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Sample records for moltox oxygen process

  1. Air separation by the Moltox process

    SciTech Connect

    Erickson, D. C.

    1981-04-01

    The report describes results of a development program on a new and energy saving process for air separation. The Moltox process involves reversibly reacting oxygen in air with a recirculating salt solution, such that oxygen is extracted without depressurizing the remaining nitrogen. Energy savings of approximately 50% are indicated for this process compared to conventional cryogenic air separation. The development program consisted of design, construction, and operation of a 6 liter/minute pilot plant; optimization of the process flowsheet through computer modelling; investigation of engineering aspects of the process including corrosion, safety, and NO/sub x/ generation; and an economic comparison to conventional cryogenic practice. All objectives were satisfactorily achieved except for continuous operation of the pilot plant, and the modifications necessary to achieve that have been identified. Economically the Moltox process shows a substantial advantage over large scale cryogenic plants which are powered by fuel vice electricity.

  2. Air separation by the Moltox process. Interim final report

    SciTech Connect

    Erickson, D.C.

    1981-04-01

    Results are described of a development program on a new and energy-saving process for air separation. The Moltox process involves reversibly reacting oxygen in air with a recirculating salt solution, such that oxygen is extracted without depressurizing the remaining nitrogen. Energy savings of approximately 50% are indicated for this process compared to conventional cryogenic air separation. The development program consisted of design, construction, and operation of a 6 liter/minute pilot plant; optimization of the process flowsheet through computer modelling; investigation of engineering aspects of the process including corrosion, safety, and NO/sub x/ generation; and an economic comparison to conventional cryogenic practice. All objectives were satisfactorily achieved except for continuous operation of the pilot plant, and the modifications necessary to achieve that have been identified. Economically the Moltox process shows a substantial advantage over large scale cryogenic plants which are powered by fuel vice electricity.

  3. Corrosion study in the chemical air separation (MOLTOX trademark ) process

    SciTech Connect

    Kang, Doohee; Wong, Kai P.; Archer, R.A.; Cassano, A.A.

    1988-12-01

    This report presents the results of studies aimed at solving the corrosion problems encountered during operation of the MOLTOX{trademark} pilot plant. These studies concentrated on the screening of commercial and developmental alloys under conditions simulating operation conditions in this high temperature molten salt process. Process economic studies were preformed in parallel with the laboratory testing to ensure that an economically feasible solution would be achieved. In addition to the above DOE co-funded studies, Air Products and Chemicals pursued proprietary studies aimed at developing a less corrosive salt mixture which would potentially allow the use of chemurgically available alloys such as stainless steels throughout the system. These studies will not be reported here; however, the results of corrosion tests in the new less corrosive salt mixtures are reported. Because our own studies on salt chemistry impacts heavily on the overall process and thereby has an influence on the experimental work conducted under this contract, some of the studies discussed here were impacted by our own proprietary data. Therefore, the reasons behind some of the experiments presented herein will not be explained because that information is proprietary to Air Products. 14 refs., 42 figs., 21 tabs.

  4. Sulfur oxygen processes on Io

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.; Smythe, W. D.

    1985-04-01

    The presence of allotropic sulfur as a possible major constituent of Io's surface and the properties of sulfur in combination with various sulfur-oxygen compounds believed to be present on Io's surface and in its atmosphere are studied by a series of laboratory experiments.

  5. Sulfur Oxygen Processes on Io

    NASA Technical Reports Server (NTRS)

    Nelson, R. M.; Smythe, W. D.

    1985-01-01

    The presence of allotropic sulfur as a possible major constituent of Io's surface and the properties of sulfur in combination with various sulfur-oxygen compounds believed to be present on Io's surface and in its atmosphere are studied by a series of laboratory experiments.

  6. DME-to-oxygenates process studies

    SciTech Connect

    Tartamella, T.L.; Sardesai, A.; Lee, S.; Kulik, C.J.

    1994-12-31

    The feasibility of the production of hydrocarbons from dimethyl ether (DNM) has been illustrated in a fixed bed micro-reactor as well as a bench scale fluidized bed reactor by the University of Akron/EPRI DME-to-Hydrocarbon (DTG) Process. The DTG process has distinct advantages over its methanol based counterpart. Specifically, the DTG process excels in the area of higher productivity, higher per-pass conversion, and lower heat duties than the MTG process. Also of special importance is the production of oxygenates -- including MTBE, ETBE, and TAME. DME may be reacted with isobutylene to produce a mixture of MTBE and ETBE. The properties of ETBE excel over MTBE in the areas of lower RVP and higher RON. According to industrial reports, MTBE is the fastest growing chemical (1992 US capacity 135,350 BPD, with expected growth of 34%/year to 1997). Also, recent renewed interest as an octane-enhancer and as a source of oxygen has spurred a growing interest in nonrefinery synthesis routes to ETBE. TAME, with its lower RVP and higher RON has proven useful as a gasoline blending agent and octane enhancer and may also be produced directly from DME. DME, therefore, serves as a valuable feedstock in the conversion of may oxygenates with wide-scale industrial importance. It should be also noted that the interest in the utilization of DME as process feedstock is based on the favorable process economics of EPRI/UA`s liquid phase DME process.

  7. Novel Membranes and Processes for Oxygen Enrichment

    SciTech Connect

    Lin, Haiqing

    2011-11-15

    The overall goal of this project is to develop a membrane process that produces air containing 25-35% oxygen, at a cost of $25-40/ton of equivalent pure oxygen (EPO2). Oxygen-enriched air at such a low cost will allow existing air-fueled furnaces to be converted economically to oxygen-enriched furnaces, which in turn will improve the economic and energy efficiency of combustion processes significantly, and reduce the cost of CO{sub 2} capture and sequestration from flue gases throughout the U.S. manufacturing industries. During the 12-month Concept Definition project: We identified a series of perfluoropolymers (PFPs) with promising oxygen/nitrogen separation properties, which were successfully made into thin film composite membranes. The membranes showed oxygen permeance as high as 1,200 gpu and oxygen/nitrogen selectivity of 3.0, and the permeance and selectivity were stable over the time period tested (60 days). We successfully scaled up the production of high-flux PFP-based membranes, using MTR's commercial coaters. Two bench-scale spiral-wound modules with countercurrent designs were made and parametric tests were performed to understand the effect of feed flow rate and pressure, permeate pressure and sweep flow rate on the membrane module separation properties. At various operating conditions that modeled potential industrial operating conditions, the module separation properties were similar to the pure-gas separation properties in the membrane stamps. We also identified and synthesized new polymers [including polymers of intrinsic microporosity (PIMs) and polyimides] with higher oxygen/nitrogen selectivity (3.5-5.0) than the PFPs, and made these polymers into thin film composite membranes. However, these membranes were susceptible to severe aging; pure-gas permeance decreased nearly six-fold within two weeks, making them impractical for industrial applications of oxygen enrichment. We tested the effect of oxygen-enriched air on NO{sub x} emissions using a

  8. A modified sulfate process to lunar oxygen

    NASA Technical Reports Server (NTRS)

    Sullivan, Thomas A.

    1992-01-01

    A modified sulfate process which produces oxygen from iron oxide-bearing minerals in lunar soil is under development. Reaction rates of ilmenite in varying strength sulfuric acid have been determined. Quantitative conversion of ilmenite to ferrous sulfate was observed over a range of temperatures and concentrations. Data has also been developed on the calcination of by-product sulfates. System engineering for overall operability and simplicity has begun, suggesting that a process separating the digestion and sulfate dissolution steps may offer an optimum process.

  9. A modified sulfate process to lunar oxygen

    NASA Technical Reports Server (NTRS)

    Sullivan, Thomas A.

    1992-01-01

    A modified sulfate process which produces oxygen from iron oxide-bearing minerals in lunar soil is under development. Reaction rates of ilmenite in varying strength sulfuric acid have been determined. Quantitative conversion of ilmenite to ferrous sulfate was observed over a range of temperatures and concentrations. Data has also been developed on the calcination of by-product sulfates. System engineering for overall operability and simplicity has begun, suggesting that a process separating the digestion and sulfate dissolution steps may offer an optimum process.

  10. The oxycoal process with cryogenic oxygen supply

    NASA Astrophysics Data System (ADS)

    Kather, Alfons; Scheffknecht, Günter

    2009-09-01

    Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly

  11. The oxycoal process with cryogenic oxygen supply.

    PubMed

    Kather, Alfons; Scheffknecht, Günter

    2009-09-01

    Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly

  12. Absorption process for producing oxygen and nitrogen and solution therefor

    DOEpatents

    Roman, Ian C.; Baker, Richard W.

    1990-09-25

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

  13. Absorption process for producing oxygen and nitrogen and solution therefor

    DOEpatents

    Roman, Ian C.

    1984-01-01

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

  14. Absorption process for producing oxygen and nitrogen and solution therefor

    DOEpatents

    Roman, I.C.; Baker, R.W.

    1990-09-25

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible. 1 figure

  15. Nanoparticulate-catalyzed oxygen transfer processes

    DOEpatents

    Hunt, Andrew T.; Breitkopf, Richard C.

    2009-12-01

    Nanoparticulates of oxygen transfer materials that are oxides of rare earth metals, combinations of rare earth metals, and combinations of transition metals and rare earth metals are used as catalysts in a variety of processes. Unexpectedly large thermal efficiencies are achieved relative to micron sized particulates. Processes that use these catalysts are exemplified in a multistage reactor. The exemplified reactor cracks C6 to C20 hydrocarbons, desulfurizes the hydrocarbon stream and reforms the hydrocarbons in the stream to produce hydrogen. In a first reactor stage the steam and hydrocarbon are passed through particulate mixed rare earth metal oxide to crack larger hydrocarbon molecules. In a second stage, the steam and hydrocarbon are passed through particulate material that desulfurizes the hydrocarbon. In a third stage, the hydrocarbon and steam are passed through a heated, mixed transition metal/rare earth metal oxide to reform the lower hydrocarbons and thereby produce hydrogen. Stages can be alone or combined. Parallel reactors can provide continuous reactant flow. Each of the processes can be carried out individually.

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

    PubMed

    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.

  17. New oxygen plasma process rivals laser cutting methods

    SciTech Connect

    Fernicola, R.C. )

    1994-06-01

    For many years, oxygen plasma cutting has been looked upon as a desirable process for cutting steel but not practical in production because of very short consumable parts life. Recently, a number of technical advances in the oxygen plasma cutting process provides parts life several times that of older systems and cut quality approaching that of laser systems. This paper discusses these advances.

  18. Efficiency evaluation of oxygen enrichment in energy conversion processes

    SciTech Connect

    Bomelburg, H.J.

    1983-12-01

    The extent to which energy conversion efficiencies can be increased by using oxygen or oxygen-enriched air for combustion was studied. Combustion of most fuels with oxygen instead of air was found to have five advantages: increases combustion temperature and efficiency, improves heat transfer at high temperatures, reduces nitrous oxide emissions, permits a high ration of exhaust gas recirculation and allows combustion of certain materials not combustible in air. The same advantages, although to a lesser degree, are apparent with oxygen-enriched air. The cost-effectiveness of the process must necessarily be improved by about 10% when using oxygen instead of air before such use could become justifiable on purely economic terms. Although such a modest increase appears to be attainable in real situations, this study ascertained that it is not possible to generally assess the economic gains. Rather, each case requires its own evaluation. For certain processes industry has already proven that the use of oxygen leads to more efficient plant operation. Several ideas for essentially new applications are described. Specifically, when oxygen is used with exhaust gas recirculation in external or internal combustion engines. It appears also that the advantages of pulse combustion can be amplified further if oxygen is used. When burning wet fuels with oxygen, direct steam generation becomes possible. Oxygen combustion could also improve processes for in situ gasification of coals, oil shales, peats, and other wet fuels. Enhanced oil recovery by fire flooding methods might also become more effective if oxygen is used. The cold energy contained in liquid oxygen can be substantially recovered in the low end of certain thermodynamic cycles. Further efforts to develop certain schemes for using oxygen for combustion appear to be justified from both the technical and economic viewpoints.

  19. Oxygen production on the Lunar materials processing frontier

    NASA Technical Reports Server (NTRS)

    Altenberg, Barbara H.

    1992-01-01

    During the pre-conceptual design phase of an initial lunar oxygen processing facility, it is essential to identify and compare the available processes and evaluate them in order to ensure the success of such an endeavor. The focus of this paper is to provide an overview of materials processing to produce lunar oxygen as one part of a given scenario of a developing lunar occupation. More than twenty-five techniques to produce oxygen from lunar materials have been identified. While it is important to continue research on any feasible method, not all methods can be implemented at the initial lunar facility. Hence, it is necessary during the pre-conceptual design phase to evaluate all methods and determine the leading processes for initial focus. Researchers have developed techniques for evaluating the numerous proposed methods in order to suggest which processes would be best to go to the Moon first. As one section in this paper, the recent evaluation procedures that have been presented in the literature are compared and contrasted. In general, the production methods for lunar oxygen fall into four categories: thermochemical, reactive solvent, pyrolytic, and electrochemical. Examples from two of the four categories are described, operating characteristics are contrasted, and terrestrial analogs are presented when possible. In addition to producing oxygen for use as a propellant and for life support, valuable co-products can be derived from some of the processes. This information is also highlighted in the description of a given process.

  20. Methane Post-Processing for Oxygen Loop Closure

    NASA Technical Reports Server (NTRS)

    Greenwood, Zachary W.; Abney, Morgan B.; Miller, Lee

    2016-01-01

    State-of-the-art United States Atmospheric Revitalization carbon dioxide (CO2) reduction is based on the Sabatier reaction process, which recovers approximately 50% of the oxygen (O2) from crew metabolic CO2. Oxygen recovery from carbon dioxide is constrained by the limited availability of reactant hydrogen. Post-processing of methane to recover hydrogen with the Umpqua Research Company Plasma Pyrolysis Assembly (PPA) has the potential to further close the Atmospheric Revitalization oxygen loop. The PPA decomposes methane into hydrogen and hydrocarbons, predominantly acetylene, and a small amount of solid carbon. The hydrogen must then be purified before it can be recycled for additional oxygen recovery. Long duration testing and evaluation of a four crew-member sized PPA and a discussion of hydrogen recycling system architectures are presented.

  1. Sulfur-oxygen processes on Io

    NASA Technical Reports Server (NTRS)

    Nelson, Robert M.; Smythe, William D.

    1987-01-01

    Laboratory studies of irradiated sulfur dioxide frost have found that sulfur trioxide should be formed as a consequence of the irradiation process. The spectral reflectance of solid sulfur trioxide was measured in the laboratory and it was found that the compound has strong absorption features at 3.37 and 3.70 microns. These features are not present in the spectral geometric albedo of Io. This is interpreted as an indication that sulfur trioxide may exist in such limited abundance that it is undetectable in disk averaged spectrophotometry. It is suggested that the Near-Infrared Mapping Spectrometer on the Galileo spacecraft should be able to identify condensed sulfur trioxide on Io particularly in regions bordering the sulfur dioxide deposits. The presence of elemental sulfur on Io's surface has been questioned on several grounds, most notably the suggested production process (quenched molten sulfur extrusions) and the effect of radiation (particularly X-rays) on some of the allotropes. Mixtures of sulfur allotropes were produced in the laboratory by quenching molten sulfur and it was found that the spectra indicate the presence of certain red-colored allotropes which are preserved upon quenching. The color of the sulfur glass produced is redder when the temperature of the original melt is higher. This is consistent with the suggestion that Io's spectral geometric albedo can be partly explained by the presence of quenched sulfur glasses.

  2. Sulfur-oxygen processes on Io

    NASA Astrophysics Data System (ADS)

    Nelson, Robert M.; Smythe, William D.

    1987-05-01

    Laboratory studies of irradiated sulfur dioxide frost have found that sulfur trioxide should be formed as a consequence of the irradiation process. The spectral reflectance of solid sulfur trioxide was measured in the laboratory and it was found that the compound has strong absorption features at 3.37 and 3.70 microns. These features are not present in the spectral geometric albedo of Io. This is interpreted as an indication that sulfur trioxide may exist in such limited abundance that it is undetectable in disk averaged spectrophotometry. It is suggested that the Near-Infrared Mapping Spectrometer on the Galileo spacecraft should be able to identify condensed sulfur trioxide on Io particularly in regions bordering the sulfur dioxide deposits. The presence of elemental sulfur on Io's surface has been questioned on several grounds, most notably the suggested production process (quenched molten sulfur extrusions) and the effect of radiation (particularly X-rays) on some of the allotropes. Mixtures of sulfur allotropes were produced in the laboratory by quenching molten sulfur and it was found that the spectra indicate the presence of certain red-colored allotropes which are preserved upon quenching. The color of the sulfur glass produced is redder when the temperature of the original melt is higher. This is consistent with the suggestion that Io's spectral geometric albedo can be partly explained by the presence of quenched sulfur glasses.

  3. Automation and control of off-planet oxygen production processes

    NASA Technical Reports Server (NTRS)

    Marner, W. J.; Suitor, J. W.; Schooley, L. S.; Cellier, F. E.

    1990-01-01

    This paper addresses several aspects of the automation and control of off-planet production processes. First, a general approach to process automation and control is discussed from the viewpoint of translating human process control procedures into automated procedures. Second, the control issues for the automation and control of off-planet oxygen processes are discussed. Sensors, instruments, and components are defined and discussed in the context of off-planet applications, and the need for 'smart' components is clearly established.

  4. Automation and control of off-planet oxygen production processes

    NASA Technical Reports Server (NTRS)

    Marner, W. J.; Suitor, J. W.; Schooley, L. S.; Cellier, F. E.

    1990-01-01

    This paper addresses several aspects of the automation and control of off-planet production processes. First, a general approach to process automation and control is discussed from the viewpoint of translating human process control procedures into automated procedures. Second, the control issues for the automation and control of off-planet oxygen processes are discussed. Sensors, instruments, and components are defined and discussed in the context of off-planet applications, and the need for 'smart' components is clearly established.

  5. Processing of metal and oxygen from lunar deposits

    NASA Technical Reports Server (NTRS)

    Acton, Constance F.

    1992-01-01

    On the moon, some whole rocks may be ores for abundant elements, such as oxygen, but beneficiation will be important if metallic elements are sought from raw lunar dirt. In the extraction process, a beneficiated metallic ore, such as an oxide, sulfide, carbonate, or silicate mineral, is converted to reduced metal. A variety of plausible processing technologies, which includes recovery of meteoritic iron, and processing of lunar ilmenite, are described in this report.

  6. Oxygen production processes on the Moon: An overview

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.; Carrier, W. David, III

    1991-01-01

    The production of oxygen on the Moon utilizing indigenous material is paramount to a successful lunar colonization. Several processes were put forth to accomplish this. The lunar liquid oxygen (LLOX) generation schemes which have received the most study to date are those involving: (1) the reduction of ilmenite (FeTiO3) by H2, C, CO, CH4, CO-Cl2 plasma; (2) magma electrolysis, both unadulterated and fluoride-fluxed, and (3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reduction of ilmenite and magma electrolysis processes have received the most study to date. At this stage of development, they both appear feasible schemes with various pros and cons. However, all processes should be addressed at least at the onset of the considerations. It is ultimatley the energy requirements of the entire process, including the acquisition of feedstock, which will determine the mode of oxygen productions. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and several of the most studied and feasible processes for winning oxygen from lunar materials are reviewed.

  7. Oxygen production processes on the Moon: An overview

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.; Carrier, W. David, III

    1991-01-01

    The production of oxygen on the Moon utilizing indigenous material is paramount to a successful lunar colonization. Several processes were put forth to accomplish this. The lunar liquid oxygen (LLOX) generation schemes which have received the most study to date are those involving: (1) the reduction of ilmenite (FeTiO3) by H2, C, CO, CH4, CO-Cl2 plasma; (2) magma electrolysis, both unadulterated and fluoride-fluxed, and (3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reduction of ilmenite and magma electrolysis processes have received the most study to date. At this stage of development, they both appear feasible schemes with various pros and cons. However, all processes should be addressed at least at the onset of the considerations. It is ultimatley the energy requirements of the entire process, including the acquisition of feedstock, which will determine the mode of oxygen productions. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and several of the most studied and feasible processes for winning oxygen from lunar materials are reviewed.

  8. Process for conversion of lignin to reformulated, partially oxygenated gasoline

    DOEpatents

    Shabtai, Joseph S.; Zmierczak, Wlodzimierz W.; Chornet, Esteban

    2001-01-09

    A high-yield process for converting lignin into reformulated, partially oxygenated gasoline compositions of high quality is provided. The process is a two-stage catalytic reaction process that produces a reformulated, partially oxygenated gasoline product with a controlled amount of aromatics. In the first stage of the process, a lignin feed material is subjected to a base-catalyzed depolymerization reaction, followed by a selective hydrocracking reaction which utilizes a superacid catalyst to produce a high oxygen-content depolymerized lignin product mainly composed of alkylated phenols, alkylated alkoxyphenols, and alkylbenzenes. In the second stage of the process, the depolymerized lignin product is subjected to an exhaustive etherification reaction, optionally followed by a partial ring hydrogenation reaction, to produce a reformulated, partially oxygenated/etherified gasoline product, which includes a mixture of substituted phenyl/methyl ethers, cycloalkyl methyl ethers, C.sub.7 -C.sub.10 alkylbenzenes, C.sub.6 -C.sub.10 branched and multibranched paraffins, and alkylated and polyalkylated cycloalkanes.

  9. Processing lunar soils for oxygen and other materials

    NASA Technical Reports Server (NTRS)

    Knudsen, Christian W.; Gibson, Michael A.

    1992-01-01

    Two types of lunar materials are excellent candidates for lunar oxygen production: ilmenite and silicates such as anorthite. Both are lunar surface minable, occurring in soils, breccias, and basalts. Because silicates are considerably more abundant than ilmenite, they may be preferred as source materials. Depending on the processing method chosen for oxygen production and the feedstock material, various useful metals and bulk materials can be produced as byproducts. Available processing techniques include hydrogen reduction of ilmenite and electrochemical and chemical reductions of silicates. Processes in these categories are generally in preliminary development stages and need significant research and development support to carry them to practical deployment, particularly as a lunar-based operation. The goal of beginning lunar processing operations by 2010 requires that planning and research and development emphasize the simplest processing schemes. However, more complex schemes that now appear to present difficult technical challenges may offer more valuable metal byproducts later. While they require more time and effort to perfect, the more complex or difficult schemes may provide important processing and product improvements with which to extend and elaborate the initial lunar processing facilities. A balanced R&D program should take this into account. The following topics are discussed: (1) ilmenite--semi-continuous process; (2) ilmenite--continuous fluid-bed reduction; (3) utilization of spent ilmenite to produce bulk materials; (4) silicates--electrochemical reduction; and (5) silicates--chemical reduction.

  10. Oxygen isotopic signature of CO2 from combustion processes

    NASA Astrophysics Data System (ADS)

    Schumacher, M.; Werner, R. A.; Meijer, H. A. J.; Jansen, H. G.; Brand, W. A.; Geilmann, H.; Neubert, R. E. M.

    2011-02-01

    For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O) abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires), and human induced (fossil fuel combustion, biomass burning) in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects on the order of up to 26%permil; became obvious in the derived CO2 from combustion of different kinds of material, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature), sample geometries (e.g. texture and surface-volume ratios) and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive) transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original total 18O signature of the material appeared to have little influence, however, a contribution of specific bio-chemical compounds to

  11. Oxygen isotopic signature of CO2 from combustion processes

    NASA Astrophysics Data System (ADS)

    Schumacher, M.; Neubert, R. E. M.; Meijer, H. A. J.; Jansen, H. G.; Brand, W. A.; Geilmann, H.; Werner, R. A.

    2008-11-01

    For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O) abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires), and human induced (fossil fuel combustion, biomass burning) in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects in the order of about 26‰ became obvious, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature), sample geometries (e.g. texture and surface-volume ratios) and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive) transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original 18O signature of the material appeared to have little or no influence.

  12. Biological nitrification process simulation in groundwater with dissolved oxygen controller

    NASA Astrophysics Data System (ADS)

    Zuo, Jinlong

    2009-07-01

    Nowadays groundwater contamination by nitrogenous fertilizer is a globally growing problem, but groundwater always serves as an important water source, especially in rural area. In order to tackle this problem, biological nitrification and denitrification process has been widely used for removal of nitrogenous pollutants from polluted water. To improve removal efficiency, the dissolved oxygen (DO) controller is presented. And the control strategies for the activated sludge process have been developed and evaluated by simulation. The results also showed that the DO controller will be applied widely in the control and management of the decentralization water treatment.

  13. Temperature and oxygen visual estimator for carbonization process control

    NASA Astrophysics Data System (ADS)

    Martínez, Fredy; Martínez, Fernando; Montiel, Holman

    2017-02-01

    This paper proposes a visual estimator for temperature and oxygen content for closed loop control of carbonization furnace in the production of activated carbon. The carbonization process involves thermal decomposition of vegetal material in the absence of air; this requires rigorous sensing and control of these two variables. The system consists of two cameras, a thermographic camera to estimate the temperature, and a traditional digital camera to estimate the oxygen content. In both cases we use similarity measures between images to estimate the value of the variables into the furnace, estimation that is used to control the furnace flame. The algorithm is tested with reference photos taken at the production plant, and the experimental results prove the performance of the proposed technique.

  14. Fluorophore-based sensor for oxygen radicals in processing plasmas

    SciTech Connect

    Choudhury, Faraz A.; Shohet, J. Leon; Sabat, Grzegorz; Sussman, Michael R.; Nishi, Yoshio

    2015-11-15

    A high concentration of radicals is present in many processing plasmas, which affects the processing conditions and the properties of materials exposed to the plasma. Determining the types and concentrations of free radicals present in the plasma is critical in order to determine their effects on the materials being processed. Current methods for detecting free radicals in a plasma require multiple expensive and bulky instruments, complex setups, and often, modifications to the plasma reactor. This work presents a simple technique that detects reactive-oxygen radicals incident on a surface from a plasma. The measurements are made using a fluorophore dye that is commonly used in biological and cellular systems for assay labeling in liquids. Using fluorometric analysis, it was found that the fluorophore reacts with oxygen radicals incident from the plasma, which is indicated by degradation of its fluorescence. As plasma power was increased, the quenching of the fluorescence significantly increased. Both immobilized and nonimmobilized fluorophore dyes were used and the results indicate that both states function effectively under vacuum conditions. The reaction mechanism is very similar to that of the liquid dye.

  15. Oxygen-producing inert anodes for SOM process

    DOEpatents

    Pal, Uday B

    2014-02-25

    An electrolysis system for generating a metal and molecular oxygen includes a container for receiving a metal oxide containing a metallic species to be extracted, a cathode positioned to contact a metal oxide housed within the container; an oxygen-ion-conducting membrane positioned to contact a metal oxide housed within the container; an anode in contact with the oxygen-ion-conducting membrane and spaced apart from a metal oxide housed within the container, said anode selected from the group consisting of liquid metal silver, oxygen stable electronic oxides, oxygen stable crucible cermets, and stabilized zirconia composites with oxygen stable electronic oxides.

  16. BIOLOGICALLY ENHANCED OXYGEN TRANSFER IN THE ACTIVATED SLUDGE PROCESS (JOURNAL)

    EPA Science Inventory

    Biologically enhanced oxgyen transfer has been a hypothesis to explain observed oxygen transfer rates in activated sludge systems that were well above that predicted from aerator clean-water testing. The enhanced oxygen transfer rates were based on tests using BOD bottle oxygen ...

  17. Oxygen Sensitivity of Anammox and Coupled N-Cycle Processes in Oxygen Minimum Zones

    PubMed Central

    Kalvelage, Tim; Jensen, Marlene M.; Contreras, Sergio; Revsbech, Niels Peter; Lam, Phyllis; Günter, Marcel; LaRoche, Julie; Lavik, Gaute; Kuypers, Marcel M. M.

    2011-01-01

    Nutrient measurements indicate that 30–50% of the total nitrogen (N) loss in the ocean occurs in oxygen minimum zones (OMZs). This pelagic N-removal takes place within only ∼0.1% of the ocean volume, hence moderate variations in the extent of OMZs due to global warming may have a large impact on the global N-cycle. We examined the effect of oxygen (O2) on anammox, NH3 oxidation and NO3− reduction in 15N-labeling experiments with varying O2 concentrations (0–25 µmol L−1) in the Namibian and Peruvian OMZs. Our results show that O2 is a major controlling factor for anammox activity in OMZ waters. Based on our O2 assays we estimate the upper limit for anammox to be ∼20 µmol L−1. In contrast, NH3 oxidation to NO2− and NO3− reduction to NO2− as the main NH4+ and NO2− sources for anammox were only moderately affected by changing O2 concentrations. Intriguingly, aerobic NH3 oxidation was active at non-detectable concentrations of O2, while anaerobic NO3− reduction was fully active up to at least 25 µmol L−1 O2. Hence, aerobic and anaerobic N-cycle pathways in OMZs can co-occur over a larger range of O2 concentrations than previously assumed. The zone where N-loss can occur is primarily controlled by the O2-sensitivity of anammox itself, and not by any effects of O2 on the tightly coupled pathways of aerobic NH3 oxidation and NO3− reduction. With anammox bacteria in the marine environment being active at O2 levels ∼20 times higher than those known to inhibit their cultured counterparts, the oceanic volume potentially acting as a N-sink increases tenfold. The predicted expansion of OMZs may enlarge this volume even further. Our study provides the first robust estimates of O2 sensitivities for processes directly and indirectly connected with N-loss. These are essential to assess the effects of ocean de-oxygenation on oceanic N-cycling. PMID:22216239

  18. Oxygen sensitivity of anammox and coupled N-cycle processes in oxygen minimum zones.

    PubMed

    Kalvelage, Tim; Jensen, Marlene M; Contreras, Sergio; Revsbech, Niels Peter; Lam, Phyllis; Günter, Marcel; LaRoche, Julie; Lavik, Gaute; Kuypers, Marcel M M

    2011-01-01

    Nutrient measurements indicate that 30-50% of the total nitrogen (N) loss in the ocean occurs in oxygen minimum zones (OMZs). This pelagic N-removal takes place within only ~0.1% of the ocean volume, hence moderate variations in the extent of OMZs due to global warming may have a large impact on the global N-cycle. We examined the effect of oxygen (O(2)) on anammox, NH(3) oxidation and NO(3)(-) reduction in (15)N-labeling experiments with varying O(2) concentrations (0-25 µmol L(-1)) in the Namibian and Peruvian OMZs. Our results show that O(2) is a major controlling factor for anammox activity in OMZ waters. Based on our O(2) assays we estimate the upper limit for anammox to be ~20 µmol L(-1). In contrast, NH(3) oxidation to NO(2)(-) and NO(3)(-) reduction to NO(2)(-) as the main NH(4)(+) and NO(2)(-) sources for anammox were only moderately affected by changing O(2) concentrations. Intriguingly, aerobic NH(3) oxidation was active at non-detectable concentrations of O(2), while anaerobic NO(3)(-) reduction was fully active up to at least 25 µmol L(-1) O(2). Hence, aerobic and anaerobic N-cycle pathways in OMZs can co-occur over a larger range of O(2) concentrations than previously assumed. The zone where N-loss can occur is primarily controlled by the O(2)-sensitivity of anammox itself, and not by any effects of O(2) on the tightly coupled pathways of aerobic NH(3) oxidation and NO(3)(-) reduction. With anammox bacteria in the marine environment being active at O(2) levels ~20 times higher than those known to inhibit their cultured counterparts, the oceanic volume potentially acting as a N-sink increases tenfold. The predicted expansion of OMZs may enlarge this volume even further. Our study provides the first robust estimates of O(2) sensitivities for processes directly and indirectly connected with N-loss. These are essential to assess the effects of ocean de-oxygenation on oceanic N-cycling. © 2011 Kalvelage et al.

  19. Reactive Oxygen Species (ROS): Beneficial Companions of Plants’ Developmental Processes

    PubMed Central

    Singh, Rachana; Singh, Samiksha; Parihar, Parul; Mishra, Rohit K.; Tripathi, Durgesh K.; Singh, Vijay P.; Chauhan, Devendra K.; Prasad, Sheo M.

    2016-01-01

    Reactive oxygen species (ROS) are generated inevitably in the redox reactions of plants, including respiration and photosynthesis. In earlier studies, ROS were considered as toxic by-products of aerobic pathways of the metabolism. But in recent years, concept about ROS has changed because they also participate in developmental processes of plants by acting as signaling molecules. In plants, ROS regulate many developmental processes such as cell proliferation and differentiation, programmed cell death, seed germination, gravitropism, root hair growth and pollen tube development, senescence, etc. Despite much progress, a comprehensive update of advances in the understanding of the mechanisms evoked by ROS that mediate in cell proliferation and development are fragmentry and the matter of ROS perception and the signaling cascade remains open. Therefore, keeping in view the above facts, an attempt has been made in this article to summarize the recent findings regarding updates made in the regulatory action of ROS at various plant developmental stages, which are still not well-known. PMID:27729914

  20. Fermentation process using specific oxygen uptake rates as a process control

    DOEpatents

    Van Hoek; Pim , Aristidou; Aristos , Rush; Brian

    2007-06-19

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  1. Fermentation process using specific oxygen uptake rates as a process control

    DOEpatents

    Van Hoek, Pim; Aristidou, Aristos; Rush, Brian

    2014-09-09

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  2. Fermentation process using specific oxygen uptake rates as a process control

    DOEpatents

    Van Hoek, Pim [Minnetonka, MN; Aristidou, Aristos [Maple Grove, MN; Rush, Brian [Minneapolis, MN

    2011-05-10

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  3. Fermentation process using specific oxygen uptake rates as a process control

    SciTech Connect

    Van Hoek, Pim; Aristidou, Aristos; Rush, Brian J.

    2016-08-30

    Specific oxygen uptake (OUR) is used as a process control parameter in fermentation processes. OUR is determined during at least the production phase of a fermentation process, and process parameters are adjusted to maintain the OUR within desired ranges. The invention is particularly applicable when the fermentation is conducted using a microorganism having a natural PDC pathway that has been disrupted so that it no longer functions. Microorganisms of this sort often produce poorly under strictly anaerobic conditions. Microaeration controlled by monitoring OUR allows the performance of the microorganism to be optimized.

  4. Trojan Horse Method for the Oxygen-Burning Process Reactions

    NASA Astrophysics Data System (ADS)

    Hayakawa, S.; Spitaleri, C.; Burtebayev, N.; Aimaganbetov, A.; Artemov, S. V.; Figuera, P.; Fisichella, M.; Guardo, G. L.; Igamov, S.; Indelicato, I.; Kiss, G. G.; Kubono, S.; La Cognata, M.; Lamia, L.; Lattuada, M.; Nassurlla, M.; Piasecki, E.; Rapisarda, G. G.; Romano, S.; Sakuta, S. B.; TrzciÅska, A.; Tumino, A.; Urkinbayev, A.; Zholdybayev, T.

    The 16O + 16O fusion reaction is important in terms of the explosive oxygen burning process during late evolution stage of massive stars as well as understanding of the mechanism of low-energy heavy-ion fusion reactions. The astrophysical S factor of such a heavy-ion fusion strongly depends on energy at corresponding stellar temperatures. For the 16O + 16O reaction cross section, there are larger discrepancies among different experimental data as the energy decreases, and a complete lack of data below Ec.m. = 7 MeV. We aim to determine the cross sections for the two main exit channels, α + 28Si and p + 31P, toward stellar energies. The measurements were performed indirectly by the Trojan horse method (THM) via the 16O(20Ne, α α )28Si and 16O(20Ne, pα )31P three-body reactions, respectively. We performed measurements twice using 20Ne beams at Heavy Ion Laboratory (E20Ne = 45 MeV) and at Gumilyov Eurasian National University (E20Ne = 35 MeV). We discuss the applicability of the THM to such a heavy nuclear system showing preliminary results of the momentum distribution of α -16O intercluster motion in the TH nucleus 20Ne observed for the first time, which implies a possibility of a multi-step breakup of the TH nucleus.

  5. Singlet Oxygen Formation during the Charging Process of an Aprotic Lithium-Oxygen Battery.

    PubMed

    Wandt, Johannes; Jakes, Peter; Granwehr, Josef; Gasteiger, Hubert A; Eichel, Rüdiger-A

    2016-06-06

    Aprotic lithium-oxygen (Li-O2 ) batteries have attracted considerable attention in recent years owing to their outstanding theoretical energy density. A major challenge is their poor reversibility caused by degradation reactions, which mainly occur during battery charge and are still poorly understood. Herein, we show that singlet oxygen ((1) Δg ) is formed upon Li2 O2 oxidation at potentials above 3.5 V. Singlet oxygen was detected through a reaction with a spin trap to form a stable radical that was observed by time- and voltage-resolved in operando EPR spectroscopy in a purpose-built spectroelectrochemical cell. According to our estimate, a lower limit of approximately 0.5 % of the evolved oxygen is singlet oxygen. The occurrence of highly reactive singlet oxygen might be the long-overlooked missing link in the understanding of the electrolyte degradation and carbon corrosion reactions that occur during the charging of Li-O2 cells.

  6. Oxygen defect processes in silicon and silicon germanium

    SciTech Connect

    Chroneos, A.; Sgourou, E. N.; Londos, C. A.; Schwingenschlögl, U.

    2015-06-15

    Silicon and silicon germanium are the archetypical elemental and alloy semiconductor materials for nanoelectronic, sensor, and photovoltaic applications. The investigation of radiation induced defects involving oxygen, carbon, and intrinsic defects is important for the improvement of devices as these defects can have a deleterious impact on the properties of silicon and silicon germanium. In the present review, we mainly focus on oxygen-related defects and the impact of isovalent doping on their properties in silicon and silicon germanium. The efficacy of the isovalent doping strategies to constrain the oxygen-related defects is discussed in view of recent infrared spectroscopy and density functional theory studies.

  7. Effect of bottom water oxygenation on oxygen consumption and benthic biogeochemical processes at the Crimean Shelf (Black Sea)

    NASA Astrophysics Data System (ADS)

    Lichtschlag, A.; Janssen, F.; Wenzhöfer, F.; Holtappels, M.; Struck, U.; Jessen, G.; Boetius, A.

    2012-04-01

    Hypoxia occurs where oxygen concentrations fall below a physiological threshold of many animals, usually defined as <63 µmol L-1. Oxygen depletion can be caused by anthropogenic influences, such as global warming and eutrophication, but as well occurs naturally due to restricted water exchange in combination with high nutrient loads (e.g. upwelling). Bottom-water oxygen availability not only influences the composition of faunal communities, but is also one of the main factors controlling sediment-water exchange fluxes and organic carbon degradation in the sediment, usually shifting processes towards anaerobic mineralization pathways mediated by microorganisms. The Black Sea is one of the world's largest meromictic marine basins with an anoxic water column below 180m. The outer shelf edge, where anoxic waters meet the seafloor, is an ideal natural laboratory to study the response of benthic ecosystems to hypoxia, including benthic biogeochemical processes. During the MSM 15/1 expedition with the German research vessel MARIA S. MERIAN, the NW area of the Black Sea (Crimean Shelf) was studied. The study was set up to investigate the influence of bottom water oxygenation on, (1) the respective share of fauna-mediated oxygen uptake, microbial respiration, or re-oxidation of reduced compounds formed in the deeper sediments for the total oxygen flux and (2) on the efficiency of benthic biogeochemical cycles. During our study, oxygen consumption and pathways of organic carbon degradation were estimated from benthic chamber incubations, oxygen microprofiles measured in situ, and pore water and solid phase profiles measured on retrieved cores under oxic, hypoxic, and anoxic water column conditions. Benthic oxygen fluxes measured in Crimean Shelf sediments in this study were comparable to fluxes from previous in situ and laboratory measurements at similar oxygen concentrations (total fluxes -8 to -12 mmol m-2 d-1; diffusive fluxes: -2 to -5 mmol m-2 d-1) with oxygen

  8. Venus's Mysterious Oxygen Green Line: An Auroral Process?

    NASA Astrophysics Data System (ADS)

    Gray, Candace L.; Chanover, Nancy; Slanger, Tom; Molaverdikhani, Karan; Hausler, Bernd; Tellmann, Silvia; Peter, Kerstin; Witasse, Olivier; Blelly, Pierre-Louise; Garcia-Munoz, Antonio

    2014-11-01

    Observations of nightglow (upper atmospheric emission from atoms and molecules on the nightside of a planet) allow for a multifaceted study of planetary atmospheres. Information on winds, chemistry, and solar effects is gained by observing temporal and spacial variation in nightglow intensity. One of the brightest nightglow features on Earth is the OI (1S) 557.7 nm line (oxygen green line). This emission is primarily due to photodissociation/transport but is also seen in the aurora as electron precipitation.Unlike Earth, the Venusian green line is highly temporally variable. The chemistry and mechanisms responsible are still unknown. We observe the Venusian nightglow before and after solar flares, which produce large amounts of EUV emission, and coronal mass ejections (CMEs) impacts, which inject a large number of higher energy charged particles in the the Venusian atmosphere. We consistently detect green line emission after large charged particles injections from CMEs. However we do not detectthe OI (1D) red line at 630.0 nm, which is quenched below 150 km. We propose that the Venusian green line is an auroral-type emission due to electron precipitation and is occurring deep in the atmosphere, near 125 km.To investigate how CMEs and solar flares effect the electron energy, flux, and density in the Venusian nightside atmosphere, we compare data taken by ASPERA and ELS onboard Venus Express (VEX) before and after solar storms. We find that both electron energy and flux increase after CMEs, but onlyflux increases after solar flares. Additionally, the V1 ionospheric layer at 125 km increases in electron density while the V2 at 150 km decreases in density after CMEs but not after solar flares. We model the nightside Venusian ionosphere using the observed electron energy and fluxes from VEX in an effort to constrain the chemical processes and mechanisms responsible for green line emission. We will present the results of our ground-based observations and modeling.

  9. Data acquisition and information processing in MDO oxygen electrode measurement of tissue oxygen pressure.

    PubMed

    Odman, S; Lund, N

    1980-06-01

    In 1956, CLARK presented the principle for the modern, membrane-covered, oxygen electrode, comprising the anode and the cathode within the same unit. A further development was the MDO (Mehrdraht Dortmund Oberfläche) oxygen electrode presented by LUBBERS & KESSLER during the 1960s. This electrode comprises eight separate measuring points for collecting statistical samples to calculate tissue oxygen pressure fields. In order to perform studies on humans and to enable fast presentation of measurement results, a system was developed including a PDP 11/03 D computer, which fulfils patient safety demands. The computer program included corrections for electrode drift and temperature influences, as well as statistical calculations including mean, standard deviation, skewness and kurtosis. Also included was the two-sample Kolmogorov-Smirnov test for comparison of tissue oxygen distributions. Experience from studies on humans has shown that the measurement system enables us to collect and read important patient data directly at the bedside in the intensive care ward.

  10. Fuel and oxygen addition for metal smelting or refining process

    DOEpatents

    Schlichting, M.R.

    1994-11-22

    A furnace for smelting iron ore and/or refining molten iron is equipped with an overhead pneumatic lance, through which a center stream of particulate coal is ejected at high velocity into a slag layer. An annular stream of nitrogen or argon enshrouds the coal stream. Oxygen is simultaneously ejected in an annular stream encircling the inert gas stream. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus to react with carbon monoxide gas rising from slag layer, thereby adding still more heat to the furnace. 7 figs.

  11. Fuel and oxygen addition for metal smelting or refining process

    DOEpatents

    Schlichting, Mark R.

    1994-01-01

    A furnace 10 for smelting iron ore and/or refining molten iron 20 is equipped with an overhead pneumatic lance 40, through which a center stream of particulate coal 53 is ejected at high velocity into a slag layer 30. An annular stream of nitrogen or argon 51 enshrouds the coal stream. Oxygen 52 is simultaneously ejected in an annular stream encircling the inert gas stream 51. The interposition of the inert gas stream between the coal and oxygen streams prevents the volatile matter in the coal from combusting before it reaches the slag layer. Heat of combustion is thus more efficiently delivered to the slag, where it is needed to sustain the desired reactions occurring there. A second stream of lower velocity oxygen can be delivered through an outermost annulus 84 to react with carbon monoxide gas rising from slag layer 30, thereby adding still more heat to the furnace.

  12. [Tissue oxygen exchange and oxidative processes in long-livers: age peculiarities].

    PubMed

    Korkushko, O V; Ivanov, L A; Shatilo, V B

    2012-01-01

    This work was undertaken to study tissue oxygen exchange and oxidative processes in the long-lived individuals who were assumed as the physiologically aging individuals. Oxygen tension was assessed in forearm subcutaneous cellular tissue by means of the polarographic method while performing 10 min oxygen inhalation tests (with spontaneous oxygemogram recording) and a 10 min clamping of vessels. The obtained data served as the tissue oxygen exchange indicator. This approach made us possible to evaluate the oxygen delivery and oxygen uptake. To study qualitative characteristics of oxidative processes, we assessed vacat-oxygen of the blood and urine and estimated the underoxidation coefficient proposed by Muller. We have found that tissue respiration intensity falls, the amount of underoxidated products of the blood and urine rises, and the underoxidation coefficient increases in aging. The decrease of tissue oxygen respiration intensity in subcutaneous cellular tissue reflects the development of tissue hypoxia associated with reduced activity of the enzymes, being involved in oxygen exchange. An age-related decrease of tissue perfusion leads to the formation of circulatory hypoxia and also contributes considerably to tissue hypoxia formation. The revealed changes in the tissue oxygen exchange and oxidative processes in the long-livers are generally correspondent to those that can be seen in the people of 80-89 years. This finding speaks in favor of the physiological aging in the long-livers.

  13. Effect of high-oxygen and oxygen-free modified atmosphere packaging on the spoilage process of poultry breast fillets.

    PubMed

    Rossaint, Sonja; Klausmann, Sonja; Kreyenschmidt, Judith

    2015-01-01

    A comparison was made of the effect of atmospheres containing high oxygen (70% O2 and 30% CO2) or high nitrogen (70% N2 and 30% CO2) on the spoilage process during storage (at 4°C) of poultry fillets. Four samples of each gas atmosphere were analyzed at 7 sample points during storage. For this analysis, the growth of typical spoilage organisms (Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and Lactobacilli spp.) and total viable count (TVC) were analyzed and modeled by using the Gompertz function. Sensory analyses of the poultry samples were carried out by trained sensory panelists to analyze color, odor, texture, drip loss, and general appearance. The composition of the spoilage flora differed between the oxygen-free atmosphere and the high-oxygen atmosphere. Anaerobic conditions favored the growth of Lactobacilli spp., whereas aerobic gas composition favored the growth of B. thermosphacta. However, no significant difference (P<0.05) in TVC and sensory parameters were observed for poultry samples stored under a high-oxygen atmosphere in comparison to a high-nitrogen atmosphere. These results indicate that high-oxygen packaging has no additional beneficial effect on the quality maintenance and shelf life of fresh poultry fillets.

  14. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  15. The analysis and minimization of oxygen contamination in the powder processing of molybdenum disilicide

    SciTech Connect

    Shannon, Kruse

    1994-04-24

    Problems with MoSi2 include low-temperature fracture toughness, high-temperature creep resistance, and ``pest`` phenomena. Oxygen introduced by powder processing may be the cause of some of these problems. This study led to the following conclusions: Supplied powders have significant oxygen present prior to processing (up to 2.5 %), in the form of silica on the surface. This oxygen contamination did not increase by exposure to air at room temperature. An improved powder processing method was developed that uses glass encapsulation. Analysis of microstructures created from powders that contained 4900 to 24,100 ppM oxygen showed that the silica was transferred to the fully dense MoSi2 as SiO2 inclusions. A method of producing MoSi2 with less oxygen was attempted.

  16. Participation of oxygen, having diffused through a silver membrane catalyst, in heterogeneous oxidation processes

    SciTech Connect

    Gryaznov, V.M.; Gul'yanova, S.G.; Vedernikov, V.I.

    1986-08-01

    On the basis of an investigation of the characteristics of oxidation of hydrocarbons, alcohols and ammonia on a silver membrane catalyst, and also changes of its oxygen permeability proposals have been made in relation to participation of various forms of adsorbed oxygen in the limiting stage of its transfer through silver membranes in heterogeneous oxidation processes.

  17. "Oxygen supply" as modulator of aging processes: hypoxia and hyperoxia models for aging studies.

    PubMed

    Cataldi, Amelia; Di Giulio, Camillo

    2009-07-01

    Cell growth is regulated by several factors, including oxygen supply, which influence cell metabolism. Aging is characterized by decreased oxygen supply to tissue, a reduction of tissue PO(2) and of the activity of several enzymes and metabolic factors. The oxygen-gradient diffusion at capillary tissue level is essential for the cellular survival, while the homeostasis of the oxygen in the arterial blood is mediated by reflexes sensitive to oxygen decrease and by release of several factors. Aging is correlated with a reduction of cells' oxygen supply concomitant to a parallel decrease in oxygen demand by tissues. Both chronic hypoxia or hyperoxia are considered as stresses. Indeed, in both conditions, free radical species, which damage structural and functional components of the membrane, are generated. ROS (reactive oxygen species) are physiological products of aerobic life and their accumulation affects aging. Because hypoxia per se modulates mitochondria activity, influencing oxygen consumption, hypoxia and aging could share some link. Moreover, the observation that in hypoxia or hyperoxia there is an accumulation of lipofucsine as a general reaction to stress is consistent with the accumulation of such components during aging. Correlation between hypoxia-hyperoxia and life-span remains open until we solve the question of how and why do cells sense oxygen. In other words, to better understand aging we need to know what O(2) species are being sensed by cells. In conclusion, hypoxia and hyperoxia represent an experimental model adequate for studying aging processes.

  18. Numerical Study of the Reduction Process in an Oxygen Blast Furnace

    NASA Astrophysics Data System (ADS)

    Zhang, Zongliang; Meng, Jiale; Guo, Lei; Guo, Zhancheng

    2016-02-01

    Based on computational fluid dynamics, chemical reaction kinetics, principles of transfer in metallurgy, and other principles, a multi-fluid model for a traditional blast furnace was established. The furnace conditions were simulated with this multi-fluid mathematical model, and the model was verified with the comparison of calculation and measurement. Then a multi-fluid model for an oxygen blast furnace in the gasifier-full oxygen blast furnace process was established based on this traditional blast furnace model. With the established multi-fluid model for an oxygen blast furnace, the basic characteristics of iron ore reduction process in the oxygen blast furnace were summarized, including the changing process of the iron ore reduction degree and the compositions of the burden, etc. The study found that compared to the traditional blast furnace, the magnetite reserve zone in the furnace shaft under oxygen blast furnace condition was significantly reduced, which is conducive to the efficient operation of blast furnace. In order to optimize the oxygen blast furnace design and operating parameters, the iron ore reduction process in the oxygen blast furnace was researched under different shaft tuyere positions, different recycling gas temperatures, and different allocation ratios of recycling gas between the hearth tuyere and the shaft tuyere. The results indicate that these three factors all have a substantial impact on the ore reduction process in the oxygen blast furnace. Moderate shaft tuyere position, high recycling gas temperature, and high recycling gas allocation ratio between hearth and shaft could significantly promote the reduction of iron ore, reduce the scope of the magnetite reserve zone, and improve the performance of oxygen blast furnace. Based on the above findings, the recommendations for improvement of the oxygen blast furnace design and operation were proposed.

  19. Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

    USGS Publications Warehouse

    Waldron, M.C.; Wiley, J.B.

    1996-01-01

    The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

  20. Evaluation of processing options for lunar oxygen production

    NASA Astrophysics Data System (ADS)

    Cutler, Andrew H.; Waldron, Robert D.

    Certain modifications of previously proposed space resource utilization processes, characterized as 'second generation' processes, are reviewed. Most notable are the hydrogen reduction of the iron-bearing materials class of processes, and the acid leach of the selected materials class of processes. The usual qualitative and quantitative criteria previously applied in the literature to comparisons between processes are much easier to apply in comparing very similar processes. This reasoning is applied to a few selected processes both to draw conclusions and to highlight the process by which they may be reached. Preliminary ranking of processes shows which new ones merit substantial further study; e.g., hydrogen reduction of mixed ferruginous feeds, integration of thermal cycle water splitting with sulfate leaching, and hydrochloric acid leaching of olivines are new processes that merit study, and it is argued that olivine reduction and the concurrent reduction of several iron-bearing materials instead of just one definitely rank higher than ilmenite reduction on the basis of present-day research.

  1. Oxygen-assisted purification of platinum structures deposited by ion and electron beam induced processes

    NASA Astrophysics Data System (ADS)

    Perez-Roldan, M. J.; Mulders, J. J. L.; Trompenaars, P. H. F.

    2017-05-01

    Purification in the presence of O2 flux is investigated in platinum structures grown by ion and electron beam induced deposition processes using a standard precursor, MeCpPtMe3. Two different room temperature purification processes are evaluated. In the first process, the purification is obtained by simultaneously supplying oxygen and precursor gas during the deposition. In the second process, an in situ post-treatment is performed on deposited structures by electron irradiation in the presence of oxygen. The first process applied to electron beam deposition requires a high flux of oxygen to improve the purification efficiency, while application to ion beam deposition requires a lower oxygen flux to enhance purification while avoiding an additional increase of the milling process. Both purification processes result in high purity Pt depositions and a reduction of deposition yields. For the ion beam, the electrical resistivity only drops for the first purification process: deposition supplying simultaneously oxygen and gas precursor. The second process of electron post irradiation does result in compositional changes, including reduced amounts of carbon but does not result in improvements in resistivity. For the electron beam, the resistivity shows a significant reduction applying both purification processes in sequence: in this way a resistivity of 22.5 µΩ cm has been obtained which is only twice the bulk value for Pt.

  2. Production of oxygen on the moon - Which processes are best and why

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.

    1992-01-01

    An evaluation of the 20 processes put forth for the liberation of oxygen from lunar materials has resulted in a ranking according to overall feasibility. At this time, the eight processes considered to be the most likely candidates for oxygen production on the moon are: ilmenite reduction with H2, CO, and CH4, glass reduction with H2, molten silicate electrolysis, fluxed molten silicate electrolysis, vapor pyrolysis, and ion plasma pyrolysis.

  3. Production of oxygen on the moon - Which processes are best and why

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.

    1992-01-01

    An evaluation of the 20 processes put forth for the liberation of oxygen from lunar materials has resulted in a ranking according to overall feasibility. At this time, the eight processes considered to be the most likely candidates for oxygen production on the moon are: ilmenite reduction with H2, CO, and CH4, glass reduction with H2, molten silicate electrolysis, fluxed molten silicate electrolysis, vapor pyrolysis, and ion plasma pyrolysis.

  4. Coal Combustion Behavior in New Ironmaking Process of Top Gas Recycling Oxygen Blast Furnace

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenfeng; Xue, Qingguo; Tang, Huiqing; Wang, Guang; Wang, Jingsong

    2017-10-01

    The top gas recycling oxygen blast furnace (TGR-OBF) is a new ironmaking process which can significantly reduce the coke ratio and emissions of carbon dioxide. To better understand the coal combustion characteristics in the TGR-OBF, a three dimensional model was developed to simulate the lance-blowpipe-tuyere-raceway of a TGR-OBF. The combustion characteristics of pulverized coal in TGR-OBF were investigated. Furthermore, the effects of oxygen concentration and temperature were also analyzed. The simulation results show that the coal burnout increased by 16.23% compared to that of the TBF. The oxygen content has an obvious effect on the burnout. At 70% oxygen content, the coal burnout is only 21.64%, with a decrease of 50.14% compared to that of TBF. Moreover, the effect of oxygen temperature is also very obvious.

  5. Coal Combustion Behavior in New Ironmaking Process of Top Gas Recycling Oxygen Blast Furnace

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenfeng; Xue, Qingguo; Tang, Huiqing; Wang, Guang; Wang, Jingsong

    2017-08-01

    The top gas recycling oxygen blast furnace (TGR-OBF) is a new ironmaking process which can significantly reduce the coke ratio and emissions of carbon dioxide. To better understand the coal combustion characteristics in the TGR-OBF, a three dimensional model was developed to simulate the lance-blowpipe-tuyere-raceway of a TGR-OBF. The combustion characteristics of pulverized coal in TGR-OBF were investigated. Furthermore, the effects of oxygen concentration and temperature were also analyzed. The simulation results show that the coal burnout increased by 16.23% compared to that of the TBF. The oxygen content has an obvious effect on the burnout. At 70% oxygen content, the coal burnout is only 21.64%, with a decrease of 50.14% compared to that of TBF. Moreover, the effect of oxygen temperature is also very obvious.

  6. Methane Post-Processing and Hydrogen Separation for Spacecraft Oxygen Loop Closure

    NASA Technical Reports Server (NTRS)

    Greenwood, Zachary W.; Abeny, Morgan B.; Wall, Terry; Miller, Lee A.; Wheeler, Richard R., Jr.

    2017-01-01

    State-of-the-art life support oxygen recovery technology on the International Space Station is based on the Sabatier reaction where only about half of the oxygen required for the crew is recovered from metabolic carbon dioxide (CO2). The Sabatier reaction produces water as the primary product and methane as a byproduct. Oxygen recovery is constrained by both the limited availability of reactant hydrogen from water electrolysis and Sabatier methane (CH4) being vented as a waste product resulting in a continuous loss of reactant hydrogen. Post-processing methane with the Plasma Pyrolysis Assembly (PPA) to recover this hydrogen has the potential to substantially increase oxygen recovery and thus dramatically reduce the logistical challenges associated with oxygen resupply. The PPA decomposes methane into predominantly hydrogen and acetylene. A purification system is necessary to purify hydrogen before it is recycled back to the Sabatier reactor. Testing and evaluation of acetylene removal systems and PPA system architectures are presented and discussed.

  7. Molecular Oxygen and Reactive Oxygen Species in Bread-making Processes: Scarce, but Nevertheless Important.

    PubMed

    Decamps, Karolien; Joye, Iris J; De Vos, Dirk E; Courtin, Christophe M; Delcour, Jan A

    2016-01-01

    In bread making, O2 is consumed by flour constituents, yeast, and, optionally, some additives optimizing dough processing and/or product quality. It plays a major role especially in the oxidation/reduction phenomena in dough, impacting gluten network structure. The O2 level is about 7.2 mmol/kg dough, of which a significant part stems from wheat flour. We speculate that O2 is quickly lost to the atmosphere during flour hydration. Later, when the gluten network structure develops, some O2 is incorporated in dough through mixing-in of air. O2 is consumed by yeast respiration and in a number of reactions catalyzed by a wide range of enzymes present or added. About 60% of the O2 consumption in yeastless dough is ascribed to oxidation of fatty acids by wheat lipoxygenase activity. In yeasted dough, about 70% of the O2 in dough is consumed by yeast and wheat lipoxygenase. This would leave only about 30% for other reactions. The severe competition between endogenous (and added) O2-consuming systems impacts the gluten network. Moreover, the scarce literature data available suggest that exogenous oxidative enzymes but not those in flour may promote crosslinking of arabinoxylan in yeastless dough. In any case, dough turns anaerobic during the first minutes of fermentation.

  8. Numerical analysis of the primary processes controlling oxygen dynamics on the Louisiana Shelf

    NASA Astrophysics Data System (ADS)

    Yu, L.; Fennel, K.; Laurent, A.; Murrell, M. C.; Lehrter, J. C.

    2014-10-01

    The Louisiana shelf in the northern Gulf of Mexico receives large amounts of freshwater and nutrients from the Mississippi/Atchafalaya River system. These river inputs contribute to widespread bottom-water hypoxia every summer. In this study, we use a physical-biogeochemical model that explicitly simulates oxygen sources and sinks on the Louisiana shelf to identify the key mechanisms controlling hypoxia development. First, we validate the model simulation against observed dissolved oxygen concentrations, primary production, water column respiration, and sediment oxygen consumption. In the model simulation, heterotrophy is prevalent in shelf waters throughout the year except near the mouths of the Mississippi and Atchafalaya Rivers where primary production exceeds respiratory oxygen consumption during June and July. During this time, efflux of oxygen to the atmosphere, driven by photosynthesis and surface warming, becomes a significant oxygen sink while the well-developed pycnocline isolates autotrophic surface waters from the heterotrophic and hypoxic waters below. A substantial fraction of primary production occurs below the pycnocline in summer. We investigate whether this primary production below the pycnocline is mitigating the development of hypoxic conditions with the help of a sensitivity experiment where we disable biological processes in the water column (i.e. primary production and water column respiration). In this experiment below-pycnocline primary production reduces the spatial extent of hypoxic bottom waters only slightly. Our results suggest that the combination of physical processes and sediment oxygen consumption largely determine the spatial extent and dynamics of hypoxia on the Louisiana shelf.

  9. Numerical analysis of the primary processes controlling oxygen dynamics on the Louisiana shelf

    NASA Astrophysics Data System (ADS)

    Yu, L.; Fennel, K.; Laurent, A.; Murrell, M. C.; Lehrter, J. C.

    2015-04-01

    The Louisiana shelf, in the northern Gulf of Mexico, receives large amounts of freshwater and nutrients from the Mississippi-Atchafalaya river system. These river inputs contribute to widespread bottom-water hypoxia every summer. In this study, we use a physical-biogeochemical model that explicitly simulates oxygen sources and sinks on the Louisiana shelf to identify the key mechanisms controlling hypoxia development. First, we validate the model simulation against observed dissolved oxygen concentrations, primary production, water column respiration, and sediment oxygen consumption. In the model simulation, heterotrophy is prevalent in shelf waters throughout the year, except near the mouths of the Mississippi and Atchafalaya rivers, where primary production exceeds respiratory oxygen consumption during June and July. During this time, efflux of oxygen to the atmosphere, driven by photosynthesis and surface warming, becomes a significant oxygen sink. A substantial fraction of primary production occurs below the pycnocline in summer. We investigate whether this primary production below the pycnocline is mitigating the development of hypoxic conditions with the help of a sensitivity experiment where we disable biological processes in the water column (i.e., primary production and water column respiration). With this experiment we show that below-pycnocline primary production reduces the spatial extent of hypoxic bottom waters only slightly. Our results suggest that the combination of physical processes (advection and vertical diffusion) and sediment oxygen consumption largely determine the spatial extent and dynamics of hypoxia on the Louisiana shelf.

  10. Sub-ppb Oxygen Contaminant Detection in Semi-Conductor Processing

    NASA Technical Reports Server (NTRS)

    Man, K. F.

    1995-01-01

    Gaseous contaminants such as oxygen, water vapor, nitrogen and hydrocarbons are often present in the processing environment in semiconductor device fabrication and in containerless materials processing. The contaminants arise as a result of outgassing from hot surfaces or they may be part of the impurities in commercial ultra-high purity gases. Among these gaseous contaminants, oxygen is the most reactive and, therefore, has the most adverse effects on the end product. There has been an intense effort at the Jet Propulsion Laboratory to develop different types of oxygen sorbents to reduce oxygen concentration in a microgravity processing environment to sub-ppb (parts-per-billion) levels. Higher concentrations can lead to rapid surface oxide formation, hence reducing the quality of semiconductor devices. If the concentration of oxygen in a processing chamber at 1000oC is in the ppb level, it will only take approximately 10 seconds for an oxide layer to form on the surface of a sample. The interaction of oxygen with the water surface can lead to the formation of localized defects in semi-conductor devices, hence decreasing the manufacturing yield. For example, efficient production of 64 Mb RAM chips requires contaminations below ppb levels. This paper describes a technique for measuring trace quantities of oxygen contaminants by recording the monoatomic negative ions, O-, using mass spectrometry. The O- formation from the e--O2 interaction utilizes the electron dissociative attachment method that is greatly enhanced at the resonant energy (6.8 eV). The device combines a small gridded electron ionizer with a compact mass spectrometer. The concentrations of oxygen have been measured using the method of standard additions by diluting O2 in N2. The lowest detection limit obtained was 1.2 kHz (O- count rate) at a concentration of 10-10, corresponding to 0.1 ppb.

  11. Thermodynamic analysis of the process of formation of sulfur compounds in oxygen gasification of coal

    SciTech Connect

    G.Ya. Gerasimov; T.M. Bogacheva

    2001-05-15

    A thermodynamic approach to the description of the behavior of the system fuel-oxidizer in oxygen gasification of coal is used to reveal the main mechanisms of the process of capture of sulfur by the mineral part of the coal and to determine the fundamental possibility of the process for coals from different coal fields.

  12. The feasibility of processes for the production of oxygen on the moon

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.; Carrier, W. D., III

    1992-01-01

    An evaluation of the perceived feasibility of 20 different processs for the production of oxygen on the moon is presented. Many of them are largely untested and/or extremely complicated and difficult to implement. Simplicity, low energy, easily attainable feedstock, and resupply mass are the principal criteria for the processes that will ultimately be selected for the initial production of oxygen on the moon. An evaluation of the 20 processes resulted in a ranking according to overall feasibility. The eight processes considered to be the most likely candidates, at this time, for oxygen production on the moon are: ilmenite reduction of H2, CO2, and CH4; glass reduction with H2; molten silicate electrolysis; fluxed molten silicate electrolysis; vapor pyrolysis; and ion plasma pyrolysis.

  13. The feasibility of processes for the production of oxygen on the moon

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.; Carrier, W. D., III

    1992-01-01

    An evaluation of the perceived feasibility of 20 different processs for the production of oxygen on the moon is presented. Many of them are largely untested and/or extremely complicated and difficult to implement. Simplicity, low energy, easily attainable feedstock, and resupply mass are the principal criteria for the processes that will ultimately be selected for the initial production of oxygen on the moon. An evaluation of the 20 processes resulted in a ranking according to overall feasibility. The eight processes considered to be the most likely candidates, at this time, for oxygen production on the moon are: ilmenite reduction of H2, CO2, and CH4; glass reduction with H2; molten silicate electrolysis; fluxed molten silicate electrolysis; vapor pyrolysis; and ion plasma pyrolysis.

