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Sample records for high chemical oxygen

  1. A modified method for estimation of chemical oxygen demand for samples having high suspended solids.

    Science.gov (United States)

    Yadvika; Yadav, Asheesh Kumar; Sreekrishnan, T R; Satya, Santosh; Kohli, Sangeeta

    2006-03-01

    Determination of chemical oxygen demand (COD) of samples having high suspended solids concentration such as cattle dung slurry with open reflux method of APHA-AWWA-WPCF did not give consistent results. This study presents a modification of the open reflux method (APHA-AWWA-WPCF) to make it suitable for samples with high percentage of suspended solids. The new method is based on a different technique of sample preparation, modified quantities of reagents and higher reflux time as compared to the existing open reflux method. For samples having solids contents of 14.0 g/l or higher, the modified method was found to give higher value of COD with much higher consistency and accuracy as compared to the existing open reflux method.

  2. Highly vibrationally excited CO generated in a low-temperature chemical reaction between carbon vapor and molecular oxygen

    Science.gov (United States)

    Jans, E.; Frederickson, K.; Yurkovich, M.; Musci, B.; Rich, J. W.; Adamovich, I. V.

    2016-08-01

    A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v = 14, at low temperatures, T = 400-450 K, with population inversion at v = 4-7, in a collision-dominated environment, 15-20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants.

  3. High-pressure gravity-independent singlet oxygen generator, laser nozzle, and iodine injection system for the chemical oxygen-iodine laser

    Science.gov (United States)

    Emanuel, George

    2004-09-01

    A novel approach is outlined for a singlet oxygen generator (SOG), a laser minimum length nozzle (MLN), and an iodine injector system for a chemical oxygen-iodine laser (COIL). A unified approach, referred to as a SOG/MLN/I2 system, is partly based on past experimental work. For instance, the SOG concept stems from sparger technology and a KSY fesibility experiment. A MLN with a curved sonic line is used for the laser nozzle, and slender struts are used for the injection, in the downstream direction, of iodine/helium vapor. The heated struts are located downstream of the nozzle's throat. The engineering logic behind the approach is discussed; it has a diversity of potential system benefits relative to current technology. These include a compact, scalable laser that can operate in space. The SOG operates at a significantly higher pressure with a high O2(1Δ) yield. In addition, basic hydrogen peroxide reconditioning is not required, a water vapor removal system is not required, and diluent may be unnecessary, although useful for pressure recovery. The impact on a COIL system in terms of power, efficiency, and pressure recovery is briefly assessed.

  4. High removal of chemical and biochemical oxygen demand from tequila vinasses by using physicochemical and biological methods.

    Science.gov (United States)

    Retes-Pruneda, Jose Luis; Davila-Vazquez, Gustavo; Medina-Ramírez, Iliana; Chavez-Vela, Norma Angelica; Lozano-Alvarez, Juan Antonio; Alatriste-Mondragon, Felipe; Jauregui-Rincon, Juan

    2014-08-01

    The goal of this research is to find a more effective treatment for tequila vinasses (TVs) with potential industrial application in order to comply with the Mexican environmental regulations. TVs are characterized by their high content of solids, high values of biochemical oxygen demand (BODs), chemical oxygen demand (COD), low pH and intense colour; thus, disposal of untreated TVs severely impacts the environment. Physicochemical and biological treatments, and a combination of both, were probed on the remediation of TVs. The use of alginate for the physicochemical treatment of TVs reduced BOD5 and COD values by 70.6% and 14.2%, respectively. Twenty white-rot fungi (WRF) strains were tested in TV-based solid media. Pleurotus ostreatus 7992 and Trametes trogii 8154 were selected due to their ability to grow on TV-based solid media. Ligninolytic enzymes' production was observed in liquid cultures of both fungi. Using the selected WRF for TVs' bioremediation, both COD and BOD5 were reduced by 88.7% and 89.7%, respectively. Applying sequential physicochemical and biological treatments, BOD5 and COD were reduced by 91.6% and 93.1%, respectively. Results showed that alginate and selected WRF have potential for the industrial treatment of TVs.

  5. High Selectivity Oxygen Delignification

    Energy Technology Data Exchange (ETDEWEB)

    Lucian A. Lucia

    2005-11-15

    Project Objective: The objectives of this project are as follows: (1) Examine the physical and chemical characteristics of a partner mill pre- and post-oxygen delignified pulp and compare them to lab generated oxygen delignified pulps; (2) Apply the chemical selectivity enhancement system to the partner pre-oxygen delignified pulps under mill conditions (with and without any predetermined amounts of carryover) to determine how efficiently viscosity is preserved, how well selectivity is enhanced, if strength is improved, measure any yield differences and/or bleachability differences; and (3) Initiate a mill scale oxygen delignification run using the selectivity enhancement agent, collect the mill data, analyze it, and propose any future plans for implementation.

  6. Simultaneous efficient removal of high-strength ammonia nitrogen and chemical oxygen demand from landfill leachate by using an extremely high ammonia nitrogen-resistant strain.

    Science.gov (United States)

    Yu, Dahai; Yang, Jiyu; Fang, Xuexun; Ren, Hejun

    2015-01-01

    Bioaugmentation is a promising technology for pollutant elimination from stressed environments, and it would provide an efficient way to solve challenges in traditional biotreatment of wastewater with high strength of ammonia nitrogen (NH4(+)-N). A high NH4(+)-N-resistant bacteria strain, identified as Bacillus cereus (Jlu BC), was domesticated and isolated from the bacteria consortium in landfill leachate. Jlu BC could survive in 100 g/L NH4(+)-N environment, which indicated its extremely high NH4(+)-N tolerance than the stains found before. Jlu BC was employed in the bioaugmented system to remove high strength of NH4(+)-N from landfill leachate, and to increase the removal efficiency, response surface methodology (RSM) was used for optimizing bioaugmentation degradation conditions. At the optimum condition (initial pH 7.33, 4.14 days, initial chemical oxygen demand [COD] concentration [18,000 mg/L], 3.5 mL inoculated domesticated bacteria strain, 0.3 mg/mL phosphorus supplement, 30 °C, and 170 rpm), 94.74 ± 3.8% removal rate of NH4(+)-N was obtained, and the experiment data corresponded well with the predicted removal rate of the RSM models (95.50%). Furthermore, COD removal rate of 81.94 ± 1.4% was obtained simultaneously. The results presented are promising, and the screened strain would be of great practical importance in mature landfill leachate and other NH4(+)-N enrichment wastewater pollution control.

  7. High Selectivity Oxygen Delignification

    Energy Technology Data Exchange (ETDEWEB)

    Arthur J. Ragauskas

    2005-09-30

    The overall objective of this program was to develop improved extended oxygen delignification (EOD) technologies for current U.S. pulp mill operations. This was accomplished by: (1) Identifying pulping conditions that optimize O and OO performance; (2) Identifying structural features of lignin that enhance reactivity towards EOD of high kappa pulps; (3) Identifying factors minimizing carbohydrate degradation and improve pulp strength of EOD high kappa pulps; (4) Developing a simple, reproducible method of quantifying yield gains from EOD; and (5) Developing process conditions that significantly reduce the capital requirements of EOD while optimizing the yield benefits. Key research outcomes included, demonstrating the use of a mini-O sequence such as (E+O)Dkf:0.05(E+O) or Dkf:0.05(E+O)(E+O) without interstage washing could capture approximately 60% of the delignification efficiency of a conventional O-stage without the major capital requirements associated with an O-stage for conventional SW kraft pulps. The rate of formation and loss of fiber charge during an O-stage stage can be employed to maximize net fiber charge. Optimal fiber charge development and delignification are two independent parameters and do not parallel each other. It is possible to utilize an O-stage to enhance overall cellulosic fiber charge of low and high kappa SW kraft pulps which is beneficial for physical strength properties. The application of NIR and multi-variant analysis was developed into a rapid and simple method of determining the yield of pulp from an oxygen delignification stage that has real-world mill applications. A focus point of this program was the demonstration that Kraft pulping conditions and oxygen delignification of high and low-kappa SW and HW pulps are intimately related. Improved physical pulp properties and yield can be delivered by controlling the H-factor and active alkali charge. Low AA softwood kraft pulp with a kappa number 30 has an average improvement of 2% in

  8. Combined coagulation-flocculation and sequencing batch reactor with phosphorus adjustment for the treatment of high-strength landfill leachate: experimental kinetics and chemical oxygen demand fractionation.

    Science.gov (United States)

    El-Fadel, M; Matar, F; Hashisho, J

    2013-05-01

    The treatability of high-strength landfill leachate is challenging and relatively limited. This study examines the feasibility of treating high-strength landfill leachate (chemical oxygen demand [COD]: 7,760-11,770 mg/L, biochemical oxygen demand [BOD5]: 2,760-3,569 mg/L, total nitrogen [TN] = 980-1,160 mg/L) using a sequencing batch reactor (SBR) preceded by a coagulation-flocculation process with phosphorus nutritional balance under various mixing and aeration patterns. Simulations were also conducted to define kinetic parameters and COD fractionation. Removal efficiencies reached 89% for BOD5, 60% for COD, and 72% for TN, similar to and better than reported studies, albeit with a relatively lower hydraulic retention time (HRT) and solid retention time (SRT). The coupled experimental and simulation results contribute in filling a gap toward managing high-strength landfill leachate and providing guidelines for corresponding SBR applications. The treatability of high-strength landfill leachate, which is challenging and relatively limited, was demonstrated using a combined coagulation-flocculation with SBR technology and nutrient balance adjustment. The most suitable coagulant, kinetic design parameters, and COD fractionation were defined using coupled experimental and simulation results contributing in filling a gap toward managing high-strength leachate by providing guidelines for corresponding SBR applications and anticipating potential constraints related to the non-biodegradable COD fraction. In this context, while the combined coagulation-flocculation and SBR process improved removal efficiencies, posttreatment may be required for high-strength leachate, depending on discharge standards and ultimate usage of the treated leachate.

  9. Analytical determination of Chemical Oxygen Demand in samples considered to be difficult to analyse: solid substrates and liquid samples with high suspended solid concentrations

    DEFF Research Database (Denmark)

    Raposo, Francisco; Fernández-Cegrí, V.; De la Rubia, M.A.

    Chemical oxygen demand (COD) is a critical analytical parameter in the field of waste and wastewater treatment processes, and more specifically in anaerobic digestion processes. However, little is known about the COD measurement quality of anaerobic digestion samples. Taking into account the lack...

  10. Application of high resolution Chemical Ionization Mass Spectrometry (CI-ToFMS to study SOA composition: focus on formation of oxygenated species via aqueous phase processing

    Directory of Open Access Journals (Sweden)

    D. Aljawhary

    2013-07-01

    Full Text Available This paper demonstrates the capabilities of Chemical Ionization Mass Spectrometry (CIMS to study secondary organic aerosol (SOA composition with a high resolution (HR time-of-flight mass analyzer (aerosol-CI-ToFMS. In particular, by studying aqueous oxidation of Water Soluble Organic Compounds (WSOC extracted from α-pinene ozonolysis SOA, we assess the capabilities of three common CIMS reagent ions: (a protonated water clusters (H2OnH+, (b acetate CH3C(OO− and (c iodide water clusters I(H2On− to monitor SOA composition. As well, we report the relative sensitivity of these reagent ions to a wide range of common organic aerosol constituents. We find that (H2OnH+ is more selective to the detection of less oxidized species, so that the range of O/C and OSC (carbon oxidation state in the SOA spectra is considerably lower than those measured using CH3C(OO− and I(H2On−. Specifically, (H2OnH+ ionizes organic compounds with OSC ≤ 1.3, whereas CH3C(OO− and I(H2On− both ionize highly oxygenated organics with OSC up to 4 with I(H2On− being more selective towards multi-functional organic compounds. In the bulk O/C and H/C space, i.e. in a Van Krevelen plot, there is a remarkable agreement in both absolute magnitude and oxidation trajectory between CI-ToFMS data and those from a high resolution aerosol mass spectrometer (HR-AMS. This indicates that the CI-ToFMS data captures much of the chemical change occurring in the particle and that gas phase species, which are not detected by the HR-AMS, do not dominate the overall ion signal. Finally, the data illustrate the capability of aerosol-CI-ToFMS to monitor specific chemical change, including the fragmentation and functionalization reactions that occur during organic oxidation, and the oxidative conversion of dimeric SOA species into monomers. Overall, aerosol-CI-ToFMS is a valuable, selective complement to some common SOA characterization methods, such as AMS and spectroscopic techniques. Both

  11. Comparison of oxygen carriers for chemical-looping combustion

    Directory of Open Access Journals (Sweden)

    Johansson Marcus

    2006-01-01

    Full Text Available Chemical-looping combustion is a combustion technology with inherent separation of the greenhouse gas CO2. This technique involves combustion of fossil fuels by means of an oxygen carrier which transfers oxygen from the air to the fuel. In this manner a decrease in efficiency is avoided for the energy demanding separation of CO2 from the rest of the flue gases. Results from fifty oxygen carriers based on iron-, manganese- and nickel oxides on different inert materials are compared. The particles were prepared using freeze granulation, sintered at different temperatures and sieved to a size 125-180 mm. To simulate the environment the particles would be exposed to in a chemical-looping combustor, reactivity tests under alternating oxidizing and reducing conditions were performed in a laboratory fluidized bed-reactor of quartz. Reduction was performed in 50% CH4/50% H2O while the oxidation was carried out in 5% O2 in nitrogen. In general nickel particles are the most reactive, followed by manganese. Iron particles are harder but have a lower reactivity. An increase in sintering temperatures normally leads to an increase in strength and decrease in reactivity. Several particles investigated display a combination of high reactivity and strength as well as good fluidization behavior, and are feasible for use as oxygen carriers in chemical-looping combustion.

  12. Analytical determination of Chemical Oxygen Demand in samples considered to be difficult to analyse: solid substrates and liquid samples with high suspended solid concentrations

    DEFF Research Database (Denmark)

    Raposo, Francisco; Fernández-Cegrí, V.; De la Rubia, M.A.

    Chemical oxygen demand (COD) is a critical analytical parameter in the field of waste and wastewater treatment processes, and more specifically in anaerobic digestion processes. However, little is known about the COD measurement quality of anaerobic digestion samples. Taking into account the lack...... PTs related with COD determination have been organised, and the results reported have been compared; showing the importance of continuous participation in proficiency testing (PT) schemes in order to improve the results obtained....

  13. Performance of a stratified sand filter in removal of chemical oxygen demand, total suspended solids and ammonia nitrogen from high-strength wastewaters.

    Science.gov (United States)

    Healy, M G; Rodgers, M; Mulqueen, J

    2007-06-01

    A stratified sand filter column, operated in recirculation mode and treating synthetic effluent resembling high-strength dairy wastewaters was studied over a 342-d duration. The aim of this paper was to examine the organic, total suspended solids (TSS) and nutrient removal rates of the sand filter, operated in recirculation mode, under incrementally increasing hydraulic and organic loading rates and to propose a field filter-sizing criterion. Best performance was obtained at a system hydraulic loading rate of 10 L m(-2) d(-1); a higher system hydraulic loading rate (of 13.4 L m(-2) d(-1)) caused surface ponding. The system hydraulic loading rate of 10 L m(-2) d(-1) gave a filter chemical oxygen demand (COD), TSS, and total kjeldahl nitrogen (TKN) loading rate of 14, 3.7, and 2.1 g m(-2) d(-1), respectively, and produced consistent COD and TSS removals of greater than 99%, and an effluent NO(3)-N concentration of 42 mg L(-1) (accounting for an 86% reduction in total nitrogen (Tot-N)). As the proportional surface area requirement for the sand filter described in this study is less than the recommended surface area requirement of a free-water surface (FWS) wetland treating an effluent of similar quality, it could provide an economic and sustainable alternative to conventional wetland treatment.

  14. Assessment of a modified and optimised method for determining chemical oxygen demand of solid substrates and solutions with high suspended solid content.

    Science.gov (United States)

    Raposo, F; de la Rubia, M A; Borja, R; Alaiz, M

    2008-07-15

    A modified approach to determine the chemical oxygen demand (COD) of solid substrates based on the DIN 38414-S9 standard method is proposed. The adapted procedure is assessed and compared with standard methods widely used for water and wastewater such as the American Public Health Association-American Water Works Association-Water Pollution Control Federation (APHA-AWWA-WPCF) standard methods 5220 B-open reflux (SM-OR) and 5220 D-closed reflux colorimetric (SM-CR). Solutions with high suspended concentration of solids, as well as digestates from an anaerobic reactor, were used during the comparative test. For solid substrates, the COD recovery was about 100% when the proposed method was used. For solutions with solid content higher than 20 g TS L(-1), the recovery was only completed when the proposed method was used, showing that the methods traditionally employed are not very appropriate for samples with the described characteristics. For instance, percentages of COD recovery in the ranges of 77.3-87.1% and 89.4-94.1% were achieved when the SM-OR and SM-CR methods were used, respectively.

  15. High Temperature Sorbents for Oxygen

    Science.gov (United States)

    Sharma, Pramod K. (Inventor)

    1996-01-01

    A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C is introduced. The sorbent comprises a porous alumina silicate support such as zeolite containing from 1 to 10 percent by weight of ion exchanged transition metal such as copper or cobalt ions and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum. The activation temperature, oxygen sorption and reducibility are all improved by the presence of the platinum activator.

  16. Relationship between Oxygen Chemical Potential and Steel Cleanliness

    Institute of Scientific and Technical Information of China (English)

    Mansour Soltanieh; Yousef Payandeh

    2005-01-01

    To investigate inclusion formation in each step during steel making process, several samples were taken in different steps of the production of steel at Mobarakeh Steel Co of Esfahan to measure the oxygen chemical potential of the molten steel in each stage. The chemical compositions of the inclusions in samples were investigated lby scanning electron microscope. The chemical composition of the slag was analyzed. With the use of thermodynamic calculations and chemical analysis of the melt, at the working temperature, the relationship between dissolved oxygen and other elements were determined. Finally, it was found that there is a close relationship between inclusions formed in each step with the oxygen partial pressure.

  17. Oxygen permeation and thermo-chemical stability of oxygen separation membrane materials for the oxyfuel process

    Energy Technology Data Exchange (ETDEWEB)

    Ellett, Anna Judith

    2009-07-01

    The reduction of CO{sub 2} emissions, generally held to be one of the most significant contributors to global warming, is a major technological issue. CO{sub 2} Capture and Storage (CCS) techniques applied to large stationary sources such as coal-fired power plants could efficiently contribute to the global carbon mitigation effort. The oxyfuel process, which consists in the burning of coal in an oxygen-rich atmosphere to produce a flue gas highly concentrated in CO{sub 2}, is a technology considered for zero CO{sub 2} emission coal-fired power plants. The production of this O{sub 2}-rich combustion gas from air can be carried out using high purity oxygen separation membranes. Some of the most promising materials for this application are mixed ionic-electronic conducting (MIEC) materials with perovskite and K{sub 2}NiF{sub 4} perovskite-related structures. The present work examines the selection of La{sub 0.58}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCF58), La{sub 2}NiO{sub 4+{delta}}, Pr{sub 0.58}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (PSCF58) and Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF50) as membrane materials for the separation of O{sub 2} and N{sub 2} in the framework of the oxyfuel process with flue gas recycling. Annealing experiments were carried out on pellets exposed to CO{sub 2}, water vapour, O{sub 2} and Cr{sub 2}O{sub 3} in order to determine the thermo-chemical resistance to the atmospheres and the high temperature conditions present during membrane operation in a coal-fired power plant. The degradation of their microstructure was investigated using Scanning Electron Microscopy (SEM) in combination with electron dispersive spectroscopy (EDS) as well as X-Ray Diffraction (XRD). Also, the oxygen permeation fluxes of selected membranes were investigated as a function of temperature. The membrane materials selected were characterised using thermo-analytical techniques such as precision thermogravimetric

  18. Chemical aspects of coal liquefaction by oxygen in alkaline slurries

    Energy Technology Data Exchange (ETDEWEB)

    Andreozzi, R.; Caprio, V.; Insola, A.

    1988-03-01

    Coal liquefaction by oxygen in alkaline slurries is reviewed from the chemical point of view. Available information is considered in the light of questions relating to coal liquefaction. A lack of chemical knowledge in this area is noted, especially on model compounds. 72 refs.

  19. In situ chemical and structural investigations of the oxidation of Ge(001) substrates by atomic oxygen

    Science.gov (United States)

    Molle, Alessandro; Bhuiyan, Md. Nurul Kabir; Tallarida, Grazia; Fanciulli, Marco

    2006-08-01

    The exposure of Ge(001) substrates to atomic oxygen was studied in situ to establish the stability of the germanium oxide. After preparing chemically clean and atomically flat Ge(001) surfaces, the Ge samples were exposed to atomic oxygen in a wide temperature range from room temperature to 400°C. The chemical composition of the so-formed oxides was studied by means of x-ray photoelectron spectroscopy, while the structure was observed by reflection high energy electron diffraction. At low substrate temperatures the atomic oxygen is efficiently chemisorbed and suboxides coexist with the dioxide, which in turn is remarkably promoted in the high temperature range.

  20. Application of Ozone and Oxygen to Reduce Chemical Oxygen Demand and Hydrogen Sulfide from a Recovered Paper Processing Plant

    Directory of Open Access Journals (Sweden)

    Patricia A. Terry

    2010-01-01

    Full Text Available A pilot study was performed at the Fox River Fiber recovered paper processing company in DePere, Wisconsin, to determine the extent to which injection of oxygen and ozone could reduce the high chemical oxygen demand, COD, in the effluent and the effectiveness of the ozone/oxygen stream in suppressing production of hydrogen sulfide gas in downstream sewage lines. Adaptive Ozone Solutions, LLC, supplied the oxygen/ozone generation and injection system. Samples were analyzed both before and after oxygen/ozone injection. Hydrogen sulfide gas was continuously monitored at sewer stations downstream of Fox River Fiber. Results showed that with a very short contact time, effluent COD was reduced by over 15%. A simple kinetic model predicts that a contact time of fewer than 30 minutes could reduce COD by as much as 60%. In addition, downstream hydrogen sulfide gas production in the sewage mains was also better controlled, such that costly Bioxide applications could be reduced.

  1. Why Do Lithium-Oxygen Batteries Fail: Parasitic Chemical Reactions and Their Synergistic Effect.

    Science.gov (United States)

    Yao, Xiahui; Dong, Qi; Cheng, Qingmei; Wang, Dunwei

    2016-09-12

    As an electrochemical energy-storage technology with the highest theoretical capacity, lithium-oxygen batteries face critical challenges in terms of poor stabilities and low charge/discharge round-trip efficiencies. It is generally recognized that these issues are connected to the parasitic chemical reactions at the anode, electrolyte, and cathode. While the detailed mechanisms of these reactions have been studied separately, the possible synergistic effects between these reactions remain poorly understood. To fill in the knowledge gap, this Minireview examines literature reports on the parasitic chemical reactions and finds the reactive oxygen species a key chemical mediator that participates in or facilitates nearly all parasitic chemical reactions. Given the ubiquitous presence of oxygen in all test cells, this finding is important. It offers new insights into how to stabilize various components of lithium-oxygen batteries for high-performance operations and how to eventually materialize the full potentials of this promising technology.

  2. 20-Kw nitrogen diluent chemical oxygen-iodine laser

    Science.gov (United States)

    Yang, Tientsai T.; Bhowmik, Anup; Burde, David H.; Clark, Roy; Carroll, S.; Dickerson, Robert A.; Eblen, J.; Gylys, Vytas T.; Hsia, Y. C.; Humphreys, Richard H., Jr.; Moon, L. F.; Hurlock, Steve C.; Tomassian, A.

    2002-09-01

    A new Chemical Oxygen-Iodine Laser (COIL) has been developed and demonstrated at chlorine flow rates up to 1 gmol/s. The laser employs a cross flow jet oxygen generator operating with no diluent. The generator product flow enters the laser cavity at Mach 1 and is accelerated by mixing with 5 gmol/s, Mach 5 nitrogen diluent in an ejector nozzle array. The nitrogen also serves as the carrier for iodine. Vortex mixing is achieved through the use of mixing tabs at the nitrogen nozzle exit. Mixing approach design and analysis, including CFD analysis, led to the preferred nozzle configuration. The selected mixing enhancement design was tested in cold flow and the results are in good agreement with the CFD predictions. Good mixing was achieved within the desired cavity flow length of 20 cm and pressure recovery about 90 Torr was measured at the cavity exit. Finally, the design was incorporated into the laser and power extraction as high as 20 kw was measured at the best operating condition of 0.9 gmol/s. Stable resonator mode footprints showed desieable intensity profiles, which none of the sugar scoop profiles characteristic of the conventional COIL designs.

  3. Chitosan on Reducing Chemical Oxygen Demands in Laundry Waste Water

    Directory of Open Access Journals (Sweden)

    Tri Joko

    2016-09-01

    Full Text Available Laundry liquid waste contains several chemical substances in detergent raw materials such as phosphate, surfactants, ammonia, and total suspended solids. The existence of detergent in high concentrations and exceeds the quality standards that have been estabilished in a body of water can lead to cases of enviromental pollution in the form of increased turbidity an Chemical Oxygen Demands (COD levels. Therefore in order to maintain and to ensure the availabillity of water in terms of quality, it requires coagulation-flocculation process to laundry liquid waste before discharging into water bodies. This study aims to determine the decrease of COD levels and turbidity level in laundry liquid waste using chitosan coagulant in “X” laundry, Tembalang District, Semarang. The research is a quasi experimental study with pretest-posttest with control group research design with 6 times replication. The total samples are 60 in wich 24 tested for the levels of turbidity and 6 controls. The test results of Kruskal-Wallis with significance p-value < 0,05 indicates that dosage variation (p=0,000 gives different levels of COD and dosage variation (p=0,000 provide 755,97 mg/l and the advantage levels of turbidity before treatment was 516,20 NTU. The optimum dosage of chitosan coagulant is on the dose of 200 mg/l with the effectiveness decrease of COD levels and turbidity levels on 72,67% an 98,67% respectively.

  4. Atom interaction propensities of oxygenated chemical functions in crystal packings

    Directory of Open Access Journals (Sweden)

    Christian Jelsch

    2017-03-01

    Full Text Available The crystal contacts of several families of hydrocarbon compounds substituted with one or several types of oxygenated chemical groups were analyzed statistically using the Hirshfeld surface methodology. The propensity of contacts to occur between two chemical types is described with the contact enrichment descriptor. The systematic large enrichment ratios of some interactions like the O—H...O hydrogen bonds suggests that these contacts are a driving force in the crystal packing formation. The same statement holds for the weaker C—H...O hydrogen bonds in ethers, esters and ketones, in the absence of polar H atoms. The over-represented contacts in crystals of oxygenated hydrocarbons are generally of two types: electrostatic attractions (hydrogen bonds and hydrophobic interactions. While Cl...O interactions are generally avoided, in a minority of chloro-oxygenated hydrocarbons, significant halogen bonding does occur. General tendencies can often be derived for many contact types, but outlier compounds are instructive as they display peculiar or rare features. The methodology also allows the detection of outliers which can be structures with errors. For instance, a significant number of hydroxylated molecules displaying over-represented non-favorable oxygen–oxygen contacts turned out to have wrongly oriented hydroxyl groups. Beyond crystal packings with a single molecule in the asymmetric unit, the behavior of water in monohydrate compounds and of crystals with Z′ = 2 (dimers are also investigated. It was found in several cases that, in the presence of several oxygenated chemical groups, cross-interactions between different chemical groups (e.g. water/alcohols; alcohols/phenols are often favored in the crystal packings. While some trends in accordance with common chemical principles are retrieved, some unexpected results can however appear. For example, in crystals of alcohol–phenol compounds, the strong O—H...O hydrogen bonds between

  5. High-temperature langasite SAW oxygen sensor.

    Science.gov (United States)

    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.

  6. Natural Ores as Oxygen Carriers in Chemical Looping Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Hanjing; Siriwardane, Ranjani; Simonyi, Thomas; Poston, James

    2013-08-01

    Chemical looping combustion (CLC) is a combustion technology that utilizes oxygen from oxygen carriers (OC), such as metal oxides, instead of air to combust fuels. The use of natural minerals as oxygen carriers has advantages, such as lower cost and availability. Eight materials, based on copper or iron oxides, were selected for screening tests of CLC processes using coal and methane as fuels. Thermogravimetric experiments and bench-scale fixed-bed reactor tests were conducted to investigate the oxygen transfer capacity, reaction kinetics, and stability during cyclic reduction/oxidation reaction. Most natural minerals showed lower combustion capacity than pure CuO/Fe{sub 2}O{sub 3} due to low-concentrations of active oxide species in minerals. In coal CLC, chryscolla (Cu-based), magnetite, and limonite (Fe-based) demonstrated better reaction performances than other materials. The addition of steam improved the coal CLC performance when using natural ores because of the steam gasification of coal and the subsequent reaction of gaseous fuels with active oxide species in the natural ores. In methane CLC, chryscolla, hematite, and limonite demonstrated excellent reactivity and stability in 50-cycle thermogravimetric analysis tests. Fe{sub 2}O{sub 3}-based ores possess greater oxygen utilization but require an activation period before achieving full performance in methane CLC. Particle agglomeration issues associated with the application of natural ores in CLC processes were also studied by scanning electron microscopy (SEM).

  7. Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes

    Institute of Scientific and Technical Information of China (English)

    ZAYAS Pérez Teresa; GEISSLER Gunther; HERNANDEZ Fernando

    2007-01-01

    The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculatio and advanced oxidation processes(AOP)had been studied.The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H202,UVO3 and UV/H-H202/O3 processes was determined under acidic conditions.For each of these processes,different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater.Coffee wastewater is characterized by a high chemical oxygen demand(COD)and low total suspended solids.The outcomes of coffee wastewater reeatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD,color,and turbidity.It was found that a reductiOn in COD of 67%could be realized when the coffee wastewater was treated by chemical coagulation-flocculatlon witll lime and coagulant T-1.When coffee wastewater was treated by coagulation-flocculation in combination with UV/H202,a COD reduction of 86%was achieved,although only after prolonged UV irradiation.Of the three advanced oxidation processes considered,UV/H202,uv/03 and UV/H202/03,we found that the treatment with UV/H2O2/O3 was the most effective,with an efficiency of color,turbidity and further COD removal of 87%,when applied to the flocculated coffee wastewater.

  8. Chemical and structural changes in Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) lanthanide nickelates as a function of oxygen partial pressure at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Flura, Aurélien; Dru, Sophie; Nicollet, Clément; Vibhu, Vaibhav; Fourcade, Sébastien; Lebraud, Eric; Rougier, Aline; Bassat, Jean-Marc; Grenier, Jean-Claude, E-mail: grenier@icmcb-bordeaux.cnrs.fr

    2015-08-15

    The chemical stability of lanthanide nickelates Ln{sub 2}NiO{sub 4+δ} (Ln=La, Pr or Nd) has been studied in the temperature range 25–1300 °C, either in air or at low pO{sub 2} (down to 10{sup −4} atm). Thermal gravimetry analysis (TGA) measurements coupled with X-ray diffraction (XRD) characterization have shown that all compounds retain their K{sub 2}NiF{sub 4}-type structure in these conditions, while remaining over-stoichiometric in oxygen up to 1000 °C. Only Nd{sub 2}NiO{sub 4+δ} starts to decompose into Nd{sub 2}O{sub 3} and NiO above 1000 °C, at pO{sub 2}=10{sup −4} atm. In addition, a careful analysis of the lanthanide nickelates structural features has been performed by in situ XRD, as a function of temperature and pO{sub 2}. For all compounds, a structural transition has been always observed in the temperature range 200–400 °C, in air or at pO{sub 2}=10{sup −4} atm. In addition, their cell volume did not vary upon the variation of the oxygen partial pressure. Therefore, these materials do not exhibit a chemical expansion in these conditions, which is beneficial for a fuel cell application as cathode layers. Additional dilatometry measurements have revealed that a temperature as high as 950 °C for Pr{sub 2}NiO{sub 4+δ} or 1100 °C for La{sub 2}NiO{sub 4+δ} and Nd{sub 2}NiO{sub 4+δ} has to be reached in order to begin the sintering of the material particles, which is of primary importance to obtain an efficient electronic/ionic conduction in the corresponding designed cathode layers. Besides, excellent matching was found between the thermal expansion coefficients of lanthanide nickelates and SOFC electrolytes such as 8wt% yttria stabilized zirconia (8YSZ) or Ce{sub 0.8}Gd{sub 0.2}O{sub 2−δ} (GDC), at least from 400 °C up to 1400 °C in air or up to 1200 °C at pO{sub 2}=10{sup −4} atm. - Graphical abstract: This study reports the good chemical stability of oxygen overstoichiometric Ln2NiO4+δ(Ln = La, Pr or Nd) at high temperatures

  9. Recovery Act: Novel Oxygen Carriers for Coal-fueled Chemical Looping

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei-Ping; Cao, Yan

    2012-11-30

    Chemical Looping Combustion (CLC) could totally negate the necessity of pure oxygen by using oxygen carriers for purification of CO{sub 2} stream during combustion. It splits the single fuel combustion reaction into two linked reactions using oxygen carriers. The two linked reactions are the oxidation of oxygen carriers in the air reactor using air, and the reduction of oxygen carriers in the fuel reactor using fuels (i.e. coal). Generally metal/metal oxides are used as oxygen carriers and operated in a cyclic mode. Chemical looping combustion significantly improves the energy conversion efficiency, in terms of the electricity generation, because it improves the reversibility of the fuel combustion process through two linked parallel processes, compared to the conventional combustion process, which is operated far away from its thermo-equilibrium. Under the current carbon-constraint environment, it has been a promising carbon capture technology in terms of fuel combustion for power generation. Its disadvantage is that it is less mature in terms of technological commercialization. In this DOE-funded project, accomplishment is made by developing a series of advanced copper-based oxygen carriers, with properties of the higher oxygen-transfer capability, a favorable thermodynamics to generate high purity of CO{sub 2}, the higher reactivity, the attrition-resistance, the thermal stability in red-ox cycles and the achievement of the auto-thermal heat balance. This will be achieved into three phases in three consecutive years. The selected oxygen carriers with final-determined formula were tested in a scaled-up 10kW coal-fueled chemical looping combustion facility. This scaled-up evaluation tests (2-day, 8-hour per day) indicated that, there was no tendency of agglomeration of copper-based oxygen carriers. Only trace-amount of coke or carbon deposits on the copper-based oxygen carriers in the fuel reactor. There was also no evidence to show the sulphidization of oxygen

  10. Influence of oxygen on the chemical stage of radiobiological mechanism

    Science.gov (United States)

    Barilla, Jiří; Lokajíček, Miloš V.; Pisaková, Hana; Simr, Pavel

    2016-07-01

    The simulation of the chemical stage of radiobiological mechanism may be very helpful in studying the radiobiological effect of ionizing radiation when the water radical clusters formed by the densely ionizing ends of primary or secondary charged particle may form DSBs damaging DNA molecules in living cells. It is possible to study not only the efficiency of individual radicals but also the influence of other species or radiomodifiers (mainly oxygen) being present in water medium during irradiation. The mathematical model based on Continuous Petri nets (proposed by us recently) will be described. It makes it possible to analyze two main processes running at the same time: chemical radical reactions and the diffusion of radical clusters formed during energy transfer. One may study the time change of radical concentrations due to the chemical reactions running during diffusion process. Some orientation results concerning the efficiency of individual radicals in DSB formation (in the case of Co60 radiation) will be presented; the influence of oxygen present in water medium during irradiation will be shown, too.

  11. Highly Accurate Sensor for High-Purity Oxygen Determination Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this STTR effort, Los Gatos Research (LGR) and the University of Wisconsin (UW) propose to develop a highly-accurate sensor for high-purity oxygen determination....

  12. Detailed Chemical Kinetic Modeling of Diesel Combustion with Oxygenated Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Curran, H J; Fisher, E M; Glaude, P-A; Marinov, N M; Pitz, W J; Westbrook, C K; Flynn, P F; Durrett, R P; zur Loye, A O; Akinyemi, O C; Dryer, F L

    2000-01-11

    Emission standards for diesel engines in vehicles have been steadily reduced in recent years, and a great deal of research and development effort has been focused on reducing particulate and nitrogen oxide emissions. One promising approach to reducing emissions involves the addition of oxygen to the fuel, generally by adding an oxygenated compound to the normal diesel fuel. Miyamoto et al. [1] showed experimentally that particulate levels can be significantly reduced by adding oxygenated species to the fuel. They found the Bosch smoke number (a measure of the particulate or soot levels in diesel exhaust) falls from about 55% for conventional diesel fuel to less than 1% when the oxygen content of the fuel is above about 25% by mass, as shown in Figure 1. It has been well established that addition of oxygenates to automotive fuel, including both diesel fuel as well as gasoline, reduces NOx and CO emissions by reducing flame temperatures. This is the basis for addition of oxygenates to produce reformulated gasoline in selected portions of the country. Of course, this is also accompanied by a slight reduction in fuel economy. A new overall picture of diesel combustion has been developed by Dec [2], in which laser diagnostic studies identified stages in diesel combustion that had not previously been recognized. These stages are summarized in Figure 2. The evolution of the diesel spray is shown, starting as a liquid jet that vaporizes and entrains hot air from the combustion chamber. This relatively steady process continues as long as fuel is being injected. In particular, Dec showed that the fuel spray vaporizes and mixes with air and products of earlier combustion to provide a region in which a gas phase, premixed fuel-rich ignition and burn occurs. The products of this ignition are then observed experimentally to lead rapidly to formation of soot particles, which subsequently are consumed in a diffusion flame. Recently, Flynn et al. [3] used a chemical kinetic and

  13. Robust high temperature oxygen sensor electrodes

    DEFF Research Database (Denmark)

    Lund, Anders

    Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode ......-based electrodes and one porous electrode based on the perovskite-structured strontium and vanadiumdoped lanthanum chromium oxide (LSCV) were investigated. The porous electrodes were applied on yttrium-stabilised zirconium oxide (YSZ) substrates in a collaboration with the company PBI...

  14. Highly Oxygenated Monoterpenes from Eupatorium fortunei

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A pair of epimers of highly-oxygenated monoterpenes were isolated from the traditional Chinese medicine Eupatorium fortunei. Their structures were elucidated on the basis of the spectral analysis as (1R*, 2S*, 3R*, 4R*, 6S*)-1, 2, 3, 6-tetrehydroxy-p-menthane (1) and (1S*,2S*, 3S*, 4R*, 6R*)-1, 2, 3, 6-tetrehydroxy-p-menthane (2).

  15. Optimization of the determination of chemical oxygen demand in wastewaters.

    Science.gov (United States)

    Silva, Alexandra M E Viana da; Silva, Ricardo J N Bettencourt da; Camões, M Filomena G F C

    2011-08-12

    Chemical oxygen demand (COD) is one of the most relevant chemical parameters for the management of wastewater treatment facilities including the control of the quality of an effluent. The adequacy of decisions based on COD values relies on the quality of the measurements. Cost effective management of the minor sources of uncertainty can be applied to the analytical procedure without affecting measurement quality. This work presents a detailed assessment of the determination of COD values in wastewaters, according to ISO6060:1989 standard, which can support reduction of both measurement uncertainty and cost of analysis. This assessment includes the definition of the measurement traceability chain and the validation of the measurement procedure supported on sound and objective criteria. Detailed models of the measurement performance, including uncertainty, developed from the Differential Approach, were successfully validated by proficiency tests. The assumption of the measurement function linearity of the uncertainty propagation law was tested through the comparison with the numerical Kragten method. The gathered information supported the definition of strategies for measurement uncertainty or cost reduction. The developed models are available as electronic supplementary material, in an MS-Excel file, to be updated with the user's data.

  16. Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen

    Science.gov (United States)

    Opila, Elizabeth J.

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

  17. Real-Time Molecular Monitoring of Chemical Environment in ObligateAnaerobes during Oxygen Adaptive Response

    Energy Technology Data Exchange (ETDEWEB)

    Holman, Hoi-Ying N.; Wozei, Eleanor; Lin, Zhang; Comolli, Luis R.; Ball, David. A.; Borglin, Sharon; Fields, Matthew W.; Hazen, Terry C.; Downing, Kenneth H.

    2009-02-25

    Determining the transient chemical properties of the intracellular environment canelucidate the paths through which a biological system adapts to changes in its environment, for example, the mechanisms which enable some obligate anaerobic bacteria to survive a sudden exposure to oxygen. Here we used high-resolution Fourier Transform Infrared (FTIR) spectromicroscopy to continuously follow cellular chemistry within living obligate anaerobes by monitoring hydrogen bonding in their cellular water. We observed a sequence of wellorchestrated molecular events that correspond to changes in cellular processes in those cells that survive, but only accumulation of radicals in those that do not. We thereby can interpret the adaptive response in terms of transient intracellular chemistry and link it to oxygen stress and survival. This ability to monitor chemical changes at the molecular level can yield important insights into a wide range of adaptive responses.

  18. Chemical-Looping Combustion and Gasification of Coals and Oxygen Carrier Development: A Brief Review

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2015-09-01

    Full Text Available Chemical-looping technology is one of the promising CO2 capture technologies. It generates a CO2 enriched flue gas, which will greatly benefit CO2 capture, utilization or sequestration. Both chemical-looping combustion (CLC and chemical-looping gasification (CLG have the potential to be used to generate power, chemicals, and liquid fuels. Chemical-looping is an oxygen transporting process using oxygen carriers. Recently, attention has focused on solid fuels such as coal. Coal chemical-looping reactions are more complicated than gaseous fuels due to coal properties (like mineral matter and the complex reaction pathways involving solid fuels. The mineral matter/ash and sulfur in coal may affect the activity of oxygen carriers. Oxygen carriers are the key issue in chemical-looping processes. Thermogravimetric analysis (TGA has been widely used for the development of oxygen carriers (e.g., oxide reactivity. Two proposed processes for the CLC of solid fuels are in-situ Gasification Chemical-Looping Combustion (iG-CLC and Chemical-Looping with Oxygen Uncoupling (CLOU. The objectives of this review are to discuss various chemical-looping processes with coal, summarize TGA applications in oxygen carrier development, and outline the major challenges associated with coal chemical-looping in iG-CLC and CLOU.

  19. High-Pressure Oxygen Concentrator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA desires to generate and store gases including oxygen and nitrogen at sub-critical conditions as a part of its lunar and spacecraft atmospheric systems. Oxygen...

  20. High-Pressure Oxygen Concentrator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA desires to generate and store gases including oxygen and nitrogen at sub-critical conditions as a part of its lunar and spacecraft atmospheric systems. Oxygen...

  1. Fabrication and processing of next-generation oxygen carrier materials for chemical looping combustion

    Energy Technology Data Exchange (ETDEWEB)

    Nadarajah, Arunan [Univ. of Toledo, OH (United States)

    2017-04-26

    Among numerous methods of controlling the global warming effect, Chemical Looping Combustion is known to be the most viable option currently. A key factor to a successful chemical looping process is the presence of highly effective oxygen carriers that enable fuel combustion by going through oxidation and reduction in the presence of air and fuel respectively. In this study, CaMnO3-δ was used as the base material and doped on the A-site (Sr or La) and B-site (Fe, Ti, Zn and Al) by 10 mol % of dopants. Solid state reaction followed by mechanical extrusion (optimized paste formula) was used as the preparation method A series of novel doped perovskite-type oxygen carrier particles (CaxLa (Or Sa)1-x Mn1-yByO3-δ (B-site = Fe, Ti, Al, or Zr)) were synthesized by the proposed extrusion formula. The produced samples were characterized with XRD, SEM, BET and TGA techniques. According to the results obtained from TGA analysis, the oxygen capacity of the samples ranged between 1.2 for CLMZ and 1.75 for CSMF. Reactivity and oxygen uncoupling behaviors of the prepared samples were also evaluated using a fluidized bed chemical looping reactor using methane as the fuel at four different temperatures (800, 850, 900, 950 °C). All of the oxygen carriers showed oxygen uncoupling behavior and they were able to capture and release oxygen. Mass-based conversion of the perovskites was calculated and temperature increase proved to increase the mass-based conversion rate in all of the samples under study. Gas yield was calculated at 950 °C as well, and results showed that CLMZ, CM and CSMF showed 100% gas yields and CLMF and CSMZ showed approximately 85% yield in fluidized bed reactor, which is a high and acceptable quantity. Based on extended reactor tests the modified calcium manganese perovskite structures (CSMF) can be a good candidate for future pilot tests.

  2. Numerical investigation of the role of clustering during oxygen-carrier regeneration in Chemical Looping Combustion

    Science.gov (United States)

    Goyal, Himanshu; Pepiot, Perrine

    2016-11-01

    In the air-reactor of a dual-bed Chemical Looping Combustion (CLC) system, the spent oxygen-carrier, in the form of metal or reduced metal oxide, is oxidized with air, typically in a high velocity riser reactor. Such a configuration provides challenging modeling issues, as the granular flow is characterized by a highly fluctuating solid volume fraction due to the formation of dense clusters. This may strongly affect the solid residence time in the air-reactor, and therefore, the extent of the oxygen-carrier regeneration and ultimately, the overall reactivity of the carrier in the fuel reactor. Here, we investigate how clustering impacts gas-solid chemical reactions in the reactor using a detailed Lagrange-Euler computational framework. The simulations account for both mass and heat transfer between the gas phase and the metal oxide particles, and the evolution of oxygen content of the metal oxide particles, or equivalently, their degree of oxidation. Two particle models of different complexity are considered. Results are analyzed to quantify the relative importance on the regeneration process of the reactor hydrodynamics. This material is based upon work supported by the National Science Foundation under Grant No. CBET-1638837.

  3. Oxygen vacancy promoted methane partial oxidation over iron oxide oxygen carriers in the chemical looping process.

    Science.gov (United States)

    Cheng, Zhuo; Qin, Lang; Guo, Mengqing; Xu, Mingyuan; Fan, Jonathan A; Fan, Liang-Shih

    2016-11-30

    We perform ab initio DFT+U calculations and experimental studies of the partial oxidation of methane to syngas on iron oxide oxygen carriers to elucidate the role of oxygen vacancies in oxygen carrier reactivity. In particular, we explore the effect of oxygen vacancy concentration on sequential processes of methane dehydrogenation, and oxidation with lattice oxygen. We find that when CH4 adsorbs onto Fe atop sites without neighboring oxygen vacancies, it dehydrogenates with CHx radicals remaining on the same site and evolves into CO2via the complete oxidation pathway. In the presence of oxygen vacancies, on the other hand, the formed methyl (CH3) prefers to migrate onto the vacancy site while the H from CH4 dehydrogenation remains on the original Fe atop site, and evolves into CO via the partial oxidation pathway. The oxygen vacancies created in the oxidation process can be healed by lattice oxygen diffusion from the subsurface to the surface vacancy sites, and it is found that the outward diffusion of lattice oxygen atoms is more favorable than the horizontal diffusion on the same layer. Based on the proposed mechanism and energy profile, we identify the rate-limiting steps of the partial oxidation and complete oxidation pathways. Also, we find that increasing the oxygen vacancy concentration not only lowers the barriers of CH4 dehydrogenation but also the cleavage energy of Fe-C bonds. However, the barrier of the rate-limiting step cannot further decrease when the oxygen vacancy concentration reaches 2.5%. The fundamental insight into the oxygen vacancy effect on CH4 oxidation with iron oxide oxygen carriers can help guide the design and development of more efficient oxygen carriers and CLPO processes.

  4. High-resolution oxygen-17 NMR of solid silicates

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, K.T.; Wu, Y.; Chmelka, B.F. (Lawrence Berkeley Lab., CA (USA)); Stebbins, J. (Stanford Univ, CA (USA)); Pines, A. (Univ. of California, Berkeley (USA))

    1991-01-02

    Several{sup 17}O-enriched silicates were studied by use of dynamic angle spinning (DAS) and double rotation (DOR) nuclear magnetic resonance spectroscopy. These methods average away second-order quadrupolar interactions by reorienting a sample about a time-dependent axis, thereby yielding high-resolution spectra of oxygen-17 nuclei. A narrow spectral line is observed for each distinct oxygen site at the sum of the isotropic chemical shift and the field-dependent isotropic second-order quadrupolar shift. Resolution is increased by up to 2 orders of magnitude compared to conventional magic angle spinning (MAS) spectra. Crystallographically inequivalent oxygen are now observable as distinct resonances in spectra of polycrystalline silicates such as diopside (CaMgSi{sub 2}{sup 17}O{sub 6}), wollastonite (CaSi{sup 17}O{sub 3}), larnite (Ca{sub 2}Si{sup 17}O{sub 4}), and forsterite (Mg{sub 2}Si{sup 17}O{sub 4}).

  5. Chemical looping combustion of biomass-derived syngas using ceria-supported oxygen carriers.

    Science.gov (United States)

    Huang, H B; Aisyah, L; Ashman, P J; Leung, Y C; Kwong, C W

    2013-07-01

    Cu, Ni and Fe oxides supported on ceria were investigated for their performance as oxygen carriers during the chemical looping combustion of biomass-derived syngas. A complex gas mixture containing CO, H2, CO2, CH4 and other hydrocarbons was used to simulate the complex fuel gas environment derived from biomass gasification. Results show that the transfer of the stored oxygen into oxidants for the supported Cu and Ni oxides at 800°C for the combustion of syngas was effective (>85%). The unsupported Cu oxide showed high oxygen carrying capacity but particle sintering was observed at 800°C. A reaction temperature of 950°C was required for the supported Fe oxides to transfer the stored oxygen into oxidants effectively. Also, for the complex fuel gas environment, the supported Ni oxide was somewhat effective in reforming CH4 and other light hydrocarbons into CO, which may have benefits for the reduction of tar produced during biomass pyrolysis.

  6. High Energy Density aluminum/oxygen cell

    Science.gov (United States)

    Rudd, E. J.; Gibbons, D. W.

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell, an example of which is the metal/air cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, with high energy and power densities, environmentally acceptable and having a large, established industrial base for production and distribution. An aluminum/oxygen system is currently under development for a prototype unmanned, undersea vehicle (UUV) for the US navy and recent work has focussed upon low corrosion aluminum alloys, and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from 5 to 150 mA/cm 2 have been identified, such materials being essential to realize mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 h in a large scale, half-cell system.

  7. Oxygen ion energization observed at high altitudes

    Directory of Open Access Journals (Sweden)

    M. Waara

    2010-04-01

    Full Text Available We present a case study of significant heating (up to 8 keV perpendicular to the geomagnetic field of outflowing oxygen ions at high altitude (12 RE above the polar cap. The shape of the distribution functions indicates that most of the heating occurs locally (within 0.2–0.4 RE in altitude. This is a clear example of local ion energization at much higher altitude than usually reported. In contrast to many events at lower altitudes, it is not likely that the locally observed wave fields can cause the observed ion energization. Also, it is not likely that the ions have drifted from some nearby energization region to the point of observation. This suggests that additional fundamentally different ion energization mechanisms are present at high altitudes. One possibility is that the magnetic moment of the ions is not conserved, resulting in slower outflow velocities and longer time for ion energization.

  8. Using gas flux to estimate biological and chemical sediment oxygen demand in oil sands-affected wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Gardner Costa, J.; Slama, C.; Ciborowski, J. [Windsor Univ., ON (Canada)

    2010-07-01

    The constituents of oil sands process-affected (OSPM) wetlands include high salinity, conductivity and naphthenic acid concentrations. These constituents are expected to strain microbial communities and change methane and carbon dioxide flux rates as well as sediment oxygen consumption compared to fresher, reference wetland sites. Four OSPM and 4 reference wetlands were examined during the summers of 2009 and 2010 to determine if carbon loss in the form of sediment-associated microbial respiration differs between OSPM and reference wetlands. The study showed that OSPM wetlands release about 10 times less methane than reference wetlands. Sediment oxygen demand (SOD) was measured in 2009 and gas flux estimates of carbon dioxide were used to estimate biological sediment oxygen consumption (BSOC). Chemical sediment oxygen demand (CSOD) was estimated by subtracting BSOC from total SOD. SOD rates were found to be two times higher in OSPM wetlands than reference. CSOD was higher than biologically consumed oxygen for both wetland classes. Although microbial activity in OSPM wetlands may be lower, more oxygen is consumed in OSPM than in reference wetlands. The reclamation of boreal wetlands in the Alberta Athabasca region requires carbon accrual. Less microbial activity may promote carbon accumulation within OSPM wetlands. However, the wetland's sediment layer may have less organic input as a result of high chemical oxygen consumption because it limits benthos respiration.

  9. Chemical exposure-response relationship between air pollutants and reactive oxygen species in the human respiratory tract

    OpenAIRE

    Lakey, Pascale S. J.; Thomas Berkemeier; Haijie Tong; Arangio, Andrea M.; Kurt Lucas; Ulrich Pöschl; Manabu Shiraiwa

    2016-01-01

    Air pollution can cause oxidative stress and adverse health effects such as asthma and other respiratory diseases, but the underlying chemical processes are not well characterized. Here we present chemical exposure-response relations between ambient concentrations of air pollutants and the production rates and concentrations of reactive oxygen species (ROS) in the epithelial lining fluid (ELF) of the human respiratory tract. In highly polluted environments, fine particulate matter (PM2.5) con...

  10. Evaluation of Oxygen Concentrators and Chemical Oxygen Generators at Altitude and Temperature Extremes

    Science.gov (United States)

    2015-04-22

    insulated and is supplied with a nylon cover for further insulation. A pin attached to a wire is pulled to activate the device. Oxygen begins to flow... nylon cover for additional insulation. The device has two pins that must be pulled to initiate the reaction process. Oxygen flow begins seconds

  11. Nanocomposite oxygen carriers for chemical-looping combustion of sulfur-contaminated synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Rahul D. Solunke; Goetz Veser [United States Department of Energy, Pittsburgh, PA (United States). National Energy Technology Laboratory

    2009-09-15

    Chemical-looping combustion (CLC) is an emerging technology for clean combustion. We have previously demonstrated that the embedding of metal nanoparticles into a nanostructured ceramic matrix can result in unusually active and sinter-resistant nanocomposite oxygen carrier materials for CLC, which combine the high reactivity of metals with the high-temperature stability of ceramics. In the present study, we investigate the effect of H{sub 2}S in a typical coal-derived syngas on the stability and redox kinetics of Ni- and Cu-based nanostructured oxygen carriers. Both carriers show excellent structural stability and only mildly changed redox kinetics upon exposure to H{sub 2}S, despite a significant degree of sulfide formation. Surprisingly, partial sulfidation of the support results in a strong increase in oxygen carrier capacity in both cases because of the addition of a sulfide-sulfate cycle. Overall, the carriers show great potential for use in CLC of high-sulfur fuels. 21 refs., 13 figs. 1 tab.

  12. Correlating Biochemical and Chemical Oxygen Demand of Effluents

    African Journals Online (AJOL)

    F. K. Attiogbe1, Mary Glover-Amengor2 and K. T. Nyadziehe3

    oxygen demand (COD) of effluents from selected industries in the Kumasi Metropolis to ... comprehensiveness of the approach to solve the problem of wastewater disposal. .... GGL where higher BOD5 values were registered when spent yeast was .... Wastewater Engineering: Treatment, disposal and reuse, 3rd edn.

  13. Syngas Generation from Methane Using a Chemical-Looping Concept: A Review of Oxygen Carriers

    Directory of Open Access Journals (Sweden)

    Kongzhai Li

    2013-01-01

    Full Text Available Conversion of methane to syngas using a chemical-looping concept is a novel method for syngas generation. This process is based on the transfer of gaseous oxygen source to fuel (e.g., methane by means of a cycling process using solid oxides as oxygen carriers to avoid direct contact between fuel and gaseous oxygen. Syngas is produced through the gas-solid reaction between methane and solid oxides (oxygen carriers, and then the reduced oxygen carriers can be regenerated by a gaseous oxidant, such as air or water. The oxygen carrier is recycled between the two steps, and the syngas with a ratio of H2/CO = 2.0 can be obtained successively. Air is used instead of pure oxygen allowing considerable cost savings, and the separation of fuel from the gaseous oxidant avoids the risk of explosion and the dilution of product gas with nitrogen. The design and elaboration of suitable oxygen carriers is a key issue to optimize this method. As one of the most interesting oxygen storage materials, ceria-based and perovskite oxides were paid much attention for this process. This paper briefly introduced the recent research progresses on the oxygen carriers used in the chemical-looping selective oxidation of methane (CLSOM to syngas.

  14. Rapid hydrogen and oxygen atom transfer by a high-valent nickel-oxygen species

    NARCIS (Netherlands)

    Corona, Teresa; Draksharapu, Apparao; Padamati, Sandeep K; Gamba, Ilaria; Martin-Diaconescu, Vlad; Acuña-Parés, Ferran; Browne, Wesley R; Company, Anna

    2016-01-01

    Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed towards the characterization of the biologically relevant terminal manganese-oxygen and

  15. Rapid hydrogen and oxygen atom transfer by a high-valent nickel-oxygen species

    NARCIS (Netherlands)

    Corona, Teresa; Draksharapu, Apparao; Padamati, Sandeep K; Gamba, Ilaria; Martin-Diaconescu, Vlad; Acuña-Parés, Ferran; Browne, Wesley R; Company, Anna

    2016-01-01

    Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed towards the characterization of the biologically relevant terminal manganese-oxygen and ir

  16. Regenerable mixed copper-iron-inert support oxygen carriers for solid fuel chemical looping combustion process

    Energy Technology Data Exchange (ETDEWEB)

    Siriwardane, Ranjani V.; Tian, Hanjing

    2016-12-20

    The disclosure provides an oxygen carrier for a chemical looping cycle, such as the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The oxygen carrier is comprised of at least 24 weight % (wt %) CuO, at least 10 wt % Fe2O3, and an inert support, and is typically a calcine. The oxygen carrier exhibits a CuO crystalline structure and an absence of iron oxide crystalline structures under XRD crystallography, and provides an improved and sustained combustion reactivity in the temperature range of 600.degree. C.-1000.degree. C. particularly for solid fuels such as carbon and coal.

  17. Sodium-Oxygen Batteries: A Comparative Review from Chemical and Electrochemical Fundamentals to Future Perspective.

    Science.gov (United States)

    Yadegari, Hossein; Sun, Qian; Sun, Xueliang

    2016-09-01

    Alkali metal-oxygen (Li-O2 , Na-O2 ) batteries have attracted a great deal of attention recently due to their high theoretical energy densities, comparable to gasoline, making them attractive candidates for application in electrical vehicles. However, the limited cycling life and low energy efficiency (high charging overpotential) of these cells hinder their commercialization. The Li-O2 battery system has been extensively studied in this regard during the past decade. Compared to the numerous reports of Li-O2 batteries, the research on Na-O2 batteries is still in its infancy. Although, Na-O2 batteries show a number of attractive properties such as low charging overpotential and high round-trip energy efficiency, their cycling life is currently limited to a few tens of cycles. Therefore, understanding the chemistry behind Na-O2 cells is critical towards enhancing their performance and advancing their development. Chemical and electrochemical reactions of Na-O2 batteries are reviewed and compared with those of Li-O2 batteries in the present review, as well as recent works on the chemical composition and morphology of the discharge products in these batteries. Furthermore, the determining kinetics factors for controlling the chemical composition of the discharge products in Na-O2 cells are discussed and the potential research directions toward improving Na-O2 cells are proposed.

  18. Oxygen abundance in local disk and bulge: chemical evolution with a strictly universal IMF

    Science.gov (United States)

    Caimmi, R.; Milanese, E.

    2009-09-01

    This paper has two parts: one about observational constraints related to the empirical differential oxygen abundance distribution (EDOD), and the other about inhomogeneous models of chemical evolution, in particular the theoretical differential oxygen abundance distribution (TDOD). In the first part, the EDOD is deduced from subsamples related to two different samples involving (i) N=532 solar neighbourhood (SN) stars within the range, -1.5Prochaska et al. in Astron. J. 120:2513, 2000); (3) the fit to thin disk data implies an oxygen abundance range similar to its thick disk counterpart, with the extension of conclusion (2) to the thin disk, and the evolution of the thick + thin disk as a whole (Haywood in Mon. Not. R. Astron. Soc. 388:1175, 2008) cannot be excluded; (4) leaving outside the outer halo, a fit to the data related to different environments is provided by models with a strictly universal IMF but different probabilities of a region being active, which implies different global efficiencies of the star formation rate; (5) a special case of stellar migration across the disk can be described by models with enhanced star formation, where a fraction of currently observed SN stars were born in situ and a comparable fraction is due to the net effect of stellar migration, according to recent results based on high-resolution N-body + smooth particle hydrodynamics simulations (Ro\\vskar et al. in Astrophys. J. Lett. 684:L79, 2008).

  19. High resolution NMR theory and chemical applications

    CERN Document Server

    Becker, Edwin D

    1969-01-01

    High Resolution NMR: Theory and Chemical Applications focuses on the applications of nuclear magnetic resonance (NMR), as well as chemical shifts, lattices, and couplings. The book first offers information on the theory of NMR, including nuclear spin and magnetic moment, spin lattice relaxation, line widths, saturation, quantum mechanical description of NMR, and ringing. The text then ponders on instrumentation and techniques and chemical shifts. Discussions focus on the origin of chemical shifts, reference compounds, empirical correlations of chemical shifts, modulation and phase detection,

  20. Chemical stability of high-temperature superconductors

    Science.gov (United States)

    Bansal, Narottam P.

    1992-01-01

    A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

  1. Oxygen Handling and Cooling Options in High Temperature Electrolysis Plants

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal; J. Stephen Herring

    2008-07-01

    Idaho National Laboratory is working on a project to generate hydrogen by high temperature electrolysis (HTE). In such an HTE system, safety precautions need to be taken to handle high temperature oxygen at ~830°C. This report is aimed at addressing oxygen handling in a HTE plant.. Though oxygen itself is not flammable, most engineering material, including many gases and liquids, will burn in the presence of oxygen under some favorable physicochemical conditions. At present, an absolute set of rules does not exist that can cover all aspects of oxygen system design, material selection, and operating practices to avoid subtle hazards related to oxygen. Because most materials, including metals, will burn in an oxygen-enriched environment, hazards are always present when using oxygen. Most materials will ignite in an oxygen-enriched environment at a temperature lower than that in air, and once ignited, combustion rates are greater in the oxygen-enriched environment. Even many metals, if ignited, burn violently in an oxygen-enriched environment. However, these hazards do not preclude the operations and systems involving oxygen. Oxygen can be safely handled and used if all the materials in a system are not flammable in the end-use environment or if ignition sources are identified and controlled. In fact, the incidence of oxygen system fires is reported to be low with a probability of about one in a million. This report is a practical guideline and tutorial for the safe operation and handling of gaseous oxygen in high temperature electrolysis system. The intent is to provide safe, practical guidance that permits the accomplishment of experimental operations at INL, while being restrictive enough to prevent personnel endangerment and to provide reasonable facility protection. Adequate guidelines are provided to govern various aspects of oxygen handling associated with high temperature electrolysis system to generate hydrogen. The intent here is to present acceptable

  2. Limited Influence of Oxygen on the Evolution of Chemical Diversity in Metabolic Networks

    Directory of Open Access Journals (Sweden)

    Kazuhiro Takemoto

    2013-10-01

    Full Text Available Oxygen is thought to promote species and biomolecule diversity. Previous studies have suggested that oxygen expands metabolic networks by acquiring metabolites with different chemical properties (higher hydrophobicity, for example. However, such conclusions are typically based on biased evaluation, and are therefore non-conclusive. Thus, we re-investigated the effect of oxygen on metabolic evolution using a phylogenetic comparative method and metadata analysis to reduce the bias as much as possible. Notably, we found no difference in metabolic network expansion between aerobes and anaerobes when evaluating phylogenetic relationships. Furthermore, we showed that previous studies have overestimated or underestimated the degrees of differences in the chemical properties (e.g., hydrophobicity between oxic and anoxic metabolites in metabolic networks of unicellular organisms; however, such overestimation was not observed when considering the metabolic networks of multicellular organisms. These findings indicate that the contribution of oxygen to increased chemical diversity in metabolic networks is lower than previously thought; rather, phylogenetic signals and cell-cell communication result in increased chemical diversity. However, this conclusion does not contradict the effect of oxygen on metabolic evolution; instead, it provides a deeper understanding of how oxygen contributes to metabolic evolution despite several limitations in data analysis methods.

  3. Are macroinvertebrates in high altitude streams affected by oxygen deficiency?

    DEFF Research Database (Denmark)

    Jacobsen, Dean; Rostgaard, S.; Vásconez, J. J.

    2003-01-01

    conditions. However, this fails to take into account that oxygen solubility declines with decreasing atmospheric pressure, which may be of importance at high altitudes. 2. Based on samples of macroinvertebrate benthos and in situ measurements of respiratory oxygen demand of macroinvertebrates in small...

  4. Kinetic bottlenecks to chemical exchange rates for deep-sea animals – Part 1: Oxygen

    Directory of Open Access Journals (Sweden)

    E. T. Peltzer

    2012-10-01

    Full Text Available Ocean warming will reduce dissolved oxygen concentrations which can pose challenges to marine life. Oxygen limits are traditionally reported simply as a static concentration thresholds with no temperature, pressure or flow rate dependency. Here we treat the oceanic oxygen supply potential for heterotrophic consumption as a dynamic molecular exchange problem analogous to familiar gas exchange processes at the sea surface. A combination of the purely physico-chemical oceanic properties temperature, hydrostatic pressure, and oxygen concentration defines the ability of the ocean to supply oxygen to any given animal. This general oceanic oxygen supply potential is modulated by animal specific properties such as the diffusive boundary layer thickness to define and limit maximal oxygen supply rates. Here we combine all these properties into formal, mechanistic equations defining novel oceanic properties that subsume various relevant classical oceanographic parameters to better visualize, map, comprehend, and predict the impact of ocean deoxygenation on aerobic life. By explicitly including temperature and hydrostatic pressure into our quantities, various ocean regions ranging from the cold deep-sea to warm, coastal seas can be compared. We define purely physico-chemical quantities to describe the oceanic oxygen supply potential, but also quantities that contain organism-specific properties which in a most generalized way describe general concepts and dependencies. We apply these novel quantities to example oceanic profiles around the world and find that temperature and pressure dependencies of diffusion and partial pressure create zones of greatest physical constriction on oxygen supply typically at around 1000 m depth, which coincides with oxygen concentration minimum zones. In these zones, which comprise the bulk of the world ocean, ocean warming and deoxygenation have a clear negative effect for aerobic life. In some shallow and warm waters the

  5. Chemical expansion affected oxygen vacancy stability in different oxide structures from first principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; Weber, William J.

    2015-03-01

    We study the chemical expansion for neutral and charged oxygen vacancies in fluorite, rocksalt, perovskite and pyrochlores materials using first principles calculations. We show that the neutral oxygen vacancy leads to lattice expansion whereas the charged vacancy leads to lattice contraction. In addition, we show that there is a window of strain within which an oxygen vacancy is stable; beyond that range, the vacancy can become unstable. Using CeO2|ZrO2 interface structure as an example, we show that the concentration of oxygen vacancies can be manipulated via strain, and the vacancies can be preferentially stabilized. These results could serve as guiding principles in predicting oxygen vacancy stability in strained systems and in the design of vacancy stabilized materials.

  6. Redox energetics of novel perovskite-type oxygen carriers for chemical looping reforming

    OpenAIRE

    2012-01-01

    The present work focuses on the redox energetics of novel perovskite-type oxygen carriers for chemical looping reforming. The aim of this study is to increase the level of knowledge on the redox characteristics of materials for possible applications as the oxygen carriers for the chemical looping processes. Here we focus on the perovskite-type oxides (ABO3) with lanthanum on the A-site and first row transition metals on the B-site since first row transition metals normally have more than ...

  7. Performance of an electrochemical COD (chemical oxygen demand) sensor with an electrode-surface grinding unit.

    Science.gov (United States)

    Geun Jeong, Bong; Min Yoon, Seok; Ho Choi, Chang; Koang Kwon, Kil; Sik Hyun, Moon; Heui Yi, Dong; Soo Park, Hyung; Kim, Mia; Joo Kim, Hyung

    2007-12-01

    An electrochemical COD (chemical oxygen demand) sensor using an electrode-surface grinding unit was investigated. The electrolyzing (oxidizing) action of copper on an organic species was used as the basis of the COD measuring sensor. Using a simple three-electrode cell and a surface grinding unit, the organic species is activated by the catalytic action of copper and oxidized at a working electrode, poised at a positive potential. When synthetic wastewater was fed into the system, the measured Coulombic yields were found to be dependent on the COD of the synthetic wastewater. A linear correlation between the Coulombic yields and the COD of the synthetic wastewater was established (10-1000 mg L(-1)) when the electrode-surface grinding procedure was activated briefly at 8 h intervals. When various kinds of wastewater samples obtained from various sewage treatment plants were measured, linear correlations (r(2)> or = 0.92) between the measured EOD (electrochemical oxygen demand) value and COD of the samples were observed. At a practical wastewater treatment plant, the measurement system was successfully operated with high accuracy and good stability over 3 months. These experimental results show that the application of the measurement system would be a rapid and practical method for the determination of COD in water industries.

