energy loss. For small velocities, the discretization of levels in the cluster plays a role and the energy loss does depend on the system size. A comparison to results obtained using linear theory of screening is made, and the relative contributions of electron-hole pair and plasmon excitations to the total energy loss are analyzed. This comparison also allows us to show the importance of a nonlinear treatment of the screening in the interaction process.

  6. Gas-phase Oxygen Abundances and Radial Metallicity Gradients in the Two nearby Spiral Galaxies NGC 7793 and NGC 4945

    NASA Astrophysics Data System (ADS)

    Stanghellini, Letizia; Magrini, Laura; Casasola, Viviana

    2015-10-01

    Gas-phase abundances in H ii regions of two spiral galaxies, NGC 7793 and NGC 4945, have been studied to determine their radial metallicity gradients. We used the strong-line method to derive oxygen abundances from spectra acquired with GMOS-S, the multi-object spectrograph on the 8 m Gemini South telescope. We found that NGC 7793 has a well-defined gas-phase radial oxygen gradient of -0.321 ± 0.112 dex {R}25-1 (or -0.054 ± 0.019 dex kpc-1) in the galactocentric range 0.17 < RG/R25 < 0.82, not dissimilar from gradients calculated with direct abundance methods in galaxies of similar mass and morphology. We also determined a shallow radial oxygen gradient in NGC 4945, -0.253 ± 0.149 dex {R}25-1 (or -0.019 ± 0.011 dex kpc-1) for 0.04 < RG/R25 < 0.51, where the larger relative uncertainty derives mostly from the larger inclination of this galaxy. NGC 7793 and NGC 4945 have been selected for this study because they are similar, in mass and morphology, to M33 and the Milky Way, respectively. Since at zeroth order we expect the radial metallicity gradients to depend on mass and galaxy type, we compared our galaxies in the framework of radial metallicity models best suited for M33 and the Galaxy. We found a good agreement between M33 and NGC 7793, pointing toward similar evolution for the two galaxies. We notice instead differences between NGC 4945 and the radial metallicity gradient model that best fits the Milky Way. We found that these differences are likely related to the presence of an active galactic nucleus combined with a bar in the central regions of NGC 4945, and to its interacting environment.

  7. Oxygen analyzer

    DOEpatents

    Benner, W.H.

    1984-05-08

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N/sub 2/), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable obtained by decomposing the sample at 1135/sup 0/C, or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135/sup 0/C as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N/sub 2/, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  8. Gas-phase particle size distributions and lead loss during spray pyrolysis of (Bi,Pb)--Sr--Ca--Cu--O

    SciTech Connect

    Gurav, A.S.; Kodas, T.T.; Joutsensaari, J.; Kauppinen, E.I.; Zilliacus, R.

    1995-07-01

    Gas-phase particle size distributions and lead loss were measured during formation of (Bi,Pb)--Sr--Ca--Cu--O and pure PbO particles by spray pyrolysis at different temperatures. A differential mobility analyzer (DMA) in conjunction with a condensation particle counter (CPC) was used to monitor the gas-phase particle size distributions, and a Berner-type low-pressure impactor was used to obtain mass size distributions and a Berner-type low-pressure impactor was used to obtain mass size distributions and size-classified samples for chemical analysis. For (Bi,Pb)--Sr--Ca--Cu--O, as the processing temperature was raised from 200 to 700 {degree}C, the number average particle size decreased due to metal nitrate decomposition, intraparticle reactions forming mixed-metal oxides and particle densification. The geometric number mean particle diameter was 0.12 {mu}m at 200 {degree}C and reduced to 0.08 and 0.07 {mu}m, respectively, at 700 and 900 {degree}C. When the reactor temperature was raised from 700 and 800 {degree}C to 900 {degree}C, a large number ({similar_to}10{sup 7} no./cm{sup 3}) of new ultrafine particles were formed from PbO vapor released from the particles and the reactor walls. Particles made at temperatures up to 700 {degree}C maintained their initial stoichiometry over the whole range of particle size monitored, however; those made at 800 {degree}C and above were heavily depleted in lead in the size range 0.5--5.0 {mu}m. The evaporative losses of lead oxide from (Bi,Pb)--Sr--Ca--Cu--O particles were compared with the losses from PbO particles to gain insight into the pathways involved in lead loss and the role of intraparticle processes in controlling it.

  9. On-line derivatization for hourly measurements of gas- and particle-phase Semi-Volatile oxygenated organic compounds by Thermal desorption Aerosol Gas chromatography (SV-TAG)

    NASA Astrophysics Data System (ADS)

    Isaacman, G.; Kreisberg, N. M.; Yee, L. D.; Worton, D. R.; Chan, A. W. H.; Moss, J. A.; Hering, S. V.; Goldstein, A. H.

    2014-07-01

    Laboratory oxidation studies have identified a large number of oxygenated organic compounds that can be used as tracers to understand sources and oxidation chemistry of atmospheric particulate matter. Quantification of these compounds in ambient environments has traditionally relied on low time-resolution collection of filter samples followed by offline sample treatment with a derivatizing agent to allow analysis by gas chromatography of otherwise non-elutable organic chemicals with hydroxyl groups. We present here an automated in situ instrument for the measurement of highly polar organic semi-volatile and low-volatility compounds in both the gas- and particle-phase with hourly time-resolution. The dual-cell Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SV-TAG) with derivatization collects particle-only and combined particle-plus-vapor samples on two parallel sampling cells that are analyzed in series by thermal desorption into helium saturated with derivatizing agent. Introduction of MSTFA, a silylating agent, yields complete derivatization of all tested compounds, including alkanoic acids, polyols, diacids, sugars, and multifunctional compounds. In laboratory tests, derivatization is found to be highly reproducible (< 3% variability). During field deployment, a regularly injected internal standard is used to correct for variability in detector response, derivatization efficiency, desorption efficiency, and transfer efficiency. Error in quantification from instrument fluctuations is found to be less than 10% for hydrocarbons and less than 15% for all oxygenates for which a functionally similar internal standard is available. After internal standard corrections, calibration curves are found to be linear for all compounds over the span of one month with comparable response on both of the parallel sampling cells.

  10. Study of oxygen gas production phenomenon during stand and discharge in silver-zinc batteries

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The effects of a number of cell process and performance variables upon the oxygen evolution rate of silver/silver oxide cathodes are studied to predict and measure the conditions which would result in the production of a minimum of oxygen. The following five tasks comprise the study: the design and fabrication of two pilot test cells to be used for electrode testing; the determination of the sensitivity and accuracy of the test cell; the determination of total volumes and rates of generation by cathodes of standard production procedures; the construction of a sequential test plan; and the construction of a series of positive formation cells in which formation process factors can be controlled.

  11. N-loss isotope effects in the Peru oxygen minimum zone studied using a mesoscale eddy as a natural tracer experiment

    NASA Astrophysics Data System (ADS)

    Bourbonnais, Annie; Altabet, Mark A.; Charoenpong, Chawalit N.; Larkum, Jennifer; Hu, Haibei; Bange, Hermann W.; Stramma, Lothar

    2015-06-01

    Mesoscale eddies in Oxygen Minimum Zones (OMZs) have been identified as important fixed nitrogen (N) loss hotspots that may significantly impact both the global rate of N-loss as well as the ocean's N isotope budget. They also represent "natural tracer experiments" with intensified biogeochemical signals that can be exploited to understand the large-scale processes that control N-loss and associated isotope effects (ɛ; the ‰ deviation from 1 in the ratio of reaction rate constants for the light versus heavy isotopologues). We observed large ranges in the concentrations and N and O isotopic compositions of nitrate (NO3-), nitrite (NO2-), and biogenic N2 associated with an anticyclonic mode-water eddy in the Peru OMZ during two cruises in November and December 2012. In the eddy's center where NO3- was nearly exhausted, we measured the highest δ15N values for both NO3- and NO2- (up to ~70‰ and 50‰) ever reported for an OMZ. Correspondingly, N deficit and biogenic N2-N concentrations were also the highest near the eddy's center (up to ~40 µmol L-1). δ15N-N2 also varied with biogenic N2 production, following kinetic isotopic fractionation during NO2- reduction to N2 and, for the first time, provided an independent assessment of N isotope fractionation during OMZ N-loss. We found apparent variable ɛ for NO3- reduction (up to ~30‰ in the presence of NO2-). However, the overall ɛ for N-loss was calculated to be only ~13-14‰ (as compared to canonical values of ~20-30‰) assuming a closed system and only slightly higher assuming an open system (16-19‰). Our results were similar whether calculated from the disappearance of DIN (NO3- + NO2-) or from the appearance of N2 and changes in isotopic composition. Further, we calculated the separate ɛ values for NO3- reduction to NO2- and NO2- reduction to N2 of ~16-21‰ and ~12‰, respectively, when the effect of NO2- oxidation could be removed. These results, together with the relationship between N and O of NO

  12. Pulsed electron-beam sustained discharge CO laser on oxygen-containing gas mixtures

    SciTech Connect

    Ionin, A A; Klimachev, Yu M; Kozlov, A Yu; Kotkov, A A; Seleznev, L V

    2008-02-28

    It is shown that the addition of molecular oxygen to the working mixture of a pulsed electron-beam sustained-discharge (EBSD) laser CO amplifier leads to the increase in the small-signal gain (SSG) at the fundamental vibrational v+1{yields}v transitions in a CO molecule for v=6-13, which is explained by the increase in the population of vibrational levels. In this case, the temporal parameters of the dynamics decrease at all probed transitions. Variations observed in the SSG dynamics are explained by analysing the kinetic processes of vibrational-vibrational exchange between molecules. The study of lasing parameters of a pulsed CO laser showed that the threshold energy input decreased with increasing the oxygen content in the working mixture. It is found that the CO laser efficiency at fundamental transitions increases with the addition of oxygen, the maximum efficiency being achieved at lower energy inputs. It is shown that the pulsed EBSD CO laser can operate on the air working mixture both at the fundamental transitions and the first vibrational overtone transitions v+2{yields}v. (lasers. amplifiers)

  13. Decreasing phosphorus loss in tile-drained landscapes using flue gas desulfurization gypsum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Elevated phosphorus (P) loading from agricultural non-point source pollution continues to impair inland waterbodies throughout the world. The application of flue gas desulfurization (FGD) gypsum to agricultural fields has been suggested to decrease P loading because of its high calcium content and P...

  14. Fertilizer induced losses of nitrous oxide gas from Montana dryland cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen fertilization to crops contributes a significant portion of soil nitrous oxide (N2O) emission, a greenhouse gas responsible for global warming. This information is, however, lacking in the dryland cropping system in the northern Great Plains. Soil N2O and methane (CH4) fluxes from May to No...

  15. Influence of Oxygen Gas Ratio on the Properties of Aluminum-Doped Zinc Oxide Films Prepared by Radio Frequency Magnetron Sputtering.

    PubMed

    Kim, Minha; Jang, Yong-Jun; Jung, Ho-Sung; Song, Woochang; Kang, Hyunil; Kim, Eung Kwon; Kim, Donguk; Yi, Junsin; Lee, Jaehyeong

    2016-05-01

    Aluminum-doped zinc oxide (AZO) thin films were deposited on glass and polyimide substrates using radio frequency magnetron sputtering. We investigated the effects of the oxygen gas ratio on the properties of the AZO films for Cu(In,Ga)Se2 thin-film solar cell applications. The structural and optical properties of the AZO thin films were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and UV-Visible-NIR spectrophotometry. The oxygen gas ratio played a crucial role in controlling the optical as well as electrical properties of the films. When oxygen gas was added into the film, the surface AZO thin films became smoother and the grains were enlarged while the preferred orientation changed from (0 0 2) to (1 0 0) plane direction of the hexagonal phase. An improvement in the transmittance of the AZO thin films was achieved with the addition of 2.5-% oxygen gas. The electrical resistivity was highly increased even for a small amount of the oxygen gas addition. PMID:27483888

  16. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUIDIZED BED BOILERS: PHASE II--PILOT SCALE TESTING AND UPDATED PERFORMANCE AND ECONOMICS FOR OXYGEN FIRED CFB WITH CO2 CAPTURE

    SciTech Connect

    Nsakala ya Nsakala; Gregory N. Liljedahl; David G. Turek

    2004-10-27

    Because fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this Phase II study, ALSTOM Power Inc. (ALSTOM) has investigated one promising near-term coal fired power plant configuration designed to capture CO{sub 2} from effluent gas streams for sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}, along with some moisture, nitrogen, oxygen, and trace gases like SO{sub 2} and NO{sub x}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than in PC or Stoker firing, because recirculated gas flow can be reduced significantly. Oxygen-fired PC and Stoker units require large quantities of recirculated flue gas to maintain acceptable furnace temperatures. Oxygen-fired CFB units, on the other hand, can accomplish this by additional cooling of recirculated solids. The reduced recirculated gas flow with CFB plants results in significant Boiler Island cost savings resulting from reduced component The overall objective of the Phase II workscope, which is the subject of this report, is to generate a refined technical and economic evaluation of the Oxygen fired CFB case (Case-2 from Phase I) utilizing the information learned from pilot-scale testing of this concept. The objective of the pilot-scale testing was to generate detailed technical data needed to establish advanced CFB design requirements and performance when firing coals and

  17. Estimating oxygen diffusive conductances of gas-exchange systems: A stereological approach illustrated with the human placenta.

    PubMed

    Mayhew, Terry M

    2014-01-01

    For many organisms, respiratory gas exchange is a vital activity and different types of gas-exchange apparatus have evolved to meet individual needs. They include not only skin, gills, tracheal systems and lungs but also transient structures such as the chorioallantois of avian eggs and the placenta of eutherian mammals. The ability of these structures to allow passage of oxygen by passive diffusion can be expressed as a diffusive conductance (units: cm(3) O2 min(-1) kPa(-1)). Occasionally, the ability to estimate diffusive conductance by physiological techniques is compromised by the difficulty of obtaining O2 partial pressures on opposite sides of the tissue interface between the delivery medium (air, water, blood) and uptake medium (usually blood). An alternative strategy is to estimate a morphometric diffusive conductance by combining stereological estimates of key structural quantities (volumes, surface areas, membrane thicknesses) with complementary physicochemical data (O2-haemoglobin chemical reaction rates and Krogh's permeability coefficients). This approach has proved valuable in a variety of comparative studies on respiratory organs from diverse species. The underlying principles were formulated in pioneering studies on the pulmonary lung but are illustrated here by taking the human placenta as the gas exchanger. PMID:23069190

  18. Oxygen transport resistance at gas diffusion layer - Air channel interface with film flow of water in a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa; Kandlikar, Satish G.

    2016-01-01

    Water present as films on the gas diffusion layer-air channel interface in a proton exchange membrane fuel cell (PEMFC) alters the oxygen transport resistance, which is expressed through Sherwood number (Sh). The effect of multiple films along the flow length on Sh is investigated through 3D and stationary simulations. The effects of air Péclet number, non-dimensional film width, length, and spacing are studied. Using the simulation results, non-dimensional correlations are developed for local Sh within a mean absolute percentage error of 9%. These correlations can be used for simulating PEMFC performance over temperature and relative humidity ranges of 20-80 °C and 0-100%, respectively. Sh on the film side can be up to 31% lower than that for a dry channel, while a film may reduce the interfacial width by up to 39%. The corresponding increase in transport resistance results in lowering the voltage by 5 and 8 mV respectively at a current density of 1.5 A cm-2. However, their combined effect leads to a voltage loss of 20 mV due to this additional mass transport resistance. It is therefore important to incorporate the additional resistance introduced by the films while modeling fuel cell performance.

  19. The nitrogen and oxygen abundances in the neutral gas at high redshift

    NASA Astrophysics Data System (ADS)

    Petitjean, P.; Ledoux, C.; Srianand, R.

    2008-03-01

    Aims:We study the oxygen and nitrogen abundances in the interstellar medium of high-redshift galaxies. Methods: We use high resolution and high signal-to-noise ratio spectra of damped Lyman-α (DLA) systems detected along the line-of-sight to quasars to derive robust abundance measurements from unsaturated metal absorption lines. Results: We present results for a sample of 16 high-redshift DLAs and strong sub-DLAs (log N(H I) > 19.5, 2.4 < z_abs < 3.6) including 13 new measurements. We find that the oxygen to iron abundance ratio is pretty much constant with [O/Fe] ~ +0.32±0.10 for -2.5 < [O/H] < -1.0 with a small scatter around this value. The oxygen abundance follows quite well the silicon abundance within ~0.2 dex, although the silicon abundance could be slightly smaller for [O/H] < -2. The distribution of the [N/O] abundance ratio, measured from components that are detected in both species, is somehow double peaked: five systems have [N/O] > -1 and nine systems have [N/O] < -1.15. In the diagram [N/O] versus [O/H], a loose plateau is possibly present at [N/O] ~ -0.9, which is below the so-called primary plateau as seen in local metal-poor dwarf galaxies ([N/O] in the range -0.57 to -0.74). No system is seen above this primary plateau whereas the majority of the systems lie well below with a large scatter. All this suggests a picture in which DLAs undergo successive star-bursts. During such an episode, the [N/O] ratio decreases sharply because of the rapid release of oxygen by massive stars, whereas inbetween two bursts, nitrogen is released by low and intermediate-mass stars with a delay and the [N/O] ratio increases. Based on observations carried out at the European Southern Observatory (ESO), under visitor mode progs. ID 65.O-0063, 66.A-0624, 67.A-0078 and 68.A-0600 with the UVES echelle spectrograph installed at the ESO Very Large Telescope (VLT), unit Kueyen, on mount Paranal in Chile. Also based on archival data from progs. 68.A-0492 (PI: D'Odorico), 68.B

  20. Redox Switching of Orthoquinone-Containing Aromatic Compounds with Hydrogen and Oxygen Gas.

    PubMed

    Urakawa, Kazuki; Sumimoto, Michinori; Arisawa, Mitsuhiro; Matsuda, Masaki; Ishikawa, Hayato

    2016-06-20

    Unique redox switching of orthoquinone-containing pentacyclic aromatic compounds with molecular hydrogen and oxygen in the presence of a palladium nanoparticle catalyst (SAPd) is disclosed. These molecules were predicted by in silico screening before synthesis. Efficient protocols for the synthesis of orthoquinone-containing aromatic compounds by palladium-mediated homocoupling and the benzoin condensation reaction were developed. Clear switching between orthoquinone and aromatic hydroquinone compounds was observed on the basis of their photoluminescence properties. Furthermore, the twist strain of the orthoquinone moiety could induce dramatic changes in color and emission. PMID:27145376

  1. Alveolar gas exchange, oxygen delivery and tissue deoxygenation in men and women during incremental exercise.

    PubMed

    Peltonen, Juha E; Hägglund, Harriet; Koskela-Koivisto, Tiina; Koponen, Anne S; Aho, Jyrki M; Rissanen, Antti-Pekka E; Shoemaker, J Kevin; Tiitinen, Aila; Tikkanen, Heikki O

    2013-08-15

    We investigated whether leg and arm skeletal muscle, and cerebral deoxygenation, differ during incremental cycling exercise in men and women, and if women's lower capacity to deliver O2 affects tissue deoxygenation. Men (n=10) compared to women (n=10), had greater cardiac output, which with greater hemoglobin concentration produced greater absolute (QaO2) and body size-adjusted oxygen delivery (QaO2i) at peak exercise. Despite women's lower peak QaO2, their leg muscle deoxygenation was similar at a given work rate and QaO2, but less than in men at peak exercise (Δtissue saturation index -27.1 ± 13.2% vs. -11.8 ± 5.7%, P<0.01; Δ[deoxyhemoglobin] 15.03 ± 8.57 μM vs. 3.73 ± 3.98 μM, P<0.001). At peak exercise, oxygen uptake was associated both with QaO2 and leg muscle deoxygenation (both P<0.01). Arm muscle and cerebral deoxygenation did not differ between sexes at peak exercise. Thus, both high O2 delivery and severe active muscle deoxygenation are determinants of good exercise performance, and active muscle deoxygenation responses are regulated partly in a sex-specific manner with an influence of exercise capacity. PMID:23707876

  2. 20th century human pressures drive reductions in deepwater oxygen leading to losses of benthic methane-based food webs

    NASA Astrophysics Data System (ADS)

    Belle, Simon; Millet, Laurent; Verneaux, Valérie; Lami, Andrea; David, Etienne; Murgia, Laurie; Parent, Claire; Musazzi, Simona; Gauthier, Emilie; Bichet, Vincent; Magny, Michel

    2016-04-01

    Freshwater lakes play a key role in the global carbon cycle as sinks (organic carbon sequestration) and sources (greenhouse gas emissions). Understanding the carbon cycle response to environmental changes is becoming a crucial challenge in the context of global warming and the preponderance of human pressures. We reconstructed the long-term (1500 years) evolution of trophic functioning of the benthic food web, based on methanotrophic ancient DNA and chironomid isotope analyses). In addition, human land use is also reconstructed in three different lakes (eastern France, Jura Mountains). Our findings confirm that the benthic food web can be highly dependent on methane-derived carbon (up to 50% of the chironomid biomass) and reveal that the activation of this process can correspond to a natural functioning or be a consequence of anthropic perturbation. The studied lakes also showed a similar temporal evolution over the last century with the disappearance of the profundal aquatic insects (Chironomidae, Diptera), considered as keystone for the whole lake food web (e.g., coupling benthic-pelagic), inducing a potential collapse in the transfer of methane to top consumers. This functional state, also called the dead zone expansion, was caused by the change in human land-use occurring at the beginning of the 20th century. The strong modification of agro-pastoral practices (e.g., fertilization practices, intensive grazing, and sewage effluent) modified the influx of nutrients (by diffuse and/or point-source inputs) and induced a significant increase in the trophic status and organic matter sedimentation to reach unprecedented values. Further studies should be planned to assess dead zone expansion and, according to the regime shift theory, to provide environmental tipping points for sustainable resource management.

  3. Rapid Diamond Deposition on Ni and Co Coatings by Using Twin Acetylene/Oxygen Gas Welding Torches

    NASA Astrophysics Data System (ADS)

    Ando, Yasutaka; Noda, Yoshimasa; Adachi, Shin-ichiro

    2015-12-01

    Cermet coatings have been widely used because of their high hardness and excellent wear resistance even under high-temperature conditions. However, since cermet coatings include expensive materials such as WC, TiC, TiN and so on, low-cost hard particles as a dispersing agent need to be developed. In this study, in order to develop a low-cost diamond dispersion system for the creation of diamond/thermal sprayed metal hybrid coatings, diamond deposition on thermal sprayed Ni and Co coatings and Mo and Ni metal substrates by the combustion flame method using twin acetylene/oxygen gas welding torches was carried out. Consequently, even in cases of thermal sprayed Ni and Co coatings, diamond particles could be deposited within only 5 min. From these results, this technique is proved to have a high potential for rapid diamond deposition in order to create diamond/thermal sprayed metal hybrid coatings.

  4. Control of a Two-Dimensional Electron Gas on SrTiO3 (111) by Atomic Oxygen

    NASA Astrophysics Data System (ADS)

    McKeown Walker, Siobhan; de la Torre, A.; Bruno, F. Y.; Tamai, A.; Kim, T. K.; Hoesch, M.; Shi, M.; Bahramy, M. S.; King, P. D. C.; Baumberger, F.

    2015-03-01

    We report on the formation of a two-dimensional electron gas (2DEG) at the bare surface of (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with a 6-fold symmetric Fermi surface and strongly anisotropic effective masses. The electronic structure of the 2DEG is in good agreement with self-consistent tight-binding supercell calculations that incorporate a confinement potential due to surface band bending. Our measurements provide insight into the nontrivial consequences of quantum confinement along the [111] direction which is directly relevant to an understanding of electronic structure at (111) orientated interfaces. We further demonstrate that alternate exposure of the surface to ultraviolet light and atomic oxygen allows tuning of the carrier density and the complete suppression of the 2DEG.

  5. Energy loss of ions and ion clusters in a disordered electron gas

    NASA Astrophysics Data System (ADS)

    Nersisyan, Hrachya B.; Das, Amal K.

    2004-04-01

    The various aspects of the correlated stopping power of pointlike and extended ions moving in a disordered degenerate electron gas have been analytically and numerically studied. Within the linear response theory we have made a systematic and comprehensive investigation of correlated stopping power, vicinage function, and related quantities for protons and extended ions, as well as for their clusters. The disorder, which leads to a damping of plasmons and quasiparticles in the electron gas, is taken into account through a relaxation time approximation in the linear response function. The stopping power for an arbitrary extended ion with a single bound electron is calculated in both the low- and high velocity limitsy. Our analytical results show that in a high velocity limit the main logarithmic contribution to the stopping power for an extened ion is significantly modified and for instance, in the case of He+ , Li2+ , and Be3+ ions must behave as ln ( A v5 ) , ln ( A v3.25 ) , and ln ( A v2.77 ) , respectively where v is the ion velocity. This behavior may be contrasted with the usual ln ( v2 ) dependence for a point ion projectile. It is shown that the factor A which depends on the damping can be significantly reduced by increasing the latter. In order to highlight the effects of damping we present a comparison of our analytical and numerical results, in the case of both pointlike and extended ions, obtained for a nonzero damping with those for a vanishing damping.

  6. Gas analyzer's drift leads to systematic error in maximal oxygen uptake and maximal respiratory exchange ratio determination

    PubMed Central

    Garcia-Tabar, Ibai; Eclache, Jean P.; Aramendi, José F.; Gorostiaga, Esteban M.

    2015-01-01

    The aim was to examine the drift in the measurements of fractional concentration of oxygen (FO2) and carbon dioxide (FCO2) of a Nafion-using metabolic cart during incremental maximal exercise in 18 young and 12 elderly males, and to propose a way in which the drift can be corrected. The drift was verified by comparing the pre-test calibration values with the immediate post-test verification values of the calibration gases. The system demonstrated an average downscale drift (P < 0.001) in FO2 and FCO2 of −0.18% and −0.05%, respectively. Compared with measured values, corrected average maximal oxygen uptakevalues were 5–6% lower (P < 0.001) whereas corrected maximal respiratory exchange ratio values were 8–9% higher (P < 0.001). The drift was not due to an electronic instability in the analyzers because it was reverted after 20 min of recovery from the end of the exercise. The drift may be related to an incomplete removal of water vapor from the expired gas during transit through the Nafion conducting tube. These data demonstrate the importance of checking FO2 and FCO2 values by regular pre-test calibrations and post-test verifications, and also the importance of correcting a possible shift immediately after exercise. PMID:26578980

  7. Decrease in the etch rate of polymers in the oxygen afterglow with increasing gas flow rate

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1988-01-01

    This paper reports the variation of the etch rate of polymers in the afterglow of a radio frequency discharge in oxygen as a function of total flow rate in the range 2-10 cu cm (STP)/min. The measurements were made at ambient temperature with the O(P-3) concentration held essentially constant. Results are reported on three polymers: cis-polybutadiene, a polybutadiene with 33 percent 1,2 double bonds, and a polybutadiene with 40 percent 1,2 double bonds. It has been observed that the etch rate of these polymers decreases significantly with increasing flow rate, strongly suggesting that the vapor-phase products of polymer degradation contribute to the degradation process.

  8. Effect of Oxygen Gas on the Decomposition of Dye by Pulsed Discharge in Water Droplet Spray

    NASA Astrophysics Data System (ADS)

    Nose, Taisuke; Yokoyama, Yuzo; Nakamura, Akira; Minamitani, Yasushi

    Effect of O2 on the decolorization of indigo carmine and on the production of dissolved species such as NO2-, NO3-, O3 and H2O2 in the treatment water by pulsed discharge in water droplet spray was investigated by controlling the O2/N2 ratios as carrier gases in the reactor. The decolorization rate gradually increased with rise in O2 ratio, which reached a constant value in the range of 50% to 90% O2 ratio and decreased in pure O2. The maximum value was about 2 times as high as that of 20% O2 ratio. The decolorization efficiency was not affected by gas flow rate in the range of 4 L/min to 50 L/min. NO2- in the treatment water was only detected in pure N2, but NO3- was produced in O2/N2. NO2- added to the treatment water was not oxidized in pure N2, but was perfectly converted to NO3- in O2/N2. These results implied that hydroxyl radical produced in gas phase does not directly contribute to the oxidation of substances in water. O3 concentration gradually increased with rise in O2 ratio, whereas H2O2 concentration decreased. In the range of 50 to 80% O2 ratio, O3 and H2O2 concentrations were approximately constant value, similar to the trend of decolorization rate. Moreover rate constants on various gas mixing ratio of O2/N2 were determined from the kinetics study. These results suggested that hydroxyl radical produced in the treatment water by the chain reactions of O3 and hydroperoxy radical (HO2·) plays an important role of the decomposition of molecules in water.

  9. Gas/particle partitioning of n-alkanes, PAHs and oxygenated PAHs in urban Denver

    NASA Astrophysics Data System (ADS)

    Xie, Mingjie; Hannigan, Michael P.; Barsanti, Kelley C.

    2014-10-01

    In this study, a medium volume sampler equipped with quartz fiber filters (QFFs) and a polyurethane foam (PUF)/XAD-4/PUF sandwich (PXP) was used to collect semi-volatile organic compounds (SVOCs) in both gaseous and particle (PM2.5) phases. A backup QFF (bQFF) was used to evaluate possible sampling artifact of particulate organics due to vapor-phase adsorption. A series of n-alkanes (molecular weight: 170-562) and PAHs (128-300), and two oxy-PAHs (acenaphthenone, 168; fluorenone, 180) were measured. Breakthrough experiments demonstrated that the PXP could collect all gas-phase target compounds with high efficiency, even the low molecular weight (MW) species (e.g., naphthalene). Comparing species concentrations across different sampling matrices encountered at the Denver, Colorado field site, the light n-alkanes (MW < 282) and PAHs (MW < 192) were mostly distributed into the gas phase; while those heavy n-alkanes (MW > 324) and PAHs (MW > 202) were primarily in the particle phase (Average temperature, 12.5 ± 10.1 °C). Log values of measured gas/particle (G/P) partitioning coefficients (Kmp,OM) of selected SVOCs (docosane, tricosane, fluoranthene, pyrene, acenaphthenone and fluorenone) were linearly regressed to those of theoretically-based partitioning coefficients (Ktp,OM) for comparison. Prior to Kmp,OM calculation, the gas- and particle-phase concentrations of SVOCs were corrected following two different approaches based on bQFF measurements. The first approach assumed that the bQFF associated SVOCs were from the adsorption of gaseous SVOCs (positive artifact); the second approach assumed equal contributions from positive and negative (organics evaporated from top QFF and adsorbed by bQFF) artifacts. Under both corrections, significant correlations (p < 0.05) were observed between log Kmp,OM and log Ktp,OM for the six selected SVOCs, suggesting that the predicted G/P partitioning can reasonably capture the measured G/P partitioning behavior. The large

  10. Enhanced gas sensing performance of Li-doped ZnO nanoparticle film by the synergistic effect of oxygen interstitials and oxygen vacancies

    NASA Astrophysics Data System (ADS)

    Zhao, Jianwei; Xie, Changsheng; Yang, Li; Zhang, Shunping; Zhang, Guozhu; Cai, Ziming

    2015-03-01

    Li doped ZnO (Zn1-xLixO) nanoparticles with different content were synthesized. X-ray photoelectron spectroscopy (XPS) indicated that the ratio of oxygen to zinc for ZnO increased with increasing of Li content from x = 0 to 0.2, which had been attributed to the introduction of oxygen interstitial by Li dopant. The sensing performance and the temperature-dependent conductivity were investigated. It is observed that Li doped ZnO showed higher sensitivity and selectivity compared to the undoped ZnO. The 0.1 Li doped ZnO performed the maximum responses of 71.5 and 40.2 for 100 ppm methanol and formaldehyde, respectively, at 350 °C. The research showed that the oxygen vacancies served as active sites which supported the oxygen adsorption and reaction, oxygen interstitials served as active sites to oxidize the reducing gases and produce electrons. The enhanced sensing performance of Li doped ZnO was attributed to the synergistic effect of oxygen interstitials and oxygen vacancies.