  14. Dissolved oxygen regulation by logarithmic/antilogarithmic control to improve a wastewater treatment process.

    PubMed

    Flores, Victor R; Sanchez, Edgar N; Béteau, Jean-François; Hernandez, Salvador Carlos

    2013-01-01

    This paper presents the automation of a real activated sludge wastewater treatment plant, which is located at San Antonio Ajijic in Jalisco, Mexico. The main objective is to create an on-line automatic supervision system, and to regulate the dissolved oxygen concentration in order to improve the performances of the process treating municipal wastewater. An approximate mathematical model is determined in order to evaluate via simulations different control strategies: proportional integral (PI), fuzzy PI and PI Logarithm/Antilogarithm (PI L/A). The controlled variable is dissolved oxygen and the control input is the injected oxygen. Based on this evaluation, the PI L/A controller is selected to be implemented in the real process. After that, the implementation, testing and fully operation of the plant automation are described. With this system, the considered wastewater treatment plant save energy and improves the effluent quality; also, the process monitoring is done online and it is easily operated by the plant users.

  15. Radiation processing of water, oxygen and ozone ices

    NASA Astrophysics Data System (ADS)

    Teolis, Benjamin D.

    solid. In solid O2, a fluence dependence in the sputtering yield was discovered (using 100 keV protons) and attributed to the production of trapped ozone, which enhanced the sputtering yield. The enhancement is due to the liberation of potential energy during radiolytic decomposition of O3 into O2, which contributes to the physical ejection of molecules from the solid; a physical phenomenon not previously observed in studies of sputtering. When irradiated O2 is warmed above ˜33 K, the O2 desorbs from the solid, leaving behind residual solid ozone that was found to possess a remarkably low density (˜0.34 g/cm 3). The discovery of a low density form of solid ozone can explain the temperature dependence in the infrared spectra of condensed ozone previously reported, but the molecular structure of the solid and the reason for its transformation to a high density form at ˜47 K are still open questions. Solid ozone was found to possess an extraordinarily high sputtering yield when irradiated by 100 keV protons at 30 K and above, second only to solid hydrogen. This is due to (i) the high chemical reactivity of the solid and (ii) the volatility of the decomposition product (O2). Laboratory simulations of processes on astronomical surfaces that use infrared reflectance spectroscopy of thin films to analyze their composition and structure often ignore important optical interference effects which often lead to erroneous measurements of absorption band strengths and give an apparent dependence of this quantity on film thickness, index of refraction and wavelength. In appendix 1, these interference effects are demonstrated experimentally and the optical depths of several absorption bands of thin water ice films on a gold mirror are shown to be disproportionate to film thickness. A way to remove interference effects by performing measurements with P-polarized light incident at Brewster's angle is proposed. Additionally, appendix 2 describes a computer program I created to perform

  16. Relationship between oxygen transfer rate and airflow for fine-pore aeration under process conditions.

    PubMed

    Iranpour, R; Stenstrom, M K

    2001-01-01

    Although feedback systems that control the air supply to aeration tanks inherently incorporate some assumption about oxygen transfer response to changes in airflow, it is rare to measure this relationship under process conditions. This paper reports measurements of oxygen mass-transfer curves (MTCs) for a tank at the Tillman Water Reclamation Plant in Los Angeles, California. The curves were obtained by measuring the oxygen transfer efficiency (OTE) at selected points for several set values of airflow while the plant was operating. They approximate inverted parabolas because increasing the airflow increases the amount of oxygen supplied by the blowers, but decreases the OTE, which is the fraction of the supplied oxygen that actually enters the water. Data were recorded from both recently cleaned diffusers and ones that were moderately to severely fouled. The peaks in the curves from the fouled diffusers are at or below the midpoints of the observed ranges of airflows. Hence, there is only a narrow range of usable airflows between the lower limit, determined by the manufacturer of the diffusers, and the peak of the MTC, which is the maximum amount of oxygen that can be supplied. The peaks for the cleaned diffusers are higher, which allows more ability to adjust to changing biological loads. These results show that existing dissolved oxygen control systems may not be adequate and that fouling may reduce not only the overall efficiency of an aeration system but its ability to respond to changes in the biological load. The measurements also provide some insight to the limitations of using sparsely distributed dissolved oxygen sensors to control the aeration process and the excess costs that are incurred by the consequent need to compensate for uncertainty with extra air. However, additional testing is needed to determine whether the present results are aberrant or typical of tanks with fouled or cleaned diffusers.

  17. Properties of Aluminum Deposited by a High-Velocity Oxygen-Fueled Process

    SciTech Connect

    Chow, R; Decker, T A; Gansert, R V; Gansert, D; Lee, D

    2001-06-12

    Aluminum coatings deposited by a HVOF process have been demonstrated and relevant coating properties evaluated according to two deposition parameters, the spray distance and the oxygen-to-fuel flow ratio. The coating porosity, surface roughness, and microhardness are measured. The coating properties are fairly insensitive to spray distance, the distance between the nozzle and the workpiece, and fuel ratios, the oxygen-to-fuel flow. Increasing the fuel content does appear to improve the process productivity in terms of surface roughness. Minimization of nozzle loading is discussed.

  18. Oxygen and carbon dioxide kinetic challenges for thermophilic mineral bioleaching processes.

    PubMed

    de Kock, S H; Barnard, P; du Plessis, C A

    2004-04-01

    Agitated bacterial tank bioleaching reactors are currently sparged with air to satisfy both oxygen and CO(2) requirements of microbial cells. Under high-sulphide loading conditions, as is the case with high-grade metal sulphide concentrates, the microbial and chemical demand for oxygen is significantly increased during the bioleaching process. Sparging with enriched oxygen gas may offer an alternative process option to increased agitation and sparged aeration, to overcome the mass transfer difficulties at elevated temperatures where thermophilic Archaea, rather than Bacteria, are used. In the case of air sparging, the DO (dissolved oxygen) concentration in tank reactors could not be increased to a point where it would become inhibitory due to the limited oxygen content of air (20.9% O(2)). The use of enriched oxygen in such reactors at large scale does, however, pose its own set of process risks. The first aim of this investigation was, therefore, to determine the effects of various DO concentrations, in both the limiting and inhibitory ranges, on the microbial activity of Sulfolobus sp. U40813, a typical thermophilic mineral-leaching archaeon. Secondly, the effect of CO(2) concentration on the rate of ferrous iron oxidation was investigated. Both the oxygen and CO(2) kinetics were examined in controlled batch cultures at 78 degrees C, using ferrous sulphate and potassium tetrathionate as energy sources. The optimal DO concentration for iron oxidation was found to be between 1.5 and 4.1 mg.l(-1). The use of elevated DO concentrations (above 4.1 mg.l(-1)) inhibited the ferrous oxidation rates. The optimal gas CO(2) concentration for ferrous iron oxidation was found to be in the range 7-17% (v/v). The iron oxidation rates were, however, severely limited at CO(2) concentrations less than 7%, indicating that the CO(2) supply was limiting in this range and inhibited the microbial growth rate.

  19. Stable Isotope Composition of Molecular Oxygen in Soil Gas and Groundwater: A Potentially Robust Tracer for Diffusion and Oxygen Consumption Processes

    NASA Astrophysics Data System (ADS)

    Aggarwal, Pradeep K.; Dillon, M. A.

    1998-02-01

    We have measured the concentration and isotopic composition of molecular oxygen in soil gas and groundwater. At a site near Lincoln, Nebraska, USA, soil gas oxygen concentrations ranged from 13.8 to 17.6% at depths of 3-4 m and the δ 18O values ranged mostly from 24.0 to 27.2‰ (SMOW). The concentration of dissolved oxygen in a perched aquifer in the Texas Panhandle (depth to water ˜76 m) was about 5 mg/L and the δ 18O values were 21.2-22.9‰. The δ 18O of soil gas oxygen in our study are higher and those of dissolved oxygen are lower than the δ 18O of atmospheric oxygen (23.5‰). A model for the oxygen concentration and isotopic composition in soil gas was developed using the molecular diffusion theory. The higher δ 18O values in soil gas at the Nebraska site can be explained by the effects of diffusion and soil respiration (plant root and bacterial) on the isotopic composition of molecular oxygen. The lower δ 18O of dissolved oxygen at the Texas site indicates that oxygen consumption below the root zone in the relatively thick unsaturated zone here may have occurred with a different fractionation factor (either due to inorganic consumption or due to low respiration rates) than that observed for the dominant pathways of plant root and bacterial respiration. It is concluded that the use of the concentration and isotopic composition of soil gas and dissolved oxygen should provide a robust tool for studying the subsurface gaseous diffusion and oxygen consumption processes.

  20. BENTHIC AND WATER COLUMN PROCESSES IN A SUBTROPICAL ESTUARY: EFFECTS OF LIGHT ON OXYGEN FLUXES

    EPA Science Inventory

    Murrell, M.C., J.D. Hagy, J.G. Campbell and J.M. Caffrey. In press. Benthic and Water Column Processes in a Subtropical Estuary: Effects of Light on Oxygen Fluxes (Abstract). To be presented at the ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, 13-18 ...

  1. BENTHIC AND WATER COLUMN PROCESSES IN A SUBTROPICAL ESTUARY: EFFECTS OF LIGHT ON OXYGEN FLUXES

    EPA Science Inventory

    Murrell, M.C., J.D. Hagy, J.G. Campbell and J.M. Caffrey. In press. Benthic and Water Column Processes in a Subtropical Estuary: Effects of Light on Oxygen Fluxes (Abstract). To be presented at the ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, 13-18 ...

  2. Oxygen uptake rate tests to evaluate integrated fixed film activated sludge processes.

    PubMed

    Maas, Carol L A; Parker, Wayne J; Legge, Raymond L

    2008-12-01

    A modified oxygen uptake rate (OUR) test for characterizing the performance of integrated fixed-film activated sludge (IFAS) processes was developed while monitoring the startup of a full-scale demonstration facility. Data on total biofilm solids, in-basin nitrification rates, and batch nitrification rates were compared to the OUR test. The data was used to investigate dynamic changes in the physical and microbiological parameters during and after plant startup. Nitrification of the carriers was observed to follow different trends than the biofilm total solids during process startup. The process reached high nitrification rates within weeks, whereas the biofilm total solids required more than 50 days to attain a quasi-steady-state. This study illustrated that parameters in addition to biofilm total solids are required to assess activity in nitrifying IFAS processes and oxygen uptake rates can be a useful tool in this regard.

  3. Modelling Oxygen Dynamics in an Intermittently Stratified Estuary: Estimation of Process Rates Using Field Data

    NASA Astrophysics Data System (ADS)

    Borsuk, M. E.; Stow, C. A.; Luettich, R. A.; Paerl, H. W.; Pinckney, J. L.

    2001-01-01

    The relationship between bottom water dissolved oxygen concentration, vertical stratification, and temperature was investigated for the Neuse River estuary, North Carolina, a shallow, intermittently-mixed estuary using approximately 10 years of weekly/biweekly, mid-channel data. A generalized additive model (GAM) was used to initially explore the major relationships among observed variables. The results of this statistical model guided the specification of a process-based model of oxygen dynamics that is consistent with theory yet simple enough to be parameterized using available field data. The nonlinear optimization procedure employed allows for the direct estimation of microbial oxygen consumption and physical reoxygenation rates, including the effects of temperature and vertical stratification. These estimated rates may better represent aggregate system behaviour than closed chamber measurements made in the laboratory and in situ. The resulting model describes 79% of the variation in dissolved oxygen concentration and is robust when compared across separate locations and time periods. Model predictions suggest that the spatial extent and duration of hypoxia in the bottom waters of the Neuse are controlled by the balance between the net oxygen depletion rate and the frequency of vertical mixing events. During cool months, oxygen consumption rates remain low enough to keep oxygen concentration well above levels of concern even under extended periods of stratification. A concentration below 4 mg l -1is only expected under extended periods without vertical mixing when bottom water temperature exceeds 15 °C, while a concentration below 2 mg l -1is only expected when water temperature exceeds 20 °C. To incorporate the effects of parameter uncertainty, model error, and natural variability on model prediction, we used Monte Carlo simulation to generate distributions for the predicted number of days of hypoxia during the summer season. The expected number of days with

  4. Effect of Dissolved Oxygen on Cu Corrosion in Single Wafer Cleaning Process

    NASA Astrophysics Data System (ADS)

    Imai, Masayoshi; Yamashita, Yukinari; Futatsuki, Takashi; Shiohara, Morio; Kondo, Seiichi; Saito, Shuichi

    2009-04-01

    We investigated Cu corrosion at the via bottom of multi-layered Cu interconnects that occurred after post-etching wet cleaning and caused via open failures. We found that oxygen was dissolved into de-ionized water (DIW) on the wafer edge from the air atmosphere during the rinse step after chemical cleaning and that Cu was oxidized due to the high oxidation-reduction potential (ORP) of the rinse DIW. To prevent Cu interconnects from being corroded, control of the dissolved oxygen and the ORP of the rinse DIW by decreasing the oxygen concentration of the atmosphere in the cleaning machine as well as by using H2 water is required. This will become indispensable in the cleaning process of the next generation Cu interconnects.

  5. Process for selection of Oxygen-tolerant algal mutants that produce H.sub.2

    SciTech Connect

    Ghirardi, Maria L.; Seibert, Michael

    1999-01-01

    A process for selection of oxygen-tolerant, H.sub.2 -producing algal mutant cells comprising: (a) growing algal cells photoautotrophically under fluorescent light to mid log phase; (b) inducing algal cells grown photoautrophically under fluorescent light to mid log phase in step (a) anaerobically by (1) resuspending the cells in a buffer solution and making said suspension anaerobic with an inert gas; (2) incubating the suspension in the absence of light at ambient temperature; (c) treating the cells from step (b) with metronidazole, sodium azide, and added oxygen to controlled concentrations in the presence of white light. (d) washing off metronidazole and sodium azide to obtain final cell suspension; (e) plating said final cell suspension on a minimal medium and incubating in light at a temperature sufficient to enable colonies to appear; (f) counting the number of colonies to determine the percent of mutant survivors; and (g) testing survivors to identify oxygen-tolerant H.sub.2 -producing mutants.

  6. Activation processes on GaAs photocathode by different currents of oxygen source

    NASA Astrophysics Data System (ADS)

    Miao, Zhuang; Shi, Feng; Cheng, Hongchang; Wang, Shufei; Zhang, Xiaohui; Yuan, Yuan; Chen, Chang

    2015-04-01

    In order to know the influence of activation processes on GaAs photocathodes, three GaAs samples were activated by a fixed current of cesium source and different currents of oxygen source. The current of caesium source is same during activation to ensure initial adsorption of caesium quantum is similar, which is the base to show the difference during alternation activation of caesium and oxygen. Analysed with the activation data, it is indicated that Cs-to-O current ratio of 1.07 is the optimum ratio to obtain higher sensitivity and better stability. According to double dipole model, stable and uniform double dipole layers of GaAs-O-Cs:Cs-O-Cs are formed and negative electron affinity is achieved on GaAs surface by activation with cesium and oxygen. The analytical result is just coincident with the model. Thus there is an efficient technological method to improve sensitivity and stability of GaAs photocathode.

  7. Monitoring of singlet oxygen in the lower troposphere and processes of ozone depletion.

    NASA Astrophysics Data System (ADS)

    Iasenko, Egor; Chelibanov, Vladimir; Marugin, Alexander; Kozliner, Marat

    2016-04-01

    The processes of ozone depletion in the atmosphere are widely discussed now in a connection with the problem of a global climate changes. It is known fact that photolysis of ozone in the upper atmosphere is the source of metastable molecules of oxygen. But, metastable molecules of oxygen can be formed as a result of photo initiated heterogeneous oxidation of molecules adsorbed on the surface of natural aerosol particles. During the outdoor experiment, we observed a formation of Singlet oxygen (1Δg) at concentration level of 2 ... 5 ppb when ice crystals have been exposed to the sun light. In experiments, we used Analyzers of Singlet oxygen and Ozone (produced by JSC "OPTEC") that utilize solid-state chemiluminescence technology. We assumed that the singlet oxygen is formed in the active centers on the surface of ice crystals in the presence or absence of anthropogenic pollutants in the atmosphere. Identified efficiency of heterogeneous reaction of O2 (1Δg) formation suggests the importance of the additional channel O3 + O2 (1Δg) → 2O2 + O (3P) of atmospheric ozone removal comparable with other well known cycles of ozone depletion.

  8. Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

    NASA Astrophysics Data System (ADS)

    Thomsen, S.; Kanzow, T.; Colas, F.; Echevin, V.; Krahmann, G.; Engel, A.

    2016-02-01

    The Peruvian upwelling region shows pronounced near-surface submesoscale variability including filaments and sharp density fronts. Submesoscale frontal processes can drive large vertical velocities and enhance vertical tracer fluxes in the upper ocean. The associated high temporal and spatial variability poses a large challenge to observational approaches targeting these processes. In this study the role of submesoscale processes for the ventilation of the near-coastal oxygen minimum zone off Peru is investigated. We use satellite based sea surface temperature measurements and multiple high-resolution glider observations of temperature, salinity, oxygen and chlorophyll fluorescence carried out in January and February 2013 off Peru near 14°S during active upwelling. Additionally, high-resolution regional ocean circulation model outputs (ROMS) outputs are analysed. At the beginning of our observational survey a previously upwelled, productive and highly oxygenated water body is found in the mixed layer. Subsequently, a cold filament forms and the waters are moved offshore. After the decay of the filament and the relaxation of the upwelling front, the oxygen enriched surface water is found in the previously less oxygenated thermocline suggesting the occurrence of frontal subduction. A numerical model simulation is used to analyse the evolution of Lagrangian numerical floats in several upwelling filaments, whose vertical structure and hydrographic properties agree well with the observations. The floats trajectories support our interpretation that the subduction of previously upwelled water occurs in filaments off Peru. We find that 40 - 60 % of the floats seeded in the newly upwelled water is subducted within a time period of 5 days. This hightlights the importance of this process in ventilating the oxycline off Peru.

  9. Modeling the Oxygen Cycle in the Equatorial Pacific: Regulation of Physical and Biogeochemical Processes

    NASA Astrophysics Data System (ADS)

    Wang, X.; Murtugudde, R. G.; Zhang, D.

    2016-12-01

    Photosynthesis and respiration are important processes in all ecosystems on the Earth, in which carbon and oxygen are the two main elements. However, the oxygen cycle has received much less attention (relative to the carbon cycle) despite its big role in the earth system. Oxygen is a sensitive indicator of physical and biogeochemical processes in the ocean thus a key parameter for understanding the ocean's ecosystem and biogeochemistry. The Oxygen-Minimum-Zone (OMZ), often seen below 200 m, is a profound feature in the world oceans. There has been evidence of OMZ expansion over the past few decades in the tropical oceans. Climate models project that there would be a continued decline in dissolved oxygen (DO) and an expansion of the tropical OMZs under future warming conditions, which is of great concern because of the implications for marine organisms. We employ a validated three-dimensional model that simulates physical transport (circulation and vertical mixing), biological processes (O2 production and consumption) and ocean-atmosphere O2 exchange to quantify various sources and sinks of DO over 1980-2015. We show how we use observational data to improve our model simulation. Then we assess the spatial and temporal variability in simulated DO in the tropical Pacific Ocean, and explore the impacts of physical and biogeochemical processes on the DO dynamics, with a focus on the MOZ. Our analyses indicate that DO in the OMZ has a positive relationship with the 13ºC isotherm depth and a negative relationship with the concentration of dissolved organic material.

  10. Microstructural evolution in high oxygen fugacity processed bismuth strontium calcium copper oxide

    NASA Astrophysics Data System (ADS)

    Gannon, John J., Jr.

    A decomposition/reformation process that uses a high oxygen fugacity (2 MPa) heat treatment followed by low oxygen fugacity (<1 MPa) annealing was applied to silver-sheathed Bisb2Srsb2CaCusb2Osb{8±delta} (Bi-2212) tapes. The rate at which the Bi-2212 phase reforms was studied using X-ray diffractometry and image analyses. The kinetic data was fitted to an Avrami-type equation and was found to be consistent with that predicted for diffusion-controlled growth of plate-like grains. The effect of varying the oxygen fugacity during reformation annealing was also studied and the rate of Bi-2212 phase formation slowed considerably with increasing oxygen fugacity. The rate of oxygen exsolution from the core is a key parameter for the overall transformation kinetics. Two of the decomposition products produced by high-fOsb2 processing of the Bi-2212 compound are a copper-free alkaline-earth bismuthate (a Bisb9Srsb{11}Casb5Osb{x}-type) and CuO. Blended mixtures of these two compounds were used to form two-powder reaction couples used to study Bi-2212 phase formation. Samples were annealed in flowing oxygen at temperatures below the Bi-2212 solidus. The formation of apparent Bi-2212/Bi-2201 intergrowths along with some alkaline-earth cuprate phases were detected. The 14:24-type alkaline-earth cuprate phase was formed in fine CuO powder couples but not in couples containing large CuO particles. The reaction leading to Bi-2212 phase formation was confirmed to be solid-state at temperatures below 875sp°C. The development of c-axis grain alignment in high-fOsb2 decomposed Bi-2212 tapes that were reformed with low-fOsb2 annealing was studied. Such processing can produce enhanced 00l grain alignment and the evolution of this texture was examined in tapes at intermediate points in the reformation process. Some of the mechanisms associated with texture development in melt-processed tapes were found to be inadequate for describing the alignment in high-fOsb2 processed Bi-2212 grains

  11. Chlorination processing of local planetary ores for oxygen and metallurgically important metals

    NASA Technical Reports Server (NTRS)

    Lynch, D. C.

    1989-01-01

    The use of chlorine to extract, reclaim, and purify metals has attractive possibilities for extraterrestrial processing of local planetary resources. While a complete cyclic process has been proposed for the recovery of metallurgically significant metals and oxygen, herein the chlorination step of the cycle is examined. An experimental apparatus for reacting refractory materials, such as ilmenite, in a microwave induced plasma is being built. Complex equilibria calculations reveal that stable refractory materials can, under the influence of a plasma, undergo chlorination and yield oxygen as a by-product. These issues and the potential advantages for plasma processing in space are reviewed. Also presented is a discussion of the complex equilibria program used in the analysis.

  12. Liquid PEG Polymers Containing Antioxidants: A Versatile Platform for Studying Oxygen-Sensitive Photochemical Processes.

    PubMed

    Mongin, Cédric; Golden, Jessica H; Castellano, Felix N

    2016-09-14

    This article proposes the exploitation of widely available, inexpensive, innocuous "green" liquid polyethylene glycol (PEG) polymers containing the oxygen scavenger oleic acid (OA) as promising media for studying oxygen-sensitive photochemical processes. Here we report the successful application of this media to detailed investigations of triplet-sensitized photochemical upconversion, previously established as being readily poisoned by dissolved oxygen. Three different PEG materials were investigated with increasing molecular weight from 200 to 600 g/mol, coded as PEG-200, PEG-400, and PEG-600. These fluidic polymers facilitate an oxygen-depleted environment in comparison to commonly employed organic solvents while providing high solubility and diffusion for the dissolved chromophores. Moreover, the low oxygen permeation afforded by these PEG solvents allows them to remain deoxygenated in open containers under ambient conditions for extended time periods. OA, 9,10-dimethylanthracene (DMA), and 2,5-dimethylfuran (DMF) are shown to efficiently and quantitatively consume dissolved oxygen in the PEG environment in the presence of the photoactivated triplet sensitizer platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP). Oxygen consumption was directly correlated with systematically increasing sensitizer excited-state lifetimes that eventually reach the same plateau as achieved through extensive N2 sparging. Diffusion-controlled bimolecular triplet-triplet energy transfer quenching between PtTPBP and the acceptor/annihilator 9,10-bisphenylethynylanthracene (BPEA) was observed in all three PEG formulations investigated. Subsequent triplet-triplet annihilation, between triplet excited BPEA acceptors, achieves bright and stable upconverted singlet fluorescence from BPEA with no decrease in intensity over 20 h under ambient conditions. In the champion composition (PEG 200), the upconversion quantum efficiency reached 31% under conditions where triplet-triplet annihilation

  13. Characterization of an oxygen plasma process for cleaning packaged semiconductor devices. Final report

    SciTech Connect

    Adams, B.E.

    1996-11-01

    The purpose of this research was to experimentally determine the operating {open_quotes}window{close_quotes} for an oxygen plasma cleaning process to be used on microelectronics components just prior to wire bonding. The process was being developed to replace one that used vapor degreasing with trichlorotrifluoroethane, an ozone-depleting substance. A Box-Behnken experimental design was used to generate data from which the oxygen plasma cleaning process could be characterized. Auger electron spectrophotometry was used to measure the contamination thickness on the dice after cleaning. An empirical equation correlating the contamination thickness on the die surface with the operating parameters of the plasma system was developed from the collected Auger data, and optimum settings for cleaning semiconductor devices were determined. Devices were also tested for undesirable changes in electrical parameters resulting from cleaning in the plasma system. An increase in leakage current occurred for bipolar transistors and diodes after exposure to the oxygen plasma. Although an increase in leakage current occurred, each device`s parameter remained well below the acceptable specification limit. Based upon the experimental results, the optimum settings for the plasma cleaning process were determined to be 200 watts of power applied for five minutes in an enclosure maintained at 0.7 torr. At these settings, all measurable contamination was removed without compromising the reliability of the devices.

  14. A Novel “Oxygen-induced” Greening Process in a Cyanobacterial Mutant Lacking the Transcriptional Activator ChlR Involved in Low-oxygen Adaptation of Tetrapyrrole Biosynthesis*

    PubMed Central

    Aoki, Rina; Hiraide, Yuto; Yamakawa, Hisanori; Fujita, Yuichi

    2014-01-01

    ChlR activates the transcription of the chlAII-ho2-hemN operon in response to low-oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803. Three genes in the operon encode low-oxygen-type enzymes to bypass three oxygen-dependent reactions in tetrapyrrole biosynthesis. A chlR-lacking mutant, ΔchlR, shows poor photoautotrophic growth due to low chlorophyll (Chl) content under low-oxygen conditions, which is caused by no induction of the operon. Here, we characterized the processes of etiolation of ΔchlR cells in low-oxygen conditions and the subsequent regreening of the etiolated cells upon exposure to oxygen, by HPLC, Western blotting, and low-temperature fluorescence spectra. The Chl content of the etiolated ΔchlR cells incubated under low-oxygen conditions for 7 days was only 10% of that of the wild-type with accumulation of almost all intermediates of the magnesium branch of Chl biosynthesis. Both photosystem I (PSI) and photosystem II (PSII) were significantly decreased, accompanied by a preferential decrease of antenna Chl in PSI. Upon exposure to oxygen, the etiolated ΔchlR cells resumed to produce Chl after a short lag (∼2 h), and the level at 72 h was 80% of that of the wild-type. During this novel “oxygen-induced” greening process, the PSI and PSII contents were largely increased in parallel with the increase in Chl contents. After 72 h, the PSI content reached ∼50% of the wild-type level in contrast to the full recovery of PSII. ΔchlR provides a promising alternative system to investigate the biogenesis of PSI and PSII. PMID:24297184

  15. Process for the conversion of lower alcohols to higher branched oxygenates

    DOEpatents

    Barger, P.T.

    1996-09-24

    A process is provided for the production of branched C{sub x} oxygenates from lower alcohols such as methanol, ethanol, propanol and mixtures thereof. The process comprises contacting the lower alcohols with a solid catalyst comprising a mixed metal oxide support having components selected from the group consisting of oxides of zinc, magnesium, zirconia, titanium, manganese, chromium, and lanthanides, and an activation metal selected from the group consisting of Group VIII metal, Group IB metals, and mixtures thereof. The advantage of the process is improved yields and selectivity to isobutanol which can subsequently be employed in the production of high octane motor gasoline.

  16. Process for the conversion of lower alcohols to higher branched oxygenates

    DOEpatents

    Barger, Paul T.

    1996-01-01

    A process is provided for the production of branched C.sub.4+ oxygenates from lower alcohols such as methanol, ethanol, propanol and mixtures thereof. The process comprises contacting the lower alcohols with a solid catalyst comprising a mixed metal oxide support having components selected from the group consisting of oxides of zinc, magnesium, zirconia, titanium, manganese, chromium, and lanthanides, and an activation metal selected from the group consisting of Group VIII metal, Group IB metals, and mixtures thereof. The advantage of the process is improved yields and selectivity to isobutanol which can subsequently be employed in the production of high octane motor gasoline.

  17. Oxygen assisted laser cutting mechanism—a laminar boundary layer approach including the combustion process

    NASA Astrophysics Data System (ADS)

    Yilbaş, B. S.; Sahin, A. Z.

    1995-06-01

    The present study examines the combined effects of chemical reactions taking place between a gas jet and molten metal, the cooling effect of the jet and the evaporation of metal, during a CO 2 laser cutting process. A laminar boundary layer approach was used to develop a theoretical model for the oxygen gas jet laser cutting mechanism. An experiment was carried out to monitor the keyhole formation using a video recorder and detect the light emitted from the entrance and exist surfaces of the workpiece using a fibre-optic probe during the cutting process. The experimental study was extended to employ two different workpiece materials (stainless steel and mild steel) at two thicknesses, and varying oxygen assisting gas pressures. It is found that the theoretical model developed in the present study is valid for a cutting speed of about 30 mm s -1 and all jet velocities up to sonic, since the effect of shock is excluded in the model.

  18. Syngas chemical looping gasification process: oxygen carrier particle selection and performance

    SciTech Connect

    Fanxing Li; Hyung Ray Kim; Deepak Sridhar; Fei Wang; Liang Zeng; Joseph Chen; L.-S. Fan

    2009-08-15

    The syngas chemical looping (SCL) process coproduces hydrogen and electricity. The process involves reducing metal oxides with syngas followed by regeneration of reduced metal oxides with steam and air in a cyclic manner. Iron oxide is determined to be a desired oxygen carrier for hydrogen production considering overall properties including oxygen carrying capacity, thermodynamic properties, reaction kinetics, physical strength, melting points, and environmental effects. An iron oxide based particle can maintain good reactivity for more than 100 reduction-oxidation (redox) cycles in a thermogravimetric analyzer (TGA). The particle exhibits a good crushing strength (>20 MPa) and low attrition rate. Fixed bed experiments are carried out which reaffirm its reactivity. More than 99.75% of syngas is converted during the reduction stage. During the regeneration stage, hydrogen with an average purity of 99.8% is produced. 23 refs., 6 figs., 10 tabs.

  19. Molecular Dynamics Simulations of Surface Processes: Oxygen Recombination on Silica Surfaces at High Temperature

    DTIC Science & Technology

    2007-07-01

    size-scalable cluster approach with SixOy clusters of increasing size cleaved from the β- cristobalite unit cell. In this study the hybrid Hartree...values of the β- cristobalite cell and extending the Molecular Dynamics Simulations of Surface Processes: Oxygen Recombination on Silica Surfaces at... cristobalite surface is reported as a function of the distance of the N atom from the Si active atom. The dashed line shows the interaction

  20. Effect of shortening kraft pulping integrated with extended oxygen delignification on biorefinery process performance of eucalyptus.

    PubMed

    Li, Jing; Zhang, Chunyun; Hu, Huichao; Chai, Xin-Sheng

    2016-02-01

    The aim of this work was to study the impact of shortening kraft pulping (KP) process integrated with extended oxygen delignification (OD) on the biorefinery process performance of eucalyptus. Data showed that using kraft pulps with high kappa number could improve the delignification efficiency of OD, reduce hexenuronic acid formation in kraft pulps. Pulp viscosity for a target kappa number of ∼10 was comparable to that obtained from conventional KP and OD process. The energy and alkali consumption in the integrated biorefinery process could be optimized when using a KP pulp with kappa number of ∼27. The process could minimize the overall methanol formation, but greater amounts of carbonate and oxalate were formed. The information from this study will be helpful to the future implementation of short-time KP integrated with extended OD process in actual pulp mill applications for biorefinery, aiming at further improvement in the biorefinery effectiveness of hardwood. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Influence of the residual oxygen in the plasma immersion ion implantation (PI3) processing of materials

    NASA Astrophysics Data System (ADS)

    Ueda, M.; Silva, A. R.; Mello, Carina B.; Silva, G.; Reuther, H.; Oliveira, V. S.

    2011-12-01

    In this work, we investigated the effects of the contaminants present in the vacuum chamber of the PI3 system, in particular, the residual oxygen, which results in the formation of the oxide compounds on the surface and hence is responsible for the high implantation energies required to achieve reasonably thick treated layers. We used a mass spectrometer (RGA) with a quadruple filter to verify the composition of the residual vacuum and pressure of the elements present in the chamber. Initially we found a high proportion of residual oxygen in a vacuum with a pressure of 1 × 10 -3 Pa. Minimizing the residual oxygen percentage in about 80%, by efficient cleaning of the chamber walls and by improving the gas feeding process, we mitigated the formation of oxides during the PI3 process. Therefore we achieved a highly efficient PI3 processing obtaining implanted layers reaching about 50 nm, even in cases such as an aluminum alloy, where is very difficult to nitrogen implant at low energies. We performed nitrogen PI3 treatment of SS304 and Al7075 using pulses of only 3 kV and 15 × 10 -6 s at 1 kHz with an operating pressure of 1 Pa.

  2. Effects of dissolved oxygen on the biooxidation process of refractory gold ores.

    PubMed

    Sun, Li-Xin; Zhang, Xu; Tan, Wen-Song; Zhu, Ming-Long

    2012-11-01

    While multiple theories exist regarding the effect of dissolved oxygen (DO) on the biooxidation of minerals, few studies have been performed the cellular or molecular scale (e.g., genetics) and the mechanism remains unclear. In this paper, the effects of DO concentration on the biooxidation process of refractory sulfide gold ores by Acidithiobacillus ferrooxidans were investigated in the experimental stirred tank bioreactors (STRs). The results indicated that higher biooxidation and cell growth rates were correlated with higher DO concentration. The biooxidation process was restricted at 1.2 ppm DO due to oxygen limitation. Furthermore, the effects of DO on cellular and molecular scale were studied for the first time. The results demonstrated that the oxygen uptake rate (OUR), the Fe(2+) oxidation activity and the rus gene expression of A. ferrooxidans all increased with the DO concentration, which might be responsible for the increase of the biooxidation rates with the DO concentration. This study provides insight into the potential impact of molecular-level mechanisms of DO in the biooxidation process of minerals. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  3. Real-time observation of dynamic process of oxygen vacancy migration in cerium oxides under electric field

    SciTech Connect

    Li, Xiaomin; Qi, Kuo; Sun, Muhua; Huang, Qianming; Xu, Zhi E-mail: xdbai@iphy.ac.cn; Wang, Wenlong; Bai, Xuedong E-mail: xdbai@iphy.ac.cn

    2015-11-23

    The dynamic process of oxygen vacancy migration driven by the external electric field is directly observed at atomic scale in the cerium oxides (CeO{sub 2}) thin film by in-situ transmission electron microscopy method. When a bias voltage of a proper value is applied across the CeO{sub 2} film, the oxygen vacancies are formed near the interface of CeO{sub 2}/anode, followed by their migration along the direction of the external electric field. The structural modulation occurs in the [110] zone axis due to the ordering of oxygen vacancies. The migration of oxygen vacancies results in the reversible structural transformation, i.e., releasing and storing oxygen processes in CeO{sub 2}, which is of great significance for the ionic and electronic applications of the cerium oxides materials, such as oxygen pump, gas sensor, resistive random access memory, etc.

  4. Short-Term Molecular Acclimation Processes of Legume Nodules to Increased External Oxygen Concentration

    PubMed Central

    Avenhaus, Ulrike; Cabeza, Ricardo A.; Liese, Rebecca; Lingner, Annika; Dittert, Klaus; Salinas-Riester, Gabriela; Pommerenke, Claudia; Schulze, Joachim

    2016-01-01

    Nitrogenase is an oxygen labile enzyme. Microaerobic conditions within the infected zone of nodules are maintained primarily by an oxygen diffusion barrier (ODB) located in the nodule cortex. Flexibility of the ODB is important for the acclimation processes of nodules in response to changes in external oxygen concentration. The hypothesis of the present study was that there are additional molecular mechanisms involved. Nodule activity of Medicago truncatula plants were continuously monitored during a change from 21 to 25 or 30% oxygen around root nodules by measuring nodule H2 evolution. Within about 2 min of the increase in oxygen concentration, a steep decline in nitrogenase activity occurred. A quick recovery commenced about 8 min later. A qPCR-based analysis of the expression of genes for nitrogenase components showed a tendency toward upregulation during the recovery. The recovery resulted in a new constant activity after about 30 min, corresponding to approximately 90% of the pre-treatment level. An RNAseq-based comparative transcriptome profiling of nodules at that point in time revealed that genes for nodule-specific cysteine-rich (NCR) peptides, defensins, leghaemoglobin and chalcone and stilbene synthase were significantly upregulated when considered as a gene family. A gene for a nicotianamine synthase-like protein (Medtr1g084050) showed a strong increase in count number. The gene appears to be of importance for nodule functioning, as evidenced by its consistently high expression in nodules and a strong reaction to various environmental cues that influence nodule activity. A Tnt1-mutant that carries an insert in the coding sequence (cds) of that gene showed reduced nitrogen fixation and less efficient acclimation to an increased external oxygen concentration. It was concluded that sudden increases in oxygen concentration around nodules destroy nitrogenase, which is quickly counteracted by an increased neoformation of the enzyme. This reaction might be

  5. Short-Term Molecular Acclimation Processes of Legume Nodules to Increased External Oxygen Concentration.

    PubMed

    Avenhaus, Ulrike; Cabeza, Ricardo A; Liese, Rebecca; Lingner, Annika; Dittert, Klaus; Salinas-Riester, Gabriela; Pommerenke, Claudia; Schulze, Joachim

    2015-01-01

    Nitrogenase is an oxygen labile enzyme. Microaerobic conditions within the infected zone of nodules are maintained primarily by an oxygen diffusion barrier (ODB) located in the nodule cortex. Flexibility of the ODB is important for the acclimation processes of nodules in response to changes in external oxygen concentration. The hypothesis of the present study was that there are additional molecular mechanisms involved. Nodule activity of Medicago truncatula plants were continuously monitored during a change from 21 to 25 or 30% oxygen around root nodules by measuring nodule H2 evolution. Within about 2 min of the increase in oxygen concentration, a steep decline in nitrogenase activity occurred. A quick recovery commenced about 8 min later. A qPCR-based analysis of the expression of genes for nitrogenase components showed a tendency toward upregulation during the recovery. The recovery resulted in a new constant activity after about 30 min, corresponding to approximately 90% of the pre-treatment level. An RNAseq-based comparative transcriptome profiling of nodules at that point in time revealed that genes for nodule-specific cysteine-rich (NCR) peptides, defensins, leghaemoglobin and chalcone and stilbene synthase were significantly upregulated when considered as a gene family. A gene for a nicotianamine synthase-like protein (Medtr1g084050) showed a strong increase in count number. The gene appears to be of importance for nodule functioning, as evidenced by its consistently high expression in nodules and a strong reaction to various environmental cues that influence nodule activity. A Tnt1-mutant that carries an insert in the coding sequence (cds) of that gene showed reduced nitrogen fixation and less efficient acclimation to an increased external oxygen concentration. It was concluded that sudden increases in oxygen concentration around nodules destroy nitrogenase, which is quickly counteracted by an increased neoformation of the enzyme. This reaction might be

  6. A foundational methodology for determining system static complexity using notional lunar oxygen production processes

    NASA Astrophysics Data System (ADS)

    Long, Nicholas James

    This thesis serves to develop a preliminary foundational methodology for evaluating the static complexity of future lunar oxygen production systems when extensive information is not yet available about the various systems under consideration. Evaluating static complexity, as part of a overall system complexity analysis, is an important consideration in ultimately selecting a process to be used in a lunar base. When system complexity is higher, there is generally an overall increase in risk which could impact the safety of astronauts and the economic performance of the mission. To evaluate static complexity in lunar oxygen production, static complexity is simplified and defined into its essential components. First, three essential dimensions of static complexity are investigated, including interconnective complexity, strength of connections, and complexity in variety. Then a set of methods is developed upon which to separately evaluate each dimension. Q-connectivity analysis is proposed as a means to evaluate interconnective complexity and strength of connections. The law of requisite variety originating from cybernetic theory is suggested to interpret complexity in variety. Secondly, a means to aggregate the results of each analysis is proposed to create holistic measurement for static complexity using the Single Multi-Attribute Ranking Technique (SMART). Each method of static complexity analysis and the aggregation technique is demonstrated using notional data for four lunar oxygen production processes.

  7. Evaluation of oxygen transfer efficiency under process conditions using the dynamic off-gas method.

    PubMed

    Schuchardt, A; Libra, J A; Sahlmann, C; Wiesmann, U; Gnirss, R

    2007-05-01

    The off-gas method can be used to investigate standard oxygen transfer efficiencies under process conditions (alphaSOTE) over the operating life of an aeration system. A method to evaluate alphaSOTE is described in detail by US and German standards. The standards, however, do not describe how to evaluate dynamic changes in aSOTE over a day, which can be useful to uncover problems and unfavourable process conditions. Based on over three years experience gained in off-gas testing in Berlin wastewater treatment plants (WWTPs) under operating conditions, a method to evaluate and interpret the dynamic changes in oxygen transfer is presented. The application of the dynamic off-gas method brings important additional information, which can be used to increase operational efficiency of the aeration basin and to increase process reliability, with a relatively small increase in effort. This paper shows how to perform dynamic measurements under process conditions. Some results of such measurements under dynamic process conditions, performed in a Berlin WWTP, are discussed.

  8. Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

    NASA Astrophysics Data System (ADS)

    Thomsen, S.; Kanzow, T.; Colas, F.; Echevin, V.; Krahmann, G.; Engel, A.

    2016-08-01

    The Peruvian upwelling system encompasses the most intense and shallowest oxygen minimum zone (OMZ) in the ocean. This system shows pronounced submesoscale activity like filaments and fronts. We carried out glider-based observations off Peru during austral summer 2013 to investigate whether submesoscale frontal processes ventilate the Peruvian OMZ. We present observational evidence for the subduction of highly oxygenated surface water in a submesoscale cold filament. The subduction event ventilates the oxycline but does not reach OMZ core waters. In a regional submesoscale-permitting model we study the pathways of newly upwelled water. About 50% of upwelled virtual floats are subducted below the mixed layer within 5 days emphasizing a hitherto unrecognized importance of subduction for the ventilation of the Peruvian oxycline.

  9. CONTINUOUS PROCESS FOR PREPARING URANIUM HEXAFLUORIDE FROM URANIUM TETRAFLUORIDE AND OXYGEN

    DOEpatents

    Adams, J.B.; Bresee, J.C.; Ferris, L.M.

    1961-11-21

    A process for preparing UF/sub 6/ by reacting UF/sub 4/ and oxygen is described. The UF/sub 4/ and oxygen are continuously introduced into a fluidized bed of UO/sub 2/F/sub 2/ at a temperature of 600 to 900 deg C. The concentration of UF/sub 4/ in the bed is maintained below 25 weight per cent in order to avoid sintering and intermediate compound formation. By-product U0/sub 2/F/sub 2/ is continuously removed from the top of the bed recycled. In an alternative embodiment heat is supplied to the reaction bed by burning carbon monoxide in the bed. The product UF/sub 6/ is filtered to remove entrained particles and is recovered in cold traps and chemical traps. (AEC)

  10. Near infrared image processing to quantitate and visualize oxygen saturation during vascular occlusion.

    PubMed

    Jalil, B; Salvetti, O; Potì, L; Hartwig, V; Marinelli, M; L'Abbate, A

    2016-04-01

    The assessment of microcirculation spatial heterogeneity on the hand skin is the main objective of this work. Near-infrared spectroscopy based 2D imaging is a non-invasive technique for the assessment of tissue oxygenation. The haemoglobin oxygen saturation images were acquired by a dedicated camera (Kent Imaging) during baseline, ischaemia (brachial artery cuff occlusion) and reperfusion. Acquired images underwent a preliminary restoration process aimed at removing degradations occurring during signal capturing. Then, wavelet transform based multiscale analysis was applied to identify edges by detecting local maxima and minima across successive scales. Segmentation of test areas during different conditions was obtained by thresholding-based region growing approach. The method identifies the differences in microcirculatory control of blood flow in different regions of the hand skin. The obtained results demonstrate the potential use of NIRS images for the clinical evaluation of skin disease and microcirculatory dysfunction.

  11. Platinum Partitioning at Low Oxygen Fugacity: Implications for Core Formation Processes

    NASA Technical Reports Server (NTRS)

    Medard, E.; Martin, A. M.; Righter, K.; Lanziroti, A.; Newville, M.

    2016-01-01

    Highly siderophile elements (HSE = Au, Re, and the Pt-group elements) are tracers of silicate / metal interactions during planetary processes. Since most core-formation models involve some state of equilibrium between liquid silicate and liquid metal, understanding the partioning of highly siderophile elements (HSE) between silicate and metallic melts is a key issue for models of core / mantle equilibria and for core formation scenarios. However, partitioning models for HSE are still inaccurate due to the lack of sufficient experimental constraints to describe the variations of partitioning with key variable like temperature, pressure, and oxygen fugacity. In this abstract, we describe a self-consistent set of experiments aimed at determining the valence of platinum, one of the HSE, in silicate melts. This is a key information required to parameterize the evolution of platinum partitioning with oxygen fugacity.

  12. Investigation of Nebular Processes Through Oxygen Isotopic Analysis of Primitive Meteorite Materials

    NASA Technical Reports Server (NTRS)

    Leshin, Laurie

    2002-01-01

    As a direct result of support provided by this grant, precise and accurate determination of delta(18)O and delta(17)O in silicates (and other minerals) by ion microprobe (both IMS 6f and IMS 1270) are now being carried out in several laboratories, and these analyses, combined with application of laser fluorination techniques, have led to a proliferation of oxygen isotopic data in the past approx. 3 years. The applications of these techniques in cosmochemical research have been myriad, from understanding the most refractory objects in the nebula (CAIs) to the low temperature alteration processes on meteorite parent bodies. Here, we describe our progress in understanding the oxygen isotopic microdistributions in primitive meteorite materials, as directly supported by this Origins grant.

  13. Processing and Evaluation of Next Generation Oxygen Carrier Materials for Chemical Looping Combustion

    NASA Astrophysics Data System (ADS)

    Hamedi Rad, Mina

    This study follows two methods to achieve a modified CaMnO 3-delta structure with higher oxygen capacity and stability. The first method is replacement of manganese with iron as a cheaper alternative and the second method is size effect investigations of A-site dopants on CaMn 0.9Fe0.1O3-delta and its oxygen capacity and stability. Solid state reaction followed by mechanical extrusion is used as the preparation method. All synthesized perovskites are characterized by TGA and XRD analyses. The samples of highest oxygen capacity and stability are further characterized by SEM and BET analyses. Oxygen uncoupling behavior and reactivity of these samples are also examined using a fluidized bed reactor performing Chemical Looping Combustion. The temperature effect is also investigated during chemical looping process at temperatures of 800, 850, 900 and 950 °C. In the first method, since calcium could not be incorporated in the structure, strontium is used as the A-site cation. SrFeO3-delta has shown to be more stable than CaMnO3-delta. However, because of low oxygen capacity, it is doped on the A-site (La and Ba) and B-site (Al, Ti, Mn, Co) by 10 mol% (Sr0.9La0.1FeO3-delta, Sr0.9Ba0.1FeO3-delta, SrFe0.9Al 0.1O3-delta, SrFe0.9Ti0.1O3-delta , SrFe0.9Mn0.1O3-delta, SrFe 0.9Co0.1O3-delta). Results reveal that manganese doped structure (SrFe0.9Mn0.1O3-delta) has the highest oxygen capacity. Adding more manganese to the structure increases the oxygen capacity even further. The best iron-based structure has 30 mol% manganese, doped on the B-site, having 28% mass change in an inert atmosphere (SrFe0.7Mn0.3O3-delta, SFM73) and high stability. Results of conducted experiments in second method demonstrated that Strontium doped perovskite (Ca0.9Sr0.1Mn0.9Fe 0.1O3-delta, CS91MF91) is the best synthesized oxygen carrier among all synthesized manganese and iron-based perovskites. This material shows excellent oxygen uptake and release (1.78 wt. %) and high stability. The reactivity and

  14. An experimental research on the mixing process of supersonic oxygen-iodine parallel streams

    NASA Astrophysics Data System (ADS)

    Wang, Zengqiang; Sang, Fengting; Zhang, Yuelong; Hui, Xiaokang; Xu, Mingxiu; Zhang, Peng; Zhao, Weili; Fang, Benjie; Duo, Liping; Jin, Yuqi

    2014-12-01

    The O2(1Δ)/I2 mixing process is one of the most important steps in chemical oxygen-iodine laser (COIL). Based on the chemical fluorescence method (CFM), a diagnostic system was set up to image electronically excited fluorescent I2(B3П0) by means of a high speed camera. An optimized data analysis approach was proposed to analyze the mixing process of supersonic oxygen-iodine parallel streams, employing a set of qualitative and quantitative parameters and a proper percentage boundary threshold of the fluorescence zone. A slit nozzle bank with supersonic parallel streams and a trip tab set for enhancing the mixing process were designed and fabricated. With the diagnostic system and the data analysis approach, the performance of the trip tab set was examined and is demonstrated in this work. With the mixing enhancement, the fluorescence zone area was enlarged 3.75 times. We have studied the mixing process under different flow conditions and demonstrated the mixing properties with different iodine buffer gases, including N2, Ar, He and CO2. It was found that, among the four tested gases, Ar had the best penetration ability, whilst He showed the best free diffusion ability, and both of them could be well used as the buffer gas in our experiments. These experimental results can be useful for designing and optimizing COIL systems.

  15. Process for selection of oxygen-tolerant algal mutants that produce H{sub 2}

    SciTech Connect

    Ghirardi, M.L.; Seibert, M.

    1999-02-16

    A process for selection of oxygen-tolerant, H{sub 2}-producing algal mutant cells comprises: (a) growing algal cells photoautotrophically under fluorescent light to mid log phase; (b) inducing algal cells grown photoautotrophically under fluorescent light to mid log phase in step (a) anaerobically by (1) resuspending the cells in a buffer solution and making said suspension anaerobic with an inert gas and (2) incubating the suspension in the absence of light at ambient temperature; (c) treating the cells from step (b) with metronidazole, sodium azide, and added oxygen to controlled concentrations in the presence of white light; (d) washing off metronidazole and sodium azide to obtain final cell suspension; (e) plating said final cell suspension on a minimal medium and incubating in light at a temperature sufficient to enable colonies to appear; (f) counting the number of colonies to determine the percent of mutant survivors; and (g) testing survivors to identify oxygen-tolerant H{sub 2}-producing mutants. 5 figs.

  16. Process for selection of oxygen-tolerant algal mutants that produce H{sub 2}

    DOEpatents

    Ghirardi, M.L.; Seibert, M.

    1999-02-16

    A process for selection of oxygen-tolerant, H{sub 2}-producing algal mutant cells comprises: (a) growing algal cells photoautotrophically under fluorescent light to mid log phase; (b) inducing algal cells grown photoautotrophically under fluorescent light to mid log phase in step (a) anaerobically by (1) resuspending the cells in a buffer solution and making said suspension anaerobic with an inert gas and (2) incubating the suspension in the absence of light at ambient temperature; (c) treating the cells from step (b) with metronidazole, sodium azide, and added oxygen to controlled concentrations in the presence of white light; (d) washing off metronidazole and sodium azide to obtain final cell suspension; (e) plating said final cell suspension on a minimal medium and incubating in light at a temperature sufficient to enable colonies to appear; (f) counting the number of colonies to determine the percent of mutant survivors; and (g) testing survivors to identify oxygen-tolerant H{sub 2}-producing mutants. 5 figs.

  17. The impacts of physical processes on oxygen variations in the North Sea-Baltic Sea transition zone

    NASA Astrophysics Data System (ADS)

    Jonasson, L.; Wan, Z.; Hansen, J. H. S.; She, J.

    2011-07-01

    The bottom water of the North Sea-Baltic Sea transition zone suffers from seasonal hypoxia, usually during late summer and autumn. These hypoxic events are critical for the benthic ecosystems and the concentration of dissolved oxygen is an important measure of the water quality. However, to model the subsurface dissolved oxygen is a major challenge, especially in estuaries and coastal regions. In this study a simple oxygen consumption model is coupled to a 3-D hydrodynamical model in order to analyse oxygen variations in the transition zone. The benthic and pelagic consumption of oxygen is modelled as a function of water temperature and oxygen concentration. A quantitative assessment of the model demonstrates that the model is able to resolve both seasonal and interannual variations in dissolved oxygen. Results from several experimental simulations highlight the importance of physical processes in the regulation of dissolved oxygen. Advective oxygen transport and wind induced mixing are two key processes that control the extent of hypoxia in the transition zone.

  18. The impacts of physical processes on oxygen variations in the North Sea-Baltic Sea transition zone

    NASA Astrophysics Data System (ADS)

    Jonasson, L.; Hansen, J. L. S.; Wan, Z.; She, J.

    2012-01-01

    The bottom water of the North Sea-Baltic Sea transition zone suffers from seasonal hypoxia, usually during late summer and autumn. These hypoxic events are critical for the benthic ecosystems and the concentration of dissolved oxygen is an important measure of the water quality. However, to model the subsurface dissolved oxygen is a major challenge, especially in estuaries and coastal regions. In this study a simple oxygen consumption model is coupled to a 3-D hydrodynamical model in order to analyse oxygen variations in the transition zone. The benthic and pelagic consumption of oxygen is modelled as a function of water temperature and oxygen concentration. A quantitative assessment of the model demonstrates that the model is able to resolve both seasonal and interannual variations in dissolved oxygen. Results from several experimental simulations highlight the importance of physical processes in the regulation of dissolved oxygen. Advective oxygen transport and wind induced mixing are two key processes that control the extent of hypoxia in the transition zone.

  19. Kinetic Model of Decarburization and Denitrogenation in Vacuum Oxygen Decarburization Process for Ferritic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Xu, Yingtie; Chen, Zhaoping; Zhang, Ge

    2009-06-01

    The characteristics and classification of decarburization and denitrogenation in the vacuum vessel for stainless steel production are analyzed. Based on the analysis of movements of the liquid steel and bubbles, the kinetics of decarburization and denitrogenation in the vacuum oxygen decarburization (VOD) process has been studied. A kinetic model of decarburization and denitrogenation has been developed to simulate the VOD process, considering each reaction zone as oxygen blowing crater, bottom blowing plume, steel/slag interface, and plume eye. As a result, it is possible to quantify the contribution of each reaction zone in decarburization and denitrogenation rate at a different stage in the VOD process. Specific trials at a vacuum induction furnace were performed to refine stainless steel in vacuum carbon deoxidation (VCD) and VOD style, respectively. The trial results are in good agreement with the model calculation. Combining the trials and the model calculation and the influence of temperature control, critical carbon content selection on the terminal total [C] + [N] content can be discussed further to provide a reasonable proposal for high-quality ferritic stainless steel production.

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

    NASA Astrophysics Data System (ADS)

    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

  1. Plasma processing of ? in a hydrogen/oxygen radio-frequency discharge

    NASA Astrophysics Data System (ADS)

    Turcicová, H.; Perina, V.; Vacík, J.; Cervená, J.; Zemek, J.; Zelezný, V.; Arend, H.

    1998-05-01

    Monocrystalline 0022-3727/31/9/004/img10 was processed in a radio-frequency (27.12 MHz) discharge in hydrogen and subsequently in oxygen and the composition of the thus produced surface layers evaluated. The hydrogen plasma treatment caused a heavy blackening of the sample due to chemical reduction. At low 0022-3727/31/9/004/img11 pressures (0022-3727/31/9/004/img12 Torr) the niobate structure on the sample surface was completely destroyed; only niobium and its oxides remained on the surface. At higher pressures (0022-3727/31/9/004/img13 Torr) the niobate structure was preserved. Hydrogenation of the surface layer was found which persisted up to 5000022-3727/31/9/004/img14C. Subsequent treatment in an oxygen plasma under similar processing conditions brought about the restoration of the transparency of the sample. The following methods were used for the modified surface structure analysis: neutron depth profiling, Rutherford backscattering, x-ray photoelectron spectroscopy and VIS and IR spectrometry.

  2. Basic investigation into the production of oxygen in a solid electrolyte process

    NASA Technical Reports Server (NTRS)

    Richter, R.

    1981-01-01

    Mission analyses indicated that by extracting oxygen from the Martian atmosphere, which consists primarily of carbon dioxide, the launch mass of a spacecraft can be reduced by such an amount that samples from the planet can be returned to earth. The solid electrolyte process for producing O2 from CO2 was investigated. A model of the thermodynamic and electrochemical processes in the electrolyte cell was postulated, thereby establishing the parameters influencing the effectiveness and efficiency of an in situ O2 production system. The major operating parameters were investigated over a wide range of temperature and pressure. Operating limits imposed by the solid electrolyte material, 8% yttria stabilized zirconia, were determined as a function of the operating temperature.

  3. Cold plasma processing of local planetary ores for oxygen and metallurgically important metals

    NASA Technical Reports Server (NTRS)

    Lynch, D. C.; Bullard, D.; Ortega, R.

    1990-01-01

    The utilization of a cold plasma in chlorination processing is described. Essential equipment and instruments were received, the experimental apparatus assembled and tested, and preliminary experiments conducted. The results of the latter lend support to the original hypothesis: a cold plasma can both significantly enhance and bias chemical reactions. In two separate experiments, a cold plasma was used to reduce TiCl4 vapor and chlorinate ilmenite. The latter, reacted in an argon-chlorine plasma, yielded oxygen. The former experiment reveals that chlorine can be recovered as HCl vapor from metal chlorides in a hydrogen plasma. Furthermore, the success of the hydrogen experiments has lead to an analysis of the feasibility of direct hydrogen reduction of metal oxides in a cold plasma. That process would produce water vapor and numerous metal by-products.

  4. Gene regulatory and metabolic adaptation processes of Dinoroseobacter shibae DFL12T during oxygen depletion.

    PubMed

    Laass, Sebastian; Kleist, Sarah; Bill, Nelli; Drüppel, Katharina; Kossmehl, Sebastian; Wöhlbrand, Lars; Rabus, Ralf; Klein, Johannes; Rohde, Manfred; Bartsch, Annekathrin; Wittmann, Christoph; Schmidt-Hohagen, Kerstin; Tielen, Petra; Jahn, Dieter; Schomburg, Dietmar

    2014-05-09

    Metabolic flexibility is the key to the ecological success of the marine Roseobacter clade bacteria. We investigated the metabolic adaptation and the underlying changes in gene expression of Dinoroseobacter shibae DFL12(T) to anoxic life by a combination of metabolome, proteome, and transcriptome analyses. Time-resolved studies during continuous oxygen depletion were performed in a chemostat using nitrate as the terminal electron acceptor. Formation of the denitrification machinery was found enhanced on the transcriptional and proteome level, indicating that D. shibae DFL12(T) established nitrate respiration to compensate for the depletion of the electron acceptor oxygen. In parallel, arginine fermentation was induced. During the transition state, growth and ATP concentration were found to be reduced, as reflected by a decrease of A578 values and viable cell counts. In parallel, the central metabolism, including gluconeogenesis, protein biosynthesis, and purine/pyrimidine synthesis was found transiently reduced in agreement with the decreased demand for cellular building blocks. Surprisingly, an accumulation of poly-3-hydroxybutanoate was observed during prolonged incubation under anoxic conditions. One possible explanation is the storage of accumulated metabolites and the regeneration of NADP(+) from NADPH during poly-3-hydroxybutanoate synthesis (NADPH sink). Although D. shibae DFL12(T) was cultivated in the dark, biosynthesis of bacteriochlorophyll was increased, possibly to prepare for additional energy generation via aerobic anoxygenic photophosphorylation. Overall, oxygen depletion led to a metabolic crisis with partly blocked pathways and the accumulation of metabolites. In response, major energy-consuming processes were reduced until the alternative respiratory denitrification machinery was operative.

  5. Action of oxygen and sodium carbonate in the urea-SNCR process

    SciTech Connect

    Yang, Weijuan; Zhou, Junhu; Zhou, Zhijun; Chen, Zhenchao; Liu, Jianzhong; Cen, Kefa

    2009-09-15

    Experimental researches are focused on the effects of O{sub 2} concentration and sodium carbonate on Selective Non-Catalytic Reduction (SNCR) performance in a tube reactor, and plug flow reactor model and perfectly stirred reactor model in CHEMKIN are adopted to simulate the reactions processes. It is found that there is a conversion temperature point (CTP), on the two sides of which oxygen performs different effect. Below CTP, which is 1273 K in our experiments, higher NO reduction efficiency can be gained with higher oxygen concentration because more O{sub 2} results in more radicals to drive the reduction chain reactions by speeding up the reactions O{sub 2} + H = O + OH and H{sub 2}O + O = 2OH. At 1473 K without oxygen, 60% of NO reduction efficiency can be achieved and a 15 ppm Na{sub 2}CO{sub 3} addition improves it to 90%. In this case the reaction H{sub 2}O + H = OH + H{sub 2} becomes fast enough to provide the radical OH without the aid of O{sub 2} to produce NH{sub 2} which reduces NO. And H{sub 2} is the byproduct of this reaction. Na{sub 2}CO{sub 3} addition shifts the optimal temperature of SNCR 50 K towards lower temperature and more NO is removed in the temperature window. The reactions NaO + H{sub 2}O = NaOH + OH and NaOH + O{sub 2} = NaO{sub 2} + OH and NaOH + M = Na + M + OH offer new pathways to produce OH radical, which results in more OH and more NH{sub 2} to reduce NO. The promotion effect of Na{sub 2}CO{sub 3} is significant when temperature is lower or O{sub 2} concentration is lower, which means the radicals are insufficient. (author)

  6. Extraction processes for the production of aluminum, titanium, iron, magnesium, and oxygen and nonterrestrial sources

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Choudary, U. V.; Erstfeld, T. E.; Williams, R. J.; Chang, Y. A.

    1979-01-01

    The suitability of existing terrestrial extractive metallurgical processes for the production of Al, Ti, Fe, Mg, and O2 from nonterrestrial resources is examined from both thermodynamic and kinetic points of view. Carbochlorination of lunar anorthite concentrate in conjunction with Alcoa electrolysis process for Al; carbochlorination of lunar ilmenite concentrate followed by Ca reduction of TiO2; and subsequent reduction of Fe2O3 by H2 for Ti and Fe, respectively, are suggested. Silicothermic reduction of olivine concentrate was found to be attractive for the extraction of Mg becaue of the technological knowhow of the process. Aluminothermic reduction of olivine is the other possible alternative for the production of magnesium. The large quantities of carbon monoxide generated in the metal extraction processes can be used to recover carbon and oxygen by a combination of the following methods: (1) simple disproportionation of CO,(2) methanation of CO and electrolysis of H2O, and (3) solid-state electrolysis of gas mixtures containing CO, CO2, and H2O. The research needed for the adoption of earth-based extraction processes for lunar and asteroidal minerals is outlined.

  7. Extraction processes for the production of aluminum, titanium, iron, magnesium, and oxygen and nonterrestrial sources

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Choudary, U. V.; Erstfeld, T. E.; Williams, R. J.; Chang, Y. A.

    1979-01-01

    The suitability of existing terrestrial extractive metallurgical processes for the production of Al, Ti, Fe, Mg, and O2 from nonterrestrial resources is examined from both thermodynamic and kinetic points of view. Carbochlorination of lunar anorthite concentrate in conjunction with Alcoa electrolysis process for Al; carbochlorination of lunar ilmenite concentrate followed by Ca reduction of TiO2; and subsequent reduction of Fe2O3 by H2 for Ti and Fe, respectively, are suggested. Silicothermic reduction of olivine concentrate was found to be attractive for the extraction of Mg becaue of the technological knowhow of the process. Aluminothermic reduction of olivine is the other possible alternative for the production of magnesium. The large quantities of carbon monoxide generated in the metal extraction processes can be used to recover carbon and oxygen by a combination of the following methods: (1) simple disproportionation of CO,(2) methanation of CO and electrolysis of H2O, and (3) solid-state electrolysis of gas mixtures containing CO, CO2, and H2O. The research needed for the adoption of earth-based extraction processes for lunar and asteroidal minerals is outlined.

  8. The confines of triple oxygen isotope exponents in elemental and complex mass-dependent processes

    NASA Astrophysics Data System (ADS)

    Bao, Huiming; Cao, Xiaobin; Hayles, Justin A.