  8. Protozoan biomass relation to nutrient and chemical oxygen demand removal in activated sludge mixed liquor.

    Science.gov (United States)

    Akpor, Oghenerobor B; Momba, Maggy N B; Okonkwo, Jonathan O

    2008-08-01

    The relationship between biomass concentration to nutrient and chemical oxygen demand (COD) removal in mixed liquor supplemented with sodium acetate was investigated, using three protozoan isolates and three different initial biomass concentrations (10(1), 10(2) and 10(3) cells/mL). The study was carried out in a shaking flask environment at a shaking speed of 100 rpm for 96 h at 25 degrees C. Aliquot samples were taken periodically for the determination of phosphate, nitrate, COD and dissolved oxygen, using standard methods. The results revealed remarkable phosphate removal of 82-95% at biomass concentration of 10(3)cells/mL. A high nitrate removal of over 87% was observed at all initial biomass concentration in mixed liquor. There was an observed COD increase of over 50% in mixed liquor in at the end of 96-h incubation and this was irrespective of initial biomass concentration used for inoculation. The study shows the trend in nutrient and COD removal at different biomass concentrations of the test isolates in mixed liquor.

  9. On the oxygen and nitrogen chemical abundances and the evolution of the "green pea" galaxies

    CERN Document Server

    Amorín, Ricardo O; Vílchez, J M

    2010-01-01

    We have investigated the oxygen and nitrogen chemical abundances in extremely compact star-forming galaxies with redshifts between $\\sim$0.11-0.35, popularly referred to as "green peas". Direct and strong-line methods sensitive to the N/O ratio applied to their SDSS spectra reveals that these systems are genuine metal-poor galaxies, with mean oxygen abundances 20% solar. At a given metallicity these galaxies display systematically large N/O ratios compared to normal galaxies, which can explain the strong difference between our metallicities measurements and previous ones. While their N/O ratios follow the relation with stellar mass of local star-forming galaxies in the SDSS, we find that the mass--metallicity relation of the "green peas" is offset $\\ga$0.3 dex to lower metallicities. We argue that recent interaction-induced inflow of gas, possibly coupled with a selective metal-rich gas loss, driven by supernova winds, may explain our findings and the known galaxy properties, namely high specific star formati...

  10. Development of a highly sensitive galvanic cell oxygen sensor.

    Science.gov (United States)

    Ogino, H; Asakura, K

    1995-02-01

    A highly sensitive galvanic cell oxygen sensor was successfully developed for determining parts per billion of oxygen in high purity gases such as nitrogen, argon, etc. The response of this improved sensor was proportional in the range of oxygen concentrations from 10.0 ppm to the detection limit. The response speed in this study was improved to within 90 sec for a 90% response. The detection limit was tentatively found to be less than 0.4 ppb corresponding to S N = 2 .

  11. CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2

    Energy Technology Data Exchange (ETDEWEB)

    Peizheng Zhou

    2001-10-26

    There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the small-diameter ({approx}1/32 inch) catalyst particles have enough mechanical strength to avoid loss by attrition. However, all of the State Of The Art (SOTA) catalysts and advanced catalysts for the purpose are low in mechanical strength. The patented carbon-coated catalyst technology developed in our laboratory converts catalyst particles with low mechanical strength to strong catalysts suitable for ebullated bed application. This R&D program is concerned with the modification on the mechanical strength of the SOTA and advanced catalysts so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. The objective of this R&D program is to study the technical and economic feasibility of selective production of high-value oxygenated chemicals from synthesis gas and CO{sub 2} mixed feed in an ebullated bed reactor using carbon-coated catalyst particles.

  12. CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2

    Energy Technology Data Exchange (ETDEWEB)

    Peizheng Zhou

    2000-11-17

    There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the small-diameter ({approx} 1/32 inch) catalyst particles have enough mechanical strength to avoid loss by attrition. However, all of the State Of The Art (SOTA) catalysts and advanced catalysts for the purpose are low in mechanical strength. The patented carbon-coated catalyst technology developed in our laboratory converts catalyst particles with low mechanical strength to strong catalysts suitable for ebullated bed application. This R&D program is concerned with the modification on the mechanical strength of the SOTA and advanced catalysts so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. The objective of this R&D program is to study the technical and economic feasibility of selective production of high-value oxygenated chemicals from synthesis gas and CO{sub 2} mixed feed in an ebullated bed reactor using carbon-coated catalyst particles.

  13. [Relation between oxygen uptake rate and biosorption of activated sludge against chemical substance].

    Science.gov (United States)

    Mihara, Yuichi; Inoue, Tatsuaki; Yokota, Katsushi

    2005-02-01

    In this study, the elucidation of the toxicity mechanism was undertaken regarding the IC(50) of the oxygen uptake rate (OUR) with relevance to the biosorption as a toxicity evaluation of chemical substances for activated sludge (AS). At the IC(50) oflinear alkyl benzene sulfonate (LAS), alkyl ethoxy sulfonate (AES), alpha-olefine sulfonate (AOS), sodium dodecyl sulfate (SDS), formaldehyde (FA), benzalkonium chloride (BZaC), benzethonium chloride (BZeC), rhodamine 6G (R-6G) and fuchsine (Fuc) in which the IC(50) belonged to the 100-1000 mg/l group, when it was compared with CV and MG. In ethanol (EtOH), isopropanol (PrOH), nile blue (NB), evans blue (EB), methylene blue (MB), methyl orange (MO), paraquat (PQ), chlorophyllin (Chl) and auramine (Aur), the IC(50) was large, and the biosorption of AS was weak at 0-15%. The biosorption of MG for AS followed the adsorption isotherm equation Y=0.002X(0.511) of Freundrich. The correlation coefficient was gamma=0.998 (n=8), and a very high correlation was obtained. In the qualitative OUR curve by AS pretreated with MG or CV which belonged to the IC(50) small group, the inhibition of remarkable OUR was observed. Therefore, the findings of the present investigation suggest that the inhibition of the OUR for AS by the tested chemical substances was markedly affected by the biosorption.

  14. Highly mobile oxygen holes in magnesium oxide

    Science.gov (United States)

    Freund, Minoru M.; Freund, Friedemann; Batllo, Francois

    1989-01-01

    High-purity MgO exhibits an unexpected giant anomaly of the apparent static dielectric constant and a positive surface charge of the order of 5 x 10 to the 21st/cu cm in the top 15 nm. It is postulated that the MgO matrix contains traces of peroxy defects, O2(2-), associated with Mg(2+) vacancies. Above approximately 400 C the O2(2-) dissociates to vacancy bound O(-) and highly mobile O(-) states, which diffuse to the surface, giving rise to a high surface conductivity.

  15. Metal Oxide Nanoparticle Growth on Graphene via Chemical Activation with Atomic Oxygen

    Science.gov (United States)

    Johns, James E.; Alaboson, Justice M. P.; Patwardhan, Sameer; Ryder, Christopher R.; Schatz, George C.

    2013-01-01

    Chemically interfacing the inert basal plane of graphene with other materials has limited the development of graphene-based catalysts, composite materials, and devices. Here, we overcome this limitation by chemically activating epitaxial graphene on SiC(0001) using atomic oxygen. Atomic oxygen produces epoxide groups on graphene, which act as reactive nucleation sites for zinc oxide nanoparticle growth using the atomic layer deposition precursor diethyl zinc. In particular, exposure of epoxidized graphene to diethyl zinc abstracts oxygen, creating mobile species which diffuse on the surface to form metal oxide clusters. This mechanism is corroborated with a combination of scanning probe microscopy, Raman spectroscopy, and density functional theory, and can likely be generalized to a wide variety of related surface reactions on graphene. PMID:24206242

  16. Metal oxide nanoparticle growth on graphene via chemical activation with atomic oxygen.

    Science.gov (United States)

    Johns, James E; Alaboson, Justice M P; Patwardhan, Sameer; Ryder, Christopher R; Schatz, George C; Hersam, Mark C

    2013-12-04

    Chemically interfacing the inert basal plane of graphene with other materials has limited the development of graphene-based catalysts, composite materials, and devices. Here, we overcome this limitation by chemically activating epitaxial graphene on SiC(0001) using atomic oxygen. Atomic oxygen produces epoxide groups on graphene, which act as reactive nucleation sites for zinc oxide nanoparticle growth using the atomic layer deposition precursor diethyl zinc. In particular, exposure of epoxidized graphene to diethyl zinc abstracts oxygen, creating mobile species that diffuse on the surface to form metal oxide clusters. This mechanism is corroborated with a combination of scanning probe microscopy, Raman spectroscopy, and density functional theory and can likely be generalized to a wide variety of related surface reactions on graphene.

  17. Nanocatalysis for Primary and Secondary High Energy Lithium Oxygen Cells

    Science.gov (United States)

    2011-04-01

    included emulsified Teflon (Fuel Cell Earth, 60 wt% in water), and mixtures of styrene butadiene latex ( SBR , Euclid Chemical Company) and sodium...They were, emulsified PTFE (60wt%), 2:1 (by weight) SBR /CMC blend, and lithium acrylate. Figure 43 Comarative perfomence of cahodes containing 6...the oxygen reduction reaction in fuel cell cathodes by nitrogen doped carbon (obtained via pyrolysis of N-containing polymers) has been well

  18. HIGH PERFORMANCE CERIA BASED OXYGEN MEMBRANE

    DEFF Research Database (Denmark)

    2014-01-01

    The invention describes a new class of highly stable mixed conducting materials based on acceptor doped cerium oxide (CeO2-8 ) in which the limiting electronic conductivity is significantly enhanced by co-doping with a second element or co- dopant, such as Nb, W and Zn, so that cerium and the co...

  19. Total, chemical, and biological oxygen consumption of the sediments in the Ziya River watershed, China.

    Science.gov (United States)

    Rong, Nan; Shan, Baoqing

    2016-07-01

    Sediment oxygen demand (SOD) is a critical dissolved oxygen (DO) sink in many rivers. Understanding the relative contributions of the biological and chemical components of SOD would improve our knowledge of the potential environmental harm SOD could cause and allow appropriate management systems to be developed. A various inhibitors addition technique was conducted to measure the total, chemical, and biological SOD of sediment samples from 13 sites in the Ziya River watershed, a severely polluted and anoxic river system in the north of China. The results showed that the major component of SOD was chemical SOD due to iron predominate. The ferrous SOD accounted for 21.6-78.9 % of the total SOD and 33.26-96.79 % of the chemical SOD. Biological SOD represented 41.13 % of the overall SOD averagely. Sulfide SOD accounted for 1.78-45.71 % of the total SOD and it was the secondary predominate of the chemical SOD. Manganous SOD accounted for 1.2-16.6 % of the total SOD and it was insignificant at many sites. Only four kinds of benthos were collected in the Ziya River watershed, resulting from the low DO concentration in the sediment surface due to SOD. This study would be helpful for understanding and preventing the potential sediment oxygen depletion during river restoration.

  20. Hot-wire chemical vapor deposition of WO{sub 3−x} thin films of various oxygen contents

    Energy Technology Data Exchange (ETDEWEB)

    Houweling, Z. Silvester, E-mail: Silvester.Houweling@asml.com [Section Nanophotonics – Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, Princetonlaan 4, 3584 CC Utrecht (Netherlands); Geus, John W. [Inorganic Chemistry and Catalysis, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands); Schropp, Ruud E.I. [Section Nanophotonics – Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, Princetonlaan 4, 3584 CC Utrecht (Netherlands)

    2013-06-15

    We present the synthesis of tungsten oxide (WO{sub 3−x}) thin films consisting of layers of varying oxygen content. Configurations of layered thin films comprised of W, W/WO{sub 3−x}, WO{sub 3}/W and WO{sub 3}/W/WO{sub 3−x} are obtained in a single continuous hot-wire chemical vapor deposition process using only ambient air and hydrogen. The air oxidizes resistively heated tungsten filaments and produces the tungsten oxide species, which deposit on a substrate and are subsequently reduced by the hydrogen. The reduction of tungsten oxides to oxides of lower oxygen content (suboxides) depends on the local water vapor pressure and temperature. In this work, the substrate temperature is either below 250 °C or is kept at 750 °C. A number of films are synthesized using a combined air/hydrogen flow at various total process pressures. Rutherford backscattering spectrometry is employed to measure the number of tungsten and oxygen atoms deposited, revealing the average atomic compositions and the oxygen profiles of the films. High-resolution scanning electron microscopy is performed to measure the physical thicknesses and display the internal morphologies of the films. The chemical structure and crystallinity are investigated with Raman spectroscopy and X-ray diffraction, respectively. - Highlights: • Synthesis of tungsten oxide thin films of controllable oxygen content. • Partial reduction of WO{sub 3−x} thin films during deposition. • Deposition of layered films with configurations of W, W/WO{sub 3−x}, WO{sub 3}/W/WO{sub 3−x}. • Synthesis of WO{sub 3−x} films with atomic oxygen-to-tungsten ratios between 0.3 and 3.

  1. [High flow, humidified-reheated oxygen therapy: a new oxygenation technique for adults].

    Science.gov (United States)

    Frat, J-P; Goudet, V; Girault, C

    2013-10-01

    Currently conventional oxygen therapy is the first choice symptomatic treatment in the management of acute respiratory failure (ARF). However, conventional oxygen therapy has important limitations which have lead to the development of heated and humidified high-flow nasal oxygen therapy (HFNO). HFNO is an innovative technique that can deliver, through special nasal cannulae, up to 100% of the inspired fraction (FiO2) with heated and humidified oxygen at a maximum flow of 70L/min. The characteristics of this technique (overcoming the patient's spontaneous inspiratory flow, heated humidification,) and its physiological effects (no dilution of FiO2, positive end-expiratory pressure, pharyngeal dead-space washout, decrease in airway resistance), allow efficient optimization of oxygenation with better tolerance for patients. Current data, mainly observational, show that HFNO could be used particularly for the management of hypoxemic ARF, notably in the more severe forms. Indications for using HFNO, alone or in association with noninvasive ventilation, are potentially very broad and may involve different types of ARF (post-operative, post-extubation, palliative care) and even the practice of invasive technical procedures (bronchial fibroscopy). However, though current studies are very encouraging and promise a clinical benefit on patient outcomes, randomized trials are still needed to demonstrate that HFNO avoids the need for endotracheal intubation in the management of ARF.

  2. Metal ferrite oxygen carriers for chemical looping combustion of solid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Siriwardane, Ranjani V.; Fan, Yueying

    2017-01-31

    The disclosure provides a metal ferrite oxygen carrier for the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The metal ferrite oxygen carrier comprises MFe.sub.xO.sub.y on an inert support, where MFe.sub.xO.sub.y is a chemical composition and M is one of Mg, Ca, Sr, Ba, Co, Mn, and combinations thereof. For example, MFe.sub.xO.sub.y may be one of MgFe.sub.2O.sub.4, CaFe.sub.2O.sub.4, SrFe.sub.2O.sub.4, BaFe.sub.2O.sub.4, CoFe.sub.2O.sub.4, MnFeO.sub.3, and combinations thereof. The MFe.sub.xO.sub.y is supported on an inert support. The inert support disperses the MFe.sub.xO.sub.y oxides to avoid agglomeration and improve performance stability. In an embodiment, the inert support comprises from about 5 wt. % to about 60 wt. % of the metal ferrite oxygen carrier and the MFe.sub.xO.sub.y comprises at least 30 wt. % of the metal ferrite oxygen carrier. The metal ferrite oxygen carriers disclosed display improved reduction rates over Fe.sub.2O.sub.3, and improved oxidation rates over CuO.

  3. Process safety management for highly hazardous chemicals

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    Purpose of this document is to assist US DOE contractors who work with threshold quantities of highly hazardous chemicals (HHCs), flammable liquids or gases, or explosives in successfully implementing the requirements of OSHA Rule for Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119). Purpose of this rule is to prevent releases of HHCs that have the potential to cause catastrophic fires, explosions, or toxic exposures.

  4. Chemical homogeneity in the Orion Association: Oxygen abundances of B stars

    Directory of Open Access Journals (Sweden)

    Lanz T.

    2012-02-01

    Full Text Available We present non-LTE oxygen abundances for a sample of B stars in the Orion association. The abundance calculations included non-LTE line formation and used fully blanketed non-LTE model atmospheres. The stellar parameters were the same as adopted in the previous study by Cunha & Lambert (1994. We find that the young Orion stars in this sample of 10 stars are described by a single oxygen abundance with an average value of A(O = 8.78 and a small dispersion of ±0.05, dex which is of the order of the uncertainties in the analysis. This average oxygen abundance compares well with the average oxygen abundance obtained previously in Cunha & Lambert (1994: A(O = 8.72 ± 0.13 although this earlier study, based upon non-blanketed model atmospheres in LTE, displayed larger scatter. Small scatter of chemical abundances in Orion B stars had also been found in our previous studies for neon and argon; all based on the same effective temperature scale. The derived oxygen abundance distribution for the Orion association compares well with other results for the oxygen abundance in the solar neighborhood.

  5. Chemical exposure-response relationship between air pollutants and reactive oxygen species in the human respiratory tract

    Science.gov (United States)

    Lakey, Pascale S. J.; Berkemeier, Thomas; Tong, Haijie; Arangio, Andrea M.; Lucas, Kurt; Pöschl, Ulrich; Shiraiwa, Manabu

    2016-09-01

    Air pollution can cause oxidative stress and adverse health effects such as asthma and other respiratory diseases, but the underlying chemical processes are not well characterized. Here we present chemical exposure-response relations between ambient concentrations of air pollutants and the production rates and concentrations of reactive oxygen species (ROS) in the epithelial lining fluid (ELF) of the human respiratory tract. In highly polluted environments, fine particulate matter (PM2.5) containing redox-active transition metals, quinones, and secondary organic aerosols can increase ROS concentrations in the ELF to levels characteristic for respiratory diseases. Ambient ozone readily saturates the ELF and can enhance oxidative stress by depleting antioxidants and surfactants. Chemical exposure-response relations provide a quantitative basis for assessing the relative importance of specific air pollutants in different regions of the world, showing that aerosol-induced epithelial ROS levels in polluted megacity air can be several orders of magnitude higher than in pristine rainforest air.

  6. The evaluation of secondary system oxygen-scavenging chemicals using a water-circulating rig

    Energy Technology Data Exchange (ETDEWEB)

    Collins, M.W. [Nuclear Dept., HMS Sultan (United Kingdom)

    2002-07-01

    To assess the efficiency, mode of action and possible by-products of chemical dosing agents, e.g. oxygen scavengers, a circulating water rig was constructed. The rig uses a demineralized water supply as a source of make-up water to fill a recirculating loop of approx. 10 litres volume. The rig pipework is made of polythene with standard off-the shelf pipe fittings and connectors. The following parameters can be measured within the rig: pH and conductivity measured by in-line monitor, dissolved oxygen level, temperature. The system has already been used for some preliminary testing. The following oxygen scavengers have been used for tests: ascorbic acid (vitamin C), N,N-diethyl-hydroxylamine (DEHA), Hydroquinone, hydrazine hydrate and anhydrous sodium sulfite. (authors)

  7. Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

    Science.gov (United States)

    Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

    2017-06-01

    Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.

  8. CPAP and High-Flow Nasal Cannula Oxygen in Bronchiolitis.

    Science.gov (United States)

    Sinha, Ian P; McBride, Antonia K S; Smith, Rachel; Fernandes, Ricardo M

    2015-09-01

    Severe respiratory failure develops in some infants with bronchiolitis because of a complex pathophysiologic process involving increased airways resistance, alveolar atelectasis, muscle fatigue, and hypoxemia due to mismatch between ventilation and perfusion. Nasal CPAP and high-flow nasal cannula (HFNC) oxygen may improve the work of breathing and oxygenation. Although the mechanisms behind these noninvasive modalities of respiratory support are not well understood, they may help infants by way of distending pressure and delivery of high concentrations of warmed and humidified oxygen. Observational studies of varying quality have suggested that CPAP and HFNC may confer direct physiologic benefits to infants with bronchiolitis and that their use has reduced the need for intubation. No trials to our knowledge, however, have compared CPAP with HFNC in bronchiolitis. Two randomized trials compared CPAP with oxygen delivered by low-flow nasal cannula or face mask and found some improvements in blood gas results and some physiologic parameters, but these trials were unable to demonstrate a reduction in the need for intubation. Two trials evaluated HFNC in bronchiolitis (one comparing it with headbox oxygen, the other with nebulized hypertonic saline), with the results not seeming to suggest important clinical or physiologic benefits. In this article, we review the pathophysiology of respiratory failure in bronchiolitis, discuss these trials in detail, and consider how future research studies may be designed to best evaluate CPAP and HFNC in bronchiolitis.

  9. Chemical and Oxygen Isotopic Composition of Roman and Late Antique Glass from Northern Greece

    Directory of Open Access Journals (Sweden)

    Alberta Silvestri

    2017-01-01

    Full Text Available The present paper emphasizes the importance of measuring the oxygen isotopic and chemical compositions of ancient glass, in order to constrain some features such as age, raw materials, and production technologies and to identify the “fingerprint” of local productions. In this context, thirty-nine Roman and late Antique glass samples and eight chert samples from northern Greece were selected and analysed for their oxygen isotopic and chemical compositions. Results show that the majority of glass samples are produced using natron as flux and have δ18O values of about 15.5‰, plus or minus a few tenths of one per mil, suggesting that raw materials probably come from Levantine area. Four samples are heavily enriched in 18O, and their chemical composition clearly shows that they were made with soda plant ash as flux. Isotopic and chemical data of Greek chert samples support the hypothesis of local production of the above samples. About half of the glass samples have chemical compositions, which allow their age to be constrained to the late Antique period. For the remaining glass, similarities with literature compositional groups are reported and discussed.

  10. Comparison of Iron and Tungsten Based Oxygen Carriers for Hydrogen Production Using Chemical Looping Reforming

    Science.gov (United States)

    Khan, M. N.; Shamim, T.

    2017-08-01

    Hydrogen production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative and attractive process. Fossil fuels such as methane are the feedstocks used. This process is similar to a conventional steam-methane reforming but occurs in three steps utilizing an oxygen carrier. As the oxygen carrier plays an important role, its selection should be done carefully. In this study, two oxygen carrier materials of base metal iron (Fe) and tungsten (W) are analysed using a thermodynamic model of a three reactor chemical looping reforming plant in Aspen plus. The results indicate that iron oxide has moderate oxygen carrying capacity and is cheaper since it is abundantly available. In terms of hydrogen production efficiency, tungsten oxide gives 4% better efficiency than iron oxide. While in terms of electrical power efficiency, iron oxide gives 4.6% better results than tungsten oxide. Overall, a TRCLR system with iron oxide is 2.6% more efficient and is cost effective than the TRCLR system with tungsten oxide.

  11. Predicting dissolved oxygen concentration using kernel regression modeling approaches with nonlinear hydro-chemical data.

    Science.gov (United States)

    Singh, Kunwar P; Gupta, Shikha; Rai, Premanjali

    2014-05-01

    Kernel function-based regression models were constructed and applied to a nonlinear hydro-chemical dataset pertaining to surface water for predicting the dissolved oxygen levels. Initial features were selected using nonlinear approach. Nonlinearity in the data was tested using BDS statistics, which revealed the data with nonlinear structure. Kernel ridge regression, kernel principal component regression, kernel partial least squares regression, and support vector regression models were developed using the Gaussian kernel function and their generalization and predictive abilities were compared in terms of several statistical parameters. Model parameters were optimized using the cross-validation procedure. The proposed kernel regression methods successfully captured the nonlinear features of the original data by transforming it to a high dimensional feature space using the kernel function. Performance of all the kernel-based modeling methods used here were comparable both in terms of predictive and generalization abilities. Values of the performance criteria parameters suggested for the adequacy of the constructed models to fit the nonlinear data and their good predictive capabilities.

  12. Removal of chemical oxygen demand from textile wastewater using a natural coagulant

    Energy Technology Data Exchange (ETDEWEB)

    Ramavandi, Bahman [Bushehr University of Medical Sciences, Bushehr (Iran, Islamic Republic of); Farjadfard, Sima [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2014-01-15

    A biomaterial was successfully synthesized from Plantago ovata by using an FeCl{sub 3}-induced crude extract (FCE). The potential of FCE to act as a natural coagulant was tested for the pretreatment of real textile wastewater. Tests were performed to evaluate the effects of FCE quantity, salt concentration, and wastewater pH on chemical oxygen demand (COD) reduction during a coagulation/flocculation process. Experimental results indicated that the wastewater could be effectively treated by using a coagulation/flocculation process, where the BOD{sub 5}/COD ratio of the effluent was improved to 0.48. A low coagulant dose, 1.5mg/L, achieved a high COD removal percentage, 89%, at operational conditions of neutral pH and room temperature. The experimental data revealed that the maximum COD removal occurred at water pH<8. Increasing the salt promoted the COD removal. The settling and filterability characteristics of the sludge were also studied. Scanning electron microscopy and energy dispersive spectroscopy studies were conducted to determine the sludge structure and composition, respectively. Overall, FCE as an eco-friendly biomaterial was revealed to be a very efficient coagulant and a promising option for the removal of COD from wastewaters.

  13. Uvaridacols E-H, highly oxygenated antiausterity agents from Uvaria dac.

    Science.gov (United States)

    Awale, Suresh; Ueda, Jun-ya; Athikomkulchai, Sirivan; Dibwe, Dya Fita; Abdelhamed, Sherif; Yokoyama, Satoru; Saiki, Ikuo; Miyatake, Ryuta

    2012-11-26

    Chemical investigation of the stems of Uvaria dac yielded four new highly oxygenated cyclohexene derivatives named uvaridacols E-H (1-4). Their structures were established through NMR and circular dichroism spectroscopic analysis. Uvaridacols E (1), F (2), and H (4) displayed weak preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived conditions in a concentration-dependent manner, without causing toxicity in normal nutrient-rich conditions.

  14. High-Pressure Oxygen Generation for Outpost EVA Study

    Science.gov (United States)

    Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.

    2009-01-01

    The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

  15. Chemical Homogeneity in the Orion Association: Oxygen Abundances of B Stars

    CERN Document Server

    Cunha, K; Lanz, T

    2011-01-01

    We present non-LTE oxygen abundances for a sample of B stars in the Orion association. The abundance calculations included non-LTE line formation and used fully blanketed non-LTE model atmospheres. The stellar parameters were the same as adopted in the previous study by Cunha & Lambert (1994). We find that the young Orion stars in this sample of 10 stars are described by a single oxygen abundance with an average value of A(O)=8.78 and a small dispersion of +/- 0.05 dex, which is of the order of the uncertainties in the analysis. This average oxygen abundance compares well with the average oxygen abundance obtained previously in Cunha & Lambert (1994): A(O) = 8.72 +/- 0.13 although this earlier study, based upon non-blanketed model atmospheres in LTE, displayed larger scatter. Small scatter of chemical abundances in Orion B stars had also been found in our previous studies for neon and argon; all based on the same effective temperature scale. The derived oxygen abundance distribution for the Orion asso...

  16. Impact of Dissolved Oxygen during UV-Irradiation on the Chemical Composition and Function of CHO Cell Culture Media.

    Directory of Open Access Journals (Sweden)

    Sarah M Meunier

    Full Text Available Ultraviolet (UV irradiation is advantageous as a sterilization technique in the biopharmaceutical industry since it is capable of targeting non-enveloped viruses that are typically challenging to destroy, as well as smaller viruses that can be difficult to remove via conventional separation techniques. In this work, we investigated the influence of oxygen in the media during UV irradiation and characterized the effect on chemical composition using NMR and LC-MS, as well as the ability of the irradiated media to support cell culture. Chemically defined Chinese hamster ovary cell growth media was irradiated at high fluences in a continuous-flow UV reactor. UV-irradiation caused the depletion of pyridoxamine, pyridoxine, pyruvate, riboflavin, tryptophan, and tyrosine; and accumulation of acetate, formate, kynurenine, lumichrome, and sarcosine. Pyridoxamine was the only compound to undergo complete degradation within the fluences considered; complete depletion of pyridoxamine was observed at 200 mJ/cm2. Although in both oxygen- and nitrogen-saturated media, the cell culture performance was affected at fluences above 200 mJ/cm2, there was less of an impact on cell culture performance in the nitrogen-saturated media. Based on these results, minimization of oxygen in cell culture media prior to UV treatment is recommended to minimize the negative impact on sensitive media.

  17. High flow nasal oxygen in acute respiratory failure.

    Science.gov (United States)

    Ricard, J-D

    2012-07-01

    Use of high flow nasal cannula oxygen (HFNC) is increasingly popular in adult ICUs for patients with acute hypoxemic respiratory failure. This is the result of the successful long-term use of HFNC in the neonatal field and recent clinical data in adults indicating beneficial effects of HFNC over conventional facemask oxygen therapy. HFNC rapidly alleviates symptoms of respiratory distress and improves oxygenation by several mechanisms, including deadspace washout, reduction in oxygen dilution and in inspiratory nasopharyngeal resistance, a moderate positive airway pressure effect that may generate alveolar recruitment and an overall greater tolerance and comfort with the interface and the heated and humidified inspired gases. Indications of HFNC are broad, encompassing most if not all causes of acute hypoxemic respiratory failure. HFNC can also provide oxygen during invasive procedures, and be used to prevent or treat post-extubation respiratory failure. HFNC may also alleviate respiratory distress in patients at a palliative stage. Although observational studies suggest that HFNC might reduce the need for intubation in acute hypoxemic respiratory failure; such a reduction has not yet been demonstrated. Beyond this potential additional effect on outcome, the evidence already published argues in favor of the large use of HFNC as first line therapy for acute respiratory failure.

  18. High fidelity modeling of thermal relaxation and dissociation of oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Andrienko, Daniil A., E-mail: daniila@umich.edu; Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, 1320 Beal Ave., Ann Arbor, Michigan 48108 (United States)

    2015-11-15

    A master equation study of vibrational relaxation and dissociation of oxygen is conducted using state-specific O{sub 2}–O transition rates, generated by extensive trajectory simulations. Both O{sub 2}–O and O{sub 2}–O{sub 2} collisions are concurrently simulated in the evolving nonequilibrium gas system under constant heat bath conditions. The forced harmonic oscillator model is incorporated to simulate the state-to-state relaxation of oxygen in O{sub 2}–O{sub 2} collisions. The system of master equations is solved to simulate heating and cooling flows. The present study demonstrates the importance of atom-diatom collisions due to the extremely efficient energy randomization in the intermediate O{sub 3} complex. It is shown that the presence of atomic oxygen has a significant impact on vibrational relaxation time at temperatures observed in hypersonic flow. The population of highly-excited O{sub 2} vibrational states is affected by the amount of atomic oxygen when modeling the relaxation under constant heat bath conditions. A model of coupled state-to-state vibrational relaxation and dissociation of oxygen is also discussed.

  19. Application of Fe2O3/Al2O3 Composite Particles as Oxygen Carrier of Chemical Looping Combustion

    Institute of Scientific and Technical Information of China (English)

    Fang He; Hua Wang; Yongnian Dai

    2007-01-01

    Chemical looping combustion (CLC) of carbonaceous compounds has been proposed, in the past decade, as an efficient method for CO2 capture without cost of extra energy penalties. The technique involves the use of a metal oxide as an oxygen carrier that transfers oxygen from combustion air to fuels.The combustion is carried out in a two-step process: in the fuel reactor, the fuel is oxidized by a metal oxide, and in the air reactor, the reduced metal is oxidized back to the original phase. The use of iron oxide as an oxygen carrier has been investigated in this article. Particles composed of 80 wt% Fe2O3,together with Al2O3 as binder, have been prepared by impregnation methods. X-ray diffraction (XRD) analysis reveals that Fe2O3 does not interact with the Al2O3 binder after multi-cycles. The reactivity of the oxygen carrier particles has been studied in twenty-cycle reduction-oxidation tests in a thermal gravimetrical analysis (TGA) reactor. The components in the outlet gas have been analyzed. It has been observed that about 85% of CH4 converted to CO2 and H2O during most of the reduction periods. The oxygen carrier has kept quite a high reactivity in the twenty-cycle reactions. In the first twenty reaction cycles, the reaction rates became slightly higher with the number of cyclic reactions increasing, which was confirmed by the scanning electron microscopy (SEM) test results. The SEM analysis revealed that the pore size inside the particle had been enlarged by the thermal stress during the reaction, which was favorable for diffusion of the gaseous reactants into the particles. The experimental results suggested that the Fe2O3/Al2O3 oxygen carrier was a promising candidate for a CLC system.

  20. High throughput jet singlet oxygen generator for multi kilowatt SCOIL

    Science.gov (United States)

    Rajesh, R.; Singhal, Gaurav; Mainuddin; Tyagi, R. K.; Dawar, A. L.

    2010-06-01

    A jet flow singlet oxygen generator (JSOG) capable of handling chlorine flows of nearly 1.5 mol s -1 has been designed, developed, and tested. The generator is designed in a modular configuration taking into consideration the practical aspects of handling high throughput flows without catastrophic BHP carry over. While for such high flow rates a cross-flow configuration has been reported, the generator utilized in the present study is a counter flow configuration. A near vertical extraction of singlet oxygen is effected at the generator exit, followed by a 90° rotation of the flow forming a novel verti-horizontal COIL scheme. This allows the COIL to be operated with a vertical extraction SOG followed by the horizontal arrangement of subsequent COIL systems such as supersonic nozzle, cavity, supersonic diffuser, etc. This enables a more uniform weight distribution from point of view of mobile and other platform mounted systems, which is highly relevant for large scale systems. The present study discusses the design aspects of the jet singlet oxygen generator along with its test results for various operating ranges. Typically, for the intended design flow rates, the chlorine utilization and singlet oxygen yield have been observed to be ˜94% and ˜64%, respectively.

  1. Portable High Sensitivity and High Resolution Sensor to Determine Oxygen Purity Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I STTR project is to develop a highly sensitive oxygen (O2) sensor, with high accuracy and precision, to determine purity levels of high...

  2. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    KAUST Repository

    Sarath Kumar, S. R.

    2013-08-14

    We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.

  3. Mathematical modeling of chemical composition modification and etching of polymers under the atomic oxygen influence

    Science.gov (United States)

    Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

    2016-07-01

    Atomic oxygen (AO) of the upper atmosphere is one of the most important space factors that can cause degradation of spacecraft surface. In our previous mathematical model the Monte Carlo method and the "large particles" approximation were used for simulating processes of polymer etching under the influence of AO [1]. The interaction of enlarged AO particles with the polymer was described in terms of probabilities of reactions such as etching of polymer and specular and diffuse scattering of the AO particles on polymer. The effects of atomic oxygen on protected polymers and microfiller containing composites were simulated. The simulation results were in quite good agreement with the results of laboratory experiments on magnetoplasmadynamic accelerator of the oxygen plasma of SINP MSU [2]. In this paper we present a new model that describes the reactions of AO interactions with polymeric materials in more detail. Reactions of formation and further emission of chemical compounds such as CO, CO _{2}, H _{2}O, etc. cause the modification of the chemical composition of the polymer and change the probabilities of its consequent interaction with the AO. The simulation results are compared with the results of previous simulation and with the results of laboratory experiments. The reasons for the differences between the results of natural experiments on spacecraft, laboratory experiments and simulations are discussed. N. Chirskaya, M. Samokhina, Computer modeling of polymer structures degradation under the atomic oxygen exposure, WDS'12 Proceedings of Contributed Papers: Part III - Physics, Matfyzpress Prague, 2012, pp. 30-35. E. Voronina, L. Novikov, V. Chernik, N. Chirskaya, K. Vernigorov, G. Bondarenko, and A. Gaidar, Mathematical and experimental simulation of impact of atomic oxygen of the earth's upper atmosphere on nanostructures and polymer composites, Inorganic Materials: Applied Research, 2012, vol. 3, no. 2, pp. 95-101.

  4. Novel Local Calibration Method for Chemical Oxygen Demand Measurements by Using UV-Vis Spectrometry

    Science.gov (United States)

    Yingtian, Hu; Chao, Liu; Xiaoping, Wang

    2017-05-01

    In recent years, ultraviolet-visible spectroscopy has been widely used for chemical oxygen demand (COD) measurements of water. However, chemical compositions of substance in different water samples can cause measurement deviations, so a local calibration is needed. In this study, a novel local calibration method is proposed. The absorption spectra of COD standard solutions and wastewater samples taken from four factories were collected. We analyzed the impact of chemical compositions of substance in different water samples and extracted the morphology features of their absorptive spectra for recognition models. Furthermore, we calculated the local calibration parameters of the four categories of real water samples by specific modification based on the ability of light absorption in various water environments. After the process of local calibration, the root mean square errors (RMSEs) of the predictions were very small, which highlights the potential of this method for improving the accuracy and adaptability of COD measurements based on ultraviolet-visible spectrum.

  5. Correlation between Biochemical Oxygen Demand and Chemical Oxygen Demand for Various Wastewater Treatment Plants in Egypt to Obtain the Biodegradability Indices

    OpenAIRE

    Khaled Zaher Abdallah; Gina Hammam

    2014-01-01

    Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) are the most commonly used parameters for the characterization of wastewaters. Both of these parameters have advantages and disadvantages, and the choice usually depends on many factors such as the time period required to determine each one of them. It is essential to obtain a correlation between BOD5 and COD for various wastewater treatment plants, to help in the design and operation of these plants. In this paper, the biodegr...

  6. Validation of chemical-looping with oxygen uncoupling (CLOU using Cu-based oxygen carrier and comparative study of Cu, Mn and Co based oxygen carriers using ASPEN plus

    Directory of Open Access Journals (Sweden)

    Xiao Zhang, Subhodeep Banerjee, Ramesh K. Agarwal

    2015-01-01

    Full Text Available The chemical-looping with oxygen uncoupling (CLOU has been demonstrated to be an effective technological pathway for high-efficiency low-cost carbon dioxide capture when particulate coal serves as the fuel. In this paper, complete process-level modeling of CLOU process conducted in ASPEN Plus is presented. The heat content of fuel and air reactors and air/flue gas heat exchangers is carefully examined. It is shown that the established model provides results which are in excellent agreement with the experiments for the overall power output of the CLOU process. Finally the effect of varying the air flow rate and three different types of coal as the solid fuel on energy output is investigated, and the performance of three – Copper (Cu, Manganese (Mn and Cobalt (Co based oxygen carriers in CLOU process is compared. It is shown that there exists an optimal air flow rate to obtain the maximum power output for a given coal feeding rate and coal type. The effect of three different oxygen carriers on energy output is also investigated using the optimal air flow rate. Among the three oxygen carriers - CuO, Mn2O3, and Co3O4; Mn2O3 shows the best performance on power output. The results presented in this paper can be used to estimate the amount of various quantities such as the air flow rate and oxygen carrier (and its type required to achieve near optimal energy output from a CLOU process based power plant.

  7. CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2

    Energy Technology Data Exchange (ETDEWEB)

    Peizheng Zhou

    2002-12-30

    This report summarizes the work completed under DOE's Support of Advanced Fuel Research program, Contract No. DE-FG26-99FT40681. The contract period was October 2000 through September 2002. This R&D program investigated the modification of the mechanical strength of catalyst extrudates using Hydrocarbon Technologies, Inc. (HTI) carbon-coated catalyst technology so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. Exothermic chemical reactions benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. The carbon-coated extrudates prepared using these procedures had sufficient attrition resistance and surface area for use in ebullated bed operation. The low cost of carbon coating makes the carbon-coated catalysts highly competitive in the market of catalyst extrudates.

  8. High Oxygen Concentrations Adversely Affect the Performance of Pulmonary Surfactant.

    Science.gov (United States)

    Smallwood, Craig D; Boloori-Zadeh, Parnian; Silva, Maricris R; Gouldstone, Andrew

    2017-08-01

    Although effective in the neonatal population, exogenous pulmonary surfactant has not demonstrated a benefit in pediatric and adult subjects with hypoxic lung injury despite a sound physiologic rationale. Importantly, neonatal surfactant replacement therapy is administered in conjunction with low fractional FIO2 while pediatric/adult therapy is administered with high FIO2 . We suspected a connection between FIO2 and surfactant performance. Therefore, we sought to assess a possible mechanism by which the activity of pulmonary surfactant is adversely affected by direct oxygen exposure in in vitro experiments. The mechanical performance of pulmonary surfactant was evaluated using 2 methods. First, Langmuir-Wilhelmy balance was utilized to study the reduction in surface area (δA) of surfactant to achieve a low bound value of surface tension after repeated compression and expansion cycles. Second, dynamic light scattering was utilized to measure the size of pulmonary surfactant particles in aqueous suspension. For both experiments, comparisons were made between surfactant exposed to 21% and 100% oxygen. The δA of surfactant was 21.1 ± 2.0% and 35.8 ± 2.0% during exposure to 21% and 100% oxygen, respectively (P = .02). Furthermore, dynamic light-scattering experiments revealed a micelle diameter of 336.0 ± 12.5 μm and 280.2 ± 11.0 μm in 21% and 100% oxygen, respectively (P < .001), corresponding to a ∼16% decrease in micelle diameter following exposure to 100% oxygen. The characteristics of pulmonary surfactant were adversely affected by short-term exposure to oxygen. Specifically, surface tension studies revealed that short-term exposure of surfactant film to high concentrations of oxygen expedited the frangibility of pulmonary surfactant, as shown with the δA. This suggests that reductions in pulmonary compliance and associated adverse effects could begin to take effect in a very short period of time. If these findings can be demonstrated in vivo, a role for

  9. Oxygen Escape from Venus During High Dynamic Pressure ICMEs

    Science.gov (United States)

    McEnulty, Tess; Luhmann, J. G.; Brain, D. A.; Fedorov, A.; Jian, L. K.; Russell, C. T.; Zhang, T.; Möstl, C.; Futaana, Y.; de Pater, I.

    2013-10-01

    Previous studies using data from Pioneer Venus suggested that oxygen ion escape flux may be enhanced by orders of magnitude during Interplanetary Coronal Mass Ejections. However, this large enhancement has been ambiguous in Venus Express ion data - with some analyses showing no flux enhancement or a small enhancement (within 2 times undisturbed cases). One possible explanation is that high escape flux may be due to high dynamic pressure in the solar wind, and the dynamic pressure has been lower during the VEX time period. So, we focus on ICMEs with the largest dynamic pressure and with VEX sampling of the escaping ions during the sheath of the ICMEs (during which the highest dynamic pressures in the solar wind occur). We will show the characteristics of these large events measured by VEX, and compare them to the largest ICMEs measured by PVO. We will then discuss estimates of the oxygen ion escape flux during these events.

  10. Highly durable graphene nanoplatelets supported Pt nanocatalysts for oxygen reduction

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Zhang, Sheng; Wang, Chongmin; Nie, Zimin; Liu, Jun; Lin, Yuehe [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Wang, Yong [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164 (United States)

    2010-08-01

    We report graphene nanoplatelets (GNPs), which exhibit the advantages of both single-layer graphene and highly graphitic carbon, as a durable alternative support material for Pt nanoparticles for oxygen reduction in fuel cells. Pt nanoparticles are deposited on poly(diallyldimethylammonium chloride) (PDDA)-coated GNP, and characterized with transmission electron microscopy, X-ray diffraction, Raman spectra, and electrochemical tests. Pt/GNP exhibits greatly enhanced electrochemical durability (2-3 times that of Pt/CNT and commercial Etek Pt/C). These are attributed to the intrinsic high graphitization degree of GNP and the enhanced Pt-carbon interaction in Pt/GNP. If considering that GNP can be easily mass produced from graphite, GNP is a promising, low-cost, and durable electrocatalyst support for oxygen reduction in fuel cells. (author)

  11. Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

    Institute of Scientific and Technical Information of China (English)

    XU Qiu-jin; NIAN Yue-gang; JIN Xiang-can; YAN Chang-zhou; LIU Jin; Jiang Gao-ming

    2007-01-01

    Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. verticillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.

  12. Development of High Temperature/High Sensitivity Novel Chemical Resistive Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chonglin; Nash, Patrick; Ma, Chunrui; Enriquez, Erik; Wang, Haibing; Xu, Xing; Bao, Shangyong; Collins, Gregory

    2013-08-13

    The research has been focused to design, fabricate, and develop high temperature/high sensitivity novel multifunctional chemical sensors for the selective detection of fossil energy gases used in power and fuel systems. By systematically studying the physical properties of the LnBaCo{sub 2}O{sub 5+d} (LBCO) [Ln=Pr or La] thin-films, a new concept chemical sensor based high temperature chemical resistant change has been developed for the application for the next generation highly efficient and near zero emission power generation technologies. We also discovered that the superfast chemical dynamic behavior and an ultrafast surface exchange kinetics in the highly epitaxial LBCO thin films. Furthermore, our research indicates that hydrogen can superfast diffuse in the ordered oxygen vacancy structures in the highly epitaxial LBCO thin films, which suggest that the LBCO thin film not only can be an excellent candidate for the fabrication of high temperature ultra sensitive chemical sensors and control systems for power and fuel monitoring systems, but also can be an excellent candidate for the low temperature solid oxide fuel cell anode and cathode materials.

  13. Electron attachment to oxygen clusters studied with high energy resolution

    Science.gov (United States)

    Matejcik, S.; Stampfli, P.; Stamatovic, A.; Scheier, P.; Märk, T. D.

    1999-08-01

    Highly monochromatized electrons (with energy distributions of less than 30 meV FWHM) are used in a crossed beam experiments to investigate electron attachment to oxygen clusters (O2)n at electron energies from approximately zero eV up to several eV. At energies close to zero the attachment cross section for the reaction (O2)n+e→(O2)m- (for m=1, 2, and 3) rises strongly with decreasing electron energy compatible with s-wave electron capture to (O2)n. Peaks in the oxygen attachment cross sections present at higher energies (≈80 meV, 193 meV, 302 meV) can be ascribed to vibrational levels of the anion populated by attachment of an electron to a single oxygen molecule within the target cluster via a direct Franck-Condon transition from the ground vibrational state v=0 to a vibrational excited state v'=7,8,9,… of the anion produced. The vibrational structures observed here for the first time can be quantitatively accounted for by model calculations using a microscopic model to examine the attachment of an electron to an oxygen molecule inside a cluster. This involves (i) molecular dynamics simulations to calculate the structure of neutral clusters prior to the attachment process and (ii) calculation of the solvation energy of an oxygen anion in the cluster from the electrostatic polarization of the molecules of the cluster. The occurrence of this polarization energy at the surface of larger clusters explains the appearance of an s-wave capturing cross section at 0 eV and the slightly smaller spacings (compared to the monomer case) between the peaks at finite energy, as observed experimentally. The relative transition probabilities from the ground state of the neutral oxygen molecule to the different vibrational levels of the anion are obtained by calculating the corresponding Franck-Condon factors thereby resulting in a reasonable theoretical fit to the observed yields of negatively charged oxygen molecules and clusters.

  14. Oxygen reduction reaction over silver particles with various morphologies and surface chemical states

    Science.gov (United States)

    Ohyama, Junya; Okata, Yui; Watabe, Noriyuki; Katagiri, Makoto; Nakamura, Ayaka; Arikawa, Hidekazu; Shimizu, Ken-ichi; Takeguchi, Tatsuya; Ueda, Wataru; Satsuma, Atsushi

    2014-01-01

    The oxygen reduction reaction (ORR) in an alkaline solution was carried out using Ag powders having various particle morphologies and surface chemical states (Size: ca. 40-110 nm in crystalline size. Shape: spherical, worm like, and angular. Surface: smooth with easily reduced AgOx, defective with AgOx, and Ag2CO3 surface layer). The various Ag powders were well characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption, scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and stripping voltammetry of underpotential-deposited lead. Defective and oxidized surfaces enhanced the Ag active surface area during the ORR. The ORR activity was affected by the morphology and surface chemical state: Ag particles with defective and angular surfaces showed smaller electron exchange number between three and four but showed higher specific activity compared to Ag particles with smooth surfaces.

  15. Evaluation of the use of different coals in chemical looping combustion using a bauxite waste as oxygen carrier

    OpenAIRE

    Mendiara, Teresa; García Labiano, Francisco; Gayán Sanz, Pilar; Abad Secades, Alberto; Diego Poza, Luis F. de; Adánez Elorza, Juan

    2013-01-01

    The interest in the use of solid fuels such as coal in Chemical Looping Combustion is growing because of the benefits of the direct use of coal in this technology on the reduction of the costs linked to carbon dioxide capture. In CLC, the oxygen needed for the combustion is supplied by a solid oxygen carrier therefore avoiding the direct contact between fuel and air. Focusing on the use of solid fuels in the In-Situ Gasification Chemical Looping Combustion (iG-CLC), the oxygen ...

  16. Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel-Oxygen Species.

    Science.gov (United States)

    Corona, Teresa; Draksharapu, Apparao; Padamati, Sandeep K; Gamba, Ilaria; Martin-Diaconescu, Vlad; Acuña-Parés, Ferran; Browne, Wesley R; Company, Anna

    2016-10-05

    Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed toward the characterization of the biologically relevant terminal manganese-oxygen and iron-oxygen species, the corresponding analogues based on late-transition metals such as cobalt, nickel or copper are relatively scarce. This scarcity is in part related to the "Oxo Wall" concept, which predicts that late transition metals cannot support a terminal oxido ligand in a tetragonal environment. Here, the nickel(II) complex (1) of the tetradentate macrocyclic ligand bearing a 2,6-pyridinedicarboxamidate unit is shown to be an effective catalyst in the chlorination and oxidation of C-H bonds with sodium hypochlorite as terminal oxidant in the presence of acetic acid (AcOH). Insight into the active species responsible for the observed reactivity was gained through the study of the reaction of 1 with ClO(-) at low temperature by UV-vis absorption, resonance Raman, EPR, ESI-MS, and XAS analyses. DFT calculations aided the assignment of the trapped chromophoric species (3) as a nickel-hypochlorite species. Despite the fact that the formal oxidation state of the nickel in 3 is +4, experimental and computational analysis indicate that 3 is best formulated as a Ni(III) complex with one unpaired electron delocalized in the ligands surrounding the metal center. Most remarkably, 3 reacts rapidly with a range of substrates including those with strong aliphatic C-H bonds, indicating the direct involvement of 3 in the oxidation/chlorination reactions observed in the 1/ClO(-)/AcOH catalytic system.

  17. Influence of Chemical and Physical Properties of Activated Carbon Powders on Oxygen Reduction and Microbial Fuel Cell Performance

    KAUST Repository

    Watson, Valerie J.

    2013-06-03

    Commercially available activated carbon (AC) powders made from different precursor materials (coal, peat, coconut shell, hardwood, and phenolic resin) were electrochemically evaluated as oxygen reduction catalysts and tested as cathode catalysts in microbial fuel cells (MFCs). AC powders were characterized in terms of surface chemistry and porosity, and their kinetic activities were compared to carbon black and platinum catalysts in rotating disk electrode (RDE) tests. Cathodes using the coal-derived AC had the highest power densities in MFCs (1620 ± 10 mW m-2). Peat-based AC performed similarly in MFC tests (1610 ± 100 mW m-2) and had the best catalyst performance, with an onset potential of Eonset = 0.17 V, and n = 3.6 electrons used for oxygen reduction. Hardwood based AC had the highest number of acidic surface functional groups and the poorest performance in MFC and catalysis tests (630 ± 10 mW m-2, Eonset = -0.01 V, n = 2.1). There was an inverse relationship between onset potential and quantity of strong acid (pKa < 8) functional groups, and a larger fraction of microporosity was negatively correlated with power production in MFCs. Surface area alone was a poor predictor of catalyst performance, and a high quantity of acidic surface functional groups was determined to be detrimental to oxygen reduction and cathode performance. © 2013 American Chemical Society.

  18. Direct spectroscopic observation of singlet oxygen quenching and kinetic studies of physical and chemical singlet oxygen quenching rate constants of synthetic antioxidants (BHA, BHT, and TBHQ) in methanol.

    Science.gov (United States)

    Lee, Jun Hyun; Jung, Mun Yhung

    2010-08-01

    Singlet oxygen quenching by synthetic antioxidants (BHA, BHT, and TBHQ) was directly observed by spectroscopic monitoring of luminescence at 1268 nm. The luminescence data showed unambiguous evidence of singlet oxygen quenching by synthetic phenolic antioxidants with the highest activity for TBHQ, followed by BHA and BHT. The protective activities of these synthetic antioxidants on alpha-terpinene oxidation with chemically-induced singlet oxygen under dark further confirmed their singlet oxygen quenching abilities. Total singlet oxygen quenching rate constants (k(r) + k(q)) of BHA, BHT, and TBHQ were determined in a system containing alpha-terpinene (as a singlet oxygen trap) and methylene blue (as a sensitizer) during light irradiation, and the values were 5.14 x 10(7), 3.41 x 10(6), and 1.99 x 10(8) M(-1)s(-1), respectively. After the k(r) value of alpha-terpinene was first determined, the k(r) values of the synthetic antioxidants were calculated by measuring their relative reaction rates with singlet oxygen to that of alpha-terpinene under the identical conditions. The k(r) values of the BHA, BHT, and TBHQ were 3.90 x 10(5), 1.23 x 10(5), and 2.93 x 10(6), M(-1)s(-1). The percent partition of chemical quenching over total singlet oxygen quenching (k(r) x 100)/(k(r) + k(q)) for BHA, BHT, and TBHQ were 0.76%, 3.61%, and 1.47%, respectively. The results showed that the synthetic antioxidants quench singlet oxygen almost exclusively through the mechanism of physical quenching. This represents the first report on the singlet oxygen quenching mechanism of these synthetic antioxidants. Practical Application: The synthetic antioxidants, especially TBHQ, have been found to have a strong singlet oxygen quenching ability. This article also clearly showed that singlet oxygen quenching by synthetic antioxidants was mainly by the physical quenching mechanism. The results suggested that these synthetic antioxidants, especially TBHQ, could be used practically for the protection

  19. Myocytes oxygenation and high energy phosphate levels during hypoxia.

    Directory of Open Access Journals (Sweden)

    Mohammad Nurulqadr Jameel

    Full Text Available Decrease of ambient oxygen level has been used in myocytes culture experiments in examining the responsiveness to stress secondary to hypoxia. However, none of these studies measure the myocytes oxygenation levels resulting in ambiguity as to whether there is insufficient oxygen delivery. This study examined the hypothesis that at a basal myocardial work state, adequate myocyte oxygenation would be maintained until extremely low arterial pO2 levels were reached. Myocyte pO2 values in normal dogs were calculated from the myocardial deoxymyoglobin (Mb- δ levels using (1H-spectroscopy (MRS and were normalized to Mb-δ obtained after complete LAD occlusion. During Protocol 1 (n = 6, Mb-δ was measured during sequential reductions of the oxygen fraction of inspired gas (FIO2 from 40, 21, 15, 10, and 5%, while in protocol 2 (n = 10 Mb-δ was measured at FIO2 of 3%. Protocol 3 (n = 9 evaluated time course of Mb-δ during prolonged exposure to FIO2 of 5%. Myocardial blood flow (MBF was measured with microspheres and high energy phosphate (HEP levels were determined with (31P-MRS. MVO2 progressively increased in response to the progressive reduction of FIO2 that is accompanied by increased LV pressure, heart rate, and MBF. Mb-δ was undetectable during FIO2 values of 21, 15, 10, and 5%. However, FIO2 of 3% or prolonged exposure to FIO2 of 5% caused progressive increases of Mb-δ which were associated with decreases of PCr, ATP and the PCr/ATP ratio, as well as increases of inorganic phosphate. The intracellular PO2 values for 20% reductions of PCr and ATP were approximately 7.4 and 1.9 mmHg, respectively. These data demonstrate that in the in vivo system over a wide range of FIO2 and arterial pO2 levels, the myocyte pO2 values remain well above the K(m value with respect to cytochrome oxidase, and oxygen availability does not limit mitochondrial oxidative phosphorylation at 5% FIO2.

  20. Chemical analysis and molecular models for calcium-oxygen-carbon interactions in black carbon found in fertile Amazonian anthrosoils.

    Science.gov (United States)

    Archanjo, Braulio S; Araujo, Joyce R; Silva, Alexander M; Capaz, Rodrigo B; Falcão, Newton P S; Jorio, Ado; Achete, Carlos A

    2014-07-01

    Carbon particles containing mineral matter promote soil fertility, helping it to overcome the rather unfavorable climate conditions of the humid tropics. Intriguing examples are the Amazonian Dark Earths, anthropogenic soils also known as "Terra Preta de Índio'' (TPI), in which chemical recalcitrance and stable carbon with millenary mean residence times have been observed. Recently, the presence of calcium and oxygen within TPI-carbon nanoparticles at the nano- and mesoscale ranges has been demonstrated. In this work, we combine density functional theory calculations, scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transformed infrared spectroscopy, and high resolution X-ray photoelectron spectroscopy of TPI-carbons to elucidate the chemical arrangements of calcium-oxygen-carbon groups at the molecular level in TPI. The molecular models are based on graphene oxide nanostructures in which calcium cations are strongly adsorbed at the oxide sites. The application of material science techniques to the field of soil science facilitates a new level of understanding, providing insights into the structure and functionality of recalcitrant carbon in soil and its implications for food production and climate change.

  1. The Chemical Evolution Carousel of Spiral Galaxies: Azimuthal Variations of Oxygen Abundance in NGC1365

    Science.gov (United States)

    Ho, I.-Ting; Seibert, Mark; Meidt, Sharon E.; Kudritzki, Rolf-Peter; Kobayashi, Chiaki; Groves, Brent A.; Kewley, Lisa J.; Madore, Barry F.; Rich, Jeffrey A.; Schinnerer, Eva; D’Agostino, Joshua; Poetrodjojo, Henry

    2017-09-01

    The spatial distribution of oxygen in the interstellar medium of galaxies is the key to understanding how efficiently metals that are synthesized in massive stars can be redistributed across a galaxy. We present here a case study in the nearby spiral galaxy NGC 1365 using 3D optical data obtained in the TYPHOON Program. We find systematic azimuthal variations of the H ii region oxygen abundance imprinted on a negative radial gradient. The 0.2 dex azimuthal variations occur over a wide radial range of 0.3–0.7 R 25 and peak at the two spiral arms in NGC 1365. We show that the azimuthal variations can be explained by two physical processes: gas undergoes localized, sub-kiloparsec-scale self-enrichment when orbiting in the inter-arm region, and experiences efficient, kiloparsec-scale mixing-induced dilution when spiral density waves pass through. We construct a simple chemical evolution model to quantitatively test this picture and find that our toy model can reproduce the observations. This result suggests that the observed abundance variations in NGC 1365 are a snapshot of the dynamical local enrichment of oxygen modulated by spiral-driven, periodic mixing and dilution.

  2. Removal of trichlorobenzene using 'oxygen-enriched' highly active absorbent.

    Science.gov (United States)

    Zhao, Yi; He, Peng; Zhang, Yu-Hai; Ma, Shuangchen

    2011-01-01

    Fly ash, industry lime and an additive, Ca(ClO2)2 (C) were used to prepare the 'oxygen-enriched' highly active absorbent (HAA). The influencing factors for removal of 1,2,4-trichlorobenzene (TCB) using this absorbent such as reaction temperature, simulating gas flow rate, oxygen content, etc. were studied in a self-designed reactor. The optimum experimental conditions of removing 1,2,4-TCB are that the content of an oxidizing additive in the absorbent is 3% (wt), simulating gas flow rate is 100 mL/min, reaction temperature is 250 degrees C, and the content of oxygen in simulating gas is 6%. The maximum removal efficiency is 81.71% in 10 mins. The absorption capacity of the absorbent is 0.000111 g/g. The reaction products were determined by gas chromatograph/mass spectrometer (GC/ MS), 2,6-Bis-[1,1-Dimethylethyl]-4-methyl-Phenol is considered to be the major intermediate product. The reaction route was revealed.

  3. Unusual High Oxygen Reduction Performance in All-Carbon Electrocatalysts

    Science.gov (United States)

    Wei, Wei; Tao, Ying; Lv, Wei; Su, Fang-Yuan; Ke, Lei; Li, Jia; Wang, Da-Wei; Li, Baohua; Kang, Feiyu; Yang, Quan-Hong

    2014-09-01

    Carbon-based electrocatalysts are more durable and cost-effective than noble materials for the oxygen reduction reaction (ORR), which is an important process in energy conversion technologies. Heteroatoms are considered responsible for the excellent ORR performance in many carbon-based electrocatalysts. But whether an all-carbon electrocatalyst can effectively reduce oxygen is unknown. We subtly engineered the interfaces between planar graphene sheets and curved carbon nanotubes (G-CNT) and gained a remarkable activity/selectivity for ORR (larger current, and n = 3.86, ~93% hydroxide + ~7% peroxide). This performance is close to that of Pt; and the durability is much better than Pt. We further demonstrate the application of this G-CNT hybrid as an all-carbon cathode catalyst for lithium oxygen batteries.We speculate that the high ORR activity of this G-CNT hybrid stems from the localized charge separation at the interface of the graphene and carbon nanotube, which results from the tunneling electron transfer due to the Fermi level mismatch on the planar and curved sp2 surfaces. Our result represents a conceptual breakthrough and pioneers the new avenues towards practical all-carbon electrocatalysis.

  4. A Highly Active Low Voltage Redox Mediator for Enhanced Rechargeability of Lithium-Oxygen Batteries.

    Science.gov (United States)

    Kundu, Dipan; Black, Robert; Adams, Brian; Nazar, Linda F

    2015-12-23

    Owing to its high theoretical specific energy, the Li-oxygen battery is one of the fundamentally most promising energy storage systems, but also one of the most challenging. Poor rechargeability, involving the oxidation of insoluble and insulating lithium peroxide (Li2O2), has remained the "Achilles' heel" of this electrochemical energy storage system. We report here on a new redox mediator tris[4-(diethylamino)phenyl]amine (TDPA), that-at 3.1 V-exhibits the lowest and closest potential redox couple compared to the equilibrium voltage of the Li-oxygen cell of those reported to date, with a second couple also at a low potential of 3.5 V. We show it is a soluble "catalyst" capable of lowering the Li2O2 charging potential by >0.8 V without requiring direct electrical contact of the peroxide and that it also facilitates high discharge capacities. Its chemical and electrochemical stability, fast diffusion kinetics, and two dynamic redox potentials represent a significant advance in oxygen-evolution catalysis. It enables Li-O2 cells that can be recharged more than 100 cycles with average round-trip efficiencies >80%, opening a new avenue for practical Li-oxygen batteries.

  5. LIFE Chamber Chemical Equilibrium Simulations with Additive Hydrogen, Oxygen, and Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    DeMuth, J A; Simon, A J

    2009-09-03

    In order to enable continuous operation of a Laser Inertial confinement Fusion Energy (LIFE) engine, the material (fill-gas and debris) in the fusion chamber must be carefully managed. The chamber chemical equilibrium compositions for post-shot mixtures are evaluated to determine what compounds will be formed at temperatures 300-5000K. It is desired to know if carbon and or lead will deposit on the walls of the chamber, and if so: at what temperature, and what elements can be added to prevent this from happening. The simulation was conducted using the chemical equilibrium solver Cantera with a Matlab front-end. Solutions were obtained by running equilibrations at constant temperature and constant specific volume over the specified range of temperatures. It was found that if nothing is done, carbon will deposit on the walls once it cools to below 2138K, and lead below 838K. Three solutions to capture the carbon were found: adding pure oxygen, hydrogen/nitrogen combo, and adding pure nitrogen. The best of these was the addition of oxygen which would readily form CO at around 4000K. To determine the temperature at which carbon would deposit on the walls, temperature solutions to evaporation rate equations needed to be found. To determine how much carbon or any species was in the chamber at a given time, chamber flushing equations needed to be developed. Major concerns are deposition of carbon and/or oxygen on the tungsten walls forming tungsten oxides or tungsten carbide which could cause embrittlement and cause failure of the first wall. Further research is needed.

  6. International Space Station (ISS) Oxygen High Pressure Storage Management

    Science.gov (United States)

    Lewis, John R.; Dake, Jason; Cover, John; Leonard, Dan; Bohannon, Carl

    2004-01-01

    High pressure oxygen onboard the ISS provides support for Extra Vehicular Activities (EVA) and contingency metabolic support for the crew. This high pressure 02 is brought to the ISS by the Space Shuttle and is transferred using the Oxygen Recharge Compressor Assembly (ORCA). There are several drivers that must be considered in managing the available high pressure 02 on the ISS. The amount of O2 the Shuttle can fly up is driven by manifest mass limitations, launch slips, and on orbit Shuttle power requirements. The amount of 02 that is used from the ISS high pressure gas tanks (HPGT) is driven by the number of Shuttle docked and undocked EVAs, the type of EVA prebreath protocol that is used and contingency use of O2 for metabolic support. Also, the use of the ORCA must be managed to optimize its life on orbit and assure that it will be available to transfer the planned amount of O2 from the Shuttle. Management of this resource has required long range planning and coordination between Shuttle manifest on orbit plans. To further optimize the situation hardware options have been pursued.

  7. Calcium and chemical looping technology for power generation and carbon dioxide (CO2) capture solid oxygen- and CO2-carriers

    CERN Document Server

    Fennell, Paul

    2015-01-01

    Calcium and Chemical Looping Technology for Power Generation and Carbon Dioxide (CO2) Capture reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to chemical looping and combustion. Chapters review the market development, economics, and deployment of these systems, also providing detailed information on the variety of materials and processes that will help to shape the future of CO2 capture ready power plants. Reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to calcium and chemical loopingProvi

  8. NOx emissions from high swirl turbulent spray flames with highly oxygenated fuels

    KAUST Repository

    Bohon, Myles

    2013-01-01

    Combustion of fuels with fuel bound oxygen is of interest from both a practical and a fundamental viewpoint. While a great deal of work has been done studying the effect of oxygenated additives in diesel and gasoline engines, much less has been done examining combustion characteristics of fuels with extremely high mass fractions of fuel bound oxygen. This work presents an initial investigation into the very low NOx emissions resulting from the combustion of a model, high oxygen mass fraction fuel. Glycerol was chosen as a model fuel with a fuel bound oxygen mass fraction of 52%, and was compared with emissions measured from diesel combustion at similar conditions in a high swirl turbulent spray flame. This work has shown that high fuel bound oxygen mass fractions allow for combustion at low global equivalence ratios with comparable exhaust gas temperatures due to the significantly lower concentrations of diluting nitrogen. Despite similar exhaust gas temperatures, NOx emissions from glycerol combustion were up to an order of magnitude lower than those measured using diesel fuel. This is shown to be a result not of specific burner geometry, but rather is influenced by the presence of higher oxygen and lower nitrogen concentrations at the flame front inhibiting NOx production. © 2012 The Combustion Institute.

  9. Chromium (VI) biosorption and removal of chemical oxygen demand by Spirulina platensis from wastewater-supplemented culture medium.

    Science.gov (United States)

    Magro, Clinei D; Deon, Maitê C; De Rossi, Andreia; Reinehr, Christian O; Hemkemeier, Marcelo; Colla, Luciane M

    2012-01-01

    The inappropriate discharge of wastewater containing high concentrations of toxic metals is a serious threat to the environment. Given that the microalga Spirulina platensis has demonstrated a capacity for chromium VI (Cr (VI) biosorption, we assessed the ideal concentration of chromium-containing wastewater required for maximum removal of Cr (VI) and chemical oxygen demand (COD) from the environment by using this microalga. The Paracas and Leb-52 strains of S. platensis, with initial wastewater concentrations of 0%, 12.5%, 25%, and 50%, were cultured in Zarrouk medium diluted to 50% under controlled air, temperature, and lighting conditions. The cultures were maintained for 28 days, and pH, biomass growth, COD, and Cr (VI) were assessed. The wastewater concentration influenced microalgal growth, especially at high concentrations. Removal of 82.19% COD and 60.92% Cr (VI) was obtained, but the COD removal was greater than the Cr (VI) removal in both strains of S. platensis.