  11. Rhenium/Oxygen Interactions at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan; Myers, Dwight; Zhu, Dong-Ming; Humphrey, Donald

    2000-01-01

    The oxidation of pure rhenium is examined from 600-1400 C in oxygen/argon mixtures. Linear weight loss kinetics are observed. Gas pressures, flow rates, and temperatures are methodically varied to determine the rate controlling steps. The reaction at 600 and 800 C appears to be controlled by a chemical reaction step at the surface; whereas the higher temperature reactions appear to be controlled by gas phase diffusion of oxygen to the rhenium surface. Attack of the rhenium appears to be along grain boundaries and crystallographic planes.

  12. Loss of Basal Cells Precedes Bronchiolitis Obliterans–Like Pathological Changes in a Murine Model of Chlorine Gas Inhalation

    PubMed Central

    O’Koren, Emily G.; Hogan, Brigid L. M.

    2013-01-01

    Bronchiolitis obliterans (BO) is a major cause of chronic airway dysfunction after toxic chemical inhalation. The pathophysiology of BO is not well understood, but epithelial cell injury has been closely associated with the development of fibrotic lesions in human studies and in animal models of both toxin-induced and transplant-induced BO. However, whereas almost all cases and models of BO include epithelial injury, not all instances of epithelial injury result in BO, suggesting that epithelial damage per se is not the critical event leading to the development of BO. Here, we describe a model of chlorine-induced BO in which mice develop tracheal and large airway obliterative lesions within 10 days of exposure to high (350 parts per million [ppm]), but not low (200 ppm), concentrations of chlorine gas. Importantly, these lesions arise only under conditions and in areas in which basal cells, the resident progenitor cells for large airway epithelium, are eliminated by chlorine exposure. In areas of basal cell loss, epithelial regeneration does not occur, resulting in persistent regions of epithelial denudation. Obliterative airway lesions arise specifically from regions of epithelial denudation in a process that includes inflammatory cell infiltration by Day 2 after exposure, fibroblast infiltration and collagen deposition by Day 5, and the ingrowth of blood vessels by Day 7, ultimately leading to lethal airway obstruction by Days 9–12. We conclude that the loss of epithelial progenitor cells constitutes a critical factor leading to the development of obliterative airway lesions after chemical inhalation. PMID:23742075

  13. Role of biochar amendment in mitigation of nitrogen loss and greenhouse gas emission during sewage sludge composting.

    PubMed

    Awasthi, Mukesh Kumar; Wang, Quan; Ren, Xiuna; Zhao, Junchao; Huang, Hui; Awasthi, Sanjeev Kumar; Lahori, Altaf Hussain; Li, Ronghua; Zhou, Lina; Zhang, Zengqiang

    2016-11-01

    The objective of the present study was to mitigate the greenhouse gas (GHG) emissions during composting of dewatered fresh sewage sludge (DFSS) employing biochar combined with zeolite (B+Z) and low dosage of lime (B+L). The 12% biochar was mixed at a 10%, 15% and 30% of zeolite and 1% lime, while without any additives was used as control. The results indicated that the combine use of B+Z was significantly increased the enzymatic activities and reduced the ammonia loss 58.03-65.17% as compare to B+L amended treatment, while CH4 92.85-95.34% and N2O 95.14-97.28% decreased than control. The B+L1% amendment significantly increased the organic matter degradation but the reduction was lower than B+Z and that could reduce the CH4 and N2O emission by 55.17-63.08% and 62.24-65.53% as compare to control, respectively. Overall our results demonstrated that 12%B+Z10% addition into DFSS can be potentially used to improve the DFSS composting by mitigation of GHG emission and nitrogen loss. PMID:27497088

  14. Loss of basal cells precedes bronchiolitis obliterans-like pathological changes in a murine model of chlorine gas inhalation.

    PubMed

    O'Koren, Emily G; Hogan, Brigid L M; Gunn, Michael Dee

    2013-11-01

    Bronchiolitis obliterans (BO) is a major cause of chronic airway dysfunction after toxic chemical inhalation. The pathophysiology of BO is not well understood, but epithelial cell injury has been closely associated with the development of fibrotic lesions in human studies and in animal models of both toxin-induced and transplant-induced BO. However, whereas almost all cases and models of BO include epithelial injury, not all instances of epithelial injury result in BO, suggesting that epithelial damage per se is not the critical event leading to the development of BO. Here, we describe a model of chlorine-induced BO in which mice develop tracheal and large airway obliterative lesions within 10 days of exposure to high (350 parts per million [ppm]), but not low (200 ppm), concentrations of chlorine gas. Importantly, these lesions arise only under conditions and in areas in which basal cells, the resident progenitor cells for large airway epithelium, are eliminated by chlorine exposure. In areas of basal cell loss, epithelial regeneration does not occur, resulting in persistent regions of epithelial denudation. Obliterative airway lesions arise specifically from regions of epithelial denudation in a process that includes inflammatory cell infiltration by Day 2 after exposure, fibroblast infiltration and collagen deposition by Day 5, and the ingrowth of blood vessels by Day 7, ultimately leading to lethal airway obstruction by Days 9-12. We conclude that the loss of epithelial progenitor cells constitutes a critical factor leading to the development of obliterative airway lesions after chemical inhalation. PMID:23742075

  15. Advanced Natural Gas Reciprocating Engine: Parasitic Loss Control through Surface Modification

    SciTech Connect

    Farshid Sadeghi; Chin-Pei Wang

    2008-12-31

    This report presents results of our investigation on parasitic loss control through surface modification in reciprocating engine. In order to achieve the objectives several experimental and corresponding analytical models were designed and developed to corroborate our results. Four different test rigs were designed and developed to simulate the contact between the piston ring and cylinder liner (PRCL) contact. The Reciprocating Piston Test Rig (RPTR) is a novel suspended liner test apparatus which can be used to accurately measure the friction force and side load at the piston-cylinder interface. A mixed lubrication model for the complete ring-pack and piston skirt was developed to correlate with the experimental measurements. Comparisons between the experimental and analytical results showed good agreement. The results revealed that in the reciprocating engines higher friction occur near TDC and BDC of the stroke due to the extremely low piston speed resulting in boundary lubrication. A Small Engine Dynamometer Test Rig was also designed and developed to enable testing of cylinder liner under motored and fired conditions. Results of this study provide a baseline from which to measure the effect of surface modifications. The Pin on Disk Test Rig (POD) was used in a flat-on-flat configuration to study the friction effect of CNC machining circular pockets and laser micro-dimples. The results show that large and shallow circular pockets resulted in significant friction reduction. Deep circular pockets did not provide much load support. The Reciprocating Liner Test Rig (RLTR) was designed to simplifying the contact at the PRCL interface. Accurate measurement of friction was obtained using 3-axis piezoelectric force transducer. Two fiber optic sensors were used to measure the film thickness precisely. The results show that the friction force is reduced through the use of modified surfaces. The Shear Driven Test Rig (SDTR) was designed to simulate the mechanism of the

  16. Continuous measurements of atmospheric oxygen and carbon dioxide on a North Sea gas platform

    NASA Astrophysics Data System (ADS)

    Luijkx, I. T.; Neubert, R. E. M.; van der Laan, S.; Meijer, H. A. J.

    2009-07-01

    A new atmospheric measurement station has been established on the North Sea oil and gas production platform F3, 200 km north off the Dutch coast (54°51' N, 4°44' E). Atmospheric mixing ratios of O2 and CO2 are continuously measured using fuel cell technology and compact infrared absorption instruments, respectively. Furthermore, the station includes an automated air flask sampler for laboratory analysis of the atmospheric mixing ratios of CO2, CH4, CO and O2 and isotope measurements of δ13C, δ18O and Δ14C from CO2. This station is - to our knowledge - the first fixed sea based station with on-site continuous O2 and CO2 measurements and therefore yields valuable additional information about the CO2 uptake in coastal marine regions, specifically the North Sea. This paper presents the measurement station and the used methodologies in detail. Additionally, the first data is presented showing the seasonal cycle as expected during August 2008 through June 2009. In comparison to land-based stations, the data show low day-to-day variability, as they are practically free of nightly inversions. Therefore, the data set collected at this measurement station serves directly as background data for the coastal northwest European region. Additionally, some short-term O2 and CO2 signals are presented, including very large (over 200 per meg) and fast negative atmospheric O2 excursions.

  17. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 2.3: Sulfur Primer

    SciTech Connect

    Nexant Inc.

    2006-05-01

    This deliverable is Subtask 2.3 of Task 2, Gas Cleanup Design and Cost Estimates, of NREL Award ACO-5-44027, ''Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment''. Subtask 2.3 builds upon the sulfur removal information first presented in Subtask 2.1, Gas Cleanup Technologies for Biomass Gasification by adding additional information on the commercial applications, manufacturers, environmental footprint, and technical specifications for sulfur removal technologies. The data was obtained from Nexant's experience, input from GTI and other vendors, past and current facility data, and existing literature.

  18. Spatiotemporal dynamics of phosphorus release, oxygen consumption and greenhouse gas emissions after localised soil amendment with organic fertilisers.

    PubMed

    Christel, Wibke; Zhu, Kun; Hoefer, Christoph; Kreuzeder, Andreas; Santner, Jakob; Bruun, Sander; Magid, Jakob; Jensen, Lars Stoumann

    2016-06-01

    Organic fertilisation inevitably leads to heterogeneous distribution of organic matter and nutrients in soil, i.e. due to uneven surface spreading or inhomogeneous incorporation. The resulting localised hotspots of nutrient application will induce various biotic and abiotic nutrient turnover processes and fixation in the residue sphere, giving rise to distinct differences in nutrient availability, soil oxygen content and greenhouse gas (GHG) production. In this study we investigated the spatiotemporal dynamics of the reaction of manure solids and manure solids char with soil, focusing on their phosphorus (P) availability, as current emphasis on improving societal P efficiency through recycling waste or bio-based fertilisers necessitates a sound understanding of their behaviour. Soil layers amended at a constant P application rate with either pig manure solids or char made from pig manure solids were incubated for three weeks between layers of non-amended, P-depleted soil. Spatial and temporal changes in and around the amendment layers were simultaneously investigated in this study using a sandwich sensor consisting of a planar oxygen optode and multi-element diffusive gradients in thin films (DGT) gels, combined with GHG emission measurements. After three weeks of incubation, the soil containing a layer amended with manure solids had a lower overall O2 content and had emitted significantly more CO2 than the non-amended control or the char-amended soil. The P availability from manure solids was initially higher than that from the char, but decreased over time, whereas from the char-amended layer P availability increased in the same period. In both treatments, increases in P availability were confined to the amended soil layer and did not greatly affect P availability in the directly adjacent soil layers during the three-week incubation. These results highlight the importance of placing organic P fertilisers close to where the plant roots will grow in order to

  19. Oxygen isotope heterogeneities in the earliest protosolar gas recorded in a meteoritic calcium aluminum-rich inclusion

    NASA Astrophysics Data System (ADS)

    Aléon, Jérôme; El Goresy, Ahmed; Zinner, Ernst

    2007-11-01

    Combined petrologic, oxygen and magnesium isotopic and trace element analyses of a compound calcium-aluminum-rich inclusion (CAI) from the Efremovka reduced CV3 carbonaceous chondrite reveal that it consists of a Mg-rich, 16O-rich xenolithic CAI, previously altered in the nebula, that impacted an extensively molten, 16O-depleted, type A host CAI shortly before the end of the host's crystallization. Convoluted regions in the xenolith were probably formed by rapid crystallization of the partial melt produced during impact. Oxygen isotopic ratios in the host CAI are correlated both with melilite chemistry and location in the inclusion. The region immediately inside the Wark-Lovering rim of the CAI consists of 16O-rich gehlenite with Δ 17O ranging down to - 20‰ but melilite becomes progressively 16O-poor (Δ 17O ˜ 0‰) and Mg-rich towards the interior. In the absence of Mg isotopic fractionation, this variation is best attributed to O isotopic exchange between the nebular gas and the partially molten inclusion during its crystallization. This event lasted less than 200 h, which implies that the host CAI was transported between two nebular reservoirs with distinct O isotopic compositions during this time. Examination of possible transport mechanisms suggests that the transport occurred over a distance of less than 1 astronomical unit. The close-to-canonical 26Al/ 27Al ratio of 4.1 × 10 - 5 determined from both inclusions implies that at most 670,000 yr after the birth of the Solar System, the 16O-rich reservoir was spatially limited and an 16O-poor reservoir with typical planetary isotopic composition was available for planet formation.

  20. Multiscale Computational Analysis of Nitrogen and Oxygen Gas-Phase Thermochemistry in Hypersonic Flows

    NASA Astrophysics Data System (ADS)

    Bender, Jason D.

    Understanding hypersonic aerodynamics is important for the design of next-generation aerospace vehicles for space exploration, national security, and other applications. Ground-level experimental studies of hypersonic flows are difficult and expensive; thus, computational science plays a crucial role in this field. Computational fluid dynamics (CFD) simulations of extremely high-speed flows require models of chemical and thermal nonequilibrium processes, such as dissociation of diatomic molecules and vibrational energy relaxation. Current models are outdated and inadequate for advanced applications. We describe a multiscale computational study of gas-phase thermochemical processes in hypersonic flows, starting at the atomic scale and building systematically up to the continuum scale. The project was part of a larger effort centered on collaborations between aerospace scientists and computational chemists. We discuss the construction of potential energy surfaces for the N4, N2O2, and O4 systems, focusing especially on the multi-dimensional fitting problem. A new local fitting method named L-IMLS-G2 is presented and compared with a global fitting method. Then, we describe the theory of the quasiclassical trajectory (QCT) approach for modeling molecular collisions. We explain how we implemented the approach in a new parallel code for high-performance computing platforms. Results from billions of QCT simulations of high-energy N2 + N2, N2 + N, and N2 + O2 collisions are reported and analyzed. Reaction rate constants are calculated and sets of reactive trajectories are characterized at both thermal equilibrium and nonequilibrium conditions. The data shed light on fundamental mechanisms of dissociation and exchange reactions -- and their coupling to internal energy transfer processes -- in thermal environments typical of hypersonic flows. We discuss how the outcomes of this investigation and other related studies lay a rigorous foundation for new macroscopic models for

  1. Continuous measurements of atmospheric oxygen and carbon dioxide on a North Sea gas platform

    NASA Astrophysics Data System (ADS)

    van der Laan-Luijkx, I. T.; Neubert, R. E. M.; van der Laan, S.; Meijer, H. A. J.

    2010-01-01

    A new atmospheric measurement station has been established on the North Sea oil and gas production platform F3, 200 km north off the Dutch coast (5°51' N, 4°44' E). Atmospheric concentrations of O2 and CO2 are continuously measured using fuel cell technology and compact infrared absorption instruments, respectively. Furthermore, the station includes an automated air flask sampler for laboratory analysis of the atmospheric concentrations of CO2, CH4, CO and O2 and isotope measurements of δ13C, δ18O and Δ14C from CO2. This station is the first fixed sea based station with on-site continuous O2 and CO2 measurements and therefore yields valuable information about the CO2 uptake in coastal marine regions, specifically the North Sea. This paper presents the measurement station and the used methodologies in detail. In comparison to land-based stations, the data show low day-to-day variability, as they are practically free of nightly inversions as well as human influences, due to the station's remoteness. Therefore, the data set collected at this measurement station serves directly as background data for the coastal northwest European region. Additionally, the first data are presented showing the seasonal cycle as expected during August 2008 through June 2009. Furthermore, some short-term O2 and CO2 signals are presented. The observations at the platform include several large and fast changing negative atmospheric O2 excursions without an accompanying change in the CO2 signal, which most likely indicate marine O2 uptake.

  2. Home Oxygen Therapy

    MedlinePlus

    ... important advantage of liquid oxygen is you can transfer some of the liquid oxygen into a smaller, ... from gas stoves, candles, lighted fireplaces, or other heat sources. Don't use any flammable products like ...

  3. Microbial sulfate reduction rates and sulfur and oxygen isotope fractionations at oil and gas seeps in deepwater Gulf of Mexico

    SciTech Connect

    Aharon, P.; Fu, B.

    2000-01-01

    sulfate reduction and anaerobic methane oxidation are the dominant microbial processes occurring in hydrate-bearing sediments at bathyal depths in the Gulf of Mexico where crude oil and methane are advecting through fault conduits to the seafloor. The oil and gas seeps are typically overlain by chemosynthetic communities consisting of thiotrophic bacterial mats (Beggiatoa spp.) and methanotrophic mussels (Bathymodiolus spp.), respectively. Cores were recovered with a manned submersible from fine-grained sediments containing dispersed gas hydrates at the threshold of stability. Estimated sulfate reduction rates are variable but generally are substantially higher in crude oil seeps (up to 50 times) and methane seeps (up to 600 times) relative to a non-seep reference sediment. Sulfur and oxygen isotope fractionation factors are highest in the reference sediment but substantially lower in the seep sediments and are controlled primarily by kinetic factors related to sulfate reduction rates. Kinetic effects also control the {delta}{sup 34}S/{delta}{sup 18}O ratios such that slow microbial rates yield low ratios whereas faster rates yield progressively higher ratios. The seep data contradict previous claims that {delta}{sup 34}S/{delta}{sup 18}O ratios are diagnostic of either microbial sulfate reduction at a fixed {delta}{sup 34}S/{delta}{sup 18}O ratio of 4/1 or lower ratios caused by SO{sub 4}-H{sub 2}O equilibration at ambient temperatures. The new results offer a better understanding of methane removal via anaerobic oxidation in the sulfate reduction zone of hydrate-bearing sediments and have significant implications regarding the origin and geochemical history of sedimentary sulfate reconstructed on the basis of {delta}{sup 34}S and {delta}{sup 18}O compositions.

  4. Carbogen gas-challenge blood oxygen level-dependent magnetic resonance imaging in hepatocellular carcinoma: Initial results

    PubMed Central

    ZHANG, LONG JIANG; ZHANG, ZHUOLI; XU, JIAN; JIN, NING; LUO, SONG; LARSON, ANDREW C.; LU, GUANG MING

    2015-01-01

    The present study aimed to evaluate the feasibility of performing carbogen gas-challenge blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) measurements in patients with hepatocellular carcinoma (HCC). A total of 25 patients with HCC underwent T2* mapping derived from multi-echo gradient-recalled echo imaging prior to and following breathing carbogen (95% O2 and 5% CO2) for 10 min. Follow-up T2* mapping was performed in 5 patients 1 day after transarterial chemoembolization (TACE). T2*, R2* and ∆R2* values (R2*air - R2*carb) of the whole tumor, the solid region of the tumor and the adjacent liver parenchyma were measured and compared in the patients with HCC. The T2* value of the solid region of the tumor following carbogen breathing was higher than the value following room air breathing (P<0.05), and the R2* value of room air breathing was higher than that following carbogen breathing (P<0.05). ∆R2* values of the tumor and the adjacent liver parenchyma prior to and following carbogen breathing were 2.4±7.8, 8.1±14.7 and 2.0±11.0 sec−1, respectively. R2* values were significantly decreased in 2 cases 1 day after TACE (17.8 vs. −3.4 sec−1 and 10.2 vs. 2.4 sec−1). Overall, carbogen gas-challenge BOLD MRI measurements are feasible in clinical settings and may serve as a novel functional biomarker for monitoring the treatment efficacy of embolic therapies for HCC. PMID:26622788

  5. Effects of carbon on oxygen reduction and evolution reactions of gas-diffusion air electrodes based on perovskite-type oxides

    NASA Astrophysics Data System (ADS)

    Nishio, Koji; Molla, Sergio; Okugaki, Tomohiko; Nakanishi, Shinji; Nitta, Iwao; Kotani, Yukinari

    2015-12-01

    Electrochemical properties of three perovskite oxides with different B-site elements, LaMnO3, La0.6Sr0.4FeO3 and LaNiO3, are examined with and without carbon using gas-diffusion electrodes, in comparison with our previous results on La0.5Sr0.5CoO3. Cyclic voltammetry studies reveal very low oxygen reduction current density of carbon-free perovskite oxides, indicating their poor catalytic activity on oxygen reduction reactions. By mixing carbon with perovskite oxides, the oxygen reduction current density is increased by about two orders. The results are consistent with the peroxide pathway mechanism in which the perovskite oxide is highly active on either electrochemical reduction or chemical decomposition. Electrochemical properties of a three-layered gas diffusion electrode demonstrate the peroxide pathway mechanism works even the perovskite oxide and the carbon exist in separate layers. Oxygen evolution reactions are prominently dependent on the oxide species and also on an addition of carbon. The electrode based on carbon-free LaNiO3 or La0.5Sr0.5CoO3 show moderate oxygen evolution activity, and the activity is further enhanced by an addition of carbon, while LaMnO3 and La0.6Sr0.4FeO3 show poor activity even with an addition of carbon.

  6. Determining the optimal transmembrane gas pressure for nitrification in membrane-aerated biofilm reactors based on oxygen profile analysis.

    PubMed

    Wang, Rongchang; Xiao, Fan; Wang, Yanan; Lewandowski, Zbigniew

    2016-09-01

    The goal of this study was to investigate the effect of transmembrane gas pressure (P g) on the specific ammonium removal rate in a membrane-aerated biofilm reactor (MABR). Our experimental results show that the specific ammonium removal rate increased from 4.98 to 9.26 gN m(-2) day(-1) when P g increased from 2 to 20 kPa in an MABR with a biofilm thickness of approximately 600 μm. However, this improvement was not linear; there was a threshold of P g separating the stronger and weaker effects of P g. The ammonium removal rate was improved less significantly when P g was over the threshold, indicating that there is an optimal threshold of P g for maximizing ammonium removal in an MABR. The change in oxygen penetration depth (d p) is less sensitive to P g in the ammonia-oxidizing active layer than in the inactive layer in membrane-aerated biofilm. The location of the P g threshold is at the same point as the thickness of the active layer on the curve of d p versus P g; thus, the active layer thickness and the optimal P g can be determined on the basis of the changes in the slope of d p to P g. PMID:27170321

  7. Gas turbine engine adapted for use in combination with an apparatus for separating a portion of oxygen from compressed air

    DOEpatents

    Bland, Robert J.; Horazak, Dennis A.

    2012-03-06

    A gas turbine engine is provided comprising an outer shell, a compressor assembly, at least one combustor assembly, a turbine assembly and duct structure. The outer shell includes a compressor section, a combustor section, an intermediate section and a turbine section. The intermediate section includes at least one first opening and at least one second opening. The compressor assembly is located in the compressor section to define with the compressor section a compressor apparatus to compress air. The at least one combustor assembly is coupled to the combustor section to define with the combustor section a combustor apparatus. The turbine assembly is located in the turbine section to define with the turbine section a turbine apparatus. The duct structure is coupled to the intermediate section to receive at least a portion of the compressed air from the compressor apparatus through the at least one first opening in the intermediate section, pass the compressed air to an apparatus for separating a portion of oxygen from the compressed air to produced vitiated compressed air and return the vitiated compressed air to the intermediate section via the at least one second opening in the intermediate section.

  8. Simultaneous removal of SO{sub 2} and NO from flue gas using 'oxygen-enriched' highly reactive absorbent

    SciTech Connect

    Zhao, Y.; Sun, X.J.; Fang, H.; Liu, F.

    2007-04-15

    Fly ash, industry-grade lime, and an additive, MnO{sub 2} (M), were used to prepare an 'oxygen-enriched' highly reactive absorbent. Experiments of simultaneous desulfurization and denitrification were carried in a flue gas circulating fluidized bed (CFB). The effects of influencing factors were also investigated on the removal efficiencies of desulfurization and denitrification. Removal efficiencies of 95.5% for SO{sub 2} and 64.8% for NO were obtained respectively under the optimal experimental conditions. The component of the spent absorbent was analyzed with chemical analysis methods. The results indicated that more nitrogen species appeared in the spent absorbent except sulfur species. A scanning electron microscope (SEM) and an accessory X-ray energy spectrometer (EDS) were used to observe microproperties of the samples, including fly ash, oxidizing highly reactive absorbent, and spent absorbent. The simultaneous removal mechanism of SO{sub 2} and NO based on this absorbent was proposed according to the experimental results.

  9. Oxidation Behavior and Cracking Susceptibility of Ni-Cr Alloys in Dry Steam and Inert Gas under Extremely-Low Oxygen Partial Pressure

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Kenmoku, Yasuhiro; Endo, Takayuki; Miyazaki, Takamichi; Watanabe, Yutaka

    In order to investigate oxidation behavior and cracking susceptibility of the Ni-Cr alloys under extremely-low oxygen partial pressure, three Ni-Cr alloys (Ni-14Cr, Ni-22Cr and Ni-30Cr) were used as plate specimen and reverse U-bend specimen for oxidation experiments for 750 hours at 400 °C in two kinds of gas system (inert gas and dry steam) under various oxygen potential (Ni stable, Ni/NiO equilibrium and NiO stable). The Ni-Cr alloys cracked along grain boundary both in inert gas system (with trace O2, without H2O) and in hydrogenated steam. In the inert gas system, the cracking susceptibility was confirmed in near NiO stable condition. On the other hand, no crack was found in near Ni stable condition. In the dry steam system, the cracking susceptibility was confirmed in near Ni/NiO equilibrium. In contrast, no crack was found in near NiO stable condition. The cracking susceptibility was confirmed in near Ni/NiO equilibrium in hydrogenated steam as contrasted with higher oxygen potential in inert gas system. This result shows that potential range for the cracking susceptibility seemed to be different between the two kinds of gas system. Cracking severity was highest for Ni-14Cr and lowest for Ni-30Cr both in inert gas and steam; however, even Ni-30Cr was not immune to intergranular cracking in steam near Ni/NiO equilibrium.

  10. The effect of discontinuous gas exchange on respiratory water loss in grasshoppers (Orthoptera: Acrididae) varies across an aridity gradient.

    PubMed

    Huang, Shu-Ping; Talal, Stav; Ayali, Amir; Gefen, Eran

    2015-08-01

    The significance of discontinuous gas-exchange cycles (DGC) in reducing respiratory water loss (RWL) in insects is contentious. Results from single-species studies are equivocal in their support of the classic 'hygric hypothesis' for the evolution of DGC, whereas comparative analyses generally support a link between DGC and water balance. In this study, we investigated DGC prevalence and characteristics and RWL in three grasshopper species (Acrididae, subfamily Pamphaginae) across an aridity gradient in Israel. In order to determine whether DGC contributes to a reduction in RWL, we compared the DGC characteristics and RWL associated with CO2 release (transpiration ratio, i.e. the molar ratio of RWL to CO2 emission rates) among these species. Transpiration ratios of DGC and continuous breathers were also compared intraspecifically. Our data show that DGC characteristics, DGC prevalence and the transpiration ratios correlate well with habitat aridity. The xeric-adapted Tmethis pulchripennis exhibited a significantly shorter burst period and lower transpiration ratio compared with the other two mesic species, Ocneropsis bethlemita and Ocneropsis lividipes. However, DGC resulted in significant water savings compared with continuous exchange in T. pulchripennis only. These unique DGC characteristics for T. pulchripennis were correlated with its significantly higher mass-specific tracheal volume. Our data suggest that the origin of DGC may not be adaptive, but rather that evolved modulation of cycle characteristics confers a fitness advantage under stressful conditions. This modulation may result from morphological and/or physiological modifications. PMID:26290590

  11. A regional assessment of the cost and effectiveness of mitigation measures for reducing nutrient losses to water and greenhouse gas emissions to air from pastoral farms.

    PubMed

    Vibart, Ronaldo; Vogeler, Iris; Dennis, Samuel; Kaye-Blake, William; Monaghan, Ross; Burggraaf, Vicki; Beautrais, Josef; Mackay, Alec

    2015-06-01

    Using a novel approach that links geospatial land resource information with individual farm-scale simulation, we conducted a regional assessment of nitrogen (N) and phosphorous (P) losses to water and greenhouse gas (GHG) emissions to air from the predominant mix of pastoral industries in Southland, New Zealand. An evaluation of the cost-effectiveness of several nutrient loss mitigation strategies applied at the farm-scale, set primarily for reducing N and P losses and grouped by capital cost and potential ease of adoption, followed an initial baseline assessment. Grouped nutrient loss mitigation strategies were applied on an additive basis on the assumption of full adoption, and were broadly identified as 'improved nutrient management' (M1), 'improved animal productivity' (M2), and 'restricted grazing' (M3). Estimated annual nitrate-N leaching losses occurring under representative baseline sheep and beef (cattle) farms, and representative baseline dairy farms for the region were 10 ± 2 and 32 ± 6 kg N/ha (mean ± standard deviation), respectively. Both sheep and beef and dairy farms were responsive to N leaching loss mitigation strategies in M1, at a low cost per kg N-loss mitigated. Only dairy farms were responsive to N leaching loss abatement from adopting M2, at no additional cost per kg N-loss mitigated. Dairy farms were also responsive to N leaching loss abatement from adopting M3, but this reduction came at a greater cost per kg N-loss mitigated. Only dairy farms were responsive to P-loss mitigation strategies, in particular by adopting M1. Only dairy farms were responsive to GHG abatement; greater abatement was achieved by the most intensified dairy farm system simulated. Overall, M1 provided for high levels of regional scale N- and P-loss abatement at a low cost per farm without affecting overall farm production, M2 provided additional N-loss abatement but only marginal P-loss abatement, whereas M3 provided the greatest N-loss abatement, but

  12. Effect of depletion layer width on electrical properties of semiconductive thin film gas sensor: a numerical study based on the gradient-distributed oxygen vacancy model

    NASA Astrophysics Data System (ADS)

    Liu, Jianqiao; Lu, Yiting; Cui, Xiao; Jin, Guohua; Zhai, Zhaoxia

    2016-03-01

    The effects of depletion layer width on the semiconductor gas sensors were investigated based on the gradient-distributed oxygen vacancy model, which provided numerical descriptions for the sensor properties. The potential barrier height, sensor resistance, and response to target gases were simulated to reveal their dependences on the depletion layer width. According to the simulation, it was possible to improve the sensor response by enlarging the width of depletion layer without changing the resistance of the gas sensor under the special circumstance. The different performances between resistance and response could provide a bright expectation that the design and fabrication of gas sensing devices could be economized. The simulation results were validated by the experimental performances of SnO2 thin film gas sensors, which were prepared by the sol-gel technique. The dependences of sensor properties on depletion layer width were observed to be in agreement with the simulations.