    2015-12-01

    Small differences in triple isotope relationships, or Δ17O in the case of oxygen, have been increasingly used to study a range of problems including hydrological cycles, stratosphere-troposphere exchange, biogeochemical pathways and fluxes, and the Moon's origin in the geochemical and cosmochemical communities. A Δ17O value depends on the triple isotope exponent θ of involved reaction steps. However, the probabilistic distribution of the intrinsic and apparent θ values has not been examined for elemental processes and for processes that are out of equilibrium or bearing reservoir-transport complexities. A lack of knowledge on the confines of θ may hamper our understanding of the subtle differences among mass-dependent processes and may result in mischaracterization of a set of mass-dependent processes as being in violation of mass-dependent rules. Here we advocate a reductionist approach and explore θ confines starting from kinetic isotope effects (KIEs) within the framework of transition state theory (TST). The advantage of our KIE approach is that any elemental or composite, equilibrium or non-equilibrium process can be reduced to a set of KIEs with corresponding θKIE. We establish that the KIE between a reactant and a transition state (TS) is intrinsic. Given a range of KIEs known for Earth processes involving oxygen, we use a Monte Carlo calculation method and a range of oxygen-bonded molecular masses to obtain a distribution of θKIE values and subsequently that of θeq. Next, complexities are examined by looking into expected effects due to reaction progress, unbalanced fluxes, and reference frame. Finally, compounded reservoir-transport effects are examined using two simple processes - Rayleigh Distillation (RD) and Fractional Distillation (FD). Our results show that the apparent θ values between two species or two states of the same evolving species have much broader confines than the commonly used "canonical" confines of 0.51-0.53, particularly

  9. Decoupling the influence of biological and physical processes on the dissolved oxygen in the Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Du, Jiabi; Shen, Jian

    2015-01-01

    is instructive and essential to decouple the effects of biological and physical processes on the dissolved oxygen condition, in order to understand their contribution to the interannual variability of hypoxia in Chesapeake Bay since the 1980s. A conceptual bottom DO budget model is applied, using the vertical exchange time scale (VET) to quantify the physical condition and net oxygen consumption rate to quantify biological activities. By combining observed DO data and modeled VET values along the main stem of the Chesapeake Bay, the monthly net bottom DO consumption rate was estimated for 1985-2012. The DO budget model results show that the interannual variations of physical conditions accounts for 88.8% of the interannual variations of observed DO. The high similarity between the VET spatial pattern and the observed DO suggests that physical processes play a key role in regulating the DO condition. Model results also show that long-term VET has a slight increase in summer, but no statistically significant trend is found. Correlations among southerly wind strength, North Atlantic Oscillation index, and VET demonstrate that the physical condition in the Chesapeake Bay is highly controlled by the large-scale climate variation. The relationship is most significant during the summer, when the southerly wind dominates throughout the Chesapeake Bay. The seasonal pattern of the averaged net bottom DO consumption rate (B'20) along the main stem coincides with that of the chlorophyll-a concentration. A significant correlation between nutrient loading and B'20 suggests that the biological processes in April-May are most sensitive to the nutrient loading.

  10. Identification of sources and production processes of bottled waters by stable hydrogen and oxygen isotope ratios.

    PubMed

    Brencic, Mihael; Vreca, Polona

    2006-01-01

    Bottled water is a food product that considerably depends on the environment from which it originates, not only at the place where it is produced, but predominantly on the conditions in the recharge area of the wells captured for bottling. According to their source and the bottling process, bottled waters can be divided into natural and artificially sparkling waters, still and flavoured waters. These waters originate from various parts of the hydrological cycle and their natural origin is reflected in their hydrogen and oxygen stable isotopic compositions (delta(2)H and delta(18)O). A total of 58 domestic and foreign brands and 16 replicates of bottled waters, randomly collected on the Slovene market in September 2004, were analysed for delta(2)H and delta(18)O. The isotopic composition varied between -83 per thousand and -46 per thousand with an average of -66 per thousand for hydrogen, and between -11.9 per thousand and -7.5 per thousand with an average of -9.6 per thousand for oxygen. This investigation helped (1) to determine and test the classification of bottled waters, (2) to determine the natural origin of bottled water, and (3) to indicate differences between the natural and production processes. The production process may influence the isotopic composition of flavoured waters and artificially sparkling waters. No such modification was observed for still and natural sparkling waters. The methods applied, together with hydrological knowledge, can be used for the authentication of bottled waters for regulatory and consumer control applications. Copyright (c) 2006 John Wiley & Sons, Ltd.

  11. Simulation of Fluid Flow and Oscillation of the Argon Oxygen Decarburization (AOD) Process

    NASA Astrophysics Data System (ADS)

    Odenthal, Hans-Juergen; Thiedemann, Uwe; Falkenreck, Udo; Schlueter, Jochen

    2010-04-01

    The oscillation of argon oxygen decarburization (AOD) converters is flow related and depends on the process parameters ( e.g., vessel geometry, melt fill height, process gas type and blowing rate, vessel tilting angle, as well as geometry, number, and arrangement of the side-wall nozzles). For a 120-ton AOD converter with seven submerged side-wall nozzles, plant tests, physical simulations on a 1:4 scale water model, and computational fluid dynamics simulations have been done. The investigations show that the penetration depth of an inert gas jet into the melt does not exceed approximately 0.4 m. The plumes are located close to the nozzle-side converter wall and induce a large-scale primary vortex as well as intensive surface movements; both are responsible for the oscillation. Several process mechanisms were investigated. The oscillation is highest in the last stage of the dynamic blow and is still high during the reduction stage. As the amount of inert gas increases, the vibration level also increases. Inert gas has a greater influence on the oscillation than oxygen. Tilting the converter around 8 deg clearly leads to more intensive oscillations. Increasing the blowing rate increases the forces and torques acting on the vessel, whereas the oscillation frequency remains nearly constant. A varying fill level does not influence the vibration level the same way as the blowing rate. The operational test shows, for example, that the maximum torque does not depend on the heat size when the latter varies between -8 pct and +21 pct of the nominal heat size. The water model test shows decreasing forces and torques with a rising fill level.

  12. Variation in oxygen isotope ratio of dissolved orthophosphate induced by uptake process in natural coral holobionts

    NASA Astrophysics Data System (ADS)

    Ferrera, Charissa M.; Miyajima, Toshihiro; Watanabe, Atsushi; Umezawa, Yu; Morimoto, Naoko; San Diego-McGlone, Maria Lourdes; Nadaoka, Kazuo

    2016-06-01

    A model incubation experiment using natural zooxanthellate corals was conducted to evaluate the influence of phosphate uptake by coral holobionts on oxygen isotope ratio of dissolved PO4 3- (δ18Op). Live coral samples of Acropora digitifera, Porites cylindrica, and Heliopora coerulea were collected from coral reefs around Ishigaki Island (Okinawa, Japan) and Bolinao (northern Luzon, Philippines) and incubated for 3-5 d after acclimatization under natural light conditions with elevated concentrations of PO4 3-. Phosphate uptake by corals behaved linearly with incubation time, with uptake rate depending on temperature. δ18Op usually increased with time toward the equilibrium value with respect to oxygen isotope exchange with ambient seawater, but sometimes became higher than equilibrium value at the end of incubation. The magnitude of the isotope effect associated with uptake depended on coral species; the greatest effect was in A. digitifera and the smallest in H. coerulea. However, it varied even within samples of a single coral species, which suggests multiple uptake processes with different isotope effects operating simultaneously with varying relative contributions in the coral holobionts used. In natural environments where concentrations of PO4 3- are much lower than those used during incubation, PO4 3- is presumably turned over much faster and the δ18Op easily altered by corals and other major primary producers. This should be taken into consideration when using δ18Op as an indicator of external PO4 3- sources in coastal ecosystems.

  13. Multi-pollutant treatment of crystalline cellulosic effluent: Function of dissolved oxygen on process control.

    PubMed

    Shanthi Sravan, J; Naresh Kumar, A; Venkata Mohan, S

    2016-10-01

    Treatment of crystalline cellulose based wastewater was carried out in periodic discontinuous batch reactor (PDBR). Specific influence of dissolved oxygen on treatment of crystalline cellulosic (CC) wastewater was evaluated in three different microenvironments such as aerobic, anoxic and anaerobic. PDBR-aerobic biosystem documented relatively higher substrate degradation [2.63kgCOD/m(3)-day (92%)] in comparison to PDBR-anoxic [2.12kgCOD/m(3)-day (71%)] and PDBR-anaerobic [1.81kgCOD/m(3)-day (63%)], which is in accordance with the observed DO levels. Similarly, multipollutants viz., phosphates and nitrates removal was observed to be higher in aerobic followed by anoxic and anaerobic operations. Higher nitrate removal in aerobic operation might be attributed to the efficient denitrification carried out by the biocatalyst, which utilizes both nitrates and oxygen as oxidizing agents. Multiscan spectral profiles depicted reduction in color intensity in all three microenvironments that correlated with the substrate degradation observed. Despite the high organic load, PDBR functioned well without exhibiting process inhibition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. The structural features of hemicelluloses dissolved out at different cooking stages of active oxygen cooking process.

    PubMed

    Shi, Jianbin; Yang, Qiulin; Lin, Lu

    2014-04-15

    This work described the morphologic changes of corn stalk and the structural characterization of its hemicelluloses dissolved in yellow liquor at different cooking stages. The results showed that active oxygen cooking process was an efficient method to depolymerize the corn stalk into cellulose, hemicelluloses, and lignin as a pretreatment of biomass conversion. This cooking process can also be divided into three phases: bulk delignification, extended delignification, and residual delignification. During the heating-up period 57.67% of hemicelluloses and 62.31% of lignin were removed from the raw material. However, only 15% of hemicelluloses and 23.21% of lignin were removed during at temperature' period. The hemicelluloses from the corn stalk and yellow liquor were composed of (1→4)-β-D-xylopyranose backbones substituted with α-l-arabinofuranosyl, 4-O-methyl-α-D-glucuronic acid, and some methoxyl residues. The backbones of hemicelluloses were gradually cleaved during the cooking process. The acetyl groups substituted with xylopyranosyl residues were completely cleaved during the cooking process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Processes controlling mid-water column oxygen minima over the Texas-Louisiana shelf

    NASA Astrophysics Data System (ADS)

    Zhang, Wenxia; Hetland, Robert D.; DiMarco, Steven F.; Fennel, Katja

    2015-04-01

    We investigate distributions of dissolved oxygen over the Texas-Louisiana shelf using spatially highly resolved observations in combination with a regional circulation model with simple oxygen dynamics. The observations were collected using a towed, undulating CTD during the Mechanisms Controlling Hypoxia (MCH) program. Mid-water oxygen minimum layers (dissolved oxygen lower than 3.2 mL L-1) were detected in many transects. These oxygen minimum layers are connected with the bottom boundary layer and follow the pycnocline seaward as a tongue of low oxygen into the mid-water column. T-S diagrams highlighting the low oxygen minima in both observations and simulations imply direct connections between low-oxygen bottom water and the oxygen minimum layer. The dynamics of these oxygen minimum layers in the mid-water column are examined using a three-dimensional hydrodynamic model, based on the Regional Ocean Modeling System (ROMS). Convergence within the bottom boundary layer relative to density surfaces is calculated, results show that there is a convergence in the bottom boundary layer at the location where the pycnocline intersects the bottom. Buoyancy advection forced by bottom Ekman transport creates this convergent flow, and the corresponding low-oxygen intrusion. Similar intrusions of near-bottom water into the pycnocline are observed in other regions. The presence of hypoxia within the bottom boundary layer in the northern Gulf of Mexico creates a unique situation in which these intrusions are also associated with low dissolved oxygen.

  16. Triple oxygen isotope data characterize oxidation processes that produce sulfate on Earth (and Mars?)

    NASA Astrophysics Data System (ADS)

    Christensen, J.; Kohl, I.; Coleman, M. L.

    2011-12-01

    The Rio Tinto, a river in southwest Spain, has a long history of acid, iron and sulfate rich water resulting primarily from the oxidation of pyrite (ferrous iron sulfide). Its geochemistry and extremophile microbiology make it an exciting and ideal mars-analogue research site, as relatively recent discoveries have shown Mars to be rich in sulfates believed to have formed in an acidic environment. Current models for the oxidation pathways of pyrite sulfur to sulfate, and the microbial influences on those pathways are incomplete. Traditionally, studies have only focused on d18O as a tracer for the oxygen sources in sulfate and determination of the oxidation pathways. The d18O method has always been fraught with uncertainty due to isotope fractionation during oxygen incorporation from the two dominant sources, atmospheric oxygen and water. A relatively new method utilizing 17O measures the relationship between d17O/d18O. The average relationship has been defined as the Terrestrial Fractionation Line, with a slope of 0.52. Deviations from this relationship are represented as Cap delta 17O, the difference of delta 17O from the expected value. Cap17O values are useful because they depend only on the relationship between d17O/d18O, which remains constant during mass dependent fractionation. During O2 generation from solid BaSO4, some fractionation can occur due to incomplete oxygen yield. This can produce uncertainties in d17O and d18O, but Cap17O is dependent only on the d17O/d18O ratio and is therefore not affected. The relationship mentioned above between d17O/d18O (slope=0.52) is an average for terrestrial materials and it is becoming increasingly clear that process specific slopes can be defined. This offers an exciting opportunity to characterize potential biomarkers on Mars. If a biologically specific slope could be determined, then its signature will be preserved through subsequent mass dependent fractionation processes. Our approach is to use Río Tinto field and

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

    SciTech Connect

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

    1989-10-03

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

  18. Nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Mashifane, Thulwaneng; Waldron, Howard; Vichi, Marcello

    2016-04-01

    Understanding nitrite dynamics in the Benguela oxygen minimum zone (OMZ) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in some OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations occur below the detection limit in some regions. Nitrite concentrations are key to understanding dominant nitrogen loss mechanisms through modeling studies in the Benguela OMZ. The coupled physical-biogeochemical model for eastern boundary upwelling systems (BioEBUS) using the Southern Africa experiment (SAfE) nested configuration is applied in the Benguela to study nitrite dynamics. Model results show nitrite maxima associated with the Angola-Benguela front region. The maxima are linked to poleward nutrient rich, oxygen-depleted south Atlantic central water (SACW) from the Angola gyre which favour denitrification on the shelf during summer to autumn. Ventilation of the shelf during winter to spring by the equatorward well-aerated eastern south Atlantic central water (ESACW) results in depleted nitrite concentrations. In addition to local circulation, Hovmuller analyses suggest that both primary and secondary nitrite maxima are driven by shelf biogeochemical processes and offshore advection. Vertical depth profiles show nitrite maxima at 17°S and depletion at 23°S attributed to denitrification and anammox, respectively. Model results suggest nitrogen in the Benguela OMZ is lost to anammox, denitrification and offshore advection, with denitrification as the dominant loss mechanism rather than anammox as previously documented. These results are key to understanding feedback processes from nitrogen loss in the Benguela OMZ and its impact on related biogeochemical cycles.

  19. Neutrophil NET formation is regulated from the inside by myeloperoxidase-processed reactive oxygen species.

    PubMed

    Björnsdottir, Halla; Welin, Amanda; Michaëlsson, Erik; Osla, Veronica; Berg, Stefan; Christenson, Karin; Sundqvist, Martina; Dahlgren, Claes; Karlsson, Anna; Bylund, Johan

    2015-12-01

    Neutrophil extracellular traps (NETs) are mesh-like DNA fibers clad with intracellular proteins that are cast out from neutrophils in response to certain stimuli. The process is thought to depend on reactive oxygen species (ROS) generated by the phagocyte NADPH-oxidase and the ROS-modulating granule enzyme myeloperoxidase (MPO), but when, how, and where these factors contribute is so far uncertain. The neutrophil NADPH-oxidase can be activated at different cellular sites and ROS may be produced and processed by MPO within intracellular granules, even in situations where a phagosome is not formed, e.g., upon stimulation with phorbol myristate acetate (PMA). We investigated the subcellular location of ROS production and processing by MPO in the context of PMA-induced NET formation. Complete neutralization of extracellular ROS was not sufficient to block NET formation triggered by PMA, indicating that intragranular ROS are critical for NETosis. Employing a set of novel MPO-inhibitors, inhibition of NET formation correlated with inhibition of intragranular MPO activity. Also, extracellular addition of MPO was not sufficient to rescue NET formation in completely MPO-deficient neutrophils and specific neutralization by luminol of MPO-processed ROS within intracellular granules led to a complete block of PMA-triggered NET formation. We show for the first time that inhibition of intragranular MPO activity, or neutralization of intragranular MPO-processed ROS by luminol effectively block NET formation. Our data demonstrate that ROS must be formed and processed by MPO in order to trigger NET formation, and that these events have to occur within intracellular granules. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

    2014-01-07

    A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

  1. Experimental evaluation of the ignition process of carbon monoxide and oxygen in a rocket engine

    NASA Technical Reports Server (NTRS)

    Linne, Diane L.

    1996-01-01

    Carbon monoxide and oxygen ignition boundaries were determined in a spark torch igniter as a function of propellant inlet temperatures. The oxygen temperature was varied from ambient to -258 F, and the carbon monoxide temperature was varied from ambient to -241 F. With the oxygen and carbon monoxide at -253 F and -219 F, respectively, they successfully ignited between mixture ratios of 2.42 and 3.10. Analysis of the results indicated that the lower ignition boundary was more sensitive to oxygen temperature than to carbon monoxide temperature. Another series of tests was performed in a small simulated rocket engine with oxygen at -197 F and carbon monoxide at -193 F. An oxygen/hydrogen flame was used to initiate combustion of the oxygen and carbon monoxide. Tests performed at the optimum operating mixture ratio of 0.55 obtained steady-state combustion in every test.

  2. Improved vitamin B(12) production by step-wise reduction of oxygen uptake rate under dissolved oxygen limiting level during fermentation process.

    PubMed

    Wang, Ze-Jian; Wang, Hui-Yuan; Li, Yong-Liang; Chu, Ju; Huang, Ming-Zhi; Zhuang, Ying-Ping; Zhang, Si-Liang

    2010-04-01

    Effects of different oxygen transfer rates (OTR) on the cell growth and vitamin B(12) biosynthesis of Pseudomonas denitrificans were first investigated under dissolved oxygen limiting conditions. The results demonstrated that high OTR accelerated cell growth and initial vitamin B(12) biosynthesis rate, while lower OTR was critical for higher productivity in the late fermentation process. The oxygen uptake rates (OUR) corresponded well with OTR. Based on the metabolic intermediate analysis, a step-wise OUR control strategy was proposed. The strategy was successfully implemented in scale-up to an industrial fermenter (120,000 l). A stable maximum vitamin B(12) production of 208 + or - 2.5 mg/l was achieved, which was increased by 17.3% compared with the control. Furthermore, the glucose consumption coefficient to vitamin B(12) was 34.4% lower than that of the control. An efficient and economical fermentation process based on OUR criterion was established for industrial vitamin B(12) fermentation by P. denitrificans. Copyright 2009. Published by Elsevier Ltd.

  3. Magmatic differentiation processes at Merapi Volcano: inclusion petrology and oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Troll, Valentin R.; Deegan, Frances M.; Jolis, Ester M.; Harris, Chris; Chadwick, Jane P.; Gertisser, Ralf; Schwarzkopf, Lothar M.; Borisova, Anastassia Y.; Bindeman, Ilya N.; Sumarti, Sri; Preece, Katie

    2013-07-01

    Indonesian volcano Merapi is one of the most hazardous volcanoes on the planet and is characterised by periods of active dome growth and intermittent explosive events. Merapi currently degasses continuously through high temperature fumaroles and erupts basaltic-andesite dome lavas and associated block-and-ash-flows that carry a large range of magmatic, coarsely crystalline plutonic, and meta-sedimentary inclusions. These inclusions are useful in order to evaluate magmatic processes that act within Merapi's plumbing system, and to help an assessment of which phenomena could trigger explosive eruptions. With the aid of petrological, textural, and oxygen isotope analysis we record a range of processes during crustal magma storage and transport, including mafic recharge, magma mixing, crystal fractionation, and country rock assimilation. Notably, abundant calc-silicate inclusions (true xenoliths) and elevated δ18O values in feldspar phenocrysts from 1994, 1998, 2006, and 2010 Merapi lavas suggest addition of limestone and calc-silicate materials to the Merapi magmas. Together with high δ13C values in fumarole gas, crustal additions to mantle and slab-derived magma and volatile sources are likely a steady state process at Merapi. This late crustal input could well represent an eruption trigger due to sudden over-pressurisation of the shallowest parts of the magma storage system independently of magmatic recharge and crystal fractionation. Limited seismic precursors may be associated with this type of eruption trigger, offering a potential explanation for the sometimes erratic behaviour of Merapi during volcanic crises.

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

    NASA Astrophysics Data System (ADS)

    Ward, B. B.

    2014-12-01

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

  5. Mechanism of the cathodic process coupled to the oxidation of iron monosulfide by dissolved oxygen.

    PubMed

    Duinea, Mădălina I; Costas, Andreea; Baibarac, Mihaela; Chiriță, Paul

    2016-04-01

    This study investigated the mechanism of iron monosulfide (FeS) oxidation by dissolved oxygen (O2(aq)). Synthetic FeS was reacted with O2(aq) for 6days and at 25°C. We have characterized the initial and reacted FeS surface using Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM/EDX) analysis, Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). It was found that during the aqueous oxidation of FeS new solid phases (disulfide, polysulfide, elemental sulfur, ferric oxyhydroxides and Fe3O4) develop on the mineral surface. The results of potentiodynamic polarization experiments show that after 2days of FeS electrode immersion in oxygen bearing solution (OBS) at initial pH 5.1 and 25°C the modulus of cathodic Tafel slopes dramatically decreases, from 393mV/dec to 86mV/dec. This decrease is ascribed to the change of the mechanism of electron transfer from cathodic sites to O2 (mechanism of cathodic process). The oxidation current densities (jox) indicate that mineral oxidative dissolution is not inhibited by pH increase up to 6.7. Another conclusion, which emerges from the analysis of jox, is that the dissolved Fe(3+) does not intermediate the aqueous oxidation of FeS. The results of electrochemical impedance spectroscopy (EIS) show that after 2days of contact between electrode and OBS the properties of FeS/water interface change. From the analysis of the EIS, FTIR spectroscopy, Raman spectroscopy and SEM/EDX data we can conclude that the change of FeS/water interface properties accompanies the formation of new solid phases on the mineral surface. The new characteristics of the surface layer and FeS/water interface do not cause the inhibition of mineral oxidation.

  6. Interconnection of reactive oxygen species chemistry across the interfaces of atmospheric, environmental, and biological processes.

    PubMed

    Anglada, Josep M; Martins-Costa, Marilia; Francisco, Joseph S; Ruiz-López, Manuel F

    2015-03-17

    Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in

  7. Hydrogen and oxygen plasma enhancement in the Cu electrodeposition and consolidation processes on BDD electrode applied to nitrate reduction

    NASA Astrophysics Data System (ADS)

    Couto, A. B.; Santos, L. C. D.; Matsushima, J. T.; Baldan, M. R.; Ferreira, N. G.

    2011-09-01

    Copper nanoparticle electrodeposition and consolidation processes were studied on boron doped diamond (BDD) electrode submitted to hydrogen and oxygen plasma treatments. The modified BDD films were applied as electrodes for nitrate electroreduction. The results showed that both treatments have a strong influence on the copper deposition and dissolution processes. For BDD treated with hydrogen plasma the copper electrodeposit was homogeneous with high particle density. This behavior was attributed to the BDD surface hydrogenation that improved its conductivity. On the other hand, the treatment with oxygen plasma was important for the copper nanoparticle consolidation on BDD surface, confirmed by the result's reproducibility for nitrate reduction. This performance may be associated with the formation of oxygen groups that can act as anchor points for Cu-clusters, enhancing the interfacial adhesion between diamond and the metal coating. The best electrochemical nitrate reduction response was obtained in acid media, where occurred the separation of the nitrate reduction process and the water reduction reaction.

  8. Two-level multivariable control system of dissolved oxygen tracking and aeration system for activated sludge processes.

    PubMed

    Piotrowski, Robert

    2015-01-01

    The problem of tracking dissolved oxygen is one of the most complex and fundamental issues related to biological processes. The dissolved oxygen level in aerobic tanks has a significant influence on the behavior and activity of microorganisms. Aerated tanks are supplied with air from an aeration system (blowers, pipes, throttling valves, and diffusers). It is a complex, dynamic system governed by nonlinear hybrid dynamics. Control of the aeration system is also difficult in terms of control of the dissolved oxygen. In this article, a two-level multivariable control system for tracking dissolved oxygen and controlling an aeration system is designed. A nonlinear model predictive control algorithm was applied to design controllers for each level. This overall hierarchical control system was validated by simulation based on real data records provided by a water resource recovery facility located in Kartuzy, Northern Poland. The effect of control system parameters and disturbances was also investigated.

  9. [Effect of dissolved oxygen on microbial community in simultaneous removal of carbon, nitrogen and sulfur process].

    PubMed

    Yu, Hao; Chen, Chuan; Zhang, Li; Wang, Ai-Jie

    2013-06-01

    In order to investigate the effect of dissolved oxygen (DO) on microbial community in simultaneous removal of carbon, nitrogen and sulfur process and reveal the mechanism of high elemental sulfur conversion rate under aerobic condition, GeoChip was employed to characterize the structure of microbial community. The results indicated that the microbial community structure significantly changed with different aerobic conditions (P < 0.001). Diversity indices of microbial community increased at relatively high DO level. However, denitrifiers were greatly inhibited at this level due to the high sensitivity to DO. There was no significant change detected in the abundance of sulfate-reducing bacteria (SRB) with the changing DO. The relative abundance of sox gene showed significant difference between aeration rate of 20 mL x min(-1) and aeration rate of 0 mL x min(-1), which might suggest that the activity of sulfur-oxidizing bacteria (SOB) was obviously improved by DO. Moreover, cluster analysis of sox gene confirmed this suggestion, with higher signal intensity found in numbers of probes derived from SOB under such aerobic conditions. Overall, the results revealed a positive effect of micro-aerobic conditions on the simultaneous removal of carbon, nitrogen and sulfur process.

  10. Mus308 Processes Oxygen and Nitrogen Ethylation DNA Damage in Germ Cells of Drosophila

    PubMed Central

    Díaz-Valdés, Nancy; Comendador, Miguel A.; Sierra, L. María

    2010-01-01

    The D. melanogaster mus308 gene, highly conserved among higher eukaryotes, is implicated in the repair of cross-links and of O-ethylpyrimidine DNA damage, working in a DNA damage tolerance mechanism. However, despite its relevance, its possible role on the processing of different DNA ethylation damages is not clear. To obtain data on mutation frequency and on mutation spectra in mus308 deficient (mus308−) conditions, the ethylating agent diethyl sulfate (DES) was analysed in postmeiotic male germ cells. These data were compared with those corresponding to mus308 efficient conditions. Our results indicate that Mus308 is necessary for the processing of oxygen and N-ethylation damage, for the survival of fertilized eggs depending on the level of induced DNA damage, and for an influence of the DNA damage neighbouring sequence. These results support the role of mus308 in a tolerance mechanism linked to a translesion synthesis pathway and also to the alternative end-joinig system. PMID:20936147

  11. Modelling nitrite dynamics and associated feedback processes in the Benguela oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Mashifane, T. B.; Vichi, M.; Waldron, H. N.; Machu, E.; Garçonc, V.

    2016-08-01

    Understanding nitrite dynamics in oxygen minimum zones (OMZs) is a challenge as it represents an intermediary nitrogen species with a short turnover time. Nitrite is also reduced to nitrogen in OMZs, preventing its accumulation. This creates difficulties in detecting nitrite with colorimetric methods as concentrations may occur below detection limits in some regions. Nitrite concentrations are key to understanding intermediate nitrogen processes and their implication for nitrogen loss in OMZs. A coupled physical-biogeochemical model is applied in the Benguela OMZ to study nitrite dynamics and its associated feedback processes. Simulated results show occurrence of primary and secondary nitrite maxima in the Benguela shelf waters. The primary nitrite maxima in the Benguela are attributed to nitrification and nitrate assimilation as they occur in association with the nitracline. Secondary nitrite maxima accumulate in the Angola-Benguela Front (ABF) OMZ and are attributed to denitrification. The secondary nitrite maxima are consumed by anaerobic ammonium oxidation (anammox) off Walvis Bay. Nitrite maxima are restricted to the shelf off Walvis Bay and advected offshore in the ABF region. Interchanges between the poleward South Atlantic Central Water (SACW) and the equatorward, well-aerated Eastern South Atlantic Central Water (ESACW) drive the seasonality of nitrogen processes in the Benguela. Subsequent nitrite reduction in the Benguela OMZ leads to nitrous oxide production, with high concentrations occurring in the ABF region as a result of nitrification and denitrification. Off Walvis Bay, nitrous oxide production is low since nitrite is consumed by anammox. Nitrous oxide production occurs in thermocline, intermediate and deeper water masses in the ABF region. High N fluxes in the Benguela are attributed to nitrification as compared to anammox and denitrification. Results from this study demonstrate the role of intermediate nitrogen species in nitrogen feedback

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

    PubMed

    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 (<0.7 mg/L). At dosages ≥4.6 mg L(-1) h(-1), an O3/H2O2 mass ratio of 3.4-3.8, and initial COD <20 mg/L, a simple first order decay was indicated for both single-passed treated wastewater and recycled mineral 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.

  13. Oxygen microprofile in the prepared sediments and its implication for the sediment oxygen consuming process in a heavily polluted river of China.

    PubMed

    Wang, Chao; Zhai, Wanying; Shan, Baoqing

    2016-05-01

    Dissolved oxygen (DO) microprofiles of prepared sediments from 24 sampling sites in the Fuyang River were measured using a gold amalgam microelectrode in this study. The measured microprofiles can be divided into four types. In type I profiles, DO kept constant in the overlying water and decreased smoothly in the pore water; in type II profile, DO showed fluctuation in the pore water; in type III profiles, DO showed peak in the SWI; in type IV profiles, DO decreased obviously in the overlying water. Type I profiles indicated the absence of benthic organisms and thus the degradation of the sediment habitat. Type II and III profiles indicated the activity of benthic animal and epipelic algae, which is common in the healthy aquatic sediment. Type IV profiles indicated that the excessive accumulation of pollutants in the sediment and thus the serious sediment pollution. There are nine sites showing type I profile, three sites showing type II profile, nine sites showing type III profile, and three sites showing type IV profile in the Fuyang River. The dominance of type I and appearance of type IV indicated that sediment oxygen consumption processes in the Fuyang River were strongly influenced by the sediment pollutants release and the vanish of benthic organisms. The pharmacy, metallurgy, and curriery industries may contribute to the sediment deterioration and thus to the occurrence of type I and type IV oxygen profiles in the Fuyang River.

  14. Energy balance of the closed oxygen cycle and processes causing thermal runaway in valve-regulated lead/acid batteries

    NASA Astrophysics Data System (ADS)

    Pavlov, D.

    A model for the reactions involved in the closed oxygen cycle in valve-regulated lead/acid batteries and the associated energy transformations is proposed. When electric current flows through the closed oxygen cycle, a certain amount of electric energy is converted via electrochemical processes into chemical energy, i.e. the products obtained may interact spontaneously as a result of which the system returns to its initial state. During these spontaneous reactions, the chemical energy is converted into heat. Depending on the type of the reactions involved in oxygen reduction on the negative plate, the closed oxygen cycle may proceed in two different electrochemical systems: (i) oxygen is reduced through electrochemical reactions yielding the electrochemical system PbO 2//H 2OO/O 2///O 2//H 2OO/Pb, and (ii) oxygen is reduced through chemical reactions forming the electrochemical system PbO 2//H 2OO/O 2///PbSO 4//Pb. The energy introduced into the system for activation of the closed oxygen cycle is different for the two electrochemical systems. The quantity of this energy is calculated in the present work using thermodynamic data. During the closed oxygen cycle the electric energy is transformed into chemical energy which, in turn, is converted into heat. Part of this heat causes the cell temperature to increase and another part dissipates into the surrounding air. The amount of the former heat depends on the heat capacity of the battery and is influenced most strongly by the quantity of the electrolyte. It has been established that the rate of oxygen evolution on the positive plate depends strongly on the temperature. When the heat exchange between the battery and the surrounding medium is poor, the reactions of the closed oxygen cycle may enter (through the heat and oxygen flows between the positive and the negative plates) into self-accelerating interrelations, which may lead to thermal runaway. To avoid this, an adequate heat exchange should be maintained between

  15. What processes control the oxygen isotopes of soil bio-available phosphate?

    NASA Astrophysics Data System (ADS)

    Gross, Avner; Angert, Alon

    2015-06-01

    The biological availability of phosphorus (P) is considered to be the limiting factor for plant growth in many natural and agricultural soils. Recent studies demonstrated that valuable information on soil P dynamics can be gained from the stable oxygen isotopes of soil phosphate (δ18OP). However, to interpret this information correctly, our understanding of the processes that controls soil phosphate δ18OP values needs to be improved since most of the current data is based primarily on laboratory studies of pure microbial cultures and enzymatic assays and may not be relevant to soils. Here we designed a series of controlled soil incubation experiments to study the actual isotopic effects induced by abiotic reactions, biological uptake, microbial turnover and organic-P mineralization on soil phosphate δ18OP values. We used this data to estimate the role of these processes in mediating soil P availability. Our study was conducted on Mediterranean soils sampled from the same site during winter, spring and summer. The soils were incubated with various mineral and organic-P compounds and their bioavailable phosphate concentrations and δ18OP values were measured. We confirmed that the role of abiotic reactions on phosphate δ18OP values was negligible and that the δ18OP values of the added phosphate were rapidly driven towards isotopic equilibrium with soil water. We suggest this process was mediated by rapid microbial phosphate turnover. Yet, we did not detect the expected isotopic enrichment effect associated with phosphate biological uptake. In another set of incubation experiments we demonstrated that mineralization of phosphate from organic compounds, such as phospho-mono-ester (PME) and phosphor-di-ester (PDE), produced an offset from isotopic equilibrium, as a result of the strong isotopic fractionation associated with the mineralization process. However, the δ18OP values recorded by the mineralized phosphate were gradually driven back towards isotopic

  16. Plasmachemical and heterogeneous processes in ozonizers with oxygen activation by a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Mankelevich, Yu. A.; Voronina, E. N.; Poroykov, A. Yu.; Rakhimov, T. V.; Voloshin, D. G.; Chukalovsky, A. A.

    2016-10-01

    Plasmachemical and heterogeneous processes of generation and loss of ozone in the atmosphericpressure dielectric barrier discharge in oxygen are studied theoretically. Plasmachemical and electronic kinetics in the stage of development and decay of a single plasma filament (microdischarge) are calculated numerically with and without allowance for the effects of ozone vibrational excitation and high initial ozone concentration. The developed analytical approach is applied to determine the output ozone concentration taking into account ozone heterogeneous losses on the Al2O3 dielectric surface. Using the results of quantummechanical calculations by the method of density functional theory, a multistage catalytic mechanism of heterogeneous ozone loss based on the initial passivation of a pure Al2O3 surface by ozone and the subsequent interaction of O3 molecules with the passivated surface is proposed. It is shown that the conversion reaction 2O3 → 3O2 of a gas-phase ozone molecule with a physically adsorbed ozone molecule can result in the saturation of the maximum achievable ozone concentration at high specific energy depositions, the nonstationarity of the output ozone concentration, and its dependence on the prehistory of ozonizer operation.

  17. The optimal dissolved oxygen profile in a nitrifying activated sludge process - comparisons with ammonium feedback control.

    PubMed

    Amand, L; Carlsson, B

    2013-01-01

    Ammonium feedback control is increasingly used to determine the dissolved oxygen (DO) set-point in aerated activated sludge processes for nitrogen removal. This study compares proportional-integral (PI) ammonium feedback control with a DO profile created from a mathematical minimisation of the daily air flow rate. All simulated scenarios are set to reach the same treatment level of ammonium, based on a daily average concentration. The influent includes daily variations only and the model has three aerated zones. Comparisons are made at different plant loads and DO concentrations, and the placement of the ammonium sensor is investigated. The results show that ammonium PI control can achieve the best performance if the DO set-point is limited at a maximum value and with little integral action in the controller. Compared with constant DO control the best-performing ammonium controller can achieve 1-3.5% savings in the air flow rate, while the optimal solution can achieve a 3-7% saving. Energy savings are larger when operating at higher DO concentrations.

  18. Plasmachemical and heterogeneous processes in ozonizers with oxygen activation by a dielectric barrier discharge

    SciTech Connect

    Mankelevich, Yu. A. Voronina, E. N.; Poroykov, A. Yu.; Rakhimov, T. V.; Voloshin, D. G.; Chukalovsky, A. A.

    2016-10-15

    Plasmachemical and heterogeneous processes of generation and loss of ozone in the atmosphericpressure dielectric barrier discharge in oxygen are studied theoretically. Plasmachemical and electronic kinetics in the stage of development and decay of a single plasma filament (microdischarge) are calculated numerically with and without allowance for the effects of ozone vibrational excitation and high initial ozone concentration. The developed analytical approach is applied to determine the output ozone concentration taking into account ozone heterogeneous losses on the Al{sub 2}O{sub 3} dielectric surface. Using the results of quantummechanical calculations by the method of density functional theory, a multistage catalytic mechanism of heterogeneous ozone loss based on the initial passivation of a pure Al{sub 2}O{sub 3} surface by ozone and the subsequent interaction of O{sub 3} molecules with the passivated surface is proposed. It is shown that the conversion reaction 2O{sub 3} → 3O{sub 2} of a gas-phase ozone molecule with a physically adsorbed ozone molecule can result in the saturation of the maximum achievable ozone concentration at high specific energy depositions, the nonstationarity of the output ozone concentration, and its dependence on the prehistory of ozonizer operation.

  19. Role of Oxygen as Surface-Active Element in Linear GTA Welding Process

    NASA Astrophysics Data System (ADS)

    Yadaiah, Nirsanametla; Bag, Swarup

    2013-11-01

    Although the surface-active elements such as oxygen and sulfur have an adverse effect on momentum transport in liquid metals during fusion welding, such elements can be used beneficially up to a certain limit to increase the weld penetration in the gas tungsten arc (GTA) welding process. The fluid flow pattern and consequently the weld penetration and width change due to a change in coefficient of surface tension from a negative value to a positive value. The present work is focused on the analysis of possible effects of surface-active elements to change the weld pool dimensions in linear GTA welding. A 3D finite element-based heat transfer and fluid flow model is developed to study the effect of surface-active elements on stainless steel plates. A velocity in the order of 180 mm/s due to surface tension force is estimated at an optimum concentration of surface-active elements. Further, the differential evolution-based global optimization algorithm is integrated with the numerical model to estimate uncertain model parameters such as arc efficiency, effective arc radius, and effective values of material properties at high temperatures. The effective values of thermal conductivity and viscosity are estimated to be enhanced nine and seven times, respectively, over corresponding room temperature values. An error analysis is also performed to find out the overall reliability of the computed results, and a maximum reliability of 0.94 is achieved.

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

    PubMed

    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.

  1. Bioreactor scale-up and oxygen transfer rate in microbial processes: an overview.

    PubMed

    Garcia-Ochoa, Felix; Gomez, Emilio

    2009-01-01

    In aerobic bioprocesses, oxygen is a key substrate; due to its low solubility in broths (aqueous solutions), a continuous supply is needed. The oxygen transfer rate (OTR) must be known, and if possible predicted to achieve an optimum design operation and scale-up of bioreactors. Many studies have been conducted to enhance the efficiency of oxygen transfer. The dissolved oxygen concentration in a suspension of aerobic microorganisms depends on the rate of oxygen transfer from the gas phase to the liquid, on the rate at which oxygen is transported into the cells (where it is consumed), and on the oxygen uptake rate (OUR) by the microorganism for growth, maintenance and production. The gas-liquid mass transfer in a bioprocess is strongly influenced by the hydrodynamic conditions in the bioreactors. These conditions are known to be a function of energy dissipation that depends on the operational conditions, the physicochemical properties of the culture, the geometrical parameters of the bioreactor and also on the presence of oxygen consuming cells. Stirred tank and bubble column (of various types) bioreactors are widely used in a large variety of bioprocesses (such as aerobic fermentation and biological wastewater treatments, among others). Stirred tanks bioreactors provide high values of mass and heat transfer rates and excellent mixing. In these systems, a high number of variables affect the mass transfer and mixing, but the most important among them are stirrer speed, type and number of stirrers and gas flow rate used. In bubble columns and airlifts, the low-shear environment compared to the stirred tanks has enabled successful cultivation of shear sensitive and filamentous cells. Oxygen transfer is often the rate-limiting step in the aerobic bioprocess due to the low solubility of oxygen in the medium. The correct measurement and/or prediction of the volumetric mass transfer coefficient, (k(L)a), is a crucial step in the design, operation and scale-up of

  2. Direct observation of the dealloying process of a platinum-yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction.

    PubMed

    Malacrida, Paolo; Casalongue, Hernan G Sanchez; Masini, Federico; Kaya, Sarp; Hernández-Fernández, Patricia; Deiana, Davide; Ogasawara, Hirohito; Stephens, Ifan E L; Nilsson, Anders; Chorkendorff, Ib

    2015-11-14

    Size-selected 9 nm PtxY nanoparticles have recently shown an outstanding catalytic activity for the oxygen reduction reaction, representing a promising cathode catalyst for proton exchange membrane fuel cells (PEMFCs). Studying their electrochemical dealloying is a fundamental step towards the understanding of both their activity and stability. Herein, size-selected 9 nm PtxY nanoparticles have been deposited on the cathode side of a PEMFC specifically designed for in situ ambient pressure X-ray photoelectron spectroscopy (APXPS). The dealloying mechanism was followed in situ for the first time. It proceeds through the progressive oxidation of alloyed Y atoms, soon leading to the accumulation of Y(3+) cations at the cathode. Acid leaching with sulfuric acid is capable of accelerating the dealloying process and removing these Y(3+) cations which might cause long term degradation of the membrane. The use of APXPS under near operating conditions allowed observing the population of oxygenated surface species as a function of the electrochemical potential. Similar to the case of pure Pt nanoparticles, non-hydrated hydroxide plays a key role in the ORR catalytic process.

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

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  4. Effect of reactive oxygen species (ROS) generating system for control of airborne microorganisms in meat processing environment

    USDA-ARS?s Scientific Manuscript database

    The effectiveness of reactive oxygen species (ROS) generating AirOcare equipment on the reduction of airborne bacteria in a meat processing environment was determined. Serratia marcescens and lactic acid bacteria (Lactococcus lactis subsp. lactis and Lactobacillus plantarum) were used to artificiall...

  5. Removing oxygen from a solvent extractant in an uranium recovery process

    DOEpatents

    Hurst, Fred J.; Brown, Gilbert M.; Posey, Franz A.

    1984-01-01

    An improvement in effecting uranium recovery from phosphoric acid solutions is provided by sparging dissolved oxygen contained in solutions and solvents used in a reductive stripping stage with an effective volume of a nonoxidizing gas before the introduction of the solutions and solvents into the stage. Effective volumes of nonoxidizing gases, selected from the group consisting of argon, carbon dioxide, carbon monoxide, helium, hydrogen, nitrogen, sulfur dioxide, and mixtures thereof, displace oxygen from the solutions and solvents thereby reduce deleterious effects of oxygen such as excessive consumption of elemental or ferrous and accumulation of complex iron phosphates or cruds.

  6. Method for oxygen reduction in a uranium-recovery process. [US DOE patent application

    DOEpatents

    Hurst, F.J.; Brown, G.M.; Posey, F.A.

    1981-11-04

    An improvement in effecting uranium recovery from phosphoric acid solutions is provided by sparging dissolved oxygen contained in solutions and solvents used in a reductive stripping stage with an effective volume of a nonoxidizing gas before the introduction of the solutions and solvents into the stage. Effective volumes of nonoxidizing gases, selected from the group consisting of argon, carbon dioxide, carbon monoxide, helium, hydrogen, nitrogen, sulfur dioxide, and mixtures thereof, displace oxygen from the solutions and solvents thereby reduce deleterious effects of oxygen such as excessive consumption of elemental or ferrous iron and accumulation of complex iron phosphates or cruds.

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

    DOEpatents

    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.

  8. An evaluation of physical and biogeochemical processes regulating the oxygen minimum zone in the water column of the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Sarma, V. V. S. S.

    2002-12-01

    Monthly oxygen budgets for the intermediate waters (100-1000 m) of the Bay of Bengal were constructed based on Modular Ocean Model (MOM) and oxygen data. The model results reveal that the oxygen levels in the oxygen minimum zone (OMZ) of the Bay of Bengal are controlled by physical and the associated biological processes. It results in maintaining low oxygen levels, with no significant seasonal variability, in the subsurface layer throughout the year. Low oxygen levels in the OMZ are sustained during the period of increased supply of organic matter through river runoff by enhanced supply of oxygen by the physical pump and vice versa. Thus, low oxygen levels in the OMZ are maintained by supply of oxygen by the physical pump to meet the demands of the biological processes. The inconsistency observed among oxygen consumption rates derived based on the present oxygen budget, carbon regeneration rate, and oxygen consumption rates computed based on electron transport system technique could be due to inadequate knowledge of seasonal and spatial variability in oxygen consumption in the latter two estimates. The residence time of intermediate waters (OMZ) of Bay of Bengal was computed to be 12 years.

  9. BENTHIC-PELAGIC PROCESSES IN PENSACOLA BAY, FL: EFFECTS OF LIGHT ON OXYGEN FLUXES

    EPA Science Inventory

    Eutrophication caused by excess nutrients can exacerbate hypoxia by increasing bottom water and sediment respiration. However, in shallow sub-tropical estuaries, the euphotic zone often extends below the pycnocline allowing oxygen fluxes in Pensacola Bay, FL, USA. Measurements we...

  10. BENTHIC-PELAGIC PROCESSES IN PENSACOLA BAY, FL: EFFECTS OF LIGHT ON OXYGEN FLUXES

    EPA Science Inventory

    Eutrophication caused by excess nutrients can exacerbate hypoxia by increasing bottom water and sediment respiration. However, in shallow sub-tropical estuaries, the euphotic zone often extends below the pycnocline allowing oxygen fluxes in Pensacola Bay, FL, USA. Measurements we...

  11. Effects of Nitrogen and Oxygen Radicals on Low-Temperature Bio-Molecule Processing

    NASA Astrophysics Data System (ADS)

    Motrescu, Iuliana; Ogino, Akihisa; Tanaka, Shigeyasu; Fujiwara, Taketomo; Kodani, Shinya; Kawagishi, Hirokazu; Popa, Gheorghe; Nagatsu, Masaaki

    2011-08-01

    The mechanism by which microwave plasma is able to modify the structure and function of proteinaceous molecules is investigated. The biomolecule cystine, a dimer aminoacid, was exposed to microwave surface wave plasma produced in reactive gases, such as oxygen and nitrogen, in different conditions. Except for the physical interactions of the charged particles with the samples and the photophysical reactions induced mostly by ultraviolet radiation, these plasmas contain reactive species which promote chemical interactions. In this study we focus on the changes of biomolecules due to neutral particles inside reactive plasmas. The results proved that the effects of neutrals and charged species are not cumulative. Moreover, it seems that the charged species inside the nitrogen plasma promote nitrogen addition while the outcome of neutral exposure is cleavage. Strong oxidation occurs for oxygen treatments, most reactive species which cause oxygen addition being the oxygen molecular ions O2+.

  12. New data on the process of circulation and blood oxygenation in the lungs under physiological conditions.

    PubMed

    Ivanov, K P

    2013-02-01

    Blood flow through the human lungs weighing 600 g is about 5 to 6 liters per minute. Blood capacity of human lung is about 500 ml. Therefore, 500 ml blood is oxygenated for 5 sec. Questions arise how such a large volume of blood passes through such a small mass of the lungs and what causes very rapid blood oxygenation. Since the structure of the lungs in mammals is almost the same, the work was carried out on rats (in rats 20-22 ml of blood per minute passes through the lungs weighing 1.5-2.0 g). Intensive blood circulation was proved to be linked with a large diameter pulmonary arterioles and high blood flow velocity in them. The oxygenation rate is explained by special structure of the alveoli and special blood flow conditions, which creates ideal conditions for oxygen diffusion.

  13. Evaluation of two oxygen analyzers by computerized data acquisition and processing.

    PubMed

    Erdmann, K; Jantzen, J P; Etz, C; Dick, W F

    1986-04-01

    Monitoring of inspired oxygen concentration during anesthesia with nitrous oxide is becoming accepted as essential. This type of monitoring demands accurate monitors that respond rapidly. We evaluated two such devices for their response patterns to rapid changes in oxygen concentration, a galvanic or "fuel cell" unit and a polarographic device. Data were stored after analog-to-digital conversion. The response patterns to stepwise changes in nitrous oxide and oxygen mixtures were recorded at flow rates ranging from 2 to 10 L/min. Both units responded accurately to all changes in the absolute oxygen concentration; the polarographic unit was, on average, twice as fast. Responsiveness to nitrous oxide was low (less than 0.4% at 100% nitrous oxide), and the stability of the signals was good. The 90% response time (T90) was consistent for any stepwise increase or decrease in oxygen concentration between 0, 21, 33, 50, and 100%. After a step change from 0 to 100% oxygen at a gas flow rate of 10 L/min, the T90 was 5.8 seconds in the polarographic device and 11.4 seconds in the galvanic device (p less than 0.01). After a decrease from 100 to 0% oxygen, the T90 was 0.6 second longer in both monitors. Comparing flow rates of 2 L/min with 10 L/min, the T90 was delayed by 1.1 and 2.3 seconds for an increase, and by 1.4 and 2.9 seconds for a decrease in oxygen concentration. Experimental data suggest that both sensors respond adequately during routine clinical use. The faster response of the polarographic device is probably of limited clinical relevance, but it may aid in calibration.

  14. Critical soil conditions for oxygen stress to plant roots: Substituting the Feddes-function by a process-based model

    NASA Astrophysics Data System (ADS)

    Bartholomeus, Ruud P.; Witte, Jan-Philip M.; van Bodegom, Peter M.; van Dam, Jos C.; Aerts, Rien

    2008-10-01

    SummaryEffects of insufficient soil aeration on the functioning of plants form an important field of research. A well-known and frequently used utility to express oxygen stress experienced by plants is the Feddes-function. This function reduces root water uptake linearly between two constant pressure heads, representing threshold values for minimum and maximum oxygen deficiency. However, the correctness of this expression has never been evaluated and constant critical values for oxygen stress are likely to be inappropriate. On theoretical grounds it is expected that oxygen stress depends on various abiotic and biotic factors. In this paper, we propose a fundamentally different approach to assess oxygen stress: we built a plant physiological and soil physical process-based model to calculate the minimum gas filled porosity of the soil ( ϕgas_min) at which oxygen stress occurs. First, we calculated the minimum oxygen concentration in the gas phase of the soil needed to sustain the roots through (micro-scale) diffusion with just enough oxygen to respire. Subsequently, ϕgas_min that corresponds to this minimum oxygen concentration was calculated from diffusion from the atmosphere through the soil (macro-scale). We analyzed the validity of constant critical values to represent oxygen stress in terms of ϕgas_min, based on model simulations in which we distinguished different soil types and in which we varied temperature, organic matter content, soil depth and plant characteristics. Furthermore, in order to compare our model results with the Feddes-function, we linked root oxygen stress to root water uptake (through the sink term variable F, which is the ratio of actual and potential uptake). The simulations showed that ϕgas_min is especially sensitive to soil temperature, plant characteristics (root dry weight and maintenance respiration coefficient) and soil depth but hardly to soil organic matter content. Moreover, ϕgas_min varied considerably between soil types

  15. Anthropogenic processing of dust affects the oxygen content of the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nenes, Athanasios; Ito, Taka; Johnson, Matthew; Meskhidze, Nicholas; Valett, Jackie; Deutsch, Curtis

    2015-04-01

    Observations from the last several decades show a significant expansion of the tropical Pacific oxygen minimum zone (OMZ). However, the underlying causes remain elusive, as the currently accepted effects of ocean warming and associated solubility decease cannot fully explain the observed oxygen trend. Here we show that anthropogenic pollution can change the pattern of biological productivity and oxygen trends consistent with observations in the tropics and extratropics. These effects are caused by the mobilization of iron in mineral dust by pollutants, where it is transported and deposited to the HNLC regions of the tropical pacific affecting primary productivity and oxygen consumption by bacterial respiration. In this study, it is shown that pollution-mobilized iron deposited to high latitude oceanic environments can profoundly impact subsurface oxygen and the extent of the OMZ through long-range oceanic transport. Together with the intensification of tropical upwelling since the 1990s associated with natural climate variability, our results can explain the expansion of the OMZ in the tropical Pacific in the late twentieth century. Unlike climate variability, however, anthropogenic pollution likely influences the long-term trends in marine biogeochemistry and further alters regional productivity and subsurface oxygen distributions with profound implications for marine habitats and nitrate inventory of the oceans.

  16. Anthropogenic processing of dust affects the oxygen content of the North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nenes, A.; Ito, T.; Johnson, M. S.; Meskhidze, N.; Valett, J.; Deutsch, C. A.

    2014-12-01

    Observations from the last several decades show a significant expansion of the tropical Pacific oxygen minimum zone (OMZ). However, the underlying causes remain elusive, as the currently accepted effects of ocean warming and associated solubility decease cannot fully explain the observed oxygen trend. Here we show that anthropogenic pollution can change the pattern of biological productivity and oxygen trends consistent with observations in the tropics and extratropics. These effects are caused by the mobilization of iron in mineral dust by pollutants, where it is transported and deposited to the HNLC regions of the tropical pacific affecting primary productivity and oxygen consumption by bacterial respiration. In this study, it is shown that pollution-mobilized iron deposited to high latitude oceanic environments can profoundly impact subsurface oxygen and the extent of the OMZ through long-range oceanic transport. Together with the intensification of tropical upwelling since the 1990s associated with natural climate variability, our results can explain the expansion of the OMZ in the tropical Pacific in the late twentieth century. Unlike climate variability, however, anthropogenic pollution likely influences the long-term trends in marine biogeochemistry and further alters regional productivity and subsurface oxygen distributions with profound implications for marine habitats and nitrate inventory of the oceans.

  17. Stable carbon and oxygen isotope fractionation processes during speleothem growth: systematic investigation in novel laboratory experiments

    NASA Astrophysics Data System (ADS)

    Scholz, D.; Hansen, M.; Dreybrodt, W.

    2012-04-01

    The most widely applied climate proxies in speleothems are stable carbon and oxygen isotopes (δ13C and δ18O). The interpretation of the stable isotope signals in terms of past temperature and/or precipitation variability is complex because both δ18O and δ13C depend on a complex interplay of various processes occurring in the atmosphere, the soil and karst above the cave and inside the cave. Quantitative reconstruction of climate parameters such as temperature and precipitation has, thus, remained impossible so far. Here we present several novel laboratory experiments aiming to understand the basic physical and chemical processes affecting the δ18O and δ13C signals during precipitation of calcium carbonate on the stalagmite surface. In particular, we aim to quantify the influence of kinetic isotope fractionation and verify recently published modelling studies (Dreybrodt, 2008; Scholz et al., 2009, Dreybrodt and Scholz, 2011). Several experiments are conducted: Degassing of CO2 from a thin film of water sparged with CO2 flowing down an inclined glass plate. pH and electric conductivity are systematically documented in order to monitor degassing of CO2. The results show that degassing of CO2 is fast, and the pCO2 of the solution is in equilibrium with the atmosphere after a short distance of flow. Carbon isotope exchange between atmospheric CO2 and dissolved bicarbonate. The results show that carbon isotope exchange may have a significant effect on the δ13C value of the dissolved bicarbonate and, thus, speleothem calcite, in particular for slow drip rates. Degassing of CO2 and calcite precipitation from a thin film of water supersaturated with respect to calcite flowing down an inclined calcium carbonate plate. Drip water is sampled after different lengths of flow path and, thus, different residence times on the plate, and pH, electrical conductivity and the stable isotope composition of the water are determined. Decreasing conductivity with increasing distance

  18. Characterization of Endogenous and Reduced Promoters for Oxygen-Limited Processes Using Escherichia coli.

    PubMed

    Lara, Alvaro R; Jaén, Karim E; Sigala, Juan-Carlos; Mühlmann, Martina; Regestein, Lars; Büchs, Jochen

    2017-02-17

    Oxygen limitation can be used as a simple environmental inducer for the expression of target genes. However, there is scarce information on the characteristics of microaerobic promoters potentially useful for cell engineering and synthetic biology applications. Here, we characterized the Vitreoscilla hemoglobin promoter (Pvgb) and a set of microaerobic endogenous promoters in Escherichia coli. Oxygen-limited cultures at different maximum oxygen transfer rates were carried out. The FMN-binding fluorescent protein (FbFP), which is a nonoxygen dependent marker protein, was used as a reporter. Fluorescence and fluorescence emission rates under oxygen-limited conditions were the highest when FbFP was under transcriptional control of PadhE, Ppfl and Pvgb. The lengths of the E. coli endogenous promoters were shortened by 60%, maintaining their key regulatory elements. This resulted in improved promoter activity in most cases, particularly for PadhE, Ppfl and PnarK. Selected promoters were also evaluated using an engineered E. coli strain expressing Vitreoscilla hemoglobin (VHb). The presence of the VHb resulted in a better repression using these promoters under aerobic conditions, and increased the specific growth and fluorescence emission rates under oxygen-limited conditions. These results are useful for the selection of promoters for specific applications and for the design of modified artificial promoters.

  19. Growth of oxygen bubbles during recharge process in zinc-air battery

    NASA Astrophysics Data System (ADS)

    Wang, Keliang; Pei, Pucheng; Ma, Ze; Chen, Huicui; Xu, Huachi; Chen, Dongfang; Xing, Haoqiang

    2015-11-01

    Rechargeable zinc-air battery used for energy storage has a serious problem of charging capacity limited by oxygen bubble coalescence. Fast removal of oxygen bubbles adhered to the charging electrode surface is of great importance for improving the charging performance of the battery. Here we show that the law of oxygen bubble growth can be achieved by means of phase-field simulation, revealing two phenomena of bubble detachment and bubble coalescence located in the charging electrode on both sides. Hydrodynamic electrolyte and partial insulation structure of the charging electrode are investigated to solve the problem of oxygen bubble coalescence during charging. Two types of rechargeable zinc-air battery are developed on the basis of different tri-electrode configurations, demonstrating that the charging performance of the battery with electrolyte flow (Ⅰ) is better than that of the battery with the partially insulated electrode (Ⅱ), while the battery Ⅱ is superior to the battery Ⅰ in the discharging performance, cost and portability. The proposed solutions and results would be available for promoting commercial application of rechargeable zinc-air batteries or other metal-air batteries.

  20. Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species.

    PubMed

    Tero, Ryugo; Yamashita, Ryuma; Hashizume, Hiroshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Hori, Masaru; Ito, Masafumi

    2016-09-01

    We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Fast Oxidation Processes in a Naturally Reduced Aquifer Zone Caused by Dissolved Oxygen

    NASA Astrophysics Data System (ADS)

    Davis, J. A.; Jemison, N. E.; Williams, K. H.; Hobson, C.; Bush, R. P.

    2014-12-01

    The occurrence of naturally reduced zones is quite common in alluvial aquifers in the western U.S.A. due to the burial of woody debris in flood plains. The naturally reduced zones are heterogeneously dispersed in such aquifers and are characterized by high concentrations of organic carbon and reduced phases, including iron sulfides and reduced forms of metals, including uranium(IV). The persistence of high concentrations of dissolved uranium(VI) at uranium-contaminated aquifers on the Colorado Plateau has been attributed to slow oxidation of insoluble uranium(IV) mineral phases that are found in association with these natural reducing zones, although there is little understanding of the relative importance of various potential oxidants. Three field experiments were conducted within an alluvial aquifer adjacent to the Colorado River near Rifle, CO wherein groundwater associated with naturally reduced zones was pumped into a gas-impermeable tank, mixed with a conservative tracer (Br-), bubbled with a gas phase composed of 97% O2 and 3% CO2, and then returned to the subsurface in the same well from which it was withdrawn. Within minutes of re-injection of the oxygenated groundwater, dissolved uranium(VI) concentrations increased from less than 1 μM to greater than 2.5 μM, demonstrating that oxygen can be an important oxidant for uranium in these field systems if supplied to the naturally reduced zones. Small concentrations of nitrate were also observed in the previously nitrate-free groundwater, and Fe(II) decreased to the detection limit. These results contrast with other laboratory and field results in which oxygen was introduced to systems containing high concentrations of mackinawite (FeS) rather than the more crystalline iron sulfides found in aged, naturally reduced zones. The flux of oxygen to the naturally reduced zones in the alluvial aquifers occurs mainly through interactions between groundwater and gas phases at the water table, and seasonal variations

  2. Relaxation Process of Photoexcited meso-Naphthylporphyrins while Interacting with DNA and Singlet Oxygen Generation.

    PubMed

    Hirakawa, Kazutaka; Taguchi, Makoto; Okazaki, Shigetoshi

    2015-10-15

    Electron donor-connecting cationic porphyrins meso-(1-naphthyl)-tris(N-methyl-p-pyridinio)porphyrin (1-NapTMPyP) and meso-(2-naphthyl)-tris(N-methyl-p-pyridinio)porphyrin (2-NapTMPyP) were designed and synthesized. DFT calculations speculate that the photoexcited states of 1- and 2-NapTMPyPs can be deactivated via intramolecular electron transfer from the naphthyl moiety to the porphyrin moiety. However, the quenching effect through the intramolecular electron transfer is insufficient, possibly due to the orthogonal position of the electron donor and the porphyrin ring and the relatively small driving force: Gibbs energies are 0.11 and 0.07 eV for 1- and 2-NapTMPyPs, respectively. It was speculated that more than 0.3 eV of the driving force is required to realize effective electron transfer in similar electron-donor connecting porphyrin systems. These porphyrins aggregated around the DNA strand, accelerating the deactivation of their excited singlet state and decreasing their photosensitized singlet oxygen-generating activities. In the presence of a sufficiently large concentration of DNA, these porphyrins can bind to a DNA strand stably, leading to an increased fluorescence quantum yield and lifetime. Singlet oxygen generation was also suppressed by the aggregation of porphyrins around DNA. Although the quantum yield of singlet oxygen generation was recovered in the presence of sufficient DNA, the singlet oxygen generated by DNA-binding porphyrins was significantly smaller than that without DNA. These results suggest that DNA-binding drugs limit the generation of photosensitized singlet oxygen by quenching the DNA strand.

  3. Human Factors Process Task Analysis: Liquid Oxygen Pump Acceptance Test Procedure at the Advanced Technology Development Center

    NASA Technical Reports Server (NTRS)

    Diorio, Kimberly A.; Voska, Ned (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on Human Factors Process Failure Modes and Effects Analysis (HF PFMEA). HF PFMEA includes the following 10 steps: Describe mission; Define System; Identify human-machine; List human actions; Identify potential errors; Identify factors that effect error; Determine likelihood of error; Determine potential effects of errors; Evaluate risk; Generate solutions (manage error). The presentation also describes how this analysis was applied to a liquid oxygen pump acceptance test.

  4. Influence of dissolved oxygen concentration on the start-up of the anammox-based process: ELAN®.

    PubMed

    Morales, N; Val del Río, A; Vázquez-Padín, J R; Gutiérrez, R; Fernández-González, R; Icaran, P; Rogalla, F; Campos, J L; Méndez, R; Mosquera-Corral, A

    2015-01-01

    The anammox-based process ELAN® was started-up in two different sequencing batch reactor (SBR) pilot plant reactors treating municipal anaerobic digester supernatant. The main difference in the operation of both reactors was the dissolved oxygen (DO) concentration in the bulk liquid. SBR-1 was started at a DO value of 0.4 mg O2/L whereas SBR-2 was started at DO values of 3.0 mg O2/L. Despite both reactors working at a nitrogen removal rate of around 0.6 g N/(L d), in SBR-1, granules represented only a small fraction of the total biomass and reached a diameter of 1.1 mm after 7 months of operation, while in SBR-2 the biomass was mainly composed of granules with an average diameter of 3.2 mm after the same operational period. Oxygen microelectrode profiling revealed that granules from SBR-2 where only fully penetrated by oxygen with DO concentrations of 8 mg O2/L while granules from SBR-1 were already oxygen penetrated at DO concentrations of 1 mg O2/L. In this way granules from SBR-2 performed better due to the thick layer of ammonia oxidizing bacteria, which accounted for up to 20% of all the microbial populations, which protected the anammox bacteria from non-suitable liquid media conditions.

  5. Development of a Novel Oxygen Supply Process and its Integration with an Oxy-Fuel Coal-Fired Boiler

    SciTech Connect

    2006-12-31

    BOC, the world's second largest industrial gas company, has developed a novel high temperature sorption based technology referred to as CAR (Cyclic Autothermal Recovery) for oxygen production and supply to oxy-fuel boilers with flue gas recycle. This technology is based on sorption and storage of oxygen in a fixed bed containing mixed ionic and electronic conductor materials. The objective of the proposed work was to construct a CAR PDU that was capable of producing 10-scfm of oxygen, using steam or recycled flue gas as the sweep gas, and install it in the Combustion Test Facility. The unit was designed and fabricated at BOC/The Linde Group, Murray Hill, New Jersey. The unit was then shipped to WRI where the site had been prepared for the unit by installation of air, carbon dioxide, natural gas, nitrogen, computer, electrical and infrastructure systems. Initial experiments with the PDU consisted of flowing air into both sides of the absorption systems and using the air heaters to ramp up the bed temperatures. The two beds were tested individually to operational temperatures up to 900 C in air. The cycling process was tested where gases are flowed alternatively from the top then bottom of the beds. The PDU unit behaved properly with respect to flow, pressure and heat during tests. The PDU was advanced to the point where oxygen production testing could begin and integration to the combustion test facility could occur.

  6. Benthic biological and biogeochemical patterns and processes across an oxygen minimum zone (Pakistan margin, NE Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Cowie, Gregory L.; Levin, Lisa A.