  10. Pulse Operation of Chemical Oxygen-Iodine Laser by Pulsed Gas Discharge with the Assistance of Spark Pre-ionization

    Institute of Scientific and Technical Information of China (English)

    LI Guo-Fu; YU Hai-Jun; DUO Li-Ping; JIN Yu-Qi; WANG Jian; SANG Feng-Ting; FANG Ben-Jie; WANG De-Zhen

    2009-01-01

    The continuous wavelength chemical oxygen-iodine laser can be turned into pulse operation mode in order to obtain high energy and high pulse power. We propose an approach to produce iodine atoms instantaneously by pulsed gas discharge with the assistance of spark pre-ionization to achieve the pulsed goal. The influence of spark pre-ionization on discharge homogeneity is discussed. Voltage-current characteristics are shown and discussed in existence of the pre-ionization capacitor and peaking capacitor. The spark pre-ionization and peaking capacitor are very helpful in obtaining a stable and homogeneous discharge. The lasing is achieved at the total pressure of 2.2-2.9 kPa and single pulse energy is up to 180m J, the corresponding specific output energy is 1.0 J/L.

  11. The influence of iridium chemical oxidation state on the performance and durability of oxygen evolution catalysts in PEM electrolysis

    Science.gov (United States)

    Siracusano, S.; Baglio, V.; Grigoriev, S. A.; Merlo, L.; Fateev, V. N.; Aricò, A. S.

    2017-10-01

    Nanosized Ir-black (3 nm) and Ir-oxide (5 nm) oxygen evolution electrocatalysts showing high performance in polymer electrolyte membrane (PEM) water electrolysis based on Aquivion® short-side chain ionomer membrane are investigated to understand the role of the Ir oxidation state on the electrocatalytic activity and stability. Despite the smaller mean crystallite size, the Ir-black electrocatalyst shows significantly lower initial performance than the Ir-oxide. During operation at high current density, the Ir-black shows a decrease of cell potential with time whereas the Ir-oxide catalyst shows increasing cell potential resulting in a degradation rate of about 10 μV/h, approaching 1000 h. The unusual behaviour of the Ir-black results from the oxidation of metallic Ir to IrOx. The Ir-oxide catalyst shows instead a hydrated structure on the surface and a negative shift of about 0.5 eV for the Ir 4f binding energy after 1000 h electrolysis operation. This corresponds to the formation of a sub-stoichiometric Ir-oxide on the surface. These results indicate that a hydrated IrO2 with high oxidation state on the surface is favourable in decreasing the oxygen evolution overpotential. Modifications of the Ir chemical oxidation state during operation can affect significantly the catalytic activity and durability of the electrolysis system.

  12. Catalytic recombination of nitrogen and oxygen on high-temperature reusable surface insulation

    Science.gov (United States)

    Scott, C. D.

    1980-01-01

    The energy transfer catalytic recombination coefficient for nitrogen and oxygen recombination on the surface coating of high-temperature reusable surface insulation (HRSI) is inferred from stagnation point heat flux measurements in a high-temperature dissociated arc jet flow. The resulting catalytic recombination coefficients are correlated with an Arrhenius model for convenience, and these expressions may be used to account for catalytic recombination effects in predictions of the heat flux on the HRSI thermal protection system of the Space Shuttle Orbiter during reentry flight. Analysis of stagnation point pressure and total heat balance enthalpy measurements indicates that the arc heater reservoir conditions are not in chemical equilibrium. This is contrary to what is usually assumed for arc jet analysis and indicates the need for suitable diagnostics and analyses, especially when dealing with chemical reaction phenomena such as catalytic recombination heat transfer effects.

  13. Nonstoichiometric perovskite CaMnO(3-δ) for oxygen electrocatalysis with high activity.

    Science.gov (United States)

    Du, Jing; Zhang, Tianran; Cheng, Fangyi; Chu, Wangsheng; Wu, Ziyu; Chen, Jun

    2014-09-01

    Perovskite oxides offer efficient and cheap electrocatalysts for both oxygen reduction reactions and oxygen evolution reactions (ORR/OER) in diverse oxygen-based electrochemical technologies. In this study, we report a facile strategy to enhance the electrocatalytic activity of CaMnO3 by introducing oxygen defects. The nonstoichiometric CaMnO(3-δ) (0 < δ ≤ 0.5) was prepared through thermal reduction of pristine perovskite microspheres and nanoparticles, which were synthesized from thermal-decomposition of carbonate precursors and the Pechini route, respectively. The as-prepared samples were analyzed by chemical titration, structural refinement, thermogravimetric analysis, and energy spectrometry. In 0.1 M KOH aqueous solution, the nonstoichiometric CaMnO(3-δ) with δ near 0.25 and an average Mn valence close to 3.5 exhibited the highest ORR activity (36.7 A g(-1) at 0.70 V vs RHE, with onset potential of 0.96 V), which is comparable to that of benchmark Pt/C. Density functional theory (DFT) studies and electrical conductivity measurement revealed that the enhanced ORR kinetics is due to facilitated oxygen activation and improved electrical properties. Besides high activity, the nonstoichiometric perovskite oxides showed respectable catalytic stability. Furthermore, the moderate oxygen-defective CaMnO(3-δ) (δ ≈ 0.25) favored the OER because of the improved electrical conductivity. This study makes nonstoichiometric CaMnO(3-δ) a promising active, inexpensive bifunctional catalytic material for reversible ORR and OER.

  14. The mystery of gold's chemical activity: local bonding, morphology and reactivity of atomic oxygen.

    Science.gov (United States)

    Baker, Thomas A; Liu, Xiaoying; Friend, Cynthia M

    2011-01-07

    Recently, gold has been intensely studied as a catalyst for key synthetic reactions. Gold is an attractive catalyst because, surprisingly, it is highly active and very selective for partial oxidation processes suggesting promise for energy-efficient "green" chemistry. The underlying origin of the high activity of Au is a controversial subject since metallic gold is commonly thought to be inert. Herein, we establish that one origin of the high activity for gold catalysis is the extremely reactive nature of atomic oxygen bound in 3-fold coordination sites on metallic gold. This is the predominant form of O at low concentrations on the surface, which is a strong indication that it is most relevant to catalytic conditions. Atomic oxygen bound to metallic Au in 3-fold sites has high activity for CO oxidation, oxidation of olefins, and oxidative transformations of alcohols and amines. Among the factors identified as important in Au-O interaction are the morphology of the surface, the local binding site of oxygen, and the degree of order of the oxygen overlayer. In this Perspective, we present an overview of both theory and experiments that identify the reactive forms of O and their associated charge density distributions and bond strengths. We also analyze and model the release of Au atoms induced by O binding to the surface. This rough surface also has the potential for O(2) dissociation, which is a critical step if Au is to be activated catalytically. We further show the strong parallels between product distributions and reactivity for O-covered Au at low pressure (ultrahigh vacuum) and for nanoporous Au catalysts operating at atmospheric pressure as evidence that atomic O is the active species under working catalytic conditions when metallic Au is present. We briefly discuss the possible contributions of oxidants that may contain intact O-O bonds and of the Au-metal oxide support interface in Au catalysis. Finally, the challenges and future directions for fully

  15. Treatment test of supernatant from sewage sludge by irradiation of high energy electron beams under supersaturation with oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Hosono, Masakazu; Arai, Hidehiko (Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment); Aizawa, Masaki; Shimooka, Toshio; Yamamoto, Ichiro; Shimizu, Ken; Sugiyama, Masashi.

    1993-02-01

    Supernatant comes from dewaterization of sewage sludge, and contains biologically nondegradable organics. Therefore, it is hard to be treated by conventional activated sludge method. The development of a new technology is required to decrease the chemical oxygen demand (COD) effectively below 30 mg/l. Irradiation of high energy electron beams can convert nondegradable organics in water into substances which are biodegradable. However, sufficient dissolved oxygen in water is needed to induce oxidation effectively. In the present study, the treatment of supernatant was studied using an apparatus which can be irradiated by high intensity electron beams in flow system under supersaturation with oxygen by pressurization up to 3 atms. The dependence of oxygen concentration on the reduction in absorbance at 230 nm of azo dye (Acid Red 265) aqueous solution was examined, and it was clarified that sufficient oxygen was supplied in the solution up to about 14 kGy under 3 atms of oxygen. Radiation treatment of supernatant which came from the leather works was carried out using the above apparatus. However, as this supernatant contained high concentration of nitrite, the nitrite was removed by limited aeration activated sludge method. By this pretreatment, COD was reduced from 200 mg/l to 53 mg/l. Then, the biodegradability of supernatant irradiated under supersaturation with oxygen was examined. The final COD of the supernatant was reduced below 30 mg/l by the combined method of irradiation of 7 kGy and biological treatment. (author).

  16. Modelling chemical reactions in dc plasma inside oxygen bubbles in water

    Science.gov (United States)

    Takeuchi, N.; Ishii, Y.; Yasuoka, K.

    2012-02-01

    Plasmas generated inside oxygen bubbles in water have been developed for water purification. Zero-dimensional numerical simulations were used to investigate the chemical reactions in plasmas driven by dc voltage. The numerical and experimental results of the concentrations of hydrogen peroxide and ozone in the solution were compared with a discharge current between 1 and 7 mA. Upon increasing the water vapour concentration inside bubbles, we saw from the numerical results that the concentration of hydrogen peroxide increased with discharge current, whereas the concentration of ozone decreased. This finding agreed with the experimental results. With an increase in the discharge current, the heat flux from the plasma to the solution increased, and a large amount of water was probably vaporized into the bubbles.

  17. A pressure recovery system for chemical oxygen-iodine laser based on an active diffuser

    Science.gov (United States)

    Malkov, V. M.; Kiselev, I. A.; Orlov, A. E.; Shatalov, I. V.

    2011-09-01

    An open-type pressure recovery system (PRS) for chemical oxygen-iodine laser was designed and fabricated. As a first stage, an active diffuser was used in which the ejecting gas supply was organized through nozzles disposed around the channel periphery. The second stage was a supersonic ejector. Numerical simulation data for the viscous turbulent flow with heat release through the diffuser gas-dynamic channel, and also data obtained by testing the active diffuser in operation on a model facility equipped with a vacuum chamber, are reported. The obtained data were used to develop a full-scale setup with exhaust of laser gas into the atmosphere; this has allowed us to optimize the performance characteristics of the setup and substantially improve its mass-dimensional characteristics. Special attention was paid to parameter matching and synchronization of laser start with the operation of PRS components.

  18. Plasma chemical and electrical modelling of a negative DC corona in pure oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Soria, C [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Pontiga, F [Departamento de FIsica Aplicada II, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Castellanos, A [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain)

    2004-02-01

    A complex plasma chemical and electrical model of a negative stationary wire-to-cylinder corona discharge in pure oxygen is presented. The corona discharge is assumed to have axial and azimuthal symmetry. The experimental current-voltage characteristic is required as input data, but there are no other adjustable or empirical parameters. The experimental validation of the results of the model comes from its prediction of the ozone concentration. The role played by different reactions and species is analysed in detail using the results of the simulation. The effect of the gas temperature and of the decomposition of ozone at the electrodes is also investigated. The agreement between the model and the experiments is excellent when the effect of ozone decomposition at the electrodes is taken into account.

  19. Study on Determination of Chemical Oxygen Demand in Water with Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong-Hai; DING Hong-Chun; FANG Yan-Ju; XIAN Yue-Zhong; JIN Li-Tong

    2007-01-01

    A new method for determining chemical oxygen demand (COD) value in water using ion chromatography coupled with nano TiO2-K2S2O8 co-existing system was described. The photocatalytic oxidation system and nano TiO2-K2S2O8 co-existing system could degrade the organic compounds in water. All sulfur-containing species in the reactive solution were eventually transformed to sulfate which could be determined by conductivity detector in ion chromatography. The change of conductivity of sulfate was proportional to COD value. The optimal experimental conditions and the mechanism of the detection were discussed. The application range was 10.0-300.0 mg·L -1 and the lowest limit of detection was 3.5 mg·L -1. It was considered that the value obtained could be reliably correlated with the COD value obtained using the conventional methods.

  20. Chemical Oxygen Demand of Seawater Determined with a Microwave Heating Method

    Institute of Scientific and Technical Information of China (English)

    LIU Li; JI Hongwei; LIU Ying; XIN Huizhen

    2005-01-01

    This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.

  1. Modifications in physico-chemical properties of 100 MeV oxygen ions irradiated polyimide Kapton-H polymer

    Science.gov (United States)

    Gupta, Sanjeev Kumar; Gupta, Rashi; Singh, Paramjit; Kumar, Vikas; Jaiswal, Manoj Kumar; Chakarvarti, S. K.; Kumar, Rajesh

    2017-09-01

    The optical, structural and chemical properties of polyimide Kapton-H polymer thin film samples were modified by irradiation with 100 MeV O7+ ions (in the fluence range of 1 × 1011 to 5 × 1012 ions/cm2) and the modifications of these properties were observed by UV-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy respectively. The band gap energy of the polymer decreased considerably with discrete increment of the ion fluence (different fluence for each sample) and effective change for the sample irradiated at a fluence of 5 × 1012 ions/cm2 was observed from that of pristine sample. The amorphous nature of the polymer was observed to be decreased with increase of ion fluence. The vibrations of Ctbnd C appeared at mid fluences but the stretching vibrations of Osbnd H bond disappeared at these fluences due to the high LET of the oxygen ions.

  2. Converting Chemical Oxygen Demand (COD) of Cellulosic Ethanol Fermentation Wastewater into Microbial Lipid by Oleaginous Yeast Trichosporon cutaneum.

    Science.gov (United States)

    Wang, Juan; Hu, Mingshan; Zhang, Huizhan; Bao, Jie

    2017-01-27

    Cellulosic ethanol fermentation wastewater is the stillage stream of distillation column of cellulosic ethanol fermentation broth with high chemical oxygen demand (COD). The COD is required to reduce before the wastewater is released or recycled. Without any pretreatment nor external nutrients, the cellulosic ethanol fermentation wastewater bioconversion by Trichosporon cutaneum ACCC 20271 was carried out for the first time. The major components of the wastewater including glucose, xylose, acetic acid, ethanol, and partial of phenolic compounds could be utilized by T. cutaneum ACCC 20271. In a 3-L bioreactor, 2.16 g/L of microbial lipid accumulated with 55.05% of COD reduced after a 5-day culture of T. cutaneum ACCC 20271 in the wastewater. The fatty acid composition of the derived microbial lipid was similar with vegetable oil, in which it could be used as biodiesel production feedstock. This study will both solve the environmental problem and offer low-cost lipid feedstock for biodiesel production.

  3. Can Galactic chemical evolution explain the oxygen isotopic variations in the Solar System?

    CERN Document Server

    Lugaro, Maria; Ireland, Trevor R; Maddison, Sarah T

    2012-01-01

    A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced 16O-rich CO and 16O-poor H2O, where the H2O subsequently combined with interstellar dust to form relatively 16O-poor solids within the Solar Nebula. Another model for creating the different reservoirs of 16O-rich gas and 16O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the Solar System dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the Solar System. The GCE scenario is in contradiction with observations of the 18O/17O ratios in nearby molecular clouds and young stellar objects. ...

  4. A Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C K; Pitz, W J; Curran, H J

    2005-11-14

    A detailed chemical kinetic modeling approach is used to examine the phenomenon of suppression of sooting in diesel engines by addition of oxygenated hydrocarbon species to the fuel. This suppression, which has been observed experimentally for a few years, is explained kinetically as a reduction in concentrations of soot precursors present in the hot products of a fuel-rich diesel ignition zone when oxygenates are included. Oxygenates decrease the overall equivalence ratio of the igniting mixture, producing higher ignition temperatures and more radical species to consume more soot precursor species, leading to lower soot production. The kinetic model is also used to show how different oxygenates, ester structures in particular, can have different soot-suppression efficiencies due to differences in molecular structure of the oxygenated species.

  5. A Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C K; Pitz, W J; Curran, H J

    2005-11-14

    A detailed chemical kinetic modeling approach is used to examine the phenomenon of suppression of sooting in diesel engines by addition of oxygenated hydrocarbon species to the fuel. This suppression, which has been observed experimentally for a few years, is explained kinetically as a reduction in concentrations of soot precursors present in the hot products of a fuel-rich diesel ignition zone when oxygenates are included. Oxygenates decrease the overall equivalence ratio of the igniting mixture, producing higher ignition temperatures and more radical species to consume more soot precursor species, leading to lower soot production. The kinetic model is also used to show how different oxygenates, ester structures in particular, can have different soot-suppression efficiencies due to differences in molecular structure of the oxygenated species.

  6. Tetranitroacetimidic acid: a high oxygen oxidizer and potential replacement for ammonium perchlorate.

    Science.gov (United States)

    Vo, Thao T; Parrish, Damon A; Shreeve, Jean'ne M

    2014-08-27

    Considerable work has been focused on developing replacements for ammonium perchlorate (AP), a primary choice for solid rocket and missile propellants, due to environmental concerns resulting from the release of perchlorate into groundwater systems [corrected]. Additionally, the generation of hydrochloric acid contributes to high concentrations of acid rain and to ozone layer depletion. En route to synthesizing salts that contain cationic FOX-7, a novel, high oxygen-containing oxidizer, tetranitroacetimidic acid (TNAA), has been synthesized and fully characterized. The properties of TNAA were found to be exceptional, with a calculated specific impulse exceeding that of AP, leading to its high potential as a replacement for AP. TNAA can be synthesized easily in a one-step process by the nitration of FOX-7 in high yield (>93%). The synthesis, properties, and chemical reactivity of TNAA have been examined.

  7. Chemical diffusion coefficient of oxygen in thoria-urania mixed oxide

    Science.gov (United States)

    Matsui, Tsuneo; Naito, Keiji

    1985-10-01

    The chemical diffusion coefficients of oxygen ( D˜) in sintered samples of ( Th1- yUy) O2+ x ( y = 0.2 and 0.4) were measured by means of thermogravimetry in the temperature range 1282 ⩽ T ⩽ 1373 K. The defect diffusion coefficients ( Dd) were also calculated from the chemical diffusion coefficients obtained in this study. The activation energies of D˜ or Dd for the two samples ( Th1- yUy) O2+ xwithy = 0.2 and 0.4 were observed to be nearly the same, irrespective of the y value. These activation energies also nearly coincided with those of UO 2+x reported previously, suggesting the presence of a similar diffusion mechanism to that found in UO 2+x. The magnitude of both diffusion coefficients D˜ and Dd of ( Th1- yUy) O2+ x increased with increasing uranium content and approached that of UO 2+x. The increase of Dd of ( Th1- yUy) O2+ x with y value was considered to be due to the increase of both the vibrational frequency of lattice and the entropy change of migration produced by the substitution of a U ion for a Th ion.

  8. Chemometrics-assisted spectrophotometry method for the determination of chemical oxygen demand in pulping effluent.

    Science.gov (United States)

    Chen, Honglei; Chen, Yuancai; Zhan, Huaiyu; Fu, Shiyu

    2011-04-01

    A new method has been developed for the determination of chemical oxygen demand (COD) in pulping effluent using chemometrics-assisted spectrophotometry. Two calibration models were established by inducing UV-visible spectroscopy (model 1) and derivative spectroscopy (model 2), combined with the chemometrics software Smica-P. Correlation coefficients of the two models are 0.9954 (model 1) and 0.9963 (model 2) when COD of samples is in the range of 0 to 405 mg/L. Sensitivities of the two models are 0.0061 (model 1) and 0.0056 (model 2) and method detection limits are 2.02-2.45 mg/L (model 1) and 2.13-2.51 mg/L (model 2). Validation experiment showed that the average standard deviation of model 2 was 1.11 and that of model 1 was 1.54. Similarly, average relative error of model 2 (4.25%) was lower than model 1 (5.00%), which indicated that the predictability of model 2 was better than that of model 1. Chemometrics-assisted spectrophotometry method did not need chemical reagents and digestion which were required in the conventional methods, and the testing time of the new method was significantly shorter than the conventional ones. The proposed method can be used to measure COD in pulping effluent as an environmentally friendly approach with satisfactory results.

  9. Electrochemical treatment of rice grain-based distillery effluent: chemical oxygen demand and colour removal.

    Science.gov (United States)

    Prajapati, Abhinesh Kumar; Chaudhari, Parmesh Kumar

    2014-01-01

    The electrochemical (EC) treatment of rice grain-based distillery wastewater was carried out in a 1.5 dm3 electrolytic batch reactor using aluminium plate electrodes. With the four-plate configurations, a current density (j) of 89.3 A/m2 and pH 8 was found to be optimal, obtaining a maximum chemical oxygen demand (COD) and colour removal of 93% and 87%, respectively. The chemical dissolution of aluminium was strongly influenced by initial pH (pHi). At higher pHi (pH 9.5) anode consumption decreased while energy consumption increased. At the optimal current density 89.3 A/m2, the aluminium electrode consumption was 16.855 g/dm3 wastewater and energy consumption was 31.4 Wh/dm3 achieving a maximum COD removal of 87%. The settling and filterability characteristics ofelectrochemically treated sludge were also analysed at different pH. It was noted that treated slurry at pHi 9.5 gave best settling characteristic, which decreased with increase in pH. EC-treated effluent at pHi 8 had provided best filterability. Characteristics of scum and residues are also analysed at different pH.

  10. Toddlers at High Risk of Chemical Eye Burns

    Science.gov (United States)

    ... fullstory_160258.html Toddlers at High Risk of Chemical Eye Burns: Study Access to household cleaning products to blame, ... and 2 years have relatively high rates of chemical eye burns, with everyday cleaners a common cause, researchers say. ...

  11. High temperature chemically resistant polymer concrete

    Science.gov (United States)

    Sugama, T.; Kukacka, L.E.

    High temperature chemically resistant, non-aqueous polymer concrete composites consist of about 12 to 20% by weight of a water-insoluble polymer binder. The binder is polymerized in situ from a liquid vinyl-type monomer or mixture of vinyl containing monomers such as triallylcyanurate, styrene, acrylonitrile, acrylamide, methacrylamide, methyl-methacrylate, trimethylolpropane trimethacrylate and divinyl benzene. About 5 to 40% by weight of a reactive inorganic filler selected from the group consisting of tricalcium silicate and dicalcium silicate and mixtures containing less than 2% free lime, and about 48 to 83% by weight of silica sand/ and a free radical initiator such as di-tert-butyl peroxide, azobisisobutyronitrile, benzoyl peroxide, lauryl peroxide, other orgaic peroxides and combinations to initiate polymerization of the monomer in the presence of the inorganic filers are used.

  12. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    KAUST Repository

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  13. CAN GALACTIC CHEMICAL EVOLUTION EXPLAIN THE OXYGEN ISOTOPIC VARIATIONS IN THE SOLAR SYSTEM?

    Energy Technology Data Exchange (ETDEWEB)

    Lugaro, Maria [Monash Centre for Astrophysics (MoCA), Building 28, Monash University, Clayton, VIC 3800 (Australia); Liffman, Kurt [CSIRO/MSE, P.O. Box 56, Highett, VIC 3190 (Australia); Ireland, Trevor R. [Planetary Science Institute and Research School of Earth Sciences, Australian National University, Canberra, ACT 0200 (Australia); Maddison, Sarah T., E-mail: maria.lugaro@monash.edu [Centre for Astrophysics and Supercomputing, Swinburne University, H39, P.O. Box 218, Hawthorn, VIC 3122 (Australia)

    2012-11-01

    A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced {sup 16}O-rich CO and {sup 16}O-poor H{sub 2}O, where the H{sub 2}O subsequently combined with interstellar dust to form relatively {sup 16}O-poor solids within the solar nebula. Another model for creating the different reservoirs of {sup 16}O-rich gas and {sup 16}O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the solar system dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the solar system. The GCE scenario is in contradiction with observations of the {sup 18}O/{sup 17}O ratios in nearby molecular clouds and young stellar objects. It is very unlikely for GCE to produce a line of slope one when considering the effect of incomplete mixing of stellar ejecta in the interstellar medium. Furthermore, the assumption that the solar system dust was younger than the gas requires unusual timescales or the existence of an important stardust component that is not theoretically expected to occur nor has been identified to date.

  14. Chemical exposure-response relationship between air pollutants and reactive oxygen species in the human respiratory tract

    Science.gov (United States)

    Lakey, P. S. J.; Berkemeier, T.; Tong, H.; Arangio, A. M.; Lucas, K.; Poeschl, U.; Shiraiwa, M.

    2016-12-01

    The inhalation of air pollutants such as O3 and particulate matter can lead to the formation of reactive oxygen species (ROS) which can cause damage to biosurfaces such as the lung epithelium unless they are effectively scavenged. Although the chemical processes that lead to ROS formation within the ELF upon inhalation of pollutants are well understood qualitatively, ROS concentrations within the ELF have hardly been quantified so far. The kinetic multi-layer model of surface and bulk chemistry in the epithelial lining fluid (KM-SUB-ELF) has been developed to describe chemical reactions and mass transport and to quantify ROS production rates and concentrations within the epithelial lining fluid. KM-SUB-ELF simulations suggest that O3 will rapidly saturate the ELF whereas antioxidants and surfactant species are effective scavengers of OH. High ambient concentrations of O3 can lead to the depletion of surfactants and antioxidants within the ELF, potentially leading to oxidative stress. KM-SUB-ELF reproduced measurements for the formation of H2O2 and OH due to the presence of iron, copper and quinones in surrogate lung lining fluid. This enabled ROS production rates and concentrations in the ELF to be quantified. We found that in polluted megacities the ROS concentration in the ELF due to inhalation of pollutants was at least as high as the concentrations in the ELF of patients suffering from respiratory diseases. Cu and Fe are found to be the most important redox-active aerosol components for ROS production upon inhalation of PM2.5 in polluted regions. Therefore, a reduction in the emission of Cu and Fe should be major targets of air pollution control. Chemical exposure-response relations provide a quantitative basis for assessing the relative importance of specific air pollutants in different regions of the world, showing that aerosol-induced epithelial ROS levels in polluted megacity air can be several orders of magnitude higher than in pristine rainforest air.

  15. Formation of Nanocones on Highly Oriented Pyrolytic Graphite by Oxygen Plasma

    Directory of Open Access Journals (Sweden)

    Alenka Vesel

    2014-03-01

    Full Text Available Improvement in hemocompatibility of highly oriented pyrolytic graphite (HOPG by formation of nanostructured surface by oxygen plasma treatment is reported. We have showed that by appropriate fine tuning of plasma and discharge parameters we are able to create nanostructured surface which is densely covered with nanocones. The size of the nanocones strongly depended on treatment time. The optimal results in terms of material hemocompatibility were obtained after treatment with oxygen plasma for 15 s, when both the nanotopography and wettability were the most favorable, since marked reduction in adhesion and activation of platelets was observed on this surface. At prolonged treatment times, the rich surface topography was lost and thus also its antithrombogenic properties. Chemical composition of the surface was always more or less the same, regardless of its morphology and height of the nanocones. Namely, on all plasma treated samples, only a few atomic percent of oxygen was found, meaning that plasma caused mostly etching, leading to changes in the surface morphology. This indicates that the main preventing mechanism against platelets adhesion was the right surface morphology.

  16. Removal of chemical oxygen demand and dissolved nutrients by a sunken lawn infiltration system during intermittent storm events.

    Science.gov (United States)

    Hou, Lizhu; Yang, Huan; Li, Ming

    2014-01-01

    Urban surface water runoff typically contains high but varying amounts of organic matter and nutrients that require removal before reuse. Infiltration systems such as sunken lawns can improve water quality. However, there is currently insufficient information describing the treatment efficiency of lawn-based infiltration systems. In this study, novel sunken lawn infiltration systems (SLISs) were designed and their pollutant removal effectiveness was assessed. The results revealed that SLISs with Poa pratensis and Lolium perenne effectively removed most chemical oxygen demand (CODCr) and dissolved nutrients. Average CODCr, total nitrogen (TN), ammonium-nitrogen (NH4(+)-N) and total phosphorus (TP) concentrations were reduced by 78.93, 66.64, 71.86 and 75.83%, respectively, and the corresponding effluent concentrations met the standard for urban miscellaneous water consumption in China. The NH4(+)-N in the synthetic runoff was shown to be removed by adsorption during the stormwater dosing and nitrification during subsequent dry days, as well as through uptake by plants. Phosphorus was mainly removed by adsorption and chemical precipitation. The NH4(+)-N and phosphorus Langmuir isotherm model fitted the clay loam soil adsorption process better than the Freundlich model. Overall, these results indicate that an SLIS provides an alternative means of removing runoff pollutants owing to its efficiency, easy operation and maintenance.

  17. Particulate Formation from a Copper Oxide-Based Oxygen Carrier in Chemical Looping Combustion for CO2 Capture

    Science.gov (United States)

    Attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane chemical looping combustion (CLC) process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling...

  18. Particulate Formation from a Copper Oxide-Based Oxygen Carrier in Chemical Looping Combustion for CO2 Capture

    Science.gov (United States)

    Attrition behavior and particle loss of a copper oxide-based oxygen carrier from a methane chemical looping combustion (CLC) process was investigated in a fluidized bed reactor. The aerodynamic diameters of most elutriated particulates, after passing through a horizontal settling...

  19. Influence of Matrices on Oxygen Sensing of Three Sensing Films with Chemically Conjugated Platinum Porphyrin Probes and Preliminary Application for Monitoring of Oxygen Consumption of Escherichia coli (E. coli)

    OpenAIRE

    Tian, Yanqing; Shumway, Bradley R.; Gao, Weimin; Youngbull, Cody; Holl, Mark R.; Johnson, Roger H.; Meldrum, Deirdre R.

    2010-01-01

    Oxygen sensing films were synthesized by a chemical conjugation of functional platinum porphyrin probes in silica gel, polystyrene (PS), and poly(2-hydroxyethyl methacrylate) (PHEMA) matrices. Responses of the sensing films to gaseous oxygen and dissolved oxygen were studied and the influence of the matrices on the sensing behaviors was investigated. Silica gel films had the highest fluorescence intensity ratio from deoxygenated to oxygenated environments and the fastest response time to oxyg...

  20. High Temperature Materials for Chemical Propulsion Applications

    Science.gov (United States)

    Elam, Sandra; Hickman, Robert; O'Dell, Scott

    2007-01-01

    Radiation or passively cooled thrust chambers are used for a variety of chemical propulsion functions including apogee insertion, reaction control for launch vehicles, and primary propulsion for planetary spacecraft. The performance of these thrust chambers is limited by the operating temperature of available materials. Improved oxidation resistance and increased operating temperatures can be achieved with the use of thermal barrier coatings such as zirconium oxide (ZrO2) and hafnium oxide (HfO2). However, previous attempts to include these materials showed cracking and spalling of the oxide layer due to poor bonding. Current research at NASA's Marshall Space Flight Center (MSFC) has generated unique, high temperature material options for in-space thruster designs that are capable of up to 2500 C operating temperatures. The research is focused on fabrication technologies to form low cost Iridium,qF_.henium (Ir/Re) components with a ceramic hot wall created as an integral, functionally graded material (FGM). The goal of this effort is to further de?celop proven technologies for embedding a protective ceramic coating within the Ir/Re liner to form a robust functional gradient material. Current work includes the fabrication and testing of subscale samples to evaluate tensile, creep, thermal cyclic/oxidation, and thermophysical material properties. Larger test articles have also being fabricated and hot-fire tested to demonstrate the materials in prototype thrusters at 1O0 lbf thrust levels.

  1. High-oxygen and high-carbon dioxide containing atmospheres inhibit growth of food associated moulds

    NARCIS (Netherlands)

    Hoogerwerf, S.W.; Kets, E.P.W.; Dijksterhuis, J.

    2002-01-01

    Aims: The objective of this study was to determine the relationship between the growth of three foodborne fungi and high-oxygen modified atmosphere. Methods and Results: Petri dishes were incubated in a series of connected flasks, which were placed in a climatized room and flushed continuously with

  2. High-oxygen and high-carbon dioxide containing atmospheres inhibit growth of food associated moulds

    NARCIS (Netherlands)

    Hoogerwerf, S W; Kets, E P W; Dijksterhuis, J

    2002-01-01

    AIMS: The objective of this study was to determine the relationship between the growth of three foodborne fungi and high-oxygen modified atmosphere. METHODS AND RESULTS: Petri dishes were incubated in a series of connected flasks, which were placed in a climatized room and flushed continuously with

  3. Effect of Gasifying Medium on the Coal Chemical Looping Gasification with CaSO4 as Oxygen Carrier☆

    Institute of Scientific and Technical Information of China (English)

    Yongzhuo Liu; Weihua Jia; Qingjie Guo; Hojung Ryu

    2014-01-01

    The chemical looping gasification uses an oxygen carrier for solid fuel gasification by supplying insufficient lattice oxygen. The effect of gasifying medium on the coal chemical looping gasification with CaSO4 as oxygen carrier is investigated in this paper. The thermodynamical analysis indicates that the addition of steam and CO2 into the system can reduce the reaction temperature, at which the concentration of syngas reaches its maximum value. Experimental result in thermogravimetric analyzer and a fixed-bed reactor shows that the mixture sample goes through three stages, drying stage, pyrolysis stage and chemical looping gasification stage, with the temper-ature for three different gaseous media. The peak fitting and isoconversional methods are used to determine the reaction mechanism of the complex reactions in the chemical looping gasification process. It demonstrates that the gasifying medium (steam or CO2) boosts the chemical looping process by reducing the activation energy in the overall reaction and gasification reactions of coal char. However, the mechanism using steam as the gasifying medium differs from that using CO2. With steam as the gasifying medium, parallel reactions occur in the begin-ning stage, followed by a limiting stage shifting from a kinetic to a diffusion regime. It is opposite to the reaction mechanism with CO2 as the gasifying medium.

  4. Peroxone mineralization of chemical oxygen demand for direct potable water reuse: Kinetics and process control.

    Science.gov (United States)

    Wu, Tingting; Englehardt, James D

    2015-04-15

    Mineralization of organics in secondary effluent by the peroxone process was studied at a direct potable water reuse research treatment system serving an occupied four-bedroom, four bath university residence hall apartment. Organic concentrations were measured as chemical oxygen demand (COD) and kinetic runs were monitored at varying O3/H2O2 dosages and ratios. COD degradation could be accurately described as the parallel pseudo-1st order decay of rapidly and slowly-oxidizable fractions, and effluent COD was reduced to below the detection limit (water, and a relationship is proposed and demonstrated to estimate the pseudo-first order rate constant for design purposes. At this O3/H2O2 mass ratio, ORP and dissolved ozone were found to be useful process control indicators for monitoring COD mineralization in secondary effluent. Moreover, an average second order rate constant for OH oxidation of secondary effluent organics (measured as MCOD) was found to be 1.24 × 10(7) ± 0.64 × 10(7) M(-1) S(-1). The electric energy demand of the peroxone process is estimated at 1.73-2.49 kW h electric energy for removal of one log COD in 1 m(3) secondary effluent, comparable to the energy required for desalination of medium strength seawater. Advantages/disadvantages of the two processes for municipal wastewater reuse are discussed.

  5. Influence of Chemical Oxygen Demand Concentrations on Anaerobi Ammonium Oxidation by Granular Sludge From EGSB Reactor

    Institute of Scientific and Technical Information of China (English)

    JING KANG; JIAN-LONG WANG

    2006-01-01

    Objective To investigate the effect of chemical oxygen demand (COD) concentrations on the anaerobic ammonium oxidation (ANAMMOX). Methods An Expanded Granular Sludge Bed (EGSB) reactor was used to cultivate the granular sludge and to perform the ANAMMOX reaction in the bench scale experiment. NH4+-N and NO2--N were measured by usingcolorimetric method. NO3--N was analyzed by using the UV spectrophotometric method. COD measurement was based on digestion with potassium dichromate in concentrated sulphuric acid. Results When the COD concentrations in the reactors were 0 mg/L, 200 mg/L, 350 mg/L, and 550 mg/L, respectively, the NH4+-N removal efficiency was 12.5%, 14.2%, 14.3%, and 23.7%; the removal amount of NO2--N was almost the same; the nitrate removal efficiency was 16.8%, 94.5%, 86.6%, and 84.2% and TN removal efficiency was 16.3%, 50.7%, 46.9%, and 50.4%, moreover, the COD removal efficiency concentrations have a significant influence on anaerobic ammonium oxidation by granular sludge.

  6. A portable photoelectrochemical probe for rapid determination of chemical oxygen demand in wastewaters.

    Science.gov (United States)

    Zhang, Shanqing; Li, Lihong; Zhao, Huijun

    2009-10-15

    A photoelectrochemical probe for rapid determination of chemical oxygen demand (COD) is developed using a nanostructured mixed-phase TiO2 photoanode, namely PeCOD probe. A UV-LED light source and a USB mircroelectrochemical station are powered and controlled by a laptop computer, which makes the probe portable for onsite COD analyses. The photoelectrochemical measurement of COD was optimized in terms of light intensity, applied bias, and pH. Under the optimized conditions, the net steady state currents originated from the oxidation of organic compounds were found to be directly proportional to COD concentrations. A practical detection limit of 0.2 ppm COD and a linear range of 0-120 ppm COD were achieved. The analytical method using the portable PeCOD probe has the advantages of being rapid, low cost, robust, user-friendly, and environmental friendly. It has been successfully applied to determine the COD values of the synthetic samples consisting of potassium hydrogen phthalate, D-glucose, glutamic acid, glutaric acid, succinic acid, and malonic acid, and real samples from various industries, such as bakery, oil and grease manufacturer, poultry, hotel, fine food factory, and fresh food producer, commercial bread manufacturer. Excellent agreement between the proposed method and the conventional COD method (dichromate) was achieved.

  7. Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xixi; WANG Xiulin; SHI Xiaoyong; LI Keqiang; DING Dongsheng

    2011-01-01

    A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocated capacities of COD in the Bohai Sea are calculated. For seawater of Grades I to IV of the Chinese National Standard, the ECs of COD in the Bohai Sea were 77×104t/a, 116×l04t/a, 154×l04t/a and 193×104t/a, respectively. The Huanghe (Yellow) River pollutant discharge accounted for the largest percentage of COD at 14.3%, followed by that of from the Liugu River (11.5%), and other nine local rivers below 10%. The COD level in 2005 was worse than that of Grade II seawater and was beyond the environmental capacity. In average, 35% COD reduction is called to meet the standard of Grade I seawater.

  8. A Gibbs Energy Minimization Approach for Modeling of Chemical Reactions in a Basic Oxygen Furnace

    Science.gov (United States)

    Kruskopf, Ari; Visuri, Ville-Valtteri

    2017-08-01

    In modern steelmaking, the decarburization of hot metal is converted into steel primarily in converter processes, such as the basic oxygen furnace. The objective of this work was to develop a new mathematical model for top blown steel converter, which accounts for the complex reaction equilibria in the impact zone, also known as the hot spot, as well as the associated mass and heat transport. An in-house computer code of the model has been developed in Matlab. The main assumption of the model is that all reactions take place in a specified reaction zone. The mass transfer between the reaction volume, bulk slag, and metal determine the reaction rates for the species. The thermodynamic equilibrium is calculated using the partitioning of Gibbs energy (PGE) method. The activity model for the liquid metal is the unified interaction parameter model and for the liquid slag the modified quasichemical model (MQM). The MQM was validated by calculating iso-activity lines for the liquid slag components. The PGE method together with the MQM was validated by calculating liquidus lines for solid components. The results were compared with measurements from literature. The full chemical reaction model was validated by comparing the metal and slag compositions to measurements from industrial scale converter. The predictions were found to be in good agreement with the measured values. Furthermore, the accuracy of the model was found to compare favorably with the models proposed in the literature. The real-time capability of the proposed model was confirmed in test calculations.

  9. High Resolution Photoacoustic Spectroscopy of the Oxygen A-Band

    Science.gov (United States)

    Cich, Matthew J.; Lunny, Elizabeth M.; Stroscio, Gautam; Bui, Thinh Quoc; Bray, Caitlin; Hogan, Daniel; Rupasinghe, Priyanka; Crawford, Timothy J.; Drouin, Brian; Miller, Charles; Long, David A.; Hodges, Joseph T.; Okumura, Mitchio

    2016-06-01

    NASA's Orbiting Carbon Observatory missions require spectroscopic parameterization of the Oxygen A-Band absorption (757-775 nm) with unprecedented detail to meet the objective of delivering space-based column CO2 measurements with an accuracy of better than 1 ppm, and spectroscopic parameters with accuracies at the 0.1% level. To achieve this it is necessary for line shape models to include deviations from the Voigt line shape, including the collisional effects of speed-dependence, line mixing (LM), and collision-induced absorption (CIA). LM and CIA have been difficult to quantify in FTIR and CRDS spectra which have been limited to lower pressure measurements. A photoacoustic spectrometer has been designed to study the pressure- dependence of the spectral line shape up to pressures of 5 atm, where LM and CIA contribute significantly to the A-Band absorption. This spectrometer has a high signal-to-noise (S/N) of about 10,000 and frequency accuracy of 2 MHz. In addition, temperature-dependent effects on the line shape are studied using PID-controlled cooled nitrogen flow/ heater system. The latest acquired spectra and analysis are reported here.

  10. Highly Oxygenated Flavonoids from the Leaves of Nicotiana plumbaginifolia (Solanaceae

    Directory of Open Access Journals (Sweden)

    Md. Shafiullah Shajib

    2017-11-01

    Full Text Available Nicotiana plumbaginifolia Viv. is an annual herb of the family Solanaceae, which grows abundantly in the weedy lands of Bangladesh . This plant possesses analgesic, antibacterial, anti-anxiety and hepatoprotective properties, and produces various phenolic compounds including flavonoids. The present study afforded determination of total phenolic and flavonoid contents, and for the first time, the isolation and characterization of highly oxygenated flavonoids, e.g., 3,3' ,5,6,7,8-hexamethoxy- 4',5'-methylenedioxyflavone (1, 3,3' ,4' ,5',5,6,7,8-octamethoxyflavone (2, exoticin, 6,7,4',5'-dimethylenedioxy-3,5,3'-trimethoxyflavone (3 and ( 3,3' ,4',5,5',8-hexamethoxy-6,7-methylenedioxyflavone (4 from the leaves of N. plumbaginifolia . All these flavonoids are rather rare natural products, and only found in a few genera, e.g.,Polygonum and Murraya. The structures of the isolated flavonoids were elucidated by comprehensive spectroscopic analyses, e.g., UV, 1H, 13C NMR, DEPT, HSQC, HMBC and MS.

  11. Differential Diode Laser Sensor for High-Purity Oxygen Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A compact portable sensor for determining the purity of oxygen concentrations near 100 percent is proposed based on differential absorption of two beams from a diode...

  12. High Pressure Oxygen Generation for Future Exploration Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is the development of a cathode feed electrolysis cell stack capable of generating 3600 psia oxygen at a relevant scale for future...

  13. Anatomical adaptations for peripheral oxygen transport at high and ...

    African Journals Online (AJOL)

    1997-09-02

    Sep 2, 1997 ... vascular system, and hence delivery of oxygen and other ... lian myocardium or humming bird flight muscle, even though the va ... itative picture of microvascular anatomy has been available ...... mammalian respiratory system.

  14. Oxygen and SO2 consumption rates in white and rosé wines. Relationship with and effects on wine chemical composition.

    Science.gov (United States)

    Carrascón, Vanesa; Bueno, Mónica; Fernandez-Zurbano, Purificación; Ferreira, Vicente

    2017-10-02

    This paper addresses the study of O2 and SO2 consumption rates of white and rosé wines, their relationship to the initial chemical composition and their effects on the chemical changes experienced by wine during oxidation. Eight wines were subjected to five consecutive air-saturation cycles. O2 was monitored periodically; SO2, color and antioxidant indexes were determined after each cycle, and the initial and final composition of the wines were thoroughly determined. Wines consumed oxygen at progressively decreasing rates. In the last cycles, after a strong decrease, consistent increases of oxygen levels were seen. Oxygen consumption rates were satisfactorily modelled, being proportional to wine Copper, quercetin and kaempherol contents, and negatively proportional to cinnamic acids. SO2 consumption rates were highly diverse between wines and were positively related to free SO2, Mn and pH, among others. In the last saturations, SO2 consumption took place regardless O2 consumption, implying that SO2 should reduce chemical species oxidized in previous saturations. Some volatile phenols seem to be the endpoint of radical-mediated oxidation of polyphenols taking place preferably in the first saturation.

  15. High energy lithium-oxygen batteries - Transport barriers and thermodynamics

    KAUST Repository

    Das, Shyamal K.

    2012-01-01

    We show that it is possible to achieve higher energy density lithium-oxygen batteries by simultaneously lowering the discharge overpotential and increasing the discharge capacity via thermodynamic variables alone. By assessing the relative effects of temperature and pressure on the cell discharge profiles, we characterize and diagnose the critical roles played by multiple dynamic processes that have hindered implementation of the lithium-oxygen battery. © 2012 The Royal Society of Chemistry.

  16. Intrinsic and metal-doped gallium oxide based high-temperature oxygen sensors for combustion processes

    Science.gov (United States)

    Rubio, Ernesto Javier

    Currently, there is enormous interest in research, development and optimization of the combustion processes for energy harvesting. Recent statistical and economic analyses estimated that by improving the coal-based firing/combustion processes in the power plants, savings up to $450-500 million yearly can be achieved. Advanced sensors and controls capable of withstanding extreme environments such as high temperatures, highly corrosive atmospheres, and high pressures are critical to such efficiency enhancement and cost savings. For instance, optimization of the combustion processes in power generation systems can be achieved by sensing, monitoring and control of oxygen, which is a measure of the completeness of the process and can lead to enhanced efficiency and reduced greenhouse gas emissions. However, despite the fact that there exists a very high demand for advanced sensors, the existing technologies suffer from poor 'response and recovery times' and 'long-term stability.' Motivated by the aforementioned technological challenges, the present work was focused on high-temperature (≥700 °C) oxygen sensors for application in power generation systems. The objective of the present work is to investigate nanostructured gallium oxide (2O3) based sensors for oxygen sensing, where we propose to conduct in-depth exploration of the role of refractory metal (tungsten, W, in this case) doping into 2O 3 to enhance the sensitivity, selectivity, stability ("3S" criteria) and reliability of such sensors while keeping cost economical. Tungsten (W) doped gallium oxide (2O3) thin films were deposited via rf-magnetron co-sputtering of W-metal and Ga2O3-ceramic targets. Films were produced by varying the sputtering power applied to the W-target in order to achieve variable W content into 2O3 films while substrate temperature was kept constant at 500 °C. Chemical composition, chemical valence states, microstructure and crystal structure of as-grown and post-annealed W-doped 2O3

  17. Chemical Analysis of a "Miller-Type" Complex Prebiotic Broth: Part I: Chemical Diversity, Oxygen and Nitrogen Based Polymers.

    Science.gov (United States)

    Wollrab, Eva; Scherer, Sabrina; Aubriet, Frédéric; Carré, Vincent; Carlomagno, Teresa; Codutti, Luca; Ott, Albrecht

    2016-06-01

    In a famous experiment Stanley Miller showed that a large number of organic substances can emerge from sparking a mixture of methane, ammonia and hydrogen in the presence of water (Miller, Science 117:528-529, 1953). Among these substances Miller identified different amino acids, and he concluded that prebiotic events may well have produced many of Life's molecular building blocks. There have been many variants of the original experiment since, including different gas mixtures (Miller, J Am Chem Soc 77:2351-2361, 1955; Oró Nature 197:862-867, 1963; Schlesinger and Miller, J Mol Evol 19:376-382, 1983; Miyakawa et al., Proc Natl Acad Sci 99:14,628-14,631, 2002). Recently some of Miller's remaining original samples were analyzed with modern equipment (Johnson et al. Science 322:404-404, 2008; Parker et al. Proc Natl Acad Sci 108:5526-5531, 2011) and a total of 23 racemic amino acids were identified. To give an overview of the chemical variety of a possible prebiotic broth, here we analyze a "Miller type" experiment using state of the art mass spectrometry and NMR spectroscopy. We identify substances of a wide range of saturation, which can be hydrophilic, hydrophobic or amphiphilic in nature. Often the molecules contain heteroatoms, with amines and amides being prominent classes of molecule. In some samples we detect ethylene glycol based polymers. Their formation in water requires the presence of a catalyst. Contrary to expectations, we cannot identify any preferred reaction product. The capacity to spontaneously produce this extremely high degree of molecular variety in a very simple experiment is a remarkable feature of organic chemistry and possibly prerequisite for Life to emerge. It remains a future task to uncover how dedicated, organized chemical reaction pathways may have arisen from this degree of complexity.

  18. Chemical Analysis of a "Miller-Type" Complex Prebiotic Broth. Part I: Chemical Diversity, Oxygen and Nitrogen Based Polymers

    Science.gov (United States)

    Wollrab, Eva; Scherer, Sabrina; Aubriet, Frédéric; Carré, Vincent; Carlomagno, Teresa; Codutti, Luca; Ott, Albrecht

    2016-06-01

    In a famous experiment Stanley Miller showed that a large number of organic substances can emerge from sparking a mixture of methane, ammonia and hydrogen in the presence of water (Miller, Science 117:528-529, 1953). Among these substances Miller identified different amino acids, and he concluded that prebiotic events may well have produced many of Life's molecular building blocks. There have been many variants of the original experiment since, including different gas mixtures (Miller, J Am Chem Soc 77:2351-2361, 1955; Oró Nature 197:862-867, 1963; Schlesinger and Miller, J Mol Evol 19:376-382, 1983; Miyakawa et al., Proc Natl Acad Sci 99:14,628-14,631, 2002). Recently some of Miller's remaining original samples were analyzed with modern equipment (Johnson et al. Science 322:404-404, 2008; Parker et al. Proc Natl Acad Sci 108:5526-5531, 2011) and a total of 23 racemic amino acids were identified. To give an overview of the chemical variety of a possible prebiotic broth, here we analyze a "Miller type" experiment using state of the art mass spectrometry and NMR spectroscopy. We identify substances of a wide range of saturation, which can be hydrophilic, hydrophobic or amphiphilic in nature. Often the molecules contain heteroatoms, with amines and amides being prominent classes of molecule. In some samples we detect ethylene glycol based polymers. Their formation in water requires the presence of a catalyst. Contrary to expectations, we cannot identify any preferred reaction product. The capacity to spontaneously produce this extremely high degree of molecular variety in a very simple experiment is a remarkable feature of organic chemistry and possibly prerequisite for Life to emerge. It remains a future task to uncover how dedicated, organized chemical reaction pathways may have arisen from this degree of complexity.

  19. Role of oxygen and nitrogen in n-type microcrystalline silicon carbide grown by hot wire chemical vapor deposition

    Science.gov (United States)

    Pomaska, Manuel; Mock, Jan; Köhler, Florian; Zastrow, Uwe; Perani, Martina; Astakhov, Oleksandr; Cavalcoli, Daniela; Carius, Reinhard; Finger, Friedhelm; Ding, Kaining

    2016-12-01

    N-type microcrystalline silicon carbide (μc-SiC:H(n)) deposited by hot wire chemical vapor deposition provides advantageous opto-electronic properties for window layer material in silicon-based thin-film solar cells and silicon heterojunction solar cells. So far, it is known that the dark conductivity (σd) increases with the increase in the crystallinity of μc-SiC:H(n)films. However, due to the fact that no active doping source is used, the mechanism of electrical transport in these films is still under debate. It is suggested that unintentional doping by atmospheric oxygen (O) or nitrogen (N) contamination plays an important role in the electrical transport. To investigate the impact of O and N, we incorporated O and N in μc-SiC:H(n) films and compared the influence on the microstructural, electronic, and optical properties. We discovered that, in addition to increasing the crystallinity, it is also possible to increase the σd by several orders of magnitude by increasing the O-concentration or the N-concentration in the films. Combining a high concentration of O and N, along with a high crystallinity in the film, we optimized the σd to a maximum of 5 S/cm.

  20. Sulfur evolution in chemical looping combustion of coal with MnFe2O4 oxygen carrier.

    Science.gov (United States)

    Wang, Baowen; Gao, Chuchang; Wang, Weishu; Zhao, Haibo; Zheng, Chuguang

    2014-05-01

    Chemical looping combustion (CLC) of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi (LZ) bituminous coal, was performed in a thermogravimetric analyzer (TGA)-Fourier transform infrared (FT-IR) spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFe2O4 OC was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn3O4 or Fe2O3, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe3O4 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.

  1. Generation of High Pressure Oxygen via Electrochemical Pumping in a Multi-stage Electrolysis Stack

    Science.gov (United States)

    Setlock, John A (Inventor); Green, Robert D (Inventor); Farmer, Serene (Inventor)

    2016-01-01

    An oxygen pump can produce high-purity high-pressure oxygen. Oxygen ions (O.sup.2-) are electrochemically pumped through a multi-stage electrolysis stack of cells. Each cell includes an oxygen-ion conducting solid-state electrolyte between cathode and anode sides. Oxygen dissociates into the ions at the cathode side. The ions migrate across the electrolyte and recombine at the anode side. An insulator is between adjacent cells to electrically isolate each individual cell. Each cell receives a similar volt potential. Recombined oxygen from a previous stage can diffuse through the insulator to reach the cathode side of the next stage. Each successive stage similarly incrementally pressurizes the oxygen to produce a final elevated pressure.

  2. A mixed ionic and electronic conducting dual-phase membrane with high oxygen permeability.

    Science.gov (United States)

    Fang, Wei; Liang, Fangyi; Cao, Zhengwen; Steinbach, Frank; Feldhoff, Armin

    2015-04-13

    To combine good chemical stability and high oxygen permeability, a mixed ionic-electronic conducting (MIEC) 75 wt% Ce(0.85)Gd(0.1)Cu(0.05)O(2-δ)-25 wt% La(0.6)Ca(0.4)FeO(3-δ)(CGCO-LCF) dual-phase membrane based on a MIEC-MIEC composite has been developed. Copper doping into Ce(0.9)Gd(0.1)O(2-δ) (CGO) oxide enhances both ionic and electronic conductivity, which then leads to a change from ionic conduction to mixed conduction at elevated temperatures. For the first time we demonstrate that an intergranular film with 2-10 nm thickness containing Ce, Ca, Gd, La, and Fe has been formed between the CGCO grains in the CGCO-LCF one-pot dual-phase membrane. A high oxygen permeation flux of 0.70 mL min(-1) cm(-2) is obtained by the CGCO-LCF one-pot dual-phase membrane with 0.5 mm thickness at 950 °C using pure CO2 as the sweep gas, and the membrane shows excellent stability in the presence of CO2 even at lower temperatures (800 °C) during long-term operation.

  3. The Hazards of Reactive Chemicals in High School Laboratories.

    Science.gov (United States)

    Forlin, Peter

    Chemical reactivity is a major area of risk in high school laboratories. This paper reports on a study that has provided a research-based framework for risk management in Australian chemical education. The chemical practice model of risk management is considered with respect to kinetic factors; catalysts; concentrations and proportions;…

  4. Micro-texturing into DLC/diamond coated molds and dies via high density oxygen plasma etching

    Directory of Open Access Journals (Sweden)

    Yunata Ersyzario Edo

    2015-01-01

    Full Text Available Diamond-Like Carbon (DLC and Chemical Vapor Deposition (CVD-diamond films have been widely utilized not only as a hard protective coating for molds and dies but also as a functional substrate for bio-MEMS/NEMS. Micro-texturing into these hard coated molds and dies provides a productive tool to duplicate the original mother micro-patterns onto various work materials and to construct any tailored micro-textures for sensors and actuators. In the present paper, the high density oxygen plasma etching method is utilized to make micro-line and micro-groove patterns onto the DLC and diamond coatings. Our developing oxygen plasma etching system is introduced together with characterization on the plasma state during etching. In this quantitative plasma diagnosis, both the population of activated species and the electron and ion densities are identified through the emissive light spectroscopy and the Langmuir probe method. In addition, the on-line monitoring of the plasmas helps to describe the etching process. DLC coated WC (Co specimen is first employed to describe the etching mechanism by the present method. Chemical Vapor Deposition (CVD diamond coated WC (Co is also employed to demonstrate the reliable capacity of the present high density oxygen plasma etching. This oxygen plasma etching performance is discussed by comparison of the etching rates.

  5. Performance of on-site pilot static granular bed reactor (SGBR) for treating dairy processing wastewater and chemical oxygen demand balance modeling under different operational conditions.

    Science.gov (United States)

    Oh, Jin Hwan; Park, Jaeyoung; Ellis, Timothy G

    2015-02-01

    The performance and operational stability of a pilot-scale static granular bed reactor (SGBR) for the treatment of dairy processing wastewater were investigated under a wide range of organic and hydraulic loading rates and temperature conditions. The SGBR achieved average chemical oxygen demand (COD), biological oxygen demand (BOD), and total suspended solids (TSS)-removal efficiencies higher than 90% even at high loading rates up to 7.3 kg COD/m(3)/day, with an hydraulic retention time (HRT) of 9 h, and at low temperatures of 11 °C. The average methane yield of 0.26 L CH4/g COD(removed) was possibly affected by a high fraction of particulate COD and operation at low temperatures. The COD mass balance indicated that soluble COD was responsible for most of the methane production. The reactor showed the capacity of the methanogens to maintain their activity and withstand organic and hydraulic shock loads.

  6. Oxygenated Organic Chemicals in the Pacific Troposphere: Distribution, Sources and Chemistry

    Science.gov (United States)

    Singh, Hanwant B.; Salas, L.; Chatfield, R.; Czech, E.; Fried, A.; Evans, M.; Jacob, D. J.; Blake, D.; Heikes, B.; Talbot, R.

    2003-01-01

    Airborne measurements of a large number of oxygenated organic chemicals (Oxorgs) were carried out in the Pacific troposphere (0.1-12 km) in the Spring of 2001 (Feb. 24-April 10). Specifically these measuremen ts included acetone, methylethyl ketone (MEK), methanol, ethanol, ace taldehyde, propionaldehyde, PANS, and organic nitrates. Complementary measurements of formaldehyde, organic peroxides, and tracers were al so available. Ox-orgs were abundant in the clean troposphere and were greatly enhanced in the outflow regions from Asia. Their mixing ratios were typically highest in the lower troposphere and declined toward s the upper troposphere and the lowermost stratosphere. Their total a bundance (Ox-orgs) significantly exceeded that of NMHC (C2-C8 NMHC). A comparison of these data with observations collected some seven yea rs earlier (Feb.-March, 1994), did not reveal any significant changes . Throughout the troposphere mixing ratios of Ox-orgs were strongly c orrelated with each other as well as with tracers of fossil and bioma sshiof'uel combustion. Analysis of the relative enhancement of selected Oxorgs with respect to CH3Cl and CO in twelve sampled plumes, origi nating from fires, is used to assess their primary and secondary sour ces from biomass combustion. The composition of these plumes also ind icates a large shift of reactive nitrogen into the PAN reservoir ther eby limiting ozone formation. The Harvard 3-D photochemical model, th at uses state of the art chemistry and source information, is used to compare simulated and observed mixing ratios of selected species. A 1 -D model is used to explore the chemistry of aldehydes. These results will be presented.

  7. Experimental study on ignition characteristics of pulverized coal under high-temperature oxygen condition

    Science.gov (United States)

    Liu, G. W.; Liu, Y. H.; Dong, P.

    2016-08-01

    The high-temperature oxygen ignition technology of pulverized coal, which can replace the oil gun and achieve oil-free pulverized coal ignition by mixing the high- temperature oxygen and the pulverized coal stream directly, was proposed and a relevant ignition experimental system was built. The ignition characteristics of pulverized coal under high-temperature oxygen condition were investigated: the ignition process was described and analyzed, the influence of relevant parameters on the pulverized coal stream ignition were obtained and analyzed. The results showed: when the oxygen heating temperature is over 750 °C, the pulverized coal stream could be ignited successfully by high-temperature oxygen; increasing the pulverized coal concentration, primary air temperature and oxygen volume flow rate or decreasing the primary air velocity is helpful for the ignition and combustion of the pulverized coal stream.

  8. Nonintrusive fast response oxygen monitoring system for high temperature flows

    Science.gov (United States)

    Oh, Daniel B.; Stanton, Alan C.

    1993-01-01

    A new technique has been developed for nonintrusive in situ measurement of oxygen concentration, gas temperature, and flow velocity of the test media in hypersonic wind tunnels. It is based on absorption of near-infrared radiation from inexpensive GaAlAs laser diodes used in optoelectronics industry. It is designed for simultaneous measurements along multiple lines of sight accessed by fiber optics. Molecular oxygen concentration is measured from the magnitude of absorption signals; rotational gas temperature is measured from the intensity ratio of two oxygen absorption lines; and the flow velocity is measured from the Doppler shift of the absorption line positions. This report describes the results of an extensive series of tests of the prototype instrument in laboratory flames emphasizing assessment of the instruments capabilities for quantitative measurement of O2 concentration (mole fraction) and gas temperature.

  9. Supplemental Perioperative Oxygen to Reduce Surgical Site Infection After High-Energy Fracture Surgery (OXYGEN Study).

    Science.gov (United States)

    OʼToole, Robert V; Joshi, Manjari; Carlini, Anthony R; Sikorski, Robert A; Dagal, Armagan; Murray, Clinton K; Weaver, Michael J; Paryavi, Ebrahim; Stall, Alec C; Scharfstein, Daniel O; Agel, Julie; Zadnik, Mary; Bosse, Michael J; Castillo, Renan C

    2017-04-01

    Supplemental perioperative oxygen (SPO) therapy has been proposed as one approach for reducing the risk of surgical site infection (SSI). Current data are mixed regarding efficacy in decreasing SSI rates and hospital inpatient stays in general and few data exist for orthopaedic trauma patients. This study is a phase III, double-blind, prospective randomized clinical trial with a primary goal of assessing the efficacy of 2 different concentrations of perioperative oxygen in the prevention of SSIs in adults with tibial plateau, pilon (tibial plafond), or calcaneus fractures at higher risk of infection and definitively treated with plate and screw fixation. Patients are block randomized (within center) in a 1:1 ratio to either treatment group (FiO2 80%) or control group (FiO2 30%) and stratified by each study injury location. Secondary objectives of the study are to compare species and antibacterial sensitivities of the bacteria in patients who develop SSIs, to validate a previously developed risk prediction model for the development of SSI after fracture surgery, and to measure and compare resource utilization and cost associated with SSI in the 2 study groups. SPO is a low cost and readily available resource that could be easily disseminated to trauma centers across the country and the world if proved to be effective.

  10. Raman spectra investigation of the defects of chemical vapor deposited multilayer graphene and modified by oxygen plasma treatment

    Science.gov (United States)

    Li, Zongyao; Xu, Yu; Cao, Bing; Qi, Lin; He, Shunyu; Wang, Chinhua; Zhang, Jicai; Wang, Jianfeng; Xu, Ke

    2016-11-01

    Graphene, a two dimensional material, can be modified its properties by defects engineering. Here, we present Raman spectra studies of the multilayer graphene (MLG) fabricated by low-pressure chemical vapor deposition over copper foil, and report that the defects of MLG can be controlled by adjusting methane concentration. Moreover, MLG can be changed from metallic to semiconductoring properties by using oxygen plasma treatment, and we investigate the defects evolution of the graphene after exposing to oxygen plasma by Raman spectra. Our results indicate that the amount of defects in graphene can be changed by regulating the methane concentration and oxygen plasma exposure times, but the primary type of defect in MLG is still boundary-like defect. It is valuable for understanding the physics of defects evolution through artificially generated defects, and such defect engineering will greatly open up the future application of the novel material.

  11. Active packaged lamb with oxygen scavenger/carbon dioxide emitter sachet: physical-chemical and microbiological stability during refrigerated storage

    Directory of Open Access Journals (Sweden)

    Marco Antonio Trindade

    2013-09-01

    Full Text Available Lamb meat has been commercialized in Brazil almost exclusively as a frozen product due to the longer shelf life provided by freezing when compared to refrigeration. However, as a result of the current trend of increased demand for convenience products, a need has emerged for further studies to facilitate the marketing of refrigerated lamb cuts. The aim of the present study was to evaluate the contribution of active packaging technology in extending the shelf life of lamb loins (Longissimus lumborum stored under refrigeration (1±1 ° C when compared to the traditional vacuum packaging. For this purpose, two kinds of sachets were employed: oxygen scavenger sachet and oxygen scavenger/carbon dioxide emitter sachet. Experiments were conducted in three treatments: 1 Vacuum (Control, 2 Vacuum + oxygen scavenger sachet and 3 Vacuum + oxygen scavenger/carbon dioxide emitter sachet. Microbiological (counts of anaerobic psychrotrophs, coliform at 45 ° C, coagulase-positive staphylococci, Salmonella and lactic acid bacteria and physical-chemical (thiobarbituric acid reactive substances, objective color, pH value, water loss from cooking and shear force analyses were carried out weekly for a total storage period of 28 days. The experiment was performed three times for all treatments. Results showed that the lamb meat remained stable with respect to the majority of the evaluated physical and chemical indexes and remained within the standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period in all three packaging systems. However, all treatments presented elevated counts of anaerobic psychrotrophic microorganisms and lactic acid bacteria, reaching values above 10(7 CFU/g at 28 days of storage. Thus, under the conditions tested, neither the oxygen scavenger sachet nor the dual function sachet (oxygen scavenger/carbon dioxide emitter were able to extend the shelf life of refrigerated lamb loin when added to this

  12. Development of Test Unit for Production of Oxygen by a Regenerative Chemical

    Science.gov (United States)

    1945-05-31

    inspect the unit so it was decided to cancel the plans for building the two more casos . Dec. 19W - Feb. 19»5 On December 26, 194*, I reached the Ü. S...again, another crude experiment, was carried out to determine how the humidity of the oxygen which was produced compared with cylinder oxygen. The

  13. Acetazolamide improves cerebral oxygenation during exercise at high altitude

    NARCIS (Netherlands)

    Vuyk, J.; Bos, J. van den; Terhell, K.; Bos, R. de; Vletter, A.; Valk, P.; Beuzekom, M. van; Kleef, J. van; Dahan, A.

    2006-01-01

    Acute mountain sickness is thought to be triggered by cerebral hypoxemia and be prevented by acetazolamide (Actz). The effect of Actz on cerebral oxygenation at altitude remains unknown. In 16 members of the 2005 Dutch Cho Oyu (8201 m, Tibet) expedition, the influence of Actz and exercise (750 mg PO

  14. High-temperature potentiometric oxygen sensor with internal reference

    Energy Technology Data Exchange (ETDEWEB)

    Routbort, Jules L. (Hinsdale, IL); Singh, Dileep (Naperville, IL); Dutta, Prabir K. (Worthington, OH); Ramasamy, Ramamoorthy (North Royalton, OH); Spirig, John V. (Columbus, OH); Akbar, Sheikh (Hilliard, OH)

    2011-11-15

    A compact oxygen sensor is provided, comprising a mixture of metal and metal oxide an enclosure containing said mixture, said enclosure capable of isolating said mixture from an environment external of said enclosure, and a first wire having a first end residing within the enclosure and having a second end exposed to the environment. Also provided is a method for the fabrication of an oxygen sensor, the method comprising confining a metal-metal oxide solid mixture to a container which consists of a single material permeable to oxygen ions, supplying an electrical conductor having a first end and a second end, whereby the first end resides inside the container as a reference (PO.sub.2).sup.ref, and the second end resides outside the container in the atmosphere where oxygen partial pressure (PO.sub.2).sup.ext is to be measured, and sealing the container with additional single material such that grain boundary sliding occurs between grains of the single material and grains of the additional single material.

  15. Bismuth-lead oxide, a new highly conductive oxygen materials

    NARCIS (Netherlands)

    Honnart, F.; Boivin, J.C.; Thomas, D.; Vries, de K.J.

    1983-01-01

    The transport properties of an oxygen-deficient solid solution containing lead and bismuth oxides have been investigated. The conductivity is larger than 1 (ω× cm)−1 at 600 °C. Thermogalvanic measurements confirm that no significant electronic contribution occurs in the range 1–10−3atm p O2. The hea

  16. A quantum-chemical study of oxygen-vacancy defects in PbTiO{sub 3} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Stashans, Arvids [Laboratorio de Fisica, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)]. E-mail: arvids@utpl.edu.ec; Serrano, Sheyla [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador); Escuela de Ingenierias, Universidad Politecnica Salesiana, Campus Sur, Rumichaca s/n y Moran Valverde, Apartado 17-12-536, Quito (Ecuador); Medina, Paul [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador)

    2006-05-31

    Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO{sub 3} crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results.