  13. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 9: Mixed Alcohols From Syngas -- State of Technology

    SciTech Connect

    Nexant Inc.

    2006-05-01

    This deliverable is for Task 9, Mixed Alcohols from Syngas: State of Technology, as part of National Renewable Energy Laboratory (NREL) Award ACO-5-44027, ''Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment''. Task 9 supplements the work previously done by NREL in the mixed alcohols section of the 2003 technical report Preliminary Screening--Technical and Economic Assessment of Synthesis Gas to Fuels and Chemicals with Emphasis on the Potential for Biomass-Derived Syngas.

  14. Hourly Measurement of the Concentration and Gas-Particle Partitioning of Oxygenated Organic Tracers in Ambient Aerosol: First Results from Berkeley, CA and Rural Alabama

    NASA Astrophysics Data System (ADS)

    Isaacman, G. A.; Kreisberg, N. M.; Yee, L.; Chan, A.; Worton, D. R.; Hering, S. V.; Goldstein, A. H.

    2013-12-01

    Hourly and bi-hourly time-resolved measurements of organic tracer compounds in ambient aerosols have been successfully used to elucidate sources and formation pathways of atmospheric particulate matter. Here we extend the Semi-Volatile Thermal desorption Aerosol Gas chromatograph (SVTAG), a custom in-situ instrument that collects, desorbs, and analyzes ambient aerosol and semi-volatile compounds with hourly time resolution, to include on-line derivatization and a second, parallel collection cell that provides simultaneous collection of both particle-phase and particle-plus-gas-phase organic compounds. By introducing a silylating agent upon desorption, SVTAG can measure highly oxygenated compounds that are not easily detected using traditional gas chromatography including most of the previously reported oxygenated tracers for biogenic and anthropogenic secondary organic aerosol. The use of a pair of matched collection cells with parallel sampling and serial analysis provides direct gas-particle partitioning information. One cell collects the total organic fraction of compounds with volatilities lower than a C13 hydrocarbon, while the other cell samples through an activated carbon denuder to selectively remove the gas-phase components. Taken together these provide a direct measurement of gas-particle partitioning to yield a check on classical absorption based partitioning theory while deviations from this theory provide constraints on other driving factors in aerosol formation chemistry, such as oligomerization, salt formation, and acidity. We present here the capabilities and utility of the dual cell SVTAG with derivatization, with chemical insights gained from initial tests on ambient Berkeley air and the first results from a rural site in Alabama obtained during the Southern Oxidant and Aerosol Study (SOAS). Tracers for varying isoprene oxidation pathways are used to explore the influence of anthropogenic emissions; concentrations of 2-methyltetrols and 2-methyl

  15. The effects of 2 levels of the inspired oxygen fraction on blood gas variables in propofol-anesthetized dogs with high intracranial pressure

    PubMed Central

    Dias, Luis Gustavo Gosuen Gonçalves; Nunes, Newton; Lopes, Patrícia Cristina Ferro; de Almeida, Ricardo Miyasaka; Neto, Gláucia Bueno Pereira; de Souza, Ana Letícia Groszewicz; de Almeida Belmonte, Emílio

    2009-01-01

    The influence of 2 different levels of the inspired oxygen fraction (FiO2) on blood gas variables was evaluated in dogs with high intracranial pressure (ICP) during propofol anesthesia (induction followed by a continuous rate infusion [CRI] of 0.6 mg/kg/min) and intermittent positive pressure ventilation (IPPV). Eight adult mongrel dogs were anesthetized on 2 occasions, 21 d apart, and received oxygen at an FiO2 of 1.0 (G100) or 0.6 (G60) in a randomized crossover fashion. A fiberoptic catheter was implanted on the surface of the right cerebral cortex for assessment of the ICP. An increase in the ICP was induced by temporary ligation of the jugular vein 50 min after induction of anesthesia and immediately after baseline measurement of the ICP. Blood gas measurements were taken 20 min later and then at 15-min intervals for 1 h. Numerical data were submitted to Morrison’s multivariate statistical methods. The ICP, the cerebral perfusion pressure and the mean arterial pressure did not differ significantly between FiO2 levels or measurement times after jugular ligation. The only blood gas values that differed significantly (P < 0.05) were the arterial oxygen partial pressure, which was greater with G100 than with G60 throughout the procedure, and the venous haemoglobin saturation, that was greater with G100 than with G60 at M0. There were no significant differences between FiO2 levels or measurement times in the following blood gas variables: arterial carbon dioxide partial pressure, arterial hemoglobin saturation, base deficit, bicarbonate concentration, pH, venous oxygen partial pressure, venous carbon dioxide partial pressure and the arterial-to-end-tidal carbon dioxide difference. PMID:19436579

  16. On-line and in situ monitoring of oxygen concentration and gas temperature in a reheating furnace utilizing tunable diode-laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Sandström, Lars; Malmberg, Donald

    2002-09-01

    Increased demands on energy savings and quality control in metallurgical processes have created incentives for new methods to monitor and control the process. In this paper we will present a field trial that shows the potential of tunable diode-laser spectroscopy (TDLS) for simultaneous contact free measuring and monitoring of the oxygen concentration as well as the gas temperature in a reheating furnace during production. The field trials were carried out at an oil-fueled reheating furnace during 7 weeks of production. The tunable diode-laser spectrometer was measuring in situ across the preheating zone and the soaking zone in the furnace. During the campaign the oxygen concentration and the gas temperature in the furnace environment were simultaneously monitored and instantaneous variations in these parameters could easily be recorded and subsequently correlated to actual changes in the process. Furthermore, the much shorter response-time of the TDLS technique compared with conventional measurement methods such as thermocouples and extractive gas analyzers was also demonstrated during the trials. The results show the potential for the TDLS technique to be used for energy savings as well as product quality improvements by controlling the burners in the reheating furnace. The results show that it would be possible to control and optimize the oxygen concentration with TDLS in the control loop of the reheating furnace.

  17. Kinetics of oxygen-enhanced water gas shift on bimetallic catalysts and the roles of metals and support

    NASA Astrophysics Data System (ADS)

    Kugai, Junichiro

    The post-processing of reformate is an important step in producing hydrogen (H2) with low carbon monoxide (CO) for low temperature fuel cells from syn-gas. However, the conventional process consists of three steps, i.e. two steps of water gas shift (WGS) and preferential oxidation (PROX) of CO, and it is not suitable for mobile applications due to the large volume of water gas shift (WGS) catalysts and conditioning and/or regeneration necessary for these catalysts. Aiming at replacing those three steps by a simple one-step process, small amount of oxygen was added to WGS (the reaction called oxygen-enhanced water gas shift or OWGS) to promote the reaction kinetics and low pyrophoric ceria-supported bimetallic catalysts were employed for stable performance in this reaction. Not only CO conversion, but also H2 yield was found to increase by the O2 addition on CeO2-supported catalysts. The characteristics of OWGS, high H2 production rate at 200 to 300°C at short contact time where unreacted O2 exists, evidenced the impact of O2 addition on surface species on the catalyst. Around 1.5 of reaction order in CO for various CeO2-supported metal catalysts for OWGS compared to reaction orders in CO ranging from -0.1 to 0.6 depending on metal species for WGS shows O2 addition decreases CO coverage to free up the active sites for co-reactant (H2O) adsorption and activation. Among the monometallic and bimetallic catalysts, Pt-Cu and Pd-Cu bimetallic catalysts were superior to monometallic catalysts in OWGS. These bimetallic components were found to form alloys where noble metal is surrounded mainly by Cu to have strong interaction between noble metal and copper resulting in high OWGS activity and low pyrophoric property. The metal loadings were optimized for CeO2-supported Pd-Cu bimetallic system and 2 wt% Pd with 5 -- 10 wt% Cu were found to be the optimum for the present OWGS condition. In the kinetic study, Pd in Pd-Cu was shown to increase the active sites for H2O

  18. Oxygen exchange at gas/oxide interfaces: how the apparent activation energy of the surface exchange coefficient depends on the kinetic regime.

    PubMed

    Fielitz, Peter; Borchardt, Günter

    2016-08-10

    In the dedicated literature the oxygen surface exchange coefficient KO and the equilibrium oxygen exchange rate [Fraktur R] are considered to be directly proportional to each other regardless of the experimental circumstances. Recent experimental observations, however, contradict the consequences of this assumption. Most surprising is the finding that the apparent activation energy of KO depends dramatically on the kinetic regime in which it has been determined, i.e. surface exchange controlled vs. mixed or diffusion controlled. This work demonstrates how the diffusion boundary condition at the gas/solid interface inevitably entails a correlation between the oxygen surface exchange coefficient KO and the oxygen self-diffusion coefficient DO in the bulk ("on top" of the correlation between KO and [Fraktur R] for the pure surface exchange regime). The model can thus quantitatively explain the range of apparent activation energies measured in the different regimes: in the surface exchange regime the apparent activation energy only contains the contribution of the equilibrium exchange rate, whereas in the mixed or in the diffusion controlled regime the contribution of the oxygen self-diffusivity has also to be taken into account, which may yield significantly higher apparent activation energies and simultaneously quantifies the correlation KO ∝ DO(1/2) observed for a large number of oxides in the mixed or diffusion controlled regime, respectively. PMID:27460608

  19. Improvement of activated carbons as oxygen reduction catalysts in neutral solutions by ammonia gas treatment and their performance in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Watson, Valerie J.; Nieto Delgado, Cesar; Logan, Bruce E.

    2013-11-01

    Commercially available activated carbon (AC) powders from different precursor materials (peat, coconut shell, coal, and hardwood) were treated with ammonia gas at 700 °C to improve their performance as oxygen reduction catalysts in neutral pH solutions used in microbial fuel cells (MFCs). The ammonia treated ACs exhibited better catalytic performance in rotating ring-disk electrode tests than their untreated precursors, with the bituminous based AC most improved, with an onset potential of Eonset = 0.12 V (untreated, Eonset = 0.08 V) and n = 3.9 electrons transferred in oxygen reduction (untreated, n = 3.6), and the hardwood based AC (treated, Eonset = 0.03 V, n = 3.3; untreated, Eonset = -0.04 V, n = 3.0). Ammonia treatment decreased oxygen content by 29-58%, increased nitrogen content to 1.8 atomic %, and increased the basicity of the bituminous, peat, and hardwood ACs. The treated coal based AC cathodes had higher maximum power densities in MFCs (2450 ± 40 mW m-2) than the other AC cathodes or a Pt/C cathode (2100 ± 1 mW m-2). These results show that reduced oxygen abundance and increased nitrogen functionalities on the AC surface can increase catalytic performance for oxygen reduction in neutral media.

  20. One-Step Preparation of Oxygen/Fluorine Dual Functional MWCNTs with Good Water Dispersibility by the Initiation of Fluorine Gas.

    PubMed

    Liu, Yang; Wang, Xu; Wang, Weimiao; Li, Baoyin; Wu, Peng; Ren, Mengmeng; Cheng, Zheng; Chen, Teng; Liu, Xiangyang

    2016-03-01

    It is still a challenge to prepare water-dispersible carbon nanotubes which are proved to have great potential in numerous applications. In this present work, as low as 2% fluorine gas was used as initiator to prepare oxygen/fluorine dual functional MWCNTs (OF-MWCNTs) with good water dispersibility through a one-step method under oxygen atmosphere. The aromatic structure of OF-MWCNTs is reserved to some extent resulting in better electrical conductivity than pure fluorinated MWCNTs (F-MWCNTs). The amount of oxygen atoms and fluorine atoms (hereinafter referred to as "O-content" and "F-content") of OF-MWCNTs is up to 8.8% and 7.5%. Fourier transform infrared spectroscopy (FTIR) manifests that - COOH is covalently bonded onto the surface of OF-MWCNTs. In addition, the OF-MWCNTs sample is pH-sensitive, which further validates the successful introduction of -COOH. The successful covalent attachment of -COOH onto MWCNTs dramatically improves the hydrophilia of MWCNTs which always present hydrophobic character. It is deduced that fluorine creates reactive sites for oxygen, increases the oxygen content, and eventually results in the dispersibility of OF-MWCNTs in water. The corresponding hydrophilic OF-MWCNTs film shows good performance for separating oil-in-water emulsions. Meanwhile, the good dispersibility of OF-MWCNTs in organic solvents also makes it possible to be applied in various composites. PMID:26950382

  1. The action of humidified gas on the pulmonary lining layer. Ultrastructural observations after administration of pure oxygen and of various mixtures of oxygen and carbon dioxide.

    PubMed

    Baratta, L; Baratta, B; Castellani, P; Strazzer, F

    1979-10-15

    The study concerns the action of dehumidified or humidified gas on the pulmonary lining layer. The results of our research suggest that water vapor used in artificial ventilation may be an important determining factor of the respiratory problems reported by clinicians in man. Important modifications of the lining layer of the alveolar epithelium occur, accompanied by more important alterations, including those of the content of the alveolus, all of which contribute to the pulmonary edema observed. PMID:122059

  2. Significance of the Gunflint (Precambrian) Microflora: Photosynthetic oxygen may have had important local effects before becoming a major atmospheric gas.

    PubMed

    Cloud, P E

    1965-04-01

    Several categories of biological microstructures 1.9+/- billion years old are here described, illustrated, and referred to a group of early thallophytes that includes the thread bacteria and the blue-green algae. These microstructures were almost surely autotrophic and in the line of evolution toward green-plant photosynthesis, if not themselves oxygen producers. Geochemical evidence has been interpreted by some to imply that the contemporaneous atmosphere was essentially anoxygenic (reducing), and by others to indicate an atmosphere rich in oxygen. These conflicting interpretations may be reconciled by a hypothesis, based on demonstrable fossil organisms, that calls for local centers of biologic oxygen generation. PMID:17773767

  3. Effects of dopants and oxygen vacancies on the dielectric loss tangent of (Zr{sub 0.8}Sn{sub 0.2})TiO{sub 4} dielectric ceramics

    SciTech Connect

    Higuchi, Y.

    1995-08-01

    The effects of dopants and oxygen vacancies on dielectric loss tangent of (Zr{sub 0.8}Sn{sub 0.2})TiO{sub 4} materials were investigated. In the case that the specimen was doped with 0.5wt% Ta{sub 2}O{sub 5} and then annealed in reduced atmosphere, the increase of loss tangent was enormous at frequencies lower than 100 KHz but slight at microwave frequencies. When the specimen was doped with 0.5wt% Fe{sub 2}O{sub 3}, the loss tangent increased drastically at microwave frequencies. These experimental results are well explained by the contribution of space charge polarization and lattice defects with charge deviations.

  4. Group additive values for the gas-phase standard enthalpy of formation, entropy and heat capacity of oxygenates.

    PubMed

    Paraskevas, Paschalis D; Sabbe, Maarten K; Reyniers, Marie-Françoise; Papayannakos, Nikos; Marin, Guy B

    2013-11-25

    A complete and consistent set of 60 Benson group additive values (GAVs) for oxygenate molecules and 97 GAVs for oxygenate radicals is provided, which allow to describe their standard enthalpies of formation, entropies and heat capacities. Approximately half of the GAVs for oxygenate molecules and the majority of the GAVs for oxygenate radicals have not been reported before. The values are derived from an extensive and accurate database of thermochemical data obtained by ab initio calculations at the CBS-QB3 level of theory for 202 molecules and 248 radicals. These compounds include saturated and unsaturated, α- and β-branched, mono- and bifunctional oxygenates. Internal rotations were accounted for by using one-dimensional hindered rotor corrections. The accuracy of the database was further improved by adding bond additive corrections to the CBS-QB3 standard enthalpies of formation. Furthermore, 14 corrections for non-nearest-neighbor interactions (NNI) were introduced for molecules and 12 for radicals. The validity of the constructed group additive model was established by comparing the predicted values with both ab initio calculated values and experimental data for oxygenates and oxygenate radicals. The group additive method predicts standard enthalpies of formation, entropies, and heat capacities with chemical accuracy, respectively, within 4 kJ mol(-1) and 4 J mol(-1) K(-1) for both ab initio calculated and experimental values. As an alternative, the hydrogen bond increment (HBI) method developed by Lay et al. (T. H. Lay, J. W. Bozzelli, A. M. Dean, E. R. Ritter, J. Phys. Chem.- 1995, 99, 14514) was used to introduce 77 new HBI structures and to calculate their thermodynamic parameters (Δ(f)H°, S°, C(p)°). The GAVs reported in this work can be reliably used for the prediction of thermochemical data for large oxygenate compounds, combining rapid prediction with wide-ranging application. PMID:24123572

  5. GREENHOUSE GAS EMISSIONS CONTROL BY OXYGEN FIRING IN CIRCULATING FLUID BED BOILERS (Phase II--Evaluation of the Oxyfuel CFB Concept)

    SciTech Connect

    John L. Marion; Nsakala ya Nsakala

    2003-11-09

    The overall project goal is to determine if carbon dioxide can be captured and sequestered at a cost of about $10/ton of carbon avoided, using a newly constructed Circulating Fluidized Bed combustor while burning coal with a mixture of oxygen and recycled flue gas, instead of air. This project is structured in two Phases. Phase I was performed between September 28, 2001 and May 15, 2002. Results from Phase I were documented in a Topical Report issued on May 15, 2003 (Nsakala, et al., 2003), with the recommendation to evaluate, during Phase II, the Oxyfuel-fired CFB concept. DOE NETL accepted this recommendation, and, hence approved the project continuation into Phase II. Phase 2. The second phase of the project--which includes pilot-scale tests of an oxygen-fired circulating fluidized bed test facility with performance and economic analyses--is currently underway at ALSTOM's Power Plant Laboratories, located in Windsor, CT (US). The objective of the pilot-scale testing is to generate detailed technical data needed to establish advanced CFB design requirements and performance when firing coals and delayed petroleum coke in oxygen/carbon dioxide mixtures. Results will be used in the design of oxygen-fired CFB boilers--both retrofit and new Greenfield--as well as to provide a generic performance database for other researchers. At the conclusion of Phase 2, revised costs and performance will be estimated for both retrofit and new Greenfield design concepts with CO2 capture, purification, compression, and liquefaction.

  6. Hourly oxygen and total gas tension measurements at the Southern Ocean Time Series site reveal winter ventilation and spring net community production

    NASA Astrophysics Data System (ADS)

    Weeding, Ben; Trull, Thomas W.

    2014-01-01

    Using a moored instrument package at 35 m depth at the Southern Ocean Time Series (SOTS) site near 46°56'S 142°15'E from September 2010 to April 2011 (219 days), we obtained the first Southern Ocean Time Series of dissolved oxygen (from an optode sensor) and nitrogen (from a total gas tension sensor). Nitrogen was consistently supersaturated (100.8%-102.9%), while oxygen was highly subsaturated in early spring (as low as 93.5%) and reached supersaturation (maximum 104.9%) during only 37 days in early summer. The low oxygen levels in spring illustrate the importance of deep mixing in the Subantarctic Zone in ventilating the upper limb of the global overturning circulation. Using nitrogen as a proxy for physical processes, we isolated biological contributions to the oxygen time series to obtain net community production (NCP). Almost all NCP occurred in spring in the presence of deep mixed layers, with only small additional contributions in summer after water column stratification. The temperature and salinity time series also revealed distinct parcels of water. Rapid changes at their interfaces generated unrealistic NCP events in the standard calculation model, which were removed, while still retaining NCP contributions from each parcel. NCP totaled 2.2 ± 1.2 mol O2 m-2 over the deployment, within the range of previous estimates from low temporal resolution techniques. Examination of errors revealed particular sensitivity to entrainment, suggesting more rigorous understanding of this process is required, e.g., via profiling instruments.

  7. Production of reactive oxygen species by withaferin A causes loss of type collagen expression and COX-2 expression through the PI3K/Akt, p38, and JNK pathways in rabbit articular chondrocytes.

    PubMed

    Yu, Seon-Mi; Kim, Song-Ja

    2013-11-01

    Withaferin A (WFA) is a major chemical constituent of Withania somnifera, also known as Indian ginseng. Many recent reports have provided evidence of its anti-tumor, anti-inflammation, anti-oxidant, and immune modulatory activities. Although the compound appears to have a large number of effects, its defined mechanisms of action have not yet been determined. We investigated the effects of WFA on loss of type collagen expression and inflammation in rabbit articular chondrocytes. WFA increased the production of reactive oxygen species, suggesting the induction of oxidative stress, in a dose-dependent manner. Also, we confirmed that WFA causes loss of type collagen expression and inflammation as determined by a decrease of type II collagen expression and an increase of cyclooxygenase-2 (COX-2) expression via western blot analysis in a dose- and time- dependent manner. WFA also reduced the synthesis of sulfated proteoglycan via Alcian blue staining and caused the synthesis of prostaglandin E2 (PGE2) via assay kit in dose- and time-dependent manners. Treatment with N-acetyl-L-cysteine (NAC), an antioxidant, inhibited WFA-induced loss of type II collagen expression and increase in COX-2 expression, accompanied by inhibition of reactive oxygen species production. WFA increased phosphorylation of both Akt and p38. Inhibition of PI3K/Akt, p38, and JNK with LY294002 (LY), SB203580 (SB), or SP600125 (SP) in WFA-treated cells rescued the expression of type II collagen and suppressed the expression of COX-2. These results demonstrate that WFA induces loss of type collagen expression and inflammation via PI3K/Akt, p38, and JNK by generating reactive oxygen species in rabbit articular chondrocytes. PMID:24016823

  8. Simulation of the grain size effect in gas-sensitive SnO2 thin films using the oxygen vacancy gradient distribution model

    NASA Astrophysics Data System (ADS)

    Liu, Jianqiao; Zhai, Zhaoxia; Jin, Guohua; Li, Yuan; Monica, Faheema Fairuj; Liu, Xuesong

    2015-01-01

    The model of gradient-distributed oxygen vacancies is utilized in simulating the grain size effects of gas-sensitive SnO2 thin films. The distribution profile of oxygen vacancies has a grain size effect and the profile gradient correlates positively with the radius of the grains. The simulation results show that the grain size is a fundamental factor dominating the gas-sensing properties of thin films. The potential barrier height and resistivity have significant grain size effects when m is between 0.1 and 0.5 nm-1. The size effects on sensor response to stimulant gases can be enhanced by increasing the value of m or the absolute value of a. Two expressions are used to simulate the grain size effect of the sensor response. The expressions act similarly when a < 0.2. The simplified response provides a neat function to quantitatively explain the sensor performance on gases with low partial pressure. Although the accurate response is complicated, it is applicable to the entire concentration range. A small power-law exponent n is calculated from the accurate response expression when a high gas concentration is employed, illustrating a "saturation effect" of the response.

  9. An extended dynamical model of a geyser induced by inflow of gas (3) : effects of various friction loss in an underground watercourse

    NASA Astrophysics Data System (ADS)

    Kagami, H.

    2009-04-01

    We have proposed a mathematical model (a static model), a dynamical model and a modified dynamical model of a geyser induced by inflow of gas (a periodic bubbling spring) based on observation of Hirogawara Geyser (Yamagata, Japan)and model experiments of the geyser and have also proposed a combined model combining above 2 models. And numerical simulations of the modified dynamical model or the combined model reappear dynamics of spouting of geysers induced by inflow of gas and it becomes possible that parameters (volume of the underground space, depth of spouting hole and so on) under a geyser are estimated due to comparison between results of simulation and those of observation. Moreover we have verified above models through geological exploration, analysis of hot spring water and radioactive prospecting. Then we added evaporation effect of gas dissolved in hot spring water to the combined model. Then we expanded the combined model through adding effects of a complicated underground watercourse, that is, effects of watercourses' sudden expansion, sudden contraction, repeat of them and elbow shape to the combined model. As a result, though we could see change of spouting's amplitude, period and so on dependent on degrees of above effects, we could also see that these effects were much smaller than those of other parameters, that is, volume of the underground space, depth of spouting hole and so on. But in the case of such a long watercourse as a geyser's underground watercourse, an effect of friction loss between walls of the watercourse and hot spring water flowing along it is largest among the other effects concerning head loss. Therefore we have to consider above effect of friction loss when we discuss spouting dynamics of a geyser. In this study, we expand further above expanded model through adding effects of friction loss between walls of the watercourse and hot spring water during spouting to the combined model and estimate effects of it on spouting dynamics

  10. Windage Power Loss in Gas Foil Bearings and the Rotor-Stator Clearance of High Speed Generators Operating in High Pressure Environments

    NASA Technical Reports Server (NTRS)

    Bruckner, Robert J.

    2009-01-01

    Closed Brayton Cycle (CBC) and Closed Supercritical Cycle (CSC) engines are prime candidates to convert heat from a reactor into electric power for robotic space exploration and habitation. These engine concepts incorporate a permanent magnet starter/generator mounted on the engine shaft along with the requisite turbomachinery. Successful completion of the long-duration missions currently anticipated for these engines will require designs that adequately address all losses within the machine. The preliminary thermal management concept for these engine types is to use the cycle working fluid to provide the required cooling. In addition to providing cooling, the working fluid will also serve as the bearing lubricant. Additional requirements, due to the unique application of these microturbines, are zero contamination of the working fluid and entirely maintenance-free operation for many years. Losses in the gas foil bearings and within the rotor-stator gap of the generator become increasingly important as both rotational speed and mean operating pressure are increased. This paper presents the results of an experimental study, which obtained direct torque measurements on gas foil bearings and generator rotor-stator gaps. Test conditions for these measurements included rotational speeds up to 42,000 revolutions per minute, pressures up to 45 atmospheres, and test gases of nitrogen, helium, and carbon dioxide. These conditions provided a maximum test Taylor number of nearly one million. The results show an exponential rise in power loss as mean operating density is increased for both the gas foil bearing and generator windage. These typical "secondary" losses can become larger than the total system output power if conventional design paradigms are followed. A nondimensional analysis is presented to extend the experimental results into the CSC range for the generator windage.

  11. Gas exchange and the coagulation system of the blood during the effect on the body of high concentrations of oxygen and carbon dioxide

    NASA Technical Reports Server (NTRS)

    Palosh, L.; Agadzhanyan, N. A.; Davydov, G. A.; Rybakov, B. K.; Sergiyenko, A. S.

    1974-01-01

    Maximum permissible concentrations of oxygen and carbon dioxide in a controlled atmosphere were determined by evaluating their effects on human gas exchange, blood coagulation, and tolerances to acute hypoxia, acceleration, and physical loads. It was found that functional disturbances depend on the concentration of respiratory gases and the length of stay in an altered atmosphere. By changing the atmospheric composition and by bringing the gaseous environment into accordance with the work and rest regimen and energy expenditures, the general reactivity of the body changes favorably.

  12. The story of oxygen.

    PubMed

    Heffner, John E

    2013-01-01

    The history of oxygen from discovery to clinical application for patients with chronic lung disease represents a long and storied journey. Within a relatively short period, early investigators not only discovered oxygen but also recognized its importance to life and its role in respiration. The application of oxygen to chronic lung disease, however, took several centuries. In the modern era, physiologists pursued the chemical nature of oxygen and its physiologic interaction with cellular metabolism and gas transport. It took brazen clinicians, however, to pursue oxygen as a therapeutic resource for patients with chronic lung disease because of the concern in the 20th century of the risks of oxygen toxicity. Application of ambulatory oxygen devices allowed landmark investigations of the long-term effects of continuous oxygen that established its safety and efficacy. Although now well established for hypoxic patients, many questions remain regarding the benefits of oxygen for varying severity and types of chronic lung disease. PMID:23271817

  13. Lattice gas simulation of oxygen ordering in YBa sub 2 Cu sub 3 O sub 6+x showing dynamical scaling

    SciTech Connect

    Poulsen, H.F.; Andersen, J.V.; Mouritsen, O.G. ); Andersen, N.H. ); Bohr, H. )

    1991-05-20

    This paper reports on a 2-dimensional anisotropic lattice model for the oxygen ordering in the high T{sub c} superconductor of the YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} type shown to exhibit and ordering dynamics that obey algebraic growth laws which depend on whether it is an Ortho-I or Ortho-II phase. It is possible to relate this dynamical scaling behavior to a similar scaling in the experimentally observed temporal variation of the superconductivity transition temperature and hence suggesting a specific coupling between the coherence of oxygen order in the basal Cu-O planes and the superconducting state. Furthermore it is possible to explain the variation in the transition temperature with the oxygen density x by a phase mixing model of Ortho-II/Ortho-I domains and an assumption about the charge transfer between the basal and superconducting plane.

  14. Research on rechargeable oxygen electrodes.

    NASA Technical Reports Server (NTRS)

    Giner, J.; Holleck, G.; Malachesky, P. A.

    1970-01-01

    A research program is described which consisted of studying the effects of electrode cycling in very pure KOH solutions, with and without controlled additions of impurities, on oxide formation, oxygen evolution kinetics, oxygen reduction kinetics (including hydrogen peroxide formation), and changes in electrode structure. Bright platinum, platinized platinum, and Teflon-bonded platinum black electrodes were studied. Three main problem areas are identified: the buildup of a refractory anodic layer on prolonged cycling, which leads to a degradation of performance; the dissolution and subsequent deposition of dendritic platinum in the separator, leading to short-circuit ing and loss of electrocatalyst; and the disruptive effect of bubbling during gas evolution on charge. Each of these problem areas is analyzed, and remedial solutions are proposed.

  15. Optoacoustic measurements of human placenta and umbilical blood oxygenation

    NASA Astrophysics Data System (ADS)

    Nanovskaya, T. N.; Petrov, I. Y.; Petrov, Y.; Patrikeeva, S. L.; Ahmed, M. S.; Hankins, G. D. V.; Prough, D. S.; Esenaliev, R. O.

    2016-03-01

    Adequate oxygenation is essential for normal embryogenesis and fetal growth. Perturbations in the intrauterine oxidative environment during pregnancy are associated with several pathophysiological disorders such as pregnancy loss, preeclampsia, and intrauterine growth restriction. We proposed to use optoacoustic technology for monitoring placental and fetal umbilical blood oxygenation. In this work, we studied optoacoustic monitoring of oxygenation in placenta and umbilical cord blood ex vivo using technique of placenta perfusion. We used a medical grade, nearinfrared, tunable, optoacoustic system developed and built for oxygenation monitoring in blood vessels and in tissues. First, we calibrated the system for cord blood oxygenation measurements by using a CO-Oximeter (gold standard). Then we performed validation in cord blood circulating through the catheters localized on the fetal side of an isolated placental lobule. Finally, the oxygenation measurements were performed in the perfused placental tissue. To increase or decrease blood oxygenation, we used infusion of a gas mixture of 95% O2 + 5% CO2 and 95% N2 + 5% CO2, respectively. In placental tissue, up to four cycles of changes in oxygenation were performed. The optoacoustically measured oxygenation in circulating cord blood and in placental lobule closely correlated with the actual oxygenation data measured by CO-Oximeter. We plan to further test the placental and cord blood oxygenation monitoring with optoacoustics in animal and clinical studies.