    2009-03-01

    Oxygen minimum zones (OMZs) impinging on continental margins present sharp gradients ideal for testing environmental factors thought to influence C cycling and other benthic processes, and for identifying the roles that biota play in these processes. Here we introduce the objectives and initial results of a multinational research program designed to address the influences of water depth, the OMZ (˜150-1300 m), and organic matter (OM) availability on benthic communities and processes across the Pakistan Margin of the Arabian Sea. Hydrologic, sediment, and faunal characterizations were combined with in-situ and shipboard experiments to quantify and compare biogeochemical processes and fluxes, OM burial efficiency, and the contributions of benthic communities, across the OMZ. In this introductory paper, we briefly review previous related work in the Arabian Sea, building the rationale for integrative biogeochemical and ecological process studies. This is followed by a summary of individual volume contributions and a brief synthesis of results. Five primary stations were studied, at 140, 300, 940, 1200 and 1850 m water depth, with sampling in March-May (intermonsoon) and August-October (late-to-postmonsoon) 2003. Taken together, the contributed papers demonstrate distinct cross-margin gradients, not only in oxygenation and sediment OM content, but in benthic community structure and function, including microbial processes, the extent of bioturbation, and faunal roles in C cycling. Hydrographic studies demonstrated changes in the intensity and extent of the OMZ during the SW monsoon, with a shoaling of the upper OMZ boundary that engulfed the previously oxygenated 140-m site. Oxygen profiling and microbial process rate determinations demonstrated dramatic differences in oxygen penetration and consumption across the margin, and in the relative importance of anaerobic processes, but surprisingly little seasonal change. A broad maximum in sediment OM content occurred on

  7. Process for spinning flame retardant elastomeric compositions. [fabricating synthetic fibers for high oxygen environments

    NASA Technical Reports Server (NTRS)

    Howarth, J. T.; Sheth, S.; Sidman, K. R.; Massucco, A. A. (Inventor)

    1978-01-01

    Flame retardant elastomeric compositions comprised of either spandex type polyurethane having halogen containing polyols incorporated into the polymer chain, conventional spandex type polyurethanes in physical admixture with flame retardant additives, or fluoroelastomeric resins in physical admixture with flame retardant additives were developed. Methods are described for preparing fibers of the flame retardant elastomeric materials and manufactured articles as well as nonelastic materials such as polybenzimidazoles, fiberglass, and nylons, for high oxygen environments.

  8. Surface segregation of zirconium in oxygen-processed {Zr}/{W(111) } system at high temperatures

    NASA Astrophysics Data System (ADS)

    Lee, S. C.; Irokawa, Y.; Inoue, M.; Shimizu, R.

    1996-07-01

    The behavior of Zr-atoms on W(111) surface associated with oxygen adsorption at different sample temperatures has been studied by Auger electron spectroscopy (AES), ion scattering spectroscopy (ISS) and measurement of relative change of the workfunction which was assessed from the shift of the onset of secondary electron energy distribution (Δф). The results have revealed: (1) adsorption of Zr onto the W(111) surface followed by the elevation of sample temperature up to 1750 K in an oxygen partial pressure of 2.7 × 10 -4 Pa induces drastic diffusion of Zr-atoms into the W(111) substrate, resulting in a high work function of ˜ 4.9 eV; (2) keeping the sample temperature at 1750 K, simple evacuation of the system to 2.7 × 10 -6 Pa has resulted in the segregation of Zr-atoms onto the surface. However, the W- and oxygen-atoms were also observed by ISS, indicating that the surface was not fully covered with Zr-atoms in contrast with the previous results for {Zr}/{W(100) } system, resulting in a work function of ˜4.8 eV; (3) the ISS studies under different incident angles have indicated clearly that the W intensity increases with increasing incident angle, suggesting that the segregated Zr-atoms are slightly embedded in the outermost atomic layer of tungsten.

  9. Corrosion Resistance of Ni-Based WC/Co Coatings Deposited by Spray and Fuse Process Varying the Oxygen Flow

    NASA Astrophysics Data System (ADS)

    Jiménez, H.; Olaya, J. J.; Alfonso, J. E.; Mtshali, C. B.; Pineda-Vargas, C. A.

    2017-08-01

    In this work, the effect of oxygen flow variation in the corrosion behavior of Ni-based WC/Co coatings deposited by spray and fuse process was investigated. The coatings were deposited on gray cast iron substrates using a Superjet Eutalloy thermal spraying gun. The morphology of the coatings was analyzed using scanning electron microscopy. The crystallographic phases were registered by x-ray diffraction (XRD), the diffraction patterns show the crystalline phases of the powder components with principal reflections for Ni and WC, the increase in flame temperature, due to the oxygen flow variation, generated amorphization in the nickel and an important crystallization of the planes (111) and (222) of WC as well as the decarburization of WC in W2C and W metallic. The corrosion behavior was investigated at room temperature in a 3.5% w/w aqueous solution of NaCl via potentiodynamic polarization. Electrochemical corrosion test showed that the coatings deposited under neutral flame conditions with an oxygen flow of 12.88 SCFH evidenced higher corrosion resistance. The chemical composition of the coatings and corrosion areas were analyzed by particle-induced x-ray emission, this technique permitting the corroboration of the decarburization process of WC determined by XRD and the formation of Cl structures.

  10. Corrosion Resistance of Ni-Based WC/Co Coatings Deposited by Spray and Fuse Process Varying the Oxygen Flow

    NASA Astrophysics Data System (ADS)

    Jiménez, H.; Olaya, J. J.; Alfonso, J. E.; Mtshali, C. B.; Pineda-Vargas, C. A.

    2017-10-01

    In this work, the effect of oxygen flow variation in the corrosion behavior of Ni-based WC/Co coatings deposited by spray and fuse process was investigated. The coatings were deposited on gray cast iron substrates using a Superjet Eutalloy thermal spraying gun. The morphology of the coatings was analyzed using scanning electron microscopy. The crystallographic phases were registered by x-ray diffraction (XRD), the diffraction patterns show the crystalline phases of the powder components with principal reflections for Ni and WC, the increase in flame temperature, due to the oxygen flow variation, generated amorphization in the nickel and an important crystallization of the planes (111) and (222) of WC as well as the decarburization of WC in W2C and W metallic. The corrosion behavior was investigated at room temperature in a 3.5% w/w aqueous solution of NaCl via potentiodynamic polarization. Electrochemical corrosion test showed that the coatings deposited under neutral flame conditions with an oxygen flow of 12.88 SCFH evidenced higher corrosion resistance. The chemical composition of the coatings and corrosion areas were analyzed by particle-induced x-ray emission, this technique permitting the corroboration of the decarburization process of WC determined by XRD and the formation of Cl structures.

  11. Maximizing biomass concentration in baker's yeast process by using a decoupled geometric controller for substrate and dissolved oxygen.

    PubMed

    Chopda, Viki R; Rathore, Anurag S; Gomes, James

    2015-11-01

    Biomass production by baker's yeast in a fed-batch reactor depends on the metabolic regime determined by the concentration of glucose and dissolved oxygen in the reactor. Achieving high biomass concentration in turn is dependent on the dynamic interaction between the glucose and dissolved oxygen concentration. Taking this into account, we present in this paper the implementation of a decoupled input-output linearizing controller (DIOLC) for maximizing biomass in a fed-batch yeast process. The decoupling is based on the inversion of 2×2 input-output matrix resulting from global linearization. The DIOLC was implemented online using a platform created in LabVIEW employing a TCP/IP protocol via the reactor's built-in electronic system. An improvement in biomass yield by 23% was obtained compared to that using a PID controller. The results demonstrate superior capability of the DIOLC and that the cumulative effect of smoother control action contributes to biomass maximization.

  12. On the triple oxygen isotope composition of carbon dioxide from some combustion processes

    NASA Astrophysics Data System (ADS)

    Horváth, B.; Hofmann, M. E. G.; Pack, A.

    2012-10-01

    The triple oxygen isotope composition (Δ17O) of CO2 from different sources is gaining in importance as possible tracer of gross carbon exchanges between major reservoirs. Here we present the Δ17O of CO2 from natural gas and propane-butane combustion, wood chips burning, car exhaust and human breath. All investigated CO2 samples had negative Δ17O value compared to the CO2-water equilibration line (slope θ = 0.522; zero intercept), which was inherited from the oxidant air O2. However, for all combustion experiments, the Δ17O value of CO2 was significantly higher than the Δ17O value of air O2. The oxygen isotope composition of CO2 from natural gas (δ18O = 21.6 ± 0.7‰; Δ17O = -0.30 ± 0.02‰) and from propane-butane (δ18O = 22.5 ± 0.8‰; Δ17O = -0.32 ± 0.02‰) combustion is explained by kinetic fractionation of ambient air O2. In case of wood chips burning (δ18O = 19.4 ± 1.0‰; Δ17O = -0.21 ± 0.02‰) the wood inherent O also affected the triple oxygen isotope composition of the CO2. Car exhaust CO2 (δ18O = 32.6 ± 3.0‰; Δ17O = -0.32 ± 0.03‰) might have likely equilibrated with the condensed water in the exhaust line. The isotope composition of breath CO2 (δ18O = 35 ± 1‰; Δ17O = -0.03 ± 0.03‰) was controlled by equilibration with body water. We assess the Δ17O value of CO2 as a potential tracer for anthropogenic CO2 emission.

  13. Oxygen isotopic fractionation of O₂ during adsorption and desorption processes using molecular sieve at low temperatures.

    PubMed

    Ahn, Insu; Kusakabe, Minoru; Lee, Jong Ik

    2014-06-15

    Cryogenic trapping using molecular sieves is commonly used to collect O2 extracted from silicates for (17)O/(16)O and (18)O/(16)O analyses. However, gases which interfere with (17)O/(16)O analysis, notably NF3, are also trapped and their removal is essential for accurate direct measurement of the (17)O/(16)O ratio. It is also necessary to identify and quantify any isotopic fractionation associated with the use of cryogenic trapping using molecular sieves. The oxygen isotopic compositions of O2 before and after desorption from, and adsorption onto, 13X and 5A molecular sieves (MS13X and MS5A) at 0°C, -78°C, -114°C, and -130°C were measured in order to determine the oxygen isotopic fractionation at these temperatures. We also investigated whether isotopic fractionation occurred when O2 gas was transferred sequentially into a second cold finger, also containing molecular sieve. It was confirmed that significant oxygen isotopic fractionation occurs between the gaseous O2 and that adsorbed onto molecular sieve, if desorption and adsorption are incomplete. As the fraction of released or untrapped O2 becomes smaller with decreasing trapping temperature (from 0 to -130°C), the isotopic fractionation becomes larger. Approximately half of the total adsorbed O2 is released from the molecular sieve during desorption at -114°C, which is the temperature recommended for separation from NF3 (retained on the molecular sieve), and this will interfere with (17)O/(16)O measurements. The use of a single cold finger should be avoided, because partial desorption is accompanied by oxygen isotopic fractionation, thereby resulting in inaccurate isotopic data. The use of a dual cold finger arrangement is recommended because, as we have confirmed, the transfer of O2 from the first trap to the second is almost 100%. However, even under these conditions, a small isotopic fractionation (0.18 ± 0.05‰ in δ(17)O values and 0.26 ± 0.06‰ in δ(18)O values) occurred, with O2 in

  14. Study of both sunflower oil and its headspace throughout the oxidation process. Occurrence in the headspace of toxic oxygenated aldehydes.

    PubMed

    Guillén, María D; Cabo, Nerea; Ibargoitia, María L; Ruiz, Ainhoa

    2005-02-23

    The static headspace composition of sunflower oil throughout the oxidation process at 70 degrees C with circulating air is studied by means of solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME-GC-MS); at the same time the liquid phase of the same oil is studied by means of Fourier transform infrared (FTIR) spectroscopy. Each technique provides complementary information about the process; FITR spectroscopy detects changes in the functional groups of the liquid matrix in a global way and SPME/GC-MS provides information about the different components present in the volatile phase during the oxidation process. Concordance between the timing of the changes produced in both liquid and gaseous phases is observed, as well as agreement and complementarity in the results obtained from both phases. The formation of some well-known genotoxic and cytotoxic oxygenated aldehydes in this process and their presence in the oil headspace are proved.

  15. Spontaneous ultraweak photon emission imaging of oxidative metabolic processes in human skin: effect of molecular oxygen and antioxidant defense system

    NASA Astrophysics Data System (ADS)

    Rastogi, Anshu; Pospíšil, Pavel

    2011-09-01

    All living organisms emit spontaneous ultraweak photon emission as a result of cellular metabolic processes. In this study, the involvement of reactive oxygen species (ROS) formed as the byproduct of oxidative metabolic processes in spontaneous ultraweak photon emission was studied in human hand skin. The effect of molecular oxygen and ROS scavengers on spontaneous ultraweak photon emission from human skin was monitored using a highly sensitive photomultiplier tube and charged coupled device camera. When spontaneous ultraweak photon emission was measured under anaerobic conditions, the photon emission was decreased, whereas under hyperaerobic condition the enhancement in photon emission was observed. Spontaneous ultraweak photon emission measured after topical application of glutathione, α-tocopherol, ascorbate, and coenzyme Q10 was observed to be decreased. These results reveal that ROS formed during the cellular metabolic processes in the epidermal cells play a significant role in the spontaneous ultraweak photon emission. It is proposed that spontaneous ultraweak photon emission can be used as a noninvasive tool for the temporal and spatial monitoring of the oxidative metabolic processes and intrinsic antioxidant system in human skin.

  16. Biomanufacturing process analytical technology (PAT) application for downstream processing: Using dissolved oxygen as an indicator of product quality for a protein refolding reaction.

    PubMed

    Pizarro, Shelly A; Dinges, Rachel; Adams, Rachel; Sanchez, Ailen; Winter, Charles

    2009-10-01

    Process analytical technology (PAT) is an initiative from the US FDA combining analytical and statistical tools to improve manufacturing operations and ensure regulatory compliance. This work describes the use of a continuous monitoring system for a protein refolding reaction to provide consistency in product quality and process performance across batches. A small-scale bioreactor (3 L) is used to understand the impact of aeration for refolding recombinant human vascular endothelial growth factor (rhVEGF) in a reducing environment. A reverse-phase HPLC assay is used to assess product quality. The goal in understanding the oxygen needs of the reaction and its impact to quality, is to make a product that is efficiently refolded to its native and active form with minimum oxidative degradation from batch to batch. Because this refolding process is heavily dependent on oxygen, the % dissolved oxygen (DO) profile is explored as a PAT tool to regulate process performance at commercial manufacturing scale. A dynamic gassing out approach using constant mass transfer (k(L)a) is used for scale-up of the aeration parameters to manufacturing scale tanks (2,000 L, 15,000 L). The resulting DO profiles of the refolding reaction show similar trends across scales and these are analyzed using rpHPLC. The desired product quality attributes are then achieved through alternating air and nitrogen sparging triggered by changes in the monitored DO profile. This approach mitigates the impact of differences in equipment or feedstock components between runs, and is directly inline with the key goal of PAT to "actively manage process variability using a knowledge-based approach." (c) 2009 Wiley Periodicals, Inc.

  17. Oxygen at nanomolar levels reversibly suppresses process rates and gene expression in anammox and denitrification in the oxygen minimum zone off northern Chile.

    PubMed

    Dalsgaard, Tage; Stewart, Frank J; Thamdrup, Bo; De Brabandere, Loreto; Revsbech, Niels Peter; Ulloa, Osvaldo; Canfield, Don E; DeLong, Edward F

    2014-10-28

    A major percentage (20 to 40%) of global marine fixed-nitrogen loss occurs in oxygen minimum zones (OMZs). Concentrations of O2 and the sensitivity of the anaerobic N2-producing processes of anammox and denitrification determine where this loss occurs. We studied experimentally how O2 at nanomolar levels affects anammox and denitrification rates and the transcription of nitrogen cycle genes in the anoxic OMZ off Chile. Rates of anammox and denitrification were reversibly suppressed, most likely at the enzyme level. Fifty percent inhibition of N2 and N2O production by denitrification was achieved at 205 and 297 nM O2, respectively, whereas anammox was 50% inhibited at 886 nM O2. Coupled metatranscriptomic analysis revealed that transcripts encoding nitrous oxide reductase (nosZ), nitrite reductase (nirS), and nitric oxide reductase (norB) decreased in relative abundance above 200 nM O2. This O2 concentration did not suppress the transcription of other dissimilatory nitrogen cycle genes, including nitrate reductase (narG), hydrazine oxidoreductase (hzo), and nitrite reductase (nirK). However, taxonomic characterization of transcripts suggested inhibition of narG transcription in gammaproteobacteria, whereas the transcription of anammox narG, whose gene product is likely used to oxidatively replenish electrons for carbon fixation, was not inhibited. The taxonomic composition of transcripts differed among denitrification enzymes, suggesting that distinct groups of microorganisms mediate different steps of denitrification. Sulfide addition (1 µM) did not affect anammox or O2 inhibition kinetics but strongly stimulated N2O production by denitrification. These results identify new O2 thresholds for delimiting marine nitrogen loss and highlight the utility of integrating biogeochemical and metatranscriptomic analyses. The removal of fixed nitrogen via anammox and denitrification associated with low O2 concentrations in oceanic oxygen minimum zones (OMZ) is a major sink in

  18. Investigations on the mechanism of oxygen-dependent plant processes: ethylene biosynthesis and cyanide-resistant respiration

    SciTech Connect

    Stegink, S.J.

    1985-01-01

    Two oxygen-dependent plant processes were investigated. A cell-free preparation from pea (Pisum sativum L., cv. Alaska) was used to study ethylene biosynthesis from 1-aminocyclopropane-1-carboxylic acid. Mitochondrial cyanide-resistant respiration was investigated in studies with /sup 14/C-butyl gallate and other respiratory effectors. Ethylene biosynthesis was not due to a specific enzyme, or oxygen radicals. Rather, hydrogen peroxide, generated at low levels, coupled with endogenous manganese produced ethylene. /sup 14/C-butyl gallate bound specifically to mitochondria from cyanide-sensitive and -resistant higher plants and Neurospora crassa mitochondria. The amount of gallate bound was similar for all higher plant mitochondria. Rat liver mitochondria bound very little /sup 14/C-butyl gallate. Plant mitochondria in which cyanide-resistance was induced bound as much /sup 14/C-butyl gallate as before induction. However mitochondria from recently harvested white potato tubers did not bind the gallate. The observations suggest that an engaging factor couples with a gallate binding site in the mitochondrial membrane. With skunk cabbage spadix mitochondria the I/sub 5//sup 0/ for antimycin A inhibition of oxygen uptake was decreased by salicylhydroxamic acid pretreatment; this was also true for reverse order additions. No shift was observed with mung bean hypocotyl or Jerusalem artichoke tuber mitochondria.

  19. Singlet oxygen-induced photodegradation of the polymers and dyes in optical sensing materials and the effect of stabilizers on these processes.

    PubMed

    Enko, Barbara; Borisov, Sergey M; Regensburger, Johannes; Bäumler, Wolfgang; Gescheidt, Georg; Klimant, Ingo

    2013-09-12

    A comprehensive study of photodegradation processes in optical sensing materials caused by photosensitized singlet oxygen in different polymers is presented. The stabilities of the polymers are accessed in the oxygen consumption measurements performed with help of optical oxygen sensors. Polystyrene and poly(phenylsilesquioxane) are found to be the most stable among the polymers investigated, whereas poly(2,6-dimethyl-p-phenylene oxide) and particularly poly(methyl methacrylate) and their derivatives show the fastest oxygen consumption. The effect of the stabilizers (singlet oxygen quenchers) on the oxygen consumption rates, the photostability of the sensitizer, and the total photon emission (TPE) by singlet oxygen is studied. 1,4-Diazabicyclo[2.2.2]octane (DABCO) was found to significantly reduce both the TPE and the oxygen consumption rates, indicating its role as a physical quencher of singlet oxygen. The addition of DABCO also significantly improved the photostability of the sensitizer. The N-alkylated derivative of DABCO and DABCO covalently grafted to the polystyrene backbone are prepared in an attempt to overcome the volatility and water solubility of the quencher. These derivatives as well as other tertiary amines investigated were found to be inefficient as stabilizing agents, and some of them even negatively affected the oxygen consumption rates.

  20. Comparative techno-economic analysis and process design for indirect liquefaction pathways to distillate-range fuels via biomass-derived oxygenated intermediates upgrading: Liquid Transportation Fuel Production via Biomass-derived Oxygenated Intermediates Upgrading

    SciTech Connect

    Tan, Eric C. D.; Snowden-Swan, Lesley J.; Talmadge, Michael; Dutta, Abhijit; Jones, Susanne; Ramasamy, Karthikeyan K.; Gray, Michel; Dagle, Robert; Padmaperuma, Asanga; Gerber, Mark; Sahir, Asad H.; Tao, Ling; Zhang, Yanan

    2016-09-27

    This paper presents a comparative techno-economic analysis (TEA) of five conversion pathways from biomass to gasoline-, jet-, and diesel-range hydrocarbons via indirect liquefaction with specific focus on pathways utilizing oxygenated intermediates. The four emerging pathways of interest are compared with one conventional pathway (Fischer-Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include: biomass to syngas via indirect gasification, gas cleanup, conversion of syngas to alcohols/oxygenates followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. Conversion of biomass-derived syngas to oxygenated intermediates occurs via three different pathways, producing: 1) mixed alcohols over a MoS2 catalyst, 2) mixed oxygenates (a mixture of C2+ oxygenated compounds, predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate) using an Rh-based catalyst, and 3) ethanol from syngas fermentation. This is followed by the conversion of oxygenates/alcohols to fuel-range olefins in two approaches: 1) mixed alcohols/ethanol to 1-butanol rich mixture via Guerbet reaction, followed by alcohol dehydration, oligomerization, and hydrogenation, and 2) mixed oxygenates/ethanol to isobutene rich mixture and followed by oligomerization and hydrogenation. The design features a processing capacity of 2,000 tonnes/day (2,205 short tons) of dry biomass. The minimum fuel selling prices (MFSPs) for the four developing pathways range from $3.40 to $5.04 per gasoline-gallon equivalent (GGE), in 2011 US dollars. Sensitivity studies show that MFSPs can be improved with co-product credits and are comparable to the commercial Fischer-Tropsch benchmark ($3.58/GGE). Overall, this comparative TEA study documents potential economics for the developmental biofuel pathways via mixed oxygenates.

  1. Oxygen and Metals Processing on the Moon: Will Materials Science Change Our Future in Space?

    NASA Technical Reports Server (NTRS)

    Sibille, Laurent; Sadoway, Donald R.

    2008-01-01

    As part of an In-Situ Resource Utilization infrastructure on the lunar surface, the production of oxygen and metals by various technologies is under development within NASA projects. Such an effort reflects the ambition to change paradigms in space exploration to enable human presence for the long-term. Sustaining such presence involves the acceptance of a new concept in space activities; crews must be able to generate some of their consumables from local resources. The balance between accepting early development risks and reducing long-term mission risks is at the core of the technology development approach. We will present an overview of the technologies involved and present their possible impact on the future of human expansion in the solar system.

  2. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal.

    PubMed

    Addison, Paul S

    2016-06-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time-frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general.

  3. Catalyst for the synthesis of oxygenated organic compounds and process for its manufacture

    SciTech Connect

    Passariello, A.

    1984-07-10

    Catalyst for heterogeneous synthesis and more particularly for the preparation of oxygenated compounds from synthesis gas (substantially H/sub 2/ and CO and CO/sub 2/), based on the general formula: CuTi /SUB a/ M /SUB b/ A /SUB c/ in which M is at least one metal selected from the group consisting of chrome, manganese, cobalt, molybdenum, rhodium platinum and iron, A is an alkali or alkaline earth metal, a is comprised within 0.1 and 0.5 and b and c may vary between 0 and 0.2. Application of these catalysts for the preparation of higher alcohol mixtures (fuel grade) C/sub 1/-C/sub 4/ when b and c are zero, and C/sub 1/-C/sub 4/(for about 50%) and C/sub 5/-C/sub 10/(for the other 50%) when b and c are other than zero.

  4. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal

    PubMed Central

    2016-01-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time–frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general. PMID:27382479

  5. Effect of operational parameters on the removal of particulate chemical oxygen demand in the activated sludge process.

    PubMed

    Jimenez, Jose A; La Motta, Enrique J; Parker, Denny S

    2007-09-01

    The removal of particulate material in the aeration basin of the activated sludge process is mainly attributed to bioflocculation and hydrolysis of particulate substrate. The bioflocculation process in the aeration tank of the activated sludge process occurs only under favorable conditions in the system, and several common operational parameters affect its performance. The principal objective of this research was to observe the effect of mixed liquor suspended solids, solids retention time (SRT), and extracellular polymer substances on the removal of particulate substrate by bioflocculation. A first-order particulate removal expression, based on flocculation, accurately described the removal rates for supernatant suspended solids and colloidal chemical oxygen demand. Based on the results presented in this investigation, a mixed liquor concentration of approximately 2200 mg/L, an SRT of at least 3 days, and a contact time of 30 minutes are needed for relatively complete removal of the particulate substrate in a plug-flow reactor.

  6. The oxygen isotope effect in the earliest processed solids in the solar system: is it a chemical mass-independent process?

    NASA Astrophysics Data System (ADS)

    Ali, A.; Nuth, J. A.

    2007-06-01

    Aims:An anomalous effect in the abundances of oxygen isotopes in the most refractory calcium-aluminum-rich inclusions (CAIs) was discovered some thirty years ago. The origin of these oxygen isotopic anomalies has hitherto remained unexplained. The origin is neither nuclear, nor has the recent photochemical self-shielding explanation been proven to be valid. We discuss a possible chemical mechanism to resolve these observed effects. Methods: By uniting the most recent laboratory observations of nanoclusters of silicates in beams and the first principles theoretical studies of their structure and properties with a major dynamical constraint recently described as the surface non-RRKM effect during SiO{2} formation on the growing grain, we show that the origin of the anomalous isotopic effect in high-temperature minerals in CAIs is chemical and strictly mass-independent. Results: We report that the surface non-RRKM effect would represent a major process in the formation of our own solar system and observable protoplanetary accretion disks, and the mass-independent isotope effects are directly associated with the formation of primary grains in the high temperature nebular environment. We expect that this chemical reaction mechanistic approach combined with future time-resolved studies on the kinetics of growth of silicates and a precise knowledge of the oxygen isotopic abundances of the sun would provide a very detailed understanding of the origins of formation of our solar system.

  7. Processes controlling dissolved oxygen and pH in the upper Willamette River basin, Oregon, 1994

    USGS Publications Warehouse

    Pogue, Ted R.; Anderson, Chauncey W.

    1995-01-01

    In July and August of 1994, the U. S. Geological Survey in cooperation with the Oregon Department of Environmental Quality (ODEQ) collected data to document the spatial extent and diel variability of dissolved oxygen (DO) concentrations and pH levels in selected reaches of streams in the upper Willamette River Basin. These data were also collected to identify primary factors that control DO concentrations downstream from major point sources as well as to provide ODEQ with data to refine calibration of their steady-state DO and nutrient models for the upper Willamette River Basin. All of the reaches studied had diel variations in DO and pH. The magnitude of the diel variations in DO ranged from 0.2 to 3.9 milligrams per liter (7 to 50 percent-saturation units based on ambient water temperature and barometric pressure) and in pH from 0.3 to 1.4 units. However, of the reaches studied, only the Coast Fork Willamette River from river mile (RM) 21.7 to 12.5 and the Willamette River from RM 151 to 141.6 had field measured violations of State standards for DO and pH. DO concentration and pH in water depend on many factors. Data were collected to examine several major factors, including BOD (biochemical oxygen demand), carbonaceous BOD, nitrogenous BOD, and measures of photosynthetic activity. Of the four study reaches, only a short stretch of the Coast Fork Willamette River has potential for important levels of oxygen consumption from BOD or nitrification. Additionally, water-column primary-productivity measurements indicated that respiration and photosynthesis by free-floating algae did not explain the observed diel variations in DO in the study reaches. Results from a simple mathematical model incorporating measures of community respiration and net primary productivities indicated that periphyton are capable of producing a diel variation of the order of magnitude observed during the August study period. In the Willamette River near Peoria, the combined periphyton DO

  8. A high performance biometric signal and image processing method to reveal blood perfusion towards 3D oxygen saturation mapping

    NASA Astrophysics Data System (ADS)

    Imms, Ryan; Hu, Sijung; Azorin-Peris, Vicente; Trico, Michaël.; Summers, Ron

    2014-03-01

    Non-contact imaging photoplethysmography (PPG) is a recent development in the field of physiological data acquisition, currently undergoing a large amount of research to characterize and define the range of its capabilities. Contact-based PPG techniques have been broadly used in clinical scenarios for a number of years to obtain direct information about the degree of oxygen saturation for patients. With the advent of imaging techniques, there is strong potential to enable access to additional information such as multi-dimensional blood perfusion and saturation mapping. The further development of effective opto-physiological monitoring techniques is dependent upon novel modelling techniques coupled with improved sensor design and effective signal processing methodologies. The biometric signal and imaging processing platform (bSIPP) provides a comprehensive set of features for extraction and analysis of recorded iPPG data, enabling direct comparison with other biomedical diagnostic tools such as ECG and EEG. Additionally, utilizing information about the nature of tissue structure has enabled the generation of an engineering model describing the behaviour of light during its travel through the biological tissue. This enables the estimation of the relative oxygen saturation and blood perfusion in different layers of the tissue to be calculated, which has the potential to be a useful diagnostic tool.

  9. Computational fluid dynamics modeling of chemical looping combustion process with calcium sulphate oxygen carrier - article no. A19

    SciTech Connect

    Baosheng Jin; Rui Xiao; Zhongyi Deng; Qilei Song

    2009-07-01

    To concentrate CO{sub 2} in combustion processes by efficient and energy-saving ways is a first and very important step for its sequestration. Chemical looping combustion (CLC) could easily achieve this goal. A chemical-looping combustion system consists of a fuel reactor and an air reactor. Two reactors in the form of interconnected fluidized beds are used in the process: (1) a fuel reactor where the oxygen carrier is reduced by reaction with the fuel, and (2) an air reactor where the reduced oxygen carrier from the fuel reactor is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, while the outlet gas stream from the air reactor contains only N{sub 2} and some unused O{sub 2}. The water in combustion products can be easily removed by condensation and pure carbon dioxide is obtained without any loss of energy for separation. Until now, there is little literature about mathematical modeling of chemical-looping combustion using the computational fluid dynamics (CFD) approach. In this work, the reaction kinetic model of the fuel reactor (CaSO{sub 4}+ H{sub 2}) is developed by means of the commercial code FLUENT and the effects of partial pressure of H{sub 2} (concentration of H{sub 2}) on chemical looping combustion performance are also studied. The results show that the concentration of H{sub 2} could enhance the CLC performance.

  10. A Novel Solid Electrolyte Oxygen Sensor System for In-Situ Measurement and Process Control

    NASA Astrophysics Data System (ADS)

    Hammer, Frank Uwe; Messerschmid, Ernst; Rogg, Markus

    2010-10-01

    In 1993 the oxygen partial pressure was firstly measured inside a plasma wind tunnel using conventional λ-probes. Since then, a considerable amount of knowledge has been gained in using these sensors in ground test facilities and space. However, these commercially available sensors were too large in scale and weight. Consequently, a new development of solid electrolyte sensors called FIPEX more feasible for space was initiated. Due to space driven benefits, interest arose to use FIPEX technique in terrestrial applications e.g. to monitor sputter plants for float glass coating. Therefore, the VacuSen® sensor was developed. The characterization of VacuSen® at nominal sensor temperature TS = 680° C resulted in a sensor current according to IS = bṡpO20ṡ8±0ṡ05 I[μA] in the operation range between ptot = 1ṡ10-3 to 5 Pa. From pulse width modulation (PWM) temperature control, additional information allows to measure ptot according to ptot = aṡRPWM0ṡ107±0ṡ005 thus enlarging the operation range to ptot = 1ṡ10-3 to 1ṡ105Pa. A one point calibration routine with air, ideally at ptot = 5 Pa in order to determine both calibration parameters a and b simultaneously, is proposed.

  11. Oxygen isotope fractionation processes in the water-calcite-aragonite system

    NASA Astrophysics Data System (ADS)

    Fohlmeister, Jens; Spötl, Christoph; Plessen, Birgit; Tjallingii, Rik; Schröder-Ritzrau, Andrea; Frank, Norbert; Arps, Jennifer; Leutz, Kathrin; Vollweiler, Nicole; Trüssel, Martin

    2017-04-01

    The O isotopic composition of speleothems in their pure calcite or pure aragonite polymorphs provides valuable insight into past climate variability. However, robust climatic interpretations become difficult when both polymorphs are present either in different growth layers or as intergrown fabrics. Experimental studies show that the O isotope fractionation between the dissolved carbonate species and CaCO3 is about 0.75‰ (at 10°C) larger for aragonite than for calcite (e.g., Kim et al., 2007, Kim and O'Neil, 1997). The temperature dependence of this offset is negligible for temperature variations typical of most cave systems. However, cave analogue experiments examining this offset are still lacking. Here, we present stable O isotope measurements of a Holocene speleothem from the Swiss Alps, which shows exactly one calcite-aragonite transition along individual growth layers. Oxygen isotope measurements along 'Hendy test'-like traverses across those transitions provide insight into the fractionation behavior of the water-calcite vs. water-aragonite system. We observed a fractionation offset smaller than predicted by laboratory experiments that varies by at least a factor of two. In addition, the observed variations correlate positively with growth rate and negatively with the isotopic composition of the calcite precipitating at the growth axis. The reason for this behavior is still unclear. Trace element analyses across the transitions of growth layers are planned to help understanding this pattern.

  12. Investigation of photo-induced diffusion of oxygen into carbon nanotube for oxidation process

    NASA Astrophysics Data System (ADS)

    Hussain, Shahir; Khamaj, Jabril A.

    2015-11-01

    A controlled and less destructive way of purification of as-grown carbon nanotube (CNT) is a challenging task for the scientific community. A new approach for oxidation of as-grown CNTs using ultraviolet (UV) light lamp is investigated in this paper. For this purpose, the experiment was conducted in a UV lamp chamber consists of a layer of reflective aluminum foil inside to ensure the entire sample would have an even exposure to UV. The experiments were performed under ambient condition. In this study, we vary the exposure time of oxidation. The removal of non-nanotube material after UV light exposure is confirmed by field emission scanning electron microscopy and Raman spectroscopy. Raman spectra show that D band becomes narrow which is consistent with highly purified nanotube. We observed that the intensity of G and D* bands increased rapidly with increasing the UV light exposure time for oxidation. Intensity ratio I D*/ I D increases continually with increasing the oxidation time which confirms the reduction of impurities from the MWNTs. Fourier transform infrared spectroscopy confirms the presence of defect sites where some oxygenated functional groups are attached.

  13. Evolution of the superconductivity during the pressure-induced oxygen ordering process in oxygen-deficient REBa{sub 2}Cu{sub 3}O{sub 6+x} (RE = Y,Nd,La)

    SciTech Connect

    Fita, I.M.; Puzniak, R.; Doroshenko, N.A.; Dyakonov, V.P.; Wisniewski, A.; Szymczak, H.

    1999-11-01

    The pressure controlled oxygen reordering processes in REBa{sub 2}Cu{sub 3}O{sub 6+x}(RE = Y,Nd,La) causing the continuous charge transfer between the CuO{sub x} and CuO{sub 2} planes were investigated. The charge transfer results in the time evolution of superconductivity. A strong acceleration of ordering and disordering processes was found when the RE-ion size increases from Y to La. Pressure induced semiconductor-superconductor transition in LaBa{sub 2}Cu{sub 3}O{sub 6+x} resulted from the oxygen ordering is reported for the first time.

  14. Antihistamine induced blood oxygenation level dependent response changes related to visual processes during sensori-motor performance.

    PubMed

    van Ruitenbeek, Peter; Vermeeren, Annemiek; Mehta, Mitul Ashok; Drexler, Eva Isabell; Riedel, Willem Jan

    2014-07-01

    The histaminergic involvement in selective processes underlying its role in human sensori-motor performance is largely unknown. Recently, selective effects of central H₁-inverse agonism on sensory visual processes were observed in electrophysiological--but not behavioral data; a discrepancy suggested to result from speeded response-choice related processes. This study attempts to establish the effects on visual processes and identify putative compensatory mechanisms related to increased visual and response-choice task demands by assessing H₁-inverse agonism induced changes in blood oxygenation level dependent (BOLD) response. Twelve participants received oral doses of dexchlorpheniramine 4 mg, lorazepam 1 mg, and placebo in a three-way crossover designed study. Brain activity was assessed for choice reaction time task performance in a 3 T magnetic resonance scanner 2 h after drug administration. Participants responded with their left or right hand and index or middle finger as indicated by the laterality of stimulus presentation and identity of the stimulus, respectively. Stimuli were intact or visually degraded and responses were compatible or incompatible with the laterality of stimulus presentation. Both dexchlorpheniramine and lorazepam affected the BOLD response in the occipital cortex indicating affected visual information processing. Dexchlorpheniramine decreased BOLD response in the dorsal precuneus and left precentral gyrus as part of a motor network, which however might not be interpreted as a compensatory mechanism, but may be the upstream consequence of impaired visual processing. Copyright © 2013 Wiley Periodicals, Inc.

  15. Sliding mode control of dissolved oxygen in an integrated nitrogen removal process in a sequencing batch reactor (SBR).

    PubMed

    Muñoz, C; Young, H; Antileo, C; Bornhardt, C

    2009-01-01

    This paper presents a sliding mode controller (SMC) for dissolved oxygen (DO) in an integrated nitrogen removal process carried out in a suspended biomass sequencing batch reactor (SBR). The SMC performance was compared against an auto-tuning PI controller with parameters adjusted at the beginning of the batch cycle. A method for cancelling the slow DO sensor dynamics was implemented by using a first order model of the sensor. Tests in a lab-scale reactor showed that the SMC offers a better disturbance rejection capability than the auto-tuning PI controller, furthermore providing reasonable performance in a wide range of operation. Thus, SMC becomes an effective robust nonlinear tool to the DO control in this process, being also simple from a computational point of view, allowing its implementation in devices such as industrial programmable logic controllers (PLCs).

  16. Effect of oxygen partial pressure on texture development in lead zirconate titanate thin films processed from metalorganic precursors

    SciTech Connect

    Norton, Jarrod L.; Liedl, Gerald L.; Slamovich, Elliott B.

    1999-12-01

    Metalorganic liquid precursors were used to examine the effects of processing atmosphere on texture development in oriented Pb(Zr{sub 0.60}Ti{sub 0.40})O{sub 3} thin films. After removal of organic ligands via pyrolysis, the films were heated at 25 degree sign C/min in a 5% H{sub 2}/Ar atmosphere until a switching temperature, after which the atmosphere was switched to pure oxygen. The films were heated to a maximum temperature of 650 degree sign C with switching temperatures ranging from 450 to 600 degree sign C. The degree of (111) orientation in the lead zirconate titanate (PZT) films increased with increasing switching temperature, resulting in highly textured (111) PZT films. These results suggest that atmosphere control plays a significant role in texture development during rapid thermal processing. (c) 1999 Materials Research Society.

  17. Color analysis method for estimating the oxygen saturation of hemoglobin using an image-input and processing system.

    PubMed

    Hashimoto, M; Hata, R; Isomoto, A; Tyuma, I; Fukuda, M

    1987-04-01

    A color analysis method which enables both qualitative and quantitative analyses of an object's color was developed. The method uses a color image-input and processing system composed of a 3-tube video camera and a digital image analyzer, which quantizes a color image into values of red, green, and blue brightness, then processes these values. We introduced a spectrophotometric principle by the Beer-Lambert law, and were able to establish a color model to analyze an object's color. In the coordinate space based on our color model, the hue of the object's color is represented by the direction from the origin, and the density by the distance from the origin. This new method was used to analyze the colors of hemoglobin solutions at various oxygen saturations and concentrations. The results agreed with the known conditions, indicating the validity of the model and its usefulness for quantitative as well as qualitative analyses of color.

  18. EVALUATION OF PHOSPHINE-OXYGEN DIFFUSION SYSTEM AS A PROCESS FOR SILICON INTEGRATED CIRCUIT FABRICATION.

    DTIC Science & Technology

    Experimental conditions for the attainment of sheet resistance with high reproducibility at emitter doping levels have been obtained using the...gaseous PH3-O2 process. Under these conditions, the deposition sheet resistance follows an activation energy relationship with temperature (with E = 2.9 eV...1000C. The two-step process shows that the final diffused sheet resistance and junction depth can be predicted from the deposition sheet resistance . The

  19. A Technique for Decreasing Reactivity of Coal Material to Suppress the Oxygen Absorption Process

    NASA Astrophysics Data System (ADS)

    Timofeeva, S. S.; Lugovtsova, N. Yu; Gubanova, A. R.

    2016-08-01

    The paper describes the mechanisms of self-ignition formation in coal liable to spontaneous combustion, on the basis of experimental works performed to analyze heat and mass transfer in the coal-air system. A new approach was developed to the coal self-heating suppression and thermodynamic control of the oxidation process. The influence of coal moisture content and thermal behaviour of air in the cooling process was studied during moisture evaporation.

  20. Brain tissue oxygen amperometry in behaving rats demonstrates functional dissociation of dorsal and ventral hippocampus during spatial processing and anxiety

    PubMed Central

    McHugh, Stephen B; Fillenz, Marianne; Lowry, John P; Rawlins, J Nicolas P; Bannerman, David M

    2011-01-01

    Traditionally, the function of the hippocampus (HPC) has been viewed in unitary terms, but there is growing evidence that the HPC is functionally differentiated along its septotemporal axis. Lesion studies in rodents and functional brain imaging in humans suggest a preferential role for the septal HPC in spatial learning and a preferential role for the temporal HPC in anxiety. To better enable cross-species comparison, we present an in vivo amperometric technique that measures changes in brain tissue oxygen at high temporal resolution in freely-moving rats. We recorded simultaneously from the dorsal (septal; dHPC) and ventral (temporal; vHPC) HPC during two anxiety tasks and two spatial tasks on the radial maze. We found a double-dissociation of function in the HPC, with increased vHPC signals during anxiety and increased dHPC signals during spatial processing. In addition, dHPC signals were modulated by spatial memory demands. These results add a new dimension to the growing consensus for a differentiation of HPC function, and highlight tissue oxygen amperometry as a valuable tool to aid translation between animal and human research. PMID:21105915

  1. High-strength wastewater treatment in a pure oxygen thermophilic process: 11-year operation and monitoring of different plant configurations.

    PubMed

    Collivignarelli, M C; Bertanza, G; Sordi, M; Pedrazzani, R

    2015-01-01

    This research was carried out on a full-scale pure oxygen thermophilic plant, operated and monitored throughout a period of 11 years. The plant treats 60,000 t y⁻¹ (year 2013) of high-strength industrial wastewaters deriving mainly from pharmaceuticals and detergents production and landfill leachate. Three different plant configurations were consecutively adopted: (1) biological reactor + final clarifier and sludge recirculation (2002-2005); (2) biological reactor + ultrafiltration: membrane biological reactor (MBR) (2006); and (3) MBR + nanofiltration (since 2007). Progressive plant upgrading yielded a performance improvement chemical oxygen demand (COD) removal efficiency was enhanced by 17% and 12% after the first and second plant modification, respectively. Moreover, COD abatement efficiency exhibited a greater stability, notwithstanding high variability of the influent load. In addition, the following relevant outcomes appeared from the plant monitoring (present configuration): up to 96% removal of nitrate and nitrite, due to denitrification; low-specific biomass production (0.092 kgVSS kgCODremoved⁻¹), and biological treatability of residual COD under mesophilic conditions (BOD5/COD ratio = 0.25-0.50), thus showing the complementarity of the two biological processes.

  2. Investigating atmospheric transport processes using cosmogenic 35S and oxygen isotopic anomaly (Δ17O) in sulfate

    NASA Astrophysics Data System (ADS)

    Hill-Falkenthal, J. C.; Pandey, A.; Coupal, E.; Kim, S. D.; Dominguez, G.; Thiemens, M. H.

    2010-12-01

    Sulfate aerosols have been recognized to possess hazardous impact on both climate and human health. Improved understanding of the SO2 residence time and sulfate aerosol transport is needed for assessing its influences on climate. Cosmogenically produced 35S (half-life~87 days)1 measurements have been used to understand the atmospheric transport process, boundary layer dynamics and its effect on the tropospheric SO2 oxidation rate constant. Our method involves determining 35S in gaseous SO2 and aerosol sulfate samples collected twice a week at Scripps Institute of Oceanography Pier (La Jolla, CA) for a year along with the determination of oxygen isotopes in both coarse and fine particle samples. The oxygen isotopes measurement in sulfate and 35S measurements were done by isotope ratio mass spectrometry and low-noise liquid scintillation spectroscopy2, respectively. The data show that 35S activity is significantly different for coarse and fine particles, with the latter possessing higher activity as it is mainly produced from the gas phase oxidation of SO2 at higher altitude. The fluctuation in 35S activity in fine particles indicates mixing of air masses from higher altitude. The coarse particles show nearly constant 35S activity which is either due to the constant uptake rate of SO2 by sea salt aerosol or the coagulation of fine particles together. The normalized activity 35S/S is about 5 times higher in both coarse and fine particles during Santa Ana wind event. Santa Ana wind is characterized by low humidity (<20%) and relatively high temperature and may have an impact on SO2 oxidation. We are investigating the sulfate oxygen isotope signature and the correlation between oxygen anomaly and 35S activity in sulfate. 1. Lal D., P. K. Malhotra, and B. Peters, On the production of radioisotopes in the atmosphere by cosmic radiation and their application in meteorology, J. Atmos. AndTerrest. Phys. 12, 306, 1958 2. Brother, L.A., G. Dominguez, A. Abramian, A. Corbin

  3. Angiotensin II-derived reactive oxygen species underpinning the processing of the cardiovascular reflexes in the medulla oblongata.

    PubMed

    Braga, Valdir A; Colombari, Eduardo; Jovita, Mariana G

    2011-08-01

    The brainstem is a major site in the central nervous system involved in the processing of the cardiovascular reflexes such as the baroreflex and the peripheral chemoreflex. The nucleus tractus solitarius and the rostral ventrolateral medulla are 2 important brainstem nuclei, and they play pivotal roles in autonomic cardiovascular regulation. Angiotensin II is one of the neurotransmitters involved in the processing of the cardiovascular reflexes within the brainstem. It is well-known that one of the mechanisms by which angiotensin II exerts its effect is via the activation of pathways that generate reactive oxygen species (ROS). In the central nervous system, ROS are reported to be involved in several pathological diseases such as hypertension, heart failure and sleep apnea. However, little is known about the role of ROS in the processing of the cardiovascular reflexes within the brainstem. The present review mainly discussed some recent findings documenting a role for ROS in the processing of the baroreflex and the peripheral chemoreflex in the brainstem.

  4. Monitoring of anoxic/oxic process for nitrogen and chemical oxygen demand removal using fuzzy neural networks.

    PubMed

    Huang, Mingzhi; Wan, Jinquan; Ma, Yongwen

    2009-07-01

    In this paper, a software sensor based on a fuzzy neural network (FNN) approach was proposed for the real-time estimation of nutrient concentrations and overcoming the problem of delayed measurements. To improve the FNN performance, fuzzy subtractive clustering was used to identify the model's architecture and optimize the fuzzy rule; meanwhile, a split network structure, applied separately for anaerobic and aerobic conditions, was used with dynamic modeling methods, such as an auto-regressive model with exogenous inputs. The proposed methodology was applied to a bench-scale anoxic/oxic process for biological nitrogen removal. It was possible to partially overcome the extrapolation problem of FNNs with the aid of multi-way principal component analysis, because it has the ability to detect abnormal situations, which could generate extrapolation. Real-time estimation of chemical oxygen demand, nitrate, and ammonium concentrations based on the model was successfully carried out with the simple online information of the anoxic/oxic system.

  5. Electrocoagulation process to Chemical and Biological Oxygen Demand treatment from carwash grey water in Ahvaz megacity, Iran.

    PubMed

    Mohammadi, Mohammad Javad; Takdastan, Afshin; Jorfi, Sahand; Neisi, Abdolkazem; Farhadi, Majid; Yari, Ahmad Reza; Dobaradaran, Sina; Khaniabadi, Yusef Omidi

    2017-04-01

    In this work, we present the result of an electric coagulation process with iron and aluminum electrodes for removal of chemical and biological oxygen demand (COD and BOD) from grey water in different car washes of Ahvaz, Iran. Nowadays, one of the important dangerous that can contaminate water resources for drinking, agriculture and industrial is Car wash effluent [1,2]. In this study, initial COD and BOD concentration, pH of the solution, voltage power and reaction time was investigated. The concentration level of remaining COD and BOD in samples was measured, using DR/5000 UV-vis HACH spectrophotometer [3,4]. The effects of contact time, initial pH, electrical potential and voltage data on removal of COD and BOD were presented. Statistical analysis of the data was carried out using Special Package for Social Sciences (SPSS 16).

  6. Hydrogen and oxygen from water. III - Evaluation of a hybrid process

    NASA Astrophysics Data System (ADS)

    Diver, R. B.; Fletcher, E. A.

    1980-07-01

    The paper presents a hybrid process which produces simultaneously mechanical power and hydrogen from water by the use of solar energy. Solar energy in this model is collected at very high and at near ambient temperatures. This model uses heat rejected from the high-temperature heat exchanger in a Rankine or other conventional heat engine to operate the pumps and to produce mechanical power; the heat pump is eliminated and flat solar collectors are used to vaporize the water. It was found that reactor-separators will require membranes with Knudsen numbers of 25; the heat exchanger specifications, the heat engine, and pumps where hydrogen is compressed to 50 atm for long-range pipeline transport are discussed. It was concluded that the results given here for a device which operated at 2800 K with an upstream pressure of 0.2 atm, and which receives a net solar energy input from the collector of 1824 kW is feasible.

  7. Cold plasma processing of local planetary ores for oxygen and metallurgically important metals

    NASA Technical Reports Server (NTRS)

    Lynch, D. C.; Bullard, D.; Ortega, R.

    1991-01-01

    The utilization of a cold or nonequilibrium plasma in chlorination processing is discussed. Titanium dioxide (TiO2) was successfully chlorinated at temperatures between 700 and 900 C without the aid of carbon. In addition to these initial experiments, a technique was developed for determining the temperature of a specimen in a plasma. Development of that technique has required evaluating the emissivity of TiO2, ZrO2, and FeOTiO2 and analyzing the specimen temperature in a plasma as a function of both power absorbed by the plasma and the pressure of the plasma. The mass spectrometer was also calibrated with TiCl4 and CCl4 vapor.

  8. Conversion of Methane to Hydrogen in a Reversible Flow Reactor in the Process of Filtration Combustion of Fuel Mixtures Enriched with Oxygen

    NASA Astrophysics Data System (ADS)

    Dmitrenko, Yu. M.; Klyovan, R. A.

    2013-11-01

    This paper considers the process of partial oxidation of methane to syngas in a reversible flow reactor in the process of filtration combustion of fuel mixtures enriched with oxygen in an inert porous medium. Experimental studies have been made of the influence of the volume concentration of oxygen in the initial fuel mixture on the basic parameters of the conversion process — the maximum temperature in the combustion wave and the composition of reaction products. Investigations have been carried out for fuel mixtures having different calorific values under the same filtration conditions. It has been shown that the addition of oxygen to the initial methane-air mixture permits increasing considerably the efficiency of the conversion process.

  9. Comparative techno-economic analysis and process design for indirect liquefaction pathways to distillate-range fuels via biomass-derived oxygenated intermediates upgrading

    SciTech Connect

    Tan, Eric C. D.; Snowden-Swan, Lesley J.; Talmadge, Michael; Dutta, Abhijit; Jones, Susanne; Ramasamy, Karthikeyan K.; Gray, Michel; Dagle, Robert; Padmaperuma, Asanga; Gerber, Mark; Sahir, Asad H.; Tao, Ling; Zhang, Yanan

    2016-09-27

    This paper presents a comparative techno-economic analysis (TEA) of five conversion pathways from biomass to gasoline-, jet-, and diesel-range hydrocarbons via indirect liquefaction with a specific focus on pathways utilizing oxygenated intermediates. The four emerging pathways of interest are compared with one conventional pathway (Fischer-Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include biomass-to-syngas via indirect gasification, syngas clean-up, conversion of syngas to alcohols/oxygenates followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. Conversion of biomass-derived syngas to oxygenated intermediates occurs via three different pathways, producing: (i) mixed alcohols over a MoS2 catalyst, (ii) mixed oxygenates (a mixture of C2+ oxygenated compounds, predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate) using an Rh-based catalyst, and (iii) ethanol from syngas fermentation. This is followed by the conversion of oxygenates/alcohols to fuel-range olefins in two approaches: (i) mixed alcohols/ethanol to 1-butanol rich mixture via Guerbet reaction, followed by alcohol dehydration, oligomerization, and hydrogenation, and (ii) mixed oxygenates/ethanol to isobutene rich mixture and followed by oligomerization and hydrogenation. The design features a processing capacity of 2000 tonnes/day (2205 short tons) of dry biomass. The minimum fuel selling prices (MFSPs) for the four developing pathways range from 3.40 dollars to 5.04 dollars per gasoline-gallon equivalent (GGE), in 2011 US dollars. Sensitivity studies show that MFSPs can be improved with co-product credits and are comparable to the commercial Fischer-Tropsch benchmark ($3.58/GGE). Altogether, this comparative TEA study documents potential economics for the developmental biofuel pathways via mixed oxygenates.

  10. Comparative techno-economic analysis and process design for indirect liquefaction pathways to distillate-range fuels via biomass-derived oxygenated intermediates upgrading

    DOE PAGES

    Tan, Eric C. D.; Snowden-Swan, Lesley J.; Talmadge, Michael; ...

    2016-09-27

    This paper presents a comparative techno-economic analysis (TEA) of five conversion pathways from biomass to gasoline-, jet-, and diesel-range hydrocarbons via indirect liquefaction with a specific focus on pathways utilizing oxygenated intermediates. The four emerging pathways of interest are compared with one conventional pathway (Fischer-Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include biomass-to-syngas via indirect gasification, syngas clean-up, conversion of syngas to alcohols/oxygenates followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. Conversion of biomass-derived syngas to oxygenated intermediates occurs via three different pathways, producing: (i) mixedmore » alcohols over a MoS2 catalyst, (ii) mixed oxygenates (a mixture of C2+ oxygenated compounds, predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate) using an Rh-based catalyst, and (iii) ethanol from syngas fermentation. This is followed by the conversion of oxygenates/alcohols to fuel-range olefins in two approaches: (i) mixed alcohols/ethanol to 1-butanol rich mixture via Guerbet reaction, followed by alcohol dehydration, oligomerization, and hydrogenation, and (ii) mixed oxygenates/ethanol to isobutene rich mixture and followed by oligomerization and hydrogenation. The design features a processing capacity of 2000 tonnes/day (2205 short tons) of dry biomass. The minimum fuel selling prices (MFSPs) for the four developing pathways range from 3.40 dollars to 5.04 dollars per gasoline-gallon equivalent (GGE), in 2011 US dollars. Sensitivity studies show that MFSPs can be improved with co-product credits and are comparable to the commercial Fischer-Tropsch benchmark ($3.58/GGE). Altogether, this comparative TEA study documents potential economics for the developmental biofuel pathways via mixed oxygenates.« less

  11. Comparative techno-economic analysis and process design for indirect liquefaction pathways to distillate-range fuels via biomass-derived oxygenated intermediates upgrading

    SciTech Connect

    Tan, Eric C. D.; Snowden-Swan, Lesley J.; Talmadge, Michael; Dutta, Abhijit; Jones, Susanne; Ramasamy, Karthikeyan K.; Gray, Michel; Dagle, Robert; Padmaperuma, Asanga; Gerber, Mark; Sahir, Asad H.; Tao, Ling; Zhang, Yanan

    2016-09-27

    This paper presents a comparative techno-economic analysis (TEA) of five conversion pathways from biomass to gasoline-, jet-, and diesel-range hydrocarbons via indirect liquefaction with a specific focus on pathways utilizing oxygenated intermediates. The four emerging pathways of interest are compared with one conventional pathway (Fischer-Tropsch) for the production of the hydrocarbon blendstocks. The processing steps of the four emerging pathways include biomass-to-syngas via indirect gasification, syngas clean-up, conversion of syngas to alcohols/oxygenates followed by conversion of alcohols/oxygenates to hydrocarbon blendstocks via dehydration, oligomerization, and hydrogenation. Conversion of biomass-derived syngas to oxygenated intermediates occurs via three different pathways, producing: (i) mixed alcohols over a MoS2 catalyst, (ii) mixed oxygenates (a mixture of C2+ oxygenated compounds, predominantly ethanol, acetic acid, acetaldehyde, ethyl acetate) using an Rh-based catalyst, and (iii) ethanol from syngas fermentation. This is followed by the conversion of oxygenates/alcohols to fuel-range olefins in two approaches: (i) mixed alcohols/ethanol to 1-butanol rich mixture via Guerbet reaction, followed by alcohol dehydration, oligomerization, and hydrogenation, and (ii) mixed oxygenates/ethanol to isobutene rich mixture and followed by oligomerization and hydrogenation. The design features a processing capacity of 2000 tonnes/day (2205 short tons) of dry biomass. The minimum fuel selling prices (MFSPs) for the four developing pathways range from 3.40 dollars to 5.04 dollars per gasoline-gallon equivalent (GGE), in 2011 US dollars. Sensitivity studies show that MFSPs can be improved with co-product credits and are comparable to the commercial Fischer-Tropsch benchmark ($3.58/GGE). Altogether, this comparative TEA study documents potential economics for the developmental biofuel pathways via mixed oxygenates.

  12. Effect of a reactive oxygen species-generating system for control of airborne microorganisms in a meat-processing environment.

    PubMed

    Patel, J R; Nou, X

    2008-09-01

    The effectiveness of reactive oxygen species (ROS)-generating AirOcare equipment on the reduction of airborne bacteria in a meat-processing environment was determined. Serratia marcescens and lactic acid bacteria (Lactococcus lactis subsp. lactis and Lactobacillus plantarum) were used to artificially contaminate the air via a six-jet Collison nebulizer. Air in the meat-processing room was sampled immediately after aerosol generation and at various predetermined times at multiple locations by using a Staplex 6 stage air sampler. Approximately a 4-log reduction of the aerial S. marcescens population was observed within 2 h of treatment (P < 0.05) compared to a 1-log reduction in control samples. The S. marcescens populations reduced further by approximately 4.5 log after 24 h of exposure to ROS treatment. Approximately 3-log CFU/m3 reductions in lactic acid bacteria were observed following 2-h ROS exposure. Further ROS exposure reduced lactic acid bacteria in the air; however, the difference in their survival after 24 h of exposure was not significantly different from that observed with the control treatment. S. marcescens bacteria were more sensitive to ROS treatment than the lactic acid bacteria. These findings reveal that ROS treatment using the AirOcare unit significantly reduces airborne S. marcescens and lactic acid bacteria in meat-processing environments within 2 h.

  13. Role of DDL processes during electrolytic reduction of Cu(II) in a low oxygen environment.

    PubMed

    Brosky, Rebekah T; Pamukcu, Sibel

    2013-11-15

    Heavy metals typically accumulate in reduced bottom sediments after being discharged into waterways by industrial and municipal processes. A laboratory experiment was conducted in order to determine if abundance of clay in the bottom sediments of a Cu-contaminated aqueous ecosystem could enhance electrolytic reduction of the heavy metal. Cu(NO3)2 · 2.5H2O was added to simulate a moderately contaminated system with 650 μg Cu/ml kaolinite clay-water slurry. A constant electrical potential of 1.0 V/cm was applied across platinum wire electrodes inserted into the continuously stirred system for four days while the system ORP(2) was monitored and periodic sub-samples were taken for analysis. The electrical as well as the chemical results indicate that the quantity of Cu(II) being reduced to Cu(I), especially within the aqueous phase, is increased within the first 48 h of experimentation by the presence of kaolinite clay up to 0.05 mg clay/l slurry.

  14. Ion beam etching process for high-density spintronic devices and its damage recovery by the oxygen showering post-treatment process

    NASA Astrophysics Data System (ADS)

    Jeong, Junho; Endoh, Tetsuo

    2017-04-01

    The electric short fail trend of the perpendicular magnetic tunnel junctions (p-MTJs) caused by the ion beam etching (IBE) process is studied at various ion beam angles and cell-to-cell space widths. The number of electric short fails increases markedly at an ion beam angle greater than 35° and a cell-to-cell space width less than 30 nm at the assumed MTJ height including a hard mask (HM) of 20 nm. In order to recover these electric short fails, we propose the selective oxidation process called the oxygen showering post-treatment (OSP). By the OSP process, the number of electric short fails in sub-30-nm-spaced MTJ arrays is reduced from 25 to 0.8%, and the magnetoresistance (MR) is increased from 99 to 120%. By this result, we can verify that the damaged layer is recovered successfully by the OSP, and that the OSP can be a universal post-treatment process even beyond the 20 nm design rule for use in both reactive ion etching and IBE schemes.

  15. Age-related increase of reactive oxygen generation in the brains of mammals and birds: is reactive oxygen a signaling molecule to determine the aging process and life span?

    PubMed

    Sasaki, Toru; Unno, Keiko; Tahara, Shoichi; Kaneko, Takao

    2010-07-01

    Since Harman proposed the "free-radical theory of aging", oxidative stress has been postulated to be a major causal factor of senescence. The accumulation of oxidative stress-induced oxidatively modified macromolecules, including protein, DNA and lipid, were found in tissues during the aging process; however, it is not necessarily clear which factor is more critical, an increase in endogenous reactive oxygen and/or a decrease in anti-oxidative defense, to the age-related increase in oxidative damage. To clarify the increasing production of reactive oxygen with age, we examined reactive oxygen-dependent chemiluminescent (CL) signals in ex vivo brain slices prepared from different-aged animal brains during hypoxia-reoxygenation treatment using a novel photonic imaging method. The CL signal was intensified during reoxygenation. The signals in SAMP10 (short-life strain) and SAMR1 (control) brain slices increased with aging. The slope of the increase of CL intensity with age in P10 was steeper than in R1. Age-dependent increase of CL intensity was also observed in C57BL/6 mice, Wistar rats and pigeons; however, superoxide dismutase (SOD) activity in the brain did not change with age. These results suggest that reactive oxygen production itself increased with aging. The rate of age-related increases of CL intensity was inversely related to the maximum lifespan of animals. We speculate that reactive oxygen might be a signaling molecule and its levels in tissue might determine the aging process and lifespan. Decelerating age-related increases of reactive oxygen production are expected to be a potent strategy for anti-aging interventions.

  16. Co-processing CH4 and oxygenates on Mo/H-ZSM-5: 2. CH4-CO2 and CH4-HCOOH mixtures.

    PubMed

    Bedard, Jeremy; Hong, Do-Young; Bhan, Aditya

    2013-08-07

    Co-processing of formic acid or carbon dioxide with CH4 (FA/CH4 = 0.01-0.03 and CO2/CH4 = 0.01-0.03) on Mo/H-ZSM-5 catalysts at 950 K with the prospect of kinetically coupling dehydrogenation and deoxygenation cycles results instead in a two-zone, staged bed reactor configuration consisting of upstream oxygenate/CH4 reforming and downstream CH4 dehydroaromatization. The addition of an oxygenate co-feed (oxygenate/CH4 = 0.01-0.03) causes oxidation of the active molybdenum carbide catalyst while producing CO and H2 until completely converted. Forward rates of C6H6 synthesis are unaffected by the introduction of an oxygenate co-feed after rigorously accounting for the thermodynamic reversibility caused by the H2 produced in oxygenate reforming reactions and the fraction of the active catalyst deemed unavailable for CH4 DHA. All effects of co-processing oxygenates with CH4 can be construed in terms of an approach to equilibrium.

  17. Diffusion and aggregation process of oxygen embedded around an amorphous/crystal interface of Si(001) studied by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi

    2017-05-01

    I performed empirical molecular dynamics (MD) simulations to understand the peculiar migration behavior of oxygen embedded in an amorphous Si (a-Si) layer near the crystal/amorphous (c/a) Si interface and investigated the time evolution of the atomic configuration at high temperatures from 1200 to 1500 K. The previously proposed sweeping effect, which is demonstrated in terms of the oxygen migration and precipitation in silicon taking place along the moving c/a interface, was definitely confirmed in this MD simulation. [Hoshino et al., J. Phys. D: Appl. Phys. 49, 315106 (2016)] In the present study, I reproducibly found the theoretical evidence of the novel sweeping and aggregation phenomenon of oxygen occurring in the recrystallization process of a-Si. The temperature-dependence revealed that the relationship between the displacement velocity of the oxygen and the c/a interface plays an important role in interpreting the behavior. The oxide precipitations in the recrystallized Si as well as the sweeping effect were well reproduced in the simulation in which the systems containing several oxygen atoms were assumed. These facts significantly well explain and support my interpretation in the previous papers reported on the synthesis mechanism of the ultrathin silicon-on-insulator/buried oxide structure prepared by low-energy implantation followed by relatively low temperature annealing, compared to the ordinary separation by the implanted oxygen process.

  18. Oxygen Therapy

    MedlinePlus

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

  19. Hybrid artificial neural network genetic algorithm technique for modeling chemical oxygen demand removal in anoxic/oxic process.

    PubMed

    Ma, Yongwen; Huang, Mingzhi; Wan, Jinquan; Hu, Kang; Wang, Yan; Zhang, Huiping

    2011-01-01

    In this paper, a hybrid artificial neural network (ANN) - genetic algorithm (GA) numerical technique was successfully developed to deal with complicated problems that cannot be solved by conventional solutions. ANNs and Gas were used to model and simulate the process of removing chemical oxygen demand (COD) in an anoxic/oxic system. The minimization of the error function with respect to the network parameters (weights and biases) has been considered as training of the network. Real-coded genetic algorithm was used to train the network in an unsupervised manner. Meanwhile the important process parameters, such as the influent COD (COD(in)), reflux ratio (R(r)), carbon-nitrogen ratio (C/N) and the effluent COD (COD(out)) were considered. The result shows that compared with the performance of ANN model, the performance of the GA-ANN (genetic algorithm - artificial neural network) network was found to be more impressive. Using ANN, the mean absolute percentage error (MAPE), mean squared error (MSE) and correlation coefficient (R) were 9.33×10(-4), 2.82 and 0.98596, respectively; while for the GA-ANN, they were converged to be 4.18×10(-4), 1.12 and 0.99476, respectively.