  17. Spectroscopic Determination of Trace Contaminants in High-Purity Oxygen

    Science.gov (United States)

    Hornung, Steven

    2013-01-01

    Oxygen used for extravehicular activities (EVAs) must be free of contaminants because a difference in a few tenths of a percent of argon or nitrogen content can mean significant reduction in available EVA time. These inert gases build up in the extravehicular mobility unit because they are not metabolized or scrubbed from the atmosphere. A prototype optical emission technique capable of detecting argon and nitrogen below 0.1% in oxygen has been developed. This instrument uses a glow discharge in reduced-pressure gas to produce atomic emission from the species present. Because the atomic emission lines from oxygen, nitrogen, and argon are discrete, and in many cases well-separated, trace amounts of argon and nitrogen can be detected in the ultraviolet and visible spectrum. This is a straightforward, direct measurement of the target contaminants, and may lend itself to a device capable of on-orbit verification of oxygen purity. A glow discharge is a plasma formed in a low-pressure (1 to 10 Torr) gas cell between two electrodes. Depending on the configuration, voltages ranging from 200 V and above are required to sustain the discharge. In the discharge region, the gas is ionized and a certain population is in the excited state. Light is produced by the transitions from the excited states formed in the plasma to the ground state. The spectrum consists of discrete, narrow emission lines for the atomic species, and broader peaks that may appear as a manifold for molecular species such as O2 and N2, the wavelengths and intensities of which are a characteristic of each atom. The oxygen emission is dominated by two peaks at 777 and 844 nm.

  18. Zn/O ratio and oxygen chemical state of nanocrystalline ZnO films grown at different temperatures

    Institute of Scientific and Technical Information of China (English)

    Fan Hai-Bo; Zheng Xin-Liang; Wu Si-Cheng; Liu Zhi-Gang; Yao He-Bao

    2012-01-01

    ZnO nanocrystalline films are prepared on Si substrates at different temperatures by using metal-organic chemical vapour deposition (MOCVD).It is observed that when the growth temperature is low,the stoichiometric ratio between Zn and O atoms has a large deviation from the ideal ratio of 1:1.The ZnO grains in the film have small sizes and are not well crystallized,resulting in a poor photoluminescence (PL) property.When the temperature is increased to an appropriate value,the Zn/O ratio becomes optimized,and most of Zn and O atoms are combined into Zn-O bonds.Then the film has good crystal quality and good PL property.If the temperature is fairly high,the interfacial mutual diffusion of atoms between the substrate and the epitaxial film appears,and the desorption process of the oxygen atoms is enhanced.However,it has no effect on the film property.The film still has the best crystal quality and PL property.

  19. A miniature photoelectrochemical sensor based on organic electrochemical transistor for sensitive determination of chemical oxygen demand in wastewaters.

    Science.gov (United States)

    Liao, Jianjun; Lin, Shiwei; Zeng, Min; Yang, Yue

    2016-05-01

    A three-electrode configuration is often required in the conventional photoelectrochemical measurements. Nevertheless, one common drawback is the reference electrode and the counter electrode used in the measurements, which has been proved to be an impediment for the miniaturization. In this study, a simple, cost-effective and miniature photoelectrochemical sensor based on high sensitive organic electrochemical transistor (OECT) is developed and used for the determination of chemical oxygen demand (COD) in wastewaters. The devices show detection limit down to 0.01 mg/L COD, which is two orders of magnitude better than that of the conventional photoelectrochemical method. The excellent sensing performance can be contributed to the novel sensing mechanism of OECT devices. That is, the devices are sensitive to the potential changes induced by the photoelectrochemical reaction on TiO2 nanotube arrays gate electrodes. Real sample analyses are also carried out. The results demonstrate that the measured COD values using the OECT devices and the standard dichromate methods are in a good agreement. Since the proposed sensor is constructed on a miniature transistor, it is expected that the device shows a promising application on the integrated COD monitoring platform.

  20. Discovery of Outlying, High-Velocity Oxygen-Rich Ejecta in Cassiopeia A

    CERN Document Server

    Fesen, R A; Morse, J; Chevalier, R A; Borkowski, K J; Dopita, M A; Gerardy, C L; Lawrence, S S; Raymond, J C; Van den Bergh, S

    2006-01-01

    Hubble Space Telescope images of the young Galactic supernova remnant Cassiopeia A reveal a far larger population of outlying, high-velocity knots of ejecta with a broader range of chemical properties than previously suspected. We identify three main classes of outer ejecta: 1) Knots dominated by [N II] 6548,6583 emission; 2) Knots dominated by oxygen emission lines especially [O II] 7319,7330; and 3) Knots with emission line strengths similar to the [S II] strong FMK ejecta commonly seen in the main emission shell. The discovery of a significant population of O-rich ejecta situated in between the suspected N-rich outer photospheric layer and S-rich FMK-like ejecta suggests that the Cas A progenitor's chemical layers were not completely disrupted by the supernova explosion outside of the remnant's NE and SW high velocity `jet' regions. In addition, we find the majority of O-rich outer ejecta at projected locations out beyond (v = 6500 - 9000 km/s) the remnant's fastest moving Fe-rich X-ray emission material (...

  1. Oxygen Fugacity at High Pressure: Equations of State of Metal-Oxide Pairs

    Science.gov (United States)

    Campbell A. J.; Danielson, L.; Righter, K.; Wang, Y.; Davidson, G.; Wang, Y.

    2006-01-01

    Oxygen fugacity (fO2) varies by orders of magnitude in nature, and can induce profound changes in the chemical state of a substance, and also in the chemical equilibrium of multicomponent systems. One prominent area in high pressure geochemistry, in which fO2 is widely recognized as a principal controlling factor, is that of metal-silicate partitioning of siderophile trace elements (e.g., [1]). Numerous experiments have shown that high pressures and temperatures can significantly affect metal/silicate partitioning of siderophile and moderately siderophile elements. Parameterization of these experimental results over P, T, X, and fO2 can allow the observed siderophile element composition of the mantle to be associated with particular thermodynamic conditions [2]. However, this is best done only if quantitative control exists over each thermodynamic variable relevant to the experiments. The fO2 values for many of these partitioning experiments were determined relative to a particular metal-oxide buffer (e.g., Fe-FeO (IW), Ni-NiO (NNO), Co-CoO, Re-ReO2 (RRO)), but the parameterization of all experimental results is weakened by the fact that the pressure-induced relative changes between these buffer systems are imprecisely known.

  2. High-resolution signatures of oxygenation and microbiological activity in speleothem fluid inclusions

    Directory of Open Access Journals (Sweden)

    Nigel J.F. Blamey

    2016-09-01

    Full Text Available Speleothems frequently host “fossil” fluids that were trapped in small inclusions during growth. Such fluids may provide valuable clues to past microbial, geochemical, and climatic processes during their formation. However, one difficulty is to understand which gases represent background atmosphere and fluids within a given cave system at a particular time, and which may be the product of post-trapping residual microbial activity or abiotic chemical reactions? Do we have any hope of sorting out these differences? The success depends on a quantitative understanding of the gas composition trapped in the inclusions and an understanding of the interactions of cave mineralogy, air and water chemistry, and microbiological processes that may interfere with climatic or geochemical interpretations. Our proof-of-concept project uses time synchronous samples from several sites. We report here on this pilot investigation of speleothem inclusions using a methodology for quantitatively analyzing gases dissolved in inclusion fluids. We use incremental crushing of highly spatially resolved samples by mass spectrometry. Here, we report primarily on CH4, CO2, O2, and N2, but have included other detectable gases. The detection limit for He within aqueous fluid inclusions is ~0.2 ppm and gas ratios have ~5% precision using natural standards. We used chemically inert argon as a tracer gas to normalize results to air or air saturated water. This enables interpretation of gas data despite variability in hydrological and geological cave histories. Results are variable. For example, in one case oxygen was depleted while nitrogen was increased, which may be attributable to the breakdown of nitrate or nitrogen-containing biomolecules. In other cases, oxygen is enriched which may be attributed to several factors both geochemical and biological. We suggest potential interpretations between the competing hypotheses with larger future data sets. This first attempt tackles

  3. Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties

    Directory of Open Access Journals (Sweden)

    Ilke Uysal Unalan

    2016-12-01

    Full Text Available In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate (PET with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO were used as main polymer phase and nanobuilding block (NBB, respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ and as a function of different relative humidity (RH values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m−2·24 h−1 value below the detection limit of the instrument (0.01 mL·m−2·24 h−1 was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films. Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03. The mechanisms underlying the experimental observations are discussed.

  4. Feasibility study of sulfates as oxygen carriers for chemical looping processes

    Directory of Open Access Journals (Sweden)

    Ganesh Kale

    2012-12-01

    Full Text Available The operational feasibility temperature range of chemical looping combustion (CLC and chemical looping reforming (CLR of the fuels methane, propane, iso-octane and ethanol was explored using the common sulphates

  5. New oxygen radical source using selective sputtering of oxygen atoms for high rate deposition of TiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Yoji; Lei, Hao; Hoshi, Yoichi [Department of Electronics and Information Technology, Tokyo Polytechnic University, Kanagawa 243-0297 (Japan); State Key Laboratory for Corrosion and Protection, Surface Engineering of Materials Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Department of Electronics and Information Technology, Tokyo Polytechnic University, Kanagawa 243-0297 (Japan)

    2012-11-15

    We have developed a new oxygen radical source based on the reactive sputtering phenomena of a titanium target for high rate deposition of TiO{sub 2} films. In this oxygen radical source, oxygen radicals are mainly produced by two mechanisms: selective sputter-emission of oxygen atoms from the target surface covered with a titanium oxide layer, and production of high-density oxygen plasma in the space near the magnetron-sputtering cathode. Compared with molecular oxygen ions, the amount of atomic oxygen radicals increased significantly with an increase in discharge current so that atomic oxygen radicals were mainly produced by this radical source. It should be noted that oxygen atoms were selectively sputtered from the target surface, and titanium atoms sputter-emitted from the target cathode were negligibly small. The amount of oxygen radicals supplied from this radical source increased linearly with increasing discharge current, and oxygen radicals of 1 Multiplication-Sign 10{sup 15} atoms/s/cm{sup 2} were supplied to the substrate surface at a discharge current of 1.2 A. We conclude that our newly developed oxygen radical source can be a good tool to achieve high rate deposition and to control the structure of TiO{sub 2} films for many industrial design applications.

  6. Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process

    CERN Document Server

    Ferraro, F R; Gratton, R; Piotto, G; Lanzoni, B; Carretta, E; Rood, R T; Sills, A; Pecci, F F; Möhler, S; Beccari, G; Lucatello, S; Compagni, N

    2006-01-01

    We use high-resolution spectra obtained with the ESO Very Large Telescope to measure surface abundance patterns of 43 Blue Stragglers stars (BSS) in 47 Tuc. We discovered that a sub-population of BSS shows a significant depletion of Carbon and Oxygen with respect to the dominant population. This evidence would suggest the presence of CNO burning products on the BSS surface coming from a deeply peeled parent star, as expected in the case of mass-transfer process. This is the first detection of a chemical signature clearly pointing to a specific BSS formation process in a globular cluster.

  7. Catalytic layer for oxygen activation on ionic solid electrolytes at high temperature

    OpenAIRE

    Serra Alfaro, José Manuel; Vert Belenguer, Vicente Bernard; Escolástico Rozalén, Sonia

    2008-01-01

    The present invention relates to a catalytic porous layer for oxygen activation which may be utilised in solid oxide fuel cells (SOFCs) and in dense ceramic membranes for oxygen separation at high temperature. Said porous layer is principally formed by a mixed electron and oxygen ion conductive material possessing a structure selected from among structures of the simple perovskite or double perovskite type or structures related to perovskite, that is to say: structures of the Ruddlesden-Poppe...

  8. Increased long-term mortality after a high perioperative inspiratory oxygen fraction during abdominal surgery

    DEFF Research Database (Denmark)

    Meyhoff, Christian Sylvest; Jorgensen, Lars N; Wetterslev, Jørn;

    2012-01-01

    A high perioperative inspiratory oxygen fraction (80%) has been recommended to prevent postoperative wound infections. However, the most recent and one of the largest trials, the PROXI trial, found no reduction in surgical site infection, and 30-day mortality was higher in patients given 80% oxygen....... In this follow-up study of the PROXI trial we assessed the association between long-term mortality and perioperative oxygen fraction in patients undergoing abdominal surgery....

  9. Selection for high and low oxygen consumption-induced differences in maintenance energy requirements of mice.

    Science.gov (United States)

    Darhan, Hongyu; Kikusato, Motoi; Toyomizu, Masaaki; Roh, Sang-Gun; Katoh, Kazuo; Sato, Masahiro; Suzuki, Keiichi

    2017-07-01

    Maintenance energy requirements (MER) of mice selected for high (H) or low (L) oxygen consumption (OC) were compared. Forty-four mice from H and L OC lines were weaned at 3 weeks and divided into four experimental groups: group A were sacrificed at 4 weeks; group B were fed ad libitum, and groups C and D were fed 2.8 and 2.4 g/day, respectively, from 4 to 8 weeks of age. Groups B-D were sacrificed at 8 weeks. Chemical components were estimated for all groups. MER was estimated using a model that partitioned metabolizable energy intake into that used for maintenance, and protein and fat deposition. The feed conversion ratio for the B group was significantly higher in the H than in the L line. Feed intake for metabolic energy content per metabolic body size was significantly also higher in the H line, whereas accumulated energy content per metabolic body size was significantly higher in the L line. MER of the H line was greater than that of the L line (P < 0.10). These results suggest that selection for H or L OC produced differences in chemical components, feed efficiency, and MER between the H and L lines. © 2016 Japanese Society of Animal Science.

  10. Examination of Perovskite Structure CaMnO3-δ with MgO Addition as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Using Methane and Syngas

    Directory of Open Access Journals (Sweden)

    Dazheng Jing

    2013-01-01

    Full Text Available Perovskite structure oxygen carriers with the general formula CaMnxMg1-xO3-δ were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900°C to 1050°C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH4 to CO2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO3-δ. The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO3-δ have no thermodynamic limitations for methane oxidation to CO2 and H2O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work.

  11. Oxygen as a promoter for efficient degradation of organic pollutants by high-temperature and high-pressure electrochemistry.

    Science.gov (United States)

    Zhou, Minghua; Lei, Lecheng; Dai, Qizhou

    2007-07-07

    The introduction of oxygen in electrochemical oxidation at relatively high temperature and pressure as a promoter resulting in synergetic effects, greatly improves the mineralization of high-concentrated organic pollutants.

  12. Oxygen adsorption on Pt(110)-(1x2): new high-coverage structures

    DEFF Research Database (Denmark)

    Helveg, Stig; Lorensen, Henrik Qvist; Horch, Sebastian

    1999-01-01

    to the formation of a new high-coverage oxide-like structure with a local coverage of two oxygen atoms per platinum surface atom. We find that the repulsive O-O interactions for the O/Pt(110) system are compensated by an effective O-O attractive interaction originating from a strong coupling between oxygen...

  13. Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels

    Directory of Open Access Journals (Sweden)

    Chun Guo

    2015-12-01

    Full Text Available The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO2. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.

  14. Experimental Investigation of CaMnO3−δ Based Oxygen Carriers Used in Continuous Chemical-Looping Combustion

    Directory of Open Access Journals (Sweden)

    Peter Hallberg

    2014-01-01

    Full Text Available Three materials of perovskite structure, CaMn1−xMxO3−δ (M = Mg or Mg and Ti, have been examined as oxygen carriers in continuous operation of chemical-looping combustion (CLC in a circulating fluidized bed system with the designed fuel power 300 W. Natural gas was used as fuel. All three materials were capable of completely converting the fuel to carbon dioxide and water at 900°C. All materials also showed the ability to release gas phase oxygen when fluidized by inert gas at elevated temperature (700–950°C; that is, they were suitable for chemical looping with oxygen uncoupling (CLOU. Both fuel conversion and oxygen release improved with temperature. All three materials also showed good mechanical integrity, as the fraction of fines collected during experiments was small. These results indicate that the materials are promising oxygen carriers for chemical-looping combustion.

  15. Chemical tracers of high-metallicity environments

    CERN Document Server

    Bayet, E; Bell, T A; Viti, S

    2012-01-01

    We present for the first time a detailed study of the properties of molecular gas in metal-rich environments such as early-type galaxies (ETGs). We have explored Photon-Dominated Region (PDR) chemistry for a wide range of physical conditions likely to be appropriate for these sources. We derive fractional abundances of the 20 most chemically reactive species as a function of the metallicity, as a function of the optical depth and for various volume number gas densities, Far-Ultra Violet (FUV) radiation fields and cosmic ray ionisation rates. We also investigate the response of the chemistry to the changes in $\\alpha-$element enhancement as seen in ETGs. We find that the fractional abundances of CS, H$_{2}$S, H$_{2}$CS, H$_{2}$O, H$_{3}$O$^{+}$, HCO$^{+}$ and H$_{2}$CN seem invariant to an increase of metallicity whereas C$^{+}$, CO, C$_{2}$H, CN, HCN, HNC and OCS appear to be the species most sensitive to this change. The most sensitive species to the change in the fractional abundance of $\\alpha-$elements ar...

  16. Effects of Chemical versus Electrochemical Delithiation on the Oxygen Evolution Reaction Activity of Nickel-Rich Layered LiMO2.

    Science.gov (United States)

    Augustyn, Veronica; Manthiram, Arumugam

    2015-10-01

    Nickel-rich layered LiMO2 (M = transition metal) oxides doped with iron exhibit high oxygen evolution reaction (OER) activity in alkaline electrolytes. The LiMO2 oxides offer the possibility of investigating the influence of the number of d electrons on OER by tuning the oxidation state of M via chemical or electrochemical delithiation. Accordingly, we investigate here the electrocatalytic behavior of LiNi0.7Co0.3O2 and LiNi0.7Co0.2Fe0.1O2 before and after chemical delithiation. In addition to varying the oxidation state of the transition-metal ions, we find that chemical delithiation also affects the local chemical environment and morphology. The electrochemical response differs depending on whether the delithiation occurred ex situ chemically or in situ during the electrocatalysis. The results point to the important role of in situ transformation in LiMO2 in alkaline electrolytes during electrocatalytic cycling.

  17. Silicon-on-glass pore network micromodels with oxygen-sensing fluorophore films for chemical imaging and defined spatial structure

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Kelly, Ryan T.; Suter, Jonathan D.; Anheier, Norman C.

    2012-11-21

    Pore network microfluidic models were fabricated by a silicon-on-glass technique that provides the precision advantage of dry etched silicon while creating a structure that is transparent across all microfluidic channels and pores, and can be imaged from either side. A silicon layer is bonded to an underlying borosilicate glass substrate and thinned to the desired height of the microfluidic channels and pores. The silicon is then patterned and through-etched by deep reactive ion etching (DRIE), with the underlying glass serving as an etch stop. After bonding on a transparent glass cover plate, one obtains a micromodel in oxygen impermeable materials with water wet surfaces where the microfluidic channels are transparent and structural elements such as the pillars creating the pore network are opaque. The micromodel can be imaged from either side. The advantageous features of this approach in a chemical imaging application are demonstrated by incorporating a Pt porphyrin fluorophore in a PDMS film serving as the oxygen sensing layer and a bonding surface, or in a polystyrene film coated with a PDMS layer for bonding. The sensing of a dissolved oxygen gradient was demonstrated using fluorescence lifetime imaging, and it is shown that different matrix polymers lead to optimal use in different ranges dissolved oxygen concentration. Imaging with the opaque pillars in between the observation direction and the continuous fluorophore film yields images that retain spatial information in the sensor image.

  18. Regenerable MgO promoted metal oxide oxygen carriers for chemical looping combustion

    Science.gov (United States)

    Siriwardane, Ranjani V.; Miller, Duane D.

    2014-08-19

    The disclosure provides an oxygen carrier comprised of a plurality of metal oxide particles in contact with a plurality of MgO promoter particles. The MgO promoter particles increase the reaction rate and oxygen utilization of the metal oxide when contacting with a gaseous hydrocarbon at a temperature greater than about 725.degree. C. The promoted oxide solid is generally comprised of less than about 25 wt. % MgO, and may be prepared by physical mixing, incipient wetness impregnation, or other methods known in the art. The oxygen carrier exhibits a crystalline structure of the metal oxide and a crystalline structure of MgO under XRD crystallography, and retains these crystalline structures over subsequent redox cycles. In an embodiment, the metal oxide is Fe.sub.2O.sub.3, and the gaseous hydrocarbon is comprised of methane.

  19. Dislocations as a boundary between charge density wave and oxygen rich phases in a cuprate high temperature superconductor

    Science.gov (United States)

    Poccia, Nicola; Ricci, Alessandro; Campi, Gaetano; Bianconi, Antonio

    2017-03-01

    Multiple functional ionic and electronic orders are observed in high temperature superconducting cuprates. The charge density wave order is one of them and it is spatially localized in different regions of the material. It is also known that the oxygen interstitials introduced by chemical intercalation self-organize in different oxygen rich regions corresponding with hole rich regions in the CuO2 layers left empty by the charge density wave order domains. However, what happens in between these two orders is not known, and neither there is a method to control this spatial separation. Here we demonstrate by using scanning nano x-ray diffraction, that dislocations or grain boundaries in the material can act as boundary between charge density wave and oxygen rich phases in a optimally doped {{La}}2{{CuO}}4+y high temperature superconductor. Dislocations can be used therefore to control the anti-correlation of the charge density wave order with the oxygen interstitials in specific portion of the material.

  20. A study of the oxygen dynamics in a reactive Ar/O2 high power impulse magnetron sputtering discharge using an ionization region model

    Science.gov (United States)

    Lundin, D.; Gudmundsson, J. T.; Brenning, N.; Raadu, M. A.; Minea, T. M.

    2017-05-01

    The oxygen dynamics in a reactive Ar/O2 high power impulse magnetron sputtering discharge has been studied using a new reactive ionization region model. The aim has been to identify the dominating physical and chemical reactions in the plasma and on the surfaces of the reactor affecting the oxygen plasma chemistry. We explore the temporal evolution of the density of the ground state oxygen molecule O 2 ( X 1 Σg - ) , the singlet metastable oxygen molecules O 2 ( a 1 Δ g ) and O 2 ( b 1 Σ g ) , the oxygen atom in the ground state O(3P), the metastable oxygen atom O(1D), the positive ions O2 + and O+, and the negative ion O-. We furthermore investigate the reaction rates for the gain and loss of these species. The density of atomic oxygen increases significantly as we move from the metal mode to the transition mode, and finally into the compound (poisoned) mode. The main gain rate responsible for the increase is sputtering of atomic oxygen from the oxidized target. Both in the poisoned mode and in the transition mode, sputtering makes up more than 80% of the total gain rate for atomic oxygen. We also investigate the possibility of depositing stoichiometric TiO2 in the transition mode.

  1. Clarification of the oxygen adsorption properties of YBaCo_4O_7 at high temperature by thermogravimetry

    Institute of Scientific and Technical Information of China (English)

    朱保峰; 郝好山; 张勇; 贾建峰; 胡行

    2010-01-01

    The oxygen adsorption/desorption properties of YBaCo4O7 at high temperature were investigated by thermogravimetry(TG) method,in which two types of oxygen adsorption were combined.The first type adsorbed oxygen at about 700 °C and released the adsorbed oxygen at 880 °C.After the first type oxygen desorption,even the temperature and oxygen flow were kept the same,a second type oxygen adsorption at about 880 °C occurred and the adsorbed oxygen were released at above 980 °C.The combination of these two types of...

  2. A strategy for oxygen conditioning at high altitude: comparison with air conditioning.

    Science.gov (United States)

    West, John B

    2015-09-15

    Large numbers of people live or work at high altitude, and many visit to trek or ski. The inevitable hypoxia impairs physical working capacity, and at higher altitudes there is also cognitive impairment. Twenty years ago oxygen enrichment of room air was introduced to reduce the hypoxia, and this is now used in dormitories, hotels, mines, and telescopes. However, recent advances in technology now allow large amounts of oxygen to be obtained from air or cryogenic oxygen sources. As a result it is now feasible to oxygenate large buildings and even institutions such as hospitals. An analogy can be drawn between air conditioning that has improved the living and working conditions of millions of people who live in hot climates and oxygen conditioning that can do the same at high altitude. Oxygen conditioning is similar to air conditioning except that instead of cooling the air, the oxygen concentration is raised, thus reducing the equivalent altitude. Oxygen conditioning on a large scale could transform living and working conditions at high altitude, where it could be valuable in homes, hospitals, schools, dormitories, company headquarters, banks, and legislative settings. Copyright © 2015 the American Physiological Society.

  3. Oxygen Consumption by Red Wines. Part II: Differential Effects on Color and Chemical Composition Caused by Oxygen Taken in Different Sulfur Dioxide-Related Oxidation Contexts.

    Science.gov (United States)

    Carrascon, Vanesa; Fernandez-Zurbano, Purificación; Bueno, Mónica; Ferreira, Vicente

    2015-12-30

    Chemical changes caused by oxidation of red wines during 5 consecutive air-saturation cycles have been assessed. In order to investigate the existing relationship between the effects caused by O2 and the levels and consumption rates of wine SO2, the total oxygen consumed by the wines (16-25 mg/L) was subdivided into different nonmutually exclusive categories. The ones found most influential on chemical changes were the O2 consumed in the first saturation without equivalent SO2 consumption (O2preSO2) and the O2 consumed when levels of free SO2 were below 5 mg/L (radical forming O2). Chromatic changes were strongly related to both O2 categories, even though anthocyanidin degradation was not related to any O2 category. Radical forming O2 prevented both formation of red pigments and reduction of epigallocatechin and other proanthocyanidins, induced accumulation of phenolic acids, and caused losses of β-damascenone and whiskylactone without evidence of acetaldehyde formation. O2preSO2 seemed to play a key role in the formation of blue pigments and in the decrease of Folin index and of many important aroma compounds.

  4. Experiment to measure oxygen opacity at high density and temperature

    Science.gov (United States)

    Keiter, Paul; Mussack, Katie; Orban, Chris; Colgan, James; Ducret, Jean-Eric; Fontes, Christopher J.; Guzik, Joyce Ann; Heeter, Robert F.; Kilcrease, Dave; Le Pennec, Maelle; Mancini, Roberto; Perry, Ted; Turck-Chièze, Sylvaine; Trantham, Matt

    2017-06-01

    In recent years, there has been a debate over the abundances of heavy elements (Z >2) in the solar interior. Recent solar atmosphere models [Asplund 2009] find a significantly lower abundance for C, N, and O compared to models used roughly a decade ago. This discrepancy has led to an investigation of opacities through laboratory experiments and improved opacity models for many of the larger contributors to the sun’s opacity, including iron and oxygen. Recent opacity measurements of iron disagree with opacity model predictions [Bailey et al, 2015]. Although these results are still controversial, repeated scrutiny of the experiment and data has not produced a conclusive reason for the discrepancy. New models have been implemented in the ATOMIC opacity code for C, O and Fe to address the solar abundance issue [Colgan, 2013]. Armstrong et al [2014] have also implemented changes in the ATOMIC code for low-Z elements. However, no data currently exists to test the low-Z material models in the regime relevant to the solar convection zone. We present an experimental design using the opacity platform developed at the National Ignition Facility to study the oxygen opacity at densities and temperatures near the solar convection zone conditions.This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HEDPLP, grant No. DE-NA0001840, and the NLUF Program, grant No. DE-NA0000850, and through LLE, University of Rochester by the NNSA/OICF under Agreement No. DE-FC52-08NA28302.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Thomaz, R.; Gutierres, L.I. [Faculdade de Física, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, 90619-900 Porto Alegre (Brazil); Morais, J. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av Bento Gonçalves 9500, 91501-970 Porto Alegre (Brazil); Louette, P. [Université de Namur, Rue de Bruxelles 61, 5000 Namur (Belgium); Severin, D. [Materials Research, GSI Helmholtz Centre, Planckstr. 1, 64291 Darmstadt (Germany); Trautmann, C. [Materials Research, GSI Helmholtz Centre, Planckstr. 1, 64291 Darmstadt (Germany); Technische Universität Darmstadt, Alarich-Weiss-Straße2, 64287 Darmstadt (Germany); Pireaux, J.J. [Université de Namur, Rue de Bruxelles 61, 5000 Namur (Belgium); Papaléo, R.M. [Faculdade de Física, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, 90619-900 Porto Alegre (Brazil)

    2015-12-15

    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 (C=O and C−O−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.

  7. Metal-free and Oxygen-free Graphene as Oxygen Reduction Catalysts for Highly Efficient Fuel Cells

    Science.gov (United States)

    2013-06-30

    L. Science 2009, 323, 760) and nitrogen-doped graphene sheets (Qu, L.; Liu, Y.; Baek, J.-B.; Dai, L. ACS Nano 2010, 4, 1321) as highly efficient...fuel to create heat, fuel cells convert chemical energy directly into electricity. By pumping , for example, hydrogen gas onto one electrode (the anode...760) and nitrogen-doped graphene sheets (Qu, L.; Liu, Y.; Baek, J.-B.; Dai, L. ACS Nano 2010, 4, 1321) as highly efficient ORR, we have developed in

  8. High-Efficiency, High-Capacity, Low-NOx Aluminum Melting Using Oxygen-Enhanced Combustion

    Energy Technology Data Exchange (ETDEWEB)

    D' Agostini, M.D.

    2000-06-02

    This report describes the development and application of a novel oxygen enhanced combustion system with an integrated vacuum swing adsorption (VSA) oxygen supply providing efficient, low NOx melting in secondary aluminum furnaces. The mainstay of the combustion system is a novel air-oxy-natural gas burner that achieves high productivity and energy efficiency with low NOx emissions through advanced mixing concepts and the use of separate high- and low-purity oxidizer streams. The technology was installed on a reverberatory, secondary aluminum melting plant at the Wabash Aluminum Alloy's Syracuse, N.Y. plant, where it is currently in operation. Field testing gave evidence that the new burner technology meets the stringent NOx emissions target of 0.323 lb NO2/ton aluminum, thus complying with regulations promulgated by Southern California's South Coast Air Quality Management District (SCAQMD). Test results also indicated that the burner technology exceeded fuel efficiency and melting capacity goals. Economic modeling showed that the novel air-oxy-fuel (ADF) combustion technology provides a substantial increase in furnace profitability relative to air-fuel operation. Model results also suggest favorable economics for the air-oxy-fuel technology relative to a full oxy-fuel conversion of the furnace.

  9. Effects of the Spectral Line Broadened Model on the Performance of a Flowing Chemical Oxygen-Iodine Laser

    Institute of Scientific and Technical Information of China (English)

    高智; 胡利民

    2002-01-01

    A new gain saturation model of chemical oxygen-iodine lasers (COILs) is deduced from the conservation equations of the population number of upper and lower lasing levels. The present model is compared with both the Voigt profile function model and its low-pressure limit model. The differences between the Voigt profile function model or its low-pressure limit model and the model presented here are pointed out, such as the length of power extraction, the optimal range of the threshold gain. These differences are useful for the optimization of COIL adjustable parameters.

  10. Oxygen enrichment and its application to life support systems for workers in high-altitude areas.

    Science.gov (United States)

    Li, Yongling; Liu, Yingshu

    2014-01-01

    Workers coming from lowland regions are at risk of developing acute mountain sickness (AMS) when working in low oxygen high-altitude areas. The aim of this study was to improve the conditions that lead to hypoxia and ensure the safety of the high-altitude workers. We analyzed the influence of low atmospheric pressure on the oxygen enrichment process in high-altitude areas using an engineering method called low-pressure swing adsorption (LPSA). Fourteen male subjects were screened and divided into three groups by type of oxygen supply system used: (1) oxygen cylinder group; (2) LPSA oxygen dispersal group; and (3) control group. These tests included arterial oxygen saturation (SaO2), pulse rate (PR), breaths per minute (BPM), and blood pressure (BP). The results showed that after supplying oxygen using the LPSA method at the tunnel face, the SaO2 of workers increased; the incidence of acute mountain sickness, PR, and BPM significantly decreased. The LPSA life support system was found to be a simple, convenient, efficient, reliable, and applicable approach to ensure proper working conditions at construction sites in high-altitude areas.

  11. Mesoporous Nitrogen Doped Carbon-Glass Ceramic Cathode for High Performance Lithium-Oxygen Battery

    Science.gov (United States)

    2012-06-01

    Hardwick, and J.- M. Tarascon, Nature Materials, vol. 11, pp 19-29, 2012. 2. Linden , D. (Ed), Handbook of Batteries , 2nd Edition, Mc-Graw-Hill, New...AFRL-RQ-WP-TP-2015-0053 MESOPOROUS NITROGEN DOPED CARBON-GLASS CERAMIC CATHODE FOR HIGH PERFORMANCE LITHIUM-OXYGEN BATTERY (POSTPRINT...DOPED CARBON-GLASS CERAMIC CATHODE FOR HIGH PERFORMANCE LITHIUM-OXYGEN BATTERY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c

  12. Electrochemical Performance of Highly Mesoporous Nitrogen Doped Carbon Cathode in Lithium-Oxygen Batteries (Postprint)

    Science.gov (United States)

    2011-03-01

    Chem. Lett. 1 (2010) 2193–2203. [3] F.T. Wagner, B. Lakshmanan, M.F. Mathias, J. Phys. Chem. Lett. 1 (2010) 2204–2219. [4] D. Linden (Ed.), Handbook ...AFRL-RQ-WP-TP-2015-0052 ELECTROCHEMICAL PERFORMANCE OF HIGHLY MESOPOROUS NITROGEN DOPED CARBON CATHODE IN LITHIUM-OXYGEN BATTERIES ...01 March 2011 4. TITLE AND SUBTITLE ELECTROCHEMICAL PERFORMANCE OF HIGHLY MESOPOROUS NITROGEN DOPED CARBON CATHODE IN LITHIUM-OXYGEN BATTERIES

  13. Supplemental Perioperative Oxygen to Reduce Surgical Site Infection After High Energy Fracture Surgery

    Science.gov (United States)

    2016-10-01

    AWARD NUMBER: W81XWH-12-1-0588 TITLE: Supplemental Perioperative Oxygen to Reduce Surgical Site Infection After High Energy Fracture Surgery ...Infection After High Energy Fracture Surgery 5a. CONTRACT NUMBER W81XWH-12-1-0588 5b. GRANT NUMBER OR110123 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR...prospective randomized treatment trial investigating if supplemental perioperative oxygen use will reduce surgical site infection after surgery on fractures

  14. A Simulator for Producing of High Flux Atomic Oxygen Beam by Using ECR Plasma Source

    Institute of Scientific and Technical Information of China (English)

    Shuwang DUO; Meishuan LI; Yaming ZHANG

    2004-01-01

    In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic 5~30 eV and a cross section of φ80 mm could be obtained under the operating pressure of 10-1~10-3 Pa. Such a high flux source can provide accelerated simulation tests of materials and coatings for space applications.

  15. Influence of Trace Oxygen on the Mechanical Properties of High Pure Silver during Natural Aging

    Institute of Scientific and Technical Information of China (English)

    XIE Hongchao; ZHUANG Dianxiang; LI Ji; CHEN Liangwei; YANG Anheng; LUO Yanbo; ZHU Yong

    2012-01-01

    Two kinds of high pure silver materials with 5.3 ppm oxygen and 32.7 ppm oxygen were prepared by various melting processes,both samples were subjected to accumulative rolling with 95% thickness reduction.Their mechanical properties were tested during long natural aging.Results showed that the Ag sheet with 5.3 ppm oxygen is at full annealed state when natural aging 58 days or kept at 150℃ for 30 minutes,and the Ag sheet with 32.7 ppm oxygen is a little of recovery when natural aging a year.It is suggested that appropriate oxygen interstitial solute in Ag solid solution and a few of Ag2O particles at Ag grain boundaries impede the recovery and recrystallization of Ag sheets.

  16. Synthesis of thermal and chemical resistant oxygen barrier starch with reinforcement of nano silicon carbide.

    Science.gov (United States)

    Dash, Satyabrata; Swain, Sarat K

    2013-09-12

    Starch/silicon carbide (starch/SiC) bionanocomposites were synthesized by solution method using different wt% of silicon carbide with starch matrix. The interaction between starch and silicon carbide was studied by Fourier transform infrared (FTIR) spectroscopy. The structure of the bionanocomposites was investigated by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). Thermal property of starch/SiC bionanocomposites was measured and a significant enhancement of thermal resistance was noticed. The oxygen barrier property of the composites was studied and a substantial reduction in permeability was observed as compared to the virgin starch. The reduction of oxygen permeability with enhancement of thermal stability of prepared bionanocomposites may enable the materials suitable for thermal resistant packaging and adhesive applications.

  17. Combustion Effects in Laser-oxygen Cutting: Basic Assumptions, Numerical Simulation and High Speed Visualization

    Science.gov (United States)

    Zaitsev, Alexander V.; Ermolaev, Grigory V.

    Laser-oxygen cutting is very complicated for theoretical description technological process. Iron-oxygen combustion playing a leading role making it highly effective, able to cut thicker plates and, at the same time, producing special types of striations and other defects on the cut surface. In this paper results of numerical simulation based on elementary assumptions on iron-oxygen combustion are verified with high speed visualization of laser-oxygen cutting process. On a base of assumption that iron oxide lost its protective properties after melting simulation of striation formation due cycles of laser induced non self-sustained combustion is proposed. Assumption that reaction limiting factor is oxygen transport from the jet to cutting front allows to calculate reaction intensity by solving Navier - Stokes and diffusion system in gas phase. Influence of oxygen purity and pressure is studied theoretically. The results of numerical simulation are examined with high speed visualization of laser-oxygen cutting of 4-20 mm mild steel plates at cutting conditions close to industrial.

  18. The role of high flow oxygen therapy in acute respiratory failure.

    Science.gov (United States)

    Masclans, J R; Pérez-Terán, P; Roca, O

    2015-11-01

    Acute respiratory failure represents one of the most common causes of intensive care unit admission and oxygen therapy remains the first-line therapy in the management of these patients. In recent years, high-flow oxygen via nasal cannula has been described as a useful alternative to conventional oxygen therapy in patients with acute respiratory failure. High-flow oxygen via nasal cannula rapidly alleviates symptoms of acute respiratory failure and improves oxygenation by several mechanisms, including dead space washout, reduction in oxygen dilution and inspiratory nasopharyngeal resistance, a moderate positive airway pressure effect that may generate alveolar recruitment and an overall greater tolerance and comfort with the interface and the heated and humidified inspired gases. However, the experience in adults is still limited and there are no clinical guidelines to establish recommendations for their use. This article aims to review the existing evidence on the use of high-flow oxygen via nasal cannula in adults with acute respiratory failure and its possible applications, advantages and limitations.

  19. Characterization of a novel micro-pressure swirl reactor for removal of chemical oxygen demand and total nitrogen from domestic wastewater at low temperature.

    Science.gov (United States)

    Ren, Qingkai; Yu, Yang; Zhu, Suiyi; Bian, Dejun; Huo, Mingxin; Zhou, Dandan; Huo, Hongliang

    2017-02-06

     A novel micro-pressure swirl reactor (MPSR) was designed and applied to treat domestic wastewater at low temperature by acclimating microbial biomass with steadily decreasing temperature from 15 to 3 °C. Chemical oxygen demand (COD) was constantly removed by 85% and maintained below 50 mg L(-1) in the effluent during the process. When the air flow was controlled at 0.2 m(3) h(-1), a swirl circulation was formed in the reactor, which created a dissolved oxygen (DO) gradient with a low DO zone in the center and a high DO zone in the periphery for denitrification and nitrification. 81% of total nitrogen was removed by this reactor, in which ammonium was reduced by over 90%. However, denitrification was less effective because of the presence of low levels of oxygen. The progressively decreasing temperature favored acclimation of psychrophilic bacteria in the reactor, which replaced mesophilic bacteria in the process of treatment.

  20. The Effect of Sintering Oxygen Partial Pressure on a SmBiO3 Buffer Layer for Coated Conductors via Chemical Solution Deposition

    Directory of Open Access Journals (Sweden)

    Xiaolei Zhu

    2016-10-01

    Full Text Available The application of high-temperature YBa2Cu3O7−δ (YBCO superconducting material is a considerable prospect for the growing energy shortages. Here, SmBiO3 (SBO films were deposited on (100-orientated yttrium-stabilized zirconia (YSZ simple crystal substrates via the chemical solution deposition (CSD approach for coated conductors, and the effects of sintering oxygen partial pressure on SBO films were studied. The crystalline structures and surface morphologies of SBO films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and atomic force microscope (AFM. The optimized growth temperature, the intensity ratios of the SBO (200 peak to the SBO (111 peak, and the crystallinities of SBO films increased with the sintering oxygen partial pressure. The SEM and AFM images displayed a smooth and well-distributed surface in the argon atmosphere. The subsequent YBCO films with superconducting transition temperatures (Tc = 89.5 K, 90.2 K, and 86.2 K and critical current densities (Jc = 0.88 MA/cm2, 1.69 MA/cm2, and 0.09 MA/cm2; 77 K, self-field were deposited to further check the qualities of the SBO layer. These results indicated that sintering oxygen partial pressure had an effect on the epitaxial growth of the SBO buffer layer and YBCO superconducting properties. The experimental results may be a usable reference for the epitaxial growth of YBCO-coated conductors and other oxides.

  1. Performance of Ni-based, Fe-based and Co-based Oxygen Carriers in Chemical-Looping Hydrogen Generation

    Institute of Scientific and Technical Information of China (English)

    Liang Hao; Zhang Xiwen; Fang Xiangchen; Yuan Honggang

    2013-01-01

    Ni-based, Fe-based and Co-based oxygen carriers with perovskite oxides used as the supports were prepared by citric acid complexation method. The oxygen carriers were characterized by thermal analysis, H2-temperature-programmed reduction and X-ray diffraction methods. Performance tests were evaluated through Chemical-Looping Hydrogen Genera-tion in a ifxed-bed reactor operating at atmospheric pressure. The characterization results showed that all samples were composed of metal oxides and perovskite oxides. Performance results indicated that CH4 conversion over the oxygen car-riers decreased in the following order:NiO/LaNiO3>Co2O3/LaCoO3>Fe2O3/LaFeO3. The ability of NiO/LaNiO3 and Fe2O3/LaFeO3 to decompose water was stronger than that of Co2O3/LaCoO3 as evidenced by our experiments. H2 amounting to 80 mL upon reacting on methane in every cycle could be completely oxidized by NiO/LaNiO3 at 900℃in the period from the third cycle to the eighth cycle.

  2. [Research on chemical oxygen demand optical detection method based on the combination of multi-source spectral characteristics].

    Science.gov (United States)

    Wu, Guo-Qing; Bi, Wei-Hong

    2014-11-01

    A novel method based on multi-source spectral characteristics of the combination is proposed for chemical oxygen demand detection. First, the ultraviolet and near infrared spectrum of the actual water samples are collected respectively. After pretreatment of the spectrum data, the features of the spectrum are extracted by the nonnegative matrix factorization algorithm for training after normalization. Particle swarm and least squares support vector machines algorithm are applied to predicting chemical oxygen demand of the validation set of water samples. The effect of spectrum's base number on the predicted results is discussed. The experimental results show that the best base number of the ultraviolet spectrum is 5, the best base number of the near infrared spectrum is 2; The validation set correlation coefficient of the prediction model is 0.999 8, and the root mean square error of prediction is 3.26 mg x L(-1). Experimental results demonstrate that the nonnegative matrix factorization algorithm is more suitable for feature extraction of spectral data, and the least squares support vector machines algorithm as a quantitative model correction method of the actual water samples can get good prediction accuracy with different feature extraction methods (principal component analysis, independent component analysis), spectroscopic methods (ultraviolet spectrum method, near infrared spectrum method) and different combination pattern (data direct combination, combining data first, then feature extraction) respectively.

  3. Quantum dots assisted photocatalysis for the chemiluminometric determination of chemical oxygen demand using a single interface flow system

    Energy Technology Data Exchange (ETDEWEB)

    Silvestre, Cristina I.C.; Frigerio, Christian [Requimte, Department of Chemistry, Faculty of Pharmacy, Porto University, Rua Anibal Cunha 164, 4099-030, Porto (Portugal); Santos, Joao L.M., E-mail: joaolms@ff.up.pt [Requimte, Department of Chemistry, Faculty of Pharmacy, Porto University, Rua Anibal Cunha 164, 4099-030, Porto (Portugal); Lima, Jose L.F.C. [Requimte, Department of Chemistry, Faculty of Pharmacy, Porto University, Rua Anibal Cunha 164, 4099-030, Porto (Portugal)

    2011-08-12

    Highlights: {yields} A novel flow method for the determination of chemical oxygen demand is proposed. {yields} CdTe nanocrystals are irradiated with UV light to generate strong oxidizing species. {yields} Reactive species promote a fast catalytic degradation of organic matter. {yields} Luminol is used as a chemiluminescence probe for indirect COD assessment. {yields} A single interface flow system was implemented to automate the assays. - Abstract: A novel flow method for the determination of chemical oxygen demand (COD) is proposed in this work. It relies on the combination of a fully automated single interface flow system, an on-line UV photocatalytic unit and quantum dot (QD) nanotechnology. The developed approach takes advantage of CdTe nanocrystals capacity to generate strong oxidizing species upon irradiation with UV light, which fostered a fast catalytic degradation of the organic compounds. Luminol was used as a chemiluminescence (CL) probe for indirect COD assessment, since it is easily oxidized by the QD generated species yielding a strong CL emission that is quenched in the presence of the organic matter. The proposed methodology allowed the determination of COD concentrations between 1 and 35 mg L{sup -1}, with good precision (R.S.D. < 1.1%, n = 3) and a sampling frequency of about 33 h{sup -1}. The procedure was applied to the determination of COD in wastewater certified reference materials and the obtained results showed an excellent agreement with the certified values.

  4. Effects of chemical oxygen demand (COD)/N ratios on pollutants removal in the subsurface wastewater infiltration systems with/without intermittent aeration.

    Science.gov (United States)

    Song, Siyu; Pan, Jing; Wu, Shiwei; Guo, Yijing; Yu, Jingxiao; Shan, Qingchi

    2016-01-01

    The matrix oxidation reduction potential level, organic pollutants and nitrogen removal performances of eight subsurface wastewater infiltration systems (SWISs) (four with intermittent aeration, four without intermittent aeration) fed with influent chemical oxygen demand (COD)/N ratio of 3, 6, 12 and 18 were investigated. Nitrification of non-aerated SWISs was poor due to oxygen deficiency while higher COD/N ratios further led to lower COD and nitrogen removal rate. Intermittent aeration achieved almost complete nitrification, which successfully created aerobic conditions in the depth of 50 cm and did not change anoxic or anaerobic conditions in the depth of 80 and 110 cm. The sufficient carbon source in high COD/N ratio influent greatly promoted denitrification in SWISs with intermittent aeration. High average removal rates of COD (95.68%), ammonia nitrogen (NH4(+)-N) (99.32%) and total nitrogen (TN) (89.65%) were obtained with influent COD/N ratio of 12 in aerated SWISs. The results suggest that intermittent aeration was a reliable option to achieve high nitrogen removal in SWISs, especially with high COD/N ratio wastewater.

  5. High Energy Density Lithium Air Batteries for Oxygen Concentrators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For NASA's Exploration Medical Capabilities mission, extremely high specific energy power sources, with specific energy over 2000 Wh/kg, are urgently sought after....

  6. Chemical reaction of atomic oxygen with evaporated films of copper, part 4

    Science.gov (United States)

    Fromhold, A. T.; Williams, J. R.

    1990-01-01

    Evaporated copper films were exposed to an atomic oxygen flux of 1.4 x 10(exp 17) atoms/sq cm per sec at temperatures in the range 285 to 375 F (140 to 191 C) for time intervals between 2 and 50 minutes. Rutherford backscattering spectroscopy (RBS) was used to determine the thickness of the oxide layers formed and the ratio of the number of copper to oxygen atoms in the layers. Oxide film thicknesses ranged from 50 to 3000 A (0.005 to 0.3 microns, or equivalently, 5 x 10(exp -9) to 3 x 10(exp -7); it was determined that the primary oxide phase was Cu2O. The growth law was found to be parabolic (L(t) varies as t(exp 1/2)), in which the oxide thickness L(t) increases as the square root of the exposure time t. The analysis of the data is consistent with either of the two parabolic growth laws. (The thin-film parabolic growth law is based on the assumption that the process is diffusion controlled, with the space charge within the growing oxide layer being negligible. The thick-film parabolic growth law is also based on a diffusion controlled process, but space-charge neutrality prevails locally within very thick oxides.) In the absence of a voltage measurement across the growing oxide, a distinction between the two mechanisms cannot be made, nor can growth by the diffusion of neutral atomic oxygen be entirely ruled out. The activation energy for the reaction is on the order of 1.1 eV (1.76 x 10(exp -19) joule, or equivalently, 25.3 kcal/mole).

  7. Study of high coverages of atomic oxygen on the Pt(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Parker, D.H.; Bartram, M.E.; Koel, B.E. (Univ. of Colorado, Boulder (United States))

    1989-01-01

    Atomic oxygen coverages of up to 0.75 monolayer (ML) may be adsorbed cleanly on Pt(111) surfaces under UHV conditions by exposure to NO{sub 2} at 400 K. The authors have studied this adsorbed oxygen layer by using AES, LEED, UPS, HREELS, TPD, and work function ({Delta}{phi}) measurements. The (2{times}2)-O structure formed at {theta}{sub o} = 0.25 ML is still apparent at {theta}{sub o} = 0.60 ML and a faint (2{times}2) pattern persists even up to {theta}{sub o} = 0.75 ML.AES and {Delta}{phi} measurements show no evidence for chemically distinct species in the adlayer as a function of oxygen coverage. HREELS spectra clearly rule out the presence of molecular oxygen and oxide species over the range of oxygen coverage studied. UPS also shows no shift in binding energy of the oxygen-derived peak as the coverage is increased. These spectroscopic probes indicate that all oxygen is present as atomic oxygen with no indication of oxide formation or molecular oxygen at any coverage. Multiple O{sub 2} desorption peaks observed in TPD are interpreted as arising largely from kinetic effects rather than a result of multiple, distinctly different chemical species, even though large changes in the Pt-O bond energy are determined from the TPD data. The activation energy for O{sub 2} desorption reflects the sum of the heat of dissociative adsorption of O{sub 2} and the activation energy for O{sub 2} desorption reflects the sum of the heat of dissociative adsorption of O{sub 2} and the activation energy for O{sub 2} dissociation. The structure in the O{sub 2} TPD spectrum is due to large changes in the activation energy for O{sub 2} desorption resulting from increases in the barrier to dissociative O{sub 2} chemisorption and decreases in the Pt-O bond energy.

  8. Extended oxygen delignification of high kappa softwood pulp in a flow-through reactor

    OpenAIRE

    Jafari, Vahid

    2015-01-01

    Julkaistu vain painettuna, saatavuus katso Bibid. Published only in printed form, availability see Bibid Oxygen delignification (O-delignification) is an important tool for improving yield, reducing lignin content of pulp and lowering the bleach chemical consumption in the pulp and paper industries. This process is designed after cooking to maximize the delignification rate in comparison to the final phase of Kraft cooking without sacrificing pulp quality. In order to improve the yield of ...

  9. Synthesis of CeO2-based core/shell nanoparticles with high oxygen storage capacity

    Science.gov (United States)

    Uzunoglu, Aytekin; Kose, Dursun Ali; Stanciu, Lia A.

    2017-07-01

    Ceria plays a key role in various applications including sensing and catalysis owing to its high oxygen storage capacity (OSC). The aim of this work is to prepare novel MO x /CeO2 (M: Zr, Ti, Cu) metal oxide systems with core/shell structures using a facile two-step chemical precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption methods. The OSC property of the samples was evaluated using TGA analysis conducted at 600 °C under reductive (5% H2/Ar) and oxidative (synthetic air) environments. The OSCs of the samples were found to be 130, 253, and 2098 µmol-O2/g for ZrO2/CeO2, TiO2/CeO2, and CuO/CeO2, respectively. Effects of heat treatment on the physical and redox properties of the samples were also evaluated. In this regard, the samples were exposed to 500 °C for 5 h under ambient environment. It was observed that the heat treatment induced the formation of mixed metal oxide alloys and the BET surface area of the samples diminished significantly. The OSC of the samples, however, did not experience any significant chance, which was attributed to the compensation of the loss in the surface area by the alloy formation after the heat treatment.

  10. Effect of dissolved oxygen concentration on the bioflocculation process in high loaded MBRs.

    Science.gov (United States)

    Faust, L; Temmink, H; Zwijnenburg, A; Kemperman, A J B; Rijnaarts, H H M

    2014-12-01

    High-loaded membrane bioreactors (HL-MBRs), i.e. MBRs which are operated at extremely short sludge and hydraulic retention times, can be applied to flocculate and concentrate sewage organic matter. The concentrated organics can be used for energy recovery, or for the production of more valuable organic chemicals. Little is known about the effect of the dissolved oxygen concentration (DO) on this bioflocculation process. To examine this effect, two HL-MBRs were operated, respectively at a low (1 mg L(-1)) and a higher (4 mg L(-1)) DO. The higher DO resulted in a better flocculation efficiency, i.e. 92% of the colloidal COD in the sewage flocculated compared to 69% at the lower DO. The difference was attributed to a higher microbial production of extracellular polymeric substances at a DO of 4 mg L(-1) and to more multivalent cations (calcium, iron and aluminium) being distributed to the floc matrix. In addition, the HL-MBR that was operated at a DO of 4 mg L(-1) gave a bigger mean floc size, a lower supernatant turbidity, better settleability and better membrane filterability than the HL-MBR that was operated at a DO of 1 mg L(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Hydrogen production via sorption enhanced chemical looping reforming of glycerol using Ni-based oxygen carrier and Ca-based sorbent: Theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Wenju Wang [Nanjing University of Science and Technology, Nanjing (China)

    2014-02-15

    The sorption enhanced chemical looping reforming of glycerol (SECLRG) was proposed. This process can produce high purity H{sub 2} without need for additional gas separation equipment. Thermodynamic analysis on the reformer of SECLRG was conducted based on the minimization of Gibbs free energy. The results show that the favorable operation conditions for reformer are pressures around 1-20 atm, temperatures around 800 K, oxygen excess number of 1, and sorbent excess number of 1. The thermal efficiency with steam addition is higher than that without steam addition. The SECLRG was also examined in a fixed bed reactor, with NiO/Al{sub 2}O{sub 3} and CaO particles as bed material and glycerol as fuel. Experimental results showed that the H{sub 2} molar fraction was higher with CaO than without it. Initially, high purity hydrogen (>95%) was obtained by SECLR of glycerol at 800 K and 1 atm.

  12. Search for Fractionally Charged Nuclei in High-Energy Oxygen-Lead Collisions

    CERN Multimedia

    2002-01-01

    We propose to use stacks of CR-39 plastic track detectors to look for fractionally charged projectile fragments produced in collisions of high-energy oxygen, sulfur, and calcium nuclei with a lead target. The expected charge resolution is @s^z~=~0.06e for fragments with 17e/3~@$<$~Z~@$<$~23e/3. We request that two target + stack assemblies be exposed to 1~x~10|5 oxygen nuclei at maximum available energy.

  13. Combined Chemical Activation and Fenton Degradation to Convert Waste Polyethylene into High-Value Fine Chemicals.

    Science.gov (United States)

    Chow, Cheuk-Fai; Wong, Wing-Leung; Ho, Keith Yat-Fung; Chan, Chung-Sum; Gong, Cheng-Bin

    2016-07-04

    Plastic waste is a valuable organic resource. However, proper technologies to recover usable materials from plastic are still very rare. Although the conversion/cracking/degradation of certain plastics into chemicals has drawn much attention, effective and selective cracking of the major waste plastic polyethylene is extremely difficult, with degradation of C-C/C-H bonds identified as the bottleneck. Pyrolysis, for example, is a nonselective degradation method used to crack plastics, but it requires a very high energy input. To solve the current plastic pollution crisis, more effective technologies are needed for converting plastic waste into useful substances that can be fed into the energy cycle or used to produce fine chemicals for industry. In this study, we demonstrate a new and effective chemical approach by using the Fenton reaction to convert polyethylene plastic waste into carboxylic acids under ambient conditions. Understanding the fundamentals of this new chemical process provides a possible protocol to solve global plastic-waste problems.

  14. A highly accurate method for determination of dissolved oxygen: Gravimetric Winkler method

    Energy Technology Data Exchange (ETDEWEB)

    Helm, Irja; Jalukse, Lauri [University of Tartu, Institute of Chemistry, 14a Ravila str., 50411 Tartu (Estonia); Leito, Ivo, E-mail: ivo.leito@ut.ee [University of Tartu, Institute of Chemistry, 14a Ravila str., 50411 Tartu (Estonia)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer Probably the most accurate method available for dissolved oxygen concentration measurement was developed. Black-Right-Pointing-Pointer Careful analysis of uncertainty sources was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. Black-Right-Pointing-Pointer This development enables more accurate calibration of dissolved oxygen sensors for routine analysis than has been possible before. - Abstract: A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012-0.018 mg dm{sup -3} corresponding to the k = 2 expanded uncertainty in the range of 0.023-0.035 mg dm{sup -3} (0.27-0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.

  15. Non-equilibrium of high-temperature nitrogen and oxygen

    Science.gov (United States)

    Kunc, J. A.; Soon, W. H.

    1988-01-01

    A stationary colloidal-radiative model for determination of production of electrons, excited atoms, and spectral line intensities in high-temperature atomic N and O is presented. The populations of several atomic levels and partition functions, and the intensities of several lines, are calculated in a wide range of conditions. Transport of radiation is included by coupling the rate equations for production of the electrons and excited atoms with the Holstein escape factors which are not constant, but depend on plasma conditions.

  16. Chemical Diversity in High-Mass Star Formation

    CERN Document Server

    Beuther, H; Bergin, E A; Sridharan, T K

    2008-01-01

    Massive star formation exhibits an extremely rich chemistry. However, not much evolutionary details are known yet, especially at high spatial resolution. Therefore, we synthesize previously published Submillimeter Array high-spatial-resolution spectral line observations toward four regions of high-mass star formation that are in various evolutionary stages with a range of luminosities. Estimating column densities and comparing the spatially resolved molecular emission allows us to characterize the chemical evolution in more detail. Furthermore, we model the chemical evolution of massive warm molecular cores to be directly compared with the data. The four regions reveal many different characteristics. While some of them, e.g., the detection rate of CH3OH, can be explained by variations of the average gas temperatures, other features are attributed to chemical effects. For example, C34S is observed mainly at the core-edges and not toward their centers because of temperature-selective desorption and successive g...

  17. Oxygen Barrier Coating Deposited by Novel Plasma-enhanced Chemical Vapor Deposition

    DEFF Research Database (Denmark)

    Jiang, Juan; Benter, M.; Taboryski, Rafael Jozef

    2010-01-01

    We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source. This confi......, and it increased the barrier property of the modified low-density polyethylene, polyethylene terephthalate, and polylactide by 96.48%, 99.69%, and 99.25%, respectively....

  18. Chemical reactivity of hydrogen, nitrogen, and oxygen atoms at temperatures below 100 k

    Science.gov (United States)

    Mcgee, H. A., Jr.

    1973-01-01

    The synthesis of unusual compounds by techniques employing cryogenic cooling to retard their very extreme reactivity was investigated. Examples of such species that were studied are diimide (N2H2), cyclobutadiene (C4H4), cyclopropanone (C3H4O), oxirene (C2H2O), and many others. Special purpose cryogenically cooled inlet arrangements were designed such that the analyses incurred no warm-up of the cold, and frequently explosively unstable, compounds. Controlled energy electron impact techniques were used to measure critical potentials and to develop the molecular energetics and thermodynamics of these molecules and to gain some insight into their kinetic characteristics as well. Three and four carbon strained ring molecules were studied. Several reactions of oxygen and hydrogen atoms with simple molecules of H, N, C, and O in hard quench configurations were studied. And the quench stabilization of BH3 was explored as a model system in cryochemistry.

  19. High-valent iron in chemical and biological oxidations.

    Science.gov (United States)

    Groves, John T

    2006-04-01

    Various aspects of the reactivity of iron(IV) in chemical and biological systems are reviewed. Accumulated evidence shows that the ferryl species [Fe(IV)O](2+) can be formed under a variety of conditions including those related to the ferrous ion-hydrogen peroxide system known as Fenton's reagent. Early evidence that such a species could hydroxylate typical aliphatic C-H bonds included regioselectivities and stereospecificities for cyclohexanol hydroxylation that could not be accounted for by a freely diffusing hydroxyl radical. Iron(IV) porphyrin complexes are also found in the catalytic cycles of cytochrome P450 and chloroperoxidase. Model oxo-iron(IV) porphyrin complexes have shown reactivity similar to the proposed enzymatic intermediates. Mechanistic studies using mechanistically diagnostic substrates have implicated a radical rebound scenario for aliphatic hydroxylation by cytochrome P450. Likewise, several non-heme diiron hydroxylases, AlkB (Omega-hydroxylase), sMMO (soluble methane monooxygenase), XylM (xylene monooxygenase) and T4moH (toluene monooxygenase) all show clear indications of radical rearranged products indicating that the oxygen rebound pathway is a ubiquitous mechanism for hydrocarbon oxygenation by both heme and non-heme iron enzymes.

  20. The role of oxygen in yeast metabolism during high cell density brewery fermentations.

    Science.gov (United States)

    Verbelen, P J; Saerens, S M G; Van Mulders, S E; Delvaux, F; Delvaux, F R

    2009-04-01

    The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e., higher inoculum size). However, the decreased yeast net growth observed in these high cell density fermentations can have a negative impact on the physiological stability throughout subsequent yeast generations. The use of different oxygen conditions (wort aeration, wort oxygenation, yeast preoxygenation) was investigated to improve the growth yield during high cell density fermentations and yeast metabolic and physiological parameters were assessed systematically. Together with a higher extent of growth (dependent on the applied oxygen conditions), the fermentation power and the formation of unsaturated fatty acids were also affected. Wort oxygenation had a significant decreasing effect on the formation of esters, which was caused by a decreased expression of the alcohol acetyl transferase gene ATF1, compared with the other conditions. Lower glycogen and trehalose levels at the end of fermentation were observed in case of the high cell density fermentations with oxygenated wort and the reference fermentation. The expression levels of BAP2 (encoding the branched chain amino acid permease), ERG1 (encoding squalene epoxidase), and the stress responsive gene HSP12 were predominantly influenced by the high cell concentrations, while OLE1 (encoding the fatty acid desaturase) and the oxidative stress responsive genes SOD1 and CTT1 were mainly affected by the oxygen availability per cell. These results demonstrate that optimisation of high cell density fermentations could be achieved by improving the oxygen conditions, without drastically affecting the physiological condition of the yeast and beer quality.

  1. Non-equilibrium effects in high temperature chemical reactions

    Science.gov (United States)

    Johnson, Richard E.

    1987-01-01

    Reaction rate data were collected for chemical reactions occurring at high temperatures during reentry of space vehicles. The principle of detailed balancing is used in modeling kinetics of chemical reactions at high temperatures. Although this principle does not hold for certain transient or incubation times in the initial phase of the reaction, it does seem to be valid for the rates of internal energy transitions that occur within molecules and atoms. That is, for every rate of transition within the internal energy states of atoms or molecules, there is an inverse rate that is related through an equilibrium expression involving the energy difference of the transition.

  2. Novel fully-BODIPY functionalized cyclotetraphosphazene photosensitizers having high singlet oxygen quantum yields

    Science.gov (United States)

    Şenkuytu, Elif; Eçik, Esra Tanrıverdi

    2017-07-01

    Novel fully-BODIPY functionalized dendrimeric cyclotetraphosphazenes (FBCP 1 and 2) have been synthesized and characterized by 1H, 13C and 31P NMR spectroscopies. The photophysical and photochemical properties of FBCP 1 and 2 are investigated in dichloromethane solution. The effectiveness of singlet oxygen generation was measured for FBCP 1 and 2 by UV-Vis spectra monitoring of the solution of 1,3-diphenylisobenzofuran (DPBF), which is a well-known trapping molecule used in detection of singlet oxygen. FBCP 1 and 2 show high molar extinction coefficients in the NIR region, good singlet oxygen quantum yields and appropriate photo degradation. The data presented in the work indicate that the dendrimeric cyclotetraphosphazenes are effective singlet oxygen photosensitizers that might be used for various areas of applications such as photodynamic therapy and photocatalysis.

  3. The chemical shock tube as a tool for studying high-temperature chemical kinetics

    Science.gov (United States)

    Brabbs, Theodore A.

    1986-01-01

    Although the combustion of hydrocarbons is our primary source of energy today, the chemical reactions, or pathway, by which even the simplest hydro-carbon reacts with atmospheric oxygen to form CO2 and water may not always be known. Furthermore, even when the reaction pathway is known, the reaction rates are always under discussion. The shock tube has been an important and unique tool for building a data base of reaction rates important in the combustion of hydrocarbon fuels. The ability of a shock wave to bring the gas sample to reaction conditions rapidly and homogeneously makes shock-tube studies of reaction kinetics extremely attractive. In addition to the control and uniformity of reaction conditions achieved with shock-wave methods, shock compression can produce gas temperatures far in excess of those in conventional reactors. Argon can be heated to well over 10 000 K, and temperatures around 5000 K are easily obtained with conventional shock-tube techniques. Experiments have proven the validity of shock-wave theory; thus, reaction temperatures and pressures can be calculated from a measurement of the incident shock velocity. A description is given of the chemical shock tube and auxiliary equipment and of two examples of kinetic experiments conducted in a shock tube.

  4. High-Pressure Oxygen Generation for Outpost EVA

    Science.gov (United States)

    Jeng, Frank; Conger, Bruce; Anderson, Molly

    2008-01-01

    Low Lunar Orbit (LLO) poses unique thermal challenges for the orbiting space craft, particularly regarding the performance of the radiators. The emitted infrared (IR) heat flux from the lunar surface varies drastically from the light side to the dark side of the moon. Due to the extremely high incident IR flux, especially at low beta angles, a radiator is oftentimes unable to reject the vehicle heat load throughout the entire lunar orbit. One solution to this problem is to implement Phase Change Material (PCM) Heat Exchangers. PCM Heat Exchangers act as a "thermal capacitor, storing thermal energy when the radiator is unable to reject the required heat load. The stored energy is then removed from the PCM heat exchanger when the environment is more benign. Because they do not use an expendable resource, such as the feed water used by sublimators and evaporators, PCM Heat Exchangers are ideal for long duration Low Lunar Orbit missions. The Advanced Thermal Control project at JSC is completing a PCM heat exchanger life test to determine whether further technology development is warranted. The life test is being conducted on four nPentadecane, carbon filament heat exchangers. Fluid loop performance, repeatability, and measurement of performance degradation over 2500 meltfreeze cycles will be performed and reported in the current document.

  5. Synthesis gas production using oxygen storage materials as oxygen carrier over circulating fluidized bed

    Institute of Scientific and Technical Information of China (English)

    DAI Xiaoping; YU Changchun; LI Ranjia; WU Qiong; HAO Zhengping

    2008-01-01

    A novel process for synthesis gas production over Circulating Fluidized Bed (CFB) using oxygen storage materials as oxygen carrier was reported. First, oxygen in the air was chemically fixed and converted to lattice oxygen of oxygen storage materials over regenerator, and then methane was selectively oxidized to synthesis gas with lattice oxygen of oxygen storage materials over riser reactor. The results from simulation reaction of CFB by sequential redox reaction on a fixed bed reactor using lanthanum-based perovskite LaFeO3 and La0.8Sr0.2Fe0.9Co0.1O3 oxides prepared by sol-gel, suggested that the depleted oxygen species could be regenerated, and methane could be oxidized to synthesis gas by lattice oxygen with high selectivity. The partial oxidation of methane to synthesis gas over CFB using lattice oxygen of the oxygen storage materials instead of gaseous oxygen should be possibly applicable.

  6. Data acquisition and control system with a programmable logic controller (PLC) for a pulsed chemical oxygen-iodine laser

    Science.gov (United States)

    Yu, Haijun; Li, Guofu; Duo, Liping; Jin, Yuqi; Wang, Jian; Sang, Fengting; Kang, Yuanfu; Li, Liucheng; Wang, Yuanhu; Tang, Shukai; Yu, Hongliang

    2015-02-01

    A user-friendly data acquisition and control system (DACS) for a pulsed chemical oxygen -iodine laser (PCOIL) has been developed. It is implemented by an industrial control computer,a PLC, and a distributed input/output (I/O) module, as well as the valve and transmitter. The system is capable of handling 200 analogue/digital channels for performing various operations such as on-line acquisition, display, safety measures and control of various valves. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a PCOIL. The DACS system has been programmed using software programmable logic controller (PLC). Using this DACS, more than 200 runs were given performed successfully.

  7. Efficiency of some soil bacteria for chemical oxygen demand reduction of synthetic chlorsulfuron solutions under agiated culture conditions.