  16. An energy equivalency analysis of trade-offs between thermal efficiency and standby loss requirements for commercial gas service water heaters

    SciTech Connect

    Somasundaram, S.; Jarnagin, R.E.; Keller, J.M.; Schliesing, J.S.

    1992-06-01

    The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Standing Standard Project Committee 90.1 has approved an addendum (90.lb) to ASHRAE/IES Standard 90.1-1989. The addendum specifies an increase in the minimum thermal efficiency requirement (from 77% to 78%), accompanied by an easing of the standby loss requirements, for commercial gas-fired service water heaters. The Pacific Northwest Laboratory performed an energy equivalency analysis to assess the impact of trade-offs between the improved thermal efficiency and the less stringent standby loss requirements. The analysis objective was to estimate whether the energy savings during firing would offset the increased energy losses during standby periods. The primary focus of this report is to summarize the major results of the analysis and provide a recommendation for minimum energy-efficiency commercial gas-fired service water heaters. Limitations to the availability of detailed performance and energy-use data for these commercial water heaters are also pointed out.

  17. Collision induced dissociation of doubly-charged ions: Coulomb explosion vs. neutral loss in [Ca(urea)]{sup 2+} gas phase unimolecular reactivity via chemical dynamics simulations

    SciTech Connect

    Spezia, Riccardo; Salpin, Jean-Yves; Cimas, Alvaro; Gaigeot, Marie-Pierre; Song, Kihyung; Hase, William L.

    2012-07-01

    In this paper we report different theoretical approaches to study the gas-phase unimolecular dissociation of the doubly-charged cation [Ca(urea)]{sup 2+}, in order to rationalize recent experimental findings. Quantum mechanical plus molecular mechanical (QM/MM) direct chemical dynamics simulations were used to investigate collision induced dissociation (CID) and rotational-vibrational energy transfer for Ar{sup +} [Ca(urea)]{sup 2+} collisions. For the picosecond time-domain of the simulations, both neutral loss and Coulomb explosion reactions were found and the differences in their mechanisms elucidated. The loss of neutral urea subsequent to collision with Ar occurs via a shattering mechanism, while the formation of two singly-charged cations follows statistical (or almost statistical) dynamics. Vibrational-rotational energy transfer efficiencies obtained for trajectories that do not dissociate during the trajectory integration were used in conjunction with RRKM rate constants to approximate dissociation pathways assuming complete intramolecular vibrational energy redistribution (IVR) and statistical dynamics. This statistical limit predicts, as expected, that at long time the most stable species on the potential energy surface (PES) dominate. These results, coupled with experimental CID from which both neutral loss and Coulomb explosion products were obtained, show that the gas phase dissociation of this ion occurs by multiple mechanisms leading to different products and that reactivity on the complicated PES is dynamically complex. (authors)

  18. Effects of oxygen gas pressure on structural, electrical, and thermoelectric properties of (ZnO){sub 3}In{sub 2}O{sub 3} thin films deposited by rf magnetron sputtering

    SciTech Connect

    Orikasa, Yuki; Hayashi, Naoaki; Muranaka, Shigetoshi

    2008-06-01

    Zinc indium oxide films were deposited by the rf magnetron sputtering method using a (ZnO){sub 3}In{sub 2}O{sub 3} target. The films were prepared at 573 K in various Ar/O{sub 2} sputtering gases (O{sub 2} content: 0%-25%). The effect of the oxygen gas content in the sputtering gas on the structural, optical, electrical, and thermoelectric properties of the films was investigated. The films had a c-axis oriented layer structure. The films deposited at 0%-3% oxygen gas contents exhibited a high electrical conductivity with a high carrier concentration, n{approx_equal}10{sup 20} cm{sup -3}, while the conductivity of the films significantly decreased above the 3% oxygen gas content, having a carrier concentration below 10{sup 18} cm{sup -3}. From the optical transmission measurement, the band gap of the films was estimated to be 3.01 eV. The films deposited at 3%-8% oxygen gas contents showed a high Seebeck coefficient, -300 {mu}V/K, while the maximum power factor, 4.78x10{sup -5} W/m K{sup 2}, was obtained at the 2% oxygen gas content. The Seebeck coefficient and the power factor were calculated on the basis of degenerate semiconductors. These results suggest that zinc indium oxide films have the possibility of being high performance thermoelectric materials.

  19. Gas Phase Chemistry of Li+ with Amides: the Observation of LiOH Loss in Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Guo, Cheng; Zhou, Yuping; Liu, Pengyuan; Chai, Yunfeng; Pan, Yuanjiang

    2012-07-01

    Collision-induced dissociation (CID) of Li+ adducts of three sets of compounds that contains an amide bond, including 2-(4, 6-dimethoxypyrimidin-2-ylsulfanyl)- N-phenylbenzamide, its derivatives and simpler structures was investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS). Observed fragment ions include those that reflect loss of LiOH. Other product ions result from the Smiles rearrangement and direct C-S bond cleavage. MS/MS of H/D exchange products demonstrated occurrence of a 1,3-H shift from the amide nitrogen atom to the phenyl ring of these compounds. The LiOH loss from Li+ adducts of amides was further examined by CID of [M + Li]+ ions of N-phenylbenzamide and N-phenylcinnamide. Loss of LiOH was essentially the sole fragmentation reaction observed for the former. For the latter, both losses of LiOH and H2O were discovered. The presence of electron-donating substituents of the phenyl ring of these compounds was found to facilitate elimination of LiOH, while that loss was retarded by electron-withdrawing substituents. Proposed fragment ion structures were supported by elemental compositions deduced from ultrahigh resolution Fourier transform ion cyclotron resonance tandem mass spectrometry (FTICR-MS/MS) m/z value determinations. Density functional theory-based (DFT) calculations were performed to evaluate potential mechanisms for these reactions.

  20. Versatile radar measurement of the electron loss rate in air

    SciTech Connect

    Dogariu, Arthur; Shneider, Mikhail N.; Miles, Richard B.

    2013-11-25

    We present an experimental method that makes possible in-situ measurements of the electron loss rate in arbitrary gas mixtures. A weakly ionized plasma is induced via resonant multiphoton ionization of trace amounts of nitric oxide seeded into the gas, and homodyne microwave scattering detection is used to study the dynamics of the electron loss mechanisms. Using this approach, the attachment rate for electrons to molecular oxygen in room temperature, atmospheric pressure air is determined. The measured 0.76 × 10{sup 8} s{sup −1} attachment rate is in very good agreement with predictions based on literature data.

  1. Analysis and modeling of PEM fuel cell stack performance: Effect of in situ reverse water gas shift reaction and oxygen bleeding

    NASA Astrophysics Data System (ADS)

    Karimi, G.; Li, Xianguo

    In this study the performance of a polymer electrolyte membrane (PEM) fuel cell stack is analyzed with a mathematical model when the stack operates on hydrocarbon reformate gas as the anode feed stream. It is shown that the effect of carbon dioxide dilution of the hydrogen dominated reformate gas has a minimal impact on the stack performance. However, the CO-poisoning effect due to the in situ reverse water gas shift reaction in the anode feed stream could have a very serious adverse impact on the stack performance, especially at high current densities. Thermodynamic calculations indicate that the equilibrium concentrations of CO could be as high as 100 ppm, generated by the in situ reverse water gas shift reaction, under the typical conditions of PEM fuel cell operation; and are influenced by the stack operating temperature and water content of the reformate anode feed. This CO-poisoning of the stack performance is shown mitigated effectively by introducing about 0.5-1% oxygen to the anode feed.

  2. Development of parallel sampling and analysis for the elucidation of gas/particle partitioning of oxygenated semi-volatile organics: a limonene ozonolysis study

    NASA Astrophysics Data System (ADS)

    Rossignol, S.; Chiappini, L.; Perraudin, E.; Rio, C.; Fable, S.; Valorso, R.; Doussin, J. F.

    2012-02-01

    Gas/particle partitioning behaviour of secondary organic matter semi-volatile fraction and the associated multiphase chemistry are key features to accurately evaluate secondary organic aerosol climate and health impacts. However, today, oxygenated secondary species partitioning is rarely assessed in experimental SOA studies and SOA modelling is still largely based on estimated partitioning data. This paper describes a new analytical approach, solvent free and easy to use, to explore the chemical composition of the secondary organic matter at a molecular scale in both gas and particulate phases. The method is based on thermal-desorption (TD) of gas and particulate samples, coupled with gas chromatography (GC) and mass spectrometry (MS), with on sampling supports derivatisation processes. Gaseous compounds are trapped on PFBHA or MTBSTFA pre-coated Tenax TA adsorbent tubes. Particulate samples are collected onto quartz or Teflon-quartz filters and subsequently exposed to PFBHA or MTBSTFA derivatisation reagents before TD-GC-MS analysis. Method development and validation are presented from an atmospherically relevant range of organic acids and carbonyl and hydroxyl compounds. Method application to a limonene ozonolysis experiment conducted in the EUPHORE simulation chamber under close-to-real conditions of low concentrations and relative humidity provides an overview of the method abilities. 25 compounds have been positively or tentatively identified, 9 being in both gaseous and particulate phases and 11, among them tri carboxylic acids, hydroxyl dicarboxylic acids and oxodicarboxylic acids, being detected for the first time.

  3. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 1: Cost Estimates of Small Modular Systems

    SciTech Connect

    Nexant Inc.

    2006-05-01

    This deliverable is the Final Report for Task 1, Cost Estimates of Small Modular Systems, as part of NREL Award ACO-5-44027, ''Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment''. Subtask 1.1 looked into processes and technologies that have been commercially built at both large and small scales, with three technologies, Fluidized Catalytic Cracking (FCC) of refinery gas oil, Steam Methane Reforming (SMR) of Natural Gas, and Natural Gas Liquids (NGL) Expanders, chosen for further investigation. These technologies were chosen due to their applicability relative to other technologies being considered by NREL for future commercial applications, such as indirect gasification and fluidized bed tar cracking. Research in this subject is driven by an interest in the impact that scaling has on the cost and major process unit designs for commercial technologies. Conclusions from the evaluations performed could be applied to other technologies being considered for modular or skid-mounted applications.

  4. Study of a blast-furnace smelting technology which involves the injection of pulverized-coal fuel, natural gas, and an oxygen-enriched blast into the hearth

    SciTech Connect

    Ryzhenkov, A.N.; Yaroshevskii, S.L.; Zamuruev, V.P.; Popov, V.E.; Afanas'eva, Z.K.

    2006-05-15

    Studies were made of features of a blast-furnace smelting technology that involves the injection of natural gas (NG), oxygen (O{sub 2}) and pulverized-coal fuel (PCF) into the hearth. The technology has been implemented in the compensation and overcompensation regimes, which has made it possible to maintain or improve the gas dynamics of the furnace, the conditions for the reduction of iron oxides, the heating of the charge, and PCF combustion in the tuyere zone as PCF consumption is increased and coke use is decreased. Under the given conditions, with the blast having an oxygen content of 25.64-25.7%, the hearth injection of 131-138 kg PCF and 65-69 m{sup 3} NG for each ton of pig iron has made it possible to reduce coke consumption by 171-185 kg/ton pig (30.2-32.7%), reduce the consumption of comparison fuel by 36-37 kg/ton (5.2-5.3%), and lower the production cost of the pig iron by 43-49 hryvnas/ton (3.7-6.4%). Here, furnace productivity has increased 3.8-6.5%, while the quality of the conversion pig iron remains the same as before. Measures are being implemented to further increase the level and efficiency of PCF use.

  5. Simulation studies of the separation of Kr-85 radionuclide gas from nitrogen and oxygen across nanoporous graphene membranes in different pore configurations

    NASA Astrophysics Data System (ADS)

    Fatemi, S. Mahmood; Sepehrian, Hamid; Arabieh, Masoud

    2016-05-01

    Separating molecular species is an important precursor for various applications. In this work, we have utilized molecular dynamics (MD) simulations to examine how pore radius and structure affect the separation process. We show from MD simulations that 2-D graphene sheets with designed sub-nanometer pores can efficiently separate the Kr-85 radionuclide gas from an N2/O2 mixture. Three species of gases (Kr-85, N2 and O2 were considered in the simulation box in which different sizes and geometries of pores were modeled on the graphene sheet. The ( 30× 30× 80 Å^3 simulation box contains a nanoporous graphene membrane in the middle of the box and two fixed walls with equal distances on both sides of the nanoporous graphene. The results revealed that Kr-85 separation was improved by using an optimized pore structure. It was also found that the Kr-85 gas radionuclides could be completely separated from nitrogen and oxygen molecules in the pore-7 configuration. Restriction of the molecular orientation largely prohibited the permeation of nitrogen molecules. It was also found that nitrogen was more strongly adsorbed onto the membrane than oxygen, while krypton was not adsorbed.

  6. Adsorption of SF6 decomposed gas on anatase (101) and (001) surfaces with oxygen defect: a density functional theory study.

    PubMed

    Zhang, Xiaoxing; Chen, Qinchuan; Tang, Ju; Hu, Weihua; Zhang, Jinbin

    2014-01-01

    The detection of partial discharge by analyzing the components of SF6 gas in gas-insulated switchgears is important to the diagnosis and assessment of the operational state of power equipment. A gas sensor based on anatase TiO2 is used to detect decomposed gases in SF6. In this paper, first-principle density functional theory calculations are adopted to analyze the adsorption of SO2, SOF2, and SO2F2, the primary decomposition by-products of SF6 under partial discharge, on anatase (101) and (001) surfaces. Simulation results show that the perfect anatase (001) surface has a stronger interaction with the three gases than that of anatase (101), and both surfaces are more sensitive and selective to SO2 than to SOF2 and SO2F2. The selection of a defect surface to SO2, SOF2, and SO2F2 differs from that of a perfect surface. This theoretical result is corroborated by the sensing experiment using a TiO2 nanotube array (TNTA) gas sensor. The calculated values are analyzed to explain the results of the Pt-doped TNTA gas sensor sensing experiment. The results imply that the deposited Pt nanoparticles on the surface increase the active sites of the surface and the gas molecules may decompose upon adsorption on the active sites. PMID:24755845

  7. Adsorption of SF6 decomposed gas on anatase (101) and (001) surfaces with oxygen defect: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxing; Chen, Qinchuan; Tang, Ju; Hu, Weihua; Zhang, Jinbin

    2014-04-01

    The detection of partial discharge by analyzing the components of SF6 gas in gas-insulated switchgears is important to the diagnosis and assessment of the operational state of power equipment. A gas sensor based on anatase TiO2 is used to detect decomposed gases in SF6. In this paper, first-principle density functional theory calculations are adopted to analyze the adsorption of SO2, SOF2, and SO2F2, the primary decomposition by-products of SF6 under partial discharge, on anatase (101) and (001) surfaces. Simulation results show that the perfect anatase (001) surface has a stronger interaction with the three gases than that of anatase (101), and both surfaces are more sensitive and selective to SO2 than to SOF2 and SO2F2. The selection of a defect surface to SO2, SOF2, and SO2F2 differs from that of a perfect surface. This theoretical result is corroborated by the sensing experiment using a TiO2 nanotube array (TNTA) gas sensor. The calculated values are analyzed to explain the results of the Pt-doped TNTA gas sensor sensing experiment. The results imply that the deposited Pt nanoparticles on the surface increase the active sites of the surface and the gas molecules may decompose upon adsorption on the active sites.

  8. Gas analysis using Raman spectroscopy demonstrates the presence of intraperitoneal air (nitrogen and oxygen) in a cohort of children undergoing pediatric laparoscopic surgery.

    PubMed

    Taylor, Susan P; Sato, Thomas T; Balcom, Anthony H; Groth, Travis; Hoffman, George M

    2015-02-01

    Clinically significant gas embolism during laparoscopy is a rare but potentially catastrophic event. Case reports suggest that air, in addition to the insufflation gas, may be present. We studied the effects of equipment design and flushing techniques on the composition of gas present under experimental and routine pediatric surgical conditions. Concentrations of nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) were measured by Raman spectroscopy in gas delivered to and retrieved from a mock peritoneum during simulated laparoscopy. We then analyzed the composition of insufflated and recovered gases during elective laparoscopic procedures conducted with CO2-preflushed and unflushed tubing to determine the presence of significant (10%) quantities of air. In vitro, CO2 was not detected at the distal end of insufflator tubing until after delivery of approximately 0.2 L of gas, and N2 persisted until >0.4 L was delivered, with 40% ± 8% (mean ± SD, range 33%-49%) recovered from the mock peritoneum at the termination of initial insufflation. In clinical studies, preflushing reduced the initial concentration of N2 from 78% ± 0.5% to 23% ± 15%, but >10% air was detected in all subsequent samples, regardless of insufflation technique. Laparoscopic equipment and practice routinely permit delivery of air to the insufflated cavity. Purging the equipment with CO2 reduces but does not eliminate air (N2, O2) within the peritoneal cavity during laparoscopy. Thus, when vascular injury occurs, embolized gases will contain variable quantities of N2, O2, and CO2. As the initial insufflation volume diminishes and approaches the volume of the insufflation tubing, which occurs in infants and young pediatric patients, the concentration of N2 will approximate that of room air in an unflushed system. Small insufflation volumes containing high N2 concentrations can contribute to catastrophic air emboli in neonates and small pediatric patients. PMID:25602452

  9. Charge-state-dependent collisional energy-loss straggling of swift ions in a degenerate electron gas

    NASA Astrophysics Data System (ADS)

    Nagy, I.; Aldazabal, I.

    2009-12-01

    In order to characterize the statistical aspect of the energy loss in particle penetration, Bohr developed a kinetic theory and applied it to a beam of fast α particles interacting with free electrons. The present study rests on this classical theory of collisional straggling, and it is implemented by using a partially screened Coulomb potential to model the electron-projectile interaction. The deflection angle of electron scattering in this long-ranged field is calculated analytically within the framework of classical mechanics. The transport fluctuation cross section, which is the basic quantity to the collisional straggling in Bohr’s modeling, is determined numerically. By varying the number of bound electrons around the swift He ions, the effect of prefixed charge states in the collisional energy-loss straggling is quantified. An incoherent weighted summation of different fixed charge-state channels is discussed as well, by using normalized probabilities.

  10. Gas transfer velocities for quantifying methane, oxygen and other gas fluxes through the air-water interface of wetlands with emergent vegetation

    NASA Astrophysics Data System (ADS)

    Poindexter, C.; Variano, E. A.

    2012-12-01

    Empirical models for the gas transfer velocity, k, in the ocean, lakes and rivers are fairly well established, but there are few data to predict k for wetlands. We have conducted experiments in a simulated emergent marsh in the laboratory to explore the relationship between k, wind shear and thermal convection. Now we identify the implications of these results for gas transfer in actual wetlands by (1) quantifying the range of wind conditions in emergent vegetation canopies and the range of thermal convection intensities in wetland water columns, and (2) describing the non-linear interaction of these two stirring forces over their relevant ranges in wetlands. We measured mean wind speeds and wind speed variance within the shearless region of a Schoenoplectus-Typha marsh canopy in the Sacramento-San Joaquin Delta (Northern California, USA). The mean wind speed within this region, , is significantly smaller than wind above the canopy. Based on our laboratory experiments, for calm or even average wind conditions in this emergent marsh k600 is only on the order 0.1 cm hr-1 (for neutrally or stably stratified water columns). We parameterize unstable thermal stratification and the resulting thermal convection using the heat flux through the air-water interface, q. We analyzed a water temperature record for the Schoenoplectus-Typha marsh to obtain a long-term heat flux record. We used these heat flux data along with short-term heat flux data from other wetlands in the literature to identify the range of the gas transfer velocity associated with thermal convection in wetlands. The typical range of heat fluxes through water columns shaded by closed emergent canopies (-200 W m-2 to +200 W m-2) yields k600 values of 0.5 - 2.5 cm hr-1 according to the model we developed in the laboratory. Thus for calm or average wind conditions, the gas transfer velocity associated with thermal convection is significantly larger than the gas transfer velocity associated with wind

  11. Synthesis of a further improved porous polymer for the separation of nitrogen, oxygen, argon, and carbon monoxide by gas chromatography

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.

    1986-01-01

    A further improvement has been made in the synthesis of an N-type porous polymer for the separation of permanent gases. Changing the ratios of reactants and diluting the Hi-DVB with styrene led to a porous polymer gas chromatographic packing which is superior to commercial products and to the author's own previously reported custom-made polymer.

  12. Batteries: Avoiding oxygen

    NASA Astrophysics Data System (ADS)

    Hardwick, Laurence J.

    2016-08-01

    In the development of lithium–air batteries, managing the phase change between gaseous oxygen and crystalline lithium peroxide is a key challenge. Now, a high-performing sealed battery with an oxygen anion-redox electrode is presented that does not involve any gas evolution.

  13. Studies on the room temperature growth of nanoanatase phase TiO{sub 2} thin films by pulsed dc magnetron with oxygen as sputter gas

    SciTech Connect

    Karuppasamy, A.; Subrahmanyam, A.

    2007-03-15

    The anatase phase titanium dioxide (TiO{sub 2}) thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.5x10{sup -2} mbar are nanocrystalline (grain size of 28-43 nm) with anatase phase. The films deposited at the chamber pressure of 7.2x10{sup -2} mbar are found to be highly crystalline with a direct optical band gap of 3.40 eV, refractive index of 2.54 (at {lambda}=400 nm), and work function of 4.77 eV (determined by the Kelvin probe measurements). From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO{sub 2} at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by 'negative ion effects' and the enhanced density of TiO, TiO{sup +}, TiO{sub 2}{sup +}, and O{sup 2+} particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.2x10{sup -2} mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of {approx}45%, coloration efficiency of 14.7 cm{sup 2} C{sup -1}, and switching time (t{sub c}) of 50 s for a 2x2 cm{sup 2} device at {lambda}=633 nm.

  14. In-situ ambient quantification of monoterpenes, sesquiterpenes, and related oxygenated compounds during BEARPEX 2007 - implications for gas- and particle-phase chemistry

    NASA Astrophysics Data System (ADS)

    Bouvier-Brown, N. C.; Goldstein, A. H.; Gilman, J. B.; Kuster, W. C.; de Gouw, J. A.

    2009-04-01

    We quantified ambient mixing ratios of 9 monoterpenes, 6 sesquiterpenes, methyl chavicol, the oxygenated terpene linalool, and nopinone using an in-situ gas chromatograph with a quadrupole mass spectrometer (GC-MS). These measurements were a part of the 2007 Biosphere Effects on AeRosols and Photochemistry EXperiment (BEARPEX) at Blodgett Forest, a ponderosa pine forest in the Sierra Nevada Mountains of California. To our knowledge, these observations represent the first direct in-situ ambient quantification of the sesquiterpenes α-bergamotene, longifolene, α-farnesene, and β-farnesene. From average diurnal mixing ratio profiles, we show that α-farnesene emissions are dependent mainly on temperature whereas α-bergamotene and β-farnesene emissions are temperature- and light-dependent. The amount of sesquiterpene mass quantified above the canopy was small (averaging a total of 3.3 ppt during the day), but nevertheless these compounds contributed 8.5% to the overall ozone reactivity above the canopy. Assuming that the monoterpene-to-sesquiterpene emission rate in the canopy is similar to that observed in branch enclosure studies at the site during comparable weather conditions, and the average yield of aerosol mass from these sesquiterpenes is 10-50%, the amount of sesquiterpene mass reacted within the Blodgett Forest canopy alone accounts for 8-38% of the total organic aerosol mass measured during BEARPEX. The oxygenated monoterpene linalool was also quantified for the first time at Blodgett Forest. The linalool mass contribution was small (9.9 ppt and 0.74 ppt within and above the canopy, respectively), but it contributed 1.2% to the total ozone reactivity above the canopy. Reactive and semi-volatile compounds, especially sesquiterpenes, significantly impact the gas- and particle-phase chemistry of the atmosphere at Blodgett Forest and should be included in both biogenic volatile organic carbon emission and atmospheric chemistry models.

  15. Corrosion of 310 stainless steel in H2- H2O- H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Astrophysics Data System (ADS)

    Rao, D. Bhogeswara; Jacob, K. T.; Nelson, Howard G.

    1983-02-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 × 10-13 Nm-2 and sulfur potentials ranging from 0.19 × 10-2 Nm-2 to 33 × 10-2 Nm-2. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials ( P S 2 ± 2.7 × 10-2 Nm-2) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfidation. At low sulfur potentials ( P S 2 ± 0.19 × 10-2 Nm-2) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases. Thermochemical diagrams for the Fe-Cr-S-O, Fe-Ni-S-O, Cr-Ni-S-O, and Si-Cr-S-O systems were constructed, and the experimental results are discussed in relation to these diagrams. Based on this comparison, reasonable corrosion mechanisms were developed. At high sulfur potentials, oxide and sulfide phases initially nucleate as separate islands. Overgrowth of the oxide by the sulfide occurs and an exchange reaction governs the corrosion process. Preoxidation at low oxygen potentials and 1150 K is beneficial in suppressing sulfidation at high sulfur potentials.

  16. Preparation of a heteroepitaxial LaxSryMnzO3/BiFeO3 bilayer by r.f. magnetron sputtering with various oxygen gas flow ratios

    NASA Astrophysics Data System (ADS)

    Naganuma, H.; Ichinose, T.; Begum, H. A.; Sato, S.; Han, X. F.; Miyazaki, T.; Bae, In-T.; Oogane, M.; Ando, Y.

    2014-08-01

    BiFeO3 (BFO) and LaxSryMnzO3 (LSMO) films were epitaxially grown on SrTiO3 (100) substrates by r.f. magnetron sputtering with various oxygen gas flow ratios (FO2). Compositional ratios of each atom in both of BFO and LSMO could be controlled kept to around 10 at.% by changing FO2. Adjusting the compositional ratio to La0.35Sr0.15Mn0.5O3 not only increase Tc of LSMO but also produces sufficient oxygen to form a perovskite lattice. For an LSMO/BFO heterostructure, detailed observation by cross sectional transmission electron microscopy (TEM) revealed that the lattice of rhombohedral (SG: R-3c) LSMO was shrank by a clamping effect from the SrTiO3 substrates, and then the BFO was grown in two layers: (i) an interfacial BFO layer (7 nm thick) with evenly shrunk a-axis and c-axis, and (ii) an upper BFO layer (25 nm thick) expanded along the c-axis. Neither misfit strain nor dislocations appeared at the interface between the shrunken BFO and LSMO layers, and these heterostructures did not show exchange bias. These results suggest that BFO is suitable for a tunneling barrier combine with LSMO electrode.

  17. Cooling rates of living and killed chicken and quail eggs in air and in helium-oxygen gas mixture.

    PubMed

    Tazawa, H; Turner, J S; Paganelli, C V

    1988-01-01

    1. In a helium atmosphere, heat is dissipated from a surface 3.5 times faster than it is in air. Eggs in a helium-oxygen atmosphere cool only 1.4 times faster than they cool in air. This signifies that internal resistance to heat flow is a significant factor in the cooling rates of eggs. 2. Heat flow occurs inside an egg in two ways: by conduction through the tissues and in flowing blood. Killing an embryo stops the latter, but not the former. Eggs cool more slowly after they have been killed, signifying that blood flow can be an important component in an egg's internal flows of heat. 3. Blood flow should be a relatively more important component of heat flow in large eggs than in small eggs. The difference in conductance between living and killed eggs is larger in 60 g chicken eggs than it is in 10 g quail eggs. PMID:2900113

  18. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 2: Gas Cleanup Design and Cost Estimates -- Wood Feedstock

    SciTech Connect

    Nexant Inc.

    2006-05-01

    As part of Task 2, Gas Cleanup and Cost Estimates, Nexant investigated the appropriate process scheme for treatment of wood-derived syngas for use in the synthesis of liquid fuels. Two different 2,000 metric tonne per day gasification schemes, a low-pressure, indirect system using the gasifier, and a high-pressure, direct system using gasification technology were evaluated. Initial syngas conditions from each of the gasifiers was provided to the team by the National Renewable Energy Laboratory. Nexant was the prime contractor and principal investigator during this task; technical assistance was provided by both GTI and Emery Energy.

  19. Hearing Loss

    MedlinePlus

    ... version of this page please turn Javascript on. Hearing Loss What is Hearing Loss? Hearing loss is a common problem caused by ... sec Click to watch this video Types of Hearing Loss Hearing loss comes in many forms. It can ...

  20. Gas chromatographic separation of nitrogen, oxygen, argon, and carbon monoxide using custom-made porous polymers from high purity divinylbenzene

    NASA Technical Reports Server (NTRS)

    Pollock, G. E.; Ohara, D.; Hollis, O. L.

    1984-01-01

    Existing porous polymers were surveyed for their ability to separate the subject gases. Certain products that showed more promise than others were synthesized and the existing synthetic procedures studied and modified to produce new polymers with enhanced ability to separate the subject gases. Evaluation of the porous polymers was carried out practically by gas chromatography at ambient temperature. The modified synthetic procedures were somewhat simpler than the originals. The new porous polymers made with high purity divinylbenzene enabled use of shorter columns to obtain the separations desired.

  1. Multi-scale approach to the modeling of fission gas discharge during hypothetical loss-of-flow accident in gen-IV sodium fast reactor

    SciTech Connect

    Behafarid, F.; Shaver, D. R.; Bolotnov, I. A.; Jansen, K. E.; Antal, S. P.; Podowski, M. Z.

    2012-07-01

    The required technological and safety standards for future Gen IV Reactors can only be achieved if advanced simulation capabilities become available, which combine high performance computing with the necessary level of modeling detail and high accuracy of predictions. The purpose of this paper is to present new results of multi-scale three-dimensional (3D) simulations of the inter-related phenomena, which occur as a result of fuel element heat-up and cladding failure, including the injection of a jet of gaseous fission products into a partially blocked Sodium Fast Reactor (SFR) coolant channel, and gas/molten sodium transport along the coolant channels. The computational approach to the analysis of the overall accident scenario is based on using two different inter-communicating computational multiphase fluid dynamics (CMFD) codes: a CFD code, PHASTA, and a RANS code, NPHASE-CMFD. Using the geometry and time history of cladding failure and the gas injection rate, direct numerical simulations (DNS), combined with the Level Set method, of two-phase turbulent flow have been performed by the PHASTA code. The model allows one to track the evolution of gas/liquid interfaces at a centimeter scale. The simulated phenomena include the formation and breakup of the jet of fission products injected into the liquid sodium coolant. The PHASTA outflow has been averaged over time to obtain mean phasic velocities and volumetric concentrations, as well as the liquid turbulent kinetic energy and turbulence dissipation rate, all of which have served as the input to the core-scale simulations using the NPHASE-CMFD code. A sliding window time averaging has been used to capture mean flow parameters for transient cases. The results presented in the paper include testing and validation of the proposed models, as well the predictions of fission-gas/liquid-sodium transport along a multi-rod fuel assembly of SFR during a partial loss-of-flow accident. (authors)

  2. Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup, and Oxygen Separation Equipment; Task 2: Gas Cleanup Design and Cost Estimates -- Black Liquor Gasification

    SciTech Connect

    Nexant Inc.