  20. Role of nano and micron-sized inclusions on the oxygen controlled preform optimized infiltration growth processed YBCO superconductors

    NASA Astrophysics Data System (ADS)

    Pavan Kumar Naik, S.; Bai, V. Seshu

    2017-02-01

    In the present work, with the aim of improving the local flux pinning at the unit cell level in the YBa2Cu3O7-δ (YBCO) bulk superconductors, 20 wt% of nanoscale Sm2O3 and micron sized (Nd, Sm, Gd)2BaCuO5 secondary phase particles were added to YBCO and processed in oxygen controlled preform optimized infiltration growth process. Nano Dispersive Sol Casting method is employed to homogeneously distribute the nano Sm2O3 particles of 30-50 nm without any agglomeration in the precursor powder. Microstructural investigations on doped samples show the chemical fluctuations as annuli cores in the 211 phase particles. The introduction of mixed rare earth elements at Y-site resulted in compositional fluctuations in the superconducting matrix. The associated lattice mismatch defects have provided flux pinning up to large magnetic fields. Magnetic field dependence of current density (Jc(H)) at different temperatures revealed that the dominant pinning mechanism is caused by spatial variations of critical temperatures, due to the spatial fluctuations in the matrix composition. As the number of rare earth elements increased in the YBCO, the peak field position in the scaling of the normalized pinning force density (Fp/Fp max) significantly gets shifted towards the higher fields. The curves of Jc(H) and Fp/Fp max at different temperatures clearly indicate the LRE substitution for LRE' or Ba-sites for δTc pinning.

  1. Heart Rate and Oxygen Uptake Kinetics in Type 2 Diabetes Patients - A Pilot Study on the Influence of Cardiovascular Medication on Regulatory Processes.

    PubMed

    Koschate, Jessica; Drescher, Uwe; Baum, Klaus; Brinkmann, Christian; Schiffer, Thorsten; Latsch, Joachim; Brixius, Klara; Hoffmann, Uwe

    2017-02-15

    The aim of this pilot study was to investigate whether there are differences in heart rate and oxygen uptake kinetics in type 2 diabetes patients, considering their cardiovascular medication. It was hypothesized that cardiovascular medication would affect heart rate and oxygen uptake kinetics and that this could be detected using a standardized exercise test. 18 subjects were tested for maximal oxygen uptake. Kinetics were measured in a single test session with standardized, randomized moderate-intensity work rate changes. Time series analysis was used to estimate kinetics. Greater maxima in cross-correlation functions indicate faster kinetics. 6 patients did not take any cardiovascular medication, 6 subjects took peripherally acting medication and 6 patients were treated with centrally acting medication. Maximum oxygen uptake was not significantly different between groups. Significant main effects were identified regarding differences in muscular oxygen uptake kinetics and heart rate kinetics. Muscular oxygen uptake kinetics were significantly faster than heart rate kinetics in the group with no cardiovascular medication (maximum in cross-correlation function of muscular oxygen uptake vs. heart rate; 0.32±0.08 vs. 0.25±0.06; p=0.001) and in the group taking peripherally acting medication (0.34±0.05 vs. 0.28±0.05; p=0.009) but not in the patients taking centrally acting medication (0.28±0.05 vs. 0.30±0.07; n.s.). It can be concluded that regulatory processes for the achievement of a similar maximal oxygen uptake are different between the groups. The used standardized test provided plausible results for heart rate and oxygen uptake kinetics in a single measurement session in this patient group.

  2. Transient Oxygen/Glucose Deprivation Causes a Delayed Loss of Mitochondria and Increases Spontaneous Calcium Signaling in Astrocytic Processes

    PubMed Central

    O'Donnell, John C.; Jackson, Joshua G.

    2016-01-01

    Recently, mitochondria have been localized to astrocytic processes where they shape Ca2+ signaling; this relationship has not been examined in models of ischemia/reperfusion. We biolistically transfected astrocytes in rat hippocampal slice cultures to facilitate fluorescent confocal microscopy, and subjected these slices to transient oxygen/glucose deprivation (OGD) that causes delayed excitotoxic death of CA1 pyramidal neurons. This insult caused a delayed loss of mitochondria from astrocytic processes and increased colocalization of mitochondria with the autophagosome marker LC3B. The losses of neurons in area CA1 and mitochondria in astrocytic processes were blocked by ionotropic glutamate receptor (iGluR) antagonists, tetrodotoxin, ziconotide (Ca2+ channel blocker), two inhibitors of reversed Na+/Ca2+ exchange (KB-R7943, YM-244769), or two inhibitors of calcineurin (cyclosporin-A, FK506). The effects of OGD were mimicked by NMDA. The glutamate uptake inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]amino]phenyl]methoxy]-l-aspartate increased neuronal loss after OGD or NMDA, and blocked the loss of astrocytic mitochondria. Exogenous glutamate in the presence of iGluR antagonists caused a loss of mitochondria without a decrease in neurons in area CA1. Using the genetic Ca2+ indicator Lck-GCaMP-6S, we observed two types of Ca2+ signals: (1) in the cytoplasm surrounding mitochondria (mitochondrially centered) and (2) traversing the space between mitochondria (extramitochondrial). The spatial spread, kinetics, and frequency of these events were different. The amplitude of both types was doubled and the spread of both types changed by ∼2-fold 24 h after OGD. Together, these data suggest that pathologic activation of glutamate transport and increased astrocytic Ca2+ through reversed Na+/Ca2+ exchange triggers mitochondrial loss and dramatic increases in Ca2+ signaling in astrocytic processes. SIGNIFICANCE STATEMENT Astrocytes, the most abundant cell type in the

  3. Transient Oxygen/Glucose Deprivation Causes a Delayed Loss of Mitochondria and Increases Spontaneous Calcium Signaling in Astrocytic Processes.

    PubMed

    O'Donnell, John C; Jackson, Joshua G; Robinson, Michael B

    2016-07-06

    Recently, mitochondria have been localized to astrocytic processes where they shape Ca(2+) signaling; this relationship has not been examined in models of ischemia/reperfusion. We biolistically transfected astrocytes in rat hippocampal slice cultures to facilitate fluorescent confocal microscopy, and subjected these slices to transient oxygen/glucose deprivation (OGD) that causes delayed excitotoxic death of CA1 pyramidal neurons. This insult caused a delayed loss of mitochondria from astrocytic processes and increased colocalization of mitochondria with the autophagosome marker LC3B. The losses of neurons in area CA1 and mitochondria in astrocytic processes were blocked by ionotropic glutamate receptor (iGluR) antagonists, tetrodotoxin, ziconotide (Ca(2+) channel blocker), two inhibitors of reversed Na(+)/Ca(2+) exchange (KB-R7943, YM-244769), or two inhibitors of calcineurin (cyclosporin-A, FK506). The effects of OGD were mimicked by NMDA. The glutamate uptake inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]amino]phenyl]methoxy]-l-aspartate increased neuronal loss after OGD or NMDA, and blocked the loss of astrocytic mitochondria. Exogenous glutamate in the presence of iGluR antagonists caused a loss of mitochondria without a decrease in neurons in area CA1. Using the genetic Ca(2+) indicator Lck-GCaMP-6S, we observed two types of Ca(2+) signals: (1) in the cytoplasm surrounding mitochondria (mitochondrially centered) and (2) traversing the space between mitochondria (extramitochondrial). The spatial spread, kinetics, and frequency of these events were different. The amplitude of both types was doubled and the spread of both types changed by ∼2-fold 24 h after OGD. Together, these data suggest that pathologic activation of glutamate transport and increased astrocytic Ca(2+) through reversed Na(+)/Ca(2+) exchange triggers mitochondrial loss and dramatic increases in Ca(2+) signaling in astrocytic processes. Astrocytes, the most abundant cell type in the brain

  4. Isotopic Responses to Processes Related to Oxygen Cycling During Diel Studies in the San Joaquin River, California

    NASA Astrophysics Data System (ADS)

    Silva, S. R.; Young, M. B.; Kendall, C.; Dahlgren, R. A.; Stringfellow, W. T.

    2008-12-01

    Episodic conditions of low dissolved oxygen (DO) occurring in the San Joaquin River deep water shipping channel (DWSC) at Stockton, California inhibit salmon migration during late summer and early fall. As part of a CALFED study to determine the sources of organic matter and nutrients related to the low DO problem, four diel studies were undertaken: two at the DWSC in 2006 and 2007 and two about 40 miles upstream at Crows Landing in 2005 and 2007. The purpose of the diel studies was to gain a better understanding of the transient processes controlling oxygen concentrations and to compare the range of diel variations of various isotopic measurements with those collected on a less frequent basis. The DWSC is dredged to about 40 feet deep and is tidally influenced. The river at Crows Landing is about 5 feet deep and well above tidal influence. Crows Landing was therefore used for comparison with the DWSC as a hydrologically less complicated portion of the river that has not been dredged. Samples were collected at two hour intervals from a one meter depth at Crows Landing. Values of d18O-DO, DO concentrations and pH showed a strong diel response linked to photosynthesis and the effects of bacterial respiration. The d13C of POM (composed mostly of algae) increased at night as expected while the C:N ratio of POM unexpectedly decreases, possibly due to an increased presence of zooplankton at night. Opposing trends of d15N and d18O of nitrate unrelated to a diurnal cycle suggest that source mixing was largely responsible for nitrate composition and concentration through much of the study. Samples were collected at two hour intervals from 1, 5, and 8 meter depths at Rough and Ready Island in the DWSC. Isotope and concentration data showed a distinct diurnal photosynthetic response at the 1 meter depth only. The 2007 DIC and POM isotopic data suggested that nitrification was significantly responsible for oxygen consumption through the duration of the study. The particularly

  5. Dissolved oxygen as a factor influencing nitrogen removal rates in a one-stage system with partial nitritation and Anammox process.

    PubMed

    Cema, G; Płaza, E; Trela, J; Surmacz-Górska, J

    2011-01-01

    A biofilm system with Kaldnes biofilm carrier was used in these studies to cultivate bacteria responsible for both partial nitritation and Anammox processes. Due to co-existence of oxygen and oxygen-free zones within the biofilm depth, both processes can occur in a single reactor. Oxygen that inhibits the Anammox process is consumed in the outer layer of the biofilm and in this way Anammox bacteria are protected from oxygen. The impact of oxygen concentration on nitrogen removal rates was investigated in the pilot plant (2.1 m3), supplied with reject water from the Himmerfjärden Waste Water Treatment Plant. The results of batch tests showed that the highest nitrogen removal rates were obtained for a dissolved oxygen (DO) concentration around 3 g O2 m(-3) At a DO concentration of 4 g O2 m(-3), an increase of nitrite and nitrate nitrogen concentrations in the batch reactor were observed. The average nitrogen removal rate in the pilot plant during a whole operating period oscillated around 1.3 g N m(-2)d(-1) (0.3 +/- 0.1 kg N m(-3)d(-1)) at the average dissolved oxygen concentration of 2.3 g O2 m(-3). The maximum value of a nitrogen removal rate amounted to 1.9 g N m(-2)d(-1) (0.47 kg N m(-3)d(-1)) and was observed for a DO concentration equal to 2.5 g O2 m(-3). It was observed that increase of biofilm thickness during the operational period, had no influence on nitrogen removal rates in the pilot plant.

  6. Comparative toxicities of oxygen, ozone, chlorine dioxide, and chlorine bleaching filtrates - microtox toxicities of raw and processed filtrates

    SciTech Connect

    Ard, T.A.; McDonough, T.J.

    1995-12-31

    It has claimed that effluents from the bleaching of kraft pulp with chlorine and its compounds have deleterious effects on the aquatic environment. It has been further suggested that bleaching without the use of chlorine or its compounds will produce innocuous effluents. To obtain information on the validity of these claims, we have conducted a laboratory study of the toxicity of filtrates from chlorine-based and nonchlorine bleaching processes. We have also examined two related issues. The first is whether any toxicants generated during bleaching are rendered harmless (by neutralization, storage, and biological treatment) before being discharged to the environment. The second related issue is whether any toxicity observed in mill effluents actually originates in the bleaching process, as opposed to being due to raw material components or compounds formed during the pulping step that precedes bleaching. Several conclusions were drawn from this study. (1) There is a background level of toxicity which originates in the oxygen stage, process steps prior to bleaching, or in the wood raw material. It is decreased by neutralization and storage, but residual toxicity may still be detected after two weeks. (2) If the sum of the first and second stage toxicities is taken as an indicator of overall toxicity, the untreated filtrates may be ranked as follows: Control (Background) > D(EO) > Z(EO) > C(EO). However, these toxicities are of no importance in regard to environmental effects because of their ephemeral nature and the likelihood of their being reduced or eliminated prior to effluent discharge. Evidence for this statement is the ease with which all except the C(EO) were detoxified by neutralization and storage. (3) After neutralization and storage for two weeks at room temperature the ranking of toxicities becomes: C(EO) > D(EO) > Z(EO) > Background. The last three are similar in magnitude.

  7. Processes for the "vital effect" of Porites corals as revealed by microanalysis of oxygen, carbon and boron isotopic compositions

    NASA Astrophysics Data System (ADS)

    Rollion-Bard, C.; Chaussidon, M.; France-Lanord, C.

    2003-04-01

    Since the discovery by Knutson et al. (1972) of annual banding in massive corals, they have intensively been used to provide paleoclimate reconstructions. The oxygen isotopic composition (18O) of coral aragonite skeletons is a function of sea surface temperature (SST) and salinity (SSS) through the 18O of the seawater in which the carbonate precipitates and pH of the calcifying fluid. Carbon cycle in hermatypic corals is relatively complex because of the interaction between symbiotic algae (zooxanthellae) and coral (Goreau, 19777). Coral 13C seems to be under influence of the ratio between algae photosynthesis and algae and coral respiration (Swart, 1983). The carbonate deposited by some foraminifera and scleractinian corals is depleted 13C and 18O relative to isotope equilibrium with ambient seawater. This deviation of the biogenic carbonate - water fractionation from the inorganic fractionation is called the "vital effect" (Urey et al., 1951). Different explanations for the vital effect are proposed: (1) McConnaughey (1989) attributes the coral disequilibria to kinetic effects. (2) Spero et al. (1997) and Zeebe (1999) consider that the carbonate depletion in 18O is due to [CO32-] or pH variations. The carbon isotopic disequilibrium would be due, in this case, to 13C depleted metabolic DIC incorporation coming from the respiration. The micrometer scale analysis by ion microprobe of B, C and O isotopic compositions can allow to better understand responsible process(es) of the vital effect and the existence of a great diversity in 18O - SST calibrations for differents colonies of the same species. These analyses show that 11B and 18O of coral skeleton have a great variability at micrometer scale (10 and 12 , respectively), whereas 13C have no so important variations and that all the values are in the range of 13C measured by "classical" method (acid digestion and mass spectrometry). Thus the in

  8. Effect of oxygen content of Nd-Fe-B sintered magnet on grain boundary diffusion process of DyH2 dip-coating

    NASA Astrophysics Data System (ADS)

    Bae, Kyoung-Hoon; Lee, Seong-Rae; Kim, Hyo-Jun; Lee, Min-Woo; Jang, Tae-Suk

    2015-11-01

    We investigated the effect of oxygen content on the microstructural and magnetic properties of a DyH2 dip-coated Nd-Fe-B sintered magnet. When the magnet had a low oxygen content (1500 ppm), the volume and size of the rare-earth-rich oxide (Nd-Dy-O) phase was reduced, and a uniform and continuous thin Nd-rich grain boundary phase (GBP) was well developed. The grain boundary diffusion depth of Dy increased from 200 to 350 μm with decreasing oxygen content from ˜3000 to 1500 ppm. The coercivity of the low-oxygen magnet increased from 19.98 to 23.59 kOe after grain boundary diffusion process (GBDP) while the remanence reduction was minimized. The formation of an fcc-NdOx Nd-rich phase in the high-oxygen magnet hindered the formation of a Nd-rich triple-junction phase and GBP. In contrast, a metallic dhcp-Nd phase, which was closely related to coercivity enhancement after GBDP, was formed in the low-oxygen magnet.

  9. Seawater-temperature and UV-radiation interaction modifies oxygen consumption, digestive process and growth of an intertidal fish.

    PubMed

    García-Huidobro, M Roberto; Aldana, Marcela; Duarte, Cristian; Galbán-Malagón, Cristóbal; Pulgar, José

    2017-08-01

    UV-radiation (UVR) and temperatures have increased substantially over recent decades in many regions of the world. Both stressors independently have shown to affect the metabolism and growth in fish. However, because increase of both stressors are occurring concomitantly, to better understand their influences on marine species, their combined effects were evaluated. We test the hypothesis that UVR and temperature act synergistically affecting the metabolism, digestive process and growth of an intertidal fish. Two UVR conditions (with and without UVR) and two temperature levels (20° C and 25° C) were used. UVR increase the oxygen consumption and this was associated to opaque feces production. The absorption efficiency was higher without UVR at high temperatures (25 °C) and with UVR at low temperatures (20 °C). Finally, independent of UVR treatment, fish subjected to low temperature have higher biomass than those of high temperature. The interaction between UVR and temperature may influence on the physiology and growth of animals that inhabit in extreme habitats as upper intertidal, it could pose significant functional for aquatic animal survivorship. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Role of oxygen vacancies on the bias illumination stress stability of solution-processed zinc tin oxide thin film transistors

    SciTech Connect

    Liu, Li-Chih; Chen, Jen-Sue E-mail: jsjeng@mail.nutn.edu.tw; Jeng, Jiann-Shing E-mail: jsjeng@mail.nutn.edu.tw

    2014-07-14

    Solution-processed ultra-thin (∼3 nm) zinc tin oxide (ZTO) thin film transistors (TFTs) with a mobility of 8 cm{sup 2}/Vs are obtained with post spin-coating annealing at only 350 °C. The effect of light illumination (at wavelengths of 405 nm or 532 nm) on the stability of TFT transfer characteristics under various gate bias stress conditions (zero, positive, and negative) is investigated. It is found that the ΔV{sub th} (V{sub th}{sup stress} {sup 3400} {sup s − stress} {sup 0} {sup s}) window is significantly positive when ZTO TFTs are under positive bias stress (PBS, ΔV{sub th} = 9.98 V) and positive bias illumination stress (λ = 405 nm and ΔV{sub th} = 6.96 V), but ΔV{sub th} is slightly negative under only light illumination stress (λ = 405 nm and ΔV{sub th} = −2.02 V) or negative bias stress (ΔV{sub th} = −2.27 V). However, the ΔV{sub th} of ZTO TFT under negative bias illumination stress is substantial, and it will efficiently recover the ΔV{sub th} caused by PBS. The result is attributed to the photo-ionization and subsequent transition of electronic states of oxygen vacancies (i.e., V{sub o}, V{sub o}{sup +}, and V{sub o}{sup ++}) in ZTO. A detailed mechanism is discussed to better understand the bias stress stability of solution processed ZTO TFTs.

  11. Human Factors Process Task Analysis Liquid Oxygen Pump Acceptance Test Procedure for the Advanced Technology Development Center

    NASA Technical Reports Server (NTRS)

    Diorio, Kimberly A.

    2002-01-01

    A process task analysis effort was undertaken by Dynacs Inc. commencing in June 2002 under contract from NASA YA-D6. Funding was provided through NASA's Ames Research Center (ARC), Code M/HQ, and Industrial Engineering and Safety (IES). The John F. Kennedy Space Center (KSC) Engineering Development Contract (EDC) Task Order was 5SMA768. The scope of the effort was to conduct a Human Factors Process Failure Modes and Effects Analysis (HF PFMEA) of a hazardous activity and provide recommendations to eliminate or reduce the effects of errors caused by human factors. The Liquid Oxygen (LOX) Pump Acceptance Test Procedure (ATP) was selected for this analysis. The HF PFMEA table (see appendix A) provides an analysis of six major categories evaluated for this study. These categories include Personnel Certification, Test Procedure Format, Test Procedure Safety Controls, Test Article Data, Instrumentation, and Voice Communication. For each specific requirement listed in appendix A, the following topics were addressed: Requirement, Potential Human Error, Performance-Shaping Factors, Potential Effects of the Error, Barriers and Controls, Risk Priority Numbers, and Recommended Actions. This report summarizes findings and gives recommendations as determined by the data contained in appendix A. It also includes a discussion of technology barriers and challenges to performing task analyses, as well as lessons learned. The HF PFMEA table in appendix A recommends the use of accepted and required safety criteria in order to reduce the risk of human error. The items with the highest risk priority numbers should receive the greatest amount of consideration. Implementation of the recommendations will result in a safer operation for all personnel.

  12. Human Factors Process Task Analysis Liquid Oxygen Pump Acceptance Test Procedure for the Advanced Technology Development Center

    NASA Technical Reports Server (NTRS)

    Diorio, Kimberly A.

    2002-01-01

    A process task analysis effort was undertaken by Dynacs Inc. commencing in June 2002 under contract from NASA YA-D6. Funding was provided through NASA's Ames Research Center (ARC), Code M/HQ, and Industrial Engineering and Safety (IES). The John F. Kennedy Space Center (KSC) Engineering Development Contract (EDC) Task Order was 5SMA768. The scope of the effort was to conduct a Human Factors Process Failure Modes and Effects Analysis (HF PFMEA) of a hazardous activity and provide recommendations to eliminate or reduce the effects of errors caused by human factors. The Liquid Oxygen (LOX) Pump Acceptance Test Procedure (ATP) was selected for this analysis. The HF PFMEA table (see appendix A) provides an analysis of six major categories evaluated for this study. These categories include Personnel Certification, Test Procedure Format, Test Procedure Safety Controls, Test Article Data, Instrumentation, and Voice Communication. For each specific requirement listed in appendix A, the following topics were addressed: Requirement, Potential Human Error, Performance-Shaping Factors, Potential Effects of the Error, Barriers and Controls, Risk Priority Numbers, and Recommended Actions. This report summarizes findings and gives recommendations as determined by the data contained in appendix A. It also includes a discussion of technology barriers and challenges to performing task analyses, as well as lessons learned. The HF PFMEA table in appendix A recommends the use of accepted and required safety criteria in order to reduce the risk of human error. The items with the highest risk priority numbers should receive the greatest amount of consideration. Implementation of the recommendations will result in a safer operation for all personnel.

  13. Regulatory Effect of Low-Intensity Optical Radiation on Oxygenation of Blood Irradiated In Vivo and Metabolic Processes

    NASA Astrophysics Data System (ADS)

    Zalesskaya, G. A.; Laskina, O. V.

    2016-03-01

    For three series of blood samples, we have studied the effect of therapeutic doses of low-intensity optical radiation (LOR) on oxygenation parameters of blood irradiated in vivo, and also on the levels of some metabolites: lactate, glucose, cholesterol. The quality of blood oxygenation was assessed using three parameters: the partial pressure of oxygen pVO2, the oxygen saturation of hemoglobin SVO2, and the oxygen level in arterial and venous blood, varying under the influence of low-intensity optical radiation due to photodissociation of hemoglobin/ligand complexes. We have established that during photohemotherapy (PHT), including extracorporeal, supravascular, and intravenous blood irradiation, positive changes occur in the oxygenation parameters and the metabolite levels, while after the courses of PHT have been completed, the individual changes in such parameters in individual patients were both positive and negative. The regulatory effect of PHT was apparent in the tendency toward a decrease in high initial values and an increase in low initial values both for the oxygenation parameters and for the metabolites; but at the doses recommended for use, PHT had a regulatory but still not a normalizing effect.

  14. Solid State Thermal Gradient Processing of YTTRIUM(1) BARIUM(2) COPPER(3) OXYGEN(7-X)/SILVER Superconducting Composite Ribbons

    NASA Astrophysics Data System (ADS)

    Kaforey, Monica L.

    The effect of solid state thermal gradient processing on microstructure was examined experimentally and theoretically. The starting material Y_1Ba_2Cu _3Ag_{15} was used to produce Y_1Ba_2Cu_3O_ {7-x}/Ag superconducting composite ribbons. During the low temperature oxidation stage, internal oxidation resulted in the formation of elemental oxides Y_2O_3, BaO, and CuO in Ag. The low temperature oxidation treatment had a very strong influence on the microstructure of the final ribbon, with the tendency for forming Ag bands being stronger in samples subjected to longer oxidation stage treatments. Ag nodules formed at the surfaces due to stress relief and an Ag band formed at the center of samples due to outward solute diffusion in samples that were completely oxidized. Complete oxidation was achieved by heating the samples in flowing oxygen 5^circC/min to 140 ^circC, 0.5^ circC/min to 420^circ C, and holding for 13 hours. The high temperature transformation stage enabled the elemental oxides to transform to the superconducting oxide Y_1Ba_2Cu_3O _{7-x}. During the high temperature transformation treatment, the Ag nodules on the surface spread out to become a surface band of Ag. Coarsening resulted in an increase in the average oxide particle size and a thickening of the Ag bands as the hold time increased, with temperatures in the range of 890^circ C to 900^circC. The superconducting properties of the composite Y_1Ba_2Cu_3O_ {7-x}/Ag ribbons were tested after oxygenation. The samples were found to contain superconducting Y _1Ba_2Cu_3O_{7 -x} with a critical transition temperature in the range of 86 K to 90 K. The samples were found to be unable to support a supercurrent at either 77 K or 4.2 K. The use of solid state thermal gradient processing to produce textured Y_1Ba_2Cu _3O_{7-x}/Ag composite superconducting ribbons during the high temperature transformation stage was investigated experimentally and theoretically. Experimentally, no significant amount of either

  15. Different hydrodynamic processes regulated on water quality (nutrients, dissolved oxygen, and phytoplankton biomass) in three contrasting waters of Hong Kong.

    PubMed

    Zhou, Weihua; Yuan, Xiangcheng; Long, Aimin; Huang, Hui; Yue, Weizhong

    2014-03-01

    The subtropical Hong Kong (HK) waters are located at the eastern side of the Pearl River Estuary. Monthly changes of water quality, including nutrients, dissolved oxygen (DO), and phytoplankton biomass (Chl-a) were routinely investigated in 2003 by the Hong Kong Environmental Protection Department in three contrasting waters of HK with different prevailing hydrodynamic processes. The western, eastern, and southern waters were mainly dominated by nutrient-replete Pearl River discharge, the nutrient-poor coastal/shelf oceanic waters, and mixtures of estuarine and coastal seawater and sewage effluent of Hong Kong, respectively. Acting in response, the water quality in these three contrasting areas showed apparently spatial–temporal variation pattern. Nutrients usually decreased along western waters to eastern waters. In the dry season, the water column was strongly mixed by monsoon winds and tidal currents, which resulted in relatively low Chl-a (<5 μg l(−1)) and high bottom DO (>4 mg l(−1)), suggesting that mixing enhanced the buffering capacity of eutrophication in HK waters. However, in the wet season, surface Chl-a was generally >10 μg l(−1) in southern waters in summer due to halocline and thermohaline stratification, adequate nutrients, and light availability. Although summer hypoxia (DO <2 mg l(−1)) was episodically observed near sewage effluent site and in southern waters induced by vertical stratification, the eutrophication impacts in HK waters were not as severe as expected owing to P limitation and short water residence time in the wet season.

  16. Excitations From Impact: The Affect of CMEs on Venus' Mysterious Oxygen Green Line and Ionospheric Electrons. An Auroral Process?

    NASA Astrophysics Data System (ADS)

    Gray, C.; Chanover, N.; Slanger, T. G.; Molaverdikhani, K.; Häusler, B.; Tellmann, S.; Peter, K.

    2014-12-01

    Observations of nightglow (upper atmospheric emission from atoms and molecules on the nightside of a planet) allow for a multifaceted study of planetary atmospheres. Information on winds, chemistry, and solar effects is gained by observing temporal and spatial variation in nightglow intensity. One of the brightest nightglow features on Earth is the OI (1S-1D) 557.7 nm line (oxygen green line). This emission is primarily due to photodissociation/transport but is also seen in the aurora as electron precipitation. Unlike Earth, the Venusian green line is highly temporally variable. The chemistry and mechanisms responsible are still unknown. We observe the Venusian nightglow before and after solar flares, which produce large amounts of EUV emission, and coronal mass ejections (CMEs) impacts, which inject a large number of higher energy charged particles in the the Venusian atmosphere. We consistently detect green line emission after large charged particles injections from CMEs. However we do not detect the OI (1D) red line at 630.0 nm, which is quenched below 150 km. We propose that the Venusian green line is an auroral-type emission due to electron precipitation and is occurring deep in the atmosphere, near 125 km. To investigate how CMEs and solar flares affect the electron energy, flux, and density in the Venusian nightside atmosphere, we compare data taken by ASPERA and ELS onboard Venus Express (VEX) before and after solar storms. We find that both electron energy and flux increase after CMEs, but only flux increases after solar flares. Additionally, the V1 ionospheric layer at 125 km increases in electron density while the V2 at 150 km decreases in density after CMEs but not after solar flares. We model the nightside Venusian ionosphere using the observed electron energy and fluxes from VEX in an effort to constrain the chemical processes and mechanisms responsible for green line emission. We will present the results of our ground-based observations and modeling.

  17. Role of Nonradiative Defects and Environmental Oxygen on Exciton Recombination Processes in CsPbBr3 Perovskite Nanocrystals.

    PubMed

    Lorenzon, Monica; Sortino, Luca; Akkerman, Quinten; Accornero, Sara; Pedrini, Jacopo; Prato, Mirko; Pinchetti, Valerio; Meinardi, Francesco; Manna, Liberato; Brovelli, Sergio

    2017-06-14

    Lead halide perovskite nanocrystals (NCs) are emerging as optically active materials for solution-processed optoelectronic devices. Despite the technological relevance of tracing rational guidelines for optimizing their performances and stability beyond their intrinsic resilience to structural imperfections, no in-depth study of the role of selective carrier trapping and environmental conditions on their exciton dynamics has been reported to date. Here we conduct spectro-electrochemical (SEC) experiments, side-by-side to oxygen sensing measurements on CsPbBr3 NCs for the first time. We show that the application of EC potentials controls the emission intensity by altering the occupancy of defect states without degrading the NCs. Reductive potentials lead to strong (60%) emission quenching by trapping of photogenerated holes, whereas the concomitant suppression of electron trapping is nearly inconsequential to the emission efficiency. Consistently, oxidizing conditions result in minor (5%) brightening due to suppressed hole trapping, confirming that electron traps play a minor role in nonradiative decay. This behavior is rationalized through a model that links the occupancy of trap sites with the position of the NC Fermi level controlled by the EC potential. Photoluminescence measurements in controlled atmosphere reveal strong quenching by collisional interactions with O2, which is in contrast to the photobrightening effect observed in films and single crystals. This indicates that O2 acts as a scavenger of photoexcited electrons without mediation by structural defects and, together with the asymmetrical SEC response, suggests that electron-rich defects are likely less abundant in nanostructured perovskites than in the bulk, leading to an emission response dominated by direct interaction with the environment.

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

    PubMed

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

    2015-02-01

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

  19. The roles of resuspension, diffusion and biogeochemical processes on oxygen dynamics offshore of the Rhône River, France: a numerical modeling study

    NASA Astrophysics Data System (ADS)

    Moriarty, Julia M.; Harris, Courtney K.; Fennel, Katja; Friedrichs, Marjorie A. M.; Xu, Kehui; Rabouille, Christophe

    2017-04-01

    Observations indicate that resuspension and associated fluxes of organic material and porewater between the seabed and overlying water can alter biogeochemical dynamics in some environments, but measuring the role of sediment processes on oxygen and nutrient dynamics is challenging. A modeling approach offers a means of quantifying these fluxes for a range of conditions, but models have typically relied on simplifying assumptions regarding seabed-water-column interactions. Thus, to evaluate the role of resuspension on biogeochemical dynamics, we developed a coupled hydrodynamic, sediment transport, and biogeochemical model (HydroBioSed) within the Regional Ocean Modeling System (ROMS). This coupled model accounts for processes including the storage of particulate organic matter (POM) and dissolved nutrients within the seabed; fluxes of this material between the seabed and the water column via erosion, deposition, and diffusion at the sediment-water interface; and biogeochemical reactions within the seabed. A one-dimensional version of HydroBioSed was then implemented for the Rhône subaqueous delta in France. To isolate the role of resuspension on biogeochemical dynamics, this model implementation was run for a 2-month period that included three resuspension events; also, the supply of organic matter, oxygen, and nutrients to the model was held constant in time. Consistent with time series observations from the Rhône Delta, model results showed that erosion increased the diffusive flux of oxygen into the seabed by increasing the vertical gradient of oxygen at the seabed-water interface. This enhanced supply of oxygen to the seabed, as well as resuspension-induced increases in ammonium availability in surficial sediments, allowed seabed oxygen consumption to increase via nitrification. This increase in nitrification compensated for the decrease in seabed oxygen consumption due to aerobic remineralization that occurred as organic matter was entrained into the water

  20. [Biocompatibility of poly-L-lactic acid/Bioglass-guided bone regeneration membranes processed with oxygen plasma].

    PubMed

    Fang, Wei; Zeng, Shu-Guang; Gao, Wen-Feng

    2015-04-01

    To prepare and characterize a nano-scale fibrous hydrophilic poly-L-lactic acid/ Bioglass (PLLA/BG) composite membrane and evaluate its biocompatibility as a composite membrane for guiding bone regeneration (GBR). PLLA/BG-guided bone regeneration membrane was treated by oxygen plasma to improved its hydrophilicity. The growth of MG-63 osteoblasts on the membrane was observed using Hoechst fluorescence staining, and the biocompatibility of the membrane was evaluated by calculating the cells adhesion rate and proliferation rate. Osteogenesis of MG-63 cells was assessed by detecting alkaline phosphatase (ALP), and the formation of calcified nodules and cell morphology changes were observed using scanning electron microscope (SEM). The cell adhesion rates of PLLA/BG-guided bone regeneration membrane treated with oxygen plasma were (30.570±0.96)%, (47.27±0.78)%, and (66.78±0.69)% at 1, 3, and 6 h, respectively, significantly higher than those on PLLA membrane and untreated PLLA/BG membrane (P<0.01). The cell proliferation rates on the 3 membranes increased with time, but highest on oxygen plasma-treated PLLA/BG membrane (P<0.01). Hoechst fluorescence staining revealed that oxygen plasma treatment of the PLLA/BG membrane promoted cell adhesion. The membranes with Bioglass promoted the matrix secretion of the osteoblasts. Under SEM, the formation of calcified nodules and spindle-shaped cell morphology were observed on oxygen plasma-treated PLLA/BG membrane. Oxygen plasma-treated PLLA/BG composite membrane has good biocompatibility and can promote adhesion, proliferation and osteogenesis of the osteoblasts.

  1. Oxygen sensitive microwells.

    PubMed

    Sinkala, Elly; Eddington, David T

    2010-12-07

    Oxygen tension is critical in a number of cell pathways but is often overlooked in cell culture. One reason for this is the difficulty in modulating and assessing oxygen tensions without disturbing the culture conditions. Toward this end, a simple method to generate oxygen-sensitive microwells was developed through embossing polystyrene (PS) and platinum(ii) octaethylporphyrin ketone (PtOEPK) thin films. In addition to monitoring the oxygen tension, microwells were employed in order to isolate uniform clusters of cells in microwells. The depth and width of the microwells can be adapted to different experimental parameters easily by altering the thin film processing or embossing stamp geometries. The thin oxygen sensitive microwell substrate is also compatible with high magnification modalities such as confocal imaging. The incorporation of the oxygen sensor into the microwells produces measurements of the oxygen tension near the cell surface. The oxygen sensitive microwells were calibrated and used to monitor oxygen tensions of Madin-Darby Canine Kidney Cells (MDCKs) cultured at high and low densities as a proof of concept. Wells 500 µm in diameter seeded with an average of 330 cells exhibited an oxygen level of 12.6% whereas wells seeded with an average of 20 cells per well exhibited an oxygen level of 19.5%, a 35.7% difference. This platform represents a new tool for culturing cells in microwells in a format amenable to high magnification imaging while monitoring the oxygen state of the culture media.

  2. Oxygen Isotopic Signature of 4.4-3.9 Ga Zircons as a Monitor of Differentiation Processes on the Moon

    NASA Technical Reports Server (NTRS)

    Nemchin, A. A.; Whitehouse, M. J.; Pidgeon, R. T.; Meyer, C.

    2006-01-01

    We report oxygen isotopic compositions for 14 zircon grains from a sample of sawdust from lunar breccia 14321. The zircons range in age from approx.4.4 to 3.9 Ga and in U and Th content from a few to several hundred ppm. As such these grains represent a range of possible source rocks, from granophyric to mafic composition, and cover the total age range of the major initial lunar bombardment. Nevertheless, results show that the oxygen isotopic compositions of the zircons fall within a narrow range of (delta18)O of about 1 per mil and have (delta18)O values indistinguishable from those observed for terrestrial mid-ocean ridge basalts confirming the coincidence of lunar and Earth oxygen isotopic compositions. In the (delta17)O vs. (delta18)O, coordinates data form a tight group with a limited trend on the terrestrial fractionation line. The zircon oxygen isotopes show minimal evidence of the extreme and variable mineral differentiation and element fractionation that have contributed to the formation of their parent rocks.

  3. Oxygen Isotopic Signature of 4.4-3.9 Ga Zircons as a Monitor of Differentiation Processes on the Moon

    NASA Technical Reports Server (NTRS)

    Nemchin, A. A.; Whitehouse, M. J.; Pidgeon, R. T.; Meyer, C.

    2006-01-01

    We report oxygen isotopic compositions for 14 zircon grains from a sample of sawdust from lunar breccia 14321. The zircons range in age from approx.4.4 to 3.9 Ga and in U and Th content from a few to several hundred ppm. As such these grains represent a range of possible source rocks, from granophyric to mafic composition, and cover the total age range of the major initial lunar bombardment. Nevertheless, results show that the oxygen isotopic compositions of the zircons fall within a narrow range of (delta18)O of about 1 per mil and have (delta18)O values indistinguishable from those observed for terrestrial mid-ocean ridge basalts confirming the coincidence of lunar and Earth oxygen isotopic compositions. In the (delta17)O vs. (delta18)O, coordinates data form a tight group with a limited trend on the terrestrial fractionation line. The zircon oxygen isotopes show minimal evidence of the extreme and variable mineral differentiation and element fractionation that have contributed to the formation of their parent rocks.

  4. Anionic Pt in Silicate Melts at Low Oxygen Fugacity: Speciation, Partitioning and Implications for Core Formation Processes on Asteroids

    NASA Technical Reports Server (NTRS)

    Medard, E.; Martin, A. M.; Righter, K.; Malouta, A.; Lee, C.-T.

    2017-01-01

    Most siderophile element concentrations in planetary mantles can be explained by metal/ silicate equilibration at high temperature and pressure during core formation. Highly siderophile elements (HSE = Au, Re, and the Pt-group elements), however, usually have higher mantle abundances than predicted by partitioning models, suggesting that their concentrations have been set by late accretion of material that did not equilibrate with the core. The partitioning of HSE at the low oxygen fugacities relevant for core formation is however poorly constrained due to the lack of sufficient experimental constraints to describe the variations of partitioning with key variables like temperature, pressure, and oxygen fugacity. To better understand the relative roles of metal/silicate partitioning and late accretion, we performed a self-consistent set of experiments that parameterizes the influence of oxygen fugacity, temperature and melt composition on the partitioning of Pt, one of the HSE, between metal and silicate melts. The major outcome of this project is the fact that Pt dissolves in an anionic form in silicate melts, causing a dependence of partitioning on oxygen fugacity opposite to that reported in previous studies.

  5. In Situ Resource Utilization (ISRU) on the Moon: Moessbauer Spectroscopy as a Process Monitor for Oxygen Production. Results from a Field Test on Mauna Kea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    Morris, R.V.; Schroder, C.; Graff, T.G.; Sanders, G.B.; Lee, K.A.; Simon, T.M.; Larson, W.E.; Quinn, J.W.; Clark, L.D.; Caruso, J.J.

    2009-01-01

    Essential consumables like oxygen must to be produced from materials on the lunar surface to enable a sustained, long-term presence of humans on the Moon. The Outpost Precursor for ISRU and Modular Architecture (OPTIMA) field test on Mauna Kea, Hawaii, facilitated by the Pacific International Space Center for Exploration Systems (PISCES) of the University of Hawaii at Hilo, was designed to test the implementation of three hardware concepts to extract oxygen from the lunar regolith: Precursor ISRU Lunar Oxygen Testbed (PILOT) developed by Lockheed Martin in Littleton, CO; Regolith & Environmental Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) developed at the NASA Kennedy Space Center in Cape Canaveral, FL; and ROxygen developed at the NASA Johnson Space Center in Houston, TX. The three concepts differ in design, but all rely on the same general principle: hydrogen reduction of metal cations (primarily Fe2+) bonded to oxygen to metal (e.g., Fe0) with the production of water. The hydrogen source is residual hydrogen in the fuel tanks of lunar landers. Electrolysis of the water produces oxygen and hydrogen (which is recycled). We used the miniaturized M ssbauer spectrometer MIMOS II to quantify the yield of this process on the basis of the quantity of Fe0 produced. Iron M ssbauer spectroscopy identifies iron-bearing phases, determines iron oxidation states, and quantifies the distribution of iron between mineral phases and oxidation states. The oxygen yield can be calculated by quantitative measurements of the distribution of Fe among oxidation states in the regolith before and after hydrogen reduction. A M ssbauer spectrometer can also be used as a prospecting tool to select the optimum feedstock for the oxygen production plants (e.g., high total Fe content and easily reduced phases). As a demonstration, a MIMOS II backscatter spectrometer (SPESI, Germany) was mounted on the Cratos rover (NASA Glenn Research Center in Cleveland, OH), which is one of

  6. In Situ Resource Utilization (ISRU) on the Moon: Moessbauer Spectroscopy as a Process Monitor for Oxygen Production. Results from a Field Test on Mauna Kea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    Morris, R.V.; Schroder, C.; Graff, T.G.; Sanders, G.B.; Lee, K.A.; Simon, T.M.; Larson, W.E.; Quinn, J.W.; Clark, L.D.; Caruso, J.J.

    2009-01-01

    Essential consumables like oxygen must to be produced from materials on the lunar surface to enable a sustained, long-term presence of humans on the Moon. The Outpost Precursor for ISRU and Modular Architecture (OPTIMA) field test on Mauna Kea, Hawaii, facilitated by the Pacific International Space Center for Exploration Systems (PISCES) of the University of Hawaii at Hilo, was designed to test the implementation of three hardware concepts to extract oxygen from the lunar regolith: Precursor ISRU Lunar Oxygen Testbed (PILOT) developed by Lockheed Martin in Littleton, CO; Regolith & Environmental Science and Oxygen & Lunar Volatiles Extraction (RESOLVE) developed at the NASA Kennedy Space Center in Cape Canaveral, FL; and ROxygen developed at the NASA Johnson Space Center in Houston, TX. The three concepts differ in design, but all rely on the same general principle: hydrogen reduction of metal cations (primarily Fe2+) bonded to oxygen to metal (e.g., Fe0) with the production of water. The hydrogen source is residual hydrogen in the fuel tanks of lunar landers. Electrolysis of the water produces oxygen and hydrogen (which is recycled). We used the miniaturized M ssbauer spectrometer MIMOS II to quantify the yield of this process on the basis of the quantity of Fe0 produced. Iron M ssbauer spectroscopy identifies iron-bearing phases, determines iron oxidation states, and quantifies the distribution of iron between mineral phases and oxidation states. The oxygen yield can be calculated by quantitative measurements of the distribution of Fe among oxidation states in the regolith before and after hydrogen reduction. A M ssbauer spectrometer can also be used as a prospecting tool to select the optimum feedstock for the oxygen production plants (e.g., high total Fe content and easily reduced phases). As a demonstration, a MIMOS II backscatter spectrometer (SPESI, Germany) was mounted on the Cratos rover (NASA Glenn Research Center in Cleveland, OH), which is one of

  7. A study of injection processes for 15-percent fluorine - 85-percent oxygen and heptane in a 200-pound-thrust rocket engine

    NASA Technical Reports Server (NTRS)

    Heidmann, M F

    1957-01-01

    Characteristic exhaust velocity over a range of mixture ratios and variations in gas velocity with distance from the injector were measured for six injectors. Comparisons of injector performance showed the gains obtained from oxidant atomization, fuel atomization, and propellant mixing. The results are compared with oxygen and heptane performance and show the effect, which is qualitatively small, of spontaneous propellant ignition on the relation between injection processes and engine performance.

  8. A study of alternative methods for reclaiming oxygen from carbon dioxide and water by a solid-electrolyte process for spacecraft applications

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Two alternative technical approaches were studied for application of an electrochemical process using a solid oxide electrolyte (zirconia stabilized by yttria or scandia) to oxygen reclamation from carbon dioxide and water, for spacecraft life support systems. Among the topics considered are the advisability of proceeding to engineering prototype development and fabrication of a full scale model for the system concept, the optimum choice of method or approach to be carried into prototype development, and the technical problem areas which exist.

  9. Green Electrochemical Process Solid-Oxide Oxygen-Ion-Conducting Membrane (SOM): Direct Extraction of Ti-Fe Alloys from Natural Ilmenite

    NASA Astrophysics Data System (ADS)

    Lu, Xionggang; Zou, Xingli; Li, Chonghe; Zhong, Qingdong; Ding, Weizhong; Zhou, Zhongfu

    2012-06-01

    The direct electrochemical extraction of Ti-Fe alloys from natural ilmenite (FeTiO3) in molten CaCl2 is reported in this article. The sintered porous pellet of natural ilmenite acted as the cathode of the electrochemical system, and the carbon-saturated liquid tin contained in a solid-oxide oxygen-ion-conducting membrane (SOM) tube served as the anode of the electrolytic cell. The electrochemical process was carried out at 3.8 V, under 1223 K and 1273 K (950 °C and 1000 °C). Oxygen was ionized continuously from the cathode and discharged at the anode; solid porous Ti-Fe alloys were obtained at the cathode. The electro-deoxidation procedure of the ilmenite was characterized by analyzing partially electro-deoxidized samples taken periodically throughout the electro-deoxidation process. The findings of this study are as follows: (1) The electro-deoxidation process followed these steps: Fe2TiO5 → FeTiO3 → Fe2TiO4 → Fe, Ti (and/or Ti-Fe alloys); and TiO2 → CaTiO3 → Ti; and (2) two types of particle growth pattern are observed in the experiments. The first pattern is characterized with particle fusion and second pattern is interconnection of particles to form porous structure. A microhole oxygen-ion-migration model is suggested based on the experimental evidence.

  10. Treatment of experimental avascular necrosis of the femoral head with hyperbaric oxygen in rats: histological evaluation of the femoral heads during the early phase of the reparative process.

    PubMed

    Levin, D; Norman, D; Zinman, C; Rubinstein, L; Sabo, E; Misselevich, I; Reis, D; Boss, J H

    1999-10-01

    The healing of vascular deprivation-induced necrosis of the femoral head of rats exposed to hyperbaric oxygen was compared with that in untreated rats. The amount of necrotic bone, extent of osteoneogenesis, degree of remodeling, and changes of the articular cartilage were histologically graded on a semiquantitative scale of 0 to 3+. On the 2nd, 7th, and 21st postoperative days, there were no differences between the two groups. Newly formed appositional and intramembranous bone was more abundant and remodeling was more advanced in the femoral heads of the hyperbaric oxygen-treated than untreated rats sacrificed on the 42nd postoperative day; also there was less necrotic debris in the femoral heads of the treated rats. There were no differences in the severity of the degenerative changes of the articular cartilage of the treated and untreated rats. Exposure of rats to hyperbaric oxygen does not preserve tissue viability after all arteries supplying the femoral head are severed. Yet, resulting in an increased oxygen tension of the tissues, it seems to provide the optimal settings for reparative processes. The results suggest that hyperoxygenation-mediated relief of ischemia enhances the fibroblastic, angioblastic, osteoblastic, and osteoclastic activities such that healing of the rats' necrotic femoral heads is expedited.

  11. Pilot-Scale Demonstration of a Novel, Low-Cost Oxygen Supply Process and its Integration with Oxy-Fuel Coal-Fired Boilers

    SciTech Connect

    Krish Krishnamurthy; Divy Acharya; Frank Fitch

    2008-09-30

    In order to achieve DOE targets for carbon dioxide capture, it is crucial not only to develop process options that will generate and provide oxygen to the power cycle in a cost-effective manner compared to the conventional oxygen supply methods based on cryogenic air separation technology, but also to identify effective integration options for these new technologies into the power cycle with carbon dioxide capture. The Linde/BOC developed Ceramic Autothermal Recovery (CAR) process remains an interesting candidate to address both of these issues by the transfer of oxygen from the air to a recycled CO{sub 2} rich flue-gas stream in a cyclic process utilizing the high temperature sorption properties of perovskites. Good progress was made on this technology in this project, but significant challenges remain to be addressed before CAR oxygen production technology is ready for commercial exploitation. Phase 1 of the project was completed by the end of September 2008. The two-bed 0.7 tons/day O2 CAR process development unit (PDU) was installed adjacent to WRI's pilot scale coal combustion test facility (CTF). Start-up and operating sequences for the PDU were developed and cyclic operation of the CAR process demonstrated. Controlled low concentration methane addition allowed the beds to be heated up to operational temperature (800-900 C) and then held there during cyclic operation of the 2-bed CAR process, in this way overcoming unavoidable heat losses from the beds during steady state operation. The performance of the PDU was optimized as much as possible, but equipment limitations prevented the system from fully achieving its target performance. Design of the flue gas recirculation system to integrate CAR PDU with the CTF and the system was completed and integrated tests successfully performed at the end of the period. A detailed techno-economic analysis was made of the CAR process for supplying the oxygen in oxy-fuel combustion retrofit option using AEP's 450 MW

  12. Digital phosphorimeter with frequency domain signal processing: Application to real-time fiber-optic oxygen sensing

    NASA Astrophysics Data System (ADS)

    Alcala, J. Ricardo; Yu, Clement; Yeh, Gong Jong

    1993-06-01

    An instrument to measure the excited-state lifetimes of phosphorescent materials in real time is described. This apparatus uses pulsed and frequency-doubled Nd:YAG solid-state laser for excitation, sampler for data acquisition, and frequency domain methods for data fitting. The instrument amplifies the ac components of the detector output and band limits the signal to 25 kHz. The fundamental frequency of the excitation is then set to obtain a desired number of harmonics. This band limited signal is sampled and averaged over few thousand cycles in the time domain. The frequency domain representation of the data is obtained by employing fast Fourier transform algorithms. The phase delay and the modulation ratio of each sampled harmonic is then computed. Ten to a hundred values of the phase and modulations are averaged before computing the sensor lifetime. The instrument is capable of measuring precise and accurate excited-state lifetimes from subpicowatt luminescent signals in 100 μm optical fibers. To monitor oxygen for biomedical applications the response time of the system is decreased by collecting only 8 or 16 harmonics. A least-squares fit yields the lifetimes of single exponentials. A component of zero lifetime is introduced to account for the backscatter excitation. The phosphorescence lifetimes measured reproducibly to three parts in a thousand are used to monitor oxygen. Oxygen concentrations are computed employing empirical polynomials. The system drift is less than 1% over 100 h of continuous operation. This instrument is used to measure oxygen concentrations in vitro and in vivo with 2 s update times and 90 s full response times. Examples of measurements in saline solutions and in dogs are presented.

  13. Final report on the project entitled: Highly Preheated Combustion Air System with/without Oxygen Enrichment for Metal Processing Furnaces

    SciTech Connect

    Arvind Atreya

    2007-02-16

    This work develops and demonstrates a laboratory-scale high temperature natural gas furnace that can operate with/without oxygen enrichment to significantly improve energy efficiency and reduce emissions. The laboratory-scale is 5ft in diameter & 8ft tall. This furnace was constructed and tested. This report demonstrates the efficiency and pollutant prevention capabilities of this test furnace. The project also developed optical detection technology to control the furnace output.

  14. Enhancing dissolved oxygen control using an on-line hybrid fuzzy-neural soft-sensing model-based control system in an anaerobic/anoxic/oxic process.

    PubMed

    Huang, Mingzhi; Wan, Jinquan; Hu, Kang; Ma, Yongwen; Wang, Yan

    2013-12-01

    An on-line hybrid fuzzy-neural soft-sensing model-based control system was developed to optimize dissolved oxygen concentration in a bench-scale anaerobic/anoxic/oxic (A(2)/O) process. In order to improve the performance of the control system, a self-adapted fuzzy c-means clustering algorithm and adaptive network-based fuzzy inference system (ANFIS) models were employed. The proposed control system permits the on-line implementation of every operating strategy of the experimental system. A set of experiments involving variable hydraulic retention time (HRT), influent pH (pH), dissolved oxygen in the aerobic reactor (DO), and mixed-liquid return ratio (r) was carried out. Using the proposed system, the amount of COD in the effluent stabilized at the set-point and below. The improvement was achieved with optimum dissolved oxygen concentration because the performance of the treatment process was optimized using operating rules implemented in real time. The system allows various expert operational approaches to be deployed with the goal of minimizing organic substances in the outlet while using the minimum amount of energy.

  15. Oxygen analyzer

    DOEpatents

    Benner, William H.

    1986-01-01

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

  16. Oxygen Therapy

    MedlinePlus

    ... stored as a gas or liquid in special tanks. These tanks can be delivered to your home and contain ... they won’t run out of oxygen. Portable tanks and oxygen concentrators may make it easier for ...

  17. 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.

    PubMed

    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.

  18. Hydrogen production from a combination of the water-gas shift and redox cycle process of methane partial oxidation via lattice oxygen over LaFeO3 perovskite catalyst.

    PubMed

    Dai, Xiao Ping; Wu, Qiong; Li, Ran Jia; Yu, Chang Chun; Hao, Zheng Ping

    2006-12-28

    A redox cycle process, in which CH4 and air are periodically brought into contact with a solid oxide packed in a fixed-bed reactor, combined with the water-gas shift (WGS) reaction, is proposed for hydrogen production. The sole oxidant for partial oxidation of methane (POM) is found to be lattice oxygen instead of gaseous oxygen. A perovskite-type LaFeO3 oxide was prepared by a sol-gel method and employed as an oxygen storage material in this process. The results indicate that, under appropriate reaction conditions, methane can be oxidized to CO and H2 by the lattice oxygen of LaFeO3 perovskite oxide with a selectivity higher than 95% and the consumed lattice oxygen can be replenished in a reoxidation procedure by a redox operation. It is suggested that the POM to H2/CO by using the lattice oxygen of the oxygen storage materials instead of gaseous oxygen should be possibly applicable. The LaFeO3 perovskite oxide maintained relatively high catalytic activity and structural stability, while the carbonaceous deposits, which come from the dissociation of CH4 in the pulse reaction, occurred due to the low migration rate of lattice oxygen from the bulk toward the surface. A new dissociation-oxidation mechanism for this POM without gaseous oxygen is proposed based on the transient responses of the products checked at different surface states via both pulse reaction and switch reaction over the LaFeO3 catalyst. In the absence of gaseous-phase oxygen, the rate-determining step of methane conversion is the migration rate of lattice oxygen, but the process can be carried out in optimized cycles. The product distribution for POM over LaFeO3 catalyst in the absence of gaseous oxygen was determined by the concentration of surface oxygen, which is relevant with the migration rate of lattice oxygen from the bulk toward the surface. This process of hydrogen production via selective oxidation of methane by lattice oxygen is better in avoiding the deep oxidation (to CO2) and

  19. Investigation of the physiological response to oxygen limited process conditions of Pichia pastoris Mut(+) strain using a two-compartment scale-down system.

    PubMed

    Lorantfy, Bettina; Jazini, Mohammadhadi; Herwig, Christoph

    2013-09-01

    Inhomogeneities in production-scale bioreactors influence microbial growth and product quality due to insufficient mixing and mass transfer. For this reason, lots of efforts are being made to investigate the effects of gradients that impose stress in large-scale reactors in laboratory scale. We have implemented a scale-down model which allows separating a homogeneous part, a stirred tank reactor (STR), and a plug flow reactor (PFR) which mimics the inhomogeneous regimes of the large-scale fermenters. This scale-down model shows solutions to trigger oxygen limited conditions in the PFR part of the scale-down setup for physiological analysis. The goal of the study was to investigate the scale-up relevant physiological responses of Pichia pastoris strain to oxygen limited process conditions in the above mentioned two-compartment bioreactor setup. Experimental results with non-induced cultures show that the specific growth rate significantly decreased with increasing the exposure time to oxygen limitation. In parallel more by-products were produced. Examining physiological scalable key parameters, multivariate data analyses solely using on-line data revealed that different exposures to the oxygen limitation significantly affected the culture performance. This work with the small scale-downs setup reflects new approaches for a valuable process development tool for accelerating strain characterization or for verifying CFD simulations of large-scale bioreactors. As a novel methodological achievement, the combination of the two-compartment scale-down system with the proposed multivariate techniques of solely using on-line data is a valuable tool for recognition of stress effects on the culture performance for physiological bioprocess scale-up issues.

  20. KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility insert the liquid oxygen feedline for the 17-inch disconnect in the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

    NASA Image and Video Library

    2003-11-11

    KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility insert the liquid oxygen feedline for the 17-inch disconnect in the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

  1. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers install the liquid oxygen feedline for the 17-inch disconnect on orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

    NASA Image and Video Library

    2003-11-11

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers install the liquid oxygen feedline for the 17-inch disconnect on orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

  2. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers lift the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

    NASA Image and Video Library

    2003-11-11

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers lift the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

  3. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers raise the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

    NASA Image and Video Library

    2003-11-11

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers raise the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

  4. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers move the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

    NASA Image and Video Library

    2003-11-11

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers move the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

  5. KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility oversee installation of the liquid oxygen feedline for the 17-inch disconnect on the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

    NASA Image and Video Library

    2003-11-11

    KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility oversee installation of the liquid oxygen feedline for the 17-inch disconnect on the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

  6. Characterization of refractory matters in dyeing wastewater during a full-scale Fenton process following pure-oxygen activated sludge treatment.

    PubMed

    Bae, Wookeun; Won, Hosik; Hwang, Byungho; de Toledo, Renata Alves; Chung, Jinwook; Kwon, Kiwook; Shim, Hojae

    2015-04-28

    Refractory pollutants in raw and treated dyeing wastewaters were characterized using fractional molecular weight cut-off, Ultraviolet-vis spectrophotometry, and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI/MS). Significant organics and color compounds remained after biological (pure-oxygen activated sludge) and chemical (Fenton) treatments at a dyeing wastewater treatment plant (flow rate ∼100,000m(3)/d). HPLC-ESI/MS analysis revealed that some organic compounds disappeared after the biological treatment but reappeared after the chemical oxidation process, and some of that were originally absent in the raw dyeing wastewater was formed after the biological or chemical treatment. It appeared that the Fenton process merely impaired the color-imparting bonds in the dye materials instead of completely degrading them. Nevertheless, this process did significantly reduce the soluble chemical oxygen demand (SCOD, 66%) and color (73%) remaining after initial biological treatment which reduced SCOD by 53% and color by 13% in raw wastewater. Biological treatment decreased the degradable compounds substantially, in such a way that the following Fenton process could effectively remove recalcitrant compounds, making the overall hybrid system more economical. In addition, ferric ion inherent to the Fenton reaction effectively coagulated particulate matters not removed via biological and chemical oxidation.

  7. [Apneic oxygenation].

    PubMed

    Alekseev, A V; Vyzhigina, M A; Parshin, V D; Fedorov, D S

    2013-01-01

    Recent technological advances in thoracic and tracheal surgery make the anaesthesiologist use different respiratory techniques during the operation. Apneic oxygenation is a one of alternative techniques. This method is relatively easy in use, does not require special expensive equipment and is the only possible technique in several clinical situations when other respiratory methods are undesirable or cannot be used. However there is no enough information about apneic oxygenation in Russian. This article reviews publications about apneic oxygenation. The review deals with experiments on diffusion respiration in animals, physiological changes during apneic oxygenation in man and defines clinical cases when apneic oxygenation can be used.

  8. Oxygen analyzer

    DOEpatents

    Benner, W.H.

    1984-05-08

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

  9. Sustained in situ measurements of dissolved oxygen, methane and water transport processes in the benthic boundary layer at MC118, northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Martens, Christopher S.; Mendlovitz, Howard P.; Seim, Harvey; Lapham, Laura; D'Emidio, Marco

    2016-07-01

    Within months of the BP Macondo Wellhead blowout, elevated methane concentrations within the water column revealed a significant retention of light hydrocarbons in deep waters plus corresponding dissolved oxygen (DO) deficits. However, chemical plume tracking efforts were hindered by a lack of in situ monitoring capabilities. Here, we describe results from in situ time-series, lander-based investigations of physical and biogeochemical processes controlling dissolved oxygen, and methane at Mississippi Canyon lease block 118 ( 18 km from the oil spill) conducted shortly after the blowout through April 2012. Multiple sensor arrays plus open-cylinder flux chambers (;chimneys;) deployed from a benthic lander collected oxygen, methane, pressure, and current speed and direction data within one meter of the seafloor. The ROVARD lander system was deployed for an initial 21-day test experiment (9/13/2010-10/04/2010) at 882 m depth before a longer 160-day deployment (10/24/2011-4/01/2012) at 884 m depth. Temporal variability in current directions and velocities and water temperatures revealed strong influences of bathymetrically steered currents and overlying along-shelf flows on local and regional water transport processes. DO concentrations and temperature were inversely correlated as a result of water mass mixing processes. Flux chamber measurements during the 160-day deployment revealed total oxygen utilization (TOU) averaging 11.6 mmol/m2 day. Chimney DO concentrations measured during the 21-day deployment exhibited quasi-daily variations apparently resulting from an interaction between near inertial waves and the steep topography of an elevated scarp immediately adjacent to the 21-day deployment site that modulated currents at the top of the chimney. Variability in dissolved methane concentrations suggested significant temporal variability in gas release from nearby hydrocarbon seeps and/or delivery by local water transport processes. Free-vehicle (lander) monitoring

  10. Effect of carbon source, C/N ratio, nitrate and dissolved oxygen concentration on nitrite and ammonium production from denitrification process by Pseudomonas stutzeri D6.

    PubMed

    Yang, Xinping; Wang, Shimei; Zhou, Lixiang

    2012-01-01

    Pseudomonas stutzeri D6, selectively isolated from activated sludge was used to study NO(2)(-) and NH(4)(+) production from denitrification processes. Changes in carbon type, C/N ratio and oxygen concentration significantly influenced the magnitude of NO(2)(-) and NH(4)(+) accumulation through denitrification. D6 showed a preference for citrate and acetate, which led to the largest quantity of nitrate reduced and which were exhausted most rapidly, with minimal intermediate products accumulation. It is found that at higher initial organic carbon concentration or for directly metabolic carbon type more complete denitrification could be obtained as a result of increase of the oxygen consumption rate by substrate stimulation. The higher the oxygen concentration in the culture was, the higher the intermediate products concentration became. The experiment showed that NO(2)(-) and NH(4)(+) production was only slightly influenced by nitrate concentration. Biological nitrogen removal systems should be optimized to promote complete denitrification to minimize NO(2)(-) and NH(4)(+) accumulation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Long-term operation of oxygen-limiting membrane bioreactor (MBR) for the development of simultaneous partial nitrification, anammox and denitrification (SNAD) process.

    PubMed

    Zhao, Chuanqi; Wang, Gang; Xu, Xiaochen; Yang, Yuesuo; Yang, Fenglin

    2017-07-18

    In this study, an oxygen-limiting membrane bioreactor (MBR) with recirculation of biogas for relieving membrane fouling was successfully operated to realize the simultaneous partial nitrification, anammox and denitrification (SNAD) process. The MBR operation was considered effective in the long-term test with total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 94.86% and 98.91%, respectively. Membrane fouling was significantly alleviated due to the recirculation of biogas and the membrane had been cleaned four times with a normal filtration period of 52 days. The co-existence of ammonia-oxidizing bacteria (AOB), anammox and denitrifying bacteria in MBR was confirmed by scanning electron microscopy (SEM) and fluorescence in situ hybridizations (FISH) analysis. Furthermore, AOB were found close to the granule surface, while denitrifying bacteria and anammox were in the deeper layer of granules. Potential in excellent TN and COD removal, operational stability and sustainability, as well as in alleviating membrane fouling is expected by using this oxygen-limiting MBR.

  12. Early benthic successional processes at implanted substrates in Barkley Submarine Canyon affected by a permanent oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Cabrera De Leo, F.; Smith, C. R.; Levin, L. A.; Fleury, A.; Aguzzi, J.

    2016-02-01

    With the advent of cabled observatories scientists are now able to have a permanent presence in the deep-seafloor, being able to reveal previously unseen faunal behavior as well as to track long-term changes in biodiversity and ecosystem function. The Ocean Networks Canada 800-km loop seafloor observatory array (NEPTUNE) located in the NE Pacific has instruments measuring a variety of environmental variables ranging from temperature, salinity, oxygen, currents, turbidity, fluorescence, etc, at multiple and very high temporal resolution scales. High-definition video cameras also monitor benthic communities in multiple deep-sea habitats, all at some extent influenced by an oxygen minimum zone (OMZ). In the present study, whale-bone and wood substrates are being used to evaluate bathymetric, regional and inter-basin variations in benthic biodiversity and connectivity, as well as interactions between biodiversity and ecosystem function. In May of 2014 three humpback whale (Megaptera novaeangliae) rib sections, one 20x20x10 cm block of Douglas Fir (Pseudotsunga meniziesii), and a 30x30x30 block of authigenic carbonate were placed with the use of an ROV at 890 m depth inside Barkley Canyon. The substrate packages were placed concentrically, 45-cm away from a HD video camera. Five-minute videos were captured at 2-hr intervals. Preliminary data analysis from 8 months of deployment showed very distinct early community succession patterns between the two organic substrates (bones and wood) and the authigenic carbonate. Whalebones and wood showed amphipod (Orchomene obtusa) abundance peaks mostly contained during the first 60 days after deployment; Amphipod peak abundance rapid decline coincides with rapid growth of bacterial mat on whalebone and wood surfaces. Low abundance, species richness and substrate degradation rates are in agreement with a low oxygen environment of the OMZ in the canyon. Despite the early stages of data analysis, this experiment demonstrates how

  13. Optical Measurements Reveal Interplay Between Surface and Bottom Processes Involving Phytoplankton, Organic Carbon, Iron, Light, and Oxygen in Two Stratified Mesotrophic Lakes

    NASA Astrophysics Data System (ADS)

    Hargreaves, B. R.; Vaidya, A.; Wiles, K. A.