    Science.gov (United States)

    Erguven, G O; Yildirim, N

    2016-05-30

    This study searches the efficiency of certain soil bacteria on chemical oxygen demand (COD) reduction of synthetic chlorsulfuron solutions under agitated culture conditions. It also aims to determine the turbidity of liquid culture medium with chlorsulfuron during bacterial incubation for 120 hours. As a result the highest and lowest COD removal efficiency of bacteria was determined for Bacillus simplex as 94% and for Micrococcus luteus as 70%, respectively at the end of the 96th hour. It was found that COD removal efficiency showed certain differences depend on the bacterial species. It was also observed that B. simplex had the highest COD removal efficiency and it was a suitable bacterium species for bioremediation of a chlorsulfuron contaminated soils.

  8. Removal of color and chemical oxygen demand using a coupled coagulation-electrocoagulation-ozone treatment of industrial wastewater that contains offset printing dyes

    Energy Technology Data Exchange (ETDEWEB)

    Roa M, G.; Barrera D, C.; Balderas H, P.; Zaldumbide O, F. [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Km 14.5 Carretera Toluca-Atlacomulco, 50200 San Cayetano-Toluca, Estado de Mexico (Mexico); Reyes P, H. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Colon y Paseo Tollocan s/n, 50120 Toluca, Estado de Mexico (Mexico); Bilyeu, B., E-mail: groam@uaemex.mx [Xavier University of Louisiana, Department of Chemistry, 1 Drexel Drive, New Orleans, LA 70125 (United States)

    2014-07-01

    Industrial offset printing processes generate wastewater with highly colored obtaining values of 5 x 10{sup 6}Pt-Co units and great values of chemical oxygen demand (COD) 5.3 x 10{sup -5} mg L{sup -1}. Thus, conventional technologies such as biologicals treatment fail in reaching the discharge limits. In this research, a sequential treatment was applied: coagulation with aluminum hydroxychloride (AHC), electrocoagulation with Al anodes and finally ozonation. Optimal conditions are found when adding 20 mg L{sup -1} AHC, followed by electrocoagulation at 4 A for 50 min, and finally alkaline ozonation for 15 min, resulting in an overall color removal of 99.99% color and 99.35 COD. The sludge generated by the coagulation process was analyzed by scanning electron microscopy and energy dispersive X-ray (EDX) microanalysis. (Author)

  9. The chemical kinetics and thermodynamics of sodium species in oxygen-rich hydrogen flames

    Science.gov (United States)

    Hynes, A. J.; Steinberg, M.; Schofield, K.

    1984-01-01

    Results are presented which, it is claimed, lead to a correction of previous misconceptions over the relative importance and kinetics of NaO2. It is shown that its rapid conversion to NaO and NaOH is such that it can severely perturb the NaOH/Na ratio and produce significant concentration overshoots over that predicted from the balance of the reaction of Na with H2O. This becomes increasingly the case in flames of large O2 concentrations and temperatures below 2500 K; and the corresponding large rate constants for the termolecular formation of the other alkali peroxides imply that similar considerations will be necessary for them. Depending on the rate constants for the exothermic conversions of MO2 to MO or MOH, the steady-state concentrations of MO2 could be more or less significant than for sodium. Owing to numerous reactions that produce these conversions, the MOH species will probably be the dominant species in all cases in oxygen-rich hydrogen or hydrocarbon flames, with MO concentrations at not greater than 1 percent of the bound metal.

  10. Towards a better understanding of the origins, chemical composition and aging of oxygenated organic aerosols: case study of a Mediterranean industrialized environment, Marseille

    Directory of Open Access Journals (Sweden)

    I. El Haddad

    2013-08-01

    Full Text Available As part of the FORMES summer 2008 experiment, an Aerodyne compact time-of-flight aerosol mass spectrometer (cToF-AMS was deployed at an urban background site in Marseille to investigate the sources and aging of organic aerosols (OA. France's second largest city and the largest port in the Mediterranean, Marseille, provides a locale that is influenced by significant urban industrialized emissions and an active photochemistry with very high ozone concentrations. Particle mass spectra were analyzed by positive matrix factorization (PMF2 and the results were in very good agreement with previous apportionments obtained using a chemical mass balance (CMB approach coupled to organic markers and metals (El Haddad et al., 2011a. AMS/PMF2 was able to identify for the first time, to the best of our knowledge, the organic aerosol emitted by industrial processes. Even with significant industries in the region, industrial OA was estimated to contribute only ~ 5% of the total OA mass. Both source apportionment techniques suggest that oxygenated OA (OOA constitutes the major fraction, contributing ~ 80% of OA mass. A novel approach combining AMS/PMF2 data with 14C measurements was applied to identify and quantify the fossil and non-fossil precursors of this fraction and to explicitly assess the related uncertainties. Results show with high statistical confidence that, despite extensive urban and industrial emissions, OOA is overwhelmingly non-fossil, formed via the oxidation of biogenic precursors, including monoterpenes. AMS/PMF2 results strongly suggest that the variability observed in the OOA chemical composition is mainly driven in our case by the aerosol photochemical age. This paper presents the impact of photochemistry on the increase of OOA oxygenation levels, formation of humic-like substances (HULIS and the evolution of α-pinene SOA (secondary OA components.

  11. Evaluation of intramuscular butorphanol, azaperone, and medetomidine and nasal oxygen insufflation for the chemical immobilization of white-tailed deer, Odocoileus virginianus.

    Science.gov (United States)

    Mich, Patrice M; Wolfe, Lisa L; Sirochman, Tracey M; Sirochman, Michael A; Davis, Tracy R; Lance, William R; Miller, Michael W

    2008-09-01

    Chemical immobilization of wildlife often includes opioids or cyclohexamines. These substances are problematic as a result of their required storage, handling, and record-keeping protocols. A potentially useful alternative sedation protocol includes a combination of butorphanol, azaperone, and medetomidine (BAM: 0.43 mg/kg butorphanol, 0.36 mg/kg azaperone, 0.14 mg/kg medetomidine). One risk of wildlife immobilization with any drug combination is hypoxemia. This may be of particular importance when using an alpha 2 agonist such as medetomidine because of its powerful vasoconstrictive effect. In this prospective study, the BAM combination was evaluated for chemical immobilization of white-tailed deer. Additionally, selected physiologic parameters associated with BAM immobilization, including oxygen saturation via pulse oximetry and arterial blood gas measurement, with and without nasal insufflation of oxygen at a relatively low flow of 3 L/min, were evaluated. The BAM combination resulted in a predictable onset of sedation, with a mean induction time to lateral recumbency of 9.8 +/- 3.6 min. All deer recovered smoothly within a range of 5-20 min after reversal with intramuscular administration of naltrexone, atipamazole, and tolazoline (NAT). Clinically relevant decreases in arterial partial pressure of oxygen (PaO2) and oxygen saturation (SpO2) were observed in animals not receiving supplemental oxygen, while both parameters significantly improved for oxygen-supplemented deer. Pulse oximetry with this protocol was an unreliable indicator of oxygen saturation. In this study, altitude, recumbency, hypoventilation, butorphanol- and medetomidine-specific effects, as well as the potential for alpha 2 agonist-induced pulmonary changes all may have contributed to the development of hypoxemia. Overall, capture of white-tailed deer with the BAM/NAT protocol resulted in excellent chemical immobilization and reversal. Because the BAM combination caused significant hypoxemia

  12. Bosch Reactor Development for High Percentage Oxygen Recovery from Carbon Dioxide

    Science.gov (United States)

    Howard, David; Abney, Morgan

    2015-01-01

    This next Generation Life Support Project entails the development and demonstration of Bosch reaction technologies to improve oxygen recovery from metabolically generated oxygen and/or space environments. A primary focus was placed on alternate carbon formation reactor concepts to improve useful catalyst life for space vehicle applications, and make use of in situ catalyst resources for non-terrestrial surface missions. Current state-of-the-art oxygen recovery systems onboard the International Space Station are able to effectively recover approximately 45 percent of the oxygen consumed by humans and exhausted in the form of carbon dioxide (CO2). Excess CO2 is vented overboard and the oxygen contained in the molecules is lost. For long-duration missions beyond the reaches of Earth for resupply, it will be necessary to recover greater amounts of constituents such as oxygen that are necessary for sustaining life. Bosch technologies theoretically recover 100 percent of the oxygen from CO2, producing pure carbon as the sole waste product. Challenges with this technology revolve around the carbon product fouling catalyst materials, drastically limiting catalyst life. This project successfully demonstrated techniques to extend catalyst surface area exposure times to improve catalyst life for vehicle applications, and demonstrated the use of Martian and lunar regolith as viable catalyst Bosch Reactor Development for High Percentage Oxygen Recovery From Carbon Dioxide materials for surface missions. The Bosch process generates carbon nanotube formation within the regolith, which has been shown to improve mechanical properties of building materials. Production of bricks from post reaction regolith for building and radiation shielding applications were also explored.

  13. Pd-Pt Alloy with Coral-Like Nanostructures Showing High Performance for Oxygen Electrocatalytic Reduction.

    Science.gov (United States)

    Liu, Xing-Quan; Chen, Xue-Song; Wu, Jian; Yao, Lei

    2016-03-01

    Three-dimensional (3D) Pd-Pt alloy with coral-like nanostructures were synthesized via bubble dynamic templated electrodeposition method at room temperature. The morphology of the as-prepared nanostructures was characterized using scanning electron microscopy (SEM), EDS, high-resolution transmission electron microscopy (HRTEM), respectively. Cyclic voltammetry method was adopted to evaluate the electrocatalytic activities of the synthesized electrodes toward oxygen reduction in KCl solution. The electrochemical results indicated that the Pd-Pt alloy with coral-like nanostructures hold the high performance for oxygen reduction.

  14. The Development of a Method to Extract High Purity Oxygen From the Martian Atmosphere

    Science.gov (United States)

    Wu, Dongchuan

    1994-01-01

    controlled and therefore proportional to the reciprocal of the membrane thickness. Supported pin hole free Ag membranes with thicknesses of 12 micro m have been developed in this work. Furthermore, a pin hole free Ag membrane that was grown by a combination of Ar ion bombardment assisted physical vapor deposition and intermediate burnishing with a thickness less than 1 micro m is being developed which will substantially improve the oxygen flux level. Thickness of 1 micro m will permit flux levels of at least 106 molecules/cm2s. With this flux level, less than 1.5 m2 membrane surface area would be needed to support an astronaut on a continual basis on the Mars surface. The results of this work show that this approach of producing oxygen from the CO2 Martian atmosphere can eliminate mechanical filtration, compression and high temperature heating of the Mars atmosphere proposed previously by electrochemical methods.

  15. Effect of Ash on Oxygen Carriers for the Application of Chemical Looping Combustion to a High Carbon Char Effet des cendres sur l’activité des porteurs d’oxygène dans la combustion du charbon en boucle chimique

    Directory of Open Access Journals (Sweden)

    Rubel A.

    2011-02-01

    Full Text Available The application of Chemical Looping Combustion (CLC to solid fuels is being investigated at the University of Kentucky, Center for Applied Energy Research (CAER with the aim of the development of a Pressurized Chemical Looping Combustion/Gasification (PCLC/G process for the generation of electricity from coal. One important aspect of the CLC of solid fuel is the understanding of the effect of ash on the reactivity of Oxygen Carriers (OCs. The effect of ash on the redox capabilities of two different iron oxide OCs and on their ability to oxidize coal char was studied. To determine the effect of ash on the reactivity and recycle of the OCs through multiple redox cycles, fly ash from a coal-fired power plant was used. These experiments were performed in a TGMS system using 500 mg of ash/OC mixtures containing different ash concentrations up to 75%. The reducing gas was composed of 10% H2, 15% CO, 20% CO2, and a balance of Ar and the oxidizing gas was 20% O2 in Ar. Oxidation/reductions were carried to near completion. The ash was found to contain OC activity related to inherent iron present in the ash confirmed by XRD. This resulted in increased weight gain/loss on oxidation/reduction. The rate of oxidation/reduction increased with ash concentration due to increased porosity of the OC/ash mixture and better access of the reactive gases to the OC target sites. The two OCs were then used to combust a beneficiated coal char in the TGMS with the only oxygen supplied by an iron oxide OC. The starting mixture was 10% char and 90% of one of two OCs studied. The spent material containing reduced OC and ash was re-oxidized and 10% more char was added for a second reduction of the OC and oxidation of the added char. This procedure was repeated for 5 cycles increasing the ash concentrations from 5 to 25% in the char/ash/OC mixture. Carbon removal was 92 to 97.8 and 97.3 to 99.7% for the two different iron oxide OCs tested. Ash was not detrimental to the

  16. Technologies of oxygen supply for life support during the development of mineral resources in high altitude areas

    Institute of Scientific and Technical Information of China (English)

    Liu Yingshu; Jia Yanxiang; Wu Tianyi; Deng Ling; Yang Xiong; Liu Wenhai; Zhang Hui

    2013-01-01

    In order to fulfill the needs of life-support oxygen supply during the development of plateau mineral resources,four oxygen supply patterns suitable for the plateau mine in specific environment were developed:tunnel face diffusive oxygen supply,tunnel oxygen-bar car,carried oxygen cylinder and portable oxygen generator.Through the study of safety oxygen supply experiments in low-pressure plateau areas,the mathematical relationship between maximum integration of secure oxygen volume and altitude has been achieved.Oxygen supply safety control should follow this relationship in plateau mines during the time of executing tunnel face or in room air diffusive oxygen supply.The application results of life-support oxygen supplement technologies in the development of mineral resources in high altitude areas show that the oxygen supply for tunneling miners in plateau mines can not only effectively enhance the oxygen saturation,reduce the pulse rate and the breath rate per minute,but also improve various symptoms caused by altitude hypoxia and high-intensity physical labor.

  17. Blood flow regulation and oxygen uptake during high intensity forearm exercise.

    Science.gov (United States)

    Nyberg, Stian Kwak; Berg, Ole Kristian; Helgerud, Jan; Wang, Eivind

    2017-01-05

    The vascular strain is very high during heavy handgrip exercise, but the intensity and kinetics to reach peak blood flow, and peak oxygen uptake, are uncertain. We included 9 young (25±2yr) healthy males to evaluate blood flow and oxygen uptake responses during continuous dynamic handgrip exercise with increasing intensity. Blood flow was measured using Doppler-ultrasound and venous blood was drawn from a deep forearm vein to determine arteriovenous oxygen difference (a-vO2diff) during 6-minutes bouts of 60, 80 and 100% of maximal work rate (WRmax), respectively. Blood flow and oxygen uptake increased (pBlood velocity (49.5±11.5 cm∙sec(-1) to 58.1±11.6 cm∙sec(-1)) and brachial diameter (0.49±0.05cm to 0.50±0.06 cm) showed concomitant increases (pblood flow from 60% to 80%WRmax, while no differences were observed in a-vO2diff Shear rate also increased (pblood flow (60%WRmax:50±22s; 80%WRmax:51±20s; 100%WRmax:51±23s) than a-vO2diff (60%WRmax:29±9s; 80%WRmax:29±5s; 100%WRmax:20±5s), but not different from oxygen uptake (60%WRmax:44±25s; 80%WRmax:43±14s; 100%WRmax:41±32s). No differences were observed in MRT for blood flow or oxygen uptake with increased exercise intensity. In conclusion, when approaching maximal intensity, oxygen uptake appeared to reach a critical level at ~80% of WRmax and be regulated by blood flow. This implies that high, but not maximal, exercise intensity may be an optimal stimulus for shear stress-induced small muscle mass training adaptations.

  18. A strategy for reducing neonatal mortality at high altitude using oxygen conditioning.

    Science.gov (United States)

    West, J B

    2015-11-01

    Neonatal mortality increases with altitude. For example, in Peru the incidence of neonatal mortality in the highlands has been shown to be about double that at lower altitudes. An important factor is the low inspired PO2 of newborn babies. Typically, expectant mothers at high altitude will travel to low altitude to have their babies if possible, but often this is not feasible because of economic factors. The procedure described here raises the oxygen concentration in the air of rooms where neonates are being housed and, in effect, this means that both the mother and baby are at a much lower altitude. Oxygen conditioning is similar to air conditioning except that the oxygen concentration of the air is increased rather than the temperature being reduced. The procedure is now used at high altitude in many hotels, dormitories and telescope facilities, and has been shown to be feasible and effective.

  19. The effects of high perioperative inspiratory oxygen fraction for adult surgical patients

    DEFF Research Database (Denmark)

    Wetterslev, Jørn; Meyhoff, Christian S; Jørgensen, Lars N

    2015-01-01

    BACKGROUND: Available evidence on the effects of a high fraction of inspired oxygen (FIO2) of 60% to 90% compared with a routine fraction of inspired oxygen of 30% to 40%, during anaesthesia and surgery, on mortality and surgical site infection has been inconclusive. Previous trials and meta......-analyses have led to different conclusions on whether a high fraction of supplemental inspired oxygen during anaesthesia may decrease or increase mortality and surgical site infections in surgical patients. OBJECTIVES: To assess the benefits and harms of an FIO2 equal to or greater than 60% compared...... with a control FIO2 at or below 40% in the perioperative setting in terms of mortality, surgical site infection, respiratory insufficiency, serious adverse events and length of stay during the index admission for adult surgical patients.We looked at various outcomes, conducted subgroup and sensitivity analyses...

  20. Escape of high-energy oxygen ions through magnetopause reconnection under northward IMF

    Directory of Open Access Journals (Sweden)

    S. Kasahara

    2008-12-01

    Full Text Available During a storm recovery phase on 15 May 2005, the Geotail spacecraft repeatedly observed high-energy (>180 keV oxygen ions in the dayside magnetosheath near the equatorial plane. We focused on the time period from 11:20 UT to 13:00 UT, when Geotail observed the oxygen ions and the interplanetary magnetic field (IMF was constantly northward. The magnetic reconnection occurrence northward and duskward of Geotail is indicated by the Walén analysis and convective flows in the magnetopause boundary layer. Anisotropic pitch angle distributions of ions suggest that high-energy oxygen ions escaped from the northward of Geotail along the reconnected magnetic field lines. From the low-energy particle precipitation in the polar cap observed by DMSP, which is consistent with magnetic reconnection occurring between the magnetosheath field lines and the magnetospheric closed field lines, we conclude that these oxygen ions are of ring current origin. Our results thus suggest a new escape route of oxygen ions during northward IMF. In the present event, this escape mechanism is more dominant than the leakage via the finite Larmor radius effect across the dayside equatorial magnetopause.

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

    Science.gov (United States)

    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.

  2. Chemical Evolution of the Galactic Bulge as Derived from High-Resolution Infrared Spectroscopy of K and M Red Giants

    CERN Document Server

    Cunha, K; Cunha, Katia; Smith, Verne V.

    2006-01-01

    We present chemical abundances in K and M red-giant members of the Galactic bulge derived from high-resolution infrared spectra obtained with the Phoenix spectrograph on Gemini-South. The elements studied are carbon, nitrogen, oxygen, sodium, titanium, and iron. The evolution of C and N abundances in the studied red-giants show that their oxygen abundances represent the original values with which the stars were born. Oxygen is a superior element for probing the timescale of bulge chemical enrichment via [O/Fe] versus [Fe/H]. The [O/Fe]-[Fe/H] relation in the bulge does not follow the disk relation, with [O/Fe] values falling above those of the disk. Titanium also behaves similarly to oxygen with respect to iron. Based on these elevated values of [O/Fe] and [Ti/Fe] extending to large Fe abundances, it is suggested that the bulge underwent a more rapid chemical enrichment than the halo. In addition, there are declines in both [O/Fe] and [Ti/Fe] in those bulge targets with the largest Fe abundances, signifying a...

  3. Chemical characterization of selected high copper dental amalgams using XPS and XRD techniques

    Energy Technology Data Exchange (ETDEWEB)

    Talik, E. [A. Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)]. E-mail: talik@us.edu.pl; Babiarz-Zdyb, R. [A. Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Dziedzic, A. [Medical University of Silesia, Department of Conservative Dentistry and Periodontology, Akademicki 17 Sqr., 41-209 Bytom (Poland)

    2005-08-02

    The study was carried out to analyze some dependencies between the composition of seven high copper dental amalgams and mercury release behavior, as well as oxygen reactivity of metallic elements. Chemical comparative analysis of selected dental amalgams was carried out using X-ray photoelectron spectroscopy (XPS) technique and X-ray diffraction (XRD) method. The X-ray powder diffraction measurements revealed two main phases for measured amalgams: {gamma}{sub 1}-(Ag{sub 2}Hg{sub 3}) and {eta}'-(Cu{sub 6}Sn{sub 5}). The amount of mercury obtained by the XPS method was lower than the value quoted in the manufacturer's literature, which suggested evaporation of mercury under the UHV conditions. A linear decrease of oxygen and carbon contamination with the growing amount of Cu and Ag was observed. The XPS analysis showed that a high Sn concentration caused less resistance to oxidation. Some of the amalgams contained some extra elements, such as Bi, In, and Zn. All samples contained lead in metallic state and oxides. The amount of Ag, Cu, Sn ingredients determines the main properties of high copper amalgams and plays an important role in mercury evaporation. High tin concentration combined with the presence of smaller amounts of silver and copper (high Sn/Ag ratio) may influence the increase of mercury vaporization.

  4. Generation of highly reactive oxygen species by co-adsorption of oxygen and water on metal-supported MgO(100) thinfilms

    CERN Document Server

    Song, Zhenjun

    2015-01-01

    The formation of highly reactive oxygen species (ROS) on metal oxide surfaces have attracted considerable interest due to their diverse applications. In this work, we have performed densi-ty-functional theory calculations to investigate the co-adsorption of oxygen and water on ul-trathin MgO(100) films deposited on Mo(100) substrate. We reveal that the molecular oxygen can be stepwise decomposed completely with the assistance of water. Consequently, a series of highly ROS including superoxide, hydroperoxide, hydroxyl and single oxygen adatom are formed on Mo(100) supported MgO(100) thinfilms. The reaction barriers accompanied by the generation of ROS are reported, and the influence of the thickness of MgO(100) films is also discussed. The most promising routes to produce these fascinating species provide valuable information to understand the importance of synergistic effect, namely the substrate, the co-adorbed species, and the film thickness, in multiphase catalyst design.

  5. High intensity aerobic interval training improves peak oxygen consumption in patients with metabolic syndrome: CAT

    Directory of Open Access Journals (Sweden)

    Alexis Espinoza Salinas

    2014-06-01

    Full Text Available Introduction A number of cardiovascular risk factors characterizes the metabolic syndrome: insulin resistance (IR, low HDL cholesterol and high triglycerides. The aforementioned risk factors lead to elevated levels of abdominal adipose tissue, resulting in oxygen consumption deficiency. Purpose To verify the validity and applicability of using high intensity interval training (HIIT in subjects with metabolic syndrome and to answer the following question: Can HIIT improve peak oxygen consumption? Method The systematic review "Effects of aerobic interval training on exercise capacity and metabolic risk factors in individuals with cardiometabolic disorders" was analyzed. Results Data suggests high intensity aerobic interval training increases peak oxygen consumption by a standardized mean difference of 3.60 mL/kg-1/min-1 (95% confidence interval, 0.28-4.91. Conclusion In spite of the methodological shortcomings of the primary studies included in the systematic review, we reasonably conclude that implementation of high intensity aerobic interval training in subjects with metabolic syndrome, leads to increases in peak oxygen consumption.

  6. Luminescent metal-organic framework films as highly sensitive and fast-response oxygen sensors.

    Science.gov (United States)

    Dou, Zhongshang; Yu, Jiancan; Cui, Yuanjing; Yang, Yu; Wang, Zhiyu; Yang, Deren; Qian, Guodong

    2014-04-16

    Luminescent metal-organic framework films, CPM-5⊃Tb(3+) and MIL-100(In)⊃Tb(3+), have been constructed by postfunctionalization of two porous indium-organic frameworks with different structures, respectively. The MIL-100(In)⊃Tb(3+) film shows high oxygen sensitivity (KSV = 7.59) and short response/recovery time (6 s/53 s).

  7. Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

    DEFF Research Database (Denmark)

    Hvelplund, P; Nielsen, SB; Sørensen, M

    2001-01-01

    We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge stat...

  8. Stoichiometric SrTiO3 Films via High Pressure Oxygen Sputter Deposition

    Science.gov (United States)

    Ambwani, Palak; Jalan, Bharat; Leighton, Chris

    2013-03-01

    Defect management in epilayers of semiconducting complex oxides such as SrTiO3 is a topic of considerable contemporary interest. Recent work has shown that sufficiently precise control over stoichiometry and defects in SrTiO3 enables facile n-type doping, record high mobilities, and even simultaneous observation of quantum oscillations and superconductivity. Such progress has typically been made using techniques such as oxygen/LASER MBE or high-temperature PLD. In this work we demonstrate, via homoepitaxy on SrTiO3(001), that RF high pressure oxygen sputtering from a ceramic target is similarly capable of growth of high-quality, stoichiometric SrTiO3 films. We show that optimization of the deposition temperature (above 750 °C) and oxygen pressure (above 2.5 mBar) leads to the deposition of films indistinguishable from the substrate via grazing incidence and wide-angle x-ray scattering. The importance of a pre-treatment of the substrates in oxygen above 900 °C is emphasized. The defect density/stoichiometry was further probed via the transport properties of vacuum annealed samples with controlled O vacancy density. Finally, we also demonstrate that the stoichiometry and defect density of films deposited under non-optimal conditions can be remarkably improved via post-deposition heat treatment. Work supported by NSF DMR and NSF MRSEC.

  9. A high-input impedance differential millivolt meter for use with solid ceramic oxygen electrolyte cells

    Science.gov (United States)

    Williams, R. J.; Mullins, O.; Quin, E.

    1975-01-01

    Design factors are given for a high-input impedance differential millivolt meter designed, built, and tested as an inexpensive solid-state electronic system for use in measuring the electromotive force from solid ceramic oxygen electrolyte cells. A schematic diagram is included.

  10. The significance of the activity of dissolved oxygen, and other gases, enhanced by high hydrostatic pressure.

    Science.gov (United States)

    Ludwig, Horst; Macdonald, Alister G

    2005-04-01

    The partial pressure of oxygen and other gases dissolved in water and subjected to high hydrostatic pressure is increased. Although this was established many years ago it remains a problematical phenomenon. The review deals with some of the underlying theoretical difficulties and discusses the kinetic and environmental implications of the pressure-enhanced partial pressures.

  11. Crack Growth of D6 Steel in Air and High Pressure Oxygen

    Science.gov (United States)

    Bixler, W. D.; Engstrom, W. L.

    1971-01-01

    Fracture and subcritical flaw growth characteristics were experimentally deter­mined for electroless nickel plated D6 steel in dry air and high pressure oxygen environments as applicable to the Lunar Module/Environmental Control System (LM/ECS) descent gaseous oxygen (GOX) tank. The material tested included forgings, plate, and actual LM/ECS descent GOX tank material. Parent metal and TIG (tungsten inert gas) welds were tested. Tests indicate that proof testing the tanks at 4000 pounds per square inch or higher will insure safe operation at 3060 pounds per square inch. Although significant flaw growth can occur during proofing, subsequent growth of flaws during normal tank operation is negligible.

  12. Prediction of oxygen solubility in pure water and brines up to high temperatures and pressures

    Science.gov (United States)

    GENG, Ming; DUAN, Zhenhao

    2010-10-01

    A thermodynamic model is presented to calculate the oxygen solubility in pure water (273-600 K, 0-200 bar) and natural brines containing Na +, K +, Ca 2+, Mg 2+, Cl -, SO 42-, over a wide range of temperature, pressure and ionic strength with or close to experimental accuracy. This model is based on an accurate equation of state to calculate vapor phase chemical potential and a specific particle interaction model for liquid phase chemical potential. With this approach, the model can not only reproduce the existing experimental data, but also extrapolate beyond the data range from simple aqueous salt system to complicated brine systems including seawater. Compared with previous models, this model covers much wider temperature and pressure space in variable composition brine systems. A program for this model can be downloaded from the website: http://www.geochem-model.org.

  13. A highly accurate method for determination of dissolved oxygen: gravimetric Winkler method.

    Science.gov (United States)

    Helm, Irja; Jalukse, Lauri; Leito, Ivo

    2012-09-05

    A high-accuracy Winkler titration method has been developed for determination of dissolved oxygen concentration. Careful analysis of uncertainty sources relevant to the Winkler method was carried out and the method was optimized for minimizing all uncertainty sources as far as practical. The most important improvements were: gravimetric measurement of all solutions, pre-titration to minimize the effect of iodine volatilization, accurate amperometric end point detection and careful accounting for dissolved oxygen in the reagents. As a result, the developed method is possibly the most accurate method of determination of dissolved oxygen available. Depending on measurement conditions and on the dissolved oxygen concentration the combined standard uncertainties of the method are in the range of 0.012-0.018 mg dm(-3) corresponding to the k=2 expanded uncertainty in the range of 0.023-0.035 mg dm(-3) (0.27-0.38%, relative). This development enables more accurate calibration of electrochemical and optical dissolved oxygen sensors for routine analysis than has been possible before.

  14. Oxygen Permeation Behaviors and Hardening Effect of Titanium Alloys at High Temperature

    Institute of Scientific and Technical Information of China (English)

    Hongyan MA; Maocai WANG; Weitao WU

    2004-01-01

    In order to improve the surface hardness and wear resistance of Ti and Ti alloy components, an oxygen permeationtreatment (OPT) was developed. The oxygen permeation behaviors of three Ti alloys, TA2, TB5 and TC11, treatedin air with O-P medium at high temperature have been studied. The results show that the O-P treatment cansignificantly improve the surface hardness of Ti alloys. The oxidation mass-gain of β-Ti alloy (TB5) is much higherthan α-Ti alloy (TA2) under the same condition, while α+β Ti alloy (TC11) is the lowest. All the Ti alloys treatedat this condition produce two surface layers: the outer layer consists mainly of TiO2, as well as trace of other oxides,and the inner layer consists of a Ti-O interstitial solid solution formed by the diffusion of oxygen in α crystal latticeThick scales of β Ti alloy (TB5) are easily formed depending mainly on the poor solid solution content of oxygen,while deep solution layer can be formed since partial β phase has been transformed into α phase. The scales of α-βTi alloy (TC11) are very thin and compact. Aluminum-rich zone, as well as deficient zone, is found in oxide layerrs.A crystallographic characterization of oxygen solution layer has been performed and evaluated by crystallographiclattice constant.

  15. In vacuo reduction of silver orthophosphate with graphite for high-precision oxygen isotope analysis.

    Science.gov (United States)

    Pelc, Andrzej; Halas, Stanislaw

    2010-10-15

    The reduction of silver phosphate with graphite under vacuum conditions was studied at final reaction temperatures varying from 430 to 915°C to determine: (i) the CO(2) extraction yield, and (ii) the oxygen isotopic composition of CO(2). The CO(2) yield and oxygen isotopic composition were determined on a calibrated dual inlet and triple collector isotope ratio mass spectrometer. We observed the following three stages of the reduction process. (1) At temperatures below 590°C only CO(2) is formed, while silver orthophosphate decays to pyrophosphate. (2) At higher temperatures, 590-830°C, predominantly CO is formed from silver pyrophosphate which decays to metaphosphate; this CO was always converted into CO(2) by the glow discharge method. (3) At temperatures above 830°C the noticeable sublimation of silver orthophosphate occurs. This observation was accompanied by the oxygen isotope analysis of the obtained CO(2). The measured δ(18)O value varied from -11.93‰ (at the lowest temperature) to -20.32‰ (at the highest temperature). The optimum reduction temperature range was found to be 780-830°C. In this temperature range the oxygen isotopic composition of CO(2) is nearly constant and the reaction efficiency is relatively high. The determined difference between the δ(18)O value of oxygen in silver phosphate and that in CO(2) extracted from this phosphate is +0.70‰. Copyright © 2010 John Wiley & Sons, Ltd.

  16. A high flux pulsed source of energetic atomic oxygen. [for spacecraft materials ground testing

    Science.gov (United States)

    Krech, Robert H.; Caledonia, George E.

    1986-01-01

    The design and demonstration of a pulsed high flux source of nearly monoenergetic atomic oxygen are reported. In the present test setup, molecular oxygen under several atmospheres of pressure is introduced into an evacuated supersonic expansion nozzle through a pulsed molecular beam valve. A 10J CO2 TEA laser is focused to intensities greater than 10 to the 9th W/sq cm in the nozzle throat, generating a laser-induced breakdown with a resulting 20,000-K plasma. Plasma expansion is confined by the nozzle geometry to promote rapid electron-ion recombination. Average O-atom beam velocities from 5-13 km/s at fluxes up to 10 to the 18th atoms/pulse are measured, and a similar surface oxygen enrichment in polyethylene samples to that obtained on the STS-8 mission is found.

  17. Friction-induced ignition of metals in high-pressure oxygen

    Science.gov (United States)

    Schoenman, Len; Stoltzfus, Joel; Kazaroff, John

    1988-01-01

    Data are presented on friction-induced metal ignition (such as occurring as a result of the possible rubbing of oxygen-pressurized hydrostatic bearings and turbine blade tips) in a high-presure oxygen environment. Friction heating tests were carried out at oxygen pressures from 1 to 300 atm and surface speeds from 10 to 33 m/sec, using the NASA/White Sands Test Facility. Test results are presented on the rubbing of like material pairs spanning a wide range of burn factors and on that of dissimilar metal pairs having significantly different burn factors, indicating that the burn factor is a suitable index for rank ordering in ignition resistance for the most, but not all, materials.

  18. QCD Effective action at high temperature and small chemical potential

    CERN Document Server

    Villavicencio, C

    2007-01-01

    We present a construction of an effective Yang-Mills action for QCD, from the expansion of the fermionic determinant in terms of powers of the chemical potential at high temperature, for the case of massless quarks. We analyze this expansion in the perturbative region and find that it gives extra spurious information. We propose for the non-perturbative sector a simplified effective action which, in principle, contains only the relevant information.

  19. High Performance Electrocatalytic Reaction of Hydrogen and Oxygen on Ruthenium Nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Ruquan; Liu, Yuanyue; Peng, Zhiwei; Wang, Tuo; Jalilov, Almaz S.; Yakobson, Boris I.; Wei, Su-Huai; Tour, James M.

    2017-01-18

    The development of catalytic materials for the hydrogen oxidation, hydrogen evolution, oxygen reduction or oxygen evolution reactions with high reaction rates and low overpotentials are key goals for the development of renewable energy. We report here Ru(0) nanoclusters supported on nitrogen-doped graphene as high-performance multifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), showing activities similar to that of commercial Pt/C in alkaline solution. For HER performance in alkaline media, sample Ru/NG-750 reaches 10 mA cm-2 at an overpotential of 8 mV with a Tafel slope of 30 mV dec-1. The high HER performance in alkaline solution is advantageous because most catalysts for ORR and oxygen evolution reaction (OER) also prefer alkaline solution environment whereas degrade in acidic electrolytes. For ORR performance, Ru/NG effectively catalyzes the conversion of O2 into OH- via a 4e process at a current density comparable to that of Pt/C. The unusual catalytic activities of Ru(0) nanoclusters reported here are important discoveries for the advancement of renewable energy conversion reactions.

  20. Effects of anesthetic agents on brain blood oxygenation level revealed with ultra-high field MRI.

    Directory of Open Access Journals (Sweden)

    Luisa Ciobanu

    Full Text Available During general anesthesia it is crucial to control systemic hemodynamics and oxygenation levels. However, anesthetic agents can affect cerebral hemodynamics and metabolism in a drug-dependent manner, while systemic hemodynamics is stable. Brain-wide monitoring of this effect remains highly challenging. Because T(2*-weighted imaging at ultra-high magnetic field strengths benefits from a dramatic increase in contrast to noise ratio, we hypothesized that it could monitor anesthesia effects on brain blood oxygenation. We scanned rat brains at 7T and 17.2T under general anesthesia using different anesthetics (isoflurane, ketamine-xylazine, medetomidine. We showed that the brain/vessels contrast in T(2*-weighted images at 17.2T varied directly according to the applied pharmacological anesthetic agent, a phenomenon that was visible, but to a much smaller extent at 7T. This variation is in agreement with the mechanism of action of these agents. These data demonstrate that preclinical ultra-high field MRI can monitor the effects of a given drug on brain blood oxygenation level in the absence of systemic blood oxygenation changes and of any neural stimulation.

  1. Conductor of high electrical current at high temperature in oxygen and liquid metal environment

    Energy Technology Data Exchange (ETDEWEB)

    Powell, IV, Adam Clayton; Pati, Soobhankar; Derezinski, Stephen Joseph; Lau, Garrett; Pal, Uday B.; Guan, Xiaofei; Gopalan, Srikanth

    2016-01-12

    In one aspect, the present invention is directed to apparatuses for and methods of conducting electrical current in an oxygen and liquid metal environment. In another aspect, the invention relates to methods for production of metals from their oxides comprising providing a cathode in electrical contact with a molten electrolyte, providing a liquid metal anode separated from the cathode and the molten electrolyte by a solid oxygen ion conducting membrane, providing a current collector at the anode, and establishing a potential between the cathode and the anode.

  2. Quality improvement in determination of chemical oxygen demand in samples considered difficult to analyze, through participation in proficiency-testing schemes

    DEFF Research Database (Denmark)

    Raposo, Francisco; Fernández-Cegrí, V.; De la Rubia, M.A.

    2010-01-01

    Chemical oxygen demand (COD) is a critical analytical parameter in waste and wastewater treatment, more specifically in anaerobic digestion, although little is known about the quality of measuring COD of anaerobic digestion samples. Proficiency testing (PT) is a powerful tool that can be used...

  3. Screening of NiFe2O4 Nanoparticles as Oxygen Carrier in Chemical Looping Hydrogen Production

    DEFF Research Database (Denmark)

    Liu, Shuai; He, Fang; Huang, Zhen

    2016-01-01

    The objective of this paper is to systematically investigate the influences of different preparation methods on the properties of NiFe2O4 nanoparticles as oxygen carrier in chemical looping hydrogen production (CLH). The solid state (SS), coprecipitation (CP), hydrothermal (HT), and sol-gel (SG...

  4. Supplemental Perioperative Oxygen to Reduce Surgical Site Infection After High Energy Fracture Surgery

    Science.gov (United States)

    2015-10-01

    1 AWARD NUMBER: W81XWH-12-1-0588 TITLE: Supplemental Perioperative Oxygen to Reduce Surgical Site Infection After High Energy Fracture Surgery...Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding...Site Infection After High Energy Fracture Surgery 5a. CONTRACT NUMBER W81XWH-12-1-0588 5b. GRANT NUMBER OR110123 5c. PROGRAM ELEMENT NUMBER 6

  5. Triple oxygen isotopic composition of the high-3He/4He mantle

    Science.gov (United States)

    Starkey, N. A.; Jackson, C. R. M.; Greenwood, R. C.; Parman, S.; Franchi, I. A.; Jackson, M.; Fitton, J. G.; Stuart, F. M.; Kurz, M.; Larsen, L. M.

    2016-03-01

    Measurements of Xe isotope ratios in ocean island basalts (OIB) suggest that Earth's mantle accreted heterogeneously, and that compositional remnants of accretion are sampled by modern, high-3He/4He OIB associated with the Icelandic and Samoan plumes. If so, the high-3He/4He source may also have a distinct oxygen isotopic composition from the rest of the mantle. Here, we test if the major elements of the high-3He/4He source preserve any evidence of heterogeneous accretion using measurements of three oxygen isotopes on olivine from a variety of high-3He/4He OIB locations. To high precision, the Δ17O value of high-3He/4He olivines from Hawaii, Pitcairn, Baffin Island and Samoa, are indistinguishable from bulk mantle olivine (Δ17OBulk Mantle - Δ17OHigh 3He/4He olivine = -0.002 ± 0.004 (2 × SEM)‰). Thus, there is no resolvable oxygen isotope evidence for heterogeneous accretion in the high-3He/4He source. Modelling of mixing processes indicates that if an early-forming, oxygen-isotope distinct mantle did exist, either the anomaly was extremely small, or the anomaly was homogenised away by later mantle convection. The δ18O values of olivine with the highest 3He/4He ratios from a variety of OIB locations have a relatively uniform composition (∼5‰). This composition is intermediate to values associated with the depleted MORB mantle and the average mantle. Similarly, δ18O values of olivine from high-3He/4He OIB correlate with radiogenic isotope ratios of He, Sr, and Nd. Combined, this suggests that magmatic oxygen is sourced from the same mantle as other, more incompatible elements and that the intermediate δ18O value is a feature of the high-3He/4He mantle source. The processes responsible for the δ18O signature of high-3He/4He mantle are not certain, but δ18O-87Sr/86Sr correlations indicate that it may be connected to a predominance of a HIMU-like (high U/Pb) component or other moderate δ18O components recycled into the high-3He/4He source.

  6. THE "CHEMICAL OXYGEN DEMAND / TOTAL VOLATILE ACIDS" RATIO AS AN ANAEROBIC TREATABILITY INDICATOR FOR LANDFILL LEACHATES

    Directory of Open Access Journals (Sweden)

    R. C. Contrera

    2015-03-01

    Full Text Available Abstract In some operational circumstances a fast evaluation of landfill leachate anaerobic treatability is necessary, and neither Biochemical Methane Potential nor BOD/COD ratio are fast enough. Looking for a fast indicator, this work evaluated the anaerobic treatability of landfill leachate from São Carlos-SP (Brazil in a pilot scale Anaerobic Sequence Batch Biofilm Reactor (AnSBBR. The experiment was conducted at ambient temperature in the landfill area. After the acclimation, at a second stage of operation, the AnSBBR presented efficiency above 70%, in terms of COD removal, utilizing landfill leachate without water dilution, with an inlet COD of about 11,000 mg.L-1, a TVA/COD ratio of approximately 0.6 and reaction time equal to 7 days. To evaluate the landfill leachate biodegradability variation over time, temporal profiles of concentration were performed in the AnSBBR. The landfill leachate anaerobic biodegradability was verified to have a direct and strong relationship to the TVA/COD ratio. For a TVA/CODTotal ratio lower than 0.20, the biodegradability was considered low, for ratios between 0.20 and 0.40 it was considered medium, and above 0.40 it was considered high.

  7. Nitrate and Nitrite Variability at the Seafloor of an Oxygen Minimum Zone Revealed by a Novel Microfluidic In-Situ Chemical Sensor.

    Directory of Open Access Journals (Sweden)

    Mustafa Yücel

    Full Text Available Microfluidics, or lab-on-a-chip (LOC is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h of nitrate+nitrite (ΣNOx and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM; while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1 μM. The 170 m site had the highest median ΣNOx level (25.8 μM with less variability (22.8 to 27.7 μM. At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics.

  8. Nitrate and Nitrite Variability at the Seafloor of an Oxygen Minimum Zone Revealed by a Novel Microfluidic In-Situ Chemical Sensor

    Science.gov (United States)

    Yücel, Mustafa; Beaton, Alexander D.; Dengler, Marcus; Mowlem, Matthew C.; Sohl, Frank; Sommer, Stefan

    2015-01-01

    Microfluidics, or lab-on-a-chip (LOC) is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h) of nitrate+nitrite (ΣNOx) and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m) nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM); while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1μM). The 170 m site had the highest median ΣNOx level (25.8 μM) with less variability (22.8 to 27.7 μM). At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics. PMID:26161958

  9. The effects of hypolimnetic oxygenation on the chemical, physical, and biological properties of a shallow drinking water reservoir

    OpenAIRE

    Browne, Richard Gregory

    2013-01-01

    Hypolimnetic anoxia can result in higher internal phosphorus (P) loads from the sediments to the water column, thereby increasing nutrient availability, making preventing anoxia a major goal for lake managers to improve water quality. Side-stream saturation (SSS), a type of hypolimnetic oxygenation system, has been developed to maintain oxygenated conditions at the sediments by withdrawing oxygen-depleted water from the hypolimnion to an on-site facility and injecting it with oxygen under hi...

  10. Catchment Very-High Frequency Hydrochemistry: the Critex Chemical House

    Science.gov (United States)

    Floury, P.; Gaillardet, J.; Tallec, G.; Blanchouin, A.; Ansart, P.

    2015-12-01

    Exploring the variations of river quality at very high frequency is still a big challenge that has fundamental implications both for understanding catchment ecosystems and for water quality monitoring. Within the French Critical Zone program CRITEX, we have proposed to develop a prototype called "Chemical House", applying the "lab on field" concept to one of the stream of the Orgeval Critical Zone Observatory. The Orgeval catchment (45 km2) is part of the Critical Zone RBV ("Réseau des bassins versants") network. It is a typical temperate agricultural catchment that has been intensively monitored for the last 50 years for hydrology and nutrient chemistry. Agricultural inputs and land use are also finely monitored making Orgeval an ideal basin to test the response of the Critical Zone to agricultural forcing. Geology consists of a typical sedimentary basin of Cenozoic age with horizontal layers of limestones, silcrete and marls, covered by a thin loamy layer. Two main aquifers are present within the catchment: the Brie and the Champigny aquifers. Mean runoff is 780 mm/yr. The Chemical House is a fully automated lab and installed directly along the river, which performs measurement of all major dissolved elements such as Na, Cl, Mg, Ca, NO3, SO4 and K every half hour. It also records all physical parameters (Temperature, pH, conductivity, O2 dissolved, Turbidity) of the water every minute. Orgeval Chemical House started to measure river chemistry on June 12, 2015 and has successfully now recorded several months of data. We will present the architecture of the Chemical House and the first reproducibility and accuracy tests made during the summer drought 2015 period. Preliminary results show that the chemical house is recoding significant nychtemeral (day/night) cycles for each element. We also observe that each element has its own behaviour along a day. First results open great prospects.

  11. High oxygen consumption rates in the deep layers of the North Aegean Sea (eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    E. SOUVERMEZOGLOU

    2002-06-01

    Full Text Available Severe winter meteorological conditions promote dense water formation over the shelves of the North Aegean Sea. The newly formed dense water fills the deep basins of the North Aegean Sea, contributing to their ventilation and the downward transport of organic and inorganic material. The great bathymetric variability imposes limitations on the deep circulation and the communication between the various basins and makes the North Aegean Sea an appropriate area for the monitoring of oxygen consumption in the deep layers. Historical hydrographic data suggest that there was extensive production of dense water in the North Aegean Sea on two occasions during the last decade, the winters of 1987 and 1992-1993. Our data series from August 1986 to September 1989 and from March 1997 to February 1999, permitted us to follow, step by step, the oxygen consumption and the nutrient regeneration in the deep basins of the northern Aegean Sea during these periods of isolation. The organic matter reaching the bottom layer just after the deep water formation event is rich in labile and easily oxidizable material and its decomposition leads to a significant oxygen uptake during the first year of stagnation. The further decomposition of the remaining semi-labile and refractory material turns over on greater time scales, by consuming lesser amounts of oxygen. A more significant oxygen decrease is recorded in the eastern basin (Lemnos Basin of the North Aegean Trough, than in the central (Athos Basin and the western (North Sporades Basin ones and is attributed to the irregular contribution of the Black Sea Water (BSW to the water masses formed on the different shelves of the North Aegean Sea. Our results and the existing data on the Turkish straits showed that dissolved organic matter is the major constituent responsible for this high oxygen consumption. The slightly different particulate organic carbon fluxes to these depressions play a secondary role.

  12. High oxygen consumption rates in the deep layers of the North Aegean Sea (eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    E. SOUVERMEZOGLOU

    2012-12-01

    Full Text Available Severe winter meteorological conditions promote dense water formation over the shelves of the North Aegean Sea. The newly formed dense water fills the deep basins of the North Aegean Sea, contributing to their ventilation and the downward transport of organic and inorganic material. The great bathymetric variability imposes limitations on the deep circulation and the communication between the various basins and makes the North Aegean Sea an appropriate area for the monitoring of oxygen consumption in the deep layers. Historical hydrographic data suggest that there was extensive production of dense water in the North Aegean Sea on two occasions during the last decade, the winters of 1987 and 1992-1993. Our data series from August 1986 to September 1989 and from March 1997 to February 1999, permitted us to follow, step by step, the oxygen consumption and the nutrient regeneration in the deep basins of the northern Aegean Sea during these periods of isolation. The organic matter reaching the bottom layer just after the deep water formation event is rich in labile and easily oxidizable material and its decomposition leads to a significant oxygen uptake during the first year of stagnation. The further decomposition of the remaining semi-labile and refractory material turns over on greater time scales, by consuming lesser amounts of oxygen. A more significant oxygen decrease is recorded in the eastern basin (Lemnos Basin of the North Aegean Trough, than in the central (Athos Basin and the western (North Sporades Basin ones and is attributed to the irregular contribution of the Black Sea Water (BSW to the water masses formed on the different shelves of the North Aegean Sea. Our results and the existing data on the Turkish straits showed that dissolved organic matter is the major constituent responsible for this high oxygen consumption. The slightly different particulate organic carbon fluxes to these depressions play a secondary role.

  13. Usefulness of high doses of glucocorticoids and hyperbaric oxygen therapy in sudden sensorineural hearing loss treatment.

    Science.gov (United States)

    Narozny, Waldemar; Sicko, Zdzislaw; Przewozny, Tomasz; Stankiewicz, Czeslaw; Kot, Jacek; Kuczkowski, Jerzy

    2004-11-01

    We investigated the effect of pharmacologic (steroids, vasodilators, vitamins, and Betaserc) and hyperbaric oxygen therapy on patients with sudden sensorineural hearing loss. The pharmacologic arm of the study consisted of 52 patients with defined sudden sensorineural hearing loss treated simultaneously in the ENT Department and National Center for Hyperbaric Medicine of the Medical University of Gdansk, Poland, from 1997 to 2000 (Group A). The hyperbaric oxygen therapy consisted of exposure to 100% oxygen at a pressure of 250 kPa for a total of 60 minutes in a multiplace hyperbaric chamber. The control group included 81 patients with defined sudden sensorineural hearing loss treated in the ENT Department, Medical University of Gdansk, from 1980 to 1996 (Group B). Both groups were comparable regarding the age of the patients, season of hearing loss occurrence, tinnitus and vestibular symptom frequency, delay before therapy, and average threshold loss before the start of treatment. The treatment results (hearing gain) were estimated using pure-tone audiometry. We retrospectively analyzed the audiograms of all patients. Patients from Group A (blood flow-promoting drugs, glucocorticoids in high doses, betahistine, and hyperbaric oxygen therapy) showed significantly better recovery of hearing levels compared with those from Group B (blood flow-promoting drugs and glucocorticoids in low doses) at seven frequencies (500, 1,000, 2,000, 3,000, 4,000, 6,000, and 8,000 Hz) (p < 0.05) and four groups of frequencies (pure-tone average, high-tone average, pure middle-tone average, and overall average) (p < 0.05). Percentage hearing gain in all investigated frequencies was also better in Group A versus Group B, and the differences were statistically significant (p < 0.05). We conclude that hyperbaric oxygen therapy with high doses of glucocorticoids improves the results of conventional sudden sensorineural hearing loss treatment and should be recommended. In addition, the best

  14. Modeling, simulation, and high-autonomy control of a Martian oxygen production plant

    Science.gov (United States)

    Schooley, L. C.; Cellier, F. E.; Wang, F.-Y.; Zeigler, B. P.

    1992-01-01

    Progress on a project for the development of a high-autonomy intelligent command and control architecture for process plants used to produce oxygen from local planetary resources is reported. A distributed command and control architecture is being developed and implemented so that an oxygen production plant, or other equipment, can be reliably commanded and controlled over an extended time period in a high-autonomy mode with high-level task-oriented teleoperation from one or several remote locations. During the reporting period, progress was made at all levels of the architecture. At the remote site, several remote observers can now participate in monitoring the plant. At the local site, a command and control center was introduced for increased flexibility, reliability, and robustness. The local control architecture was enhanced to control multiple tubes in parallel, and was refined for increased robustness. The simulation model was enhanced to full dynamics descriptions.

  15. High-Performance Pd3Pb Intermetallic Catalyst for Electrochemical Oxygen Reduction.

    Science.gov (United States)

    Cui, Zhiming; Chen, Hao; Zhao, Mengtian; DiSalvo, Francis J

    2016-04-13

    Extensive efforts to develop highly active and strongly durable electrocatalyst for oxygen reduction are motivated by a need for metal-air batteries and fuel cells. Here, we report a very promising catalyst prototype of structurally ordered Pd-based alloys, Pd3Pb intermetallic compound. Such structurally ordered Pd3Pb/C exhibits a significant increase in mass activity. More importantly, compared to the conventional Pt/C catalysts, ordered Pd3Pb/C is highly durable and exhibits a much longer cycle life and higher cell efficiency in Zn-air batteries. Interestingly, ordered Pd3Pb/C possesses very high methanol tolerance during electrochemical oxygen reduction, which make it an excellent methanol-tolerant cathode catalyst for alkaline polymer electrolyte membrane fuel cells. This study provides a promising route to optimize the synthesis of ordered Pd-based intermetallic catalysts for fuel cells and metal-air batteries.

  16. Micro-collimators fabricated by chemical etching of thin polyallyldiglycol carbonate polymer films exposed to oxygen ions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, V.W.Y.; Ng, C.K.M.; Nikezic, D. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Konishi, T. [National Institute of Radiological Sciences, Department of Technical Support and Development, Chiba 263-8555 (Japan); Yu, K.N., E-mail: peter.yu@cityu.edu.h [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

    2011-03-01

    One approach for {alpha} particle radiobiological experiments is to use solid-state nuclear track detectors (SSNTDs) as support substrates to record the {alpha} particle hit positions on the targets. To facilitate accurate characterization of the hit positions as well as the incident {alpha} particle energies, micro-collimators are required in these experiments to restrict the incident {alpha} particles to those with small deviations from normal incidence with respect to the collimator. In the present paper, we fabricated micro-collimators, which restricted {alpha} particles to those with deviations as low as 12{sup o}. Specially etched polyallyldiglycol carbonate (PADC) films, which are a kind of SSNTD, with a thickness 70 {mu}m were prepared from commercially available PADC films. These were then irradiated by 4.83 MeV/n oxygen ions generated from the heavy-ion medical accelerator in Chiba (HIMAC), Japan. The irradiated films were chemically etched for at least 2.7 h to achieve etched-through air channels to form the micro-collimators. The micro-collimators formed by etching the irradiated films for 2.7, 3.0 and 4.0 h were experimentally shown to be able to restrict {alpha} particles to those very close to normal incidence. In contrast, the micro-collimator formed by etching the irradiated film for 4.5 h started to allow {alpha} particles with larger deviations from normal incidence to pass through, which is likely due to overlapping of air channels from excessive etching.

  17. Efficiency of horizontal roughing filter in removing nitrate, phosphate and chemical oxygen demand from effluent of waste stabilization pond

    Directory of Open Access Journals (Sweden)

    Seyed Mostafa Khezri

    2015-06-01

    Full Text Available Background: The effective size of the end grain of horizontal roughing filters (HRFs is larger than 2 mm. This study aimed to examine the efficiency of HRFs in removing nitrate, phosphate, and chemical oxygen demand (COD from effluent of a wastewater stabilization pond. Methods: This experimental study was conducted in 2013. The pilot project was transferred to the Karaj wastewater treatment plant (stabilization pond, and the installation, equipping, and start-up of the system began using an effluent treatment plant. Sampling was done from March to August in 3 rates, 0.5, 1 and 1.5 m/h, and included simultaneous sampling from inlet and outlet filtering to determine the concentrations of nitrate, phosphate, and COD. Results: At filtration rates of 0.5, 1, and 1.5 m/h, the average nitrate removal equaled 25%, 32%, and 34%, respectively, average phosphate removal equaled 29%, 26%, and 28%, respectively, and the average COD removal at filtration rates of 0.5, 1, and 1.5 m/h equaled 62%, 66%, and 68%, respectively. Outlet values of phosphate and nitrate were lower than the standards set by the Environmental Standards Organization (ESO (P < 0.05. Conclusion: According to the results of this study, the HRF function was approximately adequate in COD removal, but its efficiency in nitrate and phosphate removal was lower.

  18. An integrated mathematical model for chemical oxygen demand (COD) removal in moving bed biofilm reactors (MBBR) including predation and hydrolysis.

    Science.gov (United States)

    Revilla, Marta; Galán, Berta; Viguri, Javier R

    2016-07-01

    An integrated mathematical model is proposed for modelling a moving bed biofilm reactor (MBBR) for removal of chemical oxygen demand (COD) under aerobic conditions. The composite model combines the following: (i) a one-dimensional biofilm model, (ii) a bulk liquid model, and (iii) biological processes in the bulk liquid and biofilm considering the interactions among autotrophic, heterotrophic and predator microorganisms. Depending on the values for the soluble biodegradable COD loading rate (SCLR), the model takes into account a) the hydrolysis of slowly biodegradable compounds in the bulk liquid, and b) the growth of predator microorganisms in the bulk liquid and in the biofilm. The integration of the model and the SCLR allows a general description of the behaviour of COD removal by the MBBR under various conditions. The model is applied for two in-series MBBR wastewater plant from an integrated cellulose and viscose production and accurately describes the experimental concentrations of COD, total suspended solids (TSS), nitrogen and phosphorous obtained during 14 months working at different SCLRs and nutrient dosages. The representation of the microorganism group distribution in the biofilm and in the bulk liquid allow for verification of the presence of predator microorganisms in the second reactor under some operational conditions.

  19. Simple fabrication of hydrophilic nanochannels using the chemical bonding between activated ultrathin PDMS layer and cover glass by oxygen plasma.

    Science.gov (United States)

    Kim, So Hyun; Cui, Yidan; Lee, Min Jung; Nam, Seong-Won; Oh, Doori; Kang, Seong Ho; Kim, Youn Sang; Park, Sungsu

    2011-01-21

    This study describes a simple and low cost method for fabricating enclosed transparent hydrophilic nanochannels by coating low-viscosity PDMS (monoglycidyl ether-terminated polydimethylsiloxane) as an adhesion layer onto the surface of the nanotrenches that are molded with a urethane-based UV-curable polymer, Norland Optical Adhesive (NOA 63). In detail, the nanotrenches made of NOA 63 were replicated from a Si master mold and coated with 6 nm thick layer of PDMS. These nanotrenches underwent an oxygen plasma treatment and finally were bound to a cover glass by chemical bonding between silanol and hydroxyl groups. Hydrophobic recovery that is observed in the bulk PDMS was not observed in the thin film of PDMS on the mold and the PDMS-coated nanochannel maintained its surface hydrophilicity for at least one month. The potentials of the nanochannels for bioapplications were demonstrated by stretching λ-DNA (48,502 bp) in the channels. Therefore, this fabrication approach provides a practical solution for the simple fabrication of the nanochannels for bioapplications.

  20. Immobilizing of catalyst using Bayah's natural zeolite to reduce the chemical oxygen demand (COD) and total organic carbon (TOC)

    Science.gov (United States)

    Jayanudin, Kustiningsih, Indar; Sari, Denni Kartika

    2017-05-01

    Indonesia is rich of natural minerals, many of which had not been widely used. One potential natural mineral is zeolite from Bayah Banten that can be used to support catalyst in the process of waste degradation. The purpose of this research is to characterize the Bayah's zeolite and to figure out the effectiveness of the zeolite as supporting agent to the Fe catalyst in the process of phenol degradation, with the main purposes are to reduce the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC). This research consists of three steps, activation of natural zeolite using 1M, 2M, and 3M NaOH solution, impregnation process with 0.025M, 0.05 M and 0.075M Fe(NO3)3.9H2O solution, and calcination at 500°C. Bayah's natural zeolite was characterize using Brauner-Emmet-Teller (BET) for its pore area, X-ray Fluorescence (XRF) for analyzing zeolite's component before and after activation process and after impregnation process, and Scanning Electron Microscope (SEM) for analyzing zeolite's morphology. The result showed that the highest pore area was 9Å, Fe metal from Fe(NO3)3.9H2O 0,075 M solution remained in zeolite pore was 7,73%, the reduction of COD and TOC was yielded at H2O2: phenol ratio of 1 : 6.

  1. Analysis of chemical composition of high viscous oils

    Directory of Open Access Journals (Sweden)

    Irina Germanovna Yashchenko

    2014-07-01

    Full Text Available The spatial distribution of viscous oils which are considered as an important reserve for oil-production in future were studied on base of information from global database on oil physical and chemical properties. Changes in chemical composition of viscous oils in different basins and continents were analyzed as well. It is shown, on average, viscous oils are sulfur-bearing, low paraffin, highly resinous oils with an average content of asphaltenes and low content of the fraction boiling at 200 C. Study results of viscous oils peculiarities of Canada, Russia and Venezuela are given. The analysis results can be used to determine the optimal layouts and conditions of oil transportation, to improve the search methods of geochemical exploration, and to solve other problems in the oil chemistry.

  2. CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

    KAUST Repository

    Rydén, Magnus

    2011-03-01

    Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor system. For the oxygen uncoupling experiments, it was found that the particles released O2 in gas phase at temperatures above 720°C when the fuel reactor was fluidized with CO2. The effect increased with increased temperature, and with the O2 partial pressure in the air reactor. At 950°C, the O2 concentration in the outlet from the fuel reactor was in the order of 4.0vol%, if the particles were oxidized in air. For the chemical-looping combustion experiments the combustion efficiency with standard process parameters was in the order of 95% at 950°C, using 1000kg oxygen carrier per MW natural gas, of which about 30% was located in the fuel reactor. Reducing the fuel flow so that 1900kg oxygen carrier per MW natural gas was used improved the combustion efficiency to roughly 99.8%. The particles retained their physical properties, reactivity with CH4 and ability to release gas-phase O2 reasonably well throughout the testing period and there were no problems with the fluidization or formation of solid carbon in the reactor. X-ray diffraction showed that the particles underwent changes in their phase composition though. © 2010 Elsevier Ltd.

  3. High-temperature isothermal chemical cycling for solar-driven fuel production.

    Science.gov (United States)

    Hao, Yong; Yang, Chih-Kai; Haile, Sossina M

    2013-10-28

    The possibility of producing chemical fuel (hydrogen) from the solar-thermal energy input using an isothermal cycling strategy is explored. The canonical thermochemical reactive oxide, ceria, is reduced under high temperature and inert sweep gas, and in the second step oxidized by H2O at the same temperature. The process takes advantage of the oxygen chemical potential difference between the inert sweep gas and high-temperature steam, the latter becoming more oxidizing with increasing temperature as a result of thermolysis. The isothermal operation relieves the need to achieve high solid-state heat recovery for high system efficiency, as is required in a conventional two-temperature process. Thermodynamic analysis underscores the importance of gas-phase heat recovery in the isothermal approach and suggests that attractive efficiencies may be practically achievable on the system level. However, with ceria as the reactive oxide, the isothermal approach is not viable at temperatures much below 1400 °C irrespective of heat recovery. Experimental investigations show that an isothermal cycle performed at 1500 °C can yield fuel at a rate of ~9.2 ml g(-1) h(-1), while providing exceptional system simplification relative to two-temperature cycling.

  4. Understanding the biological activity of high rate algae ponds through the calculation of oxygen balances.

    Science.gov (United States)

    Arbib, Zouhayr; de Godos Crespo, Ignacio; Corona, Enrique Lara; Rogalla, Frank

    2017-06-01

    Microalgae culture in high rate algae ponds (HRAP) is an environmentally friendly technology for wastewater treatment. However, for the implementation of these systems, a better understanding of the oxygenation potential and the influence of climate conditions is required. In this work, the rates of oxygen production, consumption, and exchange with the atmosphere were calculated under varying conditions of solar irradiance and dilution rate during six months of operation in a real scale unit. This analysis allowed determining the biological response of these dynamic systems. The rates of oxygen consumption measured were considerably higher than the values calculated based on the organic loading rate. The response to light intensity in terms of oxygen production in the bioreactor was described with one of the models proposed for microalgae culture in dense concentrations. This model is based on the availability of light inside the culture and the specific response of microalgae to this parameter. The specific response to solar radiation intensity showed a reasonable stability in spite of the fluctuations due to meteorological conditions. The methodology developed is a useful tool for optimization and prediction of the performance of these systems.

  5. Biomass-oxygen gasification in a high-temperature entrained-flow gasifier.

    Science.gov (United States)

    Zhou, Jinsong; Chen, Qing; Zhao, Hui; Cao, Xiaowei; Mei, Qinfeng; Luo, Zhongyang; Cen, Kefa

    2009-01-01

    The technology associated with indirect biomass liquefaction is currently arousing increased attention, as it could ensure a supply of transportation fuels and reduce the use of petroleum. The characteristics of biomass-oxygen gasification in a bench-scale laminar entrained-flow gasifier were studied in the paper. Experiments were carried out to investigate the influence of some key factors, including reaction temperature, residence time and oxygen/biomass ratio, on the gasification. The results indicated that higher temperature favored H2 and CO production. Cold gas efficiency was improved by N10% when the temperature was increased from 1000 to 1400 degrees C. The carbon conversion increased and the syngas quality was improved with increasing residence time. A shorter residence resulted in incomplete gasification. An optimal residence time of 1.6 s was identified in this study. The introduction of oxygen to the gasifier strengthened the gasification and improved the carbon conversion, but lowered the lower heating value and the H2/CO ratio of the syngas. The optimal oxygen/biomass ratio in this study was 0.4. The results of this study will help to improve our understanding of syngas production by biomass high-temperature gasification.

  6. FIRST SPECTROSCOPIC EVIDENCE FOR HIGH IONIZATION STATE AND LOW OXYGEN ABUNDANCE IN Ly{alpha} EMITTERS ,

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Kimihiko; Shimasaku, Kazuhiro; Hashimoto, Takuya; Ono, Yoshiaki [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ouchi, Masami [Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Lee, Janice C., E-mail: nakajima@astron.s.u-tokyo.ac.jp [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2013-05-20

    We present results from Keck/NIRSPEC and Magellan/MMIRS follow-up spectroscopy of Ly{alpha} emitters (LAEs) at z = 2.2 identified in our Subaru narrowband survey. We successfully detect H{alpha} emission from seven LAEs, and perform a detailed analysis of six LAEs free from active galactic nucleus activity, two out of which, CDFS-3865 and COSMOS-30679, have [O II] and [O III] line detections. They are the first [O II]-detected LAEs at high-z, and their [O III]/[O II] ratios and R23-indices provide the first simultaneous determinations of ionization parameter and oxygen abundance for LAEs. CDFS-3865 has a very high ionization parameter (q{sub ion}=2.5{sup +1.7}{sub -0.8} Multiplication-Sign 10{sup 8} cm s{sup -1}) and a low oxygen abundance (12+ log (O/H)=7.84{sup +0.24}{sub -0.25}) in contrast with moderate values of other high-z galaxies such as Lyman break galaxies (LBGs). COSMOS-30679 also possesses a relatively high ionization parameter (q{sub ion}=8{sup +10}{sub -4} Multiplication-Sign 10{sup 7} cm s{sup -1}) and a low oxygen abundance (12+ log (O/H)=8.18{sup +0.28}{sub -0.28}). Both LAEs appear to fall below the mass-metallicity relation of z {approx} 2 LBGs. Similarly, a low metallicity of 12 + log (O/H) < 8.4 is independently indicated for typical LAEs from a composite spectrum and the [N II]/H{alpha} index. Such high ionization parameters and low oxygen abundances can be found in local star-forming galaxies, but this extreme local population occupies only {approx}0.06% of the Sloan Digital Sky Survey spectroscopic galaxy sample with a number density {approx}100 times smaller than that of LAEs. With their high ionization parameters and low oxygen abundances, LAEs would represent an early stage of galaxy formation dominated by massive stars in compact star-forming regions. High-q{sub ion} galaxies like LAEs would produce ionizing photons efficiently with a high escape fraction achieved by density-bounded H II regions, which would significantly contribute to

  7. Pulmonary interstitial fibrosis following near-drowning and exposure to short-term high oxygen concentrations.

    Science.gov (United States)

    Glauser, F L; Smith, W R

    1975-09-01

    Following near-drowning in fresh water, a 19-year-old man experienced severe adult respiratory distress syndrome, necessitating ventilatory support with positive end-expiratory pressure and high oxygen concentrations. Post-extubation, his course was highlighted by persistent hypoxemia and interrupted by a lung abscess which responded promptly to antibiotics. Pulmonary function tests were consistent with severe restrictive disease and chest radiograph revealed persistent bilateral alveolar and interstitial infiltrates. An open lung biopsy on the 26th hospital day showed interstitial fibrosis. Over the ensuing two months, the chest radiograph and pulmonary function tests returned towards normal. We attribute the pulmonary fibrosis to incomplete resolution of the alveolar interstitial pathology secondary to the near-drowning and exposure to high oxygen mixtures.