    2006-05-01

    As part of Task 2, Gas Cleanup and Cost Estimates, Nexant investigated the appropriate process scheme for removal of acid gases from black liquor-derived syngas for use in both power and liquid fuels synthesis. Two 3,200 metric tonne per day gasification schemes, both low-temperature/low-pressure (1100 deg F, 40 psi) and high-temperature/high-pressure (1800 deg F, 500 psi) were used for syngas production. Initial syngas conditions from each of the gasifiers was provided to the team by the National Renewable Energy Laboratory and Princeton University. Nexant was the prime contractor and principal investigator during this task; technical assistance was provided by both GTI and Emery Energy.

  3. Corrosion of 310 stainless steel in H2-H2O-H2S gas mixtures: Studies at constant temperature and fixed oxygen potential

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Jacob, K. T.; Nelson, H. G.

    1981-01-01

    Corrosion of SAE 310 stainless steel in H2-H2O-H2S gas mixtures was studied at a constant temperature of 1150 K. Reactive gas mixtures were chosen to yield a constant oxygen potential of approximately 6 x 10 to the minus 13th power/cu Nm and sulfur potentials ranging from 0.19 x 10 to the minus 2nd power/cu Nm to 33 x 10 to the minus 2nd power/cu Nm. The kinetics of corrosion were determined using a thermobalance, and the scales were analyzed using metallography, scanning electron microscopy, and energy dispersive X-ray analysis. Two corrosion regimes, which were dependent on sulfur potential, were identified. At high sulfur potentials (p sub S sub 2 less than or equal to 2.7 x 10 to the minus 2nd power/cu Nm) the corrosion rates were high, the kinetics obeyed a linear rate equation, and the scales consisted mainly of sulfide phases similar to those observed from pure sulfication. At low sulfur potentials (P sub S sub 2 less than or equal to 0.19 x 10 to the minus 2nd power/cu Nm) the corrosion rates were low, the kinetics obeyed a parabolic rate equation, and scales consisted mainly of oxide phases.

  4. The Effect of Pericellular Oxygen Levels on Proteomic Profile and Lipogenesis in 3T3-L1 Differentiated Preadipocytes Cultured on Gas-Permeable Cultureware.

    PubMed

    Weiszenstein, Martin; Pavlikova, Nela; Elkalaf, Moustafa; Halada, Petr; Seda, Ondrej; Trnka, Jan; Kovar, Jan; Polak, Jan

    2016-01-01

    Pericellular oxygen concentration represents an important factor in the regulation of cell functions, including cell differentiation, growth and mitochondrial energy metabolism. Hypoxia in adipose tissue has been associated with altered adipokine secretion profile and suggested as a possible factor in the development of type 2 diabetes. In vitro experiments provide an indispensable tool in metabolic research, however, physical laws of gas diffusion make prolonged exposure of adherent cells to desired pericellular O2 concentrations questionable. The aim of this study was to investigate the direct effect of various O2 levels (1%, 4% and 20% O2) on the proteomic profile and triglyceride accumulation in 3T3-L1 differentiated preadipocytes using gas-permeable cultureware. Following differentiation of cells under desired pericellular O2 concentrations, cell lysates were subjected to two-dimensional gel electrophoresis and protein visualization using Coomassie blue staining. Spots showing differential expression under hypoxia were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. All identified proteins were subjected to pathway analysis. We observed that protein expression of 26 spots was reproducibly affected by 4% and 1% O2 (17 upregulated and 9 downregulated). Pathway analysis showed that mitochondrial energy metabolism and triglyceride synthesis were significantly upregulated by hypoxia. In conclusion, this study demonstrated the direct effects of pericellular O2 levels on adipocyte energy metabolism and triglyceride synthesis, probably mediated through the reversed tricarboxylic acid cycle flux. PMID:27023342

  5. The Effect of Pericellular Oxygen Levels on Proteomic Profile and Lipogenesis in 3T3-L1 Differentiated Preadipocytes Cultured on Gas-Permeable Cultureware

    PubMed Central

    Weiszenstein, Martin; Pavlikova, Nela; Elkalaf, Moustafa; Halada, Petr; Seda, Ondrej; Trnka, Jan; Kovar, Jan; Polak, Jan

    2016-01-01

    Pericellular oxygen concentration represents an important factor in the regulation of cell functions, including cell differentiation, growth and mitochondrial energy metabolism. Hypoxia in adipose tissue has been associated with altered adipokine secretion profile and suggested as a possible factor in the development of type 2 diabetes. In vitro experiments provide an indispensable tool in metabolic research, however, physical laws of gas diffusion make prolonged exposure of adherent cells to desired pericellular O2 concentrations questionable. The aim of this study was to investigate the direct effect of various O2 levels (1%, 4% and 20% O2) on the proteomic profile and triglyceride accumulation in 3T3-L1 differentiated preadipocytes using gas-permeable cultureware. Following differentiation of cells under desired pericellular O2 concentrations, cell lysates were subjected to two-dimensional gel electrophoresis and protein visualization using Coomassie blue staining. Spots showing differential expression under hypoxia were analyzed using matrix-assisted laser desorption/ionization mass spectrometry. All identified proteins were subjected to pathway analysis. We observed that protein expression of 26 spots was reproducibly affected by 4% and 1% O2 (17 upregulated and 9 downregulated). Pathway analysis showed that mitochondrial energy metabolism and triglyceride synthesis were significantly upregulated by hypoxia. In conclusion, this study demonstrated the direct effects of pericellular O2 levels on adipocyte energy metabolism and triglyceride synthesis, probably mediated through the reversed tricarboxylic acid cycle flux. PMID:27023342

  6. Oxygen desaturation during a 6-minute walk test as a predictor of maximal exercise-induced gas exchange abnormalities in sarcoidosis

    PubMed Central

    Chenivesse, Cecile; Boulanger, Sarah; Langlois, Carole; Wemeau-Stervinou, Lidwine; Perez, Thierry

    2016-01-01

    Background Common tests for evaluating gas exchange impairment have different strengths and weaknesses. Alveolar-to-arterial oxygen pressure difference (AaDO2) at peak exercise is a sensitive indicator but it cannot be measured repeatedly. Diffusing capacity of the lung for carbon monoxide (DLco) is measured at rest and may be too insensitive to predict the effects of exercise on gas exchange impairment. Oxygen desaturation during a 6-minute walk test (∆SpO2-6MWT) can be measured repeatedly, but its value in sarcoidosis is unknown. Here, we evaluated the ability of ∆SpO2-6MWT and DLco to predict gas exchange impairment during exercise in sarcoidosis. Methods This retrospective study of 130 subjects with sarcoidosis investigated the relationship between DLco, ∆SpO2-6MWT, and peak AaDO2 using correlation tests, inter-test reliability analyses, and predictive values. For the analyses of inter-test reliability and predictive values, DLco, peak AaDO2, and ∆SpO2-6MWT were considered as binary variables (normal/abnormal) according to previously defined thresholds. Results Correlation coefficients between DLco, ∆SpO2-6MWT, and peak AaDO2 were intermediate (0.53–0.67, P<0.0003) and Kappa coefficients were low (0.21–0.42, P=0.0003–0.02). DLco predicted (I) increased peak AaDO2 with a positive predictive value (PPV) of 66% and a negative predictive value (NPV) of 78% and (II) increased ∆SpO2-6MWT with a PPV at 36% and an NPV at 88%. Normal DLco was a good predictor of the absence of severe desaturation during the 6MWT (94% NPV) and at peak exercise during cardiopulmonary exercise test (CPET) (100% NPV). ∆SpO2-6MWT predicted peak AaDO2 increase with a PPV of 74% and an NPV of 60%. Conclusions In a large population of sarcoidosis patients, neither ∆SpO2-6MWT nor DLco was a good predictor of increased peak AaDO2. In contrast, normal DLco was a good predictor of the absence of severe desaturation during the 6MWT and at peak exercise during CPET. PMID

  7. Quantifying denitrification losses from a sub-tropical pasture in Queensland/Australia - use of the 15N gas flux method

    NASA Astrophysics Data System (ADS)

    Friedl, Johannes; Scheer, Clemens; Warner, Daniel; Grace, Peter

    2014-05-01

    The microbial mediated production of nitrous oxide (N2O) and its reduction to dinitrogen (N2) via denitrification represents a loss of nitrogen (N) from fertilised agro ecosystems to the atmosphere. Although denitrification remains a major uncertainty in estimating N losses from soils, the magnitude of N2 losses and related N2:N2O ratios from soils are largely unknown due to difficulties measuring N2 against a high atmospheric background. In order to address this lack of data, this study investigated the influence of different soil moisture contents on N2 and N2O emissions from a sub-tropical pasture in Queensland/Australia using the 15N gas flux method. Intact soil cores were incubated over 14 days at 80% and 100% water filled pore space (WFPS). Gas samples were taken up to six times per day after application of 15N labelled nitrate, equivalent to 50 kg N ha-1 and analysed for N2 and N2O by isotope ratio mass spectrometry. Fluxes were calculated assuming non-random 15N distribution in the headspace according to Mulvaney and Kurtz (1984) using the labelled pool of nitrate estimated from N2O measurements (Stevens and Laughlin 2001). The main product of denitrification in both treatments was N2. N2 emissions exceeded N2O emissions by a factor of 1.3 ± 0.3 at 80% WFPS and a factor of 3 ± 0.8 at 100% WFPS. The total amount of N-N2 lost over the incubation period was 13.5±1.0 kg N ha-1 at 80% WFPS and 21.8±1.8 kg ha-1 at 100% WFPS respectively. Over the entire incubation period, N2 emissions remained elevated at 100% WFPS, showing high variation between soil cores, while related N2O emissions decreased. At 80% WFPS, N2 emissions increased constantly over time showing significantly higher values after day five. At the same time, N2O fluxes declined. Consequently, N2:N2O ratios rose over the incubation period in both treatments. Overall denitrification rates and related N2:N2O ratios were higher at 100% WFPS compared to 80% WFPS, confirming WFPS as a major driver of

  8. Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in the ambient air of two French alpine valleys. Part 1: Concentrations, sources and gas/particle partitioning

    NASA Astrophysics Data System (ADS)

    Albinet, A.; Leoz-Garziandia, E.; Budzinski, H.; Villenave, E.; Jaffrezo, J.-L.

    Ambient measurements (gas+particle phases) of 16 polycyclic aromatic hydrocarbons, 17 nitrated PAHs (NPAHs) and eight oxygenated PAHs (OPAHs) were carried out during the winter 2002-2003 and the summer 2003 in two French alpine valleys on various types of sites (traffic, sub-urban, altitude and rural). Atmospheric concentrations of these classes of compounds are of interest because they include potential mutagens and carcinogens. During both summer and winter campaigns, OPAH concentration levels were of the same order of magnitude as PAH ones while NPAH concentrations were one to two orders of magnitude lower. Total particulate PAH, OPAH and NPAH concentrations were higher in the Chamonix valley than in the Maurienne valley. A heavier pollutant accumulation process in the Chamonix valley and geomorphology promoting their dispersion seem to explain such differences. Despite reaching lower atmospheric concentrations, NPAHs seemed to account up to 20% of carcinogenic potency of particulates collected at the sites away from pollution sources. The formation of secondary compounds such as NPAHs increases significantly the carcinogenic risk at the sites away from pollution sources. Study with 2-nitrofluoranthene/1-nitropyrene ratio showed that NPAH gas phase formation was hindered in winter, and when relative contribution from primary sources was higher. Nevertheless, in winter under specific conditions, evidence of secondary NPAH formations was observed at sub-urban and traffic sites (snowfalls) and rural site (accumulation of pollutants and snowfalls). For all sampling sites, the daytime OH initiated reaction seemed to be the dominant gas phase formation pathway over the NO 3 initiated reaction. The fraction of PAHs, OPAHs and NPAHs associated with the particle phase was strongly depending on their vapour pressure and the ambient conditions.

  9. Monolithic solid electrolyte oxygen pump

    DOEpatents

    Fee, Darrell C.; Poeppel, Roger B.; Easler, Timothy E.; Dees, Dennis W.

    1989-01-01

    A multi-layer oxygen pump having a one-piece, monolithic ceramic structure affords high oxygen production per unit weight and volume and is thus particularly adapted for use as a portable oxygen supply. The oxygen pump is comprised of a large number of small cells on the order of 1-2 millimeters in diameter which form the walls of the pump and which are comprised of thin, i.e., 25-50 micrometers, ceramic layers of cell components. The cell components include an air electrode, an oxygen electrode, an electrolyte and interconnection materials. The cell walls form the passages for input air and for exhausting the oxygen which is transferred from a relatively dilute gaseous mixture to a higher concentration by applying a DC voltage across the electrodes so as to ionize the oxygen at the air electrode, whereupon the ionized oxygen travels through the electrolyte and is converted to oxygen gas at the oxygen electrode.

  10. Compaction and gas loss in welded pyroclastic deposits as revealed by porosity, permeability, and electrical conductivity measurements of the Shevlin Park Tuff

    USGS Publications Warehouse

    Wright, Heather M.; Cashman, Katharine V.

    2014-01-01

    Pyroclastic flows produced by large volcanic eruptions commonly densify after emplacement. Processes of gas escape, compaction, and welding in pyroclastic-flow deposits are controlled by the physical and thermal properties of constituent material. Through measurements of matrix porosity, permeability, and electrical conductivity, we provide a framework for understanding the evolution of pore structure during these processes. Using data from the Shevlin Park Tuff in central Oregon, United States, and from the literature, we find that over a porosity range of 0%–70%, matrix permeability varies by almost 10 orders of magnitude (from 10–20 to 10–11 m2), with over three orders of magnitude variation at any given porosity. Part of the variation at a given porosity is due to permeability anisotropy, where oriented core samples indicate higher permeabilities parallel to foliation (horizontally) than perpendicular to foliation (vertically). This suggests that pore space is flattened during compaction, creating anisotropic crack-like networks, a geometry that is supported by electrical conductivity measurements. We find that the power law equation: k1 = 1.3 × 10–21 × ϕ5.2 provides the best approximation of dominant horizontal gas loss, where k1 = permeability, and ϕ = porosity. Application of Kozeny-Carman fluid-flow approximations suggests that permeability in the Shevlin Park Tuff is controlled by crack- or disk-like pore apertures with minimum widths of 0.3 and 7.5 μm. We find that matrix permeability limits compaction over short times, but deformation is then controlled by competition among cooling, compaction, water resorption, and permeable gas escape. These competing processes control the potential for development of overpressure (and secondary explosions) and the degree of welding in the deposit, processes that are applicable to viscous densification of volcanic deposits in general. Further, the general relationships among porosity, permeability, and

  11. Lunar oxygen - The reduction of glass by hydrogen

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Mckay, David S.; Morris, Richard V.

    1992-01-01

    The direct reduction of volcanic glass by hydrogen has been proposed as a method of extracting oxygen from the lunar soil. Experiments using lunar simulant glasses reacted with flowing hydrogen gas have demonstrated reduction at temperatures from 1000 to 1200 C. For melted samples ferrous iron was reduced to the metal, which formed large crystals at the expense of the glass. Samples held below the melting point rapidly devitrified, and iron was formed from submicrometer crystals of ilmenite and pyroxene. Weight losses of 3.6 - 4.5 percent, depending on glass composition, were achieved in 3 hours at 1100 C. A lunar oxygen plant operating at this efficiency and utilizing Apollo 17 orange glass as a feedstock could produce 50 kg of oxygen per ton of soil. The processes of reduction and sintering of lunar soil are synergistic, and could be combined to produce both oxygen and construction material at a moon base.

  12. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. Thermogravimetric analysis (TGA) was carried out on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} to investigate oxygen deficiency ({delta}) of the sample. The TGA was performed in a controlled atmosphere using oxygen, argon, carbon monoxide and carbon dioxide with adjustable gas flow rates. In this experiment, the weight loss and gain of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} was directly measured by TGA. The weight change of the sample was evaluated at between 600 and 1250 C in air or 1000 C as a function of oxygen partial pressure. The oxygen deficiencies calculated from TGA data as a function of oxygen activity and temperature will be estimated and compared with that from neutron diffraction measurement in air. The LSFT and LSFT/CGO membranes were fabricated from the powder obtained from Praxair Specialty Ceramics. The sintered membranes were subjected to microstructure analysis and hardness analysis. The LSFT membrane is composed of fine grains with two kinds of grain morphology. The grain size distribution was characterized using image analysis. In LSFT/CGO membrane a lot of grain pullout was observed from the less dense, porous phase. The hardness of the LSFT and dual phase membranes were studied at various loads. The hardness values obtained from the cross section of the membranes were also compared to that of the values obtained from the surface. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. Measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} as a function of temperature an oxygen partial pressure are reported. Further analysis of the dilatometry data obtained previously is presented. A series of isotope transients

  13. Oxygen-for-Sulfur Switching in the Gas Phase: Reactions of Al and Si Oxyanions with H2S

    SciTech Connect

    Groenewold, Gary Steven; Hodges, Brittany DM; Scott, Jill Rennee; Gianotto, Anita Kay; Appelhans, Anthony David; Kessinger, Glen Frank; Wright, J. B.

    2001-03-01

    Gas-phase Si and Al oxyanions were formed by particle bombardment, isolated by mass, and then reacted with H{sub 2}S in an ion trap secondary ion mass spectrometer (IT-SIMS). The reactions proceeded by different reaction pathways depending on whether the oxyanions were even- or odd-electron species. The radical anion SiO{sub 2}{sm_bullet}{sup -} reacted with H{sub 2}S by abstracting a {sm_bullet}SH radical to form the even-electron SiO{sub 2}SH{sup -}. Once formed, the even electron SiO{sub 2}SH{sup -} reacted with a second H{sub 2}S molecule by O-for-S exchange to form SiOS{sub 2}H{sup -}. The radical anion SiO{sub 3}{sm_bullet}{sup -} abstracted an {sm_bullet}H radical from H{sub 2}S to form even-electron SiO{sub 3}H{sup -}, which then underwent two consecutive O-for-S exchange reactions with H{sub 2}S to form SiO{sub 2}SH{sup -} and SiOS{sub 2}H{sup -}. For the reactions of the even-electron anion AlO{sub 2}{sup -}, the products of two consecutive O-for-S exchange reactions with H{sub 2}S were AlOS{sup -} and AlS{sub 2}{sup -}. The radical abstraction reactions and the O-for-S exchange reactions of SiO3H{sup -}, AlO{sub 2}{sup -}, and AlOS{sup -} were efficient in the 30-50% range. The efficiency of the O-for-S exchange reaction of SiO{sub 2}SH{sup -} (producing SiOS{sub 2}H{sup -}) was substantially less efficient at 8%.

  14. Singlet oxygen O2(a1Δg) formation via UV-excitation of isoprene-oxygen C5H8-O2 encounter complexes in gas phase

    NASA Astrophysics Data System (ADS)

    Pyryaeva, Alexandra P.; Goldort, Veniamin G.; Kochubei, Sergei A.; Baklanov, Alexey V.

    2014-08-01

    Photogeneration of singlet oxygen O2(a1Δg) resulted from photoexcitation at 248 and 266 nm of isoprene-oxygen mixtures at elevated oxygen pressure has been investigated. Pulse energy and oxygen pressure dependence of the singlet oxygen yield indicate one-quantum photoexcitation of the encounter complex isoprene-oxygen C5H8-O2 as a source of O2(a1Δg). Suggested mechanism of O2(a1Δg) photogeneration involves direct excitation of complex with simultaneous change of both partner spins like that observed in van der Waals complex C5H8-O2 [Vidma et al., J. Chem. Phys. 137 (2012) 054305]. Other supposed pathways involve collision-induced photogeneration of Herzberg III state O2(A'3Δg) or triplet isoprene as the intermediates.

  15. The history of extracorporeal oxygenators.

    PubMed

    Lim, M W

    2006-10-01

    Extracorporeal oxygenators are artificial devices that substitute for anatomical lungs by delivering oxygen to, and extracting carbon dioxide from, blood. They were first conceptualised by the English scientist Robert Hooke (1635-1703) and developed into practical extracorporeal oxygenators by French and German experimental physiologists in the 19th century. Indeed, most of the extracorporeal oxygenators used until the late 1970s were derived from von Schroder's 1882 bubble oxygenator and Frey and Gruber's 1885 film oxygenator. As there is no intervening barrier between blood and oxygen, these are called 'direct contact' oxygenators; they contributed significantly to the development and practice of cardiac surgery till the 1980s. Membrane extracorporeal oxygenators introduce a gas-permeable interface between blood and oxygen. This greatly decreased the blood trauma of direct-contact extracorporeal oxygenators, and enabled extracorporeal oxygenators to be used in longer-term applications such as the intensive therapy of respiratory distress syndrome; this was demonstrably beneficial for neonates but less so for older patients. Much work since the 1960s focused on overcoming the gas exchange handicap of the membrane barrier, leading to the development of high-performance microporous hollow-fibre oxygenators that eventually replaced direct-contact oxygenators in cardiac theatres. PMID:16978315

  16. Electron Transfer Reduction of the Diazirine Ring in Gas-Phase Peptide Ions. On the Peculiar Loss of [NH4O] from Photoleucine

    NASA Astrophysics Data System (ADS)

    Marek, Aleš; Shaffer, Christopher J.; Pepin, Robert; Slováková, Kristina; Laszlo, Kenneth J.; Bush, Matthew F.; Tureček, František

    2015-03-01

    Electron transfer to gas-phase peptide ions with diazirine-containing amino acid residue photoleucine (L*) triggers diazirine ring reduction followed by cascades of residue-specific radical reactions. Upon electron transfer, substantial fractions of (GL*GGR +2H)+● cation-radicals undergo elimination of [NH4O] radicals and N2H2 molecules from the side chain. The side-chain dissociations are particularly prominent on collisional activation of long-lived (GL*GGR +2H)+● cation-radicals formed by electron transfer dissociation of noncovalent peptide-18-crown-6-ether ion complexes. The ion dissociation products were characterized by multistage tandem mass spectrometry (MSn) and ion mobility measurements. The elimination of [NH4O] was elucidated with the help of 2H, 15 N, and 18O-labeled peptide ions and found to specifically involve the amide oxygen of the N-terminal residue. The structures, energies, and electronic states of the peptide radical species were elucidated by a combination of near-UV photodissociation experiments and electron structure calculations combining ab initio and density functional theory methods. Electron transfer reaching the ground electronic states of charge reduced (GL*GGR +2H)+● cation-radicals was found to reduce the diazirine ring. In contrast, backbone N - Cα bond dissociations that represent a 60%-75% majority of all dissociations because of electron transfer are predicted to occur from excited electronic states.

  17. N2 Gas Flushing Alleviates the Loss of Bacterial Diversity and Inhibits Psychrotrophic Pseudomonas during the Cold Storage of Bovine Raw Milk.

    PubMed

    Gschwendtner, Silvia; Alatossava, Tapani; Kublik, Susanne; Fuka, Mirna Mrkonjić; Schloter, Michael; Munsch-Alatossava, Patricia

    2016-01-01

    The quality and safety of raw milk still remains a worldwide challenge. Culture-dependent methods indicated that the continuous N2 gas-flushing of raw milk reduced the bacterial growth during cold storage by up to four orders of magnitude, compared to cold storage alone. This study investigated the influence of N2 gas-flushing on bacterial diversity in bovine raw-milk samples, that were either cold stored at 6°C or additionally flushed with pure N2 for up to one week. Next-generation sequencing (NGS) of the V1-V2 hypervariable regions of 16S rRNA genes, derived from amplified cDNA, which was obtained from RNA directly isolated from raw-milk samples, was performed. The reads, which were clustered into 2448 operational taxonomic units (OTUs), were phylogenetically classified. Our data revealed a drastic reduction in the diversity of OTUs in raw milk during cold storage at 6°C at 97% similarity level; but, the N2-flushing treatment alleviated this reduction and substantially limited the loss of bacterial diversity during the same cold-storage period. Compared to cold-stored milk, the initial raw-milk samples contained less Proteobacteria (mainly Pseudomonadaceae, Moraxellaceae and Enterobacteriaceae) but more Firmicutes (mainly Ruminococcaceaea, Lachnospiraceae and Oscillospiraceaea) and Bacteroidetes (mainly Bacteroidales). Significant differences between cold-stored and additionally N2-flushed milk were mainly related to higher levels of Pseudomononadaceae (including the genera Pseudomonas and Acinetobacter) in cold-stored milk samples; furthermore, rare taxa were better preserved by the N2 gas flushing compared to the cold storage alone. No major changes in bacterial composition with time were found regarding the distribution of the major 9 OTUs, that dominated the Pseudomonas genus in N2-flushed or non-flushed milk samples, other than an intriguing predominance of bacteria related to P. veronii. Overall, this study established that neither bacteria causing milk

  18. N2 Gas Flushing Alleviates the Loss of Bacterial Diversity and Inhibits Psychrotrophic Pseudomonas during the Cold Storage of Bovine Raw Milk

    PubMed Central

    Kublik, Susanne; Fuka, Mirna Mrkonjić; Schloter, Michael; Munsch-Alatossava, Patricia

    2016-01-01

    The quality and safety of raw milk still remains a worldwide challenge. Culture-dependent methods indicated that the continuous N2 gas-flushing of raw milk reduced the bacterial growth during cold storage by up to four orders of magnitude, compared to cold storage alone. This study investigated the influence of N2 gas-flushing on bacterial diversity in bovine raw-milk samples, that were either cold stored at 6°C or additionally flushed with pure N2 for up to one week. Next-generation sequencing (NGS) of the V1-V2 hypervariable regions of 16S rRNA genes, derived from amplified cDNA, which was obtained from RNA directly isolated from raw-milk samples, was performed. The reads, which were clustered into 2448 operational taxonomic units (OTUs), were phylogenetically classified. Our data revealed a drastic reduction in the diversity of OTUs in raw milk during cold storage at 6°C at 97% similarity level; but, the N2-flushing treatment alleviated this reduction and substantially limited the loss of bacterial diversity during the same cold-storage period. Compared to cold-stored milk, the initial raw-milk samples contained less Proteobacteria (mainly Pseudomonadaceae, Moraxellaceae and Enterobacteriaceae) but more Firmicutes (mainly Ruminococcaceaea, Lachnospiraceae and Oscillospiraceaea) and Bacteroidetes (mainly Bacteroidales). Significant differences between cold-stored and additionally N2-flushed milk were mainly related to higher levels of Pseudomononadaceae (including the genera Pseudomonas and Acinetobacter) in cold-stored milk samples; furthermore, rare taxa were better preserved by the N2 gas flushing compared to the cold storage alone. No major changes in bacterial composition with time were found regarding the distribution of the major 9 OTUs, that dominated the Pseudomonas genus in N2-flushed or non-flushed milk samples, other than an intriguing predominance of bacteria related to P. veronii. Overall, this study established that neither bacteria causing milk

  19. Determination of local concentration of H{sub 2}O molecules and gas temperature in the process of hydrogen - oxygen gas mixture heating by means of linear and nonlinear laser spectroscopy

    SciTech Connect

    Kozlov, D N; Kobtsev, V D; Stel'makh, O M; Smirnov, Valery V; Stepanov, E V

    2013-01-31

    Employing the methods of linear absorption spectroscopy and nonlinear four-wave mixing spectroscopy using laserinduced gratings we have simultaneously measured the local concentrations of H{sub 2}O molecules and the gas temperature in the process of the H{sub 2} - O{sub 2} mixture heating. During the measurements of the deactivation rates of pulsed-laser excited singlet oxygen O{sub 2} (b {sup 1}{Sigma}{sup +}{sub g}) in collisions with H{sub 2} in the range 294 - 850 K, the joint use of the two methods made it possible to determine the degree of hydrogen oxidation at a given temperature. As the mixture is heated, H{sub 2}O molecules are formed by 'dark' reactions of H{sub 2} with O{sub 2} in the ground state. The experiments have shown that the measurements of tunable diode laser radiation absorption along an optical path through the inhomogeneously heated gas mixture in a cell allows high-accuracy determination of the local H{sub 2}O concentration in the O{sub 2} laser excitation volume, if the gas temperature in this volume is known. When studying the collisional deactivation of O{sub 2} (b {sup 1}{Sigma}{sup +}{sub g}) molecules, the necessary measurements of the local temperature can be implemented using laser-induced gratings, arising due to spatially periodic excitation of O{sub 2} (X{sup 3}{Sigma}{sup -}{sub g}) molecules to the b {sup 1}{Sigma}{sup +}{sub g} state by radiation of the pump laser of the four-wave mixing spectrometer. (laser spectroscopy)

  20. Gas hydrates (clathrates) causing pore-water freshening and oxygen isotope fractionation in deep-water sedimentary sections of terrigenous continental margins

    USGS Publications Warehouse

    Hesse, R.; Harrison, W.E.

    1981-01-01

    The occurrence of gas hydrates in deep-water sections of the continental margins predicted from anomalous acoustic reflectors on seismic profiles has been confirmed by recent deep-sea drilling results. On the Pacific continental slope off Guatemala gas hydrates were brought up for the first time from two holes (497, 498A) drilled during Leg 67 of the DSDP in water depths of 2360 and 5500 m, respectively. The hydrates occur in organic matter-rich Pleistocene to Miocene terrigenous sediments. In the hydrate-bearing zone a marked decrease in interstitial water chlorinities was observed starting at about 10-20 m subbottom depth. Pore waters at the bottom of the holes (near 400 m subbottom) have as little as half the chlorinity of seawater (i.e. 9???). Similar, but less pronounced, trends were observed during previous legs of the DSDP in other hydrate-prone segments of the continental margins where recharge of fresh water from the continent can be excluded (e.g. Leg 11). The crystallization of hydrates, like ice, excludes salt ions from the crystal structure. During burial the dissolved salts are separated from the solids. Subsidence results in a downward motion of the solids (including hydrates) relative to the pore fluids. Thawing of hydrates during recovery releases fresh water which is remixed with the pore fluid not involved in hydrate formation. The volume of the latter decreases downhole thus causing downward decreasing salinity (chlorinity). Hydrate formation is responsible for oxygen isotope fractionation with 18O-enrichment in the hydrate explaining increasingly more positive ??18O values in the pore fluids recovered (after hydrate dissociation) with depth. ?? 1981.

  1. A ground-based radio frequency inductively coupled plasma apparatus for atomic oxygen simulation in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Huang, Yongxian; Tian, Xiubo; Yang, Shiqin; Chu, Paul K.

    2007-10-01

    A radio frequency (rf) inductively coupled plasma apparatus has been developed to simulate the atomic oxygen environment encountered in low Earth orbit (LEO). Basing on the novel design, the apparatus can achieve stable, long lasting operation, pure and high density oxygen plasma beam. Furthermore, the effective atomic oxygen flux can be regulated. The equivalent effective atomic oxygen flux may reach (2.289-2.984)×1016at./cm2s at an oxygen pressure of 1.5Pa and rf power of 400W. The equivalent atomic oxygen flux is about 100 times than that in the LEO environment. The mass loss measured from the polyimide sample changes linearly with the exposure time, while the density of the eroded holes becomes smaller. The erosion mechanism of the polymeric materials by atomic oxygen is complex and involves initial reactions at the gas-surface interface as well as steady-state material removal.