    2009-12-01

    Water column distribution of phytoplankton, organic carbon, particulate and dissolved iron are described through detailed vertical optical measurements that include downwelling cosine irradiance, turbidity, dissolved oxygen, fluorescence by CDOM, Chl-a, phycobilin pigments, and diffuse attenuation for several UV wavebands, plus pH, temperature, and specific conductance. These measurements were completed with a group of profiling instruments during summer in two mid-latitude small lakes. Special calibration allowed for correcting the impact of CDOM and turbidity on the pigment fluorescence signals. These in situ data were combined with laboratory analysis of discrete water column samples for methanol-extracted chlorophyll-a, spectral absorbance of particles, concentration of particulates (dry mass and ash-free mass), total particulate and "dissolved" iron, DOC and CDOM (the "dissolved fraction" passes through a GF/F filter). Surface processes revealed by these measurement include solar heating and photobleaching of CDOM (partly distributed by wind-driven mixing), and nonphotochemical quenching of phytoplankton chlorophyll-a fluorescence. Bottom processes revealed by these measurements include oxygen consumption by net heterotrophic metabolism, release of DOC, CDOM, and iron from anoxic bottom sediments, and the development of a biological community structured by the light and temperature gradients and absence or scarcity of dissolved oxygen near the bottom. The iron associated with CDOM and particles in the deep samples substantially increased the latter's DOC-specific absorption once there was an opportunity for oxidation. A model for mass-specific spectral absorption of particulates accounts for the contribution of organic matter and iron associated with the particles. A detailed hydrologic budget for one of the lakes will allow the water column processes to be explored further by accounting for inputs and outputs of water and organic carbon (via precipitation

  14. River Water Quality Model no. 1 (RWQM1): case study II. Oxygen and nitrogen conversion processes in the River Glatt (Switzerland).

    PubMed

    Reichert, P

    2001-01-01

    Various simplifications of the river water quality model no. 1 are applied to data sets from the river Glatt in Switzerland. In a first application, the biomass responsible for nitrogen and oxygen conversion processes is quantified based on known reaeration rates, measured concentrations of ammonia, nitrite and oxygen and assumed growth parameters of algae and bacteria. In a second application, the model is extended to calculate chemical equilibria of inorganic carbon compounds dissolved in the water and daily variations in pH. The influence of partially unknown inflow concentrations and of calcite precipitation on fluctuations in electrical conductivity and pH are discussed. In the last model, the processes of growth of sessile algae and bacteria, detachment of algae, and grazing by benthic organisms are introduced. Due to lack of data for quantifying these processes, this last model application is speculative. Nevertheless, it is interesting because it shows a direction to which river water quality modelling would have to proceed in order to increase its predictive capabilities.

  15. Processes of chemoionization in the course of inflammation of a methane-oxygen mixture by a high-current gliding surface discharge in a closed chamber

    SciTech Connect

    Artem’ev, K. V.; Berezhetskaya, N. K.; Kossyi, I. A. Misakyan, M. A.; Popov, N. A.; Tarasova, N. M.

    2015-05-15

    Results are presented from experiments on the inflammation of a stoichiometric methane-oxygen mixture by a high-current multielectrode spark-gap in a closed cylindrical chamber. It is shown that, in both the preflame and well-developed flame stages, the gas medium is characterized by a high degree of ionization (n{sub e} ≈ 10{sup 12} cm{sup −3}) due to chemoionization processes and a high electron-neutral collision frequency (ν{sub e0} ≈ 10{sup 12} s{sup −1})

  16. Effect of dissolved oxygen on elemental sulfur generation in sulfide and nitrate removal process: characterization, pathway, and microbial community analysis.

    PubMed

    Wang, Xiaowei; Zhang, Yu; Zhang, Tingting; Zhou, Jiti

    2016-03-01

    Microaerobic bioreactor treatment for enriched sulfide and nitrate has been demonstrated as an effective strategy to improve the efficiencies of elemental sulfur (S(0)) generation, sulfide oxidation, and nitrate reduction. However, there is little detailed information for the effect and mechanism of dissolved oxygen (DO) on the variations of microbial community in sulfur generation, sulfide oxidation, and nitrate reduction systems. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was employed to evaluate the variations of microbial community structures in a sulfide oxidation and nitrate reduction reactor under different DO conditions (DO 0-0.7 mg · L(-1)). Experimental results revealed that the activity of sulfide-oxidizing bacteria (SOB) and nitrate-reducing bacteria (NRB) could be greatly stimulated in 0.1-0.3 mg-DO · L(-1). However, when the DO concentration was further elevated to more than 0.5 mg · L(-1), the abundance of NRB was markedly decreased, while the heterotrophic microorganisms, especially carbon degradation species, were enriched. The reaction pathways for sulfide and nitrate removal under microaerobic conditions were also deduced by combining batch experiments with functional species analysis. It was likely that the oxidation of sulfide to sulfur could be performed by both aerobic heterotrophic SOB and sulfur-based autotrophic denitrification bacteria with oxygen and nitrate as terminal electron acceptor, respectively. The nitrate could be reduced to nitrite by both autotrophic and heterotrophic denitrification, and then the generated nitrite could be completely converted to nitrogen gas via heterotrophic denitrification. This study provides new insights into the impacts of microaerobic conditions on the microbial community functional structures of sulfide-oxidizing, nitrate-reducing, and sulfur-producing bioreactors, which revealing the potential linkage between functional microbial communities and

  17. Contrasting hydrological processes of meteoric water incursion during magmatic-hydrothermal ore deposition: An oxygen isotope study by ion microprobe

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Bouvier, Anne-Sophie; Baumgartner, Lukas; Heinrich, Christoph A.

    2016-10-01

    Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic-hydrothermal systems has been linked to tin ore deposition in granitic plutons. In contrast, evidence from porphyry copper ore deposits suggests that crystallizing subvolcanic magma bodies are only affected by meteoric water incursion in peripheral zones and during late post-ore stages. We apply high-resolution secondary ion mass spectrometry (SIMS) to analyze oxygen isotope ratios of individual growth zones in vein quartz crystals, imaged by cathodo-luminescence microscopy (SEM-CL). Existing microthermometric information from fluid inclusions enables calculation of the oxygen isotope composition of the fluid from which the quartz precipitated, constraining the relative timing of meteoric water input into these two different settings. Our results confirm that incursion of meteoric water directly contributes to cooling of shallow granitic plutons and plays a key role in concurrent tin mineralization. By contrast, data from two porphyry copper deposits suggest that downward circulating meteoric water is counteracted by up-flowing hot magmatic fluids. Our data show that porphyry copper ore deposition occurs close to a magmatic-meteoric water interface, rather than in a purely magmatic fluid plume, confirming recent hydrological modeling. On a larger scale, the expulsion of magmatic fluids against the meteoric water interface can shield plutons from rapid convective cooling, which may aid the build-up of large magma chambers required for porphyry copper ore formation.

  18. Electroless Pt deposition on Mn3O4 nanoparticles via the galvanic replacement process: electrocatalytic nanocomposite with enhanced performance for oxygen reduction reaction.

    PubMed

    Kim, Ki Woong; Kim, Soo Min; Choi, Suhee; Kim, Jongwon; Lee, In Su

    2012-06-26

    A novel electroless Pt deposition method was exploited by employing the galvanic replacement process occurring between the Mn(3)O(4) surface and PtCl(4)(2-) complexes. The newly discovered process provides a simple protocol to produce the catalytic nanocomposite, in which a high density of ultrafine Pt nanocrystals is stably immobilized in a homogeneously dispersive state on the surface of Mn(3)O(4) nanoparticles. When the eletrocatalytic activity was tested for the oxygen reduction reaction, which limits the rate of the overall process in proton-exchange membrane fuel cells, the resulting Pt/Mn(3)O(4) nanocomposite showed highly enhanced specific activity and durability, compared with those of the commercial Pt/C catalyst.

  19. Monitoring Oxygen Status.

    PubMed

    Toffaletti, J G; Rackley, C R

    Although part of a common "blood gas" test panel with pH and pCO2, the pO2, %O2Hb, and related parameters are independently used to detect and monitor oxygen deficits from a variety of causes. Measurement of blood gases and cooximetry may be done by laboratory analyzers, point of care testing, noninvasive pulse oximetry, and transcutaneous blood gases. The specimen type and mode of monitoring oxygenation that are chosen may be based on a combination of urgency, practicality, clinical need, and therapeutic objectives. Because oxygen concentrations in blood are extremely labile, there are several highly important preanalytical practices necessary to prevent errors in oxygen and cooximetry results. Effective utilization of oxygen requires binding by hemoglobin in the lungs, transport in the blood, and release to tissues, where cellular respiration occurs. Hydrogen ion (pH), CO2, temperature, and 2,3-DPG all play important roles in these processes. Additional measurements and calculations are often used to interpret and locate the cause and source of an oxygen deficit. These include the Hb concentration, Alveolar-arterial pO2 gradient, pO2:FIO2 ratio, oxygenation index, O2 content and O2 delivery, and pulmonary dead space and intrapulmonary shunting. The causes of hypoxemia will be covered and, to illustrate how the oxygen parameters are used clinically in the diagnosis and management of patients with abnormal oxygenation, two clinical cases will be presented and described.

  20. Vitamin K Oxygenation, Glutamate Carboxylation, and Processivity: Defining the Three Critical Facets of Catalysis by the Vitamin K–Dependent Carboxylase12

    PubMed Central

    Rishavy, Mark A.; Berkner, Kathleen L.

    2012-01-01

    The vitamin K–dependent carboxylase uses vitamin K oxygenation to drive carboxylation of multiple glutamates in vitamin K–dependent proteins, rendering them active in a variety of physiologies. Multiple carboxylations of proteins are required for their activity, and the carboxylase is processive, so that premature dissociation of proteins from the carboxylase does not occur. The carboxylase is unique, with no known homology to other enzyme families, and structural determinations have not been made, rendering an understanding of catalysis elusive. Although a model explaining the relationship of oxygenation to carboxylation had been developed, until recently almost nothing was known of the function of the carboxylase itself in catalysis. In the past decade, discovery and analysis of naturally occurring carboxylase mutants has led to identification of functionally relevant residues and domains. Further, identification of nonmammalian carboxylase orthologs has provided a basis for bioinformatic analysis to identify candidates for critical functional residues. Biochemical analysis of rationally chosen carboxylase mutants has led to breakthroughs in understanding vitamin K oxygenation, glutamate carboxylation, and maintenance of processivity by the carboxylase. Protein carboxylation has also been assessed in vivo, and the intracellular environment strongly affects carboxylase function. The carboxylase is an integral membrane protein, and topological analysis, coupled with biochemical determinations, suggests that interaction of the carboxylase with the membrane is an important facet of function. Carboxylase homologs, likely acquired by horizontal transfer, have been discovered in some bacteria, and functional analysis of these homologs has the potential to lead to the discovery of new roles of vitamin K in biology. PMID:22516721

  1. Sulfur degassing at Erta Ale (Ethiopia) and Masaya (Nicaragua) volcanoes: Implications for degassing processes and oxygen fugacities of basaltic systems

    NASA Astrophysics Data System (ADS)

    Moor, J. M.; Fischer, T. P.; Sharp, Z. D.; King, P. L.; Wilke, M.; Botcharnikov, R. E.; Cottrell, E.; Zelenski, M.; Marty, B.; Klimm, K.; Rivard, C.; Ayalew, D.; Ramirez, C.; Kelley, K. A.

    2013-10-01

    We investigate the relationship between sulfur and oxygen fugacity at Erta Ale and Masaya volcanoes. Oxygen fugacity was assessed utilizing Fe3+/∑Fe and major element compositions measured in olivine-hosted melt inclusions and matrix glasses. Erta Ale melts have Fe3+/∑Fe of 0.15-0.16, reflecting fO2 of ΔQFM 0.0 ± 0.3, which is indistinguishable from fO2 calculated from CO2/CO ratios in high-temperature gases. Masaya is more oxidized at ΔQFM +1.7 ± 0.4, typical of arc settings. Sulfur isotope compositions of gases and scoria at Erta Ale (δ34Sgas - 0.5‰; δ34Sscoria + 0.9‰) and Masaya (δ34Sgas + 4.8‰; δ34Sscoria + 7.4‰) reflect distinct sulfur sources, as well as isotopic fractionation during degassing (equilibrium and kinetic fractionation effects). Sulfur speciation in melts plays an important role in isotope fractionation during degassing and S6+/∑S is <0.07 in Erta Ale melt inclusions compared to >0.67 in Masaya melt inclusions. No change is observed in Fe3+/∑Fe or S6+/∑S with extent of S degassing at Erta Ale, indicating negligible effect on fO2, and further suggesting that H2S is the dominant gas species exsolved from the S2--rich melt (i.e., no redistribution of electrons). High SO2/H2S observed in Erta Ale gas emissions is due to gas re-equilibration at low pressure and fixed fO2. Sulfur budget considerations indicate that the majority of S injected into the systems is emitted as gas, which is therefore representative of the magmatic S isotope composition. The composition of the Masaya gas plume (+4.8‰) cannot be explained by fractionation effects but rather reflects recycling of high δ34S oxidized sulfur through the subduction zone.

  2. Impact of oxygen plasma postoxidation process on Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitors

    NASA Astrophysics Data System (ADS)

    Lechaux, Y.; Fadjie-Djomkam, A. B.; Bollaert, S.; Wichmann, N.

    2016-09-01

    Capacitance-voltage (C-V) measurements and x-ray photoelectron spectroscopy (XPS) analysis were performed in order to investigate the effect of a oxygen (O2) plasma after oxide deposition on the Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor structure passivated with ammonia NH4OH solution. From C-V measurements, an improvement of charge control is observed using the O2 plasma postoxidation process on In0.53Ga0.47As, while the minimum of interface trap density remains at a good value lower than 1 × 1012 cm-2 eV-1. From XPS measurements, we found that NH4OH passivation removes drastically the Ga and As native oxides on the In0.53Ga0.47As surface and the O2 plasma postoxidation process enables the reduction of interface re-oxidation after post deposition annealing (PDA) of the oxide. The advanced hypothesis is the formation of interfacial barrier between Al2O3 and In0.53Ga0.47As which prevents the diffusion of oxygen species into the semiconductor surface during PDA.

  3. Low-Temperature Crystallization of PbZr0.3Ti0.7O3 Film Induced by High-Oxygen-Pressure Processing

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaodong; Meng, Xiangjian; Sun, Jinglan; Lin, Tie; Ma, Jianhua; Chu, Junhao; Dho, Joonghoe

    2008-09-01

    A 300-nm-thick PbZr0.3Ti0.7O3 [PZT(30/70)] film was sputtered onto LaNiO3 (LNO)/Si(100) substrates at a substrate temperature of 200 °C and then annealed under an oxygen pressure of 4 MPa at 400 °C. The amorphous phase of the as-sputtered PZT(30/70) film was transformed to a highly (h00)-oriented perovskite phase by high-oxygen-pressure-processing (HOPP). The results of electrical measurements such as of polarization (P) as functions of applied electric field (E) (P-E hysteresis loops), the capacitance as functions of the applied dc electric field (C-E loops), and the dielectric constant (ɛr) and dissipation factor (tan δ) suggested that ferroelectric properties of PZT(30/70) films were largely improved by HOPP. We consider that HOPP is compatible with currently existing silicon-based technology, which is characterized by incorporating sputtering and a processing temperature limit of ˜450 °C. The P-E hyteresis loops obtained from a prototype of 128 ×128 uncooled infrared detector arrays prepared by HOPP supported the good ferroelectricity with a high pyroelectric coefficient.

  4. Processing of low carbon content interstellar ice analogues by cosmic rays: implications for the chemistry around oxygen-rich stars

    NASA Astrophysics Data System (ADS)

    de Barros, A. L. F.; da Silveira, E. F.; Pilling, S.; Domaracka, A.; Rothard, H.; Boduch, P.

    2014-03-01

    Radiolysis of a homogeneous H2O:H2CO:CH3OH (100:2:0.8) ice mixture by fast heavy ions is performed in the laboratory in an attempt to simulate the interaction of cosmic rays with frozen surfaces at 15 K. Bombarded by 220-MeV 16O7 + ions, the ice layer is thin enough to be traversed by projectiles at approximately constant velocity and with charge states close to the equilibrium one. Analysis by Fourier transform infrared spectroscopy (FTIR) reveals that the molecular species formed are CH4, CO2, CO, HCO, HCOO- and CH3OCHO. The formation and dissociation cross-sections of all observed daughter molecules are determined. As a control procedure, a carbon budget is performed as the beam fluence increases. The observed radiation effects lead to a general observation that the destruction cross-sections of condensed gases by heavy ions are ruled by a power law that is a function of the electronic stopping power: σd ˜ Sn_e, where n is approximately 3/2. This relation is observed for the destruction of precursor H2CO molecules and for the formation of daughter species. The present results help our understanding of the chemical and physicochemical interactions induced by heavy cosmic rays in cold astrophysical environments with low carbon contents, such as those around oxygen-rich stars.

  5. Assessing the effect of natural attenuation on oxygen consumption processes in a sewage-contaminated aquifer by use of a natural-gradient tracer test

    NASA Astrophysics Data System (ADS)

    Mathisen, P. P.; Kent, D. B.; Smith, R. L.; Barber, L. B.; Harvey, R. W.; Metge, D. W.; Hess, K. M.; Leblanc, D. R.; Koch, J. C.

    2003-12-01

    Processes associated with aquifer restoration subsequent to cessation of treated-sewage loading in a sand and gravel aquifer are being investigated at the USGS Toxic Substances Hydrology Site on Cape Cod, MA. Restoration has been slow because of significant oxygen depletion resulting from biogeochemical processes associated with residual sorbed pools of organic carbon, ammonium, and reduced metals in the aquifer. The in situ interaction of the physical, chemical, and biological processes governing oxygen consumption was examined by using a natural-gradient tracer test in fall 2001, 6 years after sewage disposal had been discontinued. Ground water with a high dissolved oxygen (DO) concentration was withdrawn from an uncontaminated zone of the aquifer and re-injected with a conservative tracer, bromide, into an anoxic zone directly below a former sewage-effluent disposal bed where Fe and sulfide concentrations were below detection and the DO was less than 5 uM. An injection with negligible ammonium, a nitrate concentration of 22 uM, and DO of approximately 260 uM was maintained at approximately 15 L/hr for a period of 75 days. An array of multi-level samplers (MLS), placed at distances ranging from 1 to 7 m down-gradient from the injection well, was sampled prior to and throughout the 75-day injection, and during a 25-day period after the injection. Water samples from the MLS were analyzed for DO and a variety of aqueous constituents. The DO decreased from approximately 260 uM to 210 uM over 7 m of transport, indicating the presence of rate-limited oxygen consumption. An increase in nitrate from 22 to approximately 36 uM indicated the presence of rate-limited ammonium oxidation. However, this ammonium oxidation was not sufficient to account for all of the DO consumption. Further characterization of these processes was accomplished by use of PHREEQC, a one-dimensional, geochemical reactive transport model. The 1D model is based on an ion association model for aqueous

  6. TiC supported Pt-Ir electrocatalyst prepared by a plasma process for the oxygen electrode in unitized regenerative fuel cells

    NASA Astrophysics Data System (ADS)

    Sui, Sheng; Ma, Lirong; Zhai, Yuchun

    Unitized regenerative fuel cells (URFCs) have become more attractive for some time due to its potentially wide energy storage application such as in fields of space and renewable energy. In this study, TiC supported Pt-Ir electrocatalysts (Pt-Ir/TiC) for oxygen electrode in URFCs were synthesized, respectively, by chemical reduction process and plasma reduction process. Their physical and electrochemical properties are characterized and compared using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammogram (CV), potentiostatic technique, and electrochemical impedance spectroscopy (EIS). The results from XRD, XPS and TEM demonstrate that the plasma process gives a finer metal crystals and higher metal dispersion on the TiC support. The CV, polarization, potentiostatic and EIS results show that the Pt-Ir/TiC electrocatalyst prepared by the plasma reduction process is obviously more active than that by the chemical reduction process, in agreement with the above metal-dispersion observations. The plasma process is a promising way for the preparation of supported electrocatalysts.

  7. Modeling and Numerical Investigation of the Process of Vapor-Oxygen Gasification of Solid Fuels in a Vertical Flow Reactor Under Pressure

    NASA Astrophysics Data System (ADS)

    Rokhman, B. B.

    2014-09-01

    With the use of the developed model, detailed information has been obtained on the working process in a flow reactor with single- and two-stage schemes of vapor-oxygen gasification of coals under a pressure of 3 MPa. The dependence of the ratios of mass flow rates O2/coal and H2O/coal on the type of fuel has been established and their optimal values for the "Shell" process have been found. At a given consumption ratio of gas coal and brown coal of brand B1, the optimum diameters of particles providing minimum combustible loss of the carbon mixture have been determined. It has been found that the content of methane in the syngas in the case of two-stage gasification is much higher than in the case of single-stage gasification.

  8. Elucidating microbial processes in nitrate- and sulfate-reducing systems using sulfur and oxygen isotope ratios: The example of oil reservoir souring control

    NASA Astrophysics Data System (ADS)

    Hubert, Casey; Voordouw, Gerrit; Mayer, Bernhard

    2009-07-01

    Sulfate-reducing bacteria (SRB) are ubiquitous in anoxic environments where they couple the oxidation of organic compounds to the production of hydrogen sulfide. This can be problematic for various industries including oil production where reservoir "souring" (the generation of H 2S) requires corrective actions. Nitrate or nitrite injection into sour oil fields can promote SRB control by stimulating organotrophic nitrate- or nitrite-reducing bacteria (O-NRB) that out-compete SRB for electron donors (biocompetitive exclusion), and/or by lithotrophic nitrate- or nitrite-reducing sulfide oxidizing bacteria (NR-SOB) that remove H 2S directly. Sulfur and oxygen isotope ratios of sulfide and sulfate were monitored in batch cultures and sulfidic bioreactors to evaluate mitigation of SRB activities by nitrate or nitrite injection. Sulfate reduction in batch cultures of Desulfovibrio sp. strain Lac15 indicated typical Rayleigh-type fractionation of sulfur isotopes during bacterial sulfate reduction (BSR) with lactate, whereas oxygen isotope ratios in unreacted sulfate remained constant. Sulfur isotope fractionation in batch cultures of the NR-SOB Thiomicrospira sp. strain CVO was minimal during the oxidation of sulfide to sulfate, which had δ18O SO4 values similar to that of the water-oxygen. Treating an up-flow bioreactor with increasing doses of nitrate to eliminate sulfide resulted in changes in sulfur isotope ratios of sulfate and sulfide but very little variation in oxygen isotope ratios of sulfate. These observations were similar to results obtained from SRB-only, but different from those of NR-SOB-only pure culture control experiments. This suggests that biocompetitive exclusion of SRB took place in the nitrate-injected bioreactor. In two replicate bioreactors treated with nitrite, less pronounced sulfur isotope fractionation and a slight decrease in δ18O SO4 were observed. This indicated that NR-SOB played a minor role during dosing with low nitrite and that

  9. Oxygen Therapy

    MedlinePlus

    ... They can serve as a backup during a power outage or equipment issue. What is a nasal cannula? A nasal cannula is a two-pronged tube that is placed in your nose for delivering oxygen. The other end of the tube is attached to your oxygen system. A nasal cannula has the ability to deliver ...

  10. Appreciating Oxygen

    ERIC Educational Resources Information Center

    Weiss, Hilton M.

    2008-01-01

    Photosynthetic flora and microfauna utilize light from the sun to convert carbon dioxide and water into carbohydrates and oxygen. While these carbohydrates and their derivative hydrocarbons are generally considered to be fuels, it is the thermodynamically energetic oxygen molecule that traps, stores, and provides almost all of the energy that…

  11. Appreciating Oxygen

    ERIC Educational Resources Information Center

    Weiss, Hilton M.

    2008-01-01

    Photosynthetic flora and microfauna utilize light from the sun to convert carbon dioxide and water into carbohydrates and oxygen. While these carbohydrates and their derivative hydrocarbons are generally considered to be fuels, it is the thermodynamically energetic oxygen molecule that traps, stores, and provides almost all of the energy that…

  12. Oxygen "getter" effects on microstructure and carrier transport in low temperature combustion-processed a-InXZnO (X = Ga, Sc, Y, La) transistors.

    PubMed

    Hennek, Jonathan W; Smith, Jeremy; Yan, Aiming; Kim, Myung-Gil; Zhao, Wei; Dravid, Vinayak P; Facchetti, Antonio; Marks, Tobin J

    2013-07-24

    In oxide semiconductors, such as those based on indium zinc oxide (IXZO), a strong oxygen binding metal ion ("oxygen getter"), X, functions to control O vacancies and enhance lattice formation, hence tune carrier concentration and transport properties. Here we systematically study, in the IXZO series, the role of X = Ga(3+) versus the progression X = Sc(3+) → Y(3+) → La(3+), having similar chemical characteristics but increasing ionic radii. IXZO films are prepared from solution over broad composition ranges for the first time via low-temperature combustion synthesis. The films are characterized via thermal analysis of the precursor solutions, grazing incidence angle X-ray diffraction (GIAXRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM) with high angle annular dark field (HAADF) imaging. Excellent thin-film transistor (TFT) performance is achieved for all X, with optimal compositions after 300 °C processing exhibiting electron mobilities of 5.4, 2.6, 2.4, and 1.8 cm(2) V(-1) s(-1) for Ga(3+), Sc(3+), Y(3+), and La(3+), respectively, and with I(on)/I(off) = 10(7)-10(8). Analysis of the IXZO TFT positive bias stress response shows X = Ga(3+) to be superior with mobilities (μ) retaining >95% of the prestress values and threshold voltage shifts (ΔV(T)) of <1.6 V, versus <85% μ retention and ΔV(T) ≈ 20 V for the other trivalent ions. Detailed microstructural analysis indicates that Ga(3+) most effectively promotes oxide lattice formation. We conclude that the metal oxide lattice formation enthalpy (ΔH(L)) and metal ionic radius are the best predictors of IXZO oxygen getter efficacy.

  13. Evaluation of reactive oxygen species generating AirOcare system for reducing airborne microbial populations in a meat processing plant

    USDA-ARS?s Scientific Manuscript database

    The microbial contamination of meat and meat products is of continuing concern to the meat industry and regulatory agencies. Air has been established as a source of microbial contamination in slaughter and processing facilities. The objective of this research was to determine the efficacy of reactiv...

  14. Mass independent oxygen and sulfur isotopic compositions of environmental sulfate and nitrate. A new probe of atmospheric, hydrospheric and geological processes

    NASA Astrophysics Data System (ADS)

    Thiemens, M.; Michalski, G.; Romero, A.; McCabe, J.

    2003-04-01

    Aerosol sulfate is well known to exert a significant influence on the Earth’s atmosphere and surface. They mediate climate in its capacity as a cloud condensation nuclei (CCN) and as a visible light scattering agent. These particles are respirable, with severe cardiovascular disease consequences. Removal by wet and dry depositions is well known to cause surficial damage to biota, biodiversity, and structures. Despite decades of high precision global concentration measurements, single isotope ratio measurements (d18O, d34S) and high quality modeling efforts, there remain unresolved issues with respect to resolution of relative oxidative processes (homogenous vs. heterogeneous), transformation mechanisms, and identification of sources, proximal and distal. Mass independent oxygen isotopic compositions have added new insights un attainable by other techniques. These observations ideally complement other measurements in an effort to improve parameters used in modeling aerosols and climate. Recent sulfur mass independent compositions have potentially added a new means to recognize upper atmospheric photolytic processes. Aerosol nitrate is estimated to nearly double in the next half century, with potentially severe consequences which include soil acidification, loss of biodiversity, eutrophication of coastal and freshwaters, and, human cardiovascular disease. Loss of fresh water lake clarity, e.g. Lake Tahoe is also believed to occur due to increased nitrogen levels. As in the case of atmospheric sulfate, mass independent oxygen isotopic signatures have been observed in nitrate. The D17O is one of the largest mass independent isotopic signatures observed in any environmental species with the exception of ozone. These measurements have demonstrated the ability to provide new insight into the nitrogen cycle, including atmospheric, hydrospheric and geologic processes.

  15. Melt processing of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor in oxygen and argon atmospheres

    SciTech Connect

    Holesinger, T.G.; Miller, D.J.; Chumbley, L.S.

    1992-08-01

    Solidification and subsequent annealing of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O{sub 2} and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi{sub 2}Sr{sub 3-x}Ca{sub x}O{sub y} and Cu{sub 2}O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi{sub 2.15}Sr{sub 2}Ca{sub 0.85}Cu{sub 2}O{sub y}.

  16. Melt processing of the Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y] superconductor in oxygen and argon atmospheres

    SciTech Connect

    Holesinger, T.G.; Miller, D.J. ); Chumbley, L.S. )

    1992-08-01

    Solidification and subsequent annealing of Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub y] (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O[sub 2] and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi[sub 2]Sr[sub 3-x]Ca[sub x]O[sub y] and Cu[sub 2]O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi[sub 2.15]Sr[sub 2]Ca[sub 0.85]Cu[sub 2]O[sub y].

  17. Identification and roles of nonstoichiometric oxygen in amorphous Ta2O5 thin films deposited by electron beam and sputtering processes

    NASA Astrophysics Data System (ADS)

    Mannequin, Cedric; Tsuruoka, Tohru; Hasegawa, Tsuyoshi; Aono, Masakazu

    2016-11-01

    The morphology and composition of tantalum oxide (Ta2O5) thin films prepared by electron-beam (EB) evaporation and radio-frequency sputtering (SP) were investigated by grazing incidence X-ray diffraction (GIXRD), X-ray reflectometry (XRR), atomic force microscopy, Fourier transformed infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). GIXRD revealed an amorphous nature for both films, and XRR showed that the density of the Ta2O5-EB films was lower than that of the Ta2O5-SP films; both films have lower density than the bulk value. A larger amount of molecular water and peroxo species were detected for the Ta2O5-EB films by FTIR performed in ambient atmosphere. XPS analyses performed in vacuum confirmed the presence of hydroxyl groups, but no trace of chemisorbed molecular water was detected. In addition, a higher oxygen nonstoichiometry (higher O/Ta ratio) was found for the EB films. From these results, we conclude that the oxygen nonstoichiometry of the EB film accounted for its lower density and higher amount of absorbed molecular water. The results also suggest the importance of understanding the dependence of the structural and chemical properties of thin amorphous oxide films on the deposition process.

  18. Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates.

    SciTech Connect

    Lyons, J.E.

    1992-07-01

    The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

  19. Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates

    SciTech Connect

    Lyons, J.E.

    1992-01-01

    The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

  20. Effects of dissolved oxygen on performance and microbial community structure in a micro-aerobic hydrolysis sludge in situ reduction process.

    PubMed

    Niu, Tianhao; Zhou, Zhen; Shen, Xuelian; Qiao, Weimin; Jiang, Lu-Man; Pan, Wei; Zhou, Jijun

    2016-03-01

    A sludge process reduction activated sludge (SPRAS), with a sludge process reduction module composed of a micro-aerobic tank and a settler positioned before conventional activated sludge process, showed good performance of pollutant removal and sludge reduction. Two SPRAS systems were operated to investigate effects of micro-aeration on sludge reduction performance and microbial community structure. When dissolved oxygen (DO) concentration in the micro-aerobic tank decreased from 2.5 (SPH) to 0.5 (SPL) mg/L, the sludge reduction efficiency increased from 42.9% to 68.3%. Compared to SPH, activated sludge in SPL showed higher contents of extracellular polymeric substances and dissolved organic matter. Destabilization of floc structure in the settler, and cell lysis in the sludge process reduction module were two major reasons for sludge reduction. Illumina-MiSeq sequencing showed that microbial diversity decreased under high DO concentration. Proteobacteria, Bacteroidetes and Chloroflexi were the most abundant phyla in the SPRAS. Specific comparisons down to the class and genus level showed that fermentative, predatory and slow-growing bacteria in SPL community were more abundant than in SPH. The results revealed that micro-aeration in the SPRAS improved hydrolysis efficiency and enriched fermentative and predatory bacteria responsible for sludge reduction.

  1. Enhanced neuropeptide Y synthesis during intermittent hypoxia in the rat adrenal medulla: role of reactive oxygen species-dependent alterations in precursor peptide processing.

    PubMed

    Raghuraman, Gayatri; Kalari, Apeksha; Dhingra, Rishi; Prabhakar, Nanduri R; Kumar, Ganesh K

    2011-04-01

    Intermittent hypoxia (IH) associated with recurrent apneas often leads to cardiovascular abnormalities. Previously, we showed that IH treatment elevates blood pressure and increases plasma catecholamines (CAs) in rats via reactive oxygen species (ROS)-dependent enhanced synthesis and secretion from the adrenal medulla (AM). Neuropeptide Y (NPY), a sympathetic neurotransmitter that colocalizes with CA in the AM, has been implicated in blood pressure regulation during persistent stress. Here, we investigated whether IH facilitates NPY synthesis in the rat AM and assessed the role of ROS signaling. IH increased NPY-like immunoreactivity in many dopamine-β-hydroxylase-expressing chromaffin cells with a parallel increase in preproNPY mRNA and protein. IH increased the activities of proNPY-processing enzymes, which were due, in part, to elevated protein expression and increased proteolytic processing. IH increased ROS generation, and antioxidants reversed IH-induced increases in ROS, preproNPY, and its processing to bioactive NPY in the AM. IH treatment increased blood pressure and antioxidants and inhibition of NPY amidation prevented this response. These findings suggest that IH-induced elevation in NPY expression in the rat AM is mediated by ROS-dependent augmentation of preproNPY mRNA expression and proNPY-processing enzyme activities and contributes to IH-induced elevation of blood pressure.

  2. Effect of the increase in the entrance convergent section length of the gun nozzle on the high-velocity oxygen fuel and cold spray process

    NASA Astrophysics Data System (ADS)

    Sakaki, K.; Shimizu, Y.

    2001-09-01

    Nozzle geometry, which influences combustion gas dynamics and, therefore, sprayed particle behavior, is one of the most important parameters in the high-velocity oxygen-fuel (HVOF) thermal spray process. The nozzle geometry is also important in the cold spray method. The gas flows in the entrance convergent section of the nozzle exhibit a relatively higher temperature and are subsonic; thus, this region is most suitable for heating spray particles. In this study, numerical simulation and experiments investigated the effect of the entrance geometry of the gun nozzle on the HVOF process. The process changes inside the nozzle, as obtained by numerical simulation studies, were related to the coating properties. An Al2O3-40 mass% TiO2 powder was used for the experimental studies. The change in entrance convergent section length (rather than barrel part length or total length) of the gun nozzle had a significant effect on the deposition efficiency, microstructure, and hardness. The deposition efficiency and hardness increased as this geometry increased. On the other hand, the calculated and measured particle velocity showed a slight decrease. This effect on the HVOF process will also be applied to the nozzle design for the cold spray method.

  3. Oxygen safety

    MedlinePlus

    ... a restaurant, keep at least 6 feet (2 meters) away from any source of fire, such as ... or tabletop candle. Keep oxygen 6 feet (2 meters) away from: Toys with electric motors Electric baseboard ...

  4. Reduction of N2O and NO generation in anaerobic-aerobic (low dissolved oxygen) biological wastewater treatment process by using sludge alkaline fermentation liquid.

    PubMed

    Zhu, Xiaoyu; Chen, Yinguang

    2011-03-15

    This paper reported an efficient method to significantly reduce nitrous oxide (N(2)O) and nitric oxide (NO) generation in anaerobic-aerobic (low dissolved oxygen) processes. It was found that by the use of waste-activated sludge alkaline fermentation liquid as the synthetic wastewater-carbon source, compared with the commonly used carbon source in the literature (e.g., acetic acid), the generation of N(2)O and NO was reduced by 68.7% and 50.0%, respectively, but the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) were improved. Both N(2)O and NO were produced in the low dissolved oxygen (DO) stage, and the use of sludge fermentation liquid greatly reduced their generation from the denitrification. The presences of Cu(2+) and propionic acid in fermentation liquid were observed to play an important role in the reduction of N(2)O and NO generation. The analysis of the activities of denitrifying enzymes suggested that sludge fermentation liquid caused the significant decrease of both nitrite reductase activity to NO reductase activity ratio and NO reductase activity to N(2)O reductase activity ratio, which resulted in the lower generation of NO and N(2)O. Fluorescence in situ hybridization analysis indicated that the number of glycogen accumulating bacteria, which was reported to be relevant to nitrous oxide generation, in sludge fermentation liquid reactor was much lower than that in acetic acid reactor. The quantitative detection of the nosZ gene, encoding nitrous oxide reductase, showed that the use of fermentation liquid increased the number of bacteria capable of reducing N(2)O to N(2). The feasibility of using sludge fermentation liquid to reduce NO and N(2)O generation in an anaerobic-low DO process was finally confirmed for a municipal wastewater.

  5. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-07-01

    In the present quarter, oxygen transport perovskite ceramic membranes are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  6. Flux Pinning and Properties of Solid-Solution (Y,Nd)1+XBa2-x Cu3O7-delta Superconductors Processed in Air and Partial Oxygen Atmospheres (Preprint)

    DTIC Science & Technology

    2004-04-01

    AFRL-PR-WP-TP-2006-204 FLUX PINNING AND PROPERTIES OF SOLID - SOLUTION (Y,Nd)1+XBa2-xCu3O7-δ SUPERCONDUCTORS PROCESSED IN AIR AND PARTIAL...SUBTITLE FLUX PINNING AND PROPERTIES OF SOLID - SOLUTION (Y,Nd)i+),(Ba,_„ Cu3 07_5 SUPERCONDUCTORS PROCESSED IN AIR AND PARTIAL OXYGEN ATMOSPHERES (PREPRINT

  7. Processes affecting oxygen isotope ratios of atmospheric and ecosystem sulfate in two contrasting forest catchments in Central Europe

    SciTech Connect

    Martin Novak; Myron J. Mitchell; Iva Jackova; Frantisek Buzek; Jana Schweigstillova; Lucie Erbanova; Richard Prikryl; Daniela Fottova

    2007-02-15

    Sulfate aerosols are harmful as respirable particles. They also play a role as cloud condensation nuclei and have radiative effects on global climate. A combination of {delta}{sup 18}O-SO{sub 4} data with catchment sulfur mass balances was used to constrain processes affecting S cycling in the atmosphere and spruce forests of the Czech Republic. Extremely high S fluxes via spruce throughfall and runoff were measured at Jezeri (49 and 80 kg S ha{sup -1} yr{sup -1}, respectively). The second catchment, Na Lizu, was 10 times less polluted. In both catchments, {delta}{sup 18}O-SO{sub 4} decreased in the following order: open-area precipitation {gt} throughfall {gt} runoff. The 180-SO{sub 4} values of throughfall exhibited a seasonal pattern at both sites, with maxima in summer and minima in winter. This seasonal pattern paralleled {delta}{sup 18}O-H{sub 2}O values, which were offset by -18{per_thousand}. Sulfate in throughfall was predominantly formed by heterogeneous (aqueous) oxidation of SO{sub 2}. Wet-deposited sulfate in an open area did not show systematic {delta}{sup 18}O-SO{sub 4} trends, suggesting formation by homogeneous (gaseous) oxidation and/or transport from large distances. The percentage of incoming S that is organically cycled in soil was similar under the high and the low pollution. High-temperature {sup 18}O-rich sulfate was not detected, which contrasts with North American industrial sites. 29 refs., 4 figs., 3 tabs.

  8. Numerical Simulation of the Interaction Between Supersonic Oxygen Jets and Molten Slag-Metal Bath in Steelmaking BOF Process

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Li, Mingming; Kuang, Shibo; Zou, Zongshu

    2015-02-01

    The impinging of multiple jets onto the molten bath in the BOF steelmaking process plays a crucial role in reactor performance but is not clearly understood. This paper presents a numerical study of the interaction between the multiple jets and slag-metal bath in a BOF by means of the three-phase volume of fluid model. The validity of the model is first examined by comparing the numerical results with experimental measurement of time-averaged cavity dimensions through a scaled-down water model. The calculated results are in reasonably good agreement with the experimental data. The mathematical model is then used to investigate the primary transport phenomena of the jets-bath interaction inside a 150-ton commercial BOF under steelmaking conditions. The numerical results show that the cavity profile and interface of slag/metal/gas remain unstable as a result of the propagation of surface waves, which, likely as a major factor, governs the generation of metal droplets and their initial spatiotemporal distribution. The total momentum transferred from the jets into the bath is consumed about a half to drive the movement of slag, rather than fully converted as the stirring power for the metal bath. Finally, the effects of operational conditions and fluid properties are quantified. It is shown that compared to viscosity and surface tension of the melts, operating pressure and lance height have a much more significant impact on the slag-metal interface behavior and cavity shape as well as the fluid dynamics in the molten bath.

  9. Effects of pH, Temperature, Dissolved Oxygen, and Flow Rate on Phosphorus Release Processes at the Sediment and Water Interface in Storm Sewer

    PubMed Central

    Li, Haiyan; Li, Mingyi; Zhang, Xiaoran

    2013-01-01

    The effects of pH, temperature, dissolved oxygen (DO), and flow rate on the phosphorus (P) release processes at the sediment and water interface in rainwater pipes were investigated. The sampling was conducted in a residential storm sewer of North Li Shi Road in Xi Cheng District of Beijing on August 3, 2011. The release rate of P increased with the increase of pH from 8 to 10. High temperature is favorable for the release of P. The concentration of total phosphorus (TP) in the overlying water increased as the concentration of DO decreased. With the increase of flow rate from 0.7 m s−1 to 1.1 m s−1, the concentration of TP in the overlying water increased and then tends to be stable. Among all the factors examined in the present study, the flow rate is the primary influence factor on P release. The cumulative amount of P release increased with the process of pipeline runoff in the rainfall events with high intensities and shorter durations. Feasible measures such as best management practices and low-impact development can be conducted to control the P release on urban sediments by slowing down the flow rate. PMID:24349823

  10. Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

    NASA Astrophysics Data System (ADS)

    Watanabe, Toshiyuki; Kano, Makoto; Yoshida, Kentaro; Suzuki, Tetsuya

    2012-09-01

    The topics of the applied technology of amorphous carbon film to reduce friction using diamond-like carbon (DLC) coated by the vacuum arc ion plating process and to improve the gas barrier property using the amorphous carbon film by the atmospheric pressure plasma process are introduced with the basic experimental results. For reducing friction, the super low friction coefficient below 0.01 has been found when the tetrahedral amorphous carbon coating deposited by T-shape filtered arc deposition method [ta-C(T)] was evaluated the friction property under oleic acid lubrication at pure sliding condition. It was thought that the low share strength tribofilm composed of water and oleic acid mono-layer seemed to be formed on the sliding interface. For gas barrier performance, the amorphous carbon film deposited by the atmospheric pressure plasma chemical vapour deposition (CVD) technique on poly(ethylene terephthalate) (PET) substrate was improved the oxygen transmission ratio (OTR) around 30% compared with that of uncoated PET substrate. These advanced performance obtained by the optimum material combination of DLC with lubricant and the original atmospheric pressure plasma CVD technique are expected to be applied on the actual application for the different types of the industrial fields in near future.

  11. Improved curdlan fermentation process based on optimization of dissolved oxygen combined with pH control and metabolic characterization of Agrobacterium sp. ATCC 31749.

    PubMed

    Zhang, Hong-Tao; Zhan, Xiao-Bei; Zheng, Zhi-Yong; Wu, Jian-Rong; English, Nike; Yu, Xiao-Bin; Lin, Chi-Chung

    2012-01-01

    A significant problem in scale-down cultures, rarely studied for metabolic characterization and curdlan-producing Agrobacterium sp. ATCC 31749, is the presence of dissolved oxygen (DO) gradients combined with pH control. Constant DO, between 5% and 75%, was maintained during batch fermentations by manipulating the agitation with PID system. Fermentation, metabolic and kinetic characterization studies were conducted in a scale-down system. The curdlan yield, intracellular nucleotide levels and glucose conversion efficiency into curdlan were significantly affected by DO concentrations. The optimum DO concentrations for curdlan production were 45-60%. The average curdlan yield, curdlan productivity and glucose conversion efficiency into curdlan were enhanced by 80%, 66% and 32%, respectively, compared to that at 15% DO. No apparent difference in the gel strength of the resulting curdlan was detected. The comparison of curdlan biosynthesis and cellular nucleotide levels showed that curdlan production had positive relationship with intracellular levels of UTP, ADP, AMP, NAD(+), NADH and UDP-glucose. The curdlan productivity under 45% DO and 60% DO was different during 20-50 h. However, after 60 h curdlan productivity of both conditions was similar. On that basis, a simple and reproducible two-stage DO control process for curdlan production was developed. Curdlan production yield reached 42.8 g/l, an increase of 30% compared to that of the single agitation speed control process.

  12. Processing 2-Methyl-l-Tryptophan through Tandem Transamination and Selective Oxygenation Initiates Indole Ring Expansion in the Biosynthesis of Thiostrepton.

    PubMed

    Lin, Zhi; Ji, Jia; Zhou, Shuaixiang; Zhang, Fang; Wu, Jiequn; Guo, Yinlong; Liu, Wen

    2017-09-06

    Thiostrepton (TSR), an archetypal member of the family of ribosomally synthesized and post-translationally modified thiopeptide antibiotics, possesses a biologically important quinaldic acid (QA) moiety within the side-ring system of its characteristic thiopeptide framework. QA is derived from an independent l-Trp residue; however, its associated transformation process remains poorly understood. We here report that during the formation of QA, the key expansion of an indole to a quinoline relies on the activities of the pyridoxal-5'-phosphate-dependent protein TsrA and the flavoprotein TsrE. These proteins act in tandem to process the precursor 2-methyl- l-Trp through reversible transamination and selective oxygenation, thereby initiating a highly reactive rearrangement in which selective C2-N1 bond cleavage via hydrolysis for indole ring-opening is closely coupled with C2'-N1 bond formation via condensation for recyclization and ring expansion in the production of a quinoline ketone intermediate. This indole ring-expansion mechanism is unusual, and represents a new strategy found in nature for l-Trp-based functionalization.

  13. Partial nitrification and denitrification of mature landfill leachate using a pilot-scale continuous activated sludge process at low dissolved oxygen.

    PubMed

    Chen, Zhenguo; Wang, Xiaojun; Yang, YongYuan; Mirino, Markus W; Yuan, Yanlei

    2016-10-01

    Controlling of low dissolved oxygen (DO) levels (0.1-0.5mg/L), a cost-effective strategy, was applied to a pilot-scale anoxic-oxic-oxic-anoxic process for partial nitrification and denitrification of mature landfill leachate. High ammonium removal efficiency, stable nitrite accumulation rate and total nitrogen removal efficiency was higher than 95.0%, 90.0% and 66.4%, respectively, implying potential application of this process for nitrogen removal of mature landfill leachate. Efficient nitrite accumulation in the first oxic reactor depended on low DO conditions and sufficient alkalinity. However, operational limit was mainly decided by actual hydraulic retention time (AHRT) of the first oxic reactor and appeared with AHRT less than 13.9h under DO of 0.3-0.5mg/L. High-throughput sequencing analysis demonstrated significant change of bacterial diversity in the first oxic reactor after a long-term operation and dominant bacteria genus Nitrosomonas was shown to be responsible for NH4(+)-N removal and nitrite accumulation under low DO levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Determining Carbon and Oxygen Stable Isotope Systematics in Brines at Elevated p/T Conditions to Enhance Monitoring of CO2 Induced Processes in Carbon Storage Reservoirs

    NASA Astrophysics Data System (ADS)

    Becker, V.; Myrttinen, A.; Mayer, B.; Barth, J. A.

    2012-12-01

    Stable carbon isotope ratios (δ13C) are a powerful tool for inferring carbon sources and mixing ratios of injected and baseline CO2 in storage reservoirs. Furthermore, CO2 releasing and consuming processes can be deduced if the isotopic compositions of end-members are known. At low CO2 pressures (pCO2), oxygen isotope ratios (δ18O) of CO2 usually assume the δ18O of the water plus a temperature-dependent isotope fractionation factor. However, at very high CO2 pressures as they occur in CO2 storage reservoirs, the δ18O of the injected CO2 may in fact change the δ18O of the reservoir brine. Hence, changing δ18O of brine constitutes an additional tracer for reservoir-internal carbon dynamics and allows the determination of the amount of free phase CO2 present in the reservoir (Johnson et al. 2011). Further systematic research to quantify carbon and oxygen isotope fractionation between the involved inorganic carbon species (CO2, H2CO3, HCO3-, CO32-, carbonate minerals) and kinetic and equilibrium isotope effects during gas-water-rock interactions is necessary because p/T conditions and salinities in CO2 storage reservoirs may exceed the boundary conditions of typical environmental isotope applications, thereby limiting the accuracy of stable isotope monitoring approaches in deep saline formations (Becker et al. 2011). In doing so, it is crucial to compare isotopic patterns observed in laboratory experiments with artificial brines to similar experiments with original fluids from representative field sites to account for reactions of dissolved inorganic carbon (DIC) with minor brine components. In the CO2ISO-LABEL project, funded by the German Ministry for Education and Research, multiple series of laboratory experiments are conducted to determine the influence of pressure, temperature and brine composition on the δ13C of DIC and the δ18O of brines in water-CO2-rock reactions with special focus placed on kinetics and stable oxygen and carbon isotope fractionation

  15. Dissolved oxygen: Chapter 6

    USGS Publications Warehouse

    Senn, David; Downing-Kunz, Maureen; Novick, Emily

    2016-01-01

    Dissolved oxygen (DO) concentration serves as an important indicator of estuarine habitat condition, because all aquatic macro-organisms require some minimum DO level to survive and prosper. The instantaneous DO concentration, measured at a specific location in the water column, results from a balance between multiple processes that add or remove oxygen (Figure 6.1): primary production produces O2; aerobic respiration in the water column and sediments consumes O2; abiotic or microbially-mediated biogeochemical reactions utilize O2 as an oxidant (e.g., oxidation of ammonium, sulfide, and ferrous iron); O2 exchange occurs across the air:water interface in response to under- or oversaturated DO concentrations in the water column; and water currents and turbulent mixing transport DO into and out of zones in the water column. If the oxygen loss rate exceeds the oxygen production or input rate, DO concentration decreases. When DO losses exceed production or input over a prolonged enough period of time, hypoxia ((<2-3 mg/L) or anoxia can develop. Persistent hypoxia or anoxia causes stress or death in aquatic organism populations, or for organisms that can escape a hypoxic or anoxic area, the loss of habitat. In addition, sulfide, which is toxic to aquatic organisms and causes odor problems, escapes from sediments under low oxygen conditions. Low dissolved oxygen is a common aquatic ecosystem response to elevated organic

  16. The oxygen-binding vs. oxygen-consuming paradigm in biocatalysis: structural biology and biomolecular simulation.

    PubMed

    Baron, Riccardo; McCammon, J Andrew; Mattevi, Andrea

    2009-12-01

    Oxygen biocatalysis and regulation is crucial to a variety of biochemical processes in nature. Oxygen-binding proteins cover only a limited part of oxygen biocatalysis, which involves numerous examples of oxygen-consuming biocatalysts with low oxygen affinities. The integration of experiments with powerful biomolecular simulation opens appealing possibilities to investigate crucial questions on the fascinating relationship between enzyme dynamics and oxygen biocatalysis in new protein structures.

  17. Process for the synthesis of symmetric and unsymmetric oxygen bridged dimers of boron subphthalocyanines (μ-oxo-(BsubPc)2s).

    PubMed

    Dang, Jeremy D; Fulford, Mabel V; Kamino, Brett A; Paton, Andrew S; Bender, Timothy P

    2015-03-07

    A process for the gram scale synthesis of the oxygen bridged dimer of boron subphthalocyanine, μ-oxo-(BsubPc)2, has been developed. During the development it was found that a wide range of reaction pathways under diverse conditions lead to μ-oxo-(BsubPc)2 formation. However, obtaining μ-oxo-(BsubPc)2 as the main reaction product in appreciable yields and its subsequent isolation were extremely challenging. The best balance of purity, yield and conversion was achieved with a time controlled reaction of an equimolar reaction of HO-BsubPc with Br-BsubPc in the presence of K3PO4. The purification involved sequentially Soxhlet extraction, Kauffman column chromatography and train sublimation. We have repeated the process and yields ranged from 27 to 30% of pure, doubly-sublimed μ-oxo-(BsubPc)2. This process also enabled the synthesis of unsymmetric μ-oxo-(BsubPc)2s by reaction of HO-BsubPc with Br-F12BsubPc, Cl-Cl6BsubPc and Cl-Cl12BsubPc. After synthesis the solution-state properties of the unsymmetric μ-oxo-(BsubPc)2s were investigated, and compared to the symmetric μ-oxo-(BsubPc)2 and more broadly to other BsubPcs. The electronic properties of μ-oxo-(BsubPc)2 were found to differ from its unsymmetric counterparts, but were found to be similar to halo-BsubPcs. Furthermore, the photophysical properties of μ-oxo-(BsubPc)2, both symmetric and unsymmetric, differed greatly from all other known BsubPcs.

  18. Oxygen-reducing catalyst layer

    DOEpatents

    O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  19. The role of Ar plasma treatment in generating oxygen vacancies in indium tin oxide thin films prepared by the sol-gel process

    NASA Astrophysics Data System (ADS)

    Hwang, Deuk-Kyu; Misra, Mirnmoy; Lee, Ye-Eun; Baek, Sung-Doo; Myoung, Jae-Min; Lee, Tae Il

    2017-05-01

    Argon (Ar) plasma treatment was carried out to reduce the sheet resistance of indium tin oxide (ITO) thin films. The Ar plasma treatment did not cause any significant changes to the crystal structure, surface morphology, or optical properties of the ITO thin films. However, an X-ray photoelectron spectroscopy study confirmed that the concentration of oxygen vacancies in the film dramatically increased with the plasma treatment time. Thus, we concluded that the decrease in the sheet resistance was caused by the increase in the oxygen vacancy concentration in the film. Furthermore, to verify how the concentration of oxygen vacancies in the film increased with the Ar plasma treatment time, cumulative and continuous plasma treatments were conducted. The oxygen vacancies were found to be created by surface heating via the outward thermal diffusion of oxygen atoms from inside the film.

  20. Influence of wastewater type on the impact generated by TiO2 nanoparticles on the oxygen uptake rate in activated sludge process.

    PubMed

    Cervantes-Avilés, Pabel; Camarillo Piñas, Nayeli; Ida, Junichi; Cuevas-Rodríguez, Germán

    2017-04-01

    Physicochemical characteristics of wastewater have a relationship with the stability of TiO2 nanoparticles (NPs). This in turn has an effect on the toxicity of TiO2 NPs in microorganisms. In this work, the effect of TiO2 NPs on activated sludge process was evaluated using three different types of wastewater: synthetic, raw, and filtered. The results showed that aggregate size of TiO2 NPs and their specific adsorption of substrates were influenced by the type of substrates and the presence of suspended solids in the wastewater. It was also shown that TiO2 NPs in raw wastewater severely inhibited oxygen uptake by microorganisms as compared to uptake in synthetic or filtered wastewater. The attachment of TiO2 NP aggregates on cell membranes was observed for all types of wastewater. However, the internalization of TiO2 NPs by microorganisms was observed only for raw and filtered wastewater. These results indicate that the effects caused by TiO2 NPs on activated sludge were different depending on the wastewater used for the experiment.

  1. Economic process to co-produce poly(ε-l-lysine) and poly(l-diaminopropionic acid) by a pH and dissolved oxygen control strategy.

    PubMed

    Xu, Zhaoxian; Feng, Xiaohai; Sun, Zhuzhen; Cao, Changhong; Li, Sha; Xu, Zheng; Xu, Zongqi; Bo, Fangfang; Xu, Hong

    2015-01-01

    This study tended to apply biorefinery of indigenous microbes to the fermentation of target-product generation through a novel control strategy. A novel strategy for co-producing two valuable homopoly(amino acid)s, poly(ε-l-lysine) (ε-PL) and poly(l-diaminopropionic acid) (PDAP), was developed by controlling pH and dissolved oxygen concentrations in Streptomyces albulus PD-1 fermentation. The production of ε-PL and PDAP got 29.4 and 9.6gL(-1), respectively, via fed-batch cultivation in a 5L bioreactor. What is more, the highest production yield (21.8%) of similar production systems was achieved by using this novel strategy. To consider the economic-feasibility, large-scale production in a 1t fermentor was also implemented, which would increase the gross profit of 54,243.5USD from one fed-batch bioprocess. This type of fermentation, which produces multiple commercial products from a unified process is attractive, because it will improve the utilization rate of raw materials, enhance production value and enrich product variety. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Kinetic Modeling Reveals the Roles of Reactive Oxygen Species Scavenging and DNA Repair Processes in Shaping the Dose-Response Curve of KBrO₃-Induced DNA Damage.

    PubMed

    Spassova, Maria A; Miller, David J; Nikolov, Alexander S

    2015-01-01

    We have developed a kinetic model to investigate how DNA repair processes and scavengers of reactive oxygen species (ROS) can affect the dose-response shape of prooxidant induced DNA damage. We used as an example chemical KBrO3 which is activated by glutathione and forms reactive intermediates that directly interact with DNA to form 8-hydroxy-2-deoxyguanosine DNA adducts (8-OH-dG). The single strand breaks (SSB) that can result from failed base excision repair of these adducts were considered as an effect downstream from 8-OH-dG. We previously demonstrated that, in the presence of effective base excision repair, 8-OH-dG can exhibit threshold-like dose-response dependence, while the downstream SSB can still exhibit a linear dose-response. Here we demonstrate that this result holds for a variety of conditions, including low levels of GSH, the presence of additional SSB repair mechanisms, or a scavenger. It has been shown that melatonin, a terminal scavenger, inhibits KBrO3-caused oxidative damage. Our modeling revealed that sustained exposure to KBrO3 can lead to fast scavenger exhaustion, in which case the dose-response shapes for both endpoints are not substantially affected. The results are important to consider when forming conclusions on a chemical's toxicity dose dependence based on the dose-response of early genotoxic events.

  3. Reactive oxygen species (ROS) and wound healing: the functional role of ROS and emerging ROS-modulating technologies for augmentation of the healing process.

    PubMed

    Dunnill, Christopher; Patton, Thomas; Brennan, James; Barrett, John; Dryden, Matthew; Cooke, Jonathan; Leaper, David; Georgopoulos, Nikolaos T

    2017-02-01

    Reactive oxygen species (ROS) play a pivotal role in the orchestration of the normal wound-healing response. They act as secondary messengers to many immunocytes and non-lymphoid cells, which are involved in the repair process, and appear to be important in coordinating the recruitment of lymphoid cells to the wound site and effective tissue repair. ROS also possess the ability to regulate the formation of blood vessels (angiogenesis) at the wound site and the optimal perfusion of blood into the wound-healing area. ROS act in the host's defence through phagocytes that induce an ROS burst onto the pathogens present in wounds, leading to their destruction, and during this period, excess ROS leakage into the surrounding environment has further bacteriostatic effects. In light of these important roles of ROS in wound healing and the continued quest for therapeutic strategies to treat wounds in general and chronic wounds, such as diabetic foot ulcers, venous and arterial leg ulcers and pressure ulcers in particular, the manipulation of ROS represents a promising avenue for improving wound-healing responses when they are stalled. This article presents a review of the evidence supporting the critical role of ROS in wound healing and infection control at the wound site, and some of the new emerging concepts associated with ROS modulation and its potential in improving wound healing are discussed.

  4. The observation research of the differences in cell death and reactive oxygen species in the process of infecting Arabidopsis with avirulent strains

    NASA Astrophysics Data System (ADS)

    Liu, HuaBin; Chen, WenLi

    2012-03-01

    Objective: To observe the differences of cell death and accumulation of reactive oxygen species (ROS) in the process of infecting Arabidopsis with avirulent Pseudomonas syringae pv. tomato DC3000 (avrB, avrRps4), it will be of great importance to research the role of plant disease resistance and defense response. Methods: Using WT, AtrbohD and AtrbohF mutant as experimental materials, we discuss the impact of cell death and ROS on the leaves of Arabidopsis infected with avirulent Pst DC3000 (avrB, avrRps4), observed by spectral analysis and visualized by DAB and trypan blue stain. Results: When infected with avirulent Pst DC3000, both WT and AtrbohF mutant line behaved resistance that exhibited burst of ROS and HR occur, limit senescence and pathogen induced chlorotic cell death. Paradoxically, AtrbohD mutant behaved susceptible characters that exhibited a small quantity of ROS accumulated and enhanced cell death. Conclusion: After infection of Arabidopsis with avirulent Pst DC3000, WT exhibited more ROS accumulation than AtrbohF, and AtrbohD eliminated the majority of total ROS production. Although both WT and AtrbohF mutant exhibited HR occur, enhanced cell death in AtrbohD mutant.

  5. Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis.

    PubMed

    Bao, K Q; Gao, J Q; Wang, Z B; Zhang, R Q; Zhang, Z Y; Sugiura, N

    2012-01-01

    Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions.

  6. 'Pre-prosthetic use of poly(lactic-co-glycolic acid) membranes treated with oxygen plasma and TiO2 nanocomposite particles for guided bone regeneration processes'.

    PubMed

    Castillo-Dalí, Gabriel; Castillo-Oyagüe, Raquel; Terriza, Antonia; Saffar, Jean-Louis; Batista-Cruzado, Antonio; Lynch, Christopher D; Sloan, Alastair J; Gutiérrez-Pérez, José-Luis; Torres-Lagares, Daniel

    2016-04-01

    Guided bone regeneration (GBR) processes are frequently necessary to achieve appropriate substrates before the restoration of edentulous areas. This study aimed to evaluate the bone regeneration reliability of a new poly-lactic-co-glycolic acid (PLGA) membrane after treatment with oxygen plasma (PO2) and titanium dioxide (TiO2) composite nanoparticles. Circumferential bone defects (diameter: 10mm; depth: 3mm) were created on the parietal bones of eight experimentation rabbits and were randomly covered with control membranes (Group 1: PLGA) or experimental membranes (Group 2: PLGA/PO2/TiO2). The animals were euthanized two months afterwards, and a morphologic study was then performed under microscope using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone formed in the grown defects, concentration of osteoclasts, and intensity of osteosynthetic activity were assessed. Comparisons among the groups and with the original bone tissue were made using the Kruskal-Wallis test. The level of significance was set in advance at a=0.05. The experimental group recorded higher values for new bone formation, mineralised bone length, and osteoclast concentration; this group also registered the highest osteosynthetic activity. Bone layers in advanced formation stages and low proportions of immature tissue were observed in the study group. The functionalised membranes showed the best efficacy for bone regeneration. The addition of TiO2 nanoparticles onto PLGA/PO2 membranes for GBR processes may be a promising technique to restore bone dimensions and anatomic contours as a prerequisite to well-supported and natural-appearing prosthetic rehabilitations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The effects of high temperature processing on the structural and optical properties of oxygenated CdS window layers in CdTe solar cells

    SciTech Connect

    Paudel, Naba R.; Grice, Corey R.; Xiao, Chuanxiao; Yan, Yanfa

    2014-07-28

    High efficiency CdTe solar cells typically use oxygenated CdS (CdS:O) window layers. We synthesize CdS:O window layers at room temperature (RT) and 270 °C using reactive sputtering. The band gaps of CdS:O layers deposited at RT increase when O{sub 2}/(O{sub 2} + Ar) ratios in the deposition chamber increase. On the other hand, the band gaps of CdS:O layers deposited at 270 °C decrease as the O{sub 2}/(O{sub 2} + Ar) ratios increase. Interestingly, however, our high temperature closed-space sublimation (CSS) processed CdTe solar cells using CdS:O window layers deposited at RT and 270 °C exhibit very similar cell performance, including similar short-circuit current densities. To understand the underlying reasons, CdS:O thin films deposited at RT and 270 °C are annealed at temperatures that simulate the CSS process of CdTe deposition. X-ray diffraction, atomic force microscopy, and UV-visible light absorption spectroscopy characterization of the annealed films reveals that the CdS:O films deposited at RT undergo grain regrowth and/or crystallization and exhibit reduced band gaps after the annealing. Our results suggest that CdS:O thin films deposited at RT and 270 °C should exhibit similar optical properties after the deposition of CdTe layers, explaining the similar cell performance.