  8. High performance electrodes in vanadium redox flow batteries through oxygen-enriched thermal activation

    Science.gov (United States)

    Pezeshki, Alan M.; Clement, Jason T.; Veith, Gabriel M.; Zawodzinski, Thomas A.; Mench, Matthew M.

    2015-10-01

    The roundtrip electrochemical energy efficiency is improved from 63% to 76% at a current density of 200 mA cm-2 in an all-vanadium redox flow battery (VRFB) by utilizing modified carbon paper electrodes in the high-performance no-gap design. Heat treatment of the carbon paper electrodes in a 42% oxygen/58% nitrogen atmosphere increases the electrochemically wetted surface area from 0.24 to 51.22 m2 g-1, resulting in a 100-140 mV decrease in activation overpotential at operationally relevant current densities. An enriched oxygen environment decreases the amount of treatment time required to achieve high surface area. The increased efficiency and greater depth of discharge doubles the total usable energy stored in a fixed amount of electrolyte during operation at 200 mA cm-2.

  9. M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood

    CERN Document Server

    Gizis, John E; Hauschildt, Peter H

    2015-01-01

    We investigate the frequency of high carbon-to-oxygen (C/O $= 0.9$) M dwarf stars in the solar neighbourhood. Using synthetic spectra, we find that such M dwarfs would have weaker TiO bands relative to hydride features. Similar weakening has already been detected in M-subdwarf (sdM) stars. By comparing to existing spectroscopic surveys of nearby stars, we show that less than one percent of nearby stars have high carbon-to-oxygen ratios. This limit does not include stars with C/O$=0.9$, [m/H]$>0.3$, and [C/Fe]$>0.1$, which we predict to have low-resolution optical spectra similar to solar metallicity M dwarfs.

  10. Numerical analysis of the effects of a high gradient magnetic field on flowing erythrocytes in a membrane oxygenator

    Energy Technology Data Exchange (ETDEWEB)

    Mitamura, Yoshinori, E-mail: ymitamura@par.odn.ne.jp; Okamoto, Eiji, E-mail: okamoto@tspirit.tokai-u.jp

    2015-04-15

    This study was carried out to clarify the effect of a high gradient magnetic field on pressure characteristics of blood in a hollow fiber membrane oxygenator in a solenoid coil by means of numerical analysis. Deoxygenated erythrocytes are paramagnetic, and oxygenated erythrocytes are diamagnetic. Blood changes its magnetic susceptibility depending on whether it is carrying oxygen or not. Motion of blood was analyzed by solving the continuous equation and the Navier–Stokes equation. It was confirmed that oxygenation of deoxygenated blood in the downstream side of the applied magnetic field was effective for pressure rise in a non-uniform magnetic field. The pressure rise was enhanced greatly by an increase in magnetic field intensity. The results suggest that a membrane oxygenator works as an actuator and there is a possibility of self-circulation of blood through an oxygenator in a non-uniform magnetic field. - Highlights: • Effects of a gradient magnetic field on erythrocytes in an oxygenator were analyzed. • Blood changes magnetic susceptibility depending on if it is carrying oxygen or not. • Oxygenation of deoxygenated blood is effective for pressure rise in a magnetic field. • A membrane oxygenator works as an actuator. • There is a possibility of self-circulation of blood through an oxygenator.

  11. High surface area graphene foams by chemical vapor deposition

    Science.gov (United States)

    Drieschner, Simon; Weber, Michael; Wohlketzetter, Jörg; Vieten, Josua; Makrygiannis, Evangelos; Blaschke, Benno M.; Morandi, Vittorio; Colombo, Luigi; Bonaccorso, Francesco; Garrido, Jose A.

    2016-12-01

    Three-dimensional (3D) graphene-based structures combine the unique physical properties of graphene with the opportunity to get high electrochemically available surface area per unit of geometric surface area. Several preparation techniques have been reported to fabricate 3D graphene-based macroscopic structures for energy storage applications such as supercapacitors. Although reaserch has been focused so far on achieving either high specific capacitance or high volumetric capacitance, much less attention has been dedicated to obtain high specific and high volumetric capacitance simultaneously. Here, we present a facile technique to fabricate graphene foams (GF) of high crystal quality with tunable pore size grown by chemical vapor deposition. We exploited porous sacrificial templates prepared by sintering nickel and copper metal powders. Tuning the particle size of the metal powders and the growth temperature allow fine control of the resulting pore size of the 3D graphene-based structures smaller than 1 μm. The as-produced 3D graphene structures provide a high volumetric electric double layer capacitance (165 mF cm-3). High specific capacitance (100 Fg-1) is obtained by lowering the number of layers down to single layer graphene. Furthermore, the small pore size increases the stability of these GFs in contrast to the ones that have been grown so far on commercial metal foams. Electrodes based on the as-prepared GFs can be a boost for the development of supercapacitors, where both low volume and mass are required.

  12. CONSTRAINTS ON THE SOURCE OF ULTRA-HIGH-ENERGY COSMIC RAYS USING ANISOTROPY VERSUS CHEMICAL COMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ruo-Yu; Wang, Xiang-Yu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Taylor, Andrew M. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Lemoine, Martin [Institut d' Astrophysique de Paris, CNRS, UPMC, 98 bis Boulevard Arago, F-75014 Paris (France); Waxman, Eli, E-mail: lemoine@iap.fr [Physics Faculty, Weizmann Institute, P.O. Box 26, Rehovot 7600 (Israel)

    2013-10-20

    The joint analysis of anisotropy signals and chemical composition of ultra-high-energy cosmic rays offers strong potential for shedding light on the sources of these particles. Following up on an earlier idea, this paper studies the anisotropies produced by protons of energy >E/Z, assuming that anisotropies at energy >E have been produced by nuclei of charge Z, which share the same magnetic rigidity. We calculate the number of secondary protons produced through photodisintegration of the primary heavy nuclei. Making the extreme assumption that the source does not inject any proton, we find that the source(s) responsible for anisotropies such as reported by the Pierre Auger Observatory should lie closer than ∼20-30, 80-100, and 180-200 Mpc if the anisotropy signal is mainly composed of oxygen, silicon, and iron nuclei, respectively. A violation of this constraint would otherwise result in the secondary protons forming a more significant anisotropy signal at lower energies. Even if the source were located closer than this distance, it would require an extraordinary metallicity ∼> 120, 1600, and 1100 times solar metallicity in the acceleration zone of the source, for oxygen, silicon, and iron, respectively, to ensure that the concomitantly injected protons do not produce a more significant low-energy anisotropy. This offers interesting prospects for constraining the nature and the source of ultra-high-energy cosmic rays with the increase in statistics expected from next-generation detectors.

  13. Chemical Vapor Deposition at High Pressure in a Microgravity Environment

    Science.gov (United States)

    McCall, Sonya; Bachmann, Klaus; LeSure, Stacie; Sukidi, Nkadi; Wang, Fuchao

    1999-01-01

    In this paper we present an evaluation of critical requirements of organometallic chemical vapor deposition (OMCVD) at elevated pressure for a channel flow reactor in a microgravity environment. The objective of using high pressure is to maintain single-phase surface composition for materials that have high thermal decomposition pressure at their optimum growth temperature. Access to microgravity is needed to maintain conditions of laminar flow, which is essential for process analysis. Based on ground based observations we present an optimized reactor design for OMCVD at high pressure and reduced gravity. Also, we discuss non-intrusive real-time optical monitoring of flow dynamics coupled to homogeneous gas phase reactions, transport and surface processes. While suborbital flights may suffice for studies of initial stages of heteroepitaxy experiments in space are essential for a complete evaluation of steady-state growth.

  14. Investigation into the High Voltage Shutdown of the Oxygen Generator System in the International Space Station

    Science.gov (United States)

    Carpenter, Joyce E.; Gentry, Gregory J.; Diderich, Greg S.; Roy, Robert J.; Golden, John L.; VanKeuren, Steve; Steele, John W.; Rector, Tony J.; Varsik, Jerome D.; Montefusco, Daniel J.; Wilson, Mark E.; Worthy, Erica S.

    2012-01-01

    The Oxygen Generation System (OGS) Hydrogen Dome Assembly Orbital Replacement Unit (ORU) serial number 00001 suffered a cell stack high-voltage shutdown on July 5, 2010. The Hydrogen Dome Assembly ORU was removed and replaced with the on-board spare ORU serial number 00002 to maintain OGS operation. The Hydrogen Dome Assembly ORU was returned from ISS on STS-133/ULF-5 in March 2011 with test, teardown and evaluation (TT&E) and failure analysis to follow.

  15. Highly oxygenated triterpenoids from the roots of Schisandra chinensis and their anti-inflammatory activities.

    Science.gov (United States)

    Song, Qiu-Yan; Gao, Kun; Nan, Zhi-Biao

    2016-01-01

    A new highly oxygenated triterpenoid, schinchinenlactone D (1), and three known compounds (2-4) were isolated from the roots of Schisandra chinensis. Their structures were determined by combining the spectroscopic analysis with the theoretical computations. The anti-inflammatory activities of compounds 1-4 were evaluated, and compound 3 exhibits the most significant activity in the inhibition of NO production with an IC50 value of 10.6 μM.

  16. Studies on high chemical reactivity of nano-NaH

    Institute of Scientific and Technical Information of China (English)

    FAN Yinheng; ZOU Yunling; JIN Dan; WU Qiang; LIU Tong; XU Jie

    2007-01-01

    A comparison between the initial reaction rates of nanometric and commercial Nail has been studied in four test reactions: 1) hydrogenolysis of chlorobenzene; 2) selec-tive reduction of cinnamaldehyde to cinnamyl alcohol; 3)metallation of dimethyl sulfoxide; and 4) catalytic hydroge-nation ofolefins. The experimental results indicate that when Nail is used as a chemical reagent in the first three reactions,the initial reaction rates of nano-NaH is 230, 120 and 110 times higher than those of the commercial ones respectively,and it is in agreement with the difference in specific surface areas between these two forms of Nail. When Nail is used as a catalyst component together with Cp2TiCl2 in the fourth reaction, catalyst with nano-NaH gives extremely high activity in the hydrogenation of olefins, while the one with commercial Nail gives no activity at all even ifa large amount of the commercial Nail is used to make the total surface area equivalent to that of nano-NaH. Thus, it is evident that although large specific surface area is important for nano-Nail to be used as a catalyst component, high surface energy with surface defects seems to be more important. The largespecific surface and the activated surface of nano-NaH withhigh surface energy should be the main factors for thei rextremely high chemical reactivity, while whether the former or the latter one plays a leading role depends on the type of reactions involved.

  17. Pasteurization of food by hydrostatic high pressure: chemical aspects.

    Science.gov (United States)

    Tauscher, B

    1995-01-01

    Food pasteurized by hydrostatic high pressure have already been marketed in Japan. There is great interest in this method also in Europe and USA. Temperature and pressure are the essential parameters influencing the state of substances including foods. While the influence of temperature on food has been extensively investigated, effects of pressure, also in combination with temperature, are attracting increasing scientific attention now. Processes and reactions in food governed by Le Chatelier's principle are of special interest; they include chemical reactions of both low- and macromolecular compounds. Theoretical fundamentals and examples of pressure affected reactions are presented.

  18. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    Energy Technology Data Exchange (ETDEWEB)

    Sheard, Michael A., E-mail: msheard@chla.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ghent, Matthew V., E-mail: mattghent@gmail.com [Department of Pathology, Keck School of Medicine, University of Southern California, Health Sciences Campus, Los Angeles, CA 90089 (United States); Cabral, Daniel J., E-mail: dcabral14@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Lee, Joanne C., E-mail: joannebarnhart@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Khankaldyyan, Vazgen, E-mail: khangaldian@yahoo.com [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ji, Lingyun, E-mail: lingyun.ji@med.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Wu, Samuel Q., E-mail: swu@chla.usc.edu [Medical Genetics, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Kang, Min H., E-mail: min.kang@ttuhsc.edu [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); and others

    2015-05-15

    Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.

  19. Hydrogen-oxygen flame acceleration and transition to detonation in channels with no-slip walls for a detailed chemical reaction model.

    Science.gov (United States)

    Ivanov, M F; Kiverin, A D; Liberman, M A

    2011-05-01

    The features of flame acceleration in channels with wall friction and the deflagration to detonation transition (DDT) are investigated theoretically and using high resolution numerical simulations of two-dimensional reactive Navier-Stokes equations, including the effects of viscosity, thermal conduction, molecular diffusion, and a detailed chemical reaction mechanism for hydrogen-oxygen gaseous mixture. It is shown that in a wide channel, from the beginning, the flame velocity increases exponentially for a short time and then flame acceleration decreases, ending up with the abrupt increase of the combustion wave velocity and the actual transition to detonation. In a thin channel with a width smaller than the critical value, the exponential increase of the flame velocity is not bounded and ends up with the transition to detonation. The transition to detonation occurs due to the pressure pulse, which is formed at the tip of the accelerating flame. The amplitude of the pressure pulse grows exponentially due to a positive feedback coupling between the pressure pulse and the heat released in the reaction. Finally, large amplitude pressure pulse steepens into a strong shock coupled with the reaction zone forming the overdriven detonation. The evolution from a temperature gradient to a detonation via the Zeldovich gradient mechanism and its applicability to the deflagration-to-detonation transition is investigated for combustible materials whose chemistry is governed by chain-branching kinetics. The results of the high resolution simulations are fully consistent with experimental observations of the flame acceleration and DDT.

  20. Supplemental Oxygen During High-Intensity Exercise Training in Nonhypoxemic Chronic Obstructive Pulmonary Disease.

    Science.gov (United States)

    Neunhäuserer, Daniel; Steidle-Kloc, Eva; Weiss, Gertraud; Kaiser, Bernhard; Niederseer, David; Hartl, Sylvia; Tschentscher, Marcus; Egger, Andreas; Schönfelder, Martin; Lamprecht, Bernd; Studnicka, Michael; Niebauer, Josef

    2016-11-01

    Physical exercise training is an evidence-based treatment in chronic obstructive pulmonary disease, and patients' peak work rate is associated with reduced chronic obstructive pulmonary disease mortality. We assessed whether supplemental oxygen during exercise training in nonhypoxemic patients with chronic obstructive pulmonary disease might lead to superior training outcomes, including improved peak work rate. This was a randomized, double-blind, controlled, crossover trial. Twenty-nine patients with chronic obstructive pulmonary disease (aged 63.5 ± 5.9 years; forced expiratory volume in 1 second percent predicted, 46.4 ± 8.6) completed 2 consecutive 6-week periods of endurance and strength training with progressive intensity, which was performed 3 times per week with supplemental oxygen or compressed medical air (flow via nasal cannula: 10 L/min). Each session of electrocardiography-controlled interval cycling lasted 31 minutes and consisted of a warm-up, 7 cycles of 1-minute intervals at 70% to 80% of peak work rate alternating with 2 minutes of active recovery, and final cooldown. Thereafter, patients completed 8 strength-training exercises of 1 set each with 8 to 15 repetitions to failure. Change in peak work rate was the primary study end point. The increase in peak work rate was more than twice as high when patients exercised with supplemental oxygen compared with medical air (0.16 ± 0.02 W/kg vs 0.07 ± 0.02 W/kg; P exercise capacity. The impact of oxygen on peak work rate was 39.1% of the overall training effect, whereas it had no influence on strength gain (P > .1 for all exercises). We report that supplemental oxygen in nonhypoxemic chronic obstructive pulmonary disease doubled the effect of endurance training but had no effect on strength gain. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Quantitative mineralogical characterization of lunar high-Ti mare basalts and soils for oxygen production

    Science.gov (United States)

    Chambers, J. G.; Taylor, L. A.; Patchen, A.; McKay, D. S.

    1995-07-01

    Efficient lunar resource utilization requires accurate and quantitative evaluation of mineral and glass abundances, distribution, and extraction feasibility, especially for ilmenite. With this in mind, true modal analyses were performed on high-Ti mare basalts and soils with X ray/backscattered electron signal digital-imaging techniques, and these data indicate that (1) ilmenite concentrations are similar for basalts and immature-submature soils with similar TiO2 content; (2) ilmenite liberation of crushed mare basalts and immature-submature mare soils are comparable (i.e., both contain similar amounts of free ilmenite); and (3) because of impact melting and agglutination of primary minerals, mature mare soils contain less ilmenite (both free and attached). Modal analyses of magnetic separates of high-Ti mare basalts and soils show that (1) ilmenite was concentrated by a factor of >=3.3 and (2) soil ilmenite was concentrated to factors of 1.7-2.3. The lower soil ilmenite separation efficiency is attributed to Fe°-bearing agglutinitic glass and amorphous rinds adhered to soil particles. Mass yields of magnetically generated feedstocks were generally less than 5 wt.% in most cases. Calculation of oxygen yield (as released by hydrogen gas reduction of ilmenite) show that (1) beneficiated basalt will provide the most oxygen (8-10%), because of higher ilmenite concentration; (2) reduction of raw immature-submature mare soils and basalts will produce similar amounts of lunar liquid oxygen (LLOX) (2.1-3.1%) and (3) raw Fe-rich pyroclastic soil, 74220, will provide more oxygen (5.4%) than beneficiated high-Ti mare soils and half that of beneficiated high-Ti mare basalts. High-Ti mare soils are attractive resources for lunar liquid oxygen (LLOX) production because of their unconsolidated nature, high ilmenite abundance, and widespread occurrence. Energy-intensive excavation and comminution likely prohibits the basalt mining during early lunar occupation. Orange soils are

  2. Co-Digestion of Palm Oil Mill Effluent and Refined Glycerin Wash Water for Chemical Oxygen Demand Removal and Methane Production

    Directory of Open Access Journals (Sweden)

    A. Sulaiman

    2009-01-01

    Full Text Available Problem statement: Refined Glycerin Wash Water (RGWW from the oleochemical industry contains high Chemical Oxygen Demand (COD and requires proper treatment before disposal. Unfortunately the wash water also contains high concentration of sodium chloride (NaCl that could cause inhibition to the normal biological treatment process. However, there is feasibility of co-digesting the RGWW and Palm Oil Mill Effluent (POME for its treatment and methane recovery. Approach: A large 500 m3 semi-commercial closed digester tank was used to study the effect of co-digesting POME and RGWW under mesophilic condition at different RGWW percentage. The digester performance in terms of COD removal efficiency and methane production rate and stability based on total Volatile Fatty Acids (VFA accumulation, Mixed Liquor Volatile Suspended Solid (MLVSS and pH were evaluated. Results: At 1.0% of RGWW co-digested, both COD removal efficiency and methane production rate showed satisfactory results with higher than 90% and 505 m3 day-1, respectively. However, once the percentage was increased to a maximum of 5.25%, COD removal efficiency remains high but the methane production rate reduced significantly down to 307 m3 day-1. At this stage, the digester was already unstable with high total VFA recorded of 913 mg L-1 and low cells concentration of 8.58 g L-1. This was probably due to the effect of plasmolysis on the methanogens at high concentration of NaCl in the digester of nearly 4000 mg L-1. Conclusion: Co-digesting of RGWW with high NaCl content and POME is satisfactory for COD removal but not for increasing the methane production.

  3. Mining Chemical Activity Status from High-Throughput Screening Assays

    KAUST Repository

    Soufan, Othman

    2015-12-14

    High-throughput screening (HTS) experiments provide a valuable resource that reports biological activity of numerous chemical compounds relative to their molecular targets. Building computational models that accurately predict such activity status (active vs. inactive) in specific assays is a challenging task given the large volume of data and frequently small proportion of active compounds relative to the inactive ones. We developed a method, DRAMOTE, to predict activity status of chemical compounds in HTP activity assays. For a class of HTP assays, our method achieves considerably better results than the current state-of-the-art-solutions. We achieved this by modification of a minority oversampling technique. To demonstrate that DRAMOTE is performing better than the other methods, we performed a comprehensive comparison analysis with several other methods and evaluated them on data from 11 PubChem assays through 1,350 experiments that involved approximately 500,000 interactions between chemicals and their target proteins. As an example of potential use, we applied DRAMOTE to develop robust models for predicting FDA approved drugs that have high probability to interact with the thyroid stimulating hormone receptor (TSHR) in humans. Our findings are further partially and indirectly supported by 3D docking results and literature information. The results based on approximately 500,000 interactions suggest that DRAMOTE has performed the best and that it can be used for developing robust virtual screening models. The datasets and implementation of all solutions are available as a MATLAB toolbox online at www.cbrc.kaust.edu.sa/dramote and can be found on Figshare.

  4. Mining Chemical Activity Status from High-Throughput Screening Assays.

    Directory of Open Access Journals (Sweden)

    Othman Soufan

    Full Text Available High-throughput screening (HTS experiments provide a valuable resource that reports biological activity of numerous chemical compounds relative to their molecular targets. Building computational models that accurately predict such activity status (active vs. inactive in specific assays is a challenging task given the large volume of data and frequently small proportion of active compounds relative to the inactive ones. We developed a method, DRAMOTE, to predict activity status of chemical compounds in HTP activity assays. For a class of HTP assays, our method achieves considerably better results than the current state-of-the-art-solutions. We achieved this by modification of a minority oversampling technique. To demonstrate that DRAMOTE is performing better than the other methods, we performed a comprehensive comparison analysis with several other methods and evaluated them on data from 11 PubChem assays through 1,350 experiments that involved approximately 500,000 interactions between chemicals and their target proteins. As an example of potential use, we applied DRAMOTE to develop robust models for predicting FDA approved drugs that have high probability to interact with the thyroid stimulating hormone receptor (TSHR in humans. Our findings are further partially and indirectly supported by 3D docking results and literature information. The results based on approximately 500,000 interactions suggest that DRAMOTE has performed the best and that it can be used for developing robust virtual screening models. The datasets and implementation of all solutions are available as a MATLAB toolbox online at www.cbrc.kaust.edu.sa/dramote and can be found on Figshare.

  5. Mining Chemical Activity Status from High-Throughput Screening Assays.

    Science.gov (United States)

    Soufan, Othman; Ba-alawi, Wail; Afeef, Moataz; Essack, Magbubah; Rodionov, Valentin; Kalnis, Panos; Bajic, Vladimir B

    2015-01-01

    High-throughput screening (HTS) experiments provide a valuable resource that reports biological activity of numerous chemical compounds relative to their molecular targets. Building computational models that accurately predict such activity status (active vs. inactive) in specific assays is a challenging task given the large volume of data and frequently small proportion of active compounds relative to the inactive ones. We developed a method, DRAMOTE, to predict activity status of chemical compounds in HTP activity assays. For a class of HTP assays, our method achieves considerably better results than the current state-of-the-art-solutions. We achieved this by modification of a minority oversampling technique. To demonstrate that DRAMOTE is performing better than the other methods, we performed a comprehensive comparison analysis with several other methods and evaluated them on data from 11 PubChem assays through 1,350 experiments that involved approximately 500,000 interactions between chemicals and their target proteins. As an example of potential use, we applied DRAMOTE to develop robust models for predicting FDA approved drugs that have high probability to interact with the thyroid stimulating hormone receptor (TSHR) in humans. Our findings are further partially and indirectly supported by 3D docking results and literature information. The results based on approximately 500,000 interactions suggest that DRAMOTE has performed the best and that it can be used for developing robust virtual screening models. The datasets and implementation of all solutions are available as a MATLAB toolbox online at www.cbrc.kaust.edu.sa/dramote and can be found on Figshare.

  6. Chemical and Thermodynamic Properties at High Temperatures: A Symposium

    Science.gov (United States)

    Walker, Raymond F.

    1961-01-01

    This book contains the program and all available abstracts of the 90' invited and contributed papers to be presented at the TUPAC Symposium on Chemical and Thermodynamic Properties at High Temperatures. The Symposium will be held in conjunction with the XVIIIth IUPAC Congress, Montreal, August 6 - 12, 1961. It has been organized, by the Subcommissions on Condensed States and on Gaseous States of the Commission on High Temperatures and Refractories and by the Subcommission on Experimental Thermodynamics of the Commission on Chemical Thermodynamics, acting in conjunction with the Organizing Committee of the IUPAC Congress. All inquiries concerning participation In the Symposium should be directed to: Secretary, XVIIIth International Congress of Pure and Applied Chemistry, National Research Council, Ottawa, 'Canada. Owing to the limited time and facilities available for the preparation and printing of the book, it has not been possible to refer the proofs of the abstracts to the authors for checking. Furthermore, it has not been possible to subject the manuscripts to a very thorough editorial examination. Some obvious errors in the manuscripts have been corrected; other errors undoubtedly have been introduced. Figures have been redrawn only when such a step was essential for reproduction purposes. Sincere apologies are offered to authors and readers for any errors which remain; however, in the circumstances neither the IUPAC Commissions who organized the Symposium, nor the U. S. Government Agencies who assisted in the preparation of this book can accept responsibility for the errors.

  7. Graphene oxide and laponite composite films with high oxygen-barrier properties

    Science.gov (United States)

    Yoo, Jongtae; Lee, Sang Bong; Lee, Chang Kee; Hwang, Sung Wook; Kim, Chaerin; Fujigaya, Tsuyohiko; Nakashima, Naotoshi; Shim, Jin Kie

    2014-08-01

    The design and fabrication of oxygen barrier films is important for both fundamental and industrial applications. We prepared three different thin films composed of graphene oxide (GO) and laponite (LN), a typical low cost inorganic clay, with the GO/LN volume ratios of 1.9/0.1, 1.7/0.3 and 1.5/0.5 together with a double layer film of the GO and LN. We found that the films with GO/LN = 1.9/0.1 and the double layers exhibited high oxygen barrier and oxygen transmission rate values that reached 0.55 and 0.37 cm3 per m2 per atm per day, respectively, which were much lower than those of the films prepared from the pure GO, only LN and GO/LN = 1.7/0.3 and 1.5/0.5. This study is important for the design and fabrication of a film from GO-based all inorganic nanomaterials for applications in gas-barrier membranes.The design and fabrication of oxygen barrier films is important for both fundamental and industrial applications. We prepared three different thin films composed of graphene oxide (GO) and laponite (LN), a typical low cost inorganic clay, with the GO/LN volume ratios of 1.9/0.1, 1.7/0.3 and 1.5/0.5 together with a double layer film of the GO and LN. We found that the films with GO/LN = 1.9/0.1 and the double layers exhibited high oxygen barrier and oxygen transmission rate values that reached 0.55 and 0.37 cm3 per m2 per atm per day, respectively, which were much lower than those of the films prepared from the pure GO, only LN and GO/LN = 1.7/0.3 and 1.5/0.5. This study is important for the design and fabrication of a film from GO-based all inorganic nanomaterials for applications in gas-barrier membranes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03429e

  8. High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M

    2011-03-01

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed high temperature chemical kinetic mechanism for n-octane and three lightly branched isomers octane (i.e., 2-methylheptane, 3-methylheptane, and 2,5-dimethylhexane). The model is validated against experimental data from a variety of fundamental combustion devices. This new model is used to show how the location and number of methyl branches affects fuel reactivity including laminar flame speed and species formation.

  9. The role of oxygen-increased respirator in humans ascending to high altitude

    Directory of Open Access Journals (Sweden)

    Shen Guanghao

    2012-08-01

    Full Text Available Abstract Background Acute mountain sickness (AMS is common for people who live in low altitude areas ascending to the high altitude. Many instruments have been developed to treat mild cases of AMS. However, long-lasting and portable anti-hypoxia equipment for individual is not yet available. Methods Oxygen-increased respirator (OIR has been designed to reduce the risk of acute mountain sickness in acute exposure to low air pressure. It can increase the density of oxygen by increasing total atmospheric pressure in a mask. Male subjects were screened, and eighty-eight were qualified to perform the experiments. The subjects were divided into 5 groups and were involved in some of the tests at 4 different altitudes (Group 1, 2: 3700 m; Group 3,4,5: 4000 m, 4700 m, 5380 m with and without OIR. These tests include heart rate, saturation of peripheral oxygen (SpO2, malondialdehyde (MDA, superoxide dismutase (SOD, blood lactate (BLA and PWC (physical work capacity -170. Results The results showed that higher SpO2, lower heart rate (except during exercise and better recovery of heart rate were observed from all the subjects ’with OIR’ compared with ’without OIR’ (P Conclusions We suggested that OIR may play a useful role in protecting people ascending to high altitude before acclimatization.

  10. High doses of pseudoephedrine hydrochloride accelerate onset of CNS oxygen toxicity seizures in unanesthetized rats.

    Science.gov (United States)

    Pilla, R; Held, H E; Landon, C S; Dean, J B

    2013-08-29

    Pseudoephedrine (PSE) salts (hydrochloride and sulfate) are commonly used as nasal and paranasal decongestants by scuba divers. Anecdotal reports from the Divers Alert Network suggest that taking PSE prior to diving while breathing pure O₂ increases the risk for CNS oxygen toxicity (CNS-OT), which manifests as seizures. We hypothesized that high doses of PSE reduce the latency time to seizure (LS) in unanesthetized rats breathing 5 atmospheres absolute (ATA) of hyperbaric oxygen. Sixty-three male rats were implanted with radio-transmitters that recorded electroencephalogram activity and body temperature. After ≥7-day recovery, and 2 h before "diving", each rat was administered either saline solution (control) or PSE hydrochloride intragastrically at the following doses (mg PSE/kg): 0, 40, 80, 100, 120, 160, and 320. Rats breathed pure O₂ and were dived to 5ATA until the onset of behavioral seizures coincident with neurological seizures. LS was the time elapsed between reaching 5ATA and exhibiting seizures. We observed a significant dose-dependent decrease in the LS at doses of 100-320 mg/kg, whereas no significant differences in LS from control value were observed at doses ≤80 mg/kg. Our findings showed that high doses of PSE accelerate the onset of CNS-OT seizures in unanesthetized rats breathing 5ATA of poikilocapnic hyperoxia. Extrapolating our findings to humans, we conclude that the recommended daily dose of PSE should not be abused prior to diving with oxygen-enriched gas mixes or pure O₂.

  11. Effects of slow deep breathing at high altitude on oxygen saturation, pulmonary and systemic hemodynamics.

    Directory of Open Access Journals (Sweden)

    Grzegorz Bilo

    Full Text Available Slow deep breathing improves blood oxygenation (Sp(O2 and affects hemodynamics in hypoxic patients. We investigated the ventilatory and hemodynamic effects of slow deep breathing in normal subjects at high altitude. We collected data in healthy lowlanders staying either at 4559 m for 2-3 days (Study A; N = 39 or at 5400 m for 12-16 days (Study B; N = 28. Study variables, including Sp(O2 and systemic and pulmonary arterial pressure, were assessed before, during and after 15 minutes of breathing at 6 breaths/min. At the end of slow breathing, an increase in Sp(O2 (Study A: from 80.2±7.7% to 89.5±8.2%; Study B: from 81.0±4.2% to 88.6±4.5; both p<0.001 and significant reductions in systemic and pulmonary arterial pressure occurred. This was associated with increased tidal volume and no changes in minute ventilation or pulmonary CO diffusion. Slow deep breathing improves ventilation efficiency for oxygen as shown by blood oxygenation increase, and it reduces systemic and pulmonary blood pressure at high altitude but does not change pulmonary gas diffusion.

  12. Experimental measurement of the electrical conductivity of single crystal olivine at high temperature and high pressure under different oxygen fugacities

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    At 1.0-4.0 GPa and 1123-1473 K and under oxygen fugacity-controlled conditions (Ni + NiO, Fe + Fe3O4, Fe +FeO and Mo + MoO2 buffers), a YJ-3000t Model six-anvil solid high-pressure apparatus and a Sarltron-1260 Impedance/Gain-Phase analyzer were employed to conduct an in situ measurement of the electrical conductivity of single crystal olivine. Experimental results showed that: (1) within the range of experimentally selected frequencies (103-106 Hz), the electrical conductivity of the sample is of great dependence on the frequency; (2) with the rise of temperature (T), the electrical conductivity (σ) will increase, and the Arrenhius linear relationship is established between lgσ and 1/T; (3) under the control of oxygen buffer Fe + Fe3O4, with the rise of pressure, the electrical conductivity tends to decrease whereas the activation enthalpy and independent-of-temperature preexponential factor tend to increase,with the activation energy and activation volume of the sample estimated at ( 1.25 ± 0.08) eV and (0. 105 ± 0. 025) cm3/mol, respectively; (4) under given pressure and temperature conditions, the electrical conductivity tends to increase whereas the activation energy tends to decrease with increasing oxygen fugacity; and (5) the mechanism of electrical conduction of small polarons can provide insight into the behavior of electrical conduction of olivine under high pressure and high temperature.

  13. Maximal exercise and muscle oxygen extraction in acclimatizing lowlanders and high altitude natives

    DEFF Research Database (Denmark)

    Lundby, Carsten; Sander, Mikael; van Hall, Gerrit

    2006-01-01

    values obtained at sea level, the former values were almost completely restored to sea level values. This would suggest that the major determinant V(o2max)for not to increase with acclimatization is the observed reduction in maximal leg blood flow and O(2) conductance.......The tight relation between arterial oxygen content and maximum oxygen uptake (Vv(o2max)within a given person at sea level is diminished with altitude acclimatization. An explanation often suggested for this mismatch is impairment of the muscle O(2) extraction capacity with chronic hypoxia...... O(2) extraction at maximal exercise was 90.0+/-1.0% in the Danish lowlanders at sea level, and remained close to this value in all situations. In contrast to this, fractional arterial O(2) extraction was 83.2+/-2.8% in the high altitude natives, and did not change with the induction of normoxia...

  14. Interacting Carbon Nitride and Titanium Carbide Nanosheets for High-Performance Oxygen Evolution.

    Science.gov (United States)

    Ma, Tian Yi; Cao, Jian Liang; Jaroniec, Mietek; Qiao, Shi Zhang

    2016-01-18

    Free-standing flexible films, constructed from two-dimensional graphitic carbon nitride and titanium carbide (with MXene phase) nanosheets, display outstanding activity and stability in catalyzing the oxygen-evolution reaction in alkaline aqueous system, which originates from the Ti-N(x) motifs acting as electroactive sites, and the hierarchically porous structure with highly hydrophilic surface. With this excellent electrocatalytic ability, comparable to that of the state-of-the-art precious-/transition-metal catalysts and superior to that of most free-standing films reported to date, they are directly used as efficient cathodes in rechargeable zinc-air batteries. Our findings reveal that the rational interaction between different two-dimensional materials can remarkably promote the oxygen electrochemistry, thus boosting the entire clean energy system.

  15. High Stellar FUV/NUV Ratio and Oxygen Contents in the Atmospheres of Potentially Habitable Planets

    CERN Document Server

    Tian, Feng; Linsky, Jeffrey L; Mauas, Pablo J D; Vieytes, Mariela C

    2013-01-01

    Recent observations of several planet-hosting M dwarfs show that most have FUV/NUV flux ratios 1000 times greater than that of the Sun. Here we show that the atmospheric oxygen contents (O2 and O3) of potentially habitable planets in this type of UV environment could be 2~3 orders of magnitude greater than those of their counterparts around Sun-like stars as a result of decreased photolysis of O3, H2O2, and HO2. Thus detectable levels of atmospheric oxygen, in combination with the existence of H2O and CO2, may not be the most promising biosignatures on planets around stars with high FUV/NUV ratios such as the observed M dwarfs.

  16. High-Flow Nasal Interface Improves Oxygenation in Patients Undergoing Bronchoscopy

    Directory of Open Access Journals (Sweden)

    Umberto Lucangelo

    2012-01-01

    Full Text Available During bronchoscopy hypoxemia is commonly found and oxygen supply can be delivered by interfaces fed with high gas flows. Recently, the high-flow nasal cannula (HFNC has been introduced for oxygen therapy in adults, but they have not been used so far during bronchoscopy in adults. Forty-five patients were randomly assigned to 3 groups receiving oxygen: 40 L/min through a Venturi mask (V40, N=15, nasal cannula (N40, N=15, and 60 L/min through a nasal cannula (N60, N=15 during bronchoscopy. Gas exchange and circulatory variables were sampled before (FiO2 = 0.21, at the end of bronchoscopy (FiO2 = 0.5, and thereafter (V40, FiO2 = 0.35. In 8 healthy volunteers oxygen was randomly delivered according to V40, N40, and N60 settings, and airway pressure was measured. At the end of bronchoscopy, N60 presented higher PaO2, PaO2/FiO2, and SpO2 than V40 and N40 that did not differ between them. In the volunteers (N60 median airway pressure amounted to 3.6 cmH2O. Under a flow rate of 40 L/min both the Venturi mask and HFNC behaved similarly, but nasal cannula associated with a 60 L/min flow produced the better results, thus indicating its use in mild respiratory dysfunctions.

  17. Tetragonal zirconia polycrystals - a high performance solid oxygen ion conductor. [ZrO[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Weppner, W. (Max-Planck-Inst. fuer Festkoerperforschung, Stuttgart (Germany))

    1992-05-01

    The ionic conductivity of sintered pellets of tetragonal zirconia polycrystals (TZP) was found to be higher than that of cubic stabilized zirconia (CSZ) below about 700degC in spite of the lower concentration of defects. At 400degC the bulk conductivity is 1.2 X 10[sup -4] [Omega][sup -1] cm[sup -1] with an activation enthalpy of 0.92 eV. This shows that the mobility of the defects in TZP is about one order of magnitude higher than in CSZ. TZP pellets show high thermo-mechanical stability and may be readily sealed into glass tubes to provide gastight separate electrode compartments. Such an arrangement shows a fast response to variations of the oxygen partial pressure even at temperatures as low as 150degC. The correct Nernstian voltage is observed within about 1 s under reducing conditions and within a few minutes under oxidizing conditions. It may be assumed that the fast response even at low temperatures is related to the electronic properties of TZP. Investigations of the electronic behavior of the surface by work function measurements and of the minority charge carrier conductivities are reported as a function of the temperature and oxygen partial pressure. The evaluation of Hebb-Wagner polarization measurements has to be modified by considering the formation of internal electrical fields. It appears that TZP is very useful for fuel cells in view of both its thermo-mechanical stability and its favorable electrical properties at lower temperatures. Limiting-current oxygen sensors have been developed on the basis of this material which show superior performance compared with CSZ. Replacement of the gas diffusion barrier by a solid oxide allows high oxygen partial pressure to be measured.

  18. Numerical analysis of the effects of a high gradient magnetic field on flowing erythrocytes in a membrane oxygenator

    Science.gov (United States)

    Mitamura, Yoshinori; Okamoto, Eiji

    2015-04-01

    This study was carried out to clarify the effect of a high gradient magnetic field on pressure characteristics of blood in a hollow fiber membrane oxygenator in a solenoid coil by means of numerical analysis. Deoxygenated erythrocytes are paramagnetic, and oxygenated erythrocytes are diamagnetic. Blood changes its magnetic susceptibility depending on whether it is carrying oxygen or not. Motion of blood was analyzed by solving the continuous equation and the Navier-Stokes equation. It was confirmed that oxygenation of deoxygenated blood in the downstream side of the applied magnetic field was effective for pressure rise in a non-uniform magnetic field. The pressure rise was enhanced greatly by an increase in magnetic field intensity. The results suggest that a membrane oxygenator works as an actuator and there is a possibility of self-circulation of blood through an oxygenator in a non-uniform magnetic field.

  19. Growth of High TcYBaCuO Thin Films by Metalorganic Chemical Vapor Deposition

    Science.gov (United States)

    Kirlin, Peter S.; Binder, R.; Gardiner, R.; Brown, Duncan W.

    1990-03-01

    Thin films of YBa2Cu3O7-x were grown on MgO(100) by metalorganic chemical vapor deposition (MOCVD). Low pressure growth studies were carried out between 400 and 600°C using metal β-diketonate complexes as source reagents for Y, Ba, and Cu. As-deposited films were amorphous and a two stage annealing protocol was used in which fluorine was first removed in a Ar/H20 stream between 700 and 850°C, followed by calcination in flowing oxygen between 500 and 950°C. Scanning electron microscopy, X-ray diffraction and energy dispersive analysis indicate that good compositional and dimensional uniformity could be achieved. The temperature of the oxygen annealing step was shown to have a dramatic impact on the physical and electrical properties of the YBa2Cu307-x thin films. Annealing temperatures exceeding 910°C gave large crystallites and semiconducting resistivity above Tc; annealing temperatures below 910°C yielded films with metallic conductivity whose density and superconducting transition varied inversely with maximum annealing temperature. Optimized deposition/annealing protocols yielded films with a preferred c-axis orientation, R273/R100 ratios of 2, onsets as high as 94K and zero resistance exceeding 90K.

  20. A high-throughput chemically induced inflammation assay in zebrafish

    Directory of Open Access Journals (Sweden)

    Liebel Urban

    2010-12-01

    Full Text Available Abstract Background Studies on innate immunity have benefited from the introduction of zebrafish as a model system. Transgenic fish expressing fluorescent proteins in leukocyte populations allow direct, quantitative visualization of an inflammatory response in vivo. It has been proposed that this animal model can be used for high-throughput screens aimed at the identification of novel immunomodulatory lead compounds. However, current assays require invasive manipulation of fish individually, thus preventing high-content screening. Results Here we show that specific, noninvasive damage to lateral line neuromast cells can induce a robust acute inflammatory response. Exposure of fish larvae to sublethal concentrations of copper sulfate selectively damages the sensory hair cell population inducing infiltration of leukocytes to neuromasts within 20 minutes. Inflammation can be assayed in real time using transgenic fish expressing fluorescent proteins in leukocytes or by histochemical assays in fixed larvae. We demonstrate the usefulness of this method for chemical and genetic screens to detect the effect of immunomodulatory compounds and mutations affecting the leukocyte response. Moreover, we transformed the assay into a high-throughput screening method by using a customized automated imaging and processing system that quantifies the magnitude of the inflammatory reaction. Conclusions This approach allows rapid screening of thousands of compounds or mutagenized zebrafish for effects on inflammation and enables the identification of novel players in the regulation of innate immunity and potential lead compounds toward new immunomodulatory therapies. We have called this method the chemically induced inflammation assay, or ChIn assay. See Commentary article: http://www.biomedcentral.com/1741-7007/8/148.

  1. A new extension of the polarizable continuum model: Toward a quantum chemical description of chemical reactions at extreme high pressure.

    Science.gov (United States)

    Cammi, Roberto

    2015-11-15

    A quantum chemical method for studying potential energy surfaces of reactive molecular systems at extreme high pressures is presented. The method is an extension of the standard Polarizable Continuum Model that is usually used for Quantum Chemical study of chemical reactions at a standard condition of pressure. The physical basis of the method and the corresponding computational protocol are described in necessary detail, and an application of the method to the dimerization of cyclopentadiene (up to 20 GPa) is reported.

  2. Highly dispersed TaOx nanoparticles prepared by electrodeposition as oxygen reduction electrocatalysts for polymer electrolyte fuel cells

    KAUST Repository

    Seo, Jeongsuk

    2013-06-06

    Based on the chemical stability of group IV and V elements in acidic solutions, TaOx nanoparticles prepared by electrodeposition in an ethanol-based Ta plating bath at room temperature were investigated as novel nonplatinum electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs). Electrodeposition conditions of Ta complexes and subsequent various heat treatments for the deposited TaOx were examined for the best performance of the ORR. TaOx particles on carbon black (CB), electrodeposited at a constant potential of -0.5 V Ag/AgCl for 10 s and then heat-treated by pure H2 flow at 523 K for 1 h, showed excellent catalytic activity with an onset potential of 0.93 VRHE (for 2 μA cm-2) for the ORR. Surface characterizations of the catalysts were performed by scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The loading amounts of the electrodeposited material on the CB were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). All the physical results suggested that high dispersion of TaOx particles on the CB surface with 2-3 nm size was critical and key for high activity. The chemical identity and modified surface structure for the deposited TaOx catalysts before and after H 2 heat treatment were analyzed by X-ray photoelectron spectroscopy (XPS). The formation of more exposed active sites on the electrode surface and enhanced electroconductivity of the tantalum oxide promoted from the H 2 treatment greatly improved the ORR performance of the electrodeposited TaOx nanoparticles on CB. Finally, the highly retained ORR activity after an accelerated durability test in an acidic solution confirmed and proved the chemical stability of the oxide nanoparticles. The high utilization of the electrodeposited TaOx nanoparticles uniformly dispersed on CB for the ORR was comparable to that of commercial Pt/CB catalysts

  3. Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS for the measurement of atmospherically significant oxygenated volatile organic compounds

    Directory of Open Access Journals (Sweden)

    K. P. Wyche

    2007-01-01

    Full Text Available The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence supported oxygenated volatile organic compound (OVOC measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0–0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+ as the primary chemical ionization (CI reagent in order to facilitate proton transfer to the analyte OVOCs. The results presented show that the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs at mixing ratios of around 10 ppbV in "real-time" (i.e. detection on the one-minute time scale, with sub-ppbV measurement also achieved following an increase in averaging time to tens of minutes. It is shown that in general OVOC measurement is made with high accuracy and precision, with integration time, mixing ratio and compound dependent values as good as 4–13% and 3–15% respectively. It is demonstrated that CIR-TOF-MS has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurement.

  4. Electrochemically fabricated polypyrrole-cobalt-oxygen coordination complex as high-performance lithium-storage materials.

    Science.gov (United States)

    Guo, Bingkun; Kong, Qingyu; Zhu, Ying; Mao, Ya; Wang, Zhaoxiang; Wan, Meixiang; Chen, Liquan

    2011-12-23

    Current lithium-ion battery (LIB) technologies are all based on inorganic electrode materials, though organic materials have been used as electrodes for years. Disadvantages such as limited thermal stability and low specific capacity hinder their applications. On the other hand, the transition metal oxides that provide high lithium-storage capacity by way of electrochemical conversion reaction suffer from poor cycling stability. Here we report a novel high-performance, organic, lithium-storage material, a polypyrrole-cobalt-oxygen (PPy-Co-O) coordination complex, with high lithium-storage capacity and excellent cycling stability. Extended X-ray absorption fine structure and Raman spectroscopy and other physical and electrochemical characterizations demonstrate that this coordination complex can be electrochemically fabricated by cycling PPy-coated Co(3)O(4) between 0.0 V and 3.0 V versus Li(+)/Li. Density functional theory (DFT) calculations indicate that each cobalt atom coordinates with two nitrogen atoms within the PPy-Co coordination layer and the layers are connected with oxygen atoms between them. Coordination weakens the C-H bonds on PPy and makes the complex a novel lithium-storage material with high capacity and high cycling stability.

  5. Oxygen stabilization induced enhancement in superconducting characteristics of high-Tc oxides

    Science.gov (United States)

    Wu, M. K.; Chen, J. T.; Huang, C. Y.

    1991-01-01

    In an attempt to enhance the electrical and mechanical properties of the high temperature superconducting oxides, high T(sub c) composites were prepared composed of the 123 compounds and AgO. The presence of extra oxygen due to the decomposition of AgO at high temperature is found to stabilize the superconducting 123 phase. Ag is found to serve as clean flux for grain growth and precipitates as pinning center. Consequently, almost two orders of magnitude enhancement in critical current densities were also observed in these composites. In addition, these composites also show much improvement in workability and shape formation. On the other hand, proper oxygen treatment of Y5Ba6Cu11Oy was found to possibly stabilize superconducting phase with T(sub c) near 250 K. I-V, ac susceptibility, and electrical resistivity measurements indicate the existence of this ultra high T(sub c) phase in this compound. Detailed structure, microstructure, electrical, magnetic and thermal studies of the superconducting composites and the ultra high T(sub c) compound are presented and discussed.

  6. High cell density fed-batch fermentations for lipase production: feeding strategies and oxygen transfer.

    Science.gov (United States)

    Salehmin, M N I; Annuar, M S M; Chisti, Y

    2013-11-01

    This review is focused on the production of microbial lipases by high cell density fermentation. Lipases are among the most widely used of the enzyme catalysts. Although lipases are produced by animals and plants, industrial lipases are sourced almost exclusively from microorganisms. Many of the commercial lipases are produced using recombinant species. Microbial lipases are mostly produced by batch and fed-batch fermentation. Lipases are generally secreted by the cell into the extracellular environment. Thus, a crude preparation of lipases can be obtained by removing the microbial cells from the fermentation broth. This crude cell-free broth may be further concentrated and used as is, or lipases may be purified from it to various levels. For many large volume applications, lipases must be produced at extremely low cost. High cell density fermentation is a promising method for low-cost production: it allows a high concentration of the biomass and the enzyme to be attained rapidly and this eases the downstream recovery of the enzyme. High density fermentation enhances enzyme productivity compared with the traditional submerged culture batch fermentation. In production of enzymes, a high cell density is generally achieved through fed-batch operation, not through perfusion culture which is cumbersome. The feeding strategies used in fed-batch fermentations for producing lipases and the implications of these strategies are discussed. Most lipase-producing microbial fermentations require oxygen. Oxygen transfer in such fermentations is discussed.

  7. Chemical conversion of self-assembled hexadecyl monolayers with active oxygen species generated by vacuum ultraviolet irradiation in an atmospheric environment.

    Science.gov (United States)

    Soliman, Ahmed I A; Ichii, Takashi; Utsunomiya, Toru; Sugimura, Hiroyuki

    2015-07-28

    Vacuum ultraviolet (VUV, λ = 172 nm) irradiation of alkyl self-assembled monolayers (SAMs) in the presence of dry air alters their surface properties. In this work, UV photochemically prepared hexadecyl (HD)-SAMs on hydrogen-terminated silicon substrates were irradiated by VUV light in dry air, which generated active oxygen species upon excitation of the atmospheric oxygen molecules. These active oxygen species converted the terminal methyl groups of the SAMs to polar functional groups, which were examined quantitatively by X-ray photoelectron spectroscopy (XPS) and chemical labeling. At the first stage of VUV irradiation, the surface of SAMs was functionalized, and the ratios of the generated polar functional groups markedly increased. With the elongation of the irradiation period, the SAMs gradually degraded, and the total polar group percentages gradually decreased. The difference between the oxygenated carbon components derived by the deconvolution of the XPS carbon (C1s) spectrum and the chemical labeling of polar groups revealed enormous quantities of ethereal and ester groups that cannot react with the labeling reagents but are included in the C1s spectral envelope. These modifications were reflected on morphological structures of SAMs, which were gradually distorted until a complete amorphous structure was obtained after the complete elimination of HD-SAMs.

  8. Optimization and application of atmospheric pressure chemical and photoionization hydrogen-deuterium exchange mass spectrometry for speciation of oxygen-containing compounds.

    Science.gov (United States)

    Acter, Thamina; Kim, Donghwi; Ahmed, Arif; Jin, Jang Mi; Yim, Un Hyuk; Shim, Won Joon; Kim, Young Hwan; Kim, Sunghwan

    2016-05-01

    This paper presents a detailed investigation of the feasibility of optimized positive and negative atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and atmospheric pressure photoionization (APPI) MS coupled to hydrogen-deuterium exchange (HDX) for structural assignment of diverse oxygen-containing compounds. The important parameters for optimization of HDX MS were characterized. The optimized techniques employed in the positive and negative modes showed satisfactory HDX product ions for the model compounds when dichloromethane and toluene were employed as a co-solvent in APCI- and APPI-HDX, respectively. The evaluation of the mass spectra obtained from 38 oxygen-containing compounds demonstrated that the extent of the HDX of the ions was structure-dependent. The combination of information provided by different ionization techniques could be used for better speciation of oxygen-containing compounds. For example, (+) APPI-HDX is sensitive to compounds with alcohol, ketone, or aldehyde substituents, while (-) APPI-HDX is sensitive to compounds with carboxylic functional groups. In addition, the compounds with alcohol can be distinguished from other compounds by the presence of exchanged peaks. The combined information was applied to study chemical compositions of degraded oils. The HDX pattern, double bond equivalent (DBE) distribution, and previously reported oxidation products were combined to predict structures of the compounds produced from oxidation of oil. Overall, this study shows that APCI- and APPI-HDX MS are useful experimental techniques that can be applied for the structural analysis of oxygen-containing compounds.

  9. An experimental data base for material selection and design of high-speed, high-pressure, oxygen turbomachinery

    Science.gov (United States)

    Schoenman, L.; Stoltzfus, J. M.

    1985-01-01

    New technologies for space-based, reusable, throttleable, cryogenic, orbit transfer propulsion are being evaluated. A variable-thrust (200 to 3000 lbF), 2000 psi chamber pressure, LO2/LH2 engine has been selected to demonstrate the 20-hour, 500-restart life goal, and a specific impulse of 480 lbF-sec/lbM. The advanced design uses warm oxygen to power a fully integrated turbopump that delivers 4500 psi LO2. The selected engine cycle provides the following advantages over conventional expander cycle designs which use H2 to drive the LH2 and LO2 pumps; higher engine operating pressures and performance in a smaller envelope, lower turbine operating temperatures, elimination of interpropellant seals and purges, and an extended throttling range. The design approach and results of testing to characterize materials for use in high-pressure gaseous oxygen are discussed. Test methods include particle impact testing in a sonic-flow, hot GO2 streams and forced, high-speed friction rubbing testing. Materials are exposed to oxygen and nitrogen atmospheres at pressures of 100, 1000, and 3000 psi to identify separately the gas cooling effects from the metal oxidation effects at the rubbing surface. The selection of candidate design materials is based on an analytical parameter defined as the burn factor. Typical materials tested include carbon steel, stainless steel, nickel, copper, and monel alloys.

  10. High fluence laser irradiation induces reactive oxygen species generation in human lung adenocarcinoma cells

    Science.gov (United States)

    Wang, Fang; Xing, Da; Chen, Tong-Sheng

    2006-09-01

    Low-power laser irradiation (LPLI) has been used for therapies such as curing spinal cord injury, healing wound et al. Yet, the mechanism of LPLI remains unclear. Our previous study showed that low fluences laser irradiation induces human lung adenocarcinoma cells (ASTC-a-1) proliferation, but high fluences induced apoptosis and caspase-3 activation. In order to study the mechanism of apoptosis induced by high fluences LPLI further, we have measured the dynamics of generation of reactive oxygen species (ROS) using H IIDCFDA fluorescence probes during this process. ASTC-a-1 cells apoptosis was induced by He-Ne laser irradiation at high fluence of 120J/cm2. A confocal laser scanning microscope was used to perform fluorescence imaging. The results demonstrated that high fluence LPLI induced the increase of mitochondria ROS. Our studies contribute to clarify the biological mechanism of high fluence LPLI-induced cell apoptosis.

  11. Effect of spent cotton stalks on color removal and chemical oxygen demand lowering in olive oil mill wastewater by white rot fungi.

    Science.gov (United States)

    Kahraman, S; Yeşilada, O

    1999-01-01

    Wastewater from olive oil mill was decolorized (and its chemical oxygen demand reduced in static cultivation) using the fungi Coriolus versicolor, Funalia trogii, Phanerochaete chrysosporium and Pleurotus sajor-caju. The effect of cotton stalk on decolorizing and COD removing capability was demonstrated. P. chrysosporium (in 20% medium with cotton stalk) reduced the COD by 48% and color by 58%, F. trogii (in 30% medium with cotton stalk)) by 51 and 55%, respectively.

  12. A primordial origin for molecular oxygen in comets: A chemical kinetics study of the formation and survival of O$_2$ ice from clouds to disks

    CERN Document Server

    Taquet, Vianney; Walsh, Catherine; van Dishoeck, Ewine F

    2016-01-01

    Molecular oxygen has been confirmed as the fourth most abundant molecule in cometary material O$_2$/H$_2$O $\\sim 4$ %) and is thought to have a primordial nature, i.e., coming from the interstellar cloud from which our solar system was formed. However, interstellar O$_2$ gas is notoriously difficult to detect and has only been observed in one potential precursor of a solar-like system. Here, the chemical and physical origin of O$_2$ in comets is investigated using sophisticated astrochemical models. Three origins are considered: i) in dark clouds, ii) during forming protostellar disks, and iii) during luminosity outbursts in disks. The dark cloud models show that reproduction of the observed abundance of O$_2$ and related species in comet 67P/C-G requires a low H/O ratio facilitated by a high total density ($\\geq 10^5$ cm$^{-3}$), and a moderate cosmic ray ionisation rate ($\\leq 10^{-16}$ s$^{-1}$) while a temperature of 20 K, slightly higher than the typical temperatures found in dark clouds, also enhances t...

  13. Clinical evidence on high flow oxygen therapy and active humidification in adults.

    Science.gov (United States)

    Gotera, C; Díaz Lobato, S; Pinto, T; Winck, J C

    2013-01-01

    Recently there has been growing interest in an alternative to conventional oxygen therapy: the heated, humidified high flow nasal cannula oxygen therapy (HFNC). A number of physiological effects have been described with HFNC: pharyngeal dead space washout, reduction of nasopharyngeal resistance, a positive expiratory pressure effect, an alveolar recruitment, greater humidification, more comfort and better tolerance by the patient, better control of FiO2 and mucociliary clearance. There is limited experience of HFNC in adults. There are no established guidelines or decision-making pathways to guide use of the HFNC therapy for adults. In this article we review the existing evidence of HFNC oxygen therapy in adult patients, its advantages, limitations and the current literature on clinical applications. Further research is required to determine the long-term effect of this therapy and identify the adult patient population to whom it is most beneficial. Copyright © 2013 Sociedade Portuguesa de Pneumologia. Published by Elsevier España. All rights reserved.

  14. Hierarchically porous carbons with optimized nitrogen doping as highly active electrocatalysts for oxygen reduction

    Science.gov (United States)

    Liang, Hai-Wei; Zhuang, Xiaodong; Brüller, Sebastian; Feng, Xinliang; Müllen, Klaus

    2014-09-01

    Development of efficient, low-cost and stable electrocatalysts as the alternative to platinum for the oxygen reduction reaction is of significance for many important electrochemical devices, such as fuel cells, metal-air batteries and chlor-alkali electrolysers. Here we report a highly active nitrogen-doped, carbon-based, metal-free oxygen reduction reaction electrocatalyst, prepared by a hard-templating synthesis, for which nitrogen-enriched aromatic polymers and colloidal silica are used as precursor and template, respectively, followed by ammonia activation. Our protocol allows for the simultaneous optimization of both porous structures and surface functionalities of nitrogen-doped carbons. Accordingly, the prepared catalysts show the highest oxygen reduction reaction activity (half-wave potential of 0.85 V versus reversible hydrogen electrode with a low loading of 0.1 mg cm-2) in alkaline media among all reported metal-free catalysts. Significantly, when used for constructing the air electrode of zinc-air battery, our metal-free catalyst outperforms the state-of the-art platinum-based catalyst.

  15. Oxygen potential in the rim region of high burnup UO 2 fuel

    Science.gov (United States)

    Matzke, Hj.

    1994-01-01

    Small specimens from the rim region (fuel surface) of a UO 2 fuel rod with an average burnup of 7.6% FIMA were analysed in a miniaturized galvanic cell to determine their oxygen potential Δ Ḡ(O 2) . These fuel pieces represented the porous rim structure with very small grains known to be formed near the periphery of high burnup UO 2 fuel pellets. The oxygen potential of the rim material was very low, corresponding to that of unirradiated stoichiometric UO 2, or to that of slightly substoichiometric UO 2 containing rare earth fission products. No indication of oxidation due to fission was found, though most fission was that of Pu. Measurements on pieces from the inner, unrestructured fuel showed somewhat higher oxygen potentials corresponding to those of very slightly substoichiometric fuel if allowance is made for the incorporation of rare earths. These results are in contrast to some generally accepted ideas of burnup effects, and the possible reasons and implications are discussed.

  16. An integrated chemical and oxygen isotopic study of primitive olivine grains in picrites from the Emeishan Large Igneous Province, SW China: Evidence for oxygen isotope heterogeneity in mantle sources

    Science.gov (United States)

    Yu, Song-Yue; Shen, Neng-Ping; Song, Xie-Yan; Ripley, Edward M.; Li, Chusi; Chen, Lie-Meng

    2017-10-01

    Recognition of the nature of potential mantle sources of continental flood basalts is complicated by possible overprinting related to crustal contamination as magmas migrate to the surface (Arndt and Christensen, 1992). However, in picritic lava flows primitive olivine phenocrysts that formed early in the crystallization sequence can potentially provide unperturbed information of their mantle source. We have carried out an integrated chemical and oxygen isotopic (in situ SIMS) study of primitive olivine grains (Fo ranging from 88 to 92.6 mol%) in the Emeishan picrites at different locations (Wulongba, Wuguijing, Tanglanghe and Maoniuping). We use these data to evaluate the geochemical nature of mantle sources for magmas from which the primitive olivine crystallized. The primitive olivine grains in the samples from Maoniuping, Wuguijing and Tanglanghe are characterized by mantle-like δ18O values (mean values are 5.1 ± 0.3‰ (2σ, n = 53), 5.2 ± 0.3‰ (2σ, n = 122) and 5.3 ± 0.3‰ (n = 25), respectively) coupled with generally low Fo contents (mean values are 88.7 ± 1.4 mol% (2σ, n = 53), 89.8 ± 1.8 mol% (2σ, n = 122) and 89.4 ± 1.8 mol% (2σ, n = 25), respectively). In contrast, the olivine grains in the samples from Wulongba are characterized by elevated δ18O values (mean = 5.6 ± 0.3‰ (2σ, n = 58)) coupled with generally higher Fo contents (mean = 91 ± 2.8 mol% (2σ, n = 58)) than primitive olivine in the samples from the other locations. Based on olivine compositions, primitive olivine in picrites from Maoniuping, Tanglanghe and Wuguijing are consistent with derivation from hybrid mantle sources containing similar proportions of peridotite and pyroxenite/eclogite components. The δ18O values of these primitive olivine grains are consistent with melting of plume source materials. The chemical composition of the primitive olivine from Wulongba are also consistent with derivation from a hybrid peridotite/pyroxenite source, but the high δ18O values

  17. Determination of the relative resistance to ignition of selected turbopump materials in high-pressure, high-temperature, oxygen environments, volume 1

    Science.gov (United States)

    Stoltzfus, Joel M.; Benz, Frank J.

    1986-01-01

    Advances in the design of the liquid oxygen, liquid hydrogen engines for the Space Transportation System call for the use of warm, high-pressure oxygen as the driving gas in the liquid oxygen turbopump. The NASA Lewis Research Center requested the NASA White Sands Test Facility (WSTF) to design a test program to determine the relative resistance to ignition of nine selected turbopump materials: Hastelloy X, Inconel 600, Invar 36, Monel K-500, nickel 200, silicon carbide, stainless steel 316, and zirconium copper. The materials were subjected to particle impact and to frictional heating in high-pressure oxygen.

  18. Observations of atmospheric chemical deposition to high Arctic snow

    Science.gov (United States)

    Macdonald, Katrina M.; Sharma, Sangeeta; Toom, Desiree; Chivulescu, Alina; Hanna, Sarah; Bertram, Allan K.; Platt, Andrew; Elsasser, Mike; Huang, Lin; Tarasick, David; Chellman, Nathan; McConnell, Joseph R.; Bozem, Heiko; Kunkel, Daniel; Duan Lei, Ying; Evans, Greg J.; Abbatt, Jonathan P. D.

    2017-05-01

    Rapidly rising temperatures and loss of snow and ice cover have demonstrated the unique vulnerability of the high Arctic to climate change. There are major uncertainties in modelling the chemical depositional and scavenging processes of Arctic snow. To that end, fresh snow samples collected on average every 4 days at Alert, Nunavut, from September 2014 to June 2015 were analyzed for black carbon, major ions, and metals, and their concentrations and fluxes were reported. Comparison with simultaneous measurements of atmospheric aerosol mass loadings yields effective deposition velocities that encompass all processes by which the atmospheric species are transferred to the snow. It is inferred from these values that dry deposition is the dominant removal mechanism for several compounds over the winter while wet deposition increased in importance in the fall and spring, possibly due to enhanced scavenging by mixed-phase clouds. Black carbon aerosol was the least efficiently deposited species to the snow.

  19. Chemical-looping gasification of biomass in a 10k Wth interconnected fluidized bed reactor using Fe2 O3/Al2 O3 oxygen carrier

    Institute of Scientific and Technical Information of China (English)

    HUSEYIN Sozen; WEI Guo-qiang; LI Hai-bin; HE Fang; HUANG Zhen

    2014-01-01

    The aim of this research is to design and operate a 10 kW hot chemical-looping gasification ( CLG) unit using Fe2 O3/Al2 O3 as an oxygen carrier and saw dust as a fuel. The effect of the operation temperature on gas composition in the air reactor and the fuel reactor, and the carbon conversion of biomass to CO2 and CO in the fuel reactor have been experimentally studied. A total 60 h run has been obtained with the same batch of oxygen carrier of iron oxide supported with alumina. The results show that CO and H2 concentrations are increased with increasing temperature in the fuel reactor. It is also found that with increasing fuel reactor temperature, both the amount of residual char in the fuel reactor and CO2 concentration of the exit gas from the air reactor are degreased. Carbon conversion rate and gasification efficiency are increased by increasing temperature and H2 production at 870 ℃reaches the highest rate. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET-surface area tests have been used to characterize fresh and reacted oxygen carrier particles. The results display that the oxygen carrier activity is not declined and the specific surface area of the oxygen carrier particles is not decreased significantly.

  20. High-CHO diet increases post-exercise oxygen consumption after a supramaximal exercise bout.

    Science.gov (United States)

    Ferreira, G A; Bertuzzi, R; De-Oliveira, F R; Pires, F O; Lima-Silva, A E

    2016-10-24

    We investigated if carbohydrate (CHO) availability could affect the excess post-exercise oxygen consumption (EPOC) after a single supramaximal exercise bout. Five physically active men cycled at 115% of peak oxygen uptake (V̇O2 peak) until exhaustion with low or high pre-exercise CHO availability. The endogenous CHO stores were manipulated by performing a glycogen-depletion exercise protocol 48 h before the trial, followed by 48 h consuming either a low- (10% CHO) or a high-CHO (80% CHO) diet regime. Compared to the low-CHO diet, the high-CHO diet increased time to exhaustion (3.0±0.6 min vs 4.4±0.6, respectively, P=0.01) and the total O2 consumption during the exercise (6.9±0.9 L and 11.3±2.1, respectively, P=0.01). This was accompanied by a higher EPOC magnitude (4.6±1.8 L vs 6.2±2.8, respectively, P=0.03) and a greater total O2 consumption throughout the session (exercise+recovery: 11.5±2.5 L vs 17.5±4.2, respectively, P=0.01). These results suggest that a single bout of supramaximal exercise performed with high CHO availability increases both exercise and post-exercise energy expenditure.

  1. High-CHO diet increases post-exercise oxygen consumption after a supramaximal exercise bout

    Science.gov (United States)

    Ferreira, G.A.; Bertuzzi, R.; De-Oliveira, F.R.; Pires, F.O.; Lima-Silva, A.E.

    2016-01-01

    We investigated if carbohydrate (CHO) availability could affect the excess post-exercise oxygen consumption (EPOC) after a single supramaximal exercise bout. Five physically active men cycled at 115% of peak oxygen uptake (V̇O2 peak) until exhaustion with low or high pre-exercise CHO availability. The endogenous CHO stores were manipulated by performing a glycogen-depletion exercise protocol 48 h before the trial, followed by 48 h consuming either a low- (10% CHO) or a high-CHO (80% CHO) diet regime. Compared to the low-CHO diet, the high-CHO diet increased time to exhaustion (3.0±0.6 min vs 4.4±0.6, respectively, P=0.01) and the total O2 consumption during the exercise (6.9±0.9 L and 11.3±2.1, respectively, P=0.01). This was accompanied by a higher EPOC magnitude (4.6±1.8 L vs 6.2±2.8, respectively, P=0.03) and a greater total O2 consumption throughout the session (exercise+recovery: 11.5±2.5 L vs 17.5±4.2, respectively, P=0.01). These results suggest that a single bout of supramaximal exercise performed with high CHO availability increases both exercise and post-exercise energy expenditure. PMID:27783812

  2. Physical and chemical performances of high Al steels

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-chuan; DONG Yuan-chi; ZHANG Wen-ming; WANG Shi-jun; ZHOU Yun

    2005-01-01

    The effects of acid-soluble Al content on the physical and chemical performances of high Al steels were investigated. The results show that the distribution of acid-soluble Al in steel substrate is uniform. With increasing Al content, the strength and toughness of steels decrease a little but the hardness increases. The average yield strength and tensile strength are 425 MPa and 570 MPa, respectively, and the Rockwell hardness is 89.7. For non-Al steels the average oxidation rate is up to 0.421 mg/(cm2·h) at 1 373 K. For high Al steels, when the mass fraction of Al is less than 5%, there is a thinner gray oxidized layer on surface and the oxidation rate is high; when the mass fraction of Al is more than 8.0%, the thin, close and yellow glossing film still exists, and the average oxidation rate is only 0.016 mg/(cm2·h).