  2. A ground-based radio frequency inductively coupled plasma apparatus for atomic oxygen simulation in low Earth orbit.

    PubMed

    Huang, Yongxian; Tian, Xiubo; Yang, Shiqin; Chu, Paul K

    2007-10-01

    A radio frequency (rf) inductively coupled plasma apparatus has been developed to simulate the atomic oxygen environment encountered in low Earth orbit (LEO). Basing on the novel design, the apparatus can achieve stable, long lasting operation, pure and high density oxygen plasma beam. Furthermore, the effective atomic oxygen flux can be regulated. The equivalent effective atomic oxygen flux may reach (2.289-2.984) x 10(16) at.cm(2) s at an oxygen pressure of 1.5 Pa and rf power of 400 W. The equivalent atomic oxygen flux is about 100 times than that in the LEO environment. The mass loss measured from the polyimide sample changes linearly with the exposure time, while the density of the eroded holes becomes smaller. The erosion mechanism of the polymeric materials by atomic oxygen is complex and involves initial reactions at the gas-surface interface as well as steady-state material removal. PMID:17979410

  3. Orbital transfer vehicle oxygen turbopump technology. Volume 2: Nitrogen and ambient oxygen testing

    NASA Technical Reports Server (NTRS)

    Brannam, R. J.; Buckmann, P. S.; Chen, B. H.; Church, S. J.; Sabiers, R. L.

    1990-01-01

    The testing of a rocket engine oxygen turbopump using high pressure ambient temperature nitrogen and oxygen as the turbine drive gas in separate test series is discussed. The pumped fluid was liquid nitrogen or liquid oxygen. The turbopump (TPA) is designed to operate with 400 F oxygen turbine drive gas which will be demonstrated in a subsequent test series. Following bearing tests, the TPA was finish machined (impeller blading and inlet/outlet ports). Testing started on 15 February 1989 and was successfully concluded on 21 March 1989. Testing started using nitrogen to reduce the ignition hazard during initial TPA checkout. The Hydrostatic Bearing System requires a Bearing Pressurization System. Initial testing used a separate bearing supply to prevent a rubbing start. Two test series were successfully completed with the bearing assist supplied only by the pump second stage output which entailed a rubbing start until pump pressure builds up. The final test series used ambient oxygen drive and no external bearing assist. Total operating time was 2268 seconds. There were 14 starts without bearing assist and operating speeds up to 80,000 rpm were logged. Teardown examination showed some smearing of silverplated bearing surfaces but no exposure of the underlying monel material. There was no evidence of melting or oxidation due to the oxygen exposure. The articulating, self-centering hydrostatic bearing exhibited no bearing load or stability problems. The only anomaly was higher than predicted flow losses which were attributed to a faulty ring seal. The TPA will be refurbished prior to the 400 F oxygen test series but its condition is acceptable, as is, for continued operating. This was a highly successful test program.

  4. A half-century of production-phase greenhouse gas emissions from food loss & waste in the global food supply chain.

    PubMed

    Porter, Stephen D; Reay, David S; Higgins, Peter; Bomberg, Elizabeth

    2016-11-15

    Research on loss & waste of food meant for human consumption (FLW) and its environmental impact typically focuses on a single or small number of commodities in a specific location and point in time. However, it is unclear how trends in global FLW and potential for climate impact have evolved. Here, by utilising the Food and Agriculture Organization's food balance sheet data, we expand upon existing literature. Firstly, we provide a differentiated (by commodity, country and supply chain stage) bottom-up approach; secondly, we conduct a 50-year longitudinal analysis of global FLW and its production-phase greenhouse gas (GHG) emissions; and thirdly, we trace food wastage and its associated emissions through the entire food supply chain. Between 1961 and 2011 the annual amount of FLW by mass grew a factor of three - from 540Mt to 1.6Gt; associated production-phase (GHG) emissions more than tripled (from 680Mt to 2.2Gt CO2e). A 44% increase in global average per capita FLW emissions was also identified - from 225kg CO2e in 1961 to 323kg CO2e in 2011. The regional weighting within this global average changing markedly over time; in 1961 developed countries accounted for 48% of FLW and less than a quarter (24%) in 2011. The largest increases in FLW-associated GHG emissions were from developing economies, specifically China and Latin America - primarily from increasing losses in fruit and vegetables. Over the period examined, cumulatively such emissions added almost 68Gt CO2e to the atmospheric GHG stock; an amount the rough equivalent of two years of emissions from all anthropogenic sources at present rates. Building up from the most granular data available, this study highlights the growth in the climate burden of FLW emissions, and thus the need to improve efficiency in food supply chains to mitigate future emissions. PMID:27432722

  5. Oxygen and hydrogen effects on the chemical vapor deposition of aluminum nitride films

    SciTech Connect

    Aspar, B.; Armas, B.; Combescure, C. ); Figueras, A.; Rodriguez-Clemente, R. ); Mazel, A.; Kihn, Y.; Sevely, J. )

    1993-06-01

    Aluminum nitride has been obtained by chemical vapor deposition using AlCl[sub 3] and NH[sub 3] as precursors. Progressive introduction of N[sub 2]0 in the gas mixture has shown the possibility of inserting oxygen in the AlN lattice. This involves strong changes of surface morphology of the deposit and the formation of less-crystallized materials. When hydrogen is added to the gas mixture, these effects are reduced, Electron energy loss spectroscopy has shown that, in this case, oxygen is mainly concentrated on the external parts of AlN crystals, the structure of which has been found consistent with the wurtzite structure.

  6. 41 CFR 50-204.67 - Oxygen.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 1 2012-07-01 2009-07-01 true Oxygen. 50-204.67 Section..., Vapors, Fumes, Dusts, and Mists § 50-204.67 Oxygen. The in-plant transfer, handling, storage, and utilization of oxygen as a liquid or a compressed gas shall be in accordance with Compressed Gas...

  7. 41 CFR 50-204.67 - Oxygen.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Oxygen. 50-204.67 Section..., Vapors, Fumes, Dusts, and Mists § 50-204.67 Oxygen. The in-plant transfer, handling, storage, and utilization of oxygen as a liquid or a compressed gas shall be in accordance with Compressed Gas...

  8. 41 CFR 50-204.67 - Oxygen.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 1 2014-07-01 2014-07-01 false Oxygen. 50-204.67..., Vapors, Fumes, Dusts, and Mists § 50-204.67 Oxygen. The in-plant transfer, handling, storage, and utilization of oxygen as a liquid or a compressed gas shall be in accordance with Compressed Gas...

  9. 41 CFR 50-204.67 - Oxygen.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 1 2013-07-01 2013-07-01 false Oxygen. 50-204.67..., Vapors, Fumes, Dusts, and Mists § 50-204.67 Oxygen. The in-plant transfer, handling, storage, and utilization of oxygen as a liquid or a compressed gas shall be in accordance with Compressed Gas...

  10. 41 CFR 50-204.67 - Oxygen.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 1 2011-07-01 2009-07-01 true Oxygen. 50-204.67 Section..., Vapors, Fumes, Dusts, and Mists § 50-204.67 Oxygen. The in-plant transfer, handling, storage, and utilization of oxygen as a liquid or a compressed gas shall be in accordance with Compressed Gas...

  11. [THE STUDY OF THE EFFECTS OF ANXYOLYTIC, ANTIOXIDANT, IMMUNOCORRECTOR AND HYPERBARIC OXYGENATION ON THE DYNAMICS OF MAIN BLOOD GAS AND ELECTROLYTE INDICES AND BEHAVIORAL RESPONSE IN EXPERIMENTAL STRESS MODEL].

    PubMed

    Govsh, E V; Podsevatkin, V G; Blinov, D S; Kiryukhina, S V; Podsevatkina, S V; Bochkareva, N V

    2016-01-01

    Experiments on the model of immobilization stress in albino mice showed that a combination of mexidol, thymogen, and hyperbaric oxygenation reduced adverse effects of diazepam on behavioral response of animals in the black-and-white chamber and elevated cross maze tests and led to optimization of the blood gas composition as manifested by increased oxygen tension, normalization of the partial pressure of carbon dioxide, and restoration of the acid-base balance and blood bicarbonate level. The proposed combined treatment can be recommended for the treatment of patients with stress-induced pathology. PMID:27455576

  12. Hyperbaric Oxygen Therapy Registry

    ClinicalTrials.gov

    2016-05-18

    Air or Gas Embolism; Carbon Monoxide Poisoning; Clostridial Myositis and Myonecrosis (Gas Gangrene); Crush Injury, Compartment Syndrome & Other Acute Traumatic Ischemias; Decompression Sickness; Peripheral Arterial Insufficiency and Central Retinal Artery Occlusion; Severe Anemia; Intracranial Abscess; Necrotizing Soft Tissue Infections; Osteomyelitis (Refractory); Delayed Radiation Injury (Soft Tissue and Bony Necrosis); Compromised Grafts and Flaps; Acute Thermal Burn Injury; Idiopathic Sudden Sensorineural Hearing Loss

  13. Seven-Day Mortality Can Be Predicted in Medical Patients by Blood Pressure, Age, Respiratory Rate, Loss of Independence, and Peripheral Oxygen Saturation (the PARIS Score): A Prospective Cohort Study with External Validation

    PubMed Central

    Brabrand, Mikkel; Lassen, Annmarie Touborg; Knudsen, Torben; Hallas, Jesper

    2015-01-01

    Background Most existing risk stratification systems predicting mortality in emergency departments or admission units are complex in clinical use or have not been validated to a level where use is considered appropriate. We aimed to develop and validate a simple system that predicts seven-day mortality of acutely admitted medical patients using routinely collected variables obtained within the first minutes after arrival. Methods and Findings This observational prospective cohort study used three independent cohorts at the medical admission units at a regional teaching hospital and a tertiary university hospital and included all adult (≥15 years) patients. Multivariable logistic regression analysis was used to identify the clinical variables that best predicted the endpoint. From this, we developed a simplified model that can be calculated without specialized tools or loss of predictive ability. The outcome was defined as seven-day all-cause mortality. 76 patients (2.5%) met the endpoint in the development cohort, 57 (2.0%) in the first validation cohort, and 111 (4.3%) in the second. Systolic blood Pressure, Age, Respiratory rate, loss of Independence, and peripheral oxygen Saturation were associated with the endpoint (full model). Based on this, we developed a simple score (range 0–5), ie, the PARIS score, by dichotomizing the variables. The ability to identify patients at increased risk (discriminatory power and calibration) was excellent for all three cohorts using both models. For patients with a PARIS score ≥3, sensitivity was 62.5–74.0%, specificity 85.9–91.1%, positive predictive value 11.2–17.5%, and negative predictive value 98.3–99.3%. Patients with a score ≤1 had a low mortality (≤1%); with 2, intermediate mortality (2–5%); and ≥3, high mortality (≥10%). Conclusions Seven-day mortality can be predicted upon admission with high sensitivity and specificity and excellent negative predictive values. PMID:25867881

  14. Assessment of tissue oxygenation.

    PubMed

    Robertson, P W; Hart, B B

    1999-06-01

    A continuous supply of oxygen to all tissues is necessary for the efficient production of ATP, and this supply is considered sufficient when aerobic metabolism is maintained. Nonhealing wounds, necrotizing infections, radiation-induced necrosis, crush injury, decompression illness, and CO poisoning all exhibit impaired tissue oxygenation. The need for efficacy of HBO therapy in such conditions is in part determined by the prevailing state of tissue oxygen supply and demand. The methods currently available or under development for assessing the adequacy of tissue oxygenation include blood gas analysis, transcutaneous oxygen measurement, gastric tonometry, pulse oximetry, near-infrared spectroscopy, functional MR imaging, MR spectroscopy, electron paramagnetic resonance, positron emission tomography, and single photon emission computed tomography. The clinical and experimental applications of these methods are discussed and emphasis is placed on their role in hyperbaric medicine. PMID:10333450

  15. Make Liquid Oxygen in Your Class

    ERIC Educational Resources Information Center

    French, M. M. J.; Hibbert, Michael

    2010-01-01

    Oxygen is one of the component gases of air at room temperature, making up around 20% of the atmosphere. But can oxygen be liquified? This article details a method for making small amounts of liquid oxygen in the classroom if there is no access to a cylinder of compressed oxygen gas, and two methods for identifying the fact that it is liquid…

  16. Comparison of three lines of broilers differing in ascites susceptibility or growth rate. 2. Egg weight loss, gas pressures, embryonic heat production, and physiological hormone levels.

    PubMed

    De Smit, L; Tona, K; Bruggeman, V; Onagbesan, O; Hassanzadeh, M; Arckens, L; Decuypere, E

    2005-09-01

    Ascites is a metabolic disorder that accounts for over 25% of overall mortality in the broiler industry. This disorder is manifested between wk 5 and 6 posthatch, but there are previous indications that predisposition may be identified during embryonic development. In this current study, we determined embryonic physiological and metabolic parameters that may be associated with ascites predisposition. For this purpose, we used broiler eggs from 3 lines that differed in ascites sensitivity. These included an ascites-sensitive dam line (DAS), an ascites-resistant dam line (DAR), and an ascites-sensitive sire line (SASL). Eggs were incubated for 21 d under standard conditions. The following parameters were measured during incubation: egg weights at setting, egg weight losses at 18 d, embryo body weights and embryo heart weights throughout development, air cell partial gas pressures (pCO2 and pO2) levels at d 18 and at internal pipping (IP); plasma triiodothyronine, thyroxine, and corticosterone levels at d 18, IP, and hatch; heat production from d 17 until hatch, hematocrit values at hatch, and posthatch growth rate to 7 d along with hematocrit values. The data obtained revealed that selection for ascites sensitivity or rapid growth rate had no consistent influence on some of these parameters such that they could be wholly associated with ascites sensitivity for predictive purposes. Whereas differences in embryonic developmental patterns were apparent throughout embryonic development, these differences in physiological and metabolic parameters may be due partly to genetic differences unrelated to ascites sensitivity. PMID:16206567

  17. Phenotypic plasticity of gas exchange pattern and water loss in Scarabaeus spretus (Coleoptera: Scarabaeidae): deconstructing the basis for metabolic rate variation.

    PubMed

    Terblanche, John S; Clusella-Trullas, Susana; Chown, Steven L

    2010-09-01

    Investigation of gas exchange patterns and modulation of metabolism provide insight into metabolic control systems and evolution in diverse terrestrial environments. Variation in metabolic rate in response to environmental conditions has been explained largely in the context of two contrasting hypotheses, namely metabolic depression in response to stressful or resource-(e.g. water) limited conditions, or elevation of metabolism at low temperatures to sustain life in extreme conditions. To deconstruct the basis for metabolic rate changes in response to temperature variation, here we undertake a full factorial study investigating the longer- and short-term effects of temperature exposure on gas exchange patterns. We examined responses of traits of gas exchange [standard metabolic rate (SMR); discontinuous gas exchange (DGE) cycle frequency; cuticular, respiratory and total water loss rate (WLR)] to elucidate the magnitude and form of plastic responses in the dung beetle, Scarabaeus spretus. Results showed that short- and longer-term temperature variation generally have significant effects on SMR and WLR. Overall, acclimation to increased temperature led to a decline in SMR (from 0.071+/-0.004 ml CO(2) h(-1) in 15 degrees C-acclimated beetles to 0.039+/-0.004 ml CO(2) h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) modulated by reduced DGE frequency (15 degrees C acclimation: 0.554+/-0.027 mHz, 20 degrees C acclimation: 0.257+/-0.030 mHz, 25 degrees C acclimation: 0.208+/-0.027 mHz recorded at 20 degrees C), reduced cuticular WLRs (from 1.058+/-0.537 mg h(-1) in 15 degrees C-acclimated beetles to 0.900+/-0.400 mg h(-1) in 25 degrees C-acclimated beetles measured at 20 degrees C) and reduced total WLR (from 4.2+/-0.5 mg h(-1) in 15 degrees C-acclimated beetles to 3.1+/-0.5 mg h(-1) in 25 degrees C-acclimated beetles measured at 25 degrees C). Respiratory WLR was reduced from 2.25+/-0.40 mg h(-1) in 15 degrees C-acclimated beetles to 1.60+/-0.40 mg h

  18. Oxygen Transport Membranes

    SciTech Connect

    S. Bandopadhyay

    2008-08-30

    The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

  19. Oceanography: Coastal oceanic nitrogen loss

    NASA Astrophysics Data System (ADS)

    Thamdrup, Bo

    2013-03-01

    Oxygen minimum zones crop up along the eastern boundaries of ocean basins in the low latitudes. A survey of the oxygen minimum zone in the eastern South Pacific points to the coastal zone as a hotspot for anammox-driven marine nitrogen loss.

  20. Gas-phase reactions of molecular oxygen with uranyl(V) anionic complexes-synthesis and characterization of new superoxides of uranyl(VI).

    PubMed

    Lucena, Ana F; Carretas, José M; Marçalo, Joaquim; Michelini, Maria C; Gong, Yu; Gibson, John K

    2015-04-16

    Gas-phase complexes of uranyl(V) ligated to anions X(-) (X = F, Cl, Br, I, OH, NO3, ClO4, HCO2, CH3CO2, CF3CO2, CH3COS, NCS, N3), [UO2X2](-), were produced by electrospray ionization and reacted with O2 in a quadrupole ion trap mass spectrometer to form uranyl(VI) anionic complexes, [UO2X2(O2)](-), comprising a superoxo ligand. The comparative rates for the oxidation reactions were measured, ranging from relatively fast [UO2(OH)2](-) to slow [UO2I2](-). The reaction rates of [UO2X2](-) ions containing polyatomic ligands were significantly faster than those containing the monatomic halogens, which can be attributed to the greater number of vibrational degrees of freedom in the polyatomic ligands to dissipate the energy of the initial O2-association complexes. The effect of the basicity of the X(-) ligands was also apparent in the relative rates for O2 addition, with a general correlation between increasing ligand basicity and O2-addition efficiency for polyatomic ligands. Collision-induced dissociation of the superoxo complexes showed in all cases loss of O2 to form the [UO2X2](-) anions, indicating weaker binding of the O2(-) ligand compared to the X(-) ligands. Density functional theory computations of the structures and energetics of selected species are in accord with the experimental observations. PMID:25807358

  1. Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE): Lunar Advanced Volatile Analysis (LAVA) Capillary Fluid Dynamic Restriction Effects on Gas Chromatography

    NASA Technical Reports Server (NTRS)

    Gonzalez, Marianne; Quinn, Jacqueline; Captain, Janine; Santiago-Bond, Josephine; Starr, Stanley

    2015-01-01

    The Resource Prospector (RP) mission with the Regolith and Environment Science and Oxygen Lunar Volatile Extraction (RESOLVE) payload aims to show the presence of water in lunar regolith, and establish a proving ground for NASAs mission to Mars. One of the analysis is performed by the Lunar Advanced Volatiles Analysis (LAVA) subsystem, which consists of a fluid network that facilitates the transport of volatile samples to a gas chromatograph and mass spectrometer (GC-MS) instrument. The understanding of fluid dynamics directed from the GC to the MS is important due to the influence of flow rates and pressures that affect the accuracy of and prevent the damage to the overall GC-MS instrument. The micro-scale capillary fluid network within the GC alone has various lengths and inner-diameters; therefore, determination of pressure differentials and flow rates are difficult to model computationally, with additional complexity from the vacuum conditions in space and lack of a lunar atmosphere. A series of tests were performed on an experimental set-up of the system where the inner diameters of the GC transfer line connecting to the MS were varied. The effect on chromatography readings were also studied by applying these lines onto a GC instrument. It was found that a smaller inner diameter transfer line resulted in a lower flow rate, as well as a lower pressure differential across the thermal conductivity detector (TCD) unit of the GC and a negligible pressure drop across the mock-up capillary column. The chromatography was affected with longer retention times and broader peak integrations. It was concluded that a 0.050 mm inner diameter line still proved most suitable for the systems flow rate preferences. In addition, it was evident that this small transfer line portrayed some expense to GC signal characteristics and the wait time for steady-state operation.

  2. Characterization of CeO2-Supported Cu-Pd Bimetallic Catalyst for the Oxygen-Assisted Water-Gas Shift Reaction

    SciTech Connect

    Fox, Elise; Velu, Subramani; Engelhard, Mark H.; Chin, Ya-Huei; Miller, Jeffrey T.; Kropf, Jeremy; Song, Chunshan

    2008-12-10

    This study was focused to investigate the roles of Cu and Pd in CuPd/CeO2 bimetallic catalysts containing 20-30 wt% Cu and 0.5-1 wt% Pd used in the oxygen-assisted water-gas shift (OWGS) reaction employing a combined bulk and surface characterization techniques such as XRD, TPR, CO chemisorption, and in-situ XPS. The catalytic activity for CO conversion and the stability of catalyst during on-stream operation increased by the addition of Cu to Pd/CeO2 or Pd to Cu/CeO2 monometallic catalysts, especially when the OWGS reaction was performed under low temperatures, below 200oC. The bimetallic catalyst after leaching with nitric acid retained about 60% of its original activity. The TPR of monometallic Cu/CeO2 showed reduction of CuO supported on CeO2 in two distinct regions, around 150 and 250oC. The high temperature peak disappeared and reduction occurred in a single step around 150oC upon Pd addition. The Pd dispersion decreased from 38.5% for Pd/CeO2 to below 1% for CuPd/CeO2 bimetallic catalyst. In-situ XPS studies showed a shift in Cu 2p peaks toward lower binding energy (BE) with concommitant shift in the Pd 3d peaks toward higher BE. Addition of Pd decreased the surface Cu concentration while the concentration of Pd remained unaltered. All these observations indicated the formation of Cu-Pd surface alloy. The valence band XP spectra collected below 10 eV corroborated the core level XP spectra and indicated that Cu is mainly involved in the catalytic reaction. The improved catalytic activity and stability of CuPd/CeO2 bimetallic catalyst was attributed to the alloy formation.

  3. Gas treating process

    SciTech Connect

    Hass, R.H.

    1990-01-09

    This patent describes a process for preventing oxygen from deactivating a catalyst susceptible to deactivation by oxygen. It comprises: scavenging oxygen contained in a feed gas stream comprising carbon monoxide and water vapor as reactant gases in the presence of an oxidation catalyst under conditions which remove essentially all of the oxygen by reaction with hydrogen sulfide and contacting the resultant gas stream, containing the reactants but essentially free of oxygen, with a catalyst susceptible to deactivation by oxygen but active for the water gas shift reaction. The contacting being under conditions resulting in the conversion of at least some of the carbon monoxide and water vapor to hydrogen and carbon dioxide.

  4. The effects of the pressure and the oxygen content of the sputtering gas on the structure and the properties of zinc oxy-nitride thin films deposited by reactive sputtering of zinc

    NASA Astrophysics Data System (ADS)

    Jiang, Nanke; Georgiev, Daniel G.; Jayatissa, Ahalapitiya H.

    2013-02-01

    Zinc nitride and oxy-nitride thin films were prepared by reactive magnetron rf sputtering of zinc in either nitrogen-argon or nitrogen-argon-oxygen ambient. The effects of varying the total sputtering pressure and the oxygen fraction in the total sputtering gas mixture on the microstructure, electrical and optical properties were investigated. With increasing the sputtering pressure, the dominant phase comprising the film material changes from the crystalline zinc nitride phase to crystalline zinc oxide. The characteristic pressure, at which this change in the dominant phase is observed, decreases with the increase of the oxygen fraction in the total sputtering gas mixture. The increase of the oxygen content in the films (from 5 at.% to a maximum of 40 at.%) and the downward shift in the optical absorption edge (from 920 to 400 nm), combined with the x-ray diffraction data, support these observations, indicating the controllable fabrication of an oxy-nitride film material. Correlations between the films’ fabrication conditions, including post-deposition annealing, their structure and composition, and their electrical properties are examined as well.

  5. Measurement of respiratory water loss in newborn lambs.

    PubMed

    Hammarlund, K; Riesenfeld, T; Sedin, G

    1986-05-01

    A flow-through system for measurement of respiratory water loss, providing data on oxygen consumption and carbon dioxide production, is described. The system uses a mass spectrometer, specially equipped with a water channel, for analysis of gas concentrations. To avoid condensation of water vapour, the tubing in the flow-through system is heated. The method was tested by evaporating known amounts of water, and was found to be very accurate with a correlation coefficient of 0.999. Measurements were made in 10 fullterm lambs of varying postnatal age (4-15 days) and a mean respiratory water loss (RWL) of 11.7 mg kg-1 min-1 was found at rest. The RWL decreased with increasing postnatal age, as did oxygen consumption. The RWL at rest was influenced by the ambient relative humidity, with higher values at lower humidities. PMID:3088913

  6. Oxygen Therapy

    MedlinePlus

    ... 85-95% pure oxygen. The concentrator runs on electricity or a battery. A concentrator for home usually ... systems deliver 100% oxygen, and do not require electricity. A small canister can be filled from the ...

  7. Impact of oxygen injection on CH4 and N2O emissions from rising main sewers.

    PubMed

    Ganigué, Ramon; Yuan, Zhiguo

    2014-11-01

    Oxygen injection is a commonly used mitigation strategy for sulfide control in sewers. Methane, a potent greenhouse gas, is also produced in sewers. Oxygen injection may reduce methane generation/emission, but could potentially lead to N2O production due to the development of a nitrifying microbial community. The impact of oxygen dosing for sulfide control in sewers on CH4 and N2O production was assessed in this study in laboratory sewer reactors. Results showed that oxygen injection is able to reduce CH4 formation in sewers, although full control of CH4 was not achieved, likely due to partial oxygen penetration into sewer biofilm. The experimental results also revealed a nitrogen loss of around 5 mN/L. However, no significant N2O accumulation was detected. PMID:24975803

  8. Iodine losses during Winkler titrations

    NASA Astrophysics Data System (ADS)

    Knapp, George P.; Stalcup, Marvel C.; Stanley, Robert J.

    1991-01-01

    An experiment designed to measure iodine loss during the aliquot version of the Winkler titration for dissolved oxygen in seawater shows that 0.01-0.03 ml l -1 equivalent oxygen is lost at typical oceanic concentrations in the method presently used. A standardization technique, which mimics that employed during the titration of seawater samples, compensates for this iodine loss throughout the oceanic range. This result, contradicting an earlier report by GREEN and CARRITT (1966, Analyst, 91, 207-208), demonstrates that the whole-bottle method of oxygen titration is not to be preferred over the aliquot method.

  9. Oxygen supplies in disaster management.

    PubMed

    Blakeman, Thomas C; Branson, Richard D

    2013-01-01

    Mass casualty events and disasters, both natural and human-generated, occur frequently around the world and can generate scores of injured or ill victims in need of resources. Of the available medical supplies, oxygen remains the critical consumable resource in disaster management. Strategic management of oxygen supplies in disaster scenarios remains a priority. Hospitals have large supplies of liquid oxygen and a supply of compressed gas oxygen cylinders that allow several days of reserve, but a large influx of patients from a disaster can strain these resources. Most backup liquid oxygen supplies are attached to the main liquid system and supply line. In the event of damage to the main system, the reserve supply is rendered useless. The Strategic National Stockpile supplies medications, medical supplies, and equipment to disaster areas, but it does not supply oxygen. Contracted vendors can deliver oxygen to alternate care facilities in disaster areas, in the form of concentrators, compressed gas cylinders, and liquid oxygen. Planning for oxygen needs following a disaster still presents a substantial challenge, but alternate care facilities have proven to be valuable in relieving pressure from the mass influx of patients into hospitals, especially for those on home oxygen who require only an electrical source to power their oxygen concentrator. PMID:23271827

  10. Oxygen-reducing catalyst layer

    DOEpatents

    O'Brien, Dennis P.; Schmoeckel, Alison K.; Vernstrom, George D.; Atanasoski, Radoslav; Wood, Thomas E.; Yang, Ruizhi; Easton, E. Bradley; Dahn, Jeffrey R.; O'Neill, David G.

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  11. Mass loss

    NASA Technical Reports Server (NTRS)

    Goldberg, Leo

    1987-01-01

    Observational evidence for mass loss from cool stars is reviewed. Spectra line profiles are used for the derivation of mass-loss rates with the aid of the equation of continuity. This equation implies steady mass loss with spherical symmetry. Data from binary stars, Mira variables, and red giants in globular clusters are examined. Silicate emission is discussed as a useful indicator of mass loss in the middle infrared spectra. The use of thermal millimeter-wave radiation, Very Large Array (VLA) measurement of radio emission, and OH/IR masers are discussed as a tool for mass loss measurement. Evidence for nonsteady mass loss is also reviewed.

  12. The effect of irradiation in air or in hyperbaric oxygen on the Fib/T tumor in WHT mice pretreated with a hypoxic gas mixture

    SciTech Connect

    Hendrikse, A.; Blekkenhorst, G. )

    1991-01-01

    The effect of exposing WHT mice bearing the Fib/T tumor to a low-oxygen environment (8, 10, and 15% oxygen) for 48 h or 72 h before irradiation was compared, using an in vitro colony-forming excision assay, to the effect obtained when mice were pretreated with air. The response of the Fib/T tumor to radiation delivered in air was improved both by a 48-h and by a 72-h exposure of the animals to 8, 10, and 15% oxygen. However, the greatest tumor sensitization was achieved when mice were kept in 8% oxygen for 48 h before irradiation. These results are interpreted and discussed in relation to increases in the 2,3-DPG concentration, which were shown to occur when mice were exposed to a reduced oxygen environment. The relative importance of two models proposed to explain these findings is assessed. If mice pretreated with air were irradiated in hyperbaric oxygen, a similar tumor response was observed compared to that when mice were exposed to 8% oxygen for 48 h and then irradiated in air.

  13. Relationship of Exercise, Age, and Gender on Decompression Sickness and Venous Gas Emboli During 2-Hour Oxygen Prebreathe Prior to Hypobaric Exposure

    NASA Technical Reports Server (NTRS)

    Conkin, J.; Gernhardt, M. L.; Foster, P. P.; Pilmanis, A. A.; Butler, B. D.; Beltran, E.; Fife, C. E.; Vann, R. D.; Gerth, W. A.; Loftin, K. C.; Paloski, William H. (Technical Monitor)

    2000-01-01

    We evaluated four 2-hour oxygen prebreathe protocols combining adynamia (non-walking) and 4 different amounts of exercise for potential use with extravehicular activity (EVA) on the International Space Station. Phase I: upper and lower body exercises using dual-cycle ergometry (75% VO2 max for 10 min). Phase 11: same ergometry plus 24 min of light exercise that simulated space suit preparations. Phase III: same 24 min of light exercise but no ergometry, and Phase IV: 56 min of light exercise without ergometry. After 80 min on 100% O2, the subjects breathed 26.5% O2 - 73.5% N2 for 30 min at 10.2 psi. All subjects performed a series of upper body exercises from a recumbent position for 4 hrs at 4.3 psi to simulate EVA work. Venous gas emboli (VGE) were monitored every 12 min using precordial Doppler ultrasound. The 39 female and 126 male exposures were analyzed for correlations between decompression sickness (DCS) or VGE, and risk variables. The duration and quantity of exercise during prebreathe inversely relates to DCS and VGE incidence. The type and distribution of the 19 cases of DCS were similar to historical cases. There was no correlation of age, gender, body mass index, or fitness level with greater incidence of DCS or all VGE. However there were more Grade IV VGE in males > 40 years (10 of 19) than in those =< 40 years (3 of 107), with p<0.01 from Fisher's Exact Chi square The latency time for VGE was longer (103 min +/- 56 SD, n = 15 versus 53 min +/- 31, n =13) when the ergometry occurred about 15 min into the prebreathe than when performed at the start of the prebreathe, but the order of the ergometry did not influence the overall DCS and VGE incidence. An increasing amount of exercise during prebreathes reduced the risk of DCS during subsequent exposures to 4.3 psi. Age, gender, or fitness level did not correlate with the incidence of DCS or VGE (combination of Grades I-IV). However males greater than 40 years had a higher incidence of Grade IV VGE.