  8. In-situ transmission electron microscopy study of oxygen vacancy ordering and dislocation annihilation in undoped and Sm-doped CeO2 ceramics during redox processes

    NASA Astrophysics Data System (ADS)

    Ding, Yong; Chen, Yu; Pradel, Ken C.; Liu, Meilin; Lin Wang, Zhong

    2016-12-01

    Ceria (CeO2) based ceramics have been widely used for many applications due to their unique ionic, electronic, and catalytic properties. Here, we report our findings in investigating into the redox processes of undoped and Sm-doped CeO2 ceramics stimulated by high-energy electron beam irradiation within a transmission electron microscope (TEM). The reduced structure with oxygen vacancy ordering has been identified as the CeO1.68 (C-Ce2O3+δ) phase via high-resolution TEM. The reduction of Ce4+ to Ce3+ has been monitored by electron energy-loss spectroscopy. The decreased electronic conductivity of the Sm-doped CeO2 (Sm0.2Ce0.8O1.9, SDC) is revealed by electron holography, as positive electrostatic charges accumulated at the surfaces of SDC grains under electron beam irradiation, but not at CeO2 grains. The formation of the reduced CeO1.68 domains corresponds to lattice expansion compared to the CeO2 matrix. Therefore, the growth of CeO1.68 nuclei builds up strain inside the matrix, causing annihilation of dislocations inside the grains. By using in-situ high-resolution TEM and a fast OneView camera recording system, we investigated dislocation motion inside both CeO2 and SDC grains under electron beam irradiation. The dislocations prefer to dissociate into Shockley partials bounded by stacking faults. Then, the partials can easily glide in the {111} planes to reach the grain surfaces. Even the Lomer-Cottrell lock can be swept away by the phase change induced strain field. Our results revealed the high mobility of dislocations inside CeO2 and SDC grains during their respective redox processes.

  9. Anomalous C-V response correlated to relaxation processes in TiO{sub 2} thin film based-metal-insulator-metal capacitor: Effect of titanium and oxygen defects

    SciTech Connect

    Kahouli, A.; Marichy, C.; Pinna, N.

    2015-04-21

    Capacitance-voltage (C–V) and capacitance-frequency (C–f) measurements are performed on atomic layer deposited TiO{sub 2} thin films with top and bottom Au and Pt electrodes, respectively, over a large temperature and frequency range. A sharp capacitance peak/discontinuity (C–V anomalous) is observed in the C–V characteristics at various temperatures and voltages. It is demonstrated that this phenomenon is directly associated with oxygen vacancies. The C–V peak irreversibility and dissymmetry at the reversal dc voltage are attributed to difference between the Schottky contacts at the metal/TiO{sub 2} interfaces. Dielectric analyses reveal two relaxation processes with degeneration of the activation energy. The low trap level of 0.60–0.65 eV is associated with the first ionized oxygen vacancy at low temperature, while the deep trap level of 1.05 eV is associated to the second ionized oxygen vacancy at high temperature. The DC conductivity of the films exhibits a transition temperature at 200 °C, suggesting a transition from a conduction regime governed by ionized oxygen vacancies to one governed by interstitial Ti{sup 3+} ions. Both the C–V anomalous and relaxation processes in TiO{sub 2} arise from oxygen vacancies, while the conduction mechanism at high temperature is governed by interstitial titanium ions.

  10. The natural history of oxygen.

    PubMed

    Dole, M

    1965-09-01

    The nuclear reactions occurring in the cores of stars which are believed to produce the element oxygen are first described. Evidence for the absence of free oxygen in the early atmosphere of the earth is reviewed. Mechanisms of creation of atmospheric oxygen by photochemical processes are then discussed in detail. Uncertainty regarding the rate of diffusion of water vapor through the cold trap at 70 km altitude in calculating the rate of the photochemical production of oxygen is avoided by using data for the concentration of hydrogen atoms at 90 km obtained from the Meinel OH absorption bands. It is estimated that the present atmospheric oxygen content could have been produced five to ten times during the earth's history. It is shown that the isotopic composition of atmospheric oxygen is not that of photosynthetic oxygen. The fractionation of oxygen isotopes by organic respiration and oxidation occurs in a direction to enhance the O(18) content of the atmosphere and compensates for the O(18) dilution resulting from photosynthetic oxygen. Thus, an oxygen isotope cycle exists in nature.

  11. The Natural History of Oxygen

    PubMed Central

    Dole, Malcolm

    1965-01-01

    The nuclear reactions occurring in the cores of stars which are believed to produce the element oxygen are first described. Evidence for the absence of free oxygen in the early atmosphere of the earth is reviewed. Mechanisms of creation of atmospheric oxygen by photochemical processes are then discussed in detail. Uncertainty regarding the rate of diffusion of water vapor through the cold trap at 70 km altitude in calculating the rate of the photochemical production of oxygen is avoided by using data for the concentration of hydrogen atoms at 90 km obtained from the Meinel OH absorption bands. It is estimated that the present atmospheric oxygen content could have been produced five to ten times during the earth's history. It is shown that the isotopic composition of atmospheric oxygen is not that of photosynthetic oxygen. The fractionation of oxygen isotopes by organic respiration and oxidation occurs in a direction to enhance the O18 content of the atmosphere and compensates for the O18 dilution resulting from photosynthetic oxygen. Thus, an oxygen isotope cycle exists in nature. PMID:5859927

  12. Reversible Oxygenation of Oxygen Transport Proteins.

    ERIC Educational Resources Information Center

    Drain, C. M.; Corden, Barry B.

    1987-01-01

    Describes a lecture demonstration which illustrates changes in the visible spectra of oxygen transport proteins upon reversible oxygen binding. Provides a comparison of the physical characteristics of oxygen storage and transport proteins. Reviews essentials for preparation of the materials. (ML)

  13. Novel nanostructured oxygen sensor

    NASA Astrophysics Data System (ADS)

    Boardman, Alan James

    New government regulations and industry requirements for medical oxygen sensors require the development of alternate materials and process optimization of primary sensor components. Current oxygen sensors are not compliant with the Restriction of Hazardous Substances (RoHS) Directive. This work focused on two areas. First, was finding suitable readily available materials for the sensor anodes. Second was optimizing the processing of the sensor cathode membrane for reduced delamination. Oxygen sensors were made using tin (Sn) and bismuth (Bi) electrodes, potassium hydroxide (KOH) and acetic acid (CH3COOH) electrolytes with platinum (Pt) and gold (Au) reference electrodes. Bi electrodes were fabricated by casting and pressing processes. Electrochemical characterization of the Sn and Bi electrodes was performed by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and sensing characterization per BSEN ISO 21647:2009 at various oxygen percentages, 0%, 20.9% and 100% oxygen levels with an automated test apparatus. The Sn anode with both electrolyte solutions showed good oxygen sensing properties and performance in a sensor. This system shows promise for replacement of Pb electrodes as required by the RoHS Directive. The Bi anode with Au cathode in both KOH and CH3COOH electrolytes showed acceptable performance and oxygen sensing properties. The Bi anodes fabricated by separate manufacturing methods demonstrated effectiveness for use in medical oxygen sensors. Gold thin films were prepared by magnetron sputtering on Flouroethylene Polymer (FEP) films. The FEP substrate temperature ranged from -77°C to 50°C. X-Ray Diffraction (XRD) and 4-point resistivity characterized the effects of substrate temperature to Au thin film particle size. XRD peak broadening and resistivity measurements showed a strong correlation of particle size to FEP substrate temperature. Particle size at 50°C was 594A and the -77°C particle size was 2.4 x 103A. Substrate

  14. AISI/DOE Advanced Process Control Program Vol. 1 of 6: Optical Sensors and Controls for Improved Basic Oxygen Furnace Operations

    SciTech Connect

    Sarah Allendorf; David Ottesen; Donald Hardesty

    2002-01-31

    The development of an optical sensor for basic oxygen furnace (BOF) off-gas composition and temperature in this Advanced Process Control project has been a laboratory spectroscopic method evolve into a pre-commercialization prototype sensor system. The sensor simultaneously detects an infrared tunable diode laser ITDL beam transmitted through the process off-gas directly above the furnace mouth, and the infrared greybody emission from the particulate-laden off-gas stream. Following developmental laboratory and field-testing, the sensor prototype was successfully tested in four long-term field trials at Bethlehem Steel's Sparrows Point plant in Baltimore, MD> The resulting optical data were analyzed and reveal correlations with four important process variables: (1) bath turndown temperature; (2) carbon monoxide post-combustion control; (2) bath carbon concentration; and (4) furnace slopping behavior. The optical sensor measurement of the off-gas temperature is modestly correlated with bath turndown temperature. A detailed regression analysis of over 200 heats suggests that a dynamic control level of +25 Degree F can be attained with a stand-alone laser-based optical sensor. The ability to track off-gas temperatures to control post-combustion lance practice is also demonstrated, and may be of great use in optimizing post-combustion efficiency in electric furnace steelmaking operations. In addition to the laser-based absorption spectroscopy data collected by this sensor, a concurrent signal generated by greybody emission from the particle-laden off-gas was collected and analyzed. A detailed regression analysis shows an excellent correlation of a single variable with final bath turndown carbon concentration. Extended field trials in 1998 and early 1999 show a response range from below 0.03% to a least 0.15% carbon concentration with a precision of +0.0007%. Finally, a strong correlation between prolonged drops in the off-gas emission signal and furnace slopping events

  15. Induction of single strand breaks, and base lesions in plasmid DNA films induced by carbon, nitrogen, and oxygen KLL Auger process.

    PubMed

    Fujii, Kentaro; Yokoya, Akinari; Shikazono, Naoya

    2008-12-01

    To reveal the reaction process in DNA by Auger electrons using the observed single strand breaks (SSB) and base lesions induced by monochromatic ultrasoft X-rays in dry plasmid DNA film. Desorbed ions from DNA and 2-deoxy-D-ribose thin films were also measured to ascertain the decomposition site in DNA. Dry plasmid DNA (pUC18) films were irradiated with synchrotron monochromatic ultrasoft X-rays (USX). Two photon energies, 270, and 560 eV, were chosen for the irradiation experiments. Irradiated plasmid DNA was analyzed by agarose gel electrophoresis. The yield of base lesions was determined by the post-irradiation-treatment of the DNA with enzymatic probes (formamidpyrimidine DNA glycosylase [Fpg] and endonuclease III [Nth]). Desorbed ions induced by 540 eV USX irradiation from calf thymus DNA and 2-deoxy-D-ribose thin films were detected by quadrupole-mass spectrometer. Yield of strand breaks and base lesions were obtained by 270 and 560 eV photon energies, respectively. Each yield showed characteristic of the photon energy spectrum. The characteristics of the desorbed ion mass spectra from 2-deoxy-D-ribose and DNA films were strikingly similar with each other. In this paper we report, for the first time, the yields of base lesions and SSB induced by monochromatic USX. The yield of SSB induced by core-ionization of carbon, nitrogen, and oxygen was two times more frequent than that of valence-electrons. From the comparison of desorbed ion mass spectra of 2-deoxy-D-ribose with DNA films we predict these breaks are likely to be induced by the decomposition of the sugar sites in DNA backbone.

  16. Reliability of new poly (lactic-co-glycolic acid) membranes treated with oxygen plasma plus silicon dioxide layers for pre-prosthetic guided bone regeneration processes.

    PubMed

    Castillo-Dalí, G; Castillo-Oyagüe, R; Batista-Cruzado, A; López-Santos, C; Rodríguez-González-Elipe, A; Saffar, J-L; Lynch, C-D; Gutiérrez-Pérez, J-L; Torres-Lagares, D

    2017-03-01

    The use of cold plasmas may improve the surface roughness of poly(lactic-co-glycolic) acid (PLGA) membranes, which may stimulate the adhesion of osteogenic mediators and cells, thus accelerating the biodegradation of the barriers. Moreover, the incorporation of metallic-oxide particles to the surface of these membranes may enhance their osteoinductive capacity. Therefore, the aim of this paper was to evaluate the reliability of a new PLGA membrane after being treated with oxygen plasma (PO2) plus silicon dioxide (SiO2) layers for guided bone regeneration (GBR) processes. Circumferential bone defects (diameter: 11 mm; depth: 3 mm) were created on the top of eight experimentation rabbits' skulls and were randomly covered with: (1) PLGA membranes (control), or (2) PLGA/PO2/SiO2 barriers. The animals were euthanized two months afterwards. A micromorphologic study was then performed using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone, concentration of osteoclasts, and intensity of ostheosynthetic activity were assessed and compared with those of the original bone tissue. The Kruskal-Wallis test was applied for between-group com Asignificance level of a=0.05 was considered. The PLGA/PO2/SiO2 membranes achieved the significantly highest new bone formation, length of mineralised bone, concentration of osteoclasts, and ostheosynthetic activity. The percentage of regenerated bone supplied by the new membranes was similar to that of the original bone tissue. Unlike what happened in the control group, PLGA/PO2/SiO2 membranes predominantly showed bone layers in advanced stages of formation. The addition of SiO2 layers to PLGA membranes pre-treated with PO2 improves their bone-regeneration potential. Although further research is necessary to corroborate these conclusions in humans, this could be a promising strategy to rebuild the bone architecture prior to rehabilitate edentulous areas.

  17. Selective photooxidation of hydrocarbons in zeolites by oxygen

    DOEpatents

    Frei, Heinz; Blatter, Fritz; Sun, Hai

    1998-01-01

    A selective photooxidation process for the conversion of hydrocarbon molecules to partially oxygenated derivatives, which comprises the steps of adsorbing a hydrocarbon and oxygen onto a dehydrated zeolite support matrix to form a hydrocarbon-oxygen contact pair, and subsequently exposing the hydrocarbon-oxygen contact pair to visible light, thereby forming a partially oxygenated derivative.

  18. Oxygenated fraction and mass of organic aerosol from direct emission and atmospheric processing measured on the R/V Ronald Brown during TEXAQS/GoMACCS 2006

    NASA Astrophysics Data System (ADS)

    Russell, L. M.; Takahama, S.; Liu, S.; Hawkins, L. N.; Covert, D. S.; Quinn, P. K.; Bates, T. S.

    2009-04-01

    masses. Organosulfate groups were found in GAM and SAM, accounting for 1% and 3% of OM, respectively. Two thirds of the OM and oxygen-to-carbon (O/C) measured could be attributed to oil and wood combustion sources on the basis of mild or strong correlations to coemitted, nonvolatile trace metals, with the remaining one third being associated with atmospherically processed organic aerosol. The cloud condensation nuclei (CCN) fraction (normalized by total condensation nuclei) had weak correlations to the alcohol and amine group fractions and mild correlation with O/C, also varying inversely with alkane group fraction. The chemical components that influenced f(RH) were sulfate, organic, and nitrate fraction, but this contrast is consistent with the size-distribution dependence of CCN counters and nephelometers.

  19. Oxygen Extraction from Minerals

    NASA Technical Reports Server (NTRS)

    Muscatello, Tony

    2017-01-01

    Oxygen, whether used as part of rocket bipropellant or for astronaut life support, is a key consumable for space exploration and commercialization. In Situ Resource Utilization (ISRU) has been proposed many times as a method for making space exploration more cost effective and sustainable. On planetary and asteroid surfaces the presence of minerals in the regolith that contain oxygen is very common, making them a potential oxygen resource. The majority of research and development for oxygen extraction from minerals has been for lunar regolith although this work would generally be applicable to regolith at other locations in space. This presentation will briefly survey the major methods investigated for oxygen extraction from regolith with a focus on the current status of those methods and possible future development pathways. The major oxygen production methods are (1) extraction from lunar ilmenite (FeTiO3) with either hydrogen or carbon monoxide, (2) carbothermal reduction of iron oxides and silicates with methane, and (3) molten regolith electrolysis (MRE) of silicates. Methods (1) and (2) have also been investigated in a two-step process using CO reduction and carbon deposition followed by carbothermal reduction. All three processes have byproducts that could also be used as resources. Hydrogen or carbon monoxide reduction produce iron metal in small amounts that could potentially be used as construction material. Carbothermal reduction also makes iron metal along with silicon metal and a glass with possible applications. MRE produces iron, silicon, aluminum, titanium, and glass, with higher silicon yields than carbothermal reduction. On Mars and possibly on some moons and asteroids, water is present in the form of mineral hydrates, hydroxyl (-OH) groups on minerals, andor water adsorbed on mineral surfaces. Heating of the minerals can liberate the water which can be electrolyzed to provide a source of oxygen as well. The chemistry of these processes, some key

  20. Mechanisms of Oxidation with Oxygen

    PubMed Central

    Taube, Henry

    1965-01-01

    Several topics are dealt with in discussing the reactions of molecular oxygen, but a common goal is pursued in each: to try to understand the reactions in terms of the fundamental properties of the oxygen molecule, and of the other reactants. The paper first describes the electronic structure of oxygen and of two low-lying electronically excited states. Concern with the low-lying electronically excited states is no longer the sole property of spectroscopists; recently, evidence has been presented for the participation of such activated molecules in chemical reactions. The chemistry of oxygen is dominated by the fact that the molecule in the ground state has two unpaired electrons, whereas the products of oxidation in many important reactions have zero spin. In its reactions with transition metal ions the restrictions imposed by the spin state of the oxygen molecule are easily circumvented. A number of reactions of oxygen with metal ions have been studied in considerable detail; conclusions on basic aspects of the reaction mechanism are outlined. Among the most interesting reactions of oxygen are those in which it is reversibly absorbed by reducing agents. Reversible absorption to form a peroxide in the bound state is possible; some of the conditions which must be fulfilled by a reducing system to qualify as storing oxygen in this way are reasonably well understood and are here enunciated. Little has been done on the formation of oxygen from water; some factors involved in this process are discussed. PMID:5859925

  1. A comparative study of the processes of generation of singlet oxygen upon irradiation of aqueous preparations on the basis of chlorin e6 and coproporphyrin III

    NASA Astrophysics Data System (ADS)

    Bagrov, I. V.; Belousova, I. M.; Gorelov, S. I.; Dobrun, M. V.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, A. V.; Kris'ko, T. K.

    2017-02-01

    The photosensitizing ability of an agent based on chlorin e6 (Photoditazin), which is used for photodynamic diagnosis and therapy, is compared with that of a new preparation on the basis of coproporphyrin III in the environment of a phosphate buffer and a simulated biological environment (albumin solution). The efficiency of singlet-oxygen production was estimated by EPR spectroscopy and spectroscopy in the UV and visible ranges with the use of "chemical traps" of singlet oxygen. By irradiating drugs with LED emission centered at λmax = 520 nm, we determined the quantum yield of singlet-oxygen production in a buffer solution; the obtained values are 0.60 and 0.37 for chlorine and coproporphyrin, respectively. The steady-state concentration of singlet oxygen upon irradiation of solutions of the studied photosensitizers with concentrations of 12-43 μM and the density of radiation power within the 6-96 W/cm2 region was found to be in the region of 1010-1011 molecules/cm3. It is shown that the introduction into the solution of egg albumin (0.1%) reduces the sensitizing properties of the two drugs by two to three times, while the efficiencies of the preparations with respect to singlet-oxygen production become almost identical (0.19 and 0.17).

  2. Gold-catalyzed hydrative carbocyclization of 1,5- and 1,6-diyn-3-ones via an oxygen transfer process.

    PubMed

    Tang, Jhih-Meng; Liu, Ting-An; Liu, Rai-Shung

    2008-11-07

    This study reports new hydrative carbocyclizations of 1,5- and 1,6-diyn-3-ones catalyzed by PPh3AuOTf, involving a pi-alkyne-assisted oxygen transfer in the reaction mechanisms. Treatment of 2-(alk-2-yn-1-onyl)-1-alkynylbenzenes with PPh3AuOTf (5 mol %) in wet 1,4-dioxane (23 degrees C, 10 min) led to hydrative aromatization to give 4-hydroxyl-1-naphthyl ketones efficiently. This approach is also extendible to the hydrative cyclization of acyclic 1,5-diyn-3-ones, which afforded 4-cyclopentenonyl ketones in reasonable yields. On the basis of this oxygen-labeling study, we propose a plausible mechanism involving an alkyne-assisted oxygen transfer to generate key oxonium and gold-enolate intermediates.

  3. Integrated oxygen recovery system

    NASA Technical Reports Server (NTRS)

    Lee, M. Gene; Davenport, Ronald J.

    1993-01-01

    Life Systems has conceptualized an innovative Integrated Oxygen Recovery System (IORS) applicable to advanced mission air revitalization. The IORS provides the capability to electrochemically generate metabolic oxygen (O2) and recover O2 from the space habitat atmosphere via a carbon dioxide (CO2) reduction process within a single assembly. To achieve this capability, the IORS utilizes a Solid Metal Cathode (SMC) water electrolysis unit that simultaneously serves as the Sabatier CO2 reduction reactor. The IORS enables two major life support systems currently baselined in closed loop air revitalization systems to be combined into one smaller, less complex system. This concept reduces fluidic and electrical interface requirements and eliminates a hydrogen (H2) interface. Life Systems is performing an evaluation of the IORS process directed at demonstrating performance and quantifying key physical characteristics including power, weight, and volume. The results of the checkout, shakedown, and initial parametric tests are summarized.

  4. Integrated oxygen recovery system

    NASA Technical Reports Server (NTRS)

    Lee, M. Gene; Davenport, Ronald J.

    1993-01-01

    Life Systems has conceptualized an innovative Integrated Oxygen Recovery System (IORS) applicable to advanced mission air revitalization. The IORS provides the capability to electrochemically generate metabolic oxygen (O2) and recover O2 from the space habitat atmosphere via a carbon dioxide (CO2) reduction process within a single assembly. To achieve this capability, the IORS utilizes a Solid Metal Cathode (SMC) water electrolysis unit that simultaneously serves as the Sabatier CO2 reduction reactor. The IORS enables two major life support systems currently baselined in closed loop air revitalization systems to be combined into one smaller, less complex system. This concept reduces fluidic and electrical interface requirements and eliminates a hydrogen (H2) interface. Life Systems is performing an evaluation of the IORS process directed at demonstrating performance and quantifying key physical characteristics including power, weight, and volume. Technical progress achieved during the first two months of the program is summarized.

  5. Atomic Oxygen Task

    NASA Technical Reports Server (NTRS)

    Hadaway, James B.

    1997-01-01

    This report details work performed by the Center for Applied Optics (CAO) at the University of Alabama in Huntsville (UAH) on the contract entitled 'Atomic Oxygen Task' for NASA's Marshall Space Flight Center (contract NAS8-38609, Delivery Order 109, modification number 1). Atomic oxygen effects on exposed materials remain a critical concern in designing spacecraft to withstand exposure in the Low Earth Orbit (LEO) environment. The basic objective of atomic oxygen research in NASA's Materials & Processes (M&P) Laboratory is to provide the solutions to material problems facing present and future space missions. The objective of this work was to provide the necessary research for the design of specialized experimental test configurations and development of techniques for evaluating in-situ space environmental effects, including the effects of atomic oxygen and electromagnetic radiation on candidate materials. Specific tasks were performed to address materials issues concerning accelerated environmental testing as well as specifically addressing materials issues of particular concern for LDEF analysis and Space Station materials selection.

  6. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  7. Oxygen detection using evanescent fields

    DOEpatents

    Duan, Yixiang; Cao, Weenqing

    2007-08-28

    An apparatus and method for the detection of oxygen using optical fiber based evanescent light absorption. Methylene blue was immobilized using a sol-gel process on a portion of the exterior surface of an optical fiber for which the cladding has been removed, thereby forming an optical oxygen sensor. When light is directed through the optical fiber, transmitted light intensity varies as a result of changes in the absorption of evanescent light by the methylene blue in response to the oxygen concentration to which the sensor is exposed. The sensor was found to have a linear response to oxygen concentration on a semi-logarithmic scale within the oxygen concentration range between 0.6% and 20.9%, a response time and a recovery time of about 3 s, ant to exhibit good reversibility and repeatability. An increase in temperature from 21.degree. C. to 35.degree. C. does not affect the net absorption of the sensor.

  8. Scale-up of naringinase production process based on the constant oxygen transfer rate for a novel strain of Bacillus methylotrophicus.

    PubMed

    Raval, Keyur; Gehlot, Kartik; B D, Prasanna

    2017-02-07

    Naringinase bioprocess based on Bacillus methylotrophicus was successfully scaled up based on constant oxygen transfer rate (OTR) as the scale-up criterion from 5-L bioreactor to 20-L bioreactor. OTR was measured in 5 and 20-L bioreactor under various operating conditions using dynamic method. The operating conditions, where complete dispersion was observed were identified. The highest OTR of 0.035 and 0.04 mMol/L/s was observed in 5 and 20-L bioreactor, respectively. Critical dissolved oxygen concentration of novel isolated strain B. methylotrophicus was found to be 20% of oxygen saturation in optimized medium. The B. methylotrophicus cells grown on sucrose had maximum oxygen uptake rate of 0.14 mMol/L/s in optimized growth medium. The cells produced the maximum naringinase activity of 751 and 778 U/L at 34 hr in 5 and 20-L bioreactors, respectively. The maximum specific growth rate of about 0.178/hr was observed at both the scales of operations. The maximum naringinase yield of 160 and 164 U/g biomass was observed in 5 and 20-L bioreactors, respectively. The growth and production profiles at both scales were similar indicating successful scale-up strategy for B. methylotrophicus culture.

  9. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    NASA Technical Reports Server (NTRS)

    Mansell, J. Matthew; Abney, Morgan B.

    2012-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these oxygenated compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing.

  10. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    NASA Technical Reports Server (NTRS)

    Mansell, J. Matthew; Abney, Morgan B.; Miller, Lee A.

    2011-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these "oxygenated" compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing

  11. Oxygen measurements to improve singlet oxygen dosimetry

    NASA Astrophysics Data System (ADS)

    Kim, Michele M.; Penjweini, Rozhin; Ong, Yi Hong; Finlay, Jarod C.; Zhu, Timothy C.

    2017-02-01

    Photodynamic therapy (PDT) involves interactions between the three main components of light fluence, photosensitizer concentration, and oxygenation. Currently, singlet oxygen explicit dosimetry (SOED) has focused on the first two of these components. The macroscopic model to calculate reacted singlet oxygen has previously involved a fixed initial ground state oxygen concentration. A phosphorescence-based oxygen probe was used to measure ground state oxygen concentration throughout treatments for mice bearing radioactively induced fibroscarcoma tumors. Photofrin-, BPD-, and HPPH-mediated PDT was performed on mice. Model-calculated oxygen and measured oxygen was compared to evaluate the macroscopic model as well as the photochemical parameters involved. Oxygen measurements at various depths were compared to calculated values. Furthermore, we explored the use of noninvasive diffuse correlation spectroscopy (DCS) to measure tumor blood flow changes in response to PDT to improve the model calculation of reacted singlet oxygen. Mice were monitored after treatment to see the effect of oxygenation on long-term recurrence-free survival as well as the efficacy of using reacted singlet oxygen as a predictive measure of outcome. Measurement of oxygenation during treatment helps to improve SOED as well as confirm the photochemical parameters involved in the macroscopic model. Use of DCS in predicting oxygenation changes was also investigated.

  12. Oxygen Systems Cleaners for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Davis, Samuel E.; Lowery, Freida

    1997-01-01

    New environmental regulations have forced extensive evaluations of many different cleaning agents for use in oxygen systems. This is no simple process because pure oxygen is a very strong oxidizer, and when placed in contact with a foreign substance, the combination may be explosive. This foreign substance can easily be a cleaning agent residue left over in the oxygen system after cleaning. This paper focuses on the factors that must be considered when selecting a cleaning agent for oxygen systems, as well as the approval processes which are currently being utilized by NASA for oxygen compatibility of materials. This paper will provide a working description of how to begin selecting a cleaning agent for oxygen systems. The paper will present the following: Background information on the necessity of a stringent selection process for oxygen system cleaners; Specifications and regulations concerning cleaning for oxygen service; Changing oxygen cleaning specifications given current environmental concerns; Testing for cleanliness in oxygen systems, Cleaning agents that have been tested for oxygen systems, including an extensive list of some of the newer 'environmentally friendly' cleaning agents; and Test results and conclusions from the testing. The paper will also provide instructions on the proper procedures for obtaining NASA approval on a candidate oxygen systems cleaning agent.

  13. Oxygen saturation and cognitive performance.

    PubMed

    Andersson, Jan; Berggren, Peter; Grönkvist, Mikael; Magnusson, Staffan; Svensson, Erland

    2002-07-01

    The purpose of the experiments was to investigate how inhalation of 100% oxygen affected cognitive performance. A test battery was developed that was designed to capture different aspects of cognitive processes, i.e., perception, attention, working memory, long-term memory and prospective memory. All tests were verbally based, thus reducing cognitive spatial processes to a minimum. In experiment 1, 48 participants volunteered in a complete factorial within-participant design. Two different conditions for type of gas were used, inhalation of 100% oxygen and inhalation of breathing air (approximately 21% oxygen balanced with nitrogen). The inhalation was performed during the 1 min prior to starting each separate test. The instructions for each test were given during the inhalation period. All participants inhaled oxygen or breathing air through a Swedish military pilot mask. Physiological (heartbeats per minute and blood oxygen saturation level) reactions were recorded continuously throughout the session. Participants also completed a mood-state questionnaire before and after the test battery. The results revealed that cognitive performance were not affected by inhalation. Hence, this experiment does not replicate previous findings that suggest that inhalation of 100% oxygen could increase cognitive performance. Another experiment was performed to control for methodological issues. Experiment 2 revealed exactly the same pattern, i.e., inhalation of oxygen did not affect cognitive functioning.

  14. Solid-state source of atomic oxygen for low-temperature oxidation processes: Application to pulsed laser deposition of TiO{sub 2}:N films

    SciTech Connect

    Ojima, Daiki; Chiba, Tetsuya; Shima, Kazunari; Hiramatsu, Hidenori; Hosono, Hideo; Hayashi, Katsuro

    2012-02-15

    An atomic oxygen (AO) source has been redesigned to coordinate with a pulsed laser deposition system and used to grow nitrogen-doped TiO{sub 2} films by deposition of TiN and simultaneous irradiation of the substrate with AO. The AO source uses an incandescently heated thin tube of zirconia as an oxygen permeation media to generate pure AO of low kinetic energy. The emission flux is calibrated using a silver-coated quartz crystal microbalance. The thin shape of the probe and transverse emission geometry of this emission device allow the emission area to be positioned close to the substrate surface, enhancing the irradiation flux at the substrate. AO irradiation is crucial for formation of TiO{sub 2} phases via oxidation of the deposited TiN laser plume, and is effective for decrease of the substrate temperature for crystallization of anatase phase to as low as around 200 deg. C.

  15. Treatment of real coal gasification wastewater using a novel integrated system of anoxic hybrid two stage aerobic processes: performance and the role of pure oxygen microbubble.

    PubMed

    Zhuang, Haifeng; Han, Hongjun; Shan, Shengdao

    2016-06-01

    A novel integrated system of anoxic-pure oxygen microbubble-activated sludge reactor-moving bed biofilm reactor was employed in treatment of real coal gasification wastewater. The results showed the integrated system had efficient performance of pollutants removal in short hydraulic retention time. While pure oxygen microbubble with the flow rate of 1.5 L/h and NaHCO3 dosage ratio of 2:1 (amount NaHCO3 to NH4 (+)-N ratio, mol: mol) were used, the removal efficiencies of COD, total phenols (TPh) and NH4 (+)-N reached 90, 95, and 95 %, respectively, with the influent loading rates of 3.4 kg COD/(m(3) d), 0.81 kg TPh/(m(3) d), and 0.28 kg NH4 (+)-N/(m(3) d). With the recycle ratio of 300 %, the concentrations of NO2 (-)-N and NO3 (-)-N in effluent decreased to 12 and 59 mg/L, respectively. Meanwhile, pure oxygen microbubble significantly improved the enzymatic activities and affected the effluent organic compositions and reduced the foam expansion. Thus, the novel integrated system with efficient, stable, and economical advantages was suitable for engineering application.

  16. Assessing the biomineralization processes in the shell microstructure of modern brachiopods: variations in the oxygen isotope composition and minor element ratios

    NASA Astrophysics Data System (ADS)

    Milner Garcia, Sara Ana; Rollion-Bard, Claire; Burckel, Pierre; Tomašových, Adam; Angiolini, Lucia; Henkel, Daniela

    2017-04-01

    Brachiopods have been extensively used to reconstruct physicochemical conditions of ancient oceans due to their extensive fossil record and shells made of stable low-Mg calcite. In this context, it is important to assess the impact of brachiopod shell biomineralization processes on geochemical proxies. Six modern species of brachiopod specimen representing the three low-Mg calcite orders (i.e. Terebratulida, Rhynchonellida and Thecideida) were selected, in order to identify the most reliable taxa and the best shell portions to use for measurements of proxies. Three main different shell structures were identified: (1) only primary layer, (2) primary and secondary fibrous layers and (3) same as (2) with also a tertiary columnar layer. Oxygen isotope composition was measured at the micrometre scale with high-resolution ion microprobe. Generally, O isotope values of shells composed of primary and secondary layers show a progression towards more positive values from the outer primary layer to the inner secondary layer. The columnar tertiary shell layer, when present, has the most positive isotopic O values, the closest to the isotopic equilibrium. Variations at the micrometre scale are higher than those measured by conventional bulk techniques, as already shown by Cusack et al. (2012). Trace elements ratios (Li/Ca, B/Ca, Na/Ca, Mg/Ca, and Sr/Ca) were determined by laser ablation coupled to an ICP-MS. The trace element points define profiles parallel to the O isotope ion probe spots. The elemental ratio profiles of species composed by primary and secondary shell layers (Terebratalia transversa, Magasella sanguinea and Magellania venosa) show different behaviours depending on the elements. Mg/Ca and Sr/Ca values are constant throughout all profiles, even Mg/Ca values are more variable. The values of both ratios are in good agreement with previous studies (Perez-Huerta et al., 2008; Butler et al., 2015). Li/Ca values are also constant among the different profiles. In

  17. Sterilization by oxygen plasma

    NASA Astrophysics Data System (ADS)

    Moreira, Adir José; Mansano, Ronaldo Domingues; Andreoli Pinto, Terezinha de Jesus; Ruas, Ronaldo; Zambon, Luis da Silva; da Silva, Mônica Valero; Verdonck, Patrick Bernard

    2004-07-01

    The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site and it also affects the bulk properties of the polymers. The use of a gas plasma is an elegant alternative sterilization technique. The plasma promotes an efficient inactivation of the micro-organisms, minimises the damage to the materials and presents very little danger for personnel and the environment. Pure oxygen reactive ion etching type of plasmas were applied to inactivate a biologic indicator, the Bacillus stearothermophilus, to confirm the efficiency of this process. The sterilization processes took a short time, in a few minutes the mortality was complete. In situ analysis of the micro-organisms' inactivating time was possible using emission spectrophotometry. The increase in the intensity of the 777.5 nm oxygen line shows the end of the oxidation of the biologic materials. The results were also observed and corroborated by scanning electron microscopy.

  18. Changes of the surface structure of corn stalk in the cooking process with active oxygen and MgO-based solid alkali as a pretreatment of its biomass conversion.

    PubMed

    Pang, Chunsheng; Xie, Tujun; Lin, Lu; Zhuang, Junping; Liu, Ying; Shi, Jianbin; Yang, Qiulin

    2012-01-01

    This study presents a novel, efficient and environmentally friendly process for the cooking of corn stalk that uses active oxygen (O2 and H2O2) and a recoverable solid alkali (MgO). The structural changes on the surface of corn stalk before and after cooking were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The results showed that lignin and extractives were effectively removed, especially those on the surface of corn stalk. Additionally, the changes included becoming fibrillar, the exposure of cellulose and hemi-cellulose and the pitting corrosion on the surface, etc. The results also showed that the removal reaction is from outside to inside, but the main reaction is possibly on the surface. Furthermore, the results of active oxygen cooking with a solid alkali are compared with those of alkaline cooking in the paper.

  19. Coal liquefaction process streams characterization and evaluation: The use of selective chemical reactions and carbon NMR spectroscopy in the speciation and quantification of oxygen functional groups in coal resids

    SciTech Connect

    Stock, L.M.; Cheng, C. . Dept. of Chemistry)

    1992-11-01

    This study demonstrated the feasibility of using phase-transfer methylation reactions for the derivatization of hydroxyl functionalities and single-electron transfer reactions to cleave ether groups in distillation resid materials derived from direct coal liquefaction. [sup 13]C-NMR was used to analyze the reaction products. It was demonstrated that the techniques can be used to speciate and quantify about half of the oxygen in resids. The remaining half of the oxygen is presumed to be present as unreactive ethers, probably dibenzofurans. Hydroxyl concentrations were determined on five resid samples and ether cleavage reactions were conducted on three of those five. Further development of this general analytical strategy as a process development tool is justified based on these results.

  20. Coal liquefaction process streams characterization and evaluation: The use of selective chemical reactions and carbon NMR spectroscopy in the speciation and quantification of oxygen functional groups in coal resids

    SciTech Connect

    Stock, L.M.; Cheng, C.

    1992-11-01

    This study demonstrated the feasibility of using phase-transfer methylation reactions for the derivatization of hydroxyl functionalities and single-electron transfer reactions to cleave ether groups in distillation resid materials derived from direct coal liquefaction. {sup 13}C-NMR was used to analyze the reaction products. It was demonstrated that the techniques can be used to speciate and quantify about half of the oxygen in resids. The remaining half of the oxygen is presumed to be present as unreactive ethers, probably dibenzofurans. Hydroxyl concentrations were determined on five resid samples and ether cleavage reactions were conducted on three of those five. Further development of this general analytical strategy as a process development tool is justified based on these results.

  1. Adiabatic Compression of Oxygen: Real Fluid Temperatures

    NASA Technical Reports Server (NTRS)

    Barragan, Michelle; Wilson, D. Bruce; Stoltzfus, Joel M.

    2000-01-01

    The adiabatic compression of oxygen has been identified as an ignition source for systems operating in enriched oxygen atmospheres. Current practice is to evaluate the temperature rise on compression by treating oxygen as an ideal gas with constant heat capacity. This paper establishes the appropriate thermodynamic analysis for the common occurrence of adiabatic compression of oxygen and in the process defines a satisfactory equation of state (EOS) for oxygen. It uses that EOS to model adiabatic compression as isentropic compression and calculates final temperatures for this system using current approaches for comparison.

  2. Oxygen Isotopes in Meteorites

    NASA Astrophysics Data System (ADS)

    Clayton, R. N.

    2003-12-01

    Oxygen isotope abundance variations in meteorites are very useful in elucidating chemical and physical processes that occurred during the formation of the solar system (Clayton, 1993). On Earth, the mean abundances of the three stable isotopes are 16O: 99.76%, 17O: 0.039%, and 18O: 0.202%. It is conventional to express variations in abundances of the isotopes in terms of isotopic ratios, relative to an arbitrary standard, called SMOW (for standard mean ocean water), as follows:The isotopic composition of any sample can then be represented by one point on a "three-isotope plot," a graph of δ17O versus δ18O. It will be seen that such plots are invaluable in interpreting meteoritic data. Figure 1 shows schematically the effect of various processes on an initial composition at the center of the diagram. Almost all terrestrial materials lie along a "fractionation" trend; most meteoritic materials lie near a line of "16O addition" (or subtraction). (4K)Figure 1. Schematic representation of various isotopic processes shown on an oxygen three-isotope plot. Almost all terrestrial materials plot along a line of "fractionation"; most primitive meteoritic materials plot near a line of "16O addition." The three isotopes of oxygen are produced by nucleosynthesis in stars, but by different nuclear processes in different stellar environments. The principal isotope, 16O, is a primary isotope (capable of being produced from hydrogen and helium alone), formed in massive stars (>10 solar masses), and ejected by supernova explosions. The two rare isotopes are secondary nuclei (produced in stars from nuclei formed in an earlier generation of stars), with 17O coming primarily from low- and intermediate-mass stars (<8 solar masses), and 18O coming primarily from high-mass stars (Prantzos et al., 1996). These differences in type of stellar source result in large observable variations in stellar isotopic abundances as functions of age, size, metallicity, and galactic location ( Prantzos

  3. Artificial oxygen transport protein

    DOEpatents

    Dutton, P. Leslie

    2014-09-30

    This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

  4. Energy management study for lunar oxygen production

    NASA Technical Reports Server (NTRS)

    Fazzolare, R. A.; Wong-Swanson, B. G.

    1989-01-01

    Energy management opportunities in the process of hydrogen reduction of ilmenite for lunar oxygen production are being investigated. An optimal energy system to supply the power requirements for the process will be determined.

  5. Oxygen sensing and signaling.

    PubMed

    van Dongen, Joost T; Licausi, Francesco

    2015-01-01

    Oxygen is an indispensable substrate for many biochemical reactions in plants, including energy metabolism (respiration). Despite its importance, plants lack an active transport mechanism to distribute oxygen to all cells. Therefore, steep oxygen gradients occur within most plant tissues, which can be exacerbated by environmental perturbations that further reduce oxygen availability. Plants possess various responses to cope with spatial and temporal variations in oxygen availability, many of which involve metabolic adaptations to deal with energy crises induced by low oxygen. Responses are induced gradually when oxygen concentrations decrease and are rapidly reversed upon reoxygenation. A direct effect of the oxygen level can be observed in the stability, and thus activity, of various transcription factors that control the expression of hypoxia-induced genes. Additional signaling pathways are activated by the impact of oxygen deficiency on mitochondrial and chloroplast functioning. Here, we describe the molecular components of the oxygen-sensing pathway.

  6. Preparation of perovskite-type oxides of cobalt by the malic acid aided process and their electrocatalytic surface properties in relation to oxygen evolution

    SciTech Connect

    Tiwari, S.K.; Chartier, P.; Singh, R.N. . Electrochemical Lab.)

    1995-01-01

    The electrocatalytic properties of perovskite-type cobalt oxides (La[sub 1[minus]x]Sr[sub x]CoO[sub 3], where x = 0, 0.2, 0.4), in the form of thin films on conductive supports, were studied by cyclic voltammetry and Tafel polarization techniques. The films had conductive and satisfactory adherent properties. The oxides were synthesized by a low temperature malic acid aided method. The cyclic voltammetry showed a pair of redox peaks prior to the onset of oxygen evolution on the oxide film with nickel support, while similar peaks were absent in the same oxide film on Pt and Ti. The anodic polarization studies indicated two Tafel slopes: 57 to 64 mV/decade at low and 100 to 130 mV/decade at high overpotentials, and first-order kinetics with respect to OH[sup [minus

  7. Oxygen Sensing and Homeostasis

    PubMed Central

    Semenza, Gregg L.

    2015-01-01

    The discovery of carotid bodies as sensory receptors for detecting arterial blood oxygen levels, and the identification and elucidation of the roles of hypoxia-inducible factors (HIFs) in oxygen homeostasis have propelled the field of oxygen biology. This review highlights the gas-messenger signaling mechanisms associated with oxygen sensing, as well as transcriptional and non-transcriptional mechanisms underlying the maintenance of oxygen homeostasis by HIFs and their relevance to physiology and pathology. PMID:26328879

  8. [Use of hyperbaric oxygenation for wound management].

    PubMed

    Berner, Juan Enrique; Vidal, Pedro; Will, Patrick; Castillo, Pablo

    2014-12-01

    Hyperbaric oxygenation consists in exposing patients to increased gas pressures while inhaling pure oxygen. It involves the use of hyperbaric chambers that can double or triple gas pressure inside them. Hyperbaric oxygenation may be useful in different clinical situations, but mostly for the treatment of decompression syndrome. In the last decades, it has been used for the management of different kinds of wounds. Hyperbaric oxygenation not only increases the delivery of oxygen to damaged tissues, but also stimulates angiogenesis, collagen synthesis, stem cell migration and local immune response. Clinical trials that have addressed the use of hyperbaric oxygenation are difficult to compare due to their heterogeneity in terms of experimental design, kind of injuries involved and assessment of outcome. Even though, most studies support the concept that hyperbaric oxygenation accelerates the healing process.

  9. [How did the earth's oxygen atmosphere originate?].

    PubMed

    Schäfer, G

    2004-09-01

    The planet earth did not carry an oxygen atmosphere from the beginning. Though oxygen could arise from radiation mediated water splitting, these processes were not efficient enough to create a global gas atmosphere. Oxygen in the latter is a product of the photosynthetic activity of early green organisms. Only after biological mass-formation of oxygen the UV-protective ozone layer could develop, then enabeling life to move from water onto land. This took billions of years. The basics of the processes of biological oxygen liberation and utilization are described in the following as well as the importance of their steady state equilibrium. Also a hint is given to oxygen as a toxic compound though being a chemical prerequisite for aerobic life on earth.

  10. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The CO-CO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  11. The impact of decreasing cutoff values for maximal oxygen consumption (VO2max) in the decision-making process for candidates to lung cancer surgery

    PubMed Central

    Gatani, Tindaro; Di Maio, Massimo; Meoli, Ilernando; La Rocca, Antonello; Martucci, Nicola; La Manna, Carmine; Stefanelli, Francesco

    2013-01-01

    Background Maximal oxygen consumption (VO2max) is considered a decisive test for risk prediction in patients with borderline cardiopulmonary reserve. Guidelines have adopted decreasing VO2max cut-off values to define operability within acceptable mortality and morbidity limits. We wanted to investigate how the adoption of decreasing VO2max cut-off-values assessment contributed to better select lung surgery candidates. Methods One hundred and nineteen consecutive surgical candidates have been prospectively analyzed as a sample population. Preoperative work-up included spirometry and transfer factor (DLco); irrespective of the spirometric values, these patients were subjected to VO2max assessment. Surgical eligibility was decided by the same surgeon throughout the series. In the postoperative period, overall mortality and the occurrence of any, major or minor complications was recorded and graded according to the Common Terminology Criteria for Adverse Events v.4.3. Results Three arbitrary cut-offs were introduced at 15, 14 and 12 mL.kg-1.min-1. Notably, 15 and 12 mL.kg-1.min-1 correlated with percentage VO2max values of 50% and 35% of predicted (P<0.0001 and 0.0079), respectively. Accordingly, the patients were subdivided into groups in which the prevalence of postoperative morbidity was recorded. The groups were homogeneous as to age, BMI, preoperative absolute and percentage FEV1 and DLco. In the Cox proportionate-hazards multivariate analysis, VO2max less than 35% (P=0.0017) and CTCAE >2 (P=0.0457) emerged as significant predictors of survival after surgery. Conversely on logistic regression analysis, age over 70 years (P=0.03) and pneumonectomy (P=0.001), but not VO2max cut-off values, were significant predictors of major (CTCAE >2) morbidity. Conclusions Since VO2max is increasingly used to contribute to risk prediction for the individual patient, surgeons need to be advised that the concept of a definitive, generalized cut-off value for VO2max is probably a

  12. Oxygen chemisorption cryogenic refrigerator

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1987-01-01

    The present invention relates to a chemisorption compressor cryogenic refrigerator which employs oxygen to provide cooling at 60 to 100 K. The invention includes dual vessels containing an oxygen absorbent material, alternately heated and cooled to provide a continuous flow of high pressure oxygen, multiple heat exchangers for precooling the oxygen, a Joule-Thomson expansion valve system for expanding the oxygen to partially liquefy it and a liquid oxygen pressure vessel. The primary novelty is that, while it was believed that once oxygen combined with an element or compound the reaction could not reverse to release gaseous oxygen, in this case oxygen will indeed react in a reversible fashion with certain materials and will do so at temperatures and pressures which make it practical for incorporation into a cryogenic refrigeration system.

  13. The story of oxygen.

    PubMed

    Heffner, John E

    2013-01-01

    The history of oxygen from discovery to clinical application for patients with chronic lung disease represents a long and storied journey. Within a relatively short period, early investigators not only discovered oxygen but also recognized its importance to life and its role in respiration. The application of oxygen to chronic lung disease, however, took several centuries. In the modern era, physiologists pursued the chemical nature of oxygen and its physiologic interaction with cellular metabolism and gas transport. It took brazen clinicians, however, to pursue oxygen as a therapeutic resource for patients with chronic lung disease because of the concern in the 20th century of the risks of oxygen toxicity. Application of ambulatory oxygen devices allowed landmark investigations of the long-term effects of continuous oxygen that established its safety and efficacy. Although now well established for hypoxic patients, many questions remain regarding the benefits of oxygen for varying severity and types of chronic lung disease.

  14. Phase equilibria in the YBCuO system and melt processing of Ag clad Y 1Ba 2Cu 3O 7- x tapes at reduced oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    MacManus-Driscoll, J. L.; Bravman, J. C.; Beyers, R. B.

    1995-02-01

    We have undertaken phase-stability studies of Y 1Ba 2Cu 3O 7- x(+Ag) and BaCu 2O 2 (+Ag) over the temperature range 780°C-950°C and oxygen partial pressure range 1.0 × 10 -6-2.0 × 10 -1 atm. Ag was found to have no effect on the thermodynamic stability of either phase. Partial melting of YBCO was found at temperatures as low as 800°C ± 10°C, with significant peritectic melting at temperatures as low as 900°C ± 10°C. These thermochemical studies have enabled us to determine the optimum conditions for reduced temperature and pressure (RTP) processing of Ag clad Y 1Ba 2Cu 3O 7- x pellets and tapes. The classic domain structure with strong texturing over short lengths was produced in samples melt processed by controlling oxygen partial pressure at a fixed temperature. The RTP method has the advantage that the second phase Y 2BaCuO 5 particle size can be controlled. Moreover, the technique offers the promise of long lengths of flexible Y 1Ba 2Cu 3O 7- x tapes with high current carrying capability.

  15. Choosing the appropriate configuration and cannulation strategies for extracorporeal membrane oxygenation: the potential dynamic process of organ support and importance of hybrid modes.

    PubMed

    Sorokin, Vitaly; MacLaren, Graeme; Vidanapathirana, Puwalani C; Delnoij, Thijs; Lorusso, Roberto

    2017-05-01

    Extracorporeal membrane oxygenation (ECMO) is becoming a common procedure to support patients with severe cardio-circulatory or respiratory failure as well as in case of combined compromise of the two systems. Deciding which ECMO configuration and proceeding with an uneventful implantation, however, may present minor or major shortcomings. Cannulation techniques should be tailored to specific patient conditions to provide sufficient regional and systemic perfusion, both of which must be comprehensively monitored. Changes in the patient's status or suboptimal ECMO-related support, however, may occur and should trigger re-appraisal of the cannulation strategy and circuit configuration. This dynamic management, based around the adequacy of end organ perfusion and patient requirements, may dictate ECMO configuration and cannulation changes. In these circumstances, adjunct of a cannula in the venous or arterial vasculature may represent a mandatory procedure to solve unfavorable hemodynamic status or enhance ECMO efficiency. These type of ECMO configurations, different from basic one, and called hybrid configurations, may represent, therefore, a critical aspect of optimal ECMO management towards optimized and successful temporary support. The aim of this review is to critically appraise and summarize the existing literature on adult ECMO configuration including cannulation strategies and circuit arrangement, and highlighting more complex pattern required in some specific clinical settings. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

  16. Mechanical and photo-fragmentation processes for nanonization of melanin to improve its efficacy in protecting cells from reactive oxygen species stress

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Cheng; Chen, Sih-Min; Liu, Jhong-Han; Hsu, Hsiang-Wei; Lin, Hoang-Yan; Chen, Szu-yuan

    2015-02-01

    It has been well established ex vivo that melanin has the ability of scavenging free radicals and reactive oxygen species (ROS), besides other functions. Therefore, we propose to utilize nanonized melanin as medication against acute oxidative stress. For this purpose, we developed and characterized two techniques based on mechanical stir and photo-fragmentation using femtosecond laser pulses, respectively, for disintegration of suspended melanin powder to produce nanometer-sized and water-dispersible melanin. This resolves a major obstacle in the medical and industrial applications of melanin. The viabilities of cultured retinal pigment epithelium (RPE) cells exposed to exogenous H2O2 stress and treated with various conditions of melanin and irradiation were compared. It was found that melanin could be nanonized very effectively with the techniques, and nanonized melanin exhibited a much stronger effect than unprocessed melanin on raising the viability of cultured RPE cells under acute ROS stress. The effect was even more prominent without simultaneous light irradiation, promising for effective in vivo application to the whole body.

  17. Mechanical and photo-fragmentation processes for nanonization of melanin to improve its efficacy in protecting cells from reactive oxygen species stress

    SciTech Connect

    Liu, Yi-Cheng; Chen, Sih-Min; Liu, Jhong-Han; Hsu, Hsiang-Wei; Lin, Hoang-Yan; Chen, Szu-yuan

    2015-02-14

    It has been well established ex vivo that melanin has the ability of scavenging free radicals and reactive oxygen species (ROS), besides other functions. Therefore, we propose to utilize nanonized melanin as medication against acute oxidative stress. For this purpose, we developed and characterized two techniques based on mechanical stir and photo-fragmentation using femtosecond laser pulses, respectively, for disintegration of suspended melanin powder to produce nanometer-sized and water-dispersible melanin. This resolves a major obstacle in the medical and industrial applications of melanin. The viabilities of cultured retinal pigment epithelium (RPE) cells exposed to exogenous H{sub 2}O{sub 2} stress and treated with various conditions of melanin and irradiation were compared. It was found that melanin could be nanonized very effectively with the techniques, and nanonized melanin exhibited a much stronger effect than unprocessed melanin on raising the viability of cultured RPE cells under acute ROS stress. The effect was even more prominent without simultaneous light irradiation, promising for effective in vivo application to the whole body.

  18. Solid state oxygen sensor

    DOEpatents

    Garzon, Fernando H.; Chung, Brandon W.; Raistrick, Ian D.; Brosha, Eric L.

    1996-01-01

    Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer.

  19. Solid state oxygen sensor

    DOEpatents

    Garzon, F.H.; Chung, B.W.; Raistrick, I.D.; Brosha, E.L.

    1996-08-06

    Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer. 4 figs.

  20. Atomic transport of oxygen

    SciTech Connect

    Routbort, J.L.; Tomlins, G.W.

    1994-06-15

    Atomic transport of oxygen in nonstoichiometric oxides is an extremely important topic which overlaps science and technology. In many cases the diffusion of oxygen controls sintering, grain growth, and creep. High oxygen diffusivity is critical for efficient operation of many fuel cells. Additionally, oxygen diffusivities are an essential ingredient in any point defect model. Secondary Ion Mass Spectrometry (SIMS) is the most accurate modern technique to measure oxygen tracer diffusion. This paper briefly reviews the principles and applications of SIMS for the measurement of oxygen transport. Case studies are taken from recent work on ZnO and some high-temperature superconductors.

  1. Modelling Tumour Oxygenation, Reoxygenation and Implications on Treatment Outcome

    PubMed Central

    Dasu, Alexandru

    2013-01-01

    Oxygenation is an important component of the tumour microenvironment, having a significant impact on the progression and management of cancer. Theoretical determination of tissue oxygenation through simulations of the oxygen transport process is a powerful tool to characterise the spatial distribution of oxygen on the microscopic scale and its dynamics and to study its impact on the response to radiation. Accurate modelling of tumour oxygenation must take into account important aspects that are specific to tumours, making the quantitative characterisation of oxygenation rather difficult. This paper aims to discuss the important aspects of modelling tumour oxygenation, reoxygenation, and implications for treatment. PMID:23401721

  2. Factors controlling oxygen utilization.

    PubMed

    Biaglow, John; Dewhirst, Mark; Leeper, Dennis; Burd, Randy; Tuttle, Steve

    2005-01-01

    We demonstrate, theoretically, that oxygen diffusion distance is related to the metabolic rate of tumors (QO2) as well as the oxygen tension. The difference in QO2 rate between tumors can vary by as much as 80-fold. Inhibition of oxygen utilization by glucose or chemical inhibitors can improve the diffusion distance. Combining respiratory inhibitors with increased availability of oxygen will further improve the oxygen diffusion distance for all tumors. A simple means for inhibiting oxygen consumption is the use of glucose (the Crabtree effect). The inhibition of tumor oxygen utilization by glucose occurs in R323OAc mammary carcinoma and 9L glioma cells. However, stimulation of oxygen consumption is observed with glucose in the Q7 hepatoma cell line. MIBG, a known inhibitor of oxygen utilization, blocks oxygen consumption in 9L, but is weakly inhibitory with the Q7. Q7 tumor cells demonstrate an anomalous behavior of glucose and MIBG on oxygen consumption. Our results clearly demonstrate the necessity for comparing effects of different agents on different tumor cells. Generalizations cannot be made with respect to the choice of inhibitor for in vivo use. Our work shows that oxygen consumption also can be inhibited with malonate and chlorosuccinate. These substrates may be effective in vivo, where glucose is low and glutamine is the major substrate. Our results indicate that information about individual tumor substrate-linked metabolic controls may be necessary before attempting to inhibit oxygen utilization in vivo for therapeutic benefit.

  3. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-12-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  4. The distribution pattern of the red tide and the process of oxygen depletion in the coastal brackish Lake Nakaumi, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Seto, K.; Miyagi, H.; Katsuki, K.; Takata, H.; Dettman, D. L.

    2007-12-01

    Lake Nakaumi is a coastal brackish water lake formed by the Yumigahama peninsula. The water mass of Lake Nakaumi has two-layer structures. The main halocline divided to Nakaumi Surface Water (NSW) of the intermediate saline water (around 15psu) and Nakaumi Bottom Water (NBW) of the high saline water (about 30psu). Recently, the occurrence of red tide bloom is frequently observed in the lake. The main purpose of this study is to understand the influence of the red tide on the lake environment (The especially, dissolved oxygen in NBW). In this study, we investigated the water quality during April to June 2006 when the lake has experienced extensive occurrence of red tide, and we also monitored the chlorophyll-a (Chl-a) distribution by in vivo fluorometric method. ? Red tide blooms were observed almost in the entire area of Lake Nakaumi in spring, 2006. The water surface showed reddish brown color due to the occurrence of red tide. In the composition of the phytoplankton, Prorocentrum minimum was the dominant species during the red tide. The composition of the phytoplankton rapidly changed during May 27 to 30, and it shifts to the community in which Cyanophyceae is dominant. During that time, the Chl-a concentration rapidly decreased. Based on the vertical distribution of the Chl-a concentration, the red tide at our observation period was divided to 3 phases. In Phase I (March 18th to April 22nd), the Chl-a concentration was relatively low, and homogenous distribution in NSW. In Phase II (April 22nd to May 10th), the Chl-a concentration shows high value, and the peak of Chl-a concentration was present at small-scale and main halocline in the whole water column. In Phase III (May 10th to May 27th), the peak concentrations of Chl-a were distributed around small-scale halocline in NSW and main halocline. In NBW, the Chl-a concentration was low. In Phase I, the dissolved oxygen (DO) concentration of NBW shows 5~7mg/l. During Phase II, DO in NBW decreased. The decreasing

  5. EVALUATING AN INNOVATIVE OXYGEN SENSOR FOR REMOTE SUBSURFACE OXYGEN MEASUREMENTS

    SciTech Connect

    Millings, M; Brian Riha, B; Warren Hyde, W; Karen Vangelas, K; Brian02 Looney, B

    2006-10-12

    Oxygen is a primary indicator of whether anaerobic reductive dechlorination and similar redox based processes contribute to natural attenuation remedies at chlorinated solvent contaminated sites. Thus, oxygen is a viable indicator parameter for documenting that a system is being sustained in an anaerobic condition. A team of researchers investigated the adaptation of an optical sensor that was developed for oceanographic applications. The optical sensor, because of its design and operating principle, has potential for extended deployment and sensitivity at the low oxygen levels relevant to natural attenuation. The results of the research indicate this tool will be useful for in situ long-term monitoring applications, but that the traditional characterization tools continue to be appropriate for characterization activities.

  6. Glovebox oxygen monitoring system

    SciTech Connect

    Haggard, R.

    1993-08-01

    This system is located in the Replacement Tritium Facility (RTF) at the Savannah River Site of the US Department of Energy. The basic system consists of an oxygen sensor module located inside the glovebox and a wall mounted panel located outside the glovebox that contains an electronics package that displays the oxygen level, displays alarms, and sends signals to a facility Distributed Control System (DCS). RTF is a new facility that will be used primarily to load and unload tritium reservoirs, and recycle the tritium for use in existing or new reservoirs. Tritium, an oderless, colorless, gas is a radioactive isotope of hydrogen that is used in modern thermonuclear weapons. Once on-line, RTF will replace other tritium facilities that have been in existence since the 1950`s. Since the entire process at RTF is contained in nitrogen blanketed gloveboxes and features have been provided to recapture fugitive tritium, environmental releases and worker exposure to tritium will be reduced compared to the old facilities.

  7. Corrosion of copper in oxygen-deficient groundwater with and without deep bedrock micro-organisms: Characterisation of microbial communities and surface processes

    NASA Astrophysics Data System (ADS)

    Huttunen-Saarivirta, E.; Rajala, P.; Bomberg, M.; Carpén, L.

    2017-02-01

    Copper specimens were exposed to oxygen-deficient artificial groundwater in the presence and absence of micro-organisms enriched from the deep bedrock of the planned nuclear waste repository site at Olkiluoto island on the western coast of Finland. During the exposure periods of 4 and 10 months, the copper specimens were subjected to electrochemical measurements. The biofilm developed on the specimens and the water used in the exposures were subjected to microbiological analyses. Changes in the water chemistry were also determined and surfaces of the copper specimens were characterized with respect to the morphology and composition of the formed corrosion products. The results showed that under biotic conditions, redox of the water and open circuit potential (OCP) of the copper specimens were generally negative and resulted in the build-up of a copper sulphide, Cu2S, layer due to the activity of sulphate-reducing bacteria (SRB) that were included in the system. In the 4-month test, the electrochemical behaviour of the specimens changed during the exposure and alphaproteobactria Rhizobiales were the dominant bacterial group in the biofilm where the highest corrosion rate was observed. In the 10-month test, however, deltaproteobacteria SRB flourished and the initial electrochemical behaviour and the low corrosion rate of the copper were retained until the end of the test period. Under abiotic conditions, the positive water redox potential and specimen OCP correlated with the formation of copper oxide, Cu2O. Furthermore, in the absence of SRB, Cu2O provided slightly inferior protection against corrosion compared to that by Cu2S in the presence of SRB. The obtained results show that the presence of microorganisms may enhance the passivity of copper. In addition, the identification of key microbial species, such as SRB thriving on copper for long time periods, is important for successful prediction of the behaviour of copper.

  8. Workshop on Oxygen in Asteroids and Meteorites

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Contents include the following: Constraints on the detection of solar nebula's oxidation state through asteroid observation. Oxidation/Reduction Processes in Primitive Achondrites. Low-Temperature Chemical Processing on Asteroids. On the Formation Location of Asteroids and Meteorites. The Spectral Properties of Angritic Basalts. Correlation Between Chemical and Oxygen Isotopic Compositions in Chondrites. Effect of In-Situ Aqueous Alteration on Thermal Model Heat Budgets. Oxidation-Reduction in Meteorites: The Case of High-Ni Irons. Ureilite Atmospherics: Coming up for Air on a Parent Body. High Temperature Effects Including Oxygen Fugacity, in Pre-Planetary and Planetary Meteorites and Asteroids. Oxygen Isotopic Variation of Asteroidal Materials. High-Temperature Chemical Processing on Asteroids: An Oxygen Isotope Perspective. Oxygen Isotopes and Origin of Opaque Assemblages from the Ningqiang Carbonaceous Chondrite. Water Distribution in the Asteroid Belt. Comparative Planetary Mineralogy: V Systematics in Planetary Pyroxenes and fo 2 Estimates for Basalts from Vesta.

  9. Pilot Plant Makes Oxygen Difluoride

    NASA Technical Reports Server (NTRS)

    Humphrey, Marshall F.; Lawton, Emil A.

    1989-01-01

    Pilot plant makes oxygen difluoride highly-energetic, space-storable oxidizer not made commercially. Designed to handle reactants, product, and byproduct, most of which highly reactive, corrosive, and toxic. Oxygen difluoride evolves continuously from reactor containing potassium hydroxide in water at 10 degree C. Collection tanks alternated; one filled while other drained to storage cylinder. Excess OF2 and F2 dissipated in combustion of charcoal in burn barrel. Toxic byproduct, potassium fluoride, reacted with calcium hydroxide to form nontoxic calcium fluoride and to regenerate potassium hydroxide. Equipment processes toxic, difficult-to-make substance efficiently and safely.

  10. Pilot Plant Makes Oxygen Difluoride

    NASA Technical Reports Server (NTRS)

    Humphrey, Marshall F.; Lawton, Emil A.

    1989-01-01

    Pilot plant makes oxygen difluoride highly-energetic, space-storable oxidizer not made commercially. Designed to handle reactants, product, and byproduct, most of which highly reactive, corrosive, and toxic. Oxygen difluoride evolves continuously from reactor containing potassium hydroxide in water at 10 degree C. Collection tanks alternated; one filled while other drained to storage cylinder. Excess OF2 and F2 dissipated in combustion of charcoal in burn barrel. Toxic byproduct, potassium fluoride, reacted with calcium hydroxide to form nontoxic calcium fluoride and to regenerate potassium hydroxide. Equipment processes toxic, difficult-to-make substance efficiently and safely.

  11. Chemical oxygen generation.

    PubMed

    Ward, Kevin R; Huvard, Gary S; McHugh, Mark; Mallepally, Rajender R; Imbruce, Richard

    2013-01-01

    While pressurized oxygen in tank form, as well as oxygen concentrators, are ubiquitous in civilian healthcare in developed countries for medical use, there are a number of settings where use of these oxygen delivery platforms is problematic. These settings include but are not limited to combat casualty care and healthcare provided in extreme rural environments in undeveloped countries. Furthermore, there are a number of settings where delivery of oxygen other than the pulmonary route to oxygenate tissues would be of value, including severe lung injury, airway obstruction, and others. This paper provides a brief overview of the previous and current attempts to utilize chemical oxygen production strategies to enhance systemic oxygenation. While promising, the routine use of chemically produced oxygen continues to pose significant engineering and physiologic challenges.

  12. Oxygen in Orion

    NASA Image and Video Library

    2011-08-01

    This graphic illustrates where astronomers at last found oxygen molecules in space -- near the star-forming core of the Orion nebula. The squiggly lines, or spectra, reveal the signatures of oxygen molecules, detected by ESA Hershel Space Observatory.

  13. Hyperbaric oxygen therapy

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002375.htm Hyperbaric oxygen therapy To use the sharing features on this page, please enable JavaScript. Hyperbaric oxygen therapy uses a special pressure chamber to increase ...