  3. Oxygen rich titania: a dopant free, high temperature stable, and visible-light active anatase photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Etacheri, Vinodkumar; Pillai, Suresh C. [Centre for Research in Engineering Surface Technology (CREST), FOCAS Institute, Dublin Institute of Technology, Camden Row, Dublin 8 (Ireland); Seery, Michael K. [School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8 (Ireland); Hinder, Steven J. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom)

    2011-10-07

    The simultaneous existence of visible light photocatalytic activity and high temperature anatase phase stability up to 900 C in undoped TiO{sub 2} is reported for the first time. These properties are achieved by the in-situ generation of oxygen through the thermal decomposition of peroxo-titania complex (formed by the precursor modification with H{sub 2}O{sub 2}). Titania containing the highest amount of oxygen (16 H{sub 2}O{sub 2}-TiO{sub 2}) retains 100% anatase phase even at 900 C, where as the control sample exists as 100% rutile at this temperature. The same composition exhibits a six-fold and two-fold increase in visible light photocatalytic activities in comparison to the control sample and the standard photocatalyst Degussa P-25 respectively. Among the various para-meters affecting the photocatalytic action, such as band gap narrowing, textural properties, crystallite size, and anatase phase stability, band gap narrowing was identified as the major factor responsible for the visible light photocatalytic activity. Increased Ti-O-Ti bond strength and upward shifting of the valence band (VB) maximum, which is responsible for the high temperature stability and visible light activity respectively, are identified from FT-IR, XPS, and photoluminescence (PL) spectroscopic studies. It is therefore proposed that the oxygen excess defects present in these titania samples are responsible for the high temperature stability and enhanced visible light photocatalytic activities. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Ability of the aquatic fern Azolla to remove chemical oxygen demand and polyphenols from olive mill wastewater

    Directory of Open Access Journals (Sweden)

    Sacchi, Angelo

    2007-03-01

    Full Text Available We investigated the biofiltration ability of the aquatic fern Azolla to remove polyphenols and chemical oxygen demand (COD from olive mill wastewater (OMWw collected from the traditional (TS and continuous (CS extraction systems. Azolla biomass was packed into five sequential Imhoff cones and five sequential columns. In both experiments, the filtrates collected from the 5th biofilter showed a decrease in polyphenol contents: from 7650 mg l–1 to 3610 mg l–1 in TS OMWw and from 3852 mg l–1 to 1351 mg l–1 in CS OMWw. The COD contents decreased from 110200 mg L–1 to 52400 mg L–1 in TS OMWw and from 41600 mg L–1 to 2300 mg L–1 in CS OMWw. A 5:1 OMWw to Azolla-fresh-weight ratio was optimal for both polyphenol and COD removal. The biofiltration ability of alfalfa was compared with that of Azolla, but the treatment with alfalfa did not result in the reduction of COD or polyphenols.La eficacia del helecho de agua azolla para eliminar polifenoles y reducir la demanda química de oxígeno (DQO de los alpechines obtenidos en el proceso de obtención tradicional y continuo del aceite de oliva, fue investigado mediante ensayos de filtración. Cinco conos secuenciales de Imhoff y cinco columnas secuenciales se rellenaron de biomasa de Azolla. En ambos experimentos, el filtrado procedente de la quinta extracción mostró una disminución en el contenido de polifenoles de 7650 mg L–1 a 3610 mg L–1en el alpechín obtenido mediante el sistema tradicional y de 3852 mg L–1 a 1351 mg L–1en el alpechín del sistema continuo. La demanda química de oxígeno del alpechín del sistema tradicional disminuyó de 110200 mg L–1 a 52400 mg L–1 en y de 41600 mg L–1a 2300 mg L–1en el procedente del sistema continuo. Una proporción en peso 5:1 de alpechín: Azolla fue la óptima tanto para la reducción de los polifenoles como para la de la DQO. La eficiencia del tratamiento biológico con alfalfa se comparó con la obtenida con Azolla. Los

  5. Characterizing the Chemical Stability of High Temperature Materials for Application in Extreme Environments

    Science.gov (United States)

    Opila, Elizabeth

    2005-01-01

    The chemical stability of high temperature materials must be known for use in the extreme environments of combustion applications. The characterization techniques available at NASA Glenn Research Center vary from fundamental thermodynamic property determination to material durability testing in actual engine environments. In this paper some of the unique techniques and facilities available at NASA Glenn will be reviewed. Multiple cell Knudsen effusion mass spectrometry is used to determine thermodynamic data by sampling gas species formed by reaction or equilibration in a Knudsen cell held in a vacuum. The transpiration technique can also be used to determine thermodynamic data of volatile species but at atmospheric pressures. Thermodynamic data in the Si-O-H(g) system were determined with this technique. Free Jet Sampling Mass Spectrometry can be used to study gas-solid interactions at a pressure of one atmosphere. Volatile Si(OH)4(g) was identified by this mass spectrometry technique. A High Pressure Burner Rig is used to expose high temperature materials in hydrocarbon-fueled combustion environments. Silicon carbide (SiC) volatility rates were measured in the burner rig as a function of total pressure, gas velocity and temperature. Finally, the Research Combustion Lab Rocket Test Cell is used to expose high temperature materials in hydrogen/oxygen rocket engine environments to assess material durability. SiC recession due to rocket engine exposures was measured as a function of oxidant/fuel ratio, temperature, and total pressure. The emphasis of the discussion for all techniques will be placed on experimental factors that must be controlled for accurate acquisition of results and reliable prediction of high temperature material chemical stability.

  6. Chemical and microstructural study of the oxygen passivation behaviour of nanocrystalline Mg and MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Friedrichs, O. [Instituto de Ciencia de Materiales de Sevilla (CSIC-University of Seville), Centro de Investigaciones Cientificas ' Isla de la Cartuja' , Avda. Americo Vespucio 49, 41092 Seville (Spain); Sanchez-Lopez, J.C. [Instituto de Ciencia de Materiales de Sevilla (CSIC-University of Seville), Centro de Investigaciones Cientificas ' Isla de la Cartuja' , Avda. Americo Vespucio 49, 41092 Seville (Spain); Lopez-Cartes, C. [Instituto de Ciencia de Materiales de Sevilla (CSIC-University of Seville), Centro de Investigaciones Cientificas ' Isla de la Cartuja' , Avda. Americo Vespucio 49, 41092 Seville (Spain); Dornheim, M. [Department of Materials Research, Institute for Materials Research, GKSS Research Centre, Geesthacht GmbH, D-21502 Geesthacht (Germany); Klassen, T. [Department of Materials Research, Institute for Materials Research, GKSS Research Centre, Geesthacht GmbH, D-21502 Geesthacht (Germany); Bormann, R. [Department of Materials Research, Institute for Materials Research, GKSS Research Centre, Geesthacht GmbH, D-21502 Geesthacht (Germany); Fernandez, A. [Instituto de Ciencia de Materiales de Sevilla (CSIC-University of Seville), Centro de Investigaciones Cientificas ' Isla de la Cartuja' , Avda. Americo Vespucio 49, 41092 Seville (Spain)]. E-mail: asuncion@icmse.csic.es

    2006-01-15

    Nanocrystalline Mg and MgH{sub 2} samples have been prepared by high-energy ball milling and gas phase condensation methods. Starting from these materials in their 'as received' state without air exposure, a study of the oxygen and air passivation behaviour was carried out by 'in situ' analysis of the samples by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The binding energy and photoemission Auger parameters have been determined for metallic magnesium as well as for magnesium hydride, oxide and hydroxide species. Values of the MgH{sub 2} material were reported for the first time. The study clearly shows the formation of an oxide passivation layer of ca. 3-4 nm in thickness for all the nanocrystalline magnesium samples handled under controlled inert gas atmospheres. A hydroxide like amorphous layer is formed at the topmost surface layers of the nanocrystalline Mg and MgH{sub 2} samples. The implication of these studies for H{sub 2} storage and transport applications of nanocrystalline magnesium is discussed.

  7. Oxygen Abundances in Nearby FGK Stars and the Galactic Chemical Evolution of the Local Disk and Halo

    CERN Document Server

    Ramirez, I; Lambert, D L

    2013-01-01

    Atmospheric parameters and oxygen abundances of 825 nearby FGK stars are derived using high-quality spectra and a non-LTE analysis of the 777 nm O I triplet lines. We assign a kinematic probability for the stars to be thin-disk (P1), thick-disk (P2), and halo (P3) members. We confirm previous findings of enhanced [O/Fe] in thick-disk (P2>0.5) relative to thin-disk (P1>0.5) stars with [Fe/H]-0.2. Nevertheless, we find that the kinematic membership criterion fails at separating perfectly the stars in the [O/Fe]-[Fe/H] plane, even when a very restrictive kinematic separation is employed. Stars with "intermediate" kinematics (P10.5) show a large star-to-star scatter in [O/Fe]-[Fe/H], but most of it is due to stars with Galactocentric rotational velocity V-200 km/s follow an [O/Fe]-[Fe/H] relation with almost no star-to-star scatter. Early mergers with satellite galaxies explain most of our observations, but the significant fraction of disk stars with "ambiguous" kinematics and abundances suggests that scattering ...

  8. Highly oxygenated stigmastane-type steroids from the aerial parts of Vernonia anthelmintica Willd.

    Science.gov (United States)

    Hua, Lei; Qi, Wei-Yan; Hussain, Syed Hamid; Gao, Kun; Arfan, Mohammad

    2012-06-01

    Nine new highly oxygenated stigmastane-type steroids, vernoanthelcin A-I (1-9), and two new stigmastane-type steroidal glycosides, vernoantheloside A and B (10 and 11) were isolated from the aerial parts of Vernonia anthelmintica Willd. The structures of compounds 1-11 were determined on the basis of IR, MS, 1D-NMR, and 2D-NMR, and their absolute configurations were deduced using single-crystal X-ray diffraction and the CD exciton chirality method. Compounds 1, 5, 7, 9 and 10 were tested for their effects on estrogen biosynthesis in human ovarian granulosa-like cells (KGN cells).

  9. Effect of hydrogen in Inconel Alloy 600 on corrosion in high temperature oxygenated water

    Energy Technology Data Exchange (ETDEWEB)

    Hou, J. [Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University, 6-6-01, Aramaki Aoba, Aoba-ku, Sendai 980-8579 (Japan); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China); Peng, Q.J. [Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University, 6-6-01, Aramaki Aoba, Aoba-ku, Sendai 980-8579 (Japan)], E-mail: qpeng@rift.mech.tohoku.ac.jp; Sakaguchi, K.; Takeda, Y.; Kuniya, J.; Shoji, T. [Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University, 6-6-01, Aramaki Aoba, Aoba-ku, Sendai 980-8579 (Japan)

    2010-03-15

    Corrosion test on hydrogen charged and uncharged coupons of Inconel Alloy 600 in high temperature oxygenated water showed more weight loss of charged coupon. Observation of the oxide film by transmission electron microscopy (TEM) showed a defective, thicker oxide layer on charged coupon. Analyses of the oxide film by TEM-energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy indicated enrichment of Ni but depletion of Cr in the oxide film on charged coupon. The changes in corrosion behavior and microstructure of the oxide film were most likely due to the hydrogen enhanced preferential dissolution of Cr cations in the water.

  10. Ground state atomic oxygen in high-power impulse magnetron sputtering: a quantitative study

    Science.gov (United States)

    Britun, Nikolay; Belosludtsev, Alexandr; Silva, Tiago; Snyders, Rony

    2017-02-01

    The ground state density of oxygen atoms in reactive high-power impulse magnetron sputtering discharges has been studied quantitatively. Both time-resolved and space-resolved measurements were conducted. The measurements were performed using two-photon absorption laser-induced fluorescence (TALIF), and calibrated by optical emission actinometry with multiple Ar emission lines. The results clarify the dynamics of the O ground state atoms in the discharge afterglow significantly, including their propagation and fast decay after the plasma pulse, as well as the influence of gas pressure, O2 admixture, etc.

  11. Pt5Gd as a Highly Active and Stable Catalyst for Oxygen Electroreduction

    DEFF Research Database (Denmark)

    Escribano, Maria Escudero; Verdaguer-Casadevall, Arnau; Verdaguer Casadevall, Arnau

    2012-01-01

    The activity and stability of Pt5Gd for the oxygen reduction reaction (ORR) have been studied, using a combination of electrochemical measurements, angle-resolved X-ray photoelectron spectroscopy (AR-XPS), and density functional theory calculations. Sputter-cleaned, polycrystalline Pt5Gd shows a 5...... can be explained by means of compressive strain effects. Furthermore, these novel bimetallic electrocatalysts are highly stable, which, in combination with their enhanced activity, makes them very promising for the development of new cathode catalysts for fuel cells....

  12. Efficient Production of O- by Dissociative Attachment of Slow Electrons to Highly Excited Metastable Oxygen Molecules

    Science.gov (United States)

    Hayashi, Daiyu; Kadota, Kiyoshi

    1999-01-01

    In this paper, the mechanism for efficient production of O- in the afterglow of a low-pressure and high-density oxygen plasma has been described. We proposed a new production process, the dissociative attachment of slow electrons to highly excited metastable oxygen molecules O2 (A3 Σu+, A'3Δu, c1Σu-). The electron attachment frequency has been obtained from the experimental results, and was significantly high for the electron temperature of less than 2 eV. The cross section, σDA, for this process was evaluated by a quantum mechanical approach. σDA at 0.1 eV was larger by two-orders of magnitude than the peak value at 6.7 eV for the ground state O2 (X3Σg+). The enhancement of the electron attachment frequency at low temperature can be explained by dissociative attachment of slow electrons to O2 (A3Σu+, A'3Δu, c1Σu-).

  13. Backside versus frontside advanced chemical analysis of high-k/metal gate stacks

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, E., E-mail: eugenie.martinez@cea.fr [Univ Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Saidi, B. [STMicroelectronics, 850 rue Jean Monnet, 38926 Rousset Cedex, Crolles (France); Veillerot, M. [Univ Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Caubet, P. [STMicroelectronics, 850 rue Jean Monnet, 38926 Rousset Cedex, Crolles (France); Fabbri, J-M. [Univ Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Piallat, F. [STMicroelectronics, 850 rue Jean Monnet, 38926 Rousset Cedex, Crolles (France); Gassilloud, R. [Univ Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Schamm-Chardon, S. [CEMES-CNRS et Université de Toulouse, 29 rue Jeanne Marvig, 31055 Toulouse (France)

    2015-08-15

    Highlights: • The backside approach is a promising solution for advanced chemical characterization of future MOSFETs. • Frontside ToF-SIMS and Auger depth profiles are affected by cumulative mixing effects and thus not relevant for analyzing ultra-thin layers. • Higher in-depth resolution is possible in the backside approach for Auger and ToF-SIMS depth profiling. • Backside depth profiling allows revealing ultra-thin layers and elemental in-depth redistribution inside high-k/metal gate stacks. • Backside XPS allows preserving the full metal gate, thus enabling the analysis of real technological samples. - Abstract: Downscaling of transistors beyond the 14 nm technological node requires the implementation of new architectures and materials. Advanced characterization methods are needed to gain information about the chemical composition of buried layers and interfaces. An effective approach based on backside analysis is presented here. X-ray photoelectron spectroscopy, Auger depth profiling and time-of-flight secondary ions mass spectrometry are combined to investigate inter-diffusion phenomena. To highlight improvements related to the backside method, backside and frontside analyses are compared. Critical information regarding nitrogen, oxygen and aluminium redistribution inside the gate stacks is obtained only in the backside configuration.

  14. Oxygen levels versus chemical pollutants: do they have similar influence on macrofaunal assemblages? A case study in a harbour with two opposing entrances

    Energy Technology Data Exchange (ETDEWEB)

    Guerra-Garcia, J.M. [Laboratorio de Biologia Marina, Departamento de Fisiologia y Zoologia, Facultad de Biologia, Universidad de Sevilla, Avda Reina Mercedes 6, 41012 Sevilla (Spain)]. E-mail: jmguerra@us.es; Garcia-Gomez, J.C. [Laboratorio de Biologia Marina, Departamento de Fisiologia y Zoologia, Facultad de Biologia, Universidad de Sevilla, Avda Reina Mercedes 6, 41012 Sevilla (Spain)

    2005-05-01

    Generally, harbours are polluted zones characterised by low values of hydrodynamism and oxygen in the water column and high concentrations of pollutants in sediments. The harbour of Ceuta, North Africa, has an unusual structure; it is located between two bays connected by a channel, which increases the water movement and exchange in the harbour, maintaining moderate oxygen levels in the water-sediment interface. Nevertheless, high concentration of organic matter, nutrients and heavy metals were measured in sediments from this harbour. Under these unusual conditions (high levels of pollution but total saturation of oxygen in the water column) we studied the responses of soft-bottom macrobenthic communities using uni and multivariate analyses. The number of species was similar inside and outside the harbour but the species composition differed between internal and external stations; oxygen levels seem to control the 'quantity' of species whereas pollutants control the 'quality' of them. - A high diversity of benthic animals was found in a polluted harbour where high oxygen levels occurred.

  15. Fiber optic chemical sensors: The evolution of high- density fiber-optic DNA microarrays

    Science.gov (United States)

    Ferguson, Jane A.

    2001-06-01

    Sensors were developed for multianalyte monitoring, fermentation monitoring, lactate analysis, remote oxygen detection for use in bioremediation monitoring and in a fuel spill clean-up project, heavy metal analysis, and high density DNA microarrays. The major focus of this thesis involved creating and improving high-density DNA gene arrays. Fiber optic sensors are created using fluorescent indicators, polymeric supports, and optical fiber substrates. The fluorescent indicator is entrapped in a polymer layer and attached to the tip of the optical fiber. The tip of the fiber bearing the sensing layer (the distal end) is placed in the sample of interest while the other end of the fiber (the proximal end) is connected to an analysis system. Any length of fiber can be used without compromising the integrity or sensitivity of the system. A fiber optic oxygen sensor was designed incorporating an oxygen sensitive fluorescent dye and a gas permeable polymer attached to an optical fiber. The construction simplicity and ruggedness of the sensor enabled its deployment for in situ chemical oxidation and bioremediation studies. Optical fibers were also used as the substrate to detect biomolecules in solution. To monitor bioprocesses, the production of the analyte of interest must be coupled with a species that is optically measurable. For example, oxygen is consumed in many metabolic functions. The fiber optic oxygen sensor is equipped with an additional sensing layer. Upon contact with a specific biochemical in the sample, a reaction occurs in the additional sensing layer that either consumes or produces oxygen. This dual layer system was used to monitor the presence of lactate, an important metabolite for clinical and bioprocess analysis. In many biological and environmental systems, the generation of one species occurs coincidentally with the generation or consumption of another species. A multianalyte sensor was prepared that can monitor the simultaneous activity of pH, CO2

  16. Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

    Science.gov (United States)

    Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

    2015-12-01

    Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 μg/L for nitrated and 0.3-8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected.

  17. Stereoselective synthesis of a highly oxygenated decahydrocyclopenta[g]chromene derivative: the common tricyclic framework of leucosceptrine and leucosesterterpenone.

    Science.gov (United States)

    Abe, Hideki; Horii, Yuri; Hagiwara, Megumi; Kobayashi, Toyoharu; Ito, Hisanaka

    2015-04-11

    Stereoselective construction of the highly oxygenated decahydrocyclopenta[g]chromene skeleton, which is the tricyclic core of leucosceptrine, which possesses prolylendopeptidase inhibitory activity, and leucosesterterpenone, which exhibits anti-angiogenic activity, from Leucosceptrum canum, was achieved.

  18. A new highly sensitive method to assess respiration rates and kinetics of natural planktonic communities by use of the switchable trace oxygen sensor and reduced oxygen concentrations.

    Science.gov (United States)

    Tiano, Laura; Garcia-Robledo, Emilio; Revsbech, Niels Peter

    2014-01-01

    Oxygen respiration rates in pelagic environments are often difficult to quantify as the resolutions of our methods for O2 concentration determination are marginal for observing significant decreases during bottle incubations of less than 24 hours. Here we present the assessment of a new highly sensitive method, that combine Switchable Trace Oxygen (STOX) sensors and all-glass bottle incubations, where the O2 concentration was artificially lowered. The detection limit of respiration rate by this method is inversely proportional to the O2 concentration, down to <2 nmol L(-1) h(-1) for water with an initial O2 concentration of 500 nmol L(-1). The method was tested in Danish coastal waters and in oceanic hypoxic waters. It proved to give precise measurements also with low oxygen consumption rates (∼7 nmol L(-1) h(-1)), and to significantly decrease the time required for incubations (≤14 hours) compared to traditional methods. This method provides continuous real time measurements, allowing for a number of diverse possibilities, such as modeling the rate of oxygen decrease to obtain kinetic parameters. Our data revealed apparent half-saturation concentrations (Km values) one order of magnitude lower than previously reported for marine bacteria, varying between 66 and 234 nmol L(-1) O2. Km values vary between different microbial planktonic communities, but our data show that it is possible to measure reliable respiration rates at concentrations ∼0.5-1 µmol L(-1) O2 that are comparable to the ones measured at full air saturation.

  19. Considerable Enhancement of Field Emission of SnO2Nanowires by Post-Annealing Process in Oxygen at High Temperature

    Directory of Open Access Journals (Sweden)

    Fang XS

    2009-01-01

    Full Text Available Abstract The field emission properties of SnO2nanowires fabricated by chemical vapor deposition with metallic catalyst-assistance were investigated. For the as-fabricated SnO2nanowires, the turn-on and threshold field were 4.03 and 5.4 V/μm, respectively. Considerable enhancement of field emission of SnO2nanowires was obtained by a post-annealing process in oxygen at high temperature. When the SnO2nanowires were post-annealed at 1,000 °C in oxygen, the turn-on and threshold field were decreased to 3.77 and 4.4 V/μm, respectively, and the current density was increased to 6.58 from 0.3 mA/cm2at the same applied electric field of 5.0 V/μm.

  20. Selective oxidation of glycerol to formic acid in highly concentrated aqueous solutions with molecular oxygen using V-substituted phosphomolybdic acids

    KAUST Repository

    Zhang, Jizhe

    2014-01-01

    Formic acid is an important commodity chemical as well as a promising medium for hydrogen storage and hydrogen production. In this paper, we report that formic acid can be produced through selective oxidation of glycerol, a low-cost by-product of biodiesel, by using vanadium-substituted phosphomolybdic acids as catalysts and molecular oxygen as the oxidant. Significantly, this catalytic system allows for high-concentration conversions and thus leads to exceptional efficiency. Specifically, 3.64 g of formic acid was produced from 10 g of glycerol/water (50/50 in weight) solution. © 2014 the Partner Organisations.

  1. 40 CFR 799.5085 - Chemical testing requirements for certain high production volume chemicals.

    Science.gov (United States)

    2010-07-01

    ... (preferred species), rat, or Chinese hamster): 40 CFR 799.9538 OR Mammalian Erythrocyte Micronucleus Test (in... CHEMICAL SUBSTANCE AND MIXTURE TESTING REQUIREMENTS Multichemical Test Rules § 799.5085 Chemical testing... paragraph (j) of this section at any time from April 17, 2006 to the end of the test data...

  2. Low-Temperature, Chemically Grown Titanium Oxide Thin Films with a High Hole Tunneling Rate for Si Solar Cells

    Directory of Open Access Journals (Sweden)

    Yu-Tsu Lee

    2016-05-01

    Full Text Available In this paper, we propose a chemically grown titanium oxide (TiO2 on Si to form a heterojunction for photovoltaic devices. The chemically grown TiO2 does not block hole transport. Ultraviolet photoemission spectroscopy was used to study the band alignment. A substantial band offset at the TiO2/Si interface was observed. X-ray photoemission spectroscopy (XPS revealed that the chemically grown TiO2 is oxygen-deficient and contains numerous gap states. A multiple-trap-assisted tunneling (TAT model was used to explain the high hole injection rate. According to this model, the tunneling rate can be 105 orders of magnitude higher for holes passing through TiO2 than for flow through SiO2. With 24-nm-thick TiO2, a Si solar cell achieves a 33.2 mA/cm2 photocurrent on a planar substrate, with a 9.4% power conversion efficiency. Plan-view scanning electron microscopy images indicate that a moth-eye-like structure formed during TiO2 deposition. This structure enables light harvesting for a high photocurrent. The high photocurrent and ease of production of chemically grown TiO2 imply that it is a suitable candidate for future low-cost, high-efficiency solar cell applications.

  3. Fabrication of vertically aligned diamond whiskers from highly boron-doped diamond by oxygen plasma etching.

    Science.gov (United States)

    Terashima, Chiaki; Arihara, Kazuki; Okazaki, Sohei; Shichi, Tetsuya; Tryk, Donald A; Shirafuji, Tatsuru; Saito, Nagahiro; Takai, Osamu; Fujishima, Akira

    2011-02-01

    Conductive diamond whiskers were fabricated by maskless oxygen plasma etching on highly boron-doped diamond substrates. The effects of the etching conditions and the boron concentration in diamond on the whisker morphology and overall substrate coverage were investigated. High boron-doping levels (greater than 8.4 × 10(20) cm(-3)) are crucial for the formation of the nanosized, densely packed whiskers with diameter of ca. 20 nm, length of ca. 200 nm, and density of ca. 3.8 × 10(10) cm(-2) under optimal oxygen plasma etching conditions (10 min at a chamber pressure of 20 Pa). Confocal Raman mapping and scanning electron microscopy illustrate that the boron distribution in the diamond surface region is consistent with the distribution of whisker sites. The boron dopant atoms in the diamond appear to lead to the initial fine column formation. This simple method could provide a facile, cost-effective means for the preparation of conductive nanostructured diamond materials for electrochemical applications as well as electron emission devices.

  4. Facile synthesis of high strength hot-water wood extract films with oxygen-barrier performance

    Science.gov (United States)

    Chen, Ge-Gu; Fu, Gen-Que; Wang, Xiao-Jun; Gong, Xiao-Dong; Niu, Ya-Shuai; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2017-01-01

    Biobased nanocomposite films for food packaging with high mechanical strength and good oxygen-barrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated FCMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm3 μm/day·m2·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of high-performance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging.

  5. Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium–Oxygen Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E.; Wang, Chong-Min; Zhang, Ji-Guang

    2016-08-10

    Lithium-oxygen (Li-O2) battery has an extremely high theoretical specific energy density as compared with conventional energy storage systems. However, practical application of Li-O2 battery system still faces significant challenges, especially its poor cyclability. In this work, we report a new approach to synthesis ultrafine metal oxide nanocatalysts through an electrochemical pre-lithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20~30 nm to a uniformly distributed domain of ~ 2 nm and largely improved their catalytic activity. Structurally, the pre-lithiated NCO NWs are featured by ultrafine NiO/CoO nanoparticles, which show high stability during prolonged cycles in terms of morphology and the particle size, therefore maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. Li-O2 battery using this catalyst has demonstrated an initial capacity of 29,280 mAh g-1 and has retained a stable capacity of over 1,000 mAh g-1 after 100 cycles based on the weight of NCO active material. Direct in-situ TEM observation conclusively reveals the lithiation/delithiation process of as-prepared NCO NWs, clarifying the NCO/Li electrochemical reaction mechanism that can be extended to other transition-metal oxides and providing the in depth understandings on the catalysts and battery chemistries of other ternary transition-metal oxides.

  6. Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium-Oxygen Batteries.

    Science.gov (United States)

    Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E; Wang, Chong-Min; Zhang, Ji-Guang

    2016-08-10

    Lithium-oxygen (Li-O2) batteries have an extremely high theoretical specific energy density when compared with conventional energy-storage systems. However, practical application of the Li-O2 battery system still faces significant challenges. In this work, we report a new approach for synthesis of ultrafine metal oxide nanocatalysts through an electrochemical prelithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20-30 nm to a uniformly distributed domain of ∼2 nm and significantly improves their catalytic activity. Structurally, the prelithiated NCO nanowires feature ultrafine NiO/CoO nanoparticles that are highly stable during prolonged cycles in terms of morphology and particle size, thus maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. A Li-O2 battery using this catalyst demonstrated an initial capacity of 29 280 mAh g(-1) and retained a capacity of >1000 mAh g(-1) after 100 cycles based on the weight of the NCO active material. Direct in situ transmission electron microscopy observations conclusively revealed the lithiation/delithiation process of as-prepared NCO nanowires and provided in-depth understanding for both catalyst and battery chemistries of transition-metal oxides. This unique electrochemical approach could also be used to form ultrafine nanoparticles of a broad range of materials for catalyst and other applications.

  7. High-resolution CCD spectra of stars in globular clusters. I - Oxygen in M13

    Science.gov (United States)

    Leep, E. M.; Wallerstein, G.; Oke, J. B.

    1986-01-01

    High-resolution (0.3 A) CCD spectra obtained at the 200 in. coude spectrograph have been analyzed for the abundances of O, Sc, Fe, and La in four stars in the globular cluster M13. Fe/H abundance is found to be = -1.6, as found by many other observers of this cluster. For three stars O/Fe abundance is found to be = +0.3 + or - 0.1, which is similar to O/Fe ratios in other globular clusters and metal-poor field stars. For star II-67, no oxygen line is visible at 6300 A and O/Fe abundance is found to be not greater than -0.4 (for a high carbon content) and not greater than -0.7 (for a low carbon content). The latter is more likely to be correct. Two possible explanations of the oxygen deficiency in II-67 are discussed: primordial deficiency, and CNO cycling at or above a temperature of 25,000,000 K.

  8. The use of high-flow nasal oxygen therapy in the management of hypercarbic respiratory failure.

    Science.gov (United States)

    Millar, Jonathan; Lutton, Stuart; O'Connor, Philip

    2014-04-01

    Hypercarbic respiratory failure, occurring secondary to chronic lung disease, is a frequently encountered problem. These patients present a significant challenge to respiratory and critical care services, as many are unsuitable for mechanical ventilation and most have multiple comorbidities. Recently, noninvasive ventilation (NIV) has become established as the primary modality for respiratory support in this group of patients. Several factors limit patient compliance with NIV, not least comfort and tolerability. A recent innovation in adult critical care is the use of high-flow nasal oxygen (HFNO) devices. These systems are capable of delivering high gas flows via nasal cannulae, with the ability to blend air and oxygen to give a controlled FiO2. Few clinical studies have been conducted in adults, although several are planned. To date the majority of available evidence addresses the use of HFNO in hypoxemic respiratory failure. Here we present a case in which a HFNO system was used to successfully manage hypercarbic respiratory failure in a patient unable to tolerate conventional NIV.

  9. Surface strontium enrichment on highly active perovskites for oxygen electrocatalysis in solid oxide fuel cells

    KAUST Repository

    Crumlin, Ethan J.

    2012-01-01

    Perovskite oxides have high catalytic activities for oxygen electrocatalysis competitive to platinum at elevated temperatures. However, little is known about the oxide surface chemistry that influences the activity near ambient oxygen partial pressures, which hampers the design of highly active catalysts for many clean-energy technologies such as solid oxide fuel cells. Using in situ synchrotron-based, ambient pressure X-ray photoelectron spectroscopy to study the surface chemistry changes, we show that the coverage of surface secondary phases on a (001)-oriented La 0.8Sr 0.2CoO 3-δ (LSC) film becomes smaller than that on an LSC powder pellet at elevated temperatures. In addition, strontium (Sr) in the perovskite structure enriches towards the film surface in contrast to the pellet having no detectable changes with increasing temperature. We propose that the ability to reduce surface secondary phases and develop Sr-enriched perovskite surfaces of the LSC film contributes to its enhanced activity for O 2 electrocatalysis relative to LSC powder-based electrodes. © 2012 The Royal Society of Chemistry.

  10. Microbial nar-GFP cell sensors reveal oxygen limitations in highly agitated and aerated laboratory-scale fermentors

    Directory of Open Access Journals (Sweden)

    Rao Govind

    2009-01-01

    Full Text Available Abstract Background Small-scale microbial fermentations are often assumed to be homogeneous, and oxygen limitation due to inadequate micromixing is often overlooked as a potential problem. To assess the relative degree of micromixing, and hence propensity for oxygen limitation, a new cellular oxygen sensor has been developed. The oxygen responsive E. coli nitrate reductase (nar promoter was used to construct an oxygen reporter plasmid (pNar-GFPuv which allows cell-based reporting of oxygen limitation. Because there are greater than 109 cells in a fermentor, one can outfit a vessel with more than 109 sensors. Our concept was tested in high density, lab-scale (5 L, fed-batch, E. coli fermentations operated with varied mixing efficiency – one verses four impellers. Results In both cases, bioreactors were maintained identically at greater than 80% dissolved oxygen (DO during batch phase and at approximately 20% DO during fed-batch phase. Trends for glucose consumption, biomass and DO showed nearly identical behavior. However, fermentations with only one impeller showed significantly higher GFPuv expression than those with four, indicating a higher degree of fluid segregation sufficient for cellular oxygen deprivation. As the characteristic time for GFPuv expression (approx 90 min. is much larger than that for mixing (approx 10 s, increased specific fluorescence represents an averaged effect of oxygen limitation over time and by natural extension, over space. Conclusion Thus, the pNar-GFPuv plasmid enabled bioreactor-wide oxygen sensing in that bacterial cells served as individual recirculating sensors integrating their responses over space and time. We envision cell-based oxygen sensors may find utility in a wide variety of bioprocessing applications.

  11. Oxygen Adsorption-Desorption Behavior and Superconducting Properties of High-Tc Bi(Pb)-Sr-Ca-Cu-O

    Science.gov (United States)

    Miura, Norio; Suzuta, Hiroki; Deshimaru, Yuichi; Shimizu, Youichi; Sakashita, Hirofumi; Yamazoe, Noboru

    1989-07-01

    Temperature-programmed desorption (TPD) chromatograms revealed that a small amount of oxygen was desorbed from high-Tc Bi(Pb)-Sr-Ca-Cu-O (BPSCCO) in the temperature range from ca. 350 to ca. 650°C prior to a steep increase of oxygen desorption in the higher temperature range. The Tc of BPSCCO was significantly lowered with the progress of oxygen desorption especially in the former temperature range, and was restored to the original level when the desorbed oxygen was recovered. With no corresponding changes in X-ray powder diffraction pattern being detected, the oxygen desorbed below ca. 650°C was concluded to have strong relevance to the superconductivity of BPSCCO.

  12. Long-term effects of antibiotics on the elimination of chemical oxygen demand, nitrification, and viable bacteria in laboratory-scale wastewater treatment plants.

    Science.gov (United States)

    Schmidt, Susan; Winter, Josef; Gallert, Claudia

    2012-10-01

    Antibiotics and other pharmaceuticals are contaminants of the environment because of their widespread use and incomplete removal by microorganisms during wastewater treatment. The influence of a mixture of ciprofloxacin (CIP), gentamicin (GM), sulfamethoxazole (SMZ)/trimethoprim (TMP), and vancomycin (VA), up to a final concentration of 40 mg/L, on the elimination of chemical oxygen demand (COD), nitrification, and survival of bacteria, as well as the elimination of the antibiotics, was assessed in a long-term study in laboratory treatment plants (LTPs). In the presence of 30 mg/L antibiotics, nitrification of artificial sewage by activated sludge ended at nitrite. Nitrate formation was almost completely inhibited. No nitrification at all was possible in the presence of 40 mg/L antibiotics. The nitrifiers were more sensitive to antibiotics than heterotrophic bacteria. COD elimination in antibiotic-stressed LTPs was not influenced by ≤20 mg/L antibiotics. Addition of 30 mg/L antibiotic mixture decreased COD removal efficiency for a period, but the LTPs recovered. Similar results were obtained with 40 mg/L antibiotic mixture. The total viable count of bacteria was not affected negatively by the antibiotics. It ranged from 2.2 × 10(6) to 8.2 × 10(6) colony-forming units per milliliter (CFU/mL) compared with the control at 1.4 × 10(6)-6.3 × 10(6) CFU/mL. Elimination of the four antibiotics during phases of 2.4-30 mg/L from the liquid was high for GM (70-90 %), much lower for VA, TMP, and CIP (0-50 %), and highly fluctuating for SMZ (0-95 %). The antibiotics were mainly adsorbed to the sludge and not biodegraded.

  13. Development of variable pathlength UV-vis spectroscopy combined with partial-least-squares regression for wastewater chemical oxygen demand (COD) monitoring.

    Science.gov (United States)

    Chen, Baisheng; Wu, Huanan; Li, Sam Fong Yau

    2014-03-01

    To overcome the challenging task to select an appropriate pathlength for wastewater chemical oxygen demand (COD) monitoring with high accuracy by UV-vis spectroscopy in wastewater treatment process, a variable pathlength approach combined with partial-least squares regression (PLSR) was developed in this study. Two new strategies were proposed to extract relevant information of UV-vis spectral data from variable pathlength measurements. The first strategy was by data fusion with two data fusion levels: low-level data fusion (LLDF) and mid-level data fusion (MLDF). Predictive accuracy was found to improve, indicated by the lower root-mean-square errors of prediction (RMSEP) compared with those obtained for single pathlength measurements. Both fusion levels were found to deliver very robust PLSR models with residual predictive deviations (RPD) greater than 3 (i.e. 3.22 and 3.29, respectively). The second strategy involved calculating the slopes of absorbance against pathlength at each wavelength to generate slope-derived spectra. Without the requirement to select the optimal pathlength, the predictive accuracy (RMSEP) was improved by 20-43% as compared to single pathlength spectroscopy. Comparing to nine-factor models from fusion strategy, the PLSR model from slope-derived spectroscopy was found to be more parsimonious with only five factors and more robust with residual predictive deviation (RPD) of 3.72. It also offered excellent correlation of predicted and measured COD values with R(2) of 0.936. In sum, variable pathlength spectroscopy with the two proposed data analysis strategies proved to be successful in enhancing prediction performance of COD in wastewater and showed high potential to be applied in on-line water quality monitoring.

  14. Shelf Life of Oxygen Moisture Bottle after Chemical Disinfection%氧气湿化瓶消毒后保存期的研究

    Institute of Scientific and Technical Information of China (English)

    李少英; 李碧坚; 何丽媚

    2013-01-01

      目的通过对氧气湿化瓶化学消毒后保存期进行研究,以明确其保存有效期。方法将240个氧气湿化瓶化学消毒后分别保存于5个临床科室,保存时间180 d,每月进行细菌学监测。结果氧气湿化瓶化学消毒后保存30、60、90、120、150、180 d细菌监测结果均≤20 CFU/件,未检出致病菌,合格率100%。结论氧气湿化瓶化学消毒后用保鲜袋单独包装,做好保存环境管理,其保存期最少6个月。%Objective To explore the shelf life of oxygen moisture bottle after chemical disinfection and to make clear its validity. Methods A total of 240 oxygen moisture bottles after chemical disinfection had been stored in clinical departments for 180 days and bacteriological monitoring was carried out every month. Results Bacteria monitoring 30, 60, 90, 120, 150 and 180 days after chemical disinfection showed there was 20 or less cfu/per piece and no pathogenic bacteria was found, with a qualification rate of 100%. Conclusion Once oxygen moisture bottle is packaged by plastic bag individually and stored in friendly environment, the shelf life of it after chemical disinfection could last for at least 6 months.

  15. Measurements of tropospheric HO2 and RO2 by oxygen dilution modulation and chemical ionization mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. S. Olson

    2010-09-01

    Full Text Available An improved method for the measurement of hydroperoxy radicals (HO2 and organic peroxy radicals (RO2, where R is any organic group has been developed that combines two previous chemical conversion/chemical ionization mass spectrometry (CIMS peroxy radical measurement techniques. Applicable to both ground-based and aircraft platforms, the method provides good separation between HO2 and RO2 and frequent measurement capability with observations of both HO2 and HO2 + RO2 amounts each minute. This allows for analyses of measured [HO2]/[HO2 + RO2] ratios on timescales relevant to tropospheric photochemistry. By varying both [NO] and [O2] simultaneously in the chemical conversion region of the PeRCIMS (Peroxy Radical CIMS inlet, the method exploits the changing conversion efficiency of RO2 to HO2 under different inlet [NO]/[O2] to selectively observe either primarily HO2 or the sum of HO2 and RO2. Two modes of operation have been established for ambient measurements: in the first half of the minute, RO2 radicals are measured at close to 100% efficiency along with HO2 radicals (low [NO]/[O2] = 2.53 × 10−5 and in the second half of the minute, HO2 is detected while the majority of ambient RO2 radicals are measured with approximately 15% efficiency (high [NO]/[O2] = 6.80 × 10−4. The method has been tested extensively in the laboratory under various conditions and for a variety of organic peroxy radicals relevant to the atmosphere and the results of these tests are presented. The modified PeRCIMS instrument has been deployed successfully using the current measurement technique on a number of aircraft campaigns, including on the NSF/NCAR C-130 during the MIRAGE-Mex and NASA INTEX-B field campaigns in the spring of 2006. A brief comparison of the peroxy radical measurements during these campaigns to a photochemical box model confirms that the PeRCIMS is able to successfully separate and measure HO2 and RO2 under the majority of tropospheric conditions.

  16. Measurements of tropospheric HO2 and RO2 by oxygen dilution modulation and chemical ionization mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. S. Olson

    2011-01-01

    Full Text Available An improved method for the measurement of hydroperoxy radicals (HO2 and organic peroxy radicals (RO2, where R is any organic group has been developed that combines two previous chemical conversion/chemical ionization mass spectrometry (CIMS peroxy radical measurement techniques. Applicable to both ground-based and aircraft platforms, the method provides good separation between HO2 and RO2 and frequent measurement capability with observations of both HO2 and HO2+RO2 amounts each minute. This allows for analyses of measured [HO2]/[HO2+RO2] ratios on timescales relevant to tropospheric photochemistry. By varying both [NO] and [O2] simultaneously in the chemical conversion region of the PeRCIMS (Peroxy Radical CIMS inlet, the method exploits the changing conversion efficiency of RO2 to HO2 under different inlet [NO]/[O2] to selectively observe either primarily HO2 or the sum of HO2 and RO2. Two modes of operation have been established for ambient measurements: in the first half of the minute, RO2 radicals are measured at close to 100% efficiency along with HO2 radicals (low [NO]/[O2] = 2.53×10−5 and in the second half of the minute, HO2 is detected while the majority of ambient RO2 radicals are measured with low efficiency, approximately 15% (high [NO]/[O2] = 6.80×10−4. The method has been tested extensively in the laboratory under various conditions and for a variety of organic peroxy radicals relevant to the atmosphere and the results of these tests are presented. The modified PeRCIMS instrument has been deployed successfully using the new measurement technique on a number of aircraft campaigns, including on the NSF/NCAR C-130 during the MIRAGE-Mex and NASA INTEX-B field campaigns in the spring of 2006. A brief comparison of the peroxy radical measurements during these campaigns to a photochemical box model indicates good agreement under tropospheric conditions where NOx (NO+NO2 concentrations are lower than 0.5 ppbV (parts per billion by

  17. Measurements of tropospheric HO2 and RO2 by oxygen dilution modulation and chemical ionization mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. S. Olson

    2011-04-01

    Full Text Available An improved method for the measurement of hydroperoxy radicals (HO2 and organic peroxy radicals (RO2, where R is any organic group has been developed that combines two previous chemical conversion/chemical ionization mass spectrometry (CIMS peroxy radical measurement techniques. Applicable to both ground-based and aircraft platforms, the method provides good separation between HO2 and RO2, and frequent measurement capability with observations of both HO2 and HO2 + RO2 amounts each minute. These improvements allow for analyses of measured [HO2]/[HO2 + RO2] ratios on timescales relevant to tropospheric photochemistry. By varying both [NO] and [O2] simultaneously in the chemical conversion region of the PeRCIMS (Peroxy Radical CIMS inlet, the method exploits the changing conversion efficiency of RO2 to HO2 under different inlet [NO]/[O2] to selectively observe either primarily HO2 or the sum of HO2 and RO2. Two modes of operation have been established for ambient measurements: in the first half of the minute, RO2 radicals are measured at close to 100% efficiency along with HO2 radicals (low [NO]/[O2] = 2.53 × 10−5 and in the second half of the minute, HO2 is detected while the majority of ambient RO2 radicals are measured with low efficiency, approximately 15% (high [NO]/[O2] = 6.80 × 10−4. The method has been tested extensively in the laboratory under various conditions and for a variety of organic peroxy radicals relevant to the atmosphere and the results of these tests are presented. The modified PeRCIMS instrument has been deployed successfully using the new measurement technique on a number of aircraft campaigns, including on the NSF/NCAR C-130 during the MIRAGE-Mex and NASA INTEX-B field campaigns in the spring of 2006. A brief comparison of the peroxy radical measurements during these campaigns to a photochemical box model indicates good agreement under tropospheric conditions where NOx (NO + NO2 concentrations are lower than 0.5 ppb

  18. High oxygen modifies vasodilator effect of cysteine via enhanced oxidative stress and thromboxane production in the rat mesenteric artery.

    Science.gov (United States)

    Yasuda, Yoshitaka; Feng, Guo-Gang; Li, Jiazheng; Nakamura, Emi; Hayashi, Hisaki; Sato, Motohiko; Fujiwara, Yoshihiro; Kinoshita, Hiroyuki

    2016-09-01

    Whether high oxygen is harmful to the vascular function is unclear. The present study examined if high oxygen modifies vasodilator effect of cysteine via enhanced oxidative stress and thromboxane production. Rat mesenteric arteries with endothelium at 95 or 50 % oxygen were subjected to isometric force recordings, measurement of thromboxane B2 levels, determination of superoxide and peroxynitrite levels and evaluation of NADPH oxidase subunit protein expression, respectively. L-cysteine (0.01-3 mM) constricted or dilated arteries at 95 and 50 % oxygen, respectively. Thromboxane receptor antagonist SQ-29,548 (1 μM) abolished the constriction at 95 % oxygen. L-cysteine (3 mM) increased levels of thromboxane B2 in arteries upon 95 % oxygen application. L-cysteine relaxed arteries treated with superoxide inhibitor tiron (2 mM) or NADPH oxidase inhibitor gp91ds-tat (1 μM) irrespective of the oxygen concentration while ATP-sensitive K(+) channel inhibitor glibenclamide (1 μM) and cystathionine-γ-lyase (CSE) inhibitor DL-propargylglycine (10 mM) similarly abolished the relaxation. L-cysteine (3 mM) with 95 % oxygen augmented levels of superoxide as well as nitrotyrosine within the artery, concomitantly with enhanced membrane protein expression of NADPH oxidase subunit p47phox. The higher concentration of oxygen attenuates L-cysteine-induced vasodilation via superoxide production mediated by NADPH oxidase along with thromboxane A2 production, resulting in vasoconstriction. The increased levels of superoxide, as well as peroxynitrite, coexist with the impaired vasodilation related to ATP-sensitive K(+) channels and CSE. Higher oxygen with plasma cysteine may cause oxidative stress and vasoconstrictor prostanoid production in blood vessels.

  19. An fMRI study on variation of visuospatial cognitive performance of young male due to highly concentrated oxygen administration

    Science.gov (United States)

    Chung, Soon Cheol; Kim, Ik Hyeon; Tack, Gye Rae; Sohn, Jin Hun

    2004-04-01

    This study investigated the effects of 30% oxygen administration on the visuospatial cognitive performance using fMRI. Eight college students (right-handed, average age 23.5) were selected as subjects for this study. Oxygen supply equipment which gives 21% and 30% oxygen at a constant rate of 8L/min was developed for this study. To measure the performance of visuospatial cognition, two questionnaires with similar difficulty containing 20 questions each were also developed. Experiment was designed as two runs: run for visuospatial cognition test with normal air (21% of oxygen) and run for visuospatial cognition test with highly concentrated air (30% of oxygen). Run consists of 4 blocks and each block has 8 control problems and 5 visuospatial problems. Functional brain images were taken from 3T MRI using single-shot EPI method. Activities of neural network due to performing visuospatial cognition test were identified using subtraction procedure, and activation areas while performing visuospatial cognition test were extracted using double subtraction procedure. Activities were observed at occipital lobe, parietal lobe, and frontal lobe when performing visuospatial cognition test following both 21% and 30% oxygen administration. But in case of only 30% oxygen administration there were more activities at left precuneus, left cuneus, right postcentral gyrus, bilateral middle frontal gyri, right inferior frontal gyrus, left superior frontal gyrus, bilateral uvula, bilateral pyramis, and nodule compared with 21% oxygen administration. From results of visuospatial cognition test, accuracy rate increased in case of 30% oxygen administration. Thus it could be concluded that highly concentrated oxygen administration has positive effects on the visuospatial cognitive performance.

  20. Nano Ce2O2S with Highly Enriched Oxygen-Deficient Ce(3+) Sites Supported by N and S Dual-Doped Carbon as an Active Oxygen-Supply Catalyst for the Oxygen Reduction Reaction.

    Science.gov (United States)

    Yang, Liu; Cai, Zhuang; Hao, Liang; Xing, Zipeng; Dai, Ying; Xu, Xin; Pan, Siyu; Duan, Yaqiang; Zou, Jinlong

    2017-07-12

    The design of rare-earth-metal oxide/oxysulfide catalysts with high activity and durability for the oxygen reduction reaction (ORR) is still a grand challenge at present. In this study, Ce-species (Ce2O2S/CeO2)/N, S dual-doped carbon (Ce-species/NSC) catalysts with promising oxygen storage/release capacities are prepared at different temperatures (800-1000 °C) to enhance the ORR efficiency. Mechanisms for the effects of temperature on crystalline phase transition between CeO2 and Ce2O2S and structure evolution of Ce-species/NSCs are inferred to better understand their catalytic activity. Porous Ce2O2S/NSC (950 °C) catalyst as the air-breathing cathode exhibits a maximum power density of 1087.2 mW m(-2), which is higher than those of other Ce-species/NSCs and commercial Pt/C (989.13 mW m(-2)) in microbial fuel cells. The decline of the power density of Ce2O2S/NSC (950 °C) cathode is 8.7% after 80 days of operation, which is far lower than that of Pt/C (36.7%). Ce2O2S/NSC (950 °C) has a four-electron selectivity toward the ORR and a low charge-transfer resistance (5.49 Ω), contributing to high ORR activity and durability. The promising ORR catalytic activity of Ce2O2S/NSC (950 °C) is attributed to its high specific surface area (338.9 m(2) g(-1)), varied active sites, high electrical conductivity, and sufficient oxygen vacancies in the Ce2O2S skeleton. The high content of Ce(3+) in Ce2O2S/NSC (950 °C) facilitates the formation of more oxygen-deficient Ce(3+) sites that generate more oxygen vacancies to release/store more oxygen to stabilize the available oxygen for the ORR. Thus, this study provides a new perspective for preparation and application of this new type of the ORR catalyst.

  1. Characterisation of perovskite-type high-temperature membranes used for oxygen supply in fossil fuelled power plant processes; Charakterisierung perowskitischer Hochtemperaturmembranen zur Sauerstoffbereitstellung fuer fossil gefeuerte Kraftwerksprozesse

    Energy Technology Data Exchange (ETDEWEB)

    Moebius, Sigrid Annett

    2010-03-12

    In this thesis thermochemical properties of mixed conducting perovskite-type materials were investigated. Those materials are assumed to be applicable as gas separation membranes in the oxyfuel process. Here, the materials are aimed to produce the required oxygen for the combustion more energy-efficient than using cryogenic air separation. High-temperature materials which are applicable for this purpose must be gastight and should exhibit a high oxygen permeation rate and a preferably low thermal expansion coefficient. Moreover, the materials need to be long-term stable under power plant relevant conditions. The aim of this work is a better understanding of the material behaviour. Furthermore, on the basis of the results it should be possible to draw conclusions concerning the suitability of the material for application in oxyfuel power plant processes. Therefor, the influence of the chemical composition (doping elements and stoichiometry) of the perovskites, the temperature and the oxygen content in the ambient atmosphere on the thermochemical properties are studied systematically. In the framework of this thesis it could be stated that the thermochemical behaviour of prospective membrane materials strongly depends on the above mentioned parameters. In addition, the degradation behaviour (thermochemical stability) of the materials was investigated. The degradation behaviour influences the suitability of the material to be used in oxyfuel power plant processes. Here, the influence of the chemical composition of the perovskites, the temperature and the CO{sub 2}-concentration in dry and humid atmospheres was also studied. On the basis of the results it could be stated that the thermochemical stability strongly depends on the surrounding atmosphere and on the chemical composition of the perovskites. (orig.)

  2. Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

    Directory of Open Access Journals (Sweden)

    Il-Nam Kim

    2012-01-01

    Full Text Available We present evidence of denitrification on the continental slopes of the Ulleung Basin (UB and the Eastern Japan Basin (EJB near the Tatar Strait (TtS in the East/Japan Sea (EJS, despite its high water column dissolved oxygen concentrations. Some nutrient concentration data deviate significantly from the fitted regression line of nitrate (N vs. phosphate (P in deep waters, indicating a loss of nitrate in the region. The EJS has a lower N/P ratio (ca. 12.4 below 300 dbar than a traditional Redfield ratio (16. The N/P ratio and oxygen concentration are substantially lower at several locations whose depths are close to the sediment-water interface, near TtS (500 - 1100 dbar and in UB (1100 - 2200 dbar. The decreased nitrate concentration is smaller than the expected nitrate level (a low N/P ratio of < 12.4, and a secondary nitrite peak near the bottom of these two regions: taken collectively, both indicate the presence of denitrification in the bottom layer. It is speculated that active re-mineralization and denitrification may occur simultaneously along the rich organic matter bottom layer on the slope environment. Denitrification rates are estimated at ~3 - 33 μmol N m-2 d-1. Current estimates do not support the previous idea of basin-wide denitrification in EJS, although the N/P ratio is low like in other hypoxic/anoxic seas. A better understanding of the denitrification process is necessary for predicting future changes of nitrogen cycle in the well-oxygenated EJS considering the decadal-scale physical and biogeochemical changes that have occurred.

  3. Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

    Directory of Open Access Journals (Sweden)

    Il-Nam Kim

    2012-01-01

    Full Text Available We present evidence of denitrification on the continental slopes of the Ulleung Basin (UB and the Eastern Japan Basin (EJB near the Tatar Strait (TtS in the East/Japan Sea (EJS, despite its high water column dissolved oxygen concentrations. Some nutrient concentration data deviate significantly from the fitted regression line of nitrate (N vs. phosphate (P in deep waters, indicating a loss of nitrate in the region. The EJS has a lower N/P ratio (ca. 12.4 below 300 dbar than a traditional Redfield ratio (16. The N/P ratio and oxygen concentration are substantially lower at several locations whose depths are close to the sediment-water interface, near TtS (500 - 1100 dbar and in UB (1100 - 2200 dbar. The decreased nitrate concentration is smaller than the expected nitrate level (a low N/P ratio of < 12.4, and a secondary nitrite peak near the bottom of these two regions: taken collectively, both indicate the presence of denitrification in the bottom layer. It is speculated that active re-mineralization and denitrification may occur simultaneously along the rich organic matter bottom layer on the slope environment. Denitrification rates are estimated at ~3 - 33 μmol N m-2 d-1. Current estimates do not support the previous idea of basin-wide denitrification in EJS, although the N/P ratio is low like in other hypoxic/anoxic seas. A better understanding of the denitrification process is necessary for predicting future changes of nitrogen cycle in the well-oxygenated EJS considering the decadal-scale physical and biogeochemical changes that have occurred.

  4. Structure and stability of a high-coverage (1x1) oxygen phase on Ru(0001)

    CERN Document Server

    Stampfl, C; Over, H; Scheffler, M; Ertl, G

    1996-01-01

    The formation of chemisorbed O-phases on Ru(0001) by exposure to O_2 at low pressures is apparently limited to coverages Theta <= 0.5. Using low-energy electron diffraction and density functional theory we show that this restriction is caused by kinetic hindering and that a dense O overlayer (Theta = 1) can be formed with a (1x1) periodicity. The structural and energetic properties of this new adsorbate phase are analyzed and discussed in view of attempts to bridge the so-called "pressure gap" in heterogeneous catalysis. It is argued that the identified system actuates the unusually high rate of oxidizing reactions at Ru surfaces under high oxygen pressure conditions.

  5. An Experimental Study on High Temperature and Low Oxygen Air Combustion

    Institute of Scientific and Technical Information of China (English)

    W.B.Kim; D.H.Chung; 等

    2000-01-01

    High temperature preheated and diluted air combustion has been confirmed as the technolgy,mainly applied to industrial furnaces and kilns,to realize higher thermal efficiency and lower emissions.The purpose of this study was to investigate fundamental aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with room temperature air.The test items were exhaust gas components of CO,NOx,flame shape and raidcal components of CH,OH and C2,which were measured with gas analyser,camera and ICCD(Intersified Charged-Coupled Device) camera.Many phenomena as results appeared in combustion with the oxidizer,low oxygen concentation and extremely high temperature air,such as expansion of the flammable limits,increased flame propagation speed,it looked so strange as compared with those in existing combustion technology,we confirmed that such extraordinary phenomena were believable through the hot-test experiment.

  6. Polarizing Oxygen Vacancies in Insulating Metal Oxides under a High Electric Field

    Science.gov (United States)

    Youssef, Mostafa; Van Vliet, Krystyn J.; Yildiz, Bilge

    2017-09-01

    We demonstrate a thermodynamic formulation to quantify defect formation energetics in an insulator under a high electric field. As a model system, we analyzed neutral oxygen vacancies (color centers) in alkaline-earth-metal binary oxides using density functional theory, Berry phase calculations, and maximally localized Wannier functions. The work of polarization lowers the field-dependent electric Gibbs energy of formation of this defect. This is attributed mainly to the ease of polarizing the two electrons trapped in the vacant site, and secondarily to the defect induced reduction in bond stiffness and softening of phonon modes. The formulation and analysis have implications for understanding the behavior of insulating oxides in electronic, magnetic, catalytic, and electrocaloric devices under a high electric field.

  7. Influence of oxygen pressure on critical current density and magnetic flux pinning structures in YBa2Cu3O7-x fabricated by chemical solution deposition

    Institute of Scientific and Technical Information of China (English)

    Ding Fa-Zhu; Gu Hong-Wei; Zhang Teng; Dai Shao-Tao; Xiao Li-Ye

    2011-01-01

    This paper studies the effect of oxygen partial pressure on the fabrication of YBa2Cu3O7-x films on (00/) LaAlO3 substrates by metalorganic deposition using trifluoroacetates (TFA-MOD). As the oxygen partial pressure increases to 1500 Pa, a great increase in the superconducting properties is observed at high magnetic fields parallel to the YBCO c axis. The cross-sectional transmission electron microscope images show that a high density of stacking faults in the size range of 10-15 nm may act as flux pinning centres to enhance the critical current density of the YBCO films

  8. Stratified Bacterial Diversity along Physico-chemical Gradients in High-Altitude Modern Stromatolites

    Science.gov (United States)

    Toneatti, Diego M.; Albarracín, Virginia H.; Flores, Maria R.; Polerecky, Lubos; Farías, María E.

    2017-01-01

    At an altitude of 3,570 m, the volcanic lake Socompa in the Argentinean Andes is presently the highest site where actively forming stromatolite-like structures have been reported. Interestingly, pigment and microsensor analyses performed through the different layers of the stromatolites (50 mm-deep) showed steep vertical gradients of light and oxygen, hydrogen sulfide and pH in the porewater. Given the relatively good characterization of these physico-chemical gradients, the aim of this follow-up work was to specifically address how the bacterial diversity stratified along the top six layers of the stromatolites which seems the most metabolically important and diversified zone of the whole microbial community. We herein discussed how, in only 7 mm, a drastic succession of metabolic adaptations occurred: i.e., microbial communities shift from a UV-high/oxic world to an IR-low/anoxic/high H2S environment which force stratification and metabolic specialization of the bacterial community, thus, modulating the chemical faces of the Socompa stromatolites. The oxic zone was dominated by Deinococcus sp. at top surface (0.3 mm), followed by a second layer of Coleofasciculus sp. (0.3 to ∼2 mm). Sequences from anoxygenic phototrophic Alphaproteobacteria, along with an increasing diversity of phyla including Bacteroidetes, Spirochaetes were found at middle layers 3 and 4. Deeper layers (5–7 mm) were mostly occupied by sulfate reducers of Deltaproteobacteria, Bacteroidetes and Firmicutes, next to a high diversity and equitable community of rare, unclassified and candidate phyla. This analysis showed how microbial communities stratified in a physicochemical vertical profile and according to the light source. It also gives an insight of which bacterial metabolic capabilities might operate and produce a microbial cooperative strategy to thrive in one of the most extreme environments on Earth. PMID:28446906

  9. Anisotropy vs chemical composition at ultra-high energies

    CERN Document Server

    Lemoine, Martin

    2009-01-01

    This paper proposes and discusses a test of the chemical composition of ultra-high energy cosmic rays that relies on the anisotropy patterns measured as a function of energy. In particular, we show that if one records an anisotropy signal produced by heavy nuclei of charge Z above an energy E_{thr}, one should record an even stronger (possibly much stronger) anisotropy at energies >E_{thr}/Z due to the proton component that is expected to be associated with the sources of the heavy nuclei. This conclusion remains robust with respect to the parameters characterizing the sources and it does not depend at all on the modelling of astrophysical magnetic fields. As a concrete example, we apply this test to the most recent data of the Pierre Auger Observatory. Assuming that the anisotropy reported above 55EeV is not a statistical accident, and that no significant anisotropy has been observed at energies 10^{45}Z^{-2}erg/s. Using this bound in conjunction with the above conclusions, we argue that the current PAO data...

  10. Triangular Ag-Pd alloy nanoprisms: rational synthesis with high-efficiency for electrocatalytic oxygen reduction

    Science.gov (United States)

    Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Zhang, Xiao; Tan, Chaoliang; Li, Hai; Zhang, Hua; Xue, Can

    2014-09-01

    We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems.We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03600j

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

    Science.gov (United States)

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

    2011-01-01

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

  12. Thermochemical prediction of chemical form distributions of fission products in LWR oxide fuels irradiated to high burnup

    Energy Technology Data Exchange (ETDEWEB)

    Moriyama, Kouki; Furuya, Hirotaka [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

    1997-09-01

    Based on the result of micro-gamma scanning of a fuel pin irradiated to high burnup in a commercial PWR, the radial distribution of chemical forms of fission products (FPs) in LWR fuel pins was theoretically predicted by a thermochemical computer code SOLGASMIX-PV. The absolute amounts of fission products generated in the fuel was calculated by ORIGEN-2 code, and the radial distributions of temperature and oxygen potential were calculated by taking the neutron depression and oxygen redistribution in the fuel into account. A fuel pellet was radially divided into 51 sections and chemical forms of FPs were calculated in each section. In addition, the effects of linear heat rating (LHR) and average O/U ratio on radial distribution of chemical form were evaluated. It was found that approximately 13 mole% of the total amount of Cs compounds exists as CsI and virtually remaining fraction as Cs{sub 2}MoO{sub 4} under the operation condition of LHR below 400 W/cm. On the other hand, when LHR is beyond 400 W/cm under the transient operation condition, its distribution did not change so much from the one under normal operation condition. (author)

  13. Two levels of the inspired oxygen fraction in propofol-anesthetized dogs with high intracranial pressure: cardiopulmonary function

    Directory of Open Access Journals (Sweden)

    P.C. Ferro Lopes

    2014-10-01

    Full Text Available In the initial stage of traumatic brain injury, the use of 1.0 inspired oxygen fraction (FiO2 is indicated. However, high FiO2 has been correlated with atelectasis. Thus, the effects of FiO2 = 1.0 and FiO2 = 0.6 on the cardiopulmonary function in propofol-anesthetized dogs with high intracranial pressure (ICP were evaluated. Eight dogs were anesthetized on two occasions, receiving, during controlled ventilation, an FiO2 = 1 (G100 or an FiO2 = 0.6 (G60. Propofol was used for induction (10mg.kg-1 followed by a continuous rate infusion (0.6mg.kg-1.minute-1. An increase in the ICP was induced by temporary obliteration of the right jugular vein (OJv 50 minutes after induction of anesthesia. The measurement was taken twenty minutes after OJv (T0 and then at 15-minute intervals (T15 to T60. Alveolar oxygen partial pressure in G60 was lower than in G100 during the whole procedure. Alveolar-arterial oxygen gradient in G100 was greater than in G60 at T0 and at T60. No differences were observed for arterial oxygen partial pressure/inspired oxygen fraction ratio, arterial-to-alveolar oxygen pressure ratio, respiratory index, venous admixture, oxygen delivery, oxygen consumption, oxygen extraction, heart rate, mean pulmonary arterial pressure, pulmonary arterial occlusion pressure, cardiac index, stroke index and systemic vascular resistance index. In G100, mean arterial pressure at T0 was higher than at T45. In dogs with high ICP, the cardiopulmonary function was not influenced by the different FiO2 used.

  14. Investigation of the Performance of Low-Cost Calcium-Based Oxygen Carrier in Chemical Looping Combustion of Coal%廉价钙基载氧体煤化学链燃烧试验研究

    Institute of Scientific and Technical Information of China (English)

    施文平; 肖睿; 杨一超; 张帅

    2012-01-01

    化学链燃烧技术逐渐发展成为一项非常有前景的实现CO2高效低能耗分离捕集技术.在小型固定床上研究了廉价钙基载氧体的还原/氧化反应特性以及持续循环能力,讨论了温度、压力、煤/载氧体质量比对钙基载氧体反应特性的影响.试验结果表明,温度和压力的升高能显著增强煤气化产物与CaSO4之间的反应,导致CO2收率和碳转化率相应增加.在煤/载氧体高质量比情况下,由于实际反应过程中存在平行反应、载氧体颗粒内部传质阻力等因素,造成载氧体的失活和载氧能力下降.故为得到高的CO2收率和碳转化率,煤/载氧体质量比应控制在0.14以下.%Chemical-looping combustion(CLC) will be a very promising technology due to its high efficiency and low-cost for CO2 separation.In this paper,the reduction/oxidation characteristic as well as the cyclic performance of low-cost calcium-based oxygen carrier was investigated in a bench-scale fixed-bed reactor.The effect of temperature,operating pressure and coal/oxygen carrier mass ratio on the performance of calcium-based oxygen carrier were discussed.The results showed that increasing temperature and pressure can obviously enhance the reaction of calcium-based oxygen carrier with coal gasification products,which can lead to higher CO2 yield and carbon conversion.Such factors as the parallel reactions and the resistance of internal mass transfer in the oxygen carrier particles in practical reaction lead to inactivation of the oxygen carrier and the decrease of the oxygen carring ability.The coal/oxygen carrier mass ratio should be limited to 0.14 to get higher CO2 yield and carbon conversion.

  15. 76 FR 1067 - Testing of Certain High Production Volume Chemicals; Second Group of Chemicals

    Science.gov (United States)

    2011-01-07

    ...; Albemarle Corporation (Albemarle); American Chemistry Council (ACC); Chlorinated Paraffins Industry... Responsible Medicine (PCRM), the Alternatives Research Development Foundation (ARDF), and the American Anti... Medicine. B. Are these chemical substances produced and/or imported in substantial quantities? EPA...

  16. Oxygen Evolution Assisted Fabrication of Highly Loaded Carbon Nanotube/MnO2 Hybrid Films for High-Performance Flexible Pseudosupercapacitors.

    Science.gov (United States)

    Chen, Hongyuan; Zeng, Sha; Chen, Minghai; Zhang, Yongyi; Zheng, Lianxi; Li, Qingwen

    2016-04-01

    To date, it has been a great challenge to design high-performance flexible energy storage devices for sufficient loading of redox species in the electrode assemblies, with well-maintained mechanical robustness and enhanced electron/ionic transport during charge/discharge cycles. An electrochemical activation strategy is demonstrated for the facile regeneration of carbon nanotube (CNT) film prepared via floating catalyst chemical vapor deposition strategy into a flexible, robust, and highly conductive hydrogel-like film, which is promising as electrode matrix for efficient loading of redox species and the fabrication of high-performance flexible pseudosupercapacitors. The strong and conductive CNT films can be effectively expanded and activated by electrochemical anodic oxygen evolution reaction, presenting greatly enhanced internal space and surface wettability with well-maintained strength, flexibility, and conductivity. The as-formed hydrogel-like film is quite favorable for electrochemical deposition of manganese dioxide (MnO2 ) with loading mass up to 93 wt% and electrode capacitance kept around 300 F g(-1) (areal capacitance of 1.2 F cm(-2) ). This hybrid film was further used to assemble a flexible symmetric pseudosupercapacitor without using any other current collectors and conductive additives. The assembled flexible supercapacitors exhibited good rate performance, with the areal capacitance of more than 300 mF cm(-2) , much superior to other reported MnO2 based flexible thin-film supercapacitors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Electron Attachment to Oxygen and Nitric-Oxide Clusters with High Energy Resolution

    Science.gov (United States)

    Scheier, P.; Senn, G.; Stampfli, P.; Mńrk, T. D.; Chu, Y.; Matejcik, S.; Stamatovic, A.; Illenberger, E.