  14. THE DETERMINATION OF CORRELATION LINKAGES BETWEEN LEVEL OF REACTIVE OXYGEN SPECIES, CONTENTS OF NEUTROPHILES AND BLOOD GAS COMPOSITION IN EXPERIMENTAL ACUTE LUNG INJURY.

    PubMed

    Marushchak, M; Krynytska, I; Petrenko, N; Klishch, I

    2016-04-01

    Acute lung injury (ALI) remains a major cause of acute respiratory failure and death of patients. Despite the achievements at the current stage in treatment, morbidity and mortality of ALI remain high. However, a deeper understanding of the pathogenetic links of ALI, identifying of the predictors that positively or negatively influence on the course of the syndrome, the correlation between some pathogenetic mechanisms will improve therapeutic strategies for patients with ALI, which makes the actuality of this study. The aim of the research was to detect additional pathogenetic mechanisms of the acute lung injury development in rats based on a comparative analysis of the correlations between the level of reactive oxygen species in blood and bronchoalveolar lavage, contents of neutrophils and blood gas composition. The experiments were performed on 54 white nonlinear mature male rats 200-220g in weight. The animals were divided into 5 groups: the 1st - control group (n=6), the 2nd - animals affected by hydrochloric acid for 2 hours (n=12), the 3rd - animals affected by hydrochloric acid for 6 hours (n=12), the 4th - animals affected by hydrochloric acid for 12 hours (n=12), the 5th - animals affected by hydrochloric acid for 24 hours (n=12). Correlation analysis was performed between all the studied indices. Coefficient of linear correlation (r) and its fidelity (p) was calculated that was accordingly denoted in the tables (correlation matrices). The correlation coefficient was significant at p<0.05. Conducted correlative analysis showed that the level of ROS in neutrophils of blood in rats with modeled ALI had a high negative correlative linkage with pH of arterial blood in 2nd and 3rd experimental groups. Conducted correlative analysis of data in BAL showed that the level of ROS in neutrophils in rats with modeled ALI had a strong positive correlative relationship with the number of white blood cells in 3-rd, 4-th and 5-th experimental groups and positive

  15. Stable carbon and oxygen isotopic analysis of carbon monoxide in soil gas using CF-IRMS by isotope-ratio monitoring of CO

    NASA Astrophysics Data System (ADS)

    Tsunogai, U.; Nakagawa, F.; Komatsu, D. D.; Gamo, T.

    2002-12-01

    We have developed a rapid and simple measurement system for both content and stable isotopic compositions (13C and 18O) of CO, using continuous flow isotope ratio mass spectrometry (CF-IRMS) by simultaneously monitoring the CO+ ion currents at masses 28, 29, and 30. The analytical system consisted sequentially of a sample trapping port (liquid nitrogen temperature silica gel and Molecular sieve 5A), a gas dryer, CO purification column (Molecular sieve 5A), a cryofocusing unit, and a final purification column using a GC capillary. Analytical precision of 0.2 \\permil for 13C and 0.4 \\permil for 18O can be realized for samples that contain as little as 300 pmol CO within 40 minutes for one sample analysis. Analytical blanks associated with the method are less than 1 pmol. The extent of analytical error in δ13C due to mass-independent fractionation of oxygen in natural CO is estimated to be less than 0.3 \\permil. Based on this system, we report herein a kinetic isotopic effect during CO consumption in soil. The observed KIEs are estimated to be \\pm8 \\permil for δ13C and \\pm12 \\permil for δ18O. Two steps must be involved in these KIEs: one is the fractionation during diffusion of CO into the soil pores, while the other is due to actual absorption by the active soil organism. The estimated value resembles with the theoretical maximum KIE for the fractionation during diffusion of CO into the soil pores. In addition, the estimated values are completely different from those for the CO + OH reaction, especially for δ18O, suggesting that the KIE is an useful indicator for distinguishing between these two major sink processes of CO. By estimating the average KIE during soil oxidation of CO through similar KIE measurements at different locations and/or seasons, we can estimate both global and local CO budgets, by balancing CO sources and sinks through the use of δ13C and δ18O of CO.

  16. Hair Loss

    MedlinePlus

    ... may cause hair loss in women. If your hair loss has occurred gradually with advancing age, FOLLICULAR DEGENERATION may be the cause. Post-pregnancy hormone changes usually reverse themselves without any treatment. While follicular degeneration cannot ...

  17. Application of dispersive liquid-liquid microextraction and gas chromatography with mass spectrometry for the determination of oxygenated volatile organic compounds in effluents from the production of petroleum bitumen.

    PubMed

    Boczkaj, Grzegorz; Makoś, Patrycja; Przyjazny, Andrzej

    2016-07-01

    We present a new procedure for the determination of oxygenated volatile organic compounds in samples of postoxidative effluents from the production of petroleum bitumens using dispersive liquid-liquid microextraction and gas chromatography with mass spectrometry. The eight extraction parameters were optimized for 43 oxygenated volatile organic compounds. The detection limits obtained ranged from 0.07 to 0.82 μg/mL for most of the analytes, the precision was good (relative standard deviation below 2.91% at the 5 μg/mL level and 4.75% at the limit of quantification), the recoveries for the majority of compounds varied from 70.6 to 118.9%, and the linear range was wide, which demonstrates the usefulness of the procedure. The developed procedure was used for the determination of oxygenated volatile organic compounds in samples of raw postoxidative effluents and in effluents after chemical treatment. In total, 23 compounds at concentration levels from 0.37 to 32.95 μg/mL were identified in real samples. The same samples were also analyzed in the SCAN mode, which resulted in four more phenol derivatives being identified and tentatively determined. The studies demonstrated the need for monitoring volatile organic compounds content in effluents following various treatments due to the formation of secondary oxygenated volatile organic compounds. PMID:27144480

  18. Comparing the efficiency of supersonic oxygen-iodine laser with different mixing designs

    NASA Astrophysics Data System (ADS)

    Vyskubenko, Boris A.; Adamenkov, A. A.; Bakshin, V. V.; Efremov, V. I.; Ilyin, S. P.; Kolobyanin, Yu. V.; Krukovsky, I. M.; Kudryashov, E. A.; Moiseyev, V. B.

    2003-11-01

    The paper presents experimental studies of supersonic oxygen-iodine laser (OIL) using twisted-flow singlet oxygen generator (SOG) over a wide range of the singlet oxygen pressures and the buffer gas flow rates. The experiments used different designs of the nozzle unit and mixing system for singlet oxygen and iodine gas with the carrier gas (such as nitrogen or helium). For a wide range of the key parameters, the study looked at the efficiency of supersonic OIL with variation of the singlet oxygen pressure. The measurements were made for different positions of the iodine injection plane with respect to the critical cross-section (both in the subsonic part of the nozzle and in the supersonic flow). The gas pressure at the nozzle unit entry was varied from 50 to 250 Torr. The total pressure loss have been found for different mixing designs. Experimental curves are given for energy performance and chemical efficiency of the supersonic OIL as a function of the key parameters. Comparison is made between the calculated and experimental data. For the optimum conditions of OIL operation, chemical efficiency of 25-30% has been achieved.

  19. Appreciating Oxygen

    ERIC Educational Resources Information Center

    Weiss, Hilton M.

    2008-01-01

    Photosynthetic flora and microfauna utilize light from the sun to convert carbon dioxide and water into carbohydrates and oxygen. While these carbohydrates and their derivative hydrocarbons are generally considered to be fuels, it is the thermodynamically energetic oxygen molecule that traps, stores, and provides almost all of the energy that…

  20. Oxygen safety

    MedlinePlus

    ... Watch out for splattering grease. It can catch fire. Keep children with oxygen away from the stove top and oven. Cooking ... under the bed. Keep liquids that may catch fire away from your oxygen. This includes cleaning products that contain oil, grease, ...

  1. Molecular rotational line profiles from oxygen-rich red giant winds

    NASA Technical Reports Server (NTRS)

    Justtanont, K.; Skinner, C. J.; Tielens, A. G. G. M.

    1994-01-01

    We have developed a radiative transfer model of the dust and gas envelopes around late-type stars. The gas kinetic temperature for each star is calculated by solving equations of motion and the energy balance simultaneously. The main processes include viscous heating and adiabatic and radiative cooling. Heating is dominated by viscosity as the grains stream outward through the gas, with some contribution in oxygen-rich stars by near-IR pumping of H2O followed by collisional de-excitation in the inner envelope. For O-rich stars, rotational H2O cooling is a dominant mechanism in the middle part of the envelope, with CO cooling being less significant. We have applied our model to three well-studied oxygen-rich red giant stars. The three stars cover a wide range of mass-loss rates, and hence they have different temperature structures. The derived temperature structures are used in calculating CO line profiles for these objects. Comparison of the dust and gas mass-loss rates suggests that mass-loss rates are not constant during the asymptotic giant branch phase. In particular, the results show that the low CO 1-0 antenna temperatures of OH/IR stars reflect an earlier phase of much lower mass-loss rate.

  2. The Herschel Oxygen Project: Herschel Space Observatory Open Time Key Project

    NASA Technical Reports Server (NTRS)

    Goldsmith, Paul F.

    2008-01-01

    Topics include: Why oxygen and why at submillimeter wavelengths; gas phase chemistry for water, oxygen, and carbon monoxide is relatively simple; molecular oxygen structure; lower rotational levels and transitions of oxygen; oxygen abundance in interstellar clouds; SWAS spectra of terrestrial oxygen; what Herschel offers HOP; key regions for probing oxygen in the dense interstellar medium; HOP sources and strategy; and HOP data and analysis.

  3. Solar heating of common lunar minerals for the production of oxygen

    NASA Technical Reports Server (NTRS)

    Senior, C. L.

    1991-01-01

    The purpose of this work was to demonstrate the feasibility of vapor-phase reduction (pyrolysis) of lunar materials to produce oxygen. Solar furnace experiments were conducted on two common lunar minerals, ilmenite and anorthite. Thermodynamic equilibrium calculations predicted that ilmenite should show a larger pressure increase than anorthite under conditions of the experiments and this was confirmed by the experiments. The measured mass loss of the ilmenite sample was consistent with loss of oxygen by reduction of iron in the liquid phase; this result was also predicted from equilibrium calculations. Based on preliminary experiments and equilibrium calculations, the temperatures needed for pyrolysis are expected to be in the range of 2000 to 2500 K, giving total gas pressures of 0.01 to 1 torr. Bulk regolith can be used as a feedstock without extensive beneficiation. Further, selective condensation of metal-containing species from the gas phase may yield metallic iron and silicon as byproducts from the process.

  4. Single Step Bi-reforming and Oxidative Bi-reforming of Methane (Natural Gas) with Steam and Carbon Dioxide to Metgas (CO-2H2) for Methanol Synthesis: Self-Sufficient Effective and Exclusive Oxygenation of Methane to Methanol with Oxygen.

    PubMed

    Olah, George A; Goeppert, Alain; Czaun, Miklos; Mathew, Thomas; May, Robert B; Prakash, G K Surya

    2015-07-15

    Catalysts based on suitable metal oxide supports, such as NiO/MgO and CoO/MgO, were shown to be active for single step bi-reforming, the combined steam and dry reforming of methane or natural gas with H2O and CO2 exclusively to metgas (CO-2H2) for efficient methanol synthesis. Reactions were carried out in a tubular flow reactor under pressures up to 42 bar at 830-910 °C. Using a CH4 to steam to CO2 ratio of ∼3:2:1 in the gas feed, the H2/CO ratio of 2:1 was achieved, which is desired for subsequent methanol synthesis. The needed 2/1 steam/CO2 feed ratio together with the reaction heat for the endothermic bi-reforming can be conveniently obtained by the complete combustion of a quarter part of the overall used methane (natural gas) with oxygen of the air (oxidative bi-reforming). Complete combustion of a part of methane followed by bi-reforming leads to the production of metgas (H2/CO in 2:1 mol ratio) for self-sufficient exclusive methanol synthesis. The long sought after but elusive efficient and selective oxygenation of methane to methanol is thus achieved in an effective and economic way without any oxidation byproduct formation according to CH4 + 1/2O2 → CH3OH. PMID:26086090

  5. The Anaesthesia Gas Supply System

    PubMed Central

    Das, Sabyasachi; Chattopadhyay, Subhrajyoti; Bose, Payel

    2013-01-01

    The anaesthesia gas supply system is designed to provide a safe, cost-effective and convenient system for the delivery of medical gases at the point of-use. The doctrine of the anaesthesia gas supply system is based on four essential principles: Identity, continuity, adequacy and quality. Knowledge about gas supply system is an integral component of safe anaesthetic practice. Mishaps involving the malfunction or misuse of medical gas supply to operating theatres have cost many lives. The medical gases used in anaesthesia and intensive care are oxygen, nitrous oxide, medical air, entonox, carbon dioxide and heliox. Oxygen is one of the most widely used gases for life-support and respiratory therapy besides anaesthetic procedures. In this article, an effort is made to describe the production, storage and delivery of anaesthetic gases. The design of anaesthesia equipment must take into account the local conditions such as climate, demand and power supply. The operational policy of the gas supply system should have a backup plan to cater to the emergency need of the hospital, in the event of the loss of the primary source of supply. PMID:24249882

  6. Fuel cell serves as oxygen level detector

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Monitoring the oxygen level in the air is accomplished by a fuel cell detector whose voltage output is proportional to the partial pressure of oxygen in the sampled gas. The relationship between output voltage and partial pressure of oxygen can be calibrated.

  7. High Temperature Langasite SAW Oxygen Sensor

    SciTech Connect

    Zheng, Peng; Chin, Tao-Lun; Greve, David; Oppenheim, Irving; Malone, Vanessa; Cao, Limin

    2011-08-01

    High-temperature langasite SAW oxygen sensors using sputtered ZnO as a resistive gas-sensing layer were fabricated and tested. Sensitivity to oxygen gas was observed between 500°C to 700°C, with a sensitivity peak at about 625°C, consistent with the theoretical predictions of the acoustoelectric effect.

  8. Oxygen therapy and intraocular oxygenation.

    PubMed Central

    Jampol, L M

    1987-01-01

    When delivered to the corneal surface of rabbits or monkeys, 100% oxygen can significantly increase the pO2 in the aqueous humor. Under hyperbaric conditions (two atmospheres), an observed rise in the aqueous pO2 in rabbits breathing room air can be increased further by exposing the rabbit cornea to 100% oxygen. The high oxygen levels under hyperbaric conditions are mediated by intravascular and transcorneal delivery of oxygen. The increase in the pO2 levels in the aqueous can prevent sickling of intracameral human erythrocytes containing sickle hemoglobin. Thus, oxygen therapy transcorneally or systemically could potentially be used to treat a sickle cell hyphema. The exposure of rabbit eyes to 100% oxygen at the corneal surface is followed by autoregulation (constriction) of the iris vasculature. We could demonstrate no constriction in the eyes of two normal human volunteers or of four patients with chronic stable rubeosis iridis. Preretinal vitreous pO2 levels can be significantly raised by exposing monkeys to hyperbaric 100% oxygen. This procedure may be of value in treating acute, reversible ischemic inner retinal diseases. Transcorneal or vascular delivery of oxygen to the eye under normobaric or hyperbaric conditions may be effective in treating ischemic diseases of the anterior segment, such as anterior segment necrosis or rubeosis iridis, or ischemic inner retinal diseases. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 B FIGURE 5 C FIGURE 5 A FIGURE 6 PMID:3447339

  9. Outgassing of oxygen from polycarbonate.

    PubMed

    Moon, Sung In; Monson, L; Extrand, C W

    2009-07-01

    A manometric permeation apparatus was used to study the "outgassing" or desorption of oxygen from polycarbonate (PC). A PC film was placed in the apparatus. Both sides were exposed to oxygen until the film was saturated. To simulate inert gas purging of a closed container or "microenvironment", oxygen was pumped from one side of the apparatus to reduce the concentration on that side to nearly zero. Oxygen concentrations on the freshly purged side rose quickly at first but then slowed. Eventually, a steady state was established and oxygen concentrations increased linearly with time. Mass-transport coefficients (permeation, diffusion, and solubility coefficients) were also estimated and then used to successfully predict the postpurge rise of the oxygen concentration. PMID:20355958

  10. Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

    NASA Astrophysics Data System (ADS)

    Mezhenin, A. V.; Azyazov, V. N.

    2012-12-01

    The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio Π. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at τd <= 7. Efficient energy extraction from the OIL active medium is achieved in the case of τd = 5 - 7, Π = 4 - 8.

  11. Similarity criteria in calculations of the energy characteristics of a cw oxygen - iodine laser

    SciTech Connect

    Mezhenin, A V; Azyazov, V N

    2012-12-31

    The calculated and experimental data on the energy efficiency of a cw oxygen - iodine laser (OIL) are analysed based on two similarity criteria, namely, on the ratio of the residence time of the gas mixture in the resonator to the characteristic time of extraction of the energy stored in singlet oxygen td and on the gain-to-loss ratio {Pi}. It is shown that the simplified two-level laser model satisfactorily predicts the output characteristics of OILs with a stable resonator at {tau}{sub d} {<=} 7. Efficient energy extraction from the OIL active medium is achieved in the case of {tau}{sub d} = 5 - 7, {Pi} = 4 - 8. (lasers)

  12. Atomic oxygen reactor having at least one sidearm conduit

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L. (Inventor)

    1994-01-01

    An apparatus for treating a microporous structure with atomic oxygen is presented. The apparatus includes a main gas chamber for flowing gas in an axial direction and a source of gas, containing atomic oxygen, connected for introducing the gas into the main gas chamber. The apparatus employs at least one side arm extending from the main atomic oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

  13. Effect of annealing in a various oxygen atmosphere on structural, optical, electrical and gas sensing properties of MoxOy thin films

    NASA Astrophysics Data System (ADS)

    Arfaoui, A.; Ouni, B.; Touihri, S.; Mhamdi, A.; Labidi, A.; Manoubi, T.

    2015-07-01

    Molybdenum oxide thin films were thermally evaporated on a glass substrate and monitored by an annealing process in a variable oxygen atmosphere. The effects of post annealing condition on the microstructural, morphological, optical and electrical properties were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscope, spectroscopic ellipsometry and impedance spectroscopy. As-deposited amorphous films crystallized into tetragonal metastable phase of Mo5O14 on annealing at 500 °C in vacuum and air. This structure transformed to stable orthorhombic of MoO3 with annealing in oxygen environment. The optical parameters such as the refractive index, extinction coefficient, optical band gap energy and the Urbach energy were calculated from Cauchy formalism. Ellipsometric measurements reveal that the samples present optical gap located between 3.24 and 3.90 eV when the atmosphere becomes rich on oxygen. The variation of the conductivity in terms of the temperature shows an electrical behavior with oxygen environment. Finally, it has been found that MoO3 thin films had high sensitivity to ethanol, which made them as a good candidate for the ethanol sensor.

  14. Methanol Droplet Combustion in Oxygen-Inert Environments in Microgravity

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha; Dietrich, Daniel L.; Hicks, Michael C.; Williams, Forman A.

    2013-01-01

    The Flame Extinguishment (FLEX) experiment that is currently underway in the Combustion Integrated Rack facility onboard the International Space Station is aimed at understanding the effects of inert diluents on the flammability of condensed phase fuels. To this end, droplets of various fuels, including alkanes and alcohols, are burned in a quiescent microgravity environment with varying amounts of oxygen and inert diluents to determine the limiting oxygen index (LOI) for these fuels. In this study we report experimental observations of methanol droplets burning in oxygen-nitrogen-carbon dioxide and oxygen-nitrogen-helium gas mixtures at 0.7 and 1 atmospheric pressures. The initial droplet size varied between approximately 1.5 mm and 4 mm to capture both diffusive extinction brought about by insufficient residence time at the flame and radiative extinction caused by excessive heat loss from the flame zone. The ambient oxygen concentration varied from a high value of 30% by volume to as low as 12%, approaching the limiting oxygen index for the fuel. The inert dilution by carbon dioxide and helium varied over a range of 0% to 70% by volume. In these experiments, both freely floated and tethered droplets were ignited using symmetrically opposed hot-wire igniters and the burning histories were recorded onboard using digital cameras, downlinked later to the ground for analysis. The digital images yielded droplet and flame diameters as functions of time and subsequently droplet burning rate, flame standoff ratio, and initial and extinction droplet diameters. Simplified theoretical models correlate the measured burning rate constant and the flame standoff ratio reasonably well. An activation energy asymptotic theory accounting for time-dependent water dissolution or evaporation from the droplet is shown to predict the measured diffusive extinction conditions well. The experiments also show that the limiting oxygen index for methanol in these diluent gases is around 12% to

  15. OXYGEN POISONING IN MAMMALS.

    PubMed

    Binger, C A; Faulkner, J M; Moore, R L

    1927-04-30

    1. Oxygen in concentrations of over 70 per cent of an atmosphere is poisonous to dogs, rabbits, guinea pigs and mice. 2. The poisonous effects manifest themselves in drowsiness, anorexia, loss of weight, increasing dyspnea, cyanosis and death from oxygen want. 3. The cause of oxygen want is a destructive lesion of the lungs. 4. The lesion may be characterized grossly as an hemorrhagic edema. Microscopically there is to be seen in varying degrees of intensity (a) capillary engorgement with hemorrhage, (b) the presence of interstitial and intraalveolar serum, (c) hypertrophy and desquamation of alveolar cells, (d) interstitial and alveolar infiltration of mononuclear cells. 5. The type of tissue reaction is not characteristic of an infectious process and no organisms have been recovered at autopsy from the heart's blood or from lung puncture. 6. The poisonous effects of inhalations of oxygen-rich mixtures do not appear to be related to impurities in the oxygen, nor are they related to faulty ventilation, excessive moisture or increased carbon dioxide in the atmosphere of the chambers in which the experimental animals were confined. PMID:19869294

  16. Rhenium-Oxygen Interactions at High Temperatures

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Myers, Dwight L.; Zhu, Dongming; Humphrey, Donald

    2000-01-01

    The reaction of pure rhenium metal with dilute oxygen/argon mixtures was studied from 600 to 1400 C. Temperature, oxygen pressure, and flow rates were systematically varied to determine the rate-controlling steps. At lower temperatures the oxygen/rhenium chemical reaction is rate limiting; at higher temperatures gas-phase diffusion of oxygen through the static boundary layer is rate limiting. At all temperatures post-reaction microstructures indicate preferential attack along certain crystallographic planes and defects.

  17. Kinetics of the gas-phase reaction between ozone and three unsaturated oxygenated compounds: Ethyl 3,3-dimethyl acrylate, 2-methyl-2-pentenal and 6-methyl-5-hepten-2-one at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Gaona Colmán, Elizabeth; Blanco, María B.; Barnes, Ian; Teruel, Mariano A.

    2015-05-01

    Rate coefficients for the gas-phase reactions of O3 molecules with three unsaturated oxygenated compounds have been determined using the relative kinetic technique in an environmental chamber with FTIR detection of the reactants at (298 ± 2) K in 760 Torr total pressure of synthetic air. The following rate coefficients (in units of 10-17 cm3 molecule-1 s-1) were determined: ethyl 3,3-dimethyl acrylate (0.82 ± 0.19), 2-methyl-2-pentenal (0.71 ± 0.16) and 6-methyl-5-hepten-2-one (26 ± 7). The different reactivity of the unsaturated oxygenated compounds toward O3 is discussed in terms of their chemical structure. In addition, a correlation between the reactivity of structurally different unsaturated compounds (alkenes and unsaturated oxygenated VOCs, such as ethers, esters, aldehydes, ketones and alcohols) toward O3 molecules and the HOMO (Highest Occupied Molecular Orbital) of the compounds is presented. Using the kinetic parameters determined in this work, residence times of these unsaturated compounds in the atmosphere with respect to reaction with O3 have been calculated. In urban and rural areas the main sink of 6-methyl-5-hepten-2-one is reaction with O3 molecules with a residence time in the order of few minutes.

  18. Inhibition of reactive oxygen species generation and downstream activation of the ERK/STAT3/RANKL signaling cascade in osteoblasts accounts for the protective effects of estradiol on ethanol-induced bone loss

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bone loss occurs with chronic ethanol (EtOH) consumption in males and cycling females as a result of increased bone resorption. We have demonstrated that in vivo estradiol treatment can reverse this effect. However, the molecular mechanisms of EtOH-induced bone loss and of estrogen protection are la...

  19. Oxygen electrode reaction in molten carbonate fuel cells

    SciTech Connect

    Appleby, A.J.; White, R.E.

    1992-07-07

    Molten carbonate fuel cell system is a leading candidate for the utility power generation because of its high efficiency for fuel to AC power conversion, capability for an internal reforming, and a very low environmental impact. However, the performance of the molten carbonate fuel cell is limited by the oxygen reduction reaction and the cell life time is limited by the stability of the cathode material. An elucidation of oxygen reduction reaction in molten alkali carbonate is essential because overpotential losses in the molten carbonate fuel cell are considerably greater at the oxygen cathode than at the fuel anode. Oxygen reduction on a fully-immersed gold electrode in a lithium carbonate melt was investigated by electrochemical impedance spectroscopy and cyclic voltammetry to determine electrode kinetic and mass transfer parameters. The dependences of electrode kinetic and mass transfer parameters on gas composition and temperature were examined to determine the reaction orders and the activation energies. The results showed that oxygen reduction in a pure lithium carbonate melt occurs via the peroxide mechanism. A mass transfer parameter, D{sub O}{sup 1/2}C{sub O}, estimated by the cyclic voltammetry concurred with that calculated by the EIS technique. The temperature dependence of the exchange current density and the product D{sub O}{sup 1/2}C{sub O} were examined and the apparent activation energies were determined to be about 122 and 175 kJ/ mol, respectively.

  20. Respiratory weight losses during exercise.

    NASA Technical Reports Server (NTRS)

    Mitchell, J. W.; Nadel, E. R.; Stolwijk, J. A. J.

    1972-01-01

    Evaporative water loss from the respiratory tract was determined over a wide range of exercise. The absolute humidity of the expired air was the same at all levels of exercise and equal to that measured at rest. The rate of respiratory water loss during exercise was found to be 0.019 of the oxygen uptake times (44 minus water vapor pressure). The rate of weight loss during exercise due to CO2-O2 exchange was calculated. For exercise at oxygen consumption rates exceeding 1.5 L/min in a dry environment with a water vapor pressure of 10 mm Hg, the total rate of weight loss via the respiratory tract is on the order of 2-5 g/min.

  1. Wide-area remote-sensing system of pollution and gas dispersal by near-infrared absorption based on low-loss optical fiber network

    NASA Technical Reports Server (NTRS)

    Inaba, H.

    1986-01-01

    An all optical remote sensing system utilizing long distance, ultralow loss optical fiber networks is studied and discussed for near infrared absorption measurements of combustible and/or explosive gases such as CH4 and C3H8 in our environment, including experimental results achieved in a diameter more than 20 km. The use of a near infrared wavelength range is emphasized.

  2. Memory loss

    MedlinePlus

    ... usually include asking questions of family members and friends. For this reason, they should come to the appointment. Medical history questions may include: Type of memory loss, such as short-term or long-term ...

  3. Hair loss

    MedlinePlus

    ... that is applied to the scalp to stimulate hair growth. Other medicines, such as hormones, may be prescribed to decrease hair loss and promote hair growth. Drugs such as finasteride and dutasteride can be ...

  4. Hair Loss

    MedlinePlus

    ... Common baldness" usually means male-pattern baldness, or permanent-pattern baldness. It is also called androgenetic alopecia. ... will grow back normally. However, scarring can cause permanent hair loss. Hot oil hair treatments or chemicals ...

  5. Hair Loss

    MedlinePlus

    ... are stress, a low protein diet, a family history, or poor nutrition. Treatment for hair loss depends on the cause. In some cases, treating the underlying cause will correct the problem. Other treatments include medicines and hair restoration.

  6. Hearing Loss

    MedlinePlus

    ... Devices Can Help? Hearing aids. Hearing aids are electronic, battery-run devices that make sounds louder. There ... to turn up the volume. Cochlear implants. These electronic devices are for people with severe hearing loss. ...

  7. Quasi-two-dimensional electron gas at the epitaxial alumina/SrTiO{sub 3} interface: Control of oxygen vacancies

    SciTech Connect

    Kormondy, Kristy J.; Posadas, Agham B.; Demkov, Alexander A.; Ngo, Thong Q.; Ekerdt, John G.; Lu, Sirong; Smith, David J.; McCartney, Martha R.; Goble, Nicholas; Gao, Xuan P. A.; Jordan-Sweet, Jean

    2015-03-07

    In this paper, we report on the highly conductive layer formed at the crystalline γ-alumina/SrTiO{sub 3} interface, which is attributed to oxygen vacancies. We describe the structure of thin γ-alumina layers deposited by molecular beam epitaxy on SrTiO{sub 3} (001) at growth temperatures in the range of 400–800 °C, as determined by reflection-high-energy electron diffraction, x-ray diffraction, and high-resolution electron microscopy. In situ x-ray photoelectron spectroscopy was used to confirm the presence of the oxygen-deficient layer. Electrical characterization indicates sheet carrier densities of ∼10{sup 13 }cm{sup −2} at room temperature for the sample deposited at 700 °C, with a maximum electron Hall mobility of 3100 cm{sup 2}V{sup −1}s{sup −1} at 3.2 K and room temperature mobility of 22 cm{sup 2}V{sup −1}s{sup −1}. Annealing in oxygen is found to reduce the carrier density and turn a conductive sample into an insulator.