  14. Miniature oxygen resuscitator

    NASA Technical Reports Server (NTRS)

    Johnson, G.; Teegen, J. T.; Waddell, H.

    1969-01-01

    Miniature, portable resuscitation system is used during evacuation of patients to medical facilities. A carrying case contains a modified resuscitator head, cylinder of oxygen, two-stage oxygen regulator, low pressure tube, and a mask for mouth and nose.

  15. Hydrogen- and oxygen from water.

    PubMed

    Fletcher, E A; Moen, R L

    1977-09-09

    The limitations of thermochemical energy storage devices are the limitations of Carnot devices. Entropy production entailed in product separation further limits the efficiency of thermochemical processes. Thus, high upper temperatures and few reaction steps are desirable. In this article, the one-step effusional separation of water into hydrogen and oxygen is considered. Membrane materials, design, and fabrication techniques are suggested. A parametric analysis of the process suggests that the idea is a tantalizing possibility.

  16. Oxygen electrode in molten carbonate fuel cells

    SciTech Connect

    Dave, B.B.; White, R.E. . Dept. of Chemical Engineering); Srinivasan, S; Appleby, A.J. . Center for Electrochemical Systems and Hydrogen Research)

    1990-01-01

    During this quarter, impedance data were analyzed for oxygen reduction process in molten carbonate electrolyte and a manuscript, Impedance Analysis for Oxygen Reduction in a Lithium Carbonate Melt: Effects of Partial Pressure of Carbon Dioxide and Temperature,'' was prepared which will be submitted to Journal of the Electrochemical Society for publication. 31 refs., 10 figs., 5 tabs.

  17. Oxygen control with microfluidics.

    PubMed

    Brennan, Martin D; Rexius-Hall, Megan L; Elgass, Laura Jane; Eddington, David T

    2014-11-21

    Cellular function and behavior are affected by the partial pressure of O2, or oxygen tension, in the microenvironment. The level of oxygenation is important, as it is a balance of oxygen availability and oxygen consumption that is necessary to maintain normoxia. Changes in oxygen tension, from above physiological oxygen tension (hyperoxia) to below physiological levels (hypoxia) or even complete absence of oxygen (anoxia), trigger potent biological responses. For instance, hypoxia has been shown to support the maintenance and promote proliferation of regenerative stem and progenitor cells. Paradoxically, hypoxia also contributes to the development of pathological conditions including systemic inflammatory response, tumorigenesis, and cardiovascular disease, such as ischemic heart disease and pulmonary hypertension. Current methods to study cellular behavior in low levels of oxygen tension include hypoxia workstations and hypoxia chambers. These culture systems do not provide oxygen gradients that are found in vivo or precise control at the microscale. Microfluidic platforms have been developed to overcome the inherent limits of these current methods, including lack of spatial control, slow equilibration, and unachievable or difficult coupling to live-cell microscopy. The various applications made possible by microfluidic systems are the topic of this review. In order to understand how the microscale can be leveraged for oxygen control of cells and tissues within microfluidic systems, some background understanding of diffusion, solubility, and transport at the microscale will be presented in addition to a discussion on the methods for measuring the oxygen tension in microfluidic channels. Finally the various methods for oxygen control within microfluidic platforms will be discussed including devices that rely on diffusion from liquid or gas, utilizing on-or-off-chip mixers, leveraging cellular oxygen uptake to deplete the oxygen, relying on chemical reactions in

  18. Oxygen evolution reaction catalysis

    DOEpatents

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  19. Solid state oxygen sensor

    DOEpatents

    Garzon, Fernando H.; Brosha, Eric L.

    1997-01-01

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures.

  20. Production and Consumption of Reactive Oxygen Species by Fullerenes

    EPA Science Inventory

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

  1. Production and Consumption of Reactive Oxygen Species by Fullerenes

    EPA Science Inventory

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

  2. Oxygen therapy - infants

    MedlinePlus

    ... the cells in the body get too little oxygen, energy production decreases. With too little energy, cells may not work well and may die. Your baby may not grow properly. Many of the developing organs, ... much oxygen can also cause injury. Breathing too much oxygen ...

  3. Hypoxemia (Low Blood Oxygen)

    MedlinePlus

    Symptoms Hypoxemia (low blood oxygen) By Mayo Clinic Staff Hypoxemia is a below-normal level of oxygen in your blood, specifically in the arteries. Hypoxemia ... of breath. Hypoxemia is determined by measuring the oxygen level in a blood sample taken from an ...

  4. Indicators: Dissolved Oxygen

    EPA Pesticide Factsheets

    Dissolved oxygen (DO) is the amount of oxygen that is present in water. It is an important measure of water quality as it indicates a water body's ability to support aquatic life. Water bodies receive oxygen from the atmosphere and from aquatic plants.

  5. Oxygen boost pump study

    NASA Technical Reports Server (NTRS)

    1975-01-01

    An oxygen boost pump is described which can be used to charge the high pressure oxygen tank in the extravehicular activity equipment from spacecraft supply. The only interface with the spacecraft is the +06 6.205 Pa supply line. The breadboard study results and oxygen tank survey are summarized and the results of the flight-type prototype design and analysis are presented.

  6. Oxygen diffusion in cuprate superconductors

    SciTech Connect

    Routbort, J.L.; Rothman, S.J.

    1995-01-01

    Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La{sub 2}{sub {minus}}{sub {times}}Sr{sub {times}}CuO{sub 4}, YBa{sub 2}Cu{sub 3}O{sub 7}{sub {minus}}{delta}, YBa{sub 2}Cu{sub 4}O{sub 8}, and the Bi{sub 2}Sr{sub 2}Ca{sub n}{sub {minus}}{sub 1}Cu{sub n}O{sub 2}{sub +}{sub 4} (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible.

  7. The Role of Oxygen during Fracture Healing

    PubMed Central

    Lu, Chuanyong; Saless, Neema; Wang, Xiaodong; Sinha, Arjun; Decker, Sebastian; Kazakia, Galateia; Hou, Huagang; Williams, Benjamin; Swartz, Harold M.; Hunt, Thomas K.; Miclau, Theodore; Marcucio, Ralph S.

    2016-01-01

    Oxygen affects the activity of multiple skeletogenic cells and is involved in many processes that are important for fracture healing. However, the role of oxygen in fracture healing has not been fully studied. Here we systematically examine the effects of oxygen tension on fracture healing and test the ability of hyperoxia to rescue healing defects in a mouse model of ischemic fracture healing. Mice with tibia fracture were housed in custom-built gas chambers and groups breathed a constant atmosphere of 13% oxygen (hypoxia), 21% oxygen (normoxia), or 50% oxygen (hyperoxia). The influx of inflammatory cells to the fracture site, stem cell differentiation, tissue vascularization, and fracture healing were analyzed. In addition, the efficacy of hyperoxia (50% breathing oxygen) as a treatment regimen for fracture nonunion was tested. Hypoxic animals had decreased tissue vascularity, decreased bone formation, and delayed callus remodeling. Hyperoxia increased tissue vascularization, altered fracture healing in un-complicated fractures, and improved bone repair in ischemia-induced delayed fracture union. However, neither hypoxia nor hyperoxia significantly altered chondrogenesis or osteogenesis during early stages of fracture healing, and infiltration of macrophages and neutrophils was not affected by environmental oxygen after bone injury. In conclusion, our results indicate that environmental oxygen levels affect tissue vascularization and fracture healing, and that providing oxygen to patients with fractures accompanied by ischemia may be beneficial. PMID:23063782

  8. Nitrate-nitrogen and oxygen isotope ratios for identification of nitrate sources and dominant nitrogen cycle processes in a tile-drained dryland agricultural field

    USDA-ARS?s Scientific Manuscript database

    Agricultural systems are a leading source of reactive nitrogen to aquatic and atmospheric ecosystems. Natural d15Nnitrate and d18Onitrate are used to identify the dominant nitrogen cycle processes and sources of NO3- leached from a tile-drained, dryland agricultural field. Tile-drain water discharge...

  9. Tissue oxygen measurement system

    NASA Technical Reports Server (NTRS)

    Soller, Babs R. (Inventor)

    2004-01-01

    A device and method in accordance with the invention for determining the oxygen partial pressure (PO.sub.2) of a tissue by irradiating the tissue with optical radiation such that the light is emitted from the tissue, and by collecting the reflected or transmitted light from the tissue to form an optical spectrum. A spectral processor determines the PO.sub.2 level in tissue by processing this spectrum with a previously-constructed spectral calibration model. The tissue may, for example, be disposed underneath a covering tissue, such as skin, of a patient, and the tissue illuminated and light collected through the skin. Alternatively, direct tissue illumination and collection may be effected with a hand-held or endoscopic probe. A preferred system also determines pH from the same spectrum, and the processor may determine critical conditions and issue warnings based on parameter values.

  10. Oxygen diffusion barrier coating

    NASA Technical Reports Server (NTRS)

    Unnam, Jalaiah (Inventor); Clark, Ronald K. (Inventor)

    1987-01-01

    A method for coating a titanium panel or foil with aluminum and amorphous silicon to provide an oxygen barrier abrogating oxidation of the substrate metal is developed. The process is accomplished with known inexpensive procedures common in materials research laboratories, i.e., electron beam deposition and sputtering. The procedures are conductive to treating foil gage titanium and result in submicron layers which virtually add no weight to the titanium. There are no costly heating steps. The coatings blend with the substrate titanium until separate mechanical properties are subsumed by those of the substrate without cracking or spallation. This method appreciably increases the ability of titanium to mechanically perform in high thermal environments such as those witnessed on structures of space vehicles during re-entry

  11. Diffusion and solubility of oxygen in silver

    NASA Technical Reports Server (NTRS)

    Eichenauer, W.; Miller, G.

    1985-01-01

    The diffusion and solubility of oxygen in Ag in the temperature range between 412 and 862 C was determined. The following interpolation formula was found for the solubility: L = 8.19.1/100.exp(-11 860/RT)Mol O2/g.At.Ag.at 1/.5. The process obeys the Sieverts square root law within the limits of error. The dissolution of oxygen in Ag may be accompanied by the dissociation of the oxygen molecules into atoms. The tests on Ag-foils reveal that below a temperature of about 500 C a higher solubility is simulated by the adsorption of oxygen. The diffusion coefficient of oxygen in silver obeys the following equation: D = 2.72.1/100.exp(-11 000/RT)sq cm/s. The relatively low activation energy of 11 kcal/g.At suggests that the diffusion of oxygen takes places over interstitial sites.

  12. A Survey of Alternative Oxygen Production Technologies

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E.; Parrish, Clyde F.; Buttner, William J.; Surma, Jan M.; Delgado, H. (Technical Monitor)

    2000-01-01

    Utilization of the Martian atmosphere for the production of fuel and oxygen has been extensively studied. The baseline fuel production process is a Sabatier reactor, which produces methane and water from carbon dioxide and hydrogen. The oxygen produced from the electrolysis of the water is only half of that needed for methane-based rocket propellant, and additional oxygen is needed for breathing air, fuel cells and other energy sources. Zirconia electrolysis cells for the direct reduction of CO2 are being developed as an alternative means of producing oxygen, but present many challenges for a large-scale oxygen production system. The very high operating temperatures and fragile nature of the cells coupled with fairly high operating voltages leave room for improvement. This paper will survey alternative oxygen production technologies, present data on operating characteristics, materials of construction, and some preliminary laboratory results on attempts to implement each.

  13. A survey of alternative oxygen production technologies

    NASA Astrophysics Data System (ADS)

    Lueck, Dale E.; Parrish, Clyde F.; Buttner, William J.; Surma, Jan M.

    2001-02-01

    Utilization of the Martian atmosphere for the production of fuel and oxygen has been extensively studied. The baseline fuel production process is a Sabatier reactor, which produces methane and water from carbon dioxide and hydrogen. The oxygen produced from the electrolysis of the water is only half of that needed for methane-based rocket propellant, and additional oxygen is needed for breathing air, fuel cells and other energy sources. Zirconia electrolysis cells for the direct reduction of CO2 are being developed as an alternative means of producing oxygen, but present many challenges for a large-scale oxygen production system. The very high operating temperatures and fragile nature of the cells coupled with fairly high operating voltages leave room for improvement. This paper will survey alternative oxygen production technologies, present data on operating characteristics, materials of construction, and some preliminary laboratory results on attempts to implement each. .

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

    NASA Astrophysics Data System (ADS)

    Li, Xuechun; Li, Dian; Wang, Younian

    2016-09-01

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

  15. Enhanced humification by carbonated basic oxygen furnace steel slag--II. Process characterization and the role of inorganic components in the formation of humic-like substances.

    PubMed

    Qi, Guangxia; Yue, Dongbei; Fukushima, Masami; Fukuchi, Shigeki; Nishimoto, Ryo; Nie, Yongfeng

    2012-06-01

    Enhanced humification by abiotic catalysts is a potentially promising supplementary composting method for stabilizing organic carbon from biowastes. In this study, the role of steel slag in the transformation of humic precursors was directly characterized by measuring the variance in dissolved organic carbon (DOC), spectroscopic parameters (E(600)), and the concentration and molecular weight change of humic-like substances (HLS) during the process. In addition, a mechanistic study of the process was explored. The results directly showed that steel slag greatly accelerated the formation of HLS. The findings indicate that Fe(III)-and Mn(IV)-oxides in steel slag act as oxidants and substantially enhance the polycondensation of humic precursors. Moreover, the reaction appears to suppress the release of metals from steel slag to a certain extent under acidic conditions. This can be attributed to the cover of HLS on the external surface of steel slag, which is significant for its environmentally sound reuse.

  16. Solar Energy Systems for Lunar Oxygen Generation

    NASA Technical Reports Server (NTRS)

    Colozza, Anthony J.; Heller, Richard S.; Wong, Wayne A.; Hepp, Aloysius F.

    2010-01-01

    An evaluation of several solar concentrator-based systems for producing oxygen from lunar regolith was performed. The systems utilize a solar concentrator mirror to provide thermal energy for the oxygen production process. Thermal energy to power a Stirling heat engine and photovoltaics are compared for the production of electricity. The electricity produced is utilized to operate the equipment needed in the oxygen production process. The initial oxygen production method utilized in the analysis is hydrogen reduction of ilmenite. Utilizing this method of oxygen production a baseline system design was produced. This baseline system had an oxygen production rate of 0.6 kg/hr with a concentrator mirror size of 5 m. Variations were performed on the baseline design to show how changes in the system size and process (rate) affected the oxygen production rate. An evaluation of the power requirements for a carbothermal lunar regolith reduction reactor has also been conducted. The reactor had a total power requirement between 8,320 to 9,961 W when producing 1000 kg/year of oxygen. The solar concentrator used to provide the thermal power (over 82 percent of the total energy requirement) would have a diameter of less than 4 m.

  17. Singlet oxygen in photosensitization.

    PubMed

    Moan, Johan; Juzenas, Petras

    2006-01-01

    Oxygen is a ubiquitous element and a vitally important substance for life on the Earth, and especially for human life. Living organisms need oxygen for most, if not all, of their cellular functions. On the other hand, oxygen can produce metabolites that are toxic and potentially lethal to the same cells. Being reactive and chemically unstable reactive oxygen species (ROS) are the most important metabolites that initiate reduction and oxidation (redox) reactions under physiological conditions. Oxygen in its excited singlet state (1O2) is probably the most important intermediate in such reactions. Since the discovery of oxygen by Joseph Priestley in 1775 it has been recognized that oxygen can be both beneficial and harmful to life.

  18. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W.

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  19. Oxygen partial pressure sensor

    DOEpatents

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-01-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals.

  1. High Selectivity Oxygen Delignification

    SciTech Connect

    Arthur J. Ragauskas Lucian A. Lucia Hasan Jameel

    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

  2. Carbon, oxygen and strontium isotopic constraints on fluid sources, temperatures and biogeochemical processes during the formation of seep carbonates - Secchia River site, Northern Apennines

    NASA Astrophysics Data System (ADS)

    Viola, Irene; Capozzi, Rossella; Bernasconi, Stefano M.; Rickli, Jörg

    2017-07-01

    Understanding authigenic seep carbonate formation provides clues for hydrocarbon exploration and insights into contributions to gas budgets of marine environments and the atmosphere. Seep carbonates discovered in the outcropping succession along the Secchia riverbanks (near Modena, Italy) belong to the Argille Azzurre Formation of Early Pleistocene age deposited in an upper shelf environment overlying the Miocene foredeep successions, which include hydrocarbon fields. The fluid migration from the hydrocarbon fields, up to the surface, is presently active on land and started in the marine succession during the Late Miocene. Authigenic globular carbonate concretions and carbonate chimneys are interspersed along the strata throughout the section. A comprehensive geochemical characterisation of the carbonates has been carried out to understand the processes leading to their formation. The carbonate concretions are the record of past hydrocarbon vents linked to the Miocene petroleum system of the Northern Apennines. The samples are composed of > 50% microcrystalline dolomite. The δ13C signatures identify two groups in the samples according to different type of formation processes. Globular concretions have positive values that suggest an influence of CO2 associated to secondary methanogenesis due to microbial degradation of higher hydrocarbons. The analysed chimney, with negative δ13C values, is interpreted as former conduit where carbonate precipitation is promoted by Anaerobic Oxidation of Methane coupled with Sulfate Reduction. The δ18O range, coupled with 87/86Sr signatures, indicate that the contribution of deep connate water from the Miocene reservoirs is up to 23% during the formation of the globular concretions. The connate water occurrence is also documented by higher ambient temperatures. The different isotope signatures in seep carbonates result from the relative contribution of the recognised gas and water components, linked to different plumbing systems

  3. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Oxygen and oxygen equipment. 414.226 Section 414... Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules—(1) Oxygen equipment. Payment for rental of oxygen equipment is made based on a monthly fee schedule...

  4. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 3 2013-10-01 2013-10-01 false Oxygen and oxygen equipment. 414.226 Section 414... Durable Medical Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules—(1) Oxygen equipment. Payment for rental of oxygen equipment is made based on a monthly...

  5. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 3 2012-10-01 2012-10-01 false Oxygen and oxygen equipment. 414.226 Section 414... Durable Medical Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules—(1) Oxygen equipment. Payment for rental of oxygen equipment is made based on a monthly...

  6. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 3 2011-10-01 2011-10-01 false Oxygen and oxygen equipment. 414.226 Section 414... Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules—(1) Oxygen equipment. Payment for rental of oxygen equipment is made based on a monthly fee schedule...

  7. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 3 2014-10-01 2014-10-01 false Oxygen and oxygen equipment. 414.226 Section 414... Durable Medical Equipment, Prosthetic and Orthotic Devices, and Surgical Dressings § 414.226 Oxygen and oxygen equipment. (a) Payment rules—(1) Oxygen equipment. Payment for rental of oxygen equipment is...

  8. 2-Oxoglutarate-dependent dioxygenases are sensors of energy metabolism, oxygen availability, and iron homeostasis: potential role in the regulation of aging process.

    PubMed

    Salminen, Antero; Kauppinen, Anu; Kaarniranta, Kai

    2015-10-01

    Recent studies have revealed that the members of an ancient family of nonheme Fe(2+)/2-oxoglutarate-dependent dioxygenases (2-OGDO) are involved in the functions associated with the aging process. 2-Oxoglutarate and O2 are the obligatory substrates and Fe(2+) a cofactor in the activation of 2-OGDO enzymes, which can induce the hydroxylation of distinct proteins and the demethylation of DNA and histones. For instance, ten-eleven translocation 1-3 (TET1-3) are the demethylases of DNA, whereas Jumonji C domain-containing histone lysine demethylases (KDM2-7) are the major epigenetic regulators of chromatin landscape, known to be altered with aging. The functions of hypoxia-inducible factor (HIF) prolyl hydroxylases (PHD1-3) as well as those of collagen hydroxylases are associated with age-related degeneration. Moreover, the ribosomal hydroxylase OGFOD1 controls mRNA translation, which is known to decline with aging. 2-OGDO enzymes are the sensors of energy metabolism, since the Krebs cycle intermediate 2-oxoglutarate is an activator whereas succinate and fumarate are the potent inhibitors of 2-OGDO enzymes. In addition, O2 availability and iron redox homeostasis control the activities of 2-OGDO enzymes in tissues. We will briefly elucidate the catalytic mechanisms of 2-OGDO enzymes and then review the potential functions of the above-mentioned 2-OGDO enzymes in the control of the aging process.

  9. Hadean Crustal Processes Revealed from Oxygen Isotopes and U-Th-Pb Depth Profiling of Pre-4.0 Ga Detrital Zircons from Western Australia

    NASA Technical Reports Server (NTRS)

    Trail, D.; Mojzsis, S. J.; Harrison, T. M.

    2005-01-01

    Because physical and chemical processes of the past are determined from analysis of a preserved geologic record, little is known about terrestrial crustal processes of the first 500 Ma during the so-called Hadean Eon. What is known from direct measurements has been derived almost exclusively from the study of greater than 4.0 Ga detrital zircons from the Jack Hills, Western Australia. The geochemistry of these zircons has direct application to understanding the origin and evolution of the rocks during the Hadean because: (i) U-Th-Pb age determinations by ion microprobe suggests the presence of crust as early as 4.37 Ga, or shortly after lunar formation; (ii) high-resolution U-Th-Pb zircon depth profiles reported here reveal several episodes of zircon growth in the Hadean previously unrecognized; (iii) core regions of pre-4.0 Ga zircons with igneous compositions are enriched in O-18 and contain metaluminous and peraluminous mineral inclusions, both features indicative of S-type grainitod protoliths. Study of these ancient zircons provides a unique window into the first half billion years that permits assessment of the potential of the Hadean Earth to host an emergent biosphere.

  10. Imaging pH and oxygen at the soil-root interface by planar optodes: a challenging technology to study dynamic rhizosphere processes.

    NASA Astrophysics Data System (ADS)

    Daudin, Gabrielle; Oburger, Eva; Schmidt, Hannes; Borisov, Sergey; Pradier, Céline; Jourdan, Christophe; Marsden, Claire; Obermaier, Daniela; Woebken, Dagmar; Richter, Andreas; Wenzel, Walter; Hinsinger, Philippe

    2017-04-01

    Roots do not only take up water and nutrients from surrounding soil but they also release a wide range of exudates, such as low molecular weight organic compounds, CO2 or protons. Root-soil interactions trigger heterogeneous rhizosphere processes based on differences in root activity along the root axis and with distance from the root surface. Elucidating their temporal and spatial dynamics is of crucial importance for a better understanding of these interrelated biogeochemical processes in the rhizosphere. Therefore, monitoring key parameters at a fine scale and in a non-invasive way at the root-soil interface is essential. Planar optodes are an emerging technology that allows in situ and non-destructive imaging of mainly pH, CO2 and O2. Originated in limnology, planar optodes have recently been applied to soil-root systems in laboratory conditions. This presentation will highlight advantages and challenges of using planar optodes to image pH and O2 dynamics in the rhizosphere, focusing on two RGB (red-green-blue) approaches: a commercially available system (PreSens) and a custom-made one. Important insights into robustness, accuracy, potentials and limitations of the two systems applied to different laboratory/greenhouse-based experimental conditions (flooded and aerobic rhizobox systems, plant species) will be addressed. Furthermore, challenges of optode measurements in the field, including a first case study with Eucalyptus grandis in Brazil, will be discussed.

  11. Excitation-ionization processes in K-shell vacancy production in Li by fast bare oxygen ions: doubly-differential cross sections

    NASA Astrophysics Data System (ADS)

    Śpiewanowski, M. D.; Gulyás, L.; Horbatsch, M.; Kirchner, T.

    2016-05-01

    Recent theoretical work has demonstrated that K-shell vacancy production in Li by 1.5 MeV/amu O8+ impact cannot be understood as a simple one-electron process. Rather, a certain two-electron excitation-ionization process, in which the valence electron is removed, while one of the K-shell electrons makes a transition to an excited state, was found to give the dominant contribution to the singly-differential cross section at low to intermediate energies of the outgoing electron. In this work, we extend the calculations to the doubly-differential level and present cross sections which are differential in the electron energy and the transverse momentum transfer. The calculation involves the combination of impact-parameter-dependent single-electron amplitudes and a two-dimensional Fourier transformation of the resulting multielectron amplitudes to obtain momentum-transfer-dependent transition matrix elements. Results are found to be in good agreement with recent measurements, especially at low outgoing electron energy, and underline the importance of two-electron excitation ionization in this collision system. Work supported by NSERC, Canada and the Hungarian Scientific Research Fund.

  12. Effect of superatmospheric oxygen packaging on sensorial quality, spoilage, and Listeria monocytogenes and Aeromonas caviae growth in fresh processed mixed salads.

    PubMed

    Allende, Ana; Jacxsens, Liesbeth; Devlieghere, Frank; Debevere, Johan; Artés, Francisco

    2002-10-01

    Atmospheres with O2 levels higher than 70 kPa have recently been suggested as an innovation to modified atmosphere packaging (MAP) for fresh processed vegetables to maintain sensory quality and safety. In the present work, mixed vegetable salad collected from a commercial processing plant and stored with the MAP technique was studied. Two gas mixtures were actively generated by using an initial O2 concentration of 95 kPa and combined with two plastic films. The low-barrier film permeability for O2 was 1,629 mlO2/m2 x 24 h x atm with 30 microm of thickness (Hyplast, Hoogstraten, Belgium) and the O2 permeability of the high-barrier film was 2 mlO2/m2 x 24h x atm with 150 microm of thickness (Euralpack, Wommelgen, Belgium) at 23 degrees C. As control, active conventional MAP with application of 3 to 5 kPa of O2 and 6 to 8 kPa of CO2 was used. Packaged salads were stored up to 8 days at 4 degrees C and at temperatures simulating chilled distribution chain conditions. Microbial safety and sensory quality, as well as the survival of inoculated Listeria monocytogenes and Aeromonas caviae, were monitored. The effect of superatmospheric O2 on the growth of aerobic microflora was variable. Under superatmospheric conditions, lactic acid bacteria and members of Enterobacteriaceae were inhibited. Nevertheless, growth of yeast and A. caviae seem to be stimulated by superatmospheric O2, whereas growth of psychrotrophic bacteria and L monocytogenes was not affected. The overall visual appearance (mainly color) of the mixed vegetable salads was better maintained and the shelf life prolonged when packaged under O2 concentrations greater than 50 kPa.

  13. Oxygen requirements of the earliest animals

    PubMed Central

    Mills, Daniel B.; Ward, Lewis M.; Jones, CarriAyne; Sweeten, Brittany; Forth, Michael; Treusch, Alexander H.; Canfield, Donald E.

    2014-01-01

    A rise in the oxygen content of the atmosphere and oceans is one of the most popular explanations for the relatively late and abrupt appearance of animal life on Earth. In this scenario, Earth’s surface environment failed to meet the high oxygen requirements of animals up until the middle to late Neoproterozoic Era (850–542 million years ago), when oxygen concentrations sufficiently rose to permit the existence of animal life for the first time. Although multiple lines of geochemical evidence support an oxygenation of the Ediacaran oceans (635–542 million years ago), roughly corresponding with the first appearance of metazoans in the fossil record, the oxygen requirements of basal animals remain unclear. Here we show that modern demosponges, serving as analogs for early animals, can survive under low-oxygen conditions of 0.5–4.0% present atmospheric levels. Because the last common ancestor of metazoans likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content of the atmosphere and oceans. Instead, other ecological and developmental processes are needed to adequately explain the origin and earliest evolution of animal life on Earth. PMID:24550467

  14. Oxygen requirements of the earliest animals

    NASA Astrophysics Data System (ADS)

    Mills, Daniel B.; Ward, Lewis M.; Jones, CarriAyne; Sweeten, Brittany; Forth, Michael; Treusch, Alexander H.; Canfield, Donald E.

    2014-03-01

    A rise in the oxygen content of the atmosphere and oceans is one of the most popular explanations for the relatively late and abrupt appearance of animal life on Earth. In this scenario, Earth's surface environment failed to meet the high oxygen requirements of animals up until the middle to late Neoproterozoic Era (850-542 million years ago), when oxygen concentrations sufficiently rose to permit the existence of animal life for the first time. Although multiple lines of geochemical evidence support an oxygenation of the Ediacaran oceans (635-542 million years ago), roughly corresponding with the first appearance of metazoans in the fossil record, the oxygen requirements of basal animals remain unclear. Here we show that modern demosponges, serving as analogs for early animals, can survive under low-oxygen conditions of 0.5-4.0% present atmospheric levels. Because the last common ancestor of metazoans likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content of the atmosphere and oceans. Instead, other ecological and developmental processes are needed to adequately explain the origin and earliest evolution of animal life on Earth.

  15. Oxygen requirements of the earliest animals.

    PubMed

    Mills, Daniel B; Ward, Lewis M; Jones, Carriayne; Sweeten, Brittany; Forth, Michael; Treusch, Alexander H; Canfield, Donald E

    2014-03-18

    A rise in the oxygen content of the atmosphere and oceans is one of the most popular explanations for the relatively late and abrupt appearance of animal life on Earth. In this scenario, Earth's surface environment failed to meet the high oxygen requirements of animals up until the middle to late Neoproterozoic Era (850-542 million years ago), when oxygen concentrations sufficiently rose to permit the existence of animal life for the first time. Although multiple lines of geochemical evidence support an oxygenation of the Ediacaran oceans (635-542 million years ago), roughly corresponding with the first appearance of metazoans in the fossil record, the oxygen requirements of basal animals remain unclear. Here we show that modern demosponges, serving as analogs for early animals, can survive under low-oxygen conditions of 0.5-4.0% present atmospheric levels. Because the last common ancestor of metazoans likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content of the atmosphere and oceans. Instead, other ecological and developmental processes are needed to adequately explain the origin and earliest evolution of animal life on Earth.

  16. Oxygen ion conducting materials

    DOEpatents

    Carter, J. David; Wang, Xiaoping; Vaughey, John; Krumpelt, Michael

    2004-11-23

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  17. Oxygen ion conducting materials

    DOEpatents

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2005-07-12

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  18. Integrated turbomachine oxygen plant

    DOEpatents

    Anand, Ashok Kumar; DePuy, Richard Anthony; Muthaiah, Veerappan

    2014-06-17

    An integrated turbomachine oxygen plant includes a turbomachine and an air separation unit. One or more compressor pathways flow compressed air from a compressor through one or more of a combustor and a turbine expander to cool the combustor and/or the turbine expander. An air separation unit is operably connected to the one or more compressor pathways and is configured to separate the compressed air into oxygen and oxygen-depleted air. A method of air separation in an integrated turbomachine oxygen plant includes compressing a flow of air in a compressor of a turbomachine. The compressed flow of air is flowed through one or more of a combustor and a turbine expander of the turbomachine to cool the combustor and/or the turbine expander. The compressed flow of air is directed to an air separation unit and is separated into oxygen and oxygen-depleted air.

  19. Oxygen ion conducting materials

    DOEpatents

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2003-01-01

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  20. Oxygen, a paradoxical element?

    PubMed

    Greabu, Maria; Battino, M; Mohora, Maria; Olinescu, R; Totan, Alexandra; Didilescu, Andreea

    2008-01-01

    Oxygen is an essential element for life on earth. No life may exist without oxygen. But in the last forty years, conclusive evidence demonstrated the double-edge sword of this element. In certain conditions, oxygen may produce reactive species, even free radicals. More, the production of reactive oxygen species (ROS) takes place everywhere: in air, nature or inside human bodies. The paradox of oxygen atom is entirely due to its peculiar electronic structure. But life began on earth, only when nature found efficient weapons against ROS, these antioxidants, which all creatures are extensibly endowed with. The consequences of oxygen activation in human bodies are only partly known, in spite of extensive scientific research on theoretical, experimental and clinical domains.

  1. Continuous home oxygen therapy.

    PubMed

    Ortega Ruiz, Francisco; Díaz Lobato, Salvador; Galdiz Iturri, Juan Bautista; García Rio, Francisco; Güell Rous, Rosa; Morante Velez, Fátima; Puente Maestu, Luis; Tàrrega Camarasa, Julia

    2014-05-01

    Oxygen therapy is defined as the therapeutic use of oxygen and consists of administering oxygen at higher concentrations than those found in room air, with the aim of treating or preventing hypoxia. This therapeutic intervention has been shown to increase survival in patients with chronic obstructive pulmonary disease (COPD) and respiratory failure. Although this concept has been extended by analogy to chronic respiratory failure caused by respiratory and non-respiratory diseases, continuous oxygen therapy has not been shown to be effective in other disorders. Oxygen therapy has not been shown to improve survival in patients with COPD and moderate hypoxaemia, nor is there consensus regarding its use during nocturnal desaturations in COPD or desaturations caused by effort. The choice of the oxygen source must be made on the basis of criteria such as technical issues, patient comfort and adaptability and cost. Flow must be adjusted to achieve appropriate transcutaneous oxyhaemoglobin saturation correction.

  2. Oxygen therapy for COPD.

    PubMed

    McDonald, Christine F

    2014-11-01

    Chronic obstructive pulmonary disease (COPD) is a leading cause of disability and death globally, characterised by progressive breathlessness, loss of function and, in its later stages, chronic hypoxaemia. Long-term continuous oxygen therapy increases life expectancy in patients with severe resting hypoxaemia. However, there are few data to support the use of oxygen in patients with only mild hypoxaemia and more research is required to determine any benefits of oxygen supplementation in COPD in such individuals.

  3. Atomic Oxygen Effects

    NASA Technical Reports Server (NTRS)

    Miller, Sharon K. R.

    2014-01-01

    Atomic oxygen, which is the most predominant species in low Earth orbit, is highly reactive and can break chemical bonds on the surface of a wide variety of materials leading to volatilization or surface oxidation which can result in failure of spacecraft materials and components. This presentation will give an overview of how atomic oxygen reacts with spacecraft materials, results of space exposure testing of a variety of materials, and examples of failures caused by atomic oxygen.

  4. Oxygen concentrators: a primary oxygen supply source.

    PubMed

    Friesen, R M; Raber, M B; Reimer, D H

    1999-12-01

    Efforts to harmonize the standards of the CSA and the ISO, as they relate to compressed medical gas supply and piping, prompted us to review ten years experience with oxygen concentrators (OCs) in Canada used as a primary hospital oxygen supply. The goals of this study were; 1) To document the number of Canadian OC Hospital sites, 2) to define what impact these units have had on medical practice and patient care, and 3) to explore trends in oxygen costing and utilization at the study sites. Following a four part mail survey and telephone follow up, site surveys were conducted for all hospitals utilizing an OC. Installation and service records, operating costs, amortization detail, leasing records as well as patient safety were all detailed. Forty eight of 52 Canadian hospitals utilizing an OC participated. Clinical activity at the surveyed sites of 1996 included 30,642 surgical operations, 9,415 intensive care bed days and 364,529 emergency room visits. The cumulative survey represents 1,026,819 hr of OC operation. During a 24 hr day, OCs operate 55 +/- 3% of the time. Financial analysis was validated at 43 of the 48 hospital sites. During the study the unit cost of oxygen was reduced by 62% (P <.0001). An annual increase in oxygen consumption of 11.5 +/- 2% was documented (P <.0001). No patient care critical incidents related to OCs were reported. An OC installation which is CAN/CSA Z305.6-M92 compliant provides a safe, reliable, cost efficient primary hospital source of oxygen.

  5. Measuring Traces Of Oxygen By Resonant Electron Attachment

    NASA Technical Reports Server (NTRS)

    Man, Kin Fung; Boumsellek, Said; Chutjian, Ara

    1995-01-01

    Method of detecting trace amounts of oxygen based on dissociative attachment of electrons to oxygen molecules followed by measurement of resulting flux of negative oxygen ions in mass spectrometer. High sensitivity achieved in method by exploiting resonance in dissociative attachment of electrons to oxygen molecules: electron-attachment cross section rises to high peak at incident electron kinetic energy of 6.2 eV. Relative concentrations below 1 ppb detected. Devised to increase sensitivity of detection of oxygen in processing chambers in which oxygen regarded as contaminant; for example, chambers used in making semiconductor devices and in growing high-purity crystals.

  6. Artist's concept of oxygen tanks of the Apollo 14 spacecraft

    NASA Image and Video Library

    1971-01-12

    S71-16745 (January 1971) --- An artist's concept illustrating a cutaway view of one of the three oxygen tanks of the Apollo 14 spacecraft. This is the new Apollo oxygen tank design, developed since the Apollo 13 oxygen tank explosion. Apollo 14 has three oxygen tanks redesigned to eliminate ignition sources, minimize the use of combustible materials, and simplify the fabrication process. The third tank has been added to the Apollo 14 Service Module, located in the SM's sector one, apart from the pair of oxygen tanks in sector four. Arrows point out various features of the oxygen tank.

  7. Workshop on Oxygen in the Terrestrial Planets

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in

  8. Mineralization of desmetryne by electrochemical advanced oxidation processes using a boron-doped diamond anode and an oxygen-diffusion cathode.

    PubMed

    Borràs, Núria; Arias, Conchita; Oliver, Ramon; Brillas, Enric

    2011-11-01

    The mineralization of acidic aqueous solutions of the herbicide desmetryne has been studied by electrochemical advanced oxidation processes (EAOPs) such as anodic oxidation with electrogenerated H(2)O(2) (AO-H(2)O(2)), electro-Fenton (EF) and photoelectro-Fenton (PEF) with UVA light. Electrolyses were conducted in an open and cylindrical cell with a boron-doped diamond (BDD) anode and an O(2)-diffusion cathode for H(2)O(2) generation. The main oxidizing species are ()OH radicals formed at the BDD surface in all treatments and in the bulk from Fenton's reaction between added Fe(2+) and electrogenerated H(2)O(2) in EF and PEF. A poor mineralization was attained using AO-H(2)O(2) by the slow oxidation of persistent by-products with ()OH at the BDD surface. The synergistic action of ()OH in the bulk enhanced the degradation rate in EF, although almost total mineralization was only achieved in PEF due to the additional ()OH generation and photolysis of intermediates by UVA irradiation. The effect of current, pH and herbicide concentration on the mineralization degree and mineralization current efficiency of each EAOP was examined. Desmetryne decay always followed a pseudo first-order kinetics, being more rapidly destroyed in the sequence AO-H(2)O(2)

  9. Measuring tissue oxygenation

    NASA Technical Reports Server (NTRS)

    Soyemi, Olusola O. (Inventor); Soller, Babs R. (Inventor); Yang, Ye (Inventor)

    2009-01-01

    Methods and systems for calculating tissue oxygenation, e.g., oxygen saturation, in a target tissue are disclosed. In some embodiments, the methods include: (a) directing incident radiation to a target tissue and determining reflectance spectra of the target tissue by measuring intensities of reflected radiation from the target tissue at a plurality of radiation wavelengths; (b) correcting the measured intensities of the reflectance spectra to reduce contributions thereto from skin and fat layers through which the incident radiation propagates; (c) determining oxygen saturation in the target tissue based on the corrected reflectance spectra; and (d) outputting the determined value of oxygen saturation.

  10. Solid state oxygen sensor

    DOEpatents

    Garzon, F.H.; Brosha, E.L.

    1997-12-09

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures. 6 figs.

  11. Elastomer Compatible With Oxygen

    NASA Technical Reports Server (NTRS)

    Martin, Jon W.

    1987-01-01

    Artificial rubber resists ignition on impact and seals at low temperatures. Filled fluoroelastomer called "Katiflex" developed for use in seals of vessels holding cold liquid and gaseous oxygen. New material more compatible with liquid oxygen than polytetrafluoroethylene. Provides dynamic seal at -196 degrees C with only 4 times seal stress required at room temperature. In contrast, conventional rubber seals burn or explode on impact in high-pressure oxygen, and turn hard or even brittle at liquid-oxygen temperatures, do not seal reliably, also see (MFS-28124).

  12. The role of oxygen in lipid oxidation reactions: a review.

    PubMed

    Johnson, David R; Decker, Eric A

    2015-01-01

    The susceptibility of food oil to quality loss is largely determined by the presence of oxygen. This article reviews the current understanding concerning the effect of oxygen types, location, and concentration on the oxidative stability of foods. It also discusses the major factors that influence the interaction between oxygen and lipids such as antioxidants, prooxidants, reactive oxygen species (ROS), environmental conditions, and oxygen scavengers. Research has shown that the amount of oxygen needed to cause oxidation is generally very small and that by reducing oxygen concentration in containers to less than 2%, oxidative stability can be greatly enhanced. However, very few studies have systematically examined the oxygen levels needed to reduce, or inhibit, lipid oxidation processes. Thus, a more comprehensive understanding of the relationship between oxygen levels and lipid oxidation is necessary for the development of innovative antioxidant solutions and package designs that prolong the quality of foods containing lipids.

  13. Kinetic analysis of the temperature dependence of PbSe colloidal quantum dot photoluminescence: Effects of synthesis process and oxygen exposure

    NASA Astrophysics Data System (ADS)

    Foell, Charles A.; Abel, Keith A.; van Veggel, Frank C. J. M.; Young, Jeff F.

    2014-01-01

    A kinetic model is derived and used to analyze recently published works and new data on the temperature dependence of the spectrally integrated photoluminescence (PL) from thick-film formulations of PbSe colloidal quantum dots (QDs), with particular attention to the effects of air exposure. The model assumes that the excitons thermalize within a ground-state manifold of states and treats the distribution of radiative and nonradiative decay rates within the distribution as generally as possible, while using a minimal number of free parameters. By adjusting the parameters of the model, good fits are obtained for the wide range of integrated PL behaviors reported in [J. Phys. Chem. Lett. 2, 889 (2011), 10.1021/jz2001979; ACS Nano 6, 5498 (2012), 10.1021/nn301405j; Phys. Rev. B 82, 165435 (2010), 10.1103/PhysRevB.82.165435] and the new data presented in this manuscript. By comparing the extracted parameters we deduce the following: (i) All of the samples in the first two references emit from two distinct clusters of states separated by an energy of 55 to 80 meV regardless of air exposure, while there is only one cluster of emissive states that contributes to the emission reported in the third reference. (ii) In the absence of intentional air exposure, the nonradiative decay from all samples can be described by a single Arrhenius-like process. (iii) Although air-exposure effects are reversible in some samples and irreversible in others, the changes in integrated PL behavior brought about by air-exposure forces the introduction of a common, low-activation-energy nonradiative pathway in all cases. (iv) The low-lying emissive cluster of the two-emissive-cluster samples exhibits behavior similar to the single emissive cluster of the other samples. (v) Many hours of air exposure do not trend either the radiative or nonradiative behavior of the dual-emissive-cluster samples towards the behavior of the single-emissive-cluster samples.

  14. Oxygen separation from air using zirconia solid electrolyte membranes

    NASA Technical Reports Server (NTRS)

    Suitor, J. W.; Marner, W. J.; Schroeder, J. E.; Losey, R. W.; Ferrall, J. F.

    1988-01-01

    Air separation using a zirconia solid electrolyte membrane is a possible alternative source of oxygen. The process of zirconia oxygen separation is reviewed, and an oxygen plant concept using such separation is described. Potential cell designs, stack designs, and testing procedures are examined. Fabrication of the materials used in a zirconia module as well as distribution plate design and fabrication are examined.

  15. 1. LOOKING NORTH AT THE BASIC OXYGEN STEELMAKING PLANT. THE ...

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

    1. LOOKING NORTH AT THE BASIC OXYGEN STEELMAKING PLANT. THE FLUX HANDLING BUILDING IS ON THE RIGHT, THE MOULD CONDITIONING BUILDING IS IN THE CENTER, THE BASIC OXYGEN PROCESS (BOP) SHOP IS IN THE CENTER BACKGROUND, AND OPEN HEARTH No. 2 BUILDING IS ON THE LEFT. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  16. Oxygen separation from air using zirconia solid electrolyte membranes

    NASA Technical Reports Server (NTRS)

    Suitor, J. W.; Marner, W. J.; Schroeder, J. E.; Losey, R. W.; Ferrall, J. F.

    1988-01-01

    Air separation using a zirconia solid electrolyte membrane is a possible alternative source of oxygen. The process of zirconia oxygen separation is reviewed, and an oxygen plant concept using such separation is described. Potential cell designs, stack designs, and testing procedures are examined. Fabrication of the materials used in a zirconia module as well as distribution plate design and fabrication are examined.

  17. Oxygen production by pyrolysis of lunar regolith

    NASA Technical Reports Server (NTRS)

    Senior, Constance L.

    1991-01-01

    Oxygen was identified as the most important product of initial lunar materials processing efforts. A source of oxygen on the Moon provides an alternative to the costly transport of propellant to the Moon or to low earth orbit. Pyrolysis, or vapor-phase reduction, involves heating a feedstock to temperatures sufficient to decompose the constituent metal oxides and release oxygen. The process relies on the vaporization of metal oxides in the form of reduced suboxides or atomic species. The reduced species must then be condensed without re-oxidizing, yielding oxygen in the gas phase. The feasibility of obtaining oxygen from common lunar minerals was demonstrated using solar furnace experiments. These results are discussed together with chemical equilibrium models which were extended to include the multicomponent oxides used in experiments. For the first time, both experiments and theoretical models dealt with the complex oxides that make up potential lunar feedstocks. Two major conclusions are drawn from this preliminary work. First, unbeneficiated regolith is a suitable feedstock for pyrolysis. Second, the process can operate at moderate temperatures, circa 2000 K, which could be supplied by direct solar or electrical energy. In addition to these advantages in choice of feedstock and energy source, the pyrolysis process requires no chemicals or reagents, making it an attractive process for lunar oxygen production.

  18. Oxygen production by pyrolysis of lunar regolith

    NASA Technical Reports Server (NTRS)

    Senior, Constance L.

    1991-01-01

    Oxygen was identified as the most important product of initial lunar materials processing efforts. A source of oxygen on the Moon provides an alternative to the costly transport of propellant to the Moon or to low earth orbit. Pyrolysis, or vapor-phase reduction, involves heating a feedstock to temperatures sufficient to decompose the constituent metal oxides and release oxygen. The process relies on the vaporization of metal oxides in the form of reduced suboxides or atomic species. The reduced species must then be condensed without re-oxidizing, yielding oxygen in the gas phase. The feasibility of obtaining oxygen from common lunar minerals was demonstrated using solar furnace experiments. These results are discussed together with chemical equilibrium models which were extended to include the multicomponent oxides used in experiments. For the first time, both experiments and theoretical models dealt with the complex oxides that make up potential lunar feedstocks. Two major conclusions are drawn from this preliminary work. First, unbeneficiated regolith is a suitable feedstock for pyrolysis. Second, the process can operate at moderate temperatures, circa 2000 K, which could be supplied by direct solar or electrical energy. In addition to these advantages in choice of feedstock and energy source, the pyrolysis process requires no chemicals or reagents, making it an attractive process for lunar oxygen production.

  19. Additively Manufactured Metals in Oxygen Systems Project

    NASA Technical Reports Server (NTRS)

    Tylka, Jonathan

    2015-01-01

    Metals produced by additive manufacturing methods, such as Powder Bed Fusion Technology, are now mature enough to be considered for qualification in human spaceflight oxygen systems. The mechanical properties of metals produced through AM processes are being systematically studied. However, it is unknown whether AM metals in oxygen applications may present an increased risk of flammability or ignition as compared to wrought metals of the same metallurgical composition due to increased porosity. Per NASA-STD-6001B materials to be used in oxygen system applications shall be based on flammability and combustion test data, followed by a flammability assessment. Without systematic flammability and ignition testing in oxygen there is no credible method for NASA to accurately evaluate the risk of using AM metals in oxygen systems.

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

    DTIC Science & Technology

    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

  1. Oxygen sensitive paper

    NASA Technical Reports Server (NTRS)

    Whidby, J. F.

    1973-01-01

    Paper is impregnated with mixture of methylene blue and ethylenediaminetetraacetic acid. Methylene blue is photo-reduced to leuco-form. Paper is kept isolated from oxygen until ready for use. Paper can be reused by photo-reduction after oxygen exposure.

  2. Hyperbaric Oxygen Therapy

    MedlinePlus

    ... treated with hyperbaric oxygen therapy include serious infections, bubbles of air in your blood vessels, and wounds that won't heal as a result of diabetes or radiation injury. In a hyperbaric oxygen therapy chamber, the air pressure is increased to three times ...

  3. Aircrew oxygen system

    NASA Technical Reports Server (NTRS)

    Babinsky, A. D.; Kiraly, R. J.; Wynveen, R. A.

    1972-01-01

    Closed-loop rebreather system which includes pilot provides oxygen for use in aircraft by safe, reliable method of low weight and size and reduces expense of ground equipment. Water electrolysis generated oxygen is fed into rebreather loop which allows nitrogen elimination and water and carbon dioxide removal.

  4. Durability of oxygen sensors

    NASA Astrophysics Data System (ADS)

    Snapp, L.

    1985-03-01

    This report describes the results of dynamometer and vehicle durability testing from a variety of sources, as well as common causes of failure for oxygen sensors. The data indicates that oxygen sensors show low failure rates, even at mileages of 80,000 miles and beyond.

  5. How plasma induced oxidation, oxygenation, and de-oxygenation influences viability of skin cells

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Strudwick, Xanthe; Short, Robert D.; Ogawa, Kotaro; Hatta, Akimitsu; Furuta, Hiroshi; Gaur, Nishtha; Hong, Sung-Ha; Cowin, Allison J.; Fukuhara, Hideo; Inoue, Keiji; Ito, Masafumi; Charles, Christine; Boswell, Roderick W.; Bradley, James W.; Graves, David B.; Szili, Endre J.

    2016-11-01

    The effect of oxidation, oxygenation, and de-oxygenation arising from He gas jet and He plasma jet treatments on the viability of skin cells cultured in vitro has been investigated. He gas jet treatment de-oxygenated cell culture medium in a process referred to as "sparging." He plasma jet treatments oxidized, as well as oxygenated or de-oxygenated cell culture medium depending on the dissolved oxygen concentration at the time of treatment. He gas and plasma jets were shown to have beneficial or deleterious effects on skin cells depending on the concentration of dissolved oxygen and other oxidative molecules at the time of treatment. Different combinations of treatments with He gas and plasma jets can be used to modulate the concentrations of dissolved oxygen and other oxidative molecules to influence cell viability. This study highlights the importance of a priori knowledge of the concentration of dissolved oxygen at the time of plasma jet treatment, given the potential for significant impact on the biological or medical outcome. Monitoring and controlling the dynamic changes in dissolved oxygen is essential in order to develop effective strategies for the use of cold atmospheric plasma jets in biology and medicine.

  6. Atomic Oxygen Textured Polymers

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Hunt, Jason D.; Drobotij, Erin; Cales, Michael R.; Cantrell, Gidget

    1995-01-01

    Atomic oxygen can be used to microscopically alter the surface morphology of polymeric materials in space or in ground laboratory facilities. For polymeric materials whose sole oxidation products are volatile species, directed atomic oxygen reactions produce surfaces of microscopic cones. However, isotropic atomic oxygen exposure results in polymer surfaces covered with lower aspect ratio sharp-edged craters. Isotropic atomic oxygen plasma exposure of polymers typically causes a significant decrease in water contact angle as well as altered coefficient of static friction. Such surface alterations may be of benefit for industrial and biomedical applications. The results of atomic oxygen plasma exposure of thirty-three (33) different polymers are presented, including typical morphology changes, effects on water contact angle, and coefficient of static friction.

  7. A new oxygen prescription produces real improvements in therapeutic oxygen use

    PubMed Central

    Rudge, James; Odedra, Sunita; Harrison, Danielle

    2014-01-01

    In the UK, safe use and administration of oxygen therapy was unsatisfactory prior to the implementation of national guidelines in 2008. Each year since then the British Thoracic Society (BTS) has conducted a national audit that has demonstrated a slow but steady improvement in oxygen use across four key standards. Sandwell and West Birmingham NHS Hospitals Trust has participated in this audit process but has failed to show consistent improvements. The aim of this quality improvement project was to produce meaningful and sustained improvements in oxygen use across each of the four standards. Four interventions were developed over three PDSA cycles and included: 1. a new oxygen prescription chart, 2. oxygen ‘alert’ stickers for use on drug and MEWS charts, 3. point of care resources, and 4. senior led educational sessions for healthcare staff. Each intervention was tested on the Acute Medical Unit over seven days and data collected using the BTS data collection form. The QIP improved oxygen use across each of the standards: baseline measurement for standard one demonstrated that 55% of patients using oxygen had a valid oxygen prescription, improving to 94% after PDSA cycle three. For standard two, baseline measurement demonstrated that 50% of patients had a documented oxygen target saturation range, improving to 94% after PDSA cycle three. For standard three, baseline measurement demonstrated that 84% patients using oxygen had saturations documented on the MEWS chart, improving to 100% after PDSA cycle three. Finally, baseline measurement of standard four demonstrated that 0% patients with a valid oxygen prescription had it signed for at drugs rounds, improving to 18% after PDSA cycle three. Oxygen use was substantially improved during the QIP. Following engagement with stakeholders a new oxygen prescription will be rolled out within the Trust with projected annual savings of £30,400. PMID:26734309

  8. Atomic Oxygen Fluence Monitor

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.

    2011-01-01

    This innovation enables a means for actively measuring atomic oxygen fluence (accumulated atoms of atomic oxygen per area) that has impinged upon spacecraft surfaces. Telemetered data from the device provides spacecraft designers, researchers, and mission managers with real-time measurement of atomic oxygen fluence, which is useful for prediction of the durability of spacecraft materials and components. The innovation is a compact fluence measuring device that allows in-space measurement and transmittance of measured atomic oxygen fluence as a function of time based on atomic oxygen erosion yields (the erosion yield of a material is the volume of material that is oxidized per incident oxygen atom) of materials that have been measured in low Earth orbit. It has a linear electrical response to atomic oxygen fluence, and is capable of measuring high atomic oxygen fluences (up to >10(exp 22) atoms/sq cm), which are representative of multi-year low-Earth orbital missions (such as the International Space Station). The durability or remaining structural lifetime of solar arrays that consist of polymer blankets on which the solar cells are attached can be predicted if one knows the atomic oxygen fluence that the solar array blanket has been exposed to. In addition, numerous organizations that launch space experiments into low-Earth orbit want to know the accumulated atomic oxygen fluence that their materials or components have been exposed to. The device is based on the erosion yield of pyrolytic graphite. It uses two 12deg inclined wedges of graphite that are over a grit-blasted fused silica window covering a photodiode. As the wedges erode, a greater area of solar illumination reaches the photodiode. A reference photodiode is also used that receives unobstructed solar illumination and is oriented in the same direction as the pyrolytic graphite covered photodiode. The short-circuit current from the photodiodes is measured and either sent to an onboard data logger, or

  9. Acceleration of the aging process by oxygen

    NASA Technical Reports Server (NTRS)

    Miquel, J.; Lunderen, P. R.; Bensch, K. G.

    1975-01-01

    Tissue changes induced by hyperoxia have been compared with those of normal aging. Results of investigations using male flies prompt conclusion that normal aging, radiation syndrome, and hyperoxic injury share at least one common feature--lipid peroxidation damage to all mambranes resulting in accumulation of age pigment.

  10. Discharge Processes in the Oxygen Plasma

    DTIC Science & Technology

    1981-04-01

    oJ -k .* I L1La 86 •t-,; out put was :oniWected to one inl1lUt 0’[ a different.i.al am- 1) liit or. ’ rOhe reflected oneorqy froem the cavity was...of Chemco with experiments and with electron current continuity calcula- tions. The experimental results were obtained from the mi - crowave cavity...4 08 0 195 40i 60 mi 80mi i at high E/N values. The 03 density was calculated to be several orders of magnitude lower than that of the other neutral

  11. Atomic Oxygen Cleaning of Unpainted Plaster Sculptures

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Miller, Sharon K.

    2017-01-01

    Atomic oxygen erosion of polymers has been found to be a threat to spacecraft in low Earth orbit. As a result ground facilities have been developed to identify coatings to protect polymers such as used for solar array blankets. As a result of extensive laboratory testing, it was discovered that soot and other organic contamination on paintings could be readily removed by atomic oxygen interactions with minimal damage to the artwork. No method, other than dusting, has been found to be effective in the cleaning of unpainted plaster sculptures This presentation discusses the atomic oxygen interaction processes and how effective they are for cleaning soot damaged unpainted plaster sculptures.

  12. Oxygen Transport Ceramic Membranes

    SciTech Connect

    S. Bandopadhyay; N. Nagabhushana; X.-D Zhou; Q. Cai; J. Yang; W.B. Yelon; W.J. James; H.U. Anderson; Alan Jacobson; C.A. Mims

    2004-10-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In this report, Moessbauer spectroscopy was used to study the local environmentals of LSFT with various level of oxygen deficiency. Ionic valence state, magnetic interaction and influence of Ti on superexchange are discussed Stable crack growth studies on Dense OTM bars provided by Praxair were done at elevated temperature, pressure and elevated conditions. Post-fracture X-ray data of the OTM fractured at 1000 C in environment were refined by FullProf code and results indicate a distortion of the parent cubic perovskite to orthorhombic structure with reduced symmetry. TGA-DTA studies on the post-fracture samples also indicated residual effect arising from the thermal and stress history of the samples. An electrochemical cell has been designed and built for measurements of the Seebeck coefficient as a function of temperature and pressure. The initial measurements on La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-{delta}} are reported. Neutron diffraction measurements of the same composition are in agreement with both the stoichiometry and the kinetic behavior observed in coulometric titration measurements. A series of isotope transients under air separation mode (small gradient) were completed on the membrane of LSCrF-2828 at 900 C. Low pO{sub 2} atmospheres based on with CO-CO{sub 2} mixtures have also been admitted to the delivery side of the LSCrF-2828 membrane to produce the gradients which exist under syngas generation conditions. The COCO{sub 2} mixtures have normal isotopic {sup 18}O abundances. The evolution of {sup 18}O on the delivery side in these experiments after an {sup 18}O pulse on the air side reveals a wealth of information about the oxygen transport processes.

  13. Kinetics of oxygen species in an electrically driven singlet oxygen generator

    NASA Astrophysics Data System (ADS)

    Azyazov, V. N.; Torbin, A. P.; Pershin, A. A.; Mikheyev, P. A.; Heaven, M. C.

    2015-12-01

    The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O3(υ) formed in O + O2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O2(a1Δ), oxygen atom removal and ozone formation. It is shown that the process O3(υ ⩾ 2) + O2(a1Δ) → 2O2 + O is the main O2(a1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O2(a1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

  14. Oxygenated kidney preservation techniques.

    PubMed

    Hosgood, Sarah A; Nicholson, Harriet F L; Nicholson, Michael L

    2012-03-15

    Improving preservation techniques to minimize injury is of particular importance in organs from marginal donors. Since the introduction of transplantation and routine use of hypothermic temperatures for kidney preservation, there has been much debate on whether it is necessary to add oxygen to support the low level of metabolism under these conditions. Supplementing the kidney with oxygen during hypothermic preservation is not common practice. However, there is evidence to support its application. Oxygen can be added by various techniques such as retrograde persufflation whereby filtered and humidified oxygen is bubbled through the vasculature; under hyperbaric conditions using specialized pressurized chambers; during hypothermic machine perfusion; with the addition of oxygen carriers; and under normothermic conditions. Evidence suggests that oxygenation is particularly beneficial in restoring cellular levels of adenosine triphosphate after kidneys have been subjected to warm or cold ischemic injury. However, under normal conditions, the benefits are less convincing, but the evidence is insufficient to draw any conclusions. This overview explores the ways in which oxygen can be administered during preservation in experimental and clinical models of kidney transplantation.

  15. Oxygen foreshock of Mars

    NASA Astrophysics Data System (ADS)

    Yamauchi, M.; Lundin, R.; Frahm, R. A.; Sauvaud, J.-A.; Holmström, M.; Barabash, S.

    2015-12-01

    Mars Express (MEX) has operated for more than 10 years in the environment of Mars, providing solar wind ion observations from the Analyzer of Space Plasmas and Energetic Atoms experiment's Ion Mass Analyser (IMA). On 21 September 2008, MEX/IMA detected foreshock-like discrete distributions of oxygen ions at around 1 keV in the solar wind attached to the bow shock and this distribution was observed continuously up to more than 2000 km from the bow shock. Foreshock-like protons are also observed but at a shifted location from the oxygen by about 1000 km, at a slightly higher energy, and flowing in a slightly different direction than the oxygen ions. Both protons and oxygen ions are flowing anti-sunward at different angles with respect to the solar wind direction. This is the first time that a substantial amount of planetary oxygen is observed upstream of the bow shock. Although rare, this is not the only IMA observation of foreshock-like oxygen: oxygen ions are sometimes observed for a short period of time (<5 min) inside the foreshock region. These observations suggest a new escape channel for planetary ions through the acceleration in the bow shock-magnetosheath region.

  16. Synthetic carriers of oxygen.

    PubMed

    Dellacherie, E; Labrude, P; Vigneron, C; Riess, J G

    1987-01-01

    During the last decade, construction of artificial carriers of oxygen for transfusion purposes has evolved in three main directions, which can be reviewed as follows. The first approach consists of modifying hemoglobin (Hb), the natural oxygen carrier, in order to lower its oxygen affinity and increase its intravascular persistence. To achieve this aim, two basic procedures have been used: molecular and environmental modification. In the first case, Hb is modified with chemical reagents; the second requires encapsulation of Hb to obtain artificial erythrocytes. The second approach is based on the use of synthetic oxygen-carrying chelates that mimic the oxygenation function of Hb. The main products in this class are metalloporphyrins, whose chemical environment is designed to render them efficient as reversible carriers of oxygen in vivo. Finally, the third approach deals with the perfluorochemicals used in emulsified form. Perfluorochemical liquids are excellent gas solvents, but some problems remain unsolved with regard to their development as oxygen carriers in vivo: low O2 dissolving capacity, toxicity, and excretion.

  17. Electrochemical oxygen concentrator as an oxygen compressor

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A solid polymer electrolyte (SPE) oxygen compressor is described which generates pressures of 3000 psi. The SPE is a cation exchange membrane with chemical compatibility, and has the capability of withstanding 5000 psi. Other features of the compressor described include: gasketless sealing, porus plate cell supports, and conductive cooling. Results are presented of a computer program which defines the power of the system as a function of density, temperature, pressure, membrane thickness, and water content.

  18. OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL

    SciTech Connect

    David R. Thompson; Lawrence E. Bool; Jack C. Chen

    2004-04-01

    Conventional wisdom says adding oxygen to a combustion system enhances product throughput, system efficiency, and, unless special care is taken, increases NOx emissions. This increase in NOx emissions is typically due to elevated flame temperatures associated with oxygen use leading to added thermal NOx formation. Innovative low flame temperature oxy-fuel burner designs have been developed and commercialized to minimize both thermal and fuel NOx formation for gas and oil fired industrial furnaces. To be effective these systems require close to 100% oxy-fuel combustion and the cost of oxygen is paid for by fuel savings and other benefits. For applications to coal-fired utility boilers at the current cost of oxygen, however, it is not economically feasible to use 100% oxygen for NOx control. In spite of this conventional wisdom, Praxair and its team members, in partnership with the US Department of Energy National Energy Technology Laboratory, have developed a novel way to use oxygen to reduce NOx emissions without resorting to complete oxy-fuel conversion. In this concept oxygen is added to the combustion process to enhance operation of a low NOx combustion system. Only a small fraction of combustion air is replaced with oxygen in the process. By selectively adding oxygen to a low NOx combustion system it is possible to reduce NOx emissions from nitrogen-containing fuels, including pulverized coal, while improving combustion characteristics such as unburned carbon. A combination of experimental work and modeling was used to define how well oxygen enhanced combustion could reduce NOx emissions. The results of this work suggest that small amounts of oxygen replacement can reduce the NOx emissions as compared to the air-alone system. NOx emissions significantly below 0.15 lbs/MMBtu were measured. Oxygen addition was also shown to reduce carbon in ash. Comparison of the costs of using oxygen for NOx control against competing technologies, such as SCR, show that this

  19. Method for producing oxygen from lunar materials

    NASA Technical Reports Server (NTRS)

    Sullivan, Thomas A. (Inventor)

    1993-01-01

    This invention is related to producing oxygen from lunar or Martian materials, particularly from lunar ilmenite in situ. The process includes producing a slurry of the minerals and hot sulfuric acid, the acid and minerals reacting to form sulfates of the metal. Water is added to the slurry to dissolve the minerals into an aqueous solution, the first aqueous solution is separated from unreacted minerals from the slurry, and the aqueous solution is electrolyzed to produce the metal and oxygen.

  20. Enhanced Glow Discharge Production of Oxygen

    NASA Technical Reports Server (NTRS)

    Ash, Robert; Zhong, Shi

    1998-01-01

    Studies starting in late seventies have shown Mars atmosphere can be used as a feedstock for oxygen production using simple chemical processing systems during early phases of the Mars exploration program. This approach has been recognized as one of the most important in-situ resource utilization (ISRU) concepts for enabling future round trip Mars missions. It was determined a decade ago that separation of oxygen can be accomplished efficiently by permeation through a silver membrane at temperatures well below 1000 K. This process involves adsorption of atomic oxygen on the surface and its subsequent diffusion through a silver lattice via an oxygen concentration gradient. We have determined recently that glow discharge can be used to liberate atomic oxygen from Mars atmosphere and that the oxygen can be collected through a silver permeation membrane. Recently, we demonstrated a substantial increase in energy efficiency of the process by applying a radio frequency discharge in combination with a silver permeation membrane. The experiments were performed using pure carbon dioxide in the pressure range equal to Mars surface conditions. Energy efficiency was defined as the ratio of the energy required to dissociate a unit mass of oxygen from carbon dioxide to the (electrical) energy consumed by the overall system during the dissociation and collection process. The research effort, started at NASA Langley Research Center, continued with this project. Oxygen production apparatus, built and operated under the research grant NAG1-1140 was relocated to the Atomic Beams Laboratory at ODU in July 1996, being since then in fall operation.