    Highly monochrornatized electrons (with energy distributions of less than 15 meV FWHM) are used in a crossed beams experiment to investigate electron attachment to oxygen clusters (O2)n and nitric-oxide clusters (NO)n at electron energies from approximately zero eV up to several eV. At energies close to zero the attachment cross section for the reaction (X)n + e → X- (for X=O2 and NO, respectively) rises strongly with decreasing electron energy compatible with s-wave electron capture to Xn. Peaks in the oxygen attachment cross sections present at higher energies (80 meV, 193 meV,…) can be ascribed to vibrational levels of the anion. The vibrational spacings observed can be quantitatively accounted for by model calculations. In contrast, peaks at higher energies (220 meV, 440 meV,…) in the dissociative attachment cross sections for NOn are due to direct excitation of the vibrational levels in neutral NO prior to localization of the excess charge in the cluster (vibrational autoscavenging).

  18. High energy oxygen ion induced modifications in lead based perovskite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jali, V.M. [Department of Physics, Gulbarga University, Gulbarga - 585 106 (India)]. E-mail: vmjali@rediffmail.com; Angadi, Basavaraj [Thin Films Materials Research Center, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Venkateswarlu, P. [Solar Panels Division, ISRO Satellite Centre, Bangalore - 560 017 (India); Kumar, Ravi [Materials Science Division, Inter University Accelerator Center, New-Delhi - 110 067 (India); Krupanidhi, S.B. [Materials Research Centre, Indian Institute of Science, Bangalore - 560 012 (India)

    2007-07-15

    The lead based ferroelectric PbZr{sub 0.53}Ti{sub 0.47}O{sub 3} (PZT), (Pb{sub 0.90}La{sub 0.10})TiO{sub 3} (PLT10) and (Pb{sub 0.80}La{sub 0.20})TiO{sub 3} (PLT20) thin films, prepared by pulsed laser ablation technique, were studied for their response to the 70 MeV oxygen ion irradiation. The dielectric analysis, capacitance-voltage (C-V) and DC leakage current measurements were performed before and after the irradiation to high-energy oxygen ions. The irradiation produced considerable changes in the dielectric, C-V, leakage characteristics and induced some amount of amorphization. The PZT films showed partial recrystallization after a thermal annealing at 400 deg. C for 10 min. The phase transition temperature [T {sub c}] of PLT20 increased from 115 deg. C to 120 deg. C. The DC conductivity measurements showed a shift in the onset of non-linear conduction region. The current density decreased by two orders of magnitude after irradiation. After annealing the irradiated films at a temperature of 400 deg. C for 10 min, the films partially regained the dielectric and electrical properties. The results are discussed in terms of the irradiation-induced amorphization, the pinning of the ferroelectric domains by trapped charges and the thermal annealing of the defects generated during the irradiation.

  19. A reactor for high-temperature pyrolysis and oxygen isotopic analysis of cellulose via induction heating.

    Science.gov (United States)

    Evans, Michael N

    2008-07-01

    A reactor for converting cellulose into carbon monoxide for subsequent oxygen isotopic analysis via continuous flow isotope ratio mass spectrometry is described. The system employs an induction heater to produce temperatures >or=1500 degrees C within a molybdenum foil crucible positioned by boron nitride (BN) spacers within a quartz outer sleeve. For samples of a homogeneous working standard cellulose between 300 and 400 microg in size, the blank/signal ratio is <5%, and the long-term precision is 0.30 per thousand (N = 232). For samples of 30 to 100 microg in size, a gas pressure sintered silicon nitride (Si(3)N(4)) outer sleeve replaces the quartz sleeve, the BN spacers are not used, and 6.0-grade carrier He must be used to minimize the blank signal. With these modifications a blank/sample ratio of <5% and long-term precision of 0.30 per thousand (N = 144) are obtained. These results are similar to those achieved using standard high-temperature furnaces, but the reactor is simpler to pack, the system is more economical to run, and samples as small as 30 microg cellulose may be measured. For both reactors memory is significant in the subsequent sample and is believed to be due to exchange with reactor oxygen at temperatures above 1000 degrees C. Further applications might include online preparation of other materials requiring temperatures of 1500-2600 degrees C.

  20. Redox-Active Metal-Organic Composites for Highly Selective Oxygen Separation Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wen [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Banerjee, Debasis [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Liu, Jian [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Schaef, Herbert T. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Crum, Jarrod V. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Fernandez, Carlos A. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Kukkadapu, Ravi K. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nie, Zimin [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Nune, Satish K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Motkuri, Radha K. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Chapman, Karena W. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Engelhard, Mark H. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Hayes, James C. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Silvers, Kurt L. [National Security Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Krishna, Rajamani [Van' t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904 1098 XH Amsterdam The Netherlands; McGrail, B. Peter [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Liu, Jun [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Thallapally, Praveen K. [Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2016-03-08

    Incorporating, a redox active organometallic molIncorporating, a redox active organometallic molecule within a porous matrix is a useful strategy to form redox active composite materials for emerging applications such as energy storage, electro-catalysis and electro-magnetic separation. Herein we report a new class of stable, redox active metal organic composites for oxygen/air separation with exceptional efficiency. In particular, Ferrocene impregnated in a thermally stable hierarchical porous framework showed a saturation uptake capacity of >51 mg/g for oxygen at a very low relative saturation pressure (P/Po) of 0.06. The material shows excellent O2 selectivity from air as evident from experimental and simulated breakthrough experiments. In detail structural analysis using 57Fe-Mössbauer, X-ray photoelectron spectroscopy (XPS) and pair distribution function (PDF) analysis show that of O2 adsorption affinity and selectivity originates by the formation Fe3+-O oxide due to the highly reactive nature of the organometallics imbedded in the porous matrix.

  1. Oxygen potential measurements in high burnup LWR U0 2 fuel

    Science.gov (United States)

    Matzke, Hj.

    1995-05-01

    A miniature solid state galvanic cell was used to measure the oxygen potential Δ overlineG( O2) of reactor irradiated U0 2 fuel at different burnups in the range of 28 to ⩾ 150 GWd d/t M. This very high burnup was achieved in the rim region of a fuel with a cross section average burnup of 75 GWd d/t M. The fuels had different enrichments and therefore different contributions of fission of 235U and 239Pu. The temperature range covered was 900 to 1350 K. None of the fuels showed a significant oxidation. Rather, if allowance is made for the dissolved rare earth fission products and the Pu formed during irradiation, some of the fuels were very slightly substoichiometric and the highest possible degree of oxidation corresponded to U0 2.001. In general, the Δ overlineG( O2) at 750°C was about -400 kJ/mol, corresponding to the Δ overlineG( O2) of the reaction Mo + O 2 → MoO 2. The implication of these results which are in contrast to commonly assumed ideas that U0 2 fuel oxidizes due to burnup, are discussed and the importance of the fission product Mo and of the zircaloy clad as oxygen buffers is outlined.

  2. Replacement of chemical oxygen demand (COD) with total organic carbon (TOC) for monitoring wastewater treatment performance to minimize disposal of toxic analytical waste.

    Science.gov (United States)

    Dubber, Donata; Gray, Nicholas F

    2010-10-01

    Chemical oxygen demand (COD) is widely used for wastewater monitoring, design, modeling and plant operational analysis. However this method results in the production of hazardous wastes including mercury and hexavalent chromium. The study examined the replacement of COD with total organic carbon (TOC) for general performance monitoring by comparing their relationship with influent and effluent samples from 11 wastewater treatment plants. Biochemical oxygen demand (BOD5) was also included in the comparison as a control. The results show significant linear relationships between TOC, COD and BOD5 in settled (influent) domestic and municipal wastewaters, but only between COD and TOC in treated effluents. The study concludes that TOC can be reliably used for the generic replacement of both COD (COD=49.2+3.00*TOC) and BOD5 (BOD5=23.7+1.68*TOC) in influent wastewaters but only for COD (COD=7.25+2.99*TOC) in final effluents.

  3. PENGGUNAAN LUMPUR AKTIF UNTUK MENURUNKAN KADAR Biological Oxygen Demand (BOD, Chemical Oxygen Demand (COD, dan LOGAM BERAT JENIS TIMBAL (Pb dan CADM IUM (Cd PADA LIMBAH CAIR PENCELUPAN INDUSTRI BATIK

    Directory of Open Access Journals (Sweden)

    RAFICHA RACHMA

    2015-06-01

    Full Text Available In the production process, batik dyeing industry use a lot of water and chemicals in the coloring or dyeing fabric dyeing wastewater batik. Batik dyeing waste industry typically have concentrations of chemical oxygen demand (COD and biological oxygen demand (BOD and heavy metals that exceed quality standards set by the government. In an effort to overcome the problems posed by wastewater, the wastewater treatment process must be done before the waste is discharged into aquatic environment. One of the biological wastewater treatment system that is able to reduce levels of contamination are industrial wastewater is activated sludge system. This research was conducted to determine the optimal time and time effectiveness of treatment with activated sludge to reduce levels of COD, BOD, and Pb in the batik industry wastewater. In this research using activated sludge by taking a fixed volume on sampling from hour o to hour 24 so as to produce organic compounds that remain much lower concentrations can result in COD, BOD, and Pb. This is because the longer the settling time of the volume of waste activated sludge with variable sampling and at the same time a decrease in the percentage levels of COD, BOD, and Pb greater. The results of this research found that activated sludge best influence in lowering the levels of COD, BOD, and Pb. This is due to the activity of microorganisms that have given nutrient and insufficient oxygen in aeration process with the longest time that the ability of the microbes in the sludge to oxidize organic materials with the highest effectiveness in the waste. After going through treatment with activated sludge showed that the optimal time of activated sludge treatment to decrease the levels of COD in wastewater dyeing batik industry is 12 hours, the reduced levels of BOD is 12 hours, and to decrease levels of Pb is 8 hours.

  4. RESEARCH ON CHEMICAL COMPOSITION AND MICROSTRUCTURE OF NEWLY-DEVELOPED HIGH STRENGTH AND HIGH ELONGATION STEELS

    Institute of Scientific and Technical Information of China (English)

    Y. Chen; X. Chen; A.M. Guo; D.X. Luo; B.F. Xu; Z.X. Yuan; P.H. Li; S.K. Pu; S.B. Zhou

    2003-01-01

    The different chemical composition of silicon and manganese as well as different re-tained austenite fraction ranged from 4% to 10% of the high strength and high elon-gation steels were studied in the paper. The dislocations and carbon concentrationin retained austenite were observed by a transmission electron microscope and anelectric probe analyzer, respectively. The experimental results showed that silicon andmanganese are two fundamental alloying elements to stabilize austenite effectively butretaining austenite in different mechanisms. Meanwhile, the cooling processing playedan important role in controlling the fraction of retained austenite of the hot-rolledhigh strength and high plasticity steels.

  5. Study of iron structure stability in high temperature molten lead-bismuth eutectic with oxygen injection using molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Arkundato, Artoto [Physics Department, Faculty of Mathematical and Natural Sciences, Jember University, Jl. Kalimantan 37 Jember (Indonesia); Su' ud, Zaki [Physics Department, Faculty of Mathematical and Natural Sciences, Bandung Institute of Technology, Jl. Ganesha 10, Bandung (Indonesia); Sudarko [Chemistry Department, Faculty of Mathematical and Natural Sciences, Jember University, Jl. Kalimantan 37 Jember (Indonesia); Shafii, Mohammad Ali [Physics Department, Faculty of Mathematical and Natural Sciences, Andalas University, Padang (Indonesia); Celino, Massimo [ENEA, CR Casaccia, Via Anguillarese 301, Rome (Italy)

    2014-09-30

    Corrosion of structural materials in high temperature molten lead-bismuth eutectic is a major problem for design of PbBi cooled reactor. One technique to inhibit corrosion process is to inject oxygen into coolant. In this paper we study and focus on a way of inhibiting the corrosion of iron using molecular dynamics method. For the simulation results we concluded that effective corrosion inhibition of iron may be achieved by injection 0.0532 wt% to 0.1156 wt% oxygen into liquid lead-bismuth. At this oxygen concentration the structure of iron material will be maintained at about 70% in bcc crystal structure during interaction with liquid metal.

  6. A New Approach for Removal of Nitrogen Oxides from Synthetic Gas-streams under High Concentration of Oxygen in Biofilters

    Institute of Scientific and Technical Information of China (English)

    Shao Bin HUANG; Ju Guang ZHANG; He Ping HU; Yue SITU

    2005-01-01

    The potential of using denitrifying and nitrifying concurrent biofilters for the removal of nitrogen oxides from synthetic gas streams was studied under the condition of high oxygen concentration. It was found that more than 85% of nitric oxide was removed from synthetic combustion gas-streams which contained 20% oxygen and 350 μL/L NO, with a residence time of60 seconds. In the process, it was found that the existing of oxygen showed no evident negative effect on the efficiency of nitrogen removal.

  7. Impact of high oxygen and vacuum retail ready packaging formats on lamb loin and topside eating quality.

    Science.gov (United States)

    Frank, Damian Conrad; Geesink, Geert; Alvarenga, Tharcilla I R C; Polkinghorne, Rod; Stark, Janet; Lee, Michael; Warner, Robyn

    2017-01-01

    Lamb steaks from semimembranosus (SM) and longissimus thoracis et lumborum (LTL) muscles were allocated to three different packaging treatments - Darfresh® vacuum skin packaging (VSP), Darfresh® Bloom packaging (80% O2:20% CO2; Hi-Ox-DB) or high oxygen modified atmosphere packaging (80% O2:20% CO2; Hi-Ox-MAP) - and stored in simulated retail display for 5 or 10days and then subjected to consumer sensory and chemical analyses. Hi-Ox-MAP and Hi-Ox-DB samples had lower tenderness, flavor, juiciness and overall liking scores and higher TBARS values, compared to VSP. Hi-Ox-MAP samples deteriorated in juiciness and flavor between 5 and 10days. Hi-Ox-MAP LTL samples had a lower myofibrillar fragmentation index, consistent with reduced proteolysis, although desmin proteolysis and desmin and troponin-T cross-linking were not influenced by packaging. The LTL exhibited greater desmin degradation and reduced desmin cross-linking relative to the SM, supporting the higher tenderness scores in this muscle. Direct packaging of lamb into retail ready VSP may provide the sheepmeat industry with greater flexibility while increasing consumer satisfaction.

  8. Preparation of high-content hexagonal boron nitride composite film and characterization of atomic oxygen erosion resistance

    Science.gov (United States)

    Zhang, Yu; Li, Min; Gu, Yizhuo; Wang, Shaokai; Zhang, Zuoguang

    2017-04-01

    Space aircrafts circling in low earth orbit are suffered from highly reactive atomic oxygen (AO). To shield AO, a flexible thin film with 80 wt.% hexagonal boron nitride (h-BN) and h-BN/epoxy film were fabricated through vacuum filtration and adding nanofibrillated cellulose fibers. H-BN nanosheets were hydroxylated for enhancing interaction in the films. Mass loss and erosion yield at accumulated AO fluence about 3.04 × 1020 atoms/cm2 were adopted to evaluate the AO resistance properties of the films. A carpet-like rough surface, chemical oxidations and change in crystal structure of h-BN were found after AO treatment, and the degrading mechanism was proposed. The mass loss and erosion yield under AO attack were compared between h-BN film and h-BN/epoxy film, and the comparison was also done for various types of shielding AO materials. Excellent AO resistance property of h-BN film is shown, and the reasons are analyzed.

  9. Nitrogen-doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Du, Lei; Luo, Langli; Feng, Zhenxing; Engelhard, Mark H.; Xie, Xiaohong; Han, Binghong; Sun, Junming; Zhang, Jianghao; Yin, Geping; Wang, Chongmin; Wang, Yong; Shao, Yuyan

    2017-09-01

    Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and durability. Herein, we report a highly active (360 mV overpotential at 10 mA cm–2GEO) and durable (no degradation after 20000 cycles) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron−donation/deviation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.

  10. Managing High-Altitude Pulmonary Edema with Oxygen Alone: Results of a Randomized Controlled Trial.

    Science.gov (United States)

    Yanamandra, Uday; Nair, Velu; Singh, Surinderpal; Gupta, Amul; Mulajkar, Deepak; Yanamandra, Sushma; Norgais, Konchok; Mukherjee, Ruchira; Singh, Vikrant; Bhattachar, Srinivasa A; Patyal, Sagarika; Grewal, Rajan; Chopra, Bhushan

    2016-12-01

    Yanamandra, Uday, Velu Nair, Surinderpal Singh, Amul Gupta, Deepak Mulajkar, Sushma Yanamandra, Konchok Norgais, Ruchira Mukherjee, Vikrant Singh, Srinivasa A. Bhattachar, Sagarika Patyal, and Rajan Grewal. High-altitude pulmonary edema management: Is anything other than oxygen required? Results of a randomized controlled trial. High Alt Med Biol. 17:294-299, 2016.-Treatment strategies for management of high-altitude pulmonary edema (HAPE) are mainly based on the observational studies with only two randomized controlled trials, thus the practice is very heterogeneous and individualized as per the choice of treating physician. To compare the response to different modalities of therapy in patients with HAPE in a randomized controlled manner. We conducted an open-label, randomized noninferiority trial to compare three modalities of therapy (Therapy 1: supplemental O2 with oral dexamethasone 8 mg q8 hours [n = 42], Therapy 2: supplemental O2 with sustained release oral nifedipine 20 mg q8 hours [n = 41], and Therapy 3: only supplemental O2 [n = 50]). Bed rest was mandated in all patients. The study was conducted in a cohort of previously healthy young lowlander males at an altitude of 3500 m. Baseline characteristics of the patients were comparable in the study arms. Complete response was defined as clinical and radiological resolution of features of HAPE, no oxygen dependency, a normal 6-minute walk test (6MWT) on 2 consecutive days, and normal two-dimensional echocardiography. Results were compared by analysis of variance using SPSS version 16.0. There was no statistical difference in duration of therapy to complete response between the three groups (Therapy 1: 8.1 ± 4.0 days, Therapy 2: 6.7 ± 3.9 days, Therapy 3: 6.8 ± 3.2 days; p = 0.15). There were no deaths in any of the groups. We conclude that oxygen and bed rest alone are adequate therapy for HAPE and that adjuvant pharmacotherapy with either dexamethasone or nifedipine

  11. Effect of oxygen on the production of abnormally high heats of interaction with hydrogen chemisorbed on gold

    Energy Technology Data Exchange (ETDEWEB)

    Groszek, A.J., E-mail: info@microscal.com [Microscal Limited, 79 Southern Row, London W10 5AL (United Kingdom); Institute of Catalysis and Surface Chemistry, Polish Academy of Science, ul.Niezapominajek 8, Krakow 30-239 (Poland); Lalik, E. [Institute of Catalysis and Surface Chemistry, Polish Academy of Science, ul.Niezapominajek 8, Krakow 30-239 (Poland)

    2011-02-01

    Abnormally high heats, exceeding 1600 kJ/mol (16 eV) per molecular oxygen, are generated by interaction of the oxygen with the hydrogen adsorbed on gold surfaces at 125 deg. C. The highest heats were observed during the interactions of fine gold particles supported on titanium oxide, approaching 1700 kJ/mol for three consecutive 100 nmol pulses of O{sub 2} interacting with the adsorbed hydrogen atoms. The heats rapidly decrease after the hydrogen is consumed. It was also observed that the interactions of the gold particles with pure oxygen in the presence of noble gases, such as argon and helium, produced the heats markedly higher than those observed in the absence of noble gases. The abnormally high heats revealed by this work reach values from 3.5 to 6.1 times higher than the heats of formation of gaseous water from molecular hydrogen and oxygen.

  12. Role of H2O2 in the fluctuating patterns of COD (chemical oxygen demand) during the treatment of palm oil mill effluent (POME) using pilot scale triple frequency ultrasound cavitation reactor.

    Science.gov (United States)

    Manickam, Sivakumar; Abidin, Norhaida binti Zainal; Parthasarathy, Shridharan; Alzorqi, Ibrahim; Ng, Ern Huay; Tiong, Timm Joyce; Gomes, Rachel L; Ali, Asgar

    2014-07-01

    Palm oil mill effluent (POME) is a highly contaminating wastewater due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Conventional treatment methods require longer residence time (10-15 days) and higher operating cost. Owing to this, finding a suitable and efficient method for the treatment of POME is crucial. In this investigation, ultrasound cavitation technology has been used as an alternative technique to treat POME. Cavitation is the phenomenon of formation, growth and collapse of bubbles in a liquid. The end process of collapse leads to intense conditions of temperature and pressure and shock waves which assist various physical and chemical transformations. Two different ultrasound systems i.e. ultrasonic bath (37 kHz) and a hexagonal triple frequency ultrasonic reactor (28, 40 and 70 kHz) of 15 L have been used. The results showed a fluctuating COD pattern (in between 45,000 and 60,000 mg/L) while using ultrasound bath alone, whereas a non-fluctuating COD pattern with a final COD of 27,000 mg/L was achieved when hydrogen peroxide was introduced. Similarly for the triple frequency ultrasound reactor, coupling all the three frequencies resulted into a final COD of 41,300 mg/L compared to any other individual or combination of two frequencies. With the possibility of larger and continuous ultrasonic cavitational reactors, it is believed that this could be a promising and a fruitful green process engineering technique for the treatment of POME.

  13. A primordial origin for molecular oxygen in comets: A chemical kinetics study of the formation and survival of O2 ice from clouds to disks

    Science.gov (United States)

    Taquet, V.; Furuya, K.; Walsh, C.; van Dishoeck, E. F.

    2016-09-01

    Molecular oxygen has been confirmed as the fourth most abundant molecule in cometary material (O2/H2O ˜4 %) and is thought to have a primordial nature, i.e., coming from the interstellar cloud from which our solar system was formed. However, interstellar O2 gas is notoriously difficult to detect and has only been observed in one potential precursor of a solar-like system. Here, the chemical and physical origin of O2 in comets is investigated using sophisticated astrochemical models. Three origins are considered: i) in dark clouds, ii) during forming protostellar disks, and iii) during luminosity outbursts in disks. The dark cloud models show that reproduction of the observed abundance of O2 and related species in comet 67P/C-G requires a low H/O ratio facilitated by a high total density (≥105 cm-3), and a moderate cosmic ray ionisation rate (≤10-16 s-1) while a temperature of 20 K, slightly higher than the typical temperatures found in dark clouds, also enhances the production of O2. Disk models show that O2 can only be formed in the gas phase in intermediate disk layers, and cannot explain the strong correlation between O2 and H2O in comet 67P/C-G together with the weak correlation between other volatiles and H2O. However, primordial O2 ice can survive transport into the comet-forming regions of disks. Taken together, these models favour a dark cloud (or "primordial") origin for O2 in comets, albeit for dark clouds which are warmer and denser than those usually considered as solar system progenitors.

  14. A primordial origin for molecular oxygen in comets: a chemical kinetics study of the formation and survival of O2ice from clouds to discs

    Science.gov (United States)

    Taquet, V.; Furuya, K.; Walsh, C.; van Dishoeck, E. F.

    2016-11-01

    Molecular oxygen has been confirmed as the fourth most abundant molecule in cometary material O$_2$/H$_2$O $\\sim 4$ %) and is thought to have a primordial nature, i.e., coming from the interstellar cloud from which our solar system was formed. However, interstellar O$_2$ gas is notoriously difficult to detect and has only been observed in one potential precursor of a solar-like system. Here, the chemical and physical origin of O$_2$ in comets is investigated using sophisticated astrochemical models. Three origins are considered: i) in dark clouds, ii) during forming protostellar disks, and iii) during luminosity outbursts in disks. The dark cloud models show that reproduction of the observed abundance of O$_2$ and related species in comet 67P/C-G requires a low H/O ratio facilitated by a high total density ($\\geq 10^5$ cm$^{-3}$), and a moderate cosmic ray ionisation rate ($\\leq 10^{-16}$ s$^{-1}$) while a temperature of 20 K, slightly higher than the typical temperatures found in dark clouds, also enhances the production of O$_2$. Disk models show that O$_2$ can only be formed in the gas phase in intermediate disk layers, and cannot explain the strong correlation between O$_2$ and H$_2$O in comet 67P/C-G together with the weak correlation between other volatiles and H$_2$O. However, primordial O$_2$ ice can survive transport into the comet-forming regions of disks. Taken together, these models favour a dark cloud (or "primordial") origin for O$_2$ in comets, albeit for dark clouds which are warmer and denser than those usually considered as solar system progenitors.

  15. Effect of an oxygen plasma on the physical and chemical properties of several fluids for the Liquid Droplet Radiator

    Science.gov (United States)

    Gulino, Daniel A.; Coles, Carolyn E.

    1987-01-01

    The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethylsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed depolymerization of the fluid molecule.

  16. Zambian pre-service junior high school science teachers' chemical reasoning and ability

    Science.gov (United States)

    Banda, Asiana

    The purpose of this study was two-fold: examine junior high school pre-service science teachers' chemical reasoning; and establish the extent to which the pre-service science teachers' chemical abilities explain their chemical reasoning. A sample comprised 165 junior high school pre-service science teachers at Mufulira College of Education in Zambia. There were 82 males and 83 females. Data were collected using a Chemical Concept Reasoning Test (CCRT). Pre-service science teachers' chemical reasoning was established through qualitative analysis of their responses to test items. The Rasch Model was used to determine the pre-service teachers' chemical abilities and item difficulty. Results show that most pre-service science teachers had incorrect chemical reasoning on chemical concepts assessed in this study. There was no significant difference in chemical understanding between the Full-Time and Distance Education pre-service science teachers, and between second and third year pre-service science teachers. However, there was a significant difference in chemical understanding between male and female pre-service science teachers. Male pre-service science teachers showed better chemical understanding than female pre-service science teachers. The Rasch model revealed that the pre-service science teachers had low chemical abilities, and the CCRT was very difficult for this group of pre-service science teachers. As such, their incorrect chemical reasoning was attributed to their low chemical abilities. These results have implications on science teacher education, chemistry teaching and learning, and chemical education research.

  17. Chemically and Thermally Stable High Energy Density Silicone Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal energy storage systems with 300 ? 1000 kJ/kg energy density through either phase changes or chemical heat absorption are sought by NASA. This proposed effort...

  18. Activated carbon fibers with a high heteroatom content by chemical activation of PBO with phosphoric acid.

    Science.gov (United States)

    Vázquez-Santos, M B; Suárez-García, F; Martínez-Alonso, A; Tascón, J M D

    2012-04-03

    The preparation of activated carbon fibers (ACFs) by phosphoric acid activation of poly(p-phenylene benzobisoxazole) (PBO) fibers was studied, with particular attention to the effects of impregnation ratio and carbonization temperature on porous texture. Phosphoric acid has a strong effect on PBO degradation, lowering the temperature range at which the decomposition takes place and changing the number of mass loss steps. Chemical analysis results indicated that activation with phosphoric acid increases the concentration of oxygenated surface groups; the resulting materials also exhibiting high nitrogen content. ACFs are obtained with extremely high yields; they have well-developed porosity restricted to the micropore and narrow mesopore range and with a significant concentration of phosphorus incorporated homogeneously in the form of functional groups. An increase in the impregnation ratio leads to increases in both pore volume and pore size, maximum values of surface area (1250 m(2)/g) and total pore volume (0.67 cm(3)/g) being attained at the highest impregnation ratio (210 wt % H(3)PO(4)) and lowest activation temperature (650 °C) used; the corresponding yield was as large as 83 wt %. The obtained surface areas and pore volumes were higher than those achieved in previous works by physical activation with CO(2) of PBO chars.

  19. Effect of a high strength chemical industry wastewater on microbial community dynamics and mesophilic methane generation.

    Science.gov (United States)

    Venkatakrishnan, Harish; Tan, Youming; Majid, Maszenan Bin Abdul; Pathak, Santosh; Sendjaja, Antonius Yudi; Li, Dongzhe; Liu, Jerry Jian Lin; Zhou, Yan; Ng, Wun Jern

    2014-04-01

    A high strength chemical industry wastewater was assessed for its impact on anaerobic microbial community dynamics and consequently mesophilic methane generation. Cumulative methane production was 251 mL/g total chemical oxygen demand removed at standard temperature and pressure at the end of 30 days experimental period with a highest recorded methane percentage of 80.6% of total biogas volume. Volatile fatty acids (VFAs) analysis revealed that acetic acid was the major intermediate VFAs produced with propionic acid accumulating over the experimental period. Quantitative analysis of microbial communities in the test and control groups with quantitative real time polymerase chain reaction highlighted that in the test group, Eubacteria (96.3%) was dominant in comparison with methanogens (3.7%). The latter were dominated by Methanomicrobiales and Methanobacteriales while Methanosarcinaceae in test groups increased over the experimental period, reaching a maximum on day 30. Denaturing gradient gel electrophoresis profile was performed, targeting the 16S rRNA gene of Eubacteria and Archaea, with the DNA samples extracted at 3 different time points from the test groups. A phylogenetic tree was constructed for the sequences using the neighborhood joining method. The analysis revealed that the presence of organisms resembling Syntrophomonadaceae could have contributed to increased production of acetic and propionic acid intermediates while decrease of organisms resembling Pelotomaculum sp. could have most likely contributed to accumulation of propionic acid. This study suggested that the degradation of organic components within the high strength industrial wastewater is closely linked with the activity of certain niche microbial communities within eubacteria and methanogens.

  20. Solid-State Raman Converters for High-Average Power Chemical Oxygen Iodine Laser

    Science.gov (United States)

    1998-01-01

    spectral resolution of the system was 0.2-1.0 cmŕ. The argon laser plasma discharge lines were cut by an additional ÖD •TM...Principles of Nonlinear Optics. New York; Wiley, 1984, ch. 10. 15. R. L. Carman , F. Shimizu, C. S. Wang, and N. Bloembergen, "Theory of Stokes pulse shapes

  1. High-performance oxygen reduction catalyst derived from porous, nitrogen-doped carbon nanosheets

    Science.gov (United States)

    Wang, Hao; Chen, Kai; Cao, Yingjie; Zhu, Juntong; Jiang, Yining; Feng, Lai; Dai, Xiao; Zou, Guifu

    2016-10-01

    A facile, self-foaming strategy is reported to synthesize porous, nitrogen-doped carbon nanosheets (N-CNSs) as a metal-free electrocatalyst for oxygen reduction reaction (ORR). Benefiting from the synergistic functions of N-induced active sites, a highly specific surface area and continuous structure, the optimal N-CNS catalyst exhibits Pt-like ORR activity (positive onset potential of ˜0 V versus Ag/AgCl and limiting current density of 5 mA cm-2) through a four-electron transfer process in alkaline media with excellent cycle stability and methanol tolerance. This work not only provides a promising metal-free ORR catalyst but also opens up a new path for designing carbon-based materials towards broad applications.

  2. Tooth enamel oxygen “isoscapes” show a high degree of human mobility in prehistoric Britain

    Science.gov (United States)

    Pellegrini, Maura; Pouncett, John; Jay, Mandy; Pearson, Mike Parker; Richards, Michael P.

    2016-10-01

    A geostatistical model to predict human skeletal oxygen isotope values (δ18Op) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as ‘non-local’ to the areas where they were buried (spatial outliers). A marked variation in δ18Op is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ18O values-a process known to be problematic.

  3. Molecular mechanisms regulating oxygen transport and consumption in high altitude and hibernating mammals

    DEFF Research Database (Denmark)

    Revsbech, Inge Grønvall

    2016-01-01

    The aim of this thesis is to broaden the knowledge of molecular mechanisms of adjustment in oxygen (O2) uptake, conduction, delivery and consumption in mammals adapted to extreme conditions. For this end, I have worked with animals living at high altitude as an example of environmental hypoxia......, and hibernating mammals, as an example of closely balanced internal low O2. Studies have had two main focus points. Firstly, I have investigated variations in hemolysate and hemoglobin (Hb) O2 affinity, working to pinpoint whether and how functional changes in intrinsic affinity or cofactor sensitivity of the Hb...... molecule compares to amino acid substitutions in the molecule, i.e., can be characterized as evolved genetic adaptation. Phenotypic acclimatization in Hb- O2 affinity responses involves changes in cofactor to Hb tetramer ratio. Secondly, I have worked with (in a cardiovascular perspective) fine...

  4. Pt Monolayer Shell on Nitrided Alloy Core—A Path to Highly Stable Oxygen Reduction Catalyst

    Directory of Open Access Journals (Sweden)

    Jue Hu

    2015-07-01

    Full Text Available The inadequate activity and stability of Pt as a cathode catalyst under the severe operation conditions are the critical problems facing the application of the proton exchange membrane fuel cell (PEMFC. Here we report on a novel route to synthesize highly active and stable oxygen reduction catalysts by depositing Pt monolayer on a nitrided alloy core. The prepared PtMLPdNiN/C catalyst retains 89% of the initial electrochemical surface area after 50,000 cycles between potentials 0.6 and 1.0 V. By correlating electron energy-loss spectroscopy and X-ray absorption spectroscopy analyses with electrochemical measurements, we found that the significant improvement of stability of the PtMLPdNiN/C catalyst is caused by nitrogen doping while reducing the total precious metal loading.

  5. Oxidation of High-temperature Alloy Wires in Dry Oxygen and Water Vapor

    Science.gov (United States)

    Opila, Elizabeth J.; Lorincz, Jonathan A.; DeMange, Jeffrey J.

    2004-01-01

    Small diameter wires (150 to 250 microns) of the high temperature alloys Haynes 188, Haynes 230, Haynes 230, Haynes 214, Kanthal Al and PM2000 were oxidized at 1204 C in dry oxygen or 50% H2O /50% O2 for 70 Hours. The oxidation kinetics were monitored using a thermogravimetric technique. Oxide phase composition and morphology of the oxidized wires were determined by X-ray diffraction,field emission scanning electron microscopy, and energy dispersive spectroscopy. The alumina-forming alloys, Kanthal Al and PM2000, out-performed the chromia-forming alloys under this conditions. PM2000 was recommended as the most promising candidate for advanced hybrid seal applications for space reentry control surface seals or hypersonic propulsion system seals. This study also demonstrated that thermogravimetric analysis of small diameter wires is a powerful technique for the study of oxide volatility, oxide adherence, and breakaway oxidation.

  6. Highly oxygenated chromones from mangrove-derived endophytic fungus Rhytidhysteron rufulum.

    Science.gov (United States)

    Chokpaiboon, Supichar; Choodej, Siwattra; Boonyuen, Nattawut; Teerawatananond, Thapong; Pudhom, Khanitha

    2016-02-01

    Five highly oxygenated chromones, rhytidchromones A-E, were isolated from the culture broth of a mangrove-derived endophytic fungus, Rhytidhysteron rufulum, isolated from Thai Bruguiera gymnorrhiza. Their structures were determined by analysis of 1D and 2D NMR spectroscopic data. The structure of rhytidchromone A was further confirmed by single-crystal X-ray diffraction analysis. These compounds were evaluated for cytotoxicity against four cancer cell lines (MCF-7, Hep-G2, Kato-3 and CaSki). All compounds, except for rhytidchromone D, displayed cytotoxicity against Kato-3 cell lines with IC50 values ranging from 16.0 to 23.3μM, while rhytidchromones A and C were active against MCF-7 cells with IC50 values of 19.3 and 17.7μM, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Microstructure Characterization of WCCo-Mo Based Coatings Produced Using High Velocity Oxygen Fuel

    Directory of Open Access Journals (Sweden)

    Serkan Islak

    2015-12-01

    Full Text Available The present study has been carried out in order to investigate the microstructural properties of WCCo-Mo composite coatings deposited onto a SAE 4140 steel substrate by high velocity oxygen fuel (HVOF thermal spray. For this purpose, the Mo quantity added to the WCCo was changed as 10, 20, 30 and 40 wt. % percents. The coatings are compared in terms of their phase composition, microstructure and hardness. Phase compound and microstructure of coating layers were examined using X-ray diffractometer (XRD and scanning electron microscope (SEM. XRD results showed that WCCo-Mo composite coatings were mainly composed of WC, W2C, Co3W3C, Mo2C, MoO2, Mo and Co phases. The average hardness of the coatings increased with increasing Mo content.

  8. DYNAMIC ANALYSIS OF PARTICLE FLYING VELOCITY IN HIGH VELOCITY OXYGEN FUEL SPRAY

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiping; Dong Zujue; Huo Shubin

    2000-01-01

    Based on gas dynamics,thermodynamics,fluid dynamics of multiphase systems and other theories,the dynamic analyses of the particle flying velocity in a high velocity oxygen fuel spray (HVOF) is accomplished.The relationships between the flying velocity of a particle and the flying time or flying length,particle size,hot gas velocity,and pressure or density of the gas are proposed.Meanwhile,the influences of the velocity and mass rate of flow of the flame gas of a HVOF gun,and particle size on the particle flying velocity are discussed in detail.The dynamic pressure concept is introduced to express the flow capacity of hot gas of a HVOF gun,and the relationship between the dynamic pressure of a HVOF gun and the velocity of a particle for depositing is presented.

  9. CHEMICALS

    CERN Document Server

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  10. Oxygen Therapy

    Science.gov (United States)

    ... oxygen at very high altitudes (like in the mountains or in an airplane) even if you do ... Med Vol 171. P1-P2, 2005 ATS Patient Education Series © 2016 American Thoracic Society www. thoracic. org ...

  11. Hydrogen/Oxygen Reactions at High Pressures and Intermediate Temperatures: Flow Reactor Experiments and Kinetic Modeling

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Glarborg, Peter

    A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, ignition occurs at the temperature of 775–800 K. In general, the present model provides a good agreement with the measurements in the flow reactor and with recent data on laminar burning velocity and ignition delay time.......A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, the mechanism is used to simulate published data on ignition delay time and laminar burning velocity of hydrogen. The flow reactor results show that at reducing, stoichiometric, and oxidizing conditions, conversion starts at temperatures of 750–775 K, 800–825 K, and 800–825 K, respectively. In oxygen atmosphere...

  12. Development of the orpheus perfusion simulator for use in high-fidelity extracorporeal membrane oxygenation simulation.

    Science.gov (United States)

    Lansdowne, William; Machin, David; Grant, David J

    2012-12-01

    Despite its life-sustaining potential, extracorporeal membrane oxygenation (ECMO) remains a complex treatment modality for which close teamwork is imperative with a high risk of adverse events leading to significant morbidity and mortality. The provision of adequate training and continuing education is key in mitigating these risks. Traditional training for ECMO has relied predominantly on didactic education and hands-on water drills. These methods may overemphasize cognitive skills while underemphasizing technical skills and completely ignoring team and human factor skills. These water drills are often static, lacking the time pressure, typical alarms, and a sense of urgency inherent to actual critical ECMO scenarios. Simulation-based training provides an opportunity for staff to develop and maintain technical proficiency in high-risk, infrequent events without fear of harming patients. In addition, it provides opportunities for interdisciplinary training and improved communication and teamwork among team members (1). Although simulation has become widely accepted for training of practitioners from many disciplines, there are currently, to our knowledge, no commercially available dedicated high-fidelity ECMO simulators. Our article describes the modification of the Orpheus Perfusion Simulator and its incorporation into a fully immersive, high-fidelity, point-of-care ECMO simulation model.

  13. A Facile Synthesis of Nitrogen-Doped Highly Porous Carbon Nanoplatelets: Efficient Catalysts for Oxygen Electroreduction

    Science.gov (United States)

    Zhang, Yaqing; Zhang, Xianlei; Ma, Xiuxiu; Guo, Wenhui; Wang, Chunchi; Asefa, Tewodros; He, Xingquan

    2017-01-01

    The oxygen reduction reaction (ORR) is of great importance for various renewable energy conversion technologies such as fuel cells and metal-air batteries. Heteroatom-doped carbon nanomaterials have proven to be robust metal-free electrocatalysts for ORR in the above-mentioned energy devices. Herein, we demonstrate the synthesis of novel highly porous N-doped carbon nanoplatelets (N-HPCNPs) derived from oatmeal (or a biological material) and we show the materials’ high-efficiency as electrocatalyst for ORR. The obtained N-HPCNPs hybrid materials exhibit superior electrocatalytic activities towards ORR, besides excellent stability and good methanol tolerance in both basic and acidic electrolytes. The unique nanoarchitectures with rich micropores and mesopores, as well as the high surface area-to-volume ratios, present in the materials significantly increase the density of accessible catalytically active sites in them and facilitate the transport of electrons and electrolyte within the materials. Consequently, the N-HPCNPs catalysts hold a great potential to serve as low-cost and highly efficient cathode materials in direct methanol fuel cells (DMFCs). PMID:28240234

  14. A Facile Synthesis of Nitrogen-Doped Highly Porous Carbon Nanoplatelets: Efficient Catalysts for Oxygen Electroreduction.

    Science.gov (United States)

    Zhang, Yaqing; Zhang, Xianlei; Ma, Xiuxiu; Guo, Wenhui; Wang, Chunchi; Asefa, Tewodros; He, Xingquan

    2017-02-27

    The oxygen reduction reaction (ORR) is of great importance for various renewable energy conversion technologies such as fuel cells and metal-air batteries. Heteroatom-doped carbon nanomaterials have proven to be robust metal-free electrocatalysts for ORR in the above-mentioned energy devices. Herein, we demonstrate the synthesis of novel highly porous N-doped carbon nanoplatelets (N-HPCNPs) derived from oatmeal (or a biological material) and we show the materials' high-efficiency as electrocatalyst for ORR. The obtained N-HPCNPs hybrid materials exhibit superior electrocatalytic activities towards ORR, besides excellent stability and good methanol tolerance in both basic and acidic electrolytes. The unique nanoarchitectures with rich micropores and mesopores, as well as the high surface area-to-volume ratios, present in the materials significantly increase the density of accessible catalytically active sites in them and facilitate the transport of electrons and electrolyte within the materials. Consequently, the N-HPCNPs catalysts hold a great potential to serve as low-cost and highly efficient cathode materials in direct methanol fuel cells (DMFCs).

  15. High-resolution 17O double-rotation NMR characterization of ring and non-ring oxygen in vitreous B2O3.

    Science.gov (United States)

    Wong, Alan; Howes, Andy P; Parkinson, Ben; Anupõld, Tiit; Samoson, Ago; Holland, Diane; Dupree, Ray

    2009-08-28

    The application of double rotation (DOR) NMR to crystalline materials (both inorganic and organic) has made tremendous strides in providing site-specific information about materials in recent years. However (17)O DOR has yet to demonstrate its potential in disordered materials such as glasses. In the present study, we have successfully recorded high resolution (17)O DOR spectra of vitreous B(2)O(3) (v-B(2)O(3)), a highly effective glass-forming oxide of considerable technological importance. Two distinct oxygen sites are resolved and a complete set of (17)O NMR parameters were determined from the DOR spectra. These were assigned to oxygen atoms in the planar boroxol ring [B(3)O(6)] and in the non-boroxol [BO(3)] groups which share oxygen with the ring boron atoms. This assignment was based on the similarity of all of their (17)O parameters with those found by DFT calculation for caesium enneaborate, Cs(2)O.9B(2)O(3), which has two boroxol rings in its structure. The boroxol ring oxygens have a more positive chemical shift, a larger shift anisotropy and a smaller electric field gradient than non ring oxygens (O(R): delta(iso) = 100 +/- 1 ppm, span = 180 +/- 20 ppm, skew = -0.4 +/- 0.1, P(q) = 5.0 +/- 0.2 MHz; O(NR): delta(iso) = 86 +/- 1 ppm, span = 100 +/- 20 ppm, skew = 0.1 +/- 0.1, P(q) = 5.7 +/- 0.2 MHz). The relative proportions of the two sites in v-B(2)O(3) are approximately 1 : 1, as expected if all three boron atoms in the boroxol ring are each connected to one oxygen in a linking [BO(3)] group and there are very few [BO(3)]-[BO(3)] linkages. We see no evidence for a third oxygen site such as has been reported in an earlier study of v-B(2)O(3). This work demonstrates the potential of (17)O DOR to provide site-specific information in disordered materials.

  16. The Interconversion of Electrical and Chemical Energy: The Electrolysis of Water and the Hydrogen-Oxygen Fuel Cell.

    Science.gov (United States)

    Roffia, Sergio; And Others

    1988-01-01

    Discusses some of the drawbacks of using a demonstration of the electrolysis of water to illustrate the interconversion between electrical and chemical energy. Illustrates a simple apparatus allowing demonstration of this concept while overcoming these drawbacks. (CW)

  17. The Interconversion of Electrical and Chemical Energy: The Electrolysis of Water and the Hydrogen-Oxygen Fuel Cell.

    Science.gov (United States)

    Roffia, Sergio; And Others

    1988-01-01

    Discusses some of the drawbacks of using a demonstration of the electrolysis of water to illustrate the interconversion between electrical and chemical energy. Illustrates a simple apparatus allowing demonstration of this concept while overcoming these drawbacks. (CW)

  18. Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum.

    Science.gov (United States)

    Lee, Ho Nyung; Ambrose Seo, Sung S; Choi, Woo Seok; Rouleau, Christopher M

    2016-01-29

    In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on single crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Therefore, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but expands the utility of pulsed laser epitaxy of other materials as well.

  19. Nitrogen-doped MoS2/carbon as highly oxygen-permeable and stable catalysts for oxygen reduction reaction in microbial fuel cells

    Science.gov (United States)

    Hao, Liang; Yu, Jia; Xu, Xin; Yang, Liu; Xing, Zipeng; Dai, Ying; Sun, Ye; Zou, Jinlong

    2017-01-01

    Developing non-noble metal catalysts with high oxygen-permeability and activity for oxygen reduction reaction (ORR) is crucial for microbial fuel cells (MFCs). In this study, nitrogen-doped molybdenum disulfide/carbon (N-MoS2/C) is prepared using melamine as nitrogen and carbon sources. Ammonium molybdate, thiourea and Pluronic F127 are used as Mo source, S source and surfactant, respectively. Mo-S-melamine complex precursor is obtained through the evaporation-induced self-assembly route, which is then carbonized at 800, 900 and 1000 °C to fabricate N-MoS2/C. Defect-rich N-MoS2/C has a large number of exposed active sites and a high oxygen permeability. N-MoS2/C (900 °C) with regular honeycomb structure shows the maximum power density of 0.815 W m-2, which is far higher than that of Pt/C (0.520 W m-2) and only has a decline of 1.23% after 1800 h operation in MFCs. Four-electron (4e-) reduction of O2 is the main ORR pathway for N-MoS2/C (900 °C), attributing to the efficient permeation, adsorption, activation and reduction of O2 on the active sites. The synergy among abundant defects, N-species (pyridinic N, graphitic N and Mo-Nx) and high conductivity contributes to the promising ORR activity. This simple synthetic route of N-doped metal sulfides/carbon composites displays a new prospect for preparation of ORR catalyst.

  20. Chemical equilibrium in high pressure molecular fluid mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M.S.

    1993-09-01

    The N{sub atoms}PT Monte Carlo simulation method has been reformulated to incorporate multiple species and chemical reactions with changes in total number of molecules. While maintaining a constant number of each type of atom, the number of molecules is changed by turning on and off the interactions of any particular position with other molecules. Chemical reactions are allowed as a correlated move of atoms to differnt molecular locations. Equilibrium chemical composition is determined as an average over the simulation along with equation of state quantities. A large set of simulations has been made with the system N{sub 2} + O{sub 2} {rightleftharpoons} NO covering a wide range in P and T. Both Hugoniot states and the CJ point have been determined and are shown to be sensitive to the potentials between unlike species.

  1. Oxygen concentration control of dopamine-induced high uniformity surface coating chemistry.

    Science.gov (United States)

    Kim, Hyo Won; McCloskey, Bryan D; Choi, Tae Hwan; Lee, Changho; Kim, Min-Joung; Freeman, Benny D; Park, Ho Bum

    2013-01-23

    Material surface engineering has attracted great interest in important applications, including electronics, biomedicine, and membranes. More recently, dopamine has been widely exploited in solution-based chemistry to direct facile surface modification. However, unsolved questions remain about the chemical identity of the final products, their deposition kinetics and their binding mechanism. In particular, the dopamine oxidation reaction kinetics is a key to improving surface modification efficiency. Here, we demonstrate that high O(2) concentrations in the dopamine solution lead to highly homogeneous, thin layer deposition on any material surfaces via accelerated reaction kinetics, elucidated by Le Chatelier's principle toward dopamine oxidation steps in a Michael-addition reaction. As a result, highly uniform, ultra-smooth modified surfaces are achieved in much shorter deposition times. This finding provides new insights into the effect of reaction kinetics and molecular geometry on the uniformity of modifications for surface engineering techniques.

  2. Optically based quantification of absolute cerebral metabolic rate of oxygen (CMRO2) with high spatial resolution in rodents

    Science.gov (United States)

    Yaseen, Mohammad A.; Srinivasan, Vivek J.; Sakadžić, Sava; Vinogradov, Sergei A.; Boas, David A.

    2010-02-01

    Measuring oxygen delivery in brain tissue is important for identifying the pathophysiological changes associated with brain injury and various diseases such as cancer, stroke, and Alzheimer's disease. We have developed a multi-modal imaging system for minimally invasive measurement of cerebral oxygenation and blood flow in small animals with high spatial resolution. The system allows for simultaneous measurement of blood flow using Fourier-domain optical coherence tomography, and oxygen partial pressure (pO2) using either confocal or multiphoton phosphorescence lifetime imaging with exogenous porphyrin-based dyes sensitive to dissolved oxygen. Here we present the changes in pO2 and blood flow in superficial cortical vessels of Sprague Dawley rats in response to conditions such as hypoxia, hyperoxia, and functional stimulation. pO2 measurements display considerable heterogeneity over distances that cannot be resolved with more widely used oxygen-monitoring techniques such as BOLD-fMRI. Large increases in blood flow are observed in response to functional stimulation and hypoxia. Our system allows for quantification of cerebral metabolic rate of oxygen (CMRO2) with high spatial resolution, providing a better understanding of metabolic dynamics during functional stimulation and under various neuropathologies. Ultimately, better insight into the underlying mechanisms of neuropathologies will facilitate the development of improved therapeutic strategies to minimize damage to brain tissue.

  3. Device and method for enhanced collection and assay of chemicals with high surface area ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Addleman, Raymond S.; Li, Xiaohong Shari; Chouyyok, Wilaiwan; Cinson, Anthony D.; Bays, John T.; Wallace, Krys

    2016-02-16

    A method and device for enhanced capture of target analytes is disclosed. This invention relates to collection of chemicals for separations and analysis. More specifically, this invention relates to a solid phase microextraction (SPME) device having better capability for chemical collection and analysis. This includes better physical stability, capacity for chemical collection, flexible surface chemistry and high affinity for target analyte.

  4. New Active Organic Substance in Oyster Shell Capable of Scavenging Oxygen Free Radicals with High Efficiency

    Institute of Scientific and Technical Information of China (English)

    MA Jian-hua

    2008-01-01

    A light purple organic active substance capable of scavenging hydroxyl radical·OH with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%.It was found for the first time that this active substance may scavenge ·OH with the efficiency far higher than that of vitamin C.This active substance may scavenge also superoxide radical(O2-·)although the scavenging efficiency is far lower than that of vitamin C.Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.

  5. Growth patterns, chemical composition and oxygen consumption in early juvenile Hyas araneus (Decapoda: Majidae) reared in the laboratory

    Science.gov (United States)

    Anger, K.; Harms, J.; Christiansen, M. E.; Süsens, U.; Wilmes, B.

    1992-03-01

    Early (instar I and II) juveniles of the spider crab Hyas araneus were reared under constant conditions (12 °C, 32‰S) in the laboratory, and their growth, biochemical composition, and respiration were studied. Every second day, dry weight (W), ash-free dry weight (AFW), and contents of ash, organic and inorganic carbon (C), nitrogen (N), hydrogen (H), protein, chitin, lipid, and carbohydrates were measured, as well as oxygen consumption. Changes in the absolute amounts of W. AFW, and C, N, and H during the moulting cycle are described with various regression equations as functions of age within a given instar. These patterns of growth differ in part from those that have been observed during previous studies in larval stages of the same and some other decapod species, possibly indicating different growth strategies in larvae and juveniles. There were clear periodic changes in ash (% of W) and inorganic C (as % of total C), with initially very low and then steeply increasing values in postmoult, a maximum in intermoult, and decreasing figures during the premoult phase of each moulting cycle. Similar patterns were observed in the chitin fraction, reaching a maximum of 16% of W (31% of AFW). Ash, inorganic C, and chitin represent the major components of the exoskeleton and hence, changes in their amounts are associated with the formation and loss of cuticle material. Consequently, a high percentage of mineral matter was lost with the exuvia (76% of the late premoult [LPM] ash content, 74% of inorganic C), but relatively small fractions of LPM organic matter (15% of AFW, 11% of organic C, 5 6% of N and H). These cyclic changes in the cuticle caused an inverse pattern of variation in the percentage values (% of W) of AFW, organic C, N, H, and biochemical constituents other than chitin. When these measures of living biomass were related to, exclusively, the organic body fraction (AFM), much less variation was found during individual moulting cycles, with values of

  6. Oxygen ion energization by waves in the high altitude cusp and mantle

    Directory of Open Access Journals (Sweden)

    M. Waara

    2012-09-01

    Full Text Available We present a comparative study of low frequency electric field spectral densities and temperatures observed by the Cluster spacecraft in the high altitude cusp/mantle region. We compare the relation between the O+ temperature and wave intensity at the oxygen gyrofrequency at each measurement point and find a clear correlation. The trend of the correlation agrees with the predictions by both an asymptotic mean-particle theory and a test-particle approach. The perpendicular to parallel temperature ratio is also consistent with the predictions of the asymptotic mean-particle theory. At times the perpendicular temperature is significantly higher than predicted by the models. A simple study of the evolution of the particle distributions (conics at these altitudes indicates that enhanced perpendicular temperatures would be observed over many RE after heating ceases. Therefore, sporadic intense heating is the likely explanation for cases with high temperature and comparably low wave activity. We observe waves of sufficient amplitude to explain the highest observed temperatures, while the theory in general overestimates the temperature associated with the highest observed wave activity, indicating that such high wave activity is very sporadic.

  7. Engineering of Corynebacterium glutamicum for high-yield L-valine production under oxygen deprivation conditions.

    Science.gov (United States)

    Hasegawa, Satoshi; Suda, Masako; Uematsu, Kimio; Natsuma, Yumi; Hiraga, Kazumi; Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki

    2013-02-01

    We previously demonstrated efficient L-valine production by metabolically engineered Corynebacterium glutamicum under oxygen deprivation. To achieve the high productivity, a NADH/NADPH cofactor imbalance during the synthesis of l-valine was overcome by engineering NAD-preferring mutant acetohydroxy acid isomeroreductase (AHAIR) and using NAD-specific leucine dehydrogenase from Lysinibacillus sphaericus. Lactate as a by-product was largely eliminated by disrupting the lactate dehydrogenase gene ldhA. Nonetheless, a few other by-products, particularly succinate, were still produced and acted to suppress the L-valine yield. Eliminating these by-products therefore was deemed key to improving theL-valine yield. By additionally disrupting the phosphoenolpyruvate carboxylase gene ppc, succinate production was effectively suppressed, but both glucose consumption and L-valine production dropped considerably due to the severely elevated intracellular NADH/NAD(+) ratio. In contrast, this perturbed intracellular redox state was more than compensated for by deletion of three genes associated with NADH-producing acetate synthesis and overexpression of five glycolytic genes, including gapA, encoding NADH-inhibited glyceraldehyde-3-phosphate dehydrogenase. Inserting feedback-resistant mutant acetohydroxy acid synthase and NAD-preferring mutant AHAIR in the chromosome resulted in higher L-valine yield and productivity. Deleting the alanine transaminase gene avtA suppressed alanine production. The resultant strain produced 1,280 mM L-valine at a yield of 88% mol mol of glucose(-1) after 24 h under oxygen deprivation, a vastly improved yield over our previous best.

  8. Freestanding eggshell membrane-based electrodes for high-performance supercapacitors and oxygen evolution reaction

    Science.gov (United States)

    Geng, Jing; Wu, Hao; Al-Enizi, Abdullah M.; Elzatahry, Ahmed A.; Zheng, Gengfeng

    2015-08-01

    A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific capacitances at current densities from 1 to 20 A g-1, with excellent capacitance retention (>90%) at 10 A g-1 for over 10 000 cycles. When employed as an OER catalyst, this eggshell membrane-based electrode exhibits an OER onset potential of 1.53 V vs. the reversible hydrogen electrode (RHE), and a stable catalytic current density of 20 mA cm-2 at 1.65 V vs. the RHE.A type of freestanding, light-weight eggshell membrane-based electrode is demonstrated for supercapacitors and for oxygen evolution reaction (OER) catalysis. As a widely available daily waste, eggshell membranes have unique porous three-dimensional grid-like fibrous structures with relatively high surface area and abundant macropores, allowing for effective conjugation of carbon nanotubes and growth of NiCo2O4 nanowire arrays, an effective supercapacitor material and OER catalyst. The three-dimensional fibrous eggshell membrane frameworks with carbon nanotubes offer efficient pathways for charge transport, and the macropores between adjacent fibers are fully accessible for electrolytes and bubble evolution. As a supercapacitor, the eggshell membrane/carbon nanotube/NiCo2O4 electrode shows high specific

  9. Effects of extra oxygen on the structure and superconductivity of La2-xCaxCuO4+y prepared by chemical oxidation

    DEFF Research Database (Denmark)

    Rial, C.; Moran, E.; Alario Franco, M.A.

    1998-01-01

    improve considerably upon oxidation. The oxidized Ca-doped materials with x less than or equal to 0.08 show an almost constant T-c of similar to 38 K, close to that corresponding to the optimum hole-doping in La2-xMxCuO4; however, the oxidized samples with higher Ca contents present slightly lower T(c)s......The insertion of an excess of oxygen within the structure of La2-xCaxCuO4 (x less than or equal to 0.12) by means of room temperature chemical oxidation modifies the physical properties and the crystal structure of these cuprates. The superconducting features of the starting La2-xCaxCuO4 samples....... This decrease of T-c is connected with the ability of these compounds to incorporate extra oxygen, which decreases as the Ca-doping increases and is controlled by a structural limit. The behavior of the La2-xCaxCuO4 materials under the oxidation process and the changes induced by the interstitial oxygen...

  10. Oral Administration of the Japanese Traditional Medicine Keishibukuryogan-ka-yokuinin Decreases Reactive Oxygen Metabolites in Rat Plasma: Identification of Chemical Constituents Contributing to Antioxidant Activity

    Directory of Open Access Journals (Sweden)

    Yosuke Matsubara

    2017-02-01

    Full Text Available Insufficient detoxification and/or overproduction of reactive oxygen species (ROS induce cellular and tissue damage, and generated reactive oxygen metabolites become exacerbating factors of dermatitis. Keishibukuryogan-ka-yokuinin (KBGY is a traditional Japanese medicine prescribed to treat dermatitis such as acne vulgaris. Our aim was to verify the antioxidant properties of KBGY, and identify its active constituents by blood pharmacokinetic techniques. Chemical constituents were quantified in extracts of KBGY, crude components, and the plasma of rats treated with a single oral administration of KBGY. Twenty-three KBGY compounds were detected in plasma, including gallic acid, prunasin, paeoniflorin, and azelaic acid, which have been reported to be effective for inflammation. KBGY decreased level of the diacron-reactive oxygen metabolites (d-ROMs in plasma. ROS-scavenging and lipid hydroperoxide (LPO generation assays revealed that gallic acid, 3-O-methylgallic acid, (+-catechin, and lariciresinol possess strong antioxidant activities. Gallic acid was active at a similar concentration to the maximum plasma concentration, therefore, our findings indicate that gallic acid is an important active constituent contributing to the antioxidant effects of KBGY. KBGY and its active constituents may improve redox imbalances induced by oxidative stress as an optional treatment for skin diseases.

  11. Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

    Science.gov (United States)

    Singh, Jagdish P.; Yueh, Fang-Yu; Kalluru, Rajamohan R.; Harrison, Louie

    2012-01-01

    An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LOX

  12. Antioxidants keep the potentially probiotic but highly oxygen-sensitive human gut bacterium Faecalibacterium prausnitzii alive at ambient air

    NARCIS (Netherlands)

    Khan, M. Tanweer; van Dijl, Jan Maarten; Harmsen, Hermie J M

    2014-01-01

    The beneficial human gut microbe Faecalibacterium prausnitzii is a 'probiotic of the future' since it produces high amounts of butyrate and anti-inflammatory compounds. However, this bacterium is highly oxygen-senstive, making it notoriously difficult to cultivate and preserve. This has so far precl

  13. Improving the simultaneous removal of chemical oxygen demand and terephthalic acid in a cross-flow aerobic sludge reactor by using response surface methodology.

    Science.gov (United States)

    Hu, Dong-Xue; Tian, Yu; Chen, Zhao-Bo; Ge, Hui; Cui, Yu-Bo; Ran, Chun-Qiu

    2015-01-01

    Central composite design and response surface methodology (RSM) were implemented to optimize the operational parameters for a cross-flow aerobic sludge reactor (CFASR) in remedying mixed printing and dyeing wastewater (MPDW). The individual and interactive effects of three variables, hydraulic retention time (HRT), pH and sludge loading rate (SLR), on chemical oxygen demand (COD) and terephthalic acid (TA) removal rates were evaluated. For HRT of 15.3-19.8 hours, pH of 7.2-8.1 and SLR of 0.4-0.6 kg chemical oxygen demand (COD) per kg mixed liquor suspended solids per day, COD and TA removal rates of the CFASR exceeded 85% and 90%, respectively. The check experiment revealed that the effluent from the optimized CFASR was stable below the limitation of 100 mg COD/L and the TA concentration decreased by 6.0% compared to the usual CFASR. The results verified that the RSM was useful for optimizing the operation parameters of the CFASR in remedying MPDW.

  14. Constraints on the source of ultra-high energy cosmic rays using anisotropy vs chemical composition

    CERN Document Server

    Liu, Ruo-Yu; Lemoine, Martin; Wang, Xiang-Yu; Waxman, Eli

    2013-01-01

    The joint analysis of anisotropy signals and chemical composition of ultra-high energy cosmic rays offers strong potential for shedding light on the sources of these particles. Following up on an earlier idea, this paper studies the anisotropies produced by protons of energy >E/Z, assuming that anisotropies at energy >E have been produced by nuclei of charge Z, which share the same magnetic rigidity. We calculate the number of secondary protons produced through photodisintegration of the primary heavy nuclei. Making the extreme assumption that the source does not inject any proton, we find that the source(s) responsible for anisotropies such as reported by the Pierre Auger Observatory should lie closer than ~20-30, 80-100 and 180-200 Mpc if the anisotropy signal is mainly composed of oxygen, silicon and iron nuclei respectively. A violation of this constraint would otherwise result in the secondary protons forming a more significant anisotropy signal at lower energies. Even if the source were located closer t...

  15. Highly-active oxygen evolution electrocatalyzed by a Fe-doped NiSe nanoflake array electrode.

    Science.gov (United States)

    Tang, Chun; Asiri, Abdullah M; Sun, Xuping

    2016-03-25

    Alkaline water electrolysis offers a simple method for mass production of hydrogen but suffers from the sluggish kinetics of the anodic oxygen evolution reaction (OER), calling for the development of low-cost and durable oxygen evolution electrocatalysts with high activity. In this communication, we report a highly-active robust oxygen evolution electrode, developed by in situ hydrothermal growth of an Fe-doped NiSe nanoflake array directly on a macroporous FeNi foam (Fe-NiSe/FeNi foam). This electrode catalyzes the OER with an onset overpotential as low as 200 mV and needs overpotentials of 245 and 264 mV to achieve 50 and 100 mA cm(-2), respectively, in 1.0 M KOH. Remarkably, it is also highly robust to drive 500 and 1000 mA cm(-2) at overpotentials of 246 and 263 mV, respectively, in 30 wt% KOH.

  16. Influence of oxygen partial pressure on crystallization behaviour and high-temperature stability of stone wool fibres

    Energy Technology Data Exchange (ETDEWEB)

    Kaasgaard, M.; Jacobsen, P.A.L.; Yue Yuanzheng [Aalborg Univ. (Denmark). Section of Chemistry

    2005-04-01

    The influence of oxygen partial pressure on the redox state of the iron in stone wool is studied using thermogravimetry (TG). The thermal response of the stone wool is measured using differential scanning calorimetry (DSC). The high-temperature stability of stone wool depending on the oxygen partial pressure is observed using scanning electron microscopy (SEM). It is confirmed that the oxidation of Fe{sup 2+} to Fe{sup 3+} is responsible for the high-temperature stability of stone wool. Even a minor increase in oxygen partial pressure can considerably alter the crystallization behaviour and enhance the high-temperature stability of the stone wool. The origin for that is discussed. (orig.)

  17. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hans, M., E-mail: hans@mch.rwth-aachen.de; Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Primetzhofer, D. [Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, S-75120 Uppsala (Sweden); Kurapov, D.; Arndt, M.; Rudigier, H. [Oerlikon Balzers Coating AG, Iramali 18, LI-9496 Balzers, Principality of Liechtenstein (Liechtenstein)

    2014-09-07

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

  18. Secular distribution of highly metalliferous black shales corresponds with peaks in past atmosphere oxygenation

    Science.gov (United States)

    Johnson, Sean C.; Large, Ross R.; Coveney, Raymond M.; Kelley, Karen D.; Slack, John F.; Steadman, Jeffrey A.; Gregory, Daniel D.; Sack, Patrick J.; Meffre, Sebastien

    2017-08-01

    Highly metalliferous black shales (HMBS) are enriched in organic carbon and a suite of metals, including Ni, Se, Mo, Ag, Au, Zn, Cu, Pb, V, As, Sb, Se, P, Cr, and U ± PGE, compared to common black shales, and are distributed at particular times through Earth history. They constitute an important future source of metals. HMBS are relatively thin units within thicker packages of regionally extensive, continental margin or intra-continental marine shales that are rich in organic matter and bio-essential trace elements. Accumulation and preservation of black shales, and the metals contained within them, usually require low-oxygen or euxinic bottom waters. However, whole-rock redox proxies, particularly Mo, suggest that HMBS may have formed during periods of elevated atmosphere pO2. This interpretation is supported by high levels of nutrient trace elements within these rocks and secular patterns of Se and Se/Co ratios in sedimentary pyrite through Earth history, with peaks occurring in the middle Paleoproterozoic, Early Cambrian to Early Ordovician, Middle Devonian, Middle to late Carboniferous, Middle Permian, and Middle to Late Cretaceous, all corresponding with time periods of HMBS deposition. This counter-intuitive relationship of strongly anoxic to euxinic, localized seafloor conditions forming under an atmosphere of peak oxygen concentrations is proposed as key to the genesis of HMBS. The secular peaks and shoulders of enriched Se in sedimentary pyrite through time correlate with periods of tectonic plate collision, which resulted in high nutrient supply to the oceans and consequently maximum productivity accompanying severe drawdown into seafloor muds of C, S, P, and nutrient trace metals. The focused burial of C and S over extensive areas of the seafloor, during these anoxic to euxinic periods, likely resulted in an O2 increase in the atmosphere, causing short-lived peaks in pO2 that coincide with the deposition of HMBS. As metals become scarce, particularly Mo

  19. Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes

    DEFF Research Database (Denmark)

    Qingfeng, Li; Bergqvist, R. S.; Hjuler, H. A.

    1999-01-01

    Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and PBI polymer electrolytes in a temperature range from 80 to 190°C. Compared with pure H3PO4, using the H3PO4 doped Nafion and PBI polymer electrolytes can significantly improve the oxygen...

  20. High Activity of Hexagonal Ag/Pt Nanoshell Catalyst for Oxygen Electroreduction

    Directory of Open Access Journals (Sweden)

    Lee Chien-Liang

    2008-01-01

    Full Text Available Abstract Hexagonal Ag/Pt nanoshells were prepared by using a hexagonal Ag nanoplate as the displacement template and by introducing Pt ions. The prepared Ag/Pt nanoshells played the role of an electrocatalyst in an oxygen reduction process. Compared to spherical Pt and Ag/Pt nanoparticles, the hexagonal Ag/Pt nanoshells showed higher activity for oxygen electroreduction.