  8. Hyperbaric oxygen therapy and the eye.

    PubMed

    Butler, F K; Hagan, C; Murphy-Lavoie, H

    2008-01-01

    Hyperbaric oxygen therapy (HBOT) is a primary or adjunctive therapy for a variety of medical disorders including some involving the eye. This paper is the first comprehensive review of HBOT for ocular indications. The authors recommend the following as ocular indications for HBOT: decompression sickness or arterial gas embolism with visual signs or symptoms, central retinal artery occlusion, ocular and periocular gas gangrene, cerebro-rhino-orbital mucormycosis, periocular necrotizing fasciitis, carbon monoxide poisoning with visual sequelae, radiation optic neuropathy, radiation or mitomycin C-induced scleral necrosis, and periorbital reconstructive surgery. Other ocular disorders that may benefit from HBOT include selected cases of ischemic optic neuropathy, ischemic central retinal vein occlusion, branch retinal artery occlusion with central vision loss, ischemic branch retinal vein occlusion, cystoid macular edema associated with retinal venous occlusion, post-surgical inflammation, or intrinsic inflammatory disorders, periocular brown recluse spider envenomation, ocular quinine toxicity, Purtscher's retinopathy, radiation retinopathy, anterior segment ischemia, retinal detachment in sickle cell disease, refractory actinomycotiC lacrimal canaliculitis, pyoderma gangrenosum of the orbit and refractory pseudomonas keratitis. Visual function should be monitored as clinically indicated before, during, and after therapy when HBOT is undertaken to treat vision loss. Visual acuity alone is not an adequate measure of visual function to monitor the efficacy of HBOT in this setting. Ocular examinations should also include automated perimetry to evaluate the central 30 degrees of visual field at appropriate intervals. Interpretation of the literature on the efficacy of HBOT in treating ocular disorders is complicated by several factors: frequent failure to include visual field examination as an outcome measure, failure to adequately address the interval from symptom onset

  9. The Role of Plasmas on Enhanced O2+ Loss at Mars

    NASA Astrophysics Data System (ADS)

    Ergun, Robert; Andersson, Laila; Woodson, Adam; Fowler, Chris; Weber, Tristan; Delory, Greg; Andrews, David; Eriksson, Anders; Mooroka, Mitchico; Stweart, Ian; Mahaffy, Paul; Jakosky, Bruce

    2016-04-01

    Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures in Mars' day side ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O2+ up to ~500 km in altitude, suggesting that O2+ may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher electron temperature (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher electron temperature may greatly increase O2+ loss at Mars. In particular, enhanced Te in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field, which draws ions out of the region allowing for enhanced escape. With active solar wind, electron and ion heating, direct O2+ loss could match or exceed loss via dissociative recombination of O2+. These results suggest that direct loss of O2+ may have played a significant role in the loss of oxygen at Mars.

  10. Enhanced O2+ loss at Mars due to an ambipolar electric field from electron heating

    NASA Astrophysics Data System (ADS)

    Ergun, R. E.; Andersson, L. A.; Fowler, C. M.; Woodson, A. K.; Weber, T. D.; Delory, G. T.; Andrews, D. J.; Eriksson, A. I.; McEnulty, T.; Morooka, M. W.; Stewart, A. I. F.; Mahaffy, P. R.; Jakosky, B. M.

    2016-05-01

    Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures (Te) in Mars' dayside ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O2+ up to ~500 km in altitude, suggesting that O2+ may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher Te (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher Te may greatly increase O2+ loss at Mars. In particular, enhanced Te in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field with a potential (eΦ) of several kBTe, which draws ions out of the region allowing for enhanced escape. With active solar wind, electron, and ion heating, direct O2+ loss could match or exceed loss via dissociative recombination of O2+. These results suggest that direct loss of O2+ may have played a significant role in the loss of oxygen at Mars over time.

  11. Enhancement of Oxygen Mass Transfer and Gas Holdup Using Palm Oil in Stirred Tank Bioreactors with Xanthan Solutions as Simulated Viscous Fermentation Broths

    PubMed Central

    Mohd Sauid, Suhaila; Huey Ling, Tan; Veluri, Murthy V. P. S.

    2013-01-01

    Volumetric mass transfer coefficient (kLa) is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase the kLa. The present study opted for palm oil as the organic phase as it is plentiful in Malaysia. Experiments were carried out to study the effect of viscosity, gas holdup, and kLa on the xanthan solution with different palm oil fractions by varying the agitation rate and aeration rate in a 5 L bench-top bioreactor fitted with twin Rushton turbines. Results showed that 10% (v/v) of palm oil raised the kLa of xanthan solution by 1.5 to 3 folds with the highest kLa value of 84.44 h−1. It was also found that palm oil increased the gas holdup and viscosity of the xanthan solution. The kLa values obtained as a function of power input, superficial gas velocity, and palm oil fraction were validated by two different empirical equations. Similarly, the gas holdup obtained as a function of power input and superficial gas velocity was validated by another empirical equation. All correlations were found to fit well with higher determination coefficients. PMID:24350269

  12. Enhancement of oxygen mass transfer and gas holdup using palm oil in stirred tank bioreactors with xanthan solutions as simulated viscous fermentation broths.

    PubMed

    Mohd Sauid, Suhaila; Krishnan, Jagannathan; Huey Ling, Tan; Veluri, Murthy V P S

    2013-01-01

    Volumetric mass transfer coefficient (kLa) is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase the kLa. The present study opted for palm oil as the organic phase as it is plentiful in Malaysia. Experiments were carried out to study the effect of viscosity, gas holdup, and kLa on the xanthan solution with different palm oil fractions by varying the agitation rate and aeration rate in a 5 L bench-top bioreactor fitted with twin Rushton turbines. Results showed that 10% (v/v) of palm oil raised the kLa of xanthan solution by 1.5 to 3 folds with the highest kLa value of 84.44 h(-1). It was also found that palm oil increased the gas holdup and viscosity of the xanthan solution. The kLa values obtained as a function of power input, superficial gas velocity, and palm oil fraction were validated by two different empirical equations. Similarly, the gas holdup obtained as a function of power input and superficial gas velocity was validated by another empirical equation. All correlations were found to fit well with higher determination coefficients. PMID:24350269

  13. Device and method for separating oxygen isotopes

    DOEpatents

    Rockwood, Stephen D.; Sander, Robert K.

    1984-01-01

    A device and method for separating oxygen isotopes with an ArF laser which produces coherent radiation at approximately 193 nm. The output of the ArF laser is filtered in natural air and applied to an irradiation cell where it preferentially photodissociates molecules of oxygen gas containing .sup.17 O or .sup.18 O oxygen nuclides. A scavenger such as O.sub.2, CO or ethylene is used to collect the preferentially dissociated oxygen atoms and recycled to produce isotopically enriched molecular oxygen gas. Other embodiments utilize an ArF laser which is narrowly tuned with a prism or diffraction grating to preferentially photodissociate desired isotopes. Similarly, desired mixtures of isotopic gas can be used as a filter to photodissociate enriched preselected isotopes of oxygen.

  14. Consider oxygen for hydrocarbon oxidations

    SciTech Connect

    Shahani, G.H.; Gunardson, H.H.; Easterbrook, N.C.

    1996-11-01

    A number of commodity petrochemicals are produced by the selective, catalytic oxidation of hydrocarbons in the liquid and gas phase. These chemicals are the basic building blocks for a host of chemical intermediates. Producing each of these chemicals requires large volumes of air or tonnage quantities of oxygen for oxidation. This oxidation can be carried out using air, oxygen-enriched air, or pure oxygen. Many oxidation processes, such as that for making ethylene oxide, originally were implemented using air but have switched to oxygen. Other processes, such as for vinyl acetate, were developed as oxygen-based processes directly. Over the years, using pure oxygen has become an accepted practice in a number of petrochemical processes, such as those for acetaldehyde, ethylene oxide, propylene oxide, vinyl acetate, and vinyl chloride. As the authors will discuss, using oxygen provides some significant advantages. So, the authors expect that the trend of existing air-based processes converting to oxygen will continue, while new processes based on oxygen will emerge.

  15. A CENSUS OF OXYGEN IN STAR-FORMING GALAXIES: AN EMPIRICAL MODEL LINKING METALLICITIES, STAR FORMATION RATES, AND OUTFLOWS

    SciTech Connect

    Zahid, H. J.; Dima, G. I.; Kewley, L. J.; Erb, D. K.; Dave, R.

    2012-09-20

    In this contribution, we present the first census of oxygen in star-forming galaxies in the local universe. We examine three samples of galaxies with metallicities and star formation rates (SFRs) at z = 0.07, 0.8, and 2.26, including the Sloan Digital Sky Survey (SDSS) and DEEP2 survey. We infer the total mass of oxygen produced and mass of oxygen found in the gas-phase from our local SDSS sample. The star formation history is determined by requiring that galaxies evolve along the relation between stellar mass and SFR observed in our three samples. We show that the observed relation between stellar mass and SFR for our three samples is consistent with other samples in the literature. The mass-metallicity relation is well established for our three samples, and from this we empirically determine the chemical evolution of star-forming galaxies. Thus, we are able to simultaneously constrain the SFRs and metallicities of galaxies over cosmic time, allowing us to estimate the mass of oxygen locked up in stars. Combining this work with independent measurements reported in the literature, we conclude that the loss of oxygen from the interstellar medium of local star-forming galaxies is likely to be a ubiquitous process with the oxygen mass loss scaling (almost) linearly with stellar mass. We estimate the total baryonic mass loss and argue that only a small fraction of the baryons inferred from cosmological observations accrete onto galaxies.

  16. Generation of singlet oxygen for an oxygen-iodine laser in a radio-frequency discharge

    SciTech Connect

    Braginskii, O V; Vasil'eva, A N; Klopovskii, K S; Kovalev, A S; Lopaev, D V; Mankelevich, Yu A; Popov, N A; Rakhimov, Aleksandr T; Rakhimova, T V

    2005-01-31

    The generation of singlet oxygen (SO) in a radio-frequency discharge (13.56 MHz) in the gas flow was investigated experimentally and theoretically. The oxygen pressure was varied from 2 to 20 Torr and the energy deposition in gas from 10 to 2000 J mmol{sup -1}. The saturation of the SO concentration with increasing the energy deposition was shown to arise from the three-body process of SO quenching by atomic oxygen. Removing atomic oxygen allowed a 2.5-fold increase in the ultimate SO concentration at the discharge output. For an oxygen pressure of 15 Torr, the SO fraction amounts to 10%. (active media. lasers)

  17. Method for Trace Oxygen Detection

    NASA Technical Reports Server (NTRS)

    Man, Kim Fung (Inventor); Boumsellek, Said (Inventor); Chutjian, Ara (Inventor)

    1997-01-01

    Trace levels of molecular oxygen are measured by introducing a gas containing the molecular oxygen into a target zone, and impacting the molecular oxygen in the target zone with electrons at the O(-) resonant energy level for dissociative electron attachment to produce O(-) ions. Preferably, the electrons have an energy of about 4 to about 10 eV. The amount of O(-) ions produced is measured, and is correlated with the molecular oxygen content in the target zone. The technique is effective for measuring levels of oxygen below 50 ppb. and even less than 1 ppb. The amount of O(-) can be measured in a quadrupole mass analyzer. Best results are obtained when the electrons have an energy of about 6 to about 8 eV. and preferably about 6.8 eV. The method can be used for other species by selecting the appropriate electron energy level.

  18. Effect of varying the gas headspace to meat ratio on the quality and shelf-life of beef steaks packaged in high oxygen modified atmosphere packs.

    PubMed

    Murphy, K M; O'Grady, M N; Kerry, J P

    2013-08-01

    Beef steaks (M. longissimus dorsi) were stored in modified atmosphere packs (MAP) (80% O₂:20% CO₂) with gas headspace to meat ratios of 2:1, 1:1 and 0.5:1 for 14 days at 4 °C. The pH, surface colour, texture and microbiology of beef steaks were unaffected (P>0.05) by varying the gas headspace to meat ratio. APLSR (ANOVA-partial least squares regression) and jack-knife uncertainty testing indicated that lipid oxidation (TBARS) was significantly positively correlated with days 10 (P<0.05) and 14 (P<0.001) of storage. Chemical and sensory detection of lipid oxidation in beef steaks were in agreement on day 14 of storage. The sensory quality and acceptability of beef steaks were similar in gas headspace to meat ratios of 2:1 or 1:1 and unacceptable in 0.5:1. Results indicate that pack size and gas volume can be reduced without negatively affecting fresh beef quality and shelf-life. PMID:23618740

  19. The Unique Gas-Phase Chemistry of the [AuO](+) /CH4 Couple: Selective Oxygen-Atom Transfer to, Rather than Hydrogen-Atom Abstraction from, Methane.

    PubMed

    Zhou, Shaodong; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2016-08-26

    The thermal reaction of [AuO](+) with methane has been explored using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. In contrast to the previously studied congener [CuO](+) , and to [AgO](+) , [AuO](+) reacts with CH4 exclusively via oxygen-atom transfer to form CH3 OH, and a novel mechanistic scenario for this selective oxidation process has been revealed. Also, the origin of the inertness of the [AgO](+) /CH4 couple has been addressed computationally. PMID:27390885

  20. Oxygen-Concentrating Cell

    NASA Technical Reports Server (NTRS)

    Buehler, K.

    1986-01-01

    High-purity oxygen produced from breathing air or from propellantgrade oxygen in oxygen-concentrating cell. Operating economics of concentrator attractive: Energy consumption about 4 Wh per liter of oxygen, slightly lower than conventional electrochemical oxygen extractors.

  1. Using oxygen at home

    MedlinePlus

    ... DO NOT use oil-based products, such as petroleum jelly (Vaseline). Ask your oxygen equipment provider about ... oxygen; Hypoxia - home oxygen; Hospice - home oxygen References American Thoracic Society. Why do I need oxygen therapy? ...

  2. Reactivity of atomic oxygen radical anions bound to titania and zirconia nanoparticles in the gas phase: low-temperature oxidation of carbon monoxide.

    PubMed

    Ma, Jia-Bi; Xu, Bo; Meng, Jing-Heng; Wu, Xiao-Nan; Ding, Xun-Lei; Li, Xiao-Na; He, Sheng-Gui

    2013-02-27

    Titanium and zirconium oxide cluster anions with dimensions up to nanosize are prepared by laser ablation and reacted with carbon monoxide in a fast low reactor. The cluster reactions are characterized by time-of-flight mass spectrometry and density functional theory calculations. The oxygen atom transfers from (TiO(2))(n)O(-) (n = 3-25) to CO and formations of (TiO(2))(n)(-) are observed, whereas the reactions of (ZrO(2))(n)O(-) (n = 3-25) with CO generate the CO addition products (ZrO(2))(n)OCO(-), which lose CO(2) upon the collisions (studied for n = 3-9) with a crossed helium beam. The computational study indicates that the (MO(2))(n)O(-) (M = Ti, Zr; n = 3-8) clusters are atomic radical anion (O(-)) bonded systems, and the energetics for CO oxidation by the O(-) radicals to form CO(2) is strongly dependent on the metals as well as the cluster size for the titanium system. Atomic oxygen radical anions are important reactive intermediates, while it is difficult to capture and characterize them for condensed phase systems. The reactivity pattern of the O(-)-bonded (TiO(2))(n)O(-) and (ZrO(2))(n)O(-) correlates very well with different behaviors of titania and zirconia supports in the low-temperature catalytic CO oxidation. PMID:23368886

  3. Ozone - plant surface reactions an important ozone loss term?

    NASA Astrophysics Data System (ADS)

    Hansel, Armin; Jud, Werner; Fischer, Lukas; Canaval, Eva; Wohlfahrt, Georg; Tissier, Alain

    2015-04-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants responsible for global crop losses with associated economic costs of several billions dollar per year. Plant injuries have been related to the uptake of ozone through stomatal pores and oxidative effects damaging the internal leaf tissue. But a striking question remains: How much ozone enters the plant through open stomata and how much ozone is lost by chemical reactions at the plant surface? Until now surface losses are estimated from measured total ozone deposition fluxes and calculated stomatal conductance values. While stomatal conductance of CO2 and H2O is well understood and extensively used in describing plant atmosphere gas exchange, stomatal conductance of ozone is not well known. Here we use different Nicotiana tabacum varieties and find that surface reactions of ozone with diterpenoids synthesized by glandular trichomes reduce ozone flux through open stomata. Our measurements reveal that fast ozone loss at the plant surface is accompanied with prompt release of oxygenated volatile compounds. In the ozone fumigation experiments of different Nicotiana tabacum varieties the release of specific volatile oxy-VOCs allowed to identify the semi volatile precursor compounds at the plant surface. Ozone fumigation experiments with Norway spruce (Picea abies) and Scots Pine (Pinus sylvestris), two common species in the Northern Hemisphere, show also a significant ozone loss at the plant surface for Picea abies. Fluid dynamic calculations of ozone transport in the diffusive leaf boundary layer reveal a vertical but no horizontal ozone gradient thus reducing ozone fluxes through the pores in case of efficient ozone scavenging plant surfaces. We explain this efficient ozone protection mechanism by the porous surface architecture of plants in combination with unsaturated semi-volatile compounds deposited at the plant surface. These results show that unsaturated semi-volatile compounds at

  4. Hair Loss

    MedlinePlus

    ... psychosocial impact of hair loss have found patients’ self-esteem, body image and self-confidence to be negatively ... 1-2 Known psychosocial complications include depression, low self-esteem, altered self-image, and less frequent and enjoyable ...

  5. 38. DETAIL OF COOLING WATER BOOSTER PUMP FOR OXYGEN FURNACES, ...

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

    38. DETAIL OF COOLING WATER BOOSTER PUMP FOR OXYGEN FURNACES, LANCES, AND FUME HOODS IN THE GAS WASHER PUMP HOUSE LOOKING EAST. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  6. New electrolyte may increase life of polarographic oxygen sensors

    NASA Technical Reports Server (NTRS)

    Albright, C. F.

    1967-01-01

    Electrolyte increases life on oxygen sensors in a polarograph used for measuring the partial pressure of oxygen in a gas mixture. It consists of a solution of lithium chloride, dimethyl acetamide and water.

  7. 21 CFR 870.4350 - Cardiopulmonary bypass oxygenator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... bypass oxygenator. (a) Identification. A cardiopulmonary bypass oxygenator is a device used to exchange gases between blood and a gaseous environment to satisfy the gas exchange needs of a patient during...

  8. Plan for protection of oil and natural gas resources Naval Oil Shale Reserve No. 1 and No. 3, Garfield County, Colorado. [Communitization to prevent losses to nearby drillers

    SciTech Connect

    Not Available

    1987-10-01

    This plan provides for the protection of the Government's interest in hydrocarbons found in Naval Oil Shale Reserve No.1 (NOSR-1) and Naval Oil Shale Reserve No. 3 (NOSR-3) located in GArfield County, Colorado, and complements a similar plan developed in 1983. Recent development of private property near NOSR-3 exceeds the activity contemplated in the 1983 plan, and has progressed to drilling units on land which, under Colorado spacing orders, would include at least 50 percent NOSR-3 land. Due to the proximity of these commerical gas wells to NOSR-3 land, it is estimated that gas produced from the wells would include gas which had migrated from NOSR-3. To protect the Government's interest in these and other such wells which may be drilled near NOSR-1 or NOSR-3, the Department's plan of primary protection is to enter into communitization agreements with the private developers when they initiate wells which would drain NOSR-1 or NOSR-3 hydrocarbons. In general, these agreements would permit the sharing of costs and hydrocarbon production based on surface acreage owned by each party in each of the drilling units. If attempts to obtain such agreements fail, or if it is determined that offset wells are needed in addition to the communitized units, the Department plans to drill and produce wells on NOSR-1 and NOSR-3 which would offset production from nearby wells on private lands. These measures will preclude the migration of NOSR-1 and NOSR-3 hydrocarbons to privately-owned wells, and protect the Government's resources. The results of the Department of Justice anti-trust review performed pursuant to Section 7430(g) of title 10, United States Code, are provided as a part of this plan at Exhibit N.

  9. SAR11 bacteria linked to ocean anoxia and nitrogen loss.

    PubMed

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel; Nath, Sangeeta; Rodriguez-R, Luis M; Burns, Andrew S; Ranjan, Piyush; Sarode, Neha; Malmstrom, Rex R; Padilla, Cory C; Stone, Benjamin K; Bristow, Laura A; Larsen, Morten; Glass, Jennifer B; Thamdrup, Bo; Woyke, Tanja; Konstantinidis, Konstantinos T; Stewart, Frank J

    2016-08-11

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas. Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world's largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen, including genes for respiratory nitrate reductases (Nar). SAR11 nar genes were experimentally verified to encode proteins catalysing the nitrite-producing first step of denitrification and constituted ~40% of OMZ nar transcripts, with transcription peaking in the anoxic zone of maximum nitrate reduction activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth's most abundant organismal group. PMID:27487207

  10. Photochemical Aging of α-pinene and β-pinene Secondary Organic Aerosol formed from Nitrate Radical Oxidation: New Insights into the Formation and Fates of Highly Oxygenated Gas- and Particle-phase Organic Nitrates

    NASA Astrophysics Data System (ADS)

    Nah, T.; Sanchez, J.; Boyd, C.; Ng, N. L.

    2015-12-01

    The nitrate radical (NO3), one of the most important oxidants in the nocturnal atmosphere, can react rapidly with a variety of biogenic volatile organic compounds (BVOCs) to form high mass concentrations of secondary organic aerosol (SOA) and organic nitrates (ON). Despite its critical importance in aerosol formation, the mechanisms and products from the NO3 oxidation of BVOCs have been largely unexplored, and the fates of their SOA and ON after formation are not well characterized. In this work, we studied the formation of SOA and ON from the NO3 oxidation of α-pinene and β-pinene and investigated for the first time how they evolve during dark and photochemical aging through a series of chamber experiments performed at the Georgia Tech Environmental Chamber (GTEC) facility. The α-pinene and β-pinene SOA are characterized using real-time gas- and particle-phase measurements, which are used to propose mechanisms for SOA and organic nitrate formation and aging. Highly oxygenated gas- and particle-phase ON (containing as many as 9 oxygen atoms) are detected during the NO3 reaction. In addition, the β-pinene SOA and α-pinene SOA exhibited drastically different behavior during photochemical aging. Our results indicate that nighttime ON formed by NO3+monoterpene chemistry can serve as either NOx reservoirs or sinks depending on the monoterpene precursor. Results from this study provide fundamental data for evaluating the contributions of NO3+monoterpene reactions to ambient OA measured in the Southeastern U.S.

  11. Adiabatic Compression of Oxygen: Real Fluid Temperatures

    NASA Technical Reports Server (NTRS)

    Barragan, Michelle; Wilson, D. Bruce; Stoltzfus, Joel M.

    2000-01-01

    The adiabatic compression of oxygen has been identified as an ignition source for systems operating in enriched oxygen atmospheres. Current practice is to evaluate the temperature rise on compression by treating oxygen as an ideal gas with constant heat capacity. This paper establishes the appropriate thermodynamic analysis for the common occurrence of adiabatic compression of oxygen and in the process defines a satisfactory equation of state (EOS) for oxygen. It uses that EOS to model adiabatic compression as isentropic compression and calculates final temperatures for this system using current approaches for comparison.

  12. Quantum dots as a possible oxygen sensor

    NASA Astrophysics Data System (ADS)

    Ziółczyk, Paulina; Kur-Kowalska, Katarzyna; Przybyt, Małgorzata; Miller, Ewa

    Results of studies on optical properties of low toxicity quantum dots (QDs) obtained from copper doped zinc sulfate are discussed in the paper. The effect of copper admixture concentration and solution pH on the fluorescence emission intensity of QDs was investigated. Quenching of QDs fluorescence by oxygen was reported and removal of the oxygen from the environment by two methods was described. In the chemical method oxygen was eliminated by adding sodium sulfite, in the other method oxygen was removed from the solution using nitrogen gas. For elimination of oxygen by purging the solution with nitrogen the increase of fluorescence intensity with decreasing oxygen concentration obeyed Stern-Volmer equation indicating quenching. For the chemical method Stern-Volmer equation was not fulfilled. The fluorescence decays lifetimes were determined and the increase of mean lifetimes at the absence of oxygen support hypothesis that QDs fluorescence is quenched by oxygen.

  13. Protective Effects of Estradiol on Ethanol-induced Bone Loss Involves Inhibition of Reactive Oxygen Species Generation in Osteoblasts and Downstream Activation of the ERK/STAT3/RANKL Signaling Cascade

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bone loss occurs following chronic ethanol (EtOH) consumption in males and cycling females in part as a result of increased bone resorption. We have demonstrated in vivo that estradiol treatment can reverse this effect. Using osteoclast precursors from bone marrow and osteoblast/pre-osteoclast co-cu...

  14. Report on ISS O2 Production, Gas Supply and Partial Pressure Management

    NASA Technical Reports Server (NTRS)

    Schaezler, Ryan N.; Cook, Anthony J.

    2015-01-01

    Oxygen is used on International Space Station (ISS) for metabolic support and denitrogenation procedures prior to Extra-Vehicular Activities. Nitrogen is used to maintain total pressure and account for losses associated with leakage and operational losses. Oxygen and nitrogen have been supplied by various visiting vehicles such as the Progress and Shuttle in addition to the on-orbit oxygen production capability. Starting in 2014, new high pressure oxygen/nitrogen tanks are available to launch on commercial cargo vehicles and will replace the high pressure gas source that Shuttle used to provide. To maintain a habitable atmosphere the oxygen and nitrogen partial pressures are controlled between upper and lower bounds. The full range of the allowable partial pressures along with the increased ISS cabin volume are utilized as a buffer allowing days to pass between oxygen production or direct addition of oxygen and nitrogen to the atmosphere from reserves. This paper summarizes the amount of gas supplied and produced from all of the sources and describes past experience of managing partial pressures along with the range of management options available to the ISS.

  15. Underground coal gasification using oxygen and steam

    SciTech Connect

    Yang, L.H.; Zhang, X.; Liu, S.

    2009-07-01

    In this paper, through model experiment of the underground coal gasification, the effects of pure oxygen gasification, oxygen-steam gasification, and moving-point gasification methods on the underground gasification process and gas quality were studied. Experiments showed that H{sub 2} and CO volume fraction in product gas during the pure oxygen gasification was 23.63-30.24% and 35.22-46.32%, respectively, with the gas heating value exceeding 11.00 MJ/m{sup 3}; under the oxygen-steam gasification, when the steam/oxygen ratio stood at 2: 1, gas compositions remained virtually stable and CO + H{sub 2} was basically between 61.66 and 71.29%. Moving-point gasification could effectively improve the changes in the cavity in the coal seams or the effects of roof inbreak on gas quality; the ratio of gas flowing quantity to oxygen supplying quantity was between 3.1:1 and 3.5:1 and took on the linear changes; on the basis of the test data, the reasons for gas quality changes under different gasification conditions were analyzed.

  16. Pregnancy loss.

    PubMed

    Robinson, Gail Erlick

    2014-01-01

    Women who lose desired pregnancies by miscarriage, stillbirth, or genetic termination are at risk of suffering from grief, anxiety, guilt and self-blame that may even present in subsequent pregnancies. It is important to find effective means of helping women deal with these losses. The approach to stillbirth has shifted from immediately removing the child from the mother to encouraging the parents to view and hold the baby. This approach has been questioned as possibly causing persistent anxiety and post-traumatic stress disorder. Women who miscarry are currently encouraged to find ways to memorialise the lost fetus. Couples who decide to terminate a pregnancy after discovering a defect may deal not only with sadness but also guilt. Immediate crisis intervention and follow-up care should be available, recognising that individual women may experience different reactions and their specific post-loss needs must be assessed. PMID:24047642

  17. Beam loss

    NASA Astrophysics Data System (ADS)

    VanGinneken, A.; Edwards, D.; Harrison, M.

    1989-04-01

    This paper presents results from simulations of beam losses during the operation of a superconducting accelerator. The calculations use a combination of hadron/electromagnetic cascade plus elastic scattering codes with accelerator tracking routines. These calculations have been used in conjunction with the design of the Fermilab Tevatron. First accelerator geometry is described. The rest of the paper discusses a detailed attempt to simulate a fast extraction cycle, essentially in chronological order. Beginning with an unperturbed beam, the simulation generates proton phase-space distributions incident on the electrostatic septum. These interact either elastically or inelastically with the septum wires, and the products of these interactions are traced through the machine. Where these leave the accelerator, energy deposition levels in the magnets are calculated together with the projected response of the beam-loss monitors in this region. Finally, results of the calculation are compared with experimental data. (AIP)

  18. Atomic oxygen patterning from a biomedical needle-plasma source

    NASA Astrophysics Data System (ADS)

    Kelly, Seán; Turner, Miles M.

    2013-09-01

    A "plasma needle" is a cold plasma source operating at atmospheric pressure. Such sources interact strongly with living cells, but experimental studies on bacterial samples show that this interaction has a surprising pattern resulting in circular or annular killing structures. This paper presents numerical simulations showing that this pattern occurs because biologically active reactive oxygen and nitrogen species are produced dominantly where effluent from the plasma needle interacts with ambient air. A novel solution strategy is utilised coupling plasma produced neutral (uncharged) reactive species to the gas dynamics solving for steady state profiles at the treated biological surface. Numerical results are compared with experimental reports corroborating evidence for atomic oxygen as a key bactericidal species. Surface losses are considered for interaction of plasma produced reactants with reactive solid and liquid interfaces. Atomic oxygen surface reactions on a reactive solid surface with adsorption probabilities above 0.1 are shown to be limited by the flux of atomic oxygen from the plasma. Interaction of the source with an aqueous surface showed hydrogen peroxide as the dominant species at this interface.

  19. Atomic oxygen patterning from a biomedical needle-plasma source

    SciTech Connect

    Kelly, Seán; Turner, Miles M.

    2013-09-28

    A “plasma needle” is a cold plasma source operating at atmospheric pressure. Such sources interact strongly with living cells, but experimental studies on bacterial samples show that this interaction has a surprising pattern resulting in circular or annular killing structures. This paper presents numerical simulations showing that this pattern occurs because biologically active reactive oxygen and nitrogen species are produced dominantly where effluent from the plasma needle interacts with ambient air. A novel solution strategy is utilised coupling plasma produced neutral (uncharged) reactive species to the gas dynamics solving for steady state profiles at the treated biological surface. Numerical results are compared with experimental reports corroborating evidence for atomic oxygen as a key bactericidal species. Surface losses are considered for interaction of plasma produced reactants with reactive solid and liquid interfaces. Atomic oxygen surface reactions on a reactive solid surface with adsorption probabilities above 0.1 are shown to be limited by the flux of atomic oxygen from the plasma. Interaction of the source with an aqueous surface showed hydrogen peroxide as the dominant species at this interface.

  20. Volatile organic compounds in a residential and commercial urban area with a diesel, compressed natural gas and oxygenated gasoline vehicular fleet.

    PubMed

    Martins, Eduardo Monteiro; Arbilla, Graciela; Gatti, Luciana Vanni

    2010-02-01

    Air samples were collected in a typical residential and commercial area in Rio de Janeiro, Brazil, where buses and trucks use diesel and light duty vehicles use compressed natural gas, ethanol, and gasohol (gasoline blended with ethanol) as fuel. A total of 66 C3-C12 volatile organic compounds (VOCs) were identified. The most abundant compounds, on a mass concentration basis, included propane, isobutane, i-pentane, m,p-xylene, 1,3,5-trimethylbenzene, toluene, styrene, ethylbenzene, isopropylbenzene, o-xylene and 1,2,4-trimethylbenzene. Two VOCs photochemical reactivity rankings are presented: one involves reaction with OH and the other involves production of ozone. PMID:19787279